The salivary transcriptome of Anopheles gambiae (Diptera: Culicidae) larvae: A microarray-based analysis

Abstract

In spite of the many recent developments in the field of vector sialomics, the salivary glands of larval mosquitoes have been largely unexplored. We used whole-transcriptome microarray analysis to create a gene-expression profile of the salivary gland tissue of fourth-instar Anopheles gambiae larvae, and compare it to the gene-expression profile of a matching group of whole larvae. We identified a total of 221 probes with expression values that were (a) significantly enriched in the salivary glands, and (b) sufficiently annotated as to allow the prediction of the presence/absence of signal peptides in their corresponding gene products. Based on available annotation of the protein sequences associated with these probes, we propose that the main roles of larval salivary secretions include: (a) immune response, (b) mouthpart lubrication, (c) nutrient metabolism, and (d) xenobiotic detoxification. Other highlights of the study include the cloning of a transcript encoding a previously unknown salivary defensin (AgDef5), the confirmation of mucus secretion by the larval salivary glands, and the first report of salivary lipocalins in the Culicidae.

Differential roles of an Anopheline midgut GPI-anchored protein in mediating Plasmodium falciparum and Plasmodium vivax ookinete invasion

“…Transcription is then likely initiated within 24 hours after blood feeding to replenish mRNA transcript in preparation for subsequent blood meals. An increase in transcription levels of AgSGU was also found in larval salivary glands relative to the whole larvae with the glands removed (Neira et al, 2009). These data, as well as homology with salivary-gland proteins empirically identified in sand flies (Kato et al, 2006), suggests a role for AgSGU in the salivary glands or saliva, in addition to the midgut.…”

“…Thus, we find no definitive evidence for protein expression of AgSGU in adult female salivary glands, results congruent with a published proteome for this tissue in An. gambiae (Kalume et al, 2005) despite its transcription in the salivary glands of larvae (Neira et al, 2009). …”

Ion and solute transport by Prestin in Drosophila and Anopheles

“…Both genes are located on chromosome 3. Microarray analysis (http://funcgen.vectorbase.org/ExpressionData/) (Neira Oviedo et al, 2009; Neira Oviedo et al, 2008) reveals that Ag PrestinA mRNA is highly expressed in salivary glands and gastric caeca (Fig 3B). On the other hand Ag PrestinB mRNA is highly expressed in posterior midgut and hindgut (Fig 3C).…”

Slc4-like anion transporters of the larval mosquito alimentary canal

“…The foci of this manuscript are the two proteins/transcripts/genes referred to herein as NDAE1 (Na + dependent) and AE1 (Na + independent). Although the Ag AE2 mRNA sequence has been cloned as a cDNA and deposited into GenBank (accession number EU068741) its expression shows little evidence of differential expression in alimentary canal tissues in Ag larvae and hence is not further pursued in this report (Neira-Oviedo et al, 2008, 2009, Linser et al, 2009). In contrast, both Ag NDAE1 and Ag AE1 exhibit differential expression in distinct compartments of the alimentary canal (Linser et al, 2009) and are the foci of this report.…”

“…Also, phylogenetic analyses of SLC4-like gene sequences in Aa and in Anopheles gambiae ( Ag ) were reported in 2009 (Linser et al, 2009). Microarray analyses demonstrate that transcripts of the members of this gene family in Ag larvae are expressed in tissue- and cell-type specific patterns in the alimentary canal (Neira-Oviedo et al, 2008, 2009; ibid). In the present study, we report the cloning and characterization of an NDAE1-like anion exchanger (AE) from larval Ag cDNA (AgNDAE-1).…”