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  • Mutation
  • United States
  • Springer  (152)
  • American Association of Petroleum Geologists (AAPG)
  • Institute of Electrical and Electronics Engineers (IEEE)
  • Sächsisches Landesamt für Umwelt, Landwirtschaft und Geologie
  • Wiley-Blackwell - SSH
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Keywords
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  • 1
    Electronic Resource
    Electronic Resource
    Understanding agri-food networks as social relations (2000)
    Springer
    Agriculture and human values 17 (2000), S. 279-283 
    Details
    ISSN: 1572-8366
    Keywords: Agri-food network ; Gender ; Sustainable agriculture ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Actor network theory and supply chainmanagement theory provide suggestive researchdirections for understanding regional agri-foodnetworks. These theories claim that relationshipsbased upon trust and cooperation are critical to thestrength and vitality of the network. This means thatexploring and detailing these relationships among thesuppliers, producers, workers, processors, brokers,wholesalers, and retailers within specific regionalgeographies of these networks are critical forfurthering cooperation and trust. Key areas ofcooperation include resource sharing andapprenticeship programs. Employing food networks as akey unit of contextual analysis will deepen ourunderstanding of how to enhance their resiliency andvibrancy. Important questions can be raised about thedifference gender makes for farmers, brokers,entrepreneurs, and workers in local food networks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007692303118
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  • 2
    Electronic Resource
    Electronic Resource
    Mutation L210W of HIV-1 reverse transcriptase in patients receiving combination therapy (2000)
    Springer
    Journal of biomedical science 7 (2000), S. 507-513 
    Details
    ISSN: 1423-0127
    Keywords: AIDS ; Resistance ; Mutation ; Genotype ; Zidovudine ; Fitness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mutation L210W of HIV-1 reverse transcriptase (RT) is one of the six main mutations that confer in vivo resistance to zidovudine. Surprisingly, this mutation has received scant appraisal and its contribution to the genotypic resistance to nucleoside analogs is not well understood. The aim of this study was: (1) to study the frequency of mutation L210W in a large collection of HIV-1 sequences (2,049 samples, including 395 DNA and 1,654 RNA sequences) from patients receiving combination therapy, and (2) to analyze its association with the other mutations that confer resistance to zidovudine. A mutation at codon 210 (mainly L210W) was found in 647 (32%) of the 2,049 sequences analyzed. Only 43 (〈7%) of these 647 genomes were also mutated at codon 70 (p 〈 10−5). In contrast, 98% of these 647 sequences were also mutated at codon 215 (essentially T215Y/F), and 94% at codon 41 (mainly M41L). These data showing a close association between L210W, T215Y/F, and M41L, and a mutual exclusion between K70R and L210W, were confirmed by analyzing the sequences stored in the HIV-1 sequences available through the Stanford HIV RT and Protease Database. Follow-up studies demonstrated that L210W appeared always after T215Y/F. This observation is consistent with crystallographic studies which suggested that the aromatic side chain of Trp 210 could stabilize the interaction of Phe/Tyr215 with the dNTP-binding pocket. This molecular cross-talk between amino acid chains occurs nearby the conserved Asp113 residue. Since the lateral chain of Arg70 may also interact with Asp113, this is likely to create a sterical hindrance around this residue. Thus, the R→K reversion of codon 70 may represent a compensatory mechanism allowing a functional rearrangement of the dNTP-binding pocket in the mutated RT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253366
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  • 3
    Electronic Resource
    Electronic Resource
    A novel HLA-A*6816 allele possibly generated by a point mutation in a Chilean from Punta Arenas (Magellan Strait) (2000)
    Springer
    Immunogenetics 51 (2000), S. 257-260 
    Details
    ISSN: 1432-1211
    Keywords: Key words Amerindians ; Chileans ; HLA-A*6816 ; Mutation ; Gene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050618
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  • 4
    Electronic Resource
    Electronic Resource
    On the Mutation Rates of the Mitochondrial and Nuclear Genomes of Salmonid Fishes (2000)
    Springer
    Russian journal of marine biology 26 (2000), S. 432-438 
    Details
    ISSN: 1608-3377
    Keywords: Mutation ; phylogeny ; nuclear DNA ; mitochondrial DNA ; salmonid fishes ; divergence time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mutation rates of the mitochondrial and nuclear genomes of salmonid fishes were assessed on the basis of a phylogenetic study of 12 species representing four genera of the family Salmonidae. Analysis of the extent of divergence of the masu salmon Oncorhynchus masou and the Pacific trout Parasalmo suggests a high rate of mtDNA mutation in the masu salmon. However, the nuclear genome in this species has mutated relatively slowly. For the other 5 species of Pacific salmon, no discrepancy was found in the mutation rates of mitochondrial and nuclear DNA. Values of the absolute time of divergence of taxa, calculated for the two independently inherited parts of the salmonid genome, were approximately within the same range and coincided with those based on evolutionary hypotheses [1, 21].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009450906139
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic characterization of the 44D-45B region of the Drosophila melanogaster genome based on an F2 lethal screen (2000)
    Springer
    Molecular genetics and genomics 263 (2000), S. 137-143 
    Details
    ISSN: 1617-4623
    Keywords: Key wordsDrosophila ; Cytogenetic region 44D-45B ; EMS mutagenesis ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have performed an F2 genetic screen to identify lethal mutations that map to the 44D-45B region of the Drosophila melanogaster genome. By screening 8500 mutagenized chromosomes for lethality over Df(2R)Np3, a deficiency which encompasses nearly 1% of the D. melanogaster euchromatic genome, we recovered 125 lines with lethal mutations that represent 38 complementation groups. The lethal mutations have been mapped to deficiencies that span the 44D-45B region, producing an approximate map position for each complementation group. Lethal mutations were analyzed to determine the phase of development at which lethality occurred. In addition, we have linked some of the complementation groups to P element-induced lethals that map to 44D-45B, thus possibly providing new alleles of a previously tagged gene. Some of the complementation groups represent potentially novel alleles of previously identified genes that map to the region. Several genes have been mapped by molecular means to the 44D-45B region, but do not have any reported mutant alleles. This screen may have uncovered mutant alleles of these genes. The results of complementation tests with previously identified genes in 44D-45B suggests that over half of the complementation groups identified in this screen may be novel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380050040
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  • 6
    Electronic Resource
    Electronic Resource
    Preliminary distributional analysis of US endangered bird species (2000)
    Springer
    Biodiversity and conservation 9 (2000), S. 1313-1322 
    Details
    ISSN: 1572-9710
    Keywords: BIOCLIM ; birds ; conservation strategies ; ecological niche modeling ; endangered species ; GARP ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A first exploration of applications of ecological niche modeling and geographic distributional prediction to endangered species protection is developed. Foci of richness of endangered bird species are identified in coastal California and along the southern fringe of the United States. Species included on the Endangered Species List on the basis of peripheral populations inflate these concentrations considerably. Species without protection in the US National Park System are focused particularly in peninsular Florida. Application of this methodology to additional taxa and regions holds promise for diverse conservation applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008924322405
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  • 7
    Electronic Resource
    Electronic Resource
    Western migrants in central Europe: Isolated individuals or members of transnational communities? (2000)
    Springer
    GeoJournal 50 (2000), S. 105-108 
    Details
    ISSN: 1572-9893
    Keywords: community ; Czech Republic ; East Central Europe ; ethnicity ; migration ; Prague ; social exclusion ; transnationalism ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Abstract Migration flows from western Europe, the United States and Canada to east central Europe have received little attention so far. But numbers are now considerable and in the context of globalisation it seems appropriate to conceptualise communities of Westerners in terms of transnational social spaces as defined by Glick Schiller et al. Study of Americans in Prague reveals three main groups: enterprise managers, lifestyle migrants and entrepreneurs in small and medium-sized enterprises. All are engaged in a variety of different processes of community-building, often with clear trends towards a new transnationalism. Yet, the individual attempt to live in two societies is limited by the marked boundaries of the communities and by the degree of social exclusion which they experience from the majority population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007183532417
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  • 8
    Electronic Resource
    Electronic Resource
    Fibrillin gene (FBN1) mutations in Japanese patients with Marfan syndrome (2000)
    Springer
    Journal of human genetics 45 (2000), S. 115-118 
    Details
    ISSN: 1435-232X
    Keywords: Key words Marfan syndrome ; FBN1 ; Fibrillin-1 ; Japanese ; Mutation ; Gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Marfan syndrome (MFS; MIM #154700) is a connective tissue disorder characterized by cardiovascular, skeletal, and ocular abnormalities. The fibrillin-1 gene (FBN1; MIM no. 134797) on chromosome 15 was revealed to be the cause of Marfan syndrome. To date over 137 types of FBN1 mutations have been reported. In this study, two novel mutations and a recurrent de-novo mutation were identified in patients with MFS by means of single-strand conformational polymorphism (SSCP) analysis. The two novel mutations are a 4-bp deletion at nucleotide 2820-2823 and a G-to-T transversion at nucleotide 1421 (C474F), located on exon 23 and exon 11, respectively. A previously reported mutation at the splicing donor site of intron 2 (IVS2 G + 1A), which is predicted to cause exon skipping, was identified in a sporadic patient with classical MFS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380050027
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  • 9
    Electronic Resource
    Electronic Resource
    Novel mutations of the FANCG gene causing alternative splicing in Japanese Fanconi anemia (2000)
    Springer
    Journal of human genetics 45 (2000), S. 159-166 
    Details
    ISSN: 1435-232X
    Keywords: Key words Fanconi anemia ; Mutation ; the FANCA gene ; the FANCC gene ; the FANCG gene ; Alternative splicing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Fanconi anemia (FA), an autosomal recessive disorder characterized by a progressive pancytopenia associated with congenital anomalies and high predisposition to malignancies, is a genetically and clinically heterogeneous disease. At least eight complementation groups (FA-A to FA-H) have been identified. Previously, we studied mutations of the FANCA gene, responsible for FA-A, and found pathogenic mutations in 12 of 15 unclassified Japanese FA patients. Here, we further studied an additional 5 FA patients for sequence alterations of the FANCA gene and found pathogenic mutations in 2 of them. We further analyzed mutations of the FANCC and FANCG genes, responsible for FA-C and FA-G, respectively, in the remaining 6 FA patients. Although there was no alterations in the FANCC gene in these 6 patients, two novel mutations of the FANCG gene, causing aberrant RNA splicing, were detected in 2 FA patients. One was a base substitution from G to C of the invariant GT dinucleotides at the splice donor site of intron 3, resulting in the skipping of exon 3, as well as the skipping of exons 3 and 4. The other was a base substitution from C to T in exon 8, creating a nonsense codon (Q356X). This mutation resulted in the exclusion of a sequence of 18 nucleotides containing the mutation from the mRNA, without affecting the splicing potential of either the authentic or the cryptic splice donor site. Collectively, 14 of the 20 unclassified Japanese FA patients belong to the FA-A group, 2 belong to the FA-G group, and none belongs to the FA-C group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380050203
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  • 10
    Electronic Resource
    Electronic Resource
    Novel mutation of L718X in the ATP7A gene in a Japanese patient with classical Menkes disease, and four novel polymorphisms in the Japanese population (2000)
    Springer
    Journal of human genetics 45 (2000), S. 315-317 
    Details
    ISSN: 1435-232X
    Keywords: Key words Menkes disease ; ATP7A gene ; MNK gene ; Mutation ; Polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Menkes disease is an X-linked recessive disorder of the copper membrane transport system caused by mutations in the ATP7A gene. While various mutations in the ATP7A gene have been reported, a genotype-phenotype correlation has not been clearly defined. A novel mutation in the ATP7A gene in a Japanese patient with classical Menkes disease was identified via analysis of reverse-transcriptase polymerase chain reaction products and genomic DNA of the ATP7A gene. The nonsense mutation, L718X, was found to result in premature termination and immature ATP7A protein, unlikely to have normal functioning. Therefore, this nonsense mutation of the ATP7A gene is proposed to play a causative role in presenting the classical Menkes phenotype. Furthermore, four novel polymorphisms, C1535T (L464L), C2151T (T669I), G2253A (R703H), and C3677T (H1178Y) were also identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380070024
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  • 11
    Electronic Resource
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    Haplotype analysis suggests that the two predominant mutations in Japanese patients with holocarboxylase synthetase deficiency are founder mutations (2000)
    Springer
    Journal of human genetics 45 (2000), S. 358-362 
    Details
    ISSN: 1435-232X
    Keywords: Key words Holocarboxylase synthetase ; Multiple carboxylase deficiency ; Biotin ; Mutation ; Microsatellite markers ; Haplotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Holocarboxylase synthetase (HCS) deficiency is a rare autosomal recessive disorder of biotin metabolism. Including three new Japanese patients we diagnosed in this study, ten Japanese families have, so far, been accumulated. In these families, the mutations 237Leu 〉 Pro (sevenalleles) and 1067delG (five alleles) were predominant; 508Arg 〉 Trp and 550Val 〉 Met mutations were identified in three families in the heterozygous form and in one patient in the homozygous form, respectively. To determine the origin of these mutations, we identified new polymorphic microsatellite markers in the HCS gene and analyzed the haplotypes of the patients. All the 237Leu 〉 Pro and the 1067delG alleles were associated with haplotype 2-2. This finding is consistent with the notion that these mutations are founder mutations in the Japanese population. Three Japanese 508Arg 〉 Trp alleles were associated with several haplotypes, including 2-3 and 1-4. The haplotype of a Taiwanese patient homozygous for the 508Arg 〉 Trp mutation was 2-3/2-3. The haplotype of one Japanese patient homozygous for the 550Val 〉 Met mutation was 1-4/1-4, whereas that of a Jewish patient with the same homozygous mutation was 2-3/2-3. Both mutations were associated with at least two haplotypes and were found in several ethnic groups. The changes 508Arg 〉 Trp and 550Val 〉 Met occurred at CpG dinucleotide. The data suggest that these two mutations represent a mutational hot-spot.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380070008
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  • 12
    Electronic Resource
    Electronic Resource
    A nonsense mutation at Arg-1947 in the NF1 gene in a case of neurofibromatosis type 1 in a Korean patient (2000)
    Springer
    Journal of human genetics 45 (2000), S. 84-85 
    Details
    ISSN: 1435-232X
    Keywords: Key words Hot spot ; Mutation ; Neurofibromatosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We report a case of neurofibromatosis (NF) 1 presenting as a C-to-T transition changing an Arg-1947 codon to a stop codon. Because this mutation has been described in multiple Caucasian and Japanese families, the codon CGA for Arg-1947 in the NF1 gene is considered to be a hotspot for mutation in neurofibromatosis type 1 in all ethnic groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380050016
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  • 13
    Electronic Resource
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    Glucose-6-phosphatase gene mutations in Taiwan Chinese patients with glycogen storage disease type Ia (2000)
    Springer
    Journal of human genetics 45 (2000), S. 197-199 
    Details
    ISSN: 1435-232X
    Keywords: Key words Glycogen storage disease type Ia ; Glucose-6-phosphatase ; Mutation ; Chinese ; Taiwan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Glycogen storage disease type Ia (GSD Ia) is caused by a deficiency of glucose-6-phosphatase (G6Pase) activity. Eighteen GSD Ia families were studied for G6Pase gene mutations. Thirty-two mutations were found in 36 GSD Ia chromosomes: 16 were 727 G→T (44.44%); 13 were R83H (327 G→T; 36.11%); 1 was 341delG; 1 was 933insAA; and 1 was 793 G→T. The 727 G→T and R83H mutations together accounted for 80.56% (29/36) of the GSD Ia chromosomes. These two mutations were easily examined by polymerase chain reaction-based methods, and the prenatal diagnosis of a non-affected fetus was successfully made. The 727 G→T mutation is the predominant mutation in Japanese GSD Ia patients, but is rarely seen in Western counties. The 727 G→T mutation is also the most prevalent mutation in Taiwan Chinese, although the incidence is not as high as in Japan.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380070026
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  • 14
    Electronic Resource
    Electronic Resource
    Mutational analysis of the MECP2 gene in Japanese patients with Rett syndrome (2000)
    Springer
    Journal of human genetics 45 (2000), S. 231-236 
    Details
    ISSN: 1435-232X
