Estefânia de Souza Andrade

Vitamin E and reduced glutathione in Prochilodus lineatus (curimba) semen cryopreservation (Characiformes: Prochilodontidae)

This study investigated the addition of antioxidants vitamin E and reduced glutathione on curimba (Prochilodus lineatus) semen cryopreservation and compared sodium bicarbonate solution and distilled water as activators. The experiment was conducted at the environmental station of CEMIG, in Itutinga-MG, Brazil, between December/2009 and January/2010. Semen samples (n = 7) with semen motility above 80% were diluted in cryoprotectant solutions composed of 10% methanol, 15% lactose and containing different concentrations of antioxidants: 50 (VE50), 100 (VE100) and 250 (VE250) µM of vitamin E, and 0.5 (RG0.5), 1.0 (RG1.0) and 1.5 (RG1.5) mM of reduced glutathione. A solution without antioxidants was used as a control. The semen was diluted at a ratio of 1:4 (100 iL semen:400 ∝L cryoprotectant solution). The toxicity of the solutions was evaluated by investigating semen motility after 10 min in the solution. The rest of the diluted semen was placed into 0.5 mL straws maintained in nitrogen vapour for 24 hours and packed into a nitrogen liquid cylinder for four days. The samples were thawed in a water bath at 60°C for 8 s and the rate (%) and duration (s) of semen activation with distilled water or sodium bicarbonate was evaluated. In the toxicity test, we found that vitamin E and reduced glutathione were not toxic to curimba semen at any of the tested concentrations (P>0.05). The duration of motility was longer (P 0.05). Thus, the antioxidants vitamin E and reduced glutathione did not improve the quality of cryopreserved curimba semen, but they did not cause toxic effects to the semen in natura and they did not decrease its quality during cryopreservation.

Reproductive dynamics of Leporinus obtusidens captured downstream from an important hydropower Station in Brazil

This study evaluated the reproductive dynamics and gonadal morphology of piaparas (Leporinus obtusidens) captured downstream from the Funil Hydroelectric Power Station. The 107 piaparas evaluated were captured monthly from Sep 2006 to Aug 2007. The data were stratified among the seasons to evaluate gonad maturation and the reproductive period was determined by assessing the gonadosomatic index, hepatosomatic index, abdominal fat index (AFI), weight:length ratio, condition factor and sexual proportion. The reproductive period lasted from winter to summer (Jul-Mar) in females and from spring to autumn (Sept-Jun) in males. AFI was high during and after the reproductive period in females and only during the reproductive period in males. The highest HIS values for males and females were obtained in spring and summer (Sept-Mar). The females observed did not spawn and showed follicular atresia. These characteristics suggest that L. obtusidens does not use the study area as a reproductive site and probably migrates for this purpose.

Toxicity of cryoprotectants on Prochilodus lineatus (Valenciennes, 1837) (curimba) embryos in an experimental incubator (Characiformes: Prochilodontidae)

This paper investigated the effect of cryoprotectant substances on Prochilodus lineatus embryos in an experimental incubator. The prospective study applied combinations of polyvinyl alcohol, hydroxyethyl cellulose, gelatin and fetal bovine serum with dimethyl sulfoxide and ethylene glycol in a new experimental incubator. The morphology of embryos, larval viability and the efficiency of experimental incubators in maintaining the quality of embryos were evaluated. This study demonstrates the efficient association between hydroxyethylcellulose and dimethyl sulfoxide as greater viability (p<0.05) was found for embryos (72.9 ± 23.9%). It should also be noted the permeation of cryoprotectants in embryos through the changes found in chorion diameter, embryo diameter and embryo volume comparing the treatments versus control group (water) (p<0.05), this results can help in future cryopreservation protocols. Although the temperature and oxygenation differed between the usual and experimental incubators (p<0.05), the results showed a high fertilization rate (79.6 ± 13.2%) for experimental incubators (p<0.05) which is sufficient for the maintenance of embryos in a cryoprotective environment and effectively allows experimentation for long periods with cryoprotectant substances. Cryopreservation of fish embryos has not been accomplished yet and new approaches are required for understanding the permeability of teleost embryos, especially in Brazilian native species.

