clock news
clock | June 3, 2007Wide Range Of Sleep-related Disorders Associated With Abnormal Sexual Behaviors, Experiences:
A paper published in the June 1st issue of the journal SLEEP is the first literature review and formal classification of a wide range of documented sleep-related disorders associated with abnormal sexual behaviors and experiences. These abnormal sexual behaviors, which emerge during sleep, are referred to as "sleepsex" or "sexsomnia".
See also this, this and this.
Why Patients With Obstructive Sleep Apnea Are At Higher Risk For Cardiovascular Disease:
Researchers have found that patients with…
clock | May 22, 2007
If 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 | May 18, 2007
As we mentioned just the other day, studying animal behavior is tough as "animals do whatever they darned please". Thus, making sure that everything is controlled for in an experimental setup is of paramount importance. Furthermore, for the studies to be replicable in other labs, it is always a good idea for experimental setups to be standardized. Even that is often not enough. I do not have access to Science but you may all recall a paper from several years ago in which two labs tried to simultaneously perform exactly the same experiment in mice, using all the standard equipment,…
clock | May 17, 2007I recently mentioned a study reporting circadian oscillations of bacterial clock-proteins KaiA, KaiB and KaiC in a dish with no transcription and translation whatsoever - the oscillations being due entirely to polymerization of proteins. Now, a mathematical model of this system has also been published describing how the working of the system is possible.
clock | May 6, 2007
This is going to be a challenging post to write for several reasons. How do I explain that a paper that does not show too much new stuff is actually a seminal paper? How do I condense a 12-page Cell paper describing a gazillion experiments without spending too much time on details of each experiment (as much as I'd love to do exactly that)? How do I review it calmly and critically without gushing all over it and waxing poetically about its authors? How do I put it in proper theoretical and historical perspective without unnecessarily insulting someone? I'll give it a try and we'll see…
clock | May 1, 2007One chronobiological pioneer is leaving and another one is coming in. Gene Block is going to UCLA and Joe Takahashi is leaving Northwestern (What are Fred Turek and others going to do there without him? What happens to the Howard Hughes institute?) and coming in to head the new Center for Circadian and Systems Biology. A very interesting game of musical chairs. Stay tuned.
clock | April 26, 2007Thus reports The Scientist:
Researchers from three different labs have identified a new circadian gene in the mouse, according to two papers in Science and one paper in Cell published online this week. Mutagenesis screens revealed that mutations in a protein called FBXL3 lengthen the mouse circadian period by several hours, and biochemical analyses showed that FBXL3 is necessary for degradation of key circadian clock proteins.
I'll probably have something more to say once I get hold of the actual papers.
In a perfect world, the three groups would have done Open Notebook science, found each…
clock | April 22, 2007This is the first study I know that directly tested this - the effects of rotating shifts on longevity - in humans, though some studies of night-shift nurses have shown large increases in breast cancers, stomach ulcers and heart diseases, and similar studies have been done in various rodents and fruitflies:
Working in shifts shortens life span: Study:
A study of 3,912-day workers and 4,623 shift workers of the Southeastern Central Railway in Nagpur showed the former lived 3.94 years longer than their counterparts on shift duties, said the study by Atanu Kumar Pati of The School of Life…
clock | April 12, 2007I made only a brief mention of the study when the press release first came out, but the actual paper (which is excellent) is out now. It is on PLoS so it is free for all to see: Mania-like behavior induced by disruption of CLOCK:
Circadian rhythms and the genes that make up the molecular clock have long been implicated in bipolar disorder. Genetic evidence in bipolar patients suggests that the central transcriptional activator of molecular rhythms, CLOCK, may be particularly important. However, the exact role of this gene in the development of this disorder remains unclear. Here we show that…
clock | April 2, 2007
One of the big questions in circadian research is how does the transcription/translation feedback loop manage to get stretched to such a long time-frame: 24 hours. If one took into account the normal dynamics of transcription and translation, the cycle would last a couple of hours at best. The usual answer is that, probably, interactions with a variety of other cellular components slows down the cycle. And this may be correct in Eukaryotes, but a paper came out a couple of years ago showing that placing three cyanobacterial clock genes and some ATP into a test-tube results in a 24-hour…
clock | March 21, 2007A new paper just came out today on PLoS-Biology: Glucocorticoids Play a Key Role in Circadian Cell Cycle Rhythms. The paper is long and complicated, with many control experiments, etc, so I will just give you a very brief summary of the main finding.
One of the three major hypotheses for the origin of circadian clocks is the need to shield sensitive cellular processes - including cell division - from the effects of UV radiation by the sun, thus relegating it to night-time only:
The cyclic nature of energetic availability and cycles of potentially degrading effects of the sun's ultraviolet…
clock | March 19, 2007It has been known for quite a while now that bipolar disorder is essentially a circadian clock disorder. However, there was a problem in that there was no known animal model for the bipolar disorder.
