Doubting Didymus

Vaderzygen.

Direstraits addressed this:
"According to the article, the Przewalski wild horse has 66 chromsomes. The domesticated horse has 64 chromosomes. However, despite the genome diffences, the two horses can be crossed and produce fertile offspring."

Genome differences do not pose a problem, the two 'orphaned' chromosomes both line up with the double chromosome. Just as in the horses in the above quote, this causes no problems.

As posted by mageth, different resolutions of g banding use totally different methods, like different languages. You are comparing different g-banding 'languages'. It's like saying that two versions of voltaire are completely different bacause one is in french and one translated to english. it only makes sense to compare g banding in the same 'language'.

You should note if you re-read this thread, that scigirl began her responses to you in a most civil tone. She appears to slowly lose patience with you over time.

Edited to add an earnest question: do you read every post, or do you skip some? Why did you not respond do direstraits's quote about horses which overcome this precise problem?

[ September 05, 2002: Message edited by: Doubting Didymus ]</p>

CRDbulldog

Congratulations, you have finally asked a somewhat intelligent question and I do salute you for it <img src="graemlins/notworthy.gif" border="0" alt="[Not Worthy]" /> However, don't get paranoid. The answer is simple.

The banding pattern in the picture from the Genome Project does not correspond to recognized standards for G-banding. G-banding is produced when the chromosome is stained with a particular stain (Giemsa, if I recall correctly). There are other stains that produce banding patterns on chromosomes that are different. They are called C-banding, Q-banding, and R-banding. These stains all bind at different places on the chromosome so can produce different banding patterns.

I seriously doubt that any stains were used for the banding pattern seen in the Genome Project, however. It is my guess the banding pattern you see is a functional banding pattern based on the location of identified genes within the chromosome and does not correlate with anything you could see with a light microscope.

Cheers,

CRDbulldog

Skeptical

This is a legitimate question that needs an answer. So ok, let's use the scientific method. We have an apparent discrepancy between new data (your picture) and existing data believed to be correct (original picture). Now, I am not a geneticist, so I didn't know what the answer was. However, I know science works, we see the results everyday. Based on the past success of science, I assume there is a reasonable explanation and only reject existing data if there is no reasonable empirical explanation to be had.

First, I hypothesized about the possible causes. Looking at your posted picture and the original, there are obviously some key differences, but for the most part the pictures are very similar with most of the differnces being in the top "half" of the chromosome. Not knowing the exact mechanics of g-banding, I hypothesized that perhaps there are different methods of g-banding responsible for the differences or perhaps, since the pictures appeared to me to be computer generated that there might be differences in resolution responsible as well.

I further hypothesized that whatever the differences between the two pictures, what was needed was a picture of a chimp chromosome using similar g-banding techniques and resolution as used by your picture. Based on this hypothesis, I did a search on google for "chimp+chromosome". I hoped I might find other pictures of chimp chromosomes that might match the picture from the human genome project. One of the hits yielded the following <a href="http://www.indiana.edu/~ensiweb/lessons/chromcom.html" target="_blank">link</a>.

Almost half way down the page, I noticed the following snippet:

"(Optional) Hominoid Karyotypes (all chromosomes of human, chimp, gorilla, and orangutan, side-by-side, for easy comparison). Provided here with the kind permisssion of the lead author, Jorge Yunis, and AAAS (from Yunis' 1982 article in Science). You may notice that the banding patterns on the human and chimp chromosomes on this sheet do not match the enlarged versions on the 4 pages. This is due to the fact that the chromosomes used in this study were taken at a slightly different stage in the mitosis cycle." (emphasis mine)

When it talks about the "sheet" its talking about the same original drawing shown by Scigirl. (check the references)

Then, I looked at the accompanying <a href="http://www.indiana.edu/~ensiweb/lessons/chr.bk1.html" target="_blank">pictures</a> and compared them to the picture you posted and the original picture. I noticed that the human chromosome #2 as listed in all 3 had some key differences in all pictures. However, I noticed also that in the 2 different pictures where the human chromosome was laid out next to the chimp chromosome and the g-banding were done using the same processes during the same phase of mitosis, the g-bandings matched exactly!

