Kishima Y, Yamashita S, Martin C, Mikami T
Laboratory of Genetic Engineering, Faculty of Agriculture, Hokkaido University, Sapporo, Japan.
Plant Mol Biol. 1999 Jan;39(2):299-308. doi: 10.1023/a:1006129413306.
We have investigated the organization of the transposon Tam3 family in Antirrhinum majus. Genomic hybridization experiments and characterization of 40 independent Tam3 clones isolated from an A. majus plant revealed that the Tam3 family is quite conserved and the copy sizes are uniform. We did not find any copy with a deleted internal sequence, unlike what is usually observed in other transposons. This exceptionally conserved structure of the Tam3 family was confirmed by PCR and sequencing analyses. Sequencing analysis identified eight copies with sequences completely identical to that of the Tam3 transposase gene. These results suggested that a considerable number of autonomous Tam3 copies are present in the genome of A. majus. Among 24 copies which are surrounded by single copy regions of the genome, 14 copies are present as specific insertions in the line which we used, but absent in other lines. These copies are therefore predicted to be movable. If this ratio is the same for all Tam3 copies in a genome, then a maximum of 60% of the copies are estimated to be movable in the genome. The relatively high frequency of gene tagged by Tam3 might reflect the large number of movable copies in the genome.
我们研究了金鱼草中转座子Tam3家族的组织情况。基因组杂交实验以及从一株金鱼草植株中分离出的40个独立Tam3克隆的特征分析表明，Tam3家族相当保守，且拷贝大小一致。与通常在其他转座子中观察到的情况不同，我们未发现任何内部序列缺失的拷贝。通过PCR和测序分析证实了Tam3家族这种异常保守的结构。测序分析鉴定出8个拷贝，其序列与Tam3转座酶基因的序列完全相同。这些结果表明，金鱼草基因组中存在相当数量的自主Tam3拷贝。在基因组单拷贝区域包围的24个拷贝中，有14个拷贝在我们使用的品系中作为特定插入存在，但在其他品系中不存在。因此，这些拷贝预计是可移动的。如果这个比例对于基因组中所有Tam3拷贝都相同，那么估计基因组中最多60%的拷贝是可移动的。Tam3标记基因的相对高频率可能反映了基因组中大量可移动的拷贝。
