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Bacterial symbiont and salivary peptide evolution in the context of leech phylogeny

Published online by Cambridge University Press:  10 May 2011

MARK E. SIDDALL ,
GI-SIK MIN ,
FRANK M. FONTANELLA ,
ANNA J. PHILLIPS  and
SARA C. WATSON
MARK E. SIDDALL*
Affiliation:
Sackler Institute of Comparative Genomics & Division of Invertebrate Zoology, American Museum of Natural History, New York, NY, USA
GI-SIK MIN
Affiliation:
Department of Biological Sciences, Inha University, Yonghyun-dong, Nam-Gu, Incheon 402-751, Korea
FRANK M. FONTANELLA
Affiliation:
Department of Biology, Brigham Young University, Provo, UT 84602, USA
ANNA J. PHILLIPS
Affiliation:
Sackler Institute of Comparative Genomics & Division of Invertebrate Zoology, American Museum of Natural History, New York, NY, USA Department of Biology, The Graduate Center, The City University of New York, New York, NY, USA
SARA C. WATSON
Affiliation:
Sackler Institute of Comparative Genomics & Division of Invertebrate Zoology, American Museum of Natural History, New York, NY, USA
*
*Corresponding author: Mark E Siddall. E-mail: siddall@amnh.org
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Summary

The evolutionary history of leeches is employed as a general framework for understanding more than merely the systematics of this charismatic group of annelid worms, and serves as a basis for understanding blood-feeding related correlates ranging from the specifics of gut-associated bacterial symbionts to salivary anticoagulant peptides. A variety of medicinal leech families were examined for intraluminal crop bacterial symbionts. Species of Aeromonas and Bacteroidetes were characterized with DNA gyrase B and 16S rDNA. Bacteroidetes isolates were found to be much more phylogenetically diverse and suggested stronger evidence of phylogenetic correlation than the gammaproteobacteria. Patterns that look like co-speciation with limited taxon sampling do not in the full context of phylogeny. Bioactive compounds that are expressed as gene products, like those in leech salivary glands, have ‘passed the test’ of evolutionary selection. We produced and bioinformatically mined salivary gland EST libraries across medicinal leech lineages to experimentally and statistically evaluate whether evolutionary selection on peptides can identify structure-function activities of known therapeutically relevant bioactive compounds like antithrombin, hirudin and antistasin. The combined information content of a well corroborated leech phylogeny and broad taxonomic coverage of expressed proteins leads to a rich understanding of evolution and function in leech history.

Keywords

Leechesphylogenymicrobiologyprotein evolution
Type
Research Article
Information
Parasitology , Volume 138 , Special Issue 13: Systematics as a cornerstone of parasitology , November 2011 , pp. 1815 - 1827
Copyright
Copyright © Cambridge University Press 2011

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