JIA-2019-11

2584 CUI Dong-nan et al. Journal of Integrative Agriculture 2019, 18(11): 2579–2588 diapause (Miura et al. 1998; Godlewski et al. 2001, Lewis et al. 2002, Sonoda et al. 2006, Spyliotopoulos et al. 2007, Tungjitwitayakul et al. 2008). For example, in diapause larvae of rice stem borer, Chilo suppressalis , Sonoda et al. (2006) found the up-regulation of storage protein 1 when the temperature of cold acclimation was shifted to 5 from 10°C. In Sesamia nonagrioides , mRNA levels of a storage protein were extremely low in larvae at the pre-diapause stage, but levels dramatically increased at the maintenance and termination stages of diapause (Spyliotopoulos et al. 2007). In our study, hexamerin-like protein 4 was significantly up- regulated in diapause eggs while hexamerin-like protein 1 was significantly down-regulated in diapause eggs in comparison to non-diapause eggs. Hexamerin-like protein 2 showed no significant difference between diapause and non-diapause eggs. Furthermore, verification of transcriptional levels by qRT-PCR showed that the level of hexamerin-like protein 4 in diapause eggs was significantly lower than that in non-diapause eggs, which was contrary to the change trend observed of protein levels. We speculate that the female locusts of the diapause treatment group synthesized hexamerin-like protein 4 and passed it onto their offspring, in order to help their offsprings survive the long diapause period. Studies revealed that juvenile hormone (JH) and its analogue are involved in diapause regulation (Yin and Chippendale 1976; Singtripop et al. 2002). Tawfik et al. (2002) found that the content of JH in diapause eggs was significantly lower than that in non-diapause eggs of migratory locust, with at least three types of enzymes, JH esterase, JH epoxide hydrolase and JH diol kinase, involved in JH degradation (Morisseau and Hammock 2005; Kamita and Hammock 2010; Saito et al. 2015). Wolschin and Gadau (2009) found the expression level of a JH epoxide hydroxylase increases with time in Nasonia diapause larvae. In our research, we found that the expression of JHEH1 was down-regulated in diapause eggs, but the difference from non-diapause eggs was not significant. Moreover, the qRT-PCR results showed that transcript expression of JHEH1 in diapause eggs was significantly lower than that of the non-diapause eggs, which was consistent with the difference observed in the protein result. Ecdysone also plays an important role in diapause regulation (Sonobe et al. 1999) and the cytochrome P450 gene is critical in the synthesis of ecdysone. Cytochrome P450 enzymes catalyze biosynthesis of ecdysone in 0 5 10 15 20 25 Small molecule metabolic process Organic acid metabolic process Carboxylic acid metabolic process Oxoacid metabolic process Cellular ketone metabolic process Cellular nitrogen compound biosynthetic process Monovalent inorganic cation transport Proton transport Hydrogen transport Cellular amino acid metabolic process Folic acid-containing compound biosynthetic process Cellular amine metabolic process Electron transport Cofactor metabolic process Heterocycle biosynthetic process Coenzyme biosynthetic process Aspartate family amino acid biosynthetic process Coenzyme metabolic process Nucleotide biosynthetic process Organic acid biosynthetic process Proton-transporting two-sector ATPase complex Ribonucleoprotein complex Macromolecular complex Cytoplasm Ribosome Oxidoreductase activity Oxidoreductase activity, acting on the CH-CH group of donors Acyl-CoA dehydrogenase activity Calcium ion storage activity Structural constituent of ribosome Number of proteins GO term The most enriched GO terms Molecular function Biological process Cellular component Fig. 4 Gene Ontology (GO) classification of differentially expressed proteins (DEPs) between non-diapause and diapause locust eggs. The DEPs are grouped into three hierarchically structured GO terms, biological process, cellular component, and molecular function.