Freethought & Rationalism Archive

tgamble · 04-27-2003, 06:16 AM

http://www.theologyweb.com/forum/sho...9961#post79961

"And to return to the thread, there are plenty of features that are contrary to what is predicted by common ancestry evolution, but they are explained away as convergent evolution. For example, an antigen receptor protein has the same unusual single chain structure in camels and nurse sharks, but this cannot be explained by a common ancestor of sharks and camels (Proceedings of the National Academy of Sciences 95:11,804)."

Anyone have this reference handy? I don't trust Socrates to be honest about his sources. Most likely he got it from this bit of AIg propaganda.
http://www.answersingenesis.org/news...c_american.asp

I suspect that the claim is ignorant as his claim that "The �-hemoglobin of crocodiles has more in common with that of chickens (17.5 %) than that of vipers (5.6 %), their fellow reptiles." which is true, but Sarfati seems to think it somehow contradicts common descent.

Wounded King · 04-27-2003, 06:41 AM

Roux KH, Greenberg AS, Greene L, Strelets L, Avila D, McKinney EC, Flajnik MF. Structural analysis of the nurse shark (new) antigen receptor (NAR): molecular convergence of NAR and unusual mammalian immunoglobulins.
Proc Natl Acad Sci U S A. 1998 Sep 29;95(20):11804-9.

Socrates just doesnt seem to be familiar with how to write a decent citation.

pz · 04-27-2003, 06:51 AM

Quote:

Originally posted by tgamble
http://www.theologyweb.com/forum/sho...9961#post79961

"And to return to the thread, there are plenty of features that are contrary to what is predicted by common ancestry evolution, but they are explained away as convergent evolution. For example, an antigen receptor protein has the same unusual single chain structure in camels and nurse sharks, but this cannot be explained by a common ancestor of sharks and camels (Proceedings of the National Academy of Sciences 95:11,804)."

Anyone have this reference handy? I don't trust Socrates to be honest about his sources.

You are wise not to.

Here's the abstract:

Quote:

Structural analysis of the nurse shark (new) antigen receptor (NAR): Molecular convergence of NAR and unusual mammalian immunoglobulins

Kenneth H. Roux, Andrew S. Greenberg, Lesley Greene, Lioudmila Strelets*, David Avila�, E. Churchill McKinney, and Martin F. Flajnik

_ABSTRACT
We recently have identified an antigen receptor in sharks called NAR (new or nurse shark antigen receptor) that is secreted by splenocytes but does not associate with Ig light (L) chains. The NAR variable (V) region undergoes high levels of somatic mutation and is equally divergent from both Ig and T cell receptors (TCR). Here we show by electron microscopy that NAR V regions, unlike those of conventional Ig and TCR, do not form dimers but rather are independent, flexible domains. This unusual feature is analogous to bona fide camelid IgG in which modifications of Ig heavy chain V (VH) sequences prevent dimer formation with L chains. NAR also displays a uniquely flexible constant (C) region. Sequence analysis and modeling show that there are only two types of expressed NAR genes, each having different combinations of noncanonical cysteine (Cys) residues in the V domains that likely form disulfide bonds to stabilize the single antigen-recognition unit. In one NAR class, rearrangement events result in mature genes encoding an even number of Cys (two or four) in complementarity-determining region 3_(CDR3), which is analogous to Cys codon expression in an unusual human diversity (D) segment family. The NAR CDR3 Cys generally are encoded by preferred reading frames of rearranging D segments, providing a clear design for use of preferred reading frame in antigen receptor D regions. These unusual characteristics shared by NAR and unconventional mammalian Ig are most likely the result of convergent evolution at the molecular level.

The gist of the story is that, unlike the typical antigen receptor which consists of heavy and light chains, they have found that nurse sharks express an antigen receptor that consists of only the heavy chain. Something similar has been seen in camels and llamas, where "two of their three IgG subclasses contain no L chains and the unassociated VH domains interact with antigen as monomers". So, basically, we have a case where certain animals use a monomer rather than a dimer -- something that isn't too hard to imagine happening independently in evolution.

