Stories tagged color
Signs of color preserved in stone?: Fossil feather from Brazil (left) displays similarities with recent woodpecker feather (right)
Courtesy J.Vinther/YaleResearchers at Yale University are reporting the discovery of pigmentation within the fossilize feather from a bird or dinosaur. Using a powerful electron microscope, paleobiologist Jakob Vinther and his team claim that particles seen in the 100-million-year-old fossil appear to be similar to those seen in the feathers of living birds. This could mean that color - a characteristic long-thought lost in the fossil record - could someday be determined from the remains of pigment.
Vinther’s colleagues included Yale paleontologist Derek E. G. Briggs and Yale ornithologist Richard O. Prum. The results of their study will appear in an upcoming issue of Biology Letters. The research shows that dark stripes in the Cretaceous-aged feather display many similarities to the make-up of black melanin particles found in modern bird feathers. Melanin compounds determine color in plants and animals, a trait useful for such things as camouflage, species identification, and courtship display. In humans, melanin colors our skin and also protects us from overexposure to sunlight.
For a long time, the dark granules seen in fossilized feathers were thought to be the carbon remains of bacteria that had worked at decomposing the organism prior to fossilization. But advances in electron microscope technology have given scientists a closer - and clearer – picture of the feather’s structure, and instead show them to be fossilized melanosomes containing melanin pigment.
"Feather melanin is responsible for rusty-red to jet-black colors and a regular ordering of melanin even produces glossy iridescence,” Vinther said. “Understanding these organic remains in fossil feathers also demonstrates that melanin can resist decay for millions of years."
Under the scope, the lighter bands of the fossilized feather showed only the rock matrix, while the darker bands displayed traces of residue closely resembling the organic compounds found in the feathers of modern birds.
“You wouldn’t expect bacteria to be aligned according to the orientation of the feathers,” said Vinther.
Another bird fossil showed similar organic traces in the feathers surrounding its skull. The 55-million-year-old fossil from Denmark also preserved an organic imprint of the eye that showed structures similar to the melanosomes found in eyes of modern birds.
Nanostructure studies could one day provide paleontologists with evidence of colors other than just black and gray tones, and not just in fossil feathers. Vinther figures other organic remains such as fur from prehistoric mammals or fossil skin impressions from dinosaurs could prove to be the remains of the melanin.
LINKS
ScienceNews story
Yale website story
Cosmos magazine website story
Melansome info
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My neighbor's tree dies a slow, agonizing, horrible death: Well, the leaves do, anyway. Photo by Gene
Oh, sure. Autumn looks pretty, with its big flashy colors and brilliant blue skies. But that’s just a mask it wears to disguise its true, evil intentions. Everything good in the world is dying, all around us, and there’s nothing we can do about it. In fall the nights grow longer, the days colder. Beaches close. Bicycles get packed away for the season. The two most perfect inventions of the mind of man – daylight saving time and baseball – both come to a close. It is the end of life as we have known it. And all we have to look forward to are endless months of icicle winds, lowering skies, and – worst of all – football.
The fiery colors of Autumn are the flames of a funeral pyre, a sign of death and decay. According to Susan Carpenter, native plant gardener at the University of Wisconsin-Madison Arboretum, leaves depend on the chemical auxin to keep open the tubes that supply water, sugar and nutrients. But the cooler temperatures and shorter days of Autumn shut off auxin production. The tubes are cut off, and the leaf strangles and dies. Chlorophyll, the green chemical that gives leaves their summer color, disintegrates, leaving behind two other chemicals: yellow carotene and red anthocyanin. Different tree species contain these chemicals in different amounts, resulting in the various colors we see.
Trees are at their most colorful when a cool, wet summer is followed by a sunny, dry fall. Rainfall promotes tree growth, and moderate temperatures prevent scorching in the summer sun. Extra sunlight in the fall allows trees to continue producing their chemicals right up to the end.
Here in Michigan, we had pretty much the opposite – a summer of drought and searing temperatures, followed by a fairly wet fall. The trees have been pretty brown since mid-September, though a few of them are making a late run at color. Don’t bother, boys. We’re depressed enough as it is.
Race: Are We So Different? More about the exhibit
The Science Museum of Minnesota will be the world premiere location of an exhibit about race and human variation called RACE: Are We So Different? on January 10th. I just finished watching the Paula Zahn NOW show on CNN tonight on Racism in America that covered many of the same topics that are discussed in the RACE exhibit, such as white privilege and the history and current status of racial preference in housing. It was interesting, and it was good to see race be openly discussed on national television.
