Comparative responses in rare minnow exposed to 17β-estradiol during different life stages

Abstract

Present in the excrement of humans and animals, 17beta-estradiol (E(2)) has been detected in the aquatic environment in a range from several nanograms to several hundred nanograms per liter. In this study, the sensitivities of rare minnows during different life stages to E(2) at environmentally relevant (5, 25, and 100 ng l(-1)) and high (1000 ng l(-1)) concentrations were compared using vitellogenin (VTG) and gonad development as biomarkers under semistatic conditions. After 21 days of exposure, VTG concentrations in whole-body homogenates were analyzed; the results indicated that the lowest observed effective concentration for VTG induction was 25 ng l(-1) E(2) in the adult stage, but 100 ng l(-1) E(2) in the larval and juvenile stages. After exposure in the early life stage, the larval and juvenile fish were transferred to clean water until gonad maturation. No significant difference in VTG induction was found between the exposure and control groups in the adults. However, a markedly increased proportion of females and appearance of hermaphrodism were observed in the juvenile-stage group exposed to 25 ng l(-1) E(2). These results showed that VTG induction in the adult stage is more sensitive than in larval and juvenile stages following exposure to E(2). The juvenile stage may be the critical period of gonad development. Sex ratio could be a sensitive biomarker indicating exposure to xenoestrogens in early-life-stage subchronic exposure tests. The results of this study provide useful information for selecting sensitive biomarkers properly in aquatic toxicology testing.

Comparative responses to endocrine disrupting compounds in early life stages of Atlantic salmon, Salmo salar

“…Regulation of circulating E2 by ERs is an important regulator of ovarian development in fish and is interlinked with growth and development (Devlin and Nagahama, 2002). Estrogen receptors increase in number during development, and in particular are likely to increase rapidly prior to and during sexual differentiation and reproduction (Liao et al, 2009), and transcription of different isoforms shifts periodically throughout early development (Chandrasekar et al, 2010). Gonad differentiation begins early in development in Atlantic salmon, as many of the major genes involved in sex determination and differentiation are upregulated in the embryonic stage (von Schalburg et al, 2011).…”

A review of studies on androgen and estrogen exposure in fish early life stages: effects on gene and hormonal control of sexual differentiation

“…Due to the estrogen control of VTG, levels of this protein have been found to be an effective biomarker for estrogen exposure in fish. Many of the articles reviewed for this paper used VTG induction as a marker of estrogen exposure and response, and many found VTG induction at environmentally relevant concentrations of E 1 , E 2 , EE 2 and E 3 (Bogers et al , ; Fenske et al , ; Holbech et al , ; Länge et al , ; Liao et al , ; Örn et al , ; van Aerle et al , ). Further, Tyler et al () found induction of this protein to be a more sensitive endpoint than changes on sex ratios or sex reversal in juvenile fathead minnows exposed to 17 β ‐E 2 .…”

Molecular cloning of Foxl2 gene and the effects of endocrine-disrupting chemicals on its mRNA level in rare minnow, Gobiocypris rarus

“…Gobiocypris rarus has been widely used as an important model animal for studies with their small size, ease of laboratory culture, wide temperature range, short life cycle, high fertilization rate and hatching rate, sensitivity to chemicals, and many other advantages, and rare minnow are promising animal model for aquatic toxicology research (Wang 1999). Recently, several studies have documented endocrine-disrupting effects in G. rarus (Zha et al 2007(Zha et al , 2008aLiao et al 2009;Wang et al 2010Wang et al , 2011.…”