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  • 1990-1994  (431)
  • 1880-1889
  • 1993  (431)
  • Genetics  (251)
  • Biochemistry  (180)
  • 1
    ISSN: 1432-0533
    Keywords: Canine galactosialidosis ; Morphology ; Biochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An adult-onset lysosomal storage disorder was diagnosed in a 5-year-old Schipperke dog with progressive cerebellar and central vestibular signs. It was characterized by cerebellar atrophy with extensive loss of Purkinje and granular cells, and hydrocephalus. Enlarged and vacuolated neurons were observed in spinal cord and brain; pancreatic centrolobular and islet cells were also vacuolated. Ultrastructurally, enlarged secondary lysosomes laden with lamellated membrane structures were present in neurons and empty enlarged vacuoles were found in pancreatic centroacinar, ductal, and islet cells. On frozen sections neurons stained with Ricinus communis agglutinin-I and wheat germ agglutinin. On paraffin sections neurons stained with luxol fast blue, periodic acid-Schiff, Concanavalia ensiformis agglutinin, and were autofluorescent. These findings indicate an accumulation of glycolipids containing terminal β-galactosyl and α-sialyl residues, and N-linked oligosaccharides. Tissue activity of lysosomal β-galactosidase was 50% of normal and the activity of β-hexosaminidase was elevated. Brain lipid-bound sialic acid was twice normal, with a small increase of GM1-ganglioside, but there was a significant elevation of GM2 (GD2) and GM3 (GD3). In addition, significant elevations of sialylated and non-sialylated oligosaccharides were noted. These clinical, biochemical and pathological findings are similar to those observed in human patients with adult-onset galactosialidosis.
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  • 2
    ISSN: 1432-0428
    Keywords: Genetics ; DNA polymorphism ; glucose ; phosphorylation ; glycolysis ; chromosome 2 ; insulin resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Type 2 (non-insulin-dependent) diabetes mellitus is characterized by decreased levels of glucose 6-phosphate in skeletal muscle. It has been suggested that the lower concentrations of glucose 6-phosphate contribute to the defect in glucose metabolism noted in muscle tissue of subjects with Type 2 diabetes or subjects at increased risk of developing Type 2 diabetes. Lower levels of glucose 6-phosphate could be due to a defect in glucose uptake, or phosphorylation, or both. Hexokinase II is the isozyme of hexokinase that is expressed in skeletal muscle and is responsible for catalysing the phosphorylation of glucose in this tissue. The recent demonstration that mutations in another member of this family of glucose phosphorylating enzymes, glucokinase, can lead to the development of Type 2 diabetes prompted us to begin to examine the possible role of hexokinase II in the development of this genetically heterogeneous disorder. As a first step, we have cloned the human hexokinase II gene (HK2) and mapped it to human chromosome 2, band p13.1, by fluorescence in situ hybridization to metaphase chromosomes. In addition, we have identified and characterized a simple tandem repeat DNA polymorphism in HK2 and used this DNA polymorphism to localize this gene within the genetic linkage map of chromosome 2.
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  • 3
    ISSN: 1432-1076
    Keywords: Androgen ; Receptor ; Genetics ; Mutations ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Androgen insensitivity syndromes represent one cause of human male pseudohermaphroditism related to defects in the androgen receptor. The formation of a biologically active androgen receptor complex with testosterone and 5α-dihydrotestosterone is required for normal androgen action during fetal development and fifferentiation of the internal accessory sex glands and external genitalia. Cloning of the human androgen receptor complementary DNA and genetic screening of human subjects with the clinical and biochemical features of androgen insensitivity using the polymerase chain reaction, denaturing gradient gel electrophoresis and nucleotide sequencing techniques have led to the identification of molecular defects in the androgen receptor. The complexity of phenotypic presentation by affected subjects with the complete or partial forms of androgen insensitivity is represented by the heterogeneity of androgen receptor gene mutations which include deletions and point mutations, with the latter causing, inappropriate splicing of RNA, premature termination of transcription and amino acid substitutions. The naturally occurring mutations in the androgen receptor of subjects with androgen insensitivity represent a base upon which we can increase our understanding of the structure and function of the androgen receptor in normal physiology, and disease.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 152 (1993), S. 467-468 
    ISSN: 1432-1076
    Keywords: Hirschsprung disease ; Familial occurrence ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Hirschsprung disease (HD) is genetically heterogeneous with approximately 4% familial occurrence. The recurrence risk is higher in patients with severe involvement. We describe the transmission of histotopochemically proven HD from a father with long aganglionic segment disease to a son with ultrashort segment disease. This observation suggests that the length of involvement in HD is related to the variable expression of the gene defect. It also suggests autosomal dominant inheritance of HD.
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  • 5
    ISSN: 1432-0428
    Keywords: Genetics ; Type 2 (non-insulin-dependent) diabetes mellitus ; HLA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Epidemiologic data suggest that a parental history of Type 2 (non-insulin-dependent) diabetes mellitus increases the risk of Type 1 (insulin-dependent) diabetes in siblings of a Type 1 diabetes proband. This increase in risk is consistent with a shared genetic susceptibility between Type 1 and Type 2 diabetes. We have previously reported evidence that HLA-DR4-linked factors may represent a homogeneous subset of diabetes susceptibility. First, HLA-DR4 frequency was higher in Type 1 diabetic study subjects with a Type 2 diabetic parent than in Type 1 diabetic subjects whose parents were not diabetic. Second, a DR4-haplotype was transmitted from the Type 2 diabetic parent to the Type 1 offspring more often than expected. These data are consistent with the hypothesis that families with a Type 2 diabetic parent and Type 1 diabetic child, heavily determined by HLA-DR4 linked factors, may represent a homogeneous subset of diabetes susceptibility. In this report, we further explore the relationship between the high-risk HLA antigen (HLA-DR4) in study subjects with differing glycaemic status (National Diabetes Data Group criteria). In this community-based study, we find evidence that HLA-DR4 is increased in study subjects with Type 2 diabetes and may be a marker for Type 2 diabetes susceptibility.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 86 (1993), S. 333-338 
    ISSN: 1432-2242
    Keywords: Genetics ; Rice ; Salinity ; Tolerance ; Na-Kratio ; Diallel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genetics of salinity tolerance in rice was investigated by a nine-parent complete diallel including reciprocals. Test materials involved susceptible (IR28, IR29, and MI-48), moderately tolerant (IR4595-4-1-13, IR9884-54-3-1E-P1, and IR10206-29-2-1), and tolerant (“Nona Bokra”, “Pokkali”, and SR26B) parents. Twoweek-old seedlings were grown in a salinized (EC = 12 dS/m) culture solution for 19 days under controlled conditions in the IRRI phytotron. Typical characteristics of salinity tolerance in rice were found to be Na+ exclusion and an increased absorption of K+ to maintain a good Na-K balance in the shoot. Genetic component analysis (GCA) revealed that a low Na-K ratio is governed by both additive and dominance gene effects. The trait exhibited overdominance, and two groups of genes were detected. Environmental effects were large, and the heritability of the trait was low. Our findings suggest that when breeding for salt tolerance, selection must be done in a later generation and under controlled conditions in order to minimize environmental effects. Modified bulk and single-seed descent would be the suitable breeding methods. Combining ability analysis revealed that both GCA and specific combining ability (SCA) effects were important in the genetics of salt tolerance. Moderately tolerant parents — e.g., IR4595-4-1-13 and IR9884-54-3-1E-P1 — were the best general combiners. Most of the best combinations had susceptible parents crossed either to moderate or tolerant parents. The presence of reciprocal effects among crosses necessitates the use of susceptible parents as males in hybridization programs. Large heterotic effects suggest the potential of hybrid rice for salt-affected lands.
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  • 7
    ISSN: 1432-2072
    Keywords: Morphine ; Behavioral activity ; Analgesia ; Rat ; Self-administration ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of the current study was to investigate genetic differences between two inbred strains of rats, Fisher-344 (F344/N) and Wistar Albino Glaxo (WAG/GSto), in a number of drug-naive and drug-related behaviors, including oral and intravenous morphine self-administration. F344/N and WAG/GSto rats differed in drug-naive behaviors such as nociception, rearing and sensitivity to lick suppression tests but did not differ in locomotor activity, ambulation or grooming behavior. F344/N rats were less sensitive to thermal stimuli as measured via tail-flick response, and more sensitive to the suppressive effects of intermittent shock in a lick suppression test. The F344/N rats demonstrated a significantly greater amount of rearing in open field tests but did not differ from WAG/GSto rats in locomotor activity, ambulation or grooming behavior. In addition to the behavioral results, naive F344/N and WAG/GSto rats were found to differ in μ and α2 receptor concentrations (F344/N〉WAG/GSto) and in 5HT2 and D2 affinity constants (WAG/GSto〉F344/N). These two inbred rat strains also differed in drug-related behaviors. F344/N rats showed significantly greater depression of locomotor activity at morphine 3 mg/kg than WAG/GSto rats. In addition, F344/N rats consumed significantly greater amounts of morphine in a two-bottle choice procedure and morphine maintained significantly greater amounts of behavior during intravenous self-administration sessions. Importantly, drug maintained behavior was significantly greater than with vehicle only in the F344/N rats during operant self-administration sessions.
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  • 8
    ISSN: 1437-160X
    Keywords: Systemic lupus erythematosus ; HLA-DP ; Ro (SS-A) autoantibodies ; La (SS-B) autoantibodies ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We investigated the association of HLA-DPB1 alleles with the occurrence of autoantibodies against Ro (SS-A) or La (SS-B) using recombinant 52kD-Ro, 60 kD-Ro and La proteins in 177 German patients with systemic lupus erythematosus (SLE). A significant increase in the frequency of DPB1 *0101 is observed in SLE patients compared to healthy controls (P corr.〈0.004). Antibodies against 52 kD-Ro, 60 kD-Ro and La are tested by ELISA and are found with a frequency of 25.4%, 33.9% and 17.5% in the patients, respectively. An association with HLA-DPB1 *0101 is observed for antibodies against La (P〈0.01) and 52 kD-Ro (P〈0.01), but not for 60 kD-Ro in the absence of La/52 kD-Ro. Since there is a strong linkage disequilibrium between DPB1 *0101 and DR3 in the normal population and in SLE patients, and since there is an association between DR3 and SLE, as well as between DR3 and the occurrence of recombinant Ro/La antibodies in SLE patients, we investigated whether DPB1 *0101 is associated per se or via linkage disequilibrium with DR3. DPB1 *0101 in the absence of DR3 is not more common in patients than in controls and not in patients with autoantibodies to Ro and La than without antoantibodies. We conclude that there is no evidence for a direct involvement of DPB1 *0101 in the production of Ro/La autoantibodies in SLE patients.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 240 (1993), S. 151-155 
    ISSN: 1432-1459
    Keywords: Genetics ; Complex partial seizures ; Waking and sleep EEGs ; Siblings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Waking and sleep EEGs were recorded in 29 siblings of 19 patients with complex partial seizures. At least 1 sibling with epileptic activity (EA) was found for 36.8% of the patients. Taking the 29 siblings as a basis, in 7 EA was recorded. Most EA was seen during sleep in stage C (29%). More EA was recorded in female siblings (28% :18%) and in siblings of female patients (56% :20%). All EA was seen in the age range 5–14 years. Siblings with occipital theta-delta activity with a generalization tendency showed more EA (59%) than those without this pattern (8%). Of the siblings of patients with generalized EA 50% showed EA, but only 25% of those of patients with localized EEG patterns.
