Posted on 09/08/2003 4:58:18 PM PDT by bondserv
How the Eye Lens Stays Clear 08/28/2003
To act as a true lens that can focus light, the lens of the eye must remain transparent for a lifetime. Yet the eye lens is not a piece of glass, but a growing, living tissue made up of cells. How can such a tissue stay clear, when the cells must be nourished, and when they contain organelles and chromosomes that would tend to obscure light?
Actually, that is exactly the problem with cataracts, one of the leading causes of blindness, in which the lens becomes clouded. Scientists at Bassnet Labs at Washington University (St. Louis, Missouri) have been studying how the eye maintains transparency, and found an enzyme that, when it fails, leads to cataracts in mice. The job of this enzyme is to chop up and dispose of DNA in lens cells. In a normal eye, “Light can pass through the lens because the cells break down their internal structures during development,” reports Science Now. Nagata et al. at the lab found large amounts of an enzyme named DLAD in mouse lens cells that chops up DNA for disposal. Mice lacking this enzyme developed cataracts. Failures in this enzyme, or the gene that codes for it, are also probably implicated in cataract development in humans.
Their work, published in Nature Aug. 28, explains how lens cells develop: “The eye lens is composed of fibre cells, which develop from the epithelial cells on the anterior surface of the lens. Differentiation into a lens fibre cell is accompanied by changes in cell shape, the expression of crystallins and the degradation of cellular organelles.” Until now it was not known how the cell dismantled its organelles and DNA. The fibre cells have their nuclei removed during maturation, but the DNA remains. It is the job of DLAD to act like a chipper and degrade the long DNA molecules into fragments that can be expelled. Even if the other aspects of fibre-cell cleanup succeed, this study shows that DNA stragglers are enough to cause cataracts.
So normal eye operation depends on the successful cleanup and removal of construction equipment and blueprints: organelles and DNA. Science Now tells a little more about these remarkable lens cells: “Even so, these cells aren’t simply empty; they house a highly organized network of proteins called crystallins* that transmit and focus the light passing through. Any disruption in this sophisticated scaffolding can cloud the lens, causing cataracts.” (Emphasis added.)
Here is an electron micrograph from Birkbeck College, UK showing how the fibre cells in the lens are stacked in neat rows like lumber with hexagonal edges for close packing.
What an amazing thing a living, transparent lens is. Did you ever think about this process, that a sophisticated molecular machine had to be produced from the DNA library that could chop up DNA into fragments, so that they could be removed and not obstruct the light path? Undoubtedly this is not the only enzyme involved in the cleanup job. Each fibre cell needs organelles and DNA during development, but they must be cleared away at the right time, and in the right order before the lens is deployed into operation, or else the user is denied the wonder of sight. This is just one tiny aspect of dozens of complex systems that all must work for vision to work.
Think of an eagle, detecting from high in the air a fish below the water, and using its visual sensors to accurately gauge its approach velocity, pitch, yaw and roll in order for it to capture food for the young in the nest, whose eyes are just opening to the world. Muscles, nerves, specialized tissues, detectors, software, image processing, cleanup, maintenance, lubrication and systems integration are just a few subsystems that must be accurately designed and coordinated in this, just one of many such complex sensory organs in the body.
Evolution is a fake fur that gives warm fuzzies to people who think in glittering generalities. Those who put on lab coats and examine the details and try to fit them into an evolutionary history get cold shudders.*A National Library of Medicine paper describes one of these crystallin proteins: “alpha-Crystallin is a major lens protein, comprising up to 40% of total lens proteins, where its structural function is to assist in maintaining the proper refractive index in the lens. In addition to its structural role, it has been shown to function in a chaperone-like manner. The chaperone-like function of alpha-crystallin will help prevent the formation of large light-scattering aggregates and possibly cataract. ... Reconstructed images of alpha B-crystallin obtained with cryo-electron microscopy support the concept that alpha B-crystallin is an extremely dynamic molecule and demonstrated that it has a hollow interior. Interestingly, we present evidence that native alpha-crystallin is significantly more thermally stable than either alpha A- or alpha B-crystallin alone. In fact, our experiments suggest that a 3:1 ratio of alpha A to alpha B subunit composition in an alpha-crystallin molecule is optimal in terms of thermal stability. This fascinating result explains the stoichiometric ratios of alpha A- and alpha B-crystallin subunits in the mammalian lens.” (Emphasis added.)
That's not what you said in post# 139.
Well, if you want to say that growing a billion cells that are immune to each of a dozen poisons, even though the starting population is killed by all of them, isn't evolution, then you and I mean different things by the word and probably can't talk about it.
Now your story is different. Let's see the study for that one, not that it would prove evolution anyway. Evolution requires far more than change, it requires increased complexity and increased number of functions.
Yes there is a connection between Darwinian evolution and Christian belief - Darwinism denies a Creator. It has to in fact. To believe in the numerous improbabilities which Darwinian evolution asks its believers to swallow, one must totally reject that God could have created life, that God could have created man.
