The Genome of Medicinal Leech (Whitmania pigra) and comparative genomic study for Exploration of Bioactive Ingredients

Abstract

BackgroundLeeches are classic annelids that have a huge diversity and closely related to people, especially medicinal leeches. Medicinal leeches have been widely utilized in medicine based on the pharmacological activities of their bioactive ingredients. Comparative genomic study of these leeches enables us to understand the difference among medicinal leeches and other leeches and facilitates the discovery of bioactive ingredients.ResultsIn this study, we reported the genome of Whitmania pigra and compared it with Hirudo medicinalis and Helobdella robusta. The assembled genome size of W. pigra is 177 Mbp, close to the estimated genome. Approximately about 23% of the genome was repetitive. A total of 26,743 protein-coding genes were subsequently predicted. W. pigra have 12346 (46%) and 10295 (38%) orthologous genes with H. medicinalis and H. robusta, respectively. About 20% and 24% genes in W. pigra showed syntenic arrangement with H. medicinalis and H. robusta, respectively, revealed by gene synteny analysis. Furthermore, W. pigra, H. medicinalis and H. robusta expanded different gene families enriched in different biological processes. By inspecting genome distribution and gene structure of hirudin, we identified a new hirudin gene g17108 (hirudin_2) with different cysteine pattern. Finally, we systematically explored and compared the active substances in the genomes of three leeches. The results showed that W. pigra and H. medicinalis exceed H. robusta in both kinds and gene number of active molecules.ConclusionsThis study reported the genome of W. pigra and compared it with other two leeches, which provides an important genome resource and new insight into the exploration and development of bioactive molecules of medicinal leeches.

Life without blood: Molecular and functional analysis of hirudins and hirudin‐like factors of the Asian non‐hematophagous leech Whitmania pigra

“…We identified and subsequently functionally characterized six variants of putative hirudins/HLFs: Wpig_V1‐V6. The variant Wpig_V6 is almost identical to hirudin_1 in the draft genome of Whitmania pigra 22 and to Wpig_hirudin 20 ; GenBank Acc. No.…”

“…Yao et al 21 described the antithrombotic effect of an aqueous extract of Whitmania pigra , but denied the presence of hirudin. In a yet unpublished manuscript Tong et al 22 report on a draft genome of Whitmania pigra including the identification of two putative hirudin‐encoding genes, one complete (hirudin_1) and the other incomplete (hirudin_2). Hirudin_1 is identical to Wpig_hirudin mentioned above.…”