This was powerful evidence that when comparing apples to apples, the g-bandings matched between human and chimp chromosomes, even though factors such as the phase of the mitosis cycle could cause different results between different tests. i.e. If you take the g-bands of human and chimp chromosomes at the same phase of mitosis, they match. If you take the g-bands at a different phase of mitosis they still match each other, although the results may differ slightly _between_ the results taken at different phases of mitosis.

This alone provided a very coherent reason with data to back it up showing why the picture you posted differed from the original picture posted by Scigirl. I was in the process of researching further data regarding the g-banding process when I saw Megath's post. This seems to provide additional potential reasons. There may still be others. A geneticist no doubt could provide a more detailed explanation but I think we have enough data to have made the point.

So where does that leave us? In my opinion, the evidence is now even stronger than before. You posted a legitimate question with legitimate data. It needed to be explained. I hypothesized possible explanations based on my limited genetic understanding, performed research and discovered data that provided a very powerful example that human and chimp chromosomes match even when the g-bands are taken during different periods of mitosis. We now have _two_ independent confirmations of this match instead of the single match provided originally. In short, I believe the fact that human and chimp chromosomes match has been re-established along with an additional explanation of why some pictures of g-bands taken under different conditions may not match other pictures exactly. (note again however that human and chimp g-bands taken under the _same_ conditions _do_ match as shown be the 2 separate comparison pictures)

I assure you that I did not know this information beforehand and that my first initial reaction to your post was "hmmm, I wonder why that is?". This is science at work. I conceived a hypothesis to explain new data, looked for confirming or disconfirming evidence, found the evidence and strengthened the existing theory. I hope my rudimentary explanation of the process I followed and the data discovered is sufficient to answer your question.

[ September 05, 2002: Message edited by: Skeptical ]</p>

Skeptical

Let's be clear. The original picture posted by Scigirl clearly shows matching g-bands. You can deny that the data was collected correctly, but you cannot deny that the pictures of the g-bands match. People are not "seeing what they want to see", the picture as shown is irrefutable assuming the data is correct. If you want to argue about the picture, you'll have to argue that the data that supplied the picture was collected incorrectly. It appears that you are trying to do this by posting your other picture. I have to say that at least finally you are making what could be a legitimate point, and its refreshing compared to your other posts. If there were no explanation for the discrepancy, there would be a problem. Fortunately for the common descent theory, there is perfectly legitimate explanation. (see my other post, as well as that of others)

If you disagree with objective data that has been collected by scientists in their fields, data that has passed the rigors of peer review time and time again, the only reasonable explanation can be that you think that scientists are lying about the data. You said you disagreed with the objective data, I reasonably concluded you must believe the scientists are lying, I don't know what other conclusion could be drawn.

Vander, I honestly have not seen you make _any_ points. I have seen you argue about terminology in scientific papers. I have seen you claim that fusions don't occur despite being repeatedly shown several examples of fusions. I have seen you indicate that you don't think there's much evidence for evolution _prior_ to even examining the DNA evidence, which you yourself admitted you knew almost nothing about prior to this thread. If you had actual data to make a point instead of preconceived notions, your points would be seriously addressed. As I said, as far as I can tell this is the first serious question that you have raised, and it needs to and is being addressed.

If your going to criticize something, you need to do so in an honest, legitimate manner. Plenty of criticizing takes place of evolutionary theories between scientists, and they do so based on the objective data. Quote mining, the standard fare of creationists is, as has been pointed out time and time again, the same as lying. Plain and simple. Criticize all you want _as long as you have empirical data_. Saying things like "you just follow evolution because Darwin in your savior" is not data, its a worthless ad hominem attack of no relevance. Ditto for taking quotes out of context and trying to show a scientist saying something they did not. If you have an argument, you have to post your evidence to back it up. None of your previous posts did this, you just made assertions on topics you clearly had not performed adequate research on.

Vander, with all due respect, anyone who claims that fusions don't occur can hardly say that others are "confused". The only real controvery is among those who don't know the facts and those who do. Several clear examples of fusions have been shown to you, yet you seem to still claim "there's no evidence". You still dispute that human chromosome #2 has two centromeres and 2 additional telomeres which is beyond reasonable dispute. You seem to basically argue about things which are known facts to geneticists without any data to back you up and when data is provided to you, you just ignore it.

