Cell walls and symbioses of the economically important brown seaweed Ascophyllum nodosum

在过去的30年里，我的研究主要集中在经济上重要的棕色海藻节瘤海藻的生物学上。这种藻类具有独特的生物学特性：它的寿命非常长(可能是100年)，而且它的生态使它成为整个北大西洋寒冷温带水域潮间带的基础物种。羊肚菌是一个复杂共生群落的主要宿主，该群落包括两种专性红藻(Vertebrata lanosa和Choreocolax Polysiphoniae)、一种全身性专性真菌(Mycophycias Ascophylli)和一种兼性附生褐藻(Elachista Fucicola)及其伴生海洋昆虫(Halocladius Varablis)。我的工作在很大程度上涉及到对这个群落的各个组成部分所扮演的共生联系和生态角色的理解，以及与它们的相互作用相关的生物过程和使这个群落得以持续存在的生理特征。 我实验室以前的生态学工作强调了在细胞生物学方面进行更多基础研究的必要性。这项研究将利用以前成功使用的技术，包括透射电子显微镜和共聚焦显微镜。这项工作将强调褐藻细胞壁的细胞生物学，并将其整合到在纯研究和应用研究的背景下对褐藻细胞壁的更全面的理解中。其中一个研究部分将讨论从褐藻衍生的商业产品的特性是否确实基于褐藻，或者它们是否来自共生真菌。这将通过比较商业和自制的三种相关岩藻的提取物来完成，其中两个物种(ascophyllum和Pelvetia canalulata)具有相同的真菌内共生体，而一个物种(Fucus Vesillosus)没有相同的真菌内共生体。几种共生菌(即脊椎动物门、埃拉基斯塔菌和霉菌属)穿透宿主组织，造成轻微到主要的损害，包括局部细胞死亡和宿主组织的主要溶解。将使用免疫标记和电子显微镜来探索这些过程，以在改变细胞壁结构和组成的背景下评估物种之间的相互作用。 尽管它的营养叶状体寿命很长，但在外部叶状体的脱落和再生过程中，子囊菌不断地破坏和重建其细胞壁。每年，这会释放出约10%的站立生物量作为碎屑。这一下垂过程发生在所有营养轴和生殖结构上。导致松弛的化学诱因将是这项工作的重点。此外，在生殖体(即花托)成熟期间，子囊经历了主要的壁溶解。本研究将通过细胞壁破裂和程序性细胞死亡的细胞生物学来研究成熟过程。

For the last 30 years my research has had a primary focus of the biology of the economically important brown seaweed Ascophyllum nodosum. This alga has unique biological properties: it is both extremely long-lived (potentially 100 years), and has an ecology that makes it a foundation species in the intertidal zone throughout the cold temperate waters of the North Atlantic Ocean. Ascophyllum is the primary host of a complex symbiotic community that includes two obligate red algae (Vertebrata lanosa, Choreocolax polysiphoniae), a systemic obligate fungus (Mycophycias ascophylli), and a facultative epiphytic brown algae (Elachista fucicola) with its associated marine insect (Halocladius variabilis). My work has largely involved developing an understanding of the symbiotic associations and the ecological roles played by individual components of this community, and the biological processes associated with their interactions and physiological features that allow this community to persist. Previous ecological work in my laboratory highlighted the need for more fundamental studies in cell biology. This research will make use of techniques successfully used previously, including transmission electron microscopy and confocal microscopy. The work will emphasize the cell biology of brown algal cell walls, and integrate this into a more comprehensive understanding of brown algal cell walls in the context of both pure and applied research. One research component will address whether or not the properties of commercial products derived from the brown alga are indeed based on the brown alga, or whether they are derived from the symbiotic fungus. This will be done by comparing commercial and home-made' extracts of three related fucoid species of which two species (Ascophyllum and Pelvetia canaliculata) have the same fungal endosymbiont, and one species which does not (Fucus vesiculosus). Several of the symbionts (i.e. Vertebrata, Elachista and Mycophycias) penetrate the host tissue and cause minimal to major damage including localized cell death, and major dissolution of host tissue. These processes will be explored using immunolabelling and electron microscopy to evaluate interactions between species in the context of changing cell wall structure and composition. Despite its long-lived vegetative thallus, Ascophyllum is continuously breaking down and reforming its cell walls in a process of sloughing and regeneration of the external thallus wall. Annually, this releases about 10% of the standing biomass as detritus. This sloughing process occurs on all vegetative axes and reproductive structures. The chemical triggers that induce sloughing will be a focus of this work. In addition, during maturation of reproductive bodies (i.e. receptacles) Ascophyllum undergoes major wall dissolution. This research will investigate the maturation process by focusing on the cell biology of cell wall breakdown and programmed cell death.