Chronobiology:
Much of the biological research is done in a handful of model organisms. Important studies in organisms that can help us better understand the evolutionary relationships on a large scale tend to be hidden far away from the limelight of...
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Posted on May 13, 2008 8:01 AM • 1 Comments • 0 TrackBacks
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...
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Posted on May 4, 2008 4:53 PM • 3 Comments • 0 TrackBacks
This post from March 27, 2006 starts with some of my old research and poses a new hypothesis....
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Posted on May 4, 2008 7:58 AM • 0 Comments • 0 TrackBacks
You and I, as well as all of our mammalian brethren, have just a few photopigments, i.e., colored molecules that change shape when exposed to light and subsequently trigger cascades of biochemical reactions leading to changes in electrical properties of...
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Posted on May 2, 2008 4:55 PM • 2 Comments • 0 TrackBacks
If 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...
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Posted on May 1, 2008 4:50 PM • 4 Comments • 0 TrackBacks
Since this is another one of the recurring themes on my blog, I decided to republish all of my old posts on the topic together under the fold. Since my move here to the new blog, I have continued to...
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Posted on April 25, 2008 4:56 PM • 3 Comments • 0 TrackBacks
From January 20, 2006, on the need to check the model-derived findings in non-model organisms....
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Posted on April 23, 2008 4:20 PM • 0 Comments • 0 TrackBacks
This is a summary of my 1999 paper, following in the footsteps of the work I described here two days ago. The work described in that earlier post was done surprisingly quickly - in about a year - so I...
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Posted on April 21, 2008 4:55 PM • 1 Comments • 0 TrackBacks
One of the important questions in the study of circadian organization is the way multiple clocks in the body communicate with each other in order to produce unified rhythmic output....
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Posted on April 20, 2008 4:51 PM • 0 Comments • 0 TrackBacks
One of the assumptions in the study of circadian organization is that, at the level of molecules and cells, all vertebrate (and perhaps all animal) clocks work in roughly the same way. The diversity of circadian properties is understood to...
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Posted on April 19, 2008 4:55 PM • 1 Comments • 0 TrackBacks
How birds know when and where to migrate (from April 03, 2006)...
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Posted on April 18, 2008 4:59 PM • 2 Comments • 0 TrackBacks
A January 20, 2006 post placing a cool physiological/behavioral study into an evolutionary context....
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Posted on April 17, 2008 4:52 PM • 0 Comments • 0 TrackBacks
As traveling is not conducive to vigorous blogging (apart from posting travelogue pictures), I have asked a couple of friends to write guest posts here. The first to step up to the plate is Anne Marie who put together her...
Posted on April 17, 2008 10:58 AM • 1 Comments • 0 TrackBacks
This post, from January 25, 2006, describes part of the Doctoral work of my lab-buddy Chris....
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Posted on April 14, 2008 4:56 PM • 0 Comments • 0 TrackBacks
Being out of the lab, out of science, and out of funding for a while also means that I have not been at a scientific conference for a few years now, not even my favourite meeting of the Society for...
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Posted on April 12, 2008 4:27 PM • 1 Comments • 0 TrackBacks
From the Harvard Division of Sleep Medicine: To honor the distinguished career of Professor Richard Kronauer, we will again award the Richard E Kronauer Prize for Excellence in Biomathematical Modeling. This is presented to a graduate student or post-doctoral fellow...
Posted on April 10, 2008 10:31 AM • 0 Comments • 0 TrackBacks
This post is perhaps not my best post, but is, by far, my most popular ever. Sick and tired of politics after the 2004 election I decided to start a science-only blog - Circadiana. After a couple of days...
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Posted on April 7, 2008 4:57 PM • 2 Comments • 0 TrackBacks
It has been almost three years since I promised to write a post detailing the photoperiodic response in mammals. (Birds are more complicated). Now Shelley gives a good example - the snowshoe hare which changes color annually: it is dark...
Posted on March 5, 2008 9:33 PM • 0 Comments • 0 TrackBacks
The 11th Biennial Meeting of the Society for Research on Biological Rhythms will be held in Sandestin, FL on May 17th-21st, 2008. And I'll be there. This meeting occurs every two years (on even-numbered years, the International Congress and...
Posted on March 2, 2008 6:24 PM • 0 Comments • 0 TrackBacks
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...
Posted on February 14, 2008 6:37 PM • 0 Comments • 0 TrackBacks
Keystone sleep/circadian meeting. Jay Dunlap, Emmanuel Mignot and Amita Seghal are organizing a Keystone meeting on Genetics and Biochemistry of Sleep in Lake Tahoe, March 7-12 (click here to see large):...
