CNRS-UMR 7592, Institut Jacques Monod, Paris, France.
PLoS One. 2009 Dec 14;4(12):e8201. doi: 10.1371/journal.pone.0008201.
The lack of correlation between genome size and organismal complexity is understood in terms of the massive presence of repetitive and non-coding DNA. This non-coding subgenome has long been called "junk" DNA. However, it might have important functions. Generation of junk DNA depends on proliferation of selfish DNA elements and on local or global DNA duplication followed by genic non-functionalization.
METHODOLOGY/PRINCIPAL FINDINGS: Evidence from genomic analyses and experimental data indicates that Whole Genome Duplications (WGD) are often followed by a return to the diploid state, through DNA deletions and intra/interchromosomal rearrangements. We use simple theoretical models and simulations to explore how a WGD accompanied by sequence deletions might affect the dosage balance often required among several gene products involved in regulatory processes. We find that potential genomic deletions leading to changes in nuclear and cell volume might potentially perturb gene dosage balance.
CONCLUSIONS/SIGNIFICANCE: The potentially negative impact of DNA deletions can be buffered if deleted genic DNA is, at least temporarily, replaced by repetitive DNA so that the nuclear/cell volume remains compatible with normal living. Thus, we speculate that retention of non-functionalized non-coding DNA, and replacement of deleted DNA through proliferation of selfish elements, might help avoid dosage imbalances in cycles of polyploidization and diploidization, which are particularly frequent in plants.
人们从基因组大小与生物体复杂性之间缺乏相关性的角度来理解大量存在的重复和非编码 DNA。这个非编码亚基因组长期以来一直被称为“垃圾”DNA。然而，它可能具有重要的功能。垃圾 DNA的产生取决于自私 DNA 元素的增殖，以及局部或全局的 DNA 复制，然后是基因的非功能化。
方法/主要发现：来自基因组分析和实验数据的证据表明，全基因组复制（WGD）通常会通过 DNA 缺失和染色体内/间重排，回到二倍体状态。我们使用简单的理论模型和模拟来探索 WGD 伴随着序列缺失如何影响参与调控过程的几个基因产物之间通常需要的剂量平衡。我们发现，潜在的基因组缺失导致核和细胞体积变化，可能会潜在地破坏基因剂量平衡。
结论/意义：如果被删除的基因 DNA 至少暂时被重复 DNA 取代，从而使核/细胞体积与正常生活保持兼容，那么潜在的 DNA 删除的负面影响可以得到缓冲。因此，我们推测，非功能化的非编码 DNA 的保留，以及通过增殖自私元素取代缺失的 DNA，可能有助于避免多倍体化和二倍体化循环中的剂量失衡，这种情况在植物中尤为频繁。
