Chickens ‘One-Up’ Humans in Ability to See Color
February 17, 2010
Researchers at Washington University School of Medicine in St. Louis have peered deep into the eye of the chicken and found a masterpiece of biological design.
Scientists mapped five types of light receptors in the chicken’s eye. They discovered the receptors were laid out in interwoven mosaics that maximized the chicken’s ability to see many colors in any given part of the retina, the light-sensing structure at the back of the eye.
“Based on this analysis, birds have clearly one-upped us in several ways in terms of color vision,” says Joseph C. Corbo, M.D., Ph.D., senior author and assistant professor of pathology and immunology and of genetics. “Color receptor organization in the chicken retina greatly exceeds that seen in most other retinas and certainly that in most mammalian retinas.”
Corbo plans follow-up studies of how this organization is established. He says such insights could eventually help scientists seeking to use stem cells and other new techniques to treat the nearly 200 genetic disorders that can cause various forms of blindness.
Chemists Discover How Antiviral Drugs Bind to and Block Flu Virus
February 4, 2010
Antiviral drugs block influenza A viruses from reproducing and spreading by attaching to a site within a proton channel necessary for the virus to infect healthy cells, according to a research project led by Iowa State University’s Mei Hong and published in the Feb. 4 issue of the journal Nature.
Hong, Iowa State’s John D. Corbett Professor of Chemistry and an associate scientist for the U.S. Department of Energy’s Ames Laboratory, said the findings clarify previous, conflicting studies and should pave the way to development of new antiviral drugs against influenza viruses, including pandemic H1N1.
Two papers published by Nature in 2008 came to different conclusions about where the antiviral drug amantadine binds to a flu virus and stops it from infecting a healthy cell. A paper based on X-ray studies concluded the drug attached to the lumen of the proton channel, the area inside the channel, and stopped the virus by blocking the channel. Another paper based on solution nuclear magnetic resonance (NMR) technology concluded the drug attached to the surface of the virus protein near the proton channel and stopped the virus by indirectly changing the channel structure.
Hong’s research concluded that when amantadine is present at the pharmacologically relevant amount of one molecule per channel, it attaches to the lumen inside the proton channel. But the paper also reports that when there are high concentrations of
In Bats and Whales, Convergence in Echolocation Ability Runs Deep
January 27, 2010
Only some bats and toothed whales rely on sophisticated echolocation, in which they emit sonar pulses and process returning echoes, to detect and track down small prey. Now, two new studies in the January 26th issue of Current Biology, a Cell Press publication, show that bats’ and whales’ remarkable ability and the high-frequency hearing it depends on are shared at a much deeper level than anyone would have anticipated — all the way down to the molecular level.
The discovery represents an unprecedented example of adaptive sequence convergence between two highly divergent groups and suggests that such convergence at the sequence level might be more common than scientists had suspected.
“The natural world is full of examples of species that have evolved similar characteristics independently, such as the tusks of elephants and walruses,” said Stephen Rossiter of the University of London, an author on one of the studies. “However, it is generally assumed that most of these so-called convergent traits have arisen by different genes or different mutations. Our study shows that a complex trait — echolocation — has in fact evolved by identical genetic changes in bats and dolphins.”
Bacteria Are More Capable of Complex Decision-Making Than Thought
January 20, 2010
It’s not thinking in the way humans, dogs or even birds think, but new findings from researchers at the University of Tennessee, Knoxville, show that bacteria are more capable of complex decision-making than previously known.
The discovery sets a landmark in research to understand the way bacteria are able to respond and adapt to changes in their environment, a trait shared by nearly all living things, and it could lead to innovations in fields from medicine to agriculture.
In the long-term, the researchers think that scientists will be able to take the findings, published in theProceedings of the National Academy of Sciences, and use them to tailor medicines in new ways to fight harmful bacteria or to find enhanced ways to use bacteria in agricultural or other applications.
Bigger Not Necessarily Better, When It Comes to Brains
November 18, 2009
Tiny insects could be as intelligent as much bigger animals, despite only having a brain the size of a pinhead, say scientists at Queen Mary, University of London.
“Animals with bigger brains are not necessarily more intelligent,” according to Lars Chittka, Professor of Sensory and Behavioural Ecology at Queen Mary’s Research Centre for Psychology and University of Cambridge colleague, Jeremy Niven. This begs the important question: what are they for?
Research repeatedly shows how insects are capable of some intelligent behaviours scientists previously thought was unique to larger animals. Honeybees, for example, can count, categorise similar objects like dogs or human faces, understand ’same’ and ‘different’, and differentiate between shapes that are symmetrical and asymmetrical.
Culprit Compounds That Block Beans’ Healthful Iron Probed
October 19, 2009
Familiar beans like reds, whites and pintos are rich in iron, a nutrient essential for our health. But not all of the little legumes’ treasure trove of iron is bioaccessible—that is, available for our bodies to readily absorb.
In ongoing investigations, Agricultural Research Service (ARS) animal physiologist Raymond P. Glahn and Cornell University co-investigators are discovering more about natural compounds in foods that increase or, problematically, decrease absorption of iron from those foods. Glahn is based at the ARS Robert W. Holley Center for Agriculture and Health in Ithaca, N.Y.
