Hox genes, or homeobox genes, are responsible for pattern development of limbs. Since urodele amphibians, like the axolotl, have a really remarkable ability to regenerate their limbs scientists at the University of California, Irvine's Developmental Biology Center wanted to see the role Hox genes, in particular the play HoxA complex, in this ability.
These genes essentially get turned off after limbs are developed in the embryo and in humans they do not get turned on again, which is unfortunate. Within the HoxA complex, Hox9 and Hox13 are both reexpressed early within the regeneration of the axolotl limbs. Not only does the axolotl express these Hox genes, these scientists isolated 17 different genes that are similar. Along with Hox, these 17 genes are responsible for the complex regeneration system. These genes are usually expressed with temporal and spatial colinearity during embryo development, meaning that the genes at one end of the chromosome are expressed at the head while the genes at the other end of the chromosome are expressed at the tail end. This is not the case for limb regeneration. Once signaled, these genes express the same way no matter where the limb loss is located (the cells do not differentiate). It is not until the later process does the cells start to differentiate depending what place along the proximal-distal axis they are being grown from. Basically, all of the limbs and tail start out as a stump and then once they reach a certain point, they will differentiate into the correct limb.
Could we potentially use this knowledge to help amputees regrow limbs or would that be pushing science a little too far? Humans do express both the HoxA13 and the HoxA9 genes.
This literally looks like some type of Pokemon character. I have heard about the homeobox genes in my Zoology or Genetics class I believe, but I didn't really remembered how they functioned. I'm glad you provided some background information on this. I find this topic cool because they have the ability to grow back any limb that may be taken off. I hope they will be able to one day isolate these genes and find a way to gene transfer this into the DNA of other organisms to see how it would effect organisms that are similar to humans. By looking at the results of this, using these genes in humans would be a medical marvel for people who are amputees.
ReplyDeleteNice title. If we have these same or similar genes, then wouldn't it be useful to also know how these genes are regulated? Do you know if it is an immune response once a limb is lost or something else?
ReplyDeleteCould it really be possible for humans to regrow lost limbs? The possibility alone is incredible. I don't think this would be pushing science too far. I don't see how it would hurt anyone and like you said, these genes are already naturally within us. I'm sure there would be some people who would oppose it, but I'm all for it.
ReplyDeleteIt would be incredible if we had the capability to regrow limbs! I wonder if people would then opt for amputation over surgery in cases of broken limbs...I am also curious how this would or if it would alter our bone structure in terms of flexibility and strength. Side note: Love that title!
ReplyDeleteKari-
ReplyDeleteYou chose a very interesting (and cute) topic! Axolotls are truly fascinating creatures! While I think the Hox gene and its ability to assist in limb regeneration is interesting, I am indecisive on it applicability to humans. I feel as if the biology behind amphibians and humans are vastly different, so it might not be feasible or even possible to apply the same mechanism of re-growth to humans. However, it is interesting that these two organisms share similar genes. In addition, there is always the possibility of multiple, undiscovered genes working together to allow an axolotl to regenerate its missing limb. For me, there are too many unanswered questions to decide whether research should be expanded to amputee limb regeneration.
I could be completely wrong on this, but I think that it may be more complex than simply turning on and off genes; for this to work in amphibians, I bet there must be some persistent embryonic tissues remaining in the limb...undifferentiated cells that can be induced to become any other type of cell. As far as I know, we don't have these distributed throughout our bodies.
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