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Scientists Analyze Chromosomes 2 and 4: Discover Largest "Gene Deserts"
National Human Genome Research Institute ^ | 06 April 2005 | Staff

Posted on 04/13/2005 6:20:23 PM PDT by PatrickHenry

A detailed analysis of chromosomes 2 and 4 has detected the largest "gene deserts" known in the human genome and uncovered more evidence that human chromosome 2 arose from the fusion of two ancestral ape chromosomes, researchers supported by the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health (NIH), reported today.

In a study published in the April 7 issue of the journal Nature, a multi-institution team, led by [load of names deleted, but available in the original article].

"This analysis is an impressive achievement that will deepen our understanding of the human genome and speed the discovery of genes related to human health and disease. In addition, these findings provide exciting new insights into the structure and evolution of mammalian genomes," said Francis S. Collins, M.D., Ph.D., director of NHGRI, which led the U.S. component of the Human Genome Project along with the DOE.

Chromosome 4 has long been of interest to the medical community because it holds the gene for Huntington's disease, polycystic kidney disease, a form of muscular dystrophy and a variety of other inherited disorders. Chromosome 2 is noteworthy for being the second largest human chromosome, trailing only chromosome 1 in size. It is also home to the gene with the longest known, protein-coding sequence - a 280,000 base pair gene that codes for a muscle protein, called titin, which is 33,000 amino acids long.

One of the central goals of the effort to analyze the human genome is the identification of all genes, which are generally defined as stretches of DNA that code for particular proteins. The new analysis confirmed the existence of 1,346 protein-coding genes on chromosome 2 and 796 protein-coding genes on chromosome 4.

As part of their examination of chromosome 4, the researchers found what are believed to be the largest "gene deserts" yet discovered in the human genome sequence. These regions of the genome are called gene deserts because they are devoid of any protein-coding genes. However, researchers suspect such regions are important to human biology because they have been conserved throughout the evolution of mammals and birds, and work is now underway to figure out their exact functions.

Humans have 23 pairs of chromosomes - one less pair than chimpanzees, gorillas, orangutans and other great apes. For more than two decades, researchers have thought human chromosome 2 was produced as the result of the fusion of two mid-sized ape chromosomes and a Seattle group located the fusion site in 2002.

In the latest analysis, researchers searched the chromosome's DNA sequence for the relics of the center (centromere) of the ape chromosome that was inactivated upon fusion with the other ape chromosome. They subsequently identified a 36,000 base pair stretch of DNA sequence that likely marks the precise location of the inactived centromere. That tract is characterized by a type of DNA duplication, known as alpha satellite repeats, that is a hallmark of centromeres. In addition, the tract is flanked by an unusual abundance of another type of DNA duplication, called a segmental duplication.

"These data raise the possibility of a new tool for studying genome evolution. We may be able to find other chromosomes that have disappeared over the course of time by searching other mammals' DNA for similar patterns of duplication," said Richard K. Wilson, Ph.D., director of the Washington University School of Medicine's Genome Sequencing Center and senior author of the study.

In another intriguing finding, the researchers identified a messenger RNA (mRNA) transcript from a gene on chromosome 2 that possibly may produce a protein unique to humans and chimps. Scientists have tentative evidence that the gene may be used to make a protein in the brain and the testes. The team also identified "hypervariable" regions in which genes contain variations that may lead to the production of altered proteins unique to humans. The functions of the altered proteins are not known, and researchers emphasized that their findings still require "cautious evaluation."

In October 2004, the International Human Genome Sequencing Consortium published its scientific description of the finished human genome sequence in Nature. Detailed annotations and analyses have already been published for chromosomes 5, 6, 7, 9, 10, 13, 14, 16, 19, 20, 21, 22, X and Y. Publications describing the remaining chromosomes are forthcoming.

