Thursday, April 13, 2006

Regeneration

Inspired by some of my friends who have started blogging about their science, I will attempt a few posts to spread awareness(!!!) about cell biology and perhaps a little about developmental biology. Here goes nothing.



Ugh! Now that's a face that only a mother could love. Maybe..not only mothers but also the few scientists who have chosen it as their model organism. It is not a rule that the model organism you work on should be cute but it helps.(first said by Ralph Greenspan). Imagine waking up every morning and thinking "I have to go back to the lab to work on Axolotl" and then that horrendous image would come to mind. I for one would definitely just turn back and go to sleep again.

However this awful creature is making waves though for one thing that it does - regeneration. If you cut off a limb of this amazing animal it can regerate it....completely! Magic!

Not really. Of course it would have a 'developmental program'[a series of events involving the sequential expression and use of proteins for a develpomental event like formation of a wing etc] . Just that the specific developmental program is not known yet. Once that puzzle is cracked it would bring in billions to the person who figures out how this is done. (and you thought there was no money in science!)

The brightest among you would have figured it out why this thing is uber-hot by now. The application of this program either in vitro or in vivo could possibly lead to regeneration of human body parts like a factory.

All paradise and glory but there is catch! (isn't there always?)

Unlike my favourite model organism, (the fruit fly - muuuaaah!) the genetics of axolotl has not yet been well worked out. I am sure it is because of its hideous looks but then no one asked me. It is related to lizards and genetics here is difficult. For good genetics you need a way to make 'bad genes'(mutations for the purists) so that you can study the effects of these 'bad genes'. One way is to hang around and wait till you get a 'bad gene'/mutation that arises spontaneously in the population. The other way is to actually just go in and damage the damn DNA.

Recently scientists have managed to do something like that. They were able to make transgenic Axolotl i.e. they have managed to put some foreign DNA into a wild axolotl. Actually they put GFP into it.

Why GFP? GFP stands for Green Flourescent Protein which is actually a gene from Jellyfish that glows under Ultra-Violet light. The beauty of GFP is that it can be expressed in any organism still it would glow under UV. Therefore, this is a wonderful non-invasive marker for cells that you want to track.

Advantage Axolotl...and now you can track the cell lines with GFP as they develop so that you will be able to follow which cell gives rise to what(the so called cell lineage). So then you can determine in the final regerated limb which cell came from where. Of course this technique can be used to damage DNA to make mutants as well. With this new technique we should be able to figure out soon how axolotl manages to regenerate body parts.

So will be able to order our body parts soon? Don't hold your breath. There is still a long way to go.

P.S. For the nitpickers, axolotl is not the only organism that can 'regenerate', there are also the planaria(lower in the evolutionary ladder and therefore farther from humans), lizards(tails!) and earthworms. In addition, there was one report of a mouse that can completely heal its heart.

(The picture is from here.)

13 comments:

Anonymous said...

well I feel the picture looks cute like a new born baby.

what did you mean by

"For good genetics you need a way to make 'bad genes'(mutations for the purists) so that you can study the effects of these 'bad genes'."

samudrika said...

you must be a scientist then! Of course that pic is one of a mutant. the real things have green skin. could not find a decent pic of that.

To study the effect of a gene you make a defect in that gene and see the external manifestation. not only do you have to make a defect you have to be able to follow the defect in subsequent generations i.e. maintain it so that it is not lost. that is "good genetics"

musafir said...

wow !!! that was some article. I can no longer say I am completely ignorant in biology research, at least I learnt a few things.

Shanta Laishram said...

This is interesting! if regeneration is possible, it will put a question mark on theory of natural selection and survival of fittest!

I have observed that earthworms can live even if you cut into several pieces! Though its not really regeneration, its definitely interesting!

kray said...

that thing looks like stitch!!!!! u know, from lilo and stitch??!!! it sooo does!!!! :D

btw, the GFP tracer thingy sounds really cool!!! could they make subcutaneous uv-luminous tattoos with it?!! :P that'd be like the ultimate party bling!!

Vivek said...

Well I'm confused after reading Shanta's remark. If you cut an earthworm into two pieces, is it that one of the pieces regenerate into a full earthworm? Or, do both of the pieces regenerate the missing parts and we get two earthworms? And is it that a particular organ has to remain intact for regeneration to occur?

Sorry for so many questions, I'm feeling a bit curious!

Shanta Laishram said...

@Vivek

I have seen that even after cutting the earthworm into n>=2 pieces, those parts can move and stay alive like n separate earthworms! I have cut it myself to see that! But I don't know how long they live after that! Also I don't know if it should be called as regeneration!

Nikhil Joshi said...

may I place an order for a well-developed "Brain"?? the only thing, I wish I could have sometime:(

Nice way to spread the awareness....but it adsorbs your popularity...keep in mind :D

samudrika said...

@musafir
Mission accomplished in a way I suppose.

@shanta and vivek
Started reading some stuff on earthworms. apprently whether they survive or not depends on how they are cut. they can regenerate entire heads too!

@shanta
there are interesting implicatoins for evolution. it is belived that the earthworm developed this kind of a system for a specific reason.
think birds and birds pulling worms out of the soil. sometimes worms get stuck and it gets torn into half as the bird tries to pull it out of the soil!
Advantage worm. even after bird takes off with one half of worm, the other half in the soil will regenerate and form a new worm!

@nikhil
you have enough brains already!(on assumption that you do physics in tifr)
but there is something called "too much of a good thing" :)

Nikhil Joshi said...

@samudrika:

hey, this is not fair...I ordered for a "WELL DEVELOPED" brain...which is not guaranteed :(, being in MEI (what was it??)

Shripad said...

Amazing post Samudrika! Wow, biology is so interesting and so much down to earth. I many times feel this pang that Mathematics can not be explained effectively to a layman. Well, perhaps Shanta can explain Number Theory but it would be difficult for a Linear Algebraic Group theorist (like me) to enlighten others about his research subject.

Coming back to the post, this regeneration must be an attempt to survive, as Samudrika explained in the case of earthworm, so there does not seem any contradiction with the theory of natural selection and survival of fittest to me, at least.

Could we call the growing of trees as a regeneration process? If yes, then it would be (perhaps) quite easier to study the regeneration in trees than in an Axolot.

samudrika said...

@nikhil
you already have a well-developed brain, joshi. lets others also have some brain power.

@shripad
thank you. glad that i could get the point across.

trees are difficult things because they have a "cell wall" - a strucuture made of cellulose and lignin which animal dont have. so that complicates things. they dont need well develped blood vessels, bones etc like animals do. therefore they are different.

Aghori said...

urgh ! this creature looks horrible ... plus all this talk of regeneration of body organs makes me think of Pramod Mahajan ... that reminds of his miserable condition, with all the graphic pictures on the newspapers of livers/kidneys/intestines ... almost makes me puke ... and that reminds me of the his villainous brother .. i am reeling ...

Oh my God ! ... what a horrible feeling I got from reading your blog ... mind is a horrible machine !