 |
|
Research Team Is First to Model Photochemical Compass for Bird Navigation
May 01, 2008A team of researchers at Arizona State University and the University of Oxford are the first to model a photochemical compass that may simulate how migrating birds use light and Earth's weak magnetic field to navigate. The team reports in the April 30, 2008, online issue of Nature that the photochemical model becomes sensitive to the magnitude and direction of weak magnetic fields similar to Earth's when exposed to light. The research funded by the National Science Foundation (NSF) demonstrates that this phenomenon, known as chemical magnetoreception, is feasible and gives insight into the structural and dynamic design features of a photochemical compass.
The most common bird migration pattern in the northern hemisphere is to fly north in the summer to breed in the Artic and to fly south to warmer regions for the winter.
Regardless of which way they are flying, migrating birds are important ecologically as a food source for other animals. They also transport plankton, materials involved in plant reproduction and hitchhikers such as ticks and lice, which can carry micro-organisms harmful to human health.
About 50 animal species, ranging from birds and mammals to reptiles and insects, use Earth's weak magnetic field for navigation. Earth's magnetic field ranges from approximately 30 to 60 millionths of one tesla. By comparison, magnetic resonance imaging, or MRI, uses magnetic fields from 1.5 to 3.0 tesla.
Weak magnetic fields are also produced by widely used technologies such as power lines and communications equipment. Because these man-made magnetic fields can disrupt animal navigation, "it is essential for humans to understand how animals navigate using Earth's weak magnetic field and the effects of human activity on animal navigation," according to Devens Gust, foundation professor of chemistry and biochemistry at Arizona State University.
Even though the mechanisms of a bird's internal compass have been studied intensively, they are not completely understood.
One existing theory is that photoreceptors in a bird's retina absorb light, which causes a chemical reaction that, in turn, produces a short-lived photochemical species whose lifetime is sensitive to the magnitude and direction of a weak magnetic field.
The photoreceptor theory is supported by the fact that blue light photoreceptors have been detected in retinas of migratory birds when they perform magnetic orientation. However, it has not been confirmed in the field or the lab that a magnetic field as weak as Earth's can produce detectable changes within a photochemical molecule; nor, has a photochemical molecule been shown to respond to the direction of such a magnetic field until now.
The U.S. and U.K. researchers have demonstrated that a synthesized photochemical molecule composed of linked carotenoid, porphyrin and fullerene units can act as a magnetic compass. Carotenoid is an organic pigment that occurs naturally in plants and other photosynthetic organisms. Porphyrin is similar to a chlorophyll molecule and exists in green leaves and red blood cells. Fullerene is composed entirely of carbon, and a spherical fullerene is known as a "buckyball."
Under normal conditions, each of the outer electron orbitals of the linked carotenoid (C), porphyrin (P) and fullerene (F) units contain two paired electrons. In the pair, the magnetic "north" pole of one electron is matched with the magnetic "south" pole of the other, causing it to be non-magnetic. As all of its electrons are paired, the CPF molecule has a neutral charge and exists in its lowest energy or ground state. Alternatively, when a CPF molecule is exposed to light, porphyrin absorbs the light energy and moves into a higher energy or excited state.
Porphyrin's excited state induces a carotenoid electron to leave its partner electron and move to fullerene's outer orbital. Since the transfer of the single electron causes the outer orbital of fullerene to gain an electron and be negatively charged and the outer orbital of carotenoid to be short one electron and positively charged, the newly formed molecule, C•+PF•-, exists in a charge-separated state.
Given that the single, or radical, electrons located in the outer orbitals of the carotenoid and fullerene units are no longer paired with their partner electrons, and are located on opposite ends of the C•+PF•- molecule, they can respond to the direction and magnitude of weak external magnetic forces of approximately 50 millionths of a tesla. After a brief moment, the lone radical electron on the fullerene returns to the carotenoid and the absorbed light energy is converted to heat.
"These results provide a clear proof-of-principle that the magnetic compass sense of migratory birds is based on a magnetically sensitive chemical reaction whose lifetime depends on the orientation of its molecules to Earth's magnetic field," said Peter Hore, professor of chemistry at Oxford University and head of the U.K. team.
