BATON ROUGE, Monday, May 2, 2005 Louisiana State University scientists in the Department of Biological Sciences have unraveled the details of a 25-million-year-old evolutionary process in the human genome. Specific DNA sequences that appear to have persisted in a latent state for long periods of time may not be simply lying dormant. Instead, the researchers say that these elements have played a crucial role in human evolution by surreptitiously spawning hyperactive progeny copies, giving rise to the most abundant family of DNA elements in the human genome: Alu elements. The study, which was led by LSU scientist Dr. Mark A. Batzer, provides the first strong mechanistic evidence for the evolution of Alu elements to date. It appears in the May issue of the journal Genome Research.
Alu elements are short, 300-nucleotide-long DNA sequences capable of copying themselves, mobilizing through an RNA intermediate, and inserting into another location in the genome. Over evolutionary time, this retrotransposition activity has led to the generation of over one million copies of Alu elements in the human genome, making them the most abundant type of sequence present. Because Alu elements are so abundant, comprising approximately 10% of the total human genome, they have been thoroughly characterized in terms of their origin and sequence composition. What has remained elusive to scientists, however, are the actual mechanisms by which these elements persist and propagate over time to influence human evolution.
In an attempt to understand these mechanisms, Dr. Batzer and his colleagues examined a subfamily of Alu elements in the human genome known as the AluYb lineage, and compared these elements to those in the genomes of other primate species, including chimpanzees, bonobos, gorillas, orangutans, gibbons and siamangs. The AluYb subfamily accounts for approximately 40% of all human-specific Alu elements and is currently one of the most active Alu lineages Page: 1 2 3 Related biology news :1
Contact: Maria A. Smit
Cold Spring Harbor Laboratory
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