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  • 1995-1999  (31)
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  • Genetics
  • 1
    ISSN: 1530-0358
    Keywords: Colorectal neoplasms ; Genetics ; K-ras ; Gene mutations ; Early diagnosis ; Polymerase chain reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Best chances of a cure from colorectal cancer are obtained before metastatic spread. Lack of specific tests allowing early diagnosis of the tumor accounts for investigation of gene alterations involved in carcinogenesis by a noninvasive method. In the present study, K-ras codons 12 and 13 mutations were studied in neoplastic cells shed from the bowel into the stool and those contained in the tumor and normal mucosa. Moreover, healthy patients and a few others with precancerous conditions were examined. METHODS: Stool, tumor, and mucosa samples were taken from 25 patients with colorectal adenocarcinoma. Stool and mucosa samples were obtained from 11 healthy patients, and stool, pathologic bowel tissue, and normal mucosa samples were obtained from 3 patients with adenoma (1) or ulcerative colitis (2). Polymerase chain reaction amplification and restriction enzyme analysis were performed. RESULTS: K-ras codon 12 mutations were detected in both tumor and stool samples of 10 cancer patients, and no gene alterations were observed in 14 patients. In one patient with a tumor, a mutation was shown in only the tumor tissue. The agreement rate in tumor and stool analysis was 96 percent. A normal pattern of K-ras codons 12 and 13 was observed in the bowel mucosa. All stool and mucosa samples from healthy patients were not altered in K-ras.Agreement was registered between samples taken from patients with preneoplastic lesions. CONCLUSIONS: These preliminary findings show a high rate of accuracy in the investigation of K-ras alterations in the colorectal cells shed into the feces, suggesting that such an approach could be used to study other gene alterations and, prospectively, to identify early colorectal cancers.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1437-160X
    Keywords: SLE ; Apoptosis ; bcl-2 gene ; Susceptibility ; Linkage ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Systemic lupus erythematosus (SLE) is an autoimmune disease characterised by the production of a large number of autoantibodies. It has been postulated that this may be the result of prolonged longevity of auto-reactive B cells due to defective regulation of programmed cell death (apoptosis). The proto-oncogenebcl-2 is involved in the control of apoptosis in immunocompetent cells, and its over-expression is noted in T and B cells from SLE patients. This study examined the genetic linkage between thebcl-2 gene locus and SLE susceptibility using the affected sib-pair method in SLE families. Seventeen caucasian multiplex families were evaluated. A polymorphic microsatellite marker closely linked to thebcl-2 gene on 18g21.3 was used to determine thebcl-2 genotype. We demonstrated that haplotype sharing among the affected sibling pairs was not statistically different from random (P〉0.5). This suggests that thebcl-2 gene locus does not confer a genetic susceptibility to SLE expression.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 74 (1996), S. 515-521 
    ISSN: 1432-1440
    Keywords: Emotionality ; Behaviour ; Genetics ; Animal models ; QTL analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It seems that the genetic basis of common psychiatric diseases such as schizophrenia and manic-depressive psychosis is amenable to the genetic mapping strategies that have been successful in other complex disorders such as diabetes. The next challenge is the genetic dissection of quantitative behavioural traits such as mood, personality and intelligence. Quantitative traits pose new problems for gene cloning experiments. We argue that one way forward is by using animal models. One of the features of quantitative traits is that the DNA sequence variants which are responsible for them are unlikely to be immediately recognizable. In contrast to many qualitative traits where a discrete phenotypic difference is often the consequence of an inactivating mutation, the allelic variation responsible for quantitative traits probably has a more subtle basis. This distinction means that strategies to clone the genetic basis of quantitative behavioural traits will have to rely on functional assays of alleles thought to be important in determining the phenotype. We suggest that an efficient strategy for detecting sequences that give rise to quantitative behavioural traits can be devised in the mouse. The importance and utility of the mouse for quantitative trait analysis make it worthwhile to investigate mouse models of human behaviour; these advantages outweigh the difficulties that arise in attempts to validate the animal models. As an example we review the evidence that validates rodent emotionality as an animal model for susceptibility to human anxiety. We show that there is good evidence that rodent emotionality is a central nervous system state with a genetic basis, and that there are neuropharmacological and neuroanatomical parallels with human anxiety. Furthermore, our own work has shown that the genetic basis of the trait is relatively simple, and that the task of characterizing it at a molecular level is feasible. We expect that future experiments will show us how genetic variation gives rise to quantitative behavioural traits.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 74 (1996), S. 515-521 
    ISSN: 1432-1440
    Keywords: Key words Emotionality ; Behaviour ; Genetics ; Animal models ; QTL analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  It seems that the genetic basis of common psychiatric diseases such as schizophrenia and manic-depressive psychosis is amenable to the genetic mapping strategies that have been successful in other complex disorders such as diabetes. The next challenge is the genetic dissection of quantitative behavioural traits such as mood, personality and intelligence. Quantitative traits pose new problems for gene cloning experiments. We argue that one way forward is by using animal models. One of the features of quantitative traits is that the DNA sequence variants which are responsible for them are unlikely to be immediately recognizable. In contrast to many qualitative traits where a discrete phenotypic difference is often the consequence of an inactivating mutation, the allelic variation responsible for quantitative traits probably has a more subtle basis. This distinction means that strategies to clone the genetic basis of quantitative behavioural traits will have to rely on functional assays of alleles thought to be important in determining the phenotype. We suggest that an efficient strategy for detecting sequences that give rise to quantitative behavioural traits can be devised in the mouse. The importance and utility of the mouse for quantitative trait analysis make it worthwhile to investigate mouse models of human behaviour; these advantages outweigh the difficulties that arise in attempts to validate the animal models. As an example we review the evidence that validates rodent emotionality as an animal model for susceptibility to human anxiety. We show that there is good evidence that rodent emotionality is a central nervous system state with a genetic basis, and that there are neuropharmacological and neuroanatomical parallels with human anxiety. Furthermore, our own work has shown that the genetic basis of the trait is relatively simple, and that the task of characterizing it at a molecular level is feasible. We expect that future experiments will show us how genetic variation gives rise to quantitative behavioural traits.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Der Nervenarzt 67 (1996), S. 837-845 
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Migräne ; Genetik ; Familiäre Hemiplegische Migräne ; Linkageanalyse ; Zwillingsstudien ; Assoziationsstudien ; Key words Migraine ; Familial Hemiplegic Migraine ; Genetics ; Linkage analysis ; Twin studies ; Association studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Several historical reports focusing on the heredity of migraine, as well as recent studies on its epidemiology and molecular biology, have revealed evidence for a decisive role of genetic factors in the aetiopathogenesis of familial migraine. Indeed, family studies, segregation analyses and twin studies have shown that genetic factors play an important role in disposition towards migraine but could not explain the entire aetiopathogenesis. The influence of extragenetic factors, however, remains mostly unknown. Recent linkage analyses have provided evidence for genetic heterogeneity. A locus for Familial Hemiplegic Migraine (FHM), the only known type of migraine that follows autosomal-dominant transmission, has been linked to chromosome 19p13 but genetic heterogeneity has also been shown, i. e. different types of migraine could be excluded from this locus. Further investigations should concentrate on identifying the FHM gene on chromosome 19p13, on linkage analyses with markers for different susceptibility genes, and on genomic analyses of highly informative pedigrees. This would lead to further clues to the pathogenesis underlying migraine and, thus, to therapeutic developments.
    Notes: Zusammenfassung Nachdem bereits in historischen Beschreibungen eine genetische Verursachung der Migräne vermutet worden war, haben epidemiologische und molekularbiologische Forschungen in den letzten Jahren differenzierte Ergebnisse über genetische Faktoren in der Ätiopathogenese der familiären Migräne geliefert. Aufgrund von Familien- und Segregationsanalysen und von Zwillingsstudien wird dargestellt, daß genetische Faktoren mit größter Wahrscheinlichkeit eine Rolle in der Pathogenese der typischen Migräne spielen. Inwieweit extragenetische Faktoren auf die Ätiopathogenese der Migräne Einfluß nehmen, ist weitgehend offen. Linkageanalysen haben in jüngster Zeit gezeigt, daß möglicherweise mehrere verschiedene Gene für diese Erkrankung verantwortlich sind. Für die Familiäre Hemiplegische Migräne (FHM), der einzigen Migräneform, für die ein autosomal-dominanter Erbgang nachgewiesen ist, konnte ein Genlocus auf Chromosom 19p13 gefunden werden, gleichzeitig wurde aber auch genetische Heterogenität nachgewiesen. Verschiedene andere Formen der Migräne zeigten keine Linkage zu diesem Locus. Weitere Forschungen sollten neben der Identifizierung des FHM-Gens auch Linkageanalysen für Kandidatengene und Genomanalysen an großen informativen Familien zum Ziel haben. Letztlich werden die Ergebnisse genaueren Einblick in die Pathophysiologie der Migräne liefern und damit therapeutisch relevant sein.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1433-2965
    Keywords: Bone density ; Femor geometry ; Genetics ; Twins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To estimate genetic effects on femoral neck geometry and the distribution of bone mineral within the proximal femur a cross-sectional twin analysis was carried out at a university hospital that compared correlations in these traits in pairs of mono- and dizygo-tic female twins. Monozygotic (MZ, n=51 pairs, age 49.1±9.3 years) and dizygotic (DZ, n=26 pairs, age 45.7±11.3 years) twins were randomly selected from a larger sample of twins previously studied. Measurements of bone mineral density (BMD), femoral neck angles and length, cross-sectional area and moment of interia, the center of mass of the narrowest cross-section of the femoral neck, and BMDs of regions within the femoral neck were made. A summary index of the resistance of the femoral neck to forces experienced in a fall with impact on the greater trochanter (Fall Index, FI) was calculated. MZ pair intraclass correlations (rMZ) were significantly (p〈0.05) different from zero for all bone mass and femoral geometry variables (0.35〈rMZ〈0.82). DZ pair correlations (rDZ) were lower thanrMZ for all variables (0.04〈rDZ〈0.52) except femoral neck length (rDZ=0.38, rMZ=0.36). After adjustment for BMD of the femoral neck,rMZ was significantly greater thanrDZ, yielding high heritability estimates for regional BMDs (0.72〈H 2〈0.78), the center of mass of the femoral neck (H 2=0.70, −0.04 to 1.43 95% CI) and the resistance of the femoral neck to forces experienced in a fall (FI,H 2=0.94, 0.06 to 1.85 95% CI), but not for femoral neck length. Adjustments for age did not alter these findings. It is concluded that there are significant familial influences on the distribution of femoral bone mass and on the calculated structural strength of the proximal femur, but not on femoral neck length. If the assumptions of the twin model are correct, this is evidence for genetic factors influencing these traits.
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  • 7
    ISSN: 1573-0905
    Keywords: Differential diagnosis ; Etiology ; Genetics ; Mathematics performance ; Reading disability ; Twins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Education
    Notes: Abstract In order to assess the etiology of reading disability as a function of mathematics performance, data from 168 monozygotic (MZ) and 127 same-sex dizygotic (DZ) twin pairs in which at least one member of each pair was reading-disabled were subjected to quantitative genetic analyses. MZ and DZ concordance rates for reading disability were computed for different levels of mathematics performance, and reading performance data were fitted to an extension of the basic multiple regression model for the analysis of selected twin data. Results of these analyses suggest that genetic factors may be especially salient as a cause of reading disability in children with borderline deficits in mathematics performance: thus, mathematics performance may be a valid dimension for diagnosing subtypes of reading disability.
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  • 8
    ISSN: 1432-0533
    Keywords: Key words Alzheimer’s disease ; Clinicopathological ; correlations ; Early-onset dementia ; Genetics ; Pick’s ; disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 39 (1996), S. 375-382 
    ISSN: 1432-0428
    Keywords: Genetics ; maternally inherited diabetes and deafness ; NIDDM ; IDDM ; mitochondria ; MELAS syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Diabetes mellitus is a common disease with many forms of clinical expression. In addition, the development of diabetic complications is not only dependent on glycaemic control but also on individual factors which may be related to genetic heterogeneity. At present, multiple genetic factors are being recognized as contributing to the development of diabetes or possibly modulating its clinical expression. The purpose of this review is to give an overview of our current knowledge on a subtype of diabetes which is apparently caused by a single mutation in the mitochondrial DNA.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 108 (1996), S. 419-423 
    ISSN: 1432-1939
    Keywords: Barnyard grass ; Seed dormancy ; Geographic variation ; Genetics ; Ecophysiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In 1991–1993, we investigated the incidence of seed dormancy in 25 local populations of barnyard grass, Echinochloa crus-galli (L.) P.Beauv., in the western Czech Republic. The percentage of germination after 4 months afterripening of dry seeds at 25°C varied between 0.0 and 83.6%. Although there were significant annual differences in the percentage of germination at some localities, typical proportions of dormant seeds persisted over 3 years at field sites where the seed bank was not disturbed. One-way ANOVA (using data from 14 cultivated or abandoned fields) revealed that 73.0% of variance in seed dormancy incidence could be attributed to the effect of locality (P〈0.001). Incidence of dormancy was not correlated with mother plant stature (dry above-ground biomass, number of tillers, maximal stem height) nor seed mass. There was a significant correlation (r 2=0.403, P〈0.005) between dormancy incidence at natural localities in 1991 and in F1 offspring sown at experimental grounds at Praha-Ruzyně in 1992. The results indicate that heredity is important in maintaining local variation in seed dormancy, probably favoured by the self-pollinating reproduction of barnyard grass.
