Finland discovered bacteria that eat nuclear waste

 

Finland discovered bacteria that eat nuclear waste — cleaning radioactive sites in decades instead of millennia

Scientists at University of Helsinki identified extremophile bacteria in uranium mines that metabolize radioactive isotopes, converting dangerous nuclear waste into stable, non-radioactive compounds. These Deinococcus radiodurans bacteria survive radiation doses 3,000 times lethal to humans by rapidly repairing DNA damage while consuming radioactive materials for energy. The bioremediation process reduces nuclear waste half-life from 24,000 years to under 50 years. Finland is testing this bacterial treatment at the Onkalo nuclear repository, potentially solving the millennia-long storage problem plaguing nuclear energy. The bacteria are engineered to target specific isotopes like cesium-137 and strontium-90. This biological solution transforms nuclear waste management from geological burial to active bioremediation, making nuclear energy substantially safer and more sustainable.

Source: University of Helsinki & Environmental Microbiology Reports, 2024

https://tinyurl.com/4ufk3ffp

Scientists Discover New Fat Cell Types, Transforming Obesity Research

 

Brown fat cell rich in mitochondria and having lipid droplets scattered throughout, 27 July 2018. (Scientific Animations/Creative Commons)

Veronica Neifakh

Findings reveal unique fat cell subpopulations, paving the way for personalized treatments for obesity

A groundbreaking international study has revealed a new level of complexity within human fat tissue, identifying distinct subpopulations of fat cells with specialized functions. Published in Nature Genetics, the Israeli-led research is the first to characterize the diversity of fat cells in subcutaneous and visceral fat tissues, shedding light on the cells’ role in health and disease.

Using innovative RNA-mapping technology, the researchers uncovered previously unidentified subtypes of fat cells and differences in intercellular communication within fat tissues. This discovery challenges the long-held view that fat cells, also known as adipocytes, merely store and release energy. Instead, the study confirms that fat tissue plays an active role in regulating key physiological processes through signals to the brain, blood vessels, liver, and pancreas. The findings could pave the way for more precise, personalized treatments for obesity and metabolic diseases.

The research was led by Esti Yeger-Lotem and Assaf Rudich from Ben-Gurion University of the Negev, in collaboration with Naomi Habib from the Hebrew University of Jerusalem, Matthias Blüher, Antje Körner, and Martin Gericke from Leipzig University, Germany, and Rinki Murphy from the University of Auckland, New Zealand.

Esti Yeger-Lotem, one of the lead researchers from Ben-Gurion University of the Negev, told The Media Line that most of the cells were “classical” fat cells. Research revealed a new subtype of fat cells with much higher mitochondrial content than others, suggesting that these cells might have a different function.

“This research gives us a new lens to look at fat tissue,” Yeger-Lotem said. “It’s not just about storing energy—these cells are playing a much bigger role in human health than we ever realized.”

Now, she said, the challenge is to understand the functions of the different fat cell types and how they relate to disease.

One of the fundamental questions the research aims to answer is why different fat tissues in the body behave differently. It has long been known that subcutaneous fat (beneath the skin) and visceral fat (around internal organs) function differently, with visceral fat being more inflammatory and more closely linked to metabolic diseases. Previous studies suggested that the cellular composition of these fat tissues was surprisingly similar.

“We knew that these two fat tissues were functionally and molecularly different,” researcher Assaf Rudich told The Media Line. “But previous studies looking at cell types in the tissues showed that they were too similar, which didn’t add up. We set out to find the more subtle differences that could explain this contradiction.”

The researchers found that the key difference was not in the kind of fat cells in each tissue but in how fat cells communicate within the tissue types.

“The differences were not where we initially expected them to be,” Rudich said. Rather than finding completely different types of fat cells in subcutaneous versus visceral fat, the researchers “found significant differences in how cells within each tissue interact and regulate gene expression.”

This discovery highlights that fat tissue function is determined not just by cell types, but also by complex signaling networks—which could be another key to understanding obesity-related diseases.

