A Chromosome-Level Genome Assembly of the Non-Hematophagous Leech Whitmania pigra (Whitman 1884): Identification and Expression Analysis of Antithrombotic Genes.

Despite being a non-hematophagous leech, Whitmania pigra is widely used in traditional Chinese medicine for the treatment of antithrombotic diseases. In this study, we provide a high quality genome of W. pigra and based on which, we performed a systematic identification of the potential antithrombotic genes and their corresponding proteins. We identified twenty antithrombotic gene families including thirteen coagulation inhibitors, three platelet aggregation inhibitors, three fibrinolysis enhancers, and one tissue penetration enhancer. Unexpectedly, a total of 79 antithrombotic genes were identified, more than a typical blood-feeding Hirudinaria manillensis, which had only 72 antithrombotic genes. In addition, combining with the RNA-seq data of W. pigra and H. manillensis, we calculated the expression levels of antithrombotic genes of the two species. Five and four gene families had significantly higher and lower expression levels in W. pigra than in H. manillensis, respectively. These results showed that the number and expression level of antithrombotic genes of a non-hematophagous leech are not always less than those of a hematophagous leech. Our study provides the most comprehensive collection of antithrombotic biomacromolecules from a non-hematophagous leech to date and will significantly enhance the investigation and utilization of leech derivatives in thrombosis therapy research and pharmaceutical applications.

A new species of medicinal leech in the genus Hirudo Linnaeus, 1758 (Hirudiniformes, Hirudinidae) from Tianjin City, China.

Medicinal leeches in the genus Hirudo have been utilized for therapeutic procedures for thousands of years. To date, six known species of Hirudo are widely distributed in different regions of the Eurasian continent. In this study, a new medicinal leech species Hirudotianjinensis Liu, sp. nov. is described based upon specimens collected from Tianjin City, China. The new species can be distinguished from its congeners by a combination of characters: blackish green dorsum with five continuous yellow longitudinal stripes; six sensillae on dorsal annulus a2 of segments VIII-XXV; greyish green ventrum with irregular bilateral dark brown spots; dorsum and abdomen separated by a pair of pale yellow stripes; front half atrium wrapped by white prostate; apparent albumen gland; epididymis massive in relation to ejaculatory bulb. The phylogenetic tree based upon COI implies a sister relationship to H.nipponia Whitman, 1886. A key to the known species is provided.

Insights into gut microbiota communities of Poecilobdella manillensis, a prevalent Asian medicinal leech.

AIMS: Medicinal leeches (Annelida: Hirudinea) are fresh water ectoparasitic species which have been applied as traditional therapy. However, gut microbiota could bring high risks of opportunistic infections after leeching and arouses great interests. Here, gut bacterial and fungal communities of an Asian prevalent leech Poecilobdella manillensis were characterized and analysed through culture-independent sequencing. METHODS AND RESULTS: With high coverage in 18 samples (>0.999), a more complicated community was apparent after comparing with previous leech studies. A total of 779/939 OTUs of bacteria and fungi were detected from leech guts. The bacterial community was dominated by the phylum Bacteroidetes and Synergistetes. Genera Mucinivorans and Fretibacterium accounted mostly at the genus level, and genus Aeromonas showed an extremely low abundance (2.02%) on average. The fungal community was dominated by the phylum Ascomycota and Basidiomycota. At the genus level, the dominant OTUs included Mortierella, Geminibasidium and Fusarium. The analysis of core taxa included those above dominant genera and some low-abundance genera (>1%). The functional annotation of the bacterial community showed a close correlation with metabolism (34.8 ± 0.6%). Some fungal species were predicted as opportunistic human pathogens including Fusarium and Chaetomiaceae. CONCLUSIONS: The present study provides fundamental rationales for further studies of such issues as bacteria-fungi-host interactions, host fitness, potential pathogens, and infecting risks after leeching. It shall facilitate in-depth explorations on the safe utilization of leech therapy. SIGNIFICANCE AND IMPACT OF STUDY: Present paper is the first-ever exploration on microbiota of a prevalent Asian medicinal leech based on culture-independent technical. And it is also the first report of gut fungi community of medicinal leech. The diversity and composition of bacteria in P. manillensis was far different from that of the European leech. The main components and core OTUs indicate a particular gut environment of medicinal leech. Unknown bacterial and fungal species were also recovered from leech gut.

The genome of medicinal leech (Whitmania pigra) and comparative genomic study for exploration of bioactive ingredients.

BACKGROUND: Leeches are classic annelids that have a huge diversity and are 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. RESULTS: In 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 size. 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 patterns. Finally, we systematically explored and compared the active substances in the genomes of three leech species. The results showed that W. pigra and H. medicinalis exceed H. robusta in both kinds and gene number of active molecules. CONCLUSIONS: This 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.

De novo assembly and comparative transcriptome characterization of Poecilobdella javanica provide insight into blood feeding of medicinal leeches.

Leeches (family Hirudinidae) are classic model invertebrates used in diverse clinical treatments, such as reconstructive microsurgery, hypertension, and gangrene treatment. The blood-feeding habit is essential for these therapies, yet the molecular mechanisms underlying the process are poorly understood. In the present study, the transcriptome of Poecilobdella javanica from five time points (days 0, 1, 10, 20, and 30 separately) of blood feeding was sequenced with short paired-end reads. After stringent quality control, ∼380 million high-quality reads were assembled using SOAPdenovo-Trans with optimal parameters into a non-redundant set of 48 784 transcripts (≥100 base pairs), representing about 38 Mb of unique transcriptome sequence. The average length of the transcripts was 570 bp with N50 lengths of 5751 to 7413 bp among different time points. We have assessed the effect of sequence quality and various assembly parameters on the final assembly output. Functional categorization revealed the conservation of genes involved in various biological processes, such as basal transcription factors and ribosome biogenesis in eukaryotes. In addition, we found that DNA/RNA related pathways were predominantly expressed in the starving state while fatty acid metabolism, the anticoagulant pathway, and amino acid biosynthesis were activated during blood feeding. The leech transcriptome provides a resource for gene discovery and development of functional molecular markers during clinical applications.