As I announced last week, this week will be All Clocks All The Time. Why?
First, I need to move some of the old posts from Circadiana over here, at a faster rate than I’ve been doing so far. Second, I’ll be quite busy this week. Third, I need to hype myself up for the final effort at my Dissertation so blogging about any other topic would be counter-productive (not that it’s not gonna happen…)
So, here is the deal. Over the next five days I will repost some old and write some new posts on three big topics in Chronobiology: circadian organization, entrainment and photoperiodism. Within each topic, I will start with posts that are basic and general and gradually move towards more and more detailed, or specific, or up-to-date posts (what students call “hard material”), ending with descriptions of some of my own (published only) work in those areas.
Perhaps you should prepare for this by checking out some of the Clock Tutorials that I have already re-posted here. I have started by defining the field in What Is Chronobiology, followed by a post that serves as a dictionary reference to Basic Concepts and Terms.
I have tackled the questions of the origin, evolution and adaptive function of biological clocks twice, from two different angles, in Clock Evolution and Whence Clocks.
You can read about the early history of the field, from the early days until about 1960s, and with heavy emphasis on Darwin’s own work, in Darwin On Time. I followed up the history to a more modern time, and connected it to what we know about clocks, in Forty-Five Years of Pittendrigh’s Empirical Generalizations. Even more recent history, focusing on the molecular findings, you can read about in Clock Genetics – A Short History.
Finally, in order to understand the findings in the field, you need to know how the experiments are designed and why – this tells you about the way chronobiologists think. So, check out On Methodology.
Then, you’ll be ready for this week in clocks.
On Monday (that is, later today), we’ll start tackling Circadian Organization. What are the elements of the circadian system, where are they in the body, how they work, how they get the information from the environment, how they communicate with each other, and how they generate observable, measurable rhythms – those are the questions covered in this section.
I’ll start with a post tackling the general question about circadian organization (longer than the previous sentence). Then, I’ll focus on circadian organization in mammals mainly because it is comparatively simple and serves as a good reference point for comparison to clock systems in other organisms. I’ll only cover the basics, leaving much of complexity and recent findings aside for now. Then, I’ll move to non-mammalian vertebrates and their complicated circadian organization, with emphasis on birds (because we know the most about them). Finally, I’ll get down to nitty-gritty detail in a post about circadian organization in a single species – the Japanese quail, the lab animal model I did all my work on.
On Tuesday, I’ll follow up with one or two posts about the Doctoral research on circadian organization in Japanese quail done by my lab-mate Chris: how the two clocks in two eyes manage to always stay in sync with each other? I will follow that with one or two posts on my own Masters work on retinal and extra-retinal pacemakers and photoreceptors in quail and the question if the (female) quail organization is reducible to one complex circadian system or can be best understood as two separate systems that communicate with each other.
On Wednesday, we move on to Entrainment, with a series of six posts explaining what entrainment is and how it is studied – a tutorial on very simplified physics of (coupled) oscillators, which sounds hard but if you go slowly you will “get it”, I hope.
On Thursday, you will see two posts on the timing of seasonality and photoperiodism – something that depends on the understanding of entrainment from the previous day. Then, I intend to write about some of my own work that combined a study of entrainment with a study of photoperiodism.
Finally, on Friday, I’ll try to put it all together with one new and one old post about the circadian control of body temperature – from physiology and behavior to ecology and evolution, with a tangential look at entrainment by scheduled feedings and the phenomenon of “masking”.
I hope you enjoy this five-day mini-course and find it useful and enlightening. I appreciate all feedback on how to make those posts clearer, more readable and more useful to casual blog-readers and students alike.
This post was originally written on February 11, 2005. Moving from relatively simple mammalian model to more complex systems.
A Blog Around The Clock 