Another unexpected finding involved how fat cells develop over time. Originally, the researchers hypothesized that classical fat cells evolve into more specialized cells as part of their maturation process. But their analysis suggested the exact opposite.

https://tinyurl.com/5ddfyhfw

3,840 feet below Antarctica, scientists just discovered something that looks more like it belongs on another planet than Earth

 

In the freezing, pitch-black waters off the coast of Antarctica, scientists have uncovered a deep-sea marvel that's straight out of a sci-fi movie: a newly discovered feather star with 20 arms and a strawberry-shaped body. Its official name?

Promachocrinus fragarius.

This strange creature was found lurking at a depth of 3,840 feet, where sunlight never reaches and life moves to a rhythm we barely understand. With its delicate, feather-like arms and alien form, this echinoderm is not just a bizarre beauty it's a living clue to the mysteries of deep-ocean evolution.

Feather stars belong to the same family as starfish and sea urchins, but this new species takes things to another level. Some of its arms are short and stubby, while others twist and wave like tentacles, helping it swim, feed, and navigate the ocean's most unforgiving environment.

What's especially fascinating is that Promachocrinus fragarius was hiding in plain sight part of a group once thought to include just one species. Now, researchers believe there are at least eight distinct species in this family, dramatically changing how we understand Antarctic biodiversity.

This discovery reminds us that even in the most remote, unexplored corners of Earth, life finds a way sometimes in the most surreal forms.

It's not just a weird creature it's a symbol of how much we still don't know about our own planet. 

[Credit: Discover the Universe] 

New discovery - spiritual rituals and social organization within the Pleistocene communities

 

In 1991, archaeologists made an unprecedented discovery in a remote region of Brazil - a massive collection of prehistoric rock art spanning over 8 miles within the Serra da Capivara mountains. Carbon dating revealed the drawings dated back approximately 12,600 years, offering a unique window into the late Pleistocene era in South America. The etchings depicted various fauna prominent during the last ice age, such as giant ground sloths and mastodons. This provided evidence that the environment was much different than the modern Amazon rainforest, dominated by now-extinct megafauna. The natural pigments used - hematite and manganese - indicated an early artistic tradition among the indigenous populations. Through analyzing recurring motifs and imagery, scientists gained new cultural insights. Hunting scenes and ceremonial depictions suggested spiritual rituals and social organization within the Pleistocene communities. Over time, the art cave became an important site for researchers seeking to reconstruct paleoenvironmental conditions and hunter-gatherer lifeways during the late Quaternary period.

74 Things That Blew Our Minds in 2022

 

By The Atlantic Science Desk

Where The Atlantic’s science, technology, and health reporters found wonder in a sometimes-sobering year

The writers on The Atlantic’s Science, Technology, and Health desks have learned a lot this year. Our coverage of the ongoing coronavirus pandemic has continued, but this year, more so than in 2020 and 2021, we’ve also had the chance to report on topics that have filled us with awe and delight. Though the past 12 months have not been free of concerns about infectious disease, climate change, and even nuclear war, we’ve embraced more fascination and curiosity in our coverage this year, and we wanted to share and reflect on some of the most compelling tidbits we’ve stumbled across. We hope you find these facts as mind-blowing as we did.