But they make great food.
Will have to check out "Crawling Cells & Comet Tails." Thanks so much for the link!
Evolution requires far more than change, it requires increased complexity and increased number of functions.
Those things have been seen.
Thank you for your astute support of my cause! You're the best. Maybe you could tell our friends if Cell is a reputable source of propaganda, being that you are our local litmus test.
Your input is always welcome, if not always expected. ;-)
A viral intron happening at the same location in independent events would be a truly staggering coincidence. For the DNA record to be just as compatitible with common design as common descent, this staggering coincidence would have to be repeated to account for thousands of viral introns that have been cataloged across multiple genomes up and down the tree of life. It simply cannot have happened as often as you need it.
But it's worse than that. These viral scars are themselves subject to mutation, and that's what we see. Some primate gets a virus which imbeds its DNA in a germ-line cell nucleus but fails to coopt the cell function per the usual plan. Instead, the cell reproduces normally, even with the splice of virus genome inserted. A baby is born with a harmless marker in its DNA.
Millions of years later, you can tell whether a primate came out of that lineage or not by whether the marker is present. Furthermore, you can guess how long ago the marker was inserted by the amount of mutations accumulated among the variations.
That does not spell "common designer." It screams "common descent." That's what we see. You have a tree of DNA relatedness. It has mutations on top of mutations. The connectedness lacking in the fossil record (because of the spottiness of the fossilization process itself) is present in the DNA picture. Big mutations help outline major branching points, but these accumulate a finer dust of little mutations all the time.
And that's without looking at other lines of evidence. When you do, you find that your "designer" somehow decided to make whales out of even-toed ungulate parts. Molecular biological data said this first, but then Pakicetus and Rhodocetus fossils turned up with the diagnostic pulley-shaped ankle-bones of that same group.
Do you understand what I just said? The molecular bio data essentially predicted what would otherwise be an almost absurdly ridiculous fossil find. Whales would be even-toed ungulates, if they still had toes. The people who found the fossils that clinched this didn't believe it themselves until they found the fossils.
And what are all those funny fossil series that seem to show forms morphing into other forms? Why do they match the same trees that the DNA gives you? I mean, why do you make a whale out of camel-goat-pig-hippo stuff when you have fish available? And why does your designer work up to the modern forms with an aquatic-as-a-crodicle whale, then an aquatic-as-a-seal whale, then some obligate-marine-but-still-has-external-legs-type whales?
In the end, all you can do to stay in the game is postulate a designer who can't fail to emulate evolution.
Porpoises are air breathing mammals with bones, much more similar to camels than sharks.
But why? Why afflict the porpoise with a need to come up for air at all? Where it lives, such a feature is merely a liability. Yes, the porpoise is a mammal and is made from mammalian parts. You're trying to use the your model's problem to dodge your model's problem.
Your designer made bird after bird after bird. Suddenly, however, he decided to make another kind of flyer using tree-dwelling mammal parts. Your designer made fish after fish after fish, then suddenly decided he needed another thing shaped like a fish, swimming around in the ocean eating fish, but made using camel/pig/giraffe/hippo parts.
Then he put funny trace data in the DNA to make it look like camels, pigs, hippos, and cetaceans all diverged from a common ancestor. Then he put funny fossils in the ground to make it look like land ungulates slowly became aquatic to become cetaceans.
What were we supposed to think? You've got to let Occam's Razor kick in at some point.
There are many credentialed biologists and chemists who disagree with you.
Whatever the number that disagrees with me, it's nothing to the number that disagrees with you. I can't believe you have no more sense than to go there.
Very good.
Good to see you are still around. Look forward to your further contributions.
Well, once again, the picture is more complicated than that. An international team has just reported in the journal Cell 07/25/2003 that “Telomerase Maintains Telomere Structure in Normal Human Cells.” They found that all cells express this repair enzyme...That would be a very curious sort of self-reference for a slice of text from the Cell article. It simply isn't that at all, and anyone who actually reads it can see such.
You continue to compound your sins. You stole words without attribution. You misrepresented creationist spin on an article as the original article. And this kind of thing:
Thank you for your astute support of my cause!
Too squirmy. "Just the facts, Ma'am!"
When you quote, cite! Links are our friends. And tell it like it is, not like you wish it was.
I knew we would bring you to our side eventually. By the way, my wife and two children got the same flu bug two winters ago. I am still scarred by the event! :-)
Millions of years later, you can tell whether a primate came out of that lineage or not by whether the marker is present. Furthermore, you can guess how long ago the marker was inserted by the amount of mutations accumulated among the variations.
That does not spell "common designer." It screams "common descent." That's what we see. You have a tree of DNA relatedness. It has mutations on top of mutations. The connectedness lacking in the fossil record (because of the spottiness of the fossilization process itself) is present in the DNA picture. Big mutations help outline major branching points, but these accumulate a finer dust of little mutations all the time.
