Modulatory effects of some amino acids and neuropeptides on luminescence in the brittlestar Amphipholis squamata

Amphipholis squamata is a polychromatic luminescent ophiuroid, The effects of amino acids (gamma-aminobutyric acid, GABA, taurine, glycine and glutama te), N-methyl-D-aspartate (NMDA) and the invertebrate neuropeptides Antho-R Famide, FMRFamide and SALMFamides S1 and S2 were tested on acetylcholine-in duced luminescence from isolated arms of clear and black specimens of Amphi pholis squamata. The results showed that GABA, glycine and Antho-RFamide in hibited ACh-induced luminescence of clear specimens and had no significant effect on black specimens. Glutamic acid had no significant effect on ACh-i nduced luminescence, but triggered luminescence in the absence of ACh in bo th types of specimen. Taurine, NMDA and FMRFamide showed no significant eff ects on either clear or black specimens. S1 potentiated ACh-induced lumines cence of clear and black specimens, while S2 had no clear modulatory effect on luminescence. These results suggest that, in addition to the previously described cholinergic system in Amphipholis squamata, there is also a modu latory component to luminescence control. Moreover, we observed a differenc e in modulation of luminescence between clear and black specimens.