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  • Electronic Resource  (77)
  • 1990-1994
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  • 1984  (36)
  • 1981  (41)
  • Genetics
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  • Electronic Resource  (77)
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  • 1990-1994
  • 1980-1984  (77)
  • 1940-1944
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 62 (1984), S. 953-962 
    ISSN: 1432-1440
    Keywords: Purine metabolism ; Enzyme defects ; Molecular mechanisms ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An overview of inherited disorders of purine metabolism, concentrating on well established enzyme defects is given. Included are HPRT and the LNS, APRT and 2,8-dihydroxyadenine lithiasis, hyperactivity of PRPP synthetase, ADA and PNP and immunodeficiencies. Emphasis is put on underlying molecular mechanisms on the gene-, enzyme-, or metabolite level for a better understanding of the events leading from the genotype to the clinical phenotype. Finally some aspects of extracellular purine nucleotide metabolism catalyzed by cell surface-bound ectoenzymes are discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2072
    Keywords: Phenylethylamine ; Genetics ; Heritability ; Recombinant inbred strains ; Locomotor ; Amphetamine ; Schizophrenia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract β-Phenylethylamine (PEA) is an amphetaminelike compound that is postulated to be a possible endogenous psychotogen. We studied locomotor response to PEA in two inbred progenitor strains of mice (C57BL/6 By and BALB/c By), their reciprocal F1 hybrids (B6CF1 and CB6F1), and seven recombinant inbred strains (CXBD, CXBE, CXBG, CXBH, CXBI, CXGJ, and CXBK). Univariate and multivariate statistical analyses were done. Heritability of the response to PEA was 82%. The strain distribution pattern was suggestive of the inheritance of the trait through a single major gene locus.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Genetics ; blood groups ; acetylator phenotype ; blood glucose ; M value ; Type 1 diabetes ; Type 2 diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The acetylator phenotype and ABO blood groups were evaluated in 55 normal subjects and in 156 diabetic patients [61 with Type 1 (insulin-dependent) diabetes and 95 with Type 2 (non-insulin-dependent) diabetes]. The prevalence of fast acetylators was significantly higher in the Type 1 diabetic patients (53%) than in the control subjects (29%). In the Type 2 diabetic patients the prevalence was 39%, and thus not signifi cantly different from the control or Type 1 diabetic groups. In the Type 2 diabetic patients, but not in the control or in the Type 1 diabetic subjects, an association between the fast acetylator phenotype and the B blood group was found.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2072
    Keywords: Apomorphine ; Dopamine ; Stereotypy ; Hypomotility ; Roman High and Low Avoiders ; Genetics ; Dopamine receptors ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two experiments were carried out to investigate differences in the behavioural responses to “high” and “low” doses of apomorphine in two strains of rats selectively bred for high and low avoidance on a two-way active avoidance task: the Roman High and Low Avoiders. Significant strain differences were found in the stereotypy resulting from a high dose of apomorphine (2 mg/kg s.c.). In a second experiment no strain differences were, however, apparent for the hypomotility produced by low doses of the drug (0.05 mg/ kg s.c.). Pretreatment with a low dose of apomorphine had no effect on the stereotypy response when the animals were subsequently retested with the high dose. These results may indicate differential sensitivities of dopamine receptors in these strains.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2242
    Keywords: Triticum aestivum L. ; Doubled-haploids ; Genetics ; Androgenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plants of three common wheat (Triticum aestivum L. em. Thell) cultivars and one randomly selected doubled-haploid line derived by anther culture from each of the three cultivars were each grown in three environments, a field environment, a greenhouse environment, and a growth chamber environment. Anthers containing largely miduninucleate to late uninucleate microspores were cultured and calli were induced to regenerate plants in order to assess the effects of cultivar, cultivar family (cultivar and corresponding doubled-haploid derivative), anther-donor plant environment, and cultivar X environment interaction on androgenic responses. Large differences in response were observed among cultivars as well as between cultivars and doubled-haploids. Differences between cultivar and doubled-haploid within cultivar family usually resulted from higher frequency of response in the cultivar, contrary to the hypothesis that anther culture per se constitutes a general selective device for superior androgenic responses. Also, in a second experiment, anther callusing frequency was greater in the cultivar ‘Kitt’ than in any of five unique doubled-haploid lines derived from ‘Kitt’. Significant effects were also observed in the first experiment for the interactions of cultivar family X environment as well as doubled-haploid vs. cultivar X environment, although the effect of environment itself was less significant than these interactions.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 67 (1984), S. 97-111 
    ISSN: 1432-2242
    Keywords: Genetics ; Nitrogen ; Grain crops ; Selection ; Plant breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary It is necessary to increase protein productivity of grain crops to meet present and future world protein requirements. Conventional plant breeding methodology has been to select genotypes with enhanced yield or grain protein concentration. In addition to this determination of end product, we suggest measurements of a number of physiological and biochemical processes of nitrogen (N) metabolism which precede plant maturity as selection criteria for enhanced N metabolism and grain crop productivity. The measurement across the growing season of genotypic variation in components of N metabolism would constitute a physiological/biochemical selection program to be incorporated with the determination of harvestable end product. A properly designed physiological/biochemical selection program would integrate the effects of plant genotype, environment, and their interactions allowing identification of the factors limiting productivity of particular genotypes, and would also estimate end product. Our review of literature pertinent to whole plant N metabolism suggests that such a selection program initially include NO 3 - uptake, N2 fixation, N accumulation, N remobilization, seed protein synthesis, and Nitrogen Harvest Index.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 69 (1984), S. 15-21 
    ISSN: 1432-2242
    Keywords: Genetics ; Heat tolerance ; Thyroid function ; Chickens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Five experiments were conducted to assess the genetic variation in thyroid function (T3, T4), body weight and heat stress survival time in chickens. Thyroxine (T4) levels were found to be elevated in response to 4 and 8 μg bovine thyroid stimulating hormone (TSH) in experiment I. In experiment II, 4 μg of TSH was injected into chickens from 30 sire families of the Athens-Canadian Randombred population. The heritability of T4 levels after TSH injection was high. In experiment III, families identified as having innate high or low T4 levels after TSH injection and a group of control birds were subjected to a heat Stressor of 50 °C for up to 240 min at six weeks of age and heat stress survival time was studied. The groups did not differ from each other in heat stress survival time. Experiment IV was similar to experiment I except triiodothyronine (T3) was also measured after TSH injection. Both T4 and T3 levels after TSH injection were moderately heritable. In experiment V birds were reared to six weeks of age and heritability calculated for body weight, T4, T3, and heat stress survival time. Heritabilities were high for body weight, moderate for T4 and heat stress survival time, and low for T3. Phenotypic correlations were significant and negative for heat stress survival time with body weight and T4, and for body weight with T3 after TSH. Significant positive correlations were found for T4 with T3 after TSH and also T4 and body weight. Analysis of genetic correlations suggested that none of the traits studied would be an adequate selection parameter for achieving heat tolerance without reducing body weight.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 1-25 
    ISSN: 0192-253X
    Keywords: maize ; endosperm ; mutants ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 43-58 
    ISSN: 0192-253X
    Keywords: ciliate genetics ; Tetrahymena malaccensis ; karyonidal inheritance ; macronuclear assortment ; selfing ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mating type determination in Tetrahymena malaccensis is karyonidal, ie, the four new macronuclei developing in a single conjugating pair are independently determined as to which of the six known mating types they will express. Occasional selfing clones are similar to those in T thermophila, in that any one is capable of stabilizing at a restricted range of mating types. The genetic basis of mating type potentialities is incompletely resolved. T malaccensis may, like T thermophila and T canadensis, have a single multiallelic locus that controls the array of types. Quantitative considerations suggest, however, that other loci may be involved.
