Physical Localization and DNA Methylation of 45S rRNA Gene Loci in Jatropha curcas L. |
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| Authors: | Zhiyun Gong Chao Xue Mingliang Zhang Rui Guo Yong Zhou Guoxin Shi |
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| Affiliation: | Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou, Jiangsu, China.; Oregon State University, United States of America, |
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| Abstract: | In eukaryotes, 45S rRNA genes are arranged in tandem arrays of repeat units, and not all copies are transcribed during mitosis. DNA methylation is considered to be an epigenetic marker for rDNA activation. Here, we established a clear and accurate karyogram for Jatropha curcas L. The chromosomal formula was found to be 2n = 2x = 22 = 12m+10sm. We found that the 45S rDNA loci were located at the termini of chromosomes 7 and 9 in J. curcas. The distribution of 45S rDNA has no significant difference in J. curcas from different sources. Based on the hybridization signal patterns, there were two forms of rDNA - dispersed and condensed. The dispersed type of signals appeared during interphase and prophase, while the condensed types appeared during different stages of mitosis. DNA methylation analysis showed that when 45S rDNA stronger signals were dispersed and connected to the nucleolus, DNA methylation levels were lower at interphase and prophase. However, when the 45S rDNA loci were condensed, especially during metaphase, they showed different forms of DNA methylation. |
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