Preferential occupancy of R2 retroelements on the B chromosomes of the grasshopper Eyprepocnemis plorans.
Preferential occupancy of R2 retroelements on the B chromosomes of the grasshopper Eyprepocnemis plorans.
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DOI：
10.1371/journal.pone.0091820
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
López-León MD
中科院分区：
文献类型：
--
作者：
Montiel EE;Cabrero J;Ruiz-Estévez M;Burke WD;Eickbush TH;Camacho JP;López-León MD
R2 非 LTR 逆转录转座子专门插入宿主的 28S rRNA 基因中，并通过与 rDNA 单位共转录来表达。蚱蜢 Eyprepocnemis plorans 在其大部分 A 染色体上含有转录的 rDNA 簇，以及在许多种群中发现的寄生 B 染色体上的非转录 rDNA 簇。这里确定了 E. plorans R2 元件的结构、其相对于 rDNA 单位数量的丰度及其逆转录转座活性。从五个种群中筛选出来的动物的 A 染色体上平均含有超过 12,000 个 rDNA 单位，但令人惊讶的是只有约 100 个 R2 元件。监测这些人群中个体的 R2 插入模式仅发现低水平的逆转录转座。在 E. porans 中观察到的低 R2 插入率与之前在 rDNA 单位少得多的昆虫物种中观察到的高 R2 插入率不同。有人提出，高水平的 R2 在 E. plorans 中受到强烈选择，因为该物种的 rDNA 转录机制无法区分 R2 插入单位和未插入单位。 E. plorans 的 B 染色体含有额外的 7,000 至 15,000 个 rDNA 单位，但与 A 染色体相反，含有 150 至 1,500 多个 R2 元件。不活跃的 B 染色体 rDNA 簇中 R2 浓度较高，表明这些染色体可以充当 R2 插入的汇点，从而进一步降低 A 染色体上的插入水平。这些研究表明寄生 B 染色体和 R2 元件之间存在有趣的进化关系。
R2 non-LTR retrotransposons exclusively insert into the 28S rRNA genes of their host, and are expressed by co-transcription with the rDNA unit. The grasshopper Eyprepocnemis plorans contains transcribed rDNA clusters on most of its A chromosomes, as well as non-transcribed rDNA clusters on the parasitic B chromosomes found in many populations. Here the structure of the E. plorans R2 element, its abundance relative to the number of rDNA units and its retrotransposition activity were determined. Animals screened from five populations contained on average over 12,000 rDNA units on their A chromosomes, but surprisingly only about 100 R2 elements. Monitoring the patterns of R2 insertions in individuals from these populations revealed only low levels of retrotransposition. The low rates of R2 insertion observed in E. plorans differ from the high levels of R2 insertion previously observed in insect species that have many fewer rDNA units. It is proposed that high levels of R2 are strongly selected against in E. plorans, because the rDNA transcription machinery in this species is unable to differentiate between R2-inserted and uninserted units. The B chromosomes of E. plorans contain an additional 7,000 to 15,000 rDNA units, but in contrast to the A chromosomes, from 150 to over 1,500 R2 elements. The higher concentration of R2 in the inactive B chromosomes rDNA clusters suggests these chromosomes can act as a sink for R2 insertions thus further reducing the level of insertions on the A chromosomes. These studies suggest an interesting evolutionary relationship between the parasitic B chromosomes and R2 elements.
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影响因子：
1.6
作者：
Cabrero, J;Bakkali, M;Camacho, JPM
通讯作者：
Camacho, JPM
影响因子：
3.1
作者：
CABRERO, J;ALCHE, JD;CAMACHO, JPM
通讯作者：
CAMACHO, JPM
影响因子：
11.4
作者：
EICKBUSH, TH;ROBINS, B
通讯作者：
ROBINS, B
影响因子：
10.7
作者：
Bachtrog, D
通讯作者：
Bachtrog, D
影响因子：
3.8
作者：
Cabrero, J;López-León, MD;Camacho, JPM
通讯作者：
Camacho, JPM