The real kicker, though, and evidence that that fraud Socrates never read the paper, is this bit from the conclusion:

Quote:

There is every reason to believe that the camelid V regions represent bona fide mammalian VH that recently have been modified to form monomers as they have up to 75% amino acid identity with other mammalian V regions. Can the same be said for the NAR V domain? Of the various unique characteristics of NAR, two stand out. First, the overall NAR V sequence is not at all similar to conventional IgVH (25% identity) and is only somewhat more similar to VL and TCR V (3), suggesting that NAR must have diverged from Ig/TCR long ago. The origin of the second characteristic, the unpaired V domain, is less obvious. It may have been an early trait that coevolved with or perhaps influenced the overall uniqueness of the NAR V domain sequence. By this view, the unpaired V domain may represent a primordial relic that has been superseded largely by the more efficient two-domain, antigen-binding motifs.

They know the sequence. The camel monomer has a sequence that is very similar to that of mammals in general, suggesting a recent divergence. The nurse shark monomer is very, very different in sequence, suggesting a much more ancient divergence.

Coragyps · 04-27-2003, 10:14 AM

FWIW, PNAS has free access to their archives from 1990 to (?) 3 months ago, here. Science isn't quite as generous, but Sept 1996 to one year ago is all available over there with free registration.

WinAce · 04-27-2003, 10:15 AM

Ah, I see you made a thread devoted to mine. Good job.

I really think the fact that they have nothing which contradicts evolution, despite the dozen or so examples I listed, will hurt their position significantly vis a vis the readers. They already suffered crushing, Waterloo-eque style defeats on the ERV and "operational vs. origins science" threads... (hats off to Vorkosigan)

RufusAtticus · 04-27-2003, 02:37 PM

Yeah, I found it intesting the T5S dropped the observation/inference thread when I asked him what he knew about DNA fingerprinting & sequencing. (He had already labeled them as observations.) Perhaps he realized that if he answered he'd have to admit that no observation happens without inference.

lpetrich · 04-27-2003, 02:47 PM

Quote:

Originally posted by tgamble
I suspect that the claim is ignorant as his claim that "The �-hemoglobin of crocodiles has more in common with that of chickens (17.5 %) than that of vipers (5.6 %), their fellow reptiles." which is true, but Sarfati seems to think it somehow contradicts common descent.

I think that Sarfati expects the family tree to be

Birds
Reptiles
- Snakes
- Crocodilians

When it is actually

Snakes
Archosaurs
- Crocodilians
- Birds

Doubting Didymus · 04-27-2003, 04:10 PM

Quote:

"The �-hemoglobin of crocodiles has more in common with that of chickens (17.5 %) than that of vipers (5.6 %), their fellow reptiles."

Just repeating that for posterity.

Their fellow reptiles. Their FELLOW reptiles. The monophyletic group containing only reptiles.

What is this safarti persons education? Has he, in his life, ever studied a little obscure field called biology? I know dinosaur - obsessed primary schoolers who would have a better knowledge of scaly-thing phylogeny.

lpetrich · 04-27-2003, 04:43 PM

Creationist Jonathan Sarfati is a physical chemist and spectroscopist.

For some strange reason, a large number of creationists are engineers, though some are physical scientists (Jonathan Sarfati), some are earth scientists (Andrew Snelling), and a few are biological ones (Duane Gish, Jonathan Wells).

Here is an introduction to Andrew Snelling; also check out his two-faced career. Is he an old-earth mainstream geologist or a young-earth flood geologist?

New Jerry Smith · 04-27-2003, 06:43 PM

Boys & Girls, I have spent a fair bit of time reading Socrates' posts on Theology Web, and I'd go dollars to doughnuts that Socrates is Jon Safarti of AiG.

The rhetoric is the same.
The arguments are the same.
Both are from NZ or OZ (whichever).
Both have "high science qualifications" in "chemistry".
He uses language and links from AiG without apology or the least bit of shame.
He uses no other sources.
He is very protective of his anonymity, something relatively uncommon among individuals who are 'faceless' to begin with.

