关键词： AIC Akaike Information Criterion BEB Bayes Empirical Bayes CHH CPP Clade Posterior Probability Crustacean Hyperglycemic Hormone DNA complementary to RNA EST Expressed Sequence Tag(s) FEL FUBAR Fast Unbiased Bayesian AppRoximation GTR+I+G Generalized Time Reversible plus Gamma plus Invariant model ICK ITP Inhibitor Cystine Knot Ion Transport Peptide LRT Latrodectin Latrodectus MEME ML Mixed Effects Model of Episodic Diversifying Selection Molecular evolution NCBI National Center for Biotechnology Information Phylogeny RTA RTA clade Random Taxon Additions Retrolateral Tibial Apophysis clade SLAC TPM3uf+I+G Venom aa amino acid(s) base pair(s) bp cDNA d(N) d(S) double strand(ed) ds fixed effects likelihood likelihood ratio test maximum likelihood nonsynonymous substitutions per nonsynonymous site single-likelihood ancestor counting synonymous substitutions per synonymous site three parameter with unequal base frequencies plus gamma plus Invariant model α-Latrotoxin LMWPs α-latrotoxin associated low molecular weight proteins

Mesh ： Amino Acid Sequence Animals Black Widow Spider / genetics Insect Proteins / genetics Molecular Sequence Data Neuropeptides / genetics Phylogeny Sequence Alignment Spider Venoms / genetics

来  源：   DOI：10.1016/j.gene.2013.11.054   PDF(Pubmed)

Abstract：
Venoms have attracted enormous attention because of their potent physiological effects and dynamic evolution, including the convergent recruitment of homologous genes for venom expression. Here we provide novel evidence for the recruitment of genes from the Crustacean Hyperglycemic Hormone (CHH) and arthropod Ion Transport Peptide (ITP) superfamily for venom expression in black widow spiders. We characterized latrodectin peptides from venom gland cDNAs from the Western black widow spider (Latrodectus hesperus), the brown widow (Latrodectus geometricus) and cupboard spider (Steatoda grossa). Phylogenetic analyses of these sequences with homologs from other spider, scorpion and wasp venom cDNAs, as well as CHH/ITP neuropeptides, show latrodectins as derived members of the CHH/ITP superfamily. These analyses suggest that CHH/ITP homologs are more widespread in spider venoms, and were recruited for venom expression in two additional arthropod lineages. We also found that the latrodectin 2 gene and nearly all CHH/ITP genes include a phase 2 intron in the same position, supporting latrodectin\'s placement within the CHH/ITP superfamily. Evolutionary analyses of latrodectins suggest episodes of positive selection along some sequence lineages, and positive and purifying selection on specific codons, supporting its functional importance in widow venom. We consider how this improved understanding of latrodectin evolution informs functional hypotheses regarding its role in black widow venom as well as its potential convergent recruitment for venom expression across arthropods.
摘要：
毒液由于其强大的生理效应和动态进化而引起了极大的关注，包括用于毒液表达的同源基因的趋同募集。在这里，我们为甲壳动物高血糖激素（CHH）和节肢动物离子运输肽（ITP）超家族招募基因以在黑寡妇蜘蛛中表达毒液提供了新的证据。我们从西方黑寡妇蜘蛛（Latrodectushesperus）的毒腺cDNA中鉴定了latrodectin肽，棕色寡妇（Latrodectusgeometricus）和橱柜蜘蛛（Steatodagrossa）。这些序列与其他蜘蛛同源物的系统发育分析，蝎子和黄蜂毒液cDNA，以及CHH/ITP神经肽，将latrodectin显示为CHH/ITP超家族的衍生成员。这些分析表明，CHH/ITP同源物在蜘蛛毒液中更广泛，并招募了另外两个节肢动物谱系的毒液表达。我们还发现latrodectin2基因和几乎所有的CHH/ITP基因在同一位置包含2相内含子，支持latrodectin在CHH/ITP超家族中的放置。latrodectin的进化分析表明，沿某些序列谱系的阳性选择发作，以及特定密码子的阳性和纯化选择，支持其在寡妇毒液中的功能重要性。我们考虑这种对latrodectin进化的改进理解如何为其在黑寡妇毒液中的作用以及其在节肢动物中毒液表达的潜在趋同招募提供功能假设。
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