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 83-91 
    ISSN: 0192-253X
    Keywords: temporal genes ; acid hydrolases ; liver ; mice ; hepatocytes ; nonhepatocytes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The cell specificity of expression of three distinct trans acting temporal gene systems determining the developmental control of α-galactosidase, β-galactosidase and β-glucuronidase was tested in mouse liver. For α-galactosidase and β-galactosidase, expression was limited to hepatocytes; no effect was seen in nonhepatocytes. For β-glucuronidase the data suggest that expression of the Gus-t temporal locus is also limited to hepatocytes, and that the smaller enzyme reduction seen in nonhepatocytes of some strains is due to a separate systemic regulatory locus that is also present in the [Gus] gene complex. We conclude that the temporal gene-determined timing mechanisms initiating switches in rates of enzyme synthesis are intrinsic to the cells themselves and are not communicated to adjacent cells. This conclusion applies to the temporal locus for β-glucuronidase that is proximate to its structural gene as well as those for α-galactosidase and β-galactosidase that are distant from the structural genes that they regulate.
    Additional Material: 5 Tab.
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  • 12
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 117-127 
    ISSN: 0192-253X
    Keywords: temporal-regualatory variation ; isocitrate dehydrogenase ; rainbow trout ; Salmo gairdneri ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We examined a temporal series of embryos from 14 full-sib families of rainbow trout with starch gel electrophoresis to determine the time of initial detection of enzyme produced by ldh-3. Maternal enzyme was detected in unfertilized eggs, whereas paternal alleles showed evidence of initial expression after gastrulation and epiboly. Two alleles, 40 and 71, were expressed synchronously several days before the 114 allele. Measurement of enzyme activity by spectrophotometric analysis and serial dilution supported these observations. The degree of delay of expression of the 114 allele between families was coupled with other estimates of developmental rate. These data suggest the existence of allelic variation at a cis-acting genetic element controlling the pattern of ontogenetic expression of structural alleles at Idh-3.
    Additional Material: 2 Ill.
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  • 13
    ISSN: 0192-253X
    Keywords: Drosophila melanogaster ; ts-mutants ; adenylate cyclase ; Phosphodiesterase ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The mode of the developmental expression of adenylate cyclase (AC) and phosphodiesterase (PDE) in D melanogaster indicates that PDE plays the major role in the maintenance of a certain level of cAMP in postembryonic development, while both enzymes function in concert in imago. The ts-mutants ts155 and ts622, characterized upon their isolation as having an increased cAMP content and normal PDE activity, manifest high levels of AC activity from the third day of imago life. The levels of PDE activity characteristic for adult mutants with altered enzyme activity (low in ts66 and ts980, high in ts398) are manifested in ts980 from larval instar II, and from the larval instar III in ts398 and ts66. Data on the dependence of PDE activity in adults upon temperature of incubation, being in agreement with the expectations for a ts-mutation in a gene coding for a form of PDE in case of ts66, suggest that ts398 affects not the enzyme-coding gene but rather one for an activator protein. The fact that in ts398 (the polyphasic ts-lethal mapping to 1-38.9) 1) AC activity is somewhat higher than normal at 22°C and is readily activated at 29°C, 2) activity of PDE-I assayed in heat-pretreated homogenates is higher than normal, 3) that boiled extracts of ts398 are potent activators of the wild type and of its own PDE-I indicates that it is a mutation affecting calmodulin, which is known to be stable at boiling and capable of activating both AC and PDE-I. Data on Ca2+ and EGTA effects suggest that the mutation presumably increases Ca2+-binding activity of calmodulin, ts980 and ts622, in which ts-lethality could be produced only by certain doses of haloperidol and triftazine, appear to be lethal in compounds with ts398, thus indicating that these mutations could affect the same calmodulin-controlling gene.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 201-207 
    ISSN: 0192-253X
    Keywords: rDNA ; compensation ; rRNA-DNA hybrids ; restriction analysis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The compensatory response is a regulatory event influencing the redundancy of the ribosomal RNA cistrons (rDNAs) of Drosophila melanogaster. In this report we attempt to demonstrate that the compensatory event and the thymidine analogue bromodeoxyuridine (BrdU) specifically interact. We conclude that the drug inhibits the compensatory response of Drosophila melanogaster XO males and argue that the compensatory event is not the passive consequence of replicational dominance known to occur in Drosophila polytene tissues.
    Additional Material: 2 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 239-239 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 0192-253X
    Keywords: gonad differentiation ; gene expression ; two-dimensional micro gel electrophoresis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Gonadal protein patterns were studied during development in the rat by two-dimensional micro-gel electrophoresis. Specific proteins were detected in both the male and the female sex at the morphologically indifferent state (two female- and one male-specific) and during differentiation. At the onset of gonadal differentiation (day 14) two additional sex-specific proteins were discovered in the male and two in the female. These proteins remained expressed during further development. One testicular protein was restricted to the cytosol of the tunica albuginea. The other one was absent from the tunica. In the female gonad, the two proteins were membrane-specific, one present in germ cells, the other in somatic cells. In the testis, one additional protein was discovered at postnatal day 1. Thus according to biochemical criteria there is no indifferent state of gonadal development. The testis and ovary express sex-specific genes both before and after the onset of gonadal differentiation.
    Additional Material: 8 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 93-102 
    ISSN: 0192-253X
    Keywords: pattern formation ; cell-lethal mutations ; imaginal discs ; cell death ; pattern triplications ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effects of 48-hr 29°C temperature treatments on the imaginal leg discs of Drosophila hemizygous for a temperature-sensitive cell-lethal mutation were examined to determine whether the induction of patches of cell death in the imaginal discs is a prerequisite for the induction of pattern triplications. In a statistical analysis, the frequency of induction of cell death was found to be highly correlated with the frequency of induction of triplications. In addition, individual discs in which cell death had been induced were cultured and found to triplicate at frequencies significantly greater than discs with no visible cell death, or unselected discs from the same larvae.
    Additional Material: 3 Ill.
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  • 18
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 103-114 
    ISSN: 0192-253X
    Keywords: Drosophila ; pupation ; larval moults ; Lethalcryptocephal ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The events of normal pupation in Drosophila melanogaster are described in detail from the time of gas bubble expulsion until the completion of pupation with the eversion of the cephalic complex. The importance of the internal gas bubble for posterior movement of the prepupa is examined and its relation to the expulsion of the larval mouthparts and the creation of the anterior gas space described.The phenotype of lethalcryptocephal homozygotes, which characteristically cannot evert their heads, is re-examined. Observations of larval lethality and multiple mouthparts in 1 (2)crc larvae and pupae are described. These new aspects of the mutant phenotype are discussed with respect to the abnormalities of pupation. Fristrom's hypothesis that the basic mutant lesion is an increased stiffness of the pupal cuticle due to an excess chitin deposition is re-evaluated.
    Additional Material: 5 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 173-175 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 179-180 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 21
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 219-225 
    ISSN: 0192-253X
    Keywords: actin ; gene regulation ; development ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Extreme and rapid changes in the synthesis of messenger RNAs and proteins accompany differentiation in wing tissues of Drosophila. Of the six actin genes, at least three are expressed in wing cells, some during the most extreme changes in cell shape. However, different messages of the set appear, decay, and reappear on a regulated temporal program. These results show that actin expression is stage-specific in a single cell type.
    Additional Material: 3 Ill.
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  • 22
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 115-116 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 23
    ISSN: 0192-253X
    Keywords: Tetrahymena ; Paramecium ; mating type differentiation ; intranuclear coordination ; macronuclear molecular cloning ; ARF ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mating type determination in Tetrahymena thermophila involves developmentally programmed, heritable alterations of the macronucleus, localized to the mtd locus. This determination can be predictably controlled by the environmental conditions during macronuclear development, eg, temperature and time of refeeding. In this article we have further characterized the effects of delayed refeeding on mating type determination, as revealed by the frequency of mating types among the progeny of a cross. Our results show that 1) the magnitude of this starvation effect decreases with temperature of conjugation and becomes undetectable at 18°C; 2) starvation during the interval 14 to 22 hr (after conjugation is induced at 30°C) is a necessary and sufficient condition for the induction of starvation effects; 3) relative mating type frequencies vary monotonically with nutrient concentration present during this critical period; and 4) sister macronuclei, developing under starvation conditions in the same cytoplasm, differentiate majority mating types characteristic of early or late refeeding; sister macronuclei show no apparent correlation with each other. On the basis of our observations on early and late refed cells, we propose that the composition of the newly developed macronucleus is the outcome of two key events: 1) mating type determination at the mtd locus and 2) differential molecular cloning of generally one or two autonomously replicating fragments (ARFs) of the macronuclear DNA bearing the mtd locus.
