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An insight into the sialotranscriptome of the West Nile mosquito vector, Culex tarsalis.

Calvo E, Sanchez-Vargas I, Favreau AJ, Barbian KD, Pham VM, Olson KE, Ribeiro JM - BMC Genomics (2010)

Bottom Line: Comparison of the C. tarsalis sialotranscriptome with that of C. quinquefasciatus reveals accelerated evolution of salivary proteins as compared to housekeeping proteins.Several protein families previously found exclusive of mosquitoes, including only in the Aedes genus have been identified in C. tarsalis.Interestingly, a protein family so far unique to C. quinquefasciatus, with 30 genes, is also found in C. tarsalis, indicating it was not a specific C. quinquefasciatus acquisition in its evolution to optimize mammal blood feeding.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Vector Biology, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.

ABSTRACT

Background: Saliva of adult female mosquitoes help sugar and blood feeding by providing enzymes and polypeptides that help sugar digestion, control microbial growth and counteract their vertebrate host hemostasis and inflammation. Mosquito saliva also potentiates the transmission of vector borne pathogens, including arboviruses. Culex tarsalis is a bird feeding mosquito vector of West Nile Virus closely related to C. quinquefasciatus, a mosquito relatively recently adapted to feed on humans, and the only mosquito of the genus Culex to have its sialotranscriptome so far described.

Results: A total of 1,753 clones randomly selected from an adult female C. tarsalis salivary glands (SG) cDNA library were sequenced and used to assemble a database that yielded 809 clusters of related sequences, 675 of which were singletons. Primer extension experiments were performed in selected clones to further extend sequence coverage, allowing for the identification of 283 protein sequences, 80 of which code for putative secreted proteins.

Conclusion: Comparison of the C. tarsalis sialotranscriptome with that of C. quinquefasciatus reveals accelerated evolution of salivary proteins as compared to housekeeping proteins. The average amino acid identity among salivary proteins is 70.1%, while that for housekeeping proteins is 91.2% (P < 0.05), and the codon volatility of secreted proteins is significantly higher than those of housekeeping proteins. Several protein families previously found exclusive of mosquitoes, including only in the Aedes genus have been identified in C. tarsalis. Interestingly, a protein family so far unique to C. quinquefasciatus, with 30 genes, is also found in C. tarsalis, indicating it was not a specific C. quinquefasciatus acquisition in its evolution to optimize mammal blood feeding.

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The 30.5 kDa family of culicine proteins. A) Clustal alignment. The Culex tarsalis proteins are identified by their Ctar-prefix. The remaining sequences are named with the first three letters from the genus name followed by two letters from the species name and by their NCBI protein accession number. The symbols above the alignment indicate: (*) identical sites; (:) conserved sites; less conserved sites. B) Neighbor Joining bootstrapped phylogram of the alignment in A. The Culex tarsalis proteins are marked with a square symbol. The numbers on the branches represent the percent bootstrap support. The bar in the bottom represents 20% amino acid divergence. For more details, see text.
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Figure 4: The 30.5 kDa family of culicine proteins. A) Clustal alignment. The Culex tarsalis proteins are identified by their Ctar-prefix. The remaining sequences are named with the first three letters from the genus name followed by two letters from the species name and by their NCBI protein accession number. The symbols above the alignment indicate: (*) identical sites; (:) conserved sites; less conserved sites. B) Neighbor Joining bootstrapped phylogram of the alignment in A. The Culex tarsalis proteins are marked with a square symbol. The numbers on the branches represent the percent bootstrap support. The bar in the bottom represents 20% amino acid divergence. For more details, see text.

Mentions: Members of the 30.5 kDa protein were previously discovered in Ae. aegypti, Ae. albopictus and C. quinquefasciatus sialotranscriptomes. Additional related proteins were also deducted from the genomes of Ae. aegypti and C. quinquefasciatus, but not An. gambiae. The sialotranscriptome of C. tarsalis provides additional evidence for this multi copy family exclusive of Culicines. Clustal alignment of these protein sequences (Fig 4A) shows many conserved amino acids and a conserved Cys framework on the second half of the protein. The bootstrapped phylogram shows 3 robust clades. Clade I contains a sub clade of 2 Ae. aegypti and 2 Ae. albopictus proteins, and a second sub clade of a C. quinquefasciatus and Ctar-129. Clade II has 4 C. tarsalis sequences, possibly alleles of a single gene or closely related genes, and one C. quinquefasciatus sequence. Clade III shows a possible gene expansion in C. quinquefasciatus containing 4 gene products, clustering with one Ae. aegypti sequence. Overall the phylogram indicates that Aedes aegypti has at least 3 genes coding for this protein family, while C. quinquefasciatus has at least 6, 3 of which possibly arrived by further gene duplications within clade III. Culex tarsalis and Ae. albopictus, have at least two genes expressing these proteins in their adult female salivary glands. Psiblast of members of this protein family against the NR protein database converges after 6 iterations, retrieving solely Aedes and Culex proteins (not shown). The function of this protein family is unknown, but transcripts for this family were found enriched in the salivary glands of adult female Ae. aegypti [4] suggesting a blood feeding role.


