Vanzela A L, Cuadrado A, Jouve N, Luceño M, Guerra M
Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, SP, Brazil.
Chromosome Res. 1998 Aug;6(5):345-9. doi: 10.1023/a:1009279912631.
Several cytogenetic studies have shown that representatives of the family Cyperaceae have holocentric chromosomes. Despite their interesting chromosome morphology, the chromosome organization has not been studied. This paper reports on the number and distribution of 18S-5.8S-26S ribosomal RNA sites by fluorescence in situ hybridization in eight Brazilian species of Rhynchospora. The signal of the rDNA probe was always localized in the telomeric regions. A high degree of variation was observed in the number of labelled sites, ranging from 4-8 in karyotypes with 2n = 10 to 30 sites in a karyotype with 50 chromosomes. It is possible that the same mechanism involved in the multiplication of these regions in organisms with monocentric chromosomes also plays a role in the polymorphism observed in holocentric chromosomes of Rhynchospora. An interesting feature of most hybridization sites was their diffuse state observed through to early metaphase. The decondensed state probably reflects the later transcription of this region during the cell cycle.
多项细胞遗传学研究表明，莎草科植物具有全着丝粒染色体。尽管其染色体形态有趣，但染色体组织尚未得到研究。本文报道了通过荧光原位杂交技术对巴西8种刺子莞属植物中18S - 5.8S - 26S核糖体RNA位点的数量和分布情况。核糖体DNA探针的信号总是定位在端粒区域。观察到标记位点的数量存在高度变异，在2n = 10的核型中为4 - 8个，在具有50条染色体的核型中为30个位点。在具有单着丝粒染色体的生物体中，参与这些区域倍增的相同机制可能也在刺子莞属全着丝粒染色体中观察到的多态性中发挥作用。大多数杂交位点的一个有趣特征是，直到早中期都观察到它们处于弥散状态。这种解聚状态可能反映了该区域在细胞周期后期的转录情况。
