Good catch. Using zebrafish, researchers were able to track down the gene that causes this giant mirror carp to have few, large scales.
Credit: Oliver Hasselhoff
Posted on 09/05/2009 12:33:45 AM PDT by neverdem
Good catch. Using zebrafish, researchers were able to track down the gene that causes this giant mirror carp to have few, large scales.
Credit: Oliver Hasselhoff
A long-standing question in biology is how evolution tinkers with genes without mucking things up. The prevailing theory is that the genome has copies of critical genes, so that if mutations spoil one, there's a backup. Now researchers have new proof that evolution can work this way.
The scientists tracked down a duplicated gene that made possible so-called mirror fish, which have large, reflective scales. "This is a valuable proof of concept that beautifully illustrates how gene and genome duplications can facilitate morphological evolution," says R. Craig Albertson, an evolutionary biologist at Syracuse University in New York state.
Biologists Matthew Harris and Nicholas Rohner of the Max Planck Institute for Developmental Biology in Tübingen, Germany, started their experiment by using chemicals to mutate zebrafish genes. They then scanned the mutant fish for unusual traits. One mutant was almost scaleless, reminiscent of domesticated mirror carp bred to lack many scales to be easy to clean. The researchers tracked the mutation down to a gene called fibroblast growth factor receptor 1 (fgfr1).
Because mutations in this gene typically cause mammal and fish embryos to die, Harris and Rohner suspected it must have a twin somewhere else in the zebrafish genome. It did. The researchers found an intact version of fgfr1, in addition to the mutated copy that leads to mirror scales.
To see if the process of duplication and mutation happens outside the lab, Harris and Rohner scanned for fgfr1 in mirror carp. They found duplicate fgfr1 genes in two varieties of mirror carp: One had lost 111 bases from the twin gene, and another had a base substitution in the twin gene, both of which had presumably led to fewer scales. The team reports its findings online today in Current Biology.
This is the first duplicated gene that Harris and Rohner have discovered, but they expect to find many more. About 25% of the zebrafish's 17,000 genes are duplicated, and those that are mutated may also exist in wild animals as well as domesticated ones.
Explain how a basic (relatively speaking) 2-chamber heart circulatory system can evolve into the very complex 4 chamber or double heart system.
Lungfish
You don't have to explain it, just draw a sweeping arrow on a chart between the two. Sort of fade the start end, and that's all you ever need.
Are we surprised that genes have error-correcting mechanisms in them, considering how much error-correction and damage-control organisms already have?
This neither proves or disproves evolution. An evolutionist will say, “See, you can muck up the genetic sequence, and still get a viable animal”, and the ID guy will say, “What a smart designer to have an error-correction mechanisms built into the design”.
"Because mutations in this gene typically cause mammal and fish embryos to die, Harris and Rohner suspected it must have a twin somewhere else in the zebrafish genome. It did. The researchers found an intact version of fgfr1, in addition to the mutated copy that leads to mirror scales.
"To see if the process of duplication and mutation happens outside the lab, Harris and Rohner scanned for fgfr1 in mirror carp. They found duplicate fgfr1 genes in two varieties of mirror carp: One had lost 111 bases from the twin gene, and another had a base substitution in the twin gene, both of which had presumably led to fewer scales."
IMHO, they're alluding to two pairs of genes for fgfr1, not simple Mendelian genetics with a pair of dominant and recessive alleles, but copy number variation(cnv).
I only read this citation's abstract so far, but it's a review article. I've posted other articles about cnv that you can find clicking on the appropriate keywords.
P.S. I'm not interested in proving or disproving evolution. I can live with it, just like the Roman Catholic Church does. Different human populations have various copy number variations for amylases.
Could intravenous antivirals be a last-ditch treatment for swine flu?
FReepmail me if you want on or off my health and science ping list. Anyone can post any unposted link as they see fit.
Oh, you have to have lungs first ~ that’s what the atrial chambers do ~ pump blood through the lungs. No lungs, no need for four chambers.
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Thanks neverdem. |
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