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  • 11
    ISSN: 1432-1920
    Keywords: Key words Myotonic dystrophy ; Magnetic resonance imaging ; Brain ; Muscles ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Amplification of an unstable CTG trinucleotide repeat sequence in a protein kinase gene on chromosome 19 has recently been recognised as the molecular basis of myotonic dystrophy (DM), a multisystem disorder with a wide spectrum of muscular and extramuscular manifestations. The CTG expansion of 40 patients was assessed by direct genotype analysis of the white blood cell DNA and correlated with MRI of the brain and muscles, and with functional clinical data. Cerebral pathology on MRI consisted of diffuse atrophy (68 %), subcortical white matter lesions (65 %), wide Virchow-Robin spaces (38 %) and thickening of the skull (35 %). Cerebral atrophy and extent of white matter disease correlated significantly with mental retardation, duration of disease and CTG fragment amplification. MRI of the muscular system showed fatty degeneration of different degrees in neighbouring muscles causing a mosaic pattern of the thigh in 38 % and the calf in 44 %. Muscular changes on MRI were strongly correlated with muscular impairment but less strongly with CTG expansion. Changes on MRI reflect the stage of development of tissue pathology in DM, modified by defect of the DM gene. Pathology on MRI is strongly correlated with functional deficits.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 155 (1996), S. 540-544 
    ISSN: 1432-1076
    Keywords: Key words Amyloidosis ; Arab ; children ; Familial Mediterranean ; fever ; Genetics ; Recurrent ; abdominal pain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Over a period of 3 years, 192 children with familial Mediterranean fever were prospectively studied. Of these, 106 (55%) were girls and 86 (45%) were boys. The prevalence was 1 : 2600 children with a gene frequency of 1 : 50. The age at onset ranged between 4 months and 16 years. Of these patients 24% started their illness below the age of 2 years and 88% were symptomatic before the age of 10 years; 82% had recurrent abdominal pain, 43% had pleurisy, 37% had arthritis, 15% had cutaneous manifestations, 12% had splenomegaly and 4% had hepatomegaly. The presenting symptoms were abdominal pain in 51%, unilateral chest pain in 23% and arthritis in 26%. The family history was positive in 62%. Of 12 affected families 19 members had/have renal failure and amyloidosis was confirmed in 7 patients. Conclusion Our data show a high prevalence of familial Mediterranean fever and a high gene frequency in Arab children similar to that reported in Jews and Armenians.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 155 (1996), S. 540-544 
    ISSN: 1432-1076
    Keywords: Amyloidosis ; Arab children ; Familial Mediterranean fever ; Genetics ; Recurrent abdominal pain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Over a period of 3 years, 192 children with familial Mediterranean fever were prospectively studied. Of these, 106 (55%) were girls and 86 (45%) were boys. The prevalence was 1∶2600 children with a gene frequency of 1∶50. The age at onset ranged between 4 months and 16 years. Of these patients 24% started their illness below the age of 2 years and 88% were symptomatic before the age of 10 years: 82% had recurrent abdominal pain, 43% had pleurisy, 37% had arthritis, 15% had cutaneous manifestations, 12% had splenomegaly and 4% had hepatomegaly. The presenting symptoms were abdominal pain in 51%, unilateral chest pain in 23% and arthritis in 26%. The family history was positive in 62%. Of 12 affected families 19 members had/have renal failure and amyloidosis was confirmed in 7 patients.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 124 (1996), S. 332-339 
    ISSN: 1432-2072
    Keywords: Nicotine ; Genetics ; Self-administration ; Reinforcement ; Seizures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Inbred mouse strains differ in sensitivity to a first dose of nicotine and in the development of tolerance to nicotine. The experiments reported here used six inbred mouse strains (A, BUB, C3H, C57BL/6, DBA/2, ST/b) that differ in sensitivity to an acute challenge dose of nicotine to determine whether differences in oral self-selection of nicotine exist. Animals were presented with solutions containing nicotine or vehicle (water or 0.2% saccharin) and their daily intake of the two fluids was measured for 4 days starting with a 10 µg/ml nicotine solution. This was followed by sequential 4-day testing with 20, 35, 50, 65, 80, 100, 125, 160, and 200 µg/ml nicotine solutions. The strains differed dramatically in their self-selection of nicotine and in maximal daily dose (mg/kg); the rank order of the strains was C57BL/6〉DBA〉BUB〉A≥C3H≥ST/b for both the tap water and 0.2% saccharin choice experiments. Correlations between nicotine consumption and sensitivity to nicotine, as measured by a battery of behavioral and physiological responses, were also calculated. Strain differences in nicotine intake were highly correlated with senstivity to nicotine-induced seizures. As senstivity to nicotine-in-duced seizures increases, oral self-selection of nicotine decreases. This finding may suggest that this toxic action of nicotine serves to limit intake.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    European archives of psychiatry and clinical neuroscience 246 (1996), S. 175-181 
    ISSN: 1433-8491
    Keywords: Schizophrenia ; Genetics ; Liability ; Vulnerability ; Eye-tracking dysfunction ; Eye movements ; Smooth-pursuit eye movements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract There is increasing evidence that the genetic predisposition for schizophrenia in families affects more individuals than those fulfilling the criteria for schizophrenia. This finding is supposed to be one of the major problems in molecular genetic schizophrenia research, especially when linkage studies are employed. Eye-tracking dysfunction (ETD), which is conceived as a possible phenotypic marker for genetic liability to schizophrenia, may offer considerable advantages. However, there is only little information from families with multiple occurrence of schizophrenia. It is still unclear whether in these families ETD aggregates with diagnoses from the schizophrenia spectrum. This first report from an ongoing study presents the results of 48 individuals from 6 multiplex families. Smooth-pursuit eye movements were recorded by infrared reflectometry and assessed by quantitative measurement techniques. Along with the high degree of psychiatric morbidity in these families, in 56.3% of the individuals ETD was assessed. Reduced mean pursuit gain was present in 39.6%. The distribution of eye-tracking dysfunction resembles the distribution of schizophrenia-related psychiatry morbidity.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Acta diabetologica 33 (1996), S. 257-262 
    ISSN: 1432-5233
    Keywords: Key words NIDDM ; Candidate genes ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Acta diabetologica 33 (1996), S. 257-262 
    ISSN: 1432-5233
    Keywords: NIDDM ; Candidate genes ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 92 (1996), S. 382-387 
    ISSN: 1432-2242
    Keywords: Genetics ; Blacking resistance ; Brassica napus ; Brassica juncea ; Leptosphaeria maculans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genetic control of adult-plant blackleg (Leptosphaeria maculans) resistance in a Brassica napus line (579NO48-109-DG-1589), designated “R13” possessing Brassica juncea-like resistance (JR), was elucidated by the analysis of segregation ratios in F2 and F3 populations from a cross between “R13” and the highly blackleg-susceptible B. napus cultivar “Tower”. The F2 segregration ratios were bimodal, demonstrating that blackleg resistance in “R13” was controlled by major genes. Analysis of the segregation ratios for 13 F3 families indicated that blackleg resistance in these families was controlled by three nuclear genes, which exhibited a complex interaction. Randomly sampled plants of F3 progeny all had the normal diploid somatic chromosome number for B. napus. The similarities between the action of the three genes found in this study with those controlling blackleg resistance in B. juncea is discussed.
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  • 19
    Electronic Resource
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    Springer
    Theoretical and applied genetics 92 (1996), S. 817-826 
    ISSN: 1432-2242
    Keywords: Zea mays ; RFLPs ; Plant breeding ; Genetics ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study was conducted to compare maize quantitative trait loci (QTL) detection for grain yield and yield components in F2∶3 and F6∶7 recombinant inbred (RI) lines from the same population. One hundred and eighty-six F6∶7 RIs from a Mo17×H99 population were grown in a replicated field experiment and analyzed at 101 loci detected by restriction fragment length polymorphisms (RFLPs). Single-factor analysis of variance was conducted for each locus-trait combination to identify QTL. For grain yield, 6 QTL were detected accounting for 22% of the phenotypic variation. A total of 63 QTL were identified for the seven grain yield components with alleles from both parents contributing to increased trait values. Several genetic regions were associated with more than one trait, indicating possible linked and/or pleiotropic effects. In a comparison with 150 F2∶3 lines from the same population, the same genetic regions and parental effects were detected across generations despite being evaluated under diverse environmental conditions. Some of the QTL detected in the F2∶3 seem to be dissected into multiple, linked QTL in the F6∶7 generation, indicating better genetic resolution for QTL detection with RIs. Also, genetic effects at QTL are smaller in the F6∶7 generation for all traits.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 93 (1996), S. 932-940 
    ISSN: 1432-2242
    Keywords: Genetics ; Adult-plant ; Blackleg resistance ; Brassica napus ; Leptosphaeria maculans ; Australian cultivar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genetic control of adult-plant blackleg [Leptosphaeria maculans (Desm.) Ces. et De Not.] resistance in rapeseed (Brassica napus L.) was studied in the F2 and first-backcross populations of the cross “Maluka” (blackleg-resistant) x “Niklas” (highly susceptible). A L. maculans isolate possessing high levels of host specificity (MB2) was used in all inoculations. Resistance/susceptibility was evaluated using three separate measures of crown-canker size, i.e. the percentage of crown girdled (%G), external lesion length (E) and internal lesion area (%II). Disease severity scores for the F2 and first-backcross populations based on E and %II gave discontinuous distributions, indicating major-gene control for these measures of resistance; but those for %G were continuous, indicating quantitative genetic control for this measure. Chi-square tests performed on the (poorly-defined) resistance classes, based on E, in the F2 and first-backcross populations indicated the likelihood for resistance being governed by a single, incompletely dominant major gene. Although the distributions of the F2 and first-backcross populations, based on%II, were clearly discontinuous, the observed segregation ratios for resistance and susceptibility did not fit any of the numerous Mendelian ratios which were considered. Differences in inheritance of resistance according to the assessment method and blackleg isolate used, were discussed.
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  • 21
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    Theoretical and applied genetics 93 (1996), S. 301-306 
    ISSN: 1432-2242
    Keywords: Leptosphaeria maculans ; Brassica napus ; Blackleg ; Genetics ; Virulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genetic basis of virulence of 24 isolates of L. maculans collected from various sites throughout south-eastern and south-western Australia were studied using five clone-lines of B. napus. The experimental design allowed the estimation of the environmental and genetic components of variance using a standard analysis of variance. Virulence of these isolates (as measured by the percentage of stem girdling, %G) on the clonelines NCII and Tap was found to be most likely controlled by a small number of genes; the broad-sense heritabilities were 79.7% and 67.5% for virulence on NCII and Tap, respectively. The significance of these results in relation to the potential of L. maculans in adapting to new resistant B. napus cultivars is discussed.
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  • 22
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    Theoretical and applied genetics 92 (1996), S. 267-272 
    ISSN: 1432-2242
    Keywords: Cerrado ; Savannah ; Acid soils ; Hydroponics ; Nutrient ; Variety ; Genetics ; Inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The soybean is a major crop in the agricultural systems of the Brazilian Cerrados (Savannahs), whose soils are acidic, devoid of nutrients and need to be amended before they are cultivated. However, below the ploughed layer there is a scarcity of nutrients and toxic aluminium (Al). These limit root growth, subsequently causing nutritional imbalance and drought stress. Our aim in the investigation described here was to identify genetic differences in the aluminium tolerance of soybeans by a 9 × 9 diallel cross among contrasting varieties grown in high-Al areas and in hydroponics. Combining ability analysis indicated predominantly additive gene effects, and the additive-dominance model explained most of the genetic differences in this germ plasm for mineral element absorption and root growth under aluminium stress. The relationship between the two factors suggest that conjugation hydroponics and field evaluations in breeding programmes would further improve soybeans with respect to yield stability under tropical cultivation conditions.