Hmmm. Makes you wonder what the "powerful" know that the masses don't, ay? (ok, that's off topic, I just couldn't resist)

Ok, great, let's do that. I for one am glad to see an actual challenge based on data and not preconceived notions. Please see my response and that of others to your posted picture.

If this was the basis of your "provisional" denial of the fact that human and chimp chromosomes match, I think your question has been answered in spades if your willing to look at the evidence.

Vanderzyden

Skeptical,

I must say that, on the face of it, your last two posts make several worthy points. By far, they are the most viable replies in the entire thread. However, there are several things that are incorrect. For example: No one, I say no one, has posted anything of substance regarding a demonstration of fusion. The wild/domestic horse hybrid is controversial.

I will review your findings and respond--but it may be a little while.

Incidentally, I am awaiting your response on the other thread.

Vanderzyden

Doubting Didymus

You are not the only one waiting for participation in another thread.

I humbly request your participation in the thread that deals with your original quotes.

If not now or soon, could you give us some idea of the time it will take you to get to this thread?

Jesus Tap-Dancin' Christ

Goddamn gravitationists.

*Sigh*

scigirl, I understand why you are throwing in the towel now. Broken records don't tend to yield new information. Fortunately, the programmers have given us a great graemlin for these moments:
<img src="graemlins/banghead.gif" border="0" alt="[Bang Head]" />
<img src="graemlins/banghead.gif" border="0" alt="[Bang Head]" />
<img src="graemlins/banghead.gif" border="0" alt="[Bang Head]" />

mfaber

Vander, you are wrong. Here is the sequence from of fusion junction in chromosome #2. I have snipped out the flanking regions and just focused on the relic sequences for the telomere fusion. To see the whole unaltered sequence, click on the accession number link below in the sequence header.

• 1. The head or "forward" reading sequence of the first ancestral chromosome is in bold. Telomers are tandem repeats 5'(TTAGGG)3'(this is the sequence on the "forward" strand). Because this fusion happened long ago, mutations have accumulated in this sequence so the "repeats" aren't "perfect"(in base sequence). These sequences don't function as telomers anymore so there is no selective pressure on these now-useless sequences (they are not conserved).
• 2. The tail or "reverse" reading sequence of the joining telomere of the other ancestral chromosome is in bold italics. The repeats are "reversed" 5'(CCCTAA)3'. Again, these repeats aren't "perfect" for the same reason as in 1).

LOCUS HUMCHR2A 1873 bp DNA linear PRI 31-DEC-1994
DEFINITION Human ancestral telomeric fusion DNA sequence.
<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=nucleotide&list_uids=18 0516&dopt=GenBank" target="_blank">ACCESSION NUMBER M73018</a>ORGANISM Homo sapiens
REFERENCE 1 (bases 1 to 1873)
AUTHORS IJdo,J.W., Baldini,A., Ward,D.C., Reeders,S.T. and Wells,R.A.
TITLE Origin of human chromosome 2:an ancestral telomere-telomere fusion
JOURNAL Proc. Natl. Acad. Sci. U.S.A. 88 (20), 9051-9055 (1991)
MEDLINE 92020989 PUBMED 1924367
BASE COUNT 400 a 622 c 526 g 325 t
ORIGIN chromosome 2q13.

Left Flanking sequence deleted(bases 1-480)

