Posted on 07/19/2022 10:49:48 AM PDT by Red Badger
Study in mice is first to directly test health effects of losing male chromosome
Computer generated X and Y chromosomes
The Y (right) may be the runt of the chromosomes, but losing it may lead to heart failure and death. NATHAN DEVERY/SCIENCE SOURCE
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As men get older, they don’t just lose their hair, muscle tone, and knee cartilage. They also start to lose Y chromosomes from their cells. Scientists have linked this vanishing to a long list of diseases and a higher risk of death, but the evidence has been circumstantial. Now, researchers report that when they removed the Y chromosome from male mice, the animals died earlier than their Y-carrying counterparts, likely because their hearts became stiffer.
“This is the best evidence to date” that losing the Y chromosome is detrimental to health, says John Perry, a human geneticist at the University of Cambridge. Perry led one of the biggest studies on the frequency of Y chromosome loss in men, but wasn’t connected to the new research.
Despite its macho reputation, the Y chromosome is a pipsqueak, carrying a mere 71 genes—less than one-tenth as many as the X chromosome. That may be why the chromosome sometimes doesn’t get passed on when a cell divides. Analyzing blood samples is the easiest way to detect loss of Y, and researchers have found the chromosome is missing from at least some white blood cells in about 40% of 70-year-olds and 57% of 93-year-olds. In some older men, more than 80% of the cells can be short a Y chromosome.
Cells can survive and reproduce without a Y, but men lacking the chromosome in some of their cells are more likely to suffer from heart disease, cancer, Alzheimer’s disease, and other aging-related ailments. Moreover, the condition could be a reason why men die on average about 5 years earlier than women in the United States, says molecular biologist Kenneth Walsh of the University of Virginia.
To test whether removing the Y chromosome harms health, Walsh and colleagues performed bone marrow transplants on 38 mice. They used the CRISPR-Cas9 gene-editing tool to delete the Y chromosome from mouse bone marrow cells and then inserted the altered cells into young male mice whose bone marrow had been removed. The swap didn’t banish the Y chromosome from the recipients, but it culled the chromosome from 49% to 81% of white blood cells—about the same percentage as in many humans with Y-chromosome loss. The 37 control mice for this experiment also received bone marrow transplants but retained the Y chromosome.
For nearly 2 years, the researchers followed both groups of animals. The Y-lacking rodents were more likely to die during this period—only about 40% of these mice survived for 600 days after the transplants, versus about 60% of the control rodents.
Mice that lost their Y chromosome also had weaker hearts. After about 15 months, the heart’s contraction strength had declined by close to 20%. In addition, the buildup of tough connective tissue, a process called fibrosis, surged in the hearts of mice missing the Y chromosome. This accumulation stiffens the heart and impairs its ability to pump blood.
The bone marrow transplants the researchers performed on the mice did not eliminate the Y chromosome from heart muscle cells. But the white blood cells called macrophages, which are born in the bone marrow, slip into the heart. The scientists found that many of the macrophages from mice lacking the Y chromosome began to promote fibrosis, stimulating other cells in the heart to spin more connective tissue.
Something similar may be going on in humans. Walsh and colleagues obtained DNA and survival information for more than 15,000 men from the UK Biobank, a huge health database. The team determined that men who had lost the Y chromosome from at least 40% of their white blood cells were 31% more likely to die from circulatory system diseases than those in which the chromosome was more abundant. When the scientists broke down the causes of death that correlated with the Y chromosome’s absence, they identified several cardiac conditions, including heart failure.
Losing the Y chromosome spurs fibrosis in the heart, resulting in heart failure and an earlier death, the team concludes today in Science. Researchers have long downplayed the Y chromosome’s health impact because it sports so few genes, Walsh says, but the evidence suggests shedding it “leads to a staggering amount of years of life lost.”
Genetic epidemiologist Mitchell Machiela of the National Cancer Institute, who also wasn’t connected to the study, says the research provides “compelling evidence.” The discovery that macrophages in the Y-lacking mice change their “personality” and begin to foster fibrosis makes sense, adds collagen biologist Amy Bradshaw of the Medical University of South Carolina. This switch “is central to a lot of the fibrosis we see in the heart.”
However, cardiologist Nikolaos Frangogiannis of the Albert Einstein College of Medicine cautions that the results do not confirm that increased fibrosis is killing the mice. In the animals missing the Y chromosome, “the fibrosis is fairly subtle,” he says. Moreover, the heart weakening the rodents suffered “is not that bad” and would not be fatal. The mice may be dying from some other heart-related cause. Still, he says, the study is “very exciting” and “could have a major impact on the way we see heart failure.”
doi: 10.1126/science.add9504
It is a proven fact that men like their muscles stiffer.
I click off 71 in a couple weeks and agree with your assessment of exercise! Good for you.
I blew the meniscus on my left knee about 15 years ago and the pain was excruciating. I was able to get back to pain-free walking and hiking with judicious rest and excise. Now I only get occasional twinges.
My wife had meniscus arthroscopic surgery on both knees and has had excellent outcomes.
ha ha oh that y chromosone is still there. I’m sure Mr Levine has an admirals stripe for two x’s anyway.
LOL
Yeah I misspelled lab, but I guess it works either way lol.
I was walking on the beach yesterday, and Boom! I knew I lost something, but couldn’t figure out what it was.
Now I know.
5.56mm
“..people who produce and seek to distribute semen to targeted recipients..”
What is a man?
A vibration platform and once a week fasting are the best way to counteract aging processes.
When I lose my y..do I get to go in the women’s shower?
Like Chuck Bronson.
I’ve posted spelling errors myself. That just happened to be a funny one.
Keeping testosterone levels higher and keeping antioxidant levels high.
Exercise/physical movememt is much more vital to brain health than crossword puzzles. The coordination required keeps more of the brain engaged and active.
Once again I’m happy I’m not a mouse....
My elderly dad still works part time in a restricted area. I am not sure about losing Y chromosomes, but he lost his fingerprints and has to use a RFID badge to enter the building....
“Keeping testosterone levels higher and keeping antioxidant levels high.”
What says that keeps the reduction of Y chromosomes down?.
Yes, testosterone and antioxicents are important, but the Y chromosome issues seems to be an unrelated separate matter.
Well, a “vibration platform” and fasting might be generally helpful in aging, but what says those things will have any relationship to the Y chromosome issue, which to me seems just a “matter of time” and not speficically to “aging” in general?
I think there are some things which just may come to all in time, and G-d did not mean for humans to live forever any way, and least not after Adam.
Damage to chromosomes occur due to oxidant stress
Antioxidants repair or prevent the damage
Healthy chromosomes that will work properly have long telomeres
Antioxidants like c and e lengthen dna telomeres
This means the chromosomes will stick around because they will function well and divide well and have less damage over the long haul
Keeping chromosomes healthy keeps them being around
whut? So we turn fag as we age? No way!
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