Chromium(III)-induced father-mediated 45S rRNA genetic and epigenetic inheritance.

B130 Chromium(III), a preconceptional carcinogen in mice, induces hypomethylation in the spacer promoter region of the 45S ribosomal RNA gene ( rRNA ) in the sperm of males two weeks after treatment. Thus, the rRNA gene was monitored in chromium(III), acid saline vehicle, and untreated groups throughout mouse developmental stages, from the sperm of treated animals (40 to 45 each group) to day-8 (10 litters each) and day-11 (9 to10 litters each) embryos, and three tissues (lung, liver, and sperm from epididymis) of 6-week adults (7 to 9 litters each) in the offspring. In addition to DNA methylation in the spacer promoter, single nucleotide polymorphisms (SNPs) in both spacer and gene promoters were quantified by polymerase chain reaction and pyrosequencing techniques. Three new SNP sites were identified in the gene promoter by cloning-sequencing and yielded 4 alleles. In the sperm of treated animals, both chromium(III) and acid saline induced hypomethylation (paired T test, p rRNA gene, which is mediated via paternal exposure and may increase tumor risk in the offspring.