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.)
Okay, it is miraculous. Don't you see how such a system could not arise without both the ability to fight extraneous organisms and not fight its own organism? You need both or you have death. Therefore it could not have arisen piecemeal as evolution requires, it had to have arisen all at once - and btw - it is a pretty complex system involving more than one organ. That it arises before birth shows its importance.
This is the kind of garbage that evolutionist try to get away with all the time. If the original population was completely destroyed, then where did the following ones come from?????????????
Here is a good example.
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, and that there is a complicated interplay between regulatory factors to keep a normal cell functioning through multiple cell divisions, with just the right number of telomeres for its needs and environment. Their observations “support the view that telomerase and telomere structure are dynamically regulated in normal human cells,” and that telomere length alone is not a sign of old age and impending death.
Only when things go wrong with these regulatory mechanisms do cells either lose their last telomeres and die, or go wild into immortal replication cycles as in cancer. Telomerase is a key ingredient both in the regulation of cell proliferation and replicative lifespan, they found. Targeting telomerase in cancer treatment as a bad molecule may not be wise, therefore. It’s apparently a vital part of a normal cell’s operation. One thing is clear: “the relationships among telomere length, telomere expression, and replicative lifespan are more complex than previously believed.”
The complexity of life and the credibility of Darwinian evolution are inversely proportional. The complexity of life is increasing.
Evolution is a fake fur that gives warm fuzzies to people who think in glittering generalities.
Hugs
2 posted on 09/08/2003 5:05 PM PDT by JesseShurun
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I ran across this today as I was trapped in a waiting room. I read an article in "Discovery" about a Dr. Patrick Brown and the Public Library of Science(www.publiclibraryofscience.org) project. Later I wnet to the webpage and found the picture of Dr. Theriot. Needless to say she was more interesting than Watson and I looked her up on the net where I found the seminar. The seminar is over an hour but it is well worth it. Great stuff!
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Common descent would necessitate similar genetics. Similar genetics would be susceptible to similar viruses. These scars very well could represent a scar left on creatures that don't have the genetic immunities to avoid the virus.
...much less for Him to be putting a pseudo-history in porpoises that makes it look like they're more related to camels than to sharks.
Porpoises are air breathing mammals with bones, much more similar to camels than sharks. If I programmed an add-on for Windoze, I wouldn't use Unix code.
You inherit DNA changes whether they're good for you or not.
I agree many mutations can be passed down. Information rich DNA makes each and every one of us completely unique. (For good or Bad).
What we see in DNA makes sense against this model.
Where ever the data leads us is fine with me. Unfortunately, preconceptions are ingrained in all human beings. So we are destined to differ on opinion until the evidence leaves us no other choice.
What kind of designer tries to pass forward forever every design change--even if it's just accidental noise--that isn't seriously harmful to the designed? What we see in DNA does not make sense against a designer model unless the designer is a mindless robot.
There are many credentialed biologists and chemists who disagree with you.
Check the link back to the origin of this article. What the Webmaster does is he gathers articles from science journals that typically evolutionist’s scientists show surprise at their findings. These don't always work in favor of creationism; oftentimes they illustrate how the leading scientists are befuddled by where the evidence is leading them.
He updates monthly and has a backlog of articles from the last three years. His name is Davis Coppedge, and he is a scientist at JPL working on the Cassini project, which is approaching Saturn. He is also a Creationist who uses recent data gathered from the archives at NASA that confounds the scientists regarding findings in our solar system. Remember, many of the most advanced satellites that have been sent into space have been in the last 20 years.
I will be posting some of his research over the next few weeks. Exciting new astronomical discoveries that aren't usually leaked to the press.
That is Hilarious!!
I will check out the vid tomorrow.
It is over an hour, but as I said well worth it. Notice that velocity is pretty well fixed for the technique. That has some impact on a gradual improvement, there isn't any.
(FYI, it is customary to copy someone when you cite them.)
But I am glad you found something worthwhile in my #82. :-)
Give me a break. The original population wasn't destroyed. If you give two drops of nicotine to a dog, it will die, but if you give it one drop one day and two drops the next, it will not. The dog becomes habituated to the drug. Bacteria can evolve within a few generations (with mutagenic assistance) to survive a dose of antobiotic that would have killed them all, if given suddenly at once. But, this isn't habitutation in the sense of a narcotic drug, because the process occurs over several generations, unlike the dog which can have its tolerance changed within much less than one lifetime. Hence, the fact that the dead do not reproduce is again irrelevant to the question at hand, and your mock outrage at "that garbage peddled by evolutionists" is nothing but hot air.
I fear that you are correct -- especially those who dogmatically advocate the "Young Earth" position, and/or those who call what they preach/teach, "Creation 'Science'".
I'm working on a book along the lines of your comment; tentative title, "Creation Hubris"
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