Department of Finemechanics, Graduate School of Engineering, Tohoku University, 6-6-01 Aramaki Aza Aoba, Sendai, Miyagi 980-8579, Japan.
Department of Finemechanics, Graduate School of Engineering, Tohoku University, 6-6-01 Aramaki Aza Aoba, Sendai, Miyagi 980-8579, Japan
J Exp Biol. 2020 Aug 6;223(Pt 15):jeb224691. doi: 10.1242/jeb.224691.
The nematode is a filter feeder that lives in various viscous habitats such as soil, the intestines of slugs, and rotting materials such as fruits and stems. draws in suspensions of bacteria and separates bacteria from water using the pharyngeal pump. Although these worms often live in highly viscous habitats, it is still unclear how they survive in these environments by eating bacteria. In this study, we investigated the effects of suspension viscosity on the survival rate of malnourished worms by combining live imaging and scaling analyses. We found that survival rate decreased with increases in viscosity because the high viscosity suppressed the amount of food ingested. The same tendency was found in two feeding-defective mutants, (7) and (). We also found that the high viscosity weakened pump function, but the velocities in the pharynx were not zero, even in the most viscous suspensions. Finally, we estimated the amount of ingested food using scaling analyses, which provided a master curve of the experimental survival rates. These results illustrate that the survival rate of worms is strongly dependent on the ingested bacteria per unit time associated with physical environments, such as the viscosity of food suspensions and the cell density of bacteria. The pump function of the pharynx is not completely lost even in fluids that have 10 times higher viscosity than water, which may contribute to their ability to survive around the world in highly viscous environments.
线虫是一种滤食性动物，生活在各种粘性栖息地，如土壤、鼻涕虫的肠道以及腐烂的水果和茎秆等物质中。它利用咽泵从悬浮液中吸入细菌，并将细菌与水分离。尽管这些蠕虫通常生活在高粘性的环境中，但它们如何通过食用细菌在这些环境中生存仍然不清楚。在这项研究中，我们通过结合实时成像和比例分析，研究了悬浮液粘性对线虫营养不良存活率的影响。我们发现，存活率随粘性的增加而降低，因为高粘性抑制了摄入的食物量。在两个进食缺陷突变体（7 和 ）中也发现了相同的趋势。我们还发现，高粘性会削弱泵的功能，但即使在最粘稠的悬浮液中，咽中的流速也不为零。最后，我们使用比例分析估计了摄入的食物量，这为实验存活率的主曲线提供了依据。这些结果表明，线虫的存活率强烈依赖于与物理环境相关的单位时间内摄入的细菌量，例如食物悬浮液的粘性和细菌的细胞密度。即使在粘度是水的 10 倍的液体中， 咽的泵功能也不会完全丧失，这可能有助于它们在全球范围内在高粘性环境中生存。
