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.
I wonder how much of the "desert" genes relate to the fact that genes can also be read by RNA three dimentionally. Protein production is not always linear along a DNA strand like we see on simple TV animations.
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...
How do you supppose that first 23 Chromosomer haploid felt when he met his female counterpart, the 24 Chromosomer haploid?
Pond Scum Alert
"You keep your faith in man and Scientology and I will keep mine in the Lord."
If you think Scientology has anything to do with science, Tom Cruise would like to speak to you.
Dunno.
What process would create mice with human neurons?
very kinky
"How do you supppose that first 23 Chromosomer haploid felt when he met his female counterpart, the 24 Chromosomer haploid?"
Don't leave me in suspense, whats the punchline??
Well, if you believe that we evolved from the ocean into an ape and then into a human, you sure as heck aren't a Christian or Jew. Not sure if they allow for that sort of thing in scientology but im sure they do.
"How do you supppose that first 23 Chromosomer haploid felt when he met his female counterpart, the 24 Chromosomer haploid?"
Don't leave me in suspense, whats the punchline??
"centromere" I don't use the metric system, what's this about half an inche?
That wasn't a joke, it was haploid for thought. Think about it. :-}
There are a great many Christians and Jews that would disagree with you.
Yeah, yeah. I heard you the first time.
I think he starts feeling the most delicious parts and moves on from there.
Or how about "Hot Mama"?
It doesn't matter if they disagree with me or not, they disagree with the Bible.
Well, if you believe that we evolved from the ocean into an ape and then into a human, you sure as heck aren't a Christian or Jew.
There are a great many Christians and Jews that would disagree with you.
Pope John Paul II being one of them.
“[N]ew findings lead us toward the recognition of evolution as more than a hypothesis. In fact it is remarkable that this theory has had progressively greater influence on the spirit of researchers, following a series of discoveries in different scholarly disciplines. The convergence in the results of these independent studies—which was neither planned nor sought—constitutes in itself a significant argument in favor of the theory.”
“A theory is a meta-scientific elaboration, which is distinct from, but in harmony with, the results of observation. With the help of such a theory a group of data and independent facts can be related to one another and interpreted in one comprehensive explanation. The theory proves its validity by the measure to which it can be verified. It is constantly being tested against the facts; when it can no longer explain these facts, it shows its limits and its lack of usefulness, and it must be revised.”
-- Pope John Paul II, 23 October 1996.
"It doesn't matter if they disagree with me or not, they disagree with the Bible"
I guess that's settled and we can all go home now.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.