Fernandes Carlos Alexandre, Martins-Santos Isabel Cristina
Department of Cell Biology and Genetics, State University of Maringá, Avenida Colombo 5790, 87020-900 Maringá, PR, Brazil.
Genetica. 2005 Jul;124(2-3):301-6. doi: 10.1007/s10709-005-4751-7.
Chromosomes of Astyanax scabripinnis from the Tatupeba stream, Ivaí Basin (state of Paraná, Brazil), were analyzed. Astyanax scabripinnis population presents 3 different diploid numbers (2n = 46, 48 and 50) and B chromosomes in each cytotype. Eighty per cent of the females among individuals of cytotype I (2n = 50) has a metacentric B macrochromosome, whereas three different types of B chromosomes were identified in individuals of cytotype II (2n = 48). Cytotype III (2n = 46) showed two B chromosomes of different morphologic types (metacentric macrochromosomes and acrocentric) in all specimens and cells analyzed. Constitutive heterochromatin pattern for the three cytotypes showed weak markings in centromeric regions and conspicuous blocks in the telomere regions of ST and A chromosomes. Whereas C-banding showed that B chromosomes were totally or partially heterochromatic, a discussion on their behavior and origin was also undertaken.
对来自巴西巴拉那州伊瓦伊河流域塔图佩巴溪的糙鳍丽脂鲤的染色体进行了分析。糙鳍丽脂鲤种群呈现出3种不同的二倍体数目（2n = 46、48和50），并且在每种细胞型中都存在B染色体。细胞型I（2n = 50）的个体中80%的雌性具有一条中着丝粒B大染色体，而在细胞型II（2n = 48）的个体中鉴定出了3种不同类型的B染色体。细胞型III（2n = 46）在所有分析的标本和细胞中都显示出两条形态不同的B染色体（中着丝粒大染色体和近端着丝粒染色体）。三种细胞型的组成型异染色质模式在着丝粒区域显示出较弱的标记，而在ST和A染色体的端粒区域有明显的块状。虽然C带显示B染色体完全或部分是异染色质的，但也对它们的行为和起源进行了讨论。
