Molecular mechanisms regulating molting in a crustacean.
Crustacean growth and development is characterized by periodic shedding (ecdysis) and replacement of the rigid exoskeleton. Secretions of the X-organ sinus gland complex control the cellular events that lead to growth and molting. Western blot and ELISA results showed a progressive increase in growth arrest-specific protein (Gas7) from early postmolt stage to a maximum at late postmolt stage. Phosphorylation of ERK2, a downstream signaling protein, was also identified in the subsequent stages. ERK2 phosphorylation resulted in the expression of molt-inhibiting hormone (MIH). Specific ERK inhibitors (PD98059 and UO126) exhibited the ability to reduce the molting duration of Fenneropenaeus indicus from 12-14 days to 7-8 days, suggesting that the ERK1/2 signaling pathway is responsible for the expression of MIH, which controls the molt cycle. We have identified the stage-specific expression of Gas7 (approximately 48 kDa) in the X-organ sinus gland complex of eyestalk which is involved in the downstream signaling of the ERK1/2 pathway regulating the expression of MIH during the molt cycle of the white shrimp, F. indicus. These are the first data showing an association between the Gas7 signal-transduction process and regulation of the molt cycle and provides an alternative molecular intervention mechanism to the traditional eyestalk ablation in crustaceans.
Devaraj
Halagowder
H
Unit of Biochemistry, Department of Zoology, University of Madras, Tamil Nadu, India. hdrajum@yahoo.com
Natarajan
Ayithan
A
D000818:Animals; D002070:Butadienes / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D005419:Flavonoids / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D018978:Molting / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009570:Nitriles / Q000378:metabolism; D033561:Penaeidae / Q000033:anatomy & histology / Q000502:physiology*; D010766:Phosphorylation; D017956:Photoreceptor Cells, Invertebrate / Q000033:anatomy & histology / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*
D002070:Butadienes; D004791:Enzyme Inhibitors; D005419:Flavonoids; C485435:Gas7 protein, mouse; D009419:Nerve Tissue Proteins; D009570:Nitriles; C113580:U 0126; D019950:Mitogen-Activated Protein Kinase 1; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one