The salivary gland transcriptome of the neotropical malaria vector Anopheles darlingi reveals accelerated evolution of genes relevant to hematophagy.
BACKGROUND
Mosquito saliva, consisting of a mixture of dozens of proteins affecting vertebrate hemostasis and having sugar digestive and antimicrobial properties, helps both blood and sugar meal feeding. Culicine and anopheline mosquitoes diverged ~150 MYA, and within the anophelines, the New World species diverged from those of the Old World ~95 MYA. While the sialotranscriptome (from the Greek sialo, saliva) of several species of the Cellia subgenus of Anopheles has been described thoroughly, no detailed analysis of any New World anopheline has been done to date. Here we present and analyze data from a comprehensive salivary gland (SG) transcriptome of the neotropical malaria vector Anopheles darlingi (subgenus Nyssorhynchus).


RESULTS
A total of 2,371 clones randomly selected from an adult female An. darlingi SG cDNA library were sequenced and used to assemble a database that yielded 966 clusters of related sequences, 739 of which were singletons. Primer extension experiments were performed in selected clones to further extend sequence coverage, allowing for the identification of 183 protein sequences, 114 of which code for putative secreted proteins.


CONCLUSIONS
Comparative analysis of sialotranscriptomes of An. darlingi and An. gambiae reveals significant divergence of salivary proteins. On average, salivary proteins are only 53% identical, while housekeeping proteins are 86% identical between the two species. Furthermore, An. darlingi proteins were found that match culicine but not anopheline proteins, indicating loss or rapid evolution of these proteins in the old world Cellia subgenus. On the other hand, several well represented salivary protein families in old world anophelines are not expressed in An. darlingi.
Calvo
Eric
E
Section of Vector Biology, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, NIH, Rockville, MD 20852, USA. eric.calvo@fda.hhs.gov
Pham
Van M
VM
Marinotti
Osvaldo
O
Andersen
John F
JF
Ribeiro
José M C
JM
D000595:Amino Acid Sequence; D000818:Animals; D000852:Anopheles / Q000235:genetics*; D016000:Cluster Analysis; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D005260:Female; D020869:Gene Expression Profiling; D015723:Gene Library; D017344:Genes, Insect; D008969:Molecular Sequence Data; D012469:Salivary Glands / Q000378:metabolism*; D012471:Salivary Proteins and Peptides / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D012471:Salivary Proteins and Peptides