关键词: 意大利蝗, 越冬卵, 胚胎发育, 血蓝蛋白, 基因表达, 表达谱

Abstract: 【Aim】 Calliptamus italicus is a major dominant pest in Xinjiang and overwinters in the soil with eggs. Respiratory metabolism can reflect the physiological state of locust eggs. Respiratory protein is especially important for C. italicus eggs, whose respiratory system is not well-developed. This study aims to clarify the expression profiles of hemocyanin gene in the developmental process of C. italicus eggs. 【Methods】 The expression levels of hemocyanin subunit genes Hc1 and Hc2 in different developmental stages of eggs and the 1st instar nymph of C. italicus were analyzed by quantitative real-time PCR. 【Results】 Based on anatomical observation, the developmental process of overwintering eggs of C. italicus is divided into ten stages, including nine egg stages (C-Ⅰ-C-Ⅸ) and the 1st instar nymph stage (C-Ⅹ). Hc1 and Hc2 were expressed in all the developmental stages of eggs and the 1st instar nymph of C. italicus. During the early stage of embryogenesis (C-Ⅰ, C-Ⅱ and C-Ⅲ), the expression level of Hc1 increased gradually, and was significantly higher at the stage C-Ⅲ than at the stages C-Ⅰ and C-Ⅱ. During the diapause stage (C-Ⅳ, C-Ⅴ and C-Ⅵ), the embryonic development was stagnant, and the expression level of Hc1 was lower than those at the stages C-Ⅲ, C-Ⅶ and C-Ⅷ. During the post-diapause developmental stage (C-Ⅶ and C-Ⅷ), the diapause of eggs were terminated and eggs developed rapidly, and the expression level of Hc1 was higher than those at the early developmental stage and diapause stage. Especially, the expression level of Hc1 in eggs at the stage C-Ⅷ was the highest (212.3156±10.5470), significantly higher than that in eggs at all of the other stages, and the expression level of Hc1 in the 1st instar nymph was the lowest (0.4017±0.1010). The expression level of Hc2 in eggs at the stage C-Ⅴ was the highest (679.7511±54.5719). The expression level of Hc2 was not significantly different at various developmental stages of eggs except stage C-Ⅴ. Hc1 was highly expressed during the post-diapause stage of eggs, while Hc2 was highly expressed during the diapause stage of eggs. 【Conclusion】 The hemocyanin subunit genes Hc1 and Hc2 are expressed throughout the developmental process of C. italicus eggs and show phase-specific expression. Hc1 and Hc2 synergistically provide oxygen for egg development. Hc1 is mainly responsible for oxygen transport during the post-diapause developmental stage of eggs, while Hc2 is mainly responsible for oxygen transport during the diapause stage of eggs with low oxygen carrying efficiency. The results can provide a scientific basis for further exploration of the stress resistance mechanism of C. italicus eggs.

Key words: Calliptamus italicus, overwintering egg, embryonic development, hemocyanin, gene expression, expression profile