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  • 10
    ISSN: 1432-1440
    Keywords: Hereditary ataxias ; Friedreich's ataxia ; Genetics ; FRDA locus ; Chromosome 9
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The clinical features of Friedreich's ataxia are described and reevaluated in a group of 14 German patients from 9 independent families. In contrast to previous studies, demonstration of linkage to the Friedreich's ataxia locus (FRDA) on chromosome 9p allowed confirmation of the genetic homogeneity of the disease in the patients under study. Marked variability within families was observed for age of onset of the disease (4–24 years) and for age of becoming wheelchair bound (17–37 years). Electrocardiographic changes were present in all and echocardiographic changes in 50% of the patients. Pathological changes of visual evoked potentials were detected in only 50% of the patients while brainstem auditory evoked potentials and somatosensory evoked potentials were always abnormal.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Sexuality and disability 11 (1993), S. 221-228 
    ISSN: 1573-6717
    Keywords: Genetics ; disability ; reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Psychology
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Primates 34 (1993), S. 333-346 
    ISSN: 0032-8332
    Keywords: Genetics ; Pedigrees ; Molecular evolution ; Pan ; Hylobates ; Macaca ; DNA sequences ; Microsatellite loci
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using DNA amplified from shed or plucked hair follicles it is now possible to genotype individual primates at many nuclear and mitochondrial gene loci. Sequence specific primers and the polymerase chain reaction permit the rapid production of sufficient DNA from a single hair for numerous analyses. The direct sequencing of relatively conservative mtDNA sequences like cytochromeb is proving useful in establishing species and subspecies-level relationships. More variable sequences (e.g. the mtDNA control region or D-loop) are useful at the population and social community levels. Paternity exclusion, pedigree relationships, and community structure can be determined using simple sequence length polymorphisms (SSLPs) of multiple hypervariable nuclear microsatellite or simple sequence repeat (SSR) loci. Studies involving captive and free-ranging chimpanzees, gibbons, and macaques illustrate the resolving power of these new non-invasive molecular genetic genotyping techniques.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    European archives of psychiatry and clinical neuroscience 243 (1993), S. 131-142 
    ISSN: 1433-8491
    Keywords: Genetics ; Nosology ; Methodology ; Linkage analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Statistical procedures and molecular genetic techniques have attained a fine degree of resolution. Their ability to find disease genes has revolutionized medicine and raised hopes for breakthroughs in psychiatry. However, such breakthroughs may require an equally discriminating nosology. A psychiatric genetic nosology seeks to classify patients into categories that correspond to distinct genetic entities by addressing the problem of diagnostic accuracy: the degree to which a diagnosis correctly classifies people with and without a putative genetic illness. We review methods that deal with misclassification in genetic studies. These are clinical and epidemiological approaches that deal directly with how to define the observable manifestation of a putative genotype. We discuss two groups of methods: those that use known phenotypes and those that design new phenotypes.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    European archives of psychiatry and clinical neuroscience 243 (1993), S. 143-149 
    ISSN: 1433-8491
    Keywords: Genetics ; Linkage ; Psychiatric disorders ; Genetic epidemiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Linkage analysis has been successful in identifying the genetic basis of numerous Mendelian diseases. These successes were due in part to the rapid developments in molecular biology, which have yielded a plethora of informative genetic markers. Although there is strong evidence that the manifestation of schizophrenia and bipolar affective disorders is controlled by genes, no evidence for linkage has been established. For psychiatric disorders, the most important limiting factor is likely to be the lack of single loci with very large effects that occur with any relevant frequency. The difficulties of linkage studies in psychiatric disorders are discussed with reference to non-psychiatric genetic diseases for which linkage to genetic markers has been successful. Recommendations for collecting information to clarify the patterns of transmission of the psychiatric disorders are described.
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  • 15
    ISSN: 1432-2242
    Keywords: Genetics ; Disease ; Mapping ; Breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molecular markers at 103 loci were used to identify the location of quantitative sources of resistance to Exserohilum turcicum in 150 F2∶3 lines of a B52/Mo17 maize population. Host-plant response was measured in terms of the average number of lesions per leaf, the average percent leaf tissue diseased (severity), and the average size of lesions. The location of quantitative trait loci were compared with three loci having known qualitative effects, namely Ht1, Ht2 and bx1. Chromosomal regions containing the Ht1 and Ht2 loci showed a small contribution in determining lesion size, even though alleles with dominant, qualitative effects at these loci have never been reported in either inbred parent. Similar effects were not observed for the number of lesions or for disease severity. Likewise, some contribution was observed for chromosomal regions encompassing the bx1 locus in determining lesion size but not the number of lesions or disease severity. Overall the contribution of loci in the vicinity of Ht1, Ht2 and bx1 was small relative to variation attributable to loci with quantitative effects identified in this study. Molecular-marker-facilitated mapping concurred with previous reciprocal translocation mapping studies on the importance of chromosomes 3, 5 and 7, despite the fact that these studies utilized diverse sources of resistant germplasm.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 176 (1993), S. 53-63 
    ISSN: 1615-6102
    Keywords: Acetabularia acetabulum ; Gamete release ; Mating efficiency ; Mating physiology ; Gamete half-life ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have improved zygote recovery 11–1,000 fold by optimizing the physiology of gamete release and mating inAcetabularia acetabulum. Gamete release was affected by agar purity, concentration, and volume/gametangial pair. Cold pre-treatment of gametangia (14–30 d at 10°C in the dark) synchronized subsequent gamete release at 21°C in the light. Cold pre-treatment was nearly twice as effective in synchronizing subsequent gamete release when intact, gametangia-bearing caps rather than isolated gametangia were pretreated. Synchronizing gamete release doubled mating efficiency. In a wild-type laboratory strain ofA. acetabulum, there were 1,561±207 gametes/gametangium which had half-lives of 14.5 d in 0.1% seawater-agar. We recovered 48–93% of the expected numbers of zygotes from a mass mating of 8 to 1,226 gametangia and 11–128% of the expected numbers of zygotes from mating single gametangial pairs: the large range in the calculated mating efficiency may be attributable to the variation in the numbers of gametes made per gametangium. Zygote recovery from single gametangial pairs was highly dependent on the volume of mating matrix. In addition, most zygotes recovered were unattached to any other zygotes in the subsequent generation (〉 95% single cells from matings of 1–500 gametangial pairs). Our improvements in mating conditions and zygote recovery (1) have facilitated cell manipulation and culture ofA. acetabulum in the laboratory; and (2) have made controlled crosses for selection and genetic analysis of mutants feasible. These advances have removed a major barrier to genetic analysis of development inAcetabularia.
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  • 17
    ISSN: 1432-0878
    Keywords: Gap junction ; Cell junction ; Immunocytochemistry ; Biochemistry ; Heliothis virescens (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Subcellular fractions enriched in gap junctions with an ultrastructure similar to those in intact insect tissue have been obtained by extracting crude membranes from the tobacco budworm Heliothis virescens (Lepidoptera: Noctuidae) with 2.5 mM NaOH. n-Octyl-β-d-glucopyranoside (OG) was used to further purify integral membrane proteins in the NaOH-extracted fractions. A polyclonal antibody (R16) is described that specifically labels nonextracted and NaOH-extracted gap junctions in cell fractions by electron microscope immunocytochemistry. R16 immunostaining of sectioned Heliothis testis at the light-microscope level yields a pattern of immunoreactivity consistent with the distribution of gap junctions in the tissue. R16 identifies a 40-kDa protein as a candidate gap junction protein on immunoblots of crude membrane, NaOH-extracted and NaOH/OG-extracted fractions.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 235 (1993), S. 611-621 
    ISSN: 0003-276X
    Keywords: Peroxidase ; Parotid gland ; Salivary gland ; Rat ; Growth and development ; Biochemistry ; Cytochemistry ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The course of development of salivary peroxidase, an enzyme that has an important role in oral defense mechanisms, has been well documented in rat submandibular glands. However, the only report on salivary peroxidase activity in the other major salivary glands of the rat has been a cytochemical study of the adult parotid gland. In the present investigation, the accumulation of salivary peroxidase activity in developing parotid glands of rats was followed both biochemically and cytochemically. Specific activity (units per mg protein) attributable to salivary peroxidase began at 1 day after birth, then rose rapidly but unevenly, with peaks at 21 and 70 days, and no difference between the sexes at any age. Activity per gland increased progressively to 42 days in both sexes and was significantly higher in males at 70 days. The cytochemical observations on peroxidase activity localized to the rough endoplasmic reticulum and secretory granules of the developing acini were well correlated with the biochemical findings. Peroxidase-negative cells occurred in immature acini at 1 and 7 days, but only in the intercalated ducts thereafter. This observation suggests that the acini are a source of some of the ductal cells, at least during early postnatal development. The developmental pattern of specific activity differed from those of other rat parotid secretory enzymes, indicating that control of their synthesis during development is noncoordinate. The patterns of specific activity of the parotid and submandibular glands were complementary, suggesting that their combined secretions may supply biologically significant peroxidase activity to the oral cavities of rats throughout postnatal development. © 1993 Wiley-Liss, Inc.
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  • 19
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 30-36 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We consider the tree search problem for the recurrence relation that appears in the evaluation of molecular integrals over Cartesian Gaussian basis functions. A systematic way of performing tree search is shown. By applying the result of tree searching to the LRL2 method of Lindh, Ryu, and Liu (LRL) (J. Chem. Phys., 95, 5889 1991), which is an auxiliary function-based method, we obtain significant reductions of the floating point operations (FLOPS) counts in the K4 region. The resulting FLOPS counts in the K4 region are comparable up to [dd|dd] angular momentum cases to the LRL1 method of LRL, currently the method requiring least FLOPS for [dd|dd] and higher angular momentum basis functions. For [ff|ff], [gg|gg], [hh|hh], and [ii|ii] cases, the required FLOPS are 24, 40, 51, and 59%, respectively, less than the LRL1 method in the K4 region. These are the best FLOPS counts available in the literature for high angular momentum cases. Also, there will be no overhead in either the K2 or K0 region in implementing the present scheme. This should lead to more efficient codes of integral evaluations for higher angular momentum cases than any other existing codes. © 1993 John Wiley & Sons, Inc.
