Neurohormone cascades during crustacean ecdysis

所有节肢动物（如昆虫和螃蟹）都必须定期蜕去外骨骼，以便生长和变形。这个过程被称为蜕皮，是由复杂的激素控制的。就在蜕皮之前，一系列精确定时的激素“级联反应”开始了，这引发了一系列的行为和形态变化，使动物得以出现，膨胀到最终（更大的尺寸），并最终硬化外骨骼。对于昆虫，尤其是果蝇，我们对这些过程中涉及的激素了解甚多，特别是甲壳类动物心脏活性肽和囊囊素的激素研究得特别深入。对于甲壳类动物，我们几乎一无所知，尽管甲壳类动物的心脏活性肽，顾名思义，首先是在螃蟹中发现的！关于法氏囊，直到最近我在螃蟹身上发现了编码类似“法氏囊样”激素的基因，人们才对其有所了解。然而，我们不太了解这些激素是如何工作的，或者它们在甲壳类动物中的功能，而且由于水生甲壳类动物（如螃蟹）和昆虫（如苍蝇）有着非常不同的生活方式，确定这些激素在分解过程中是如何工作和相互作用的将是非常有趣的。这将通过测定激素在螃蟹中枢神经系统的神经细胞中的分布和水平，以及它们在蜕化过程中是如何释放的来完成的。通过测量释放模式，使用高度敏感的分析技术来确定在旧外骨骼出现的精确时间阶段释放的少量激素，以及随着新外骨骼的发育和硬化。我还将使用一种名为“RNA干扰”的强大技术（该技术的创始人刚刚获得诺贝尔奖），以减少在换羽过程中螃蟹神经系统中存在的激素和/或基因表达水平（法氏囊和甲壳类动物心脏活性肽），或减少螃蟹皮肤中法氏囊受体的数量（昆虫法氏囊的目标组织），看看我是否能破坏动物的正常换羽模式和行为。从而揭示了激素的功能。最后，我将尝试通过注射激素或药物来“拯救”这些异常的蜕皮模式，这些药物将激素信号传递给参与产生新外骨骼的细胞机器，并观察蜕皮期间和之后的后续事件。通过这种方式，我们可以更详细地了解一个极其复杂的过程——蜕皮。这不仅可以让我们比较两种最大的节肢动物群体之间这些激素作用方式的差异，而且还可以在未来，允许操纵经济上重要的甲壳类动物的换羽，以经济上可持续的方式最大化产量。

All arthropods (such as insects and crabs) must periodically shed their exoskeletons in order to grow and matamorphose. This process, called ecdysis, is under complex hormonal control. Just before ecdysis a precisely timed series of hormonal 'cascades' begin, which set off a series of behavioural and morphological changes allowing the animal to emerge, swell to its final (larger size) and eventually harden the exoskeleton. For insects, and particularly for the fruit fly, Drosophila much is known about the hormones involved in these processes, and in particular, the hormones called crustacean cardioactive peptide and bursicon are particularly well studied. For crustaceans hardly anything is known, despite the fact that crustacean cardioactive peptide was, as its name suggests firstly found in crabs! With regard to bursicon, absolutely nothing was known until very recently, when I discovered genes encoding similar 'bursicon-like' hormones in crabs. However, we do not know much about how these hormones work, or their functions in crustaceans, and since aquatic crustaceans (i.e. crabs) and insects (i.e.flies) have very different lifestyles, it would be fascinating to determine how these hormones work and interact during ecdysis. This will be done by determining the hormones' distribution and levels in the nerve cells in the central nervous system of the crab, and how they are released during ecdysis by measuring patterns of release using highly sensitive assay techniques to determine the vanishingly small amounts of hormones released at precisely timed stages of emergence from the old exoskeleton, and as the new one develops and hardens. I will also use a powerful technique called 'RNA interference' (the founders of this technique have just been awarded a Nobel prize), to reduce the amount of hormones and/or the levels of gene expression (bursicon and crustacean cardioactive peptide) present in the crabs nervous system during moulting, or reduce the numbers of bursicon receptors in the crabs skin (the target tissue for bursicon in insects), to see if I can disrupt the normal moulting pattern and behaviour of the animal, thus shedding light on the functions of the hormones. Finally, I will try to 'rescue' these abnormal moulting patterns by injecting the hormones, or pharmacological agents involved in transmitting the hormonal signal to the cellular machinery involved in producing the new exoskeleton, and observing subsequent events during and after moulting. In this way, a much more detailed understanding of an exquisitely complex process- ecdysis- can be obtained. This will not only allow us to compare differences in the way these hormones act between the two largest arthropod groups, but also may in the future, allow manipulation of moulting in economically important crustaceans, to maximise yield in an economically sustainable way.