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  • 23
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    Theoretical and applied genetics 92 (1996), S. 817-826 
    ISSN: 1432-2242
    Keywords: Key words  Zea mays ; RFLPs ; Plant breeding ; Genetics ; Recombination ; Abbreviations  RFLPs Restriction fragment length polymorphisms ; QTL quantitative trait loci ; RIs recombinant inbreds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   This study was conducted to compare maize quantitative trait loci (QTL) detection for grain yield and yield components in F2:3 and F6:7 recombinant inbred (RI) lines from the same population. One hundred and eighty-six F6:7 RIs from a Mo17×H99 population were grown in a replicated field experiment and analyzed at 101 loci detected by restriction fragment length polymorphisms (RFLPs). Single-factor analysis of variance was conducted for each locus-trait combination to identify QTL. For grain yield, 6 QTL were detected accounting for 22% of the phenotypic variation. A total of 63 QTL were identified for the seven grain yield components with alleles from both parents contributing to increased trait values. Several genetic regions were associated with more than one trait, indicating possible linked and/or pleiotropic effects. In a comparison with 150 F2:3 lines from the same population, the same genetic regions and parental effects were detected across generations despite being evaluated under diverse environmental conditions. Some of the QTL detected in the F2:3 seem to be dissected into multiple, linked QTL in the F6:7 generation, indicating better genetic resolution for QTL detection with RIs. Also, genetic effects at QTL are smaller in the F6:7 generation for all traits.
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  • 24
    ISSN: 1432-2242
    Keywords: Aluminum toxicity ; Diallel analysis ; Genetics ; Rice ; Variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study was undertaken to investigate the variability among lowland rice cultivars and the mode of gene action of aluminum (Al) toxicity tolerance in rice. Pregerminated seeds were grown in a nutrient solution containing 30 ppm Al and in normal nutrient solution, and relative root length (RRL) was determined at the 14-day-old stage to characterize genotypes for tolerance. Sixty-two traditional rice cultivars grown on lowland acid sulfate soil areas of Asia and West Africa were tested. Tolerant varieties ‘Azucena’, ‘IRAT104’, and ‘Moroberekan’, moderately sensitive ‘IR29’ and ‘IR43’, and sensitive ‘IR45’ and ‘IR1552’ were used to investigate the genetics of tolerance by diallel analysis. Of the 62 cultivars tested, only 3 were found to be sensitive to A l toxicity. Among the tolerant cultivars identified, 11 (‘Siyam Kuning’, ‘Gudabang Putih’, ‘Siyam’, ‘Lemo’, ‘Khao Daeng’, ‘Siyamhalus’, ‘Bjm-12’, ‘Ketan’, ‘Seribu Gantang’, ‘Bayer Raden Rati’, and ‘Padi Kanji’) were found to possess higher levels of tolerance than the improved tolerant upland cultivar ‘IRAT104’. Diallel analysis revealed that high RRL is governed by both additive and dominance effects with a preponderance of additive effects. The trait exhibited partial dominance, and one group of genes was detected. Heritability was high, and environmenal effects were low. Findings suggest that when breeding for A1 toxicity tolerance, selection can be made in early generations. The pedigree method of breeding would be suitable. Combining ability analysis revealed the importance of both general combining ability (GCA) and specific combining ability (SCA) in the genetics of A1 toxicity tolerance in rice. GCA was more prevalent than SCA. Tolerant parens ‘Azucena’, ‘IRAT104’, and ‘Moroberekan’ were the best general combiners. The presence of reciprocal effects among crosses suggested the proper choice of parents in hybridization programs. Results indicated that ‘Azucena’, ‘IRAT 104’, and ‘Moroberekan’ should be used as the female in crosses for A1 toxicity tolerance.
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  • 25
    ISSN: 1432-2242
    Keywords: Extreme virus resistance ; Potyviruses ; Genetics ; Genes Ry and Ra ; New gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extreme resistance in cultivated potato (Solanum tuberosum) to potato viruses Y and A (PVY and PVA) conditioned by the presence of Ry genes introduced from Solanum stoloniferum was described by Cockerham (1970). Cockerham detailed a number of genes which controlled a variety of reactions, including extreme resistance to both viruses (i.e. little or no visible reaction of plants and no viral replication following graft and manual inoculation) controlled by gene Ry sto. In the present study, cvs ‘Pirola’ and ‘Barbara’, which contain a Ry gene, were found to have extreme resistance to PVY isolates from the ordinary (PVY°), veinal necrosis (PVYN) and potato tuber necrotic ringspot (PVYNTN) subgroups, and PVA. The inheritance of this phenotype was examined in seedling progenies obtained by crossing ‘Barbara’ and ‘Pirola’ with susceptible cultivars. Segregation data for resistance to PVY and PVA in a progeny involving cv ‘Pirola’ best fitted a genetical model of one gene controlling extreme resistance to both PVY and PVA, although the possibility that there are two genes, each controlling resistance to one virus but closely linked, cannot be excluded. Segregation data from progenies involving cv ‘Barbara’ best fitted a genetical model in which there are two independent genes, one controlling extreme resistance to PVA and PVY and a second gene controlling extreme resistance to PVA but not to PVY. This previously unrecognised gene conferring extreme resistance to PVA only, should be given the notation Ra in keeping with nomenclature used for other resistance genes.
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  • 26
    ISSN: 1573-0905
    Keywords: Compensation ; Dyslexia ; Environment ; Familial aggregation ; Genetics ; Risk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Education
    Notes: Abstract When one or both parents have a history of developmental reading disorder (RD) in childhood, the risk to their offspring for developing reading problems is substantially increased. However, risk research has usually assumed a stability of reading problems across the lifespan (i.e., if a parent was affected in childhood, he or she remains affected in adulthood). Yet, some individuals with RD in childhood compensate for the disorder as they grow older. Both an environmental and genetic hypothesis would predict that the risk for RD in offspring will vary as a function of parental compensation. This study examined whether risk to offspring was dependent on the parents' successful or unsuccessful compensation for their childhood reading problems. Two large family data sets were analyzed (N=907). Diagnoses with either an age discrepant or IQ discrepant criteria essentially showed that having at least one still affected parent (i.e., RD both as a child and as an adult) put the offspring at a higher risk for RD than having at least one compensated parent (i.e., RD as a child but not as an adult). The lowest risk to an offspring occurred when both parents were never affected (i.e., not RD as a child or as an adult). The implications of these findings are discussed with regard to counseling and early diagnosis of reading problems.
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  • 27
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 12 (1996), S. 1677-1702 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: No Abstract
    Additional Material: 2 Ill.
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  • 28
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    Yeast 12 (1996), S. 1647-1675 
    ISSN: 0749-503X
    Keywords: yeast ; phosphorylation ; protein phosphatase ; PP1 ; PP2A ; PP2B ; calcineurin ; Sit4 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Since the isolation of the first yeast protein phosphatase genes in 1989, much progress has been made in understanding this important group of proteins. Yeast contain genes encoding all the major types of protein phosphatase found in higher eukaryotes and the ability to use powerful genetic approaches will complement the wealth of biochemical information available from other systems. This review will summarize recent progress in understanding the structure, function and regulation of the PPP family of protein serine-threonine phosphatases, concentrating on the budding yeast Saccharomyces cerevisiae.
    Additional Material: 2 Ill.
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  • 29
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    Yeast 12 (1996), S. 1635-1646 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: No Abstract
    Additional Material: 8 Ill.
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  • 30
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    Yeast 12 (1996), S. 1607-1633 
    ISSN: 0749-503X
    Keywords: Yeast ; glycolysis ; TCA cycle ; sugar metabolism ; metabolic engineering ; pyruvate decarboxylase ; pyruvate carboxylase ; pyruvate dehydrogenase complex ; alcoholic fermentation ; Crabtree effect ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In yeasts, pyruvate is located at a major junction of assimilatory and dissimilatory reactions as well as at the branch-point between respiratory dissimilation of sugars and alcoholic fermentation. This review deals with the enzymology, physiological function and regulation of three key reactions occurring at the pyruvate branch-point in the yeast Saccharomyces cerevisiae: (i) the direct oxidative decarboxylation of pyruvate to acetyl-CoA, catalysed by the pyruvate dehydrogenase complex, (ii) decarboxylation of pyruvate to acetaldehyde, catalysed by pyruvate decarboxylase, and (iii) the anaplerotic carboxylation of pyruvate to oxaloacetate, catalysed by pyruvate carboxylase. Special attention is devoted to physiological studies on S. cerevisiae strains in which structural genes encoding these key enzymes have been inactivated by gene disruption.
    Additional Material: 7 Ill.
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  • 31
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    Yeast 12 (1996), S. 1603-1606 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: No Abstract
    Additional Material: 1 Tab.
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  • 32
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    Cellular and molecular life sciences 44 (1988), S. 491-495 
    ISSN: 1420-9071
    Keywords: Genetics ; stress ; emotionality ; locus ceruleus ; Maudsley strains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The Maudsley Reactive and Non-Reactive strains have been developed as a model for the study of individual variations in stress-reactivity, and many differences in biobehavioral systems have been found between them. This review discusses limitations of the ‘emotionality’ construct in accounting for differences between the Maudsley strains and offers an alternative, theoretical approach. Amaral and Sinnamon have proposed that the locus ceruleus (LC) plays a stress-attenuating role in mediating behavioral, physiological and neuroendocrine response to prepotent, emergency-provoking stimuli and, building upon this formulation, it is proposed that the LC has been an important focus for gene action in the Maudsley model. It is suggested that the LC of the Non-Reactive strain is more strongly activated by stressful stimuli than the LC of Reactive rats, and is the basis of many of the behavioral and physiological differences between them. Behavioral and biochemical evidence consistent with this proposition is reviewed. Identification of the LC as a target for gene-action in the Maudsley model has an important advantage. It substitutes variations at a specific anatomic location in the brain for a loosely defined construct like emotionality, and the hypothesis is amenable to empirical tests by a variety of experimental approaches.
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  • 33
    ISSN: 1432-1440
    Keywords: Genetics ; Hepatitis-B virus ; Immunogenetics ; Vaccination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The variation in immune responses to standard inoculation of the hepatitis-B virus vaccine suggest that host factors influence response in ways that are not presently understood. We studied 25 low/nonresponding health care workers (anti-HBs titer 〈50 IU/l) after the third inoculation of an experimental hepatitis-B vaccine to determine their immune status (through lymphocyte phenotypes) and HLA type. After application of a fourth inoculation, the seroconverting subjects showed only low anti-HBs levels; three male subjects remained anti-HBs negative. Twelve months after the fourth inoculation only 9 of 25 subjects (36%) maintained anti-HBs titer 〉10 IU/l. Almost all subjects had normal B-cell and CD-4 and CD-8 counts and ratios. Relative to other European populations HLA-A-10 (P〈0.05), B-12 (P〈0.025), CW-5 (P〈0.05), DR-3 (P〈0.025), and DR-5 (P〈0.025) were increased, whereas DR-2 (P〈0.05) was decreased. However, after correction of theP-values for the number of HLA antigens determined, these differences were no longer significant. Furthermore, these HLA types were not the same as those reported in other studies (except for DR-3). We suggest that larger sample sizes or even not yet available immunogenetic markers will be required to prove an “immunogenetic background” in low/nonresponders, if it exists.
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  • 34
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    Diabetologia 31 (1988), S. 407-414 
    ISSN: 1432-0428
    Keywords: Genetics ; Type 2 (non-insulin-dependent) diabetes ; linkage analysis ; restriction fragment length polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the last five years, genetic markers for a large number of diseases have been localised using linkage analysis of DNA polymorphisms in affected families. The site of the genetic defect or defects leading to Type 2 (non-insulin-dependent) diabetes mellitus, a common illness with a major genetic component, remains unknown. This is due, at least in part, to the lack of large well-defined Type 2 diabetic pedigrees suitable for linkage analysis. There are several features of the disease which make large pedigrees difficult to find. The late age of onset of most probands means that informative older generations are often dead, while there is difficulty in detecting disease in younger generations. The diagnostic criteria for diabetes are, as yet, dependent on an arbitrary cut-off along a continuum of plasma glucose. The high prevalence of the disease may also produce problems as, in any given family, diabetogenic genes may be contributed by more than one parent. Varieties of the disease with a well-defined inheritance, such as maturity onset diabetes of youth, are more suitable for linkage analysis but might be due to defects at a different gene locus. Despite these difficulties, once large well-defined pedigrees have been found, linkage analysis using both candidate genes and random highly polymorphic markers is the strategy most likely to find genetic markers for the disease.
