Dataset Information

Comparative genomics of parasitic silkworm microsporidia reveal an association between genome expansion and host adaptation.

ABSTRACT:

Background

Microsporidian Nosema bombycis has received much attention because the pébrine disease of domesticated silkworms results in great economic losses in the silkworm industry. So far, no effective treatment could be found for pébrine. Compared to other known Nosema parasites, N. bombycis can unusually parasitize a broad range of hosts. To gain some insights into the underlying genetic mechanism of pathological ability and host range expansion in this parasite, a comparative genomic approach is conducted. The genome of two Nosema parasites, N. bombycis and N. antheraeae (an obligatory parasite to undomesticated silkworms Antheraea pernyi), were sequenced and compared with their distantly related species, N. ceranae (an obligatory parasite to honey bees).

Results

Our comparative genomics analysis show that the N. bombycis genome has greatly expanded due to the following three molecular mechanisms: 1) the proliferation of host-derived transposable elements, 2) the acquisition of many horizontally transferred genes from bacteria, and 3) the production of abundnant gene duplications. To our knowledge, duplicated genes derived not only from small-scale events (e.g., tandem duplications) but also from large-scale events (e.g., segmental duplications) have never been seen so abundant in any reported microsporidia genomes. Our relative dating analysis further indicated that these duplication events have arisen recently over very short evolutionary time. Furthermore, several duplicated genes involving in the cytotoxic metabolic pathway were found to undergo positive selection, suggestive of the role of duplicated genes on the adaptive evolution of pathogenic ability.

Conclusions

Genome expansion is rarely considered as the evolutionary outcome acting on those highly reduced and compact parasitic microsporidian genomes. This study, for the first time, demonstrates that the parasitic genomes can expand, instead of shrink, through several common molecular mechanisms such as gene duplication, horizontal gene transfer, and transposable element expansion. We also showed that the duplicated genes can serve as raw materials for evolutionary innovations possibly contributing to the increase of pathologenic ability. Based on our research, we propose that duplicated genes of N. bombycis should be treated as primary targets for treatment designs against pébrine. The genome data and annotation information of N. bombycis and N.antheraeae were submitted to GenBank (Accession numbers ACJZ01000001 -ACJZ01003558).

SUBMITTER: Pan G

PROVIDER: S-EPMC3614468 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature

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Publications

Comparative genomics of parasitic silkworm microsporidia reveal an association between genome expansion and host adaptation.

Pan Guoqing G Xu Jinshan J Li Tian T Xia Qingyou Q Liu Shao-Lun SL Zhang Guojie G Li Songgang S Li Chunfeng C Liu Handeng H Yang Liu L Liu Tie T Zhang Xi X Wu Zhengli Z Fan Wei W Dang Xiaoqun X Xiang Heng H Tao Meilin M Li Yanhong Y Hu Junhua J Li Zhi Z Lin Lipeng L Luo Jie J Geng Lina L Wang LinLing L Long Mengxian M Wan Yongji Y He Ningjia N Zhang Ze Z Lu Cheng C Keeling Patrick J PJ Wang Jun J Xiang Zhonghuai Z Zhou Zeyang Z

BMC genomics 20130316

<h4>Background</h4>Microsporidian Nosema bombycis has received much attention because the pébrine disease of domesticated silkworms results in great economic losses in the silkworm industry. So far, no effective treatment could be found for pébrine. Compared to other known Nosema parasites, N. bombycis can unusually parasitize a broad range of hosts. To gain some insights into the underlying genetic mechanism of pathological ability and host range expansion in this parasite, a comparative genomi ...[more]

PMID: 23496955

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Project description:BackgroundDiversity of hair in marine mammals was suggested as an evolutionary innovation to adapt aquatic environment, yet its genetic basis remained poorly explored. We scanned α-keratin genes, one major structural components of hair, in 16 genomes of mammalian species, including seven cetaceans, two pinnipeds, polar bear, manatee and five terrestrial species.ResultsExtensive gene loss and high pseudogenization rate of α-keratin genes were identified in cetaceans when compared to terrestrial artiodactylans (average number of α-keratins 37.29 vs. 58.33; pseudogenization rate 29.89% vs. 8.00%), especially of hair follicle-specific keratin genes (average pseudogenization rate in cetaceans of 43.88% relative to 3.80% artiodactylian average). Compared to toothed whale, the much more number of intact functional α-keratin genes was examined in the baleen whale that had specific keratinized baleen. In contrast, the number of keratin genes in pinnipeds, polar bear and manatee were comparable to those of their respective terrestrial relatives. Additionally, four keratin genes (K39, K9, K42, and K74) were found to be pseudogenes or lost uniquely in cetaceans and manatees.ConclusionsSpecies-specific evolution of α-keratin gene family identified in the marine mammals might be responsible for their different hair characteristics. Increased gene loss and pseudogenization rate identified in cetacean lineages was likely to contribute to hair-less phenotype to adaptation for complete aquatic environment. However, the fully aquatic manatee still remained the comparable number of intact genes to its terrestrial relative, probably due to its perioral bristles and bristle-like hairs on the oral disk. By contrast, similar evolution pattern of α-keratin gene repertoire in the pinnipeds, polar bear and their terrestrial relatives was likely due to abundant hair to keep warm when they went ashore. Interestingly, some keratin genes were exclusively lost in cetaceans and manatees, likely as a result of convergent hair-loss phenotype to inhabit completely aquatic environment in both groups.

Dataset Information

Comparative genomics of parasitic silkworm microsporidia reveal an association between genome expansion and host adaptation.

Background

Results

Conclusions

Publications

Comparative genomics of parasitic silkworm microsporidia reveal an association between genome expansion and host adaptation.

Similar Datasets

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