Freethought & Rationalism Archive

Albion · 10-12-2002, 12:00 PM

So eyes are an example of good intelligent design whether an aniomal needs them or not, and vestigial eyes are an example of good intelligent design, and lack of vestigial eyes is an example of good intelligent design, and basically everything's an example of good intelligent design. There's science for you!

Coragyps · 10-12-2002, 01:13 PM

The article:
Central Role for the Lens in Cave Fish Eye Degeneration
Yoshiyuki Yamamoto and William R. Jeffery
Science 2000 July 28; 289: 631-633.
Its abstract:

Quote:

Astyanax mexicanus is a teleost with eyed surface-dwelling and eyeless cave-dwelling forms. Eye formation is initiated in cave fish embryos, but the eye subsequently arrests and degenerates. The surface fish lens stimulates growth and development after transplantation into the cave fish optic cup, restoring optic tissues lost during cave fish evolution. Conversely, eye growth and development are retarded following transplantation of a surface fish lens into a cave fish optic cup or lens extirpation. These results show that evolutionary changes in an inductive signal from the lens are involved in cave fish eye degeneration.

VZ, if you don't have a college library handy, I would be glad to fax or mail you a copy of the article.

Edited to add: But I would want you to actually read it if I did.

[ October 12, 2002: Message edited by: Coragyps ]

Bubba · 10-12-2002, 02:56 PM

Quote:

Originally posted by pz:

If you have nothing of substance to say, please do not try to sidetrack this thread. Deal with it.[/QB]

That would require critical thought and evidence, two things ceationism is sadly lacking in.

Bubba

Bubba · 10-12-2002, 03:00 PM

Quote:

Originally posted by Clutch:
Vandervasion's current argument: As long as I insist that there is no evidence, even when it is spoonfed to me, then... ummm, I can say that I don't see any evidence.

Keep up the good work! You are pounding nails into creationism's coffin with every risible dodge.

...he's not alone in doing this either...
<img src="graemlins/banghead.gif" border="0" alt="[Bang Head]" />

Bubba

Bubba · 10-12-2002, 03:04 PM

Quote:

Originally posted by rbochnermd:


Sweet Jesus, I'll promise pz sexual favors if he makes you go away.

Rick

I doubt you'd be the only one...

Bubba

pz · 10-12-2002, 04:04 PM

Quote:

Originally posted by Bubba:

Quote:

Originally posted by rbochnermd:

Sweet Jesus, I'll promise pz sexual favors if he makes you go away.

I doubt you'd be the only one...

Don't be offended by this, but the fact that a gastroenterologist and a guy named Bubba are talking about giving me sexual favors if Vanderzyden goes away is the only thing currently tempering my scorn for the little weasel.

Vanderzyden · 10-12-2002, 04:22 PM

Quote:

Originally posted by pz:

...the only thing currently tempering my scorn for the little weasel.

Spoken like an adolescent. Ridicule, but no substance. How is it that you are granted responsibility in teaching students?

Vanderzyden

Vanderzyden · 10-12-2002, 04:23 PM

Coragyps,

Thanks for referring me to the proper journal and the abstract. This affords me the opportunity to examine another "evolutionary" exhibit. Here is the entire article, which I obtained through a free subscription to <a href="http://www.sciencemag.org/cgi/login?uri=/subscriptions/signedin.shtml" target="_blank">Science Online</a>:

Quote:

Central Role for the Lens in Cave Fish Eye Degeneration
Yoshiyuki Yamamoto and William R. Jeffery*

Astyanax mexicanus is a teleost with eyed surface-dwelling and eyeless cave-dwelling forms. Eye formation is initiated in cave fish embryos, but the eye subsequently arrests and degenerates. The surface fish lens stimulates growth and development after transplantation into the cave fish optic cup, restoring optic tissues lost during cave fish evolution. Conversely, eye growth and development are retarded following transplantation of a surface fish lens into a cave fish optic cup or lens extirpation. These results show that evolutionary changes in an inductive signal from the lens are involved in cave fish eye degeneration.