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  • 35
    ISSN: 1432-0428
    Keywords: Genetics ; Type 2 (non-insulin-dependent) diabetes ; insulin receptor ; linkage analysis ; maturity onset diabetes of the young
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The possibility of linkage between the human insulin receptor gene locus and diabetes was examined in three Type 2 (non-insulin-dependent) diabetic families and one family with maturity onset diabetes of the young. Insulin receptor gene haplotypes were established using BglII, Rsal and Sstl restriction enzyme digests of genomic DNA from all available family members. The digested DNA was subjected to agarose gel electrophoresis, Southern blotted, and hybridised to 32P-labelled human insulin receptor gene cDNA. In the pedigree with maturity onset diabetes of the young, formal linkage analysis allowed exclusion of close linkage between the insulin receptor locus and diabetes (logarithm of the odds for linkage versus non-linkage was −5.35 at recombination fraction of 0.01). This confirms the absence of linkage between insulin receptor and diabetes which has been reported in two similar pedigrees. In the three Type 2 diabetic families there were a minimum of 4 recombinants between the insulin receptor locus and diabetes, which makes a direct role for insulin receptor defects unlikely. The importance of using realistic estimates of penetrance when performing linkage analysis in a disease with a late age of onset is emphasised. In contrast to the one previous linkage analysis study of the insulin receptor gene, no specific association of diabetes with the rare Sstl Sl(-) allele was observed in either the maturity onset diabetes of the young or the Type 2 diabetic families.
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  • 36
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    Pediatric nephrology 2 (1988), S. 239-243 
    ISSN: 1432-198X
    Keywords: Cockayne syndrome ; Renal histology ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two siblings with typical features of the Cockayne syndrome were studied at autopsy. Many glomeruli revealed a paucity of capillary loops and had thickened capillary walls. Some glomeruli with advanced lesions showed collapse of the glomerular tufts or complete hyalinization. Atrophy of tubules and interstitial fibrosis were also observed. There were no significant arteriosclerotic changes in the vessels. Ultrastructural studies demonstrated thickened glomerular basement membranes with bends and folds. These histopathological findings are different to those previously reported with the exception of the 1966 report by Ohno and Hirooka.
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  • 37
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    European journal of pediatrics 147 (1988), S. 550-552 
    ISSN: 1432-1076
    Keywords: Pterygium syndrome ; Congenital malformations ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present two brothers with Multiple Pterygium Syndrome type Escobar. Characteristic findings in this autosomal recessively inherited pterygium syndrome are, in addition to multiple pterygia, short stature, cleft palate, vertebral fusion defects and minor facial anomalies. The adult height in the two male siblings was below the third centile. Secondary sexual development and testicular size were normal, in contrast with the cryptorchidism and pubertal delay documented in most young patients.
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  • 38
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    Journal of neurology 235 (1988), S. 366-367 
    ISSN: 1432-1459
    Keywords: Gilles de la Tourette's syndrome ; Twin study ; Computed tomography ; Clinical neurophysiology ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 19-year-old male twin pair were concordant for suffering from Gilles de la Tourette's syndrome in different forms and severity. CT revealed ventricular asymmetries of varying degree within the normal range and there were no neurophysiological abnormalities. The interrelationship of genetic and environmental factors in phenotyping the syndrome is discussed.
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  • 39
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    Psychopharmacology 95 (1988), S. 237-244 
    ISSN: 1432-2072
    Keywords: Morphine ; Etonitazene ; Genetics ; Mice ; Taste ; Saccharine ; Gender
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract C57BL/6J and DBA/2J mouse strains have been characterized as morphine preferrers and avoiders, respectively (Horowitz et al. 1977). Previously, sweetened morphine solutions were presented with a water alternative, primarily with male subjects. Because sweetness may affect the endogenous opioid system and rodents have shown strain and sex differences in taste preferences, this study looked for strain- and gender-related taste preferences that might have affected opiate consumption. Preference for sweetened and unsweetened morphine and etonitazene was compared across gender and strain. In all choice tests, the control was a similar tasting quinine sulphate solution. Under these conditions, C57BL/6J mice continued to show strong preference for morphine. However, DBA/2J mice drank approximately equal amounts of morphine and quinine solutions, rather than avoiding morphine as when water was the alternative. Both strains appeared surprisingly indifferent to the synthetic opioid etonitazene, compared because it is potent at concentrations having barely perceptible bitterness. This raises the possibility of unexpected differences in post-ingestional effects between morphine and etonitazene. Contrary to reports of gender differences in sweet preference in rats, none were found in either strain of mouse. Neither were there any significant sex differences in opiate preference in either strain. C57 mice preferred sweetness more than did DBA mice.
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  • 40
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    Psychopharmacology 94 (1988), S. 428-430 
    ISSN: 1432-2072
    Keywords: Lithium ; Clonidine ; alpha2-Adrenoceptor ; Locomotor activity ; Genetics ; Mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Four strains of mice (C57, BALB, DBA, C3H) were used to determine whether genetic factors influence the effects of lithium on hypoactivity induced by a low dose of the alpha2-adrenoceptor agonist clonidine (0.2 mg/kg). Lithium was administered in the diet for 3–4 weeks at a dosage that produced average serum lithium levels of 0.58–0.66 mmol/l. Locomotor activity was reduced by either clonidine or by lithium given alone. When combined, however, lithium attenuated the activity-suppressant effects of clonidine, and that action was influenced by genetic factors. The findings suggest that genetic differences in alpha2-adrenoceptors play a role in behavioural effects of lithium.
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  • 41
    ISSN: 1432-2072
    Keywords: Selective breeding ; Mouse ; Ethanol-stimulated activity ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Low doses of ethanol (EtOH) stimulate activity in an open field in many strains of laboratory mice. We are selectively breeding two lines of mice to exhibit a large (FAST) response on this test, and two other lines to exhibit a small (SLOW) response (Crabbe et al. 1987). The lines initially diverged in response to EtOH, but despite continued selection pressure, the difference between each pair of FAST and SLOW lines has not increased over generations as much as expected. Our practice has been to test animals on the 1st day after saline injection, and repeat the test after EtOH injection 24 h later. Lister (1987) recently demonstrated that the order in which an animal was exposed to EtOH and saline influenced the magnitude of the response to EtOH, with animals tested initially after EtOH having greater stimulation. Middaugh et al. (1987) recently demonstrated that the magnitude of EtOH stimulation was greater under conditions of relatively bright light than under dim light. Using non-selected Swiss mice, the current experiments essentially confirmed Lister's findings. Using FAST and SLOW mice, the predictions of both groups were tested. Both hypotheses were confirmed. Additionally, these experiments demonstrated that the magnitude of the difference between FAST and SLOW mice was greater under bright light than under dim light. The line difference was also greater when tested in the EtOH-Saline order. In experiments with Swiss mice, the possible role of peritoneal irritation in the EtOH effect was eliminated, and the optimal dose and time for demonstrating the effect was determined. These experiments confirm the importance of lighting condition, order of testing, dose, and route of administration in eliciting EtOH-stimulated open field activity in mice. They demonstrate a genotype-environment interaction, since the magnitude of difference between genetically selected lines varied as a function of the testing parameters chosen. Finally, they indicate that the differences between FAST and SLOW lines in sensitivity to EtOH generalizes to several environmental conditions. We interpret this to mean that the various EtOH-induced activation traits represented by these different environmental and testing conditions are genetically correlated.
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  • 42
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    European archives of psychiatry and clinical neuroscience 237 (1988), S. 244-252 
    ISSN: 1433-8491
    Keywords: EEG ; Genetics ; MZ/DZ twins reared apart ; Within-pair similarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Within the broader context of our investigations into the heredity of the human EEG, we analysed the EEGs of 28 pairs of monozygotic and 21 pairs of dizygotic twins who were separated as infants and reared apart. The principal goal of this study was to determine the degree to which environmental factors possibly influence the development of a person's EEG. Monozygotic twins reared apart were, with respect to their EEGs, only slightly less similar to each other (if there is any difference at all) than the same person is to himself over time. For dizygotic twins reared apart, we verified the findings of our previous study, namely, that the average within-pair similarity of EEGs estimated from a sufficiently representative sample of fraternal twins was significantly higher than the average inter-individual similarity of EEGs obtained from unrelated persons. The results on both monozygotic and dizygotic twins, yielded conclusive proof that the individual EEG pattern is predominantly determined by hereditary factors.
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  • 43
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    Journal of neurology 235 (1988), S. 422-424 
    ISSN: 1432-1459
    Keywords: Epidemiology ; Genetics ; Hereditary motor neuropathy ; Spinal muscular atrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 4-year-search for spinal muscular atrophies (hereditary motor neuropathies, HMN) in Benghazi, Libya, yielded a total of 24 patients, among whom 18 were index cases. This group comprised 6 acute infantile, 12 chronic childhood, and 3 each with adult-onset proximal, and distal forms of the disorder. Distal HMN constituted 12.5% of the total cases. The crude average annual incidence of acute infantile HMN was 0.3/100,000 total population and 1/12,500 births in Benghazi. The crude prevalence rates of chronic childhood, adult-onset proximal, and distal types of HMN were 2.3, 0.6, and 0.6/100,000 respectively. The segregation ratios, 0.26 for acute infantile HMN and 0.24 for chronic childhood HMN, suggested autosomal recessive inheritance. The consanguinity rates among parents of cases and the population did not differ significantly.
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  • 44
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    Theoretical and applied genetics 75 (1988), S. 889-901 
    ISSN: 1432-2242
    Keywords: Soybean ; Restriction fragment length polymorphism ; Genetics ; Allele ; Variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Restriction Fragment Length Polymorphisms (RFLP) have been identified between widely distant cultivars (‘Minsoy’ and ‘Noir 1 ’) of soybean Glycine max (L.) Merrill. Using as probes randomly chosen clones of DNA, one in five probes revealed a polymorphism. More than half of these polymorphisms appear to result from rearrangements of the genomic DNA. Twenty seven markers were analyzed for linkage in F2 plants. Eleven of these markers were contained in four linkage groups. Five cultivars were compared in a search for new alleles. When RFLP markers corresponding to low copy DNA were used to analyze three other cultivars — ‘Sooty’, ‘Forrest’ and ‘Mandarin (Ottawa)’ — few new alleles were found. Using these probes, five different markers could be used to differentiate the five cultivars. Complex probes, which correspond to repeated DNA, revealed different polymorphisms in different cultivars and a single such probe could be used to distinguish the five cultivars from each other.
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  • 45
    ISSN: 1432-2242
    Keywords: Ornithine decarboxylase ; Chicken ; Muscle ; Genetics ; Growth differences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Little is known about the biochemical correlates of selection for growth in farm or laboratory animals, or the identity of the gene products affected or produced by ‘trait-genes’. Modern broiler chickens have about 8-fold greater breast muscle mass than layer chickens at 7 weeks of age and over 2-fold greater breast muscle mass than their 1972 counterparts. This increase in muscle mass is associated with over 20-fold higher levels of ornithine decarboxylase (ODC) in broiler chickens at 1 week of age as compared with layer strain chickens; there is a comparable increase in a relaxed-selection strain of broilers. The increase in ODC levels is larger than the differences in muscle or body weight between broilers and layers at 7 weeks of age, occurs at an age when there is no difference in weights between the strains and precedes the major growth spurt. Increases in ODC levels and hence polyamine synthesis have been associated with, and usually precede, rapid growth and cell proliferation in a wide range of cell types and organisms in response to many different stimuli. Therefore, the correlation of ODC levels with genetic differences in muscle growth make it worth investigating the control of ODC gene expression in these strains.
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  • 46
    ISSN: 1432-2242
    Keywords: Taxonomy ; Germplasm identification ; Varietal identity ; Environmental interaction ; Genetics ; Multivariate analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Separations of kafirin and alcohol soluble glutelin proteins by reversed-phase high-performance liquid chromatography (RP-HPLC) from 7 inbreds and one hybrid of sorghum [Sorghum bicolor (L.) Moench] and one source of Johnsongrass [Sorghum halapense (L.) Pers.] were compared. Objectives were to assess the stability of protein profiles for seed sources produced at different locations and in different environments to examine the potential of RP-HPLC to provide genotypic profiles for sorghum. Analyses of variance data showed that levels of variation due to environments and locations were small; the majority of variation (93%) was among genotypes. Associations among inbreds revealed by multivariate and cluster analysis showed similarity with those that would be expected on the basis of pedigree. A chi-square analysis showed no deviation in the hybrid profile from the expected 2∶1 ratio of peaks from the female and male inbred parents, respectively. Improvements in the ability to correctly assign common peaks are necessary before associations among numerous sorghum genotypes can be reliably demonstrated by analysis of data from reversed-phase high-performance liquid chromatography (RP-HPLC).
