Oocytes of The Endangered Gray Catfish (Surubim-Do-Paraiba) Submitted to Different Conservation Protocols.

BACKGROUND: The gray catfish known as Surubim-do-Paraíba (Steindachneridion parahybae), which is endemic to the Paraíba do Sul river basin, is on the red list of Brazilian fauna threatened with extinction and the cryopreservation of germ cells of this fish is needed in support of conservation. OBJECTIVE: We aimed to assess the effect of storage temperature on S. parahybae mature and immature oocytes. METHODS: Two trials were carried out. Trial I (TI.1-3) used 30 mature oocytes (diameter >1.8 mm) placed in cryoprotectant solutions and submitted to three different techniques. Trial II (TII.1-3) used 30 immature oocytes (diameter <1.6 mm) placed in cryoprotectant solutions and submitted to three storage temperatures (i.e., TII.1 at room temperature for 120 min; TII.2 in the freezer for 120 min; TII.3 in liquid nitrogen for 24 hours. RESULT: The mature oocytes were sensitive to every protocol used, including at room temperature. In contrast, the immature oocytes had increased sensitivity according to the temperature reduction to which they were submitted, with the treatment in liquid nitrogen causing greater damage. CONCLUSION: The immature stages exhibit more promising results, encouraging further studies using the combination of different CPSs, mainly penetrating ones, in oocyte cryopreservation protocols.

Processo de maturação das gônadas de pintado (Pseudoplatystoma corruscans) alimentado com dois níveis proteicos e suplementados com óleo de milho / Process of gonad maturation of Pseudoplatystoma corruscans fed diets containing different levels of protein and supplemented with corn oil

Investigou-se o efeito da adição de C18:2n6, por meio da inclusão de óleo de milho em dietas com dois níveis de proteína bruta, sobre o processo de maturação de gametas de pintado, Pseudoplatystoma corruscans, mantidos em tanques-rede. Foram avaliados: taxa de sobrevivência, relação peso x comprimento, fator de condição (K) e índice gonadossomático (IGS). O experimento foi realizado entre março de 2004 e fevereiro de 2006, em 12 tanques-rede, distribuídos em seis viveiros-escavados de 600m² e densidade de estocagem de 20 peixes/tanque-rede. Utilizaram-se três tratamentos (T) com duas repetições/viveiro: T1 com 28 por cento de PB; T2 com 28 por cento de PB + 5 por cento óleo de milho e T3 com 40 por cento de PB. O crescimento foi ligeiramente mais alto nos peixes do T3. As taxas de sobrevivência foram acima de 77 por cento. Pode-se inferir que as rações ofertadas não causaram alterações histomorfológicas durante o processo de maturação gonadal dessa espécie. O IGS e o K foram ligeiramente mais altos nos animais alimentados com a ração enriquecida com óleo de milho.

It was studied the effect of the addition of C18:2n6, by the inclusion of corn oil, in diets with different levels of crude protein (CP) on the process of gonad maturation in surubim, Pseudoplatystoma corruscans. Survival rate, weight x length ratio, condition factor (K), and gonadossomatic index (GSI) were evaluated. The experiment was carried out from March 2004 to February 2006, using 12 cages distributed in six tanks, with 20 fishes per cage. Three treatments (T) were: T1 28 percent CP; T2 28 percent CP + 5 percent corn oils, and T3 40 percent CP. No effect of the diet was observed on growth in the 1st and 2nd years of age, with a slightly superior growth of T3 fish. The survival rates were superior to 77 percent. It can be inferred that the offered diet did not cause histomorphological alterations during the process of gonadal maturation of this species. However, the GSI and the K were slightly advanced and superior in the animals fed the diet supplemented with corn oil.

Patterns of oocyte development in natural habitat and captive Salminus hilarii Valenciennes, 1850 (Teleostei: Characidae).

Fecundity and oocyte development in Salminus hilarii female brood stock were analyzed with the aim of investigating the impact of migration impediment on oogenesis. Histological analyses of the ovaries were performed in adult females caught in two different environments--the Tietê River (natural) and captivity--and the gonadossomatic index, oocyte diameter and fecundity determined. Five germ cell development stages (oogonium, perinucleolar, cortical alveoli, vitellogenic, ripe) and two other structures (postovulatory follicles and atretic oocytes) were observed in females caught in the river. Captive animals lacked the ripe oocytes and postovulatory follicles and had a relatively higher number of atretic oocytes. Females in captivity are known to produce larger oocytes, and they release fewer eggs in each spawn (absolute fecundity) when compared with animals that are able to migrate. Our results suggest that the Tietê River is undergoing alterations which are being reflected in the reproductive performance of S. hilarii, mainly due to the presence of atretic oocytes in females caught in the river. The lack of postovulatory follicles and ripe oocytes in captive animals reveals that migratory impediment negatively impacts final oocyte maturation. However, the stage of maturation reached is adequate for ovulation induction with hormone manipulation.