Sounds good. We shall await your contribution to the genealogy of all species. Maybe you could move to Salt Lake City and make a revolutionary contribution to the mapping of mankind.
And what are all those funny fossil series that seem to show forms morphing into other forms? Why do they match the same trees that the DNA gives you? I mean, why do you make a whale out of camel-goat-pig-hippo stuff when you have fish available? And why does your designer work up to the modern forms with an aquatic-as-a-crodicle whale, then an aquatic-as-a-seal whale, then some obligate-marine-but-still-has-external-legs-type whales?
In the end, all you can do to stay in the game is postulate a designer who can't fail to emulate evolution.
Maybe our computer programming matches our designers "style" because it fits a logical model. Where are those traces of Windows 3.1 in XP anyway?
But why? Why afflict the porpoise with a need to come up for air at all? Where it lives, such a feature is merely a liability. Yes, the porpoise is a mammal and is made from mammalian parts. You're trying to use the your model's problem to dodge your model's problem.
How many humans have been saved by sharks? Anthropomorphic of me ain't it, fellow big brained mammals and all?
Then he put funny trace data in the DNA to make it look like camels, pigs, hippos, and cetaceans all diverged from a common ancestor. Then he put funny fossils in the ground to make it look like land ungulates slowly became aquatic to become cetaceans.
Debatable.
Whatever the number that disagrees with me, it's nothing to the number that disagrees with you. I can't believe you have no more sense than to go there.
We need only follow the evidence. My perspective of you and your friends analysis tells me you are inserting your pre-conditions, and you would say the same of me. You can overlook the zealousness with which the scientific community tries to assert their perspective, then realize they continually get set on their heads with the evidence pointing toward design, having to revise their tall tales.
Check here regularly for said "set on their head" examples.
Left-Handed Amino Acids Explained? 09/06/2003
Another theory has surfaced to explain the origin of left-handed amino acids in proteins. Reported in Science News1, R. Graham Cooks and colleagues at Purdue University studied all 20 biological amino acids, and found that one – serine – formed stable clusters of all left- or all right-handed forms. The third lightest (after glycine and alanine), possessing an uncharged polar side chain, serine not only clustered in single-handed forms, but attracted other amino acids of the same hand. Sugars of the opposite hand were also attracted to the eight-molecule serine rings.
Serine clusters’ high stability and selectivity have convinced the researchers that left-handed serine must have forced its chemical siblings to follow its lead [sic]. What caused serine’s left form to become dominant in the first place remains an open question. Some scientists say that ancient minerals may have favored one form over the other (SN: 5/5/01, p. 276). Others point to the effects of radiation hitting primordial Earth. Or, says Cooks, it could have happened by chance.(Emphasis added in all quotes.) As to this chance event, Cooks speculates in the Purdue News press release that “If somehow polarized light, for example, or a swirling motion in water were present at a critical moment, some of the right-handed clusters could have become left-handed. This could have cascaded into other prebiotic reactions and set the pace for a billion years of evolution” [sic]. He calls serine the “bouncer at life’s dance club.” His team’s paper was published online Aug. 4 in the German chemistry journal Angewandte Chemie.2
For the complete article Click Here
All spin, all the time. And how many articles do they have to read to try to find something that they can hope to spin as good news?
Their quotes do not mean what they invite you to believe. For instance:
The difference becomes even more dramatic when the numbers of introns conserved in Arabidopsis and each of the three animal species are compared: approximately three times more plant introns have a counterpart in humans than in the fly or the worm (Table 2).[I have discarded their added emphases because I'm feeling lazy. Just try to imagine somebody shouting the key words, OK?]
Humans conserve more ancestral introns than flies, mosquitoes, or worms. In the creationist strawman version of evolution, that's a problem because plants are lower in the tree of life, then worms are higher, and then insects higher yet, etc. How did the introns skip the worms and insects to get from the plants to the humans?
Real evolution says that today's plants, worms, insects, and humans are extant forms at the tips of their distantly related branches. None of the others are even close to ancestral to humans. Wake me up when humans have an unexpectedly different intron picture from, say, orangutans, or flies and mosquitoes are no more related in their DNA than flies and humans, etc.
The researchers found some surprises, yes. This happens all the time. Creationists report it as follows all the time:
It’s almost funny to watch evolutionists wiggle and squirm when the data don’t fit their expectations.There's always something they can say. If there are no surprises, they just skip the article and don't report it. If inescapably confronted with it, they whip out the all-purpose mantra: "Their conclusions are just from evolutionary assumptions going in, not from the actual evidence." But if there ARE surprises, which are simply the engine of how science refines the picture, then scientists are "squirming."
I'd be interested in some details on this.
The proto-horse (Eohippus?) was very small. They evolved themselves to "almost" modern size all by their lonesome selves.
--Boris
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.