All that's left is ---- does he play chess?

04-27-2003, 06:16 AM	#1
tgamble Veteran Member Join Date: Sep 2000 Location: St. John's, Nfld. Canada Posts: 1,652	Evidence that contradicts common descent. http://www.theologyweb.com/forum/sho...9961#post79961 "And to return to the thread, there are plenty of features that are contrary to what is predicted by common ancestry evolution, but they are explained away as convergent evolution. For example, an antigen receptor protein has the same unusual single chain structure in camels and nurse sharks, but this cannot be explained by a common ancestor of sharks and camels (Proceedings of the National Academy of Sciences 95:11,804)." Anyone have this reference handy? I don't trust Socrates to be honest about his sources. Most likely he got it from this bit of AIg propaganda. http://www.answersingenesis.org/news...c_american.asp I suspect that the claim is ignorant as his claim that "The �-hemoglobin of crocodiles has more in common with that of chickens (17.5 %) than that of vipers (5.6 %), their fellow reptiles." which is true, but Sarfati seems to think it somehow contradicts common descent.

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search

04-27-2003, 06:41 AM	#2
Wounded King Veteran Member Join Date: Mar 2003 Location: Edinburgh Posts: 1,211	Roux KH, Greenberg AS, Greene L, Strelets L, Avila D, McKinney EC, Flajnik MF. Structural analysis of the nurse shark (new) antigen receptor (NAR): molecular convergence of NAR and unusual mammalian immunoglobulins. Proc Natl Acad Sci U S A. 1998 Sep 29;95(20):11804-9. Socrates just doesnt seem to be familiar with how to write a decent citation.

04-27-2003, 10:14 AM	#4
Coragyps Veteran Join Date: Aug 2001 Location: Snyder,Texas,USA Posts: 4,411	FWIW, PNAS has free access to their archives from 1990 to (?) 3 months ago, here. Science isn't quite as generous, but Sept 1996 to one year ago is all available over there with free registration.

04-27-2003, 10:15 AM	#5
WinAce Beloved Deceased Join Date: Feb 2002 Location: Carrboro, NC Posts: 1,539	Ah, I see you made a thread devoted to mine. Good job. I really think the fact that they have nothing which contradicts evolution, despite the dozen or so examples I listed, will hurt their position significantly vis a vis the readers. They already suffered crushing, Waterloo-eque style defeats on the ERV and "operational vs. origins science" threads... (hats off to Vorkosigan)

04-27-2003, 02:37 PM	#6
RufusAtticus Veteran Member Join Date: Nov 2001 Location: NCSU Posts: 5,853	Yeah, I found it intesting the T5S dropped the observation/inference thread when I asked him what he knew about DNA fingerprinting & sequencing. (He had already labeled them as observations.) Perhaps he realized that if he answered he'd have to admit that no observation happens without inference.

04-27-2003, 04:43 PM	#9
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	Creationist Jonathan Sarfati is a physical chemist and spectroscopist. For some strange reason, a large number of creationists are engineers, though some are physical scientists (Jonathan Sarfati), some are earth scientists (Andrew Snelling), and a few are biological ones (Duane Gish, Jonathan Wells). Here is an introduction to Andrew Snelling; also check out his two-faced career. Is he an old-earth mainstream geologist or a young-earth flood geologist?

04-27-2003, 06:43 PM	#10
New Jerry Smith Junior Member Join Date: Feb 2003 Location: Tennessee Posts: 9	Boys & Girls, I have spent a fair bit of time reading Socrates' posts on Theology Web, and I'd go dollars to doughnuts that Socrates is Jon Safarti of AiG. The rhetoric is the same. The arguments are the same. Both are from NZ or OZ (whichever). Both have "high science qualifications" in "chemistry". He uses language and links from AiG without apology or the least bit of shame. He uses no other sources. He is very protective of his anonymity, something relatively uncommon among individuals who are 'faceless' to begin with. All that's left is ---- does he play chess?

Freethought & Rationalism Archive

The archives are read only.