Physiological and Molecular Mechanisms of Stress Tolerance in a Polar Insect

极地昆虫应激耐受的生理和分子机制

• 批准号: 0413786
• 负责人: David Denlinger
• 金额: $ 28.81万
• 依托单位: Ohio State University Research Foundation -DO NOT USE
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0413786&HistoricalAwards=false
• 关键词: Physiological; Molecular; Mechanisms; Stress; Tolerance

Polar terrestrial environments are often described as deserts, where water availability is recognized as one of the most important limits on the distribution of terrestrial organisms. In addition, prolonged low winter temperatures threaten survival, and summer temperatures challenge organisms with extensive diel variations and rapid transitions from freezing to desiccating conditions. Global warming has further impacted the extreme thermal and hydric conditions experienced by Antarctic terrestrial plant and arthropod communities, especially as a result of glacial retreat along the Antarctic Peninsula. This research will focus on thermal and hydric adaptations in the terrestrial midge, Belgica antarctica, the largest and most southerly holometabolous insect living in this challenging and changing environment. Overwintering midge larvae encased in the frozen substrate must endure desert-like conditions for more than 300 days since free water is biologically unavailable as ice. During the summer, larvae may be immersed in melt water or outwash from penguin colonies and seal wallows, in addition to saltwater splash. Alternatively, the larvae may be subjected to extended periods of desiccation as their microhabitats dry out. Due to their small size, relative immobility and the patchiness of suitable microhabitats, larvae may thus be subjected to stresses that include desiccation, hypo- or hyperosmotic conditions, high salinity exposure, and anoxia for extended periods. Research efforts will focus in three areas relevant to the stress tolerance mechanisms operating in these midges:(1) obtaining a detailed characterization of microclimatic conditions experienced by B. antarctica, especially those related to thermal and hydric diversity, both seasonally and among microhabitat types in the vicinity of Palmer Station, Antarctica; (2) examining the effects of extreme fluctuations in water availability and effects on physiological and molecular responses - to determine if midge larvae utilize the mechanism of cryoprotective dehydration for winter survival, and if genes encoding heat shock proteins and other genes are upregulated in larval responses to dehydration and rehydration; (3) investigating the dietary transmission of cryoprotectants from plant to insect host, which will test the hypothesis that midge larvae acquire increased resistance to desiccation and temperature stress by acquiring cryoprotectants from their host plants. This project will provide outreach to both elementary and secondary educators and their students. The team will include a teacher who will benefit professionally by full participation in the research, and will also assist in providing outreach to other teachers and their students. From Palmer Station, the field team will communicate daily research progress by e-mail supplemented with digital pictures with teachers and their elementary students to stimulate interest in an Antarctic biology and scientific research. These efforts will be supplemented with presentations at local schools and national teacher meetings, and by publishing hands-on, inquiry-based articles related to cryobiology and polar biology in education journals. Furthermore, the principal investigators will maintain major commitments to training graduate students and postdoctoral scholars, as well as undergraduate students by providing extended research experience that includes publication of scientific papers and presentations at national meetings.

极地陆地环境通常被描述为沙漠，其中水资源被认为是陆地生物分布的最重要限制之一。此外，冬季长期低温威胁着生存，而夏季气温则对生物体提出了广泛的昼夜变化和从冰冻条件到干燥条件的快速转变的挑战。全球变暖进一步影响了南极陆地植物和节肢动物群落所经历的极端高温和水分条件，特别是由于南极半岛沿线冰川退缩。这项研究将重点关注陆地蠓（Belgica antarctica）的热和水分适应，这是生活在这个充满挑战和变化的环境中的最大、最南端的全变态昆虫。包裹在冰冻基质中的越冬蠓幼虫必须忍受类似沙漠的条件超过 300 天，因为在生物学上，自由水无法以冰的形式获得。在夏季，除了盐水飞溅之外，幼虫还可能浸入融水中或从企鹅群和海豹的泥沼中冲走。或者，当幼虫的微生境变干时，它们可能会经历长时间的干燥。由于其体型小、相对固定以及适宜的微生境的分散性，幼虫因此可能会受到包括干燥、低渗或高渗条件、高盐度暴露和长时间缺氧在内的应激。研究工作将集中在与这些蠓的应激耐受机制相关的三个领域：(1) 获得南极洲蠓所经历的小气候条件的详细特征，特别是那些与季节性和微生境类型之间的热量和水分多样性相关的特征。南极洲帕尔默站附近； (2) 检查可用水量极端波动的影响以及对生理和分子反应的影响 - 确定蠓幼虫是否利用冷冻保护脱水机制来维持冬季生存，以及编码热休克蛋白的基因和其他基因在幼虫反应中是否上调脱水和补液； (3) 研究冷冻保护剂从植物到昆虫宿主的饮食传播，这将检验蠓幼虫通过从宿主植物获取冷冻保护剂来增强对干燥和温度胁迫的抵抗力的假设。该项目将为中小学教育工作者及其学生提供外展服务。该团队将包括一名教师，他将通过全面参与研究而在专业上受益，并将协助向其他教师及其学生提供外展服务。从帕尔默站，现场团队将通过电子邮件与教师和小学生交流日常研究进展，并辅以数码图片，以激发他们对南极生物学和科学研究的兴趣。这些努力将得到在当地学校和全国教师会议上的演讲以及在教育期刊上发表与低温生物学和极地生物学相关的实践性、探究性文章的补充。此外，主要研究人员将继续致力于培养研究生和博士后学者以及本科生，提供扩展的研究经验，包括发表科学论文和在国家会议上的演讲。