Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States.
J Insect Physiol. 2011 Jul;57(7):1017-22. doi: 10.1016/j.jinsphys.2011.04.019. Epub 2011 May 1.
Neuropeptides are important regulators of diverse processes during development. The insect neuropeptide bursicon, a 30 kDa heterodimer, controls the hardening of the new cuticle after the shedding of the old one (ecdysis) and the inflation and maturation of adult wings. Given this specific functional role, its expression should only be required transiently because adult insects no longer undergo ecdysis. Here we report the transient expression of bursicon in the mosquito, Anopheles gambiae. Quantitative RT-PCR revealed that transcription of the bursicon monomers, burs and pburs, steadily increases through the larval stages, peaks in the black pupa stage, and decreases to below detectable levels by 8 h after adult ecdysis (eclosion). Immunohistochemistry on the adult nervous system showed that bursicon is co-expressed with crustacean cardioactive peptide (CCAP) in specific neurons of the abdominal ganglia, but that labeling intensity wanes by 14 h post-eclosion. Finally, detection of disintegrating DNA by TUNEL labeling demonstrated that the bursicon expressing neurons successively undergo apoptosis following eclosion. Taken altogether, these data describe A. gambiae as another holometabolous insect in which bursicon ceases to be produced in adults, and in which the bursicon expressing neurons are removed from the ventral nerve cord.
神经肽是发育过程中多种过程的重要调节剂。昆虫神经肽bursicon 是一种 30 kDa 的异二聚体，它控制着旧表皮（蜕皮）脱落后新表皮的硬化，以及成年翅膀的充气和成熟。鉴于其特定的功能作用，它的表达应该只是暂时需要的，因为成年昆虫不再经历蜕皮。在这里，我们报告了蚊子 Anopheles gambiae 中 bursicon 的瞬时表达。定量 RT-PCR 显示，burs 和 pburs 单体的转录在幼虫阶段持续增加，在黑蛹阶段达到峰值，并在成年蜕皮（羽化）后 8 小时降至无法检测的水平。对成年神经系统的免疫组织化学染色显示，bursicon 与甲壳动物心活肽（CCAP）在腹神经节的特定神经元中共同表达，但在羽化后 14 小时标记强度减弱。最后，通过 TUNEL 标记检测到的降解 DNA 表明，表达 bursicon 的神经元在羽化后相继经历细胞凋亡。总的来说，这些数据表明 A. gambiae 是另一种完全变态昆虫，其中 bursicon 在成年期不再产生，并且表达 bursicon 的神经元从腹神经索中移除。
