Project description:Here, we report the use of Illumina RNA-Seq for investigating the physiology of the digestive-tract microbiome within the medicinal leech, Hirudo verbana. About 12 million cDNA reads were mapped against the genomes of the two dominant members of this simple microbiome. Results suggested that the most abundant, yet uncultured Rikenella-like bacterium forages host mucin glycans and ferments the carbohydrates to acetate that is secreted into the environment. The second dominant symbiont, Aeromonas veronii, appears to utilize the acetate secreted by Rikenella as a carbon and energy source, possibly linking the physiologies of the dominant symbionts. This study demonstrates how RNA-seq can be used to reveal the physiology of a naturally occurring microbiome.
Project description:The European medicinal leech has been used for medicinal purposes for millennia, and continues to be used today in modern hospital settings. Its utility is granted by the extremely potent anticoagulation factors that the leech secretes into the incision wound during feeding and, although a handful of studies have targeted certain anticoagulants, the full range of anticoagulation factors expressed by this species remains unknown. Here, we present the first draft genome of the European medicinal leech, Hirudo medicinalis, and estimate that we have sequenced between 79-94% of the full genome. Leveraging these data, we searched for anticoagulation factors across the genome of H. medicinalis. Following orthology determination through a series of BLAST searches, as well as phylogenetic analyses, we estimate that fully 15 different known anticoagulation factors are utilized by the species, and that 17 other proteins that have been linked to antihemostasis are also present in the genome. We underscore the utility of the draft genome for comparative studies of leeches and discuss our results in an evolutionary context.
Project description:BACKGROUND:Salivary cell secretion (SCS) plays a critical role in blood feeding by medicinal leeches, making them of use for certain medical purposes even today. RESULTS:We annotated the Hirudo medicinalis genome and performed RNA-seq on salivary cells isolated from three closely related leech species, H. medicinalis, Hirudo orientalis, and Hirudo verbana. Differential expression analysis verified by proteomics identified salivary cell-specific gene expression, many of which encode previously unknown salivary components. However, the genes encoding known anticoagulants have been found to be expressed not only in salivary cells. The function-related analysis of the unique salivary cell genes enabled an update of the concept of interactions between salivary proteins and components of haemostasis. CONCLUSIONS:Here we report a genome draft of Hirudo medicinalis and describe identification of novel salivary proteins and new homologs of genes encoding known anticoagulants in transcriptomes of three medicinal leech species. Our data provide new insights in genetics of blood-feeding lifestyle in leeches.
Project description:In this study we used Illumina RNA-seq to identify genes expressed by A. veronii in mid-log phase growth in a rich medium and within the digestive tract of the medicinal leech. Our results shed light on the physiology of A. veronii during colonization of the leech gut.