Citation:

Urich, M., W. Henderson, A. MacLeod, L. Yonkos, AND R. Bringolf. Gonad metabolomics and blood biochemical analysis reveal differences associated with testicular oocytes in wild largemouth bass (Micropterus salmoides). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY - PART B: BIOCHEMISTRY & MOLECULAR BIOLOGY. Elsevier Science Ltd, New York, NY, 250:110491, (2020). https://doi.org/10.1016/j.cbpb.2020.110491

Impact/Purpose:

Highlights Intersex fish collected from impoundment with no known chemical contamination. Metabolomics analysis conducted on intersex gonadal tissues. Blood plasma biochemical screen measured markers of fish health. Plasma vitellogenin levels low; no sign of estrogen exposure. Results suggest intersex associated with thermal, hypoxic stress.

Description:

Adverse reproductive effects associated with gonadal intersex among freshwater fish could hold considerable implications for population sustainability. Testicular oocytes (TO) is the most common form or intersex and is widespread among centrarchids (sunfishes) of North America and other freshwater teleosts. Placing TO within the toxicological context of adverse outcome pathways (AOPs) to assess ecological risk is a priority for ecotoxicologists due to its association with harmful chemical exposure and adverse reproductive effects in some cases. However, key event relationships between EDC exposure, incidence of TO, and apical outcomes have yet to be fully elucidated – in part due to a lack of knowledge of relationships between intersex gonad physiology and fish health. Understanding the physiological status of intersex fish is critical to assess ecological risk, understand mechanisms of induction, and establish biomarkers of intersex in fish. In the present study, features of gonad metabolite profiles associated with TO in largemouth bass (LMB, Micropterus salmoides) collected from an impoundment in Georgia (USA) were determined using GC-MS-based metabolomics. Clinical blood biochemical screens were also conducted to evaluate markers of fish health associated with TO. Results suggest that physiological changes associated with energy expenditure, gonad lipid and protein metabolism, and thermal and/or hypoxic stress may be related to the occurrence of TO in LMB. These results provide novel insight to cellular pathways underlying the intersex condition and to identify candidate analytes for biomarker discovery. Overall, these results highlight the need to understand relationships between TO and physical stressors such as temperature and hypoxia.

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