Browsing by Author "Domingues, Nuno Manuel Cardoso"
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- Gene expression during oogenesis in the Mozambique tilapia (O. Mossambicus)Publication . Domingues, Nuno Manuel Cardoso; Canario, Adelino V. M.; Deloffre, LaurenceTilapias show a variety of physiological adaptations that allow them to live in different environmental conditions, disturbing local ecosystems where they are introduced by human hand, where they reproduce at faster rates as their cycles are short and constant. They have complex behaviours, with species in the Oreochromis and Sarotherodon genus exhibiting parental care. Thus, they have become a preferred research species. Knowledge on their physiology might benefit the medical sciences, the fisheries industry, environmentsl sciences and aquaculture, which is still the major player in sex genes research, as tilapias fish are the second most cultured species worldwide and there are problems with their high spawning rates as these originate high density stocks in tanks. There is considerable information concerning the hypothalamus-pituitary-gonadal axis in vertebrates, with gonadotrophins (FSH and LH) playing stimulating roles in development of the ovary and maturation of oocytes. Other hormones and factors are involved, mediating the actions of these or as products of their induction. The early stages of development of the ovarian follicle and the enveloped oocytes are still poorly described, with FSH being considered the first inducer for decades. This implies a role for local factors that are regulating the early stages of growth. Recently, TGF-β family member activin has been shown to induce FSH incorporation by the follicles and other members of this family also seem to have an important role in the ovary, such as BMPs and GDFs. Some other factors were studied in this thesis for expression patterns throughout oocyte development. With this objective, ovaries from 8 females were extracted and dissected under a binocular amplifier with groups of oocytes in 4 different stages being collected for each. RNA was extracted and purified and turned into cDNA by reverse transcription. Genes with preferential expression in ovary (determined by subtractive hybridization and then with semiquantitative RT-PCR) were tested by RT-PCR in oocytes and band intensity was quantified using Quantity One from Biorad, using as reference 18S rRNA. These genes include FoxL2, CYP19a, Vasa, RBMX, BMP-R IB, CPI-17, Aly and other unidentified fragments: SART, PPMP (homolog sequences but not confirmed) and XP2 (putative new protein) and clone 26 (no homolog sequence known). Results show significant differences among the 4 oocyte stages for practically every gene tested, except for Aly and SART. Correlations among some of the genes also show they might have related functions in the process.