Evolution of pattern formation in insects

寄生黄蜂Copidosoma floridanum(CF)的多胚胎发育是最极端的发育形式之一，其中2000个胚胎是从一个受精卵克隆产生的，表现出一种激进的强制性胚胎单卵双胞胎。此外，这种黄蜂从同一受精卵产生两种形态上不同的克隆种姓：1)化蛹并产生成年黄蜂的生殖种姓；2)不育的士兵种姓，用于保护生殖兄弟姐妹不受竞争对手的伤害，并在改变性别比例方面发挥作用。这种复杂的发育程序和克隆种姓生产是对群居昆虫发育进化和种姓指定的其他例子中的概念的挑战。*我们已经完成了CF基因组的全基因组测序、组装和注释。在这项建议中，我们建议探索以基因组甲基化为重点的表观遗传变化在这种黄蜂发育进化中的作用。我们的初步分析证实了CF基因组甲基化的特征，我们发现了甲基转移酶DNMT3蛋白家族中前所未有的基因增殖，表明表观遗传变化在这种发育模式的进化中发挥了重要作用。在这项应用中，我们建议：*1)进行全基因组亚硫酸氢盐测序，以确定碱基分辨率下的甲基化胞嘧啶并研究DNA甲基化模式*2)使用RNAseq对不同发育阶段的转录组谱进行分析，以了解甲基化与基因表达之间的关系*3)使用甲基化激动剂和甲基化拮抗剂进行操纵性实验，以确定改变基因组甲基化对发育的功能影响，并对目标上调和甲基化基因进行RNAi*这项研究的影响将包括基础科学、新基因组资源的生成、基因组浏览器的研究以及应用于生物病虫害防治的知识。基础知识将剖析基因组甲基化在昆虫发育和基因调控中的作用。此外，它还将揭示复杂的发展进化和发展新颖性的进化机制。CF基因组、甲基组和操纵实验将为研究社会昆虫进化和社会基因组学提供重要资源，为回答这一领域的关键问题提供工具：保守的遗传途径是否重复地被招募到与社会特征相关的功能角色？基因组结构如何影响种姓偏向的基因表达和表型新颖性？新基因在优惠性的起源和阐述中扮演了什么角色？工蚁的表型是真社会昆虫进化新颖性的来源吗？该计划还将为HQP提供出色的培训。

Polyembryonic development in the parasitic wasp Copidosoma floridanum (Cf) represents one of most extreme forms of development, where 2000 embryos are clonaly produced from a single zygote, exhibiting a radical form of obligatory embryo monozygotic twinning. Furthermore, this wasp produces two morphologically different clonal castes from same zygote: 1) a reproductive caste that pupate and produce adult wasps and 2) a soldier caste that is sterile and serves to defend the reproductive siblings from competitors and plays a role in modification of sex ratio. This type of complex developmental program and clonal caste production represents a challenge to the concepts in the evolution of development and other examples of caste specification in social insects. ******We have already performed whole genome sequencing, assembly and annotation of the Cf genome. In this proposal we propose to explore the role of epigenetic changes focusing on genome methylation in the evolution of development of this wasp. Our preliminary analysis confirmed hallmarks of genome methylation in Cf and we discovered unprecedented proliferation of genes in the DNMT3 protein family of methyltransferases, suggesting that epigenetic changes play an important role in evolution of this mode of development. In this application we propose to: ***1) Perform whole genome bisulfite sequencing of Cf to determine methylated cytosines at basepair resolution and study DNA methylation patterns***2) Perform transcriptome profiling of different developmental stages using RNAseq to gain insight into relationship between methylation and gene expression***3) Perform manipulative experiments using agonists and antagonists of methylation to determine the functional effects of altering genome methylation on development and perform RNAi on the target upregulated and methylated genes******The impact of this research will include fundamental science, generation of new genomic resources, genome browser for research community and applied knowledge applicable to the biological pest control. The fundamental knowledge will dissect the role of genome methylation on development and gene regulation in insects. In addition, it will uncover mechanisms of complex developmental evolution and evolution of developmental novelty. The Cf genome, methylome and manipulative experiments will provide important resources for study of social insect evolution and sociogenomics offering tools to answer key questions in this area: Are conserved genetic pathways repeatedly recruited into functional roles associated with social traits? How does genome architecture influence caste-biased gene expression, and phenotypic novelty? What is the role of novel genes in the origins and elaborations of eusociality? Is the worker phenotype the source of evolutionary novelty in eusocial insects? This program will also provide an outstanding training for HQPs.