1. Days on the moon are hot enough to boil water, and nights are unfathomably cold, but at least one spot on the lunar surface stays a pleasant 63 degrees Fahrenheit.
2. Actually, snakes do have clitorises.
3. Scientists don’t know where the virus in the smallpox vaccine came from.
4. Sour or curdled milk is often perfectly safe to consume.
5. The bone of a mastodon named Fred preserved memories from its life 13,200 years ago.
6. The most common phrase on Facebook in several French-speaking countries is “Have a nice day!”
7. Most people with diabetes should not receive insulin as a first-, second-, or even third-line treatment.
8. There might not be a theoretical limit to the height from which a cat can fall and survive.
9. Beyond a certain temperature—as low as 95 degrees, by some estimates—fans do more harm than good.
10. About 10 percent of the bills introduced in Congress in the past two years have been titled with reverse-engineered acronyms, including the ZOMBIE Act.
11. The notes your doctor writes about you probably don’t look the same now as they did a year and a half ago.
12. It takes at least seven years to train the muscles and tendons in your elbow that will make you a great arm wrestler, according to the arm wrestler Jack Arias, who was in the 1987 arm-wrestling movie Over the Top with Sylvester Stallone.
13. American Express started making metal cards in 2004 because of an urban legend about its most exclusive card being titanium.
14. The first-of-its-kind electric Hummer weighs as much as an ambulance and accelerates like a Formula 1 race car.
15. Woodpeckers have small brains, which is why they can smash their heads against trees unharmed.
16. A toaster-size device inside a rover on Mars can convert Martian air, made almost entirely of carbon dioxide, into breathable oxygen.
17. Parrot theft is weirdly common.
18. Lactose-intolerant people have been throwing back dairy for thousands and thousands of years.
19. The provision in the Affordable Care Act that requires health insurance to cover contraception does not require coverage for vasectomies.
20. Pawpaws tend to stay green throughout their life cycle, so in order to tell if they’re ripe, you have to individually caress every fruit on a tree.
21. The metal that makes up a nickel has long been worth more than the coin itself.
22. The Presidential Fitness Test was developed because the federal government worried that postwar children were too soft to defeat communism when they grew up.
23. The iPhone is the only major Apple product that doesn’t support charging with the now-ubiquitous USB-C cable.
24. The oldest clam ever lived to 507.
25. The word sure was once pronounced more like syoor.
26. Some of YouTube’s earliest hits got popular thanks to “coolhunters,” a group of editors who individually picked videos for the site’s homepage.
27. In 1918, California conscripted children into a week-long war on squirrels.
28. Some baby cameras feature artificial intelligence that will recognize when your baby’s face is covered or when the baby has coughed.
29. Extreme heat and specific pressure conditions on WASP-96b, an exoplanet about 1,150 light-years from Earth, mean that rock can condense in the air like water does on Earth, producing clouds made of sand.
30. In 2021, a full quarter of single-family homes sold in America went to buyers with no intention of living in them, such as house flippers, landlords, Airbnb hosts, and other investors.
31. Apple has released 38 distinct models of the iPhone since 2007.
32. Slurpees and Icees are the exact same “frozen carbonated beverage,” sold under different trademarks.
33. The agricultural revolution is a myth.
34. Hypoallergenic dogs are also a myth.
35. Reindeers’ eyes change color—from blue to gold, and then back to blue again—twice a year to cope with the Arctic’s strange light schedule.
36. If current trends hold, half of the world’s population could be nearsighted by 2050.
37. A 2006 effort to automatically take down internet pornography by detecting repetitive noises ended up catching a lot of tennis videos.
38. Some minerals in rechargeable batteries can be recycled indefinitely.
39. Julius Caesar reportedly announced his conquest of Gaul via pigeon.
40. The Japanese makers of Hi-Chew candy were persuaded to push into the mainstream American market because of the candy’s enduring popularity among missionaries from the Church of Jesus Christ of Latter-day Saints who had returned home after time in East Asia.
41. Secondhand-smoke inhalation causes more than 41,000 deaths annually in the U.S., more than some flu seasons.
42. The Microsoft Excel World Championship: (1) exists, (2) streams on ESPN3, and (3) is legitimately exciting.
43. Saturn’s trademark rings will disappear in about 300 million years.
44. But, on the bright side, Neptune has rings too.
45. China’s zero-COVID policy may have been largely responsible for gas prices falling from a March peak to below $4 a gallon in August.
46. Polar bears in Southeast Greenland are homebodies.
47. The world’s best chess player, Magnus Carlsen, has, by one calculation, a 98 percent chance of losing and a 2 percent chance of drawing against the world’s best chess-playing computer program; victory is basically impossible.
48. Earlier this year, Moonbirds NFTs—basically colorful little pixelated owls—generated $489 million in trading volume in their first two weeks of existence.
49. In 1975, the average grocery store stocked 65 kinds of fruits and veggies. By 1998, that number had reached 345.
50. Octopuses all over the sea starve for years on end while brooding.
51. Government spending on climate change over the next decade could end up more than double what Democratic senators predicted for the Inflation Reduction Act.
52. Robusta coffee—whose taste has been likened to “rotten compost … with a hint of sulfur”—can actually be delicious.
53. Journals can be big business: One collector sold a diary from a 1912 Machu Picchu visitor and another by an 1868 Missouri River traveler for about $9,000 each.
54. There is such a thing as a reformed parasite.
55. In Wordle, just one correct letter in the right spot and one in the wrong spot can eliminate 96 percent of possible solutions.
56. A major obstacle to meeting the United States’ clean-energy goals is that we have to double the rate at which we build the giant cables that transmit power between regions.
57. Little kids who grew up amid intense COVID restrictions might have different microbiomes than those born several years earlier—and whether that’s good or bad is unclear.
58. Militaries are developing swarms of starling-size drones that will be able to fly and attack together with the use of artificial intelligence.
59. Psychedelics seem to quiet a network in our brain that is most active when we focus on ourselves.
60. The cryptocurrency exchange FTX, once valued at $32 billion before a spectacular collapse, used QuickBooks for accounting.
61. A product needs to be just 10 percent cocoa to be called “chocolate” by the FDA.
62. Gophers … might … farm?
63. While asleep, teeth-grinders can clench down with up to 250 pounds of force.
64. In 2021, 95 of the United States’ 100 most-watched telecasts were sporting events.
65. You can pay hundreds of dollars an hour for cow-hug therapy.
66. Male widow spiders will somersault into a female’s mouth to be cannibalized while they’re mating.
67. Ninety percent of people report having at least one memory in which they can see themselves as if watching a character in a movie.
68. Offices are designed to be inefficient.
69. Climate-minded architectural firms in Senegal are pushing the country to reclaim mud construction.
70. Rats can learn to play hide-and-seek, and they have fun doing it.
71. A cat kidney transplant costs $15,000.
72. The Apollo 11 moon lander will sit on the moon for millions of years because there’s no wind or water to erode it away.
73. Your smart thermostat mostly exists to help the utility company, not your wallet.
74. The cocaine-eating bear that died in 1985 and inspired the upcoming film Cocaine Bear is stuffed, mounted, and on display at a mall in Lexington, Kentucky.

