Aging results in hypermethylation of ribosomal DNA in sperm and liver of male rats
Bibliographic record
Abstract
There is a concern that increased paternal age may be associated with altered fertility and an increased incidence of birth defects in man. In previous studies of aged male rats, we have found abnormalities in the fertility and in the embryos sired by older males. Aging in mammals is associated with alterations in the content and patterns of DNA methylation in somatic cells; however, little is known in regard to germ cells. A systematic search for global and gene-specific alterations of DNA methylation in germ cells and liver of male rats was done. Restriction landmark genomic scanning, a method used to determine specific methylation patterns of CpG island sequences, has revealed a region of the ribosomal DNA locus that is preferentially hypermethylated with age in both spermatozoa and liver. In contrast, all single copy CpG island sequences in spermatozoa and in liver remain unaltered with age. We further demonstrate that a large proportion of rat ribosomal DNA is normally methylated and that regional and site-specific differences exist in the patterns of methylation between spermatozoa and liver. We conclude that patterns of ribosomal DNA methylation in spermatozoa are vulnerable to the same age-dependent alterations that we observe in normal aging liver. Failure to maintain normal DNA methylation patterns in male germ cells could be one of the mechanisms underlying age-related abnormalities in fertility and progeny outcome.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".