Death to Sperm Mitochondria; March 1999; Scientific American Magazine; by Hopkin; 1 Page(s)

So you got your crooked schnozz from your mother and your mud-brown eyes from Dad. That's the luck of the draw. But if you're a mammal, you got all your mitochondria from Mom. These little organelles-which provide the energy for your metabolic needs-derive from the maternal side, so they have proved indispensable in tracing human lineages. Sperm, like oocytes, also have mitochondria, but the organelles vanish from the embryo shortly after fertilization. Of course, just how they are made to disappear has always been a mystery.

Now researchers led by Peter Sutovsky and Gerald Schatten of the Oregon Regional Primate Research Center in Beaverton, Ore., think they have figured out the signal that dooms paternal mitochondria to destruction. Their findings-presented at the American Society for Cell Biology meeting last December-suggest that mitochondria in developing sperm become tagged with a protein that is known to route damaged proteins to the cellular trash bin. After fertilization, the egg may recognize the tag and dispose of the foreign organelles.