Genome plasticity in response to stress in Tetrahymena thermophila: selective and reversible chromosome amplification and paralogous expansion of metallothionein genes.
Genome plasticity in response to stress in Tetrahymena thermophila: selective and reversible chromosome amplification and paralogous expansion of metallothionein genes.
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DOI：
10.1111/1462-2920.14251
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发表时间：
2018-07
影响因子：
5.1
通讯作者：
Gutiérrez JC
中科院分区：
文献类型：
--
作者：
de Francisco P;Martín-González A;Turkewitz AP;Gutiérrez JC
极端压力情况会诱发遗传变异，包括基因组重组。在像嗜热四膜虫这样的纤毛虫中，体细胞大核的约 45 倍倍性可能能够实现依赖于基因组可塑性的适应性反应。为了确定与金属毒性相关的潜在基因组水平适应，我们在对极端金属浓度（Cd2+、Cu2+或Pb2+）进行延长适应期后分离出三种嗜热四膜虫菌株。在 Cd 适应菌株中，我们发现位于同一大核染色体的三个基因的拷贝数增加了约 5 倍，其中包括两个金属硫蛋白基因 MTT1 和 MTT3。该大核染色体的表观扩增是可逆且可重复的，具体取决于环境金属的存在。我们还分析了 MTT1 和/或 MTT5 的三种敲除 (KO) 和/或敲低 (KD) 菌株。在MTT5KD菌株中，我们发现至少两个由MTT1的旁系同源扩增产生的新基因，它们编码MTT1的截短变体。这种扩展可以通过基于大核染色体对上 MTT1 基因之间体细胞重组的模型来解释。至少有两个新的旁系同源物在 Cd2+ 的作用下被转录和上调。总而言之，我们已经确定了两种不同的机制，都涉及多倍体大核中的基因组可塑性，这可能代表对金属相关应激的适应性反应。
Extreme stress situations can induce genetic variations including genome reorganization. In ciliates like Tetrahymena thermophila, the ~45-fold ploidy of the somatic macronucleus may enable adaptive responses that depend on genome plasticity. To identify potential genome-level adaptations related to metal toxicity, we isolated three Tetrahymena thermophila strains afteran extended adaptation period to extreme metal concentrations (Cd2+, Cu2+ or Pb2+). In the Cd-adapted strain, we found a ~5-fold copy number increase of three genes located in the same macronuclear chromosome, includingtwo metallothionein genes, MTT1 and MTT3. The apparent amplification of this macronuclear chromosome was reversible and reproducible, depending on the presence of environmental metal. We also analysed three knockout (KO) and/or knockdown (KD) strains for MTT1 and/or MTT5. In the MTT5KD strain, we found at least two new genes arising from paralogous expansion of MTT1, which encode truncated variants of MTT1. The expansion, can be explained by a model based on somatic recombination between MTT1 genes on pairs of macronuclear chromosomes. At least two of the new paralogs are transcribed and upregulated in response to Cd2+. Altogether, we have thus identified two distinct mechanisms, both involving genomic plasticity in the polyploid macronucleus, that may represent adaptive responses to metal-related stress.
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影响因子：
6.4
作者：
Adamo GM;Brocca S;Passolunghi S;Salvato B;Lotti M
通讯作者：
Lotti M
影响因子：
4
作者：
Heng, Henry H. Q.
通讯作者：
Heng, Henry H. Q.
嗜热四膜虫通过基因片段连接和删除选择几种交配类型之一
影响因子：
9.8
作者：
Cervantes MD;Hamilton EP;Xiong J;Lawson MJ;Yuan D;Hadjithomas M;Miao W;Orias E
通讯作者：
Orias E
影响因子：
9.2
作者：
Espart A;Marín M;Gil-Moreno S;Palacios Ò;Amaro F;Martín-González A;Gutiérrez JC;Capdevila M;Atrian S
通讯作者：
Atrian S
影响因子：
4.4
作者：
Farslow JC;Lipinski KJ;Packard LB;Edgley ML;Taylor J;Flibotte S;Moerman DG;Katju V;Bergthorsson U
通讯作者：
Bergthorsson U