clock news

Circadian Clock May Be Critical For Remembering What You Learn, Researchers Say: The circadian rhythm that quietly pulses inside us all, guiding our daily cycle from sleep to wakefulness and back to sleep again, may be doing much more than just that simple metronomic task, according to Stanford researchers. Working with Siberian hamsters, biologist Norman Ruby has shown that having a functioning circadian system is critical to the hamsters' ability to remember what they have learned. Without it, he said, "They can't remember anything." Time Of Day Influences Yield For Pharmacologically…
The October issue of the Journal of Biological Rhythms came in late last week - the only scientific journal I get in hard-copy these days. Along with several other interesting articles, one that immediately drew my attention was Clock Gene Wikis Available: Join the 'Long Tail' by John B. Hogenesch and Andrew I. Su (J Biol Rhythms 2008 23: 456-457.), especially since John Hogenesh and I talked about it in May at the SRBR meeting. Now some of you may be quick to make a connection between this article and its author Andrew Su and A Gene Wiki for Community Annotation of Gene Function, published…
Glow worms glimmer on cue: University of Queensland researcher and lecturer Dr David Merritt has discovered that Tasmanian cave glow-worms are energy conservationists: they switch their lights off at night-time. The discovery was made during a partially funded UQ Firstlink study, which revealed that the glow-worm's prey-luring light output is governed by circadian rhythms, regardless of ambient light levels. The study aimed to investigate the physiology and behaviours of cave dwelling glow-worms, which are actually the immature or larval stage of a mosquito-like fly found in Queensland, New…
Believe it or not, this appears to have something to do with their circadian rhythms! Back in the 1960s and early 1970s, there was quite a lot of research published on the circadian rhythms in earthworms, mostly by Miriam Bennett. As far as I can tell, nobody's followed up on that work since. I know, from a trusted source, that earthworms will not run in running-wheels, believe it or not! The wheels were modified to contain a groove down the middle (so that the worm can go only in one direction and not off the wheel), the groove was covered with filter paper (to prevent the worm from…
Grand Rounds (4) 38 are up on NHS Blog Doctor The latest Homeschooling Carnival is up in The Common Room.
Today in PLoS Genetics: a nice review of some interest to my readers: When Clocks Go Bad: Neurobehavioural Consequences of Disrupted Circadian Timing by Alun R. Barnard and Patrick M. Nolan: Progress in unravelling the cellular and molecular basis of mammalian circadian regulation over the past decade has provided us with new avenues through which we can explore central nervous system disease. Deteriorations in measurable circadian output parameters, such as sleep/wake deficits and dysregulation of circulating hormone levels, are common features of most central nervous system disorders. At…
In the Journal of Circadian Rhythms: A new approach to understanding the impact of circadian disruption on human health (pdf): Background Light and dark patterns are the major synchronizer of circadian rhythms to the 24-hour solar day. Disruption of circadian rhythms has been associated with a variety of maladies. Ecological studies of human exposures to light are virtually nonexistent, however, making it difficult to determine if, in fact, light-induced circadian disruption directly affects human health. Methods A newly developed field measurement device recorded circadian light exposures…
A couple of days have passed and I had a lot of work-related stuff to catch up with, but I thought I better write a recap now while the iron is still hot and I remember it all. Here we go.... Surprise #1 Last time I went to a SRBR meeting (or for that matter any scientific meeting) was in 2002. I started my first blog in 2004. I started writing about science, specifically about Chronobiology, in January of 2005. Before last week's meeting I knew of one chronobiologist who reads my blog regularly. I knew of one other chronobiologist who contacted me to ask to use some of the material for…
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…
I got several e-mails yesterday about a new study about the molecular mechanism underlying circadian rhythms in mammals ("You gotta blog about this!"), so, thanks to Abel, I got the paper (PDF), printed it out, and, after coming back from the pool, sat down on the porch to read it. After reading the press releases, I was in a mind-frame of a movie reviewer, looking for holes and weaknesses so I could pounce on it and write a highly critical post, but, even after a whole hour of careful reading of seven pages, I did not find anything deeply disturbing about the paper. Actually, more I read…
To sleep or not to sleep: the ecology of sleep in artificial organisms: We systematically varied input parameters related to the number of food and sleep sites, the degree to which food and sleep sites overlap, and the rate at which food patches were depleted. Our results reveal that: (1) the costs of traveling between more spatially separated food and sleep clusters select for monophasic sleep, (2) more rapid food patch depletion reduces sleep times, and (3) agents spend more time attempting to acquire the 'rarer' resource, that is, the average time spent sleeping is positively correlated…
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…
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, exactly…
Two interesting papers came out last week [from the Archives - click on the clock logo to see the original post], 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…
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…
'Fiona' Gene Controls Flower's Physiologic Clock: Scientists have found a new gene that regulates the daily and yearly physiological cycles of flowering and seeding. POSTECH researchers, led by Nam Hong-gil and Kim Jeong-sik, said that they named the gene FIONA1 after the heroine in the popular animation ``Shrek.'' In the animation, princess Fiona is human by day but becomes an ogress at sunset. Fiona also sounds similar to the term ``flowering'' in Korean. The research is a foundation for further discoveries of the plants' clock systems, the team said. To study the gene, the POSTECH team…
I found two articles interesting to me in today's issue of PLoS Computational Biology - the first one about becoming a good scientist, the other on circadian rhythms: On the Process of Becoming a Great Scientist: In the vein of promoting further debate and discussion, I provide here a different and perhaps deeper look at what makes a successful scientist. While I can't claim to have the reputation of Hamming, I grew up in a family of well-known scientists, and have had plenty of chances to observe the trajectories of scientific careers over my lifetime. Based on that experience, I propose the…
Washington Post has an article on how to plant your own floral clock, just like the one built by Linnaeus.
It's rare that an article combines my two interests - in biological clocks and politics. This one does: Circadian rhythms differ for the king and the president: One is a night owl who likes to do business after midnight. The other is an early-to-bed guy who brags about going to sleep around 9:30 p.m. Uh-oh. One of them is King Abdullah of Saudi Arabia. The other is President Bush. So what happens when the president comes calling on the king? Call it the battle over bedtime. What the article fails to mention is that 9pm in Saudi Arabia is NOT 9pm for Bush. He just flew there. His internal…
I had no time to read this in detail and write a really decent overview here, perhaps I will do it later, but for now, here are the links and key excerpts from a pair of exciting new papers in PLoS Biology and PLoS ONE, which describe the patterns of expression of a second type of cryptochrome gene in Monarch butterflies. This cryptochrome (Cry) is more similar to the vertebrate Cry than the insect Cry, also present in this butterfly. The temporal and spatial patterns of expression of the two types of Cry suggest that they may be involved in the transfer of time-information from the…