Comparative Analysis of Codon Usage Bias Between Two Lepidopteran Insect Species: Bombyx Mandarina and Ostrinia Furnacalis

JYOTIKA SHARMA; SUPRIYO CHAKRABORTY; ARIF UDDIN

Volume : III, Issue : VI, June - 2014

Comparative Analysis of Codon Usage Bias Between Two Lepidopteran Insect Species: Bombyx Mandarina and Ostrinia Furnacalis

Jyotika Sharma, Supriyo Chakraborty, Arif Uddin

Abstract :

Background: Codon usage bias is the unequal use of synonymous codons; some codons are more preferred than others. However codon usage pattern is different among genes and among organisms. The bias is found more often in highly expressed genes. The greatest diversity of insects among the animal kingdom makes insects appropriate for codon bias study at variable evolutionary time scales. Result and Discussion: we analyzed pattern of codon usage in two insect species of Lepidopteran order. The ENC values range from 51 to 60 with a mean value of 57.75 in B. mandarina but from 52 to 60 with a mean value of 57.17 in O. furnacalis, respectively. In B. mandarina, a significant positive correlation was observed between A% and A3% (r = 0.608**, p < 0.01), C% and C3 % (r = 844**, p < 0.01), GC% and GC3 % (r = 0.818**, p < 0.01 ) and significant negative correlation observed between the most of heterogeneous nucleotide comparisons; A% and GC3% ( r = -0.641** p<0.01 ), T% and G3% (r = -0.311 p>0.05), T % and C3 % ( r = - 0.871**p<0.01). In O. furnacalis , a significant positive correlation was observed between A% and A3 % (r = 0.892**p<0.01), C% and C3% (r = 0.974** p<0.01), GC% and GC3% (r = 0.895** p<0.01) and significant negative correlation observed between the most of heterogeneous nucleotide comparisons; A % and GC3 % (r = -0.791** p<0.01 ), T% and G3%( r = -0.486* p<0.05), T% and C3 %( r = - 0.900** p<0.01 ). These results suggest that compositional constraint under mutation pressure has contributed the pattern of codon usage bias in these two insect species of the order Lepidoptera. Conclusion: Codon usage bias was not very remarkable in these species. Nucleotide constraint and compositional constraint are significant factors that affect codon usage pattern in these species. The most frequent codons end with C at the 3rd position, most probably suggesting the role of the compositional constraint under mutation pressure. We find that mutation pressure is the main factor for the pattern of codon usage bias in these Lepidopteran species.