    Keywords: Key words Rett syndrome ; Mental retardation ; MECP2 gene ; Methyl-CpG-binding protein ; X chromosome dominant ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Rett syndrome is a neurodevelopmental disorder observed almost exclusively in girls, and is characterized by autistic tendency, severe mental retardation, stereotyped hand movements, seizures, and acquired microcephaly. Recently, the MECP2 (methyl-CpG-binding protein 2) gene, mapped on chromosome Xq28, was reported to be responsible for Rett syndrome. We performed mutational analysis of the MECP2 gene in 26 Japanese patients with Rett syndrome (who were sporadic cases), and identified disease alleles in 19 patients. The mutations consisted of 12 different types including 3 missense, 3 nonsense, and 6 frameshift mutations. Of these, 8 mutations are novel. Most of these mutations affect the functional domains, methyl-CpG binding domain (MBD), and transcriptional repression domain (TRD), and therefore may critically affect the function of MeCP2. The disease phenotype of patients with mutations in the MBD tended to be more severe than the phenotype of those with mutations in the TRD. We also identified 2 types of silent mutations and 4 types of missense mutations as benign variants, and these are all novel ones. Most of the nucleotide substitutions involve C → T transitions at CpG hotspots. The novel disease alleles and benign variants of the MECP2 gene found in this study should contribute to the establishment of a reliable diagnosis of Rett syndrome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380070032
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  • 15
    Electronic Resource
    Electronic Resource
    Novel mutations of the ATP7B gene in Japanese patients with Wilson disease (2000)
    Springer
    Journal of human genetics 45 (2000), S. 86-91 
    Details
    ISSN: 1435-232X
    Keywords: Key words Wilson disease ; ATP7B gene ; Mutation ; Polymorphism ; Japanese
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Wilson disease (WD) is an autosomal recessive disorder characterized by copper accumulation in the liver, brain, kidneys, and corneas, and culminating in copper toxication in these organs. In this study, we analyzed mutations of the responsible gene, ATP7B, in four Japanese patients with WD. By direct sequencing, we identified five mutations, of which two were novel, and 16 polymorphisms, of which 6 were novel. The mutations 2871delC and 2513delA shift the reading frame so that truncated abnormal protein is expected. In contrast to these mutations found in patients with hepatic-type of early onset, the mutations A874V, R778L, and 3892delGTC were either missense mutations or inframe 1-amino acid deletion, and occurred in the patients with hepato-neurologic type of late onset. The mutations 2871delC and R778L have been previously reported in a relatively large number of Japanese patients. In particular, R778L is known to be more prevalent in Asian countries than in other countries of the world. Our data are compatible with the hypothesis that the mutations tend to occur in a population-specific manner. Therefore, the accumulation of the types of mutations in Japanese patients with WD will facilitate the fast and effective genetic diagnosis of WD in Japanese patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380050017
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  • 16
    Electronic Resource
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    A novel nonsense mutation of the PEPD gene in a Japanese patient with prolidase deficiency (2000)
    Springer
    Journal of human genetics 45 (2000), S. 102-104 
    Details
    ISSN: 1435-232X
    Keywords: Key words PEPD ; Prolidase deficiency ; Mutation ; Polymorphism ; Nonsense mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A nonsense mutation at amino acid residue 184 in the human peptidase D (PEPD) gene caused the production of a truncated polypeptide. Characterizing molecular defects in patients provides clues to elucidate the relationship between the phenotype and the genotype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380050023
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  • 17
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    A novel interstitial deletion of KAL1 in a Japanese family with Kallmann syndrome (2000)
    Springer
    Journal of human genetics 45 (2000), S. 237-240 
    Details
    ISSN: 1435-232X
    Keywords: Key words Kallmann syndrome ; KAL1 ; Mutation ; Anosmia ; Hypogonadism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We identified a novel interstitial deletion that spanned from exons 5 to 10 of KAL1 in two Japanese brothers with X-linked Kallmann syndrome (KS; MIM no. 308700). Both brothers had hypogonadism, unilateral renal agenesis, and disturbance of the sense of smell, but they had no other neurological manifestations, including mental disturbance. Their mother was confirmed to be an asymptomatic carrier, by use of a comparative multiplex polymerase chain reaction (PCR) analysis. The present patients are further examples of patients with KS without mental disturbance caused by a mutation confined to KAL1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380070033
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  • 18
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    The BRCA2 genetic variant IVS7 + 2T → G is a mutation (2000)
    Springer
    Journal of human genetics 45 (2000), S. 351-357 
    Details
    ISSN: 1435-232X
    Keywords: Key wordsBRCA2 ; RNA ; Splice ; Mutation ; Intron ; Cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Biochemical and genetic characterizations that support the conclusion that the variant BRCA2 IVS7 + 2T → G represents a deleterious mutation are presented. RNA analysis from a breast cancer patient with BRCA2 IVS7 + 2T → G showed that the productive message was produced from only one chromosome. A haplotype analysis confirmed that the intronic variant resides on the chromosome that does not produce the normal mRNA. Additionally, an RNA splicing product that deletes exon 7 was produced by the chromosome that carries BRCA2 IVS7 + 2T → G. The deletion of exon 7 from the RNA alters the open reading frame by removing residues 249–287 and incorporating 18 abnormal amino acids before terminating with an opal stop codon. The experimental approach presented produces strong evidence of the presence of a deleterious mutation, because the contribution by both chromosomes to each RNA species analyzed was tracked using a coding region polymorphism as a marker. Furthermore, a single nucleotide polymorphism (SNP) haplotype analysis that confirms the location of the intronic variant and an associated family history that shows a high incidence of cancer supported these biochemical data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380070007
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  • 19
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    A novel type X collagen gene mutation (G595R) associated with Schmid-type metaphyseal chondrodysplasia (2000)
    Springer
    Journal of human genetics 45 (2000), S. 105-108 
    Details
    ISSN: 1435-232X
    Keywords: Key words Metaphyseal chondrodysplasia Schmid type (MCDS) ; Mutation ; Type X collagen gene (COL10A1) ; Carboxyl-terminal noncollagenous (NC1) domain ; Spondylometaphyseal dysplasia (SMD) ; Type X collagenopathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Metaphyseal chondrodysplasia of the Schmid type (MCDS) is a skeletal dysplasia affecting the long bone metaphyses; it is characterized by short stature, bowlegs, and coxa vara. The spine is generally not involved. Here we report a novel missense mutation of the type X collagen gene in a sporadic case of MCDS. The mutation was a heterozygous single base-pair transition of G-to-A at nucleotide 1783, which predicted a substitution of glycine by arginine at codon 595 (G595R) in the carboxyl-terminal noncollagenous domain. Interestingly, another mutation of the same codon, in which glycine is substituted by glutamic acid (G595E), was previously reported to cause spondylometaphyseal dysplasia (SMD), another group of skeletal dysplasias with involvement of the spine in addition to the long tubular bones. The novel G595R mutation identified in the present study supports the concept of type X collagenopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380050024
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  • 20
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    Seeing Patterns: Models, Visual Evidence and Pictorial Communication in the Work of Barbara McClintock (1999)
    Springer
    Journal of the history of biology 32 (1999), S. 163-195 
    Details
    ISSN: 1573-0387
    Keywords: cytogenetics ; diagrams ; genetics ; illustrations ; McClintock ; models ; molecular biology ; photographs ; twentieth-century ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Notes: Abstract Barbara McClintock won the Nobel Prize in 1983 for her discovery of mobile genetic elements. Her Nobel work began in 1944, and by 1950 McClintock began presenting her work on “controlling elements.” McClintock performed her studies through the use of controlled breeding experiments with known mutant stocks, and read the action of controlling elements (transposons) in visible patterns of pigment and starch distribution. She taught close colleagues to “read” the patterns in her maize kernels, “seeing” pigment and starch genes turning on and off. McClintock illustrated her talks and papers on controlling elements or transposons with photographs of the spotted and streaked maize kernels which were both her evidence and the key to her explanations. Transposon action could be read in the patterns by the initiated, but those without step by step instruction by McClintock or experience in maize often found her presentations confusing. The photographs she displayed became both McClintock's means of communication, and a barrier to successful presentation of her results. The photographs also had a second and more subtle effect. As images of patterns arrived at through growth and development of the kernel, they highlight what McClintock believed to be the developmental consequences of transposition, which in McClintock's view was her central contribution, over the mechanism of transposition, for which she was eventually recognized by others. Scientific activities are extremely visual, both at the sites of investigation and in communication through drawings, photographs, and movies. Those visual messages deserve greater scrutiny by historians of science.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004420726771
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    The structure of the llama heavy chain constant genes reveals a mechanism for heavy-chain antibody formation (1999)
    Springer
    Immunogenetics 50 (1999), S. 98-101 
    Details
    ISSN: 1432-1211
    Keywords: Key words Llama ; splice ; CH1 ; Antibody ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050694
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    Genomic organization of the HSET locus and the possible association of HLA-linked genes with immotile cilia syndrome (ICS) (1999)
    Springer
    Immunogenetics 49 (1999), S. 644-652 
    Details
    ISSN: 1432-1211
    Keywords: Key words HLA complex ; Immotile cilia syndrome ; Mutation ; Kinesin multigene family ; Human Chromosome 6
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The kinesin-related protein (HSET) gene belongs to the kinesin superfamily, the members of which are involved in cellular transport processes. The HSET gene product was previously characterized by partial cDNA sequencing. The gene is located on the short arm of human Chromosome 6 (6p21.3), at the centromeric end of the major histocompatibility complex. Here, we report the genomic structure of the complete HSET gene together with its flanking loci. Sequence analysis of the 40 kilobase (kb) cosmid clone containing the HSET gene also revealed the presence of several new genes not related to the kinesin superfamily. These include a 60S ribosomal protein L35A-like pseudogene (rPL35A-like) on the telomeric side and a polycomb-like gene (PHF1), a copper tolerance-like gene (CUTA1) and the 5' part of the synaptic ras-GTPase-activating protein (SynGAP) gene centromeric of HSET. In addition, a complete 60S ribosomal protein L12-like (rPL12L) gene in intron 3 of the HSET gene was identified which appears to have an open reading frame. The possible involvement of the HSET gene and a β-tubulin gene (TUBB) in the pathogenesis of immotile cilia syndrome (ICS) was studied by screening two unrelated ICS families with microtubular defects and suspected HLA linkage for mutations within the HSET gene and the TUBB gene. Four single base substitutions were detected in the HSET gene, and none in the TUBB gene. On the basis of these data, a role of the HSET and TUBB products in the pathogenesis of ICS in the two families is unlikely.
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    URL: http://dx.doi.org/10.1007/s002510050660
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    Polymorphism around cog extends into adjacent structural genes (1999)
    Springer
    Current genetics 35 (1999), S. 631-637 
    Details
    ISSN: 1432-0983
    Keywords: Key words Recombinator ; Meiotic recombination ; Polymorphism ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The recombination hotspot cog overlaps a highly polymorphic 950-bp region of linkage group I in Neurospora crassa. The sequence of this region in the four strains, Lindegren 25a, Lindegren A, Emerson A and St. Lawrence 74A, each differs from the others by 1.4% or more. Comparison of the sequence of St. Lawrence 74A and Lindegren 25a each side of cog shows a high level of sequence heterology extending in both directions, including the coding sequences for his-3 and a putative gene lpl with homology to yeast lysophospholipase. The St. Lawrence 74A and Lindegren 25a sequences of his-3, centromere-proximal to cog, differ at 14 nucleotides, resulting in six amino-acid variations between the predicted protein sequences. In lpl, distal from cog, the sequences differ at 19 nucleotides leading to five amino-acid differences between the predicted proteins. Sequence heterology between St. Lawrence 74A and Lindegren 25a peaks either side of cog and then declines with distance. At the am locus on linkage group V, heterology is much less but peaks close to a weak recombination hotspot 5′ of the coding sequence. Uneven distribution of polymorphism along chromosomes has been explained by a hitch-hiking hypothesis in which selection for advantageous mutations causes local fixation of unselected variation. We suggest that new mutations arising from errors in recombination also contribute to the uneven distribution of polymorphism.
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    URL: http://dx.doi.org/10.1007/s002940050462
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    Characterisation of resistance to turnip mosaic virus in oilseed rape (Brassica napus) and genetic mapping of TuRB01 (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 1149-1154 
    Details
    ISSN: 1432-2242
    Keywords: Key words Brassica ; TuMV Resistance ; Genetic mapping ; Mutation ; Plant breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Turnip mosaic virus (TuMV) is the major virus infecting Brassica crops. A dominant gene, TuRB01, that confers extreme resistance to some isolates of TuMV on Brassica napus (oilseed rape), has been mapped genetically. The mapping employed a set of doubled-haploid lines extracted from a population used previously to develop a reference RFLP map of the B. napus genome. The positioning of TuRB01 on linkage group N6 of the B. napus A–genome indicated that the gene probably originated from Brassica rapa. Resistance phenotypes were confirmed by indirect plate-trapped antigen ELISA using a monoclonal antibody raised against TuMV. The specificity of TuRB01 was determined using a wide range of TuMV isolates, including representatives of the European and American/Taiwanese pathotyping systems. Some isolates of TuMV that did not normally infect B. napus plants possessing TuRB01 produced mutant viruses able to overcome the action of the resistance gene. TuRB01 is the first gene for host resistance to TuMV to be mapped in a Brassica crop. A second locus, TuRB02, that appeared to control the degree of susceptibility to the TuMV isolate CHN 1 in a quantitative manner, was identified on the C-genome linkage group N14. The mapping of other complementary genes and the selective combining of such genes, using marker-assisted breeding, will make durable resistance to TuMV a realisable breeding objective.
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    URL: http://dx.doi.org/10.1007/s001220051319
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    Evolvability of machines and tapes (1999)
    Springer
    Artificial life and robotics 3 (1999), S. 242-245 
    Details
    ISSN: 1614-7456
    Keywords: Mutation ; Self-reproduction ; Evolvability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A self-reproduction process is described and discussed via a network model of machines and description tapes. The emergence of a core network which dynamically sustains the rewriting processes of machines on tapes is reported. The structures of the core networks are generic, and include Eigen's hypercycle as a special case. In the cell assembly model, where each cell contains machines and tapes, we show that the instability of the core network in some cells is sustained by those cells with stable core networks. The instability of the core network is transfered to its offspring when the cells divide. What is inherited here is not the patterns of tapes, but the way machines read tapes in a core network.
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    URL: http://dx.doi.org/10.1007/BF02481188
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    Molecular characterization of waxy mutations in wheat (1999)
    Springer
    Molecular genetics and genomics 261 (1999), S. 463-471 
    Details
    ISSN: 1617-4623
    Keywords: Key words Granule-bound starch synthase ; Starch ; Waxy ; Wheat ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To date, few mutations in wheat have been characterized at the molecular level. In this study, the mutations in the three waxy alleles in waxy wheat (Wx-A1b,Wx-B1b and Wx-D1b) were characterized, and waxy gene expression was compared in several wheat lines, including hexaploid and tetraploid waxy lines of wheat. Southern analysis showed that the Wx-B1b allele had sustained a deletion which included the entire coding region of the Wx-B1 gene. DNA homologous to waxy gene sequences was still present in the Wx-A1b and Wx-D1b alleles of the hexaploid waxy mutant. Transcripts of waxy alleles were also detected in both hexaploid and tetraploid mutants at 10 days post-anthesis, but the transcript level was dramatically reduced compared to that found in non-waxy lines. Isolation of cDNAs showed that transcripts were produced by both the Wx-A1b and Wx-D1b alleles. A 23-bp deletion sustained by the Wx-A1b allele at an exon-intron junction results in the use of a cryptic splice site during mRNA processing. The deduced translation product encoded by the Wx-A1b cDNA lacks 39 amino acids, including the putative ADP-glucose binding site and a portion of the transit peptide. The C-terminal region of the deduced protein encoded by the Wx-D1b cDNA lacks the last 30 amino acids. Comparison of the genomic sequences of the null and wild-type Wx-D1 alleles indicated that 588 bp were deleted in the Wx-D1b mutation, and that the last 261 bp of the Wx-D1b cDNA originated from the normally non-transcribed 3′ flanking region. Like several deletion mutations characterized in other plant species, both Wx-A1b and Wx-D1b alleles contain small DNA insertions, or filler DNA, between the deletion end-points.
