The Potent Respiratory System of Osedax mucofloris (Siboglinidae, Annelida) - A Prerequisite for the Origin of Bone-Eating Osedax?
The Potent Respiratory System of Osedax mucofloris (Siboglinidae, Annelida) - A Prerequisite for the Origin of Bone-Eating Osedax?
复制标题
Osedax mucofloris（Siboglinidae，Annelida）强大的呼吸系统 - 食骨食骨起源的先决条件？
作者：
Randi S. Huusgaard;B. Vismann;M. Kühl;M. Macnaugton;Veronica Colmander;G. Rouse;A. Glover;T. Dahlgren;K. Worsaae
Osedax是一种著名的食骨动物，广泛分布在太平洋和大西洋的鲸鱼福尔斯上。这些无肠环节动物包含内共生异养细菌在一个分支根系嵌入脊椎动物的骨头，而躯干和前须延伸到周围的水。骨环境中的独特生活方式受到骨基质上和骨基质内的高细菌活性的挑战，可能导致O2消耗和潜在有毒硫化物的积累。我们测量了包埋Osedax周围的O2分布，并表明骨微环境是缺氧的。形态学研究表明，Osedax的通气机制仅限于前须，前须通过具有大的表面积、大的表面积与体积比和短的扩散距离来优化高O2摄取。血管系统包括躯干中的大血管，其促进从前冠向高度血管化的根部结构供应充足的含氧血液。O. mucofloris显示出高的O2消耗，超过了没有内共生体的广泛的休眠环节动物的平均O2消耗。我们认为O. mucofloris作为适应其独特的营养策略，根嵌入缺氧的骨骼和由于需氧异养内共生体引起的O2需求升高。
Members of the conspicuous bone-eating genus, Osedax, are widely distributed on whale falls in the Pacific and Atlantic Oceans. These gutless annelids contain endosymbiotic heterotrophic bacteria in a branching root system embedded in the bones of vertebrates, whereas a trunk and anterior palps extend into the surrounding water. The unique life style within a bone environment is challenged by the high bacterial activity on, and within, the bone matrix possibly causing O2 depletion, and build-up of potentially toxic sulphide. We measured the O2 distribution around embedded Osedax and showed that the bone microenvironment is anoxic. Morphological studies showed that ventilation mechanisms in Osedax are restricted to the anterior palps, which are optimized for high O2 uptake by possessing a large surface area, large surface to volume ratio, and short diffusion distances. The blood vascular system comprises large vessels in the trunk, which facilitate an ample supply of oxygenated blood from the anterior crown to a highly vascularised root structure. Respirometry studies of O. mucofloris showed a high O2 consumption that exceeded the average O2 consumption of a broad line of resting annelids without endosymbionts. We regard this combination of features of the respiratory system of O. mucofloris as an adaptation to their unique nutrition strategy with roots embedded in anoxic bones and elevated O2 demand due to aerobic heterotrophic endosymbionts.