Giovano Neumann

Storage of Steindachneridion parahybae oocytes at different temperatures

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.

Optimization of the sperm:oocyte ratio and sperm economy in the artificial reproduction of Rhamdia quelen using fructose as a sperm motility modulator

This research was conducted to evaluate the effects of fructose as a modulator of sperm motility and its effects on the reduction in number of sperm cells in IVF using cryopreserved Rhamdia quelen semen. Sperm activation occurred in solutions containing fructose (0.0, 0.9, 1.8, 2.7, 3.6 and 4.5%). The sperm motility rate, velocity and duration of sperm motility were assessed by polynomial regression analysis and grouped by the principal component analysis (PCA). Then, the oocytes were mixed with semen at proportions of 1×10(4), 3×10(4), 5×10(4), 7×10(4) and 9×10(4) for the sperm:oocyte ratio and fertilization was induced by the activation of gametes with the fructose-containing solutions. The fertilization, hatching and larval normality rate were evaluated by response surface protocol and were further grouped by PCA. All sperm variables were affected by the activating solutions, and the most desirable theoretical results for the rate of sperm motility were obtained when using a solution containing 2.85% fructose. In the IVF and incubation assays, there was an interactive effect between the motile sperm:oocyte ratio and the fructose concentration on the rates of oocyte fertilization, hatching and on the clustered index for reproductive success. The results suggest the possibility of reducing the sperm cells on IVF by 17.77% when using a solution containing 2.28% fructose. In conclusion, the use of solutions containing fructose at concentrations that maximize sperm movement allow the reduction of the motile sperm:oocyte ratio, thus promoting sperm metabolic efficiencies and contributing to the feasibility of using cryopreserved semen at a large-scale in IVF.

Exposure of male tilapia (Oreochromis niloticus) to copper by intraperitoneal injection: DNA damage and larval impairment

The present work aimed to assess the genotoxic effects of intraperitoneally injected copper in males of O. niloticus, and to investigate its association with eventual changes in the quality of the gametes and in the generation of offspring abnormalities. Thus, to evaluate DNA damage, the alkaline comet assay was performed in sperm and blood; sperm parameters were analyzed to determine the quality of the gametes, and the incidence of morphological abnormalities of larvae, originated from eggs fertilized by males exposed to copper, was used as a measure of reproductive impairment. Male fish were exposed to three doses (1 mg/kg, 2 mg/kg, 4 mg/kg) of copper sulfate via intraperitoneal injection and observed after 96 h of exposure. We found that the quality of gametes was not affected by copper, as indicated by the lack of differences in sperm parameters between the exposed and the control groups. Nonetheless, copper induced an increase in sperm DNA damage at all tested doses. Taking into consideration the total number of abnormalities, larvae presented a higher proportion of morphological abnormalities at all the tested doses. Considering the morphological abnormalities separately, the 2 mg/kg and 4 mg/kg groups presented significantly higher frequencies of arrested development and spinal abnormalities than the control group. This work suggests that intraperitoneally injected copper is an inductor of DNA breakage in germ cells of O. niloticus males. Copper induces the formation of larval morphological abnormalities, causing reproductive impairment to this species. The fact that copper did not induce alterations on sperm parameters indicates that the parental genotoxic effects are inheritable to the offspring.