Identification and expression pattern of the chemosensory protein gene family in the silkworm, Bombyx mori

Insect chemosensory proteins (CSPs) as well as odorant-binding proteins (OBPs) have been supposed to transport hydrophobic chemicals to receptors on sensory neurons. Compared with OBPs, CSPs are expressed more broadly in various insect tissues. We performed a genome-wide analysis of the candidate CSP gene family in the silkworm. A total of 20 candidate CSPs, including 3 gene fragments and 2 pseudogenes, were characterized based on their conserved cysteine residues and their similarity to CSPs in other insects. Some of these genes were clustered in the silkworm genome. The gene expression pattern of these candidates was investigated using RT-PCR and microarray, and the results showed that these genes were expressed primarily in mature larvae and the adult moth, suggesting silkworm CSPs may be involved in development. The majority of silkworm CSP genes are expressed broadly in tissues including the antennae, head, thorax, legs, wings, epithelium, testes, ovaries, pheromone glands, wing disks, and compound eyes.