School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332.
Aquatic Chemical Ecology Center, Georgia Institute of Technology, Atlanta, GA 30332.
Proc Natl Acad Sci U S A. 2018 Jan 23;115(4):662-667. doi: 10.1073/pnas.1713901115. Epub 2018 Jan 8.
An effective strategy for prey to survive in habitats rich in predators is to avoid being noticed. Thus, prey are under selection pressure to recognize predators and adjust their behavior, which can impact numerous community-wide interactions. Many animals in murky and turbulent aquatic environments rely on waterborne chemical cues. Previous research showed that the mud crab, , recognizes the predatory blue crab, , via a cue in blue crab urine. This cue is strongest if blue crabs recently preyed upon mud crabs. Subsequently, mud crabs suppress their foraging activity, reducing predation by blue crabs. Using NMR spectroscopy- and mass spectrometry-based metabolomics, chemical variation in urine from blue crabs fed different diets was related to prey behavior. We identified the urinary metabolites trigonelline and homarine as components of the cue that mud crabs use to detect blue crabs, with concentrations of each metabolite dependent on the blue crab's diet. At concentrations found naturally in blue crab urine, trigonelline and homarine, alone as well as in a mixture, alerted mud crabs to the presence of blue crabs, leading to decreased foraging by mud crabs. Risk perception by waterborne cues has been widely observed by ecologists, but the molecular nature of these cues has not been previously identified. Metabolomics provides an opportunity to study waterborne cues where other approaches have historically failed, advancing our understanding of the chemical nature of a wide range of ecological interactions.
在富含捕食者的栖息地中，猎物生存的有效策略是避免被注意到。因此，猎物承受着识别捕食者和调整行为的选择压力，这可能会影响到众多的群落间相互作用。在浑浊和动荡的水生环境中，许多动物依赖于水中的化学线索。先前的研究表明，泥蟹通过蓝蟹尿液中的一种线索来识别捕食者蓝蟹。如果蓝蟹最近捕食了泥蟹，这种线索最强。随后，泥蟹会抑制其觅食活动，从而减少蓝蟹的捕食。通过基于 NMR 光谱和质谱的代谢组学研究，我们发现蓝蟹在不同饮食条件下的尿液中的化学变化与猎物行为有关。我们确定了尿液中的代谢物瓜氨酸和高丝氨酸是泥蟹用来检测蓝蟹的线索成分，每种代谢物的浓度取决于蓝蟹的饮食。在蓝蟹尿液中自然存在的浓度下，瓜氨酸和高丝氨酸单独或混合存在时，会向泥蟹发出蓝蟹存在的警报，导致泥蟹觅食减少。水生线索的风险感知已被生态学家广泛观察到，但这些线索的分子性质以前尚未确定。代谢组学为研究其他方法以前未能研究的水生线索提供了机会，从而提高了我们对广泛的生态相互作用的化学性质的理解。
