Endocrine scaffolds and peptide networks: How is the molt cycle and ecdysis programme controlled in crustaceans?

节肢动物是地球上最成功的多细胞生物，在多样性，物种数量和栖息地利用方面。可以说，它们是地球上最重要的生物;作为传粉者、害虫和疾病媒介，它们在生态系统中发挥着关键作用，但其中许多生物，例如甲壳类动物，是高价值的食物资源。它们的成功是由于它们的生长模式，这涉及到周期性的外骨骼脱落，以允许生长和发育。最近，已经有爆炸性的信息昆虫肽激素的性质，几种模式昆虫的遗传温顺性，基因组和转录组分析一起导致了戏剧性的，确实是根本性的进步，我们的知识的激素控制昆虫蜕皮程序。然而，相比之下，对甲壳类动物中的等效过程的了解要少得多。虽然节肢动物有着共同的祖先（已经分化超过500 mya），这在昆虫和甲壳类动物的许多肽和受体的相似性中得到了很好的反映，但其中一些在功能上存在分歧。当比较甲壳类动物和昆虫的蜕皮控制时，这一点得到了很好的说明：从旧的外骨骼（“蜕皮盒”）中出现的定型行为所涉及的核心组件是相似的，但驱动蜕皮激素合成增加的控制机制是完全不同的。我们最近发现了一种新的神经肽信号系统（corazonin- CRZ），其靶向蜕皮腺（Y-器官），这将完全重新评估甲壳动物蜕皮模型对蜕皮激素合成的控制。在这些（蜕皮前的开始和蜕皮），我们已经发现了一个肽和受体信号系统的诱人一瞥（蜕皮触发激素，ETH，和羽化激素，EH），其似乎与昆虫中的那些同源，但我们在甲壳类动物中没有功能信息。在该项目中，最重要的目的是揭示这里概述的蜕皮周期的三个阶段中涉及的神经肽/受体信号传导的复杂性，使用我们完善的螃蟹（Carcinus maenas）模型。首先，将调查CRZ信号的新作用，其拟议的作用，在控制行动的蜕皮抑制激素（MIH）和甲壳类高血糖激素CHH，这将可能是一个关键的控制进入蜕皮前。由于这些激素的受体还没有被确定，我们将通过单转录测序和生物信息学方法来确定和功能性地鉴定这些受体，由此将确定由Y器官表达的推定受体的全长转录序列，然后在异源表达系统中进行功能性“去孤儿化”。其次，我们将鉴定ETH和EH及其同源受体的肽信号传导途径和表达，这些受体迄今为止仅在昆虫中使用本文提到的方法已知。最后，我们的目标是发现这些激素信号系统在蜕皮的最终阶段的作用-蜕皮中使用有针对性的方法所涉及的精确整合的行为和激素级联。我们将通过改变这些激素的表达和/或释放时间来操纵或破坏蜕皮“盒”，这将涉及确定蜕皮过程中关键激素顺序释放的改变。拟议的研究将首先回答甲壳动物内分泌学中的大问题：蜕皮是如何控制的？此外，由于它是转化的，它对水产养殖具有直接的潜在应用和益处。我们建议，激素控制机制，我们确定在螃蟹模型，因为这些都是核心过程，直接翻译到虾养殖，那里几乎没有知识的功能特征的神经内分泌控制蜕皮。

Arthropods are the most successful multicellular organisms on earth, in terms of diversity, species number and habitat utilisation. Arguably, they are the most important on earth; providing key ecosystem roles, as pollinators, pests and vectors of disease, yet many, for example crustaceans, are high value food resources. Their success is due to their growth format, which involves periodic shedding of the exoskeleton to allow growth, and development. Recently, there has been an explosion of information regarding the nature of insect peptide hormones, and the genetic tractability of several model insect species, together with genome and transcriptome analyses has led to dramatic, indeed fundamental advances in our knowledge of the hormonal control of insect ecdysis programmes. However, in comparison, knowledge of the equivalent processes in crustaceans is far less well developed. Whilst arthropods share a common ancestry, (having diverged over 500mya), which is beautifully reflected in the similarity of many of the peptides and receptors of insects and crustaceans, there has been a divergence in function of a number of these. This is illustrated nicely when comparing molt control in crustaceans and insects: The core components involved in stereotyped behaviours involved in emergence from the old exoskeleton (the "ecdysis cassette") are similar, yet the control mechanisms that drive increases in molting hormone synthesis are entirely different. We have recently discovered a novel neuropeptide signalling system (corazonin- CRZ) which targets the molting gland (Y-organ) that will completely reappraise models of crustacean molting with regard to the control of ecdysteroid synthesis. In between these (premolt initiation and ecdysis), we have discovered tantalising glimpses of a peptide and receptor signalling system (ecdysis triggering hormone, ETH, and eclosion hormone, EH) which appears to be homologous to those in insects, but for which we have no functional information in crustaceans.In this project, the over-arching objective is to unravel the complexities of neuropeptide/receptor signalling involved in the three phases of the molt cycle outlined here, using our well established crab (Carcinus maenas) model. Firstly, will investigate the novel role of CRZ signalling in relation to its proposed role in controlling the action of the molt-inhibiting hormone (MIH) and crustacean hyperglycemic hormone CHH that will likely be a key control in entry into premolt. Since the receptors for these hormones have not been identified, we will identify and functionally characterise these by a single transcript sequencing and bioinformatics approach, whereby full length transcript sequences of putative receptors expressed by the Y-organ will be identified, followed by functional "deorphaning" in heterologous expression systems. Secondly, we will identify the peptide signalling pathway and expression of ETH and EH and their cognate receptors, which are thus far only known in insects using the approaches alluded to here. Finally we aim to discover the roles of these hormone signalling systems in the ultimate stage of molting- the precisely integrated behavioural and hormonal cascades involved in ecdysis using a targeted approach. We will manipulate or disrupt the ecdysis "cassette" by altering expression and/or timing of release of these hormones, which will involve determining alterations in the sequential release of key hormones during ecdysis.The proposed research will firstly answer the big question in crustacean endocrinology: How is ecdysis controlled? Furthermore, it has direct potential application and benefits to aquaculture, since it is translational. We propose that the hormonal control mechanisms that we identify in a crab model will, since these are core processes, be directly translatable to shrimp aquaculture, where there is almost no knowledge of functional characterised neuroendocrine control of ecdysis.