Similarity of the C-elegans developmental timing protein LIN-42 to circadian rhythm proteins

The Caenorhabditis elegans heterochronic genes control the relative timing and sequence of many events during postembryonic development, including the terminal differentiation of the Lateral hypodermis, which occurs during th e final (fourth) molt. Inactivation of the heterochronic gene lin-42 causes hypodermal terminal differentiation to occur precociously, during the thir d molt. LIN-42 most closely resembles the Period family of proteins from Dr osophila and other organisms, proteins that function in another type of bio logical timing mechanism: the timing of circadian rhythms. Per mRNA Levels oscillate with an approximately 24-hour periodicity. lin-42 mRNA Levels als o oscillate, but with a faster rhythm; the oscillation occurs relative to t he approximately 6-hour molting cycles of postembryonic development.