People always long for longevity. For this reason, longevity secrets such as exercising more, eating a reasonable diet, regular work and rest, and maintaining a relaxed attitude have been repeatedly mentioned. Although these lifestyles can indeed make us healthy and live longer, scientific research has found that what really controls the lifespan of humans and all animals is the regulation of genes in our bodies.
DNA methylation and longevity
Methyl is a group formed after the methane molecule loses a hydrogen atom. It is composed of carbon and hydrogen and plays an important role in animal bodies. However, animals cannot synthesize methyl groups by themselves and need to be absorbed from some methyl-rich substances. Such methyl-rich substances are called "methyl donors", such as betaine, methionine, choline, folic acid, Vitamin B12, etc.
After the methyl group enters the animal body, it can bind to certain specific parts of the DNA. This binding process is called methylation. DNA methylation does not change the gene sequence, but it regulates the expression of the gene.
The level of DNA methylation decreases with age. A study published in the Proceedings of the National Academy of Sciences in 2012 showed that the degree of DNA methylation in 103-year-old individuals is lower than that of newborns, and the reduction is not a small number. The methylation sites of people over a hundred years old There are even 500,000 fewer than babies. This means that by observing the degree of DNA methylation in an animal, the life span of the animal can be inferred to a certain extent.
Benjamin Mayne, a molecular biologist at the Australian Commonwealth Organization for Scientific Research, started by comparing the location and number of gene methylation, which can more accurately estimate the life span of different species. Meyn found the genomes of 252 vertebrates from the global genome database, and then by comparing the differences in gene methylation sites and numbers of animals with different lifespans, he found some genes that affect the lifespan of vertebrates. These genes have different degrees of influence on lifespan. Meyn conducted various simulation calculations based on different influencing factors, and finally found the most reliable formula for predicting results.
Meyn used this formula to estimate the lifespan of some species. For example, he estimated that the recently extinct species Pingta Island giant tortoise had a lifespan of 120 years, and the last member of the species, Longthem, who died in 2012 George was 112 years old. The longest-lived mammal in the world, the right whale, has an estimated lifespan of 268 years. This prediction is 57 years older than the oldest individual of this species discovered today, but it is very likely to exist in the deep sea. Right whale.
In another study, the researchers compared the genetic status of a pair of 3-year-old identical twins with another pair of 50-year-old identical twins. They found that the degree of methylation and histone modification between 3-year-old identical twins was basically the same, while the degree of methylation, histone modification and gene expression between 50-year-old identical twins was quite different. This shows that by detecting the degree of DNA methylation in different individuals, biologists can predict the lifespan of an individual in the future.
The "killer" wreaking havoc in the body
do you know? As you read this article, there are countless "killers" in your body attacking your cells, and your lifespan is being stolen little by little. This cold "killer" is free radicals.
As the name implies, free radicals are a type of free ionic groups, such as superoxide ions. It is free because it has an unpaired electron, which will snatch an electron from other substances everywhere and make itself form a stable substance. In fact, freedom basically has a partner. In living organisms, its partner is hydrogen ion. When living things breathe, oxygen is decomposed into oxygen ions. These oxygen ions combine with hydrogen ions near the mitochondrial membrane. However, there are too many oxygen ions. Not all oxygen ions can find their destined partners, so "single" oxygen Ions eventually become free radicals, and they embark on the road of "forcible and arrogant".
Free radicals are not picky. They will snatch electrons from all encountered substances such as DNA, proteins and sugars, destroy the original stable structure of these substances, and ultimately damage the health of organisms and even shorten their lifespan.
From this, we know that free radicals are produced during respiration. If respiration and metabolism are weakened, will organisms live longer? Some facts confirm this view. There are many long-lived animals living in the cold deep sea, such as the 507-year-old Arctic clam and the 392-year-old Greenland shark. Dr. Steven Ostad of the University of Alabama at Birmingham believes that low-temperature environments reduce the rate of biological metabolism, thereby slowing the production of free radicals and the process of cell division, so biological life is longer.
Other "programmers" of life programs
Chromosomes and genes determine all the traits of organisms, and lifespan is naturally controlled by them. Scientists have found some lifespan "programmers", such as telomeres on chromosomes. Telomeres are structures located at the ends of chromosomes. When cells divide, chromosomes will also replicate and divide. After each division, the telomeres at the ends will shorten. When the telomeres are short to a limit, the cell will die. When most of the cells in the human body die , People are gradually aging and eventually dying.
Some scientists are also looking for "longevity genes." Researchers at the University of East Anglia in the United Kingdom and the University of Uppsala in Sweden have found a gene called DAF-2 in C. elegans, which researchers believe is related to the aging process. When the researchers "turned off" the worm's DAF-2 gene, the worm's lifespan was doubled and its offspring became healthier.
With the popularization of gene sequencing technology, scientists have also found "longevity genes" in humans. Scientists from the New Zealand Gene Research Center sequenced the genes of 100 New Zealand people over the age of 100, and found two types of genes that are conducive to longevity, APOE and FOXO3A. APOE can accelerate blood lipid metabolism and reduce people's blood lipids, while FOXO3A can prolong the cell division cycle, reduce the number of cell divisions, repair DNA damage, and prevent cell cancer. There is also a group of genes called SIRT. Many scientists agree that it has a DNA repair function and is a well-deserved longevity gene.
