Kim Mijung, Robich Rebecca M, Rinehart Joseph P, Denlinger David L
Department of Entomology, The Ohio State University, Columbus, OH 43210, USA.
J Insect Physiol. 2006 Nov-Dec;52(11-12):1226-33. doi: 10.1016/j.jinsphys.2006.09.007. Epub 2006 Sep 20.
Two actin genes cloned from Culex pipiens L. are upregulated during adult diapause. Though actins 1 and 2 were expressed throughout diapause, both genes were most highly expressed early in diapause. These changes in gene expression were accompanied by a conspicuous redistribution of polymerized actin that was most pronounced in the midguts of diapausing mosquitoes that were exposed to low temperature. In nondiapausing mosquitoes reared at 25 degrees C and in diapausing mosquitoes reared at 18 degrees C, polymerized actin was clustered at high concentrations at the intersections of the muscle fibers that form the midgut musculature. When adults 7-10 days post-eclosion were exposed to low temperature (-5 degrees C for 12 h), the polymerized actin was evenly distributed along the muscle fibers in both nondiapausing and diapausing mosquitoes. Exposure of older adults (1 month post-eclosion) to low temperature (-5 degrees C for 12 h) elicited an even greater distribution of polymerized actin, an effect that was especially pronounced in diapausing mosquitoes. These changes in gene expression and actin distribution suggest a role for actins in enhancing survival of diapausing adults during the low temperatures of winter by fortification of the cytoskeleton.
从致倦库蚊中克隆出的两个肌动蛋白基因在成虫滞育期间上调。虽然肌动蛋白1和2在整个滞育期均有表达，但这两个基因在滞育早期表达水平最高。基因表达的这些变化伴随着聚合肌动蛋白明显的重新分布，这在暴露于低温的滞育蚊子的中肠中最为明显。在25摄氏度饲养的非滞育蚊子和18摄氏度饲养的滞育蚊子中，聚合肌动蛋白在形成中肠肌肉组织的肌纤维交叉处高浓度聚集。羽化后7 - 10天的成虫暴露于低温（-5摄氏度，12小时）时，非滞育和滞育蚊子的聚合肌动蛋白均沿肌纤维均匀分布。将羽化后1个月的老龄成虫暴露于低温（-5摄氏度，12小时）会引发聚合肌动蛋白更广泛的分布，这种效应在滞育蚊子中尤为明显。基因表达和肌动蛋白分布的这些变化表明，肌动蛋白通过强化细胞骨架在增强滞育成虫在冬季低温期间的存活率方面发挥作用。