Swimbladder abnormalities in piapara (Leporinus obtusidens) captured downstream of the Funil Dam

Os danos que as usinas hidreletricas causam na fauna aquatica tem sido relatados, mas novos estudos focando as especies nativas, especialmente os peixes de grande porte sao necessarios. O presente estudo descreve as anomalias de bexiga natatoria em piapara Leporinus obtusidens, uma especie de peixe migratorio, coletados a jusante da barragem da estacao Hidreletrica do Funil, Minas Gerais, Brasil. Os 117 exemplares coletados foram dissecados para avaliacao da bexiga natatoria na cavidade celomatica. As anormalidades detectadas em 14 dos peixes capturados (12%) foram ruptura do tecido com exteriorizacao da bexiga natatoria (N = 12) e formacao de projecoes da bexiga (N = 2). Os exemplares que apresentavam anormalidades de bexiga, possuiam peso superior a 1300 g em ambos os sexos. Este tipo de anomalia pode ser causado por processo infeccioso da bexiga, no entanto, nao foram detectados processos inflamatorios nesses peixes. O quadro de anomalias em bexiga natatoria em piapara sugere que os individuos foram submetidos a uma brusca despressurizacao, possivelmente relacionada a passagem pelas turbinas. Outros estudos comparativos sao necessarios para corroborar esta hipotese.

Sulfated Polysaccharides in Diets for Nile tilapia (Oreochromis niloticus) in theInitial Growth Phase

This study had the objective of evaluating the performance of Nile tilapia, in initial growth phase, with the supplementation of fucoidan, extracted from brown algae, at 30 days of rearing. The experiment was conducted for a period of 30 days. We used 216 Nile tilapia fingerlings distributed in to twelve 60 liter tanks, in a completely randomized design, totalizing four treatments and tree replicates. The fingerlings were supplemented with powdered sulfated polysaccharide extract at the levels of 0%, 0.5%, 1.0% and 1.5%. During the experimental period, two samplings were performed (initial and final) to measure zootechnical performance, muscle histology and blood plasma chromatography. The data were submitted to analysis of variance at a level of significance of 5%. The performance variables muscle fiber diameter frequency and fucose plasmatic concentration were not significant among the treatments (P>0.05). It was possible to identify fucose in the blood plasma of the animals, proving its efficiency in breaking the α-(1-3) bonds of the polysaccharide, thus absorbing this component. The histological analysis showed that there was a higher percentage of hypertrophic growth of the muscle fibers, given that, in all treatments, the diameter class >50 μm prevailed (P<0.05). In conclusion, the sulfated polysaccharide fucoidan, used in diets for Oreochromis niloticus with 30 days of rearing, was not effective in increasing performance parameters and muscle growth.

Influence of Photoperiod over Morphometric and Hematological Parameters of Juvenile Piracanjubas (Brycon orbygnianus)

The aim of this study was to evaluate morphometric and hematological parameters of juveniles Piracanjubas treated with two distinct photoperiod. Twenty nine fish with 100 g, in a factorial design were performed in 18 h light:6 h dark (18L:6D) and 6L:18D two different photoperiod, and morphometric and hematological parameters were evaluated at 45 d and 90 d after photoperiod treatment. Benzocaine 1% was used for euthanasia. Fish were weighed and measured, so as visceral fat, liver and gonads. Hematocrit, total count of white cells, lymphocytes and neutrophils were counted. Results showed that there was no significant relationship between bodyweight and standard length. Significant interaction (P = 0.00018) had been found between the fat index (FI) and gonado-somatic index (GSI) and the photoperiod and time. At 90 d, the fish kept in 18L:6D had a lower rate of fat than the fish kept in 6L:18D (P < 0.05). The GSI was higher in the group 6L:18D compared with the 18L:6D (P < 0.005). There was no interaction between photoperiod and period of treatment for total leukocyte count, however with 90 d, the total leukocyte count was decreased (P < 0.05). Moreover, decrease of the hematocrit from 58.1% to 46.9% and an increase of lymphocytes from 31.5% to 43.5% had been found in fish kept in 18L:6D after 90 d (P < 0.05). Fish kept in 6L:18D presented an increase in segmented neutrophils and lymphocytes (P < 0.05). It is concluded that photoperiod maintained at 6L:18D for Piracanjubas permits a greater gonadal development and an amount of immune cells over the photoperiod maintained in 18L: 6D.