September 15, 2007 (Vol. 27, No. 16)
Strong Points: Useful research information
Weak Points: Registration required
Ask a molecular biologist why eukaryotic genomes are so much bigger than prokaryotic ones and they will usually say “repetitive elements.” Once described as junk DNA, repetitive elements in the genome are increasingly being examined for previously overlooked functions. Prime examples of these are the telomeres, those short repeating sequences found at the end of eukaryotic chromosomes. Serving as guardians of the chromosomal ends, their lengths at birth may be a factor in an individual’s maximum life span. Other common elements are evidence of the evolutionary past where sequences invaded and or were duplicated in cells. Tracking all of these elements is Repbase, a database of “prototypic sequences representing repetitive DNA from different eukaryotic species.” The available sequences are extensive (registration required), though segments of the site (Repeat Maps) are restricted to Arabidopsis thaliana and Caenorhabditis elegans. A useful research resource.