Danilo Pedro Streit Júnior

Diversidade genética de pacu do Rio Paranapanema e do estoque de um programa de repovoamento

The objective of this work was to study the genetic diversity of pacu samples from the middle Paranapanema River and from the broodstock used in the stock enhancement program of the Aquaculture and Hydrology Station at the Duke Energy Power Plant, by RAPD marker. Fourteen primers were used to analyze 30 individuals captured in the middle Paranapanema River and 29 individuals from the broodstock. The Shannon genetic diversity index and percentage of polymorphic fragments were higher in individuals captured in the Paranapanema River. Genetic similarity was larger in individuals of the broodstock. Results of analysis of molecular variance showed that the major part of the genetic variation is within the groups (84.2%) and not between them (15.8%). The identity and genetic distance among the groups were 0.9517 and 0.0549, respectively. Moderate genetic differentiation (FST = 0.15) and high number of migrants per generation (Nm = 5.33) were observed between the two groups. The genetic diversity was lower in the broodstock than in fish captured in the middle Paranapanema River.

Embriões de pacu submetidos a diferentes protocolos de resfriamento

The objective of this work was to evaluate the percentage of hatching after cooling of pacu (Piaractus mesopotamicus) embryos at -8oC for six hours, treated with cryoprotectant solutions, to obtain a cooling protocol for the specie. There were 2.400 embryos in post-gastrula stage development, in seven cryoprotectants solutions and control with three replicates, in completely randomized design. Ethylene glycol and honey-jelly were inappropriate. The substitution of 50% sucrose did not produce positive results. The combination of methanol (9%) and sucrose (17.5%) performed 69.2% of hatching and is recommended for cooling of pacu embryos at -8 oC for six hours.

Viability of dourado embryos cooled in different cryoprotectant solutions

The objective of this work was to evaluate the effect of different cryoprotectants on the viability of dourado (Salminus brasiliensis) embryos. Ten cryoprotectant solutions were tested. For each solution, 300 embryos were selected at the closing of the blastopore stage, and 300 more embryos were used as a negative control. After cooling (-8oC for 6 hours), the embryos were rehydrated directly in the incubator until hatching. The best result is obtained with the cryoprotectant solution containing 9% methanol associated with 17% sucrose, resulting in a larvae hatching rate of 67.06%.

Diversidade genética de dourado utilizado em programas de repovoamento no rio Paranapanema

The objective of this work was to estimate by RAPD markers the genetic diversity of a Salminus brasiliensis lot used in stock enhancement programs in the Paranapanema River, Parana, Brazil. Ten broodstocks (five males and five females) and their progeny (40 larvae and 40 fingerlings) were analyzed. Eight analyzed primers produced 96 fragments, of which 81.2% were polymorphic. There was significant difference in the frequency of 32 out of the 96 fragments, with the presence of an exclusive fragment in the fingerlings. The Shannon index, the percentage of polymorphic fragments, and the genetic distance and identity showed less genetic divergence between broodstocks and larvae, besides a decrease of genetic variability in the fingerlings. Genetic divergence was lower in the fingerlings in comparison to the larvae and broodstocks. The molecular variance results showed that most of the genetic variation is within (90.05%) and not between groups (9.95%). The broodstock lot has high genetic variability, and genetic differences were observed between the larval and fingerling stages.