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  • 20
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 19-29 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A method is proposed to perform computer simulations of protein dynamics in the long-time regime. The method is based upon a Monte Carlo technique. The only molecular degrees of freedom considered are bond rotations. All other degrees of freedom including the amide plane torsions are kept rigid. These constraints approximately account for all interactions related to chemical bonding. An individual Monte Carlo step adopts the Go and Scheraga algorithm where local conformational changes in a small window of the protein backbone are performed. By using correlated rotations, the conformation of residues outside the window remains invariant. To test the reliability of the method, the nonbonded interactions are turned off in the present application. Exact statistical averages are compared with values obtained from data of computer simulation involving 2 × 106 scans of the window along the protein backbone. Time is related to the number of scans of the window along the protein backbone. End-to-end distance autocorrelation functions decay to 1/e of its initial value in about 103-104 scans of the window algorithm. Time decay follows a stretched exponential Kohlrausch decay law. © 1993 John Wiley & Sons, Inc.
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  • 21
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 226-236 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: In this article, we describe the program MORMIN, which can simultaneously minimize the mechanical energy of a given macromolecular structure, together with a weighted quadratic penalty function of the difference between the observed and computed nuclear Overhauser effect (nOe) peaks. The gradient of the nOe penalty function relatively to the proton coordinates is computed from an exact closed formula of a matrix exponential derivative. To cut CPU time, the molecular system is partitioned into nonoverlapping subsets containing the protons involved in the observed peaks. The algorithm is no longer exact, but if a 1% relative error is accepted it can be run, on a scalar computer, in about the same CPU time as needed for the calculation of the mechanical energy. We have successfully run the program in more than 1000 situations, including cases where the hybrid method failed because of the occurrence of negative eigenvalues. In some cases, the optimization of the Cartesian coordinates could be successfully extended to individual atomic diffusion times. © 1993 John Wiley & Sons, Inc.
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993) 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
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  • 23
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 253-262 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We present investigations on the use of dielectric continuum models for the self-consistent description of electrostatic solvent effects on the ground state of a molecule and on excitation energies. The electronic structure calculations have been carried out in the framework of the INDO and INDO/S-CI method, respectively. We compare the performance of three implementations of the cavity model that all allow an arbitrary shape of the solute cavity. The procedures differ in the effort spent on the description of the charge density at the cavity surface. Two procedures in the vein of Miertus̆, Scrocco, and Tomasi (MST) rely upon point charges to model the reaction field and differ in the way the cavity surface is modeled. While one implementation divides the surface into flat triangular patches, the improved version uses curved triangles. Alternatively, we investigate a finite element method (FEM) for the calculation of the surface charge density. Applications to rod-shaped organic molecules (including their charge transfer excitations) illustrate the superiority of the improved MST formalism over the primitive one, as it exhibits faster convergence of the results with increasing node density on the cavity surface. The FEM approach, which also employs curved surface patches, leads to a further improvement as it needs less computational effort, especially in the treatment of excited states. © 1993 John Wiley & Sons, Inc.
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  • 24
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 312-329 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A fully functional parallel version of the molecular dynamics (MD) module of AMBER3a has been implemented. Procedures parallelized include the calculation of the long-range nonbonded Coulomb and Lennard-Jones interactions, generation of the pairlist, intramolecular bond, angle, dihedral, 1-4 nonbonded interaction terms, coordinate restraints, and the SHAKE bond constraint algorithm. As far as we can determine, this is the first published description where a distributed-memory MIMD parallel implementation of the SHAKE algorithm has been designed to treat not only hydrogen-containing bonds but also all heavy-atom bonds, and where “shaken” crosslinks are supported as well. We discuss the subtasking and partitioning of an MD time-step, load balancing the nonbonded evaluations, describe in algorithmic detail how parallelization of SHAKE was accomplished, and present speedup, efficiency, and benchmarking results achieved when this hypercube adaptation of the MD module AMBER was applied to several variant molecular systems. Results are presented for speedup and efficiency obtained on the nCUBE machine, using up to 128 processors, as well as benchmarks for performance comparisons with the CRAY YMP and FPS522 vector machines. © 1993 John Wiley & Sons, Inc.
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  • 25
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    Journal of Computational Chemistry 14 (1993), S. 349-352 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We report the development of a new approximate method of calculating molecular surface areas. Our technique is based upon the method of Sharake and Rupley but incorporates several major advances. First, we represent the state of surface points as bits in a bit string so we can utilize Boolean operations to simultaneously turn off multiple test points in one Boolean AND operation. Second, we use a series of Boolean mask look-up tables to reduce the time complexity of the calculation of molecular surface area down to the same magnitude as doing a potential energy evaluation. When we use a 256 surface point sphere for all of the atoms in BPTI, a 454 nonhydrogen atom protein, and a 1.4-Å solvent probe, we in general underestimate the total solvent-accessible surface area (SASA) by approximately 1.25% with a correlation coefficient of 0.9990 over a wide range of conformations. The average CPU time required to calculate the SASA of a BPTI conformer is 0.58 s on an SGI 4D/220 workstation. We also describe a method by which we can calculate an approximate finite difference SASA gradient for BPTI in 0.79 of CPU time. © 1993 John Wiley & Sons, Inc.
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  • 26
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    Journal of Computational Chemistry 14 (1993), S. 620-626 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We computed the free energy of solvation for a series of ions and neutral molecules using two different continuum approaches. First, we used the AM1-SM1 technique, where the AM1 Fock matrix is modified to include a generalized Born contribution. Second, we applied the DelPhi approach, where the electrostatic component of the free energy of solvation is evaluated by resolving the Poisson-Boltzman equation by a finite difference method. Both methods appear equally reliable for ionic systems. For neutral compounds, AM1-SM1 performs better than DelPhi; however, the differences become less pronounced for compounds with larger free energies of solvation. In parallel, both methods were applied to study the influence of the solvation process in the overall drug receptor interaction for a series of closely related ligands for the D1 dopamine receptor. An inverse linear relationship was found between the free energy of solvation and the logarithm of the affinity of the ligands; nevertheless, electrostatic properties are likely to modulate affinity as well. © 1993 John Wiley & Sons, Inc.
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  • 27
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    Journal of Computational Chemistry 14 (1993), S. 655-666 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The structures of several sulfones, including dimethyl sulfone, methyl ethyl sulfone, methyl vinyl sulfone, and diphenyl sulfone, have been fit with the MM3 force field to existing experimental data from electron diffraction and microwave spectroscopy. The vibrational spectra have also been fit for six of these compounds. The torsional parameters for the aliphatic sulfones were fit to ab initio 6-31G data. Heats of formation were also fit. © 1993 John Wiley & Sons, Inc.
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  • 28
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    Journal of Computational Chemistry 14 (1993), S. 667-672 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Chemisorption on small, closed-ring CdS clusters and the electronic structure of the surface were studied using Hartree-Fock valence calculations based upon stepwise density matrix approximations. Detailed valence calculations gave stabilization energies similar to the all-electron results for the small CdS clusters, verifying our valence method in which the approximations of the density matrices were fitted against the atomic calculations. Chemisorption studies have shown that the 4d shell relaxation on the Cd atom plays a crucial role even though the 4d does not participate directly in the substrate-adsorbate bonds. Thus, the CdCl2 was found unbound to the surface in the case of implicit description of the 4d orbital of the Cd whereas treating the Cd 4d orbital explicitly in the variational calculation the CdCl2 bonds to the surface with the calculated adsorption energy of 107.4 kJ/mol. © 1993 John Wiley & Sons, Inc.
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  • 29
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    Journal of Computational Chemistry 14 (1993), S. 741-750 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Using experimental solubilities and partial pressures for hydrocarbon solution in water and molecular dynamics calculations of hydrocarbon water interaction energies, hydrocarbon-water cavity potentials are obtained and then plotted vs. accessible surface area. The data used is mainly for aliphatic hydrocarbons, but benzene is included. Molecular dynamics calculations of pairs of hydrocarbon molecules together with the cavity potential curve are then used to obtain hydrophobic interaction free energies between the hydrocarbon pairs. While the cavity potential change is related to a change in surface area for hydrocarbon systems, the hydrocarbon-water interaction energy is not, so that the hydrophobic binding energy is not. The results are in agreement with previous results by a different method (R.B. Hermann, In Seventh Jerusalem Symposium on Quantum Pharmacology, E. Bergman and B. Pullman, Eds., D. Reidel, Dordrecht, 1974, p. 441) in that there is little or no solvent-induced binding free energy between small hydrocarbon molecules in a dilute aqueous solution. It is proposed that the cavity potential vs. accessible surface area curve obtained here can be used together with OPLS parameters to calculate both hydrocarbon-water solvation free energies and hydrophobic interactions. © 1993 John Wiley & Sons, Inc.
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  • 30
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    Journal of Computational Chemistry 14 (1993), S. 769-774 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We present a storage-efficient and robust algorithm for the computation of eigenvectors of large sparse symmetrical matrices using a Lanczos scheme. The algorithm is based upon a linear combination of Lanczos vectors (LCLV) with a variable iteration depth. A simple method is given to determine the iteration depth before the eigenvector computation is performed. Test calculations are reported for tight-binding models of ordered and disordered 2-D systems. The algorithm turns out to be reliable if an eigenvector residual less than 10-4 is required. We report benchmarks for various computers. Possible fields of application are discussed. © 1993 John Wiley & Sons, Inc.
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  • 31
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    Journal of Computational Chemistry 14 (1993), S. 775-789 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: It is suggested to improve the MNDO model by the explicit inclusion of valence-shell orthogonalization corrections, penetration integrals, and effective core potentials (ECPs) in the one-center part of the core Hamiltonian matrix. Guided by analytic formulas and numerical ab initio results, the orthogonalization corrections are expressed in terms of the resonance integrals that are represented by a new empirical parametric function. All two-center Coulomb interactions and ECP integrals are evaluated analytically in a Gaussian basis followed by a uniform Klopman-Ohno scaling. One particular implementation of the proposed NDDO SCF approach is described and parameterized for the elements H, C, N, O, and F. In a statistical evaluation of ground-state properties, this implementation shows slight but consistent improvements over MNDO, AM1, and PM3. Significant improvements are found for excited states, transition states, and strong hydrogen bonds. Possible further enhancements of the current implementation are discussed. © 1993 John Wiley & Sons, Inc.
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  • 32
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    Journal of Computational Chemistry 14 (1993), S. 809-817 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The two-step hydrolyses of substituted polyglycolic acids are modeled by the semiempirical MNDO Hamiltonian using small molecule analogs to determine the effect of the alkyl substituents on the reaction and activation enthalpies. Reaction enthalpies remain reasonably constant up to three carbons, before becoming less exothermic for large alkyl substituents. Activation enthalpies show patterns that can be explained by steric effects. © 1993 John Wiley & Sons, Inc.
