On pi day – March 14 – from Mr Thomas came Plant UV Detectors Could Not Have Evolved. He asks:
[D]id plants really evolve over eons, or were they created in one day? New research demonstrates exactly why plants had to have been created in an instant.
Or at night, possibly? Anyway, this will be interesting to see.
A team of scientists led by researchers at the Scripps Research Institute and the University of Glasgow investigated the marvelous mechanism by which plant cells detect harmful UV-B radiation and then send signals that activate cellular UV-B protection regimes. Without UV detection and prevention, and without all the biochemicals for photosynthesis, plants would have long ago died.
A protein in plants called UVR8 responds to light in just the UV-B range. The protein consists of two identical halves that automatically link to one another just before light hits them. Investigators learned that when UV-B light hits a particular amino acid near the center of the dual complex to change its electrical charges, the halves separate and activate the protein.
More of less. We have a two-halved protein held together by weak attractive forces: when UV light hits they separate and go about their business, orchestrating the fixing of damage. In a few hours the two halves have rejoined and the process can begin again.
The study appears online in Science Express. The lead authors said, “Other light-sensing proteins require a chemical modification or helper molecule to detect light, but UVR8 is unique in that it has these inbuilt UV-B-sensing tryptophan pyramids—structures that no one has seen before.”
You can see why he’s going with the ‘that’s amazing/irreducibly complex’ route.
When separated, each UVR8 protein half somehow quickly signals its cell to activate UV-B protection systems.
“Somehow” – yes, we don’t know exactly how they do it in this case, but proteins that regulate gene expression and other processes are fairly common.
To discover what plant life would be like without the dual-purpose protein UVR8, the researchers mutated UVR8 proteins. “The mutant plants grew poorly when exposed to UV ‘B’ wavelength radiation—the range most responsible for tanning and burning of human skin,” according to a Scripps Research Institute news release.
That is a misrepresentation of what occurred. First, the full quote is as follows:
Researchers first found evidence of UVR8’s protective function in 2002, when they knocked out its gene in the wild mustard plant Arabidopsis, the standard experimental model for plant biologists. The mutant plants grew poorly when exposed to UV “B” wavelength radiation—the range most responsible for tanning and burning of human skin.
They didn’t mutate it, they knocked the gene out completely. And this was how theydiscovered it.
But they did also mutate it (possibly chemically and not genetically – I can’t tell), as part of this study. To quote the press release:
To help confirm that UVR8 can sense UV-B light entirely on its own, members of Jenkins’s lab altered single amino acids within UVR8 to see how the molecule’s light-sensing function changed. Tryptophans in the pyramid structure turned out to be crucial for UV-B detection; in fact, amino-acid substitution of one tryptophan by a phenylalanine shifts the sensitivity of UVR8 to shorter-wavelength UV-C radiation. “These experiments showed without a doubt that UVR8 contains its own light sensor,” said Getzoff.
By alluding to this but putting a quote relating to its discovery instead, Brian Thomas is intentionally misleading his readers into thinking that the protein is much more vulnerable to alterations than it actually is.
If plants evolved over millions of years, then nature would have constructed their UV detection and protection system one piece at a time.
It would also construct it early – we’ll get to that soon.
But there are too many precisely specified parts for evolution to explain, such as various communicating molecules that detect UV, transport the correct signals to the correct places, receive those signals accurately, and deploy specific responses like activating a gene or producing more or less of a specific protein based on those signals. Building each of these separately and over long periods of time is unrealistic.
No, and that wont be how it was done.
We begin with DNA reparation systems already in place: the development of those would come even before this. The process would involve other proteins that do the actual repair work that can be inhibited or sped up by the presence of other proteins. Additionally, the genes that code for these fixit proteins can also be turned on and off by other proteins.
Now, it’s not efficient to have this machinery running at the same intensity at all times: any change that makes it more responsive to conditions will be selected for. And so, if a protein is mutated so that it has a slight attraction to itself (or others of the same) and so weakly bonds and becomes useless/less useful, this will be beneficial. It would not be hard to make it unbind if hit by UV light: this will provide energy, which has to go somewhere and could easily break the bond as part of that. Fine tuning to frequency etc can happen later. In this case, it seems that an obscure regulatory protein was altered in this way: there doesn’t seem to be a reason why it couldn’t have been more direct. The Designer moves in mysterious ways….or maybe evolution is just random?
This is because it takes more than just UVR8 for all of this to work properly, just as it takes more than just a key for a car to function. In other words, all the parts had to have been put in place all at once. Otherwise, the first imaginary evolving plants would have incurred DNA damage from sunlight faster than the damage could be repaired.
No, see above – repair mechanisms will already have been in place, of course, and this merely makes them better.
UVR8-like proteins also occur in algae and moss.
And that should be good evidence that you can modify the protein, and that it can evolve. There is not just one way to do it.
The evolutionary authors tried to fit these observations into their nature-only paradigm by insisting that UVR8 evolved early and all descendant plants inherited it.
And why not?
But because UVR8 would be useless without many other precisely interacting molecules, inheriting it would have been a waste of energy.
Again, I’m going with it having arisen later than the infrastructure that it modulates.
UVR8, along with all other vital plant molecules, was created on purpose. The fact that UV damage is detected and repaired by all kinds of plants just means that God designed all plants with foresight.
Or, that they are capable of evolving it given environmental stimuli.
And that means that the Genesis record had it right all along. [Gen. quote from the top of the page: “And the earth brought forth grass, and herb yielding seed after his kind, and the tree yielding fruit, whose seed was in itself, after his kind: and God saw that it was good. And the evening and the morning were the third day.” – Genesis 1:12-13]
And that shows just how weak the evidence they need to prop up their beliefs. That does not follow.
It is wonderfully ironic, then, that the gist of the next DpSU was an accusation that real scientists were committing the logical fallacy of circular reasoning. Because this article is full of logical fallacies – as always.
I forgot to mention, back when I summarised a months worth of DpSUs, one called What Causes a Galaxy’s Magnetism? I forgot, because it was taken apart instead at Exposing PseudoAstronomy. So, go read.