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Biological Clocks in Protista

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I originally published this post on July 4, 2006.

Writing a chronobiology blog for a year and a half now [see note above - this was written in 2006] has been quite a learning experience for me. I did not know how much I did not know (I am aware that most of my readers know even less, but still….). Thus, when I wrote about clocks in birds I was on my territory – this is the stuff I know first-hand and have probably read every paper in the field. The same goes for topics touching on seasonality and photoperiodism as my MS Thesis was on this topic.

I feel equally at home when discussing evolution of clocks. I am also familiar with the clocks in some, but not all, arthropods. And that is all fine and well….but, my readers are anthropocentric. They want more posts about humans – both clocks and sleep – something I knew very little about. So, I have learned a lot over the past year and a half by digging through the literature and books on the subject. I was also forced to learn more about the molecular machinery of the circadian clock as most newsworthy (thus bloggable) new papers are on the clock genetics.

Acetabularia

Acetabularia

I know almost nothing about clocks in plants, fungi or fish, for instance, but I intend to learn – both for my own sake and for the sake of my blog readers. Actually, I started digging through the literature taxon by taxon some while ago, pretty much on two tracks: one covering the Invertebrates (like this and this), the other on microorganisms.

It is interesting to see how much I have regurgitated textbook dogma and conference hallway “truths” in my initial post on the clocks in microorganisms, only to have to contradict myself once I actually delved into the literature and learned for myself (see the series here: one, two, three, four and five).

Chlamydomonas

Chlamydomonas

I bet the same thing is going to happen next, as I am embarking on the literature on the clocks in Protista. I wish I could have a copy of Cellular and Molecular Bases of Biological Clocks: Models and Mechanisms for Circadian Timekeeping by Leland N. Edmunds, an excellent book that contains a lot of information on the clocks in protists. However, it is expensive, and although it is on my amazon wish list, I doubt anyone will splurge on it for me.

So, over the next couple of months, expect a series of posts on the clocks in protists. From the old textbooks and conference lore, I believe that one of the first (if not THE first) circadian mutation was discovered in the Chlamydomonas, belonging to the group of green algae (recently moved into the Kingdom Plantae, but I will treat it as a Protist for the purposes of my series) which was an important laboratory model early in the development of the field.

Euglena

Euglena

People like Leland Edmunds have worked out a lot of cell biology of clocks in the Paramecium (Ciliata) and Euglena (Flagellates).

The most astonishing results came from some 1950s studies in the Acetabularia, another green alga, in which rhythms persisted in the absence of the cell nucleus. The studies were repeated in early 1990s, yet to this day there is no good explanation of the findings – I am looking forward to reviewing that part!

Starting on my literature search, I discovered that some work was also done on Rhodophyta (red algae), e.g., this and this.

Gonyalax

Gonyalax polyedra

Most of the work in protists, however, was performed on Lingulodinium polyedrum, much better known by its old name Gonyaulax polyedra. It was initially studied by one of the pioneers of chronobiology, J.Woodland Hastings. ‘Woody’, as he was known, had many graduate students who, after leaving his lab, took Gonyaulax with them and did further research for many years. Several very important findings, with implications for the whole field of chronobiology, came out of that research on Gonyaulax.

Unfortunately, the way science funding is going these days, when even fruitfly researchers are complaining, little to no research is currently done on clocks in protista – all those researchers have moved to mice and rats in order to get their work funded. I hope this situation changes in the future. Protists are such a huge and diverse group of organisms, they are bound to keep many cool secrets we should try to uncover.






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  1. 1. N a g n o s t i c 9:32 am 03/13/2012

    Perhaps Lynn Margulis’ ideas about bacteria’s role in the development and function of more “advanced” life can aid in the pursuit of answers to these questions.

    Link to this

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