© 2001 by The Society for Integrative and Comparative Biology
Interactions Between Limb Regeneration and Molting in Decapod Crustaceans1
1 Department of Biology, Cell and Molecular Biology Program, and Program in Molecular, Cellular and Integrative Neurosciences, Colorado State University, Fort Collins, Colorado 80523
Molting and regeneration of lost appendages are tightly-coupled, hormonally-regulated processes in decapod crustaceans. Precocious molts are induced by eyestalk ablation, which reduces circulating molt-inhibiting hormone (MIH) and results in an immediate rise in hemolymph ecdysteroids. Precocious molts are also induced by autotomy of 5–8 walking legs; adult land crabs (Gecarcinus lateralis) molt 6–8 wk after multiple leg autotomy (MLA). Autotomy of one or more of the 1° limb buds (LBs) that form after MLA before a critical period interrupts proecdysis until 2° LBs re-regenerate and grow to the approximate size of those lost. Based on these observations, Skinner proposed that limb buds produce two factors that control proecdysial events. Limb Autotomy Factor–Anecdysis (LAFan), produced by 1° LBs when at least five legs are autotomized, stimulates anecdysial animals to enter proecdysis. Limb Autotomy Factor–Proecdysis (LAFpro), produced by 2° LBs in premolt animals when at least one 1° LB is autotomized, inhibits proecdysial processes. Initial characterizations suggest that LAFpro is a MIH-like polypeptide that inhibits the synthesis and secretion of ecdysteroid by the Y-organs.