Ascophyllum and its symbionts: cell biology, ecology and resource management

泡叶藻及其共生体：细胞生物学、生态学和资源管理

• 批准号: RGPIN-2015-04828
• 负责人: Garbary, David
• 金额: $ 1.53万
• 依托单位: St. Francis Xavier University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=651528
• 关键词: Ascophyllum; its; symbionts; cell; biology

The research will focus on the biology of the brown, economically important seaweed, Ascophyllum nodosum, the dominant organism of the intertidal zone of much of Nova Scotia and cold-temperate coastlines of the North Atlantic Ocean.  The primary thrust of the research is to gain a deeper understanding of the symbiotic community hosted by A. nodosum and its role both in fundamental ecological processes operating in the intertidal zone, and the large-scale impact of  harvesting of this resource in eastern Canada.  While the symbiotic community comprises at least seven species (two brown algae, an ascomycete, two red algae, a diatom and an insect), this proposal will focus on three key members of the community: A. nodosum (the primary host), Mycophycias ascophylli (an obligate endophytic fungus universally present in A. nodosum) and Vertebrata lanosa (an epiphytic, host-specific red alga typically abundant on A. nodosum).  The research will characterize basic processes of growth and seasonal adaptations of A. nodosum and its symbionts in the context of the harvesting industry. Preliminary data suggests that the industry reported 20 tons ha-1 (ca. 25% of standing crop) harvested in southwestern Nova Scotia is a major underrepresentation of the biological impact of the biomass removal by at least 140% - this unaccounted for material is what would normally be contributed to the detrital food chain of coastal habitats.  This is derived from the biomass of reproductive structures, the removal of large fronds by wave action, and a newly discovered process of epidermal shedding in which an outer layer of material from the entire frond is shed at regular intervals into the environment as particulate and dissolved organic matter. The research will clarify the process of shedding from a physiological standpoint (i.e., the potential role of reactive oxygen species in the process) and its fine structural details, based on confocal, and transmission and scanning electron microscopy. The role of Mycophycias in the symbiosis and its role as a component in the primary commercial product will also be studied. This will be accomplished using two approaches: 1) bioassays with commercial and experimental extracts of A. nodosum, Pelvetia (a European relative that also hosts the fungus) and Fucus (without Mycophycias), and 2)  isolating cultures of the fungus itself, and evaluating extracts in similar bioassays. The latter approach is significant in that it may lead to industrially produced extracts with greater (or more specific) activity in resulting commercial products, and minimize the extent of the commercial wild harvest of Ascophyllum, which may be having a negative impact on coastal biodiversity and fertility.

这项研究将集中在具有重要经济价值的棕色海藻的生物学上，这种海藻是新斯科舍省大部分地区和北大西洋寒温带海岸线的潮间带的主要生物。该研究的主要目的是为了更深入地了解沙草共生群落及其在潮间带基本生态过程中的作用，以及加拿大东部这种资源的大规模采收的影响。虽然共生群落包括至少7种（2种褐藻，1种子囊菌，2种红藻，1种硅藻和1种昆虫），但本提案将重点关注该群落的3个关键成员：a . nodosum（主要寄主），m . ascophyia ascophylli（普遍存在于a . nodosum中的专性内生真菌）和脊椎动物（一种附生的，寄主特异性的红藻，通常大量存在于a . nodosum上）。本研究将在采收工业的背景下描述结瘤草及其共生体的生长和季节适应的基本过程。初步数据表明，该行业报告在新斯科舍省西南部收获了20吨每公顷（约占现有作物的25%），这是对生物质去除的生物影响的严重低估，至少有140% -这些未计算的材料通常会贡献给沿海栖息地的碎屑食物链。这源于生殖结构的生物量、波浪作用对大叶子的去除，以及新发现的表皮脱落过程，在这个过程中，整个叶子的外层物质以颗粒和溶解的有机物的形式定期脱落到环境中。本研究将基于共聚焦、透射和扫描电子显微镜，从生理学角度（即活性氧在该过程中的潜在作用）阐明脱落过程及其精细结构细节。还将研究菌体在共生中的作用及其作为主要商业产品的组成部分的作用。这将通过两种方法来完成：1)用a . nodosum, Pelvetia（也是真菌宿主的欧洲亲戚）和Fucus（不含霉菌）的商业和实验提取物进行生物测定，2)分离真菌本身的培养物，并在类似的生物测定中评估提取物。后一种方法意义重大，因为它可能导致工业生产的提取物在最终的商业产品中具有更大（或更具体）的活性，并最大限度地减少商业野生收获的范围，这可能对沿海生物多样性和肥力产生负面影响。