Two groups of researchers seem to have solved the mystery of how and when the first human settlers spread out through the Pacific Islands. One group studied the evolution of a stomach bacteria while the other examined the evolution of language, but both came up with remarkably congruous results. The evolutionary trajectory implied by words and bugs begins with an initial migration from Taiwan 5,000 years ago, with a first wave of people spreading to the Philippines and a second to western Polynesia [Wired News].
In the bacterial study, researchers took stomach samples from people native to Taiwan, Australia, Melanesia, Polynesia and New Guinea. They measured genetic variation in Helicobacter pylori, a common gut microbe that traveled with humans when they first left Africa more than 60,000 years ago…. They found that the [bacteria] from people’s guts in Polynesia and Melanesia–islands stretching from New Caledonia all the way to Samoa–were genetically similar to the samples from aboriginal people in Taiwan. What’s more, the Taiwanese bacteria had more genetic diversity than other populations [The Scientist]. Because genetic mutations accumulate over time, these results indicate that the early Taiwanese people were the ancestors of the other groups that split off over the centuries.
(more…)
A tiny worm has developed a compelling system for survival: It avoids trouble and sickness. A single genetic change in the tiny worm Caenorhabditis elegans compels some worms to stay away from harmful bacteria and others to eat the microorganisms [Science News]. While some researchers believe that the healthier worms also have some innate immunity to the bacteria, a new study shows definitively that a gene controls their behavior and keeps them from ingesting substances that will do them harm.
As reported in Science [subscription required], researchers first noted that a Hawaiian population of C. elegans had less resistance to harmful bacteria than the standard laboratory worms. A genetic study revealed that the Hawaiian worms have a different version of a gene called npr-1, which causes them to produce less of a protein that senses signals from neurons. When researchers tweaked the standard lab worms to have the same npr-1 mutation, those worms were also more susceptible to infection, indicating that the single gene was somehow responsible.
(more…)
It’s entirely possible that researchers may have detected the first ever evidence of extraterrestrial life. Researchers who spent seven years studying the atmosphere of Mars say they glimpsed discrete plumes of methane gas rising from the surface of the planet in 2003, which could have been produced by bacteria living deep underground. On Earth, a class of bacteria known as methanogens breathes out methane as a waste product [The New York Times].
Before the public could get too excited, the researchers noted that that the biological explanation is just one of two possibilities–there’s also geological processes to consider. The methane could have been produced by geothermal chemical reactions involving water and heat like those in the hot springs of Yellowstone…. [N]o signs of recent volcanism, or even any hot spots, have been spotted on Mars [The New York Times], but ancient volcanic activity could have left methane deposits trapped underground, and puffs of that gas could be routinely released. Finally, the source could be a process known as serpentinisation that occurs at low temperatures and occurs when rocks rich in the minerals olivine and pyroxene react chemically with water, releasing methane [BBC News].
(more…)
The germ-fighting power of bleach lies in its ability to unravel cellular proteins, according to a new study. Researchers at the University of Michigan report that the active ingredient in bleach, hypochlorous acid, irreparably alters the three-dimensional structure of proteins in living cells—to fatal effect. They also found that some bacteria possess a special protein that can somewhat counter the ravages of hypochlorous acid. The findings clear up a hitherto murky understanding of how the common household cleaner does its job. “Everyone knew that bleached worked, and that was enough,” says [researcher Ursula Jacob]. “Few really cared how it worked” [Nature News].
In fact, Jacob’s team didn’t set out to answer that question either. They were studying a bacterial protein known as heat shock protein 33 (Hsp33) that helps other proteins maintain their proper shapes. Hsp33 is activated in times of stress, such as when the bacteria is exposed to high temperatures. “At high temperatures, proteins begin to lose their three-dimensional molecular structure and start to clump together and form large, insoluble aggregates, just like when you boil an egg,” said study lead author Jeannette Winter… Like a boiled egg, those proteins can never revert to their previous state, and the stressed cells eventually die [LiveScience.com].
(more…)
A genetic analysis of two 9,000-year-old human skeletons found off the coast of Israel reveal that the Neolithic people were infected with tuberculosis, making them the earliest known TB cases to be confirmed with genetic testing. The bone discovery contradicts the long-held theory that human TB evolved from cattle strains around the time of animal domestication, says [study coauthor] Helen Donoghue…. Rather, high population densities could have made it easier for the disease to spread [New Scientist].
