Abstract: Chemosensory proteins (CSPs) are a class of small soluble proteins in insects, which are supposed to recognize and transport non-volatility odour molecules and chemical stimuli. In this study, we investigated the expression pattern of BmCSP4 using semi-quantitative RT-PCR. The results showed that BmCSP4 was expressed across various developmental stages, with gradual decrease from 4th larva to pupa. The tissue expression profile in males and females at adult stage was further studied, and the results showed that the expression level of BmCSP4 was lower in female head (with antennae removed), throax and abdomen than in other female tissues. The binding specificity of BmCSP4 to 15 compounds was tested using N-phenyl-1-naphthylamine (1-NPN) as fluorescent probe, and the results showed that only benzaldehyde, p-methoxy benzaldehy, 2-pentyl-3-phenylpropenoic, 1-phenyl-1-butanol and acetophenone at the concentration of 10 μmol/L replaced 1-NPN from BmCSP4 by 50%, with the dissociation constants of 3.20, 2.24, 2.88, 2.04 and 2.52 μmol/L, respectively. These results suggest that BmCSP4 may have diverse physiological function in different developmental stages, and may be involved in the process of discriminating aromatic aldehyde and aromatic ketone compounds.

Key words: Bombyx mori, chemosensory protein, semi-quantitative PCR, N-phenyl-1-naphthylamine, fluorescence binding assay