. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ^T-^ 20—hydroxyecdysone Environmental Inputs Eyestalk Ganglia MIH \ R cholesterol ATP AC cAMP. Ca 5' AMP ecdysone ecdysone Y—organ FIGURE 5. Model of neuroendocrine regulatory interactions of the X-organ-sinus gland-Y-organ system. Environmental inputs including stress activate serotonergic eyestalk neurons which stimulate MIH-containing neurosecretory cells of the X-organ (XO)-sinus gland (SG) complex to release MIH. MIH in hemolymph binds to putative Y-organ cell surface receptors (R) resulting in activation of adenylate c
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ^T-^ 20—hydroxyecdysone Environmental Inputs Eyestalk Ganglia MIH \ R cholesterol ATP AC cAMP. Ca 5' AMP ecdysone ecdysone Y—organ FIGURE 5. Model of neuroendocrine regulatory interactions of the X-organ-sinus gland-Y-organ system. Environmental inputs including stress activate serotonergic eyestalk neurons which stimulate MIH-containing neurosecretory cells of the X-organ (XO)-sinus gland (SG) complex to release MIH. MIH in hemolymph binds to putative Y-organ cell surface receptors (R) resulting in activation of adenylate cyclase (AC) and generation of cAMP. cAMP suppresses production of ecdysone from cholesterol, an effect antagonized by calcium (Ca) which activates a calcium-calmodulin-sensitive cAMP-phosphodiesterase. Thus with continued release of MIH, ecdysone liters remain low and the intermolt state is maintained. A reduction of MIH release (due to a transient increase in hemolymph ecdysteroid levels or to reduced peripheral neural input) releases Y-organs from inhibition (decreased Y-organ cAMP levels) and ecdysone production is increased. Ecdysone is converted in peripheral tissues to 20-hydroxyecdysone. The latter eventually exerts feedback inhibition on release of MIH from XOSG cells, permitting the large rise in hemolymph ecdysteroid tilers prior to the molt. Y-organ activity subsequently declines (cause unknown), ecdysteroid liters fall, and MIH is again released reinslaling the intermolt slage. See text for further discussion and delails. 271. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 189
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