Miller J T, Dong F, Jackson S A, Song J, Jiang J
Department of Horticulture, University of Wisconsin, Madison, Wisconsin 53706, USA.
Genetics. 1998 Dec;150(4):1615-23. doi: 10.1093/genetics/150.4.1615.
Several distinct DNA fragments were subcloned from a sorghum (Sorghum bicolor) bacterial artificial chromosome clone 13I16 that was derived from a centromere. Three fragments showed significant sequence identity to either Ty3/gypsy- or Ty1/copia-like retrotransposons. Fluorescence in situ hybridization (FISH) analysis revealed that the Ty1/copia-related DNA sequences are not specific to the centromeric regions. However, the Ty3/gypsy-related sequences were present exclusively in the centromeres of all sorghum chromosomes. FISH and gel-blot hybridization showed that these sequences are also conserved in the centromeric regions of all species within Gramineae. Thus, we report a new retrotransposon that is conserved in specific chromosomal regions of distantly related eukaryotic species. We propose that the Ty3/gypsy-like retrotransposons in the grass centromeres may be ancient insertions and are likely to have been amplified during centromere evolution. The possible role of centromeric retrotransposons in plant centromere function is discussed.
从来源于着丝粒的高粱（双色高粱）细菌人工染色体克隆13I16中，亚克隆出了几个不同的DNA片段。三个片段与Ty3/gypsy类或Ty1/copia类逆转座子显示出显著的序列同源性。荧光原位杂交（FISH）分析表明，与Ty1/copia相关的DNA序列并非着丝粒区域所特有。然而，与Ty3/gypsy相关的序列仅存在于所有高粱染色体的着丝粒中。FISH和凝胶印迹杂交表明，这些序列在禾本科所有物种的着丝粒区域也保守。因此，我们报道了一种在远缘真核生物物种的特定染色体区域保守的新逆转座子。我们提出，禾本科着丝粒中的Ty3/gypsy类逆转座子可能是古老的插入序列，并且很可能在着丝粒进化过程中发生了扩增。文中还讨论了着丝粒逆转座子在植物着丝粒功能中的可能作用。
