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A team of scientists at the Harvard Gazette recently discovered a new type of ribosomal DNA clock (rDNA), a new aging biomarker based on rDNA, a segment of the genome that was previously bound mechanically to aging.
This newly discovered rDNA could be used to accurately identify the chronological and biological age of an individual. Its applications are potentially vast, especially to measure how exposure to certain pollutants or dietary interventions accelerates or slows the aging of various species, including mice and humans.
Lead author Bernardo Lemos, an associate professor in environmental epigenetics, said: "We hope that the ribosomal clock will provide new information on the impact of the environment and personal choices. on long-term health. The determination of biological age is an essential step in understanding the fundamental aspects of aging and developing tools to inform personal choices in public and public health.
There are two types of age: the chronological age, or the number of years of life of a person or animal, and the biological age, which explains the lifestyle factors that can shorten or extend life, including diet, exercise and environmental exposures. Overall, it has been shown that the biological age was a better predictor of all-cause mortality and the onset of the disease than chronological age.
For this study, scientists observed rDNA, the most active segment of the genome and one that was also mechanically linked to aging in a number of previous studies.
Scientists have speculated that rDNA is a "smoking gun" in the genomic control of aging and could harbor a previously unrecognized clock. To test this idea, they examined epigenetic chemical alterations (also called DNA methylation) in CpG sites, where a cytosine nucleotide is followed by a guanine nucleotide. The study focused on rDNA, a small genomic (13 kilobase) but essential and highly active genome segment, as a new marker of age.
The examination of genome-scale datasets from mice, dogs and people showed that speculation had legitimacy: many CpGs in rDNA showed signs extended methylation resulting from aging. To further test the clock, they envisioned information from 14-week-old mice that reacted to containment of calories, a known mediation that improves lifespan.
Mice on a calorie-restricted diet showed a significant decrease in rDNA methylation at CpG destinations and mice whose feeding was not limited. In addition, calorie-limited mice indicated that their age was younger than their orderly age.
The researchers were surprised to learn that the evaluation of methylation in a small segment of the mammalian genome allowed for clocks as accurate as those built from hundreds of thousands of sites located on the ground. along the genome. They noted that their approach could prove faster and more economical in determining the biological and chronological age than current methods of monitoring scattered sites in the genome. The results highlight the fundamental role of rDNA in aging and highlight its potential as a widely applicable age predictor that can be calibrated for all mammalian species.
It is important to note that clocks respond to interventions, which could allow scientists to study how biological age responds to environmental exposures and lifestyle choices. The determination of a specific biological age can indicate how much a person is better or worse than the general population, and could possibly help determine if that person poses a high risk of death or a particular disease .
The study was published online today in Genome Research.
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