Takasaki N, Park L, Kaeriyama M, Gharrett A J, Okada N
Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan.
J Mol Evol. 1996 Feb;42(2):103-16. doi: 10.1007/BF02198835.
Short interspersed repetitive elements (SINEs), known as the HpaI family, are present in the genomes of all salmonid species (Kido et al., Proc. Natl. Acad. Sci. USA 1991, 88: 2326-2330). Recently, we showed that the retropositional efficiency of the SINE family in the lineage of chum salmon is extraordinarily high in comparison with that in other salmonid lineages. (Takasaki et al., Proc. Natl. Acad. Sci. USA 1994, 91: 10153-10157). To investigate the reason for this high efficiency, we searched for members of the HpaI SINE family that have been amplified species-specifically in pink salmon. Since the efficiency of the species-specific amplification in pink salmon is not high and since other members of the same subfamily of SINEs were also amplified species-specifically in pink salmon, the actual sequence of this subfamily might not be the cause of the high retropositional efficiency of SINEs in chum salmon. Rather, it appears that a highly dominant source gene for the subfamily may have been newly created by retroposition, and some aspect of the local environment around the site of retroposition may have been responsible for the creation of this dominant source gene in chum salmon. Furthermore, a total of 11 sequences of HpaI SINEs that have been amplified species-specifically in three salmon lineages was compiled and characterized. Judging from the distribution of members of the same-sequence subfamily of SINEs in different lineages and from the distribution of the different-sequence subfamilies in the same lineage, we have concluded that multiple dispersed loci are responsible for the amplification of SINEs. We also discuss the additional possibility of horizontal transmission of SINEs between species. The availability of the sets of primers used for the detection of the species-specific amplifications of the SINEs provides a convenient and reliable method for identification of these salmonid species.
短散在重复元件（SINEs），即HpaI家族，存在于所有鲑科物种的基因组中（木户等人，《美国国家科学院院刊》1991年，88卷：2326 - 2330页）。最近，我们发现，与其他鲑科谱系相比，秋鲑谱系中SINE家族的逆转座效率极高。（高崎等人，《美国国家科学院院刊》1994年，91卷：10153 - 10157页）。为了探究这种高效率的原因，我们在粉鲑中寻找物种特异性扩增的HpaI SINE家族成员。由于粉鲑中物种特异性扩增的效率不高，且同一SINE亚家族的其他成员在粉鲑中也有物种特异性扩增，所以该亚家族的实际序列可能不是秋鲑中SINE逆转座效率高的原因。相反，似乎该亚家族的一个高度占主导地位的源基因可能是通过逆转座新产生的，逆转座位点周围局部环境的某些方面可能是秋鲑中这个占主导地位的源基因产生的原因。此外，我们汇编并分析了在三个鲑科谱系中物种特异性扩增的11个HpaI SINE序列。从不同谱系中SINE同序列亚家族成员的分布以及同一谱系中不同序列亚家族的分布来看，我们得出结论，多个分散的位点负责SINE的扩增。我们还讨论了SINE在物种间水平转移的其他可能性。用于检测SINE物种特异性扩增的引物组为这些鲑科物种的鉴定提供了一种方便可靠的方法。
