Category Archives: Clock Tutorials

Persistence In Perfusion

Blogging on Peer-Reviewed Research

Persistence In PerfusionThis post, from January 25, 2006, describes part of the Doctoral work of my lab-buddy Chris.

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Phase-Response Curve and T-Cycles: Clocks and Photoperiodism in Quail

Phase-Response Curve and T-Cycles: Clocks and Photoperiodism in QuailThis 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 decided to do some more for my Masters Thesis.
The obvious next thing to do was to expose the quail to T-cycles, i.e., non-24h cycles. This is some arcane circadiana, so please refer to the series of posts on entrainment from yesterday and the two posts on seasonality and photoperiodism posted this morning so you can follow the discussion below:
There were three big reasons for me to attempt the T-cycle experiment at that time:

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How eyes talk to each other?

How eyes talk to each other?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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Quail: How many clocks?

Quail:  How many clocks?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 be a higher-level property of interacting multicellular and multi-organ circadian systems: how the clocks receive environmental information, how the multiple pacemakers communicate and synchronize with each other, how they convey the temporal information to the peripheral clocks in all the other cells in the body, and how peripheral clocks generate observable rhythms in biochemistry, physiology and behavior.

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Chossat’s Effect in humans and other animals

Chossat's Effect in humans and other animalsThis 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 anyone’s Thesis. My advisor designed it and started the experiment with the first couple of birds. When I joined the lab, I did the experiment in an additional number of animals. When Chris joined the lab, he took over the project and did the rest of the lab work, including bringing in the idea for an additional experiment that was included, and some of the analysis. We all talked about it in our lab meetings for a long time. In the end, the boss did most of the analysis and all of the writing, so the order of authors faithfully reflects the relative contributions to the work.
What is not mentioned in the post below is an additional observation – that return of the food after the fasting period induced a phase-shift of the circadian system, so we also generated a Phase-Response Curve, suggesting that food-entrainable pacemaker in quail is, unlike in mammals, not separate from the light-entrainable system.
Finally, at the end of the post, I show some unpublished data – a rare event in science blogging.

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Clock Tutorial #16: Photoperiodism – Models and Experimental Approaches

Clock Tutorial #16:  Photoperiodism - Models and Experimental ApproachesThis post (written on August 13, 2005) describes the basic theory behind photoperiodism and some experimental protocols developed to test the theory.

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Does circadian clock regulate clutch-size in birds? A question of appropriateness of the model animal.

 Does circadian clock regulate clutch-size in birds? A question of appropriateness of the model animal.This post from March 27, 2006 starts with some of my old research and poses a new hypothesis.

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