Abstract

Analysis of codon usage bias (CUB) is very much important in perceiving the knowledge of molecular biology, the discovery of a new gene, designing of transgenes and evolution of gene. In this study, we analyzed compositional features and codon usage of MT-CO (COI, COII and COIII) genes among the classes of Arthropoda to explore the pattern of CUB as no research work was reported yet. Nucleotide composition analysis in CO genes suggested that the genes were AT-rich in all the four classes of Arthropoda. CUB was low in all the classes of Arthropoda for MT-CO genes as revealed from a high effective number of codons (ENC). We also found that the evolutionary forces namely mutation pressure and natural selection were the key influencing factors in CUB among MT-CO genes as revealed by correlation analysis between overall nucleotide composition and nucleotide composition at the 3rd codon position. Correspondence analysis suggested that the pattern of CUB was different among the classes of Arthropoda. Further, it was revealed from the neutrality plot that natural selection had a dominant role while mutation pressure exhibited a minor role in structuring the pattern of codon usage in all the classes of Arthropoda across COI, COII and COIII genes.

摘要

密码子使用偏倚（CUB）的分析对于了解分子生物学知识，发现新基因，设计转基因和基因进化非常重要。在这项研究中，我们分析了节肢动物类中MT-CO（COI，COII和COIII）基因的组成特征和密码子使用，以探索CUB的模式，因为尚未有研究工作被报道。CO基因中的核苷酸组成分析表明，在所有四类节肢动物中，这些基因富含AT。在MT-CO的所有节肢动物类中，CUB都很低从高有效密码子（ENC）中揭示的基因。我们还发现，进化力即突变压力和自然选择是MT-CO基因中CUB的关键影响因素，这是通过整体核苷酸组成与第3个密码子位置的核苷酸组成之间的相关性分析揭示的。对应分析表明，节肢动物类的CUB模式不同。此外，从中性图揭示，自然选择在COI，COII和COIII基因的所有节肢动物类中，在构造节肢动物的所有密码子使用模式中起着次要作用，而突变压力显示出次要作用。