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    URL: http://dx.doi.org/10.1007/s004380050989
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    Germline mutations of E-cadherin gene in Korean familial gastric cancer patients (1999)
    Springer
    Journal of human genetics 44 (1999), S. 177-180 
    Details
    ISSN: 1435-232X
    Keywords: Key words Familial gastric cancer ; E-cadherin ; Germline ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Gastric cancer is the most common cancer in Korea. Germline mutations of the E-cadherin gene have recently been identified in familial gastric cancer patients. We screened five Korean familial gastric cancer patients to investigate germline mutations of the E-cadherin gene. These patients fulfilled the following criteria: presence of at least two gastric cancer patients within first-degree relatives and one patient diagnosed before the age of 50 years. Abnormal band patterns were found in exons 6 and 10 in two familial gastric cancer patients by polymerase chain reaction-single strand conformation polymorphism analysis (probands from the SNU-G2 and SNU-G1001 families, respectively). DNA sequencing analysis of the E-cadherin gene of these two patients revealed missense mutations in each exon. The SNU-G2 proband harbored a missense mutation from aspartic acid (GAT) to glycine (GGT) at codon 244 in exon 6 of the E-cadherin gene, and the SNU-G1001 proband had a missense mutation from valine (GTG) to alanine (GCG) at codon 487 in exon 10. The SNU-G2 proband was diagnosed with gastric cancer at the age of 38; three brothers and two sisters had died of gastric cancer under the age of 50, and their mother had died of gastric cancer at the age of 63. The SNU-G1001 proband was diagnosed with gastric cancer at the age of 42 and one brother had died of gastric cancer at the age of 49. In summary, we found germline mutations of the E-cadherin gene in two of five Korean familial gastric cancer patients screened.
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    URL: http://dx.doi.org/10.1007/s100380050137
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    Molecular characterization of galactokinase deficiency in Japanese patients (1999)
    Springer
    Journal of human genetics 44 (1999), S. 377-382 
    Details
    ISSN: 1435-232X
    Keywords: Key words Galactosemia ; Galactokinase (GALK) ; Mutation ; Genotype ; Phenotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Galactokinase (GALK) deficiency is an autosomal recessive disorder, which causes cataract formation in children not maintained on a lactose-free diet. We characterized the human GALK gene by screening a Japanese genomic DNA phage library, and found that several nucleotides in the 5′-untranslated region and introns 1, 2, and 5 in our GALK genomic analysis differed from published data. A 20-bp tandem repeat was found in three places in intron 5, which were considered insertion sequences. We identified five novel mutations in seven unrelated Japanese patients with GALK deficiency. There were three missense mutations and two deletions. All three missense mutations (R256W, T344M, and G349S) occurred at CpG dinucleotides, and the T344M and G349S mutations occurred in the conserved region. The three missense mutations led to a drastic reduction in GALK activity when individual mutant cDNAs were expressed in a mammalian cell system. These findings indicated that these missense mutations caused GALK deficiency. The two deletions, of 410delG and 509–510delGT, occurred at the nucleotide repeats GGGGGG and GTGTGT, respectively, and resulted in in-frame nonsense codons at amino acids 163 and 201. These mutations arose by slipped strand mispairing. All five mutations occurred at hot spots in the CpG dinucleotide for missense mutations and in short direct repeats for deletions. These five mutations in Japanese have not yet been identified in Caucasians. We speculate that the origin of GALK mutations in Japanese is different from that in Caucasians.
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    URL: http://dx.doi.org/10.1007/s100380050182
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    Molecular characterization of 6-pyruvoyl-tetrahydropterin synthase deficiency in Japanese patients (1999)
    Springer
    Journal of human genetics 44 (1999), S. 163-168 
    Details
    ISSN: 1435-232X
    Keywords: Key words 6-Pyruvoyl-tetrahydropterin synthase (PTPS) deficiency ; Tetrahydrobiopterin ; Mutation ; Missense ; Splicing ; Phenotype and genotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We identified three mutations in four Japanese patients with central type 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency. One missense mutation was a C-to-T transition, resulting in the substitution of Pro by Ser at codon 87 (P87S) in exon 5. Another missense mutation was a G-to-A transition, resulting in the substitution of Asp by Asn at codon 96 (D96N) in exon 5. A splicing mutation was found by skipping of exon 4 on PTPS mRNA analysis, and a G-to-A transition at the third base of codon 81 (E81E) and at the terminal base in exon 4 were detected on genomic PTPS DNA analysis. The E81E mutation affected the splice donor site of exon 4 and caused the splicing error. In COS cell expression analysis, the P87S and D96N mutant constructs revealed, respectively, 52% and 10% of wild-type activity. Patients with P87S/P87S (52%/52% in-vitro PTPS activity) exhibited 0.11 and 0 μU/g hemoglobin [Hb] in erythrocyte PTPS activity (wild-type control: 11-29 μU/gHb) erythrocyte PTPS activity, and the patient with P87S/D96N mutations (52%/10%) had 0.97 μU/gHb in PTPS erythrocyte activity. The PTPS erythrocyte activity did not coincide with the in-vitro PTPS activity based on patient genotype.
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    URL: http://dx.doi.org/10.1007/s100380050134
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    Mutational analysis of TSC1 and TSC2 genes in Japanese patients with tuberous sclerosis complex (1999)
    Springer
    Journal of human genetics 44 (1999), S. 391-396 
    Details
    ISSN: 1435-232X
    Keywords: Key words Tuberous sclerosis complex ; TSC1 gene ; TSC2 gene ; Hamartin ; Tuberin ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have surveyed the mutations of TSC1 and TSC2 from 38 (25 sporadic, 11 familial, and 2 unknown) Japanese patients with tuberous sclerosis complex. In 23 of 38 subjects, we detected 18 new mutations in addition to 4 mutations that had been previously reported. We also found 3 new polymorphisms. The mutations were not clustered on a particular exon in either of the genes. Seven TSC1 mutations found in 3 familial and 4 sporadic cases were on the exons (3 missense, 2 nonsense point mutations, a 1-base insertion, and a 2-bp deletion). Fifteen TSC2 mutations were found in 5 familial cases, 10 sporadic cases, and 1 unknown case. The 12 mutations were on the exons (8 missense, 1 nonsense point mutations, a 1-bp insertion, a 5-bp deletion, and a 4-bp replacement) and 3 point mutations were on the exon–intron junctions. Although the patients with TSC2 mutations tend to exhibit relatively severe mental retardation in comparison to those with TSC1 mutations, a genotype–phenotype correlation could not yet be established. The widespread distribution of TSC1/TSC2 mutations hinders the development of a simple diagnostic test, and the identification of individual mutations does not provide the prediction of prognosis.
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    URL: http://dx.doi.org/10.1007/s100380050185
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    Molecular analysis of methylmalonyl-CoA mutase deficiency: identification of three missense mutations in mut 0 patients (1999)
    Springer
    Journal of human genetics 44 (1999), S. 35-39 
    Details
    ISSN: 1435-232X
    Keywords: Key words Methylmalonic acidemia ; Methylmalonyl-CoA mutase ; Adenosylcobalamin ; Organic aciduria ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Genetic defects in the methylmalonyl-CoA mutase (MCM) gene cause methylmalonic acidemia (MMA). Only three mutations have been reported among Oriental patients to date. We studied fibroblast cell lines established from three Japanese patients with MCM deficiency. Enzymatic study showed that these patients had the mut 0 type of MMA. Nucleotide sequencing of MCM cDNAs identified three missense mutations: a T to A change at nucleotide position 2082, which results in an amino acid substitution of Glu669 for valine (V669E); a T to A change at position 1179 with the corresponding amino acid substitution of Asp368 for valine (V368D); and a G to A change at position 1182 with the corresponding amino acid substitution of His369 for arginine (R369H). Each of the three missense mutations abolished MCM activity according to a transient expression study. Alignment of these mutations with a recently reported homology model of human MCM allowed us to speculate on the effect of these nonconservative amino acid substitutions on MCM activity: V368D and R369H affected residues in the β/α-(TIM-) barrel domain, on one of the two α-helices that form the dimer interface, while V669E altered a residue in the adenosylcobalamin-binding domain in the C terminus.
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    EYA1 nonsense mutation in a Japanese branchio-oto-renal syndrome family (1999)
    Springer
    Journal of human genetics 44 (1999), S. 261-265 
    Details
    ISSN: 1435-232X
    Keywords: Key words Branchio-oto-renal (BOR) syndrome ; EYA1 ; Mutation ; Japanese ; Hearing impairment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Advances in molecular genetics have recently revealed that mutations in the EYA1 gene are responsible for branchio-oto-renal (BOR) syndrome in European and other populations. This is the first report confirming that an EYA1 gene mutation is also disease-causing in an Asian population. We have described one Japanese BOR syndrome family showing a novel mutation in exon 7 of the EYA1 gene. There was extensive variation of clinical phenotypes within this family. When the physician is confronted with a BOR family showing a wide variation in clinical expression, molecular genetic testing helps to achieve accurate diagnosis.
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    URL: http://dx.doi.org/10.1007/s100380050156
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    A new single-nucleotide polymorphism in the seventh component of complement (C7) gene (1999)
    Springer
    Journal of human genetics 44 (1999), S. 272-273 
    Details
    ISSN: 1435-232X
    Keywords: Key words Complement ; C7 ; Mutation ; Polymorphism ; Population genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A new single-nucleotide polymorphism has been found in the 3′ untranslated region of the complement component C7 gene. It is present with similar frequencies in the Japanese and Germans. This polymorphism would be a useful marker in the genetic study of C6 and C7 deficiencies.
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    Four novel mutations of the Fanconi anemia group A gene (FAA) in Japanese patients (1999)
    Springer
    Journal of human genetics 44 (1999), S. 48-51 
    Details
    ISSN: 1435-232X
    Keywords: Key words Fanconi anemia ; FAA gene ; Mutation ; Polymorphism ; SSCP ; Direct sequencing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Fanconi anemia (FA) is an autosomal recessive disorder characterized by pancytopenia, predisposition to cancers, and a diverse variety of congenital malformations. At least eight complementation groups, A through H, have been described. Recently, the FA-A gene (FAA) has been isolated, and a large number of distinct mutations reported in ethnically diverse FA-A patients. Here, we report on the mutation analysis of five FA patients by single-strand conformation polymorphism. Out of five patients, at least three were found to have mutations in the FAA gene. The first patient was a compound heterozygote with a 1-bp deletion and a single-base substitution. The second patient had a heterozygous 2-bp deletion, which introduces a premature termination codon, and the third patient had a heterozygous splice donor site mutation in intron 27.
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    URL: http://dx.doi.org/10.1007/s100380050106
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    Radiation-induced mutations from accessory buds of sweet cherry, Prunus avium L. cv ‘Bing’ (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 912-916 
    Details
    ISSN: 1432-2242
    Keywords: Key words Accessory buds ; Mutation ; Growth-reduced ; Mutant sector ; Gamma radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Dormant scions of ‘Bing’ were exposed to 1–2.5 krad of gamma radiation in order to induce useful mutations. The main buds were excised and the scions grafted to allow the growth of accessory buds into primary (V1) shoots. The frequency and types of mutations on secondary (V2) populations are described. In a population of 3324 V2 shoots, the overall mutation frequency was 6.4%: 4.2% partial, 1.6% total and 0.3% growth-reduced mutants were identified. The experiment was repeated using 3 krad- and 4 krad-fractionated doses in water. Differences in mutation frequency at 3 krad and 4 krad were not significant. Of 2562 surviving V2 shoots derived from the irradiation of accessory buds of both standard and V1 shoots, the overall mutation frequency was 3.3%: 1.7% were partial-leaf mutants, 1.0% were total-leaf mutants, and 0.54% were growth-reduced mutants. For maximum mutation rate with adequate survival we suggest acute irradiation of accessory buds in air at dosages approximating LD50 (2.75–3 krad). A larger mutant sector was present in V1 shoots derived from accessory buds than those from main buds as revealed by the higher number of total mutant repeats in the families.
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    panicle phytomer 1 mutations affect the panicle architecture of rice (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 1050-1056 
    Details
    ISSN: 1432-2242
    Keywords: Key words Rice ; panicle phytomer 1 ; Mutation ; Panicle ; Phytomer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We have characterized three panicle phytomer 1 (pap1) mutations from the phytomer viewpoint. In pap1 mutants, rachis phytomers were strongly affected involving a severe reduction of rachis internode length and an increase in the number of rachis internodes (number of phytomers), resulting in a large number of primary branches. In addition, bracts were frequently over-developed. By contrast, pap1 differently affected primary branch phytomers resulting in a reduction in both the number and length of internodes. Spikelets were also modified. Rudimentary and empty glumes were frequently elongated. Floral organs were mostly normal. However, a double mutation between pap1 and fon1 markedly increased the number of floral organs compared with the single fon1 mutation, suggesting that PAP1 has a distinct role in the differentiation of floral organs. The functions of PAP1 on panicle architecture are: (1) the negative regulation of the number of phytomers on the rachis but a positive regulation of the number on primary branches, (2) an elongation of internodes, and (3) the negative regulation of bract development.
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    Alteration of β-tubulin in Nicotiana plumbaginifolia confers resistance to amiprophos-methyl (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 464-472 
    Details
    ISSN: 1432-2242
    Keywords: Key words Amiprophos-methyl ; Resistance ; Mutation ; β-Tubulin ; Microtubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A Nicotiana plumbaginifolia plant (apm5r) resistant to amiprophos-methyl (APM), a phosphoro-amide herbicide, was isolated from protoplasts prepared from leaves of haploid plants. Genetic analysis revealed that the resistance is coded for by a dominant nuclear mutation and is associated with the increased stability of cortical microtubules. Two-dimensional polyacrylamide-gel electrophoresis, combined with immunoblotting using anti-tubulin monoclonal antibodies, showed that part of the β-tubulin in the resistant plant possessed lower isoelectric points than the β-tubulin of susceptible wild-type plants. These results provide evidence that the resistance to APM is associated with a mutation in a β-tubulin gene. The APM-resistant line showed cross-resistance to trifluralin, a dinitroaniline herbicide, suggesting a common mechanism of resistance between these two classes of herbicides.
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    URL: http://dx.doi.org/10.1007/s001220050918
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    Alteration of the largest subunit of RNA polymerase II and its effect on chromosome stability in Schizosaccharomyces pombe (1998)
    Springer
    Molecular genetics and genomics 258 (1998), S. 279-287 
    Details
    ISSN: 1617-4623
    Keywords: Key words RNA polymerase II largest subunit ; Mutation ; Temperature sensitivity ; Chromosome stability ; Cell cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mutation in the RNA polymerase II largest subunit (RpII LS) that is related to abnormal induction of sister chromatid exchange has previously been described the CHO-K1 cell mutant tsTM4. To elucidate the molecular basis of this effect we introduced the mutation into the homologous site in the Schizosaccharomyces pombe rpb1 gene, which encodes RpII LS. Since the tsTM4 mutant exhibited a decrease in the rate of DNA synthesis in cells arrested in S phase at the nonpermissive temperature, we focussed on the study of growth, the cell cycle, and chromosome stability at various temperatures. First, we examined the effects of the mutation on haploid yeast cells. The mutant showed slower growth than the wild type, but cell growth was not arrested at the nonpermissive temperature. When growing cells were shifted to the nonpermissive temperature, an accumulation of cells in G1 and/or G0 was observed. Tetrad analysis suggested that these phenotypes were associated with the mutation. In diploid cells, chromosome instability was detected by loss of intragenic complementation between two alleles of the ade6 gene. An abnormal fraction of cells containing an intermediate DNA content was also observed by FACS analysis. The accumulation of this fraction may reflect the fact that a large number of cells are in S phase or have an abnormal DNA content as a result of chromosome instability. These observations demonstrate that the S. pomberpb1 mutant exhibits a phenotype very similar to that of the CHO-K1 cell mutant tsTM4.
