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Martin Wolff's List: Biology
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Feb 01, 10
Marshall W. Nirenberg, a biologist who deciphered the genetic code of life, earning a Nobel Prize for his achievement, died January 15, 2010, at his home in Manhattan.
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In solving the genetic code, Dr. Nirenberg established the rules by which the genetic information in DNA is translated into proteins, the working parts of living cells. The code lies at the basis of life, and understanding it was a turning point in the history of biology.
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The achievement, in a critical experiment in 1961, was the more remarkable because Dr. Nirenberg was only 34 at the time and unknown to the celebrated circle of biologists, led by Francis Crick, who had built the framework of molecular biology.
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Jan 26, 10
As the mercury plunges to its annual lows, those of us at higher latitudes retreat to cozy shelters. We might sympathize with the birds and the squirrels that endure the subfreezing cold outside and fill some feeders, but we don’t give any thought to smaller, less appealing creatures — the insects and spiders, for instance, that inhabited the backyard or woods in the summer. They will re-emerge in the spring, so somehow they must make it through the bitter cold. How do these animals survive the deep freeze without the benefit of fur or feathers?
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The threat to life at low temperatures is not really cold, but ice. With cells and bodies composed mostly of water, ice is potentially lethal because its formation disrupts the balance between the fluids outside and inside of cells, which leads to their shrinkage and irreversible damage to tissues.
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Jan 24, 10
It is not a perfect situation, the relationship between coyote tobacco and hawkmoths.
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Sure, the hawkmoth does a good job of pollinating the plant, Nicotiana attenuata, which grows in the Western United States and flowers at night. But the hawkmoth has this habit of leaving behind its eggs, which develop into caterpillars that like nothing better than to eat the plant.
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The two chimpanzee species, the common chimp and the bonobo, may both be closely related to humans, yet they are rather different from each other behaviorally. Chimpanzee society is dominated by males, while among bonobos, females are dominant and there is less aggression. One illustration of the differences cited by scientists is that chimpanzees occasionally conduct group hunts for other primates while bonobos do not. The hunts, for tree-dwelling monkeys, seem to be more about male bonding and dominance than about nutrition, so it makes sense that the bonobos don’t do it. Except that new research shows that in fact they do.
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A new study by researchers at Cardiff University reveals that wild birds foraging on invertebrates contaminated with environmental pollutants, show marked changes in both brain and behaviour: male birds exposed to this pollution develop more complex songs, which are actually preferred by the females, even though these same males usually show reduced immune function compared to controls.
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There are two ways that stem cells can lead to treatments for diseases. Making replacement tissues for ailing organs is the direct way. But many scientists say the biggest impact of the new cells will be on the indirect way: using the cells to learn about diseases and then applying that knowledge to develop conventional drugs. Using the new technique, scientists could take a skin cell from a person with a certain disease and generate stem cells. Those cells could then be turned into other cells, allowing the scientists to look at neurons from a person with Alzheimer’s disease, say, or heart cells from a person with heart failure.
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Herons nesting in the wetlands of southeast Chicago are still being exposed to chemicals banned in the U.S. in the 1970s, a research team reports. The chemicals do not appear to be affecting the birds’ reproductive success, however. University of Illinois veterinary biosciences scientist Jeff Levengood led the study. Levengood, a wildlife toxicologist at the Illinois Natural History Survey, said that chemicals banned 30 years ago for their deleterious effects on wildlife are still showing up in the offspring of black-crowned night-herons in a Chicago wetland... The Lake Calumet birds appear to be picking up the contamination primarily from Lake Michigan by means of an invasive fish, the alewife.
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A record number of the migrating animals have been killed by hunters or rounded up and sent to slaughterhouses by park employees. The bison are being killed because they have ventured outside the park into Montana and some might carry a disease called brucellosis, which can be passed along to cattle.
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Al Hicks was standing outside an old mine in the Adirondacks, the largest bat hibernaculum, or winter resting place, in New York State. It was broad daylight in the middle of winter, and bats flew out of the mine about one a minute. Some had fallen to the ground where they flailed around on the snow like tiny wind-broken umbrellas, using the thumbs at the top joint of their wings to gain their balance. All would be dead by nightfall.
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Much has been made about the waggle dance, a fox trot of sorts that foraging honeybees do to tell their hive mates when they have found a good food source. The dance — a zigzagging figure eight maneuver performed in the hive — provides cues as to the direction and distance of the trove of flowers so the other bees can locate it. There is only one problem: Many bees seem to ignore the information.
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In the scientific equivalent of the board game Clue, teams of biologists have been sifting spotty evidence and pointing to various culprits in the widespread vanishing of harlequin frogs. It looked as if one research team was a winner in 2006 when global warming was identified as the “trigger†in the extinctions by the authors of a much-cited paper in Nature. The researchers said they had found a clear link between unusually warm years and the vanishing of mountainside frog populations. Other researchers have been questioning that connection.
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Amazon river dolphins, or botos, have a curious habit: occasionally one will grab some river grass or a rock in its mouth and pop its head above the surface, showing its prize for all to see. This ritual behavior has been noted for years, and most people who saw it assumed it was just a form of play.
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In the tropics, bats eat so many bugs that they put a significant damper on the number of bugs crawling on plants, two studies report in the journal Science. Bug-eating bats are thus a boon to farmers there, reducing the need for insecticides.
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He explained that at 100 to 500 hertz, black drum mating calls travel at a low enough frequency and long enough wavelength to carry through sea walls, into the ground and through the construction of waterfront homes like the throbbing beat in a passing car.
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The ultraviolet portion of the sun’s rays has a bad reputation, and among the different types of ultraviolet, UVB has about the worst. These shorter-wavelength rays cause sunburn and cancer and can harm the retinas of humans and other mammals. But among a certain species of jumping spider, UVB serves a useful purpose, researchers from the National University of Singapore say.
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When human cells run out of energy, a result is fatigue, and exercise grinds to a halt until those sources are replenished. Dogs are different, in particular the sled dogs that run the annual Iditarod Trail Sled Dog Race in Alaska. This is a grueling 1,100-mile race, and studies show that the dogs somehow change their metabolism during the race.
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The research is part of the human microbiome project, microbiome meaning the entourage of all microbes that live in people. The project is in its early stages but has already established that the bacteria in the human microbiome collectively possess at least 100 times as many genes as the mere 20,000 or so in the human genome. Since humans depend on their microbiome for various essential services, including digestion, a person should really be considered a superorganism, microbiologists assert, consisting of his or her own cells and those of all the commensal bacteria. The bacterial cells also outnumber human cells by 10 to 1, meaning that if cells could vote, people would be a minority in their own body.
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For a creature that has to cope with several kinds of predators, it can help to have a diversified defensive strategy — adjusting appearance or behavior depending on the enemy. Because chameleons are famous for the ability to adjust appearance, might they have such a predator-specific approach to defending themselves? In a paper in Biology Letters, researchers describe one chameleon that does.
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