Whoa!! Really?? How long does this ability last?
Yeah, that was about my reaction as well…
WHO said that?!
Nickrz -
It’s this week’s mailbag topic. Here’s the link: http://www.straightdope.com/mailbag/mnewlimb.html
And I was amused by that comment as well. Wish I’d known that when I burned the hell out of my arm when I was a baby - regenerating the arm would have helped! < g >
Kind of makes the circumcision debate moot…
Although it’s probably obvious, I go ahead and elaborate on Alphagene’s response because I had a blinding flash of the obvious a couple of minutes ago and, dammit, I intend to share it.
I was circumsized shortly after birth (maybe I should word that differently - ah, hell with it). OK, so let’s take a look here … nope, the foreskin is still gone. Based on that newborn baby regenerating a finger thing, Mr. Happy should’ve regrown his hood.
Actually, the finger regrowth in small children is on the order of the last joint only, not the whole finger. I guess I should’ve been more explicit.
Doug, thanks for clarifing that before we had the chance to perform horrible, cruel experiments. 
How much of the final joint?
Another SD tragedy averted?
(Aside to Falcon - I knew that, I was just underscoring the need for my fellow mod’s policy on posting links).
All right, I got the hint. Sorry I forgot to include the link. This is my first time posting in the Mailbag forum. I feel just awful. 
Sheesh! You try and be helpful, and find out someone didn’t need help at all. Oh well…
[[If a newborn baby loses a finger, it will regenerate…]]
My - obvious - question is what happens when you give somebody the finger?
I think the “flexibility” Doug is talking about is what the cloning researchers managed to reset to produce Dolly. They found that, if they took a body cell and froze it, they would erase the cell’s memory of what tissue it was from, and the cell would develop just like a fertilized egg.
John Stracke
www.thibault.org
Well, the regeneration thing doesn’t last long. My daughter got her finger caught in a door at age 7 months, and it clipped off a bit of the upper piece of the finger (the “padding” is what the doc called it)… he saved the nail, but the finger sure as hell din’t regenerate. Twenty two years later, she’s got a slightly deformed finger.
I’m still not sure on the answer. We can’t regenerate because we’re too complicated? Why does that make a difference? Our body does complicated stuff all the time. Why do some parts (like skin) regenerate, and some (like kidneys) not? What about stem cells? Is cancer just our regenerative abilities getting confused?
The last bit about cancer in the article brought a question to mind. Do animals that regenerate develop something like cancer? I know that the growth process can go awry, looking at the bumper crop of “plus parts” frogs we had a year or so back.
-Joe
John Stracke wrote:
Just like a fertilized egg? But … but … but, what about those terminator thingies on the ends of some genes (chromosomes?)? You know, the little DNA bits on the ends that get shorter in each copy when a cell divides until, when the DNA ends are all gone, the cell won’t divide anymore? What about those things, hmmm?!
John Stracke wrote:
quote:
I think the "flexibility" Doug is talking about is what the cloning researchers managed to reset to
produce Dolly. They found that, if they took a body cell and froze it, they would erase the cell's
memory of what tissue it was from, and the cell would develop just like a fertilized egg.
Then tracer wrote:
Just like a fertilized egg? But … but … but, what about those terminator thingies on the ends of some genes (chromosomes?)? You know, the little DNA bits on the ends that get shorter in each copy when a cell divides until, when the DNA ends are all gone, the cell won’t divide anymore? What about those things, hmmm?!
This is indeed why Dolly the cloned sheep is now physically much more mature than you'd expect her to be based on when we know she was born - quite close to the physical age of her progenitor, actually. Because you can't fool the terminator bits.[[I think the “flexibility” Doug is talking about is what the cloning researchers managed to reset to produce Dolly. They found that, if they took a body cell and froze it, they would erase the cell’s memory of what tissue it was from, and the cell would develop just like a fertilized egg.]]
This is way outside my area of expertise, but I thought it was DNA inserted into an unfertilized egg, not just a frozen cell.
Grrrrr… I come by to read some back columns and you guys suck me into yet another thread. Well alright, but you’re all on my list now.
Taking things in no particular order:
-The caps on chromosomes are called telomeres.
-The nucleus of a body cell is inserted into an unfertilized egg cell in the cloning of adult higher organisms.
-Dolly the cloned sheep has approximately the same telomere length as the sheep she was cloned from when you compare cells from the same tissue.
-The full effect of this on her aging had not been determined as of about a month ago.
-Genes are not synonymous with chromosomes.
-The regrowth of an infant’s finger (if such a phenomenon exists) is not the same as the regeneration abilities of lower organims.
-Human limbs cannot regenerate because our cells differentiate irreversibly. One of the methods for cloning that was once attempted (and may still be, though it probably doesn’t make the news) was to find a way to reverse the irreversible differentiation.
-There are lots of very simple, lower organisms that cannot regenerate lost bits.
-Small amounts of damage can be repaired because there are still cells that can either reproduce or extend into the damaged area to fill in the empty spots. This doesn’t work in more complex parts.
-Cancer is often the result of cells which have been damaged in such a way that they don’t know when to stop filling in the empty spots (ie. they divide up and down when they’re only supposed to expand out, or they keep dividing even though they’re surrounded by cells, etc.) AND all the various mechanisms for naturally stopping such uncontrolled division are broken or ineffective. You can sort of look at it as a form of regeneration gone awry, if you really want to.
-Bob