The cellular powerhouses known as mitochondria, which are the focus of this week's special issue (see p. 1475), offer clues to everything from evolution to diseases such as inherited deafness and muscular dystrophy. A number of Web sites offer information on these dynamic organelles.
A good starting point is MITOMAP, a database of genes and related references set up to help researchers make use of the 16,569-base human mitochondrial genome, sequenced in 1981—a mere snippet compared to the 3-billion-base nuclear genome. Offering a glimpse of how the Human Genome Project might one day be put to use, the site is also an archive for DNA variations, or polymorphisms, that sometimes underlie disease. For example, researchers studying a patient with a mutation in her mitochondrial DNA can type in the sequence and get back a list of references (linked to Medline) that might tell them which diseases the mutation is associated with, and whether it's common in a particular ethnic group. The site now holds more than 2200 references, says co-curator Marie Lott of Emory University in Atlanta.
MITOMAP also gives a rundown of other major mitochondria sites, including a tutorial, sites on mitochondrial diseases, and a protein database. And it lists the 95 complete mitochondrial genomes for various organisms in GenBank.