scholarly journals Codon usage bias and base composition of nuclear genes in Drosophila.

Genetics ◽  
1993 ◽  
Vol 134 (3) ◽  
pp. 847-858 ◽  
Author(s):  
E N Moriyama ◽  
D L Hartl
Keyword(s):  
Codon Usage ◽  
Codon Usage Bias ◽  
Nuclear Genome ◽  
Selective Constraint ◽  
Drosophila Virilis ◽  
Nuclear Genes ◽  
Selective Constraints ◽  
Synonymous Sites ◽  
The Difference ◽  
Translational Level

Abstract The nuclear genes of Drosophila evolve at various rates. This variation seems to correlate with codon-usage bias. In order to elucidate the determining factors of the various evolutionary rates and codon-usage bias in the Drosophila nuclear genome, we compared patterns of codon-usage bias with base compositions of exons and introns. Our results clearly show the existence of selective constraints at the translational level for synonymous (silent) sites and, on the other hand, the neutrality or near neutrality of long stretches of nucleotide sequence within noncoding regions. These features were found for comparisons among nuclear genes in a particular species (Drosophila melanogaster, Drosophila pseudoobscura and Drosophila virilis) as well as in a particular gene (alcohol dehydrogenase) among different species in the genus Drosophila. The patterns of evolution of synonymous sites in Drosophila are more similar to those in the prokaryotes than they are to those in mammals. If a difference in the level of expression of each gene is a main reason for the difference in the degree of selective constraint, the evolution of synonymous sites of Drosophila genes would be sensitive to the level of expression among genes and would change as the level of expression becomes altered in different species. Our analysis verifies these predictions and also identifies additional selective constraints at the translational level in Drosophila.

Comparative analysis of codon usage patterns in SARS-CoV-2, its mutants and other respiratory viruses

2021 ◽  
Author(s):  
Neetu Tyagi ◽  
Rahila Sardar ◽  
Dinesh Gupta
Keyword(s):  
Codon Usage ◽  
Codon Usage Bias ◽  
Gc Content ◽  
Respiratory Illness ◽  
Respiratory Viruses ◽  
Nucleotide Composition ◽  
Health Crisis ◽  
Study Results ◽  
Usage Patterns ◽  
The Difference

AbstractThe Coronavirus disease 2019 (COVID-19) outbreak caused by Severe Acute Respiratory Syndrome Coronavirus 2 virus (SARS-CoV-2) poses a worldwide human health crisis, causing respiratory illness with a high mortality rate. To investigate the factors governing codon usage bias in all the respiratory viruses, including SARS-CoV-2 isolates from different geographical locations (~62K), including two recently emerging strains from the United Kingdom (UK), i.e., VUI202012/01 and South Africa (SA), i.e., 501.Y.V2 codon usage bias (CUBs) analysis was performed. The analysis includes RSCU analysis, GC content calculation, ENC analysis, dinucleotide frequency and neutrality plot analysis. We were motivated to conduct the study to fulfil two primary aims: first, to identify the difference in codon usage bias amongst all SARS-CoV-2 genomes and, secondly, to compare their CUBs properties with other respiratory viruses. A biased nucleotide composition was found as most of the highly preferred codons were A/U-ending in all the respiratory viruses studied here. Compared with the human host, the RSCU analysis led to the identification of 11 over-represented codons and 9 under-represented codons in SARS-CoV-2 genomes. Correlation analysis of ENC and GC3s revealed that mutational pressure is the leading force determining the CUBs. The present study results yield a better understanding of codon usage preferences for SARS-CoV-2 genomes and discover the possible evolutionary determinants responsible for the biases found among the respiratory viruses, thus unveils a unique feature of the SARS-CoV-2 evolution and adaptation. To the best of our knowledge, this is the first attempt at comparative CUBs analysis on the worldwide genomes of SARS-CoV-2, including novel emerged strains and other respiratory viruses.

scholarly journals Strong selection at the level of codon usage bias: evidence against the Li-Bulmer model

2017 ◽  
Author(s):  
Heather E. Machado ◽  
David S. Lawrie ◽  
Dmitri A. Petrov
Keyword(s):  
Codon Usage ◽  
Codon Usage Bias ◽  
Population Genetic ◽  
Genomic Sequencing ◽  
Weak Selection ◽  
Strong Selection ◽  
Genome Wide ◽  
Synonymous Sites ◽  
Dominant Paradigm ◽  
Wide Population

