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【目的】低温是影响昆虫生长发育和存活的关键因子之一。为明确轮纹异痂蝗Bryodemella tuberculatum dilutum卵的抗寒性及其机理,研究了其过冷却能力与其体内水分及其他抗寒性相关生化物质含量的关系。【方法】采用热电偶法测定了轮纹异痂蝗卵的过冷却点,同时采用烘干法、残余法、氨基酸自动分析仪和高效液相色谱法分别测定了其卵的含水量、脂肪、氨基酸及小分子糖醇的含量。【结果】土壤含水量对轮纹异痂蝗滞育前卵的含水量、脂肪含量(鲜重)及过冷却点有极显著的影响(P<0.01)。随着土壤含水量从4%增加到13%,卵含水量从45.12%上升到55.25%,卵脂肪含量(鲜重)从10.39%下降到9.39%,而过冷却点从-30.11℃上升到-25.69℃。不同发育阶段卵的过冷却点、含水量、脂肪、氨基酸及小分子糖醇含量存在极显著差异(P<0.01)。从卵产下当天至120 d,卵过冷却点从-26.78℃下降至-30.18℃,含水量从51.93%下降至46.69%,脂肪含量分别从9.99%(鲜重)和17.37%(干重)上升至13.92%(鲜重)和25.29%(干重)。滞育卵的过冷却点显著低于滞育前卵的过冷却点。从卵中共检测到17种氨基酸,其中5种与过冷却点存在显著的相关关系(P<0.05)。卵过冷却点随着甘氨酸和脯氨酸含量的升高而降低,而随着胱氨酸、亮氨酸及天冬氨酸含量的增加而升高。随着卵的发育,海藻糖、甘油、肌醇和山梨醇含量逐渐上升,而葡萄糖和果糖含量逐渐下降。在卵发育过程中,海藻糖和甘油的含量显著高于其他4种物质的含量。卵过冷却点与上述6种小分子糖醇均存在显著的相关关系,其中与海藻糖和葡萄糖的相关性最强。过冷却点随海藻糖、甘油、肌醇和山梨醇含量的升高而降低,而随葡萄糖和果糖含量的升高而上升。【结论】轮纹异痂蝗卵在发育过程中,通过降低含水量,积累脂肪、脯氨酸、甘氨酸及海藻糖、甘油、肌醇和山梨醇等抗寒物质,从而提高其过冷却能力。
【Objective】 Low temperature is one of the key factors that affect the growth and survival of insects. To understand the cold resistance of Bryodemella tuberculatum dilutum eggs and its mechanism, the relationship between its supercooling ability and the contents of water and other cold-tolerance-related biochemical substances in vivo was studied. 【Method】 The supercooling points of eggs of C. crus-galli were determined by thermocouple method. At the same time, the egg-water content, fat, protein content were determined by drying method, residual method, automatic amino acid analyzer and high performance liquid chromatography Amino acids and small molecule sugar alcohol content. 【Result】 The results showed that the soil water content significantly affected the water content, fat content (fresh weight) and subcooling point of diapause eggs before larvae (P <0.01). With the increase of soil water content from 4% to 13%, the water content of eggs increased from 45.12% to 55.25%, the fat content (fresh weight) decreased from 10.39% to 9.39%, while the supercooling point increased from -30.11 ℃ to - 25.69 ° C. The subcooling point, water content, fat, amino acids and small molecule sugar alcohol content of eggs in different developmental stages were significantly different (P <0.01). The egg subcooling point decreased from -26.78 ℃ to -30.18 ℃, the water content decreased from 51.93% to 46.69%, and the fat content decreased from 9.99% (fresh weight) to 17.37% (dry weight) Rose to 13.92% (fresh weight) and 25.29% (dry weight). The subcooling point of diapause eggs was significantly lower than that of the pre-diapause eggs. A total of 17 amino acids were detected from eggs, of which 5 were significantly correlated with subcooling (P <0.05). The egg subcooling point decreased with the increase of glycine and proline content, but increased with the increase of cystine, leucine and aspartate contents. With the development of eggs, the content of trehalose, glycerol, inositol and sorbitol gradually increased while the content of glucose and fructose decreased gradually. During egg development, trehalose and glycerol levels were significantly higher than the other four substances. There was a significant correlation between egg subcooling point and the above six kinds of small sugar alcohols, of which the correlation with trehalose and glucose was the strongest. The subcooling point decreased with the increase of the content of trehalose, glycerol, inositol and sorbitol, but increased with the increase of glucose and fructose. 【Conclusion】 During the process of development, the egg of C. crus-galli increased its supercooling capacity by reducing the water content, accumulating cold, proline, glycine and trehalose, glycerin, inositol and sorbitol and other cold-resistant substances.