 |
|
Internal Clock, External Light Regulate Plant Growth
July 10, 2007Most plants and animals show changes in activity over a 24-hour cycle. Now, for the first time, researchers have shown how a plant combines signals from its internal clock with those from the environment to show a daily rhythm of growth.
Using time-lapse photography, postdoctoral researcher Kazunari Nozue, with colleagues from UC Davis and the University of Lausanne, Switzerland, found that the shoots of Arabidopsis seedlings show a spurt of growth once a day. The timing of that growth spurt is controlled by both the plant's internal clock and by exposure to light, acting on two genes called PIF 4 and PIF 5.
"It's a nice, elegant mechanism for how these two systems interact," said Julin Maloof, assistant professor of plant biology at UC Davis, who is senior author on the paper.
When the seedlings are grown in constant light, most growth occurs in the late afternoon. But when the plants were moved to a more natural light/dark cycle, growth shifted several hours to occur just before dawn. In nature, that is the time when water is usually most available.
The researchers identified the two genes, PIF 4 and PIF 5, that are connected to plant growth and regulated by the internal clock. The PIF 4 and 5 genes are "switched on" to make protein during the day, switch off after dark but then turn on again late in the night. But the proteins made by PIF 4 and PIF 5 break down when exposed to light. So while the internal clock drives transcription of the genes to produce proteins, external light removes the protein.
The PIF 4 and 5 proteins are thought to act as transcription factors that turn on other genes involved in growth.
The work is published online in the journal Nature, and was funded principally by the National Science Foundation and the Swiss National Science Foundation. The other authors on the paper are postdoctoral researcher Michael Covington and Stacey Harmer, assistant professor of plant biology at UC Davis; and Paula Duek, Severine Lorrain and Christian Fankhauser at the University of Lausanne, Switzerland.
UC Davis
When the seedlings are grown in constant light, most growth occurs in the late afternoon. But when the plants were moved to a more natural light/dark cycle, growth shifted several hours to occur just before dawn. In nature, that is the time when water is usually most available.
The researchers identified the two genes, PIF 4 and PIF 5, that are connected to plant growth and regulated by the internal clock. The PIF 4 and 5 genes are "switched on" to make protein during the day, switch off after dark but then turn on again late in the night. But the proteins made by PIF 4 and PIF 5 break down when exposed to light. So while the internal clock drives transcription of the genes to produce proteins, external light removes the protein.
The PIF 4 and 5 proteins are thought to act as transcription factors that turn on other genes involved in growth.
The work is published online in the journal Nature, and was funded principally by the National Science Foundation and the Swiss National Science Foundation. The other authors on the paper are postdoctoral researcher Michael Covington and Stacey Harmer, assistant professor of plant biology at UC Davis; and Paula Duek, Severine Lorrain and Christian Fankhauser at the University of Lausanne, Switzerland.
UC Davis
Internal Clock Current Events and Internal Clock News RSSU-M discovery about biological clocks overturns long-held theory
University of Michigan mathematicians and their British colleagues say they have identified the signal that the brain sends to the rest of the body to control biological rhythms, a finding that overturns a long-held theory about our internal clock.
Inner Workings of Molecular Thermostat Point to Pathways to Fight Diabetes, Obesity, According to Penn Study
Best known as the oxygen-carrying component of hemoglobin, the protein that makes blood red, heme also plays a role in chemical detoxification and energy metabolism within the cell. Heme levels are tightly maintained, and with good reason: Too little heme prevents cell growth and division; excessive amounts of heme are toxic.
MicroRNAs grease the cell's circadian clockwork
Most of our cells possess an internal clock, a group of genes displaying a cyclic expression pattern that reaches a peak once a day.
Fire and water reveal new archaeological dating method
Scientists at The University of Manchester have developed a new way of dating archaeological objects - using fire and water to unlock their 'internal clocks'.
UNC study: Tinkering with the circadian clock can suppress cancer growth
Researchers at the University of North Carolina at Chapel Hill have shown that disruption of the circadian clock - the internal time-keeping mechanism that keeps the body running on a 24-hour cycle - can slow the progression of cancer.
UNC study supports role of circadian clock in response to chemotherapy
For years, research has hinted that the time of day that cancer patients receive chemotherapy can impact their chances of survival. But the lack of a clear scientific explanation for this finding has kept clinicians from considering timing as a factor in treatment.
Body clock linked to diabetes and high blood sugar in new study
Diabetes and high levels of blood sugar may be linked to abnormalities in a person's body clock and sleep patterns, according to a genome-wide association study published today in the journal Nature Genetics.
