Skip to comments.Scientists Analyze Chromosomes 2 and 4: Discover Largest "Gene Deserts"
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.
That sounds very reasonable. I hope that you will avail yourself the opportunity to remind some of the evos on this board of that when they become to strident and dogmatic. It seems from behind my keyboard that they write like evolution is a proven fact and to believe otherwise makes you "demon-possessed". If you are a new poster on this board you may not believe that, but that is the term they use to people who fail to interpret the evidence the way they think we should.
In this instance for example, if there was a fusion, and if the fusion point has indeed been found, it only shows where the "cut and paste" was, not whether an ID or blind evolution performed the operation!
Considering how little we actually know about the specific proteins coded by DNA in a cell, I don't think it's particularly wise to go around unilaterally declaring all these gene deserts.
I wouldn't be surprised to find that these deserts, much like the tonsils and appendix, aren't as vestigial and unused as biologists currently maintain they are.
Interestingly enough, an evolutionary paradigm led to the wrong conclusions about the appendix and tonsils being vestigial.
PS- even those of us who believe in Revelation as a source for truth believe that our interpretations of those revelations must be examined.
So where are all the 500 million year old apes? If there's no relationship between the apes' genes, why do they exist at roughly the same time in history?
Where would you propose they came from?
"...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. "
Well, I'll be a monkey's uncle. Where is WJB when you need him?
(could this fusion have created this "gene desert"?)
If we evolved from apes, what did apes evolve from? I've never had that question answered.
The absence of Open Reading Frames is good evidence for a "desert".
Gene sequencing technology has found many genes that were previously unknown by examining for open reading frames. This technology also allows us to sequence proteins, which was a real arduous task in the old days (sigh... I guess I am getting to the point where I belong with the dinosaurs).
Nephew, more likely.
could this fusion have created this "gene desert"?
The gene desert is proof of the Fall. And the Flood. And design. And Darwin's degeneracy.
"Mmmm, jean desserts."
It was most recently the medical industry, but now has become incorporated into the State as the Medical Institute. As soon as somebody damanded the right to medical care the game was over.
tree shrews -> lemurs -> tarsiers -> apes* -> humans
* The earliest apes differentiated from ancestral haplorhines during the early Miocene Epoch, about 18-22 million years ago.
PS. Keep in mind that the modern critters listed above are just approximations of the ancestral creatures, as the extant species have also continued to evolve, though with lesser divergence. Note that monkeys diverged down their own path from tarsiers, and so apes did not evolve from monkeys, contrary to popular cliché.
Rollin' Rollin' Rollin'
Keep the Luddites rollin'
Ya can't understand 'em
Just rope, tie and brand 'em
Soon they'll be at the end of their line.
OK. What process would create apes, then a couple millions of years later, humans with similar genes?
The problem with convergence theory in this sense is that these features that are deemed emblematic of common ancestry are to a degree arbitrary. There is no reason for them to have emerged independently with precisely this arrangement (or even close to it, in the traits discussed above).