Genetic signature of strong recent positive selection at interleukin-32 gene in goat.

OBJECTIVE

Identification of the candidate genes that play key roles in phenotypic variations can provide new information about evolution and positive selection. Interleukin (IL)-32 is involved in many biological processes, however, its role for the immune response against various diseases in mammals is poorly understood. Therefore, the current investigation was performed for the better understanding of the molecular evolution and the positive selection of single nucleotide polymorphisms in gene.

METHODS

By using fixation index ( ) based method, (9375) gene was found to be outlier and under significant positive selection with the provisional combined allocation of mean heterozygosity and . Using nucleotide sequences of 11 mammalian species from National Center for Biotechnology Information database, the evolutionary selection of gene was determined using Maximum likelihood model method, through four models (M1a, M2a, M7, and M8) in Codeml program of phylogenetic analysis by maximum liklihood.

RESULTS

IL-32 is detected under positive selection using the simulations method. The phylogenetic tree revealed that goat IL-32 was in close resemblance with sheep IL-32. The coding nucleotide sequences were compared among 11 species and it was found that the goat gene shared identity with sheep (96.54%), bison (91.97%), camel (58.39%), cat (56.59%), buffalo (56.50%), human (56.13%), dog (50.97%), horse (54.04%), and rabbit (53.41%) respectively.

CONCLUSION

This study provides evidence for gene as under significant positive selection in goat.