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  • 33
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Complexes of 18-crown-6 with alkali-metal cations (Na+, K+, and Rb+), urea, and the uncomplexed crown ether were studied in vacuo with the molecular dynamics method. Conformational data from these calculations (simulation times in the range from 6-15 ns) was compared with information from the Cambridge Structural Database. Despite the differences in condition between the simulations and the solid state, a number of interesting similarities are observed. © 1993 John Wiley & Sons, Inc.
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  • 34
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    Journal of Computational Chemistry 14 (1993), S. 922-927 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A quantitative comparative analysis of molecular electrostatic potential (MEP) distributions generated from different wave functions was carried out. Wave functions were computed by using MNDO, AMl, STO-3G, 3-21G, 4-31G, 6-31G, 4-31G*, 6-31G*, and 6-31G** methods. Ten different compounds, which include usual atoms and groups of biomolecules, such as hydroxyl, carbonyl, amine, amide, imine, double and triple bonds, and heteroaromatic rings, were studied. For each compound, MEP values in the points of a common 3-D grid were computed; thereafter, the similarity between each pair of MEP distributions generated by different methods was assessed. Similarities were measured using the Spearman rank correlation coefficient. A similarity matrix was obtained for each compound. Similarity matrices were averaged and a hierarchical cluster analysis was carried out to classify the different quantum chemical methods. In the compounds studied, the main conclusion is the negligible difference between the pattern of MEP distributions generated from all split valence basis sets (with and without polarization functions). © 1993 John Wiley & Sons, Inc.
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  • 35
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    Journal of Computational Chemistry 14 (1993), S. 944-960 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A modification of Allinger's MM2 force field for the anomeric effect in O—C—N systems is presented. For optimal consistency, it was parameterized by alternate use of ab initio (3-21G level) and X-ray results to account for the energetic and structural manifestations of the effect in the gas or condensed phase, respectively. The results obtained with the modified force field are in good agreement with those from both theoretical and experimental methods. The parameterization scheme explicitly treats all structural parameters of the C—O—C—N—C moiety as well as C—N bond lengths in tertiary amines contained within an anomeric unit. In addition, it includes directional H-bond type interactions. A limited number of parameters is put forward, in accord with the general MM2 force-field approach. © 1993 John Wiley & Sons, Inc.
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  • 36
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    Journal of Computational Chemistry 14 (1993), S. 977-985 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The application of parallel processing techniques to molecular mechanics calculations is evaluated. Using the standard molecular mechanics package, MM2, four different parallel versions of the program are implemented in a four-processor computing environment. A set of 529 test structures is used to compare the efficiency of the parallel versions of MM2 to a standard serial version of the program. Statistics describing execution times and program execution cycles are gathered and analyzed. The effects of parallel processing overhead and computer system load are explored, and the practical utility of parallel processing in molecular mechanics is estimated. The results of these parallelization experiments indicate that for geometry optimizations requiring significant amounts of computing time an improvement in program execution speed approaching 50% is realizable. © 1993 John Wiley & Sons, Inc.
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  • 37
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    Journal of Computational Chemistry 14 (1993), S. 995-1005 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Parameters were derived for guanosine triphosphate (GTP) and GTP analogs suitable for the AMBER force field. Electrostatically derived net atomic charges and force parameters were extracted from MNDO semiempirical calculations. The later parameters came from fitting MNDO and AMBER atom-atom forces in a manner that is extensible to other compounds that lack sufficient vibrational spectral data. The geometric parameters for these compounds were obtained from model compounds in the Cambridge crystallographic data base. Dynamic simulations of Na4 GTP and Na2 Mg GTP of 140 and 100 ps, respectively, indicated a strong preference for a syn C2′ exo conformation in solution. © 1993 John Wiley & Sons, Inc.
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  • 38
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    Journal of Computational Chemistry 14 (1993), S. 1027-1035 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Three hydrogen-bonded minima on the phenol-water, C6H5OH - H2O, potential energy surface were located with 3-21G and 6-31G** basis sets at both Hartree-Fock and MP2 levels of theory. MP2 binding energies were computed using large “correlation consistent” basis sets that included extra diffuse functions on all atoms. An estimate of the effect of expanding the basis set to the triple-zeta level (multiple f functions on carbon and oxygen and multiple d functions on hydrogen) was derived from calculations on a related prototype system. The best estimates of the electronic binding energies for the three minima are -7.8, -5.0, and -2.0 kcal/mol. The consequences of uncertainties in the geometries and limitations in the level of correlation recovery are analyzed. It is suggested that our best estimates will likely underestimate the complete basis set, full CI values by 0.1-0.3 kcal/mol. Vibrational normal modes were determined for all three minima, including an MP2/6-31G** analysis for the most strongly bound complex. Computational strategies for larger phenol-water complexes are discussed. © John Wiley & Sons, Inc.
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  • 39
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A general procedure is presented for generating one-electron integrals over any arbitrary potential operator that is a function of radial distance only. The procedure outlines that for a nucleus centered at point C integrals over Cartesian Gaussians can be written as linear combinations of 1-D integrals. These Cartesian Gaussian functions are expressed in a compact form involving easily computed auxiliary functions. It is well known that integrals over the Coulomb operator can be expressed in terms of Fn(T) integrals, where \documentclass{article}\pagestyle{empty}\begin{document}$$ F_n \left(T \right) = \int_0^1 {u^{2n} e^{ - Tu^2 } {\rm d}u} $$\end{document} By means of a substitution for Fn(T) by other simple functions, algorithms that form integrals over an arbitrary function can be generated. Formation of such integrals is accomplished with minor editing of existing code based on the McMurchie-Davidson formalism. Further, the method is applied using the inverse-square distance and Yukawa potential operators V(r) over Cartesian Gaussian functions. Thus, the proposed methodology covers a large class of one-electron integrals necessary for theoretical studies of molecular systems by ab initio calculations. Finally, by virtue of the procedure's recursive nature it provides us with an efficient scheme of computing the proposed class of one-electron integrals. © 1993 John Wiley & Sons, Inc.
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  • 40
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    Journal of Computational Chemistry 14 (1993), S. 1019-1026 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Estimating log P (logarithm of “1-octanol to water” partition coefficients) as a measure of lipophilicity for organic compounds is of considerable importance in drug discovery. Several methods have been developed for this purpose, each with its own drawbacks and advantages. In this article, a systematic comparison of three well-documented and fully computerized methods has been attempted for a set of nucleosides and bases. The first method (BLOGP) is based on overall molecular properties derived from a molecular orbital calculation to predict log P. The second method (CLOGP) uses fragmental lipophilicity constants with correction factors and treats log P as an additive-constitutive property. The third method (ALOGP) is based on an additivity scheme of atomic lipophilicity constants, with the constitutive factor governed by an elaborate list of atom types. However, none of these methods take into account conformational flexibility or intramolecular hydrogen bonding, which can cause substantial discrepancy between observations and predictions. A comparison of predictions from each of these methods indicates that the atomic contribution method (ALOGP with r = 0.842 and SD = 0.51) is better than other methods (with r = 0.395 and SD = 1.2 for BLOGP and r = 0.713 and SD = 0.93 for CLOGP) for this class of compounds. Our overall assessment is that we do not have, as yet, a highly reliable, fully computerized log P prediction method applicable to flexible heterocycles such as nucleoside analogs. © John Wiley & Sons, Inc.
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  • 41
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    Journal of Computational Chemistry 14 (1993), S. 1194-1202 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Using a number of different lattice models of proteins, the problems introduced by the discretization of a protein backbone are discussed and examples of the most typical errors arising in low coordination number lattices presented. The geometric properties of different lattices used in the literature are compiled, and for all of them the resulting α-carbon models of proteins are described in detail and compared to the original structures obtained from experiment. © John Wiley & Sons, Inc.
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  • 42
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    Journal of Computational Chemistry 14 (1993), S. 1417-1422 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A common problem in the solution of the Poisson-Boltzmann equation using finite difference methods is the self-energy of the system, also known as the grid energy. Because atoms are typically modeled as a point charge, the infinite self-energy of a point charge is likewise modeled. In this article, a simple, alternate treatment of atomic charge is described where each atom is represented as a sphere of uniform charge. Unlike the point charge model, this method converges as the grid spacing is reduced. The uniform charge model generates the same electrostatic field outside the atoms. In addition, the use of fine grids reduces the variations in the potential due to variations in the position of atoms relative to the grid. Calculations of Born ion solvation energies, small-molecule solvation energies, and the electrostatic field of superoxide dismutase are used to demonstrate that this method yields the same results as the point charge model. © John Wiley & Sons, Inc.
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  • 43
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    Journal of Computational Chemistry 14 (1993), S. 1320-1325 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The problem of the representation of the RKR (or IPA) diatomic potential by a simple analytic function is considered. This old problem has for a fairly good solution the Coxon-Hajigeorgiou function U(x) = D[1 - exp-fn(x)]2 with fn(x) = Σm = 1n amxm. The problem of the determination of the disposable parameters a1 … an [in order that U(r) fits the given RKR potential] is reduced to that of a set of linear equations in am where a standard least-squares technique is used. The application to several states (ground or excited) of several molecules shows that a fairly “good” fit is obtained for n ∼ 10, even for the state XOg - I2 bounded by 109 vibrational levels, for which the RKR potential is defined by the coordinates of 219 points. It is shown that the percentage deviation |U(r)RKR - U(r)| throughout the range of r values is about 0.04% for XΣ—Li2, 0.0005% for XΣ—HCl, 0.06% for XOg—I2, and 0.05% for BOu—I2 (as examples). This approach shows the same success for deep and shallow potentials. The comparison of the computed Ev (vibrational energy) and Bv (rotational constant) with their corresponding experimental values shows that a good agreement is reached even for high vibrational levels close to the dissociation. © John Wiley & Sons, Inc.
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  • 44
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    Journal of Computational Chemistry 14 (1993), S. 1561-1574 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: AM1 semiempirical molecular orbital calculations are reported for 20 ion-neutral complexes, including hydrogen-bonded complexes, presumably involved in the gas-phase unimolecular decomposition of simple organic radical cations. The systems investigated are [C2H4O2]·+, [C2H5NO]·+, [C2H6O]·+, [C2H6O2]·+, [C3H6O]·+, [C3H6O2]·+, [C3H8O]·+, and [C3H8O2]·+. The AM1 results are compared with ab initio molecular orbital calculations at different levels of theory up to MP3/6-31G(d, p)//SCF/6-31G(d) + ZPVE and the available experimental data. AM1 fails to predict some local minima and the equilibrium geometries calculated for several complexes are found to be qualitatively different from those predicted by the ab initio calculations. However, reasonable agreement is generally found for the stabilization energies of the complexes toward dissociation into their loosely bound components. © John Wiley & Sons, Inc.
