Daphnia are keystone species of freshwater habitats used as model organisms in ecology and evolutionary biology. Their small size, wide geographic distribution, and sensitivity to chemicals make them useful as environmental sentinels in regulatory toxicology and chemical risk assessment. Biomolecular (-omic) assessments of responses to chemical toxicity, which reveal detailed molecular signatures, become more powerful when correlated with other phenotypic outcomes (such as behavioral, physiological, or histopathological) for comparative validation and regulatory relevance. However, the lack of histopathology or tissue phenotype characterization of this species presently limits our ability to assess cellular mechanisms of toxicity
Daphnia magna is a keystone branchiopod crustacean (order Cladocera) in lentic ecosystems worldwide and an established model in ecology and evolution. The small size, global freshwater distribution, wide range of cell size and structures of micron scale, and common use of Daphnia magna in toxicological and environmental studies make it an ideal model for demonstrating the potential power of micro-CT-enabled whole-organism phenotyping. At histological resolutions, micro-CT can be used for whole-animal qualitative and quantitative characterization of tissue and organismal structure in health and disease.
Micro-computed tomography (micro-CT) is becoming recognized as a tool for three-dimensional (3D) visualization and quantitative analysis of biological samples. Imaging whole, intact samples allows detailed investigation of overall morphology and cellular structures and is especially useful for evaluating microanatomy and phenotypes in various model organisms