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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The effect of mercury exposure and season on the physiological status of field collected rock bass

Bidwell, Joseph R. January 1988 (has links)
Selected physiological variables of rock bass <i>Ambloplites rupestris</i> collected by electroshocking, and then confined in on-site cages for one week, were examined at different times of the year. This was done in both an area contaminated with mercury, and an upstream reference site on the South River, Virginia. When compared to the upstream fish, rock bass from the mercury contaminated area had significantly higher concentrations of the metal in both the muscle and liver. On the whole, significant physiological differences between the two groups of rock bass were rather limited, although sharp differences in liver ascorbic acid and glutathione were observed between those fish which were collected in July. The July rock bass also had higher levels of liver mercury than that observed in fish collected at other times. Most seasonal changes were associated with the start of the spawning time (May), and included sex related differences in plasma calcium, liver glycogen, and ascorbic acid which were not observed on any other sampling date. Female rock bass were found to have higher liver glutathione concentrations than males throughout most of the study. Rock bass from both sites were also exposed to 150 ppb mercuric chloride for 96 hours in the laboratory. These results suggest that mercury exposure may cause a depression in the liver glutathione of these fish, although no changes in liver ascorbic acid were observed. Physiological measures on the rock bass maintained in the laboratory indicated this treatment was more stressful than confinement in cages in the river. / M.S.
2

Aspects of endocrine disruptors remediation using in vitro and in vivo ecotoxicological assays / Aspectos da remediação de disruptores endócrinos utilizando ensaios ecotoxicológicos in vitro e in vivo

Silva, Juliana Polloni [UNESP] 07 March 2017 (has links)
Submitted by JULIANA POLLONI SILVA null (ju_polloni@yahoo.com.br) on 2017-05-05T15:55:40Z No. of bitstreams: 1 Tese_UNESPSorocaba_JulianaPolloniSilva_2017.pdf: 5158035 bytes, checksum: 4293a506e5ebdca8245dde20cdbecec4 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-05-05T16:08:14Z (GMT) No. of bitstreams: 1 silva_jp_dr_soro.pdf: 5158035 bytes, checksum: 4293a506e5ebdca8245dde20cdbecec4 (MD5) / Made available in DSpace on 2017-05-05T16:08:14Z (GMT). No. of bitstreams: 1 silva_jp_dr_soro.pdf: 5158035 bytes, checksum: 4293a506e5ebdca8245dde20cdbecec4 (MD5) Previous issue date: 2017-03-07 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Produtos químicos capazes de causar desregulação endócrina em vertebrados e invertebrados têm sido detectados a baixas concentrações em ambientes aquáticos do mundo. Desta maneira, tornou-se de interesse mundial a busca por metodologias de remoção mesmos nos ambientes aquáticos. Por isso pesquisa teve como objetivo investigar três materiais (carvão ativado em pós – PAC, zeólitas naturais em pó – ZP e substâncias húmicas aquáticas – AHS) na remediação química e ecotoxicológica de 17ß-estradiol (E2) e 17α-etinilestradiol (EE2) em água mediante ensaios químicos e biológicos in vitro e in vivo. Uma concentração ambientalmente relevante de hormônios (30 ng.L-1) foi utilizada durante os ensaios em laboratório. Os resultados obtidos por meio de uma extensa relação de parâmetros morfológicos, reprodutivos e histológicos adotados permitiram concluir o significativo impacto dos HSFs sobre o desenvolvimento e manutenção de peixes expostos. Comprovou-se a superior eficiência do PAC em relação aos demais substratos na remoção de interferentes endócrinos (IEs) em água. Não obstante, suas propriedades não garantiram o mesmo desempenho com relação a amostras ambientais e, tampouco possibilitou a recuperação das injurias biológicas monitoradas após período de depuração investigado. Um estudo adicional também permitiu a elaboração de um protocolo histoquímico capaz de identificar a produção de vitelogenina (VTG) incitada pela exposição ao esteróide sintético EE2. / Chemicals with potential to cause endocrine disruption in vertebrates and invertebrates have been detected at low concentrations in the world's aquatic environments. Therefore, the search for removal methodologies in aquatic environments became a worldwide interest. The aim of this research was to investigate three materials (powered activated carbon - PAC, powered natural zeolites - ZP and aquatic humic substances - AHS) in chemical and ecotoxicological remediation of 17ß-estradiol (E2) and 17α-ethinylestradiol (EE2) in water through chemical and biological tests in vitro and in vivo. An environmentally relevant concentration of hormones (30 ng.L-1) was used during laboratory tests. The results obtained through an extensive list of morphological, reproductive and histological parameters showed the significant impact of HSFs on the development and maintenance of exposed fish. The superior efficiency of PAC was verified in relation to the other substrates in the endocrine disrupting chemicals (EDCs) removal in water. Nevertheless, their properties did not guarantee the same performance to the environmental samples, neither allow biological injuries monitored to be recovered after the period of depuration investigated. An additional study also allowed the development of a histochemical protocol capable of identifying the production of vitellogenin (VTG) prompted by exposure to the synthetic steroid EE2. / FAPESP: 2012/24495-6 / FAPESP: 2014/22733-2

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