... The eyed and eyeless forms of Astyanax probably diverged from a common ancestor within the past million years (5, 6). Here, we show that evolutionary changes in an inductive signal from the lens are involved in cave fish eye degeneration.
Although adult cave fish lack functional eyes, eye formation is initiated during embryogenesis (Fig. 1, A and B). The lens vesicle is formed but later degenerates, and the cornea, iris, and other optic tissues are absent or rudimentary (Fig. 1, C and D) (7, 8). The optic cup and neural retina are formed in cave fish, but the retinal layers are disorganized, growth is retarded, and photoreceptor cells do not differentiate. The degenerate eye sinks into the orbit and is covered by a flap of skin. Constructive changes have also evolved in cave fish, including enhanced lateral line and gustatory systems (4, 9).

Cave fish lens cells undergo apoptosis before the arrest of eye development (3). Because extensive apoptosis has not been detected in other eye tissues at this time, lens apoptosis may be an important factor in eye degeneration. Alternatively, lens apoptosis and eye degeneration could be controlled by a signal from the optic cup, which is diminished in cave fish (Fig. 1, A and B). To determine the control of lens apoptosis, we transplanted a surface fish lens vesicle into a cave fish optic cup and vice versa (Fig. 2A) (10) and assayed for apoptosis by TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling) (11)... In another control, a surface fish or cave fish lens vesicle was transplanted into a surface fish or cave fish optic cup, respectively. Eyes typical of the respective hosts were formed in the latter control, showing that the operations do not affect optic development. The cave fish lens underwent apoptosis on schedule in the surface fish host (Fig. 2, F and G). Conversely, the surface fish lens vesicle did not undergo apoptosis and formed a differentiated lens in the cave fish host (Fig. 2, D and E). Thus, apoptosis is controlled autonomously within the cave fish lens vesicle.

Eye development was stimulated on the transplant side of the cave fish host (Fig. 3, A to D) (12). Although no differences were apparent after 48 hours (Fig. 3A), a larger eye was detected on the transplant side after 8 days of development...

We have shown that the surface fish lens is sufficient to rescue eye development after transplantation into the cave fish eye primordium. We conclude that a change in an inductive signal emanating from the lens is a major cause of eye regression in cave fish (20). Our results illustrate how an evolutionary modification in embryonic induction can result in dramatic changes in adult morphology.