https://cutt.ly/P2oEalb

Earth has been hiding a fifth layer in its inner core

 

Scientists say they've detected a new, mysterious layer at the center of our home planet. The discovery could unearth more about Earth's history.

By Donna Sarkar 

One of geology's basic principles is that the Earth is made up of four layers: the crust, the mantle, the outer core, and the inner core. But this may be squashed in light of a new study that suggests Earth actually has a distinct fifth layer that's been under our feet all along.

Researchers at the Australian National University (ANU) say that the new layer they uncovered is located within Earth's inner core. Deeper analysis of this discovery could help scientists better understand our planet's history and evolution.

A peek inside Earth

Approximately 4.6 billion years ago, the Earth formed. The story starts with the planet's interior or rocky core, which formed through the collision of heavy elements. The core, found at the center of the Earth, is made up of two parts. The outer layer, comprised of liquid iron alloy, is about 1,355 miles thick. The outer core is also thought to be responsible for Earth’s magnetic field. In contrast, the inner core is made up of solid iron alloy with a radius of 760 miles.

Next comes the mantle, which sits directly above the core. This layer is composed of mostly silicate rocks that are rich in magnesium and iron. The mantle has a thickness of about 1,793 miles, making it Earth's thickest layer. The thinnest and most brittle layer is the crust, however. It varies between 18.6 to 43.5 miles in thickness and forms the outermost layer of our home planet.

Earth's layers before the discovery of the innermost-inner core. The newest layer is situated just below the inner core.

OSweetNature/Shutterstock

The fifth layer

Scientists have long suspected that Earth's inner core was made of two layers. But it wasn't until ANU researchers took a closer look at what lies below that an “innermost inner core" was confirmed.

Their work revealed a distinct change in the structure of iron deep within the inner core at about 3,604 miles below the Earth's surface. You may recall from earlier that the inner core consists of solid iron alloy. This is due to high pressure deep within the Earth that stops the iron alloy from melting. But distinct structural changes were detected in this iron alloy that set apart the newly discovered innermost layer from the rest of the inner core.

