Kahn Amanda S, Leys Sally P
Department of Biological Sciences , University of Alberta , Edmonton, Alberta , Canada T6G 2E9.
R Soc Open Sci. 2016 Nov 30;3(11):160484. doi: 10.1098/rsos.160484. eCollection 2016 Nov.
Benthic-pelagic coupling through suspension feeders and their detrital pathways is integral to carbon transport in oceans. In food-poor ecosystems however, a novel mechanism of carbon recycling has been proposed that involves direct uptake of dissolved carbon by suspension feeders followed by shedding of cells as particulate carbon. We studied cell replacement rates in a range of cold-water sponge species to determine how universal this mechanism might be. We show that cell replacement rates of feeding epithelia in explants vary from 30 hours up to 7 days, and change during different seasons and life-history stages. We also found that feeding epithelia are not replaced through direct replication but instead arise from a population of stem cells that differentiate and integrate into epithelial tissues. Our results reveal a surprising amount of complexity in the control of cell processes in sponges, with cell turnover depending on environmental conditions and using stem cells as rate-limiting mechanisms. Our results also suggest that for species in cold water with high particulate organic matter, cell turnover is not the mechanism delivering carbon flux to surrounding communities.
通过悬浮摄食者及其碎屑路径实现的底栖-水层耦合是海洋中碳运输的重要组成部分。然而，在食物匮乏的生态系统中，有人提出了一种新的碳循环机制，即悬浮摄食者直接摄取溶解碳，随后以颗粒碳的形式排出细胞。我们研究了一系列冷水海绵物种的细胞更替率，以确定这种机制的普遍程度。我们发现，外植体中摄食上皮细胞的更替率从30小时到7天不等，并且在不同季节和生活史阶段会发生变化。我们还发现，摄食上皮细胞不是通过直接复制来替换，而是来自一群干细胞，这些干细胞分化并整合到上皮组织中。我们的研究结果揭示了海绵细胞过程控制中惊人的复杂性，细胞更新取决于环境条件，并将干细胞用作限速机制。我们的研究结果还表明，对于颗粒有机物含量高的冷水物种，细胞更新不是向周围群落输送碳通量的机制。
