Hominoid genes meet on middle ground

November 14, 1999

Evolution loves a fluid genome. Chromosomes that copy, shift, and mutate their genes provide the fuel for evolutionary change. Indeed, as shown by Evan Eichler (Case Western Reserve School of Medicine) and colleagues in the November issue of Genome Research, the hominoid genome has used diverse strategies for self-alteration, including a newly discovered form of gene copying called pericentromeric duplication.

Scientists have discovered numerous examples of gene duplication in the history of our genome. In some cases, mismatching exchanges between chromosomes have strung multiple copies of a gene together, like beads on a necklace. In rarer, ancient episodes, the genome acquired extra copies of whole chromosomes. However, data from the Human Genome Project reveals a potentially different form of gene duplication occurring at the centers of chromosomes, near the centromeres. Researchers sequencing these pericentromeric regions have unearthed copies of genes whose original versions reside in distant regions of the genome.

Now Eichler and colleagues propose a novel mechanism for these duplication events, involving a unique, repeated DNA element (CAGGG) discovered in the pericentromeric region. Using fluorescent probes, they imaged the locations of the CAGGG repeats on human chromosomes and found multiple copies distributed exclusively near centromeres. Furthermore, the repeats they examined in detail were flanked with copies of disparately located genes. By comparing these copies with the original genes, the researchers estimated the genes duplicated only 10 to 25 million years ago, well after the evolutionary divergence of hominoids from Old World primates. Indeed, Old World primates, such as the baboon, possess far fewer CAGGG repeats than hominoids, such as the human, indicating the repeats themselves multiplied after the divergence. Altogether, these data suggest that CAGGG repeats mediate a recently active form of gene copying, which has pulled a disparate collection of genes to the central regions of hominoid chromosomes and thus created a potential breeding ground for new human genes.
Contact (author):

Evan Eichler
Center for Human Genetics
Case Western Reserve School of Medicine
Cleveland, Ohio 44106
Email: eee@po.cwru.edu
Fax: 216-368-3432

Cold Spring Harbor Laboratory

Related Genome Articles from Brightsurf:

Genome evolution goes digital
Dr. Alan Herbert from InsideOutBio describes ground-breaking research in a paper published online by Royal Society Open Science.

Breakthrough in genome visualization
Kadir Dede and Dr. Enno Ohlebusch at Ulm University in Germany have devised a method for constructing pan-genome subgraphs at different granularities without having to wait hours and days on end for the software to process the entire genome.

Sturgeon genome sequenced
Sturgeons lived on earth already 300 million years ago and yet their external appearance seems to have undergone very little change.

A sea monster's genome
The giant squid is an elusive giant, but its secrets are about to be revealed.

Deciphering the walnut genome
New research could provide a major boost to the state's growing $1.6 billion walnut industry by making it easier to breed walnut trees better equipped to combat the soil-borne pathogens that now plague many of California's 4,800 growers.

Illuminating the genome
Development of a new molecular visualisation method, RNA-guided endonuclease -- in situ labelling (RGEN-ISL) for the CRISPR/Cas9-mediated labelling of genomic sequences in nuclei and chromosomes.

A genome under influence
References form the basis of our comprehension of the world: they enable us to measure the height of our children or the efficiency of a drug.

How a virus destabilizes the genome
New insights into how Kaposi's sarcoma-associated herpesvirus (KSHV) induces genome instability and promotes cell proliferation could lead to the development of novel antiviral therapies for KSHV-associated cancers, according to a study published Sept.

Better genome editing
Reich Group researchers develop a more efficient and precise method of in-cell genome editing.

Unlocking the genome
A team led by Prof. Stein Aerts (VIB-KU Leuven) uncovers how access to relevant DNA regions is orchestrated in epithelial cells.

Read More: Genome News and Genome Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.