XML Feed for RxPG News   Add RxPG News Headlines to My Yahoo!   Javascript Syndication for RxPG News

Research Health World General
 
  Home
 
 Latest Research
 Cancer
 Psychiatry
  Depression
  Neuropsychiatry
  Personality Disorders
  Bulimia
  Anxiety
  Substance Abuse
  Suicide
  CFS
  Psychoses
  Child Psychiatry
  Learning-Disabilities
  Psychology
  Forensic Psychiatry
  Mood Disorders
  Sleep Disorders
   Circardian Rhythm
  Peri-Natal Psychiatry
  Psychotherapy
  Anorexia Nervosa
 Genetics
 Surgery
 Aging
 Ophthalmology
 Gynaecology
 Neurosciences
 Pharmacology
 Cardiology
 Obstetrics
 Infectious Diseases
 Respiratory Medicine
 Pathology
 Endocrinology
 Immunology
 Nephrology
 Gastroenterology
 Biotechnology
 Radiology
 Dermatology
 Microbiology
 Haematology
 Dental
 ENT
 Environment
 Embryology
 Orthopedics
 Metabolism
 Anaethesia
 Paediatrics
 Public Health
 Urology
 Musculoskeletal
 Clinical Trials
 Physiology
 Biochemistry
 Cytology
 Traumatology
 Rheumatology
 
 Medical News
 Health
 Opinion
 Healthcare
 Professionals
 Launch
 Awards & Prizes
 
 Careers
 Medical
 Nursing
 Dental
 
 Special Topics
 Euthanasia
 Ethics
 Evolution
 Odd Medical News
 Feature
 
 World News
 Tsunami
 Epidemics
 Climate
 Business
Search

Last Updated: Aug 19th, 2006 - 22:18:38

Circardian Rhythm Channel
subscribe to Circardian Rhythm newsletter

Latest Research : Psychiatry : Sleep Disorders : Circardian Rhythm

   DISCUSS   |   EMAIL   |   PRINT
New fruit fly protein JET illuminates circadian response to light
Jun 30, 2006, 02:26, Reviewed by: Dr. Priya Saxena

"Since the degradation of TIM always happens in the presence of light, the animal associates the absence of TIM with daytime hours"

 
Researchers at the University of Pennsylvania School of Medicine have identified a new protein required for the circadian response to light in fruit flies. The discovery of this protein named JET brings investigators one step closer to understanding the process by which the body's internal clock synchronizes to light. Understanding how light affects circadian (24-hour) rhythms will likely open doors to future treatments of jetlag.

The body's 24-hour clock controls a multitude of internal functions such as periods of sleep and wakefulness, body temperature, and metabolism. Although circadian function produces a stable rhythm in the body, the biological clock will reset in response to light. The human condition known as jet lag takes place during the period when the body is attempting to resynchronize to the environmental light changes brought on by travel, namely from one time zone to another.

A mutant fruit fly that possesses jetlag-like behaviors enabled senior author Amita Sehgal, PhD, Professor of Neuroscience at Penn and a Howard Hughes Medical Institute (HHMI) Investigator, and colleagues to identify the gene and subsequent protein that aids in the response of the internal biological clock to light. The researchers report their findings in most recent issue of Science.

To test the circadian rhythm of fruit flies, Sehgal and others exposed wild type (control) and mutant flies to several light and dark settings constant darkness, constant light, and equal periods of light and darkness (a light-dark cycle). During exposure to constant light for one week, the controls developed a disrupted sleep pattern after a few days, while the mutants maintained a regular circadian rhythm. The mutant and control flies displayed no behavioral differences during their exposure to constant darkness and the light-dark cycle. However, when the fruit flies were shifted from one light-dark cycle to another, the mutant flies took two days longer to adjust their sleep-wake cycle to the new light-dark schedule.

"The behavior of the mutant flies is similar to that displayed in a person who has prolonged jetlag," notes Sehgal. In search of answers to the mutant's defective circadian response to light, Sehgal and colleagues looked to the molecular details of the clock cells in the jetlag flies.

When a fruit fly is exposed to light, a photoreceptor called cryptochrome (CRY) transduces the light signal and kicks off a series of reactions within the clock cells of the brain. Under normal conditions, CRY will respond to light by binding to a protein called timeless (TIM). A second protein, a member of the F-box protein family, also binds to TIM, signaling TIM for cellular destruction.

Genetic analysis revealed that the jetlag flies possess a mutation in a gene that encodes a member of the F-box protein family. A closer examination of the protein produced by the mutated sequence led researchers to JET, a new protein within the F-box protein family.

"Since the degradation of TIM always happens in the presence of light, the animal associates the absence of TIM with daytime hours," explains Sehgal. The mutated JET protein reduces the light-dependent degradation of TIM and the circadian response to light.

Sehgal and others were able to reverse the behaviors in the jetlag flies by genetically replacing the mutated gene sequence with the normal sequence, which led to the production of the wild-type (control) JET protein. When the jetlag flies acquired the normal JET protein, regular TIM degradation took place and the fruit fly was better able to adjust to shifts in the light-dark cycle.

Future studies in the Sehgal lab will focus on continuing to identify other molecules required for the circadian response to light. "Some of the molecules required for the circadian light response in flies may be conserved in humans. Over time, we will have a better understanding of how the human clock responds to light and may be able to design drugs to treat jetlag," concludes Sehgal.
 

- Science Journal
 

uphsxnet.uphs.upenn.edu

 
Subscribe to Circardian Rhythm Newsletter
E-mail Address:

 

Study co-authors are Kyunghee Koh and Xiangzhong Zheng, both from Penn. These studies were funded by the National Institutes of Health and HHMI.

Penn Medicine is a $2.9 billion enterprise dedicated to the related missions of medical education, biomedical research, and high-quality patient care. Penn Medicine consists of the University of Pennsylvania School of Medicine (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System.

Penn's School of Medicine is ranked #2 in the nation for receipt of NIH research funds; and ranked #3 in the nation in U.S. News & World Report's most recent ranking of top research-oriented medical schools. Supporting 1,400 fulltime faculty and 700 students, the School of Medicine is recognized worldwide for its superior education and training of the next generation of physician-scientists and leaders of academic medicine.

The University of Pennsylvania Health System includes three hospitals [Hospital of the University of Pennsylvania, which is consistently ranked one of the nation's few "Honor Roll" hospitals by U.S. News & World Report; Pennsylvania Hospital, the nation's first hospital; and Penn Presbyterian Medical Center]; a faculty practice plan; a primary-care provider network; two multispecialty satellite facilities; and home care and hospice.


Related Circardian Rhythm News

Computer models may reveal what makes human body clock tick
New fruit fly protein JET illuminates circadian response to light
Children with fetal alcohol spectrum disorders exhibit altered sleeping and eating patterns
Body clock could be re-set: Research
Avoid jet lag by resetting body clock
Clocking in Pillow Time without the Pillow
Serotonin appears to modulate circardian rhythm


For any corrections of factual information, to contact the editors or to send any medical news or health news press releases, use feedback form

Top of Page

 

© Copyright 2004 onwards by RxPG Medical Solutions Private Limited
Contact Us