    Additional Material: 5 Ill.
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  • 24
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 63-63 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 25
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 73-82 
    ISSN: 0192-253X
    Keywords: axolotl ; isozymes ; phosphoglucomutase ; esterase ; G-K mapping ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Four isozyme systems were surveyed in our laboratory-bred colony of axolotls (Ambystoma mexicanum) to determine whether there were elecrophoretic variants that could be used as markers in developmental experiments. For malate dehydrogenase (MDH), lactate dehydrogenase (LDH), and phosphoglucomutase (PGM), the best separations were obtained by isoelectric focussing on polyacrylamide slab gels, whereas for soluble esterases (Est), conventional polyacrylamide gel electrophoresis was used. The patterns for both MDH and LDH were consistent with two-locus models, but no variation was obtained. The results for PGM support a single-locus model with two alleles that are expressed codominantly in heterozygotes. There is also evidence for a third, null allele. The pgm gene maps approximately 24 map units from its centromere. The majority of the animals tested produced four esterase bands. We propose that each is controlled by a separate locus. One of the bands, Est-3, is absent in some animals. The results of various crosses support the proposition that these animals are homozygous for a null allele. The est-3 gene is distant from its centromere.
    Additional Material: 2 Ill.
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  • 26
    ISSN: 0192-253X
    Keywords: 5S ribosomal RNA genes ; rearrangement ; macronuclear development ; macronuclear replication ; Tetrahymena thermophila ; determination ; phenotypic assortment ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The organization of the 5S rRNA genes in the MACronuclear genome of Tetrahymena thermophila was examined during MAC development and replication. The 5S genes are arranged in several tandem arrays of alternating transcribed and spacer sequences in both MICronucleus and MAC. The number of EcoRI fragments bearing 5S gene clusters is similar in MIC and MAC. Most fragments occur in both the MIC and newly formed MAC genomes, a few being MIC-limited and a few MAC-limited. The same rearrangements are seen in the MACs of all four caryonides of a mating pair, and most rearrangements are seen in the newly formed MACs of different inbred strains. During replication of the MAC about half the fragments bearing 5S gene clusters disappear in different cell lines, and new fragments containing 5S genes appear. These fragments differ in size from those present in the MIC or newly formed MAC. These alterations occur in the MACs of all strains except strain B, which is more resistant to vegetative rearrangement. The losses and gains of fragments occur during clonal propagation of cell lines. The process begins by 35 fissions following conjugation, but once an alteration occurs, it is stably propagated. Clonal variation occurs with respect to which losses and gains occur, although a nonrandom distribution is seen among cell clones. We conclude that the alterations in MAC fragment size occur at two stages in the life cycle of Tetrahymena. The first stage occurs during conjugation, when the MAC develops from the MIC. The second stage becomes manifest during vegetative growth, when DNA replication occurs in the MAC and daughter molecules are distributed “amitotically” to daughter nuclei. The two-stage character to MAC alterations for the 5S genes is interpreted in terms of the two steps previously described for MAC differentiation: determination and phenotypic assortment. Possible molecular mechanisms are also discussed.
    Additional Material: 5 Ill.
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  • 27
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 129-140 
    ISSN: 0192-253X
    Keywords: avian developmental antigens ; hybrids ; erythroid subpopulations ; species restriction ; monoclonal antibodies ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Monoclonal and polyclonal antibodies were used to examine the expression of three erythroid developmental antigen systems in the chicken, Japanese quail, and quail-chicken hybrid. Chicken fetal antigen (CFA), quail fetal antigen (QFA), and chicken adult antigen (CAA) each represent a series of cell-surface glycorproteins associated with the development of avian hematopoietic cells. Monoclonal anti-CFA antibodies from clones 190-4 and 288-1.1.1.2 supernatants were shown to react against epitopes associated with CFA determinants 8 and 2, respectively. Using complement-mediated microcytotoxicity, these reagents permitted the identification of different erythroid subpopulations in the neonatal chicken and hybrid; therefore, heterogeneity in cell surface CFA determinants among mature peripheral erythrocytes should serve as a useful tool for analyzing erythroid development. In the case of CAA, erythrocytes from adult hybrids were found to express the same complement of CAA determinants identified in the chicken, and CAA appeared much earlier in the hybrid than in either of the parental species. Similarly, two species-restricted fetal antigens associated with similar glycoproteins, CFA8 and QFA, had similar developmental profiles in their respective species, the chicken and quail. In contrast, these antigens were dominantly expressed but exhibited different developmental profiles on erythrocytes from the hybrids. While quail-chicken hybrids exhibited apparent genomic interactions in the expression of these developmental antigens, no evidence for the existence of hybrid-specific fetal antigens was obtained.
    Additional Material: 4 Ill.
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  • 28
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 29
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 227-238 
    ISSN: 0192-253X
    Keywords: centriole ; mitotic center ; myxomycete ; Physarum ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Amoebae of the Myxomycete Physarum polycephalum in the interphase state typically contain only one proflagellar apparatus in which the anterior kinetosome (anterior centriole) is attached to the microtubule organizing center 1 (mtoc 1). We built strains possessing more than one mtoc 1 and a variable number of anterior centrioles to allow the appearance of new structures. In 8% of the amoebae of these strains, the 1:1 attachment between the anterior centriole and the mtoc 1 is not always respected. In nine cases studied using tridimensional reconstructions from ultrastructural thin sections, the pattern of attachment was more complex. A mtoc 1 could be linked to several anterior centrioles, and/or reciprocally an anterior centriole could be linked to several mtoc 1. In one case, an anterior centriole was not linked to a mtoc 1 and in three cases, a single centriole exhibited anterior and posterior characteristics. These observations suggest that (1) each pair of centrioles constitutes a morphological and physiological entity that is distinct from the mitotic center (mtoc 1); (2) the attachment of the anterior centriole to the mtoc 1 occurs at the end of each mitosis; (3) there is an inductory process during the morphogenesis of the link between the anterior centriole and the mtoc 1; (4) the anterior characteristics of a centriole can be present in the absence of the link with the mtoc 1; (5) the anterior and posterior characteristics of a centriole are not exclusive of each other, ruling out the existence of a lineage corresponding to the anterior centriole and a lineage corresponding to the posterior centriole; and (6) the differences between anterior and posterior centrioles result from a maturation process.
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 31
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 32
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 65-71 
    ISSN: 0192-253X
    Keywords: BrdU ; rDNA ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We demonstrate that Bromodeoxyuridine (BrdU)-induced reductions of the ribosomal RNA cistrons (rDNAs) are observed in Drosophila virilis, and Drosophila busckii, but not in karyotypically normal adults or larvae of Drosophila melanogaster. However, BrdU does reduce the redundancy of the rDNAs of XO D melanogaster males, in which a compensatory response is evidenced in the untreated XO sibling controls. These results suggest that the BrdU-rDNA interaction is specific to events which modulate rDNA redundancy. Further, both thymidine and deoxycytidine “reverse” the BrdU effect in D virilis, an observation which is inconsistent with current working hypotheses describing the mechanisms of BrdUs effects.
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  • 33
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 177-177 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 34
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 209-217 
    ISSN: 0192-253X
    Keywords: chick blastula ; epiblast-hypoblast interaction ; protein pattern ; primitive streak induction ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The patterns of protein synthesis are examined in the hypoblast and in the areas that comprise the epiblast, that is, the area opaca, the marginal zone, and the central area, during the blastula stage which marks the beginning of the interaction between the epiblast and hypoblast for induction of the primitive streak. The results demonstrate that there are distinct qualitative and quantitative differences in protein patterns in individual areas of blastoderm, the differences being most distinct between the hypoblast and any of the component areas of the epiblast. These differences in patterns of proteins suggest that the component areas of the chick blastula have already diverged to different developmental fates before any apparent morphogenetic differentiation, that is, the appearance of the primitive streak.
