M J Arezo

Publications (3)3.59 Total impact

• Source

  Available from: sdbonline.org

  Article: Sex differentiation pattern in the annual fish Austrolebias charrua (Cyprinodontiformes: Rivulidae).

  M J Arezo, S D'Alessandro, N Papa, R de Sá, N Berois
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  ABSTRACT: Sex differentiation process, determination of sexual strategy, and gametogenesis of the annual fish Austrolebias charrua are established. Evidence of histological sex differentiation in an antero-posterior gradient was observed in pre-hatching stages. Sexual strategy corresponds to the "differentiated gonochoric" pattern. Histological analyses of adult gonads showed an asynchronous spawning mode for females and continuous spawning for males. Mature oocytes presented fluid yolk. Testis organization corresponded to a restricted spermatogonial model. Herein, we report the ultrastructural organization of the vitelline envelope and the main features of the sperm of A. charrua. Taking together these results also contribute to phylogenetic studies and provide base line data to propose A. charrua as a biomonitor of contamination in a protected area.
  Tissue and Cell 04/2007; 39(2):89-98. · 1.04 Impact Factor
• Article: Ultrastructure and protein composition of the oocyte envelope in the whitemouth croaker (Micropogonias furnieri, Desmarest, 1823, Sciaenidae, Perciformes)

  N. Berois, M. J. Arezo, C. Chalar, M. M. Brauer, C. Barros
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  ABSTRACT: The organization, time-course deposition and protein composition of the oocyte envelope in the whitemouth croaker, Micropogonias furnieri, were analyzed at different stages of oocyte maturation. Adult females were sampled in the Uruguayan coast of the Río de la Plata during three annual periods. Morphological organization and temporal deposition were assessed by histology and electron microscopy. Protein composition was analyzed using gel electrophoresis, followed by MALDI-TOF-MS. Oocyte envelope deposition starts in lipid-yolk oocytes, reaching maximum width in fully grown oocytes when it shows a three-layer organization. In mature oocytes, the envelope becomes narrower than in the previous stage and loses its trilaminar structure. In envelopes from fully grown oocytes, one-dimensional gel electrophoresis revealed five bands; mature oocytes showed only three bands. Following two-dimensional gel electrophoresis, 14 major polypeptides were detected in envelopes from fully grown oocytes. Considering that morphological and biochemical results obtained from samples of the three annual periods were remarkably similar, data reported here might provide a useful baseline to assess the future impact of pollutants on the oocyte envelope and reproductive success of whitemouth croakers inhabiting the geographic area.
  Journal of Applied Ichthyology 01/2007; 23(1):34 - 39. · 0.87 Impact Factor
• Article: Early development in the annual fish Cynolebias viarius

  M. J. Arezo, L. Pereiro, N. Berois
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  ABSTRACT: The detailed characteristics and timing of early development in Cynolebias viarius, an annual fish endemic to Uruguay, were obtained from in vivo observations of embryos cultured under standardized laboratory conditions. The chorion ultrastructure is reported for this species for the first time. Comparison with previous data from other annual fishes showed that C. viarius exhibited the longest early development including cleavage, blastula formation and epiboly.
  Journal of Fish Biology 04/2005; 66(5):1357 - 1370. · 1.68 Impact Factor