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Weber A.A.,Pontifical Catholic University of Minas Gerais | Arantes F.P.,Pontifical Catholic University of Minas Gerais | Sato Y.,Estacao de Hidrobiologia e Piscicultura de Tres Marias | Rizzo E.,Federal University of Minas Gerais | Bazzoli N.,Pontifical Catholic University of Minas Gerais
Zygote | Year: 2013

Summary This study shows for the first time the presence of a jelly coat on oocytes of neotropical Characiformes fish. This structure could be responsible for the adhesiveness of Astyanax bimaculatus oocytes, a species widely distributed in South America including in the São Francisco River basin in Brazil. Adult specimens of A. bimaculatus were submitted to artificial reproduction in order to analyse the egg morphology and embryonic development. The eggs were fertilised and kept in incubators with a water temperature of 24°C so that embryogenesis could be monitored. Ovulated and unfertilised oocytes were also collected and submitted to routine histological techniques. Astyanax bimaculatus oocytes were found to be spherical, yellowish, and covered by a thin jelly coat with a slightly adhesive surface. The mean oocyte diameter was 1.03 ± 0.03 mm, the perivitelline space was 0.21 ± 0.02 mm and the jelly coat's thickness was 0.04 ± 0.01 mm. Positive periodic acid-Schiff (PAS) stain and Alcian blue stain pH 2.5 indicated the presence of neutral glycoproteins, and carboxylated acid glycoconjugates on the jelly coat that formed mucosubstances that may be associated with egg adhesiveness. At a water temperature of 24°C, blastopore closure and hatching occurred at 5 h and 17 h after fertilisation, respectively. The results of this study provide essential information for phylogenetic studies and for a better understanding of the reproductive strategy of A. bimaculatus, currently included in the incertae sedis group of the Characidae family due to the lack of monophyly among the families of the group. © Cambridge University Press 2012. Source


Perini V.R.,Federal University of Minas Gerais | Sato Y.,Estacao de Hidrobiologia e Piscicultura de Tres Marias | Rizzo E.,Federal University of Minas Gerais | Bazzoli N.,Pontifical Catholic University of Minas Gerais
Journal of Veterinary Medicine Series C: Anatomia Histologia Embryologia | Year: 2013

Curimatella lepidura and Steindachnerina elegans are small forage fish, constituting an important link in the food chain, serving as food for larger commercial fish. In this study, characteristics of the eggs, of the oocyte's surface ultrastructure and of the embryogenesis are first described for these species. Absolute fecundity was 40864 ± 8769 oocytes for C. lepidura and 22089 ± 8710 oocytes for S. elegans. Oocytes of both species are yellowish, weakly adhesive and with a post-fertilization diameter of 1019.5 ± 20.6 μm and 978.75 ± 29.16 μm for C. lepidura and S. elegans, respectively. The ultrastructural analysis, using scanning electron microscopy, showed that the oocyte's surface of both species has pore canals over the entire surface and a funnel-shaped micropyle. At 24°C, the embryonic development of C. lepidura was completed 25 h after fertilization, and blastopore closure occurred in 7 h 30 min. In S. elegans, larvae hatched 20 h after fertilization, and blastopore closure occurred in 7 h 15 min. The fertilization rate was 74.5 ± 7.96 and 71.2 ± 10.8% for C. lepidura and S. elegans, respectively. This study provides important support for clarifying phylogenetic relationships and in ecological and zoological understanding of Neotropical Curimatidae fish. © 2012 Blackwell Verlag GmbH. Source


Arantes F.P.,Federal University of Minas Gerais | Arantes F.P.,Pontifical Catholic University of Minas Gerais | Santos H.B.,Federal University of Minas Gerais | Rizzo E.,Federal University of Minas Gerais | And 2 more authors.
General and Comparative Endocrinology | Year: 2011