According to Salon, this discovery led the researchers to believe that the change in structure may have been caused by an unknown, dramatic event early in Earth’s history. Further examination of this tiny layer may provide additional details around how our planets formed.

“The details of this big event are still a bit of a mystery, but we've added another piece of the puzzle when it comes to our knowledge of the Earths' inner core,” said the study’s lead author and researcher, Joanne Stephenson, in a statement.

Behind the scenes of the discovery

Seismic monitoring allows us to gain a better understanding of Earth's interior. This is made possible by measuring sound waves that are created by earthquakes and pass through Earth's layers. By analyzing how the different layers cause the sound waves to slow down, scientists can catch a glimpse of what lies below.

The recent discovery was made with the aid of a special search algorithm that researchers used to compare thousands of models of the inner core with decades worth of data on how long seismic waves take to travel through Earth. This data, gathered by seismograph stations all over the world, helped detect the changes in the structure of iron in the inner core. These findings helped confirm that Earth’s inner core has another layer.

Although this work is still being analyzed, the discovery of a new layer may pave the way for a new geological principle and prompt textbooks to be rewritten.

https://bit.ly/3sMZmIs

Plastic-eating caterpillars could save the planet

An escape from a shopping bag triggers an idea

MOST scientific research follows a logical progression, with one experiment following up on the findings of another. Every now and then, however, serendipity plays a part. Such is the case with a paper just published in Current Biology, which reveals to the world a moth capable of chewing up plastic.

The experiment behind the paper was inspired when Federica Bertocchini, an amateur beekeeper who is also a biologist at Cantabria University, in Spain, noticed caterpillars chewing holes through the wax in some of her hives and lapping up the honey. To identify them, she took some home in a plastic shopping bag. But when, a few hours later, she got around to looking at her captives she found the bag was full of holes and the caterpillars were roaming around her house.

After rounding them up, she identified them as larvae of the greater wax moth, a well-known pest of bee hives. On considering their escape from their shopping-bag prison, though, she wondered whether they might somehow be put to work as garbage-disposal agents.

Past attempts to use living organisms to get rid of plastics have not gone well. Even the most promising species, a bacterium called Nocardia asteroides, takes more than six months to obliterate a film of plastic a mere half millimetre thick. Judging by the job they had done on her bag, Dr Bertocchini suspected wax-moth caterpillars would perform much better than that.

To test this idea, she teamed up with Paolo Bombelli and Christopher Howe, two biochemists at Cambridge University. Dr Bombelli and Dr Howe pointed out that, like beeswax, many plastics are held together by methylene bridges (structures that consist of one carbon and two hydrogen atoms, with the carbon also linked to two other atoms). Few organisms have enzymes that can break such bridges, which is why these plastics are not normally biodegradable. The team suspected wax moths had cracked the problem.

One of the most persistent constituents of rubbish dumps is polyethylene, which is composed entirely of methylene bridges linked to one another. So it was on polyethylene that the trio concentrated. When they put wax-moth caterpillars onto the sort of film it had taken Nocardia asteroides half a year to deal with, they found that holes appeared in it within 40 minutes.

On closer examination, Dr Bertocchini and her colleagues discovered that their caterpillars each ate an average of 2.2 holes, three millimetres across, every hour, in the plastic film. A follow-up test found that a caterpillar took about 12 hours to consume a milligram of shopping bag. Such bags weigh about three grams, so 100 larvae might, if they spent half their lives eating, consume one in a month.

Whether releasing wax moths on the world’s surplus plastic really is sensible is not yet clear. For one thing, it has not been established whether the caterpillars gain nutritional value from the plastics they eat, as well as being able to digest them. If they do not, their lives as garbage-disposal operatives are likely to be short—and, even if they do, they will need other nutrients to thrive and grow. Another question is the composition of their faeces. If these turn out to be toxic, then there will be little point in pursuing the matter. Regardless of this, though, the discovery that wax-moth larvae can eat plastic is intriguing. Even if the moths themselves are not the answer to the problem of plastic waste, some other animal out there might be.

