Molecular and Cell Biology Carnival #5

Welcome to the December 14, 2008 edition of the Molecular and Cell Biology Carnival.

Below the fold, we have a great compilation of entries to share with you.

I would like to start off by reminding you that today marks the beginning of the American Society for Cell Biology's annual conference in San Francisco. Although I won't be there, biowrites, the new blog over at the Journal of Cell Biology, will be covering the main events, so check it out.

Next, Charles Daney who blogs at Science and Reason writes about Non-coding RNA and gene expression. The post covers a recent publication by Kouji Hirota et al. that demonstrates how the transcription of non-coding RNA helps to organize how the genome is packed and thus influences gene expression. In fact I've written a couple of post on the same topic recently. The first post gives a general background on how RNA Polymerase and chromatin talk to eachother, and the second post summarizes the results from Kouji Hirota et al.

My fellow scibling GrrlScientist presents two entries dealing with DNA fingerprinting and ornithology:
Invasive Exotic Species: More than Meets the Eye

Molecular analyses of an exotic invasive parrot species reveals (1) a cryptic species and (2) support for the notion that the pet trade was involved in establishing this invasive species in the USA

and The Evolution of Poisonous Birds

Given this suite of poisonous birds, Dumbacher wondered whether all poisonous birds closely related to each other. Based on morphological characters, it was thought they were closely related, but to learn more about the evolutionary history of this group of birds, it was necessary to reconstruct their relationships based on their DNA.

Next up, Amiya Sarkar who blogs at Physiology physics woven fine presents a pair of entries.
The Molecular Basis of Genetic Switch In The Circadian Clock:

There's a clock in us which counts time by using the genetic machinery. Time keeping is vital to coordinate cellular and environmental functions.

and Fantastic Fluorescence:Brainbow and The Nobel Prize 2008:

Green fluorescent proteins poised to give green signal to various molecular and biological processes.

Speaking of Green Fluorescent protein (aka GFP), 96well, who blogs at Reportergene presents a entry on a very clever study that used chimeric mice generated from the combination of cells expressing GFP with cells expressing lacZ. The researchers used these mice to look for cell fusion. From the entry:

So, by finding single cells expressing both reporters (immuno-histochemistry and single-cell PCR), the italian researchers found that cell fusion is a physiological process not only in muscle, throphoblast and osteoclasts, but also in adult mouse liver. This results finally answers long-lived questions about the origins of hepatic polyploidy, that was believed to occur only following DNA duplication and aborted cytokinesis.

Next we have Giovanna Di Sauro who writes about how healthy people could benefit from statins. To refresh your memory, statins control the level of cholesterol production in the body by inhibiting HMG-CoA reductase, the rate-limiting step of cholesterol synthesis. Specifically she offers some comments on the Jupiter study on the use of rosuvastatin in apparently healthy people.

And finally we have some technical advice from Nick Oswald who blogs at BitesizeBio. In this post, Nick tells you What you need to know about OD600 when measuring the density of your bacterial cultures.

The OD value represents the amount of light that is absorbed by your sample. But that value is affected by the intensity of the light beam in the spec, and the spec design. This means that similar samples will give completely different OD values in different specs due to the specs having different bulbs, or even in the same spec over time, as the beam intensity reduces with the age of the bulb.


What you really want to know from an OD600 reading is the density of the cells e.g. in cells/mL. And to get this you need a standard curve. In other words, like any other spec-based experiment you will ever perform, you need to calibrate the absorbance value against the number you actually want to know.

For some reason, people don't seem to remember this for OD600. I can't think of any other experiment where people record the absorbance value as an absolute number like they do for OD600, but maybe you can think of some - tell me in the comments :).

Very true.

That concludes this edition. Submit your blog article to the next edition of the Molecular and Cell Biology carnival using our carnival submission form. Past posts and future hosts can be found on our blog carnival index page. If you want to host any future editions of the MCB Carnival please contact Steppen Wolf.


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P.S. This is the fifth edition... Great carnival, Alex!

And yes, by all means, contact me if you are interested in hosting. Upcoming carnival dates have been posted on, so all you need to do is to let me know which one you are interested in.

P.S. This is the fifth edition...

Sorry about that. I've just fixed it.