Most fishes with commercial importance from the São Francisco basin are migratory and do not complete the reproductive cycle in lentic environments, such as hydroelectric plant reservoirs, hence natural stocks are declining and there is an urgent need to reduce the pressure of fishing on those wild populations. Therefore, studies on reproductive biology and its relationship with endocrine and environmental factors are key to improving the cultivation techniques of Brazilian fish species. This study examined the influence of water temperature on sex steroid concentrations (testosterone, 17β-estradiol and 17α-hydroxyprogesterone), spawning efficiency, fecundity, fertilisation rate, larval abnormality rates and involvement of the cytoskeleton during the final oocyte maturation of Prochilodus argenteus under experimental conditions. The results of our study showed that in captivity, sex steroid plasma concentrations and spawning performance of P. argenteus were clearly different for fish kept in water with different temperature regimes. In lower water temperature (23 °C), it was observed that: 33% of females did not ovulate, fecundity was lower and vitellogenic oocytes after the spawning induction procedure exhibited a smaller diameter. Moreover, concentrations of 17β-estradiol and 17α-hydroxyprogesterone were lower and there was a delay in the final oocyte maturation and, consequently, ovulation and spawning. Our experiments showed direct influence of water temperature in the process of induced spawning of P. argenteus. Changes in water temperature also suggest the tubulin involvement in the nuclear dislocation process and the possible action of actin filaments in the release of polar bodies during final oocyte maturation of P. argenteus. © 2011 Elsevier Inc. Source


Da Rocha Perini V.,Pontifcia University Catolica Of Minas Gerais | Sato Y.,Estacao de Hidrobiologia e Piscicultura de Tres Marias | Rizzo E.,Federal University of Minas Gerais | Bazzoli N.,Pontifcia University Catolica Of Minas Gerais
Zygote | Year: 2010

The black armoured catfish Rhinelepis aspera is an important commercial species found in the So Francisco River (Brazil) that has great potential for pisciculture. This paper presents, for the first time, information on the embryogenesis and larval development of this species. The breeder fish were subjected to spawning induction with crude carp pituitary extract. Eggs were kept in incubators at 24C and embryogenesis was observed with a stereomicroscope until hatching. Ovary fragments, samples of recently extruded oocytes and larvae were fixed in Bouin's solution and subjected to routine histology techniques. Recently extruded oocytes were also analyzed with a scanning electron microscope (SEM). Females (80%) had a positive response to hypophysation. Oocyte extrusion was performed at 8 h and 30 min after the second hormone injection and the fertilization rate achieved 72.4 8.8%. Recently extruded oocytes had a mean diameter of 1360.80 40.87 m and presented a conspicuous jelly coat covering the zona pellucida. Histochemical reactions indicated the presence of neutral glycoproteins in the yolk globules and in the zona pellucida. These reactions also indicated the presence of neutral glycoproteins and carboxylated acid glycoconjugates in the follicular cells and the jelly coat. These compounds form mucosubstances that can be related to the adhesiveness of the eggs. Under the SEM the oocytes presented a micropyle disc and a thick jelly coat over their surface. The closure of the blastopore occurred 9 h and 40 min after fertilization and embryogenesis was completed at 45 h and 50 min after fertilization, when the embryos were incubated at 24C. The total absorption of the yolk sac occurred during the fifth day indicating the need for an exogenous food supply. These results provide essential information for the successful breeding and management of the promising R. aspera. Copyright © 2009 Cambridge University Press. Source


Arantes Fabio.P.,Federal University of Minas Gerais | Santos H.B.,Federal University of Minas Gerais | Rizzo E.,Federal University of Minas Gerais | Sato Y.,Estacao de Hidrobiologia e Piscicultura de Tres Marias | Bazzoli N.,Pontifical Catholic University of Minas Gerais
Animal Reproduction Science | Year: 2010

The present study evaluated for the first time sex steroid profiles and fecundity in females of Prochilodus argenteus from two sections of the São Francisco River Brazil, downstream from the Três Marias Dam, which influences characteristics of their water habitat. The model species in the study, P. argenteus, is an important commercial and recreational species in Brazil. In the region closest to the dam (section 1), females did not reach final oocyte maturation, failed to spawn, and displayed lesser circulating concentrations of testosterone, 17(-hydroxyprogesterone (17(-P) and 17β-estradiol (E2) than those farther downstream of the dam (section 2). The endocrine and fecundity deficiencies probably are attributed to lower water temperature and oxygen concentration in (section 1). The follicular atresia rate in the region closest to the dam (26%) was greater than those fish captured farther downstream of the dam (13%), after the Abaeté River (section 2). Variations in testosterone, E2 and 17(-P concentrations in section 2, followed gonadal maturation which are typical features of species which have seasonal reproduction, group-synchronous oocyte development, and are single batch spawners such as P. argenteus. Results document the first evidence of endocrine and reproductive dysfunctions caused by inadequate water conditions in a wild population of the migratory species P. argenteus in the São Francisco River, downstream from the Três Marias dam. © 2009 Elsevier B.V. All rights reserved. Source

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