Mass spectrometry imaging of the sentinel freshwater crustacean Daphnia: a novel tool for environmental diagnostics

水蚤是生物学上的一种模式生物，与生态学、人类健康和环境健康有着直接的关系。它们的生成时间短，离合器尺寸大，易于实验室和现场操作，确保了它们在制定环境卫生标准，测试化学品安全性，监测水质以及作为生态和进化研究的模型方面的重要性。这种生物的重要性激发了国际水蚤基因组学联盟的发展，并随后发表了水蚤基因组（Science 2011; 331: 555-561）；以及伯明翰大学广泛且正在进行的深度代谢组注释和代谢物鉴定。然而，迄今为止，还没有研究绘制水蚤物种内源性代谢物的空间定位，也没有研究暴露于化学污染物后毒物（和代谢产物）的位置。在这个项目中，解吸电喷雾电离（DESI）质谱法将用于解决水蚤代谢组学研究中提取空间信息的不足。在暴露研究中绘制内源性代谢物和毒物将有助于从机制上理解环境污染物引起的毒性。此外，将为水蚤代谢组学研究开发基于快速蒸发电离（REIMS）的质谱工作流程，以大大提高样品通量，从而以统计稳健的方式对大样本集进行研究。

Daphnia is a model organism in biology, with immediate relevance for ecology, human and environmental health. Their short generation time, large clutch sizes and ease of laboratory and field manipulation have assured their importance for setting environmental health standards, for testing chemical safety, for monitoring water quality, and as a model for ecological and evolutionary research. The importance of this organism inspired the development of the international Daphnia Genomics Consortium and subsequent publishing of the Daphnia genome (Science 2011; 331: 555-561); also the extensive and on-going Deep Metabolome Annotation and metabolite identification at the University of Birmingham. However, to date, there has been no studies mapping the spatial localisation of endogenous metabolites in Daphnia species, nor the location of toxicants (and metabolic products) following exposure to chemical pollutants.In this project desorption electrospray ionisation (DESI) mass spectrometry, will be used to address the lack of spatial information extracted in metabolomic studies of Daphnia. Mapping the endogenous metabolites and toxicants in exposure studies will aid mechanistically understanding the toxicity caused by environmental pollutants.Additionally, rapid evaporative ionisation (REIMS) based mass spectrometry workflows will be developed for Daphnia metabolomics studies to greatly increase sample throughput, towards enabling studies of large sample sets in a statistically robust manner.