Reproductive seasonality of fishes from a lotic stretch of the Grande River, high Paraná river basin, Brazil

Foi investigada a correlação entre nível hidrológico, pluviosidade e temperatura e reprodução de peixes num trecho lótico do rio Grande, abaixo da barragem de Volta Grande. Para a captura, realizada com redes de espera, foram feitas seis amostragens bimestrais de abril de 1998 a fevereiro de 1999. As gônadas foram classificadas de acordo com o estádio de maturação e aquelas maduras ou esgotadas foram correlacionadas com as variáveis ambientais. A maioria das espécies apresentou reprodução sazonal, entre outubro e fevereiro. A freqüência relativa bimestral de gônadas maduras ou esgotadas de todos os exemplares agrupados foi correlacionada significativamente com pluviosidade (Spearman r = 0,94, p = 0,005) e temperatura do ar (r = 0,84, p = 0,036), mostrando a importância destes fatores no controle do ciclo reprodutivo dos peixes. Devido à barragem, o nível hidrológico pouco variou e não foi encontrada correlação significativa entre reprodução e nível hidrológico (r = -0,43, p = 0,396).

Estimativa da concentração espermática do sêmen de peixe pelo método de espermatócrito

Um experimento foi realizado com o objetivo de estimar a concentração espermática das espécies dourado (Salminus brasiliensis), curimba (Prochilodus lineatus), jundiá (Rhamdia quelen), cascudo-preto (Rhinelepis aspera) e tilápia-do-nilo (Oreochromis niloticus) pelo método de espermatócrito. Utilizaram-se 19, 58, 51, 43 e 85 reprodutores de dourado, curimba, jundiá, cascudo-preto e tilápia-do-nilo, respectivamente. Com exceção da tilápia-do-nilo, os reprodutores foram submetidos ao processo de indução hormonal e posteriormente submetidos a coleta de sêmen. Foram comparadas as técnicas de mensuração da concentração espermática do sêmen por contagem em câmara hematimétrica de Neubauer e por espermatócrito. Os resultados obtidos foram submetidos à análise de regressão a 5% de probabilidade. As concentrações espermáticas mensuradas por ambas as técnicas apresentaram relação linear, para curimbas, jundiás e tilápias-do-nilo, com equações y = 6,6624 × 10(9) + 3,68553 × 10(8)x; y = 2,153 × 10(9) + 4,426 × 10(8)x e y = -9,0897 × 10(8) + 6,0167 × 10(8), respectivamente. O método de espermatócrito pode ser utilizado para estimar a concentração espermática do sêmen de curimbas, jundiás e tilápias-do-nilo.

Temporal distribution and composition of the ichthyoplankton from Leopoldo's Inlet on the Upper Parana River floodplain (Brazil)

Temporal distribution and composition of ichthyoplankton and their relationships with some environmental variables of Leopoldo's Inlet (Ressaco do Leopoldo) on the upper Parana River floodplain, southern Brazil, were analysed. Samples were taken from February 1991 to February 1992, and 3480 larvae were collected. The highest density of larvae was observed in November 1991 (36.79 larvae/ 10 m(3)) at night (night/day ratio 7: 1). Species composition showed a predominance of Characiformes (80%). There was a high density (4.28 larvae/10 m(3)) of Bryconamericus stramineus throughout almost the whole study period, the majority of the species were more frequently collected at night. Pearson's correlation indicated a relationship between larval density, temperature, and pluviometric index. Leopoldo's Inlet, whose ichthyofauna is mainly composed of grazing and resident species. shows favourable conditions for fish reproduction and development.

Ovulação de matrizes de pacu Piaractus mesopotamicus e o papel da prostaglandina F2α

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Indução à reprodução e desenvolvimento embrionário e larval do ciclídeo acará-açu Astronotus ocellatus (Agassiz, 1831)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Suplementação de selênio orgânico em dietas de reprodutores de tilápia-do-Nilo (Oreochromis niloticus)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Proteína bruta na alimentação de reprodutores do pacu, Piaractus mesopotamicus criados em tanques-rede

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência da ingestão do triptofano dietético sobre a preferência na escolha do macho pela fêmea, auto-balanceamento da dieta e desempenho zootécnico em tilápia-do-Nilo e Pirapitinga

Pós-graduação em Aquicultura - FCAV

Hatching, survival and deformities of piracanjuba (Brycon orbignyanus) embryos subjected to different cooling protocols

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Egg surface structure of the freshwater toadfish Thalassophryne amazonica (Teleostei: Batrachoididae) with information on its distribution and natural habitat

The egg surface structure of Thalassophryne amazonica, a freshwater toadfish from the Amazon basin is described. Eggs of this species show a remarkable, highly unusual system of parallel ridges and intermittent grooves that originate at the equator of the egg and lead to the micropylar pit, at which they end in a spiralling pattern. A similar egg surface structure has so far been described only from a group of Asian anabantoid percomorphs, obviously not closely related to Thalassophryne. This egg surface pattern may enhance fertilization success by guiding sperm to the micropyle. We review museum records for T amazonica, present an updated map of its occurrence in the Amazon basin, and provide information on its habitat.

