Collaborative Research: A Matter of Life or Death? Assessing the physiological roles of PCD-related genes to stress adaptation in diatoms

合作研究：生死攸关？

• 批准号: 0927829
• 负责人: Kay Bidle
• 金额: $ 70.79万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0927829&HistoricalAwards=false
• 关键词: Collaborative; Research; Matter; Life; Death

Diatoms are a class of unicellular phytoplankton that account for ~40% of total marine primary productivity in the modern ocean. Since downward fluxes of biogenic silica and organic matter in the modern ocean derive largely from diatom productivity, there is increased interest in the mechanistic processes that regulate their fate. Indeed, the physiological state and life history of diatom assemblages dictate whether diatom Si and its associated organic C are either recycled in the euphotic zone, or exported to depth, placing mechanistic importance on cellular processes mediating bloom to post-bloom transition in response to nutrient stress. Programmed cell death (PCD) triggered by specific environmental stresses (e.g., Fe starvation, viral infection, high light, oxidative stress, and UV exposure) has now been documented in a variety of prokaryotic and eukaryotic unicellular phytoplankton, including diatoms. It provides a mechanistic framework to help explain lysis rates independent of grazing. The expression and activation of metacaspases, putative death proteases, in stressed diatoms, suggest PCD is an integral pathway in these organisms. Currently, the ecological role(s) of PCD-related genes in unicellular phytoplankton and the evolutionary drivers selecting for their retention remain unknown. Their preservation would seem to provide a negative selection pressure, yet their retention and maintenance suggests some sort of ancient, selective advantage. Metacaspases (and other PCD-related genes) may have co-evolved with other metabolic pathways whereby retention and low-level expression served housekeeping or regulatory functions. Elucidation of the ecological role(s) of PCD-related genes, like metacaspases, in diatom field populations requires an understanding of cellular function(s) and induction under relevant stressors. The premise of this proposal is that a subset of putative, PCD-related genes plays heretofore-unappreciated roles in stress adaptation in marine diatoms. The PIs will investigate whether Fe and N availability differentially regulate their expression and activity in T. pseudonana and in coastal diatoms from the California coast. The researchers will elucidate whether distinct PCD-related genes confer increased fitness under Fe or under N-limitation. This research follows from the investigators previous results that a subset of PCD-related genes is differentially expressed in T. pseudonana cells in response to Fe stress. Specific hypotheses are: (1) Expression and activity of PCD-related genes are controlled by Fe or N availability; (2) Overexpression of putative PCD-related genes confers increased fitness under nutrient limitation; (3) Diverse T. psuedonana metacaspases share functional epitope similarities; and (4) PCD-related genes in coastal diatoms display differential responses to steady-state Fe and N limitation. This work integrates physiology, biochemistry, genetics, ultra-trace metal clean techniques and field-based sampling in order to elucidate the ecological function of metacaspases in diatoms and to identify their roles and regulation in natural diatom populations under Fe versus N limitation. This novel interdisciplinary approach is particularly suited to address the roles of these fascinating enzymes.This project will allow for continued professional development of two young PIs and provide an opportunity for a female, postdoctoral associate to get first time PI experience. The proposed project provides a forum for researchers with different educational backgrounds (undergraduate students, graduate students, technician, post-docs, and faculty) to interact and develop. This project provides excellent hands-on training for development of both graduate and undergraduate students and will strongly broaden the participation of women. Proposed research will also foster new national collaborations. Research activities will interface with the Mid-Atlantic Center for Ocean Science Education Excellence (MA-COSEE) and ongoing outreach programs that introduce urban, largely minority, children and families to marine science. The PIs will participate in an ongoing public lecture series at New Jersey's Liberty Science Center entitled "Pulse of the Planet" combined with 2-hour professional development workshop for K-12 teachers. Specific goals are to stimulate awareness of the immense diversity and large-scale importance of marine microbes to ocean function.

硅藻是一类单细胞浮游植物，占现代海洋总海洋初级生产力的约40％。由于现代海洋中生物二氧化硅和有机物的向下通量主要来自硅藻生产力，因此对调节其命运的机械过程的兴趣增加。实际上，硅藻组合的生理状态和生活历史决定了硅藻Si及其相关的有机C是否在舒适区中回收或导出到深度，使机械性的重要性在介导的蜂窝过程中介导了灌木丛，从而使花朵在植物后转变，以响应营养，以应对营养方面的响应，以应对营养。压力。现已记录在各种原核生物和真核生物单细胞浮游植物浮游生物中，已记录在包括特定的环境应力（例如Fe饥饿，病毒感染，高光，氧化应激和UV暴露）触发的程序性细胞死亡（PCD）（PCD）。它提供了一个机械框架，可以帮助解释与放牧无关的裂解率。压力硅藻在压力硅藻中的肠胃菜酶的表达和激活表明PCD是这些生物体中不可或缺的途径。当前，PCD相关基因在单细胞浮游植物中的生态作用和选择保留的进化驱动因素是未知的。他们的保存似乎会带来负面的选择压力，但是他们的保留和维护表明了某种古老的选择性优势。肠胃菜酶（和其他与PCD相关的基因）可能与其他代谢途径共同发展，在该途径中，保留和低级表达提供了管家或调节功能。在硅藻场种群中阐明PCD相关基因的生态作用（S）需要了解细胞功能和相关胁迫下的诱导。该提议的前提是，推定的，与PCD相关的基因的一部分在海洋硅藻中迄今为止扮演着迄今为止无关紧要的角色。 PI将调查Fe和N的可用性是否会差异地调节其在伪造的T. pseudonana和加利福尼亚海岸的沿海硅藻中的表达和活性。研究人员将阐明在Fe下或在N限制下赋予适应性增加的独特的基因。这项研究遵循研究者以前的结果，即PCD相关基因的子集响应于Fe胁迫而在假霉菌细胞中差异表达。特定的假设是：（1）PCD相关基因的表达和活性由Fe或N的可用性控制； （2）推定PCD相关基因的过表达在养分限制下赋予了增加的适应性； （3）各种T. suedonana metacaspases具有功能表位相似性； （4）沿海硅藻中与PCD相关的基因对稳态Fe和N限制显示出差异反应。这项工作集成了生理学，生物化学，遗传学，超痕迹金属清洁技术和基于现场的抽样，以阐明硅藻中掌酶在硅藻中的生态功能，并确定其在FE与N限制下在FE与FE的自然硅藻种群中的作用和调节。这种新颖的跨学科方法特别适合于解决这些引人入胜的酶的作用。该项目将允许对两个年轻的PIS进行持续的专业发展，并为女性的博士后同事提供机会获得首次PI体验。拟议的项目为具有不同教育背景的研究人员（本科生，研究生，技术人员，技术后和教职员工）提供了一个论坛，以进行互动和发展。该项目为研究生和本科生的发展提供了出色的动手培训，并将强烈扩大妇女的参与。拟议的研究还将促进新的国家合作。研究活动将与中大西洋中部海洋科学教育中心（MA-COSEE）和正在进行的外展计划进行互动，这些计划向海洋科学带来了城市，大部分少数民族，儿童和家庭。 PI将参加新泽西州自由科学中心的持续公开演讲系列，题为“地球的脉冲”，并为K-12教师提供2小时的专业发展研讨会。具体目标是刺激对海洋微生物对海洋功能的巨大多样性和大规模重要性的认识。