The human papillomavirus-18 genome is efficiently targeted by cellular DNA methylation

AbstractHuman papillomaviruses (HPVs) infect epithelia, including the simple and the squamous epithelia of the cervix, where they can cause cancer and precursor lesions. The molecular events leading from asymptomatic HPV infections to neoplasia are poorly understood. There is evidence that progression is modulated by transcriptional mechanisms that control HPV gene expression. Here, we report the frequent methylation of HPV-18 genomes in cell culture and in situ. DNA methylation is generally known to lead to transcriptional repression due to chromatin changes. We investigated two cell lines derived from cervical cancers, namely, C4-1, which contains one HPV-18 genome, and different clones of HeLa, with 50 HPV-18 genomes. By restriction cleavage, we detected strong methylation of the L1 gene and absence of methylation of parts of the long control region (LCR). A 3-kb segment of the HPV-18 genomes downstream of the oncogenes was deleted in both cell lines. Bisulfite sequencing showed that in C4-1 cells and two HeLa clones, 18 of the 19 CpG residues in the 1.2-kb terminal part of the L1 gene were methylated, whereas a third HeLa clone had only eight methylated CpG groups, indicating changes of the methylation pattern after the establishment of the HeLa cell line. In the same four clones, none of the 12 CpG residues that overlapped with the enhancer and promoter was methylated. In six HPV-18 containing cancers and five smears from asymptomatic patients, most of the CpG residues in the L1 gene were methylated. There was complete or partial methylation, respectively, of the HPV enhancer in three of the cancers, and lack of methylation in the remaining eight samples. The promoter sequences were methylated in three of the six cancers and four of the six smears, and unmethylated elsewhere. Our data show that epithelial cells efficiently target HPV-18 genomes for DNA methylation, which may affect late and early gene transcription

Genetic Divergence for Grain Yield and Its Components in Bread Wheat (Triticum aestivum L.): Experimental Investigation

The present investigation Comprises 34 advanced breeding lines including checks of bread wheat and experiment was conducted in a complete randomized block design with three replications at the research farm department of genetics and plant breeding, RVSKVV, B.M. College of Agriculture, Khandwa during Rabi season (November 2021 to April 2022) for estimation of the multivariate analysis of divergence. The advanced breeding lines were grouped into seven clusters. Cluster III contained the highest number of advanced breeding lines(12) and clusters V, VI, and VII contained the lowest (1 each). The inter-cluster distance in most cases was larger than the intra cluster distance which indicated that wider diversity is present among the advanced breeding lines of distant grouped. The highest intra cluster distance was observed in cluster IV revealed maximum genetic divergence among its constituents. The highest inter-cluster distance was found between cluster VI and VII and the lowest was between cluster V and VI. Highest cluster mean exhibited in cluster VII for most of the agro-morphological traits i.e. number of tillers/plant, spike length, spike weight, number of grain/spike followed by cluster II for grain filling period, days to maturity and plant height. On the basis of genetic diversity analysis, maximum percent contribution towards genetic divergence in 34 advanced breeding lines were found in grain filling period, days to maturity, number of grain/spike, days to 50% flowering, biological yield per plant and harvest index. Such differences in the genetic component of traits studied in the manuscript can be applied as a source of variation in other breeding programmes and crossing nurseries for wheat improvement