Brinkman J N, Sessions S K, Houben A, Green D M
Redpath Museum, McGill University, Montreal, Quebec, Canada.
Chromosome Res. 2000;8(6):477-85. doi: 10.1023/a:1009215621509.
We examined the genetic make-up and plausible origins of the supernumerary (B) chromosomes of the Pacific giant salamander, Dicamptodon tenebrosus, from the Pacific Northwest of North America. These salamanders have variable numbers of B chromosomes, from 0 to 10 per individual. Salamanders from the most southerly and northerly regions of the species' range have lower average numbers of B chromosomes than salamanders in the middle of the range. To assess how the supernumerary chromosomes originated in D. tenebrosus, B chromosome DNA was isolated by microdissection and amplified by degenerate oligonucleotide-primed PCR. The B chromosome DNA hybridized similarly to genomic DNA from individuals of D. tenebrosus and the related species D. copei and D. ensatus, thus demonstrating that the supernumerary chromosomes were derived from the normal chromosome complement. Unique hybridization bands in both D. copei and D. tenebrosus suggest that the shared sequences have evolved independently.
我们研究了北美太平洋西北部的太平洋巨型蝾螈（Dicamptodon tenebrosus）额外（B）染色体的基因组成和可能的起源。这些蝾螈的B染色体数量各不相同，每个个体从0到10条不等。该物种分布最南端和最北端地区的蝾螈，其B染色体的平均数量低于分布范围中部的蝾螈。为了评估D. tenebrosus中额外染色体的起源方式，通过显微切割分离出B染色体DNA，并通过简并寡核苷酸引物PCR进行扩增。B染色体DNA与D. tenebrosus个体以及相关物种D. copei和D. ensatus的基因组DNA杂交情况相似，从而证明额外染色体源自正常染色体组。D. copei和D. tenebrosus中独特的杂交带表明，共享序列是独立进化的。
