Widespread Impact of Chromosomal Inversions on Gene Expression Uncovers Robustness via Phenotypic Buffering.
Widespread Impact of Chromosomal Inversions on Gene Expression Uncovers Robustness via Phenotypic Buffering.
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DOI：
10.1093/molbev/msw045
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发表时间：
2016-07
影响因子：
10.7
通讯作者：
Delneri D
中科院分区：
文献类型：
--
作者：
Naseeb S;Carter Z;Minnis D;Donaldson I;Zeef L;Delneri D
真核生物的非随机基因组织在基因组进化和功能中起着重要作用。染色体结构变化影响减数分裂适应性，并且在一些生物体中，与物种形成和对不同环境的快速适应有关。包含少数基因的小尺寸染色体倒置在“严格意义”的酵母菌中普遍存在，而与高等真核生物相比，较大的染色体倒置在酵母中不太常见。为了探索基因顺序对表型、生殖分离和基因表达的影响，我们设计了16株酿酒酵母，在Ty1元件（一种天然重排底物）之间携带所有可能的顺中心和周中心倒置。我们发现4个倒位是致死的，而另外12个倒位在丰富和最小的培养基中没有任何适合性优势或劣势。在减数分裂时，倒区大小与适合度仅呈弱负相关。然而，在断点内携带重组热点的杂合子不相关菌株的育性明显较低。在整个基因组中观察到改变的转录，而不是在反转中过度代表。尽管反向菌株的基因表达差异很大，但在94种测试条件中的大多数条件下，有丝分裂适应度并未受损，这表明表达网络的稳健性缓冲了几种环境中结构变化的有害影响。总的来说，我们的研究结果支持这样一种观点，即转录变化可能补偿ty介导的重排，从而维持恒定的表型，并表明酵母中的大反转不太可能是营养生长期间的可选择性状。
The nonrandom gene organization in eukaryotes plays a significant role in genome evolution and function. Chromosomal structural changes impact meiotic fitness and, in several organisms, are associated with speciation and rapid adaptation to different environments. Small sized chromosomal inversions, encompassing few genes, are pervasive in Saccharomyces “sensu stricto” species, while larger inversions are less common in yeasts compared with higher eukaryotes. To explore the effect of gene order on phenotype, reproductive isolation, and gene expression, we engineered 16 Saccharomyces cerevisiae strains carrying all possible paracentric and pericentric inversions between Ty1 elements, a natural substrate for rearrangements. We found that 4 inversions were lethal, while the other 12 did not show any fitness advantage or disadvantage in rich and minimal media. At meiosis, only a weak negative correlation with fitness was seen with the size of the inverted region. However, significantly lower fertility was seen in heterozygote invertant strains carrying recombination hotspots within the breakpoints. Altered transcription was observed throughout the genome rather than being overrepresented within the inversions. In spite of the large difference in gene expression in the inverted strains, mitotic fitness was not impaired in the majority of the 94 conditions tested, indicating that the robustness of the expression network buffers the deleterious effects of structural changes in several environments. Overall, our results support the notion that transcriptional changes may compensate for Ty-mediated rearrangements resulting in the maintenance of a constant phenotype, and suggest that large inversions in yeast are unlikely to be a selectable trait during vegetative growth.