Now, scientists report in the journal Nature that genes in certain plants keep infections at a distance with the help of the clock as well. Twenty-two genes in the plant Arabidopsis, all connected to the plant’s ability to resist infection, were expressed only from the evening onward, reaching their highest point at the beginning of day.
The timing corresponds with the formation of spores in a funguslike pathogen that attacks the plant and results in a condition known as mildew disease. The disease weakens the plant and forms a repugnant layer of mildew.
“From what we know, the pathogen forms spores at night and disseminates them at the beginning of day, so that’s when the danger of infection is highest,” said Xinnian Dong, a biologist at Duke University and one of the study’s authors. During the day, when the pathogen does not attack, the genes were not expressed.
This is the first time scientists have made a connection between the circadian clock and pathogen resistance, Dr. Dong said. She believes that if we analyze the complexity of the relationship between pathogens and hosts, and their circadian rhythms, there may be practical applications. Pesticide treatments could be timed to have maximum impact, for instance. Or it may even be possible to determine ideal times for administering medications in humans, she said.
By Sindya N. Bhanoo, www.nytimes.com. Picture by Wei Wang and Xinnian Dong.
Reduced levels of omega-3 in mice had consequences on emotional behaviors, French investigators say. The Institut National de la Santé et de la Recherche Medicale and the French National Institute for Agricultural Research say the imbalanced ratio between omega-6 and omega-3 increased continuously over the course of the 20th century.
The team studied mice fed a permanent diet unstable in omega-3 and omega-6 fatty acids. They found omega-3 deficiency disturbed neuronal communication and the neuronal dysfunction was accompanied by depressive behaviors among the malnourished mice.
"Our results can now corroborate clinical and epidemiological studies which have revealed associations between an omega-3/omega-6 imbalance and mood disorders. To determine if the omega-3 deficiency is responsible for these neuropsychiatric disorders additional studies are, of course, required."
The results give the first biological components of an explanation for the observed correlation between omega-3 poor diets -common in the industrialized world- and mood disorders such as depression.
By UPI.com. No credits for picture.
Conservationists in Egypt have discovered a new species of wolf, which shares DNA with Indian and Himalayan cousins. The "Egyptian jackal", as it's known, is not jackal at all, despite the visual similarities with the golden jackal. The discovery throws light on how wolf species migrated through Africa and Europe - proving that grey wolves emerged in Africa about three million years before they spread to the northern hemisphere.
As long ago as 1880 it had been noticed that the Egyptian jackal looked suspiciously like the grey wolf, and some biologists in the 20th century, studying skulls, made the same observation. However, the creature retained its name. Now, the difference has been formalised.
The investigation is published in the journal PLOS One, with author David Macdonald telling Wired.co.uk in an email: "A wolf in Africa is not only important conservation news, but raises fascinating biological questions about how the new African wolf evolved and lived alongside the real golden jackals."
Eli Rueness of the University of Oslo, who also contributed to the study, added: "We could hardly believe our own eyes when we found wolf DNA that did not match anything." However, the new species' DNA is quite similar to wolves found 2,500 kilometres away in the highlands of Ethiopia.
Professor Claudio Sillero, who has worked in Ethiopia for more than two decades, told Wired.co.uk: "This discovery contributes to our understanding of the biogeography of Afroalpine fauna, a group of species with African and Eurasian ancestry which evolved in the relative isolation of the highlands of the Horn of Africa. Rare Ethiopian wolves are themselves a recent immigrant to Africa, and separated from the grey wolf even earlier than the newly discovered African wolf."
By Duncan Geere in Wired.co.uk. Picture by www.muyinteresante.es.
Homo sapiens are an terribly vain species. We love to exhibit our big brains and our opposable thumbs — and we wouldn't be good for much without them. But there's one human attribute that doesn't get enough attention: the ability to throw things really, really far. According to a new study published in the journal Evolution and Human Behavior, not only was a good arm essential for our early survival, it is also an innate talent, deep into us from the moment of birth.
Humanity's rapid rise to the top on a planet with lots of competing species was never a sure thing. We're slow, we're soft and we have good teeth but they're nothing compared with those of the big cats or the great apes. We needed to kill the predators from a safe distance — first with rocks and later with spears.
