Cellular stress responses in the evolution of multicellular complexity

多细胞复杂性进化中的细胞应激反应

• 批准号: 222935-2013
• 负责人: Nedelcu, Aurora
• 金额: $ 3.13万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=523879
• 关键词: Cellular; stress; responses; evolution; multicellular

Our research program addresses one of the most challenging topics in evolutionary biology - the evolution of complexity. The emergence of new levels of complexity in multicellular lineages was contingent on the evolution of non-reproductive (somatic) cells. However, despite its significance, the mechanistic basis for the evolution of soma is not well understood in any lineage. To address this important question, we are using a group of green algae (the Volvocales) that comprises both unicellular (e.g, Chlamydomonas) and multicellular species (e.g., Volvox) with various levels of complexity. In Volvox carteri, a single gene - regA - is necessary and sufficient to establish the somatic cell fate. We have previously hypothesized that the evolution of soma involved the co-option of pathways that allow unicellular organisms to adaptively respond to various stress factors by investing in survival at a cost to immediate reproduction. The general objective of this research is to elucidate the mechanistic basis for the co-option of stress responses into developmental pathways during the evolution of multicellularity in Volvocales. Specifically, we want to address how the developmental regulation of regA might have evolved. We will pursue several complementary objectives and methodological approaches. (i) Identify upstream components of the signal transduction pathway associated with the induction of regA during environmental stress. (ii) Test if these signals/pathways are also involved in the developmentally-regulated induction of regA. (iii) Identify regulatory elements responsible for regA expression using bioinformatics and a yeast one-hybrid system (to probe for potential interactions between the predicted regulatory sequences and their postulated binding factors). The proposed research provides a new framework to address the evolution of soma and multicellular complexity based on the co-option of pre-existing responses to stress. This research also address several other important topics, including the contribution of cis-regulatory elements to the evolution of morphological traits, the mechanism(s) underlying gene co-option and functional diversification, and how differences in cell size translate into differential gene expression.

我们的研究计划解决了进化生物学中最具挑战性的课题之一-复杂性的进化。多细胞谱系中新的复杂性水平的出现取决于非生殖（体细胞）细胞的进化。然而，尽管它的重要性，索马的进化机制的基础是没有很好地理解在任何血统。为了解决这个重要的问题，我们正在使用一组绿色藻类（团藻目），包括单细胞（例如，衣原体）和多细胞物种（例如，团藻）具有不同程度的复杂性。在团藻中，一个单一的基因- regA -是必要的，足以建立体细胞的命运。我们以前假设，索马的进化涉及的共同选择的途径，使单细胞生物适应性地应对各种压力因素，投资于生存的成本立即繁殖。本研究的总体目标是阐明在团藻目多细胞生物进化过程中，胁迫反应进入发育途径的机制基础。具体来说，我们想解决regA的发育调控可能已经演变。我们将努力实现几个相辅相成的目标和方法。(i)确定上游组件的信号转导通路与诱导regA在环境压力。(ii)测试这些信号/通路是否也参与regA的发育调节诱导。(iii)使用生物信息学和酵母单杂交系统鉴定负责regA表达的调控元件（以探测预测的调控序列与其假定的结合因子之间的潜在相互作用）。该研究为解决索马和多细胞复杂性的进化提供了一个新的框架，该框架基于预先存在的应激反应的协同选择。这项研究还涉及其他几个重要的主题，包括顺式调控元件对形态性状进化的贡献，基因协同选择和功能多样化的机制，以及细胞大小的差异如何转化为差异基因表达。