Health Depends on Robust Cell Machinery
When we think of health, we typically visualize the big things: firm muscles, energy, lack of a protruding stomach and the like. Cell biology, though, is showing us how our health depends on the proper functioning of countless myriads of molecular machines. Here are some recent samples from the science journals:
- Heroic Underdogs in the Brain: Neurons always got the glory in neurology studies, but now it appears that structural cells called astrocytes deserve more respect. A summary of work at U. of Rochester posted on EurekAlert says that these “housekeeping” cells actually perform critical functions in regulating blood flow. They “play a direct role in controlling blood flow in the brain, a crucial process that allows parts of the brain to burst into activity when needed.” When they malfunction, they might contribute directly to degenerative maladies like Alzheimer’s disease. See also LiveScience.
- The Vital Destroyer: When cancer spreads, hope shrinks. Friends and family of cancer victims know the agony of metastasis. At least in some kinds of cancers, metastasis may be traced to failure of a protein named caspase-8 that acts like a curfew cop. Normally, reported EurekAlert about work by St. Jude’s Research Hospital, caspase-8 patrols the surfaces of tissues looking for vagrant cells that have dislodged from their normal locations and are wandering into unsafe territory. When it finds them, it turns on their built-in self-destruct program, called apoptosis. When the cops are out sick, the vagrants get out and cause trouble. The paper was published in Nature.1
- Your Third Eye: A rare type of eye cell can see. Rods and cones, we know, do most of the real-time visualization, but scientists at Brown University found “intrinsically photosensitive retinal ganglion cells,” or ipRGCs, that respond to light and are hardwired to the brain. They are pretty sure these slower-acting light sensors are responsible for setting our biological clock and controlling the iris muscles, regulating how much light enters the eye. “These cells operate like a light meter on a camera,” said researcher David Berson. “They tell the brain to constrict the pupil based on the amount of light registered over time.” There are about 2,000 of these cells in the eye, compared to millions of rods and cones.
- Don’t Bang the Eardrums: Our ears can tolerate many orders of magnitude in volume, but there are limits. Researchers at Ohio State found that “years of repeated exposure to loud noise increases the risk of developing a non-cancerous tumor that could cause hearing loss.” Please pass this warning along to your local fitness center.
- Watergate Scandal: Point mutations to our water gates, the water-regulating channels in cell membranes, can let the wrong substances in, reported Breitz et al. in PNAS.2 These elaborate channels made of protein, called aquaporins, depend on a precise amino-acid structure to authenticate water but keep other similar-size molecules out; they can even keep out tiny protons. The team inserted mistakes here and there and found that contraband like urea or glycerol could sneak in. One amazing factoid they mentioned is that a single red blood cell has as many as 200,000 aquaporins. For more on membrane channels, see 05/29/2002 and 12/20/2001. A reader found detailed powerpoint presentations and animations at the University of Illinois at Urbana-Champaign website, and more at the University of Maine.
- Gutfull Wonders The stomach is a lively place. Lots of organisms live there; hope you don’t mind. A team from Stanford and NYU decided to start surveying these one-celled companions, because “The microbiota of the human stomach … remain largely unknown.” Their preliminary results, published in PNAS,3 began, “A diverse community of 128 phylotypes was identified, featuring diversity at this site greater than previously described.” Ten percent of them were previously unknown, and they come from at least five separate phyla. Surprisingly, the population in the stomach differs from that in the mouth and esophagus, and different people have different assortments. There are some known bad bugs like Helicobacter pylori that form ulcers, but most of them must be OK or even helpful, since we usually feel good after a big meal: “The gastric microbiota may play important, as-yet-undiscovered roles in human health and disease,” they said.
- Clamp Champs: You have sliding clamps in your cells. Really. Current Biology4 talked about these wonderful machines that twist DNA during the copy process:
DNA sliding clamps were first characterized as DNA polymerase processivity factors: without their presence, cell division would be inconceivably slow; replication of long stretches of DNA would be hopelessly inefficient because DNA polymerases tend to fall off the DNA after elongating a strand by just a handful of bases. By tethering the polymerase to the DNA, such processivity factors enable the polymerase to add thousands of bases in a few seconds without detaching from the DNA. (Emphasis added in all quotes.)