An insight into the sialotranscriptome of the West Nile mosquito vector, Culex tarsalis.

Calvo E, Sanchez-Vargas I, Favreau AJ, Barbian KD, Pham VM, Olson KE, Ribeiro JM - BMC Genomics (2010)

The 30.5 kDa family of culicine proteins. A) Clustal alignment. The Culex tarsalis proteins are identified by their Ctar-prefix. The remaining sequences are named with the first three letters from the genus name followed by two letters from the species name and by their NCBI protein accession number. The symbols above the alignment indicate: (*) identical sites; (:) conserved sites; less conserved sites. B) Neighbor Joining bootstrapped phylogram of the alignment in A. The Culex tarsalis proteins are marked with a square symbol. The numbers on the branches represent the percent bootstrap support. The bar in the bottom represents 20% amino acid divergence. For more details, see text.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2823692&req=5

Figure 4: The 30.5 kDa family of culicine proteins. A) Clustal alignment. The Culex tarsalis proteins are identified by their Ctar-prefix. The remaining sequences are named with the first three letters from the genus name followed by two letters from the species name and by their NCBI protein accession number. The symbols above the alignment indicate: (*) identical sites; (:) conserved sites; less conserved sites. B) Neighbor Joining bootstrapped phylogram of the alignment in A. The Culex tarsalis proteins are marked with a square symbol. The numbers on the branches represent the percent bootstrap support. The bar in the bottom represents 20% amino acid divergence. For more details, see text.
Mentions: Members of the 30.5 kDa protein were previously discovered in Ae. aegypti, Ae. albopictus and C. quinquefasciatus sialotranscriptomes. Additional related proteins were also deducted from the genomes of Ae. aegypti and C. quinquefasciatus, but not An. gambiae. The sialotranscriptome of C. tarsalis provides additional evidence for this multi copy family exclusive of Culicines. Clustal alignment of these protein sequences (Fig 4A) shows many conserved amino acids and a conserved Cys framework on the second half of the protein. The bootstrapped phylogram shows 3 robust clades. Clade I contains a sub clade of 2 Ae. aegypti and 2 Ae. albopictus proteins, and a second sub clade of a C. quinquefasciatus and Ctar-129. Clade II has 4 C. tarsalis sequences, possibly alleles of a single gene or closely related genes, and one C. quinquefasciatus sequence. Clade III shows a possible gene expansion in C. quinquefasciatus containing 4 gene products, clustering with one Ae. aegypti sequence. Overall the phylogram indicates that Aedes aegypti has at least 3 genes coding for this protein family, while C. quinquefasciatus has at least 6, 3 of which possibly arrived by further gene duplications within clade III. Culex tarsalis and Ae. albopictus, have at least two genes expressing these proteins in their adult female salivary glands. Psiblast of members of this protein family against the NR protein database converges after 6 iterations, retrieving solely Aedes and Culex proteins (not shown). The function of this protein family is unknown, but transcripts for this family were found enriched in the salivary glands of adult female Ae. aegypti [4] suggesting a blood feeding role.

Bottom Line: Comparison of the C. tarsalis sialotranscriptome with that of C. quinquefasciatus reveals accelerated evolution of salivary proteins as compared to housekeeping proteins.Several protein families previously found exclusive of mosquitoes, including only in the Aedes genus have been identified in C. tarsalis.Interestingly, a protein family so far unique to C. quinquefasciatus, with 30 genes, is also found in C. tarsalis, indicating it was not a specific C. quinquefasciatus acquisition in its evolution to optimize mammal blood feeding.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Vector Biology, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.

ABSTRACT

Background: Saliva of adult female mosquitoes help sugar and blood feeding by providing enzymes and polypeptides that help sugar digestion, control microbial growth and counteract their vertebrate host hemostasis and inflammation. Mosquito saliva also potentiates the transmission of vector borne pathogens, including arboviruses. Culex tarsalis is a bird feeding mosquito vector of West Nile Virus closely related to C. quinquefasciatus, a mosquito relatively recently adapted to feed on humans, and the only mosquito of the genus Culex to have its sialotranscriptome so far described.

Results: A total of 1,753 clones randomly selected from an adult female C. tarsalis salivary glands (SG) cDNA library were sequenced and used to assemble a database that yielded 809 clusters of related sequences, 675 of which were singletons. Primer extension experiments were performed in selected clones to further extend sequence coverage, allowing for the identification of 283 protein sequences, 80 of which code for putative secreted proteins.

Conclusion: Comparison of the C. tarsalis sialotranscriptome with that of C. quinquefasciatus reveals accelerated evolution of salivary proteins as compared to housekeeping proteins. The average amino acid identity among salivary proteins is 70.1%, while that for housekeeping proteins is 91.2% (P < 0.05), and the codon volatility of secreted proteins is significantly higher than those of housekeeping proteins. Several protein families previously found exclusive of mosquitoes, including only in the Aedes genus have been identified in C. tarsalis. Interestingly, a protein family so far unique to C. quinquefasciatus, with 30 genes, is also found in C. tarsalis, indicating it was not a specific C. quinquefasciatus acquisition in its evolution to optimize mammal blood feeding.

Show MeSH
Related in: MedlinePlus