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  • 35
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 243-244 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 36
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 37
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    Journal of molecular evolution 17 (1981), S. 167-181 
    ISSN: 1432-1432
    Keywords: Evolution ; Genetics ; REH theory ; Mutations ; Natural selection ; Nucleic acids ; Proteins ; Paleogenetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have independently repeated the computer simulations on which Nei and Tateno (1978) base their criticism of REH theory and have extended the analysis to include mRNAs as well as proteins. The simulation data confirm the correctness of the REH method. The high average value of the fixation intensity μ2 found by Nei and Tateno is due to two factors: 1) they reported only the five replications in which μ2 was high, excluding the forty-five replications containing the more representative data;and 2) the lack of information, inherent to protein sequence data, about fixed mutations at the third nucleotide position within codons, as the values are lower when the estimate is made from the mRNAs that code for the proteins. REH values calculated from protein or nucleic acid data on the basis of the equiprobability of genetic events underestimate, not overestimate, the total fixed mutations. In REH theory the experimental data determine the estimate T2 of the time average number of codons that have been free to fix mutations during a given period of divergence. In the method of Nei and Tateno it is assumed, despite evidence to the contrary, that every amino acid position may fix a mutation. Under the latter assumption, the measure X2 of genetic divergence suggested by Nei and Tateno is not tenable: values of X2 for theα hemoglobin divergences are less than the minimum number of fixed substitutions known to have occurred. Within the context of REH theory, a paradox, first posed by Zuckerkandl, with respect to the high rate of covarion turnover and the nature of general function sites in proteins is resolved.
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  • 38
    ISSN: 1432-069X
    Keywords: Genetics ; Hair dysplasia ; Scanning electron microscopy ; Uncombable hair syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 39
    ISSN: 1432-0983
    Keywords: Protoplast ; Fusion ; Mitochondrial ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using a protoplast fusion technique we have been able to locate to the mitochondrial genome of the asporogenous yeast Torulopsis glabrata mutations conferring resistance to oligomycin, antimycin and diuron. When two strains differing in the size of their mtDNAs were fused the mitochondrial markers from the parent with the larger mtDNA (71–91) were transmitted predominantly among the fusion products. Both genetical and physical evidence support the occurrence of recombination in T. glabrata mitochondrial genome. Segregation of the mitochondrial genome appears to take place before the separation of the first bud from the fusion product.
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  • 40
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    Current genetics 4 (1981), S. 177-180 
    ISSN: 1432-0983
    Keywords: Genetics ; Yeasts, protoplasts ; Saccharomyces ; Hansenula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protoplasts of petites of strains 625-CI of Saccharomyces diastaticus and NCYC 1085 of Saccharomyces cerevisiae, originally obtained from the National Collection of Yeast Cultures, England, were fused with protoplasts of Candida pseudotropicalis, Saccharomyces rosei, Yaccharbmycesmontanus, Pichiamembranefaciens, Hansenula anomala, Hansenula capsulata, and Schizosac-charomyces pombe. The respiratory-competent products of the fusions were selected on the basis of using at least one of the carbon sources utilized by the petite parent and not by the other. The products of the fusion of C. pseudotropicalis x 1085(p−) consisted of two cell types; an oval cell which utilized both lactose and maltose and fermented lactose vigorously, and a cylindrical form which fermented maltose slowly. The S. rosei x 1085(p−) hybrids had acquired the ability to metabolize and ferment galactose, and to ferment maltose, from the petite parent. The P. membranaefaciens x 625(p−) hybrids acquired the ability to metabolize galactose, sucrose and maltose, but fermented only glucose, weakly, like the P. membranaefaciens parent strain. The H. capsulate x 625(p−) hybrids, unlike the hybrids with P. membranaefaciens or S. rosei, resembled the petite parent morphologically and also had the fermentative abilities of this strain (galactose, maltose, sucrose and starch), and the ability to ferment starch was considerably enhanced. The S. montanus x 625(p−) hybrids acquired the ability to utilize starch. Schizosaccharomyces pombe x 625(p−) hybrids resembled S. pombe morphologically, but had the ability to metabolize galactose and starch. Some of the asci produced by these hybrids contained abnormal numbers of spores. H. anomala x 624 x(p−) hybrids fermented starch, though weakly.
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    Theoretical and applied genetics 60 (1981), S. 229-236 
    ISSN: 1432-2242
    Keywords: Glutenin ; Triticum ; Genetics ; SDS ; Polyacrylamide-gel-electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The high-molecular-weight (HMW) subunits of glutenin from about 185 varieties were fractionated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). About 20 different, major subunits were distinguished by this technique although each variety contained, with only a few exceptions, between 3 and 5 subunits. Further inter-varietal substitution lines to those already described (Payne et al. 1980) were analysed and the results indicate that all the HMW subunits are controlled by the homoeologous group 1 chromosomes. All hexaploid varieties studied except ‘NapHal’ contained two major subunits controlled by chromosome 1D. Their genes were shown to be tightly linked genetically for only four different types of banding patterns were observed. The nominal molecular weights determined after fractionation in 10% polyacrylamide gels were between 110,000 and 115,000 for the larger of the two subunits and between 82,000 and 84,000 for the smaller. One quarter of the varieties contained only one major HMW subunit controlled by chromosome 1B whereas the rest had two. The chromosome 1B subunits were the most varied and nine different banding patterns were detected. All the subunits had mobilities which were intermediate between those of the two chromosome 1D-controlled subunits. Only two types of HMW subunit controlled by chromosome 1A were detected in all the varieties examined; a single variety never contained both of these subunits and 40% of varieties contained neither. The chromosome 1A-controlled subunits had slightly slower mobilities in 10% gels than the largest HMW subunit controlled by chromosome 1D. About 100 single grains were analysed from each of five different crosses of the type (F1 of variety A × variety B) × variety C. The results indicate that the genes on chromosome 1B which control the synthesis of subunits 6, 7, 13, 14 and 17 are allelic, as are the genes of the chromosome 1A-controlled subunits, 1 and 2.
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  • 42
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    Theoretical and applied genetics 60 (1981), S. 265-268 
    ISSN: 1432-2242
    Keywords: Agrocybe ; Genetics ; Fruiting ; Biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the edible white rot fungus Agrocybe aegerita the threshold from mycelial growth to fruit body formation is under control of a single gene in both monokaryons and dikaryons. The allele su opens the pathway for fruiting and allows the subsequent expression of the fruiter genes fi+ (fruit body initials) and fb + (fruit bodies). Its allele, su +, suppresses monokaryotic fruiting completely and restricts dikaryotic fruiting drastically. The detection of this threshold gene su +/su and its action and interactions has practical implication in that an opportunity for concerted breeding is created. First results indicate that the fruiter genes are involved in two essential parameters of productivity. Both time of fruiting and biomass production depend on the two fruiter genes fi + and fb +. Comparable results obtained with two other basidiomycetes suggest that the genetic control of fruiting in Agrocybe aegerita is a general mechanism which may be made use of in breeding work with other basidiomycetes of economic value.
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  • 43
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    Environmental biology of fishes 6 (1981), S. 357-360 
    ISSN: 1573-5133
    Keywords: Behaviour ; Esterase ; Evolution ; Genetics ; Isozymes ; Stock structure ; Schools ; Starch gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Heterogeneous gene frequencies of Est-1 across groups ofNotropis cornutus provide evidence of behaviourally imposed restrictions on stock structuring. Positive fixation indices (F1S = 0.056 and F1T = 0.085) were reflected by a deficiency of heterozygotes for pooled groups. The degree of subdivision ofN. cornutus stocks cannot be evaluated with the present evidence. but it is likely that their schooling behaviour is associated with significant genotypic structuring of the species.
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  • 44
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 2 (1981) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 45
    ISSN: 0192-253X
    Keywords: nuclear differentiation ; cytoplasmic inheritance ; Paramecium tetraurelia ; mating type ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In P. tetraurelia each cell is determined to express only one of the two complementary mating types, O and E. This determination is under cytoplasmic control and seems to be achieved only by the commitment or noncommitment to the expression of mating type E. All the previously known mutations affecting the differentiation of mating type prevent the expression of the E mating type (O-restricted mutations) without affecting the determination process. An E-restricted mutation was obtained: mtFE. Its phenotypic properties indicate that the mutation affects the determination process itself. When an O cell becomes mtFE/mtFE it acquires the E mating type and an E-determining cytoplasm. We propose that this constitutive determination for the E mating type is due to the inefficiency of a factor which is normally active in an O cell. This factor would act like a repressor and stabilize the E functions under an inactive state.
