Meeting Abstract

P1.30  Tuesday, Jan. 4  Effect of eyestalk ablation on expression of NO synthase and guanylyl cyclases in the Y-organ from green and red color morphs of Carcinus maenas LABERE, S.M.*; GUNDERSON, J.L.; MACLEA, K.S.; CHANG, E.S.; MYKLES, D.L.; Colorado State U.; UC Davis Bodega Marine Lab slabere@rams.colostate.edu

Adult European green crabs (Carcinus maenas) occur as two color morphs that differ in physiological properties. Green morphs molt more frequently than red morphs, which tend to be larger and put more energy into reproduction. Molting in decapod crustaceans is controlled by ecdysteroids produced in the Y-organ (YO), which is inhibited by the eyestalk neuropeptides crustacean hyperglycemic hormone (CHH) and molt-inhibiting hormone (MIH). CHH action is mediated by a membrane receptor guanylyl cyclase (GC-II), while MIH action may involve an NO synthase (NOS) and a soluble NO-sensitive GC (GC-I). Eyestalk ablation (ESA) removes the primary source of CHH and MIH, thus activating the YO in most decapods. In blackback land crab (Gecarcinus lateralis), ESA increases hemolymph ecdysteroid titers; animals enter premolt and proceed through to ecdysis. YO expression of NOS, GC-I, and GC-III (a soluble NO-insensitive GC) increases in ES-ablated G. lateralis, indicating that NO/cGMP signaling is responsive to a sudden drop in ES neuropeptides. Real-time PCR was used to quantify the effects of ESA on YO expression of NOS and the 3 GCs in the two color morphs of C. maenas. ESA causes only a transient increase in hemolymph ecdysteroid titers in both morphs. There was no effect on NOS, GC-I, GC-II, and GC-III mRNA levels up to 25 days post-ESA and mRNA levels were not correlated with ecdysteroid titers. In green morphs undergoing natural molts, there was no change in NOS and GC mRNA levels between intermolt, premolt, and postmolt animals. These results indicate that the YO in C. maenas, unlike the YO in G. lateralis, is refractory to ESA. Supported by an REU supplement to NSF grant IOS-0745224.