Apparently that has changed, if this report is to be believed:
"There's evidence suggesting that circadian genes may be involved in bipolar disorder," said Dr. Colleen McClung, assistant professor of psychiatry and the study's senior author. "What we've done is taken earlier findings a step further by engineering a mutant mouse model displaying an overall profile that is strikingly similar to…
clock | March 11, 2007The most exciting thing about this study is that this is, as far as I am aware, the first instance in which it was shown that a circadian clock gene has any effect on sleep apart from timing of it, i.e., on some other quality or quantity of sleep (not just when to fall asleep and wake up, but also the depth of sleep and the amount of sleep need):
Performing Under Sleep Deprivation: Its In Your Genes:
People are known to differ markedly in their response to sleep deprivation, but the biological underpinnings of these differences have remained difficult to identify.
Researchers have now found…
clock | March 3, 2007This news just came in:
Charles F- Ehret died of natural causes on February 24th at his home in Grayslake, Illinois, a suburb of Chicago.
His Wikipedia entry is quote short:
Charles Frederick Ehret is a WWII veteran (Battle of the Bulge/Ardennes along the Siegfried Line) as well as a world renowned molecular biologist who worked at Argonne National Laboratory (ANL) in Lemont, Illinois, USA, for 40 years. Dr. Ehret researched the effects of electromagnetic radiation on bacillus megaterium with Dr. Edward Lawrence (Larry) Powers, as well as the effects of time shifts on paramecia, rats and…
clock | February 28, 2007This is a story about two mindsets - one scientific, one not - both concerned with the same idea but doing something very different with it. Interestingly, both arrived in my e-mail inbox on the same day, but this post had to wait until I got out of bed and started feeling a little bit better.
First, just a little bit of background:
Circadian oscillations are incredibly robust, i.e., resistant to perturbations and random noise from the environment. Ricardo Azevedo has described one model that accounts for such robustness in his two-part post here and here and others have used other methods…
clock | February 10, 2007There are several journals dedicated to biological rhythms or sleep. Of those I regularly check only two or three of the best, so I often miss interesting papers that occur in lower-tier journals. Here is one from December 2006 that caught my eye the other day:
Mammalian activity - rest rhythms in Arctic continuous daylight:
Activity - rest (circadian) rhythms were studied in two species of Arctic mammals living in Arctic continuous daylight with all human-induced regular environmental cues (zeitgebers) removed. The two Arctic species (porcupine and ground squirrel) lived outdoors in large…
clock | February 5, 2007Two interesting papers came out last week, both using transgenic mice to ask important questions about circadian organization in mammals. Interestingly, in both cases the gene inserted into the mouse was a human gene, though the method was different and the question was different:
Turning a Mouse Into A Lark
The first paper (Y. Xu, K.L. Toh, C.R. Jones, J.-Y. Shin, Y.-H. Fu, and L.J. PtáÄekModeling of a Human Circadian Mutation Yields Insights into Clock Regulation by PER2. Cell, Vol 128, 59-70, 12 January 2007) is concerned with the human clock mutation that is responsible for FASBS (…
clock | January 31, 2007In light of my post earlier today about the discrepanices between 'real time' and 'clock time' (or 'social time'), it is heartening that the Parliament in the U.K. wisely decided not to switch their clocks to the time the rest of Europe observes. If they did, they would be seriously out of whack. After all, at Zero Meridian in Greenwich (yup, I stood astride it, of course), midnight is really midnight - it is the middle of the time zone. Resetting it by one hour would put the Brits at the far Western edge of another time zone and they would always experience true midnight a long time (60-…
clock | January 31, 2007While study of Time-Perception is, according to many, a sub-discipline of chronobiology, I personally know very little about it. Time perception is defined as interval timing, i.e., measuring duration of events (as opposed to counting, figuring which one of the two events happened first and which one second, or measuring time of day or year).
Still, since this blog is about all aspects of biological timing, I have to point you to a new paper in Neuron (press release) about a new computer model for human time-perception.
"If you toss a pebble into a lake," he explained, "the ripples of water…
clock | January 31, 2007
If you really read this blog "for the articles", especially the chronobiology articles, you are aware that the light-dark cycle is the most powerful environmental cue entraining circadian clocks. But it is not the only one. Clocks can also be entrained by a host of other ("non-photic") cues, e.g., scheduled meals, scheduled exercise, daily dose of melatonin, etc.
Clocks in heterothermic ("cold-blooded") animals can also entrain to temperature cycles. Lizards can entrain to temperature cycles (pdf) in which the difference between nightime low and daytime high temperatures is as small as…