1AbstractCodon usage bias (CUB), where certain codons are used more frequently than expected by chance, is a ubiquitous phenomenon and occurs across the tree of life. The dominant paradigm is that the proportion of preferred codons is set by weak selection. While experimental changes in codon usage have at times shown large phenotypic effects in contrast to this paradigm, genome-wide population genetic estimates have supported the weak selection model. Here we use deep genomic sequencing of twoDrosophila melanogasterpopulations to measure selection on synonymous sites in a way that allowed us to estimate the prevalence of both weak and strong selection. We find that selection in favor of preferred codons ranges from weak (|Nes| ∼ 1) to strong (|Nes| > 10). While previous studies indicated that selection at synonymous sites could be strong, this is the first study to detect and quantify strong selection specifically at the level of CUB. We suggest that the level of CUB in the genome is determined by the proportion of synonymous sites under no, weak, and strong selection. This model challenges the standard Li-Bulmer model and explains some of the longest-standing puzzles in the field.

scholarly journals Codon Usage Bias of the Wheat Flower Development Gene WAG-2 and Other AGAMOUS Group Genes

2017 ◽  
Vol 9 (9) ◽  
pp. 56
Author(s):  
Wenhan Hu ◽  
Shuhong Wei
Keyword(s):  
Codon Usage ◽  
Codon Usage Bias ◽  
Codon Bias ◽  
Target Genes ◽  
Expression System ◽  
Functional Studies ◽  
Codon Preference ◽  
Synonymous Codons ◽  
The Difference ◽  
Relationship Of

Analyzing codon usage bias of WAG-2 gene in wheat three-pistil (TP) mutant may provide a basis for selecting the appropriate host expression systems to improve the expression of target genes. In the present study, we analyzed the codon bias of the complete coding sequence (CDS) of the WAG-2 gene in TP using Codon W program, and compared the results with AGAMOUS (AG) group genes of other plant species. Results showed that the WAG-2 gene in TP and other monocot AG group genes preferably used codons ending with G/C bases, but Arabidopsis thaliana, Nicotiana tabacum, and other dicot crops were biased toward the synonymous codons with A/T. The clustering results based on codon bias were consistent with those based on CDS of the AG group genes, indicating that the difference in codon preference of AG group genes sequences was closely associated with the genetic relationship of the species. The Euclidean distance coefficients of WAG-2 with A. thaliana and N. tabacum were 9.255 and 5.730, respectively, indicating that N. tabacum may be more suitable for the expression of WAG-2. There were 37 codons showing distinct usage differences between WAG-2 and genome of yeast, 23 between WAG-2 and Escherichia coli. Therefore, the E. coli was the superior protein expression system. These results may improve our understanding of codon usage bias and functional studies of WAG-2.

scholarly journals Pervasive Strong Selection at the Level of Codon Usage Bias in Drosophila melanogaster

Genetics ◽  
2019 ◽  
Vol 214 (2) ◽  
pp. 511-528 ◽  
Author(s):  
Heather E. Machado ◽  
David S. Lawrie ◽  
Dmitri A. Petrov
Keyword(s):  
Drosophila Melanogaster ◽  
Codon Usage ◽  
Codon Usage Bias ◽  
Purifying Selection ◽  
Weak Selection ◽  
Strong Selection ◽  
Genome Wide ◽  
Synonymous Sites ◽  
Alternatively Spliced ◽  
Splice Junctions

Codon usage bias (CUB), where certain codons are used more frequently than expected by chance, is a ubiquitous phenomenon and occurs across the tree of life. The dominant paradigm is that the proportion of preferred codons is set by weak selection. While experimental changes in codon usage have at times shown large phenotypic effects in contrast to this paradigm, genome-wide population genetic estimates have supported the weak selection model. Here we use deep genomic population sequencing of two Drosophila melanogaster populations to measure selection on synonymous sites in a way that allowed us to estimate the prevalence of both weak and strong purifying selection. We find that selection in favor of preferred codons ranges from weak (|Nes| ∼ 1) to strong (|Nes| > 10), with strong selection acting on 10–20% of synonymous sites in preferred codons. While previous studies indicated that selection at synonymous sites could be strong, this is the first study to detect and quantify strong selection specifically at the level of CUB. Further, we find that CUB-associated polymorphism accounts for the majority of strong selection on synonymous sites, with secondary contributions of splicing (selection on alternatively spliced genes, splice junctions, and spliceosome-bound sites) and transcription factor binding. Our findings support a new model of CUB and indicate that the functional importance of CUB, as well as synonymous sites in general, have been underestimated.

scholarly journals Rates of synonymous substitution and base composition of nuclear genes in Drosophila.

