Tostes Nathália Vállery, Ferreira Marcos Vitor Rosa, Soares Fernanda Aparecida Ferrari, Silva Jéssica Coutinho, Bhering Leonardo Lopes, Clarindo Wellington Ronildo
Laboratório de Citogenética e Citometria, Departamento de Biologia Geral, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brazil.
Laboratório de Biometria, Departamento de Biologia Geral, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brazil.
Sci Rep. 2025 Apr 29;15(1):14997. doi: 10.1038/s41598-025-99560-1.
Micronuclei originate from DNA damage generated by clastogenic and/or by aneugenic effects. Depending on the pattern of damage, they may have distinct genomic origin and composition. Sequences of the centromere, telomere and rDNA have been identified in plant micronuclei. However, other DNA sequences may also be present in the micronuclei, as well as their DNA contents may be different. Here, we investigate the DNA content, genomic composition and origin of micronuclei induced in Zea mays by methyl methanesulfonate (MMS). DNA contents showed a wide range of distribution, suggesting their diverse genomic origins and illustrating how much of the nuclear genome can be lost due to mutagen effects. Micronuclei diversity was also evidenced by in situ probing with different DNA sequences (5S and 18S rDNAs, 180-bp knob and Grande LTR-retrotransposon) and by 6-diamidino-2 phenylindole (DAPI) fluorochrome. Perhaps these sequences are hotspots for MMS damage, especially the Grande LTR-retrotransposon, 5S and 18S rDNAs, which are rich in guanine. In addition, probe pools were constructed from individual genomic DNA of two microdissected micronuclei. These probe pools hybridized on all Z. mays chromosomes. However, the centromere, knob and secondary constriction were hybridized by only one probe pool, evidencing the distinct genomic composition of the micronuclei. We illustrate the micronuclei genomic diversity as they originated from several different chromosomes following the MMS treatment, and demonstrate the extent of the genotoxic damage to the genome. We provide some insights into micronuclei structure and diversity, and show that they can be further explored in mutagenesis research.
微核起源于由断裂剂和/或非整倍体效应产生的DNA损伤。根据损伤模式，它们可能具有不同的基因组起源和组成。在植物微核中已鉴定出着丝粒、端粒和rDNA的序列。然而，微核中也可能存在其他DNA序列，并且它们的DNA含量可能不同。在这里，我们研究了甲基磺酸甲酯（MMS）诱导玉米产生的微核的DNA含量、基因组组成和起源。DNA含量显示出广泛的分布范围，表明它们具有多样的基因组起源，并说明了由于诱变效应核基因组会有多少丢失。用不同的DNA序列（5S和18S rDNA、180 bp的结节和大LTR反转录转座子）原位探测以及用6-二脒基-2-苯基吲哚（DAPI）荧光染料也证明了微核的多样性。也许这些序列是MMS损伤的热点，特别是富含鸟嘌呤的大LTR反转录转座子、5S和18S rDNA。此外，从两个显微切割的微核的单个基因组DNA构建了探针池。这些探针池与所有玉米染色体杂交。然而，着丝粒、结节和次缢痕仅与一个探针池杂交，证明了微核独特的基因组组成。我们阐述了MMS处理后微核的基因组多样性，因为它们起源于几个不同的染色体，并证明了基因组的遗传毒性损伤程度。我们对微核的结构和多样性提供了一些见解，并表明它们可以在诱变研究中进一步探索。