Gust and Arizona State University collaborators Thomas Moore and Ana Moore originally synthesized photochemical molecules related to the CPF molecule for use in artificial photosynthetic reaction centers. These centers mimic the mechanisms by which photosynthetic organisms convert sunlight into useful forms of energy. They are now looking at developing their molecules for solar production of electricity or fuels such as hydrogen.
"The research completed by Gust and his collaborators is an excellent example of how basic research can lead to new knowledge and applications in many different fields of science and technology," said Tyrone Mitchell, director of NSF's Organic and Macromolecular Chemistry Program.
Co-authors of the Nature paper are Kiminori Maeda, Kevin Henbest, Filippo Cintolesi, Ilya Kuprov, Christopher Rodgers and Christiane Timmel of Oxford University and Paul A. Liddell of Arizona State University.
The research was supported by NSF Division of Chemistry award number 0352599.
The National Science Foundation (NSF)
About 50 animal species, ranging from birds and mammals to reptiles and insects, use Earth's weak magnetic field for navigation. Earth's magnetic field ranges from approximately 30 to 60 millionths of one tesla. By comparison, magnetic resonance imaging, or MRI, uses magnetic fields from 1.5 to 3.0 tesla.
Weak magnetic fields are also produced by widely used technologies such as power lines and communications equipment. Because these man-made magnetic fields can disrupt animal navigation, "it is essential for humans to understand how animals navigate using Earth's weak magnetic field and the effects of human activity on animal navigation," according to Devens Gust, foundation professor of chemistry and biochemistry at Arizona State University.
Even though the mechanisms of a bird's internal compass have been studied intensively, they are not completely understood.
One existing theory is that photoreceptors in a bird's retina absorb light, which causes a chemical reaction that, in turn, produces a short-lived photochemical species whose lifetime is sensitive to the magnitude and direction of a weak magnetic field.
The photoreceptor theory is supported by the fact that blue light photoreceptors have been detected in retinas of migratory birds when they perform magnetic orientation. However, it has not been confirmed in the field or the lab that a magnetic field as weak as Earth's can produce detectable changes within a photochemical molecule; nor, has a photochemical molecule been shown to respond to the direction of such a magnetic field until now.
The U.S. and U.K. researchers have demonstrated that a synthesized photochemical molecule composed of linked carotenoid, porphyrin and fullerene units can act as a magnetic compass. Carotenoid is an organic pigment that occurs naturally in plants and other photosynthetic organisms. Porphyrin is similar to a chlorophyll molecule and exists in green leaves and red blood cells. Fullerene is composed entirely of carbon, and a spherical fullerene is known as a "buckyball."
Under normal conditions, each of the outer electron orbitals of the linked carotenoid (C), porphyrin (P) and fullerene (F) units contain two paired electrons. In the pair, the magnetic "north" pole of one electron is matched with the magnetic "south" pole of the other, causing it to be non-magnetic. As all of its electrons are paired, the CPF molecule has a neutral charge and exists in its lowest energy or ground state. Alternatively, when a CPF molecule is exposed to light, porphyrin absorbs the light energy and moves into a higher energy or excited state.
Porphyrin's excited state induces a carotenoid electron to leave its partner electron and move to fullerene's outer orbital. Since the transfer of the single electron causes the outer orbital of fullerene to gain an electron and be negatively charged and the outer orbital of carotenoid to be short one electron and positively charged, the newly formed molecule, C•+PF•-, exists in a charge-separated state.
Given that the single, or radical, electrons located in the outer orbitals of the carotenoid and fullerene units are no longer paired with their partner electrons, and are located on opposite ends of the C•+PF•- molecule, they can respond to the direction and magnitude of weak external magnetic forces of approximately 50 millionths of a tesla. After a brief moment, the lone radical electron on the fullerene returns to the carotenoid and the absorbed light energy is converted to heat.
"These results provide a clear proof-of-principle that the magnetic compass sense of migratory birds is based on a magnetically sensitive chemical reaction whose lifetime depends on the orientation of its molecules to Earth's magnetic field," said Peter Hore, professor of chemistry at Oxford University and head of the U.K. team.
