Adult mosquitoes feed on sugary meals to obtain energy for flight and other activities, while anautogenous females take a blood meal to develop eggs. Accordingly, female but not male salivary glands possess several antihemostatic components to facilitate acquisition of blood, while both sexes have activities related to digestion of the sugar meal as well as antimicrobials to maintain meal integrity. Studies on adult female sialotranscriptomes indicated a set of approximately 70 proteins and peptides possibly secreted in saliva that presumably facilitate sugar and blood meals. Most of these proteins have no known function, so no assignment to blood or sugar feeding is possible. Microarray and RT-PCR studies attempted to identify sex specificity of these transcripts. Our present study complements the previous data set, comparing approximately 1000 randomly sequenced clones of a male adult salivary gland cDNA library with the female set. Statistically significant differences were found in 16 transcripts found exclusively in the female library, 4 transcripts significantly female enriched but also found in male glands, and 6 transcripts enriched in male glands. We additionally found a transcript in male salivary glands with a trypsin inhibitor-like (TIL) domain that we presume codes for an antimicrobial peptide; a novel defensin transcript was also found in the male sialotranscriptome. Supplemental tables can be found at.
"For Plasmodium spp. vectors, salivary gland transcriptomes and proteomes of An. gambiae (Cellia sb.) [47,56], An. stephensi (Cellia sb.) , An. funestus (Cellia sb.)  and An. darlingi (Nyssorhynchus sb.) [48,49] have been examined to date, providing a thorough description of the salivary protein repertoire from these main malaria vectors throughout the world. "
[Show abstract][Hide abstract] ABSTRACT: Background
Antibody responses against Anopheles salivary proteins can indicate individual exposure to bites of malaria vectors. The extent to which these salivary proteins are species-specific is not entirely resolved. Thus, a better knowledge of the diversity among salivary protein repertoires from various malaria vector species is necessary to select relevant genus-, subgenus- and/or species-specific salivary antigens. Such antigens could be used for quantitative (mosquito density) and qualitative (mosquito species) immunological evaluation of malaria vectors/host contact. In this study, salivary gland protein repertoires (sialomes) from several Anopheles species were compared using in silico analysis and proteomics. The antigenic diversity of salivary gland proteins among different Anopheles species was also examined.
In silico analysis of secreted salivary gland protein sequences retrieved from an NCBInr database of six Anopheles species belonging to the Cellia subgenus (An. gambiae, An. arabiensis, An. stephensi and An. funestus) and Nyssorhynchus subgenus (An. albimanus and An. darlingi) displayed a higher degree of similarity compared to salivary proteins from closely related Anopheles species. Additionally, computational hierarchical clustering allowed identification of genus-, subgenus- and species-specific salivary proteins. Proteomic and immunoblot analyses performed on salivary gland extracts from four Anopheles species (An. gambiae, An. arabiensis, An. stephensi and An. albimanus) indicated that heterogeneity of the salivary proteome and antigenic proteins was lower among closely related anopheline species and increased with phylogenetic distance.
This is the first report on the diversity of the salivary protein repertoire among species from the Anopheles genus at the protein level. This work demonstrates that a molecular diversity is exhibited among salivary proteins from closely related species despite their common pharmacological activities. The involvement of these proteins as antigenic candidates for genus-, subgenus- or species-specific immunological evaluation of individual exposure to Anopheles bites is discussed.
"These proteins are known to be involved in protein folding, glycolysis and stress response, respectively. Among other housekeeping proteins, the salivary endonuclease which belongs to the hydrolase family was also identified (Table 1): this protein is believed to reduce local blood viscosity at the bite site to enhance the feeding process . "
[Show abstract][Hide abstract] ABSTRACT: Background: The Culex quinquefasciatus mosquito, a major pest and vector of filariasis and arboviruses in the tropics, has developed multiple resistance mechanisms to the main insecticide classes currently available in public health. Among them, the insensitive acetylcholinesterase (ace-1(R) allele) is widespread worldwide and confers cross-resistance to organophosphates and carbamates. Fortunately, in an insecticide-free environment, this mutation is associated with a severe genetic cost that can affect various life history traits. Salivary proteins are directly involved in human-vector contact during biting and therefore play a key role in pathogen transmission. Methods and Results: An original proteomic approach combining 2D-electrophoresis and mass spectrometry was adopted to compare the salivary expression profiles of two strains of C. quinquefasciatus with the same genetic background but carrying either the ace-1(R) resistance allele or not (wild type). Four salivary proteins were differentially expressed (> 2 fold, P < 0.05) in susceptible (SLAB) and resistant (SR) mosquito strains. Protein identification indicated that the D7 long form, a major salivary protein involved in blood feeding success, presented lower expression in the resistant strain than the susceptible strain. In contrast, three other proteins, including metabolic enzymes (endoplasmin, triosephosphate isomerase) were significantly over-expressed in the salivary gland of ace-1(R) resistant mosquitoes. A catalogue of 67 salivary proteins of C. quinquefasciatus sialotranscriptome was also identified and described. Conclusion: The "resistance"-dependent expression of salivary proteins in mosquitoes may have considerable impact on biting behaviour and hence on the capacity to transmit parasites/viruses to humans. The behaviour of susceptible and insecticide-resistant mosquitoes in the presence of vertebrate hosts and its impact on pathogen transmission urgently requires further investigation.
PLoS ONE 03/2011; 6(3):e17496. DOI:10.1371/journal.pone.0017496 · 3.23 Impact Factor
"In the pre-genomic era, EST (Expressed Sequence Tag) based studies were adopted to understand A. gambiae [17-20] and its role in malaria transmission . However, despite its importance as a malaria vector, A. stephensi has not been intensively investigated. "
[Show abstract][Hide abstract] ABSTRACT: Malaria is a tropical disease caused by protozoan parasite, Plasmodium, which is transmitted to humans by various species of female anopheline mosquitoes. Anopheles stephensi is one such major malaria vector in urban parts of the Indian subcontinent. Unlike Anopheles gambiae, an African malaria vector, transcriptome of A. stephensi midgut tissue is less explored. We have therefore carried out generation, annotation, and analysis of expressed sequence tags from sugar-fed and Plasmodium yoelii infected blood-fed (post 24 h) adult female A. stephensi midgut tissue.
We obtained 7061 and 8306 ESTs from the sugar-fed and P. yoelii infected mosquito midgut tissue libraries, respectively. ESTs from the combined dataset formed 1319 contigs and 2627 singlets, totaling to 3946 unique transcripts. Putative functions were assigned to 1615 (40.9%) transcripts using BLASTX against UniProtKB database. Amongst unannotated transcripts, we identified 1513 putative novel transcripts and 818 potential untranslated regions (UTRs). Statistical comparison of annotated and unannotated ESTs from the two libraries identified 119 differentially regulated genes. Out of 3946 unique transcripts, only 1387 transcripts were mapped on the A. gambiae genome. These also included 189 novel transcripts, which were mapped to the unannotated regions of the genome. The EST data is available as ESTDB at http://mycompdb.bioinfo-portal.cdac.in/cgi-bin/est/index.cgi.
3946 unique transcripts were successfully identified from the adult female A. stephensi midgut tissue. These data can be used for microarray development for better understanding of vector-parasite relationship and to study differences or similarities with other malaria vectors. Mapping of putative novel transcripts from A. stephensi on the A. gambiae genome proved fruitful in identification and annotation of several genes. Failure of some novel transcripts to map on the A. gambiae genome indicates existence of substantial genomic dissimilarities between these two potent malaria vectors.
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