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Auteur Rachel Benstead
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Affiner la rechercheAn optimised experimental test procedure for measuring chemical effects on reproduction in the fathead minnow, Pimephales promelas / Rachel Benstead
Titre : An optimised experimental test procedure for measuring chemical effects on reproduction in the fathead minnow, Pimephales promelas Type de document : texte imprimé Auteurs : Rachel Benstead, Auteur Importance : pp. 90-98 Langues : Anglais (eng) Index. décimale : 571 Physiologie et sujets voisins Résumé : The production of viable offspring is fundamental to the survival of any population. Tests that quantify effects on reproduction can, therefore, inform on the potential for long-term health effects of exposure to endocrine active chemicals. Surprisingly little is known, however, about the reproductive capacity of laboratory fish species used for chemical testing. As an example, the fathead minnow, Pimephales pmmelas, is widely used in chronic assessments of reproductive toxicology, and is readily induced to reproduce in captivity, yet there is little agreement on the reproductive capacity (egg number) of this species. For this species, the notable variation in reported estimates of egg number might relate to differences in the methods of egg collection adopted by many laboratories. To investigate this hypothesis, reproduction was assessed in a total of 200 pair-breeding fathead minnow, using egg collection methods that included the addition of trays placed beneath an inverted U-shaped PVC tile that is conventionally used alone for egg collection. The results demonstrated that the placement of a mesh-screened egg collection tray, beneath the spawning tile, increased estimates of the egg number by 25-67%. In addition, adopting the mesh-screened tray reduced variation in egg number between pairs, within an experiment, from >50% to <30% and variation between experiments was reduced from 53% to 7%. Adoption of the revised system for egg collection shows that egg number in the fathead minnow is considerably more consistent than frequently reported and is a highly robust endpoint against which chemical effects can be challenged effectively. An optimised experimental test procedure for measuring chemical effects on reproduction in the fathead minnow, Pimephales promelas [texte imprimé] / Rachel Benstead, Auteur . - [s.d.] . - pp. 90-98.
Langues : Anglais (eng)
Index. décimale : 571 Physiologie et sujets voisins Résumé : The production of viable offspring is fundamental to the survival of any population. Tests that quantify effects on reproduction can, therefore, inform on the potential for long-term health effects of exposure to endocrine active chemicals. Surprisingly little is known, however, about the reproductive capacity of laboratory fish species used for chemical testing. As an example, the fathead minnow, Pimephales pmmelas, is widely used in chronic assessments of reproductive toxicology, and is readily induced to reproduce in captivity, yet there is little agreement on the reproductive capacity (egg number) of this species. For this species, the notable variation in reported estimates of egg number might relate to differences in the methods of egg collection adopted by many laboratories. To investigate this hypothesis, reproduction was assessed in a total of 200 pair-breeding fathead minnow, using egg collection methods that included the addition of trays placed beneath an inverted U-shaped PVC tile that is conventionally used alone for egg collection. The results demonstrated that the placement of a mesh-screened egg collection tray, beneath the spawning tile, increased estimates of the egg number by 25-67%. In addition, adopting the mesh-screened tray reduced variation in egg number between pairs, within an experiment, from >50% to <30% and variation between experiments was reduced from 53% to 7%. Adoption of the revised system for egg collection shows that egg number in the fathead minnow is considerably more consistent than frequently reported and is a highly robust endpoint against which chemical effects can be challenged effectively. Exemplaires(0)
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Titre : A practicable laboratory flow-through exposure system for assessing the health effects of effluents in fish Type de document : texte imprimé Auteurs : Rachel Benstead, Auteur Importance : pp. 164-172 Langues : Anglais (eng) Index. décimale : 571 Physiologie et sujets voisins Résumé : The knowledge that exposure to estrogenic wastewater treatment work (WwTW) effluents induces a range of reproductive abnormalities in fish has highlighted the need to understand the wider health effects of effluents. Access to laboratory-based testing systems for WwTW effluents could greatly facilitate this endeavour. In this investigation, a laboratory-based test system was developed and applied for WwTW effluents using fathead minnows (Pimephales promdas). Sexually maturing fathead minnows were exposed, under flow-through conditions in the laboratory, for up to 21 days to graded concentrations of effluent from three different UK (temperate) WwTWs. The stability of the estrogenic component within the test system was assessed via measurements for estradiol and estrone concentrations in the effluent, and through determining estrogenic responses in an in vitro recombinant yeast estrogen screen (rYES) and in fish (plasma vitellogenin induction). The estrogen component of the effluents was stable within the holding system used (chilled <10 'C) for up to 7 days and measured concentrations of estradiol and estrone were shown to differ by less than 20% between the first and final day of use for each batch of effluent. Total estrogenic activity as measured in the rYES was found to be more variable (up to 66% variance between measurements for the two time points) but there was no consistent trend for a reduction in estrogenic activity. Vitellogenin was induced in males in a concentration-dependent manner and the magnitude of the response observed was proportional to the average measured concentrations of estradiol and estrone in the exposure effluent. The system described, thus, provides a robust test method for evaluating the estrogenic effects of temperate WwTW effluents that could be further applied to assess wider health effects, including population-relevant endpoints such as reproduction, using model OECD warm-water fish species such as the fathead minnow. A practicable laboratory flow-through exposure system for assessing the health effects of effluents in fish [texte imprimé] / Rachel Benstead, Auteur . - [s.d.] . - pp. 164-172.
Langues : Anglais (eng)
Index. décimale : 571 Physiologie et sujets voisins Résumé : The knowledge that exposure to estrogenic wastewater treatment work (WwTW) effluents induces a range of reproductive abnormalities in fish has highlighted the need to understand the wider health effects of effluents. Access to laboratory-based testing systems for WwTW effluents could greatly facilitate this endeavour. In this investigation, a laboratory-based test system was developed and applied for WwTW effluents using fathead minnows (Pimephales promdas). Sexually maturing fathead minnows were exposed, under flow-through conditions in the laboratory, for up to 21 days to graded concentrations of effluent from three different UK (temperate) WwTWs. The stability of the estrogenic component within the test system was assessed via measurements for estradiol and estrone concentrations in the effluent, and through determining estrogenic responses in an in vitro recombinant yeast estrogen screen (rYES) and in fish (plasma vitellogenin induction). The estrogen component of the effluents was stable within the holding system used (chilled <10 'C) for up to 7 days and measured concentrations of estradiol and estrone were shown to differ by less than 20% between the first and final day of use for each batch of effluent. Total estrogenic activity as measured in the rYES was found to be more variable (up to 66% variance between measurements for the two time points) but there was no consistent trend for a reduction in estrogenic activity. Vitellogenin was induced in males in a concentration-dependent manner and the magnitude of the response observed was proportional to the average measured concentrations of estradiol and estrone in the exposure effluent. The system described, thus, provides a robust test method for evaluating the estrogenic effects of temperate WwTW effluents that could be further applied to assess wider health effects, including population-relevant endpoints such as reproduction, using model OECD warm-water fish species such as the fathead minnow. Exemplaires(0)
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