REFERENCES AND NOTES
...
Surface fish, originally collected at Balmorhea State Park, TX, and cave fish, collected at Cueva de El Pach�n, Tamaulipas, Mexico, were maintained at 25�C on a photoperiod consisting of 14 hours of light and 10 hours of darkness. For lens transplantation or extirpation, 24-hour-old (34- to 38-somite) embryos were washed for 30 min in calcium-free zebrafish ringer (CFZFR) [116 mM NaCl, 2.9 mM KCl, and 10 mM Hepes (pH 7.2)] containing 0.2% EDTA, rinsed in CFZFR (40�C), and embedded in 1.2% agar in CFZFR (40�C). After cooling to room temperature, individual embryos were cut into agarose blocks. The operations were done with sharp tungsten needles in agarose blocks arranged side by side in CFZFR. The host embryos were grown to adults under the normal photoperiod.
Y. Gavrieli, Y. Shermann, S. A. Ben-Sasson, J. Cell Biol. 119, 493 (1996) .
In 81 transplantations, 38 (49%) of the hosts survived. Nineteen (50%) of the survivors showed large external eyes on the transplant side, and the remainder showed eyes buried in the skin, although they were larger than those on the control side.
R. Macdonald and S. W. Wilson, Dev. Genes Evol. 206, 363 (1997) [CrossRef][ISI] .
Specimens were fixed in 4% paraformaldehyde, embedded in Paraplast, and sectioned at 8 �m. Sections were microwaved in 10 mM citric acid at pH 6.0 (three times) for 5 min to expose the antigens before immunostaining (9). Pax6 antibody was purchased from Babco (Richmond, CA), PCNA antibody was purchased from Santa Cruz Biotechnology (Santa Cruz, CA), and rhodopsin antibody was purchased from Leinco Technologies (St. Louis, MO). S. I. Tomarev provided Prox 1 antibody. For primary incubations, the Pax6, Prox 1, and PCNA antibodies were diluted 100:1, and the rhodopsin antibody was diluted 50:1.
N. Hirsch and W. A. Harris, J. Neurobiol. 32, 45 (1997) [CrossRef][ISI][Medline] .
Web fig. 1 is available at <a href="http://www.sciencemag.org/feature/data/1051074.shl." target="_blank">www.sciencemag.org/feature/data/1051074.shl.</a>
...
K. Negishi, W. K. Stell, Y. Takasaki, Dev. Brain Res. 55, 121 (1990) [ISI] .
Of 31 transplantations, 15 (44%) of the hosts survived. Thirteen (87%) of the survivors showed small degenerate eyes on the transplant side, and the remainder showed no effects on eye development.
Our results are relevant only to the Pach�n cave fish studied here, one of at least 30 Astyanax cave fish populations that may have evolved the eyeless phenotype by different mechanisms (4, 6).
...

First, I note that the second and third sentences of the abstract are seemingly contradictory: the second sentence indicates "growth and development" as a result of transplantation of the surface fish lens. The next sentence states that such transplantation results in "retarded" growth and development.

In the second paragraph, the reader must endure much unrelated Darwinistic preaching before arriving at the statement of purpose for this study: "...we show that evolutionary changes in an inductive signal from the lens are involved in cave fish eye degeneration." Well, we shall see if they actually provide a demonstration.

The authors go on to elaborate the difference between the cave and surface varieties of the teleost (bony fish). In the cave fish, we read that "The degenerate eye sinks into the orbit and is covered by a flap of skin. Constructive changes have also evolved in cave fish, including enhanced lateral line and gustatory systems." Presumably, the surface fish goes on to develop a functional eye. The researchers make a very interesting observation:

"Cave fish lens cells undergo apoptosis before the arrest of eye development"

And what is apoptosis, you may ask?

apoptosis: a genetically determined destruction of cells from within due to activation of a stimulus or removal of a suppressing agent or stimulus that is postulated to exist to explain the orderly elimination of superfluous cells

Yes, you read that right: the orderly elimination of superflous cells. So, in the cave fish, the development of the eye is arrested. In this experiment, the authors claim they can "stimulate" eye development with the insertion of a lens. However, in the wild, the cave fish embryos are "programmed" to cease development of the advanced eye components. Also, we see that the optic cup (eye socket) is not left bare. The eye socket is covered. Not only is the eye not formed for this deep-dwelling creature, but a covering is provided to seal out contaminants from the socket.

It may be argued that these developments are what is to be expected for a creature that can function without vision. An engineering analogy would be "software code stubs" or "disabled connectors" on common building blocks. Surely, this is not evidence of "poor" or "suboptimal" design. Rather it has all the marks of precise specification.

Now, to the experiment. First, I note these tentative statements:

Quote:

Because extensive apoptosis has not been detected in other eye tissues at this time, lens apoptosis may be an important factor in eye degeneration. Alternatively, lens apoptosis and eye degeneration could be controlled by a signal from the optic cup, which is diminished in cave fish (Fig. 1, A and B).

After explaining the experiment, the conclusion is stated at the end of the paragraph:

Quote:

Conversely, the surface fish lens vesicle did not undergo apoptosis and formed a differentiated lens in the cave fish host (Fig. 2, D and E). Thus, apoptosis is controlled autonomously within the cave fish lens vesicle.

