The brine shrimp are very healthy.
They've been selling them for years.
Posted on 02/08/2002 5:40:18 AM PST by JediGirl
Scientists have discovered the first genetic evidence explaining how small mutations can cause big changes in an organism's body.
Until now there has been little proof that one genetic change can successfully lead to a whole new species.
A University of California study has shown how a mutation in a 'master gene' which controls others could lead to a major body change.
The study looked at a class of genes known as Hox, which switch on and off other genes during an organism's development as an embryo.
The San Diego team used brine shrimp to prove a simple mutation here suppressed 15% of the limb development in the animal's central body region.
This would have allowed its ancestors, which had limbs on every segment of its body to lose their hind legs and evolve into six-legged insects.
Professor William McGinnis, who led the study, claims it answers the question as to how evolution can introduce big changes into an animal's body shape and still generate a living animal.
He said: "Creationists have argued that any big jump would result in a dead animal that wouldn't be able to perpetuate itself.
"And until now, no one's been able to demonstrate how you could do that at the genetic level with specific instructions in the genome."
Story filed: 12:41 Friday 8th February 2002
That's how it was 2000 years ago, according to John, and that's how it still is. So much hate.
As for me, the C/E debate is concerned with the material world, and we worry too much about the material world.
NAME ONE MUTATION that has PROVEN to be beneficial. Show me the previous version of a creature that mutated, then show me the better version that had more complexity and became another species. You cannot use theory, either, you must use evidence.
The brine shrimp are very healthy.
They've been selling them for years.
In the genetic code, there is a series of genes in each set of chromosomes called HOX genes that control exterior development. These particular sets of genes appear only in vertebrates and create proteins that tell the body to create or suppress appendages, tell which end to become a head or foot, and everything. In particular, there is a HOX gene called the Ubx/AbdA, which suppresses abdominal appendages in fruit flies. What they did was took this gene (which is different in each species) in fruit flies and the gene in the particular species of shrimp, and told it to activate itself in the thorax region in each species (where is where the appendages are). They compared the effects of the activated genes in both species and found that the gene that is in the shrimp doesn't suppress leg function as well as the gene that is in fruit flies. They then created a series of HOX/AbdA genes that were various blends of each species, and used the effects of these blends to note the number of legs created by each particular blend. They used this to locate the molecular sequence of each gene that causes appendage suppression. They created blends of each sequence to make sure that each sequence alternately suppressed or enhanced appendage creation.
From this, they propose that that particular molecular sequence was activated in the past in the thorax shrimp/insect ancestry, which caused the species to diverge into insects, arthropods and arachnids. That this happens in the genetic code has been hypothesized for some time, but this is the first time that someone has actually manipulated a small bit of the genetic code to make such large scale changes to the extrior structure of an organism. Certainly scientists have genetically altered fruit flies to create different species of fly that cannot reproduce with each other, but as creationists constantly remind us (as Wells does in the DI press release) no one has ever created a 4 legged fly, or a 6 legged spider, or a spider with wings. As they say at the end:
quote:"On the basis of these results, we propose that Ubx proteins in some crustacean/insect ancestors uncovered a limb-repression function by the mutation of C-terminal Ser/Thr phosphorylation sites. Together with the restriction of Ubx expression to the posterior trunk and expansion of a QA-rich domain, the loss of these sites would have contributed to the evolution of the hexapod body plan. The putative phosphorylation-mediated regulation of transcriptional repression function in arthropod Ubx proteins may occur by a similar mechanism to that recently described for the Drosophila Even-skipped protein. In both cases, such a mechanism would provide for the mediation by signal transduction of the control of transcriptional activation and repression functions of homeobox (HOX) genes."
"To our knowledge, this is the first experimental evidence that links naturally selected alterations of a specific protein sequence to a major morphological transition in evolution. There are at least two major reasons why the mutation of mutiple Ser/Thr residues that inhibit a repression function might be advantageous from an evolutionary aspect. First, mutating the residues would give dominant phenotypes, eliminating the need to fix two recessive mutations in a morphologically evolving lineage. Second, the successive removal of Ser/Thr residues might quantitatively influence repression function and morphology, allowing viable microevolutionary steps toward "hopeful monsters" with macro-evolutionary alterations in body shape."
