Endocrine-disrupting compounds (EDCs) interfere with the physiology of hormone systems. Traditionally, steroidogenic pharmaceuticals have been studied as EDCs however there has been growing evidence that non-steroidogenic pharmaceuticals can alter sex steroid levels and impair reproductive functions in fish. This is of concern as pharmaceuticals are detected in surface waters at the ng L-1 to µg L-1 range. Zebrafish (Danio rerio) were exposed to 10 µg L-1 of the pharmaceuticals carbamazepine and gemfibrozil for 6 weeks. Male-biased sex ratios were observed in the sexually mature offspring after paternal exposure, suggesting that sexual differentiation may be impacted in juveniles. Currently, the ability of pharmaceuticals to interfere with sexual differentiation of parentally exposed offspring is unknown. This thesis examined the gonad histology of juvenile zebrafish to understand how sexual differentiation was affected in the offspring of exposed parents. Paternal, but not maternal, exposure to carbamazepine resulted in a significantly faster sexual differentiation of the gonads and led to a male-biased sex ratio; these effects were not observed when both parents were exposed. Combined paternal and maternal exposure to gemfibrozil resulted in significantly faster sexual differentiation and paternal, but not maternal, exposure to gemfibrozil led to male-biased sex ratios. Interestingly, sex ratios observed in the juveniles did not always reflect those found in the same lineage at sexual maturity, suggesting a sex reversal, including a male to female transition, occurred past the juvenile sexual differentiation period in some fish. This thesis demonstrates that pharmaceuticals have the ability to disrupt sexual differentiation in the F1 offspring of exposed parents and that paternal exposure is most relevant for offspring effects. / Thesis / Master of Science (MSc) / Parental exposure to the environmentally-relevant pharmaceuticals carbamazepine or gemfibrozil led to male-biased sex ratios in adult offspring of zebrafish (Danio rerio), a common model organism. The development of the gonads in juveniles was investigated to determine how this process was impacted. Predominately, paternal exposure was found to result in a faster development of the testes and male-biased sex ratios. Interestingly, sex ratios in juveniles did not always reflect those in adults, suggesting a sex reversal may have occurred in adulthood. This study demonstrates the ability of pharmaceuticals to alter gonad development in offspring of exposed parents.

Made available in DSpace on 2014-12-17T14:03:43Z (GMT). No. of bitstreams: 1 AdilaLML.pdf: 743306 bytes, checksum: 8c2b4b2827dafcc2f2edd7664a266e10 (MD5) Previous issue date: 2006-11-30 / Two b-N-acetylhexosaminidases (F11 e F15) were purified from Echinometra lucunter gonads extracts. The purified enzymes were obtained using ammonium sulfate fractionation, followed by gel filtration chromatographies (Sephacryl S-200, Sephadex G-75 and Sephacryl S-200). The F11 fraction was purified 192.47 -fold with a 28.5% yield, and F15 fraction 85.41 -fold with a 32.3% yield. The molecular weights of the fractions were 116 kDa for F11 and 42 kDa for F15 using SDS-PAGE. In Sephacryl S-200, F15 was 84 kDa, indicating that it is a dimeric protein. When p-nitrophenyl-?-D-glycosaminide was used as substrate, we determined an apparent Km of 0.257 mM and Vmax of 0.704 for F11 and for F15 the Km was 0.235 mM and Vmax of 0.9 mM of product liberated by hour. Both enzymes have optimum pH and temperature respectively at 5.0 and 45 ?C. The enzymes showed inhibition by silver nitrate, while the glucuronic acid was a potent activator. The high inhibition of F15 by N-etylmaleimide indicates that sulphydril groups are involved in the catalysis of synthetic substrate / Neste trabalho foram purificadas e caracterizadas parcialmente duas N-acetil-b- hexosaminidases (F11 e F15) extra?das de g?nadas do equinoderma marinho Echinometra lucunter. As enzimas foram purificadas com protocolo seq?encial por precipita??o com sulfato de am?nio e cromatografias de exclus?o molecular (Sephacryl S-200, Sephadex G-75 e Sephacryl S-200). A fra??o F11 foi purificada 192,47 vezes com recupera??o de 28,5% e F15 85,41 vezes com recupera??o de 32,3%. Suas massas moleculares, determinadas por eletroforese em gel de poliacrilamida com SDS, foram respectivamente 116 e 42 kDa. Em Sephacryl S-200 F15 apresentou massa molecular de 84 KDa, sugerindo que esta enzima possui forma dim?rica. Utilizando-se p-nitrofenil N-acetil-b-glicosamin?deo como substrato obtivemos Km aparente de 0,257 mM e Vmax de 0,704 unidades de absorb?ncia a 405 nm / h para a fra??o 11, e 0,235 mM e Vmax de 0,9 unidades de absorb?ncia a 405 nm / h para F15. Ambas fra??es apresentaram pH e a temperatura ?tima de cat?lise 5,0 e 45 ?C, respectivamente. A atividade N-acetil-b-glicosaminid?sica foi potencialmente inibida por prata, iodoacetamida, N-etilmaleimida e PMSF. A forte inibi??o de F15 por N-etilmaleimida indica o envolvimento de radicais sulfidrila na hidr?lise do substrato sint?tico, caracterizando tamb?m ser uma enzima altamente sensitiva a este sal