Effects of larval–juvenile treatment with perchlorate and co-treatment with thyroxine on zebrafish sex ratios

Mukhi, Sandeep; Torres, Leticia; Patiño, Reynaldo

doi:10.1016/j.ygcen.2006.11.013

Cited by 83 publications

(65 citation statements)

References 35 publications

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“…Rather, such fish develop intersex gonads (ovotestes), which is consistent with the effects of chronic perchlorate exposure (Bernhardt et al, 2006). Mukhi et al (2007) demonstrated that administration of perchlorate to zebrafish (Danio rerio) during the larval-juvenile developmental period produced a female-biased sex ratio, and supplemental thyroid hormone administration produced a male-biased sex ratio. This finding demonstrates that thyroid hormones play a key role in the sexual development of at least some fish.…”

Section: Behaviour Of Hermaphroditesmentioning

confidence: 56%

Chronic perchlorate exposure impairs stickleback reproductive behaviour and swimming performance

Bernhardt

Hippel

2008

Behav

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SummaryWe describe behavioural changes in two generations of threespine stickleback (Gasterosteus aculeatus) exposed to environmentally relevant concentrations of perchlorate. The first generation (G 0,2002 ) was exposed as two-year-old adults to perchlorate in experimental groups ranging in concentration from less than the method detection limit (<1.1 ppb) to 18.6 ppm for up to 22 days during their courtship, spawning, egg guarding, and first five days of fry guarding. No differences were noted in the behaviour or reproductive output of these fish that were exposed as adults. However, perchlorate exposure throughout development caused widespread effects in the second generation (G 1,2003 ), which was spawned and raised through sexual maturity in one of four nominal experimental groups (0, 30 and 100 ppm, and a 'variable' treatment that progressively increased from <1.1 ppb to approximately 60 ppm perchlorate). Dose-dependent effects were found during the G 1,2003 's swimming and behavioural evaluations, including higher mortality rates among treated fish following stressful events. Perchlorate-exposed fish had higher failure rates during swimming trials and failed at lower flow rates than control fish. A number of treated fish exhibited seizures. Progressively fewer males completed benchmark metrics, such as nest building, spawning, nursery formation, or fry production, in a dose-dependent manner. Fewer males from higher treatments courted females, and those that did initiated courtship later and had a reduced behavioural repertoire compared to fish from lower treatments. The lowest observed adverse effect level (LOAEL) for swimming performance, reproductive behaviour, survivorship and recruitment was 30 ppm perchlorate (our lowest G 1,2003 treatment), and near complete inhibition of reproductive activity was noted among males raised in 100 ppm perchlorate. A small number of treated G 1,2003 females were isolated in aquaria, and some performed reproductive behaviour typical of males, such as biting, leading and zig-zagging in the presence of gravid females. These findings have profound implications for recruitment in wild fish populations exposed to perchlorate, and suggest that perchlorate may disrupt behaviour in other vertebrates as well.

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Section: Behaviour Of Hermaphroditesmentioning

confidence: 56%

Chronic perchlorate exposure impairs stickleback reproductive behaviour and swimming performance

Bernhardt

Hippel

2008

Behav

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“…Our findings suggest that FIN treatment results in an increased capacity for hepatic activation of THs ( dio2 gene product converts circulating prehormone thyroxine [T4] into active hormone triiodothyronine [T3]) while de- creasing the inactivation pathway ( dio3 gene product converts T4 into the inactive reverse T3) in males and intersex. Thyroid hormones appear to be involved in male sexual development since exposure to perchlorate, a TH synthesis inhibitor, increases the proportion of females in X. laevis [Goleman et al, 2002] and zebrafish [Mukhi et al, 2007] and induces the presence of intersex in threespine sticklebacks [Bernhardt et al, 2006]. Based on these studies we can speculate that FIN-treated males and intersex animals could be increasing their active TH concentration to counteract the effects of FIN.…”

Section: Discussionmentioning

confidence: 93%

The Aromatase Inhibitor Fadrozole and the 5-Reductase Inhibitor Finasteride Affect Gonadal Differentiation and Gene Expression in the Frog <i>Silurana tropicalis</i>

Duarte‐Guterman

Langlois

Hodgkinson

et al. 2009

Sex Dev

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Aromatase (cyp19) and the 5α- and 5β-reductases (srd5alpha and srd5beta) are important enzymes for vertebrate sexual development. We investigated the effects of inhibition of cyp19 by fadrozole (FAD), and srd5alpha and srd5beta by finasteride (FIN) during anuran larval development. Chronic exposures of Silurana (Xenopus) tropicalis from Nieuwkoop-Faber stage 12 until stage 60 were performed using either 2 µM FAD or 25 µM FIN. Histological analysis of exposed metamorphic frogs revealed that both treatments induced intersex individuals (presence of testicular oocytes). FAD treatment resulted in 55% male, 30% female and 15% intersex, while FIN treatment produced 27% male, 53% female and 20% intersex. Real-time RT-PCR analysis of hepatic sex steroid- and thyroid hormone-related gene expression demonstrated that FAD-induced intersex animals had higher srd5alpha1, srd5alpha2 and eralpha mRNA levels than control and FAD males. In contrast, FIN-induced intersex had low srd5alpha1, srd5alpha2, srd5beta and dio3 and high dio2 mRNA levels. FIN-treated males exhibited high trbeta, dio2 and a lower dio3 mRNA levels. We conclude that chemically induced intersex animals display different gene expression profiles than non-exposed animals and that, although morphologically similar, intersex animals produced by different chemicals have different endocrine pathophysiologies.

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“…Previous studies have also demonstrated estrogenic activity of PFOS and other PFCs (Maras et al, 2006;Liu et al, 2007). Mukhi et al (2007) showed that cotreatment with exogenous T 4 caused hyperthyroid-like conditions and skewed the phenotypic sex ratio toward male zebrafish, suggest an important role for TH in the process of gonadal sex differentiation and the maintenance of balanced sex ratios in developing zebrafish. Therefore, further studies are needed to reveal the exact relationship between the HPT and hypothalamic-pituitary-gonad (HPG) axes.…”

Section: Discussionmentioning

confidence: 94%

Waterborne exposure to PFOS causes disruption of the hypothalamus–pituitary–thyroid axis in zebrafish larvae

et al. 2009

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Effects of larval–juvenile treatment with perchlorate and co-treatment with thyroxine on zebrafish sex ratios

Cited by 83 publications

References 35 publications

Chronic perchlorate exposure impairs stickleback reproductive behaviour and swimming performance

Chronic perchlorate exposure impairs stickleback reproductive behaviour and swimming performance

The Aromatase Inhibitor Fadrozole and the 5-Reductase Inhibitor Finasteride Affect Gonadal Differentiation and Gene Expression in the Frog <i>Silurana tropicalis</i>

Waterborne exposure to PFOS causes disruption of the hypothalamus–pituitary–thyroid axis in zebrafish larvae

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