OK, I'll agree with this experimental conclusion. Now, the next three paragraphs go on to explain the development of the "eye" on the transplant side of the cave fish. Although there does appear to be substantial equivocation on the terms "lens" and "lens vesicle", the explanation seems reasonable.

Now, the authors do imply some type of inducement:

Quote:

...Sectioning showed that FLDX labeling was restricted to the lens, indicating that the restored eye parts were derived from the cave fish (Fig. 2, B and C). The results show that a surface fish lens can induce the development of anterior eye parts that have been lost during cave fish evolution.

It would seem that this is a hasty conclusion, since it is possible that the mere presence of a viable transplanted lens would cause general early embryonic eye development to continue towards the formation of a near-complete eye. Furthermore, we should also realize that the authors make no claim that "stimulated" experimental eye was fully functional. But the authors would have us believe that some elusive "signal" is responsible:

Quote:

We conclude that a change in an inductive signal emanating from the lens is a major cause of eye regression in cave fish (20).

This, I find, is unacceptable. The term "signal" is mentioned only four times in the entire article: Once in the abstract, once in the second paragraph, and once in the fourth and concluding paragraphs. Nowhere is this term specifically correlated to the experiment or the results.

The last sentence reads:

Quote:

Our results illustrate how an evolutionary modification in embryonic induction can result in dramatic changes in adult morphology.

This final conclusion is unwarranted and unsubstantiated in this article. The transplant of an organ does not represent an "evolutionary modification", and the means of induction has not been demonstrated.

Vanderzyden

[ October 12, 2002: Message edited by: Vanderzyden ]

[Edit by Kevin Dorner: Unfortunately due to the article being quoted being copyrighted I have removed those parts of it that were not highlighted nor discussed to the best of my ability, in order to qualify the remainder as a fair use excerpt of the original article. Please advise me if critical material was removed, and if so, what other material can be removed instead in order to compensate for any readditions.]

[ October 13, 2002: Message edited by: Kevin Dorner ]

Lizard · 10-12-2002, 04:38 PM

Oops. Never mind. VZ fooled me. He came back right away, with even more nonsense.

It's incredible how much evidence creationists can ignore. Michael Shermer says the only group which denies more reality is Holocaust deniers.

[ October 12, 2002: Message edited by: Lizard ]

Lizard · 10-12-2002, 04:57 PM

Quote:

VZ: No, my concerns have not been addressed.
The argument for "sub-optimal" design remains very weak, at least the way it is presented here.

VZ, it's okay. Really. Behe said "intelligent design" is not necessarily "optimal design." In other words, "intelligence" doesn't imply "high" intelligence. The designer may be fairly primitive and unsophisticated as far as design goes. Maybe *it* learns as it goes along.

The ID promoters are unwilling to say anything about the nature of the "intelligent designer," so anything is possible. Get it?

So you can quit arguing that "intelligent design" has to be "optimal" design. Dr. Behe gives you absolution.

Of course, he's admitted he goofed re: IC, so he is not infallible. However, he promises to correct his errors in "future writings." We are waiting, of course, with bated breath, for those corrections.

10-12-2002, 04:38 PM	#89
Lizard Regular Member Join Date: Apr 2001 Location: Kansas Posts: 169	Oops. Never mind. VZ fooled me. He came back right away, with even more nonsense. It's incredible how much evidence creationists can ignore. Michael Shermer says the only group which denies more reality is Holocaust deniers. [ October 12, 2002: Message edited by: Lizard ]</p>

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10-12-2002, 12:00 PM	#81
Albion Veteran Member Join Date: Jul 2002 Location: US east coast. And www.theroyalforums.com Posts: 2,829	So eyes are an example of good intelligent design whether an aniomal needs them or not, and vestigial eyes are an example of good intelligent design, and lack of vestigial eyes is an example of good intelligent design, and basically everything's an example of good intelligent design. There's science for you!

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