USC Scientists Uncover Secrets Of Feather Formation

University Of Southern California / ScienceDaily.com ^ | 10/31/2002 | Cheng-Ming Chuong, et al

[forsnax5]

Los Angeles, Oct. 30, 2002 - Scientists from the Keck School of Medicine of the University of Southern California have, for the first time, shown experimentally the steps in the origin and development of feathers, using the techniques of molecular biology. Their findings will have implications for the study of the morphogenesis of various epithelial organs-from hairs to lung tissue to mammary glands-and is already shedding light on the controversy over the evolution of dinosaur scales into avian feathers.

[general_re]

I do not accept this ---Under the general rule of ontogeny repeating phylogeny, downy feather made only of barbs probably appeared before the evolution of feathers with rachides and capable of flight," Chuong says. as necessarily valid.

Why are you making such a fuss over the fact that you agree with Chuong?

[Ahban]

And although you weren't a fish, you once had pharyngeal clefts that looked like gill slits

But in humans they are not gill slits, and have nothing to do with gills, or even lungs or respiration at all. They become parts of the human face unconnected to respiration.

We have gone over this before. These similarities are superficial and in no way indicate that human beings ever have anything like gills at any stage of embryonic development.

It points out a more detailed genetic scenario than previously existed.

Yes it gives us details about what genes are responsible for expression of their corresponding feather parts, but that is not proof of feather evolution from scales. They took a creature that already had feathers, and mutated its genes so that it produced mutated feathers (not even scales, so not only did they not make a lizard go through the mutations needed for scales, but they did not even 'backwards engineer' a feather to scales)- er, even if they did, that last would constitue a reduction in complexity that was already present.

[AndrewC]

Why are you making such a fuss over the fact that you agree with Chuong?

I'm not making a fuss. I answered long ago. You continued the interchange when you replied ---

Given that he says "probably", it seems clear that he is expressing an opinion rather than making a pronouncement of scientific fact. Surely he's entitled to an opinion...

39 posted on 10/31/2002 11:21 AM CST by general_re

My answer should have ended the discussion.

[general_re]

My answer should have ended the discussion.

Continuing to post to me is an odd way of indicating the close of discussion...

[Ahban]

Thanks. As long as we have this little mutual admiration society, your #81-86 is a devastating series of posts. Very specific and relavent cites. Facts facts facts. We keep sweeping away their romantic illusions of an unobligated humanity with cold hard facts. They are granted freedom to brush off those facts, yet facts they remain.

[AndrewC]

Continuing to post to me is an odd way of indicating the close of discussion...

You continued as I pointed out. The three dots at the end of your reply to me mean something to me. I replied as I am doing now.(again note the three dots). Note my message does not end with three dots.

[general_re]

I continued as you pointed out? Hmmmm.................

[AndrewC]

but they did not even 'backwards engineer' a feather to scales)- er, even if they did, that last would constitue a reduction in complexity that was already present.

As with "legless" shrimp that were not,(from another genetic "proof" of something) not much really was evidently produced

Supplementary Fig. 1. Sections of developing feather follicles. a, H&E stained longitudinal section of a feather follicle. H&E staining of cross sections at three different levels (proximal to distal) of the flight feather follicle (level indicated in panel a). b, proliferation, c, ramogenic, and d, more differentiated distal zones. Basilar layer cells become marginal plate and barb ridge growth zone epithelia (which give rise to more barbule plate cells and pulp epithelium, and later become the ramus, while intermediate layer cells become barbule plate cells). The peripheral epithelial layer becomes the feather sheath. mp, marginal plate; bp, barbule plate; ap, axial plate; gz, barb ridge growth zone. Bar size, 100 ƒÝm.

Supplementary Fig. 2. Expression patterns of BMP4, BMP2 and noggin in developing feather follicles. a, d, g, b, e, h, In situ hybridization (ISH) of cross sections cut at the two levels indicated in Fig. 1 d-f (dotted lines). c, f, i, ISH of barb ridges from cross sections of embryo stage E18 flight feather follicles. Bar size, 100 ƒÝm.

Supplementary Fig. 3. Establishment of the gene expression system in the feather follicles. a, X-gal staining of longitudinal cryostat sections of a feather regenerated from follicles at 14 days after injection with RCAS-LacZ. b, In situ hybridization using the noggin probe on a cross section of a feather regenerated from follicles 14 days after injection with RCAS-Noggin. c, Enlarged indicated area in b. Bar size, 100 ƒÝm.

[AndrewC]

I continued as you pointed out? Hmmmm.................

Sorry, I was too terse. It should read.

You continued after my explanation of what I considered invalid, by making a statement that seemed to insinuate I did not feel Chuong was entitled to an opinion. (as) I pointed this out in post 103.

[general_re]

You never explained why you thought it was invalid, which is rather what I was attempting to pry out...

[AndrewC]

You never explained why you thought it was invalid,

You missed it.

• I rejected it as a "valid" use of the experimental results.
• Politely, that is the difference between a Darwinian and a non-Darwinian, ontogeny repeating phylogeny as a premise.

[general_re]

To which I pointed out that a valid argument may have false premises and a true conclusion. Do you really wish to rehash this all again? "Who's on first?" might be more entertaining to the lurkers, after all...

[AndrewC]

To which I pointed out that a valid argument may have false premises and a true conclusion.

Valid has more than one meaning. I put quotes around it. You asked me what I considered invalid. I answered you.

val·id   Pronunciation Key  (vld)
adj.

1. Well grounded; just: a valid objection.

I do not consider it a "valid" use of the experimental results. Why? Because I do accept the premise. Therefore it is not well grounded to me.

[AndrewC]

Why? Because I do accept the premise.

Should be ---do not accept the premise.

[general_re]

"That's my opinion and I'm sticking to it." Well, okay, so long as you realize that the conclusion is not objectively invalidated by a flawed premise, nor by your refusal to accept it as valid.

[AndrewC]

"That's my opinion and I'm sticking to it." Well, okay, so long as you realize that the conclusion is not objectively invalidated by a flawed premise, nor by your refusal to accept it as valid.

You spent nearly a day allowing me to answer your silly question the way I answered it. Nice job.

[general_re]

Hey, it's not my fault that you hold entirely unsupported opinions - I don't generally expect that sort of thing on FR. DU, maybe, but not FR....

[AndrewC]

Hey, it's not my fault that you hold entirely unsupported opinions - I don't generally expect that sort of thing on FR. DU, maybe, but not FR....

Admitting places you that you frequent, now we know the font of your inanity.

[PatrickHenry]

Permit me to interrupt your thrilling debate with a placemarker.

[Nebullis]

Once again, the creationists are tripping over themselves to tear down strawmen of their own ignorant making. Just for example, ontogeny does not recapitulate phylogeny in the Haeckle sense, therefore this study is meaningless. And, as they didn't use this newly discovered developmental pathway to produce feathers in an unrelated organism (the elephant?) they didn't discover a developmental pathway. Further, because they don't accept evolution, they don't accept that the evidence is consistent with evolution. (How's that for logic?) On and on they blather. If they could only hear themselves.

This article very neatly lays out evidence for a ontogenic pathway of modern feathers, elucidating the main gene players involved. Very nice work. And we already know that ontogeny recapitulates developmental pathways so this study has something important to say about the evolution of feathers. This work is concise, clean, and significant for evolution and development.