A Web-Based Histology Atlas for the Freshwater Sentinel Species Daphnia Magna

Abstract

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 also make them useful as environmental sentinels in regulatory toxicology and chemical risk assessment. Biomolecular (omics) assessments of response to chemical toxicity largely focus today on molecular phenotypes. The present lack of mechanisms for assessing corresponding tissue phenotypes impedes our ability to assess or validate inferred cellular mechanisms of disease. Here, we introduce the Daphnia Histology Reference Atlas (DaHRA) as a baseline of anatomy and microanatomy of wildtype female and male Daphnia magna. This interactive web-based resource features overlaid vectorized demarcation of anatomical structures that are compliant with an anatomical ontology created for this atlas. We also benchmark the potential use of this tool for toxicology by documenting the histopathological features of D. magna exposed to acetaminophen. DaHRA provides microanatomical context for the interpretation of molecular and cellular data as we dissect the roles of genes and environment in defining normal and abnormal organismal phenotype.

Keywords: Daphnia magna, sentinel, microanatomy, atlas, phenotypes, sexual dimorphism, histopathology, toxicology