Gust and Arizona State University collaborators Thomas Moore and Ana Moore originally synthesized photochemical molecules related to the CPF molecule for use in artificial photosynthetic reaction centers. These centers mimic the mechanisms by which photosynthetic organisms convert sunlight into useful forms of energy. They are now looking at developing their molecules for solar production of electricity or fuels such as hydrogen.
"The research completed by Gust and his collaborators is an excellent example of how basic research can lead to new knowledge and applications in many different fields of science and technology," said Tyrone Mitchell, director of NSF's Organic and Macromolecular Chemistry Program.
Co-authors of the Nature paper are Kiminori Maeda, Kevin Henbest, Filippo Cintolesi, Ilya Kuprov, Christopher Rodgers and Christiane Timmel of Oxford University and Paul A. Liddell of Arizona State University.
The research was supported by NSF Division of Chemistry award number 0352599.
The National Science Foundation (NSF)
Photochemical Current Events and Photochemical News RSSFlax and yellow flowers can produce bioethanol
Surplus biomass from the production of flax shives, and generated from Brassica carinata, a yellow-flowered plant related to those which engulf fields in spring, can be used to produce bioethanol.
University of Hawai'i at Manoa team unravels the chemistry of Titan's hazy atmosphere
A team of University of Hawai'i at Mānoa researchers led by Ralf Kaiser, physical chemist at UH Mānoa, unraveled the chemical evolution of the orange-brownish colored atmosphere of Saturn's moon Titan, the only solar system body besides Venus and Earth with a solid surface and thick atmosphere.
They're alive!! Megacities breathe, consume energy, excrete wastes and pollute
A scientific trend to view the world's biggest cities as analogous to living, breathing organisms is fostering a deep new understanding of how poor air quality in megacities can harm residents, people living far downwind, and also play a major role in global climate change.
UCI scientists discover ozone-boosting chemical reaction
Burning of fossil fuels pumps chemicals into the air that react on surfaces such as buildings and roads to create photochemical smog-forming chlorine atoms, UC Irvine scientists report in a new study.
Methane-eating microbes can use iron and manganese oxides to 'breathe'
Iron and manganese compounds, in addition to sulfate, may play an important role in converting methane to carbon dioxide and eventually carbonates in the Earth's oceans, according to a team of researchers looking at anaerobic sediments.
New simulation shows consequences of a world without Earth's natural sunscreen
Nearly two-thirds of Earth's ozone is gone -- not just over the poles, but everywhere. The infamous ozone hole over Antarctica, first discovered in the 1980s, is a year-round fixture, with a twin over the North Pole. The ultraviolet (UV) radiation falling on mid-latitude cities like Washington, D.C., is strong enough to cause sunburn in just five minutes.
No quick or easy technological fix for climate change, researchers say
Global warming, some have argued, can be reversed with a large-scale "geoengineering" fix, such as having a giant blimp spray liquefied sulfur dioxide in the stratosphere or building tens of millions of chemical filter systems in the atmosphere to filter out carbon dioxide.
MU scientists go green with gold, distribute environmentally friendly nanoparticles
Gold nanoparticles are everywhere. They are used in cancer treatments, automobile sensors, cell phones, blood sugar monitors and hydrogen gas production.
Newly detected air pollutant mimics damaging effects of cigarette smoke
A previously unrecognized group of air pollutants could have effects remarkably similar to harmful substances found in tobacco smoke, Louisiana scientists are reporting in a study scheduled for presentation today at the 236th National Meeting of the American Chemical Society.
Hubble finds first organic molecule on extrasolar planet
The tell-tale signature of the molecule methane in the atmosphere of the Jupiter-sized extrasolar planet HD 189733b has been found with the Hubble Space Telescope. Under the right circumstances methane can play a key role in prebiotic chemistry - the chemical reactions considered necessary to form life as we know it.