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  • 45
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The deuterium quadrupole coupling constant and asymmetry parameter in heavy water were determined using ab initio SCF calculations. Snapshots from a molecular dynamics simulation were used to give liquid water cluster configurations and the influence of simulation parameters on the quadrupole coupling constant was investigated. The electronic potential model and the number of molecules in the molecular dynamics simulation and the pressure of the system were found to have only a small influence on the quadrupole coupling constant. The average value of the quadrupole coupling constant at room temperature, corrected for the known deficiency of the ab initio calculation in the gas phase, yields a quadrupole coupling constant of 253 kHz, in perfect agreement with the most recent experiments. The oxygen - deuterium bond lengths in ice Ih, ice II, and ice IX were determined using experimental quadrupole coupling constants and a model equation. An averaged bond length of 98.9 pm was obtained for the Ih form, which is approximately 2 pm shorter than that determined by neutron diffraction studies, whereas the bond lengths for the four deuterium sites in ice II and the three sites in ice IX are in fair agreement with experiment. © John Wiley & Sons, Inc.
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  • 46
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    Journal of Computational Chemistry 14 (1993), S. 1498-1503 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A comparison between Miertus-Scrocco-Tomasi (MST) SCRF and free energy perturbation (FEP) estimates of the free energy of hydration of eight small neutral molecules is presented. In both cases, the 6-31G* molecular electrostatic potential is used to describe the electrostatic properties of the molecules. The results demonstrate the ability of both methodologies to provide useful theoretical estimates of the total free energy of hydration; the average errors are only 1.5 kcal/mol (FEP) and 0.8 kcal/mol (MST/SCRF). The largest errors in the FEP and MST/SCRF results are less than 1.5 kcal/mol for all molecules except acetic acid, where the FEP method overestimates the free energy of hydration by 3.3 kcal/mol. © John Wiley & Sons, Inc.
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  • 47
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    Journal of Computational Chemistry 14 (1993), S. 1534-1544 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A comparative and systematic ab initio study of different models simulating the Si (111) surface has been carried out for a variety of embedding hydrogen atoms including unmodified hydrogen atoms and modified hydrogen atoms described with a STO-4G basis set and a Slater exponent optimized to have the cluster atoms as neutral as possible. The study has been extended to some chemisorption processes as Ag and Al on Si (111). The main conclusion of the present work is that neither the electronic structure of the isolated cluster models nor the nature of the chemisorption bond depend on the kind of embedding hydrogen atoms used to saturate the free valences of the cluster edge atoms. © John Wiley & Sons, Inc.
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  • 48
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; chromosome II sequencing ; serine-hydroxymethyl-transferase ; RIB5 ; GAP ; GTP binding protein ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report here the sequence of a 19,482 bp DNA segment of chromosome II of Saccharomyces cerevisiae. The fragment contains 16 open reading frames (ORFs) covering 74% of the sequence. Four predicted products present homology with known proteins. The ORF YBR1732 exhibits a strong homology to serine hydroxymethyl transferase; the best score is 53·1% identity in 458 amino acids overlap with the serine hydroxymethyl transferase from rabbit liver. YBR1724, which shows homology with riboflavin synthase of Bacillus subtilis, is probably the RIB5 gene implied in riboflavine synthesis and mapped in this region. YBR1733 is homologous to rab protein and YBR1728 is presumably a GTPase activating protein.
    Additional Material: 5 Ill.
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  • 49
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; protein kinase ; mRNA leader ; RAS ; cell cycle ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The SCH9 yeast gene, that was previously identified as a suppressor of cdc25 and ras1- ras2-ts temperature-sensitive mutants, encodes a putative protein kinase that positively regulates the progression of yeast cells through the G1 phase of the cell cycle. We have determined the structure of the SCH9 transcription unit, using primer extension and S1 mapping techniques. The corresponding mRNA included an unusually long 5′ region of more than 600 nucleotides preceding the major open reading frame (ORF). While the latter corresponded to a protein of 824 amino acids, an upstream open reading frame (uORF) within the 5′ leader could potentially encode a 54 amino acid peptide. To investigate the role of the AUGs within the uORF, we engineered chimaeric plasmid vectors in which SCH9 sequences including the promoter, the mRNA leader and the first 514 nucleotides of the major ORF were fused in-frame with β-galactosidase-coding sequences. Upon introduction into yeast cells, the fusion protein was efficiently expressed. However, mutational disruption of the uORF using oligonucleotide-directed mutagenesis did not affect the level of expression of the fusion protein. This indicates that regulatory mechanisms in Saccharomyces cerevisiae prevent upstream AUGs within the SCH9 mRNA leader sequence from influencing translation from downstream initiation codons.
    Additional Material: 6 Ill.
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  • 50
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    Yeast 9 (1993), S. 71-75 
    ISSN: 0749-503X
    Keywords: Heterologous expression ; β-glucuronidase ; LEU2 promoter ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The use of β-glucuronidase (β-GUS) as a reporter and sensitive detection system for Yarrowia lipolytica was studied. The Escherichia coli gusA gene was expressed under control of the homologous LEU2 promoter in a transcriptional fusion. An NcoI restriction site was introduced at the translational start-ATG, conserving the most favorable context for initiation of translation. The chimeric LEU2′-gusA gene was integrated into the LEU2 locus by homologous recombination. The β-GUS assay was very sensitive and highly reproducible, using the cytosolic fraction or a total cell extract as the source of enzyme. In a leucine-free medium, β-GUS activity was at a high, constant level, independent of growth phase. In transformants grown on complete medium, β-GUS activity was reduced about three-fold, but doubled during logarithmic growth. No intrinsic β-GUS activity was detectable in untransformed Y. lipolytica and no effect of β-GUS expression on growth was obseved. β-GUS-producing Y. lipolytica cells could be directly detected on media plates containing X-gluc (5-bromo-4-chloro-3-indolyl-β-D-glucuronide).
    Additional Material: 1 Ill.
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  • 51
    ISSN: 0749-503X
    Keywords: Quinol-cytochrome c reductase ; Saccharomyces cerevisiae ; petite ; yeast chromosome VII ; bc1 complex ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We present here mapping data for QCR9, a nuclear gene encoding a subunit of the ubiquinol-cytochrome c oxidoreductase complex. Deletion of QCR9 results in the inability of cells to grow on non-fermentable carbon sources at 37°C. Thus, qcr9 mutants can be scored by growing cells on YPE/G at 37°C, or followed by the URA3 marker, which was inserted when making the qcr9 deletion strain, JDP1. The location of QCR9 on the right arm of chromosome VII with respect to the previously mapped genes ADE3, SER2 and PET54 is given.
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  • 52
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    Yeast 9 (1993), S. 111-119 
    ISSN: 0749-503X
    Keywords: Yeast ; hexose transport ; galactose inhibition ; glycolysis ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The relationship between the pathways of glucose and galactose utilization in Saccharomyces cerevisiae has been studied. Galactose (which is transported and phosphorylated by inducible systems) is a strong inhibitor of the utilization of glucose, fructose and mannose (which have the same constitutive transport and phosphorylation systems). Conversely, all these three hexoses inhibit the utilization of galactose, though with poor efficiency. These cross-inhibitions only occur in yeast adapted to galactose or in galactose-constitutive mutants.The efficiency of galactose as inhibitor is even greater than the efficiencies of each of the other three hexoses to inhibit the utilization of each other. Phosphorylation is not involved in the inhibition and the transport of sugars is the affected step.The cross-inhibitions between galactose and either glucose, fructose or mannose do not implicate utilization of one hexose at the expense of the other, as it occurs in the mutual interactions between the latter three sugars. It seems that, by growing the yeast in galactose, a protein component is synthesized, or alternatively modified, that once bound to either galactose or any one of the other three hexoses (glucose, fructose or mannose), cross-interacts respectively with the constitutive or the inducible transport systems, impairing their function.
    Additional Material: 8 Ill.
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  • 53
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; chromosome I ; calnexin homologue ; CNE1 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 2 Ill.
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  • 54
    ISSN: 0749-503X
    Keywords: δ-Aminolevulinate synthase ; δ-aminoleuvulinate dehydratase ; Saccharomyces cerevisiae HEM R+ mutants ; catabolite repression and derepression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Catabolite repression and derepression on δ-aminolevulinate synthase (ALA-S) and δ-aminolevulinate dehydratase (ALA-D) in a normal yeast strain, D27, and its derived D27/C6 (HEM R+) were investigated. ALA-S and ALA-D activities and intracellular ALA (I-ALA) at different physiological states of the cells were measured. In YPD medium, under conditions of repression and when glucose was exhausted, both strains behaved identically as if the mutation was not expressed. In YPEt medium, however, both ALA-S and ALA-D activities were higher than in YPD, but the I-ALA content and the enzymic activity profiles shown by the two strains were quite different. It appears, therefore, that the mutation causes a deregulation of ALA-S, so that its activity is kept at a high level throughout the cell cycle. This would explain the increased levels of cytochromes present in the mutant. This mutation may affect some regulatory aspect of ALA formation and renders an ALA-S of high activity; moreover, this enzyme species seems to be more stable than in the normal strain.
    Additional Material: 6 Ill.
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  • 55
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    Yeast 9 (1993), S. 101-110 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: No abstract.
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  • 56
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    Yeast 9 (1993), S. 141-150 
    ISSN: 0749-503X
    Keywords: Protein kinase ; Saccharomyces cerevisiae ; KIN3 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have isolated a single gene from the yeast Saccharomyces cerevisiae encoding a potential 800 amino acid polypeptide of calculated Mr 90 098 Da. This protein consists of an N-terminal region that shares significant homology with the catalytic domains of several serine- and threonine-specific protein kinases, as well as a large, unique, C-terminal domain of unknown function. Haploid disruption mutants are viable and do not exhibit any readily observable growth defects under varying conditions of temperature, nutrients or osmotic strength. Due to the apparent structural similarity between this kinase and the protein products of the KIN1 and KIN2 genes, we have chosen to name this new gene KIN3.
    Additional Material: 5 Ill.
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  • 57
    ISSN: 0749-503X
    Keywords: Calcium-binding protein ; phospholipid-binding protein ; CAM1 ; elongation factor ; protein synthesis ; EF-1γ ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have isolated a gene (CAM1) from the yeast Saccharomyces cerevisiae that encodes a protein homologous to the translational cofactor elongation factor-1γ (EF-1γ) first identified in the brine shrimp Artemia salina. The predicted Cam1 amino acid sequence consists of 415 residues that share 32% identity with the Artemia protein, increasing to 72% when conservative substitutions are included. The calculated Mr of Cam1p (47 092 Da) is in close agreement with that of EF-1γ (Mr = 49 200 Da), and hydropathy plots of each protein exhibit strikingly similar profiles. Disruption of the CAM1 locus yields four viable meiotic progeny, indicating that under normal growth conditions the Cam1 protein is non-essential. Attempts to elicit a translational phenotype have been unsuccessful. Since EF-1γ participates in the regulation of a GTP-binding protein (EF-1α), double mutants with cam1 disruptions and various mutant alleles of known GTP-binding proteins were constructed and examined. No evidence was found for an interaction of CAM1 with TEF1, TEF2, SEC4, YPT1, RAS1, RAS2, CDC6, ARF1, ARF2 or CIN4. The possibility that Cam1p may play a redundant role in the regulation of protein synthesis or another GTP-dependent process is discussed.