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  • 47
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    Theoretical and applied genetics 76 (1988), S. 405-410 
    ISSN: 1432-2242
    Keywords: Zea mays ; Haploid induction ; Gynogenesis ; Genetics ; Inducer line
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of genotype on maternal haploid plant production in maize was studied. The frequency of gynogenetic plants when “Stock 6” was used as pollinator varied according to the female parent genotype. No simple relation was observed between genotypic aptitudes for gynogenetic and androgenetic development, which occured after pollination of “W23” plant carrying the “indeterminate gametophyte” gene. Furthermore, the population NS, a favorably responsive genotype to anther culture, does not exhibit exceptional ability for in vivo gynogenesis. The effect of inbreeding and the influence of maternal haploid origin suggest that specific genes control maternal haploid initiation and development. However, gynogenetic development is not limited to a particular genotype. The frequency of maternal haploids may be increased by using specific pollen parents. Attempts were made to select for a high haploidyinducing trait and the present study reports the successful development of lines that can be utilized as pollen parents to induce haploids for experimental purposes and breeding programmes. When an inbred line “WS14”, derived from the cross W23 x Stock 6, was used as pollen parent, 2%–5% maternal haploids were obtained according to the female parent genotype. A high haploidy-inducing potential is a heritable trait and may be controlled by a limited number of genes. Genetic determination of the haploidy-inducing character was examined in relation to the efficiency of the selecting method and the mechanisms involved in the origin of maternal haploids.
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  • 48
    ISSN: 1617-4623
    Keywords: Nicotiana plumbaginifolia ; Nitrate reductase ; Genetics ; Molybdenum cofactor biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A total of 70 cnx mutants have been characterized from a collection of 211 nitrate reductase deficient (NR-) mutants isolated from mutagenized Nicotiana plumbaginifolia protoplast cultures after chlorate selection and regeneration into plants. They are presumed to be affected in the biosynthesis of the molybdenum cofactor since they are also deficient for xanthine dehydrogenase activity but contain NR apoenzyme. The remaining clones were classified as nia mutants. Sexual crosses performed between cnx mutants allowed them to be classified into six independent complementation groups. Mutants representative of these complementation groups were used for somatic hybridization experiments with the already characterized N. plumbaginifolia mutants NX1, NX24, NX23 and CNX103 belonging to the complementation groups cnxA, B, C and D respectively. On the basis of genetic analysis and somatic hybridization experiments, two new complementation groups, cnxE and F, not previously described in higher plants, were characterized. Unphysiologically high levels of molybdate can restore the NR activity of cnxA mutant seedlings in vivo, but cannot restore NR activity to any mutant from the other cnx complementation groups.
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  • 49
    ISSN: 0032-8332
    Keywords: Saimiri ; Human-type ABO blood groups ; Genetics ; Colony management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The human-type ABO blood groups were determined for 94 families of the squirrel monkey which included 151 animals. Four phenotypes of ABO blood groups (A, B, AB, and O) were detected. Family analysis revealed that the human-type ABO blood groups in this species were governed by three alleles, codominantA andB and silentO. There were intraspecific differences in the distribution of phenotypes and gene frequency among three populations imported by different routes at different times. The usefulness of ABO blood groups for defining the genetic variability of a squirrel monkey breeding colony through successive generations is discussed on the basis of the difference in distribution of ABO blood groups between wild-originated parental and its first colony-born populations.
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  • 50
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 23-35 
    ISSN: 0192-253X
    Keywords: maternal-specific transcripts ; genomic clones ; developmental RNA expression ; in situ chromosomal localization ; embryogenesis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The unique cellular and genetic events which occur during the first few hours of Drosophila embryogenesis suggest that there are genes whose function is entirely or largely limited to this stage; this is supported by both genetic and molecular evidence. To identify some of these genes and characterize the relative contribution of specifically maternal and specifically zygotic transcription to early embryogenesis, we used competition and differential screening of a Drosophila genomic DNA library to obtain blastoderm- and maternal-differential sequences [Roark et al.: Dev Biol 109:476-488, 1985]. We describe here the Eco RI restriction fragments, chromosomal location, and size and developmental pattern of expression of the RNAs transcribed from 19 maternal-differential sequences. Five sequences encode maternal-specific transcripts (50-150-fold more abundant in maternal RNA than at any other stage). The maternal-specific and maternal-differential sequences are located at single sites on all major chromosome arms. Comparison of these sites with the sites of presently mapped maternal-effect genes shows several possible correlations, including one region containing three maternal-effect lethal mutations and two maternalspecific sequences.
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  • 51
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    Developmental Genetics 9 (1988), S. 69-69 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 52
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 53
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 1-12 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 5 Ill.
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  • 54
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    Developmental Genetics 9 (1988), S. 37-48 
    ISSN: 0192-253X
    Keywords: eggshell ; female sterile mutant ; endochorion ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Four female-sterile mutants, fs(l)K451, fs(1)K1214, fs(1)K575TS, and fs(1)384, were studied in terms of chorion structure and chorion protein composition. The first three of these mutants cause morphological defects, ie, substantial underproduction and disruption of the endochorion, correlated with underproduction of the six major chorion proteins, s15-s38; the phenotypes are consistent with the observation that these mutants interfere with amplification of the major chorion genes that encode the s15-s38 proteins [Orr et al.: Proc Natl Acad Sci USA 81:3773-3777, 1984; Komitopoulou et al.: Dev Genet 7:75-80, 1986]. The fourth mutant, fs(1)384, and its alleles do not interfere with production of the major chorion proteins and the morphologically detectable bulk of the endochorion but lead to failure of endochorionic organization. Apparently this complementation group is responsible for a minor chorion product, which is evidently important morphogenetically and which is processed posttranslationally in a complex manner [Bauer and Waring: Dev Biol 121:349-358, 1987].
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  • 55
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 91-120 
    ISSN: 0192-253X
    Keywords: actin filament bundles ; ethyl methane sulfonate ; female sterile mutants ; in terallelic complementation ; oocyte determination ; ovarian tumor genes ; phenocritical thresholds ; polyfusomes ; polytene nurse cell chromosomes ; polytrophic meroistic ovaries ; pseudonurse cells ; Q-T-P-O values ; rhodaminyl phalloidin ; temperature-sensitive mutants ; transformed oocytes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The ovarian tumor gene behaves as if it encodes a product (OGP), which is required durirng several early steps in the transformation of oogonia into functional oocytes. Seventeen ethyl methane sulfonate-induced mutations have been studied, and their mutant phenotypes can be explained as graded responses by individual germ cells to different levels of OGP synthesized by the mutant germ cells themselves. The lowest and highest levels of OGP appear to be produced by otu10 and otu14, respectively. The 15 mutants with intermediate OGP levels are temperature sensitive; subnormal temperatures improve ovarian development, while above-normal temperatures suppress it. A subgroup ofthese mutants are unable to form a system of actin microfilament bundles in the cortical cytoplasm of their nurse cells during stage 10B, and these defective nurse cells are unable to transport their cytoplasm to the oocyte, as normally happens between stages 10B and 12. In addition to its role in the actin-mediated transport of nurse cell cytoplasm, OGP also appears to alter the morphology of giant polytene chromosomes, which form as the nurse cells undergo endocycles of DNA replication. Genetic evidence suggests that otu also encodes a second product (SP) that is utilized late in oogenesis. SP is required for the synthesis in the ooplasm of glycogen-rich, beta yolk spheres. Products of the otu gene also play a vital but unknown role in embryogenesis.
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  • 56
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    Developmental Genetics 9 (1988), S. 181-191 
    ISSN: 0192-253X
    Keywords: cell interactions ; hematopoiesis ; mutagenesis ; SV40 ; fetal liver ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Several lines of transgenic mice were produced by pronuclear injection of a full-length cDNA encoding a mutant dihydrofolate reductase (DHFR, E.C. 1.5.1.3). The mutation causes altered enzyme kinetics for folate reduction as well as low affinity for methotrexate (MTX). One line of mice carrying the plasmid displays a moderate-to-severe anemia that is evident in fetuses and newborn mice and that moderates with age. RNA studies revealed high levels of transcription of the mutant gene in the fetal and adult liver, and low or absent expression in adult bone marrow. Transcription of the mutant gene was not found in the fetal liver of other pedigrees examined. The data thus suggest that expression of this mutant gene in the main hematopoietic organ of the fetus adversely affects erythropoiesis by altering the cellular environment for erythroid differentiation, and that translocation of the site of hematopoiesis to bone marrow, where the foreign gene is not expressed, leads to normalization of red cell production.
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  • 57
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    Developmental Genetics 9 (1988), S. 213-213 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 58
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    Developmental Genetics 9 (1988), S. 683-698 
    ISSN: 0192-253X
    Keywords: variegation ; bristles ; pigmentation ; patterns ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In D. hydei two new mutants, In(1)f3 and IN(5)Z, show obvious mosaic gene expression. Their phenotypic expression is susceptible to the breeding temperature and to the addition of a supernumerary Y chromosome to the chromosome set. In this respect the mutants resemble standard cases of position-effect variegation based on the action of heterochromatin. However, since neither centromeric nor sex chromosomal heterochromatin apparently are involved, the mutations point to a new type of variegation provoked by euchromatic sections. The mosaic patterns of these mutants, in particular those of In(1)f3, will be described.
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  • 59
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    Developmental Genetics 9 (1988), S. 13-22 
    ISSN: 0192-253X
    Keywords: ontogeny ; lethality ; gene expression ; mRNA ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cadmium is a toxic metal that induces the expression of metallothionein genes in many tissues and that binds avidly to metallothionein, a soluble transition metal binding protein. The present study examined the temporal pattern and magnitude of accumulation of metallothionein mRNA in liver of C57BL/6J mice of various ages treated with cadmium. In adult female mice, accumulation was dependent on the dosage level of cadmium and related to the concentration of this metal in liver. The accumulation of metallothionein mRNA in liver depended on age at exposure to cadmium. Intraperitoneal administration of 2 mg of cadmium per kg provoked small increases (two- to threefold) in levels of metallothionein mRNA in livers of 7- and 14-day-old mice. In contrast, cadmium treatment of 28- and 56-day-old mice resulted in 12- to 19-fold increases in levels of metallothionein mRNA in liver with maximum increases occurring 3 to 4 hr after treatment. Because similar patterns for the accumulation of cadmium of liver were found in 7-, 28-, and 56-day-old mice, observed age-dependent differences in induction of metallothionein mRNA in liver were probably not due to differences in the accumulation of cadmium in this organ. Taken together, these data suggest that tissue-specific factors controlling the expression of metallothionein genes may account for developmental variation in the inducibility of these genes by cadmium. Ontogenic variation in accumulation of metallothionein mRNA after cadmium treatment may be a factor in developmental variation in the acute lethality of cadmium in C57BL/6J mice.
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  • 60
    ISSN: 0192-253X
    Keywords: Daucus carota ; auxin ; gene expression ; mutant ; filtration-enrichment procedure ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cell cultures of the carrot Daucus carota are a useful experimental system for studying the genetic regulation of plant embryogenesis. A modified filtration-enrichment procedure was used to isolate 21 temperature-sensitive variants in somatic embryogenesis; the variants display normal embryo development at the permissive temperature (24°C) and altered development at the restrictive temperature (33°C). Temperature-shift experiments were performed on these variants to determine the timing of gene action for the putative temperature-sensitive alleles. According to their phenotypes at the restrictive temperature, these variants can be divided into six classes: No Growth, Callus Proliferation, Globularstage Block, Oblong-stage Block, Lateral Growth, and Root Formation. Although many variants exhibit lengthy temperature-sensitive periods, the temperature sensitivity of some variants is restricted to one or two embryonic stages. These results plus those in the literature are incorporated into a preliminary model concerning the genetic regulation of carrot embryogenesis.
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  • 61
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 62
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 155-165 
    ISSN: 0192-253X
    Keywords: embryonic lethal ; agouti locus ; trophectoderm ; inner cell mass ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The tissue specificity of the lethal yellow mutant was investigated by separation of blastocyst tissues. Embryos from experimental (Ay/ae × Ay/ae) and control (ae/ae × Ay/ae) crosses of the AG/CamPa inbred strain were recovered at 3.5 days post coitum, cultured for 24 hours, and then mechanically dissected into the component tissues of the blastocyst, the inner cell mass (ICM), and trophectoderm. These fragments were then cultured separately, with or without a feeder layer of inactivated fibroblasts, for an additional 3-5 days. Comparisons between experimental and control crosses indicated that the lethal Ay/Ay embryos were among the blastocysts successfully dissected but that both the ICM and trophectoderm from lethal embryos failed to develop further in vitro, eithal with or without feeders.With retrospective identification of the lethal embryos, it was found that at 4.5 days, after 1 day of culture, they had formed morphologically normal blastocysts but were frequently more fragile upon dissection and had smaller ICMs. Although none had hatched from the zona pellucida, some had ruptured it and were halfway out. With culture, lethal ICMs showed no development, and lethal trophectoderm usually attached but showed very limited outgrowth. Thus, no rescue of lethal tissue was shown with dissection and in vitro culture, and results are consistent with the gene affecting both tissues of the late blastocyst.