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  • 46
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    Developmental Genetics 2 (1981), S. 279-290 
    ISSN: 0192-253X
    Keywords: temperature-sensitive mutant ; cytokinin ; hormonal metabolism ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Developmental controls of morphological mutants of Phaseolus vulgaris L. conditioned by two independent loci, DL1 and DL2, were examined through grafting experiments and hydroponic studies. Phenotypes of mutant classes were duplicated by unions of scions and stocks derived from different genotypes. Results indicate that DL1 and DL2 regulate a root and shoot factor respectively, contributing to the mutant types. The allelic dosages of DL1 in the root and DL2 in the shoot rather than the genotype of the whole plant per se determine the severity of the mutant expression. Plants heterozygous for both loci with a temperature-sensitive expression of the mutant phenotype were used to determine physiological components involved. The primary abnormal developmental event associated with the appearance of mutant phenotypes, the restricted root growth at high temperature, could be overcome by the addition of cytokinin in hydroponic solution. These observations suggest that DL1 and DL2 may be related to the regulation of hormonal function or metabolism.
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  • 47
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 2 (1981) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 48
    ISSN: 0192-253X
    Keywords: suspensive and adhesive teratoma cells ; teratoma embryoid bodies ; cell differentiation ; endogenous prostanoid biosynthesis ; long-chain fatty acyl CoA derivatives ; mass fragmentography ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Attachment of the cell surface to a substratum may play a critical role in initiating some cellular developmental commitments and in sustaining differentiation of cells that have already been specialized. Embryoid bodies of teratoma OTT6050 were divided, on day 10 of initial culture, into myogenic adhesive cells which were already (at day 6) characterized by endogenous prostaglandin (PG)I2 formation and little-specialized suspensive cells which formed only thromboxane (TX)B2 in the same culture system. Since at day 10 both cell types reached a stationary phase in which the nature of each cell was mature enough for the analyses with mass fragmentographic technique and gas chromatography- mass spectrometry (GCMS), the total levels of predominant long-chain fatty acyl CoA (acyl CoA) derivatives could be measured comparatively as methyl esters after methanolysis. It was found as a result of major differentiation that adhesive cells had a rather low ratio of arachidonyl CoA to stearyl CoA, although adhesive cells accumulated a larger total amount of acyl CoA derivatives than that accumulated in suspensive cells.
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  • 49
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    Developmental Genetics 2 (1981), S. 99-111 
    ISSN: 0192-253X
    Keywords: CIPC as a mitotic inhibitor of Dictyostelium ; inhibition of Dictyostelium development by CIPC ; CIPC-resistant mutants ; Dictyostelium ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The anti-mitotic herbicide isopropyl N-(3-chlorophenyl) carbamate (CIPC) prevents the growth of amoebae of Dictyostelium discoideum without killing the cells for a period of time equivalent to one generation. During in-hibition, amoebae accumulate in prophase and metaphase of mitosis. After removal of CIPC, they continue through mitosis and then divide.The addition of CIPC to amoebae under starvation conditions prevents aggregation and concomitant cell elongation. The cells, however, do not lose their ability to adhere to a surface, and they remain viable. When CIPC is added to amoebae which have formed streams, it leads to the disintegration of streams into small clusters of cells and to a loss of cell elongation.Post-aggregation stages of development can be inhibited by CIPC at the mound, slug, or Mexican hat stages. Slugs break apart into distinct aggregates.Mutants resistant to CIPC can be obtained easily. Among these mutants, many become temperature sensititive for growth (27°C) or development (27°C or 15.5°C). Others show various abnormalities at the normal temperature (22°C). Most mutants are cross resistant to the microtubule inhibitors nocodazole and thiabendazole, and some are also resistant to CIPC during development.
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  • 50
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    Developmental Genetics 2 (1981), S. 147-158 
    ISSN: 0192-253X
    Keywords: triplo-lethal locus ; Tpl ; gene-dosage ; X chromosome ; Drosophila melanogaster ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Only a single locus (Tpl) is known in the Drosophila melanogaster genome that leads to early lethality when present as a heterozygous duplication (three doses) or deficiency (one dose). We report the recovery of third instar larvae (and of occasional adults) carrying a duplication for the triplo-lethal locus, Dp(Tpl). Karyotype analysis of the larvae showed that the individuals surviving were almost entirely 3X;2A metafemales. We examined the question of whether the entire X or a single X locus was a major factor permitting survival. X-Y translocations were used to produce females hyperploid for different portions of the X and carrying Dp(Tpl). Analysis of metaphase chromosomes by quinacrine fluorescence pattern indicates that the X chromosome region between 6D and 7DE must be present in an extra copy to enhance the survival of Tpl duplication-bearing females. Another type of experiment suggests that it is the region between 7C and 7DE which is essential.
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  • 51
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    Developmental Genetics 2 (1981), S. 131-146 
    ISSN: 0192-253X
    Keywords: rat chimeras ; hooded pigmentation ; melanocyte ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: New, improved media and procedures for making rat chimeric embryos and culturing them in vitro have been developed. We have produced 27 rat chimeras: 20 males and 7 females. This ratio of males to females is consistent with that seen in mouse chimeras, suggesting that rat sex chimeras develop as phenotypic males. By aggregating embryos containing appropriate genetic markers for pigment cell differentiation, it is possible to produce chimeras that elucidate the site of action of the hooded gene. The coat color patterns of black ↔ black hooded chimeras display a white belly spot. In black ↔ albino hooded chimeras, small patches of white hair appear on the head and a large white spot occurs on the belly. Black ↔ agouti hooded chimeras display both agouti and nonagouti pigmentation over the entire surface of the chimera. These animals are fully pigmented with no white spots. In black ↔ albino non-hooded chimeras, rather small irregular patches of black and white hairs are distributed throughout the pelage. Histological examination of sections of hair follicles obtained from the white areas in the head of black ↔ albino hooded chimeras revealed amelanotic melanocytes. On the other hand, hair bulbs from the white belly spots do not contain any such melanocytes. Thus the white hairs of the head are due to the presence of albino melanocytes, but the white hairs of the belly are due to the total absence of melanocytes. All these observations are consistent with the conclusion that the hooded gene acts within melanoblasts, probably to retard their migration from the neural crest and/or to prevent their entrance into the hair follicles of the white areas of hooded rats.
    Additional Material: 7 Ill.
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  • 52
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    Developmental Genetics 2 (1981), S. 171-183 
    ISSN: 0192-253X
    Keywords: sperm ; F9 antigen ; T/t-complex ; immunolabeling ; scanning electron microscopy ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The antigens defined by conventional syngeneic antiserum against F9 embryonal carcinoma cells were localized on mature sperm using immunolabeling and scanning electron microscopy. Labeling patterns were compared for normal (+ / +) mice and mice bearing recessive t-haplotypes. The results showed that antigens detected by intact anti-F9 antiserum are expressed similarly in all genotypes, except for sperm from mice bearing the t12-haplotype where the frequency of labeled cells was reduced. Labeling with the IgM fraction of anti-F9 antiserum was lower on sperm from all t-genotypes examined, with sperm from + /t12 males showing the most marked reduction. In all cases, the labeling patterns were similar, and included a labeling of the whole sperm head with complete anti-F9 antiserum and a restriction of the label to the postacrosomal region when the IgM fraction was used.
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  • 53
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    Developmental Genetics 2 (1981), S. 219-222 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 54
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    Developmental Genetics 2 (1981), S. 49-73 
    ISSN: 0192-253X
    Keywords: determination ; Drosophila ; haltere disc ; homeotic mutation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mutations at the bithorax locus transform anterior haltere tissue into anterior wing. These transformations could in principle be due to the mutations altering either the expression or cell heredity functions of determination. I have studied two alleles of the bithorax locus bx3 and bx34e using disc culture techniques and found that both produce their transformations by altering the expression of the determined state. I have also found that the expression of the temperature-sensitive allele, bx34e, can be altered by temperature shifts during the culture period. Evidence has been obtained that suggests that such changes in expression do not require growth or cell division.