Gonadal steroids levels and vitellogenesis in the formation of oocytes in Prochilodus lineatus (Valenciennes) (Teleostei: Characiformes)

The objective of this study was to obtain information about the possible mechanisms related to poor reproductive performance in tropical rheophilic fish. To that effect, cages (Cs) and earthen ponds (EPs) were used as experimental systems to provide unsuitable and suitable conditions, respectively, for curimbata (Prochilodus lineatus) breeders. Fish were maintained under experimental conditions for 18 months, and during this period females were randomly sampled every two months for biometric analysis (n=30), blood (n=5/sampling) and ovary (n=5/sampling). After this period EPs females (EPFs) and Cs females (CFs) were submitted to the induced breeding experiments. The results showed that rearing curimbata for such long time in a cage at this stocking density, reduces its growth, plasma E2 levels and vitellogenesis. During vitellogenesis, the mean plasma estradiol levels of CFs were three times lower than those of EPFs (P<0.01). CFs presented poorer results than EPFs for all the examined parameters of reproductive performance. Taken together these data showed that the reduced estradiol levels during vitellogenesis (and the consequently less intense transition from the previtellogenic to vitellogenic phase) and reduced amounts of yolk are mechanisms associated with the formation of low quality oocytes and shortened and delayed breeding season in this species. Moreover, our data showed that the onset of vitellogenesis (six months before the spawning season) must be considered as a key period related to the formation of oocytes of good quality, and adequate management should be provided throughout the year.

Influencia de las variaciones estacionales del nivel de agua sobre la reproducción y el crecimiento de Potamorhina altamazonica (COPE, 1879) en el Río Ucayali, Perú

Se estudió la influencia de las variaciones estacionales del nivel de agua sobre la reproducción y el crecimiento de Potamorhina altamazonica en el río Ucayali durante los años 2008-2012. Se observó que, la reproducción es de carácter estacional, que, tiene sincronía con el periodo de creciente (enero-marzo) alcanzado el ápice en febrero. Se estimó que las hembras alcanzan la talla media de primera madurez a los 17,8 cm y los machos a los 18,4 cm (Lt), en ambos casos a la edad teórica de un año. La mayor proporción de hembras respecto a los machos se observó en el periodo de transición a creciente, y viceversa en la creciente; mientras que el análisis anual mostró dominancia de hembras en los años 2008 y 2012. El análisis de la estructura de tallas mostró que el stock explotado estuvo compuesto por peces cuyas tallas oscilaron de 12,0 a 31,0 cm Lt y no se observaron fuertes fluctuaciones de la talla media anual. La ecuación de crecimiento de von Bertalanffy definida por Lt = 33,55*(1-e(-0,65(t-0,26)) permite estimar que la especie es de rápido crecimiento y que podría vivir en teoría 3,5 años. Los peces mostraron mejor condición o robustez en los periodos de transición a creciente y creciente, dado a que en estos, se inundan vastas áreas de bosques de llanura convirtiéndose en hábitats óptimos que favorecen la reproducción en los peces adultos y el crecimiento en los reclutas.

Sex steroid feedback regulation of pituitary gonadotropins during early secondary oocyte growth in coho salmon (Oncorhynchus kisutch) – a potential target of endocrine disruption.

Thesis (Ph.D.)--University of Washington, 2016-06

X-Linked Retinitis Pigmentosa 2 Is a Novel Maternal-Effect Gene Required for Left-Right Asymmetry in Zebrafish

Retinitis pigmentosa 2 (RP2) gene is responsible for up to 20% of X-linked retinitis pigmentosa, a severe heterogeneous genetic disorder resulting in progressive retinal degeneration in humans. In vertebrates, several bodies of evidence have clearly established the role of Rp2 protein in cilia genesis and/or function. Unexpectedly, some observations in zebrafish have suggested the oocyte-predominant expression of the rp2 gene, a typical feature of maternal-effect genes. In the present study, we investigate the maternal inheritance of rp2 gene products in zebrafish eggs in order to address whether rp2 could be a novel maternal-effect gene required for normal development. Although both rp2 mRNA and corresponding protein are expressed during oogenesis, rp2 mRNA is maternally inherited, in contrast to Rp2 protein. A knockdown of the protein transcribed from both rp2 maternal and zygotic mRNA results in delayed epiboly and severe developmental defects, including eye malformations, that were not observed when only the protein from zygotic origin was knocked down. Moreover, the knockdown of maternal and zygotic Rp2 revealed a high incidence of left-right asymmetry establishment defects compared to only zygotic knockdown. Here we show that rp2 is a novel maternal-effect gene exclusively expressed in oocytes within the zebrafish ovary and demonstrate that maternal rp2 mRNA is essential for successful embryonic development and thus contributes to egg developmental competence. Our observations also reveal that Rp2 protein translated from maternal mRNA is important to allow normal heart loop formation, thus providing evidence of a direct maternal contribution to left-right asymmetry establishment.