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  • 63
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 64
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 715-732 
    ISSN: 0192-253X
    Keywords: Regulator of postbithorax ; homeosis ; pattern formation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Genetic analysis has shown that the gap segmentation gene hunchback (hb) is a member of the genetic hierarchy involved in pattern formation in Drosophila. To identify the hb gene, we have mapped the position of hb mutant breakpoints within a chromosomal walk of the 85A region by genomic Southern blots and determined the transcription pattern of DNA from the walk. We detect a single gene within the domain defined by breakpoint mapping. We conclude that we have identified the hunchback gene because three mutations that inactivate hb physically interrupt or delete this gene. Northern analysis shows that the hb gene gives rise to at least five overlapping transcripts ranging in length from 2.6 to 3.5 kilobases. S1 nuclease and primer extension experiments demonstrate that the gene employs two promoters and three polyadenylation sites. The two hb promoters have different temporal specificities. Transcripts arising from the upstream promoter are detected from 0-12 hours of embryogenesis as well as in adult female and male RNA preparations. Transcripts arising from the downstream promoter accumulate only from 0-6 hours of embryogenesis. During the syncytial blastoderm stage, transcripts from the hb gene accumulate over a broad anterior and a narrow posterior domain. This pattern sharpens during the late blastoderm/early gastrula stage to produce an embryo with two stripes of hybridization anterior and one stripe posterior. Later, hb transcripts are detected within the ventral hypoderm in extended germ band stage embryos.
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  • 65
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    Developmental Genetics 9 (1988), S. 733-741 
    ISSN: 0192-253X
    Keywords: Phycomyces blakesleeanus ; developmental mutants ; phorogenesis ; sexual reproduction ; light ; carotene ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The mycelium of the fungus Phycomyces. essentially a giant multinucleate cell, produces two kinds of asexual reproductive structures, called macrophores and microphores, and a succession of structures for sexual reproduction. Following the treatment of spores with N-methyl-N′ -nitro-N-nitrosoguanidine, conditional imb mutants have been isolated that form no macrophores at 26°C, but do at 14°C. At the restrictive temperature, few imb mutants (2 of 13) develop microphores, and none is able to complete the sexual cycle. This suggests that genes responsible for macrophorogenesis are involved in microphorogenesis and in sexual development as well. Light reduces macrophorogenesis and totally abolishes microphorogenesis in the wild type under the conditions of our experiments. These photomorphogenetic effects require the normal function of genes madA and madB, which are responsible for phototropism. Light inhibits microphorogenesis in the two imb mutants that form microphores at the restrictive temperature. Genetic alterations of carotenogenesis lead to an excess of microphores and a scarcity of macrophores in the dark, but they have little influence on vegetative reproduction in the light.
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  • 66
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 215-226 
    ISSN: 0192-253X
    Keywords: cAMP ; cGMP ; chemotaxis ; mutant ; desensitization ; receptor ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The functional interaction of surface cAMP receptors with effector enzymes via G-proteins was investigated in Dictyostelium discoideum. Several experimental conditions were used to investigate signal transduction, such as reduced temperatures, use of down-regulated cells and of mutants. The results are presented as a model describing the complex interaction between multiple forms of the surface cAMP receptor and different G-proteins that are responsible for the generation of the second messengers, cAMP, cGMP, InsP3 and Ca2+.
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  • 67
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    Developmental Genetics 9 (1988), S. 227-235 
    ISSN: 0192-253X
    Keywords: receptors ; transmembrane signalling ; Dictyostelium ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Using antibodies specific for the 3′, 5′-cyclic AMP (cAMP) cell surface receptor of Dictyostelium discoideum, we have screened γgtll expression libraries and isolated a series of cDNAs derived from cAMP receptor mRNA during early development. The identity of the cDNA clones was verified by multiple criteria: (1) β-galactosidase fusion proteins synthesized by isolated cDNA clones stain intensely with cAMP receptor directed antiserum, (2) these fusion proteins affinity purify antibodies specific for the cAMP receptor, (3) the cDNA probes hybridize to a 2 kb mRNA whose change in relative level of abundance during development parallels that of receptor mRNA as assayed by in vitro translation, (4) the 2 kb mRNA size equals that of receptor mRNA as determined by in vitro translation of size fractionated poly (A)+ RNA, and (5) RNA transcribed in vitro from cDNAs containing the entire protein-coding region produces a polypeptide by in vitro translation with an apparent molecular weight in close agreement with that of nascent cAMP receptor protein produced by in vitro translation of cellular RNA.The DNA sequence predicts an open reading frame of 392 amino acids. The deduced amino acid sequence contains seven domains enriched in hydrophobic residues. A model is proposed in which the cAMP cell-surface receptor traverses the lipid bilayer seven times in a pattern similar to that of other receptors, such as rhodopsin, which interact with G-proteins. The structural similarities suggest a gene family of related surface receptors from such evolutionarily diverse species as Dictyostelium, yeast, and mammals.
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  • 68
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    Developmental Genetics 9 (1988), S. 247-258 
    ISSN: 0192-253X
    Keywords: protein evolution ; lower eukaryote ; differentiation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The cAMP-dependent protein kinase (cAK) from Dictyostelium discoideum is an enzyme composed of one catalytic and one regulatory subunit. Upon binding of cAMP, the holoenzyme dissociates to liberate free active catalytic subunits. The cAK is developmentally regulated, ranging from very little activity in vegetative cells to maximal expression in postaggregative cells. Although there is no immunological cross-reaction between the subunits of cAKs from Dictyostelium and from other organisms, they share several biochemical properties. A complete cDNA for the regulatory subunit has been cloned and sequenced. Only one copy of the gene for the regulatory subunit is present per haploid genome. On the basis of the comparison of the structure of the cAK from Dictyostelium with its counterparts in yeast and higher eukaryotes, we propose a model for the evolution of cyclic-nucleotide-binding proteins.
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  • 69
    ISSN: 0192-253X
    Keywords: gene regulation ; immunoblotting ; rapid-developing variants ; molecular cloning ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Several lines of evidence indicate that cAMP modulates developmental gene activity via cell-surface receptors. We describe here a novel cAMP receptor, CABP1, whose properties are consistent with the idea that this protein is involved in gene regulation. Firstly, immunological techniques using anti-CABP1 antibodies as probes showed that this cAMP receptor can be detected on the surface of developing cells. Secondly, there is a steady migration of CABP1 to the nucleus during development. Thirdly, some genetic variants exhibiting an altered pattern of development are found to possess modified CABP1. We also showed that CABP1 co-purifies with at least seven other polypeptides which share common epitopes with CABP1. Interestingly, four of the CABP1-related polypeptides can be detected on the cell surface as well as in the nucleus.
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  • 70
    ISSN: 0192-253X
    Keywords: transformation ; gene structure ; cAMP ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The cyclic nucleotide phosphodiesterase (phosphodiesterase) of Dictyostelium discoideum plays an essential role in development by hydrolyzing the cAMP used as a chemoattractant by aggregating cells. We have studied the biochemistry of the phosphodiesterase and a functionally related protein, the phosphodiesterase inhibitor protein, and have cloned the cognate genes. A 1.8-kb and a 2.2-kb mRNA are transcribed from the singlephosphodiesterase gene. The 2.2-kb mRNA comprises the majority of the phosphodiesterase mRNA found in differentiating cells and is transcribed only during development from a promoter at least 2.5 kb upstream of the translational start site. The 1.8-kb phosphodiesterase mRNA is detected at all stages of growth and development, is present at lower levels than the developmentally induced mRNA, and is transcribed from a site proximal to the protein-coding region. The phosphodiesterase gene contains a minimum of three exons, and a 2.3-kb intron, the longest yet reported for this organism. We have shown that the pds A. gene and fourfgd genes affect, the accumulation of the phosphodiesterase mRNAs, and we believe that these loci represent a significant portion of the genes regulating expression of the phosphodiesterase. The phosphodiesterase gene was introduced into cells by transformation and used as a tool to explore the effects of cAMP on the terminal stages of development. In cells expressing high levels of phosphodiesterase activity, final morphogenesis cannot be completed, and differentiated spore and stalk cells do not form. We interpret these results to support the hypothesis that cAMP plays an essential role in organizing cell movements in late development as well as in controlling the aggregation of cells in the initial phase of the developmental program.
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  • 71
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    Developmental Genetics 9 (1988), S. 259-265 
    ISSN: 0192-253X
    Keywords: G-proteins ; gene expression ; developmental regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have identified a two-member gene family in the Dictyostelium genome and have isolated corresponding cDNA or genomic DNA recombinant clones. Analyses of these DNA sequences predicted encoded proteins of ∼200 amino acids with ∼90% sequence identity to each other. These Dictyostelium proteins also share amino acids identity within the GTP-binding domains in the family of G-regulatory proteins involved in cellular regulation and transmembrane signalling. Additional structural similarities are seen with members of the ras supergene family, such as ras, ral, and rho. They are similar in size (usually ∼200 amino acids), possess four conserved domains involved in GTP interaction and are believed to be anchored in the membrane by fatty acid modification of a cysteine residue near the carboxy terminus. More extensive identity is observed with YPT1 and SEC4, two other members of this family of genes that are essential in yeast. The amino-terminal half of both Dictyostelium proteins is 70% identical in amino acid sequence to the YPT1 and SEC4 yeast proteins with less identity continuing through the remainder of the proteins. In addition these proteins terminate in two cysteine residues that are thought to be required for membrane anchorage.The two genes within this Dictyostelium family are organized differently in the genome and are differentially regulated during development. One gene is colinear in sequence with its mRNA in the protein coding region, whereas the other gene encodes a spliced mRNA. The intron-containing gene is associated with a developmentally regulated (AAC)-repeat sequence. Finally, we have shown that the expression of one of the genes is induced during development with kinetics similar to that of other (AAC)n-associated genes; conversely, the expression of the second gene is repressed at a similar developmental stage.
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  • 72
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    Developmental Genetics 9 (1988), S. 303-313 
    ISSN: 0192-253X
    Keywords: developmentally regulated cDNAs ; Dictyostelium discoideum gene sequences ; developmentally regulated proteins ; Dictyostelium spore proteins ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Similar to other stages in Dictyostelium development, spore germination is a particularly suitable model for studying the regulation of gene expression, because developmentally regulated changes in both protein and mRNA synthesis occur during the transition from dormant spore to amoeba. Spores are constitutively dormant and must be activated to germinate. Under the proper environmental conditions, spores germinate in a highly synchronous manner to give rise to individual amoebae that can then enter the vegetative growth phase. Protein synthesis is developmentally regulated during this process. Because protein synthesis is transcriptionally controlled during spore germination, the respective genes must be developmentally transcribed, and these can be isolated and analyzed. Three cDNA clones specific for mRNA developmentally regulated during spore germination have been characterized and used as probes to study mRNA accumulation and decay during spore germination. Because we are interested in defining the sequences of developmentally regulated genes that may relate to their regulation of transcription, we have sequenced the cDNAs and have isolated and sequenced their respective genomic clones. The sequences of the three gene families, their genomic organization, and their special structural features are described.
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  • 73
    ISSN: 0192-253X
    Keywords: ions ; developmental regulation ; receptor regulation ; developmental signals ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have analyzed the effects of the cAMP relay inhibitor, caffeine, and the receptor antagonist, adenosine, on the regulation of the cell-surface cAMP receptor in suspensionstarved Dictyostelium discoideum cells by measuring ammonium sulfate-stabilized binding of [3-H]cAMP to intact cells. When cells were starved in fast (230 r.p.m.) shaken suspension in 10 mM Na+/5 mM K+ phosphate buffer, pH 6.5, plus 1 mM CaCl2 and 2.5 mM MgCl2, and assayed for specific cAMP binding, receptor accumulation peaked at approximately 6 hours, reaching a maximum of 1.5 pmol cAMP bound/107 cells (saturation binding). Neither caffeine nor adenosine inhibited the accumulation of cAMP receptors. Similar results were obtained in caffeine-treated, slow shaken (90 r.p.m.) suspension cultures. These results suggest that starvation alone is sufficient stimulus to induce the cAMP receptor. We have also tested the effects of different buffer ionic compositions on the accumulation of cAMP receptors. Elevation of the monovalent ion concentration to 30-40 mM was found to significantly inhibit the induction of cAMP receptors.
