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.
This stuff is way out of my field of knowledge. I'm surprised to learn that we have one less pair of chromosomes than the apes. I would have thought more pairs would be indicative of further evolutionary advancement.
Implying that women don't have this protein?
Blah blah blah, a bunch of big words perpetuating a lie that we evolved from apes.
What's that supposed to mean? I love it when bad logic is portrayed as science. Sure the scientists in question have identified the functions of gene sequences with great precision and skill but, to jump from there to the rest is simply rediculous. Everybody be nice? There's no need to be mean to anyone just for being wrong. It's their God given right :)
Haven't the evos at FR been assuring us for years that the fusion of the two ape chromosomes was a fact? On at least one recent thread they even had pictures pointing to where the centromere would have been. How can these evo scientists just now be announcing proof of what your team has long assured me HAS ALREADY BEEN PROVEN?
This wouldn't have happened if Bush had OK'd the Kyoto Protocol!
Yeah, but hardly irreducible even in the wildest fantasy, which is why the ID raconteurs don't torture us endlessly about titin. It basically evolved from a series of gene duplications in tandem with the evolution of multicellularity, giving rise to regularly repeating domain patterns.
Blah blah blah, a bunch of big words perpetuating a lie that we evolved from apes.
Yeah, really big words there. Must be all the way up to the 8th grade.
But really, the discovery of a 36,000 base pair sequence is really just a cosmic joke that G-d is playing on us to make us think that evolution happened. At least that is the viewpoint of our creationist "scientists" with their mail order Ph.Ds.
No, I wasn't claiming that it was. What this article says could just as easily be interpreted one way as the other. For instance, if God were designing apes and men, it stands to reason that He would use many of the same materials.
(I'm not saying that's the case, I'm just saying that this doesn't really prove that men evolved from apes. Before Darwin came along, the "great chain of being" that goes back to the ancient Greeks organized the members of the animal and plant kingdoms in much the same way as Darwinists did later. It was understood that there was a hierarchy of complexity, or of lower and higher orders.)
Scientists discover we have one fewer chromosome than the apes and then find a large section of one of our chromosomes that looks like it used to be a centromere.
The theory that fusion took place is a good one. It may not be correct, but there is evidence that it is.
It's hardly a ridiculous theory.
Here's an example of a ridiculous theory: the big sky-daddy is testing our faith by planting this genetic evidence.
God would not use materials, he would conjure them. ;^)
He's not trying to "make us think" any such thing. Rather, He made us out of the same protiens because he made us out of the same kinds atoms - which work in the same way. Why do some people make things so complicated?
Funny that false evidence trail (a pseudo-centromere sequence) would be there if humans and apes are separately created. It's as if someone wanted to fake a chromosome fusion event in the history of humans. </creo-mode>
Genesis says otherwise...
Creationism is knowing when not to look.
I don't think anything can be proved in science. There are only theories that best fit the evidence.
What's interesting about this, though, is that science predicted fusion, and lo, here we have more evidence for it.
It really is too bad, though, that there isn't some book somewhere that already contains all the answers. Instead, scientists have to constantly check their theories and do research.
Hmmmm.. I see an awful lot of "let there be"s in my version of Genesis....