A Therapy for Baby Boomers to Sleep On
If you're over 55 and have spent more than a few sleepless nights, you're not alone -- insomnia affects about half of all people over 55 ― but you may also be at increased risk for physical and mental ailments.
New studies on cancer and schizophrenia, depression and heart disease, trauma and autism
The 2007 American College of Neuropsychopharmacology Annual Meeting will feature hundreds of new studies on brain and behavior from the world's leading scientists. Presentations include innovative research on potential new treatments for depression, post-traumatic stress disorder, autism and addiction.
Studies find stable sleep patterns and regular routines may improve outcomes in bipolar disorder
Bipolar disorder, commonly known as manic-depressive disorder, is highly influenced by the circadian system - the body's internal clock - and a specific kind of psychotherapy may help decrease irregularities in the circadian system that can trigger key symptoms of bipolar disorder.
More Internal Clock Current Events and Internal Clock News Articles
 |
Internal Clock Robert Henke Monolake (Primary Contributor) |
 |
Boost Your Vitality With Melatonin: Programming Your Internal Clock For Health & Well-Being by Ingeborg Cernaj (Author) This miracle drug boosts the immune system, assures a good night's rest, relieves jet lag, lowers cholesterol, and acts as a fountain of youth. Discover what melatonin is, how the body produces it, and the latest scientific research on making this hormone work most effectively for you. |
 |
Infinity Instruments Hotel Perdier - Large Distressed Resin w/internal pendulum, Clock by Infinity Instruments Wall clock featuring an internal pendulum. Distressed dial featuring Arabic numbers at every hour and black metal hands. Operated by a highly accurate quartz movement. One or two "AA" battery, not included. Guaranteed by a one year manufacturer's warranty. |
 |
Celestron CGE PRO Computerized German Equatorial Mount with 38 - 55" Adjustable Tripod, Internal Clock by Celestron The Celestron CGE Pro German Equatorial mount is being fully computerized with a database of over 40,000 celestial objects. It features increased payload capacity, all-star polar alignment, no-tool polar alignment, meridian tracking, faster slew speed, power management, pointing and tracking. |
 |
Internal Clock by Circadian Rhythms |
 |
Boost Your Vitality with Melatonin: Programming Your Internal Clock for Health and Well-Being Millions of people think it's a miracle drug--and legions of doctors agree. Melatonin boosts the immune system, assures a good night's rest, relieves jet lag, lowers cholesterol, and acts as a fountain of youth. You'll have more energy, you'll have better health, and you'll get more out of life. Find out exactly what melatonin is, how the body produces it naturally, and the latest scientific research on how to get this hormone to work most effectively for you! * The rhythm with which melatonin disperses through the body makes a big difference--and here's advice on when to take it for the best results! * Melatonin regulates "free radicals," which otherwise may become cancerous. * Lower the risks of heart attacks, strokes, and arterial damage by regulating cholesterol with Melatonin. *... |
 |
Icon Time Systems PIN Entry Time Clock by Icon Time Systems Whether you've never owned a time clock or are transitioning from a mechanical to automated system, you'll find this unit intuitive and easy to use. Within minutes, you'll have everything you need to streamline your timekeeping and payroll process. Employees simply enter a unique ID number to clock IN or OUT, and the PIN Entry Employee Time Clock does the rest: no badges to use, lose, or replace. This system comes standard with TimeVue Lite Time Tracking Software, USB connectivity, and 50 employee capacity. It's no wonder Icon Time Systems time clocks are used by more than one million employees of small businesses across the U.S. and Canada. |
 |
The Internal Clock Gary Norman (Primary Contributor) |
 |
Farewell to the Internal Clock: A contribution in the field of chronobiology by Gunter Klein (Author) 'For many people, the moon is a familiar acquaintance with mysterious qualities. Depending on how it is illuminated by the sun, it shines sometimes as a complete disc and sometimes only as a sickle, sometimes it even makes itself invisible. The forces emanating from the moon give rise to high and low tides on the seacoasts. It's course and orbital velocity can be calculated exactly by means of complex mathematical formulae. Today, only the origin of the moon remains a mystery. Was it catapulted form the earth by a cosmic super-collision, or was it a wandering stray, captured by our planet from the cosmos? Apart from this, the relationship between the moon and the earth is considered to be all but completely understood by science. This book is not a contribution to the numerous... |
 |
Good Internal Clock Sybris (Primary Contributor) |
| © 2009 BrightSurf.com |