clock news
clock | January 1, 2007 If you are interested in the background and recent history of the research on mammalian SCN in line of Erik Herzog's work I described in VIP synchronizes mammalian circadian pacemaker neurons and A Huge New Circadian Pacemaker Found In The Mammalian Brain, you may want to look at these old Circadiana posts as well:
-----------------------------Cutting Edge: Circadian Rhythm of Astrocytes (February 02, 2005):
Erik has done it again. He is not one to publish 30 papers per year, but whenever he publishes one, it always gives me the chills and thrills! What beautiful science:
Circadian Rhythm…
clock | December 20, 2006Memory Experts Show Sleeping Rats May Have Visual Dreams:
Matthew A. Wilson, professor of brain and cognitive sciences at MIT's Picower Institute for Learning and Memory, and postdoctoral associate Daoyun Ji looked at what happens in rats' brains when they dream about the mazes they ran while they were awake.
In a landmark 2001 study, Wilson showed that rats formed complex memories for sequences of events experienced while they were awake, and that these memories were replayed while they slept--perhaps reflecting the animal equivalent of dreaming.
Because these replayed memories were detected…
clock | December 19, 2006If you really read this blog 'for the articles', you know some of my recurrent themes, e.g., that almost every biological function exhibits cycles and that almost every cell in every organism contains a more-or-less functioning clock. Here is a new paper that combines both of those themes very nicely, but I'll start with a little bit of background first.
Daily Rhythms in Sensory Sensitivity
If almost every biochemical, physiological and behavioral function exhibits daily cycles, it is no surprise that such rhythms have been discovered in sensory sensitivity of many sensory modalities -…
clock | December 13, 2006Now behind the Wall, but plenty of excerpts available in this March 26, 2005 post...
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Ha! The New York Times has this neat article, that is almost half as good as my early (and so far most frequently linked) post "Everything You Always Wanted To Know About Sleep". Here are some excerpts, go read the rest:
The Crow of the Early Bird
THERE was a time when to project an image of industriousness and responsibility, all a person had to do was wake at the crack of dawn. But in a culture obsessed with status--in which every…
clock | December 11, 2006How does that work? (April 03, 2005)
-------------------------------------------------Alcohol 'binges' in rats during early brain development cause circadian rhythm problems
Rats are nocturnal animals and normally begin their activity slightly after darkness sets in. The rats that had been exposed to alcohol began activities slightly before darkness set in.
When normal rats - or for that matter, humans and other animals - are in situations without environmental cues about day and night, the body's circadian clock generally drives behaviors on a cycle slightly greater than 24 hours.…
clock | December 5, 2006
No 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 | November 20, 2006
Often a press release inflates the meaning of a research paper. Here is one example of it (from May 23, 2006):
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From Afarensis, I got a new paper about circadian rhythms in primates: Twenty-four hour rhythmic gene expression in the rhesus macaque adrenal gland (PDF), by Dario Lemos, Jodi Downs and Henryk Urbanski.
The way the study is presented in the press release (now offline!), it sounds like this is a big surprising breakthrough, but I am not too impressed. The work is good and useful, but the findings are far from Earth-shattering.
Using…
clock | November 13, 2006
This post is a relatively recent (May 24, 2006) critique of a PLoS paper.
----------------------------------------------------There is a new study on PLoS - Biology that is getting some traction in the media and which caught my attention because it was supposed to be about circadian rhythms. So, I downloaded the paper and read it through to see what it is really about.
Well, it is a decent study, but, unfortunately, it has nothing to do with circadian rhythms. Many examples of tritrophic relationships involve parasitoids (usually small wasps) being attracted by plant volatiles which are…
clock | November 6, 2006Chronic Jet-Lag Conditions Hasten Death in Aged Mice
Researchers at the University of Virginia have found that aged mice undergoing weekly light-cycle shifts - similar to those that humans experience with jet lag or rotating shift work - experienced significantly higher death rates than did old mice kept on a normal daylight schedule over the same eight-week period. The findings may not come as a great surprise to exhausted globetrotting business travellers, but the research nonetheless provides, in rather stark terms, new insight into how the disruption of circadian rhythms can impact well-…
clock | October 26, 2006
There is nothing easier than taking a bad paper - or a worse press release - and fisking it with gusto on a blog. If you happen also to know the author and keep him in contempt, the pleasure of destroying the article is even greater.
It is much, much harder to write (and to excite readers with) a blog post about an excellent paper published by your dear friends. But I'll try to do this now anyway (after the cut).
