Studies of the novel retrotransposable elements appeared on rice chromosomes

我们已经确定和特点的各种反转录转座子或不LTR的基因组中的水稻。RIES 1是一种copia类型的逆转录转座子，最初在野生稻澳大利亚稻中发现，其拷贝数量非常多。RIRE 2、RIRE 3和RIRE 8分离自水稻IR 36。结果表明，这些元件是具有LTR的吉普赛型反转录转座子，它们在水稻染色体上经常相互嵌套。RIRE 2最初被发现是与TrsA相关的序列，TrsA是位于水稻染色体亚端粒区的串联重复序列。RIRE 2的gag和pol区域与具有LTR的大刍草反转录转座子Grande 1的gag和pol区域具有高度的同源性，这些吉普赛型反转录转座子的rt基因的氨基酸序列显示它们可分为RIRE 3-RIRE 8家族和RIRE 2-Grande 1家族。我们还确定了LINE元件，非LTR反转录转座子，从各种成员的高等植物，包括水稻。序列分析表明，这些元件包含在该区域保守的氨基酸序列基序。系统发育分析表明，这些元件是垂直传播的，而不像其他具有LTR的逆转录转座子，这些元件被认为是水平传播的。

We have identified and characterized various retrotransposons with or without LTR in the genome of O.sativa. RIRE1, a retrotransposon of copia type, was originally found in wild rice O.austrariensis in an extraordinary number of copies. RIRE2, RIRE3 and RIRE8 were isolated from O.sativa IR36. These elements turned out to be retrotransposons of gypsy type with LTR.These elements were often nested one another on rice chromosomes. RIRE2 was originally found as a sequence associated with TrsA,a tandem repeat sequence at the subtelomeric regions of the O.sativa chromosome. The gag and the pol regions of RIRE2 show high homology with those of Grande1, a teosinte retrotransposon with LTR.The amino acid sequences of rt genes of these gypsy-type retrotransposons revealed that they were divided into two groups, such as RIRE3-RIRE8 family and RIRE2-Grande1 family. We have also identified LINE elements, non-LTR retrotransposons, from the various members of the higher plants including rice. Sequence analysis revealed that these elements contained amino acid sequence motifs conserved in the region. Phylogenetic analysis indicated that these elements were transmitted vertically unlike other retrotransposons with LTR,which were believed to be transmitted horizontally.