The cowpea weevil bruchid is an agriculturally important pest worldwide. Information about gene expression during digestion in this insect is lacking. We describe here the first systematic work to discover genes involved in food breakdown in C. maculatus. Using a cDNA library enriched for gut-expressed genes, a total of 1056 ESTs were screened and 503 sequences having non-redundant open reading frames were selected. Statistical analysis for the functionally annotated best matches in the non-redundant NCBI protein database revealed 74.4% similarity with other insect proteins (E£10-7). Twenty-three inferred genes potentially involved in digestive processes in cowpea weevil were identified. The genes included seven peptidases, five amylases and five glucosidases, among others. Cysteine and aspartic proteinases and a-amylases were studied in greater detail using deduced sequences. The predicted catalytic sites were identified in all three classes of enzymes. Transcriptome analysis of the cowpea bruchid will potentially permit gene discovery in other beetles, an insect order of major economic importance.
Species 1: Coleoptera Chrysomelidae Callosobruchus maculatus (cowpea weevil)
Keywords: expressed sequence tag, digestive enzymes
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