Campbell Jason C, Chin-Sang Ian D, Bendena William G
Department of Biology, Queen's University;
Department of Biology, Queen's University.
J Vis Exp. 2017 Jul 26(125):55939. doi: 10.3791/55939.
To ensure survival, organisms must be capable of avoiding unfavorable habitats while ensuring a consistent food source. Caenorhabditis elegans alter their locomotory patterns upon detection of diverse environmental stimuli and can modulate their suite of behavioral responses in response to starvation conditions. Nematodes typically exhibit a decreased aversive response when removed from a food source for over 30 min. Observation of behavioral changes in response to a changing nutritional status can provide insight into the mechanisms that regulate the transition from a well-fed to starved state. We have developed an assay that measures a nematode's ability to cross an aversive barrier (i.e. copper) then reach a food source over a prolonged period of time. This protocol builds upon previous work by integrating multiple variables in a manner that allows for continued data collection as the organisms shift towards an increasingly starved condition. Moreover, this assay permits an increased sample size so that larger populations of nematodes can be simultaneously evaluated. Organisms defective for the ability to detect or respond to copper immediately cross the chemical barrier, while wild type nematodes are initially repelled. As wild type worms are increasingly starved, they begin to cross the barrier and reach the food source. We designed this assay to evaluate a mutant that is incapable of responding to diverse environmental cues, including food sensation or detection of aversive chemicals. When evaluated via this protocol, the defective organisms immediately crossed the barrier, but were also incapable of detecting a food source. Hence, these mutants repeatedly cross the chemical barrier despite temporarily reaching a food source. This assay can straightforwardly test populations of worms to evaluate potential pathway defects related to aversion and starvation.
为确保生存，生物体必须能够避开不利的栖息地，同时确保有稳定的食物来源。秀丽隐杆线虫在检测到各种环境刺激时会改变其运动模式，并能根据饥饿状况调节其一系列行为反应。线虫从食物源移除超过30分钟后，通常会表现出厌恶反应降低。观察线虫对营养状态变化的行为反应，有助于深入了解调节从饱腹状态到饥饿状态转变的机制。我们开发了一种检测方法，用于测量线虫在长时间内穿过厌恶屏障（即铜）并到达食物源的能力。该方案基于之前的工作，通过整合多个变量，使得在生物体逐渐趋向饥饿状态时能够持续收集数据。此外，这种检测方法允许增加样本量，从而可以同时评估更多数量的线虫。缺乏检测或响应铜能力的生物体能够立即穿过化学屏障，而野生型线虫最初会受到排斥。随着野生型线虫越来越饥饿，它们开始穿过屏障并到达食物源。我们设计这个检测方法来评估一种无法对多种环境线索做出反应的突变体，包括食物感知或厌恶化学物质的检测。通过该方案进行评估时，有缺陷的生物体能够立即穿过屏障，但也无法检测到食物源。因此，这些突变体尽管会暂时到达食物源，但仍会反复穿过化学屏障。这种检测方法可以直接测试线虫群体，以评估与厌恶和饥饿相关的潜在通路缺陷。