481 ttatcccaaa gcaaggcgag gggctgcatt
521 gcaggg ---&gt; tgag gtgagggtga gggtgaggg
541 ttagggtttg ggttgggg ttggggttgggg
571 ttggggtagg gttggggttt gggttggggt
601 tagggttagg ggtaggggta gggtcagggt
631 cagggtcagg gttagggttt tagggttagg
661 gttagggtta aggtttgggg ttggggttgg
691 ggttggggtt aggggttagg ggttaggggt
721 tagggttggg gttgggggtt ggggttgggg
751 ttaggggtag gggtaggggt agggttaggg
781 ttagggttag ggtaagggtt aagggttggg
811 gttggggttg gggttagggt taggggttag
841 ggttag ----&gt; ctaa ccctaaccct aacccctaac
871 ccctaacccc aacccaaacc ccaaccccaa
901 ccccaaccct acccctaccc ctaaccccaa
931 cccttaaccc ttaaccctta acccttaccc
961 taaccctaac ccaaacccta accctaaccc
991 taccctaacc caaccctaac cctaacccta
1021 ccctaagcct aaaaccctaa aaccgtgacc
1051 ctgaccttga ccctgaccct taacccttaa
1081 cccttaaccc taaccctaac cataacccta
1111 aaccctaacc ctaaacccta accctaccct
1141 aaccccaacc cctaacccta acccctatac
1171 cctaacccta accctacccc tacccctaac
1201 cccaacccca gccccaaccc caacccttac
1231cctaacccta cctaaccctt aaccctaacc
1261 cctaacccta acccctaacc ctaccccaac
1291 cccaaaccca accctaaccc aaccctaacc
1321 caaccctaac ccctacccta acccctaacc
1351 ctaaccccta ccctaacccc taaccctaac
1381 ccctacccta acccctaacc ctagccctag
1411 ccctaaccct aaccctcacc ctaaccctca
1441 ccctaaccct caccctcacc ctcaccctca
1471 ccctaaccca a cgtctgtgc tgagaagaat

Right Flanking Sequence deleted(bases 1491-1783)

Here is the PNAS PDF file of this paper and the pertinent image is the Figure on page 2:
<a href="http://www.pnas.org/cgi/reprint/88/20/9051.pdf" target="_blank">http://www.pnas.org/cgi/reprint/88/20/9051.pdf</a>

From reading your posts, I think part of your problem is that you don't have a grasp of how DNA and chromosomes are structured, how DNA is replicated, or why telomeres are so important. I have included some websites that hopefully will help you.

1) DNA structure
<a href="http://www.web-books.com/MoBio/Free/Ch3B.htm" target="_blank">http://www.web-books.com/MoBio/Free/Ch3B.htm</a>

2) How DNA is replicated
<a href="http://www.web-books.com/MoBio/Free/Ch7B3.htm" target="_blank">http://www.web-books.com/MoBio/Free/Ch7B3.htm</a>

3) Finishing Eukaryotic DNA Replication:
Regeneration of the Ends (Telomers) by the Enzyme Telomerase
<a href="http://www.web-books.com/MoBio/Free/Ch7C.htm" target="_blank">http://www.web-books.com/MoBio/Free/Ch7C.htm</a>

Animated Teleomerase in action
<a href="http://faculty.plattsburgh.edu/donald.slish/Telomerase.html" target="_blank">http://faculty.plattsburgh.edu/donald.slish/Telomerase.html</a>

Purpose, function and structure of Telomerase
<a href="http://www.biochem.arizona.edu/classes/bioc462/462bH2002/462bHonorsProjects/462bHonors1999/bentley/ase.html" target="_blank">http://www.biochem.arizona.edu/classes/bioc462/462bH2002/462bHonorsProjects/462bHonors1 999/bentley/ase.html</a>

4)Genetic Science Learning Center, Uni. of Utah This is a great site for just the basics!
<a href="http://gslc.genetics.utah.edu/" target="_blank">http://gslc.genetics.utah.edu/</a>

Start with the Basics and Beyond tutorial
especially if you had trouble understanding 1-3. I have no idea what your science background is and if these are too simple for you, then I want you to know that no insult was intended.....

[ September 05, 2002: Message edited by: mfaber ]</p>

Blinn

Let me give you a more substantial answer than i did last night. I was growing weary of this. Both images are idealized drawings of chromosome number two, based on staining techniques that others have elaborated on here. If you start at the centromere and follow the bands, they match up one for one, keeping in mind that narrower subset bands have not been included in some cases. This is attributable to the fact that "increased resolution allows the visualization of multiple minor bands within a single previously defined sub-band."

About 2/3 of the way down the right left idiogram, one encounters a white band containing a narrow black band. Its counterpart in the right image is a narrow white band. The relative widths of these two white bands are the sole discrenpency that I can find between the two idiograms.

Clutch

"We"? You have tapeworms?

Your baffling non-sequitur I won't even touch. Just, please, cease the virtuoso performance in evidence-avoidance. Go back and respond to the posts that have from the outset eviscerated your OP and subsequent posts.