    Additional Material: 6 Ill.
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  • 58
    ISSN: 0749-503X
    Keywords: FLO1 ; flocculation ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The cloned part of the flocculation gene FLO1 of Saccharomyces cerevisiae (Teunissen, A.W.R.H., van den Berg, J.A. and Steensma, H.Y. (1993). Physical localization of the flocculation gene FLO1 on chromosome I of Saccharomyces cerevisiae, Yeast, in press) has been sequenced. The sequence contains a large open reading frame of 2685 bp. The amino acid sequence of the putative protein reveals a serine- and threonine-rich C-terminus (46%), the presence of repeated sequences and a possible secretion signal at the N-terminus. Although the sequence is not complete (we assume the missing fragment consists of repeat units), these data strongly suggest that the protein is located in the cell wall, and thus may be directly involved in the flocculation process.
    Additional Material: 3 Ill.
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  • 59
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; yeast ; chromosome XI ; MBR1 ; protein kinases ; serine-rich protein ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report in this paper the sequence of a part of chromosome XI of Saccharomyces cerevisiae. This 17 kbp nucleotide sequence represents the right half of cosmid pUKG151 and contains nine open reading frames, YKL453, 450, 449, 448, 445, 443, 442, 441 and the 5′ part of YKL440. YKL440 was previously identified as the MBR1 gene and plays a role in mitochondrial biogenesis. YKL443 is a homologue of the yeast serine-rich protein (SRP1), while YKL453 presents strong homologies with the KIN1/KIN2/SNF1 kinase family. It must be pointed out that the size of this gene is well above average for yeast.
    Additional Material: 4 Ill.
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  • 60
    ISSN: 0749-503X
    Keywords: Methylotrophic yeast ; genetic transformation ; non-homologous integration ; gene disruption ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Development of transformation systems for methylotrophic yeasts is the starting point for research aimed at developing molecular genetics of these genera and will be the key to their further successful use in biotechnology. We transformed Pichia methanolica using selector genes ADE2 and LEU2 from Saccharomyces cerevisiae and ADE1 (homologue of S. cerevisiae ADE2 gene) from P. methanolica which was cloned and sequenced in our laboratory (Hiep et al., 1991). Lithium transformation of P. methanolica strains was inefficient with intact plasmids. Linearization of plasmids at a unique restriction site within the ADE1 gene prior to transformation substantially increased its frequency. Transformation with linear ADE1, ADE2 or LEU2 gene fragments was even more effective. Introduced DNA fragments either circularized in vivo, irrespective of the structures of their ends, giving unstable transformants; or integrated at different sites of the host genome. Using this transformation system, we obtained a disruption of the ADE1 gene on the chromosome by inserting the S. cerevisiae LEU2 gene. The disruption mutation ade1::LEU2 was used to study the mechanism of intragenic recombination in P. methanolica.
    Additional Material: 3 Ill.
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  • 61
    ISSN: 0749-503X
    Keywords: Bromocresol purple ; killer toxin ; Saccharomyces cerevisiae ; fluorescence staining ; yeast ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A method is described for detecting yeast cells with plasma membrane damage, based on cell staining with bromocresol purple (BCP) which has a convenient fluorescence after entering the cells at pH below 5·2. The method was used to determine the activity of Saccharomyces cerevisiae pore-forming killer toxin K1 in commonly used lethal units. The BCP test is rapid and as precise as the plating test.
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  • 62
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    Yeast 9 (1993), S. 1219-1228 
    ISSN: 0749-503X
    Keywords: Kluyveromyces lactis ; codon usage ; G+C content ; molecular evolution ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The nature and variation of synonymous codon usage in 47 open reading frames from Kluyveromyces lactis have been investigated. Using multivariate statistical analysis, a single major trend among K. lactis genes was identified that differentiates among genes by expression level: highly expressed genes have high codon usage bias, while genes of low expression level have low bias. A relatively minor secondary trend differentiates among genes according to G+C content at silent sites. In these respects, K. lactis is similar to both Saccharomyces cerevisiae and Candida albicans, and the same ‘optimal’ codons appear to be selected in highly expressed genes in all three species. In addition, silent sites in K. lactis and S. cerevisiae have similar G+C contents, but in C. albicans genes they are more A+T-rich. Thus, in all essential features, codon usage in K. lactis is very similar to that in S. cerevisiae, even though silent sites in genes compared between these two species have undergone sufficient mutation to be saturated with changes. We conclude that the factors influencing overall codon usage, namely mutational biases and the abundances of particular tRNAs, have not diverged between the two species. Nevertheless, in a few cases, codon usage differs between homologous genes from K. lactis and S. cerevisae. The strength of codon usage bias in cytochrome c genes differs considerably, presumably because of different expression patterns in the two species. Two other, linked, genes have very different G+C content at silent sites in the two species, which may be a reflection of their chromosomal locations. Correspondence analysis was used to identify two open reading frames with highly atypical codon usage that are probably not genes.
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  • 63
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    Yeast 9 (1993), S. 1267-1271 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A gene from Saccharomyces cerevisiae was sequenced that encodes a protein with homology to a family of putative ATPases. These homologous proteins include the yeast cell division cycle protein Cdc48p and its mammalian homologues VCP and p97; Sec18p and its mammalian homologue NSF, proteins necessary for fusion of transport vesicles to target membranes in the secretory pathway; Pas1p, a protein necessary for peroxisome biosynthesis in yeast; Yme1p, a yeast mitochondrial protein that influences the rate of DNA escape from mitochondria; and TBP-1, MSS1 and Sug1p, proteins that interact with transcription factors. This newly sequenced gene, named AFG2 for ATPase family gene, is located on chromosome XII 5′ to the SLP1/VPS33 open reading reading frame and encodes an essential protein of 780 amino acids that is most homologous to Cdc48p.
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  • 64
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    Yeast 9 (1993), S. 753-759 
    ISSN: 0749-503X
    Keywords: Microsatellites ; AT-repeats ; ARS ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Microsatellites are repeats of very short sequences of DNA, interspersed in the genome. In this paper, the occurrence of the two-base repeat microsatellites has been investigated in the DNA sequence of yeast chromosome III. Only AT-repeats were found at a significantly high frequency. Some of the regions with the highest concentration of AT-repeats were located and further analysed, showing a close association with the core consensus of autonomously replicating sequences.
    Additional Material: 5 Ill.
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  • 65
    ISSN: 0749-503X
    Keywords: Yeast ; genome ; MCM2 ; MCM3 ; CDC46 ; KRE2 ; KTR1 ; MNT1 ; YUR1 ; DUR1,2 ; protein glycosylation ; lipase ; peroxisomal targeting signal ; DNA replication ; cdc21sp ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A 12 820 bp fragment from the right arm of chromosome II of Saccharomyces cerevisiae was sequenced and analysed. This fragment contains six non-overlapping long open reading frames (ORFs) designated from the centromere- to the telomere-proximal ends as: YBR1441, 1443, 1444, 1445, 1446 and 1448. YBR1441 encodes a polypeptide of 845 amino acids which shares a long consensus domain with products of S. cerevisiae MCM2, MCM3, CDC46 and Schizosaccharomyces pombe cdc21+ genes. These genes are involved in DNA replication. YBR1445 encodes a polypeptide of 404 amino acids which has strong similarity with the S. cerevisiae KRE2/MNT1, YUR1, KTR1 gene products. The KRE2/MNT1 protein is an α-1,2-mannosyltransferase. The product of YBR1444, which encodes a protein of 375 amino acids, presents a lipase signature sequence and a peroxisomal targeting signal. YBR1448, whose sequence extends further on the telomere-proximal end of the fragment, is identical to the 3′ end of the DUR1,2 gene encoding urea amidolyase. The two ORFs, YBR1443 and YBR1446, exhibit no significant similarity with any known gene.
    Additional Material: 5 Ill.
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  • 66
    ISSN: 0749-503X
    Keywords: Yeast ; Saccharomyces cerevisiae ; chromosome VIII ; ARG4 ; meiosis ; SH3 domain ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have sequenced a 3296 bp segment of the chromosome VIII adjacent to the 3′ end of the ARG4 gene. This segment contains two divergently oriented open reading frames (YSC83 and YSC84). Northern blot analysis showed the presence of transcripts corresponding to these two open reading frames in vegetative cells. Levels of these transcripts increase five to ten-fold during sporulation. These two genes are not essential for vegetative growth or sporulation. Analysis of the putative protein products on the SwissProt database revealed that the C-terminal region of the Ysc84 protein contains a putative SH3 domain.
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  • 67
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    Yeast 9 (1993), S. 1157-1164 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: No abstract.
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  • 68
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    Yeast 9 (1993), S. ii 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: No abstract.
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  • 69
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    Yeast 9 (1993), S. 941-1029 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 3 Ill.
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  • 70
    ISSN: 0749-503X
    Keywords: glucose transport ; Saccharomyces cerevisiae ; LGT1 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A low-affinity glucose transporter gene of Saccharomyces cerevisiae was cloned by complementation of the rag1 mutation in a strain of Kluyveromyces lactis defective in low-affinity glucose transport. Gene sequence and effects of null mutation in S. cerevisiae were described. Data indicated that there are multiple genes for low-affinity glucose transport.
    Additional Material: 3 Ill.
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  • 71
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    Yeast 9 (1993), S. 1331-1334 
    ISSN: 0749-503X
    Keywords: In vitro transcription ; initiation of RNA synthesis ; Schizosaccharomyces pombe ; Kluyveromyces lactis ; Candida glabrata ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We demonstrate the successful adaptation to other yeast species of a protocol previously described for production of transcriptionally active whole cell extracts from Saccharomyces cerevisiae (Woontner and Jaehning, 1990, J. Biol. Chem. 265, 8979-8982). Extracts prepared from Schizosaccharomyces pombe, Kluyveromyces lactis and Candida glabrata were all capable of initiating transcription from a template containing the S. cerevisiae CYC1 TATA box fused to a G-less cassette. Transcription in all of the extracts was sensitive to inhibition by α-amanitin, indicating that it was catalysed by RNA polymerase II, and was dramatically stimulated by the chimeric activator GAL4/VP16. The different extracts used different subsets of a group of three initiation sites.
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  • 72
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; chromosome XI ; UBI2 ; MPLI ; ORF ; myosin ; USO1 ; Nopp140 ; membrane protein ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: As part of the EEC yeast genome program, a fragment of 15 820 bp from the right arm of Saccharomyces cerevisiae chromosome XI has been sequenced. This fragment corresponds roughly to the centromere-distal half of cosmid pUKG046 and to a small fragment of cosmid pUKG096, which are located approximately 150 kb from the centromere. It contains four open reading frames (ORFs) which encode potential proteins of more than 100 amino acid residues, as well as the UBI2 gene which carries an intron and does not show up as an ORF in the sequence analysis programs. One of the putative proteins, YKR412, is very rich in serine and has significant homology at the carboxyl end to Nopp140 phosphoprotein. YKR413 has several predicted transmembrane domains. YKR15, which has been recently cloned as the MPL1 gene, encodes a polypeptide that shows homologies to myosin heavy chain and to the cytoskeleton protein Uso1.
