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The researchers now plan to make a gene chip designed to detect levels of some of these candidate genes, so that the scientists can determine at exactly what point during the regeneration process the genes are turned on. The team is also developing molecular tools that allow them to silence specific genes, which will enable them to pinpoint those that are crucial for proper regrowth.
Scientists also sequenced random chunks of the salamander genome. At about 30 billion bases and 10 times the size of the human genome, it is one of the largest among vertebrates. Most scientists expected that the extra DNA would be made up of junk DNA, long stretches of bases between genes. But initial findings were surprising. "Genes are on average 5 to 10 times larger than those in other vertebrates," says Voss. "The region of the genome containing genes is estimated to be more than two gigabases, which is as big as some entire genomes."
The extra DNA sequences sit within genes and are cut out during the translation from gene to protein. Much of this DNA comprises repetitive sequences not found in any other organisms to date, says Pao. However, it's not yet clear whether these repetitive stretches help facilitate regeneration or play some other role in the salamander's life cycle.
One of the key questions yet to be answered is whether the salamander has unique genetic properties that enable regeneration, or whether all animals have that innate capability. "If we come up with some totally unique gene only present in axolotl, that would make it really hard to replicate," says David Gardiner, a biologist at the University of California, Irvine, who is also collaborating on the project. He prefers to think that regeneration comes from a fundamental abilitylying dormant in mammals, which could be reawakened with some simple genetic prodding."Most of the tissue in our arm regenerates; it's just the arm that doesn't regenerate," he says. "What's missing is how you coordinate a response to get an integrated structure."
A chemical-infused scaffold generates new tissue by attracting stem cells.
Salamanders regrow limbs with less drastic cellular changes than previously thought.
Researchers boost growth of muscle stem cells to stop age-related muscle deterioration.
In the reference below, "Regenerating chicken wing," it says that a group at the Salk Institute identified a set of genes, the Wnt pathway, that is involved in regeneration of a chicken embryo wing. Are the Wnt pathway genes part of those activated during salamander limb regeneration?
---- Quote from 11/22/2006 article:
Researchers have now identified a genetic "on" switch that triggers regeneration at developmental stages when the animal normally lacks the capacity. Yasuhiko Kawakami and colleagues at the Salk Institute for Biological Studies, in La Jolla, CA, performed experiments in chickens and frogs in which they overactivated a set of genes, called the Wnt pathway, known to be involved in regular development and thought to be involved in regeneration.
If you actually go to the G&D paper by the Belmonte lab, you will see part of the work was done in axolotls
Yes. David Gardiner, quoted in the story, published a paper describing the activation of one of the wnt genes during axolotl limb regeneration this year (Develop. Growth Differ. 2008, (50): 289-297).
Darwins counterinteraction point
Asymmetric fragments lacking a midline displayed new smedbmp4-1 expression prior to formation of a regenerative outgrowth (blastema). Therefore axolotl limb regeneration is an Asymmetric fragments containing the midline displayed expanded smedbmp4-1 expression towards the wound. While the workup to it in mamals includes (bone morphogenetic protein-2 (BMP) and BMP4 and Wnts) calcium deposition shows selective and by translocating polymeric IgA and IgM preferential deposition, fuses a concrete series of molecular events that fuse to the simplified jejunum and allows interpretation of previous mutagenesis results in basolateral apical grouth in all tissues and axons in imaginal disks inferred by preliminary as in requirements ie. The totally gastrectomized TGX[1.] rats and feeding regiems involved to pre condition pre B and T-cells the villi (microvillus membranes) along the brush border where it colocalised with lactase stimulated degranulation activity of lactoferrin (Lf) suspected of having [TfR] defectively regulated iron metabolism in bulbectomized rats creates a vertibral mammal resembling more closley the (blastema) not discussed before rather than the axolotl discussed before as right left symetries.
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rkomatsu
52 Comments
What size of limbs?
I wonder in wonder: the regrown limb always has the proper size for the age of the salamander? If a human could have this regeneration ability reawakened, its regrown limb would be a baby's limb and only reach its full size 16+ years later?
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gpao
2 Comments
Re: What size of limbs?
limbs grow until they reach the proper size
for a video go to the Bryant/Gardiner website:
http://regeneration.bio.uci.edu/
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