Genetics ◽  
1992 ◽  
Vol 130 (4) ◽  
pp. 855-864
Author(s):  
E N Moriyama ◽  
T Gojobori
Keyword(s):  
Nuclear Genome ◽  
Nuclear Gene ◽  
Synonymous Substitution ◽  
Selective Constraint ◽  
Nuclear Genes ◽  
Functional Genes ◽  
Silent Substitution ◽  
Codon Positions ◽  
Synonymous Substitution Rates ◽  
Mutation Pattern

Abstract We compared the rates of synonymous (silent) substitution among various genes in a number of species of Drosophila. First, we found that even for a particular gene, the rate of synonymous substitution varied considerably with Drosophila lineages. Second, we showed a large variation in synonymous substitution rates among nuclear genes in Drosophila. These rates of synonymous substitution were correlated negatively with C content and positively with A content at the third codon positions. Nucleotide sequences were also compared between pseudogenes and their functional homologs. The C content of the pseudogenes was lower than that of the functional genes and the A content of the former was higher than that of the latter. Because the synonymous substitution for functional genes and the nucleotide substitution for pseudogenes are exempted from any selective constraint at the protein level, these observations could be explained by a biased pattern of mutation in the Drosophila nuclear genome. Such a bias in the mutation pattern may affect the molecular clock (local clock) of each nuclear gene of each species. Finally, we obtained the average rates of synonymous substitution for three gene groups in Drosophila; 11.0 x 10(-9), 17.5 x 10(-9) and 27.1 x 10(-9)/site/year.

scholarly journals Patterns of genome-wide codon usage bias in tobacco, tomato and potato

2021 ◽  
Vol 35 (1) ◽  
pp. 657-664
Author(s):  
Ali Mostafa Anwar ◽  
Maha Aljabri ◽  
Mohamed El-Soda
Keyword(s):  
Codon Usage ◽  
Codon Usage Bias ◽  
Genome Wide

scholarly journals Codon usage bias and environmental adaptation in microbial organisms

2021 ◽  
Author(s):  
Davide Arella ◽  
Maddalena Dilucca ◽  
Andrea Giansanti
Keyword(s):  
Codon Usage ◽  
Codon Usage Bias ◽  
Pathogenic Bacteria ◽  
Large Scale ◽  
Synonymous Codon ◽  
Principal Component ◽  
Gene Copy ◽  
Phenotypic Traits ◽  
Translational Efficiency ◽  
Microbial Organisms

AbstractIn each genome, synonymous codons are used with different frequencies; this general phenomenon is known as codon usage bias. It has been previously recognised that codon usage bias could affect the cellular fitness and might be associated with the ecology of microbial organisms. In this exploratory study, we investigated the relationship between codon usage bias, lifestyles (thermophiles vs. mesophiles; pathogenic vs. non-pathogenic; halophilic vs. non-halophilic; aerobic vs. anaerobic and facultative) and habitats (aquatic, terrestrial, host-associated, specialised, multiple) of 615 microbial organisms (544 bacteria and 71 archaea). Principal component analysis revealed that species with given phenotypic traits and living in similar environmental conditions have similar codon preferences, as represented by the relative synonymous codon usage (RSCU) index, and similar spectra of tRNA availability, as gauged by the tRNA gene copy number (tGCN). Moreover, by measuring the average tRNA adaptation index (tAI) for each genome, an index that can be associated with translational efficiency, we observed that organisms able to live in multiple habitats, including facultative organisms, mesophiles and pathogenic bacteria, are characterised by a reduced translational efficiency, consistently with their need to adapt to different environments. Our results show that synonymous codon choices might be under strong translational selection, which modulates the choice of the codons to differently match tRNA availability, depending on the organism’s lifestyle needs. To our knowledge, this is the first large-scale study that examines the role of codon bias and translational efficiency in the adaptation of microbial organisms to the environment in which they live.

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