Time filter

Source Type

Thome R.G.,Federal University of Minas Gerais | Domingos F.F.T.,Federal University of Minas Gerais | Santos H.B,Federal University of Säo João del Rei | Martinelli P.M.,Federal University of Minas Gerais | And 3 more authors.
Tissue and Cell | Year: 2012

Aiming to better understand folliculogenesis, this study evaluated cell death and proliferation of ovarian cells, besides cathepsin-D expression in Prochilodus argenteus captured in two sites of the São Francisco River downstream from the Três Marias Dam, Brazil. In the site immediately following the Dam (S1), low levels of dissolved oxygen were registered in the rainy period. The water temperature was higher in the São Francisco River immediately after the confluence with the Abaeté River (S2), regardless of the period. In S1, the ovaries showed smaller oocytes, high caspase-3 enzymatic activity and apoptosis, lower cells in proliferation and GSI, as well as a lesser quantity of cathepsin-D when compared to females captured from S2. Regarding relative frequency of ovarian structures, in the dry period, only oogonia and perinucleolar oocytes were found in fish ovaries from both sites. On the other hand, in the rainy period, the relative frequency of oogonia and perinucleolar oocytes decreased and the vitellogenic oocytes increased in S2. Postovulatory follicles were observed only in S2, whereas atretic follicles occurred at a higher frequency in S1. Our results showed that apoptosis, cell proliferation and cathepsina-D evaluation can be used as biomarkers of environmental impact. © 2011 Elsevier Ltd.

Thome R.,Federal University of Minas Gerais | Dos Santos H.B.,Federal University of Minas Gerais | Sato Y.,Estacao de Hidrobiologia e Piscicultura de Tres Marias CODEVASF | Rizzo E.,Federal University of Minas Gerais
Journal of Molecular Histology | Year: 2010

Extracellular matrix in the ovarian follicle has been characterised for several mammalian species but there are no reports that describe the immunolocalisation of the extracellular matrix elements, matrix metalloproteinases, and its relation to plasma 17β estradiol levels and follicular apoptosis during the teleost's reproductive cycle. The present study used immunohistochemistry to characterise the distribution of laminin β2, collagen type IV, fibronectin and matrix metalloproteinases-9 (MMP-9). The TUNEL in situ technique was used to quantify apoptosis and indirect immunofluorimetric to determine plasma 17β estradiol levels. The TUNEL-positive reaction associated with morphological features exhibited follicular apoptosis. During postovulatory follicle involution, the drop in plasma 17β estradiol levels after spawning contributed to the intense apoptosis observed. By immunohistochemical analysis, laminin β2 and collagen type IV were identified as the major constituents of the basement membrane. The loss of integrity of the basement membrane occurred due to lyses of the major constituents, and coincides with increased follicular apoptosis. The integrity of the basement membrane is important for the survival of follicular cells. Furthermore, the MMP-9 results suggest that this enzyme is involved in final oocyte maturation and regression of postovulatory follicles. Fibronectin was observed on the surface of follicular cells of the postovulatory follicle in P. argenteus, this being important for maintaining normal cell adhesion to extracellular matrix. In conclusion, our results suggest that the structure and composition of the extracellular matrix, and plasma 17β estradiol levels related to apoptosis, play an important role during the follicular development and post-spawning involution in teleost fishes. © 2010 Springer Science+Business Media B.V.

Pereira Arantes F.,Federal University of Minas Gerais | Batista dos Santos H.,Federal University of Minas Gerais | Rizzo E.,Federal University of Minas Gerais | Sato Y.,Estacao de Hidrobiologia e Piscicultura de Tres Marias CODEVASF | Bazzoli N.,Pontifical Catholic University of Minas Gerais
Journal of Applied Ichthyology | Year: 2011

Generally, migratory fish can complete vitellogenesis even when the migration process is interrupted; however, final oocyte maturation does not occur and therefore there is no spawning. To evaluate the reproductive process of migratory fish inside the reservoir of the Três Marias Dam (a lentic environment), 90 female and 81 male Prochilodus argenteus and 172 female and 115 male Prochilodus costatus were captured in this environment. Males and females from both species in the resting stage were pre-dominant, and the highest frequency of specimens in advanced maturation stages occurred in November, December and January. According to histological analysis, ovarian regression was frequent and vitellogenic oocytes undergoing atresia were intensely observed, moreover, no fish with ovaries and testes with characteristics of spawning and spermiation, respectively, were captured. This indicated that both species were preparing for reproduction and reaching advanced gonad maturation, but were unable to complete the process of reproduction in this environment. The data from this study indicate that the modification of portions of rivers to lentic environments can have a negative impact on the reproductive process of migratory fish in freshwater. © 2010 Blackwell Verlag, Berlin.

Loading Estacao de Hidrobiologia e Piscicultura de Tres Marias CODEVASF collaborators
Loading Estacao de Hidrobiologia e Piscicultura de Tres Marias CODEVASF collaborators