Protogynous Sex Change in the Reed Frog Hyperolius viridiflavus

Grafe, T. Ulmar; Linsenmair, K. Eduard

doi:10.2307/1445989

Cited by 32 publications

(13 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Intersex gonads and hermaphroditism are known to occur spontaneously, though infrequently, in amphibians [43,44]. However, in this study, intersex gonads occurred exclusively in mink frog tadpoles exposed to EE2 in the wild and in situ; no abnormal gonads were detected in a total of 353 wild and 140 caged reference samples of the same species.…”

Section: Discussioncontrasting

confidence: 50%

Effects of the synthetic estrogen ethinylestradiol on early life stages of mink frogs and green frogs in the wild and in situ

Park

Kidd

2005

Environmental Toxicology and Chemistry

View full text Add to dashboard Cite

Estrogenic contaminants are known to disrupt growth and development in amphibians. Field-based research is needed to elucidate their potential impacts on wild populations. Hatch success, larval growth and development rates, and gonad development were examined in native amphibians exposed to low ng/L concentrations of 17alpha-ethinylestradiol (EE2) in a whole-lake addition experiment at the Experimental Lakes Area, northwestern Ontario, Canada. Egg masses were reared in situ in the EE2-amended lake and in two reference lakes in 2001 and 2002. Hatching success was reduced significantly in green frogs (Rana clamitans) but not in mink frogs (Rana septentrionalis) exposed to EE2. Ethinylestradiol had no consistent effect on mass or development stage of hatchlings in the early larval stages of the caging study. Ethinylestradiol had no effect on sex ratios of either species in situ, and no intersex gonads were observed in exposed or reference green frog tadpoles or in reference mink frog tadpoles. However, 5.6% (total n = 18) and 12.5% (total n = 56) of EE2-exposed mink frog tadpoles were intersex in the 2001 and 2002 caging studies, respectively. Wild mink frog tadpoles also were examined, and EE2 had no effect on sex ratios. No intersex gonads were observed in reference lake tadpoles or in tadpoles from the experimental lake prior to EE2 additions; however, 2.4, 0, and 28.6% of wild EE2-exposed first-year tadpoles had intersex gonads (2001, 2002, and 2003, respectively). These results indicate that exposure to EE2 in the wild and in situ at concentrations comparable to those detected in effluents and, occasionally, in surface waters can impact gonad development and hatch success in native amphibians.

show abstract

Section: Discussioncontrasting

confidence: 50%

Effects of the synthetic estrogen ethinylestradiol on early life stages of mink frogs and green frogs in the wild and in situ

Park

Kidd

2005

Environmental Toxicology and Chemistry

View full text Add to dashboard Cite

show abstract

“…The occurrence of an isolated sex reversal event was suspected because of the abnormal age structure in a wild population of Pelobates fuscus [21,39]. Some protogyneous individuals under the supposed influence of a low male density in Hyperolius viridiflavus [40] or some proterandreous individuals under the supposed influence of "food castration" in Triturus alpestris [41] were observed in captivity. The discovery of the influence of the ionic composition of a breeding habitat on the sex ratio of Discoglossus by Stolkowski [42] launched several researches about sex control at birth in humans.…”

Section: Sensitivity Of Sex Determination To Epigenetic Factorsmentioning

confidence: 99%

Sex determination: the amphibian models

2004

View full text Add to dashboard Cite

-We review and discuss current knowledge about sex determination in amphibians. The astonishing wide variety of mechanisms of genotypic sex determination is presented and discussed in an evolutionary context. We recall the natural occurrence of transitory juvenile hermaphroditism in some species. Our present knowledge of the mechanisms of sex determination in amphibians is compared to that in mammals. The influence of epigenetic factors, and especially temperature is highlighted. In amphibians, the influence of temperature on sexual differentiation, that can prevail over genotypic sex determination, remains poorly considered in publications. We suggest that studies on genetic and epigenetic factors of gonadal sex differentiation in amphibians could provide substantial information on the evolutionary process of sex determination mechanisms in current living vertebrates.sex determination mechanisms / sexual differentiation / hermaphroditism / epigenetic factors

show abstract

“…Sex change is widespread in nature, occurring in plants, invertebrates, and teleost fishes (Policansky, 1982;Warner, 1984;Grafe and Linsenmair, 1989). There is, however, no evidence that any amniote vertebrate (mammals, birds, and reptiles) exhibits this reproductive pattern.…”

Section: Introductionmentioning

confidence: 99%

Sex Inversion of Sexually Immature Honeycomb Grouper (Epinephelus merra) by Aromatase Inhibitor

et al. 2004

View full text Add to dashboard Cite

The honeycomb grouper, Epinephelus merra , is a protogynous hermaphrodite fish. Sex steroid hormones play key roles in sex change of this species. A significant drop in endogenous estradiol-17β β β β (E2) levels alone triggers female-to-male sex change, and the subsequent elevation of 11-ketotestosterone (11KT) levels correlates with the progression of spermatogenesis. To elucidate the role of an androgen in sex change, we attempted to induce female-to-male sex change by exogenous 11KT treatments. The 75-day 11KT treatment caused 100% masculinization of pre-spawning females. Ovaries of the control (vehicle-treated) fish had oocytes at various stages of oogenesis, while the gonads of the 11KT-treated fish had transformed into testes; these contained spermatogenic germ cells at various stages, including an accumulation of spermatozoa in the sperm duct. In the sex-changed fish, plasma levels of E2 were significantly low, while both testosterone (T) and 11KT were significantly increased. Our results suggest that 11KT plays an important role in sex change in the honeycomb grouper. Whether the mechanism of 11KT-induced female-to-male sex change acts through direct stimulation of spermatogenesis in the ovary or via the inhibition of estrogen synthesis remains to be clarified.

show abstract

Protogynous Sex Change in the Reed Frog Hyperolius viridiflavus

Cited by 32 publications

References 22 publications

Effects of the synthetic estrogen ethinylestradiol on early life stages of mink frogs and green frogs in the wild and in situ

Effects of the synthetic estrogen ethinylestradiol on early life stages of mink frogs and green frogs in the wild and in situ

Sex determination: the amphibian models

Sex Inversion of Sexually Immature Honeycomb Grouper (Epinephelus merra) by Aromatase Inhibitor

Contact Info

Product

Resources

About