"The ability to throw great distances was not a small thing," says Geoffrey P. Bingham, an experimental psychologist at Indiana University. "We are the only animals with that talent." Before we pick something up, we begin tensing muscles in the arm and hand to accommodate the anticipated weight. If that weight is finally less than we guessed, we bring more muscle power to the job than is necessary, making the object feel light.
Projectile selection is a talent that some people have in greater abundance than others. Everyone, however, is born with the basic skill set, and all of us get better with practice. "You acquire the ability at the same time you're learning to throw," says Bingham. That was very good news for your most distant ancestors — and very bad news for a long-ago mastodon.
By Jeffrey Kluger, TIME Magazine. Picture by The Bridgeman Art Library / Getty Images.
Somewhere out —about 13.2 billion light-years away— the Hubble Space Telescope has recently discovered a magnificent red, amorphous mass. It's a galaxy —or it was— but it is not beautiful, it is magnificently old.
The newly discovered star block — a hundred times smaller than our Milky Way — was formed just 480 million years after the 13.7 billion-year-old universe was born, making it the oldest galaxy. As such, it provides astronomers with a look at the universe in a phase when small galaxies were being formed out of hot gas, only to disappear —leaving the skies free for the immense and mature galaxies that would come along later.
Its size, shape and the era in which it formed all suggest that it began its life as a mass of gas trapped in a pocket of dark matter. In those early days, stars took about 10 times as long to form as they did in later epochs. They were typically part of the blue star class — extremely hot stars, heavy on helium, oxygen and nitrogen. Blue stars last only a few million years before ending their lives in massive explosions.
Soon, stabler stars began to form in much larger galaxies as the universe rapidly cooled. Between 480 million and 700 million years after the Big Bang — when UDFj-39546284 was still in the skies — star formation accelerated. It was then when spiral galaxies and the other glorious formations that define the modern universe appeared.
It is not certain what forces drove those changes. The Hubble Space Telescope has a lot more work to do before more answers are revealed — and a lot more images of thousands of other galaxies to analyze.
By Jeffrey Kluger, TIME Magazine. Picture by NASA.
In his book The New Evolution Diet Arthur De Vany, who used to work as a professor at the University of California, argues if we really want to be healthy, we should follow Paleolithic humans' lifestyle. He thinks we should eat low-carb food and exercise intensely in order to control insulin.
De Vany has become the grandfather of the growing Paleo movement, a health philosophy. Their slogan could be reduced to “modern life is simply alien to our genes”. We should return to eat wild animals, fresh produce, eliminate grains and milk, and exercising in intense bursts.
There's no doubt that obesity, heart disease and diabetes are a big problem. And there's no doubt that this is a direct result of our sedentary lives. But there was no Paleolithic "lifestyle." Life in Ice Age Europe was different from life on the African savanna, requiring different diets, behaviors and genetic adaptations. Human DNA evolution didn't stop then. In fact, we're still evolving.
Human genetic adaptations actually increased around 40,000 years ago when we developed technology and became more sophisticated, cooperative thinkers. At least 3,000 significant genetic adaptations have occurred since, including the ability of some Africans, central Asians and northern Europeans to tolerate lactose as adults.
The problem, of course, is that even if De Vany and the other paleo believers are right, there's no going back to the world that existed 40,000 years ago. There's not enough wild animals to feed us all, and our genes don't care how healthy we are, but whether we reproduce or not. From an adaptation perspective, people today are doing really well: there are several billion of us.
In a new study, a Labrador learned how to sniff out cancer and was able to detect colon cancer. It was nearly as efficient as a colonoscopy. The dog was given breath samples of 306 patients, collected before they received colonoscopies; 48 patients had recently been diagnosed with cancer, and the other 258 were either suffering from another colorectal problem or had survived cancer, or were healthy.
The investigators found that the dog was at least 95% as competent at identifying cancer as colonoscopy when smelling breath samples. But the most important advantage of this technique is that the dog was especially good at detecting early-stage cancer, and could discern polyps from malignancies, which colonoscopies can't do. Detection of early-stage cancers is crucial in bowel cancer diagnosis because surgery can cure almost 90% of patients at an early stage.
Although we will not see the routine use of scent dogs in cancer screening (they're too expensive), this investigation suggests that other methods could be developed to pick up the same scent: a specific cancer smell exists and may become very effective tools.
From TIME Magazine, by Meredith Melnick. Picture by Juliet White/Photographer's Choice via Getty Images.
