Thesis (MSc)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (MA)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (M.Sc.). / Written for the Dept. of Biology. Title from title page of PDF (viewed 2009/07/02). Includes bibliographical references.

Nile red and Nile blue are intensely colored fluorescent dyes from the benzophenoxazine family. Modification of the donor amine with varying alkyl substituents was achieved with the principle aim being to investigate differences, both optical and physical, between dye scaffolds outfitted with secondary amines versus tertiary amines. These changes to the dyes’ architectural framework gave holistic effects to the bulk molecule by modulating hydrophobicity, optical properties, and protein binding constants to human serum albumin.

Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Thesis (M.Sc.)--York University, 2007. Graduate Programme in Mathematics and Statistics. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR29300

Inaug.-Diss.--Halle-Wittenberg. / Vita.

Thesis--Eberhard-Karis-Universität zu Tübingen. / Vita. Includes bibliographical references.

Sex steroids are generally considered as natural sex inducers in fish. Aromatase (cytochrome P450 aromatase) catalyses androgens into oestrogens in the steroidogenic pathway. Three different approaches were taken to elucidate the action of aromatase in relation to sex differentiation in the Nile tilapia Oreochromis niloticus. The first was treatment with Fadrozole TM,a non-steroidal aromatase inhibitor (Al), by incorporating it in the diet or by immersing fish in a solution containing Al during the sex differentiation period. The Al treatment masculinised genetic females, indicating the importance of aromatase in sex differentiation. The result revealed that the most sensitive time to Al lies between 11-18 dpf (days post fertilisation). A partial brain type aromatase cDNA (1707bp) was identified from a brain cDNA library of O. niloticus. The amino acid sequence (that corresponds to exon 2-9) derived from this showed 63.7% identity to a previously reported ovarian aromatase gene of this species, and 96.7% identity to the brain type aromatase gene of a closely related species O. mossambicus. A semi-quantitative RT-PCR method was established to investigate expression of brain and ovarian aromatase genes during ontogeny. No sexually dimorphic expression of brain aromatase mRNA was detected. However, expression of ovarian aromatase was down-regulated from 15 to 23 dpf in genetic males but upregulated in genetic females. This period overlaps closely with the most sensitive period to Al. The pattern of temperature-dependent sex determination (TSD) was examined using three different genotypes (XX, XY, YY) at two temperatures (28 and 36°C). The results showed a bidirectional pattern of TSD. YY groups showed a significant percentage of feminisation at the higher temperature, which was suppressed by the Al treatment, implying that aromatisation is mechanistically associated with TSD in this species.All of these data consistently suggest that aromatase plays a crucial role in sex differentiation, and that the decisive aromatisation takes place between 13-25 dpf in this species. Considering the timing (26-30 dpf) of the first appearance of steroid producing cells in the gonadal area, the decisive aromatisation is not likely to take place there. The brain could be the primary aromatisation site in fish sex differentiation.

Inaug.-Diss.--Halle-Wittenberg. / Vita.