Arsenic-Eating Bacteria-Six Essential Chemicals for Life

Phosphorus is one of six chemical elements that have long been thought to be essential for all Life As We Know It. The others are carbon, oxygen, nitrogen, hydrogen and sulfur.

While nature has been able to engineer substitutes for some of the other elements that exist in trace amounts for specialized purposes — like iron to carry oxygen — until now there has been no substitute for the basic six elements. Now, scientists say, these results will stimulate a lot of work on what other chemical replacements might be possible. The most fabled, much loved by science fiction authors but not ever established, is the substitution of silicon for carbon.

Phosphorus chains form the backbone of DNA and its chemical bonds, particularly in a molecule known as adenosine triphosphate, the principal means by which biological creatures store energy. “It’s like a little battery that carries chemical energy within cells,” said Dr. Scharf. So important are these “batteries,” Dr. Scharf said, that the temperature at which they break down, about 160 Celsius (320 Fahrenheit), is considered the high-temperature limit for life.

Arsenic sits right beneath phosphorus in the periodic table of the elements and shares many of its chemical properties. Indeed, that chemical closeness is what makes it toxic, Dr. Wolfe-Simon said, allowing it to slip easily into a cell’s machinery where it then gums things up, like bad oil in a car engine.

via Arsenic-Eating Bacteria Force New Thinking on What Constitutes Life – NYTimes.com.

Breast Milk Sugars Give Infants a Protective Coat

three researchers at the University of California, Davis — Bruce German, Carlito Lebrilla and David Mills. They and colleagues have found that a particular strain of bacterium, a subspecies of Bifidobacterium longum, possesses a special suite of genes that enable it to thrive on the indigestible component of milk.

This subspecies is commonly found in the feces of breast-fed infants. It coats the lining of the infant’s intestine, protecting it from noxious bacteria.

Infants presumably acquire the special strain of bifido from their mothers, but strangely, it has not yet been detected in adults. “We’re all wondering where it hides out,” Dr. Mills said.

via Breast Milk Sugars Give Infants a Protective Coat – NYTimes.com.

via Breast Milk Sugars Give Infants a Protective Coat – NYTimes.com.

Blogging the Periodic Table: Promethium, Uranium Stole It’s Fire

A century ago, so few natural elements remained undiscovered, and so many scientists were scouring the Earth for the honor of finding them, that disputes over who discovered what first became commonplace. Scientists repeatedly shot down false claims, and acrimony could linger for years, even on a national level. In one dispute between French scientists and a team of Danish and Hungarian scientists, a French magazine sniffed that the whole thing “stinks of Huns,” as if Attila himself had discovered the element.

[But news of Promethium’s Discovery] in 1947, was strangely anticlimactic. Three scientists from Oak Ridge National Laboratory made the announcement at a scientific meeting that year—but revealed that theyd actually discovered it two years before and had sat on it. They had said nothing partly because of security restrictions at a national lab, but they also knew the delay wouldn’t matter: No one else was looking for the element. The media gave the announcement unenthusiastic coverage, calling the new element “not good for much.” Science had at last discovered the final natural element, completing the periodic table after almost a century of work, and few seemed to care. What happened?

Uranium and plutonium happened. Continue reading