Esterase-D and chromosome patterns in Central Amazon piranha (Serrasalmus rhombeus Linnaeus, 1766) from Lake Catalão

• Autor(a) principal: Teixeira, Aylton Saturnino
• Data de Publicação: 2006
• Outros Autores: Nakayama, Celeste Mutuko, Porto, Jorge Ivan Rebelo, Feldberg, Eliana
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional do INPA
• Texto Completo: https://repositorio.inpa.gov.br/handle/1/14965
• topic: Carboxylesterase; Brasil; Chi Square Test; Cytotype; Dna Polymorphism; Electrophoresis; Enzyme Assay; Fish; Fish Genetics; Gene Frequency; Gene Locus; Gene Segregation; Polymorphism, Genetic; Genotype; Geographic Distribution; Karyotype; Nonhuman; Null Allele; Silent Gene; Taxonomic Identification; Serrasalmus Rhombeus

This study presents additional genetic data on piranha (Serrasalmus rhombeus Linnaeus, 1766) complex previously diagnosed due to the presence of distinct cytotypes 2n = 58 and 2n = 60. Three esterase-D enzyme loci (Est-D1, Est-D2 and Est-D3) were examined and complemented with chromosomal data from 66 piranha specimens collected from Lake Catalão. For all specimens the Est-D1 and Est-D2 loci were monomorphic. In contrast, the Est-D3 locus was polymorphic with genotypes and alleles being differentially distributed in the previously described cytotypes and served as the basis for detecting a new cytotype (2n = 60 B). In cytotype 2n = 58 the Est-D3 locus was also polymorphic and presented Mendelian allelic segregation with four genotypes (Est-D311, Est-D312, Est-D322 and Est-D333) out of six theoretically possible genotypes, presumably encoded by alleles Est-D31 (frequency = 0.237), EsT-D32 (0.710) and Est-D33 (0.053). A Chi-squared (χ2) test for Hardy-Weinberg equilibrium was applied to the Est-D3locus and revealed a genetic unbalance in cytotype 2n = 58, indicating the probable existence in the surveyed area of different stocks for that karyotypic structure. A silent null allele (Est-D30 with a high frequency (0.959) occurred exclusively in the 2n = 60 cytotype. On the other hand, the new cytotype 2n = 60 B described here for the first time was monomorphic for the presumably fixed Est-D33 allele. The data as a whole should contribute to the better understanding the rhombeus complex taxonomic status definitíon in the Central Amazon. © 2006 Sociedade Brasileira de Genética.