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    Alien plant species composition and associations with anthropogenic disturbance in North American forests (1998)
    Springer
    Plant ecology 139 (1998), S. 49-62 
    Details
    ISSN: 1573-5052
    Keywords: Alien species ; Anthropogenic disturbance ; Biological invasions ; Forests ; Ground vegetation ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A probability-based sampling scheme was used to survey plant species composition in forests of 16 states in seven geopolitical regions of the United States (California, Colorado, Minnesota, and parts of the Pacific Northwest, Southeast, Mid-Atlantic, and Northeast) in 1994. The proportion of alien species relative to the total species number and to canopy cover in the ground stratum (0–0.6 m height) was evaluated in 279 plots. Visually evident anthropogenic disturbances (e.g., artificial regeneration, logging, prescribed burning, and grazing by livestock), if any, were recorded on each plot. In each of the seven regions we quantified (1) the percentage of the number of species and total cover comprised of alien species, (2) the difference in these percentages for disturbed and undisturbed plots, and (3) the origin or native range for the alien species. The percentage of alien species ranged from approximately 4.5% (Colorado) to approximately 13.2% (California). The percentage of alien species cover ranged from approximately 1.5% in Colorado to 25% in California. In five regions, species introduced from temperate Eurasia comprised the largest proportion of alien species and cover. In the Southeast, species introduced from far eastern and subtropical Asia dominated the alien flora. In the Mid-Atlantic, the majority of alien species was Eurasian and the majority of alien species cover consisted of far eastern and subtropical Asian species. The proportion of plots in which at least one alien species was recorded was significantly higher in disturbed than undisturbed plots in the Southeast and marginally significantly higher ($p=0.053$) in the Northeast. These results are consistent with other published studies that indicate that anthropogenic disturbance affects the structure and composition of both the ground stratum and upper canopy of forest habitats. In other regions, however, no significant differences were found.
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    Significance of each of three missense mutations, G484A, G667A, and G808A, present in an inactive allele of the human Lewis gene (FUT3) for α(1,3/1,4)fucosyltransferase inactivation (1998)
    Springer
    Glycoconjugate journal 15 (1998), S. 961-967 
    Details
    ISSN: 1573-4986
    Keywords: α(1,3/1,4)fucosyltransferase ; Fuc-TIII ; Lewis-negative allele ; Chimera ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Recently, we found three novel missense mutations, G484A (Asp162Asn), G667A (Gly223Arg), and G808A (Val270Met), present in a Lewis-negative allele (le484,667,808) from an African (Xhosa) population. To define the relative contribution of each of the three mutations in the le484,667,808 allele for inactivation of the FUT3-encoded enzyme, we made chimeric FUT3 containing each of the three mutations. A transient expression study indicated that COS7 cells transfected with the FUT3 construct containing the G484A mutation expressed the Lewis antigen and had about 20% enzyme activity as compared with COS7 cells transfected with the wild type FUT3 allele, whereas COS7 cells transfected with the FUT3 construct containing either the G667A mutation or the G808A mutation did not express the Lewis antigen and showed no detectable α(1,3/1,4)fucosyltransferase activity. These results suggest that the G667A and/or the G808A missense mutations of FUT3 alleles are responsible for the inactivation of the FUT3-encoded enzyme.
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    URL: http://dx.doi.org/10.1023/A:1006981724233
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    Analysis of bilirubin uridine 5′-diphosphate (UDP)-glucuronosyltransferase gene mutations in seven patients with Crigler-Najjar syndrome type II (1998)
    Springer
    Journal of human genetics 43 (1998), S. 111-114 
    Details
    ISSN: 1435-232X
    Keywords: Key words Crigler-Najjar syndrome type II ; Mutation ; Inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Crigler-Najjar syndrome (CN) type II is caused by a reduction in hepatic bilirubin uridine 5′-diphosphate (UDP)-glucuronosyltransferase activity. Recently, there has been progress in mutation analysis of patients with CN type II. Here, we analyzed both the coding and the promoter regions of the gene in seven Japanese patients with CN type II from five unrelated families. The mutations found in this study were classified into three types. The first type was composed of double homozygous missense mutations (Gly71Arg and Tyr486Asp) in exons 1 and 5. These mutations, which were detected in five patients from three unrelated families, were the commonest. The second type, which was detected in one patient, consisted of a single homozygous missense mutation (Arg209Trp) in exon 1. The third type, which was detected in one patient and was a new type of mutation combination, was composed of a homozygous insertion mutation of the TATAA element and a heterozygous missense mutation (Pro229Gln) in exon 1. Although the first and the second type of mutations are recessive, the third type appears to be dominant with incomplete penetrance, since the allele frequency of the insertion mutation of the TATAA element is very high (40%).
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    Novel MEN1 gene mutations in familial multiple endocrine neoplasia type 1 (1998)
    Springer
    Journal of human genetics 43 (1998), S. 199-201 
    Details
    ISSN: 1435-232X
    Keywords: Key words Multiple endocrine neoplasia type 1 ; Menin ; Endocrine tumor ; Mutation ; Founder effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The recent isolation of the gene responsible for multiple endocrine neoplasia type 1 (MEN 1) has enabled direct genetic diagnosis for people with endocrine tumors and family members of affected patients. Although MEN 1 is rarely recognized in the Japanese population compared to its prevalence in Caucasians, we have previously reported a high prevalence of this disease in a limited area (Nagano Prefecture; population, 2.15 million). In this communication, we report mutations of the MEN1 gene in kindreds living in Nagano Prefecture. The absence of a common mutation among these kindreds indicates that the high prevalence of MEN 1 in this area is not due to a regional accumulation of patients descended from a common ancestor. This result implies that the prevalence of MEN 1 in other areas of Japan could also be higher than had been thought.
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    What is the Place of Christian Wolff in the History of the Social Sciences? (1997)
    Springer
    European journal of law and economics 4 (1997), S. 147-232 
    Details
    ISSN: 1572-9990
    Keywords: Methodology ; history of social science ; economists ; political economy ; history ; historical school ; Germany ; England ; United States ; historicism ; economics ; philosophy ; Wolff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Law , Economics
    Notes: Abstract This paper explores the place of Christian Wolff in the history of social science in English. The "Introduction" places Wolff in the context of the pre-history of modern social science. Samples are given of the great range of subjects on which he wrote. The importance of the German context is stressed. The second part is devoted to a sample of what the literature contains by and about Wolff. It emphasizes philosophy and science. Part three is a survey of works in the history of the social sciences that mention Wolff. He has a substantial place in political science and psychology, a much smaller place in economics and history, virtually none in anthropology, geography, and sociology. In the applied social sciences, he is found in the history of education. Possible reasons are given. Part four is devoted to the relationships of philosophy and philosophers in the pre-history of the social sciences. They were important in several different ways because they both shaped and reflected how many people thought about science and social problems. The “Summary and Conclusion” describes the present status. His contributions are summarized. He was a pivotal figure in the making of the German conception of social science. This is a preliminary study emphasizing the issues and problems that a more detailed examination would require. Several conventional judgments are challenged and possibilities for further research suggested.
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    Role of mitochondria in human aging (1997)
    Springer
    Journal of biomedical science 4 (1997), S. 319-326 
    Details
    ISSN: 1423-0127
    Keywords: Oxidative damage ; Reactive oxygen species ; Mitochondria ; Mitochondrial DNA ; Mutation ; Aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mitochondria are the major intracellular source and target sites of reactive oxygen species (ROS) that are continually generated as by-products of aerobic metabolism in animal and human cells. It has been demonstrated that mitochondrial respiratory function declines with age in various human tissues and that a defective respiratory chain results in enhanced production of ROS and free radicals in mitochondria. On the other hand, accumulating evidence now indicates that lipid peroxidation, protein modification and mitochondrial DNA (mtDNA) muutation are concurrently increased during aging. On the basis of these observations and the fact that the rate of cellular production of superoxide anions and hydrogen peroxide increases with age, it has recently been postulated that oxidative stress is a major contributory factor in the aging process. A causal relationship between oxidative modification and mutation of mtDNA, mitochondrial dysfunction and aging has emerged, although some details have remained unsolved. In this article, the role of mitochondria in the human aging process is reviewed on the basis of recent findings gathered from our and other laboratories.
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    A tobacco mutant with a reduced cell number in embryo sacs (1997)
    Springer
    Sexual plant reproduction 10 (1997), S. 300-304 
    Details
    ISSN: 1432-2145
    Keywords: Key words Embryo sac ; Structural changes ; Mutation ; Nicotiana tabacum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The semisterile tobacco plant BG-141.4 was produced using both irradiation with X-rays and anther culture. The embryological investigation of the progeny of this plant following selfing (R1) revealed disturbances in the structure of the mature embryo sacs (ESs). The major abnormality was a decrease in cell number in the ESs. Other abnormalities included disturbances in the distribution of nuclei and in cell differentiation. The overall frequency of abnormal ESs in individual plants investigated varied from 8% to 83%, while the frequency of ESs with a reduced number of cells varied from 5% to 72%. Since the examination of three subsequent generations - R2, R3 and R4 - showed similar results, it is concluded that a mutation has been induced. Its main phenotypic manifestation is most likely related to its lacking one or two nuclear division(s) during the coenocytic stage of megagametogenesis. The penetrance of the mutation varies widely.
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    Phenotypic characterization of a tobacco mutant impaired in auxin polar transport (1997)
    Springer
    Plant cell reports 17 (1997), S. 32-38 
    Details
    ISSN: 1432-203X
    Keywords: Key words Tobacco ; Nicotiana tobacum ; Mutation ; Auxin transport ; Indole acetic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mutation in tobacco (Nicotiana tabacum L. cv `Xanthi') called lat (low auxin transport) that changes many morphogenic features throughout the life of the plant has been isolated. Abnormalities were observed in seed development, embryogenesis, cotyledon formation, leaf initiation and development, leaf veination pattern, and flower development. Selfed R2 lat mutant plants set between 60% and 90% fewer seeds than wild-type tobacco, and about 10% of these seeds did not germinate. Non-germinating seeds contained either abnormal embryos or abnormal endosperm tissues. There was no uniformity in the stage at which embryonic development ceased in the aberrant seeds. Seedlings often revealed abnormal and highly varied phenotypes after germination. In some of these cases, cotyledons were heart-shaped, fused, cup-shaped, or cylindrical. Leaf morphology ranged from normal to cup-shaped, and some leaves occasionally produced shoots from the leaf midvein. Flowers ranged from normal to compound with occasional fused floral parts or split petals. Stamens were sometimes petal-like. This unusual assortment of phenotypic changes suggested that the mutation might affect a basic component of plant metabolism. We found that polar transport of indole-3-acetic acid (IAA) was reduced to about 9–19% of the wild-type level in the inflorescence axis of selfed R2 lat mutants. In addition, supplementation of 1-naphthaleneacetic acid (NAA) to sterile media suppressed some of the abnormalities of the lat mutation so long as the plants grew there. Similarities in the phenotype of embryos, cotyledon and leaf shapes, translocation of labeled IAA, and response to applied NAA indicate that the lat locus of tobacco may be analogous to the pin locus of Arabidopsis, or produce a protein that functions in the same auxin-transport pathway.
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    Terrestrial Carbon Dynamics: Case Studies in the Former Soviet Union, the Conterminous United States, Mexico and Brazil (1997)
    Springer
    Mitigation and adaptation strategies for global change 1 (1997), S. 363-383 
    Details
    ISSN: 1573-1596
    Keywords: carbon flux ; land use ; former Soviet Union ; United States ; Mexico ; Brazil ; forests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Abstract This research assessed land-use impacts on C flux at a national level in four countries: former Soviet Union, United States, Mexico and Brazil, including biotic processes in terrestrial ecosystems (closed forests, woodlands, and croplands), harvest of trees for wood and paper products, and direct C emission from fires. The terrestrial ecosystems of the four countries contain approximately 40% of the world's terrestrial biosphere C pool, with the FSU alone having 27% of the global total. Average phytomass C densities decreased from south to north while average soil C densities in all three vegetation types generally increased from south to north. The C flux from land cover conversion was divided into a biotic component and a land-use component. We estimate that the total net biotic flux (Tg/yr) was positive (= uptake) in the FSU (631) and the U.S. (332), but negative in Mexico (−37) and Brazil (−16). In contrast, total flux from land use was negative (= emissions) in all four countries (TgC/yr): FSU −343; U.S. −243; Mexico −35; and Brazil −235. The total net effect of the biotic and land-use factors was a C sink in the FSU and the U.S. and a C source in both Brazil and Mexico.
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    URL: http://dx.doi.org/10.1023/B:MITI.0000027388.65532.60
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    Forward induction, evolutionary processes and behavior evolution (1997)
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    Journal of evolutionary economics 7 (1997), S. 415-433 
    Details
    ISSN: 1432-1386
    Keywords: Key words: Forward induction ; Deviation ; Discrete evolutionary processes ; Mutation ; Limit distribution ; JEL-classification: C70; C72
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract. The paper deals with the driving forces behind behavior selection in both forward induction refinements and discrete evolutionary processes with mutations. Its main purpose is to analyse an important difference due to the support of the mutations. It shows that similar driving forces can allow to outweigh this difference. To this aim it constructs the limit Markov graph, a tool used to compute the probabilities in the limit distribution.
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    Bifurcations in haploid and diploid sequence space models (1997)
    Springer
    Journal of mathematical biology 35 (1997), S. 321-343 
    Details
    ISSN: 1432-1416
    Keywords: Key words: Sequence space ; Selection ; Mutation ; Error threshold ; Hopf bifurcations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract.  Deterministic models of mutation and selection in the space of (binary) nucleotide-type sequences have been investigated for haploid populations during the past 25 years, and, recently, for diploid populations as well. These models, in particular their ‘error thresholds’, have mainly been analyzed by numerical methods and perturbation techniques. We consider them here by means of bifurcation theory, which improves our understanding of both equilibrium and dynamical properties. In a caricature obtained from the original model by neglecting back mutation to the favourable allele, the familiar error threshold of the haploid two-class model turns out to be a simple transcritical bifurcation, whereas its diploid counterpart exhibits an additional saddle node. This corresponds to a second error threshold. Three-class models with neutral spaces of unequal size introduce further features. Such are a global bifurcation in haploid populations, and simple examples of Hopf bifurcations (as predicted by Akin’s theorem) in the diploid case.
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    The impact of elevated UV-B (280–320 nm) radiation levels on the reproduction biology of a highland and a lowland population of Silene vulgaris (1997)
    Springer
    Plant ecology 128 (1997), S. 173-179 
    Details
    ISSN: 1573-5052
    Keywords: Fertilisation ; Flowers ; Germination ; Mutation ; Seed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A highland (altitude 1600 m) and a lowland (altitude –2 m) population of the perennial herb Silene vulgaris were tested on the effects of elevated levels of UV-B radiation on their reproductivity. Highland populations receive higher natural UV-B doses than lowland populations. Therefore adaptation to high UV-B levels of the highland population is to be expected. The lowland population showed a decrease in the number of seed producing flowers and the number of seeds produced per plant under elevated UV-B levels. The highland population increased the number of seeds per plant under elevated UV-B levels. In both populations individual seed mass as well as seed germination percentages were unaffected by the UV-B flux received by the parental plant. Possible effects of UV-B induced alterations in reproductivity on the geographical distribution of the different populations are discussed.
