Aplicações de marcadores moleculares nas principais espécies da aquicultura do Nordeste Brasileiro

Abstract

The main species in evidence in Brazilian aquaculture, mainly in the state of Ceara, are Oreochromis niloticus (Nile tilapia) and Litopenaeus vannamei (white shrimp Pacific). The development of microsatellite markers has provided a major advance in genetic monitoring of these animals. So, four microsatellite markers were applied in genetic characterization of five flocks of Nile tilapia from five municipalities in the state of Ceara, with a mean expected heterozygosity reduction framework (He=0.733) compared to average observed heterozygosity (Ho = 0.575) and the rate of inbreeding (FIS) with a moderate significant genetic differentiation (FST = 0.059) in all flocks. The marker UNH231 was the only one with a consistent pattern of Hardy-Weinberg disequilibrium in most flocks. These factors led to a structuring into three groups, Group 1: Fortaleza and Itaitinga and Group 2: Amanari, Horizonte and Russas, confirming the history of flocks. The use of the site UNH104 as male indicator for Nile tilapia presented the allele 132 mostly total alleles, particularly in a state of homozygosity (132/132). However, there was no significant difference (P=0.675) in sexual identification in other genotypes. Fifteen microsatellite markers were tested on families of Litopenaeus vannamei for the construction of a panel of markers in the multiplex system. Among these nine locus multiplex amplifications exhibited consistent and no dimer formation. In the process of evaluation of markers, most of the alleles identified in the multiplex PCR system showed Mendelian segregation. However, for migration analysis of allelic loci in general, all markers were used distortions in the distribution of genotypes in relation to the expected Mendelian ratio. This shows the need for comprehensive understanding of the loci molecular evolution model used in genetic variability description of populations and L. vannamei.