ABSTRACT
Utilizaram-se marcadore microssatélites para estimar a diversidade genética de grupos de pacu (Piaractus mesopotamicus) coletados nas escadas de transposição das hidroelétricas de Canoas I (CI) e Canoas II (CII), no Rio Paranapanema, e de um estoque e uma progênie utilizados em programas de repovoamento nesse rio. Os loci microssatélites produziram 16 alelos e heterozigosidade observada média similar entre os indivíduos do rio nos dois tempos de coleta (CI14 = 0,7356; CI28 = 0,7361; CII14 = 0,7442; e CII28 = 0,7507), do estoque e da progênie (0,7261 e 0,7287, respectivamente). Foram observados desvios no equilíbrio de Hardy-Weinberg, e valores negativos do índice de fixação com excesso de heterozigotos que indicaram ausência de endogamia. As análises de diversidade genética (distância e identidade genética, índice de Shannon, F ST e AMOVA) foram indicativas de baixa diferenciação genética e conduziram ao agrupamento dos indivíduos do rio, sugerindo que essa espécie está geneticamente estruturada como uma única população. Foram verificados baixa diferenciação genética e altos valores do número de migrantes entre os indivíduos do rio, do estoque e da progênie, o que presume a origem comum derivada dos constantes repovoamentos realizados nesse rio a partir dessas populações estocadas.
This study used microsatellites markers to determine the genetic diversity of pacu (Piaractus mesopotamicus) groups collected at passage ladders of the hydroelectric plants (HEP) Canoas I (CI) and Canoas II (CII) - Paranapanema River - and of a broodstock and a progeny in stock enhancement programs in that river. The microsatellite loci produced 16 alleles and a similar heterozygosity between the individuals of the river at both times of collection (CI14 = 0.7356, CI28 = 0.7361, CII14 = 0.7442, and CII28 = 0.7507), as well of the broodstock and the progeny (0.7261 and 0.7287, respectively). Deviations were observed in Hardy-Weinberg equilibrium and negative values of fixation index with excess of heterozygosity indicated endogamy absence. The genetic diversity analyses (distance and genetic identity, Shannon index, F ST, and AMOVA) were signs of low genetic differentiation, and they led to the clustering of river individuals, suggesting that the species is genetically structured as a single population. Low genetic differentiation and high values of numbers of migrates among the river, the stock, and the progeny individuals were verified, suggesting a common origin derived from the constant stocks enhancement programs accomplished in that river with those stock populations.
Subject(s)
Animals , Genetics, Population/methods , Microsatellite Repeats , Fishes/genetics , BiomarkersABSTRACT
Avaliou-se o efeito do sistema seminatural na diversidade genética de um estoque de Brycon orbignyanus, utilizado em programas de repovoamento, com o marcador molecular RAPD. Vinte e quatro reprodutores, 12 machos e 12 fêmeas e 95 larvas da progênie foram analisados. Os nove primers utilizados produziram 90 fragmentos, dos quais 94,4 por cento foram polimórficos. Houve diferença significativa na frequência de 20 dos 90 fragmentos entre os reprodutores e sua progênie sem a presença de fragmentos exclusivos. O índice de diversidade genética de Shannon, a porcentagem de fragmentos polimórficos e a diversidade genética de Nei foram mais altos nos indivíduos da progênie. A similaridade genética foi maior nos indivíduos do estoque de reprodutores. A análise de variância molecular mostrou que a maior parte da variação está dentro de cada grupo (89,1 por cento) e não entre os grupos (10,9 por cento). A identidade e a distância genética entre os estoques foram de 0,944 e 0,057, respectivamente. Assim, a utilização do sistema seminatural evitou a mortalidade de reprodutores B. orbignyanus e conservou a variabilidade genética da progênie.
The effect of the semi-natural system on the genetic diversity of a Brycon orbignyanus stock, used in stock enhancement programs, was evaluated with the RAPD molecular marker. Twenty-four broodstocks - 12 males and 12 females - and 95 larvae of the offspring were analyzed. The nine used primers produced 90 fragments, of which 94.4 percent were polymorphic. There was significant difference in the frequency of 20 out of the 90 fragments between the broodstocks and their offspring without the presence of exclusive fragments. The Shannon genetic diversity index, the percentage of polymorphic fragments and the Nei gene diversity were higher in the offspring individuals. Genetic similarity was higher in broodstock individuals. The analysis of molecular variance results showed that the major part of the genetic variation is within the groups (89.1 percent) and not between them (10.9 percent). The identity and genetic distance between the groups were 0.944 and 0.057, respectively. Like this, the use of the semi-natural system avoided the mortality of B. orbignyanus broodstocks and conserved the genetic variability of the offspring.
Subject(s)
Animals , Genetic Variation , Fishes/genetics , Genetic Enhancement/methods , Random Amplified Polymorphic DNA Technique/methodsABSTRACT
The heterokaryotic and vegetative diploid phases of Colletotrichum lindemuthianum are described using nutritional and biochemical markers. Nitrate non-utilizing mutants (nit), derived from R2047, R89, R73, R65, and R23 isolates, were paired in all possible combinations to obtain heterokaryons. Although pairings R2047/R89, R2047/R73, R65/R73, and R73/R23 showed complete vegetative incompatibility, prototrophic heterokaryons were obtained from pairings R2047/R65, R2047/R23, R65/R89, R65/R23, R73/R89, R89/R23, R2047/R2047, R65/R65, R89/R89, R73/R73, and R23/R23. Heterokaryons gave rise to spontaneous mitotic segregants which carried markers corresponding to one or the other of the parental strains. Heterokaryons spontaneously produced prototrophic fast-growing sectors too, characterized as diploid segregants. Diploids would be expected to yield auxotrophic segregants following haploidization in basal medium or in the presence of benomyl. Parental haploid segregants were in fact recovered from diploid colonies growing in basal medium and basal medium containing the haploidizing agent. Although barriers to the formation of heterokaryons in some crosses were detected, the results demonstrate the occurrence of parasexuality among vegetative compatible mutants of C. lindemuthianum.