An insight into the sialotranscriptome of the cat flea, Ctenocephalides felis.
BACKGROUND
Saliva of hematophagous arthropods contains a diverse mixture of compounds that counteracts host hemostasis. Immunomodulatory and antiinflammatory components are also found in these organisms' saliva. Blood feeding evolved at least ten times within arthropods, providing a scenario of convergent evolution for the solution of the salivary potion. Perhaps because of immune pressure from hosts, the salivary proteins of related organisms have considerable divergence, and new protein families are often found within different genera of the same family or even among subgenera. Fleas radiated with their vertebrate hosts, including within the mammal expansion initiated 65 million years ago. Currently, only one flea species-the rat flea Xenopsylla cheopis-has been investigated by means of salivary transcriptome analysis to reveal salivary constituents, or sialome. We present the analysis of the sialome of cat flea Ctenocephaides felis.
A salivary gland cDNA library from adult fleas was randomly sequenced, assembled, and annotated. Sialomes of cat and rat fleas have in common the enzyme families of phosphatases (inactive), CD-39-type apyrase, adenosine deaminases, and esterases. Antigen-5 members are also common to both sialomes, as are defensins. FS-I/Cys7 and the 8-Cys families of peptides are also shared by both fleas and are unique to these organisms. The Gly-His-rich peptide similar to holotricin was found only in the cat flea, as were the abundantly expressed Cys-less peptide and a novel short peptide family.


CONCLUSIONS
Fleas, in contrast to bloodsucking Nematocera (mosquitoes, sand flies, and black flies), appear to concentrate a good portion of their sialome in small polypeptides, none of which have a known function but could act as inhibitors of hemostasis or inflammation. They are also unique in expansion of a phosphatase family that appears to be deficient of enzyme activity and has an unknown function.
Vector Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, USA. jribeiro@niaid.nih.gov
José M C
JM
Ribeiro
Teresa C F
TC
Assumpção
Dongying
D
Ma
Patricia H
PH
Alvarenga
Van M
VM
Pham
John F
JF
Andersen
Ivo M B
IM
Francischetti
Kevin R
KR
Macaluso
D000595:Amino Acid Sequence; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects; D002415:Cats; D003029:Coagulants / Q000737:chemistry / Q000494:pharmacology; D058251:Ctenocephalides / Q000235:genetics*; D020869:Gene Expression Profiling; D015723:Gene Library; D008969:Molecular Sequence Data; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000494:pharmacology; D010802:Phylogeny; D051381:Rats; D012463:Saliva / Q000737:chemistry / Q000378:metabolism*; D012469:Salivary Glands / Q000737:chemistry / Q000378:metabolism*; D012471:Salivary Proteins and Peptides / Q000235:genetics* / Q000494:pharmacology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D059467:Transcriptome / Q000235:genetics*; D058260:Xenopsylla / Q000235:genetics
D000893:Anti-Inflammatory Agents; D003029:Coagulants; D012471:Salivary Proteins and Peptides; D010744:Phosphoric Monoester Hydrolases