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褐藻ascopphylum nodosum的生物学上。这种藻类具有独特的生物学特性：它的寿命极长（可能长达100年），其生态环境使其成为北大西洋寒冷温带水域潮间带的基础物种。曲霉属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（脊椎动物，多sisiphoniae），一种系统专性真菌（曲霉）和兼性附生褐藻（Elachista fucicola）及其伴生海洋昆虫（Halocladius variabilis）。我的工作主要涉及发展对共生关系的理解，以及这个群落的各个组成部分所扮演的生态角色，以及与它们的相互作用和允许这个群落持续存在的生理特征相关的生物过程。我实验室以前的生态学工作强调了对细胞生物学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，并在纯研究和应用研究的背景下将其纳入对褐藻细胞壁的更全面的了解。一项研究内容将探讨从褐藻中提取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。这将通过比较三种相关岩藻类物种的商业和“自制”提取物来完成，其中两种（Ascophyllum和Pelvetia canaliculata）具有相同的真菌内共生体，而另一种（Fucus vesiculosus）没有。一些共生体（即脊椎动物、Elachista和分枝菌）穿透宿主组织，造成轻微到严重的损害，包括局部细胞死亡和宿主组织的主要溶解。这些过程将探索使用免疫标记和电子显微镜来评估在改变细胞壁结构和组成的背景下物种之间的相互作用。尽管它的营养菌体寿命很长，但在外菌体壁的脱落和再生过程中，藤蔓仍在不断地分解和改造其细胞壁。每年，这释放了大约10%的生物量作为碎屑。这种蜕皮过程发生在所有营养轴和生殖结构上。诱发蜕皮的化学诱因将是这项工作的重点。此外，在生殖体（即花托）的成熟过程中，茎条主要发生壁溶解。本研究将通过细胞壁破坏和细胞程序性死亡的细胞生物学研究成熟过程。

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.