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    URL: http://dx.doi.org/10.1023/A:1009710907336
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    Terrestrial carbon dynamics: Case studies in the former Soviet Union, the conterminous United States, Mexico and Brazil (1997)
    Springer
    Mitigation and adaptation strategies for global change 1 (1997), S. 363-383 
    Details
    ISSN: 1573-1596
    Keywords: carbon flux ; land use ; former Soviet Union ; United States ; Mexico ; Brazil ; forests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Abstract This research assessed land-use impacts on C flux at a national level in four countries: former Soviet Union, United States, Mexico and Brazil, including biotic processes in terrestrial ecosystems (closed forests, woodlands, and croplands), harvest of trees for wood and paper products, and direct C emission from fires. The terrestrial ecosystems of the four countries contain approximately 40% of the world's terrestrial biosphere C pool, with the FSU alone having 27% of the global total. Average phytomass C densities decreased from south to north while average soil C densities in all three vegetation types generally increased from south to north. The C flux from land cover conversion was divided into a biotic component and a land-use component. We estimate that the total net biotic flux (Tg/yr) was positive (=uptake) in the FSU (631) and the U.S. (332), but negative in Mexico (-37) and Brazil (-16). In contrast, total flux from land use was negative (=emissions) in all four countries (TgC/yr): FSU -342; U.S. -243; Mexico -35; and Brazil -235. The total net effect of the biotic and land-use factors was a C sink in the FSU and the U.S. and a C source in both Brazil and Mexico.
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    Acidification Trends in Surface Waters in the International Program on Acidification of Rivers and Lakes (1997)
    Springer
    Water, air & soil pollution 93 (1997), S. 27-57 
    Details
    ISSN: 1573-2932
    Keywords: Acidification ; trends ; sulfate ; nitrate ; United States ; Europe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We applied trend analyses to data from the International Cooperative Programme forAcidification of Rivers and Lakes in an attempt to discover regional patterns of long-term changesin surface water chemistry both in Europe and North America, and to relate these changes totrends in deposition. Decreases in surface water SO 3 - concentrations predominated at European sites in theFederal Republic of Germany, The Netherlands, and in Norway, and at the North American sitesin Ontario, Canada, the Adirondacks and Catskill Mountains of New York, U.S.A. Otherpredominating trends in the European sites were decreasing Ca2+ concentrations at many of thesites in The Netherlands, Norway, and Sweden. Increases in NO 3 - were observed at several sites in southern Norway, and in theAdirondack and Catskill regions of eastern New York. This, combined with an increasedoccurrence of declining base cation concentrations may well be responsible for the lack ofdocumented surface water recovery from acidification. Despite region-wide trends in severalvariables of importance in acidification, no correlations between surface water trends and changesin deposition were found using these data.
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    Acidification trends in surface waters in the international program on acidification of rivers and lakes (1997)
    Springer
    Water, air & soil pollution 93 (1997), S. 27-57 
    Details
    ISSN: 1573-2932
    Keywords: Acidification ; trends ; sulfate ; nitrate ; United States ; Europe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We applied trend analyses to data from the International Cooperative Programme for Acidification of Rivers and Lakes in an attempt to discover regional patterns of long-term changes in surface water chemistry both in Europe and North America, and to relate these changes to trends in deposition. Decreases in surface water SO4 2− concentrations predominated at European sites in the Federal Republic of Germany, The Netherlands, and in Norway, and at the North American sites in Ontario, Canada, the Adirondacks and Catskill Mountains of New York, U.S.A. Other predominating trends in the European sites were decreasing Ca2+ concentrations at many of the sites in The Netherlands, Norway, and Sweden. Increases in NO3 − were observed at several sites in southern Norway, and in the Adirondack and Catskill regions of eastern New York. This, combined with an increased occurrence of declining base cation concentrations may well be responsible for the lack of documented surface water recovery from acidification. Despite region-wide trends in several variables of importance in acidification, no correlations between surface water trends and changes in deposition were found using these data.
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    Gln54Leu of the conserved polar residue inthe interfacial coiled coil position (d) results in significant stabilization of the original structure of the COMP pentamerization domain (1997)
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 297-304 
    Details
    ISSN: 1573-3904
    Keywords: Cartilage oligomeric matrix protein ; Coiled coils ; Mutation ; Pentamer ; Thrombospondin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The assembly domain of cartilage oligomeric matrixprotein (COMP) forms an α-helical coiled coilhomopentamer with a conserved polar glutamine in theinterior (d) position. We substituted Gln54 forapolar Leu in the recombinant fragment of the rat COMPdomain. Biochemical studies and circular dichroism(CD) spectroscopy showed that the mutant, similarly tothe wild-type (w.t.) peptide, forms spontaneously anα-helical pentamer. Thermal transitions of thew.t. and mutant pentamers were analyzed by CDspectroscopy and differential scanning calorimetry.The Gln54Leu mutation increased the thermal stabilityof the pentamer with reduced disulfide bonds from73 °C to 104 °C. The denaturation of thedisulfide bonded w.t. pentamer was observed at108 °C while the mutant pentamer cannot bedenatured up to 120 °C (the apparatus limit).Thus, by Gln54Leu mutation we found a way tosignificantly stabilize the coiled coil pentamer,making this peptide even more attractive as an oligomerization tool for various biotechnological applications.
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    Mutation Gln54Leu of the conserved polar residue in the interfacial coiled coil position (d) results in significant stabilization of the original structure of the COMP pentamerization domain (1997)
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 297-304 
    Details
    ISSN: 1573-3904
    Keywords: Cartilage oligomeric matrix protein ; Coiled coils ; Mutation ; Pentamer ; Thrombospondin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The assembly domain of cartilage oligomeric matrix protein (COMP) forms an α-helical coiled coil homopentamer with a conserved polar glutamine in the interior (d) position. We substituted Gln54 for apolar Leu in the recombinant fragment of the rat COMP domain. Biochemical studies and circular dichroism (CD) spectroscopy showed that the mutant, similarly to the wild-type (w.t.) peptide, forms spontaneously an α-helical pentamer. Thermal transitions of the w.t. and mutant pentamers were analyzed by CD spectroscopy and differential scanning calorimetry. The Gln54Leu mutation increased the thermal stability of the pentamer with reduced disulfide bonds from 73°C to 104°C. The denaturation of the disulfide bonded w.t. pentamer was observed at 108°C while the mutant pentamer cannot be denatured up to 120°C (the apparatus limit). Thus, by Gln54Leu mutation we found a way to significantly stabilize the coiled coil pentamer, making this peptide even more attractive as an oligomerization tool for various biotechnological applications.
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    Integrating nineteenth-century Canadian and American census data sets (1996)
    Springer
    Computers and the humanities 30 (1996), S. 381-392 
    Details
    ISSN: 1572-8412
    Keywords: comparative demographic history ; census ; data set integration ; ICAPUMS ; IPUMS ; coding schemes ; Canada ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Media Resources and Communication Sciences, Journalism
    Notes: Abstract The comparative use of census data is a useful way to study social characteristics across national boundaries. However, truly comparative demographic history is not possible without fully integrating separate census data, uniting multiple data files with a common set of comparably coded variables. This paper describes the integration of the 1871 Canadian census public use sample with similar samples of the 1850 and 1880 American censuses to form the Integrated Canadian-American Public Use Microdata Series (ICAPUMS). These data sets lent themselves well to integration because of their strong similarities in sampling design, data collection and data organization. Consistency in the availability and treatment of variables also eased integration of the samples, although the harmonization of occupation variables presented significant challenges. The ICAPUMS features a general household relationship variable which allows us to examine household structure across the two countries and three years. The paper concludes by proposing some general principles of census data set integration. This integrated data set is now available to researchers on the website of the University of Minnesota Historical Census Projects (www.hist.umn.edu/~ipums).
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    Transforming growth factor-β receptors: Role in physiology and disease (1996)
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    Journal of biomedical science 3 (1996), S. 143-158 
    Details
    ISSN: 1423-0127
    Keywords: Transforming growth factor-β ; Tumorigenesis ; Mutation ; Tumor suppressor gene ; Receptor ; Microsatellite instability ; Transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Transforming growth factor-β (TGF-β) plays a pivotal role in numerous vital cellular activities, most significantly the regulation of cellular proliferation and differentiation and synthesis of extracellular matrix components. Its ubiquitous presence in different tissues and strict conservation of nucleotide sequence down through the most primitive vertebrate organisms underscore the essential nature of this family of molecules. The effects of TGF-β are mediated by a family of dedicated receptors, the TGF-β types I, II, and III receptors. It is now known that a wide variety of human pathology can be caused by aberrant expression and function of these receptors or their cognate ligands. The coding sequence of the human type II receptor appears to render it uniquely susceptible to DNA replication errors in the course of normal cell division. There are now substantial data suggesting that TGF-β type II receptor should be considered a tumor suppressor gene. High levels of mutation in the TGF-β type II receptor gene have been observed in a wide variety of primarily epithelial malignancies, including colon, gastric, and hepatic cancer. It appears likely that mutation of the TGF-β type II receptor gene represents a very critical step in the pathway of carcinogenesis.
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    The influence of a surface charge on the electronic and steric structure of a high potential iron-sulfur protein (1996)
    Springer
    JBIC 1 (1996), S. 257-263 
    Details
    ISSN: 1432-1327
    Keywords: Key words High-potential ; Iron-sulfur protein ; Redox ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The recombinant high-potential iron-sulfur protein (HiPIP) iso-I from Ectothiorhodospira halophila has been mutated at position 68. The αC of Val 68 is within a 0.6-nm sphere from the closest iron ion of the cluster. The valine residue has been replaced by a negatively charged glutamate residue (V68E) and by a positively charged lysine residue (V68K). With respect to the recombinant wild-type protein the reduction potentials of the V68E and V68K variants are –21±2 and +29±2 mV respectively (200 mM NaCl, pH 7, 25  °C). The solution structure of the V68E mutant was solved up to a pairwise RMSD of 66 pm for backbone atoms and 138 pm for all heavy atoms. The structure of the variant is very similar to that of recombinant wild type, indicating that the observed changes in reduction potentials are largely due to the effect of the introduced charges. It is proposed that the valence distribution within the oxidized iron-sulfur cluster is affected only slightly by the change in charge at position 68, but consistently with a simple electrostatic model.
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    Transcription of mutS and mutL-homologous genes in Saccharomyces cerevisiae during the cell cycle (1996)
    Springer
    Molecular genetics and genomics 252 (1996), S. 275-283 
    Details
    ISSN: 1617-4623
    Keywords: Key words DNA mismatch repair ; MluI cell cycle box ; Mutation ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Transcription of the Saccharomyces cerevisiae DNA mismatch repair genes PMS1, MSH2, and MSH6, a recently discovered homolog of the Escherichia coli mutS gene, was shown to be cell cycle regulated. In contrast, transcription of the MSH1, MSH3 and MLH1 genes was not regulated during the cell cycle. The MSH1 gene, which is thought to be involved in DNA mismatch repair in mitochondria, was also not induced under aerobic growth conditions. Regulation of the PMS1 gene was dependent on intact MluI cell cycle boxes, as demonstrated by analysis of a promoter mutant. Both reduced and increased expression of PMS1 resulted in a mitotic mutator phenotype. Analysis of mRNA levels was performed with a newly developed reverse transcription-PCR (polymerase chain reaction) approach using fluorescently labeled primers and an automated DNA sequencer for detection of PCR products.
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    Transcription ofmutS andmutL-homologous genes inSaccharomyces cerevisiae during the cell cycle (1996)
    Springer
    Molecular genetics and genomics 252 (1996), S. 275-283 
    Details
    ISSN: 1617-4623
    Keywords: DNA mismatch repair ; MluI cell cycle box ; Mutation ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcription of theSaccharomyces cerevisiae DNA mismatch repair genesPMS1, MSH2, andMSH6, a recently discovered homolog of theEscherichia coli mutS gene, was shown to be cell cycle regulated. In contrast, transcription of theMSH1, MSH3 andMLH1 genes was not regulated during the cell cycle. TheMSH1 gene, which is thought to be involved in DNA mismatch repair in mitochondria, was also not induced under aerobic growth conditions. Regulation of thePMS1 gene was dependent on intactMluI cell cycle boxes, as demonstrated by analysis of a promoter mutant. Both reduced and increased expression ofPMS1 resulted in a mitotic mutator phenotype. Analysis of mRNA levels was performed with a newly developed reverse transcription-PCR (polymerase chain reaction) approach using fluorescently labeled primers and an automated DNA sequencer for detection of PCR products.
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    Antimerger policy in the United States: History and lessons (1996)
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    Empirica 23 (1996), S. 229-253 
    Details
    ISSN: 1573-6911
    Keywords: Antimerger policy ; United States ; Europe ; efficiency ; L41 ; G34 ; L21
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract This paper reviews the history of US antimerger policy. This history is divided into three periods: a period in which there was almost no effective antimerger policy at all from 1890 up to 1959, a period of vigorous antimerger policy from 1950 up through 1973, and a period of lax enforcement from 1974 to the present. The paper accounts for these shifts in antimerger policy and discusses their effects. After reviewing the logic and consequences of US antimerger policy, a critique of its permises is offered, particularly as these premises apply to the recent era of lax enforcement. The paper closes with suggestions for an alternative approach to antimerger policy that is consistent with the empirical evidence on why mergers occur and their effects.
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    Comparison of symbiotic effectiveness of Rhizobium sp. with positive hydrogen-uptake activity compared with negative mutants in relation to nitrogen fixation in mungbean (Vigna radiata L.) (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 270-274 
    Details
    ISSN: 1432-0789
    Keywords: Mungbean ; Vigna radiata ; Nitrogen fixation ; Hydrogen uptake ; Mutation ; Nitrosoguanidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract H2 uptake activity was well distributed in Rhizobium sp. strains isolated from nodules of mung-bean (Vigna radiata L.). Two effective strains, RMP1 und RMP2, exhibiting significantly higher H2 uptake activity were subjected to mutagenesis with nitrosoguanidine. The respective mutation frequencies were 0.18 and 0.19%. Three Hup- mutants each of RMP1 und RMP2 were compared with the wild-type parent strains under pot culture experiments to evaluate the significance of the H2 uptake system in biological N2 fixation. Nodulation capabilities, plant growth characteristics, and the chlorophyll content of the leaves were significantly reduced in the plants treated with Hup- mutants. Nitrogenase activity in Hup- nodules was reduced by 8–41%. Similarly, N accumulation was also reduced singificantly.
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    Constraints on mutability in a multiallelic gene family (1995)
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    Journal of molecular evolution 41 (1995), S. 732-740 
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    ISSN: 1432-1432
    Keywords: Mutation ; Nearest ; neighbor effects ; DNA structure ; Brassica incompatibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A highly variable family of related DNA sequences was examined in order to determine the effect of local sequence environment on substitution mutation; 29 sequences from the Brassica self-incompatibility gene family, which possess a high level of nonsynonymous mutations, were aligned and grouped according to their similarity and function. The level and distribution of substitution mutations were calculated. A nonrandom distribution of sequence variation was observed along the sequences. The effect of neighbor biases and structural and thermodynamic measures were then compared in the absence of strong codon conservation. Biases were observed in the rates of substitution of the same base pair in different local sequence environments. The effect of the 5′ neighbor was such that nucleotide A or C was associated with more mutations than G or T. There were significant interactions of certain dinucleotides with the frequency of mutation. Sequence-dependent measures of helical stability, intrinsic curvature, components of curvature, and stacking interactions were calculated for each sequence. Decreased helical stability was found to be associated with increased mutation. The compound measure of curvature, calculated according to the “wedge” model, showed little association with mutation. However, the components of increased wedge angle and decreased twist both showed an association with increased mutation. A small effect of A-type DNA stacking was found to be associated with mutated bases.