The sequence of chromosomes 2 and 4, as well as the rest of the human genome sequence, can be accessed through the following public databases: GenBank (www.ncbi.nih.gov/Genbank) at NIH's National Center for Biotechnology Information (NCBI); the UCSC Genome Browser (www.genome.ucsc.edu) at the University of California at Santa Cruz; the Ensembl Genome Browser (www.ensembl.org) at the Wellcome Trust Sanger Institute and the EMBL-European Bioinformatics Institute; the DNA Data Bank of Japan (www.ddbj.nig.ac.jp); and EMBL-Bank (www.ebi.ac.uk/embl/index.html) at EMBL's Nucleotide Sequence Database. [Links in original article.]

NHGRI is one of the 27 institutes and centers at NIH, an agency of the Department of Health and Human Services. The NHGRI Division of Extramural Research supports grants for research and for training and career development at sites nationwide. Additional information about NHGRI can be found at www.genome.gov.


TOPICS: Culture/Society; Miscellaneous; Philosophy
KEYWORDS: chromosomes; crevolist; dna; evolution; genetics
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To: Echo Talon
well, where has one species turned into another?

Sometimes, in particular geographical circumstances, we can see it happening right now.

141 posted on 04/14/2005 1:57:30 AM PDT by Thatcherite (Conservative and Biblical Literalist are not synonymous)
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To: Thatcherite

XenuDidit placemarker


142 posted on 04/14/2005 2:02:14 AM PDT by dread78645 (Sarcasm tags are for wusses.)
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To: dread78645

My money is still on the HBX17 series nanobot hive-mind complexes from the planet Tharg. Individually dumb, but collectively the most awesome intelligence in this spiral arm.


143 posted on 04/14/2005 2:06:14 AM PDT by Thatcherite (Conservative and Biblical Literalist are not synonymous)
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To: Thatcherite
My money is still on the HBX17 series nanobot hive-mind complexes

Oh? What's the point spread?

144 posted on 04/14/2005 2:12:33 AM PDT by dread78645 (Sarcasm tags are for wusses.)
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To: dread78645
Oh? What's the point spread?

Fixed odds, 666-1.

145 posted on 04/14/2005 2:13:47 AM PDT by Thatcherite (Conservative and Biblical Literalist are not synonymous)
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To: Thatcherite

that didnt turn into a different species. that would be an example of microevolution.


146 posted on 04/14/2005 2:28:47 AM PDT by Echo Talon (http://echotalon.blogspot.com)
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To: Echo Talon
that didnt turn into a different species. that would be an example of microevolution.

The Southern ones can't interbreed. They look different. If a cataclysm had destroyed the Northern areas before we found them we'd definitely regard them as a separate species. Yet we can see the gradations back to them being the same species. Ring species permit us to see the process of speciation in action. The distinction that you make between microevolution and macroevolution is a false one. Macroevolution is simply many generations of microevolution.

147 posted on 04/14/2005 2:34:47 AM PDT by Thatcherite (Conservative and Biblical Literalist are not synonymous)
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To: Echo Talon
Microevolution leads to macroevolution. The reason that the salamanders at the ends which cannot interbreed are not considered a different species is because each subspecies can breed with the neighboring subspecies. But, by the time the ends of the ring meet they can no longer interbreed - they've evolved apart. If you got rid of the transitional populations in between, you'd officially have different species.

Another example is the Greenish Warbler:


148 posted on 04/14/2005 2:36:36 AM PDT by AntiGuv (™)
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To: Echo Talon
And another is the Larus Gull:


149 posted on 04/14/2005 2:37:51 AM PDT by AntiGuv (™)
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To: Echo Talon
Dont ya know, they say we came from some slimy thing from the ocean... and just poof the human body had morphed into the great body that we have today. pretty amazing really...

Or, you could believe something far more complex than that.

150 posted on 04/14/2005 2:44:57 AM PDT by laredo44 (Liberty is not the problem)
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To: laredo44; Echo Talon
we came from some slimy thing from the ocean... and just poof the human body had morphed into the great body that we have today

If echo talon ever met anyone who believed that, then certainly that person didn't believe in the theory of evolution. large changes happening by the "poof" mechanism is largely the preserve of supernatural beliefs.

151 posted on 04/14/2005 2:48:08 AM PDT by Thatcherite (Conservative and Biblical Literalist are not synonymous)
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To: Echo Talon

Opps! I meant Herring Gull..


