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Expression patterns of cysteine peptidase genes across the Tribolium castaneum life cycle provide clues to biological function

Perkin, Lindsey, Elpidina, Elena N., Oppert, Brenda
PeerJ 2016 v.4 no.e1581 pp. 1-22
Tribolium castaneum, adults, chromosomes, cysteine, digestion, eggs, gene expression, genes, insects, larvae, midgut, peptidases, pests, phylogeny, pupae, stored grain, transcriptome
The red flour beetle, Tribolium castaneum, is a major agricultural pest responsible for considerable loss of stored grain and cereal products worldwide. T. castaneum larvae have a highly compartmentalized gut, with cysteine peptidases mostly in the acidic anterior part of the midgut which are critical to the early stages of food digestion. We have described 26 putative cysteine peptidase genes in T. castaneum (types B, L, O, F, and K) located mostly on chromosomes 3, 7, 8, and 10. In the present study, we hypothesized that we could associate specific cysteine peptidase genes with digestive functions for food processing based on comparison of gene expression profiles in different developmental stages, feeding and non-feeding. We used RNA-Seq to determine the relative expression of cysteine peptidase genes among four major developmental stages (egg, larvae, pupae, and adult) of T. castaneum. We also compared T. castaneum cysteine peptidase genes to those in other model insects and coleopteran pests. By combining transcriptome expression, phylogenetic comparisons, response to dietary inhibitors, and other existing data, we identified key cysteine peptidases that T. castaneum larvae and adults use for food digestion, and thus new potential targets for biologically-based control products.