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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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Phylogram of the D7 protein family of mosquitoes. The numbers on the tree nodes represent the percent bootstrap support in 10,000 trials (only values above 50% are shown). The bar at the bottom indicates amino acid divergence. The Culex tarsalis sequences are named Ctar-XXX where the XXX represents the cluster number that originated it. The remaining sequences are named in a five letter followed by number format where the 3 first letters represent the 3 first letters of the genus, followed by the first 2 letters of the species binomial name. The number represents the NCBI gi/ access. For more details, see text.
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Figure 2: Phylogram of the D7 protein family of mosquitoes. The numbers on the tree nodes represent the percent bootstrap support in 10,000 trials (only values above 50% are shown). The bar at the bottom indicates amino acid divergence. The Culex tarsalis sequences are named Ctar-XXX where the XXX represents the cluster number that originated it. The remaining sequences are named in a five letter followed by number format where the 3 first letters represent the 3 first letters of the genus, followed by the first 2 letters of the species binomial name. The number represents the NCBI gi/ access. For more details, see text.

Mentions: Eight members of the D7 protein family were found in the C. tarsalis sialotranscriptome, in addition to two canonical OBP proteins. Alignment of these proteins with their close blast matches found in the NR protein database, and construction of a bootstrapped phylogram (Fig 2) shows several clades with strong bootstrap support, and allows the following inferences: The eight C. tarsalis proteins are the probable results of 4 genes. Ctar-34, Ctar-35 and Ctar-36 are possible alleles of a single gene related to other long C. quinquefasciatus D7 proteins shown in Clade I, while Ctar-37, Ctar-38 and Ctar-40 are probably alleles of a second C. tarsalis gene coding for yet another long D7 protein, and are associated within Clade II. Ctar-173, results from a gene coding for a third long D7 protein grouping in Clade V with other mosquito long D7 proteins, including, Anopheles and Aedes proteins. Ctar-371 is the only C. tarsalis sequence for a short D7 protein, grouping in clade IV with other Culex pipiens D7 proteins. Notice also Clades III and Clade VI, which exclusively contain long D7 Anopheline or Phlebotomine proteins, respectively.


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)

Phylogram of the D7 protein family of mosquitoes. The numbers on the tree nodes represent the percent bootstrap support in 10,000 trials (only values above 50% are shown). The bar at the bottom indicates amino acid divergence. The Culex tarsalis sequences are named Ctar-XXX where the XXX represents the cluster number that originated it. The remaining sequences are named in a five letter followed by number format where the 3 first letters represent the 3 first letters of the genus, followed by the first 2 letters of the species binomial name. The number represents the NCBI gi/ access. For more details, see text.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Phylogram of the D7 protein family of mosquitoes. The numbers on the tree nodes represent the percent bootstrap support in 10,000 trials (only values above 50% are shown). The bar at the bottom indicates amino acid divergence. The Culex tarsalis sequences are named Ctar-XXX where the XXX represents the cluster number that originated it. The remaining sequences are named in a five letter followed by number format where the 3 first letters represent the 3 first letters of the genus, followed by the first 2 letters of the species binomial name. The number represents the NCBI gi/ access. For more details, see text.
Mentions: Eight members of the D7 protein family were found in the C. tarsalis sialotranscriptome, in addition to two canonical OBP proteins. Alignment of these proteins with their close blast matches found in the NR protein database, and construction of a bootstrapped phylogram (Fig 2) shows several clades with strong bootstrap support, and allows the following inferences: The eight C. tarsalis proteins are the probable results of 4 genes. Ctar-34, Ctar-35 and Ctar-36 are possible alleles of a single gene related to other long C. quinquefasciatus D7 proteins shown in Clade I, while Ctar-37, Ctar-38 and Ctar-40 are probably alleles of a second C. tarsalis gene coding for yet another long D7 protein, and are associated within Clade II. Ctar-173, results from a gene coding for a third long D7 protein grouping in Clade V with other mosquito long D7 proteins, including, Anopheles and Aedes proteins. Ctar-371 is the only C. tarsalis sequence for a short D7 protein, grouping in clade IV with other Culex pipiens D7 proteins. Notice also Clades III and Clade VI, which exclusively contain long D7 Anopheline or Phlebotomine proteins, respectively.

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