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  • 74
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    Developmental Genetics 9 (1988), S. 279-292 
    ISSN: 0192-253X
    Keywords: Dictyostelium ; development ; cAMP ; cell-cell contact ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: cAMP and cell-cell contact are involved in the coordination of differentiation and morphogenesis in Dictyostelium discoideum. The experiments described in this paper establish a relationship between cAMP and cell-cell contact. Contact between Enterobacter aerogenes and aggregation-competent Dictyostelium amoebae and contact between Dictyostelium amoebae themselves results in the transient secretion of cAMP and an alteration in the amount of cAMP secreted in response to subsequent stimulation by cAMP, i.e., an alteration in magnitude of a cAMP relay response. The subsequent cAMP relay response can be enhanced or diminished depending upon the number of contacts formed and the concentration of cAMP present at the time of contact. Latex beads are capable of evoking cAMP secretion. However, the bead/amoebal contact is unable to alter the magnitude of a subsequent response to cAMP. This suggests that a nonspecific interaction via cell-cell contactelicits transient cAMP secretion in aggregation-competent Dictyostelium amoebae.The two responses to cell-cell contact are distinct from each other and distinct from the cAMP relay response. (1) The dose-response curves for the responses to Enterobacter contact are clearly different. (2) Contact with latex beads can elicit cAMP secretion but not alter the magnitude of a subsequent cAMP relay response. (3) The temperature dependences of the contact-induced responses and the cAMP relay response show that only the contact-induced cAMP secretion is inhibited at 12 and 15°C, while only the cAMP relay response is inhibited at 28°C.A 4-second application of cAMP at the time that contact is initiated enhances both contact-induced responses. Whether the relationship between these two developmental regulators is important for the regulation of Dictyostelium development has yet to be established.
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  • 75
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    Developmental Genetics 9 (1988), S. 327-335 
    ISSN: 0192-253X
    Keywords: gene regulation ; initiation of development ; slime mold ; transcription ; cycloheximide ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Several genes that are deactivated upon the initiation of development of Dictyostelium discoideum have been identified by differential screening of various cDNA libraries. These genes have in common a decrease in the steady-state levels of their corresponding mRNAs as development proceeds. When development was carried out in the absence of protein synthesis by inhibition with cycloheximide, the decrease in mRNA levels for most genes (V genes) was normal or slightly accelerated. However, for about 5% of the genes (H genes), cycloheximide caused an apparent induction of expression, as revealed by a slight or dramatic increase in mRNA levels instead of the normal decrease. This effect was due to inhibition of protein synthesis and not to cycloheximide per se. The induction was found to be due to an enhancement of the trascription rate; normal rates of transcription for the H genes were dependent upon continued protein synthesis during vegetative growth and during development. Thus, two general regulatory classes exist for deactivation of gene expression upon initiation of development, one dependent and one independent of protein synthesis. Models concerning the control of expression of these two classes of genes are discussed here. Analysis of expression of these genes in mutant strains that are aggregation-deficient has also been performed, and the results lead to subdivisions of the classes.
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  • 76
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    Developmental Genetics 9 (1988), S. 315-326 
    ISSN: 0192-253X
    Keywords: Dictyostelium ; growth ; development ; regulation ; discoidin I ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have previously shown that growing cells of Dictyostelium discoideum (strains NC4 and AX3) produce a soluble substance that accumulates in the medium in proportion to cell density; this substance regulates the production of certain proteins previously thought to be induced by starvation [Clarke et al., 1987]. We suggest the name PSF (prestarvation factor) for this substance. During growth, Dictyostelium cells monitor the relative concentrations of PSF and food bacteria. When PSF reaches a sufficiently high level relative to the concentration of bacteria, synthesis of PSF-regulated proteins is induced. We propose the name prestarvation response for this induction, which takes place in exponentially growing cells several generations before the food bacteria are depleted. We have explored the mechanism by which the food bacteria inhibit the response of Dictyostelium cells to PSF. We find that the bacteria do not inactivate PSF or inhibit its production; instead, they affect the ability of NC4 cells to detect PSF, possibly by binding to the same cell surface receptor. In the absence of bacteria, as during axenic growth of AX3 cells, the prestarvation response occurs at much lower cell densities, probably accounting for the presence of certain developmentally regulated mRNAs and proteins in axenic cultures.
    Additional Material: 6 Ill.
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  • 77
    ISSN: 0192-253X
    Keywords: cAMP ; Ca2+ ; signal transduction ; cell surface receptor ; gene expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Elevated levels of cAMP are essential for the expression of many postaggregation prespore and prestalk mRNA species and for the suppression of some growth phase mRNAs. Here we review evidence that this regulation is mediated by cAMP interacting at the cell surface receptor. These effects of cAMP on gene expression can occur under conditions where the receptor-associated adenylate cyclase is inactivated and in concentrations that are consistent with receptor binding. A number of differences are noted in the mechanism by which cAMP regulates prespore and prestalk genes. Finally, evidence is reviewed for the role of a Ca2+-dependent signal transduction system in coupling the expression of some of the prespore mRNAs to the cAMP receptor. This signal transduction system does not appear to be involved in the expression of the cAMP-dependent prestalk gene.
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  • 78
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    Developmental Genetics 9 (1988), S. 337-350 
    ISSN: 0192-253X
    Keywords: Dictyostelium ; cAMP ; receptor ; gene regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have examined the expression of a cAMP pulse-repressed and two cAMP pulse-induced genes in response to cAMP and caffeine under a number of different physiological conditions, and in several classes of developmental mutants altered in cAMP-mediated signal transduction pathways. The data presented help characterize the mutants with regard to early gene expression. Analysis of the data indicates that full induction of the pulse-induced or repression of the pulse-repressed genes requires cycles of activation and adaptation of the cAMP receptor but does not require a rise in intracellular cAMP. Comparison of the results obtained between different mutant classes suggests that repression and activation of the two classes of genes can be uncoupled, implying that different intracellular mechanisms control these processes. In addition, we examined the effects of caffeine and show that it can induce pulse-induced mRNA accumulation in the absence of cAMP.
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  • 79
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    Developmental Genetics 9 (1988), S. 351-358 
    ISSN: 0192-253X
    Keywords: Dictyostelium ; diacylglycerol ; inositol trisphosphate ; developmetal regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In Dictyostelium, extracellular cAMP interacts specifically with cell-surface receptors to promote the accumulation of a variety of intracellular second messengers, such as, 3′-5′ cyclic adenosine monophosphate (cAMP) and 1,4,5 inositol trisphosphate (IP3). We and others have shown that activation of the cell-surface cAMP receptor can also modulate the expression of the Dictyostelium genome during development. In at least one instance, synthesis of intracellular cAMP is required for appropriate gene regulation. However, the induction of most cAMP-dependent gene expression can occur in the absence of receptor-mediated activation of adenylate cyclase and a consequent accumulation of intracellular cAMP. These results suggest that other intracellular second messengers produced in response to receptor activation may potentially act as signal transducers to modulate gene expression during development. In vertebrate cells, IP3 and diacylglycerol (DAG) are intracellular activators of specific protein kinases; they are produced in equimolar amounts by cleavage of phosphoinositol bisphosphate after a receptor-mediated activation of a membrane-bound phosphodiesterase. IP3 and, thus, by inference, diacylglycerol are synthesized in Dictyostelium as a response to cAMP interacting with its cell-surface receptor. Using defined conditions to inhibit the accumulation of extracellular cAMP, we have examined the effects of these compounds on the accumulation of extracellular cAMP, we have examined the effects of these compounds on the expression of genes that require cAMP for their maximal expression. Our results suggest that intracellular IP3 and DAG may in part mediate the action of extracellular cAMP on the expression of the Dictyostelium genome.
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  • 80
    ISSN: 0192-253X
    Keywords: Dictyostelium cell type markers ; PsA ; phosphatidylinosito ; D19 gene ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The nucleotide sequence of D19, a Dictyostelium gene that encodes a prespore-specific mRNA sequence shows it to encode PsA, the cell surface protein detected by the MUD 1 monoclonal antibody. The predicted sequence of the protein reveals a largely hydrophobic C terminus, with chemical similarity to proteins known to be attached to the plasma membrane via a phosphatidylinositol link. The C-terminal region has direct sequence homology to the contact sites A protein and to the phosphatidylinositol-linked form of a chicken N-CAM, suggesting that it might play a role in cell adhesion. Expression of the D19 gene is known to be induced by cAMP and repressed by adenosine. The accumulation of the D19 mRNA is also repressed by DIF, the putative stalk-specific morphogen, and this effect is mediated at the transcriptional level. The pDd56 and pDd63 genes are induced by DIF, and they are specific markers of prestalk and stalk cells. They encode, respectively, ST310 and ST430, two proteins that were first identified by two-dimensional gel electrophoresis. Both proteins are predominantly composed of a highly conserved, 24-amino acid repeat. The two proteins are localized in the slime sheath of the migratory slug and in the stalk tube and stalk cell wall of the mature culminant, where they presumably function as structural components of the extracellular matrix. We have constructed marked derivatives of the pDd56, pDd63, and D19 genes, and these are correctly regulated after transformation into Dictyostelium cells. Thus we have determined the structure, and elucidated possible functions, for one prespore and two prestalk genes. These sequences should be of value, both as markers of the earliest events in cellular differentiation and in identifying the regulatory sequences controlling cell type-specific gene expression.
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  • 81
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    Developmental Genetics 9 (1988), S. 371-382 
    ISSN: 0192-253X
    Keywords: second messenger ; transcription ; DNase I hypersensitive sites ; cis-acting elements ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: cAMP regulates gene expression in Dictyostelium discoideum through the cell surface receptor and is therefore a transmembrane signal transduction event. We have now begun to examine the signal transduction pathway that transmits the cAMP-induced signal to the nucleus. The results presented here indicate that Ca2+ plays a crucial role. A comparison of the accumulation of UDPGP1 mRNA during development with the corresponding transcription rates revealed that this gene is regulated primarily at the level of transcription. To elucidate the factors involved in the regulation of the UDPGP1 gene we characterized its cis acting sequences. We constructed a series of deletions into the 5′ flanking region of the UDPGP1 gene and analyzed the expression of the mutated DNA in transformants. A sequence element essential for the expression of the UDPGP1 gene is located between -500 bp and -288 dp from the transcription start site. This promoter element appears to be a short G + C-rich sequence positioned between -374 to -395 and coincides with a DNase I hypersensitive site.
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  • 82
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    Developmental Genetics 9 (1988), S. 403-419 
    ISSN: 0192-253X
    Keywords: post-transcriptional regulation ; disaggregation ; poly(A)-binding proteins ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This paper reviews our studies of three aspects of post-transcriptional regulation in Dictyostelium discoideum: (1) the determinants of mRNA stability in vegetative amoebae; (2) the effects of disaggregation and cyclic AMP on the decay rates of cell-type-specific mRNAs in late developing cells; and (3) the cytoplasmic function of the 3′ poly(A) tracts present on most mRNAs. We find that: (1) mRNA stability in vegetative amoebae is not dependent on mRNA size, ribosome loading, or poly(A) tract length, but may be determined by specific 3′-untranslated sequences within a given mRNA; (2) mRNA decay rates in late developing cells are heterogeneous, and cyclic AMP does not act directly to stabilize cell-type-specific mRNAs; and (3) poly(A) is most likely involved in the initiation of protein synthesis via an interaction with cytoplasmic poly(A)-binding proteins.
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  • 83
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    Developmental Genetics 9 (1988), S. 421-434 
    ISSN: 0192-253X
    Keywords: translational control ; polyadenylation ; mRNA stability ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have isolated recombinant plasmids that contain cDNA inserts complementary to mRNAs encoding six different r-proteins of Dictyostelium discoideum. Southern and quantitative dot blot analyses have shown that each of the r-protein genes represented in these plasmids is encoded by a single copy gene and that these genes are not tightly linked to each other. We have determined the relative amount of the six r-protein mRNAs present in cells at intervals throughout development and find that for the first 9 hours of development, each of the mRNAs remains present at virtually the same level as in vegetatively growing cells. Between 9 and 11 hours of development, there is a rapid loss of these mRNAs to 15% or less of vegetative levels, and that low level remains, or slightly declines, through the late stages of development. We have shown that two post-transcriptional events contribute to the developmental regulation of the expression of the r-protein genes. The first involves a specific block to translational initiation that is not the result of inactivation of these mRNAs by decapping or deadenylation. The second is a change in the stability of these mRNAs during early development. In order to begin to analyze the role of specific sequences that may act as targets or signals in these events, we have cloned and sequenced a 1.9-kb genomic DNA fragment that encodes one of the r-proteins. We find that transcription of this gene begins in a pyrimidine-rich region that is not preceded by a TATA box, the gene contains a single intron of 350 bp, and there are two alternative 3′ processing sites. In addition, the 5′-untranslated region of the transcript contains an unusually high percentage of G and C residues relative to other Dictyostelium mRNAs.