With advances like this, it is readily apparent that we are only a few decades away from producing large scale changes in animals in a very detailed manner. Note that there are no new animals in this picture. All they did was use existing HOX genes to isolate specific sequences that would suppress limb creation. They do not mention if embryos survived in the paper, and it is not relavant to the paper at hand.
What is relavant is that they have isolated a mechanism for large scale external change in genetic structures. It is widely believed that the shrimp and the fruit fly that they studied quite likely came from the same proto-crustacean a few hundred million years ago. It was noted in the paper that the UBX/ABDA genes are very similiar in appearance, which supports that supposition, and the genes are the major instrument in limb suppression is one very small sequence of the DNA that occurs as a dominant mutation in the two chromosomes. That is, if it occurs in one, it will affect both in the next generation.
Like I said before, this is pretty big in the crevo discussions. That you can force a mutation in such a small sequence is a major step forward, and it shows that such a large step isn't so hard for nature to achieve after all.
Brilliant people,
working in the highest developed laboratory,
using the highest technology,
through a series of experimental processes guided by brilliant individuals,
determining through process of elimination which way to proceed,
have done something that you expect people to believe happened by chance alone????
As I understand it the brilliance here is not in producing a mutation but in finding how and what to change in which genes to obtain a specific mutation. Regards.
Thanks for the explanation. I don't trust jounalist's explanations of new scinetific discoveries because they often don't understand what they are reporting.
I have suspected this type of master gene for some several years. The genetic code is very similar to computer code. Computer code is heirarchical with multiple layers that call routines in the layers below. In the upper layers, incredibly complex functions can be performed by a surprisingly small amount of code. If the genetic code is similarly structured, then apparently large changes in morphology can be accomplished with a small number of changes in the genetic code. This explains the sparcity of transitional forms, that punctuated equilibrium tries to explain.
Several years ago I was watching a NOVA show about how to build a dinosur ala Jurasic Park. One scientist on the show (can't remember his name) made the most astonishing claim, at least to me. He said the best way to make a dinosaur, would be to take existing genes in an ostrich for reptile skin, tail, etc., that are not being expressed and turn those genes on transforming an ostrich into a dinosaur. If what he propesed is true, then the implications for evolution are staggering. The mechanism of evolution then would be a macro evolutionary mechanism with micro evolution playing only a fine tuning role. Like all great scientific discoveries, this discovery if it continues to pan out the way I think it might will almost completely transform the theory of evolution into a theory that would be unrecognizable by Darwin. For instance, the amount of genetic code that has to do with overall morphology may be very small compared to amount of code which codes for body parts and biochemistry. This would mean that most of the gentic code evolved very early in the history of the life, pushing it into a smaller and smaller time span.
This time around, they looked to nature for direction!
In previous studies researchers had taken the well-studied hox genes, mutated them or expressed them in places where expression is normally not found and were able to generate mutant flies with extra wings, legs, or fewer wings, legs, different segmentation patterns, etc. etc.
Okay, so, they could "artificially" do this in the lab, but the real question is, what direction did nature take? So they pulled out the sequence of a creature ancestral to the fly. A creature with a different segmentation pattern and many more legs. Using that gene in the fly they uncovered something surprising: flies have evolved a supressing function of the ancient gene.
This is not laboratory designed. This is discovering nature.
I beg your pardon. It's my accent.
It was in nature where the change was induced, it was in the laboratory where this change was repeated. Pretty amazing, huh!
That's not nature, that's the lab, the deliberate choosing oof a species to modify genetically, and that aint eolution, that's genetic manipulation.
You go for a walk one morning and see that water in a puddle turned into ice. You want to find out how it happened. Using your brilliance you come up with a theory and put some water in the freezer. After a while it turns into ice. So, even though you didn't observe in nature the process of water turning into ice, you reproduced the change in a laboratory showing one way it could've happened.
Regards.
Isn't this like saying because microbiologists use microscopes as tools to visualize bacteria, the bacteria aren't real, that's microscopy!
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