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Science,
1996]
In creatures from worms to people, it takes two sexes to reproduce, but it's often the female who gets stuck with the real work of childbearing. This division of labor is even mirrored in sperm and eggs. The unfertilized eggs of fruit flies, for example, already contain the molecular signals needed to direct one of the first events in embryonic growth, the creation of distinct body segments. The paternal contribution to early development, in contrast, seems paltry. Sperm carries nuclear material and organelles called centrosomes - organizing sites for cell division - that come into play later on, but no biochemical factors that guide early embryogenesis have been traced back to the father. In the January issue of the journal Development, however, molecular biologist Heidi Browning of the University of Colorado and developmental geneticist Susan Strome of Indiana University report that SPE-11, a protein produced only in the sperm of the nematode Caenorhabditis elegans, may play a crucial role during the first few minutes after the embryo is fertilized.
[
Science,
1996]
What 's the secret to long life? For the nematode Caenorhabditis elegans, it's slow, easy living, in which all life's events occur in a leisurely rhythm, according to work described on page 1010 of this issue. The new research, by Siegfried Hekimi and Bernard Lakowski of McGill University in Montreal, identifies four genes that, when mutated, can make these worms use energy more efficiently, feed and swim at a slower pace-and live many times their normal life-span. Some of the experimental nematodes lived for almost 2 months, far longer than their expected 9 days.
[
Science,
1996]
The one-cell animal embryo, or zygote, faces a daunting engineering task: implementing the architectural plans inscribed in its DNS for building a complex, multicelled body. So, like any sensible construction supervisor, the zygote swiftly divides the project into manageable chunks, assigning some of its progeny to build only gut, for example, and other to make only muscle or skin. Just how each early embryonic cell gets its orders is understood only for the fruit fly Drosophila melanogaster-an achievement that helped win 1995's Nobel Prize in medicine for three developmental biologists. Now, however, the communication lines governing embryonic development are emerging in another animal beloved of developmental researchers: the tiny worm known as Caenorhabditis elegans.