clock news
clock | November 30, 2007Shift Work May Be Cancer Risk:
In an announcement to be published Saturday in the journal Lancet Oncology, the International Agency for Research on Cancer, part of the World Health Organization, will label shift work as a "probable cause" of cancer.
The designation -- rooted in the theory that the disruption of circadian rhythms could be a culprit -- puts shift work on a par with ultraviolet radiation or anabolic steroids as suspected carcinogens, but does not say it is a definitive cause of cancer, such as cigarette smoking.
A random schedule of shifts - working a couple of days a week at…
clock | November 4, 2007Plano teen wins regional science award, moves on to national competition:
The awards, which recognize exceptional achievement in science, were announced Saturday at the University of Texas at Austin.
Alexander, who won a $3,000 scholarship, was honored for developing a realistic mathematical model detailing how biological clocks work.
"This is publishable, graduate-level work," said Claus Wilke, an assistant professor of Integrative Biology Section at UT.
He called Alexander's entry -- "Mathematical Modeling of a Eukaryotic Circadian Clock" -- a key component in understanding jet lag and…
clock | November 3, 2007I was fantastically busy this past week, so I failed to alert you to new articles published in PLoS Computational Biology, PLoS Pathogens, PLoS Genetics and PLoS Neglected Tropical Diseases. I have posted my picks from the latter one. This week, my pick is this one, of course, as I have watched the previous microarray studies come out one by one, each identifying a different set of genes:
Meta-Analysis of Drosophila Circadian Microarray Studies Identifies a Novel Set of Rhythmically Expressed Genes:
Circadian genes regulate many of life's most essential processes, from sleeping and eating to…
clock | October 24, 2007I am sure I have ranted about the negative effects of DST here and back on Circadiana, but the latest study - The Human Circadian Clock's Seasonal Adjustment Is Disrupted by Daylight Saving Time (pdf) (press releases: ScienceDaily, EurekAlert) by Thomas Kantermann, Myriam Juda, Martha Merrow and Till Roenneberg shows that the effects are much more long-lasting and serious than previously thought. It is not "just one hour" and "you get used to it in a couple of days". Apparently it takes weeks for the circadian system to adjust, and in some people it never does. In this day and age of…
clock | October 9, 2007There are times when one would like to hang the whole human race and finish the farce.
- Mark Twain
clock | September 27, 2007
When teaching human or animal physiology, it is very easy to come up with examples of ubiqutous negative feedback loops. On the other hand, there are very few physiological processes that can serve as examples of positive feedback. These include opening of the ion channels during the action potential, the blood clotting cascade, emptying of the urinary bladder, copulation, breastfeeding and childbirth. The last two (and perhaps the last three!) involve the hormone oxytocin. The childbirth, at least in humans, is a canonical example and the standard story goes roughly like this:
When the…
clock | September 19, 2007Circadian clocks: regulators of endocrine and metabolic rhythms by Michael Hastings, John S O'Neill and Elizabeth S Maywood is a new and excellent review of the interaction between the clocks and hormones in mammals, focusing at the molecular level. The pre-print PDF of the article is freely available on the Journal of Endocrinology site.
clock | August 11, 2007From June 26, 2006....
In the beginning, there was period.
Before 1995, the only known circadian clock genes were period (Per) in Drosophila melanogaster (wine fly) and frequency (Frq) in Neurospora crassa (bread mold). Some mutations, though not characterized at the molecular level, were also known in Chlamydomonas, Euglena as well as the famous Tau-mutation in hamsters.
I still remember the strained mathematical models attempting to account for a 24-hour rhythm with just a single gene controlling its own expression. We now know that multiple genes are involved in circadian function in…
clock | July 31, 2007
If you are one of the few of my readers who actually slogged through my Clock Tutorials, especially the difficult series on Entrainment and Phase Response Curves, you got to appreciate the usefulness of the oscillator theory from physics in its application to the study of biological clocks. Use of physics models in the study of biological rhythms, pioneered by Colin Pittendrigh, is an immensely useful tool in the understanding of the process of entrainment to environmental cycles.
Yet, as I warned several times, a Clock is a metaphor and, as such, has to be treated with thought and caution…
clock | July 20, 2007Microarrays have been used in the study of circadian expression of mammalian genes since 2002 and the consensus was built from those studies that approximately 15% of all the genes expressed in a cell are expressed in a circadian manner. I always felt it was more, much more.
I am no molecular biologist, but I have run a few gels in my life. The biggest problem was to find a control gene - one that does not cycle - to make the comparisons to. Actin, which is often used in such studies as control, cycled in our samples. In the end, we settled on one of the subunits of the ribosome as we…
clock | July 15, 2007A very cool study that I could not help but comment on (January 18, 2006)...
A brand new paper is making a splash in the field these days - so much that you can find the press release in three places: here, here and here, this last one being the coolest as it contains a movie and three podcasts!