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    The U.S. allowance trading system for sulfur dioxide: An update on market experience (1995)
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    Environmental and resource economics 5 (1995), S. 115-129 
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    ISSN: 1573-1502
    Keywords: Emission trading ; United States ; sulfur dioxide ; air pollution ; costs ; cost-effectiveness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: Abstract In 1990, the U.S. Congress passed legislation that amended the Clean Air Act to create a new program to mitigate the effects of acid deposition in the U.S. through emission reductions of sulfur dioxide (SO2) and nitrogen oxides (NOx) at electric utility plants across the country. The SO2 reductions, totalling a 40% reduction nationally from 1980 levels or a 10 million ton reduction annually, are achieved largely through an emission trading system, the largest program of its kind designed to date. This trading system has the potential to save up to half of the compliance costs associated with more traditional source-by-source emission limit programs. This paper briefly discusses background on the acid rain issue in the United States, and the principal features of the program, including: a permanent cap on utility emissions of SO2 beginning in 2010, decision to grant up-front allocation of emission credits to reduce individual approvals of trades, the use of continuous emission monitors and automatic penalties to ensure compliance, and integration of the Acid Rain program requirements with other Clean Air Act programs. The paper also discusses the development of the allowance trading market to date, including the types of compliance options chosen and quantity and type of emissions trading being conducted.
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    Production and genetic characterization of near-isogenic lines in the bread-wheat cultivar Alpe (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 650-658 
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    ISSN: 1432-2242
    Keywords: Near-isogenic lines ; Triticum aestivum Glutenin ; Gliadin ; Mutation ; Biotypes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two biotypes of the bread-wheat cultivar Alpe were shown to possess contrasting alleles at each of the glutenin (Glu-B1, Glu-D1, Glu-B3 and Glu-D3) and gliadin (Gli-B1 and Gli-D1) loci on chromosomes 1B and 1D. Fourteen near-isogenic lines (NILs) were produced by crossing these biotypes and used to determine the genetic control of both low-molecular-weight (LMW) glutenin subunits and gliadins by means of one-dimensional or two-dimensional electrophoresis. Genes coding for the B, C and D groups of EMW subunits were found to be inherited in clusters tightly linked with those controlling gliadins. Southern-blot analysis of total genomic DNAs hybridized to a γ-gliadin-specific cDNA clone revealed that seven NILs lack both the Gli-D1 and Glu-D3 loci on chromosome 1D. Segregation data indicated that these “null” alleles are normally inherited. Comparison of the “null” NILs with those possessing allele b at the Glu-D3 locus showed one B subunit, seven C subunits and two D subunits, as fractionated by two-dimensional A-PAGExSDS-PAGE, to be encoded by this allele. Alleles b and k at Glu-B3 were found to code for two C subunits plus eight and six B subunits respectively, whereas alleles b and k at Gli-B1 each controlled the synthesis of two β-gliadins, one γ and two ω-gliadins. The novel Gli-B5 locus coding for two ω-gliadins was shown to recombine with the Gli-B1 locus on chromosome 1B. The two-dimensional map of glutenin subunits showed α-gliadins encoded at the Gli-A2 locus on chromosome 6A. The use of Alpe NILs in the study of the individual and combined effects of glutenin subunits on dough properties is discussed.
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    Isolation and partial characterization of conditional cell division cycle mutants inChlamydomonas (1995)
    Springer
    Protoplasma 186 (1995), S. 149-162 
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    ISSN: 1615-6102
    Keywords: Algae ; Cytoskeleton ; Microtubules ; Microtubule organizing centres ; Mutation ; Temperature-sensitive
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have isolated a number of temperature conditional cell division cycle mutants of the unicellular plantChlamydomonas reinhardtii that are defective in single nuclear genes. Cells grow and divide normally at the permissive temperature (21 °C), but arrest in division at the restrictive temperature (33 °C). We have characterized these mutants using DNA probes and immunofluorescence techniques to localize cytoskeletal and microtubule organizing centre proteins. We describe here 3 broad classes of cell cycle mutation which result in cell cycle arrest with: unreplicated DNA (G1 arrest), duplicated DNA (G2 arrest) and multiple nuclei due to defective cytokinesis (cytokinesis arrest). The continuation of nuclear division in mutants blocked in cytokinesis provides support of an earlier hypothesis that stage specific events in theChlamydomonas cell cycle are arranged in separate dependent sequences. The mutants isolated in the present study provide insights into the role of cytoskeletal proteins in the coordination of plant cell division and the means to investigate the molecular mechanisms whereby division by multiple fission is controlled in the unicellular plantChlamydomonas.
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    US Fish and Wildlife Service 1979 wetland classification: A review (1995)
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    Plant ecology 118 (1995), S. 139-152 
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    ISSN: 1573-5052
    Keywords: Classification ; Definition ; United States ; Wetland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In 1979 the US Fish and Wildlife Service published and adopted a classification of wetlands and deepwater habitats of the United States. The system was designed for use in a national inventory of wetlands. It was intended to be ecologically based, to furnish the mapping units needed for the inventory, and to provide national consistency in terminology and definition. We review the performance of the classification after 13 years of use. The definition of wetland is based on national lists of hydric soils and plants that occur in wetlands. Our experience suggests that wetland classifications must facilitate mapping and inventory because these data gathering functions are essential to management and preservation of the wetland resource, but the definitions and taxa must have ecological basis. The most serious problem faced in construction of the classification was lack of data for many of the diverse wetland types. Review of the performance of the classification suggests that, for the most part, it was successful in accomplishing its objectives, but that problem areas should be corrected and modification could strengthen its utility. The classification, at least in concept, could be applied outside the United States. Experience gained in use of the classification can furnish guidance as to pitfalls to be avoided in the wetland classification process.
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    The best of times, the worst of times (1995)
    Springer
    Pharmacy world & science 17 (1995), S. 149-151 
    Details
    ISSN: 1573-739X
    Keywords: Antibiotics ; Communicable diseases ; Drug resistance, microbial ; Mutation ; Transduction, genetic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The development of resistance to antimicrobial agents by many bacterial pathogens has compromised traditional therapeutic regimens, making treatment of infections more difficult and frequently more expensive. Three factors have contributed to the development and spread of resistance: mutations in common genes that extend their spectrum of resistance, transfer of resistance genes among diverse microorganisms and increases in selective pressures in and outside of the hospital environment that enhance the development of resistant organisms. Some new resistance mechanisms are difficult to detect in the laboratory. Thus, resistant microorganisms may go unnoticed until they are widely disseminated in a hospital. The challenge for pharmacists, microbiologists and physicians is not only to contain the spread of existing resistant organisms, but also to prevent the emergence of new resistant pathogens by encouraging the rational and prudent use of antimicrobial agents.
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    Synonymous substitutions are clustered in enterobacterial genes (1994)
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    Journal of molecular evolution 39 (1994), S. 448-451 
    Details
    ISSN: 1432-1432
    Keywords: Synonymous substitution ; Escherichia coli ; Salmonella typhimurium ; Mutation ; Recombination ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The spatial distribution of synonymous substitutions in enterobacterial genes is investigated. It is shown that synonymous substitutions are significantly clustered in such a way that a synonymous substitution in one codon elevates the rate of synonymous substitution in an adjacent codon by about 10%. The level of clustering does not appear to be related to the level of gene expression, and it is restricted to a range of two or three codons. There are at least three possible explanations: (1) sequence-directed mutagenesis, (2) recombination, and (3) selection.
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    Evidence for in vitro induced mutation which improves somatic embryogenesis in Asparagus officinalis L. (1994)
    Springer
    Plant cell reports 13 (1994), S. 372-376 
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    ISSN: 1432-203X
    Keywords: Asparagus officinalis L ; Habituation ; Mutation ; Somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Somatic embryogenesis from different genotypes of Asparagus officinalis L. could be obtained by in vitro culture of shoot apices. Apices were first cultured on an auxin-rich inducing medium and then transferred onto a hormone-free development medium. All genotypes tested in this way produced a few somatic embryos. In some experiments, during the development phase, a new kind of friable highly embryogenic tissue appeared in a random manner. These tissues could be continuously subcultured on a hormone-free medium and were named embryogenic lines. Five of these embryogenic lines regenerated plants from somatic embryos. These regenerated plants exhibited an increased embryogenic response compared to the parent plants; e.g. apex culture produced somatic embryos without any auxin treatments. For one of the embryogenic lines, a genetic analysis showed that the improved embryogenic response of regenerated plants was controlled by a mendelian dominant monogenic mutation.
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    Energy-dependent mitochondrial mutagenicity of antibacterial ofloxacin and its recombinogenic activity in yeast (1994)
    Springer
    Current genetics 26 (1994), S. 281-284 
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    ISSN: 1432-0983
    Keywords: Ofloxacin ; Mitochondria ; Mutation ; Recombination ; Topoisomerase ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ofloxacin, a specific inhibitor of bacterial topoisomerase II, is known to inhibit the growth of yeast cells and to induce rho − mutants in the yeast S. cerevisiae. The frequency of ofloxacin-induced petite mutants under non-growth conditions was found to be strongly diminished when the cells were depleted in intramitochondrial ATP. Under optimal conditions of mitochondrial mutagenesis the drug induced mitotic recombination and reverse mutation in diploid strains but failed to cure either killer plasmids or the 2 μm DNA of dividing cells. The sensitivity to ofloxacin of the strains deficient in the DNA strandbreak repair pathway (rad52) was significantly higher then that of the wild-type strains and of the mutants deficient in excision or mutagenic DNA repair. The results are compatible with the idea that the cytotoxic and genetic activity of ofloxacin in yeast probably results from the inhibited DNA ligation function of topoisomerase II creating DNA breaks that are reparable through the recombination repair pathway.
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    Isolation and characterization of an ω3-desaturation-defective mutant of an arachidonic acid-producing fungus, Mortierella alpina 1S-4 (1994)
    Springer
    Archives of microbiology 161 (1994), S. 316-319 
    Details
    ISSN: 1432-072X
    Keywords: Fatty acids ; Mortierella alpina ; ω3-Desaturation ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mutant considered to be defective in the conversion of n-6 to n-3 fatty acids (ω3-desaturation) was derived from a Δ5-desaturation-defective mutant (Mut44) of Mortierella alpina 1S-4, after treating its spores with N-methyl-N′-nitro-N-nitrosoguanidine. This mutant cannot produce 8(Z),11(Z),14(Z),17(Z)-eicosatetraenoic acid or any other n-3 fatty acids, of which about 10% was found in its parental strain upon cultivation at 12°C. The mutant's growth rate was comparable to that of the parental strain when grown at 28°C, but it became much slower when the mutant grew at 12°C, at which the lag phase for Mut44 was about 2 d but 5 d for the mutant.
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    Immune networks modeled by replicator equations (1994)
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    Journal of mathematical biology 33 (1994), S. 111-137 
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    ISSN: 1432-1416
    Keywords: B-cells ; Immune system ; Idiotypic networks ; Mutation ; Replicator equations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In order to evaluate the role of idiotypic networks in the operation of the immune system a number of mathematical models have been formulated. Here we examine a class of B-cell models in which cell proliferation is governed by a non-negative, unimodal, symmetric response function f(h), where the field h summarizes the effect of the network on a single clone. We show that by transforming into relative concentrations, the B-cell network equations can be brought into a form that closely resembles the replicator equation. We then show that when the total number of clones in a network is conserved, the dynamics of the network can be represented by the dynamics of a replicator equation. The number of equilibria and their stability are then characterized using methods developed for the study of second-order replicator equations. Analogies with standard Lotka-Volterra equations are also indicated. A particularly interesting result of our analysis is the fact that even though the immune network equations are not second-order, the number and stability of their equilibria can be obtained by a superposition of second-order replicator systems. As a consequence, the problem of finding all of the equilibrium points of the nonlinear network equations can be reduced to solving linear equations.
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    Inhibition of Mg2+ current by single-gene mutation in Paramecium (1994)
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    The journal of membrane biology 139 (1994), S. 203-212 
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    ISSN: 1432-1424
    Keywords: Mg2+ current ; Mutation ; Paramecium ; Intracellular Mg2+ homeostasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract “Eccentric” is a newly-isolated mutant of Paramecium tetraurelia that fails to swim backwards in response to Mg2+. In the wild type, this backward swimming results from Mg2+ influx via a Mg2+-specific ion conductance (I Mg. Voltage-clamp analysis confirmed that, as suspected, step changes in membrane potential over a physiological range fail to elicit I Mg from eccentric. Further electrophysiological investigation revealed a number of additional ion-current defects in eccentric: (i) The Ca2+ current activated upon depolarization inactivates more slowly in eccentric than in the wild type, and it requires longer to recover from this inactivation. (ii) The Ca2+-dependent Na+ current deactivates significantly faster in the mutant, (iii) The two K+ currents observed upon hyperpolarization are reduced by 〉60% in eccentric. It is difficult to envision how these varied pleiotropic effects could result from loss of a single ion current. Rather, they suggest that the eccentric mutation affects a global regulatory system. Two plausible hypotheses are discussed.
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    Mutation load and mutation-selection-balance in quantitative genetic traits (1994)
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    Journal of mathematical biology 32 (1994), S. 193-218 
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    ISSN: 1432-1416
    Keywords: Selection ; Mutation ; Mutation load ; Quantitative genetic traits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Haldane (1937) showed that the reduction of equilibrium mean fitness in an infinite population due to recurrent deleterious mutations depends only on the mutation rate but not on the harmfulness of mutants. His analysis, as well as more recent ones (cf. Crow 1970), ignored back mutation. The purpose of the present paper is to extend these results to arbitrary mutation patterns among alleles and to quantitative genetic traits. We derive first-order approximations for the equilibrium mean fitness (and the mutation load) and determine the order of the error term. For a metric trait under mutation-stabilizing-selection balance our result differs qualitatively from that of Crow and Kimura (1964), whose analysis is based on a Gaussian assumption. Our general approach also yields a mathematical proof that the variance under the usual mutation-stabilizing-selection model is, to first order, µ/s (the house-of-cards approximation) as µ/s tends to zero. This holds for arbitrary mutant distributions and does not require that the population mean coincide with the optimum. We show how the mutant distribution determines the order of the error term, and thus the accuracy of the house-of-cards approximation. Upper and lower bounds to the equilibrium variance are derived that deviate only to second order as µ/s tends to zero. The multilocus case is treated under the assumption of global linkage equilibrium.
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    The generation of Mutator transposable element subfamilies in maize (1994)
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    Theoretical and applied genetics 87 (1994), S. 657-667 
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    ISSN: 1432-2242
    Keywords: Transposable elements ; Mutation ; Evolution ; DNA repair ; Gene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mobile DNAs of the Mutator system of maize (Zea mays) are exceptional both in structure and diversity. So far, six subfamilies of Mu elements have been discovered; all Mu elements share highly conserved terminal inverted repeats (TIRs), but each sub-family is defined by internal sequences that are apparently unrelated to the internal sequences of any other Mu subfamily. The Mu1/Mu2 subfamily of elements was created by the acquisition of a portion of a standard maize gene (termed MRS-A) within two Mu TIRs. Beside the unusually long (185–359 bp) and diverse TIRs found on all of these elements, other direct and inverted repeats are often found either within the central portion of a Mu element or within a TIR. Our computer analyses have shown that sequence duplications (mostly short direct repeats interrupted by a few base pairs) are common in non-autonomous members of the Mutator, Ac/Ds, and Spm(En) systems. These duplications are often tightly associated with the element-internal end of the TIRs. Comparisons of Mu element sequences have indicated that they share more terminal components than previously reported; all subfamilies have at least the most terminal 215 bp, at one end or the other, of the 359-bp Mu5 TIR. These data suggest that many Mu element subfamilies were generated from a parental element that had termini like those of Mu5. With the Mu5 TIRs as a standard, it was possible to determine that elements like Mu4 could have had their unusual TIRs created through a three-step process involving (1) addition of sequences to interrupt one TIR, (2) formation of a stem-loop structure by one strand of the element, and (3) a subsequent DNA repair/gene conversion event that duplicated the insertion(s) within the other TIR. A similar repair/conversion extending from a TIR stem into loop DNA could explain the additional inverted repeat sequences added to the internal ends of the Mu4 and Mu7 TIRs. This same basic mechanism was found to be capable of generating new Mu element subfamilies. After endonucleolytic attack of the loop within the stem-loop structure, repair/conversion of the gap could occur as an intermolecular event to generate novel internal sequences and, therefore, a new Mu element subfamily. Evidence supporting and expanding this model of new Mu element subfamily creation was identified in the sequence of MRS-A.
