Elizabeth Romagosa

Pattern of oocyte diameter frequency distribution in females of the pacu, Piaractus mesopotamicus (Holmberg 1887) (=Colossoma mitrei Berg 1895), induced to spawn

Abstract Pacu, Piaractus mesopotamicus, in captivity were selected for induced spawning with two doses of 10 and 20 IU/g of HCG (human chorionic gonadotropin) or 2 and 20 mg/kg of SPE (salmon pituitary extract) at 10-h intervals. Females were chosen for induction of spawning based on initial oocyte diameter. Three distinct groups of females were identified according to their initial response to the treatment: Group I, females that reproduced with a high rate of fertilization; Group II, females that reproduced with a low rate of fertilization; and Group III, females that did not reproduce. Oocytes that were successfully fertilized were initially green and homogeneous in size; the mode oocyte diameter was 939.0 μm, but increased to 1001.6 μm before ovulation.

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 1,187.5µm, 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.

Cell junctions in the germinal epithelium may play an important role in spermatogenesis of the catfish P. fasciatum (Pisces, Siluriformes).

We identified adhesive junctions and gap junctions between Sertoli cells, between Sertoli and germ cells and between germ cells in the testis of P. fasciatum, a catfish of commercial relevance. To investigate the role of these junctions in spermatogenesis, as well as the molecular composition of the junctions, we performed an immunohistochemistry light microscopy as well as an immunogold labelling electron microscopy study with antibodies to adhesive and gap junctions proteins. Testes that were at different stages of spermatogenesis were used. Based on our morphological studies we speculate that Sertoli–germ and germ–germ cell adhesive junctions are important for maintaining the three-dimensional structure of the germinal cysts and an organized arrangement of the germ cells inside the cysts. Connexin 32 was identified in the germ cells and in the cysts walls. Our observations also suggest that Sertoli–germ and germ–germ cells gap junctions may be involved in the mechanism of synchronous development of germ cells.

Gamete quality of streaked prochilod Prochilodus lineatus (Characiformes) after GnRHa and dopamine antagonist treatment

The efficiency of Ovaprim™ salmon gonadotropin-releasing hormone agonist (GnRHa) and dopamine antagonist on the induction of spawning and spermiation in Prochilodus lineatus in comparison with the commonly used method using pituitary extract (PE) was evaluated. Females received PE at 0.5 + 5.0 mg/kg and Ovaprim™ at 0.05 + 0.45 ml/kg or at 0.125 + 0.375 ml/kg. All males received a first dose of PE at 0.4 mg/kg and then PE at 4.0 mg/kg or Ovaprim™ at 0.25 ml/kg. Oocyte, egg, larvae and sperm quality were evaluated. All females spawned and oocyte, egg and larvae quality were similar between Ovaprim™-treated (both doses) and PE-treated females. Data from females were pooled and the mean values were: 242 g ova weight, 15% ova index, 1209 oocytes/g ova, 284,539 oocytes/female, 183 oocytes/g body weight, 1.18 mm oocyte diameter, 49% fertilization rate, 43% hatching rate and 89% normal larvae. Sperm quality was similar between Ovaprim™-treated and PE-treated males. Data from males were pooled and the mean values of semen were: volume of 3.0 ml, 14.9 × 109 sperm/ml, osmolality of 283 mOsm/kg, pH of 7.4, 71% motile sperm, 217 μm/s curvilinear velocity, 102 μm/s straight-line velocity and 189 μm/s average path velocity. Ovaprim™ treatment can be used for commercial reproduction of P. lineatus, without any loss of gamete quality in comparison with PE treatment.

Custos e rentabilidade da produção de juvenis de tilápia-do-nilo em tanques-rede utilizando-se diferentes densidades de estocagem

It was performed in this work the economic analysis of juvenile Nile Tilapia farming using different stocking densities. The experiment was carried out in an aquaculture area, using random block designs with four stocking densities (100, 200, 300 and 400 fish m-3), evaluated with six replicates, in two rearing periods: from March to April, 2005 (52 days - initial weight 43.08 ± 2.98 and final weight of 262.14 ± 47.86 g) and from March to April 2006 (58 days - initial weight of 43.16 ± 5.34 g and final weight of 314.24 ± 73.30 g). The following economic variables were analyzed: ration cost plus unit cost of juvenile divided by biomass, in R

Catfish (jundia) body yield and chemical composition fed different protein and energy level in the diet, reared in net-tanks

kg-1; percentage of ration cost per kilogram of fish produced upon sales price; percentage of juvenile cost per kilogram of fish produced upon sales price and percentage of ration costs plus juvenile cost per kilogram of fish produced upon sales price. From the smallest (100) to the highest stocking density (400), there was a decrease in the daily weight gain and an increase in the apparent feed conversion index, but this reduction did not compromise survival rate. However, the biomass gain increased with fish crowding. The highest net incomes were obtained in stocking densities of 100 and 200 fish m-3. The prices used did not remunerate the operational costs (effective and total costs), at higher densities (300 and 400 fish m-3). The best results for the juvenile Nile Tilapia breeding were obtained using densities of up to 200 fish m-3.