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  • 73
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    Yeast 9 (1993) 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 74
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    Yeast 9 (1993), S. 61-80 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 75
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    Yeast 9 (1993), S. 121-140 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 76
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    Yeast 9 (1993), S. 201-220 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 77
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    Yeast 9 (1993), S. 127-139 
    ISSN: 0749-503X
    Keywords: yeast ; polyphosphatase ; purification ; specificity ; inhibitors ; divalent cations ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Saccharomyces cerevisiae cell envelope polyphosphatase was isolated in highly active and stable form by extraction from cells with zwittergent TM-314 followed by chromatography of the extract on phosphocellulose and QAE-Sephadex in the presence of 5 mM-MgCl2, 0·5 mM-EDTA and 0·1% Triton X-100. The enzyme possessed a specific activity of 220 U/mg and after 30 days retained 87% of its activity at -20°C. Polyphosphatase molecular mass was determined to be about 40 kDa by gel filtration and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The enzyme hydrolysed polyphosphates with various chain lengths (n = 3-208), had low activity for GTP and did not split pyrophosphate, ATP and p-nitrophenylphosphate. On polyphosphates with chain lengths n = 3, 9 and 208, Km values were 1·7 × 10-4, 1·5 × 10-5 and 8·8 × 10-7 M respectively. Polyphosphatase was most active and stable at pH 6·0-8·0. The enzyme showed maximal activity at 50°C. The time of half inactivation of polyphosphatase at 40, 45 and 50°C was 45, 10 and 3 min, respectively. In the absence of divalent cations and also with Ca2+ or Cu2+, the enzyme showed practically no activity. The ability of divalent cations to activate polyphosphatase was reduced in the following order: Co2+ 〉 Mg2+ 〉 Mn2+ 〉 Fe2+ 〉 Zn2+. Polyphosphatase was completely inhibited by 1 mM-ammonium molybdate and 50 μM-Zn2+ or Cu2+ (in the presence of Mg2+).
    Additional Material: 10 Ill.
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  • 78
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 9 (1993), S. 235-249 
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; nuclear pore ; nuclear envelope ; mitosis ; karyogamy ; cell cycle ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In the yeast Saccharomyces cerevisiae, the nucleus undergoes dramatic shape changes during mitosis and mating. We have studied nuclear envelope dynamics during the processes of mitosis and conjugation using nuclear pore complexes as a marker for the nuclear envelope in wild-type cells and several cell-division-cycle (cdc) mutants.Three monoclonal antibodies are described that recognize nuclear pore complex-related antigens in S. cerevisiae. One of these antibodies, RL1, has been extensively characterized by Gerace and colleagues and recognizes nuclear pore complexes in mammalian and amphibian cells. By indirect immunofluorescence of yeast cells, all three antibodies yield a discontinuous nuclear rim stain. All three react with multiple nuclear-enriched proteins in immunoblots, including the nucleoporin protein encoded by the NSP1 gene.When the antibodies were used in immunofluorescence experiments on mating cells, the nuclear pore complex staining pattern proved to be a sensitive indicator of nuclear fusion. Nuclei with closely apposed spindle pole bodies and unfused nuclear envelopes could be readily distinguished. Marked shape changes were observed in nuclei during fusion and segregation of the diploid nucleus into the zygotic bud.In cdc14 and cdc15 mutants that arrest late in mitosis, the elongated nuclear envelope extension that stretches between daughter nuclei during telophase was preserved. In cytokinesis-defective mutants (cdc3, cdc10, cdc11 and cdc12), the elongated nuclear envelope was usually resolved into two daughter nuclei in the absence of cytokinesis. These results indicate that nuclear envelope division is mechanistically distinguishable from chromosome segregation, nucleolar segregation and cytokinesis.
    Additional Material: 5 Ill.
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  • 79
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    Yeast 9 (1993), S. 301-305 
    ISSN: 0749-503X
    Keywords: Chromosome XVI ; mitochondrial carrier ; ARO7 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have cloned and sequenced a Saccharomyces cerevisiae gene coding for a protein with significant similarities to the mitochondrial carrier family. The gene we termed YMC1 (yeast mitochondrial carrier) is located on chromosome XVI, closely downstream of ARO7 encoding chorismate mutase.
    Additional Material: 3 Ill.
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  • 80
    ISSN: 0749-503X
    Keywords: Endomitosis ; heat treatment ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Diploid cells with ability to mate, hereafter referred to as diploid mater cells, were obtained at significant frequencies by the heat treatment of haploid spores at the early germination stage in Saccharomyces cerevisiae heterothallic strain CG5M (a/α diploid cells heterozygous for five auxotrophic markers). The highest frequency (ca. 11%) of diploidization was obtained from viable cells after heat treatment at 55°C for 10 min when spores were precultivated for 30 min in liquid medium to initiate the germination. The diploid mater cells obtained were homozygous for mating type and for the auxotrophic markers. The diploidization of a spore is thus concluded to be due to endomitotic events in germinating heat-treated spores.
    Additional Material: 3 Tab.
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  • 81
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 9 (1993) 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 82
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 9 (1993), S. 1-10 
    ISSN: 0749-503X
    Keywords: Chromosome I ; Flocculation ; FLO1 ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The genetics of flocculation in the yeast Saccharomyces cerevisiae are poorly understood despite the importance of this property for strains used in industry. To be able to study the regulation of flocculation in yeast, one of the genes involved, FLO1, has been partially cloned. The identity of the gene was confirmed by the non-flocculent phenotype of cells in which the C-terminal part of the gene had been replaced by the URA3 gene. Southern blots and genetic crosses showed that the URA3 gene had integrated at the expected position on chromosome I. A region of approximately 2 kb in the middle of the FLO1 gene was consistently deleted during propagation in Escherichia coli and could not be isolated. Plasmids containing the incomplete gene, however, were still able to cause weak flocculation in a nonflocculent strain. The 3′ end of the FLO1 gene was localized at approximately 24 kb from the right end of chromosome I, 20 kb centromere-proximal to PHO11. Most of the newly isolated chromosome I sequences also hybridized to chromosome VIII DNA, thus extending the homology between the right end of chromosome I and chromosome VIII to approximately 28 kb.
    Additional Material: 5 Ill.
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  • 83
    ISSN: 0749-503X
    Keywords: Heat shock proteins ; mRNA degradation ; ribosomal proteins ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have previously shown that the heat-induced enhanced decay of yeast mRNAs encoding ribosomal proteins (rp-mRNAs) requires ongoing transcription during the heat treatment [Herruer et al. (1988) Nucl. Acids Res. 16, 7917]. In order to determine whether this requirement reflects the need for heat-shock protein (hsp), we analysed the effect of heat shock on rp-mRNA levels in several yeast strains in which each of the heat-shock genes encoding hsp26, hsp35 or hsp83 had been individually disrupted. In all three strains we still observed increased degradation of rp-mRNAs immediately after the temperature shift, demonstrating that hsp26, hsp35 and hsp83 are not required for this effect. Accelerated turnover of rp-mRNA was also found to occur upon raising the growth temperature of a mutant strain that contains a disruption of the gene specifying the heat-shock transcription factor and in wild-type yeast cells treated with canavanine, an arginine analogue that will be incorporated into all known hsps and that is known to cause misfolding of the polypeptide chain. Latter observation suggests that enhanced rp-mRNA decay is a more general stress-related phenomenon. Taken together, these data strongly indicate that the trans-acting factor required for the increase in the rate of degradation of rp-mRNAs upon stress is not one of the known yeast hsps.
    Additional Material: 5 Ill.
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  • 84
    ISSN: 0749-503X
    Keywords: Aspergillus niger ; gene expression ; glucose oxidase ; Hansenula polymorpha ; MF-α secretion leader sequence ; methylotrophic yeast ; methanol oxidase promoter ; recombinant protein ; regulatory mutants ; reporter gene ; super-secretion mutant ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The glucose oxidase gene (god) from Aspergillus niger was expressed in Hansenula polymorpha using the methanol oxidase promoter and transcription termination region and the MF-α leader sequence from Saccharomyces cerevisiae to direct secretion. The expression cassette was cloned into the S. cerevisiae vector YEp13 and used to transform H. polymorpha strain A16. In the initial transformants plasmid replication was unstable, but was stabilized by a growth regime consisting of alternating cycles of selective and non-selective growth. The stabilized strain was grown to high cell density by fed-batch fermentation. Upon induction of the MOX promoter, glucose oxidase synthesis was initiated. At the end of the fermentation, the culture density was 76 g dry weight/1 and 108 IU/ml (0·5 g/l or 0·65% dry weight) glucose oxidase was found in the culture medium; a further 86 IU/ml (0·43 g/l or 0·56% dry weight) was recovered from the cell lysate. A plate assay was used to monitor glucose oxidase levels in individual colonies. This was then used to isolate mutants which showed abnormal regulation of god expression or which showed an altered pattern of secretion. One mutant, which showed increased production of glucose oxidase, was grown to high cell density by fed-batch fermentation (100·6 g/l) and produced 445 IU/ml (2·25 g/l or 2·2% dry weight) extracellularly and 76 IU/ml (0·38 g/l or 0·4% dry weight) intracellularly. The mutant thus not only increased total production but exported 83% of the total enzyme made compared to 55% in the parent strain.
    Additional Material: 7 Ill.
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  • 85
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 9 (1993) 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 86
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 9 (1993), S. 691-702 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 2 Ill.
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  • 87
    ISSN: 0749-503X
    Keywords: Yeasts ; peroxisomes ; Hansenula polymorpha ; peroxisomal membrane ; permeability ; membrane protein ; ΔΨ measurements ; pore-forming protein ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A major 31 kDa integral peroxisomal membrane protein (PMP31) of Hansenula polymorpha was purified to homogeneity from isolated peroxisomal membranes by FPLC after solubilization by Triton X-100. Biochemical analysis indicated that this protein, which showed cross-reactivity with antibodies against the 31 kDa porin of the mitochondrial outer membrane of Saccharomyces cerevisiae, had pore-forming properties. Firstly, proteoliposomes composed of asolectin and purified PMP31 showed selective permeability, determined as the [14C]sucrose/[3H]dextran leakage ratios. Furthermore, the generation of a ΔΨ by potassium diffusion gradients was negatively affected by the presence of PMP31 in asolectin liposomes. A similar effect was observed in proteoliposomes containing purified cytochrome c oxidase as a ΔΨ generating system. Control experiments confirmed that the observed leakage is significant and introduced by the incorporation of PMP31 protein. Selective sucrose leakage was abolished in samples pretreated with glutaraldehyde; an identical effect of glutaraldehyde was, however, not observed for the membrane potential measurements.
