Bae Young-An, Kong Yoon
Department of Molecular Parasitology and Center for Molecular Medicine, Sungkyunkwan University School of Medicine and Samsung Biomedical Research Institute, Suwon 440-746, Republic of Korea.
Korean J Parasitol. 2003 Dec;41(4):209-19. doi: 10.3347/kjp.2003.41.4.209.
The evolutionary course of the CsRn1 long-terminal-repeat (LTR) retrotransposon was predicted by conducting a phylogenetic analysis with its paralog LTR sequences. Based on the clustering patterns in the phylogenetic tree, multiple CsRn1 copies could be grouped into four subsets, which were shown to have different integration times. Their differential sequence divergences and heterogeneous integration patterns strongly suggested that these subsets appeared sequentially in the genome of C. sinensis. Members of recently expanding subset showed the lowest level of divergence in their LTR and reverse transcriptase gene sequences. They were also shown to be highly polymorphic among individual genomes of the trematode. The CsRn1 element exhibited a preference for repetitive, agenic chromosomal regions in terms of selecting integration targets. Our results suggested that CsRn1 might induce a considerable degree of intergenomic variation and, thereby, have influenced the evolution of the C. sinensis genome.
通过对CsRn1长末端重复序列（LTR）逆转录转座子的旁系同源LTR序列进行系统发育分析，预测了其进化历程。基于系统发育树中的聚类模式，多个CsRn1拷贝可分为四个子集，这些子集具有不同的整合时间。它们不同的序列分歧和异质的整合模式强烈表明，这些子集在华支睾吸虫基因组中是依次出现的。最近扩张的子集中的成员在其LTR和逆转录酶基因序列中显示出最低水平的分歧。它们在吸虫的个体基因组中也表现出高度多态性。在选择整合靶点方面，CsRn1元件表现出对重复的、无基因的染色体区域的偏好。我们的结果表明，CsRn1可能会引起相当程度的基因组间变异，从而影响华支睾吸虫基因组的进化。
