Tuesday, January 18, 2011

p21 and regeneration.

A few days ago an article did the rounds on the regeneration of limbs in mammals being possible with the deleteion of a single gene. It's been known for some time that the humans have all the genes neccesary for limb regeneration, a set of genes very similar to lizards that can regenerate. The major difference being that when we lose a limb, the genes don't turn on.

A group from the Wistar Institute have published details of p21 knockout mice that appear to be able to regenerate limbs. p21 is a gene involved in the regulation of the cell cycle. There are various cyclin dependent kinases (CDK) floating around in a cell that help move a cell from a state of growth to a state of homeostasis and vice cersa. p21 binds to some of these CDK's and prevents the cell from moving into a growth phase. So by knocking out this gene in mice, the researchers appear to have been able to allow growth to move forward and the correct form of growth to progress to allow for limb regeneration.

The trouble with this is the p21 is part of the p53-tumour suppressor pathway. Basically, the p53 gene is turned on in response to DNA damage, which turns on p21 which in turn blocks the cell from replicating. Ideally, you do not want a cell to grow and replicate if it is damaged, so this a good thing. In fact, a damaged p53 gene is quite common in a variety of cancers, when the mechanism to stop damaged cells replicating is damaged, things go a little haywire and the damaged cells, can become cancerous.

Thursday, January 13, 2011

Required reading

And here I am two days later with a nice example of meta blogging. A minor one maybe, but an example none the less. And some required reading. A week or so ago, xkcd mentioned wikipedia's list of common misconceptions. Aha! I thought to myself, that sounds like fun, I'll go have a quick glance. And lo, it was fun. I know I'm not the only reader of the magnificence that is xkcd, but it's intriguing to watch the list opo up in various other places. Admitedly only on two science blogs so far, which corresponds roughly with xkcd's audience, but still.

As for the list itself? Marvelous. A lot of them I was aware of, some of them I wasn't. Some of them were things that have bugged me for ages, and it's nice to know I had due cuase. Like the vomitoria of the Romans. While I'm quite happy to believe that the Romans threw the odd fairly signifcant party or two, the idea of having specially made buckets to vomit in lacks a certain amount basic ... class. I join xkcd in suggesting that the list should be required reading.

Tuesday, January 11, 2011

The meta-blogsphere.

One thing I've been noticing of late is the cycling of the topics in the blogosphere. Over the course of several days, if one has enough rss feeds, you can see a topic building, being talked about and then fading. No solutions, or very rarely a solution, just discussion that washes a topic up on the beach where it is left to dry out and go pale in the sun.

I shouldn't really find it odd though. The blogosphere, I don't think, was ever intended as a method of producing solutions, merely a place for topics to be chewed over and maybe have a few new people made aware of them. At the moment, being a holiday season, there are very few things making waves, the only thing I can see bouncing about at the moment is the shooting of the US congress woman Gabrielle Giffords and even that isn't making huge waves in the science/skeptically leaning blogs.

I do rather wish I could recall examples from last year, some of which I consciously picked as topics at the time. Perchance I'll be a little better at recording them this year. It does make interesting watching. And reinforces a sense of place as to where one sits in the flow of opinion. For me, I've got an odd little corner place with views onto the conversations around biology and science in general, with skeptical, science, atheist and craft conversations flowing around that.


Friday, January 7, 2011

The correct making of a good cup of tea.

Only last night, I was sitting on a beach with a badly made cup of tea after a night swim talking about this. And lo, dear old Chirstopher Hitchens writes an article on slate that eventually leads me here. As Hitchens says, some of these rules are a little ... strict. I would hazard that rule one is somewhat optional, as is the final, eleventh rule. Otherwise, they're all pretty much mandatory. I see Jerry Coyne has also found the article, though he does have some funny ideas on the correct use of a biscuit. Dunking chocolate biscuits in tea? That's just wrong. Ideally you want a gingernut for dunking (no more than 2 dunks), something nice and hard that isn't going to dissolve in your tea. Though he is quite right about the neccesity of a biscuit (or a piece of fruit cake) to go alongside a good cup of tea. Garibaldis are a fine choice, just not for dunking.

Sitting on the beach with my sad cup of tea made from hot-ish water out of a Thermos, it was brought to mind how important it is to have boiling water though at the time I couldn't recall why. It comes back to tea being a herbal infusion, which doesn't release all of it's lovely flavours without being at 100oC. Reminds me of walks in the bush with Dad when he was guiding tramping clubs from the city. They would all pull out their thermos and make sub-standard tea or vile instant coffee. Dad would pull out the white spirits burner and teh billy, put some water on and boil it up then and there. Extra strong, hot billy tea. With a gingernut.