They work kind of like magic Chinese linking rings. Somehow they melt around the DNA strand without harming it. This allows all the other machinery to get a grip during that heavy-duty copying cycle. Good thing we don’t have to wait so long for the copy operation or we might never grow up.
- DNA Gyrations During Packaging: Nature printed articles on two other DNA motors that deserve special notice: one is an acrobatic “gyrase” that generates negative supercoils in DNA (that’s important for packing and safety during cell division).5 In their words, “Negative DNA supercoiling is essential in vivo to compact the genome, to relieve torsional strain during replication, and to promote local melting for vital processes such as transcript initiation by RNA polymerase.” The little motor runs on the cell’s special fuel pellets, ATP. The scientists put beads on it and watched it spin around. They found it was quite sensitive to tension.
- More DNA Acrobatics: Another team publishing in Nature6 studied motors called DNA helicases, which are “involved in nearly all aspects of DNA and RNA metabolism.” Utilizing special techniques, they watched this incredibly tiny molecular motor and discovered that it “might move like an inchworm” (that’s scientific lingo). It also runs on ATP in a precise range of stresses. Without the helicase machinery, DNA unfolding would be very, very slow. This particular helicase, named NS3, is just one of many “helicases involved in many essential cellular functions.”
1Stupack et al., “Potentiation of neuroblastoma metastasis by loss of caspase-8,” Nature 439, 95-99 (5 January 2006) | doi:10.1038/nature04323.
2Breitz et al., “Point mutations in the aromatic/arginine region in aquaporin 1 allow passage of urea, glycerol, ammonia, and protons,” Proceedings of the National Academy of Sciences USA, published online before print January 3, 2006, 10.1073/pnas.0507225103.
3Bik et al., “Molecular analysis of the bacterial microbiota in the human stomach,” Proceedings of the National Academy of Sciences USA, published online before print January 4, 2006, 10.1073/pnas.0506655103.
4Barsky and Venclovas, “DNA Sliding Clamps: Just the Right Twist to Load onto DNA,” Current Biology, Volume 15, Issue 24, 24 December 2005, pages R989-R992.
5Gore et al., “Mechanochemical analysis of DNA gyrase using rotor bead tracking,” Nature 439, 100-104 (5 January 2006) | doi:10.1038/nature04319.
6Dumont et al., “RNA translocation and unwinding mechanism of HCV NS3 helicase and its coordination by ATP,” Nature 439, 105-108 (5 January 2006) | doi:10.1038/nature04331.
Most of these articles mentioned little or nothing about evolution. Here is legitimate science in action: seeking understanding, observing phenomena in real time, learning things so as to benefit human health. Was Darwinism valuable in the slightest? These articles are mere glimpses into the new world of molecular machines for which evolutionary theory was completely unprepared. Most of these machines are parts of complexes with other machines, and they all must meet precise specs or they won’t work – and not working often means serious impairment or death. How could such elaborate factories emerge by mindless, undirected processes of evolution?
Darwinists are either scrambling to patch up their theory with new just-so stories, or else going schizophrenic by not even attempting to explain these machines on one side of their head while stating “evolution is a fact, like gravity” on the other. Any thinking person examining evidence like this will quickly tire of the “maybe this, maybe that” habit of the Darwin Party: “perhaps in some warm little pond, the first life needed a way to pack DNA, so it invented gyrase.” Yeah, right. Preach it, brother.
Charlie was plagued by stomach aches most of his life. Had he knowledge of such small wonders, his groans might have been heard round the world. Those not infected with Gastroenteritis darwini can avoid infection by clicking back through five years of Chain Links on Cell Biology and Amazing Stories. Doing so has the added benefit of inducing a state of euphoria, also known as intelligent worship.