Proteomic analysis of the crustacean molting gland (Y-organ) over the course of the molt cycle

Abstract

Molting in crustaceans is a highly complex physiological process involving regulation by two paired endocrine glands, the X-organ/sinus gland complex (XO/SG) and the Y-organ (YO). The XO/SG complex is responsible for making molt-inhibiting hormone, which negatively regulates synthesis of molting hormones, ecdysteroids, by the YO. In this study, changes in protein abundance in the YO were characterized over the course of a molt cycle induced by multiple leg autotomy in the blackback land crab, Gecarcinus lateralis. In all, 457 distinct protein spots were detected using two-dimensional gel electrophoresis, of which 230 (50%) changed significantly in abundance over the course of the molt cycle. Protein abundance differed most notably between intermolt and the three premolt stages, indicative of a biological ‘on-off’ switch. Changes in hemolymph proteins were correlated with stage-specific processes of sclerotization and melanization that facilitate cuticle hardening and support immune reactions. An abundance of cytoskeletal proteins were identified, which corresponded with glandular hypertrophy associated with synthesis and secretion of ecdysteroids. Many proteins involved in energetic pathways including glycolysis, the citric acid cycle, amino acid metabolism, and one‑carbon metabolism changed in abundance in response to increasing energy demands and the requirement for precursors of macromolecular synthesis. Several proteins involved in immune, proteostasis, and oxidative stress responses were correlated with the dynamic and demanding cellular changes associated with ecdysteroidogenesis. These changes in diverse physiological pathways represent the complexity involved with molecular regulation of the YO in decapod crustaceans.