Inhibitory Effects of Echinochrome A, Isolated from Shell of the Sea Urchin Anthocidaris crassispina, on Antigen-Stimulated Degranulation in Rat Basophilic Leukemia RBL-2H3 Cells through Suppression of Lyn Activation

Echinochrome A (Echi-A) was isolated from the sea urchin Anthocidaris crassispina and its structure determined using 1D and 2D-NMR. In the present study, we examined the inhibitory effect of Echi-A on antigen-stimulated degranulation in rat basophilic leukemia RBL-2H3 cells, which were suppressed in a dose dependent manner. The antigens bind to the high affinity immunoglobulin E receptor, which is expressed on the surface of mast cells and basophils and activate intracellular signal transduction, resulting in the release of biologically active mediators such as histamine. In order to disclose the inhibitory mechanisms of degranulation by Echi-A, we examined the elevation in intracellular Ca2+ concentration ([Ca2+]i), production levels of intracellular reactive oxygen species (ROS) and early intracellular signaling events. Both elevation of [Ca2+]i and intracellular ROS production were markedly suppressed in cells treated with Echi-A. Echi-A also suppressed the activation of Lyn, Syk, and PLCγ1/2 in antigen-stimulated cells. These results indicated that inhibition of antigen-stimulated degranulation in RBL-2H3 cells by Echi-A is mainly due to the inactivation of Lyn/Syk/PLCγ signaling pathways. Our findings suggest that Echi-A could be a beneficial agent for alleviating the symptoms of type I allergy.

Premeiotic transformation of germ plasm-related structures during the sea urchin spermatogenesis

SummaryThe germ plasm-related structures (GPRS) and the transformation that occurs to them during the spermatogenesis of the sea urchin Anthocidaris crassispina were studied by electron microscopy and morphometry. The GPRS were observed in spermatogonia and spermatocytes, but not in spermatids and sperm, which suggests an important role for these structures during the onset of meiosis. It was proposed that the germinal granules are fragmented into the compact electron-dense nuage, and fragments of the latter penetrate into the periphery of the compact electron-lucent nuage. The process of nuage integration is completed with the formation of the combined nuage, which aggregates some mitochondria into clusters. Once formed, the mitochondrial clusters undergo dissemination and assume the appearance of the dispersed nuage with mitochondrial derivatives, which in turn develops into the scattered nuage. The scattered nuage, which presumably presents the composite mixture saturated with mitochondrial matrix, terminates the GPRS transformation.