Interactions Between Limb Regeneration and Molting in Decapod Crustaceans

Molting and regeneration of lost appendages are tightly-coupled,hormonally-regulated processes in decapod crustaceans. Precociousmolts are induced by eyestalk ablation, which reduces circulatingmolt-inhibiting hormone (MIH) and results in an immediate risein hemolymph ecdysteroids. Precocious molts are also inducedby autotomy of 5–8 walking legs; adult land crabs (Gecarcinuslateralis) molt 6–8 wk after multiple leg autotomy (MLA).Autotomy of one or more of the 1° limb buds (LBs) that formafter MLA before a critical period interrupts proecdysis until2° LBs re-regenerate and grow to the approximate size ofthose lost. Based on these observations, Skinner proposed thatlimb buds produce two factors that control proecdysial events.Limb Autotomy Factor–Anecdysis (LAF_an), produced by 1°LBs when at least five legs are autotomized, stimulates anecdysialanimals to enter proecdysis. Limb Autotomy Factor–Proecdysis(LAF_pro), produced by 2° LBs in premolt animals when atleast one 1° LB is autotomized, inhibits proecdysial processes.Initial characterizations suggest that LAF_pro is a MIH-likepolypeptide that inhibits the synthesis and secretion of ecdysteroidby the Y-organs.