The skeletons of a mother and child were found amidst other artifacts of a Neolithic village, called Atlit-Yam, which is now covered by the Mediterranean Sea. A roughly 25-year–old mother had apparently passed on the bacterial infection to her 1-year–old child, after which they both died and were buried together…. Salt water, sand and clay had covered the bodies, providing excellent conditions for bone preservation. Atlit-Yam was located within a coastal marshland before its immersion by the rising ocean [Science News].
(more…)
Researchers have invented a new tool in the fight against antibiotic-resistant “superbugs” that are becoming a growing health threat worldwide: a nanoscale device that shows instantly whether new drugs can kill the bacteria. The device uses tiny springboards coated in bacteria proteins, which are then exposed to an antibiotic; if the drug effectively binds to the proteins, the springboard bends.
[D]rug resistant superbugs are becoming more common and increasingly causing problems outside of hospitals. So [lead researcher Rachel] McKendry and colleagues want to find speedier ways to screen new potential antibiotics. They say their new nanoscale device can help, revealing in minutes whether an antibiotic is potent enough to kill bacteria [New Scientist]. Typically, researchers test new antibiotics by growing a bacterial culture and then applying the antibiotics, but it can take days for the cultures to grow.
(more…)
Almost two miles beneath the earth’s surface in a South African goldmine, researchers have found a new species of bacteria that lives in total isolation from any other organism. The discovery offers the first known example of an ecosystem that isn’t a complex web of different life forms, but is instead hosts just one self-sufficient species. The bacteria, Desulforudis audaxviator, is able to extract all its food and energy directly from the surrounding water and rocks, and researchers say the independent microbe offers a glimpse of the shape life could take on other planets.
Researchers wanted to know what organisms were living in the mine’s deep fissures, a habitat completely devoid of light and oxygen, so they analyzed the genes present in a water sample to determine what species lived there. They filtered a total of 5,600 liters of mine water to get their sample, which gave other microbes plenty of opportunities to make themselves known. Of the DNA sequences obtained from this sample, over 99.9 percent were from this single species; over half of the remainder were obvious contaminants from their own lab [Ars Technica].
(more…)
Researchers have discovered new strains of Pseudomonas bacteria that feed on the PET plastic used in drink bottles, and turn it into a more valuable, biodegradable form of plastic. The discovery suggests a way to keep billions of pounds of discarded plastic out of landfills; a 2006 study [pdf] found that less than 25 percent of PET plastic is currently recycled because the industry doesn’t have enough use for the end product.
Getting high-quality material — such as plastics suitable for packaging food or beverages —- back out of recycled plastic is more expensive than making virgin PET, so most plastic bottles are recycled into lower-grade, and less valuable, plastic. But there’s only so much demand for lower-grade plastics, says microbiologist and coauthor Kevin O’ Connor…. “The problem is that the market [for recycled PET] is saturated” [Science News].
(more…)
A “sustainable chemical” company called Genomatica has developed a way to use sugar and genetically engineered bacteria to produce a common industrial chemical that’s usually produced using petroleum, and which is found in everything from Spandex to car bumpers. By using sugar from sugar cane as a feedstock, industrial chemical companies can get a cheaper alternative to petroleum-derived chemicals, while investing in processes that are less polluting and nontoxic, said Genomatica CEO Chris Gann [CNET].
Genomatica produces the chemical, 1,4-butanediol (BDO), by feeding pure glucose derived from sugarcane to E. coli bacteria, which has been engineered to produce BDO. “We have engineered the organism such that it has to secrete that product in order for it to grow,” says [company president] Christophe Schilling…. “The interests of the organism are aligned with our interests: It grows faster when it produces more” [Scientific American].
(more…)
A new batch of genetically engineered bacteria may be able to slash the cost of producing ethanol from tough materials like wood chips and switchgrass, pushing the young ethanol industry closer to its goal of creating commercially competitive alternative fuel from the waste products of farming and forestry. Ethanol from cellulose, the kind of sugar in the likes of cornstalks and sawdust, is being promoted as an environmentally friendly alternative to fossil fuels, with the advantage that it does not use food crops such as corn as raw materials [Reuters].