Occurrence and significance of ovarian and follicular regression in cachara Pseudoplatystoma fasciatum (Linnaeus, 1766): a histology approach

The processes of ovarian regression and follicular atresia which reproduction was not induced by hormone in confined cachara, Pseudoplatystoma fasciatum, were investigated. The macro and microscopic characteristics (oocytes diameter and histology) of the ovaries were described every 20 days, in four stages: initial regression (Rg I = first 20 days), intermediate regression (Rg II = from 21st to 40th day), final regression (Rg III = from 41st to 80th day) and the recovering stage, called resting II (R II = from 81st to 150th day). The experiment was conducted from late January (summer - longer days) to May (autumn - shorter days). In the beginning, A0 samples showed oocyte diameters ranging from 437.5 to 1,187.5mm, suggesting that oocytes were in perinucleolar, at final maturation and atretic phases. After 150 days, the diameters reached the lowest values and a ruptured zona radiata, as well as the nearly complete reabsorption of the yolk could be visualized. At the same time, a sharp decrease in the mean values of the gonadosomatic index (GSI), water temperature, photophase and rainfall was observed. The gradual involution of this long process was dynamic and complex, affecting the spawning success (fertilization, eclosion and larvae survival rates) and, consequently, the whole productive system.

Estudaram-se os processos de regressão ovariana e atresia folicular em cachara, Pseudoplatystoma fasciatum, mantida em cativeiro, na reprodução não induzida por hormônios. As características macro e microscópicas (diâmetro dos ovócitos e histologia) dos ovários foram descritas a cada 20 dias, em quatro estádios: na regressão inicial (Rg I - os primeiros 20 dias), na regressão intermediária (Rg II - do 21° ao 40° dia), na regressão final (Rg III - do 41° ao 80° dia) e na fase de recuperação ou de repouso II (R II - do 81° ao 150° dia). O experimento foi realizado do final de janeiro (verão-dias longos) a maio (outono-dias curtos). No início do experimento, as amostras apresentaram ovócitos com diâmetros que variaram de 437,5 a 1.187,5mm, sugerindo encontrarem-se nas fases perinucleolar, de maturação final e atrésicos. Aos 150 dias, os diâmetros atingiram os menores valores e pôde-se visualizar a zona radiata rompida e o vitelo reabsorvido. Concomitantemente, houve diminuição abrupta dos valores médios do índice gonadossomático, da temperatura da água, das horas de luz e de chuva. A involução gradual do longo processo foi dinâmica e complexa, afetando o êxito da desova (taxas de fertilização, de eclosão e de sobrevivência de larvas) e, conseqüentemente, o sistema produtivo.

The reproductive cycle of male catfish Pseudoplatystoma fasciatum (Teleostei, Pimelodidae) revealed by changes of the germinal epithelium. An approach addressed to aquaculture.

The aims of the present study were to analyze the gonadal structure of Pseudoplatystoma fasciatum males during their annual cycle to enhance understanding of their reproductive biology and to improve the hormonally induced reproduction and culture of this species in hatcheries. We adopted the recently proposed method that establishes reproductive classes that are based on variations of the germinal epithelium within the year. Five reproductive classes were established: maturation (early, middle, and late), regression and recrudescence. Our observations revealed that in the spawning season P. fasciatum testes display two main functions: sperm production and sperm storage. We also concluded that the analysis of the variation of germinal epithelium was satisfactory when applied to this freshwater catfish and should be adopted for other fish species.

Light and electron microscopy oogenesis in matrinxã, Brycon cephalus.

Oocyte development has been divided into 5 distinct stages in the reared matrinxã, Brycon cephalus, based on morphological criteria by light and transmission electron microscopy: I) chromatin-nucleolus; II) perinucleolar; III) cortical alveoli; IV) vitellogenesis; V) final maturation. In stages I and II (primary growth), oocytes reside in nests close to other oocytes (chromatin-nucleolus phase) and then within a definitive follicle (perinucleolar phase) where they greatly increase in size (the Balbiani vitelline body is the main cytoplasmic component in these latter oocytes), respectively. In stage III (cortical alveolus phase) oocytes are distinguished by the appearance of variably sized cortical alveoli and the number of these structures increases steadily towards hydration. The vitelline envelope becomes prominent. In the process of vitellogenesis (stage IV) one major accumulation of yolk proteins occurs in oocytes. In stage V (final maturation), oocyte increase slightly in size. Follicle cells go through a primordial stage and later change to a squamous and to a cubical shape. The chorion grows to a tripartite structure: an outer thin porous layer, an intermediate homogenous layer and an inner thick helicoidal layer. The ovulation of females matrinxã, required hormonal stimulation and this occurred 6 and 8 h after the second application.

Ultrastructure of the germ cells in the testis of matrinxã, Brycon cephalus (Teleostei, Characidae).

This study describes at ultrastructural level the germ cells in the testis of matrinxã (Brycon cephalus) raised in captivity. The specimens 'matrinxã' were maintained in four breeding tanks of 200 m(2), at the Aquaculture Research Center at Vale do Ribeira-CEPAR, from Fishery Institute, in Pariquera-Açu City, São Paulo, Brazil. The samples were collected from March 1994 to February 1996. The testis has been classified as tubular unrestricted spermatogonial type, in which four stages of germ cells can be distinguished as follows: spermatogonia, spermatocytes (primary and secondary); spermatids and spermatozoa.