Paul Shaw is a friend, and Indrani Ganguli is a good, good, good friend. Faculty and graduate students in biology are usually a pretty smart lot. A subset of those, as self-…
clock | October 24, 2006As the paper linked to in the previous post explains, everything is connected - clocks, sleep, hunger, obesity and diabetes.
An important part of understanding all these interconnections between clocks and food is to understand the food-entrainable clocks, i.e., how timing of meals affects the performance of the circadian clock.
A new paper provides a molecular link between scheduled meals and circadian timing, implicating our old friend PERIOD2 as part of the mechanisms by which timing of the meal entrains the brain clock (but not the mutual entrainment of peripheral clocks):
Circadian gene…
clock | October 19, 2006Randy Nelson is a wonderful person, an engaging speaker and the author of the best textbook on Behavioral Endocrinology. I heard that he is also a great teacher which does not surprise me and he has a talent for attracting some of the best students and postdocs to work in his lab. Oh, by the way, he also does some great research.
For decades, the study of seasonality and photoperiodism was a hustling bustling field, until everyone jumped on the clock-gene bandwagon. Randy Nelson is one of the rare birds to remain in the photoperiodism field, coming out every year with more and more…
clock | October 9, 2006
A January 20, 2006 post placing a cool physiological/behavioral study into an evolutionary context.
There are two main hypotheses - not mutually exclusive - for the adaptive value of having a circadian clock. One is the Internal Synchronization hypothesis, stating that the circadian clock serves to synchronize biochemical and physiological processes within the body. The second is the External Synchronization hypothesis, stating that the circadian clock serves to syncronize the physiology and behavior to the natural environment.
The prediction from the Internal Hypothesis is that circadian…
clock | October 6, 2006Considering that circadian clocks were first discovered in plants, and studied almost exclusively in plants for almost a century before people started looking at animals in the early 20th century, it is somewhat surprising that the molecular aspects of the circadian rhythm generation mechanisms have lagged behind those in insects, vertebrates, fungi and bacteria. It is always nice to see a paper reporting a discovery of a new plant clock gene:
New function for protein links plant s circadian rhythm to its light-detection mechanism:
Plants set their clocks by detecting the light cycle, and…
clock | October 5, 2006Study says no video games on school nights:
According to Dr. Iman Sharif, the results were clear-cut. "On weekdays, the more they watched, the worse they did," said Dr. Sharif. Weekends were another matter, with gaming and TV watching habits showing little or no effect on academic performance, as long as the kids spent no more than four hours per day in front of the console or TV. "They could watch a lot on weekends, and it didn't seem to correlate with doing worse in school," noted Dr. Sharif.
The study was using self-reporting by kids, which has its problems, but is OK in this case, I…
clock | October 4, 2006Since every chemical induces a different response in the body dependent on the time of day when it is administered, I am not surprised that this also applies to caffeine:
A new study at the Université de Montréal has concluded that people drinking coffee to get through a night shift or a night of studying will strongly hurt their recovery sleep the next day. The study published in the current issue of Neuropsychopharmacology was conducted by Dr. Julie Carrier from the Department of Psychology at the Université de Montréal. Dr. Carrier runs the Chronobiology Laboratory at the Hôpital du…
clock | October 2, 2006
From January 20, 2006, on the need to check the model-derived findings in non-model organisms.
There are pros and cons to the prevalent use of just a dozen or so species as standard laboratory models. On one hand, when a large chunk of the scientific community focuses its energies on a single animal, techniques get standardized, suppliers produce affordable equipment and reagents, experiments are more likely to get replicated by other labs, it is much easier to get funding, and the result is speedy increase in knowledge.
On the other hand, there are drawbacks. One is narrow focus which can…
clock | September 25, 2006
A 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…
clock | September 20, 2006Over 1.6 Million Americans Use Alternative Medicine For Insomnia Or Trouble Sleeping:
A recent analysis of national survey data reveals that over 1.6 million American adults use some form of complementary and alternative medicine (CAM) to treat insomnia or trouble sleeping according to scientists at the National Center for Complementary and Alternative Medicine (NCCAM), part of the National Institutes of Health.
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Those using CAM to treat insomnia or trouble sleeping were more likely to use biologically based therapies (nearly 65 percent), such as herbal…
clock | September 19, 2006So, is extreme "larkiness" due to overphosphorilation or underphosphorilation of PERIOD2?
Hypotheses get tested, studies conflict with each other and, in the end, there is a resolution. In this case, we are still waiting for resolution. Science marches on.