Earlier this year, Glahn, along with former ARS research plant physiologist Ross M. Welch—now retired and working as a collaborator with the Ithaca laboratory—and their university collaborators began tests with poultry as a followup to experiments that relied on Caco-2 human digestive system cells, cultured in petri dishes.
One current study with poultry builds upon a Caco-2 study from several years ago in which Glahn, Welch and colleagues determined that a natural compound known as kaempferol may be a key culprit in decreasing absorption of iron from red and pinto beans.
Improving Stem Cell Techniques Using Protein Found In Moss
September 30, 2009
Hikers know that moss on a tree trunk always points north. According to new research by Israeli and German scientists, this ancient plant may also provide a new “compass” for stem cell research, telling scientists how better to program stem cells for medical purposes.
Dr. Nir Ohad of Tel Aviv University’s Department of Plant Sciences and Prof. Ralf Reski of the University of Freiburg have discovered a new use for the Polycomb group proteins (PcG) found in moss. They reported their findings recently in the journalDevelopment. PcG proteins play an important role in telling stem cells how to develop, they believe. The research is being funded by the German-Israeli Foundation.
Moss is a kind of plant that shares basic development processes with those found in humans. “We may not have found the switch that turns stem cells into tissue,” comments Dr. Ohad, “but we have found a key component which makes this switch work.”
Stopping the runaway gene
In their new paper, the researchers describe an ancient mechanism that alters the way DNA organizes inside the cell nucleus, which in turn, affects gene expression. This finding has important implications in stem cell therapies, which can go awry if implanted stem cells aren’t reprogrammed properly.
Individual Cells Isolated From Biological Clock Can Keep Daily Time, But Are Unreliable
September 10, 2009
Alexis Webb enters a small room at Washington University in St. Louis with walls, floor and ceiling painted dark green, shuts the door, turns off the lights and bends over a microscope in a black box draped with black cloth. Through the microscope, she can see a single nerve cell on a glass cover slip glowing dimly.
The glow tells her the isolated nerve cell is busy keeping time.
Webb, a graduate student in the neuroscience program, working with Erik Herzog, Ph.D., associate professor of biology in Arts & Sciences; Nikhil Angelo, an undergraduate biology major; and James Huettner, Ph.D., associate professor of cell biology and physiology in the School of Medicine, has demonstrated that individual cells isolated from the biological clock can keep daily time all by themselves.
However, by themselves, they are unreliable. The neurons get out of synch and capriciously quit or start oscillating again.
The biological clock, a one-square millimeter area of the brain called the suprachiasmic nucleus, or SCN, just above the roof of the mouth and atop the crossing of the optic nerves, comprises about 20,000 neurons.
These cells, remarkably, contain the machinery to generate daily, or circadian, rhythms in gene expression and electrical activity. But the individual cells are sloppy and must communicate with one another to establish a coherent 24-hour rhythm, says Herzog.
Fly Eyes Help Researchers ‘See’ New Proteins Involved In Memory
August 25, 2009
With more than 1,500 eyes, not much escapes the fruit fly’s sight. Now, a new research report in the journal Geneticsdescribes how researchers from the United States and Ireland used those eyes to “see” new proteins necessary for memory. In addition to shedding light on this critical neurological process, the study also provides information on a form of mental retardation in humans.
“Understanding translational control mechanisms in the brain teaches us how the brain learns and adapts, and will inform the design of treatments for specific types of neurologic disease,” said Dr. Anne-Marie Cziko, at the University of Arizona and co-author of the study.
Specifically, the scientists found that the “fragile X mental retardation protein,” which plays a crucial role in the cellular processes involved in learning and memory, needs five other proteins to function normally. The scientists identified these proteins using an artificial system of increasing fragile X mental retardation protein in the eyes of fruit flies. Its high level leads to visible deformities in a fly’s eyes. To test the requirement of various candidate proteins for function of the fragile X mental retardation protein, the researchers genetically modified the flies to prevent them from making each candidate protein. They found that loss of any one of the five proteins caused the fruit fly’s eye to be significantly less deformed, revealing that each is required for function of the fragile X mental retardation protein.
Birds: Feather Color Is More Than Skin Deep
April 15, 2009
Where do birds get their red feathers from? According to Esther del Val, from the National History Museum in Barcelona, Spain, and her team, the red carotenoids that give the common crossbill (Loxia curvirostra) its red coloration are produced in the liver, not the skin, as previously thought.
Their findings, published online in Springer’s journal Naturwissenschaften, have implications for understanding the evolution of color signaling in bird species.
Carotenoids have important physiological functions, including antioxidant, immunomodulating, and photoprotectant properties. Carotenoid pigments are also used by many bird species as colorants, and are responsible for most of their red, orange and yellow coloration. In particular, carotenoid-red coloration in birds has been shown to act as an ornament, signaling the nutritional and health status of the individual and its ability to locate high quality resources. Recent studies have suggested that the transformation of carotenoid pigments takes place directly in the follicles during feather growth.
