利用數種重複性DNA序列的分佈建立朵麗蘭的核型

Abstract

朵麗蘭具有19對中位中節或次中位中節的染色體，其無法經由傳統的細胞遺傳學技術來辨識。本實驗從朵麗蘭基因組庫中選殖到數種重複性DNA序列，包括一種由7 bp為重複單位組成的頭尾相接重複性序列，兩種富含(GA)n微衛星序列。利用螢光原位雜交的技術將這些重複性序列、兩種核糖體RNA基因以及阿拉伯芥型的端粒序列定位到朵麗蘭有絲分裂中期的染色體上，依據這些序列在染色體上的分佈位置以及雜交訊號的差異，建立朵麗蘭核型。

Doritis pulcherrima has 19 pairs of metacentric or submetacentric chromosomes which could not be distinguished from each other by conventional cytological techniques. Several repetitive DNA sequences including one tandem repeat consisting of 7-bp repeat units, two (GA)n microsatellite sequences were isolated from genomic DNA library of Doritis pulcherrima. These repetitive DNA sequences together with two ribosomal RNA genes and Arabidopsis-type telomeric sequences were mapped to mitotic metaphase chromosomes using fluorescence in situ hybridization. Based on the variation in the spatial and quantitative distribution of these repetitive sequences, the karyotype of Doritis pulcherrima was established.