INDUCTION OF TESTIS–OVA IN JAPANESE MEDAKA (ORYZIAS LATIPES) EXPOSED TO p-NONYLPHENOL

Abstract

Abstract-4-Nonylphenol (NP) is a degradation product of nonylphenol polyethoxylates, a major group of nonionic surfactants. When Japanese medaka, Oryzias latipes were exposed from hatch to 3 months of age to aqueous solutions of NP at nominal concentrations of 10, 50, and 100 g/L, 50% of the male fish in the 50-g/L treatment and 86% of the males in the 100-g/L treatment developed testis-ova, an intersex condition characterized by both testicular and ovarian tissue in the gonad. The ratios of males to females in the control treatment (2:1, M:F) and the 100-g/L NP treatment (1:2, M:F) were also significantly different. The LOAEC for induction of testis-ova at a nominal concentration of 50 g/L NP is slightly greater than the upper range of concentrations of NP that have been reported in final effluents from municipal sewage treatment plants. Studies on the environmental fate of nonylphenol ethoxylates and degradation products in the aquatic environment are needed to assess the significance of these data in terms of potential reproductive effects in feral fish populations.

Histological alternation and vitellogenin induction in adult rare minnow (Gobiocypris rarus) after exposure to ethynylestradiol and nonylphenol

“…In addition, adult zebrafish exposed to 10 ng/l and 25 ng/l EE2 reduced the number of mature, yolk-filled oocytes (Van den Belt et al, 2001). In contrast, Gray and Metcalfe (1997) reported medaka larvae exposed for three months to NP at concentrations of 50 and 100 lg/l were shown to undergo testis-ova formation in males. Reinhard et al (2001) also reported that long-term exposures resulted in formation of ova-testes and the appearance of sex reversals in fathead minnows after 305 d of exposure to EE2 at 4 ng/l.…”

“…Reinhard et al (2001) also reported that long-term exposures resulted in formation of ova-testes and the appearance of sex reversals in fathead minnows after 305 d of exposure to EE2 at 4 ng/l. Gray and Metcalfe (1997) also reported that medaka with long-term exposure to p-nonylphenol at 50 lg/l caused the formation of ova-testes. This report showed a difference in adult fish with the formation of ova-testes at relatively low concentrations of endocrine disruptors.…”

“…They have been found to ranged from <0.2 to 12 lg/l in polluted British river waters (Blackburn and Waldock, 1995), and <0.3-45 lg/l in the Swiss river Glatt (Ahel et al, 1994). Several studies have been performed to evaluate the potential risk of NP exposure on the endocrine system, which include induction of the female specific egg yolk precursor vitellogenin in male rainbow trout (Oncorhynchus mykiss) (Jobling et al, 1996), development of testis-ova in medaka (Oryzias latipes), increasing of the ovosomatic index in medaka (Gray and Metcalfe, 1997).…”

Comparison of in Vivo and in Vitro Reporter Gene Assays for Short-Term Screening of Estrogenic Activity

“…The modest response of the transgenic zebrafish to NP is surprising, as a number of reports have documented the in vivo estrogenicity of nonylphenol in other fish species (reviewed in ref 5). NP has been shown to induce vitellogenesis and inhibition of testicular growth in male rainbow trout exposed under continuous flow conditions for 3 weeks (19) as well as to induce feminized gonads in male Japanese medaka exposed during a full life cycle (3 months) (20). Although it is possible that the 96-h-exposure duration of the transgenic zebrafish was too short to achieve an internal dose that could induce luciferase, prolonged (3 week) exposure to NP also did not result in increased luciferase expression in juvenile transgenic zebrafish (unpublished results).…”

The occurrence, causes, and consequences of estrogens in the aquatic environment

“…Besides the steroid estrogens, some of which (especially EE2) induce effects at extremely low environmental concentrations [10], a range of xenobiotics known to be present in effluents [11,12], including NP and bisphenol A, are estrogenic to fish [13]. Furthermore, some of these xenoestrogens can feminize male fish, producing effects (e.g., ovotestis) that are reminiscent of those found in wild fish living downstream of STPs [2,14]. These laboratory studies, in which fish were exposed to (often) environmentally relevant concentrations of different estrogenic chemicals (e.g., Metcalfe et al [13]), demonstrated the environmental relevance of fish reproduction tests [15].…”