Characterization of an Ancient Lepidopteran Lateral Gene Transfer

Abstract

Bacteria to eukaryote lateral gene transfers (LGT) are an important potential source of material for the evolution of novel genetic traits. The explosion in the number of newly sequenced genomes provides opportunities to identify and characterize examples of these lateral gene transfer events, and to assess their role in the evolution of new genes. In this paper, we describe an ancient lepidopteran LGT of a glycosyl hydrolase family 31 gene (GH31) from an Enterococcus bacteria. PCR amplification between the LGT and a flanking insect gene confirmed that the GH31 was integrated into the Bombyx mori genome and was not a result of an assembly error. Database searches in combination with degenerate PCR on a panel of 7 lepidopteran families confirmed that the GH31 LGT event occurred deep within the Order approximately 65–145 million years ago. The most basal species in which the LGT was found is Plutella xylostella (superfamily: Yponomeutoidea). Array data from Bombyx mori shows that GH31 is expressed, and low dN/dS ratios indicates the LGT coding sequence is under strong stabilizing selection. These findings provide further support for the proposition that bacterial LGTs are relatively common in insects and likely to be an underappreciated source of adaptive genetic material.

Horizontal gene transfer in the acquisition of novel traits by metazoans

“…The examples discussed above (and two recent reports showing multiple ancient horizontal gene transfers from bacteria and fungi to the genomes of different lepidopteran species [61,62] and the genome of the crustacean Litopenaeus vannamei [63]) show that horizontal gene transfer in arthropods is no longer a curiosity and that more accurate screening of arthropod genomes and transcriptomes will surely unveil more evidence supporting the horizontal acquisition of genes in these metazoans.…”

A novel intracellular mutualistic bacterium in the invasive antCardiocondyla obscurior

“…During analyses of the C. obscurior genome (Schrader et al, 2014), we identified prokaryotic scaffolds and candidates for horizontal gene transfers (HGTs) (Wheeler et al, 2013). These were then further characterized by blasting (blastx) all annotated genes against a database of prokaryotic proteins.…”

Host and symbiont jointly control gut microbiota during complete metamorphosis

“…Here we exploit an ancient [19], facultative and prevalent [20][21][22][23][24][25][26] symbiosis between Lepidoptera and enterococci to reconcile these approaches by studying the role of host immunity and bacterial competition during metamorphosis within a single system. The gut microbiota of Lepidoptera is limited to a handful of bacterial species that varies with habitat and diet but often is dominated by enterococci that persist through metamorphosis [12].…”