昆虫神经肽allatostatin与allatotropin的研究新近展

昆虫神经肽ａｌｌａｔｏｓｔａｔｉｎ与ａｌｌａｔｏｔｒｏｐｉｎ的研究新近展关雪辰（中国科学院动物研究所北京１０００８０）昆虫神经激素是肽类激素，它控制昆虫许多关键的生理过程，例如生长、变态、生殖和行为等。保幼激素（ＪＨ）对昆虫的卵子发生成熟起着重要的调...

昆虫Allatostatin神经肽的生物信息学分析

根据已报道的昆虫咽侧体抑制激素(Allatostatin,AS)神经肽序列,基于转录组和基因组学数据库,通过同源性比较分别查找到53、33、57和35种昆虫的AS-A、AS-B、AS-C和AS-CC前体氨基酸序列,并对这些AS前体序列进行系统发育树的构建及分析。结果表明,昆虫AS-A、AS-B、AS-C和AS-CC分别在各自的进化分支上,且AS-C和AS-CC之间的亲缘关系较近,AS-A是最早分化出来的。在4种AS的进化树中,不同种类昆虫间的亲缘关系不尽相同。其中在AS-C进化树中,除了膜翅目,完全变态类昆虫都在一个进化分支,而膜翅目和不完全变态类昆虫在一个进化分支。在AS-CC进化树中,发现鳞翅目和双翅目分别在一个进化分支上,而膜翅目、鞘翅目和不完全变态类昆虫在一个进化分支上。目前尚未找到鞘翅目昆虫的AS-A序列和膜翅目昆虫的AS-B序列。

Exploring the N-terminus region： Synthesis, bioactivity and 3D-QSAR of allatostatin analogs as novel insect growth regulators

Allatostatins （ASTs）, a family of insect neuropeptide, can inhibit juvenile hormone （JH） biosynthesis by the corpora allata （CA） in Diploptera punctata, and therefore be regarded as potential leads for the discovery of new insect growth regulators （1GRs）. But several shortcomings, such as their sensitivity to peptidases and high cost, impeded their practical application in pest management. In order to discover new IGRs, one AST analog B1 possessing non-peptide group was discovered with high ability to inhibit JH biosynthesis in vitro （IC50： 0.09 μmol/L） in our previous studies. In the present work, two series of B1 analogs with different substituents on the N-terminus region were designed and synthesized. The result suggested that benzene showed better activity than other heterocycles, and the para-substitution on the benzene was beneficial for activity. Moreover, analogs with logP value over 2.0 exhibited good activity, which indicated the hydrophobicity is important to the bioactivity. Three dimension quantitative structure-activity relationship （3D-QSAR） studies were performed to highlight the structural require- ments of ASTanalogs, which demonstrated introduction of bulkier substituents on the N-terminus would increase the activity. Analog Ⅱ12 （IC50： 0.08 μmol/L） exhibited similar inhibitory activity to the lead B1, but its synthetic route was simpler than B1. Therefore, Ⅱ12 could be used as a new lead compound for the discovery eco-friendly IGRs.

Larval feeding status regulates the transcript levels of genes encoding PTTH and allatoregulatory peptides in silkworm Bombyx mori

In Bombyx mori,two dorsolateral neurosecretory cells(NSCs)in each of thetwo brain lobes have been identified as prothoracicotropic hormone(PTTH)producingcells.This neuropeptide in insects stimulates the prothoracic gland for the synthesis andrelease of ecdysone,responsible for the molting events.Allatotropin(AT)and allatostatin(AST)are allatoregulatory neuropeptides that regulate juvenile hormone biosynthesis.Here,by using RT-qPCR,we showed that in B.mori,nutritional stress modulates themRNA expression of AT and AST-C(allatostain type C)in the central nervous systemconsisting of the brain lobes and all the associated ganglia.Using whole-mount in situhybridization,we showed that the feeding status of Bombyx larvae also influences the ex-pression of PTTH in the NSCs of the brain.Food deprivation significantly decreased themRNA expression levels of PTTH in larvae at active or terminal growth period.Further,we showed that insulin modulates the expression level of PTTH.However,its action wasdependent on the feeding status of the larvae.At feeding,the insulin decreased the PTTHexpression level,while at food deprivation,the insulin increased the PTTH expressionlevel.The data thus indicates that larval feeding status plays an important role in alteringthe mRNA expression levels of allatoregulatory peptide genes and PTTH.

Synthesis, bioactivity and functional evaluation of linker-modified allatostatin analogs as potential insect growth regulators

Insect growth regulators play an important role in integrated pest management strategies.The FGLa–allatostatins（ASTs）are a family of neuropeptides that can inhibit juvenile hormone（JH）biosynthesis by the corpora allata（CA）of Diploptera punctata in vitro,are regarded as insect growth regulator candidates.In the search for new potential mimics and to explore the effect of linker length on inhibiting JH biosynthesis,a series of AST analogs were synthesized by modifying the linker of K24,which was found to have a significant effect on JH biosynthesis in vitro in our previous study.Functional evaluation demonstrated that all the target compounds can activate the Dippu-Ast R,albeit with different potencies.Analog L6 with the longest linker（n=5）,exhibited not only a promising effect on inhibition of JH biosynthesis both in vitro and in vivo,but also good activity in inhibiting basal oocyte growth.Structure–activity relationships（SAR）studies showed that longer linkers provided greater contribution to activity.

Primal structure and activity studies of allatostatin 4 (AST 4)

The juvenile hormones (JH) are critical to the contro1 of insect development andreproduction. The production of JH by the corpora allata (CA) is regulatd in part bypeptides originating from brain. One group of these peptides termed allatostatins (AST)reversibly inhibits the biosynthesis of JH invitro. The correlation of these events suggeststhat AST, i.e. their biosynthesis, are important in the regulation of JH biosynthesis.