Analysis ups estimate of spontaneous mutations’ role in autism

Spectrum ◽  
2021 ◽  
Author(s):  
Laura Dattaro
Keyword(s):  
Spontaneous Mutations

scholarly journals On the Average Coefficient of Dominance of Deleterious Spontaneous Mutations

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 1991-2001 ◽  
Author(s):  
A García-Dorado ◽  
A Caballero
Keyword(s):  
Deleterious Mutations ◽  
Spontaneous Mutations ◽  
Partial Dominance ◽  
High Viability ◽  
Significant Difference ◽  
Plausible Hypothesis ◽  
Average Coefficient ◽  
Series Of Experiments ◽  
Very High ◽  
Balancer Chromosome

Abstract T. Mukai and co-workers in the late 1960s and O. Ohnishi in the 1970s carried out a series of experiments to obtain direct estimates of the average coefficient of dominance (h¯) of minor viability mutations in Drosophila melanogaster. The results of these experiments, although inconsistent, have been interpreted as indicating slight recessivity of deleterious mutations, with h¯≈0.4. Mukai obtained conflicting results depending on the type of heterozygotes used, some estimates suggesting overdominance and others partial dominance. Ohnishi's estimates, based on the ratio of heterozygous to homozygous viability declines, were more consistent, pointing to the above value. However, we have reanalyzed Ohnishi's data, estimating h¯ by the regression method, and obtained a much smaller estimate of ~0.1. This significant difference can be due partly to the different weighting implicit in the estimates, but we suggest that this is not the only explanation. We propose as a plausible hypothesis that a putative nonmutational decline in viability occurring in the first half of Ohnishi's experiment (affecting both homozygotes and heterozygotes) has biased upward the estimates from the ratio, while it would not bias the regression estimates. This hypothesis also explains the very high h¯≈0.7 observed in Ohnishi's high-viability chromosomes. By constructing a model of spontaneous mutations using parameters in the literature, we investigate the above possibility. The results indicate that a model of few mutations with moderately large effects and h¯≈0.2 is able to explain the observed estimates and the distributions of homozygous and heterozygous viabilities. Accounting for an expression of mutations in genotypes with the balancer chromosome Cy does not alter the conclusions qualitatively.

scholarly journals Spontaneous Mutations That Confer Antibiotic Resistance inHelicobacter pylori

2001 ◽  
Vol 45 (3) ◽  
pp. 727-733 ◽  
Author(s):  
Ge Wang ◽  
Trevor J. M. Wilson ◽  
Qin Jiang ◽  
Diane E. Taylor
Keyword(s):  
Mutant Allele ◽  
Rapid Development ◽  
Mutagenic Effect ◽  
Serial Passage ◽  
Sublethal Dose ◽  
23S Rrna ◽  
Rrna Gene ◽  
Spontaneous Mutations ◽  
H Pylori

ABSTRACT In this study, we systematically examined in vitro frequencies and spectra of the spontaneous mutations in Helicobacter pylori that confer resistance to clarithromycin (Clar), metronidazole (Mtzr), amoxicillin (Amxr), ciprofloxacin (Cipr), and rifampin (Rifr). The mutation rate of Rifror Cipr determined in a fluctuation assay is 1 × 10−8 to 2 × 10−8 per cell per division. In contrast, the mutation rates of Clar, Mtzr, and Amxr are much lower (<10−9). However, Mtzr mutants could be readily selected in vitro by using the serial passage method, suggesting that the mutagenic effect and selective effect of a sublethal dose of metronidazole contribute to the rapid development of Mtzr. Analysis of spontaneous Rifr, Clar, and Cipr mutants confirmed previous results indicating that mutations within therpoB gene, the 23S rRNA gene, and thegyrA gene, respectively, are responsible; also, several new mutant alleles were identified. Mtzrmutants resulted most frequently, but not always, from mutations in the rdxA gene. DNA fragments containing each mutant allele could readily transform susceptibleH. pylori strains to resistance, confirming that each mutant allele is responsible for the resistance phenotype.

scholarly journals E scherichia coli DNA polymerase III is responsible for the high level of spontaneous mutations in mutT strains

2012 ◽  
Vol 86 (6) ◽  
pp. 1364-1375 ◽  
Author(s):  
Masami Yamada ◽  
Masatomi Shimizu ◽  
Atsushi Katafuchi ◽  
Petr Grúz ◽  
Shingo Fujii ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Dna Polymerase Iii ◽  
Spontaneous Mutations ◽  
Polymerase Iii ◽  
High Level

DNA sequence analysis of spontaneous mutations in the SUP4-o gene of Saccharomyces cerevisiae

1988 ◽  
Vol 8 (2) ◽  
pp. 978-981
Author(s):  
C N Giroux ◽  
J R Mis ◽  
M K Pierce ◽  
S E Kohalmi ◽  
B A Kunz
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Sequence Analysis ◽  
Transposable Elements ◽  
Dna Sequencing ◽  
Dna Sequence ◽  
Base Pair ◽  
Dna Sequence Analysis ◽  
Spontaneous Mutations ◽  
Yeast Saccharomyces Cerevisiae ◽  
Spontaneous Mutagenesis

A collection of 196 spontaneous mutations in the SUP4-o gene of the yeast Saccharomyces cerevisiae was analyzed by DNA sequencing. The classes of mutation identified included all possible types of base-pair substitution, deletions of various lengths, complex alterations involving multiple changes, and insertions of transposable elements. Our findings demonstrate that at least several different mechanisms are responsible for spontaneous mutagenesis in S. cerevisiae.

scholarly journals Spontaneous mutations in Streptococcus pyogenes isolates from streptococcal toxic shock syndrome patients play roles in virulence

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Tadayoshi Ikebe ◽  
Takayuki Matsumura ◽  
Hisako Nihonmatsu ◽  
Hitomi Ohya ◽  
Rumi Okuno ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Toxic Shock Syndrome ◽  
Streptococcal Toxic Shock Syndrome ◽  
Spontaneous Mutations ◽  
Toxic Shock

scholarly journals Fitness Effects of Spontaneous Mutations in Picoeukaryotic Marine Green Algae

2016 ◽  
Vol 6 (7) ◽  
pp. 2063-2071 ◽  
Author(s):  
Marc Krasovec ◽  
Adam Eyre-Walker ◽  
Nigel Grimsley ◽  
Christophe Salmeron ◽  
David Pecqueur ◽  
...  
Keyword(s):  
Green Algae ◽  
Spontaneous Mutations ◽  
Fitness Effects
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