Use of the australian crimson-spotted rainbowfish (Melanotaenia fluviatilis) as a model test species for investigating the effects of endocrine disruptors

Abstract

Few studies have investigated the potential reproductive effects of toxicants on Australian freshwater fish species. The present study uses the Australian rainbowfish (Melanotaenia fluviatilis) as a model for testing the potential effects of 17beta-estradiol. Groups of reproductively active rainbowfish were exposed to waterborne 17beta-estradiol (control, carrier control, and 30, 100, 300, and 1,000 ng/L) for 3- and 14-d periods. Biomarkers of both low ecological relevance (plasma estradiol and testosterone, phosphoprotein, gamma-glutamyltranspeptidase [GTP]) and high ecological relevance (egg counts, hatchability, larval lengths, histopathology) were measured and the relationships between these examined. Relative to the controls, exposed female rainbowfish had a decline in plasma estradiol. An increase in phosphoprotein (vitellogenin) also was observed after exposure to 1,000 ng/L after 3 d, and histological examination of the gonads showed an increase in oocyte atresia at 1,000 ng/L on days 3 and 14. Changes in egg production were observed at 300 and 1,000 ng/L. No changes were detected to egg hatchability and larval lengths of offspring. Although there were no changes in male rainbowfish plasma testosterone or the histological organization of testes, levels of phosphoprotein increased and GTP activities were increased after 3 d of exposure at all test concentrations, but these declined at day 14. The present study demonstrated that, though measurements at the biochemical level were responsive to 17beta-estradiol exposure, fewer changes were observed in markers of higher ecological relevance at the exposures concentrations and durations tested.

Effects of the commercial antiandrogen flutamide on the biomarkers of reproduction in male Murray rainbowfish (Melanotaenia fluviatilis)

“…The adults of this fish species are economic and easy to maintain in laboratory conditions due to their small size (<4 g and 5–6 cm). In previous studies in our laboratory and elsewhere in Australia, sexually mature Murray rainbowfish have been used effectively as a model fish species to assess the effects of environmental estrogens in Australian riverine environments . The need remains, however, to determine the use of Murray rainbowfish as a sensitive model to assess effects via androgen receptors of endocrine‐disrupting compounds.…”

Di-n-butyl phthalate causes antiestrogenic effects in female murray rainbowfish (Melanotaenia fluviatilis)

“…In the Australian freshwater environment, the impact of antiandrogens or antiestrogens in native fish species is not fully understood. Murray rainbowfish ( Melanotaenia fluviatilis ) has recently been identified as a suitable candidate species for assessing the endocrine effects of endocrine‐disrupting chemicals (EDCs) in the Australian riverine environment because of its small size (<4 g) and display of sexual dimorphism in adults. The acute toxicity of DnBP (measured as the 96‐h median lethal concentration [LC50]) to rainbow trout ( Salmo gairdneri ) has been reported to be 6.5 mg/L, 1.3 mg/L to fathead minnows ( Pimephales promelas ), 0.7 mg/L to bluegill ( Lepomis macrochirus ), 2.9 mg/L to channel catfish ( Ictalurus punctatus ), 2.10 mg/L to scud ( Gammarus pseudolimnaeus ), 2.2 mg/L to red killifish ( Orizias latipes ), 0.4 mg/L to yellow perch ( Perca flavescens ), and 0.9 mg/L to the marine fish Thryssa hamiltonii .…”

Vitellogenin induction by 17β-estradiol and 17α-ethynylestradiol in male Murray rainbowfish (Melanotaenia fluviatilis)

“…The Australian Murray rainbowfish ( Melanotaenia fluviatilis ) has been used in toxicological studies to monitor environmental contaminants in Australia over the past couple of decades 14–16. It is a small (1–3 g) freshwater fish belonging to the family Melanotaeniidae that resides in inland Murray‐Darling Basin, spanning New South Wales, Victoria, and South Australia 17.…”