Biomaterial Database

Morphological differentiation and possible origin of B chromosomes in natural Brazilian population of Astyanax scabripinnis (Pisces, Characidae). 2000

D M Néo, and L A Bertollo, and O M Filho

Departamento de Genética e Evolução, Universidade Federal de São Carlos, SP, Brazil.

Specimens of Astyanax scabripinnis from three different altitudes (1920, 1800 and 700 m) along the Ribeirão Grande stream in the Campos do Jordão region (São Paulo State, Brazil) were investigated. The same diploid number, 2n = 50, was detected in the three populations, with the following karyotypic constitution: 6M, 22SM, 10ST and 12A. The populations located at 1920 and 1800 m altitude presented a high incidence of B chromosomes varying in number (0-2), shape (meta- and submetacentrics), size (large and small) and sex-related frequency (they were more frequent among females). The two morphologically variant B chromosomes probably evolved from a metacentric macrochromosome, which is the most commonly observed B chromosome in several A. scabripinnis populations.

UI	MeSH Term	Description	Entries
D007621	Karyotyping	Mapping of the KARYOTYPE of a cell.	Karyotype Analysis Methods,Analysis Method, Karyotype,Analysis Methods, Karyotype,Karyotype Analysis Method,Karyotypings,Method, Karyotype Analysis,Methods, Karyotype Analysis
D008297	Male		Males
D001938	Brazil	A country located on the eastern coast of South America, located between Colombia and Peru, that borders the Atlantic Ocean. It is bordered on the north by Venezuela, Guyana, Suriname, and French Guiana, on the south by Uruguay, and on the west by Argentina. The capital is Brasilia.
D002875	Chromosomes	In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)	Chromosome
D004171	Diploidy	The chromosomal constitution of cells, in which each type of CHROMOSOME is represented twice. Symbol: 2N or 2X.	Diploid,Diploid Cell,Cell, Diploid,Cells, Diploid,Diploid Cells,Diploidies,Diploids
D005075	Biological Evolution	The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.	Evolution, Biological
D005260	Female		Females
D005399	Fishes	A group of cold-blooded, aquatic vertebrates having gills, fins, a cartilaginous or bony endoskeleton, and elongated bodies covered with scales.
D005828	Genetics, Population	The discipline studying genetic composition of populations and effects of factors such as GENETIC SELECTION, population size, MUTATION, migration, and GENETIC DRIFT on the frequencies of various GENOTYPES and PHENOTYPES using a variety of GENETIC TECHNIQUES.	Population Genetics
D000531	Altitude	A vertical distance measured from a known level on the surface of a planet or other celestial body.	Altitudes