Post Graduate Program in Evolutionary Genetics and Molecular Biology, Department of Genetics and Evolution, Federal University of São Carlos, Rodovia Washington Luís Km 235, São Carlos 13565-905, SP, Brazil.
Post Graduate Program in Evolutionary Biology, Department of Structural, Molecular and Genetic Biology, State University of Ponta Grossa, Avenida Carlos Cavalcanti 4748, Ponta Grossa 84030-900, PR, Brazil.
Cells. 2021 May 11;10(5):1162. doi: 10.3390/cells10051162.
The way in which transcriptional activity overcomes the physical DNA structure and gene regulation mechanisms involves complex processes that are not yet fully understood. Modifications in the cytosine-guanine sequence of DNA by 5-mC are preferentially located in heterochromatic regions and are related to gene silencing. Herein, we investigate evidence of epigenetic regulation related to the B chromosome model and transposable elements in . Indirect immunofluorescence using anti-5-mC to mark methylated regions was employed along with quantitative ELISA to determine the total genomic DNA methylation level. 5-mC signals were dispersed in the chromosomes of both females and males, with preferential accumulation in the B chromosome. In addition to the heterochromatic methylated regions, our results suggest that methylation is associated with transposable elements (LINE and Tc1-Mariner). Heterochromatin content was measured based on the C-band length in relation to the size of chromosome 1. The B chromosome in comprises heterochromatin located in the pericentromeric region of both arms of this isochromosome. In this context, individuals with B chromosomes should have an increased heterochromatin content when compared to individuals that do not. Although, both heterochromatin content and genome methylation showed no significant differences between sexes or in relation to the occurrence of B chromosomes. Our evidence suggests that the B chromosome can have a compensation effect on the heterochromatin content and that methylation possibly operates to silence TEs in . This represents a sui generis compensation and gene activity buffering mechanism.
转录活性克服 DNA 结构和基因调控机制的方式涉及尚未完全理解的复杂过程。DNA 中胞嘧啶-鸟嘌呤序列的 5-mC 修饰优先位于异染色质区域，并与基因沉默有关。在此，我们研究了与 B 染色体模型和转座元件相关的表观遗传调控的证据。使用抗 5-mC 标记甲基化区域的间接免疫荧光与定量 ELISA 一起用于确定总基因组 DNA 甲基化水平。5-mC 信号在雌性和雄性的染色体中分散，在 B 染色体中优先积累。除了异染色质甲基化区域外，我们的结果表明，甲基化与转座元件（LINE 和 Tc1-Mariner）有关。根据 C 带长度与染色体 1 大小的关系来测量异染色质含量。包含在 B 染色体中的异染色质位于这条等臂染色体的两个臂的着丝粒区域。在这种情况下，与没有 B 染色体的个体相比，具有 B 染色体的个体应该具有增加的异染色质含量。尽管异染色质含量和基因组甲基化在性别之间或与 B 染色体的发生之间没有显示出显著差异。我们的证据表明，B 染色体可以对异染色质含量产生补偿效应，并且甲基化可能用于沉默 中的 TEs。这代表了一种独特的补偿和基因活性缓冲机制。