One of the biggest problems in circadian biology is to account for such a long time - 24 hours - it takes for the whole transcription-translation feedback loop to run its course through a single cycle. Biochemical reactions tend to happen at much shorter time scales. Some mathematical models tried to…
clock | July 14, 2007No other aspect of behavioral biology is as well understood at the molecular level as the mechanism that generates and sustains circadian rhythms. If you are following science in general, or this blog in particular, you are probably familiar with the names of circadian clock genes like per, tim, clk, frq, wc, cry, Bmal, kai, toc, doubletime, rev-erb etc.
The deep and detailed knowledge of the genes involved in circadian clock function has one unintended side-effect, especially for people outside the field. If one does not stop and think for a second, it is easy to fall under the impression…
clock | July 13, 2007If this gets more widely known (and, with this post, I am trying to help it become so), you can just imagine the jokes about the new challenges to the aviation industry and the renewed popularity of the Mile High Club, or the cartoons utilizing the phallic shape of airplanes!
Hamsters on Viagra Have Less Jet Lag, Research Shows (also Viagra helps jet-lagged hamsters, maybe humans, too: study and Viagra 'improves jet lag'):
Hamsters given Pfizer Inc.'s Viagra adapted more quickly to changes in their internal clocks, scientists said.
Hamsters given sildenafil, the chemical name of the drug…
clock | July 10, 2007
Menaker Awarded Farrell Prize in Sleep Medicine:
Michael Menaker, professor of biology and an international leader in the field of circadian rhythm research, received the Peter C. Farrell Prize in Sleep Medicine from the Harvard Medical School Division of Sleep Medicine during an event there on June 6.
The prize was awarded "in celebration of the life and work of Michael Menaker, trailblazer in circadian biology and prescient illuminator of how Light and Dark, the alternating ancient heritages of our planet, come to govern and synchronize living clocks."
Menaker was cited as a "ground-…
clock | July 3, 2007Surprise, surprise - a paper in Science is up there with a free online access (not the PDF, but the Full Text and that is something!):
A Molecular Basis for Natural Selection at the timeless Locus in Drosophila melanogaster:
Diapause is a protective response to unfavorable environments that results in a suspension of insect development and is most often associated with the onset of winter. The ls-tim mutation in the Drosophila melanogaster clock gene timeless has spread in Europe over the past 10,000 years, possibly because it enhances diapause. We show that the mutant allele attenuates the…
clock | June 15, 2007
Microarrays have been used in the study of circadian expression of mammalian genes since 2002 and the consensus was built from those studies that approximately 15% of all the genes expressed in a cell are expressed in a circadian manner. I always felt it was more, much more.
I am no molecular biologist, but I have run a few gels in my life. The biggest problem was to find a control gene - one that does not cycle - to make the comparisons to. Actin, which is often used in such studies as control, cycled in our samples. In the end, we settled on one of the subunits of the ribosome as we…
clock | June 14, 2007
This article, of course, got my attention:
Clocking In And Out Of Gene Expression
Using steroid receptor coactivator-3 (SRC-3), they demonstrated that activation requires addition of a phosphate molecule to the protein at one spot and addition of an ubiquitin molecule at another point. Each time the message of the gene is transcribed into a protein, another ubiquitin molecule is chained on. Five ubiquitins in the chain and the protein is automatically destroyed.
"It's built-in self destruction," said O'Malley. "It prevents you from activating a potent factor in the cells that just keeps the…
clock | June 13, 2007More stuff from SLEEP 2007, the 21st Annual Meeting of the Associated Professional Sleep Societies:
Sleep Deprivation Affects Eye-steering Coordination When Driving:
Driving a vehicle requires coordination of horizontal eye movements and steering. Recent research finds that even a single night of sleep deprivation can impact a person's ability to coordinate eye movements with steering.
Extra Sleep Improves Athletes' Performance:
Athletes who get an extra amount of sleep are more likely to improve their performance in a game, according to recent research.
Going To Bed Late May Affect The…
clock | June 13, 2007Children With Sleep Disorder Symptoms Are More Likely To Have Trouble Academically:
Students with symptoms of sleep disorders are more likely to receive bad grades in classes such as math, reading and writing than peers without symptoms of sleep disorders, according to recent research.
Slow Wave Activity During Sleep Is Lower In African-Americans Than Caucasians:
Slow wave activity (SWA), a stable trait dependent marker of the intensity of non-rapid eye movement (NREM) sleep, is lower in young healthy African-Americans compared to Caucasians who were matched for age, gender and body weight,…
clock | June 12, 2007Sleep Deprivation Affects Airport Baggage Screeners' Ability To Detect Rare Targets:
A lack of sleep may affect the performance of airport employees, which can, in turn, compromise the safety of airline passengers. Sleep deprivation can impair the ability of airport baggage screeners to visually search for and detect infrequently occurring or low prevalence targets that may ultimately pose a threat to an airline and its passengers, according to new research.
Night Shift Nurses More Likely To Have Poor Sleep Habits:
Nurses who work the night shift are more likely to have poor sleep habits, a…