Widespread gene duplication and adaptive evolution in the RNA interference pathways of the Drosophila obscura group

BioRxiv : the Preprint Server for Biology
Danang Crysnanto, Darren J Obbard

Abstract

Background: RNA interference (RNAi) related pathways provide defense against viruses and transposable elements, and have been implicated in the suppression of meiotic drive elements. Genes in these pathways often exhibit high levels of adaptive substitution, and over longer timescales show gene duplication and los--most likely as a consequence of their role in mediating conflict with these parasites. This is particularly striking for Argonaute 2 (Ago2) , which is ancestrally the key effector of antiviral RNAi in insects, but has repeatedly formed new testis-specific duplicates in the recent history of the obscura species-group of Drosophila . Results: Here we take advantage of publicly available genomic and transcriptomic data to identify six further RNAi-pathway genes that have duplicated in this clade of Drosophila, and examine their evolutionary history. As seen for Ago2 , we observe high levels of adaptive amino-acid substitution and changes in sex-biased expression in many of the paralogs. However, our phylogenetic analysis suggests that co-duplications of the RNAi machinery were not synchronous, and our expression analysis fails to identify consistent male-specific expression. Conclusions: These results confirm that RNAi ...Continue Reading

Related Concepts

Meiotic Cell Cycle
Biochemical Pathway
Benign Neoplasm of Testis
AGO2 gene
Virus
Genome
Genes
EIF2C2 protein, human
Neoplasm of Uncertain or Unknown Behavior of Testis
Drosophila obscura

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