نتایج جستجو برای: mutational pressure
تعداد نتایج: 425613 فیلتر نتایج به سال:
The rbcL (ribulose-1,5-biphosphate carboxylase oxygenase) gene plays a crucial role in carbon fixation. Previous studies shed light on its evolutionary relationship among different Phyla. Here, authors have done a comparative study of rbcL genes among proteobacteria, archaea, cyanobacteria and plants based on their compositional variations (GC%, amino acid frequency, codon usage, etc.). In addi...
PURPOSE Juvenile open-angle glaucoma (JOAG) differs from primary open-angle glaucoma in that it is usually a more severe phenotype and has an earlier age of onset. Optineurin was recently associated with a variant of POAG that is characterized by intraocular pressure within normal limits: normal-tension glaucoma. The present study tested whether OPTN sequence changes play a role in early-onset ...
Laboratory experiments show us that the deleterious character of accumulated novel age-specific mutations is reduced and made less variable with increased age. While theories of aging predict that the frequency of deleterious mutations at mutation-selection equilibrium will increase with the mutation's age of effect, they do not account for these age-related changes in the distribution of de no...
Estimates of mutational parameters, such as the average fitness effect of a new mutation and the rate at which new genetic variation for fitness is created by mutation, are important for the understanding of many biological processes. However, the causes of interspecific variation in mutational parameters and the extent to which they vary within species remain largely unknown. We maintained mul...
As François Jacob pointed out over 30 years ago, evolution is a tinkering process, and, as such, relies on the genetic diversity produced by mutation subsequently shaped by Darwinian selection. However, there is one implicit assumption that is made when studying this tinkering process; it is typically assumed that all amino acid residues are equally likely to mutate or to result from a mutation...
In small or repeatedly bottlenecked populations, mutations are expected to accumulate by genetic drift, causing fitness declines. In mutational meltdown models, such fitness declines further reduce population size, thus accelerating additional mutation accumulation and leading to extinction. Because the rate of mutation accumulation is determined partly by the mutation rate, the risk and rate o...
Genomic structural variations are an important source of genetic diversity. Copy number variations (CNVs), gains and losses of large regions of genomic sequence between individuals of a species, have been associated with a wide variety of phenotypic traits. However, in cattle, as well as many other species, relatively little is understood about CNV, including frequency of CNVs in the genome, si...
OBJECTIVES/HYPOTHESIS Mutational falsetto is a functional voice disorder characterized by failure of the male high-pitched preadolescent voice to transition to the lower pitch of adolescence and adulthood. Few objective outcomes data exist regarding the effectiveness of voice therapy for this poorly understood disorder. This study examined the immediate effects of a single therapy session using...
Chromohalobacter salexigens, a Gammaproteobacterium belonging to the family Halomonadaceae, shows a broad salinity range for growth. In order to reveal the factors influencing architecture of protein coding genes in C. salexigens, pattern of synonymous codon usage bias has been investigated. Overall codon usage analysis of the microorganism revealed that C and G ending codons are predominantly ...
BACKGROUND In spite of extensive research on the effect of mutation and selection on codon usage, a general model of codon usage bias due to mutational bias has been lacking. Because most amino acids allow synonymous GC content changing substitutions in the third codon position, the overall GC bias of a genome or genomic region is highly correlated with GC3, a measure of third position GC conte...
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