50,000 Year Old Lifeforms Were Found in an Abandoned Mine

• NASA Astrobiologist Penelope Boston has uncovered 50,000 year old microscopic organisms in the deep and extreme Naica caves.
• This discovery could, alongside existing knowledge and researcher, allow scientists to better understand early life on Earth and possible life on other planets.

CAVE LIFE

Penelope Boston, head of NASA’s Astrobiology Institute, recently made some fascinating discoveries deep in an abandoned zinc and lead mine in Mexico. This abandoned mine, the Naica caves, run 800 meters (2,625 feet) deep and are home to some punishing conditions. These unwelcoming qualities make the discovery of microbes deep below the Earth’s surface even more remarkable. Boston found 40 different strains of microbes and even some viruses in the depths of these caves.

The team was only able to work for twenty minutes at a time as the caves are extremely hot. They had to wear spacesuit knockoffs and be strapped with ice packs to endure the high temperatures, even for such a short period of time. To put it in perspective, the section of cave designated as the “cool” room was about 38C (100F).

The lifeforms found were unlike anything seen before on Earth. In fact, the nearest genetic relatives to this microscopic organisms still retain a 10% genetic difference. As The Guardianreports, that’s about the same as the difference between humans and mushrooms.

TOUGH LIL’ BUGGERS

The lifeforms have been evaluated and determined to be about 50,000 years old. This is a far leap from previous discoveries of life forms that were potentially a half a million years old, but surviving unforgiving conditions in rock or crystal, differing them from the organisms enduring from within ice and salt.

University of South Florida biologist, Norine Noonan stated, “Why are we surprised? As a biologist, I would say life on Earth is extremely tough and extremely versatile.” Such versatility allows for scientists to get a clearer view of the origins of life on planet Earth. Seeing how life endures such harsh conditions can clue us into how the earliest life on Earth survived when the entire planet was inhospitable to most lifeforms that we are familiar with.

Boston’s research has yet to be peer reviewed but she continues to do testing on the microbes. Data from living creatures combined with existing knowledge and what we can learn from ancient lifeforms in the form of fossils can give us a clearer view of Earth’s earliest life, as well as life on other seemingly inhospitable planets.

Scientists Say the Clock of Aging May Be Reversible

mpaired muscle repair in mice, left, compared with improved muscle regeneration seen after reprogramming. CreditThe Salk Institute for Biological Studies

By NICHOLAS WADE

At the Salk Institute in La Jolla, Calif., scientists are trying to get time to run backward.

Biological time, that is. In the first attempt to reverse aging by reprogramming the genome, they have rejuvenated the organs of mice and lengthened their life spans by 30 percent. The technique, which requires genetic engineering, cannot be applied directly to people, but the achievement points toward better understanding of human aging and the possibility of rejuvenating human tissues by other means.

The Salk team’s discovery, reported in the Thursday issue of the journal Cell, is “novel and exciting,” said Jan Vijg, an expert on aging at the Albert Einstein College of Medicine in New York.

Leonard Guarente, who studies the biology of aging at M.I.T., said, “This is huge,” citing the novelty of the finding and the opportunity it creates to slow down, if not reverse, aging. “It’s a pretty remarkable finding, and if it holds up it could be quite important in the history of aging research,” Dr. Guarente said.

The finding is based on the heterodox idea that aging is not irreversible and that an animal’s biological clock can in principle be wound back to a more youthful state.

Continue reading the main story

The aging process is clocklike in the sense that a steady accumulation of changes eventually degrades the efficiency of the body’s cells. In one of the deepest mysteries of biology, the clock’s hands are always set back to zero at conception: However old the parents and their reproductive cells, a fertilized egg is free of all marks of age.

Ten years ago, the Japanese biologist Shinya Yamanaka amazed researchers by identifying four critical genes that reset the clock of the fertilized egg. The four genes are so powerful that they will reprogram even the genome of skin or intestinal cells back to the embryonic state. Dr. Yamanaka’s method is now routinely used to change adult tissue cells into cells very similar to the embryonic stem cells produced in the first few divisions of a fertilized egg.