    Additional Material: 5 Ill.
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  • 55
    ISSN: 0192-253X
    Keywords: temporal genes ; GPDH isozymes ; regulation ; development, Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The complete developmental program of glycerol-3-phosphate dehydrogenase in wild type Drosophila is described with respect to activity, isozyme expression, and GPDH-specific CRM. Variants of this developmental program have been isolated from natural populations which affect the rate of accumulation of only the GPDH-3 isozyme in both the larval and adult stages of development. This activity variation segregates as a single gene which is tightly linked to the structural element on Chromosome II, exhibits cis-control, and is tissue specific in expression. This gene meets all the criteria for temporal regulatory genes.
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  • 56
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    Developmental Genetics 2 (1981) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 57
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    Developmental Genetics 2 (1981), S. 159-170 
    ISSN: 0192-253X
    Keywords: Tetrahymena hegewischi ; timing of maturity ; cellular differentiation ; genetic ; environmental variation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The development of sexual maturity has been studied in Tetrahymena hegewischi. Progeny lines do not typically change from immaturity to mating with all different mating types during a single test interval, but about 30% do mature abruptly. Some testers are more likely than others to participate in the earliest mating reactions of progeny lines which do not mature abruptly. Subcaryonidal vegetative pedigrees of 10 pairs from 4 crosses revealed considerable intrapair variation in the time, measured in fissions, of maturity. The average intrapair coefficient of variation was 20%. A nested ANOVA revealed significant genomic effects on the immaturity interval, but no significant cytoplasmic or caryonidal effects; 56% of the total variation was non-genomic. Growth in different environments had highly significant effects on the immaturity interval. Subclones grown at 27°C with alternate day transfers took on the average 2 to 3 times as many fissions to mature as sister subclones grown at 27°C with daily transfers. Subclones grown at 18°C or 34°C and transferred on alternate days had intermediate maturation times. The greatest range in the immaturity interval among lines of the same genotype was from 34 to 143 fissions. The development of maturity in this species involves genetic control of timing, but the genetic differences are obscured by a large amount of intraclonal variation and sensitivity to the environment.
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  • 58
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 2 (1981) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 59
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 2 (1981), S. 369-383 
    ISSN: 0192-253X
    Keywords: Dictyostelium discoideum ; aggregation-deficient mutants ; intracellular cAMP ; adenylate cyclase ; defective spore differentiation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Forty aggregation-deficient mutants of Dictyostelium discoideum were screened for changes in intracellular cAMP during the first 10 hr of starvation. The pools in 39 of the mutants remained low and relatively static during this period. However, amoebae of one mutant, strain HC151, exhibited significantly elevated levels of intracellular cAMP during vegetative growth and for several hours after starvation. A more detailed analysis of this mutant indicated that the elevated cAMP pools in these cells are a consequence of the premature appearance and partial activation of an adenylate cyclase. The mutation(s) altering adenylate cyclase regulation in this strain appears to map in linkage group IV. Complementation tests between strain HC151 and another mutant, HH201, which has recently been shown to produce an adenylate cyclase activity precociously [1], indicated that the mutations affecting adenylate cyclase activity in these strains map at different loci. Although both of these mutations behave recessively in heterozygous diploids with respect to gross development, an examination of early cAMP metabolism and terminal spore differentiation in these diploids suggest that these mutations are at least partially expressed during some stage(s) of the developmental cycle.
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  • 60
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    Developmental Genetics 2 (1981), S. 35-48 
    ISSN: 0192-253X
    Keywords: proteoglycan ; micromelia ; avian embryo ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Embryos homozygous for the recessive lethal gene, micromelia-Abbott, develop a severe form of micromelia, a parrot-like beak, and hemorrhagic skin. Feather development is also retarded. The reduction in length of the long bones of the leg can be traced to their cartilaginous stage Quantitative analysis of sulfated proteoglycan (PGS), a major macromolecular component of cartilage matrix, reveals that mutant tibiae, femora, and sterna contain significantly less uronic acid per μg of DNA than normal rudiments, indicating reduced accumulation of PGS in the mutant. Incorporation of radioactive precursors into cartilage PGS is severely reduced in relatively early developmental stages of a particular organ, but this reduction becomes less severe in cartilage taken from the same rudiment at a later developmental stage. Analysis of the sedimentation rate of PGS in sucrose gradients reveals no difference between normal and mutant in all cartilaginous types at all ages. These results suggest that the quantity and not the quality of PGS is affected in this mutant. The observation that the addition of para-nitrophenyl-β-D-xyloside to the culture medium can stimulate glycosaminoglycan synthesis to normal levels is interpreted to mean that the reduced levels of PGS may be the result of a reduced availability of the xylosylated protein backbone for PGS.
    Additional Material: 4 Ill.
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  • 61
    ISSN: 0192-253X
    Keywords: alcohol dehydrogenase C2 ; isozymes ; temporal locus ; genetics ; chromosome 3 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The tissue specificity of a proposed cis-acting temporal locus (Adh-3t), which regulates alcohol dehydrogenase C2 (ADH-C2) activity in mouse reproductive tissue extracts, has been examined in C5 7BL/6J, SM/J, F1 (SM/J × C5 7BL/6J) mice as well as in progeny of an (F1 [SM/J × C5 7BL/6J] × C5 7BL/6J) back-cross. Electrophoretic variants for ADH-C2, previously used to localize the gene (Adh-3) encoding this enzyme on chromosome 3, enabled the relative parental contributions to ADH-C2 phenotype in F1 and backcross mouse tissues to be determined. These analyses demonstrated that (1) stomach, kidney, lung, adrenals, seminal vesicles, epididymis, uterus, and ovary ADH-C2 is encoded by a single locus (Adh-3); Adh-3t is differentially active in various tissues, eg, lung exhibits no apparent activity whereas the temporal locus is fully active in seminal vesicles; (3) Adh-3t is probably differentically active in different cells of some tissues, eg, adrenals. Specific activity profiles of stomach and epididymal ADH-C2 during the neonatal development of C5 7BL/6J, SM/J, and F1 (SM/J × C5 7BL/6J) male mice supported the proposal for a cis-acting temporal locus for this enzyme. Genetic analyses examining segregation of Adh-3 and Adh-3t among backcross progeny suggested that these are distinct but closely linked loci, since one recombinant among 256 progeny was observed. Linkage data of Adh-3 with Va (varitint-waddler) and de (droopy ear) was also obtained, which suggested that Adh-3 is localized on chromosome 3 between Va and de.
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  • 62
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    Developmental Genetics 2 (1981), S. 357-367 
    ISSN: 0192-253X
    Keywords: amphibian hybrids ; exogastrulation ; hybrid lethality ; nucleocytoplasmic interactions ; triploidy ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Hybrids between species frequently arrest early in development. In the frog hybrid Rana catesbeiana female × Rana clamitans male, the embryo shows a characteristic development to an exogastrula which dies. This hybrid can be rescued by pressure suppression of the second polar body, which results in the addition of another haploid set of R catesbeiana chromosomes to the embryo. The triploid hybrid expresses genes from both species and can develop normally through metamorphosis. The results show that an R catesbeiana egg containing a full haploid set of R clamitans chromosomes is capable of development and that the usual developmental arrest caused by the R clamitans genome responds to chromosomal dosage.
