Multiple ancient horizontal gene transfers and duplications in lepidopteran species

Abstract

Eukaryotic horizontal gene transfer (HGT) events are increasingly being discovered yet few reports have summarized multiple occurrences in a wide range of species. We systematically investigated HGT events in the order Lepidoptera by employing a series of filters. Bombyx mori, Danaus plexippus and Heliconius melpomene had 13, 12 and 12 HGTs, respectively, from bacteria and fungi. These HGTs contributed a total of 64 predicted genes: 22 to B. mori, 22 to D. plexippus and 20 to H. melpomene. Several new genes were generated by post-transfer duplications. Post-transfer duplication of a suite of functional HGTs has rarely been reported in higher organisms. The distributional patterns of paralogues for certain genes differed in the three species, indicating potential independent duplication or loss events. All of these HGTs had homologues expressed in some other lepidopterans, indicating ancient transfer events. Most HGTs were involved in the metabolism of sugar and amino acids. These HGTs appeared to have experienced amelioration, purifying selection and accelerated evolution to adapt to the background genome of the recipient. The discovery of ancient, massive HGTs and duplications in lepidopterans and their adaptive evolution provides further insights into the evolutionary significance of the events from donors to multicellular host recipients.

Caterpillars lack a resident gut microbiome

“…Some insects likely require microbes for detoxification (16), but many caterpillars possess host-encoded mechanisms for degrading or tolerating plant allelochemicals (72). However, there may be a vestigial role for microbes in these processes, as genomes of many Lepidoptera contain microbial genes encoding enzymes with related functions (73,74). These gene acquisitions may have enabled a symbiont-free feeding strategy.…”

A gene horizontally transferred from bacteria protects arthropods from host plant cyanide poisoning

“…In Lepidoptera, the CAS gene was subsequently duplicated in H. melpomene and D. plexippus that have 3 and 2 copies of the gene, respectively (Sun et al, 2013). The importance of the laterally acquired gene for HCN detoxification in those species was not previously apparent.…”

The Biology of CNAPS

“…Nevertheless, if such cfNA could enter the gonads, then this could offer a mechanism for horizontal gene transfer (HGT) to operate, HGT involving the movement of genes from one organism to another. Although HGT has been identified to occur in lower organisms such as bdelloid rotifers [164] or Lepidoptera [165] currently, there is no such evidence for eutherians including man. This is likely to be prevented through the presence of the distinct germ cell line being separate from the soma [166].…”