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    URL: http://dx.doi.org/10.1007/BF00222890
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    Rapid conversion of rDNA intergenic spacer of diploid mutants of rice derived from γ-ray irradiated tetraploids (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 166-172 
    Details
    ISSN: 1617-4623
    Keywords: Rice ; Tetraploid irradiation ; Genome rearrangement ; rDNA ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The organization of tandemly repeated sequences of ribosomal DNA (rDNA) in rice mutants derived from γ-irradiated tetraploids was analyzed. Southern hybridization analysis of nuclear DNA revealed that most of the intergenic spacers (IGSs) in mutant rDNA are replaced concertedly by new molecular species. The new IGSs are produced by the amplification of a subrepeat of about 250 bp. Results obtained from sequence analyses indicate that various intermediate molecular species of the subrepeat were formed during structuring of the IGS region and that many rearrangements occurred between them. These findings demonstrate the effectiveness of recurrent irradiation of tetraploids for inducing artificial genome rearrangement, and also indicate the extreme plasticity and variability of genome structure in plants.
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    URL: http://dx.doi.org/10.1007/BF00280313
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    Molecular biology of AMP deaminase deficiency (1994)
    Springer
    Pharmacy world & science 16 (1994), S. 55-61 
    Details
    ISSN: 1573-739X
    Keywords: AMP deaminase/deliciency ; Deficiency diseases ; Genetics, biochemical ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In man, there are at least four isoforms of adenosine monophosphate deaminase (AMPD): myoadenylate deaminase in skeletal muscle, the L isoform in liver, and the E1 and E2 isoforms in erythrocytes. Myoadenylafe deaminase is encoded by the AMPD1 gene located on chromosome 1 p13-p21, the L isoform by the AMPD2 gene, and both isoforms in erythrocytes by the AMPD3 gene. Myoadenylate deaminase deficiency is found in 2–3% of all muscle biopsies. The inborn type of myoadenylate deaminase deficiency is caused by a single mutant allele harbouring two mutations: C34→T (Gin→Stop) and C143→T (Pro-48→Leu). Population studies revealed a frequency of the mutant allele of 0.12 in Caucasian Americans and Germans. The C34→T mutation is located in exon 2, which is alternatively spliced in part of the AMPD1 transcript in human muscle. Since the second mutation does not affect enzyme function, alternatively spliced mRNA encodes a catalytically active enzyme. Only one patient with a disorder linked to liver AMPD has been described so far. In this patient the decreased inhibition of this enzyme by GTP resulted in uric acid overproduction and gout. A complete lack of erythrocyte AMPD activity is found in asymptomatic subjects. The molecular basis of both disorders is not yet known.
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    Gene sequence of recA + and construction of recA mutants of Vibrio cholerae (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 295-302 
    Details
    ISSN: 1617-4623
    Keywords: DNA repair ; Recombination ; Virulence ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The recA + gene of Vibrio cholerae O1 has been cloned, its nucleotide sequence determined and the product characterized. A deletion mutation was constructed in the recA gene and mutants showed the typical sensitivity to UV and to DNA-damaging agents, as well as an inability to mediate homologous DNA recombination. The chromosomal recA deletion mutants in V. cholerae do not show altered virulence in the infant mouse cholera model and are thus ideal strains for use in complementation studies.
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    URL: http://dx.doi.org/10.1007/BF00285457
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    Genetic variability of the emm-related genes of the large vir regulon of group A streptococci: potential intra- and intergenomic recombination events (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 691-698 
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    ISSN: 1617-4623
    Keywords: Streptococcus pyogenes ; vir regulon ; emm-related genes ; Recombination ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One of the most prevalent genetic lineages of group A streptococci (GAS) harbors a genomic locus termed the large vir regulon, which contains an emm gene encoding the antiphagocytic M protein, and structurally related fcrA and enn (emm-related) genes encoding immunoglobulin-binding proteins. In the present study more than 100 large vir regulons from 42 different GAS serotypes were analyzed by PCR and partial DNA sequencing. On comparing these data to published sequences, sites of mutational and putative recombinational events were identified and ordered with respect to their intra/intergenic or intra/intergenomic nature. The emm-related genes were found to display small intragenic deletions or insertions, were completely deleted from, or newly inserted into the genome, or were fused to adjacent genes. Intergenomic exchanges of complete emm-related genes, or segments thereof, between different vir regulons were detected. Most of these processes seem to involve short flanking direct repeats. Occasionally, the structural changes could be correlated with changes in the functions of the encoded proteins.
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    Mapping a mutator, mu2, which increases the frequency of terminal deletions in Drosophila melanogaster (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 598-607 
    Details
    ISSN: 1617-4623
    Keywords: Deficiency mapping ; Mutation ; Telomere Chromosome structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mutator, mu2, in Drosophila melanogaster has been identified recently that potentiates the recovery of terminal deficiencies. The deleted chromosomes behave as if they had been capped; that is, they are protected from degradation and from fusion with other chromosome fragments. The mutator maps near the telomere on the left arm of chromosome 3. Using the selectable marker Aprt, 150 deficiencies for region 62 of the cytological map have been recovered. These deficiencies identify the map position of mu2 as 62B11-C1. A yeast artificial chromosome spanning this region has been subcloned into lambda phage, and the positions of deficiency breakpoints on either side of the mu2 gene have been identified within the subclones. These positions limit the location of the left end of the gene to a 23 kb region. In the course of these experiments, three additional, presumptive mutant alleles were identified, suggesting that other mutator alleles remain undiscovered in many standard laboratory stocks.
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    Diploid yeast cells yield homozygous spontaneous mutations (1993)
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    Current genetics 23 (1993), S. 430-434 
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    ISSN: 1432-0983
    Keywords: S. cerevisiae ; Mutational homozygosis ; Loss of heterozygosity ; Mutation ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A leucine-requiring hybrid of Saccharomyces cerevisiae, homoallelic at the LEU1 locus (leu1–12/leu1–12) and heterozygous for three chromosome-VII genetic markers distal to the LEU1 locus, was employed to inquire: (1) whether spontaneous gene mutation and mitotic segregation of heterozygous markers occur in positive nonrandom association and (2) whether homozygous LEU1/LEU1 mutant diploids are generated. The results demonstrate that gene mutation of leu1–12 to LEU1 and mitotic segregation of heterozygous chromosome-VII markers occur in strong positive nonrandom association, suggesting that the stimulatory DNA lesion is both mutagenic and recombinogenic. In addition, genetic analysis of diploid Leu+ revertants revealed that approximately 3% of mutations of leu1–12 to LEU1 result in LEU1/LEU1 homozygotes. Red-white sectored Leu+ colonies exhibit genotypes that implicate postreplicational chromatid breakage and exchange near the site of leu1–12 reversion, chromosome loss, and subsequent restitution of diploidy, in the sequence of events leading to mutational homozygosis. By analogy, diploid cell populations can yield variants homozygous for novel recessive gene mutations at biologically significant rates. Mutational homozygosis may be relevant to both carcinogenesis and the evolution of asexual diploid organisms.
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    URL: http://dx.doi.org/10.1007/BF00312630
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    Induction of SOS like responses by nitrofurantoin in Vibrio cholerae el tor cells (1993)
    Springer
    Archives of microbiology 159 (1993), S. 98-100 
    Details
    ISSN: 1432-072X
    Keywords: Prophage induction ; Weigle reactivation ; Mutation ; Filamentation ; Nitrofurantoin ; Vibrio cholerae el tor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Treatment of Vibrio cholerae el tor strain SLH22(J) with nitrofurantoin induced dose-dependent prophage ‘kappa’, the maximum induction being 6-fold the spontaneous induction level. UV-inactivated ‘kappa’ phages were Weigle reactivated, the maximum Weigle factor being 1.8 and 2.0 respectively in nitrofurantoin and UV pretreated el tor strain H218 Smr. Nitrofurantoin treatment also caused significant filamentation of the el tor strain H218 Smr and mutation of these cells from ampicillin sensitivity to ampicillin resistance. The levels of the four SOS-like responses induced by this drug were low but significant.
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    URL: http://dx.doi.org/10.1007/BF00244270
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    The genealogical process of neutral genes with mutation in geographically structured populations (1993)
    Springer
    Journal of mathematical biology 31 (1993), S. 123-132 
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    ISSN: 1432-1416
    Keywords: Genealogy ; Coalescent ; Mutation ; Migration ; Markov chain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The genealogical process of neutral genes with mutation in geographically structured populations is investigated. Following Watterson [24], the sampled genes are partitioned into two types, old equivalence classes and new equivalence classes. The model is described by a bivariate continuous time Markov chain as an interactive particle system. Some results are obtained in the two-population model and the stepping stone model with symmetric nearest-neighbour migration.
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    URL: http://dx.doi.org/10.1007/BF00171221
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    What is the difference between models of error thresholds and Muller's ratchet? (1993)
    Springer
    Journal of mathematical biology 32 (1993), S. 33-44 
    Details
    ISSN: 1432-1416
    Keywords: Mutation ; Selection ; Random drift ; Muller's ratchet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Two independently derived theories predict upper limits to the mutation rate beyond which evolution cannot be controlled by natural selection. One is the theory of Muller's ratchet, explaining the low phylogenetic age of parthenogenetic clones, the other one is the theory of error thresholds, predicting the maximal information content of selfreplicating molecules in prebiotic evolution. Both theories are based on similiar mathematical models but reach qualitatively different conclusions. Muller's ratchet only works in finite populations, while error thresholds are a deterministic phenomenon. In this paper it is shown that this discrepancy is due to different assumptions about the fitness values the selfreplicative units are allowed to assume. If no lower limit for the fitness values is assumed then the deterministic equilibrium frequency of the currently best genotype is strictly positive, no matter how strong mutation is, and random drift is required to cause its extinction (Muller's ratchet). On the other hand, positive lower limits for the fitness values lead to zero equilibrium frequencies in the deterministic description provided the mutation rate is high enough and no back mutations occur.
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    Comparison of the nucleotide sequences of the meta-cleavage pathway genes of TOL plasmid pWW0 from Pseudomonas putida with other meta-cleavage genes suggests that both single and multiple nucleotide substitutions contribute to enzyme evolution (1993)
    Springer
    Molecular genetics and genomics 239 (1993), S. 81-89 
    Details
    ISSN: 1617-4623
    Keywords: TOL plasmid ; Biodegradation ; Pseudornonas putida ; Evolution ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TOL plasmid pWW0 from Pseudomonas putida mt-2 encodes catabolic enzymes required for the oxidation of toluene and xylenes. The structural genes for these catabolic enzymes are clustered into two operons, the xylCMABN operon, which encodes a set of enzymes required for the transformation of toluene/xylenes to benzoate/toluates, and the xylXYZLTEGFJQKIH operon, which encodes a set of enzymes required for the transformation of benzoate/toluates to Krebs cycle intermediates. The latter operon can be divided physically and functionally into two parts, the xylXYZL cluster, which is involved in the transformation of benzoate/toluates to (methyl)catechols, and the xylTEGFJQKIH cluster, which is involved in the transformation of (methyl)catechols to Krebs cycle intermediates. Genes isofunctional to xylXYZL are present in Acinetobacter calcoaceticus, and constitute a benzoate-degradative pathway, while xylTEGFJQKIH homologous encoding enzymes of a methylphenol-degradative pathway and a naphthalene-degradative pathway are present on plasmid pVI150 from P. putida CF600, and on plasmid NAH7 from P. putida PpG7, respectively. Comparison of the nucleotide sequences of the xylXYZLTEGFJQKIH genes with other isofunctional genes suggested that the xylTEGFJQKIH genes on the TOL plasmid diverged from these homologues 20 to 50 million years ago, while the xylXYZL genes diverged from the A. calcoaceticus homologues 100 to 200 million years ago. In codons where amino acids are not conserved, the substitution rate in the third base was higher than that in synonymous codons. This result was interpreted as indicating that both single and multiple nucleotide substitutions contributed to the amino acid-substituting mutations, and hence to enzyme evolution. This observation seems to be general because mammalian globin genes exhibit the same tendency.
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    nir1, a conditional-lethal mutation in barley causing a defect in nitrite reduction (1993)
    Springer
    Molecular genetics and genomics 236 (1993), S. 275-282 
    Details
    ISSN: 1617-4623
    Keywords: Hordeum vulgare L. ; Nitrite reduction ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eleven green individuals were isolated when 95000 M2 plants of barley (Hordeum vulgare L.), mutagenised with azide in the M1, were screened for nitrite accumulation in their leaves after nitrate treatment in the light. The selected plants were maintained in aerated liquid culture solution containing glutamine as sole nitrogen source. Not all plants survived to flowering and some others that did were not fertile. One of the selected plants, STA3999, from the cultivar Tweed could be crossed to the wild-type cultivar and analysis of the F2 progeny showed that leaf nitrite accumulation was due to a recessive mutation in a single nuclear gene, which has been designated Nir1. The homozygous nir1 mutant could be maintained to flowering in liquid culture with either glutamine or ammonium as sole nitrogen source, but died within 14 days after transfer to compost. The nitrite reductase cross-reacting material seen in nitrate-treated wild-type plants could not be detected in either the leaf or the root of the homozygous nir1 mutant. Nitrite reductase activity, measured with dithionite-reduced methyl viologen as electron donor, of the nitrate-treated homozygous nir1 mutant was much reduced but NADH-nitrate reductase activity was elevated compared to wild-type plants. We conclude that the Nir1 locus determines the formation of nitrite reductase apoprotein in both the leaf and root of barley and speculate that it represents either the nitrite reductase apoprotein gene locus or, less likely, a regulatory locus whose product is required for the synthesis of nitrite reductase, but not nitrate reductase. Elevation of NADH-nitrate reductase activity in the nir1 mutant suggests a regulatory perturbation in the expression of the Narl gene.
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    URL: http://dx.doi.org/10.1007/BF00277123
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    Evolutionary consequences of nonrandom damage and repair of chromatin domains (1992)
    Springer
    Journal of molecular evolution 35 (1992), S. 156-180 
    Details
    ISSN: 1432-1432
    Keywords: DNA damage ; DNA repair ; Chromatin ; Evolution ; Nucleosomes ; Nuclear matrix ; Active genes ; Z-DNA ; Sperm ; Mutation ; Molecular clock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Some evolutionary consequences of different rates and trends in DNA damage and repair are explained. Different types of DNA damaging agents cause nonrandom lesions along the DNA. The type of DNA sequence motifs to be preferentially attacked depends upon the chemical or physical nature of the assaulting agent and the DNA base composition. Higher-order chromatin structure, the nonrandom nucleosome positioning along the DNA, the absence of nucleosomes from the promoter regions of active genes, curved DNA, the presence of sequence-specific binding proteins, and the torsional strain on the DNA induced by an increased transcriptional activity all are expected to affect rates of damage of individual genes. Furthermore, potential Z-DNA, H-DNA, slippage, and cruciform structures in the regulatory region of some genes or in other genomic loci induced by torsional strain on the DNA are more prone to modification by genotoxic agents. A specific actively transcribed gene may be preferentially damaged over nontranscribed genes only in specific cell types that maintain this gene in active chromatin fractions because of (1) its decondensed chromatin structure, (2) torsional strain in its DNA, (3) absence of nucleosomes from its regulatory region, and (4) altered nucleosome structure in its coding sequence due to the presence of modified histones and HMG proteins. The situation in this regard of germ cell lineages is, of course, the only one to intervene in evolution. Most lesions in DNA such as those caused by UV or DNA alkylating agents tend to diminish the GC content of genomes. Thus, DNA sequences not bound by selective constraints, such as pseudogenes, will show an increase in their AT content during evolution as evidenced by experimental observations. On the other hand, transcriptionally active parts may be repaired at rates higher than inactive parts of the genome, and proliferating cells may display higher repair activities than quiescent cells. This might arise from a tight coupling of the repair process with both transcription and replication, all these processes taking place on the nuclear matrix. Repair activities differ greatly among species, and there is a good correlation between life span and repair among mammals. It is predicted that genes that are transcriptionally active in germ-cell lineages have a lower mutation rate than bulk DNA, a circumstance that is expected to be reflected in evolution. Exception to this rule might be genes containing potential Z-DNA, H-DNA, or cruciform structures in their coding or regulatory regions that appear to be refractory to repair. This study supports the molecular clock hypothesis when applied to one gene within a group of related species and contends that evolutionary rates might vary between genes and gene segments not only as a result of differences in selective constraints but also as a result of differences in the rate of damage minus rate of repair among different segments of chromatin DNA.