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  • 63
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    Developmental Genetics 2 (1981), S. 203-218 
    ISSN: 0192-253X
    Keywords: cytokinesis ; fusome ; intercellular bridges ; oogenesis ; sterility ; tumor mutations ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The ethyl methane sulfonate-induced mutation, fs(1)1621, resides at 11.7 on the genetic map and within segment 4F1-5A1 of the cytological map of the X chromosome. When homozygous, fs(1)1621 renders females semisterile but has no effect on their viability; nor does it affect the viability or fertility of hemizygous males. Heterozygous females are fertile and have cytologically normal ovaries. The ovaries of homozygous females first produce normal oocytes, which, if fertilized, can develop into adult males or females. After this period, ovarian chambers containing only pseudonurse cells are formed, and finally mutant germaria produce only tumors. These contain hundreds to thousands of cells that appear to be derived from germarial cystocytes, because they occasionally form clones of interconnected cells and also can differentiate into endopolyploid pseudonurse cells. Raising the temperature speeds the rate at which tumors form; lowering it increases the probability of pseudonurse cell differentiation. Df(1)C159 includes fs(1)1621. The pattern of ovarian chamber production is more temperature sensitive in hemizygous females than in homozygous ones. The morphology of hemizygous tumors and the number of dividing cells within them also differ from homozygotes. These observations support the hypothesis that fs(1)1621 is producing a product, that less is produced by one gene than by two, and that the product plays a role in the mitosis and cytokinesis of ovarian cystocytes.
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  • 64
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    Developmental Genetics 2 (1981), S. 237-252 
    ISSN: 0192-253X
    Keywords: Drosophila ; embryonic cultures ; protein synthesis ; stage specific ; differentiation ; two-dimensional gel electrophoresis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The patterns of proteins synthesized during embryonic development in Drosophila melanogaster have been examined by two-dimensional gel electrophoresis. Primary cell cultures prepared from donor embryos synchronized to ± 1 hr were labeled with [35S]methionine at 5, 11.5, 14.5, and 26 hr after oviposition. Of approximately 400 to 500 proteins detected, the synthesis of about 50 is developmentally modulated. The greatest number of changes in the synthesis of stage-specific proteins occurs at 11.5 and 14.5 hr after oviposition, periods just prior to and during the times of the greatest overt morphological and biochemical changes. At 11.5 hr, 35 stage-specific proteins are synthesized, including 19 that are not present at the previous stage examined. At 14.5 hr, 34 stage-specific proteins can be detected, including 11 newly synthesized proteins. However, 12 proteins from the previous stage are no longer synthesized. At the completion of embryonic differentiation, at 26 hr, no new proteins are synthesized and the synthesis of many present in earlier stages has decreased or stopped. Comparison of patterns of embryonic proteins to those synthesized by two Drosophila continuous cell lines reveals that the majority of proteins are common to all. However, only about 40% of the embryonic stage-specific proteins are present in either cell line. In addition, there are several proteins unique to each cell line that are not observed in any of the embryonic stages.
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  • 65
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    Developmental Genetics 2 (1981), S. 1-12 
    ISSN: 0192-253X
    Keywords: β-galactosidase ; preimplantation ; mouse ; Bgl ; paternal effect ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Lysosomal acid hydrolase expression during preimplantation mouse embryogenesis has proved useful in estimating when mRNA transcription commences during this period. Previous work from this laboratory has shown that α-galactosidase and β-glucuronidase undergo 50- to 100-fold increases in activity between the two-cell stage and the blastocyst stage [1, 2]. Here we show that β-galactosidase activity levels undergo a similar change. We also demonstrate that mouse strains with the Bgl-sh allele produce cleavage stage embryos with 2-4-fold higher activity levels than strains with the Bgl-sd allele. Bgl has been shown to control β-galactosidase levels in adult mouse tissues [3]. Unfertilized egg β-galactosidase levels are also regulated by Bgl, but loci distant from Bgl modify egg expression. The distant sites are not observed to act during cleavage. Hybrid embryos (Bgl-sd/h) show intermediate activity levels to the parental types. The timing of the deviation of hybrid embryo β-galactosidase activity levels from maternal-type activity levels is used to estimate when transcription of genes governing β-galactosidase expression occurs.
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  • 66
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    Developmental Genetics 2 (1981), S. 23-34 
    ISSN: 0192-253X
    Keywords: Paramecium tetraurelia ; trichocysts, nuclear differentiation ; cytoplasmic inheritance ; determination ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The mtFE mutation isolated in Paramecium tetraurelia affects mating type differentiation, trichocyst excretion, and viability. Its effect on mating type has already been shown to correspond to a restriction to the E mating type interpreted by an inefficiency of nuclear O-determining factors. In this paper we study the other two phenotypic characteristics whose hereditary transmission displays two unusual features. (1) In crosses between a wild-type strain and the mutant strain, the mutant characteristics do not reappear in F2 in the wild-type cytoplasmic lineage but only in F3 after the homozygous clones have undergone an additional nuclear reorganization. (2) Some F2 wild-type clones, in the mutant cytoplasmic lineage, retain some of the phenotypic characteristics of the mutant. We propose that the mtF gene product plays a role in the control of several macronuclearly differentiated functions.
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  • 67
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    Developmental Genetics 2 (1981), S. 75-87 
    ISSN: 0192-253X
    Keywords: Drosophila melanogaster ; homoeosis ; imaginal discs ; aldehyde oxidase ; pattern formation ; compartments ; selector genes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In a study of the regulation of enzyme patterns in imaginal discs the aldehyde oxidase pattern was determined for some homoeotic mutations of D. melanogaster. Earlier indications that suggested that this pattern follows the determinitive state of compartments within imaginal discs were confirmed by the aldehyde oxidase (AO) pattern of both the wing and haltere discs from en1; bx3, en1; pbx, and en1; bx3 pbx larvae and the antennal discs from Antp73b and ssa larvae.We additionally analyzed whether AO activity depended on the determinative state of an entire compartment or was expressed autonomously in clones. Homozygous engrailed clones were induced by mitotic recombination. From the AO clones found in normally negative areas of the posterior compartment it was concluded that enzyme activity depended upon the determinative state of the cells and was not a function of the compartment as a whole.The results are described with reference to a scheme in which compartmental and subcompartmental selector genes are thought to determine a binary code on which AO patterns depend.
    Additional Material: 6 Ill.
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  • 68
    ISSN: 0192-253X
    Keywords: Drosophila ; dopa decarboxylase ; female fertility ; temperature sensitive lethal mutant ; differential tissue-specific responses to temperature ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The mutation Ddcts1 effects female sterility when homozygous, hemizygous, or heterozygous over a series of Ddc null alleles (Ddcx) indicating that some aspect of Ddc gene function is necessary for female fertility. Ovary transplant experiments demonstrate that the female sterility phenotype is ovary autonomous. Two to 3% of the total DDC activity measurable in newly hatched females is localized in their previtellogenic ovaries. The degree to which females heterozygous for Ddcts1 over different Ddc null alleles are fertile at 22°C reflects a continuous spectrum of allelic complementation similar to that observed for the effects of these genotypes on viability at 30°C. Fertility of all the Ddcts1/Ddcx females tested is significantly depressed at 30 vis-a-vis 22°C providing evidence that it is the DDC enzyme activity itself which is required for female fertility. Ddcts1/Ddcts1 homozygous and Ddcts1/Df hemizygous females are nonconditionally, completely sterile at 18, 20, 22, 25, and 30°C. Although all homo- and hemizygous females do lay some eggs, no evidence of embryogenesis or fertilization has ever been detected. The absolute, nonconditional sterility of Ddcts1 homo- and hemizygous females stands in stark contrast to the conventional temperature dependent effects of these same genotypes on viability and to the temperature sensitive effects of Ddcts1/Ddcx heterozygous females on both fertility and viability. Reasons for these tissue-specific and genotypic differences are discussed.
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  • 69
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    Developmental Genetics 2 (1981), S. 253-267 
    ISSN: 0192-253X
    Keywords: myxomycete ; Physarum polycephalum ; mating type ; sexual compatibility ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The conversion of the uninucleate amoebal form of Physarum polycephalum to the multi-nucleate plasmodial form is under the control of a genetic region which contains matA (or mt), a determinant of mating specificity. The region is the site of most gad mutations, which give amoebae the ability to produce plasmodia in clones without mating (ie, to self). In the present study, nonselfing revertants were isolated from two matA2-derived gad mutants and two matA3-derived gad mutants. Some revertants were found to have regained exactly, or nearly, the same phenotype as the original matA2 or matA3 strain. Others expressed new mating types, having gained the ability to mate with strains of the parental matA type. The results are compatible with a model in which new mating types arise from forward mutations (gad) and back mutations (npf or no plasmodium formation) occurring successively in a single gene, matA.