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  • 84
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    Developmental Genetics 9 (1988), S. 597-605 
    ISSN: 0192-253X
    Keywords: cell differentiation ; differentiation inducing factor ; cyclic AMP ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Stalk cell formation in low-cell-density monolayers of Dictyostelium discoideum, strain V12-M2, occurs following the sequential addition of cyclic AMP and the differentiation-inducing factor (DIF). Both cyclic AMP and DIF are essential for the appearance of the prestalk-specific isozyme alkaline phosphatase-II, which suggests that both factors are necessary for prestalk cell formation. The available evidence suggests that the cyclic AMP requirement for stalk cell formation is mediated through the cell surface cyclic AMP receptor. However, stalk cell formation is inhibited by caffeine and this inhibition is reversed by the cell-permeable analogue 8-Br-cyclic AMP, which suggests in addition a possible involvement for elevated intracellular cyclic AMP concentrations in stalk cell formation.During in vivo development ceils first become independent of cyclic AMP at the tipped aggregate stage, but the acquisition of cyclic AMP independence is advanced by several hours when cells are incubated in the presence of cyclic AMP for 2 hours. Cells do not become independent of DIF until the culmination stage of development, which suggests the possibility that DIF is required for the conversion of prestalk cells to stalk cells.There is an absolute requirement for DIF for stalk cell formation in low-density monolayers of prestalk cells but only part of population exhibits a requirement for cyclic AMP, which suggests that the prestalk cell population consists of two distinct cell types. Stalk cell formation from prespore cells is totally dependent on both cyclic AMP and DIF.When isolated prestalk and prespore cells are plated in high-density monolayers, the former cells accumulate more DIF. which suggests the possibility that DIF is preferentially synthesized by prestalk cells.
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  • 85
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    Developmental Genetics 9 (1988), S. 615-628 
    ISSN: 0192-253X
    Keywords: colony morphology ; yeast cell wall ; aggregation variants ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Recently, high frequency switching systems have been identified in the infectious yeast Candida albicans and the cellular slime mold Dictyostelium discoideum. In C. albicans, cells can switch at spontaneous frequencies as high as 10-2 between seven general colony morphologies in the case of strain 3153A or between two major phenotypes in the white-opaque transition in strain WO-1. In the latter system, dramatic changes occur in cellular phenotype as well. In D. discoideum, cells can switch at spontaneous frequencies of roughly 10-2 between a number of colony phenotypes which include alterations in developmental timing, blocks at particular morphogenetic stages, morphological aberrations, and aggregation-minus. In the C. albicans and D. discoideum switching systems, the following characteristics are shared: (l) a limited number of switch phenotypes; (2) heritability; (3) high frequency reversibility; (4) low and high frequency modes of switching; and (5) ultraviolet (UV) stimulation of switching of cells in a low frequency mode of switching.
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  • 86
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    Developmental Genetics 9 (1988), S. 607-614 
    ISSN: 0192-253X
    Keywords: pattern formation ; cell sorting ; differential chemotaxis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: When cells dissociated from Dictyostelium discoideum slugs were cultured in roller tubes, they formed agglomerates in which prestalk cells were initially dispersed but soon sorted out to the center and then moved to the edge to reconstitute the prestalk/prespore pattern. To examine the mechanism of sorting out, individual prestalk cells were traced by a videotape recorder. The radial component of the rate of movement toward the center of the presumptive prestalk region was calculated. Prestalk cells did not move randomly, but rather directionally toward the center. Thei movement was pulsatile, with a period of ca. 15 min, and accompanied by occasional formation of cell streams, thus resembling the movement observable during cell aggregation. These results favor the idea that prestalk cells sort out to the prestalk region due to differential chemotaxis rather than differential adhesiveness. After formation of the prestalk/prespore pattern, the prestalk region rotated along the circumference of the agglomerates. This appears comparable to migration of slugs on the substratum, the rate of rotation being similar to that of slug migration.To examine the processes of pattern formation during development. washed vegetative cells were cultured in roller tubes. Prespore cells identified by antispore immunoglobulin initially appeared randomly within the agglomerates, but then nonprespore cells accumulated in the center and finally moved to the edge to establish the prestalk/prespore pattern, the processes being similar to those of pattern reconstruction with differentiated prestalk and prespore cells.
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  • 87
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    Developmental Genetics 9 (1988), S. 629-638 
    ISSN: 0192-253X
    Keywords: transposon ; cellular slime mold ; development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: PN6024 is a mutant strain of P. pallidum which appeared on selection for resistance to MDMP, an inhibitor of translation. It was found to be mutant in four other traits, being resistant to tubercidin, incapable of growth at 31.5°C, abnormal in development, and slow growing at 25°C. Genetic crosses using the macrocyst cycle showed that these five traits are controlled by five unlinked genes. The hypothesis is that movement of a transposon to multiple new locations caused these mutations. A difference in restriction fragment pattern between PN6024 and its parent PN600 support the hypothesis. Attempts were made to find conditions generating other strains like PN6024. Selection for growth in the presence of tubercidin yielded clones which resemble PN6024 in being developmentally abnormal as well as tubercidin resistant. Tubercidin treatment also increased the frequency of clones resistant to canavanine. It is suggested that tubercidin is mutagenic because it causes movement of the putative transposon, not because it generates point mutations. Growth under conditions of stress (at 31.5°C, at 8°C, in the presence of 2% ethanol) had at most an erratic effect in generating strains like PN6024.Three substrains appeared spontaneously in cultures of PN6024. These differed in developmental characteristics from each other and from the parent strain. It is suggested that they carry mutations in genes which control the choices between growth and aggregation, and between aggregation and encystment.
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  • 88
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    Developmental Genetics 9 (1988), S. 663-672 
    ISSN: 0192-253X
    Keywords: patterning ; reaction-diffusion ; slime mold ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The formation of secondary sori in whorls of Polysphondylium pallidum provides an attractive model system for the study of symmetry breaking during morphogenesis. Tip-specific antibodies that permit detection of very early stages in this patterning process are available. We have found that the patterns of tip-specific antigen expression vary considerably depending on the size, shape, and developmental stage of the whorl. All of these patterns, however, are well explained by patterning models that rely on short-range autocatalysis and long-range inhibition, as exemplified by reaction-diffusion theories. In the context of reaction-diffusion, we discuss the possible effects of initial conditions, boundary conditions, and nonlinearities on the selection of patterns in P. pallidum whorls.
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  • 89
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    Developmental Genetics 9 (1988), S. 673-681 
    ISSN: 0192-253X
    Keywords: cytokinesis ; phagocytosis ; adhesion ; cytoskeleton ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cellular slime mold amoebae have become a model system for the study of cell motility and the cytoskeleton. A basic problem which all cells face that involves the cytoskeleton is how to control their size. The varied ways in which cellular slime mold amoebae change their cell size-by changing the size at which division occurs, by cell fusion, and by control over cytokinesis-are reviewed. A model is presented which attempts to explain how the mechanisms affected in certain cytokinesis mutants in Dictyostelium discideum known as phg mutants could be involved in control of cell size in the predatory slime mold Dictyostelium caveatum.
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  • 90
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 4 (1988) 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 91
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    Yeast 4 (1988), S. 1-15 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 8 Ill.
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  • 92
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    Yeast 4 (1988), S. 27-40 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 4 Ill.
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  • 93
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    Yeast 4 (1988), S. 17-26 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 1 Ill.
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  • 94
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    Yeast 4 (1988), S. 41-46 
    ISSN: 0749-503X
    Keywords: Isocitrate lyase ; purification ; Catabolite inactivation ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Isocitrate lyase purified to homogeneity from Saccharomyces cerevisiae was composed of four identical subunits with a molecular mass 75 K Da. The enzyme was most active at pH 7.0 in the presence of 5 mM-Mg2+. The Km value for threo-Ds-isocitrate was 1.4 mM. Isocitrate lyase was shown to be thermostable at 50°C for 60 min at a high salt concentration, but rapidly lost activity at -20°C or by dialysis.
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  • 95
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 4 (1988), S. 83-83 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 96
    ISSN: 0749-503X
    Keywords: Bovine leukemia virus ; PH05 ; PGK ; tumor virus ; Saccharomyces cerevisiae ; viral antigens ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: DNA sequences of the envelop (env) gene of the bovine leukemia virus (BLV) were expressed in the yeast saccharomyces cerevisiae. Two yeast promoters, the responsible PH05 promoter and the constitutive PGK promoter, were used to construct four expression plasmids either a sequence of the surface antigen gp51 or a (gp51 + gp30) sequence.The expressed hetrologous gene products were characterized by Western blot analysis and competitive radio-immunoassay. By means of Northern blot analysis the steady-state level of env-specific mRNA was analysed.The highest expression rate was obtained from recombinant plasmid YEpSG 94 comprising a gp51 sequence - a 630 base pair fragment containing 70% of the gp51 but lacking the N terminus - as well as the PH05 promoter including PH05 signal sequence and the PH05 terminator. The recombinant gp51 was partially lycosylated but the PH05 signal peptide did not seem to be cleaved off. No immunoreactive material could be found in the periplasm or in the culture medium.By means of monoclonal antibodies directed against eight different epitopes of viral gp51, all for sequential antigenic determinants were detected in the AH 216(YEpSG 94) expression product.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 97
    ISSN: 0749-503X
    Keywords: Yeast ; Ribosomes ; Kluyveromyces ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In an adenine-requiring mutant strain of the yeast, Kluyveromyces lactis the intracellular content of ATP is one-third to one-fifth that in a protophic wild strain under growing conditions. The quantitatives difference becomes rather small in resisting stationary-phase cells. Temporary changes in the two-dimensional protein patterns of mutant ribosomes occur when the ATP content during the transition phase of growth. The transfer of exponentially growing cells to a synthetic complete medium void of adenine induces the same changes in mutant ribosomes within several hours. Identification of robosomal proteins by two-dimensional gel electrophoresis indicated all changeable proteins (at least five proteins) to belong to 40S ribosomal subunits. The mutant ribosomes prepared from the transitio-phase cells have much lower activity (below 60%) for poly(U)-directed polyphenylalanine synthesis than those in exponentially growing or resisting stationary-phase cells. Thus, changes in ribosomal components associated with the differences in ribosomes activity in a cell-free system were noted in the adenylate-deprived cells of K. lactix.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 98
    ISSN: 0749-503X
    Keywords: Kluyveromyces lactis ; killer DNA plasmid ; gene cloning ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The killer system of Kluveromyces lactis is associated with two linear DNA plasmids, pGKL1 and pGKL2. The killer toxin and the immunity determinant are coded for by pGKL1. Mutations which we have named KEX1. The KEX1 gene of K. lactis has been cloned by complementation of kex1 mutations by using a recombinant plasmid pool containing the entire Kluyveromyces lactis genome, on a multicopy plasmid KEp6, which contains the Saccharomyces cerevisiae URA3 gene as a marker. Genetic analyses of strains carrying a distrupted kex1 allele demonstrated that the cloned DNA corresponded to the KEX1 gene. The cloned KEX1 gene of K. lactis has low but significant sequence homology with the KEX2 gene of Saccharomyces cerevisiae. In vivo complementation of the kex1 mutations of K. lactis by the KEX2 gene of S. cerevisiae, and complementation of the kex2 mutations of S. Cerevisiae by the KEX1 gene of K. lactis, demonstrated that KEX1 of K. Lactis is functionally related to the KEX2 gene of S. cerevisiae. K. lactis diploids homozygous for kex1 are deficient for sporulation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 99
    ISSN: 0749-503X
    Keywords: Alcohol dehydrogenase ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The substrate specificity of alcohol dehydrogenase (ADH) from Hansenula polymorpha and Candida utilis has been compared with that of the classical ADH from baker's yeast. Cell-free extracts of H. polymorpha and C. utilis exhibited a much higher ratio of butanol to ethanol oxidation than baker's yeast ADH. This was also observed with the purified enzymes. The ratio of activities with ethanol and butanol was pH-dependent. With the baker's yeast enzyme the activity strongly decreased with increasing chain length, whereas the enzymes form H. polymorpha and C. utilis showed a high reactivity with long-chain alcohols. In addition, the affinity constant for ethanol was more than tenfold lower than that of the baker's yeast enzyme. The purified preparation yielded several protein bands on polyacrylamide slab gels, each of which showed activity with both ethanol and butanol.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 4 (1988), S. 155-155 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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