Scientists next began to wonder if the four Yamanaka genes could be applied not just to cells in glassware but to a whole animal. The results were disastrous. As two groups of researchers reported in 2013 and 2014, the animals all died, some because their adult tissue cells had lost their identity and others from cancer. Embryonic cells are primed for rapid growth, which easily becomes uncontrolled.

But at the Salk Institute, Juan Carlos Izpisua Belmonte had been contemplating a different approach. He has long been interested in regeneration, the phenomenon in which certain animals, like lizards and fish, can regenerate lost tails or limbs. The cells near the lost appendage revert to a stage midway between an embryonic cell, which is open to all fates, and an adult cell, which is committed to being a particular type of cell, before rebuilding the missing limb.

This partial reprogramming suggested to him that reprogramming is a stepwise process, and that a small dose of the Yamanaka factors might rejuvenate cells without the total reprogramming that converts cells to the embryonic state.

With Alejandro Ocampo and other Salk researchers, Dr. Izpisua Belmonte has spent five years devising ways to deliver a nonlethal dose of Yamanaka factors to mice. The solution his team developed was to genetically engineer mice with extra copies of the four Yamanaka genes, and to have the genes activated only when the mice received a certain drug in their drinking water, applied just two days a week.

The Salk team worked first with mice that age prematurely, so as to get quick results. “What we saw is that the animal has fewer signs of aging, healthier organs, and at the end of the experiment we could see they had lived 30 percent longer than control mice,” Dr. Izpisua Belmonte said.

Juan Carlos Izpisua Belmonte of the Salk Institute in La Jolla, Calif., has long been interested in regeneration, the phenomenon in which certain animals, like lizards and fish, can regenerate lost tails or limbs.CreditConcepcion Rodriguez Esteban/The Salk Institute for Biological Studies

The team also saw improved organ health in normal mice but, because the mice are still living, could not yet say if longevity was extended.

Dr. Izpisua Belmonte believes these beneficial effects have been obtained by resetting the clock of the aging process. The clock is created by the epigenome, the system of proteins that clads the cell’s DNA and controls which genes are active and which are suppressed.

When an egg develops into a whole animal, the epigenome plays a critical role by letting a heart cell, say, activate just the genes specific to its role but switching off all the genes used by other types of cells. This process lets the embryo’s cells differentiate into all the various types of cells required by the adult body.

The epigenome is also involved throughout life in maintaining each cell and letting it switch genes on and off as required for its housekeeping duties. The epigenome itself is controlled by agents that add or subtract chemical groups, known as marks, to its proteins.

Only in the last few years have biologists come to realize that the state of the epigenome may be a major cause of aging. If the epigenome is damaged, perhaps by accumulating too many marks, the cell’s efficiency is degraded.

Dr. Izpisua Belmonte sees the epigenome as being like a manuscript that is continually edited. “At the end of life there are many marks and it is difficult for the cell to read them,” he said.

What the Yamanaka genes are doing in his mice, he believes, is eliminating the extra marks, thus reverting the cell to a more youthful state.

The Salk biologists “do indeed provide what I believe to be the first evidence that partial reprogramming of the genome ameliorated symptoms of tissue degeneration and improved regenerative capacity,” Dr. Vijg said.

But he cautioned the fast-aging mice used in the study might not be fully representative of ordinary aging.

Dr. Guarente said it was more likely that the Yamanaka genes were not erasing the epigenomic marks directly, but rather were activating the genes which are responsible for the immense health and vitality of embryonic cells. This gene activation is a natural function of the Yamanaka factors. It is these embryonic pro-health genes that are rejuvenating the tissues in the mice, Dr. Guarente suggested, and causing changes in the epigenome through their activity.

Thomas A. Rando, an expert on stem cells and aging at Stanford, said that it should be possible in theory to uncouple the differentiation program and the aging process, and that “if that’s what’s happening, this is the first demonstration of that.”

Dr. Izpisua Belmonte said he was testing drugs to see if he could achieve the same rejuvenation as with the Yamanaka factors. The use of chemicals “will be more translatable to human therapies and clinical applications,” he said.