More Photochemical Current Events and Photochemical News Articles
 |
UV Effects in Aquatic Organisms and Ecosystems (Comprehensive Series in Photochemical & Photobiological Sciences) by E.W. Helbling (Editor), H. Zagarese (Editor) This book offers extensive coverage of the most important aspects of UVR effects on all aquatic (not just freshwater and marine) ecosystems, encompassing UV physics, chemistry, biology and ecology. Comprehensive and up-to-date, "UV Effects in Aquatic Organisms and Ecosystems" aims to bridge the gap between environmental studies of UVR effects and the broader, traditional fields of ecology, oceanography and limnology. Adopting a synthetic approach, the different sections cover: the physical factors controlling UVR intensity in the atmosphere; the penetration and distribution of solar radiation in natural waters; the main photochemical process affecting natural and anthropogenic substances; and direct and indirect effects on organisms (from viruses, bacteria and algae to inverterbrate and... |
 |
Classic Chemical Processes used in the Motion Picture Laboratory Film Alchemist In Hollywood, The (Part I) (1940)- Explains chemical processes used in the motion picture laboratory. Diagrams and demonstrations of exposure, photochemical reactions, development, and printing. Photographer: Shirley Burden. Sound Recording: Bernard B. Brown. Producer: Atkinson (Ralph B.) & Solow (Sidney Paul) Audio/Visual: Sd, B&W Run time: 14:35 Alchemist In Hollywood, The (Part II) (1940)- Explains chemical processes used in the motion picture laboratory. Diagrams and demonstrations of exposure, photochemical reactions, development, and printing. Photographer: Shirley Burden. Sound Recording: Bernard B. Brown. Producer: Atkinson (Ralph B.) & Solow (Sidney Paul) Audio/Visual: Sd, B&W Run time: 13:47 |
|
The Photochemical Origin of Life by a dauvillier (Author) | |
|
Accelerated Aging: Photochemical and Thermal Aspects (Research in Conservation Technical Report) by Robert L. Feller (Author) Written by a renowned expert in the field, this book presents an overview of the results of research using accelerated aging tests. The emphasis is on the chemical aspects of photochemical stability, but thermally initiated deterioration is also discussed. Although not a "how-to" book, it does introduce the reasoning, limitations, and principles underlying the concept of accelerated aging. An extensive bibliography provides conservators and conservation scientists with an invaluable source for further research and exploration. | |
|
Photochemical Smog: Contribution of Volatile Organic Compounds by Organization for Economic Co-operation and Development (Author) | |
|
Photochemical Conversion and Storage of Solar Energy by John S. Connolly (Editor) | |
|
Principles and Practice of Photochemical Machining and Photoetching, by Allen (Author) | |
|
Photophysical and Photochemical Tools in Polymer Science: Conformation, Dynamics, Morphology (NATO Science Series C: (closed)) by Mitchell A. Winnik (Editor) | |
|
Photochemical Processing of Electronic Materials by Author Unknown (Author) This book reflects the state of the art in the field of photoprocessing. In addition to providing an introduction and review of many key areas of interest, it targets potential future applications of the technique, and realistically discusses problems that have yet to be solved. The individual chapters have been written by internationally recognized experts and the combination provides a unique and knowledgeable text. Although the basic scientific fundamentals are briefly addressed, the volume concentrates strongly on applications and as such should appeal to applied research scientists as well as students and engineers in the field, and those in managerial or funding positions in technology. Topics include: UV lens design Laser... | |
 |
Photochemical Vapor Deposition (Chemical Analysis: A Series of Monographs on Analytical Chemistry and Its Applications) by J. G. Eden (Author) Remote Sensing by Fourier Transform Spectrometry Reinhard Beer Here is a complete introduction to the specification, design, and implementation of Fourier Transform Spectrometers especially intended for atmospheric or astronomical remote sensing. Dr. Beer, one of the pioneers in this field, provides both specific and general information on the development of requirements for remote sensing Fourier transform infrared spectrometers and discusses many of the problems and pitfalls (along with their avoidance and solutions) that can beset the new user. 1992 (0 471-55346-8) 176 pp. Principles and Practice of Spectroscopic Calibration Howard Mark Clearly linking theory with applications, this unique guide to spectroscopic calibration advances an approach that is understandable, free of the usual... |
| © 2009 BrightSurf.com |