The Anopheles gambiae salivary protein gSG6: An anopheline-specific protein with a blood-feeding role

Abstract

The Anopheles gambiae salivary gland protein 6 (gSG6) is a small protein specifically found in the salivary glands of adult female mosquitoes. We report here the expression of a recombinant form of the protein and we show that in vivo gSG6 is expressed in distal-lateral lobes and is secreted with the saliva while the female mosquito probes for feeding. Injection of gSG6 dsRNA into adult An. gambiae females results in decreased gSG6 protein levels, increased probing time and reduced blood feeding ability. gSG6 orthologs have been found so far only in the salivary glands of Anopheles stephensi and Anopheles funestus, both members of the Cellia subgenus. We report here the gSG6 sequence from five additional anophelines, four species of the An. gambiae complex and Anopheles freeborni, a member of the subgenus Anopheles. We conclude that gSG6 plays some essential blood feeding role and was recruited in the anopheline subfamily most probably after the separation of the lineage which gave origin to Cellia and Anopheles subgenera.

Collagen-binding protein, Aegyptin, regulates probing time and blood feeding success in the dengue vector mosquito, Aedes aegypti

“…Instead they perform complementary functions to optimize successful feeding. Our data and conclusions are supported further by data on the partial silencing of salivary apyrase and gSG6 genes in A. gambiae, which resulted in reduced mosquito feeding efficiency (33,34). Finally, our results support transgenic approaches for studies of gain and loss of salivary functions.…”

Analysis of female salivary gland proteins of the Anopheles barbirostris complex (Diptera: Culicidae) in Thailand

“…This result does not correlate with an observation that gSG6 is conserved in five species members of the A. gambiae complex, i.e., A. gambiae, Anopheles melas, Anopheles bwambae, Anopheles quadriannulatus A, and Anopheles arabiensis (Lombardo et al 2009). The gSG6 protein was originally identified in A. gambiae in the form of a transcript specifically expressed in adult female salivary glands and predicted to encode a small secretory protein (Lanfrancotti et al 2002).…”

“…The corresponding 10 kDa protein was highly expressed in the salivary glands of adult females (Francischetti et al 2002). Lombardo et al (2009) demonstrated that gSG6 was expressed in distallateral lobes and secreted with the saliva while the female mosquito probes for feeding. Injection of gSG6 dsRNA into adult A. gambiae females resulted in decreased gSG6 protein levels, increased probing time and reduced bloodfeeding ability.…”

“…The authors concluded that gSG6 plays some essential blood-feeding role in female mosquitoes. gSG6 orthologs have been found so far in A. freeborni (subgenus Anopheles), the five species members of A. gambiae complex, A. stephensi, and Anopheles funestus (subgenus Cellia; Lombardo et al 2009). But gSG6 orthologs have not been retrieved in the transcriptomes of the Culicinae subfamily members, i.e., Culex pipiens Ribeiro et al 2004Ribeiro et al , 2007.…”

“…The distribution of specific proteins in the different morphological regions of female salivary glands has been described in various mosquitoes, for example, A. gambiae (Brennan et al 2000;Lombardo et al 2009), A. stephensi (Suwan et al 2002), and Anopheles cracens (formerly A. dirus B, Jariyapan et al 2007). The protein profiles of the A. barbirostris complex in different salivary gland lobes showed similar distribution patterns to other Anopheles mosquitoes.…”