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    Stratigraphy of total metals in PIRLA sediment cores (1992)
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    Journal of paleolimnology 7 (1992), S. 191-214 
    Details
    ISSN: 1573-0417
    Keywords: geochemistry ; metals ; lake sediments ; paleolimnology ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from 30 low-alkalinity lakes in northern New England (NE), New York (NY), the northern Great Lakes States (NGLS) of Minnesota, Michigan, and Wisconsin, and Florida (FL) have been dated by 210Pb and analyzed for water and organic content, eight major elements (Al, Ti, Fe, Mn, Ca, Mg, Na, K) plus four trace metals (Pb, Zn, Cu, and V). Variations in the percentages of major elements through time are dominated by long-term independent variations in the abundance of SiO2, FeO, and to a lesser extent Ca and Al. Additional variations are caused by varying proportions of inorganic matter. Major variations in chemistry are generally unrelated to documented distrubances in the watersheds; most disturbances are minor fires or selective logging. Accelerated accumulation of Pb from atmospheric sources into sediment first occurs in sediment dated between 1800 and 1850 in NY and NE, slightly later in the NGLS region, and about 1900 in FL. Modern accumulation rates in all areas are comparable (ca. 1 to 4 μg cm−2 yr−1). Accumulation rates of Pb in some lakes have declined significantly from 1975 to 1985. Atmospheric deposition of anthropogenic Zn and Cu is also indicated by generally increasing accumulation rates in sediment cores, but the record is not as clear nor are chemical profiles in all lakes parallel to the trends in atmospheric emissions inferred on the basis of fossil fuel consumption, smelting, and other industrial activities. Inter-lake variations in profiles of Cu and Zn are large. Vanadium accumulation rates increase by the 1940s in NY and NE, but not until the 1950s in the NGLS region. This timing correlates with regional trends in the combustion of fuel oil, a major source of atmospheric V. Acidification of some of the lakes is suggested by decreases in the concentration and accumulation rates of Mn, Ca, and Zn in recent sediment, relative to other elements of catchment origin. The decreases generally occur slightly before the onset of acidification as indicated by diatoms. Increased sediment accumulation rates for Fe may indicate the acidification of watershed soils. The use of the accumulation rate of TiO2 as an indicator of rates of erosion and for normalization of trace metal accumulation rates is in question for lakes where the flux of TiO2 from the atmosphere varies and is a significant fraction of the total flux of TiO2 to the sediment.
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    Mutation in autocatalytic reaction networks (1992)
    Springer
    Journal of mathematical biology 30 (1992), S. 597-632 
    Details
    ISSN: 1432-1416
    Keywords: Autocatalysis ; Mutation ; Perturbation theory ; Qualitative analysis ; Replication dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A class of kinetic equations describing catalysed and template induced replication, and mutation is introduced. This ODE in its most general form is split into two vector fields, a replication and a mutation field. The mutation field is considered as a perturbation of the replicator equation. The perturbation expansion is a Taylor series in a mutation parameter λ. First, second and higher order contributions are computed by means of the conventional Rayleigh-Schrödinger approach. Qualitative shifts in the positions of rest points and limit cycles on the boundary of the physically meaningful part of concentration space are predicted from flow topologies. The results of the topological analysis are summarized in two theorems which turned out to be useful in applications: the rest point migration theorem (RPM) and the limit cycle migration theorem (LCM). Quantitative expressions for the shifts of rest points are computed directly from the perturbation expansion. The concept is applied to a collection of selected examples from biophysical chemistry and biology.
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    Mutation in autocatalytic reaction networks (1992)
    Springer
    Journal of mathematical biology 30 (1992), S. 597-631 
    Details
    ISSN: 1432-1416
    Keywords: Autocatalysis ; Mutation ; Perturbation theory ; Qualitative analysis ; Replication dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A class of kinetic equations describing catalysed and template induced replication, and mutation is introduced. This ODE in its most general form is split into two vector fields, a replication and a mutation field. The mutation field is considered as a perturbation of the replicator equation. The perturbation expansion is a Taylor series in a mutation parameter λ. First, second and higher order contributions are computed by means of the conventional Rayleigh-Schrödinger approach. Qualitative shifts in the positions of rest points and limit cycles on the boundary of the physically meaningful part of concentration space are predicted from flow topologies. The results of the topological analysis are summarized in two theorems which turned out to be useful in applications: the rest point migration theorem (RPM) and the limit cycle migration theorem (LCM). Quantitative expressions for the shifts of rest points are computed directly from the perturbation expansion. The concept is applied to a collection of selected examples from biophysical chemistry and biology.
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    Probabilistic methodology for estimation of undiscovered petroleum resources in play analysis of the United States (1992)
    Springer
    Natural resources research 1 (1992), S. 153-162 
    Details
    ISSN: 1573-8981
    Keywords: Oil and gas assessment ; Analytic probability ; Play analysis ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A geostochastic system called FASPF was developed by the U.S. Geological Survey for their 1989 assessment of undiscovered petroleum resources in the United States. FASPF is a fast appraisal system for petroleum play analysis using a field-size geological model and an analytic probabilistic methodology. The geological model is a particular type of probability model whereby the volumes of oil and gas accumulations are modeled as statistical distributions in the form of probability histograms, and the risk structure is bilevel (play and accumulation) in terms of conditional probability. The probabilistic methodology is an analytic method derived from probability theory rather than Monte Carlo simulation. The resource estimates of crude oil and natural gas are calculated and expressed in terms of probability distributions. The probabilistic methodology developed by the author is explained. The analytic system resulted in a probabilistic methodology for play analysis, subplay analysis, economic analysis, and aggregation analysis. Subplay analysis included the estimation of petroleum resources on non-Federal offshore areas. Economic analysis involved the truncation of the field size with a minimum economic cutoff value. Aggregation analysis was needed to aggregate individual play and subplay estimates of oil and gas, respectively, at the provincial, regional, and national levels.
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    Beijerinckia indica var.penicillanicum penicillin V acylase: enhanced enzyme production by catabolite repression-resistant mutant and effect of solvents on enzyme activity (1991)
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 209-214 
    Details
    ISSN: 1476-5535
    Keywords: Penicillin V acylase ; Beijerinckia indica var.penicillanicum ; Mutation ; Solvent effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Beijerinckia indica var.penicillanicum mutant UREMS-5, producing 168% more penicillin V acylase, was obtained by successive treatment with UV, γ-irradiation and ethylmethane sulfonate. Penicillin V acylase production by the mutant strain was resistant to catabolite repression by glucose. Incorporation of glucose, sodium glutamate and vegetable oils in the medium enhanced enzyme production. The maximum specific production of penicillin V acylase was 244 IU/g dry weight of cells. Effect of solvents on hydrolysis of penicillin V by soluble penicillin V acylase and whole cells was studied. Methylene chloride, chloroform and carbon tetrachloride significantly stimulated the rate of penicillin V hydrolysis by whole cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01575885
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  • 94
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    Use of continuous-flow UV-induced mutation technique to enhance chlorinated organic biodegradation (1991)
    Springer
    Journal of industrial microbiology and biotechnology 8 (1991), S. 99-106 
    Details
    ISSN: 1476-5535
    Keywords: Mutation ; UV ; Biodegradation ; Chlorinated organic compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary In this study, a continuous-flow UV-induced mutation (CUM) device and the CUM device coupled to a selector (CUMS) reactor were fabricated and tested for their ability to enhance the probability of obtaining populations capable of chlorinated organic biodegradation. A mixed culture of bacteria were used as the starting strain for both the CUM and CUMS processes. Populations were obtained from the CUM and CUMS systems capable of 4-chlorobenzoic acid, 2,4-dichlorobenzoic acid and chlorendic acid biodegradation. Non-UV irradiated population served as controls for the experiments and did not demonstrate chlorinated organic biodegradation over the test duration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01578760
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  • 95
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    A survey of dermatophytes from human patients in the United States from 1985 to 1987 (1991)
    Springer
    Mycopathologia 114 (1991), S. 117-126 
    Details
    ISSN: 1573-0832
    Keywords: dermatophytes ; survey ; United States ; humans ; 1985/87
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A survey of dermatophytes isolated from patients seeking medical advice was made from 1985 to 1987 in the United States. The survey included 54 locations with data from 45 cities and one state. Listing of the isolated dermatophytes and the frequency given by percentage of the total follows: Trichophyton rubrum 54.8%, T. tonsurans 31.3%, T. mentagrophytes 6.0%, Microsporum canis 4.0%, Epidermophyton floccosum 2.0%, M. gypseum 0.6%, and T. verrucosum 0.2%. Out of a total of 14,696 isolates M. audouinii was cultured 13 times, T. violaceum 12 times, M. nanum 6 times, T. terrestre 4 times, and T. soudanense twice. Single isolations were made of M.fulvum, M. ferrugineum and T. schoenleinii. Collection of dermatophyte data in Tucson, Arizona, began in 1966. In 1987, the first case of tinea capitis caused by T. tonsurans was observed. Other isolates of this organism as the cause of tinea capitis were made in this city during that year. These infections were in black children. With the recent growth of Tucson, the percentage of blacks in the population increased and this pathogen was introduced into the general population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00436431
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  • 96
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    Prolonged environmental stress via a two step process selects mutants of Escherichia, Salmonella and Pseudomonas that grow at 54°C (1991)
    Springer
    Archives of microbiology 156 (1991), S. 307-311 
    Details
    ISSN: 1432-072X
    Keywords: Temperature ; Mutation ; Thermotolerance ; Escherichia coli ; Salmonella typhimurium ; Pseudomonas aeruginosoa ; DNA gyrase ; gyrA ; Nalidixic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A prolonged incubation of Escherichia, Salmonella or Pseudomonas at 48°C with nalidixic acid selected mutants (T48) able to grow at 48°C. A prolonged incubation at 54°C of the T48 mutants selected mutants (T54) able to grow at 54°C. These mutants were susceptible to the same bacteriophages as the original mesophilic strains. Auxotrophic phenotypes of Escherichia coli and Salmonella typhimurium mesophilic parents were demonstrated by these mutants if they were cultivated on minimal agar with cellobiose at 48°C or 54°C or on a minimal agar with glucose at 37°C. The T48 alleles mapped in the gyrA region of E. coli or S. typhimurium chromosome. In S. typhimurium the T54 alleles, which permit growth at 54°C, were shown by cotransductional analysis to be linked to gyrA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263003
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  • 97
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    Moments, cumulants, and polygenic dynamics (1991)
    Springer
    Journal of mathematical biology 30 (1991), S. 199-213 
    Details
    ISSN: 1432-1416
    Keywords: Polygenic dynamics ; Quantitative trait ; Selection ; Mutation ; Cumulants ; Generating function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A new approach for describing the evolution of polygenic traits subject to selection and mutation is presented. Differential equations for the change of cumulants of the allelic frequency distribution at a particular locus and for the cumulants of the distributions of genotypic and phenotypic values are derived. The derivation is based on the assumptions of random mating, no sex differences, absence of random drift, additive gene action, linkage equilibrium, and Hardy-Weinberg proportions. Cumulants are a set of parameters that, like moments, describe the shape of a probability density. Compared with moments, however, they have properties that make them a much more convenient tool for investigating polygenic traits. Applications to directional and stabilizing selection are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160336
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  • 98
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    DNA sequence of the Doe retroposon in the white-one mutant of Drosophila melanogaster and of secondary insertions in the phenotypically altered derivatives white honey and white-eosin (1991)
    Springer
    Molecular genetics and genomics 225 (1991), S. 17-24 
    Details
    ISSN: 1617-4623
    Keywords: Retroposon ; Transposable element ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We analysed the structure of the white locus of Drosophila melanogaster in a family of related white mutants. The white-one mutant has bleach white eyes, and a Doc transposable element is inserted into the promoter region of the white locus. The DNA sequence of this Doc insertion was determined, and showed it to be closely related to other Drosophila melanogaster retroposons such as the I factor and the F, G and jockey elements. There are two long open reading frames, which encode a putative nucleic acid binding protein and a putative reverse transcriptase, respectively. Two independent, partially pigmented derivatives were analysed by cloning sequences from this region. In white-honey a transposable element of the retroviral class, B104, is inserted within the Doe element. In white-eosin there is an insertion within the Doc element of a 190 by sequence that appears to be a member of a novel family of transposable elements. This pogo element is of the same structural class as the Drosophila melanogaster P and hobo elements. These data are consistent with the hypothesis that the Doc retroposon cannot excise, and that, for the white-one mutation, flies with altered phenotypes are most often generated by the insertion of additional transposable elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00282637
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  • 99
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    How efficient are national environmental standards? A benefit-cost analysis of the United States experience (1991)
    Springer
    Environmental and resource economics 1 (1991), S. 385-413 
    Details
    ISSN: 1573-1502
    Keywords: Environmental standards ; environmental regulations ; benefit-cost ; cost-benefit ; United States ; efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: Abstract This paper summarizes the results of the first systematic, geographically-specific efficiency assessment of the U.S. experience with national environmental standards and with alternative approaches to establishing those standards. This ex-post evaluation assessed the net benefits that resulted from EPA's regulation of conventional air and water pollutants from the pulp and paper industry between 1973 and 1984. The paper compares the benefit-cost efficiencies of the three dominant regulatory approaches: technology, ambient, and benefits. Unlike previous studies, which assessed benefits and costs on a national basis, the study estimates both costs and benefits on a facility-by-facility basis. The analysis shows how the efficiency of national environmental regulations can vary dramatically at local levels. The authors conclude that the technology-based standards for water pollution management failed as an efficient environmental strategy. The costs clearly exceeded the benefits in the aggregate, as well as in the specific in most situations. Benefits exceeded costs at only 11 of the 68 mills investigated. The ambient based standards for air pollution management succeeded as an environmental strategy in the aggregate, but succeeded in the specific for only one-third of the mills (22 of 60 mills). The benefits-based standards for air pollution management also succeeded in the aggregate as well as in the specific for about one-half of the mills. Benefits exceeded costs at 29 of the 60 mills investigated. The results of the study point to two major conclusions. First, a regulatory policy that is based on some measure of environmental results, either ambient-based or benefits-based, will be more efficient than a policy that ignores environmental results. Second, truly efficient policies for reducing environmental risks require pollution mitigation decisions that take into account local conditions. These include not only the changes in local ambient conditions, but also the number of people who will benefit from pollution reduction decisions. This latter conclusion suggests that national environmental standards per se may be inefficient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377494
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  • 100
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    Generation of new functional mutant alleles by premeiotic disruption of the Neurospora crassa am gene (1990)
    Springer
    Current genetics 18 (1990), S. 441-445 
    Details
    ISSN: 1432-0983
    Keywords: Neurospora crassa ; Mutation ; RIP phenomenon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the further analysis of a cross in which the mis-sense allele, am 3, of the Neurospora crassa am (glutamate dehydrogenase) gene was present in one parent together with two ectopic wild-type gene copies, one ascus was identified in which the two ectopic copies had been inactivated by the RIP process whereas the am 3 allele continued to produce its characteristic enzyme variety in active, but heat-sensitive, form. The am 3 allele had also acquired a new HindIII restriction site. It had no detectable methylation. The mutations responsible respectively for the new restriction site and the modified enzyme properties were separated from each other, and from the original am 3 mutation, by selecting for intragenic recombination on either side of the am 3 site. In this way two new effectively wild-type alleles were generated, one characterised by its heat-sensitive and kinetically modified enzyme product and the other by a new HindIII site. These results demonstrate that the RIP phenomenon can be a source of new functional alleles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00309914
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