152 posted on 04/14/2005 2:49:04 AM PDT by AntiGuv (™)
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To: PatrickHenry

Hmm, two large gene deserts. Well, it looks as if the Good Lord has a plan for us. He's left room to add stuff as needed. It's like soup. A little seasoning, then taste to see what's missing...and add that.


153 posted on 04/14/2005 2:55:51 AM PDT by hershey
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To: Echo Talon

PS. The map might be deceptive because the 'ends' of the ring are the overlapping North Sea range of the Herring Gull and the Lesser Black-Backed Gull. They don't look much alike at all (as gulls go) and cannot interbreed although they can breed with the neighboring gulls to the west or the east, respectively, and on around the ring. These are actually considered six full blown species, although technically they are seven subspecies.


154 posted on 04/14/2005 3:04:19 AM PDT by AntiGuv (™)
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To: PatrickHenry

extremely cool.....I really love this stuff. you know the fact that interests me the most...(not from this piece) is that Humans are genetically closer to chimps and bonobo's than any frog specie is to any other frog specie.


155 posted on 04/14/2005 3:10:55 AM PDT by Vaquero ("There is nothing lower than the human race - except the french." (Mark Twain))
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To: Echo Talon
how do you ToE isnt an APE that went extinct?

I'm guessing that what you mean is all those dubious skulls that the anti-evolutionaries can't agree on the classification of are different species of extinct ape. Firstly you have to realise that is *not* what those with some knowledge on the anti-evolution side are saying; its just something that you are clutching at, right? So that's 5 distinct species (just in that article) closer to human than any modern non-human that you are speculating have gone extinct. (and no fossil record of where modern humans or apes were at that time, curious that). At what point would you give up on that belief? If 10 were found? 15? 20? 50? 100? How perfect do you need the graduated fossil record to be before you start questioning anti-evolution? The fossil record is getting better all the time... Best not rest your faith on no further intermediate finds.

Something that you need to understand is that the fossil record has hardly any modern forms, and the deeper you go down the geological column the less the organisms you find resemble modern forms (deeper = more distant past). Does that fact suggest anything to you? It suggested a lot to many christian biologists, geologists, and paleontologists of the early 19th Century. Darwin just put together into a coherent whole what a lot of scientists were already seeing parts of; and most importantly he put forward natural selection as the driving force. It is not a coincidence that during the voyage of the Beagle Darwin was having the volumes of Lyell's geology works shipped out to him.

156 posted on 04/14/2005 3:15:39 AM PDT by Thatcherite (Conservative and Biblical Literalist are not synonymous)
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To: Thatcherite

I dont care if you had a perfectly preserved "ape-man" i wouldn't believe evolution. I could explain it away as a genetic defect. You have your beliefs and I have mine. In the end when your before the lord you can explain yourself.


157 posted on 04/14/2005 3:19:28 AM PDT by Echo Talon (http://echotalon.blogspot.com)
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To: Echo Talon
So essentially no amount of physical evidence would convince you? If so then what is the point in this discussion?

Earlier in this thread you appeared to be sure that evolution is not science and that there is no evidence for it. Now you have been shown plenty of evidence, and been told that scientists of all religions (including thousands of christians) the world over consider that ToE meets all the criteria to be considered science (in fact the volume of evidence for ToE places it amongst the most solidly grounded areas of science) you appear to be not interested in the evidence.

158 posted on 04/14/2005 3:28:10 AM PDT by Thatcherite (Conservative and Biblical Literalist are not synonymous)
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To: Thatcherite

Retreat to statement of literal biblical faith placemarker.


159 posted on 04/14/2005 3:31:51 AM PDT by Thatcherite (Conservative and Biblical Literalist are not synonymous)
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To: Echo Talon
In the end when your before the lord you can explain yourself.

As can you. Created in His image with a brain programmed to seek out explanations and you think it is appropriate to stick your head in the sand. Good luck when He asks, "What did you think of all that evidence I provided for evolution?" Your explanation may be found wanting.

160 posted on 04/14/2005 3:34:37 AM PDT by laredo44 (Liberty is not the problem)
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