Cabrero J, Lopez-Leon MD, Bakkali M, Camacho JP
Departamento de Genetica, Facultad de Ciencias, Universidad de Granada, E-18071 Granada, Spain.
Heredity (Edinb). 1999 Oct;83(# (Pt 4)):435-9. doi: 10.1038/sj.hdy.6885960.
Nine B chromosome variants, from seven different populations of Eyprepocnemis plorans collected at four localities in Spain and three in Morocco, have been shown to be mainly composed of two DNA sequences, i.e. a 180-bp tandem repeat and ribosomal DNA. B types, however, differ in the relative amounts of the two sequences. The most widespread one (B1) bears about the same amount of rDNA and 180 bp repeat, but three other variants that have reached a polymorphism by replacing B1 in smaller areas (B2, B5 and B24) carry a conspicuously larger amount of the 180 bp repeat. In Morocco, the most widespread B variant is also B1, and a rare variant that appeared in a single individual is also built with the same two DNA sequences. All these data point to a common origin for these B chromosomes, with B1 probably being the original one. The origin of the different B types and the possible relationship of the relative amount of 180 bp DNA repeat with B drive are discussed.
在西班牙四个地点和摩洛哥三个地点采集的来自七个不同群体的九种伊氏蝗（Eyprepocnemis plorans）B染色体变体，已被证明主要由两种DNA序列组成，即一个180bp的串联重复序列和核糖体DNA。然而，B型在这两种序列的相对含量上有所不同。分布最广的一种（B1）的核糖体DNA和180bp重复序列含量大致相同，但在较小区域取代B1而达到多态性的其他三种变体（B2、B5和B24）携带的180bp重复序列含量明显更多。在摩洛哥，分布最广的B变体也是B1，并且在一个个体中出现的一种罕见变体也是由相同的两种DNA序列构成。所有这些数据都指向这些B染色体有一个共同的起源，B1可能是原始的。本文讨论了不同B型的起源以及180bp DNA重复序列的相对含量与B染色体驱动之间可能的关系。