Posted on January 28, 2008 9:16 AM • 0 Comments • 0 TrackBacks
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...
Posted on January 7, 2008 8:14 PM • 1 Comments • 0 TrackBacks
On Pilobolous: When I first wrote my post on Pilobolus (here and here) I really wanted to do something extra, which I could not do at the time. If you scroll down that post, you will see I reprinted the...
Posted on December 23, 2007 12:51 AM • 0 Comments • 0 TrackBacks
I 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...
Posted on October 24, 2007 9:45 PM • 31 Comments • 0 TrackBacks
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...
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Posted on September 27, 2007 1:19 PM • 5 Comments • 0 TrackBacks
A post-doctoral position is available in the laboratory of Dr. Tosini to investigate the cellular and molecular mechanisms that control circadian rhythms in the mammalian retina [Tosini et al., (2007) Faseb J.; Sakamoto et al., (2004). J. Neuroscience 24: 9693-9697;...
Posted on September 20, 2007 8:01 PM • 0 Comments • 0 TrackBacks
Circadian 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...
Posted on September 19, 2007 2:34 PM • 0 Comments • 0 TrackBacks
NBM found an excellent online article (which I have seen before but I forgot) depicting Phase-Response Curves (PRC) to injections of melatonin in humans, rodents and lizards. Note how the shape is roughly opposite to that of a PRC to...
Posted on August 12, 2007 10:34 PM • 1 Comments • 0 TrackBacks
Sometimes a metaphor used in science is useful for research but not so useful when it comes to popular perceptions. And sometimes even scientists come under the spell of the metaphor. One of those unfortunate two-faced metaphors is the metaphor...
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Posted on August 10, 2007 4:52 PM • 7 Comments • 0 TrackBacks
This post from March 27, 2006 starts with some of my old research and poses a new hypothesis....
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Posted on August 3, 2007 4:56 PM • 0 Comments • 0 TrackBacks
This post is a modification from two papers written for two different classes in History of Science, back in 1995 and 1998. It is a part of a four-post series on Darwin and clocks. I first posted it here...
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Posted on August 3, 2007 8:52 AM • 0 Comments • 0 TrackBacks
This post about the origin, evolution and adaptive fucntion of biological clocks originated as a paper for a class, in 1999 I believe. I reprinted it here in December 2004, as a third part of a four-part post. Later, I...
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Posted on August 2, 2007 8:51 AM • 0 Comments • 0 TrackBacks
This post, originally published on January 16, 2005, was modified from one of my written prelims questions from early 2000....
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Posted on August 1, 2007 8:59 AM • 0 Comments • 0 TrackBacks
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...
Posted on July 31, 2007 1:57 PM • 1 Comments • 0 TrackBacks
This post, from January 25, 2006, describes part of the Doctoral work of my lab-buddy Chris....
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Posted on July 30, 2007 4:53 PM • 0 Comments • 0 TrackBacks
First written on March 04, 2005 for Science And Politics, then reposted on February 27, 2006 on Circadiana, a post about a childrens' book and what I learned about it since....
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Posted on July 29, 2007 4:57 PM • 6 Comments • 0 TrackBacks
Being out of the lab, out of science, and out of funding for a while also means that I have not been at a scientific conference for a few years now, not even my favourite meeting of the Society for...
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Posted on July 28, 2007 4:52 PM • 3 Comments • 0 TrackBacks
Hypotheses leading to more hypotheses (from March 19, 2006 - the Malaria Day):...
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Posted on July 26, 2007 4:57 PM • 3 Comments • 0 TrackBacks
This April 09, 2006 post places another paper of ours (Reference #17) within a broader context of physiology, behavior, ecology and evolution. The paper was a result of a "communal" experiment in the lab, i.e., it was not included in...
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Posted on July 24, 2007 4:50 PM • 0 Comments • 0 TrackBacks
This is an appropriate time of year for this post (February 05, 2006)......
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Posted on July 22, 2007 8:56 AM • 3 Comments • 0 TrackBacks
A January 20, 2006 post placing a cool physiological/behavioral study into an evolutionary context....
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Posted on July 21, 2007 4:55 PM • 0 Comments • 0 TrackBacks
Well, it's Thanksgiving tomorrow night so it's time to republish this post from last year, just in time for the ageless debate: does eating turkey meat make you sleepy? Some people say Yes, some people say No, and the debate...
