PLASTIC TIPS ON SHOELACES—that’s the analogy often used to describe telomeres, molecular caps that protect chromosomes from fraying during cell division, which play roles in aging and cancer. For research about these tiny structures, Jack W. Szostak of Massachusetts General Hospital, Elizabeth H. Blackburn of the University of California at San Francisco and Carol W. Greider of the Johns Hopkins University School of Medicine share this year’s Nobel Prize in Physiology or Medicine. Read Proto’s Summer 2008 feature on the work here.