One interesting web-based feature the show featured was a test developed by Harvard University researchers that used a series of words and images to highlight the differences between how we believe we act and think about race and how we subconsciously think about race.
Psychologists understand that people may not say what's on their minds either because they are unwilling or because they are unable to do so. For example, if asked "How much do you smoke?" a smoker who smokes 4 packs a day may purposely report smoking only 2 packs a day because they are embarrassed to admit the correct number. Or, the smoker may simply not answer the question, regarding it as a private matter. (These are examples of being unwilling to report a known answer.) But it is also possible that a smoker who smokes 4 packs a day may report smoking only 2 packs because they honestly believe they only smoke about 2 packs a day. (Unknowingly giving an incorrect answer is sometimes called self-deception; this illustrates being unable to give the desired answer).
The unwilling-unable distinction is like the difference between purposely hiding something from others and unconsciously hiding something from yourself. The Implicit Association Test makes it possible to penetrate both of these types of hiding. The IAT measures implicit attitudes and beliefs that people are either unwilling or unable to report.
It’s pretty interesting research, and a pretty interesting method. I recommend checking out the web site and trying a test or two out for yourself. You may be surprised by the result, and you may not agree with it, but I think it is interesting to learn about what our unconscious automatic preferences are. The RACE exhibit at the Science Museum will, I think, do the something similar to what this test does – give us a chance to look closely at ourselves and examine how we see others.
A Human Eye: Courtesy Wikipedia Images
Have your eyes ever played a trick on you? Perhaps you thought you saw something moving but it was a figment of your imagination. Researchers at the Salk Institute have recently suggested that two neurological pathways come together enabling superb motion detection.
Our brains rely on neural pathways to detect motion. This past April, researchers at the Salk Institute of Biological Studies have found a specific neural circuit playing a vital role in the ability to detect motion. The outer layer of the brain, named the cortex, plays an important role in motion recognition. Up till now, it has been believed that motion perception is not influenced by color and fine details. However, the idea of motion perception is becoming more colorful!
Our eyes have the duty of breaking down daily images we come across. These images are broken down into three divisions: color, position and brightness. Each of these categories has specialized pathways transmitting seen images from our eyes to our brain. The pathway transmitting color and fine spatial detail is named the parvocellular pathway. The magnocellular pathway detects low contrast and rapid changes. Lastly the visual cortex uses information from both the parvocellular and magnocellular to compute motion, shape and color.
Camouflaged lizard: Consider the motion of a slowly moving lizard camouflaged against leaves and twigs: the M pathway wouldn’t recognize the lizard, but the P pathway, detecting color, fine detail, and slow movement, would pick it up. (Photo courtesy Rachel Kramdar)
Courtesy Kramdar
The Salk Institute for Biological Studies has challenged the long-standing understanding that the magnocellular and parvocellular are two totally separate pathways. It has commonly been assumed that the magnocelluar pathway is the only pathway that transmits information to the cortical motion processing area called the MT. The MT in turn receives input from the primary visual cortex, which gets its information from the magnocelluar pathway as well. Researchers from the Salk Institute are proposing that the parvocellular pathway has input when detecting motion and also sends information to the primary visual cortex.
Sounds complicated, huh? Well, researchers at the Salk Institute used a rabies virus strain to track neural circuits in reverse. The rabies virus was used because it had special infectious properties allowing scientists to easily discern neurological pathways. They were able to trace neural circuits beginning at the MT back to the magnocellular and parvocellular pathways connecting to the primary visual cortex. The technique is called trans-synaptic tracing. Findings suggested that the magnocellular and parvocellular pathways merged before transmitting visual information to the MT area.
The research team was composed of professor Edward Callaway, graduate student Jonathan Nassi and post-doctoral researcher David Lyon, Ph.D. Callaway commented on the significance of his teams’ findings:
“...People tend to think about detection of fast motion changes. But we also need to detect the motion of things that are moving more slowly. The addition of the parvocellular pathway to the motion systems helps us to see movement of things to which the magnocelluar pathway is blind.”
-From Eurekalert
Blue sky.: Image courtesy robpatrick.
One of the random questions we often get at the Science Buzz is “why is the sky blue?”. A recent article published by the Columbia News Service addresses this question, along with nine others, in an article called How High is Your Science IQ? The article is a list of ten science facts every high school graduate should know. To get to the 10 facts the Columbia News Service asked Nobel Prize winners, institute heads, and teachers, “What is one science question every high school graduate should be able to answer?” The questions are good ones – how many can you get right? Check out the article and test yourself!
Oh, and if you want even more information on why the sky is blue, here is a good Wikipedia article on the subject.
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