    Additional Material: 5 Ill.
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  • 88
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report here the DNA sequence of a segment of chromosome XI of Saccharomyces cerevisiae extending over 7·8 kb. The segment contains four long open reading frames, YKL150, YKL153, YKL155 and YKL156, YKL155 corresponds to the CAP1 gene. YKL153 contains an intron and shows an extremely biased codon usage suggestive of a highly expressed protein. YKL156 is a homolog to UOG-1, an open reading frame associated with the cDNA clone of the mammalian growth/differentiation factor 1. YKL150 reveals common motifs to both the RNA polymerase II elongation factor of Drosophila melanogaster and to the yeast PPR2 gene product.
    Additional Material: 6 Ill.
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  • 89
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    Yeast 9 (1993), S. 307-314 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: No abstract.
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  • 90
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; chromosome I ; sulfur assimilation ; CYS3 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have cloned, sequenced and physically mapped the CYS3 gene of Saccharomyces cerevisiae. This gene can complement the cys3-1 allele, and disruptions at this locus lead to cysteine auxotrophy. The predicted CYS3 product is closely related (46% identical) to the rat cystathionine γ-lyase (Erickson et al., 1990), but differs in lacking cysteine residues. These results provide further evidence that the S288C strain of yeast resembles mammals in synthesizing cysteine solely via a trans-sulfuration pathway. The CYS3 product was found to have strong homology to three other enzymes involved in cysteine metabolism: the Escherichia coli metB and metC products and the S. cerevisiae MET25 gene product. The trans-sulfuration enzymes appears to form a diverged family and carry out related functions from bacteria to mammals.
    Additional Material: 3 Ill.
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  • 91
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 9 (1993), S. 441-463 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 1 Tab.
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  • 92
    ISSN: 0749-503X
    Keywords: Peroxisome ; immunofluorescence ; PTS-1 ; electroporation ; yeast ; targeting ; biogenesis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We describe the isolation and characterization of peroxisomal assembly mutants in the genetically manipulable yeast Yarrowia lipolytica (pay mutants). These mutants were initially identified as oleic acid-non-utilizers by their inability to grow on oleic acid, the utilization of which requires peroxisomal β-oxidation enzymes. Identification of a subset of oleic acid-non-utilizers as pay mutants was obtained by a rapid immunofluorescence procedure using antibodies to the peroxisomal targeting signal Ser-Lys-Leu-CO2H. Punctate structures characteristic of peroxisomes were not detected in pay mutants using this technique. This rapid identification by immunofluorescence should be generally applicable to the selection of peroxisomal assembly mutants in other yeasts. To take advantage of the pay mutant system, we constructed a genomic library in the autonomously replicating vector pINA445 and developed an efficient and rapid electroporation procedure for the functional complementation of these mutants. We have been successful in functionally complementing two independent pay mutants. Molecular analysis of these and other complementing genes will allow for characterization of some of the cellular elements involved in peroxisomal assembly.
    Additional Material: 6 Ill.
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  • 93
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    Yeast 9 (1993), S. 533-541 
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; starch utilization ; extracellular glucoamylase ; regulatory mutants ; carbon catabolite (glucose) repression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A diastatic strain of Saccharomyces cerevisiae producing the STA2-encoded extracellular glucoamylase (GA) in a pronounced glucose-repressible fashion was used as a parent for generating mutants with reduced GA activity under normal conditions of derepression. In addition to mutations in STA2, five other recessive mutations were identified which fell into four complementation groups designated haf1 through haf4. RNA blot analysis suggested that the haf mutations confer defects in STA2 transcription. The haf mutants were pleiotropically defective in utilization of alternative carbon sources and resembled the snf (sucrose non-fermenting) mutants identified previously as unable to derepress the expression of the SUC2 gene encoding invertase. We present evidence strongly suggesting that haf1 = snf2, haf3 = snf1 and haf4 = snf5. By phenotypic criteria, the postulated HAF2 gene (which is none of the SNF genes tested) appears to be similar to SNF2, SNF5 and SNF6, and is possibly a non-redundant extension of this group of functionally related SNF genes.
    Additional Material: 1 Ill.
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  • 94
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    Yeast 9 (1993), S. 589-598 
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; Kluyveromyces lactis ; killer toxin ; fungal chitin ; cell wall mutants ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Kluyveromyces lactis killer toxin causes sensitive strains of a variety of yeasts to arrest at the G1 stage of the cell cycle, and to lose viability. We describe here the isolation and characterization of a class of recessive mutations in Saccharomyces cerevisiae that leads to toxin resistance and a temperature-sensitive phenotype. These mutant cells arrest growth at 37°C with a characteristic phenotype of elongated buds. Cloning of the gene complementing these defects revealed it to be CAL1, coding for chitin synthase 3 activity. Calcofluor staining of the mutant cells indicated that chitin is absent both at 23°C and 37°C. Given that the CAL1 activity is responsible for the synthesis of most of chitin in yeast cells, and that in its absence the cells are viable but resistant to the killer toxin, our results strongly suggest that chitin might represent the receptor for this killer toxin.
    Additional Material: 5 Ill.
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  • 95
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 9 (1993), S. 613-623 
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; heme biosynthesis ; uroporphyrinogen decarboxylase ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: HEM6 (HEM12) in Saccharomyces cerevisiae encodes uroporphyrinogen decarboxylase, the fifth enzyme in the heme biosynthetic pathway. The HEM6 (HEM12) gene was cloned by complementation of heme auxotrophy of a hem6 mutant. Sequence analysis revealed an open reading frame of 1086 nucleotides. The predicted amino acid sequence of HEM6 (HEM12) shows extensive homology to those reported for uroporphyrinogen decarboxylase from mammalian sources. Expression of HEM6 (HEM12) was investigated and was found to increase two-fold in a non-fermentable carbon source. However, HEM6 (HEM12) transcription was unaffected by heme or by intermediates in the heme biosynthetic pathway. In addition, HEM6 (HEM12) expression is not regulated by the transcriptional activator complex HAP2-3-4, as has been shown for some genes encoding heme biosynthetic enzymes.
    Additional Material: 5 Ill.
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  • 96
    ISSN: 0749-503X
    Keywords: Yeast ; genome ; ribosomal protein L21 ; RIM2 ; ATP carrier ; MSI1 ; IRA1 ; GAP ; PGI1 ; glycolytic genes ; leucine zipper ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report the DNA sequence of an 8 kb segment localized on the right arm of chromosome II from Saccharomyces cerevisiae. The sequence reveals the presence of eight open reading frames (ORFs). Three of them, YBR1402, YBR1405 and YBR1406 are previously sequenced genes, respectively the RIM2 (replication in mitochondria), MSI1 (multicopy suppressor of IRA1 gene) and PGI1 (phosphoglucoisomerase) genes. The predicted product of the ORF YBR1401 could be the putative yeast ribosomal protein L21. A new essential gene, YBR1403, has been identified by disruption; it possesses a leucine zipper motif.
    Additional Material: 6 Ill.
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  • 97
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    Yeast 9 (1993), S. 715-722 
    ISSN: 0749-503X
    Keywords: Gene fusion ; protein purification ; glutathione S-transferase ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A rapid and convenient method of protein purification involves creating a fusion protein with glutathione S-transferase (GST) (Smith and Johnson, Gene 67, 31-40, 1988). In this report, we describe two vectors for the conditional expression of GST fusions in Saccharomyces cerevisiae. The parent plasmid is based on a high-copy, galactose-inducible shuttle vector previously described (Baldari et al., EMBO J. 6, 229-243, 1987). We have demonstrated the use of this system by creating fusions between GST and the yeast RAS2 gene. GST-Ras2 fusion proteins undergo the post-translational modifications required for Ras2p to become membrane localized. These vectors provide a useful system for the expression an dpurification of eukaryotic proteins requiring post-translational modification.
    Additional Material: 4 Ill.
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  • 98
    ISSN: 0749-503X
    Keywords: Candida utilis ; short-chain carboxylic acids ; transport ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cells of the yeast Candida utilis grown in medium with short-chain mono-, di- or tricarboxylic acids transported L(-)malic acid by two transport systems at pH 3·0. Results indicate that probably a proton symport for the ionized form of the acid and a facilitated diffusion for the undissociated form were present. Dicarboxylic acids such as succinic, fumaric, oxaloacetic and α-ketoglutaric acids were competitive inhibitors of the malic acid for the high-affinity system, suggesting that these acids used the same transport system. In turn, competitive inhibition uptake studies of labelled carboxylic acid in the low-affinity range indicated that this system was non-specific and able to accept not only carboxylic (mono-, di- or tri-) acids but also some amino acids. Additionally, under the same growth conditions, C. utilis produced two mediated transport systems for lactic acid: a proton symport for the anionic form which appeared to be a common monocarboxylate carrier and a facilitated diffusion system for the undissociated acid displaying a substrate specificity similar to that observed for the low-affinity dicarboxylic acid transport. The mediated carboxylic acid transport systems were inducible and subjected to repression by glucose. In glucose-grown cells the undissociated dicarboxylic acids entered the cells slowly by simple diffusion. Repressed glucose-grown cells were only able to produce both transport systems if an inducer, at low concentration (0·5%, w/v), was present during starvation in buffer. This process was inhibited by the presence of cycloheximide indicating that induction requires de novo protein synthesis. If a higher acid concentration was used, only the low-affinity transport system was detectable, showing that the high-affinity system was also repressed by high concentrations of the inducer.
    Additional Material: 8 Ill.
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  • 99
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 9 (1993) 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 100
    ISSN: 0749-503X
    Keywords: Respiration ; fermentation ; glycolysis ; carbon dioxide ; mitochondria ; oxygen ; ethanol tolerance ; yeast ; membrane fluidity ; mass spectrometry ; microsomes ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Saccharomyces cerevisiae HSc was grown with ethanol at concentrations up to 10% (v/v). The immediate effects of additions of externally added ethanol on CO2 production and O2 consumption of washed organisms were studied by stopped-flow membrane inlet quadrupole mass spectrometry. Fermentative activities of organisms grown with ethanol (0-5% v/v) showed similar sensitivities to inhibition by ethanol, whereas those grown with 10% (v/v) ethanol had become protected and were markedly less sensitive.The fluidity of subcellular membrane fractions was measured by determination of the temperature dependence of the rotational order parameter of the spin label 5-doxyl stearic acid (free radical) by electron spin resonance. Mitochondria prepared from yeasts grown with 0, 7 and 9% (v/v) ethanol showed similar overall fluidity, although differences in temperature-dependent behaviour indicate altered lipid composition or lateral phase separations. On the other hand the microsomal fraction from organisms grown with 9% ethanol showed a remarkable increase in fluidity. These data suggest that the protective effects of growth with ethanol near the limit of tolerance on fermentative activities may arise from altered plasma membrane fluidity properties.
    Additional Material: 6 Ill.
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