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    Developmental Genetics 2 (1981), S. 269-277 
    ISSN: 0192-253X
    Keywords: β-glucuronidase ; androgen ; receptor ; development ; mouse ; kidney ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: During postnatal development of mouse kidney the androgen responsiveness of epithelial cells for β-glucuronidase induction, cellular hypertrophy, and other enzyme inductions appears coincidentally with a rise in androgen receptor protein. Initially, a low level of receptor is present but no response is seen. Beginning at about 12 days of age responsiveness begins to increase, reaches a half-maximal level at 18-20 days, and full responsiveness by 28-30 days. The limiting factor appears to be levels of androgen receptor protein.Our experiments shed no light on the question of why each androgen responsive cell type in the organism differentiates the capacity to induce a different array of proteins. However, they do suggest that responsiveness of the β-glucuronidase gene does not appear until a minimum threshold level of receptor is exceeded, and that the response of the gene may not be saturated even at the highest levels of receptor reached.
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  • 71
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    Developmental Genetics 2 (1981), S. 305-315 
    ISSN: 0192-253X
    Keywords: X-chromosome inactivation ; mouse ; PGK-1 ; embryonic cell lineage ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have used a sensitive electrophoretic technique for estimating the activity, or ratio, of two allozymes of the X-chromosome-linked enzyme phosphoglycerate kinase (PGK-1), in order to investigate the randomness of X-chromosome expression in the derivatives of the three primary cell lineages of the early mouse conceptus. The maternally derived Pgk-1 allele is preferentially expressed in the derivatives of the primitive endoderm and trophectoderm lineages at 6 1/2 days post coitum in Pgk-1a/Pgk-1b heterozygous conceptuses, and in the one informative 5 1/2-day heterozygous conceptus analysed. This evidence for preferential expression of the maternally derived X chromosome (Xm), so soon after the time of X-chromosome inactivation, favors the possibility that the preferential expression of Xm is a consequence of primary non-random X-chromosome inactivation, rather than a secondary selection phenomenon. The majority of embryos analysed at 4 1/2 and 5 1/2 days pc produced only a single PGK-1 band, corresponding to the allozyme produced by the Pgk-1 allele on Xm, although 50% of these embryos should have been heterozygous females. Possible explanations are discussed.
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  • 72
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    Developmental Genetics 2 (1981), S. 319-336 
    ISSN: 0192-253X
    Keywords: maize ; mitochondrial DNA ; recombinant DNA ; cms-T ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Recombinant DNA and hybridization techniques have been used to compare the organization of mitochondrial DNA (mtDNA) from normal (N) and Texas male sterile (T) cytoplasms of maize. Bam H1 restriction fragments of normal mtDNA were cloned and used in molecular hybridizations against Southern blots of Bam H1 digested N and T mtDNA. Fifteen of the 35 fragments were conserved in both N and T as indicated by hybridization to comigrating bands in their restriction patterns. Only three fragments produced autoradiographs whose differences could reasonably be attributed to single changes in the cleavage site of the enzyme while approximately half (17/35) of the clones resulted in more complicated differences between N and T. The autoradiographs produced by these 17 clones indicated multiple cleavage site changes and/or sequence rearrangements of the mtDNA. Patterns of six of these 17 clones indicated partial duplication of the sequence and two showed variation in the intensity of hybridization between N and T, which may be related to the molecular heterogeneity phenomenon found in maize mitochondrial genomes. The large proportion of changes observed between N and T mtDNA indicates that rearrangements may have played an important role in the evolution of the maize mitochondrial genome.
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    Developmental Genetics 2 (1981), S. 185-202 
    ISSN: 0192-253X
    Keywords: somatic DNA alteration ; nuclear differentiation ; mating types ; ciliate genetics ; immunoglobulin genes ; Tetrahymena thermophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Experimental data on mating type determination in T. thermophila, collected by Nanney, Allen, and their collaborators over a period of 25 years, are reinterpreted in the light of our current understanding of macronuclear genetics. A strong case is developed supporting the idea that mating type determination involves the developmental alteration of somatic DNA that occurs regularly in developing macronuclei in conjugating pairs. A. testable DNA deletion/splicing model is developed that although based on a few simple, plausible assumptions, explains the observations remarkably well. The model is in (at least) superficial analogy to the mechanism that must be involved to explain the somatic differentiation and alteration of DNA sequences that ultimately constitute an expressed vertebrate immunoglobulin gene. Because of the genetic, biochemical, and micromanipulative versatility of Tetrahymena, it may well turn out to be a uniquely suitable microbial eukaryotic experimental system for the study of developmental alterations of somatic DNA.
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    Developmental Genetics 2 (1981), S. 317-317 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 75
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    Developmental Genetics 2 (1981), S. 291-303 
    ISSN: 0192-253X
    Keywords: mouse ; trisomy ; gene dosage ; enzyme activity pattern ; phosphoglycerate mutase (PGAM) ; glutamate oxaloacetate transaminase (GOT) ; isozyme ; developmental pattern ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Activity patterns of cytosolic and mitochondrial enzymes of carbohydrate and amino acid metabolism have been measured in murine trisomy 19. In spite of marked hypoplasia, no significant alterations of the patterns (per gram of organ weight) were observed, with the exception of glutamate oxaloacetate transaminase (GOT-1), and phosphoglycerate mutase (PGAM). Clear-cut gene dosage effects in liver, brain, heart, skeletal muscle, and erythrocytes of fetal and newborn mice, confirm the assignment of GOT-1 to chromosome 19. Data obtained for PGAM demonstrate that one of the two different subunits leading to organ-specific isozyme patterns of the dimer enzyme protein is coded on chromosome 19 (gene Pgam-1). Dosage effects are fully expressed in liver, brain, and erythrocytes (AA-type isozyme), but not in skeletal muscle (BB-type isozyme). Dosage effects on the hybrid AA-AB-BB-isozyme pattern in the course of development of the heart muscle, were demonstrated by means of quantitative activity measurement after electrophoretic separation. The comparison of enzyme patterns of eusomic and trisomic erythrocytes, produced after injection of fetal stem cells into irradiated adult carriers (transplantation chimaeras), revealed enzyme activity ratios that were similar to those produced by erythrocytes of adult euploid and trisomic mice. This is in agreement with the chromosome assignments and dosage effects mentioned above.
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  • 76
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 2 (1981), S. 349-356 
    ISSN: 0192-253X
    Keywords: agouti locus ; lethal yellow gene ; MSH ; dibutyryl cyclic AMP ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Alleles at the agouti locus determines the type of pigment produced in hair-bulb melanocytes. In order to analyze the mechanism of agouti gene function, an attempt was made to induce the shift in melanin synthesis in vitro. Skin explants from newborn yellow mice with genotype Ay/a were cultured with the method using membrane-filter and roller tube. Production of black pigment in the hair bulbs was observed when the explants were cultured in the presence of α-melanocyte stimulating hormone (α-MSH). Electron-microscopic observation indicates that the induced black pigments are eumelanin that is normally found in hair-bulb melanocytes of genotypically black mice. The eumelanin synthesis was also induced by cAMP, DbcAMP, or theophylline. This α-MSH-induced eumelanin synthesis was suppressed by actinomycin D or cycloheximide, suggesting that the α-MSH-induced eumelanogenesis requires de novo transcription and/or translation.
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    Developmental Genetics 2 (1981), S. 385-405 
    ISSN: 0192-253X
    Keywords: allelic isozyme variants ; mammalian development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The past decade has seen an explosion of interest in mammalian embryos. Techniques of molecular and genetic analysis coupled with advances in in vitro culture and experimental manipulation of mammalian embryos have provided important insights into mechanisms of embryogenesis. Many of these recent advances have been facilitated by the use of allelic isozyme variants as autonomous cell markers or representative gene products. Investigations aimed at exploring cell lineages and cell commitment, the timing and regulation of gene expression, X chromosome inactivation, and cell interactions have depended on the availability of appropriate isozyme variants. Results from such experiments are summarized here in order to demonstrate the usefulness of this approach and to stimulate its wider application in developmental biology.
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