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Posted on July 21, 2007 8:52 AM • 1 Comments • 0 TrackBacks
You probably realize by now that my expertise is in clocks and calendars of birds, but blogging audience forces me to occasionally look into human clocks from a medical perspective. Reprinted below the fold are three old Circadiana posts about...
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Posted on July 14, 2007 4:54 PM • 1 Comments • 0 TrackBacks
A short post from April 17, 2005 that is a good starting reference for more detailed posts covering recent research in clock genetics (click on spider-clock icon to see the original)....
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Posted on July 13, 2007 8:53 AM • 0 Comments • 0 TrackBacks
A 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...
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Posted on July 12, 2007 4:59 PM • 0 Comments • 0 TrackBacks
Chad wrote a neat history of (or should we say 'evolution of') clocks, as in "timekeeping instruments". He points out the biological clocks are "...sort of messy application, from the standpoint of physics..." and he is right - for...
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Posted on July 11, 2007 4:53 PM • 1 Comments • 0 TrackBacks
"Is sunshine good for you?" is the latest Ask a ScienceBlogger question and Nick Anthis did a great job answering it - focusing on the circadian aspects of the need for sunlight - in his response here. Excellent and quite...
Posted on June 19, 2007 2:01 PM • 1 Comments • 0 TrackBacks
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....
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Posted on June 15, 2007 3:51 PM • 1 Comments • 0 TrackBacks
Back in the late 1990s, when people first started using various differential screens, etc. looking for elusive "genes for sleep", I wrote in my written prelims (and reprinted it on my blog several years later): Now the sleep researchers are...
Posted on May 26, 2007 7:11 PM • 0 Comments • 0 TrackBacks
When it's someone's birthday it is nice to give presents, or a flower. Perhaps a whole boquet of roses. But if the birthday is a really big round number, like 300, and the birthday boy is the one who actually...
Posted on May 23, 2007 6:30 PM • 3 Comments • 0 TrackBacks
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...
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Posted on May 22, 2007 11:54 AM • 3 Comments • 0 TrackBacks
Far too gene-centered for my taste, but an excellent chronobiology primer (pdf) nonetheless....
Posted on May 21, 2007 8:42 AM • 1 Comments • 0 TrackBacks
Review of some very cool new papers on Drosophila circadian clocks
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Posted on May 19, 2007 12:56 AM • 2 Comments • 0 TrackBacks
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...
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Posted on May 7, 2007 2:42 AM • 6 Comments • 0 TrackBacks
One 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...
Posted on May 1, 2007 4:09 PM • 1 Comments • 0 TrackBacks
Thus 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...
Posted on April 26, 2007 6:00 PM • 8 Comments • 0 TrackBacks
Cold Spring Harbor 72nd Symposium: Clocks & Rhythms, May 30 - June 4, 2007. Abstract deadline is way past due, but just to go and be there (and blog from there) would be super-awesome....
Posted on April 25, 2007 3:31 PM • 0 Comments • 0 TrackBacks
This 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,...
Posted on April 22, 2007 1:06 PM • 7 Comments • 0 TrackBacks
Yup, that was going to be the title of this post. I got the paper and was ready to write the post when I noticed that Peter scooped me and posted about the same paper today (yup, there is just...
Posted on April 20, 2007 4:57 PM • 1 Comments • 0 TrackBacks
It is Marine Megavertebrate Week right now, so why not take a look at one of the most Mega of the Megaverts - the grey whale (Eschrichtius robustus): Do whales sleep? You may have heard that dolphins do - one...
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Posted on April 18, 2007 1:06 PM • 5 Comments • 0 TrackBacks
I 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...
Posted on April 12, 2007 9:00 AM • 0 Comments • 0 TrackBacks
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...
Posted on April 2, 2007 10:58 AM • 0 Comments • 0 TrackBacks
Apparently, in Denmark, the 'larks' (early-risers) are called 'A-people' while 'owls' (late-risers) are 'B-people'. We all know how important language is for eliciting frames, so it must feel doubly insulting for the Danish night owls. Today, in the age of...
Posted on March 23, 2007 2:21 PM • 4 Comments • 0 TrackBacks
A 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...
Posted on March 21, 2007 12:24 PM • 3 Comments • 0 TrackBacks
I have written about the relationship between circadian clocks and food numerous times (e.g., here, here and here). Feeding times affect the clock. Clock is related to hunger and obesity. Many intestinal peptides affect the clock as well. There is...
Posted on March 20, 2007 4:49 PM • 1 Comments • 0 TrackBacks
It 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...
Posted on March 20, 2007 2:29 AM • 0 Comments • 0 TrackBacks