Storage of Steindachneridion parahybae oocytes at different temperatures

Objetivou-se analisar o rendimento corporal e a composicao quimica de jundias, Rhamdia quelen, alimentados com racoes contendo diferentes niveis de proteina e energia e criados em sistema de tanques-rede. Utilizou-se a densidade inicial de 70 peixes/m3, em 18 tanques-rede (5,0 m3), durante 324 dias. O delineamento experimental foi inteiramente casualizado com dois fatores - niveis de proteina bruta (PB), 25, 30 ou 35%; e niveis de energia digestivel (ED): 3.250 e 3.500 kcal - e tres repeticoes. A dieta foi fornecida a vontade, mas mensurada diariamente. No inicio, um lote de peixes foi sacrificado para determinacao dos parâmetros corporais e quimicos. A cada 28 dias, dois peixes de cada unidade experimental foram abatidos para determinacao dos comprimentos total e padrao, do peso total e dos pesos de figado, gonadas, cabeca, tronco limpo e gordura visceral, respectivamente. Posteriormente, foram realizados calculos dos indices hepatossomatico e gonadossomatico, da porcentagem de cabeca e do rendimento de carcaca e do rendimento de tronco limpo. A partir do mes de junho de 2006, tambem foram registrados o rendimento de file e o sexo dos individuos. Para determinacao da composicao da carne do jundia, foram realizadas as analises quimicas de umidade, proteina bruta, lipidios e materia mineral. O fornecimento da racao com 30% de PB resultou em maior rendimento de tronco limpo. A composicao do musculo nao foi influenciada pelas dietas testadas. Os melhores resultados foram obtidos com a utilizacao de dietas contendo 30% de PB e 3.250 kcal de energia digestivel/kg.

Chilling curves for Piaractus mesopotamicus (Holmberg, 1887) embryos stored at -8 ◦ C

The objective of this study was to assess the influence of temperature and time on the storage of fresh Steindachneridion parahybae oocytes. Two experiments were carried out: (1) the fertilization rates of oocytes exposed to temperatures of 5, 15, 28 (room temperature) and 35°C were assessed 15min (control), 115, 235 and 355min after release; (2) the fertilization and hatching rates, as well as the percentage of normal larvae of oocytes exposed to 14, 17 or 20°C, 20min (control) were assessed 50, 80 and 110min after stripping. In the first experiment, the highest fertilization rates (P<0.05) were obtained in the control treatment (15min, 28°C), with 74.34±5.48% oocytes showing loss of viability over time. In the second experiment, there was a reduction (P<0.05) in the fertilization rates at the temperatures and times tested. The artificial fertilization of S. parahybae oocytes is recommended immediately after collection, and if storage is necessary, it should be conducted at temperatures between 17 and 20°C.

Tempo de migração dos macrófagos em matrinxã, Brycon amazonicus, por meio da técnica de inoculação de leveduras Saccharomyces cerevisiae

The present study investigates the effect of different slow chilling curves on the storage of pacu (Piaractus mesopotamicus) embryos submitted to chilling at -8°C. Embryos at the blastopore closure stage were divided into two groups: G1 - embryos exposed to cryoprotectant solution containing methanol (10%) and sucrose (0.5 M), treated as follows: (T1) taken directly from room temperature to the refrigerator without being submitted to the curve; (T2) chilling curve of 0.5°C/min; and (T3) chilling curve of 1°C/min; and G2 - the cryoprotectant solution alone was submitted to these same temperatures, receiving the embryos only after temperature had decreased, corresponding to treatments T4, T5 and T6, respectively. Treatments were kept at -8°C for a period of 6 h. Embryo development was evaluated for each treatment, with six replicates in an entirely randomized design. Survival among embryos not submitted to refrigeration was 94.3 ± 8.05%. Percentage of total larvae (TL) and addled eggs (AE) did not differ statistically between the groups, although percentage of swimming larvae (SL) exhibited higher values in G1 for the 1°C/min curve. Furthermore, when comparing the three chilling curves, a decrease of 1°C/min resulted in the highest TL percentage (90.85%), followed by the 0.5°C/min curve (78.52%). Thus, the use of 1°C/min chilling curves is recommended for P. mesopotamicus embryos stored for 6 h at -8°C.

Processo de maturação das gônadas de pintado (Pseudoplatystoma corruscans) alimentado com dois níveis proteicos e suplementados com óleo de milho

In aquaculture, analysis of activation and increased macrophages migration are used in order to verify the ability of the nonspecific immune fish exposed to a challenge. This study aimed to determine the time of macrophages migration in matrinxa, Brycon amazonicus, through the technique of yeast Saccharomyces cerevisiae inoculation, verifying possible changes in hematological parameters. Thirty animals with average weight of 101.55 ± 24.50 g and average length of 19.75 ± 1.72 cm were employed. The experimental inoculation periods were 2, 4, 8 and 12 hours. Thereafter, animals were anesthetized and blood was withdrawn through a caudal puncture for the determination of total erythrocytes number, differential and total leukocyte counts and total thrombocytes count, hematocrit, hemoglobin concentration and calculation of the erythrocytes index. The results for the phagocytic capacity were not significantly different between experimental periods. In the phagocytic index, the period of 2 hours presented the highest rate of phagocytized cells, indicating that 2 hours of incubation was sufficient for the macrophages migration in B. amazonicus. The number of erythrocyte was the only parameter that presented significant difference among periods.