title: Comparative Transcriptomic Analyses of Three Species of Placobdella (Rhynchobdellida: Glossiphoniidae) Confirms a Single Origin of Blood Feeding in Leeches.
abstract: One of the recalcitrant questions regarding the evolutionary history of clitellate annelids involves the feeding preference of the common ancestor of extant rhynchobdellid (proboscis bearing) and arhynchobdellid (jaw bearing) leeches. Whereas early evidence, based on morphological data, pointed towards independent acquisitions of blood feeding in the 2 orders, molecular-based phylogenetic data suggest that the ancestor of modern leeches was a sanguivore. Here, we use a comparative transcriptomic approach in order to increase our understanding of the diversity of anticoagulation factors for 3 species of the genus Placobdella, for which comparative data have been lacking, and inspect these in light of archetypal anticoagulant data for both arhynchobdellid and other rhynchobdellid species. Notwithstanding the varying levels of host specificity displayed by the 3 different species of Placobdella, transcriptomic profiles with respect to anticoagulation factors were largely similar -this despite the fact that Placobdella kwetlumye only retains a single pair of salivary glands, as opposed to the 2 pairs more common in the genus. Results show that 9 different anticoagulant proteins and an additional 5 putative antihemostasis proteins are expressed in salivary secretions of the 3 species. In particular, an ortholog of the archetypal, single-copy, anticoagulant hirudin (not previously available as comparative data for rhynchobdellids) is present in at least 2 of 3 species examined, corroborating the notion of a single origin of blood feeding in the ancestral leech.
authors.affiliation: Sackler Institute for Comparative Genomics, and Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Siddall
authors.affiliation: Sackler Institute for Comparative Genomics, and Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024.
authors.forename: Mercer R
authors.initials: MR
authors.lastname: Brugler
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kvist
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000925:Anticoagulants / Q000502:physiology; D001483:Base Sequence; D018076:DNA, Complementary / Q000096:biosynthesis / Q000737:chemistry; D020869:Gene Expression Profiling; D015723:Gene Library; D006629:Hirudins / Q000235:genetics / Q000502:physiology; D007865:Leeches / Q000235:genetics / Q000502:physiology*; D016366:Open Reading Frames / Q000235:genetics; D011499:Protein Processing, Post-Translational / Q000502:physiology; D021382:Protein Sorting Signals / Q000502:physiology; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D016415:Sequence Alignment
chemical_list: D000925:Anticoagulants; D018076:DNA, Complementary; D006629:Hirudins; D021382:Protein Sorting Signals; D012313:RNA