Ethanol from corn and sugarcane is relatively easy to produce, because yeast convert the readily accessible sugars and starches into ethanol. Cellulose presents a stiffer challenge. Cellulose fibers contain longer polysaccharide chains than those found in starches and surround them with lignin and hemicelluose, which hold the fibers together and provide strength. This makes them tough—tough enough to hold up a tree—but it also makes the sugars within very hard to access [Ars Technica].
(more…)
A new study has shown that salmonella bacteria use a surprising tactic when they attack a mammal’s intestinal system. A small percentage of the bacteria mount a kamikaze mission from which they’ll never return, but which helps allows the rest of the salmonella bacteria to thrive, spreading the infection and ultimately benefiting the species.
Researchers found that in the early stage of an infection, about 15 percent of the salmonella go on a suicide mission, invading the intestinal walls. There, the immune system handily wipes them out. But that also sets off a wider immune response that, while attacking the salmonella within the gut, also wipes out many other micro-organisms. “This inflammation removes many of the competitors, so the second group which waited outside can proliferate,” said [lead researcher] Martin Ackerman [The New York Times].
(more…)
Ninety years after the discovery of the first antibiotic, penicillin, researchers have found an entirely new tactic in the fight against bacteria that cause infectious diseases. Instead of hunting for new ways to kill bacteria, researchers have developed a drug, called LED209, that disarms them, preventing them from releasing the toxins that cause illness.
“The sensors in bacteria are waiting for the right signal to initiate the expression of virulent genes,” [said lead researcher] Vanessa Sperandio…. “Using LED209, we blocked those sensing mechanisms and basically tricked the bacteria to not recognize that they were within the host” [Reuters]. The new technique, which has only been demonstrated in mice so far, could be a boon for researchers who are worried about creating more antibiotic-resistant “superbugs.”
(more…)
In a salty hot spring near Mono Lake, California, researchers have found two new species of bacteria that use arsenic for photosynthesis, and require no oxygen to fuel the process. Researchers say the bacteria may be similar to those that existed on primordial Earth where oxygen was scarce, and may illustrate an important stage of how early life developed in mineral-rich waters over 2 billion years ago.
Arsenic is well-known for its toxicity; it was used so often as tool for homicide in the 1800s that it earned the nickname “king of poisons” [The Scientist]. Yet the newly discovered bacteria can not only tolerate the element, they require it to survive. One of the first steps most organisms perform in photosynthesis is to split water molecules, creating oxygen. Oxygen donates energy in the form of electrons to other molecules, setting off a chain reaction that eventually results in the building of sugars for the organism’s own food. For the red and green bacteria found in Mono Lake, arsenic plays the role of oxygen [Science News].
(more…)
A new study may burst the bubble of dinosaur buffs by contradicting an exciting announcement of three years ago: what was earlier identified as soft tissue preserved in the thigh bone of a Tyrannosaurus fossil is actually just modern-day bacteria, researchers say.
The new study challenges the work done by paleontologist Mary Schweitzer, who garnered headlines in 2005 for reporting in the journal Science [that her team] had found the remains of blood vessels inside the fossils unearthed in the Hell Creek Formation in Montana. Finding tissue preserved at least 65 million years shocked paleontologists who believed any such traces were lost forever [USA Today].
(more…)
After over 14 weeks of looking, Food and Drug Administration officials investigating the salmonella outbreak finally have something to go on. In a produce distribution plant in McAllen, Texas they discovered a single pepper tainted with the same strain of salmonella, called salmonella Saintpaul, that has sickened over 1,200 people since April.
The FDA inspectors say the bacteria found on the pepper in McAllen is a genetic match with the samples taken from sick patients. But Monday’s discovery, the equivalent of a fingerprint, doesn’t solve the mystery: Authorities still don’t know where the pepper became tainted — on the farm, or in the McAllen, Texas, plant, or at some stop in between, such as a packing house…. Still, “this genetic match is a very important break in the case,” said Dr. David Acheson, the Food and Drug Administration’s food safety chief [AP].
(more…)
