The role of rat neuronal calcium sensor‐1 (NCS‐1), a Ca2+‐binding protein, in synapse formation and transmitter release was examined in mouse neuroblastoma × rat glioma hybrid NG108‐15 cells in culture. Wild‐type NG108‐15 cells expressed rodent NCS‐1. Endogenous NCS‐1 was partially co‐localized with the synaptic protein SNAP‐25 at the plasma membrane in both cell bodies and processes, but not with the Golgi marker β‐COP, an individual coat subunit of the coatomer complex present on Golgi‐derived vesicles. In NG108‐15 cells co‐cultured with rat myotubes, partial co‐localization of SNAP‐25 and NCS‐1 was observed at the plasma membrane of neurites and growth cones, some of which had synaptic contacts to muscle cells. Transient co‐transfection of the rat NCS‐1 cDNA and green fluorescent protein (GFP) resulted in NCS‐1 overexpression in about 30 % of the cells as determined by fluorescence microscopy. The rate of functional synapse formation with co‐cultured rat myotubes increased 2‐fold as determined by the presence of miniature endplate potentials (MEPPs) in NCS‐1‐overexpressing NG108‐15 cells compared to non‐ and mock‐transfected cells. The number of neurites per cell, branches per neurite and length of neurites was slightly less in cells that were either transiently transfected (GFP‐NCS‐1‐fluorescence positive) or stably transformed with NCS‐1 compared to GFP‐NCS‐1‐negative, non‐transfected or mock‐transfected NG108‐15 cells. The number of action potentials that elicited endplate potentials increased in NG108‐15 cells stably transformed with rat NCS‐1. The mean number of quanta per impulse (m) increased 5‐fold. These results show that NCS‐1 functions to facilitate synapse formation, probably because of the increased quantal content of evoked acetylcholine release.

No abstract

Cyclic ADP-ribose (cADP-ribose) is a putative second messenger or modulator. However, the role of cADP-ribose in the downstream signals of the metabotropic glutamate receptors (mGluRs) is unclear. Here, we show that glutamate stimulates ADP-ribosyl cyclase activity in rat or mouse crude membranes of retina via group III mGluRs or in superior cervical ganglion via group I mGluRs. The retina of mGluR6-deficient mice showed no increase in the ADP-ribosyl cyclase level in response to glutamate. GTP enhanced the initial rate of basal and glutamate-stimulated cyclase activity. GTP-c-S also stimulated basal activity. To determine whether the coupling mode of mGluRs to ADP-ribosyl cyclase is a feature common to individual cloned mGluRs, we expressed each mGluR subtype in NG108-15 neuroblastoma · glioma hybrid cells. The glutamate-induced stimulation of the cyclase occurs preferentially in NG108-15 cells over-expressing mGluRs1, 3, 5, and 6. Cells expressing mGluR2 or mGluRs4 and 7 exhibit inhibition or no coupling, respectively. Glutamate-induced activation or inhibition of the cyclase activity was eliminated after pre-treatment with cholera or pertussis toxin, respectively. Thus, the subtype-specific coupling of mGluRs to ADP-ribosyl cyclase via G proteins suggests that some glutamate-evoked neuronal functions are mediated by cADP-ribose.

The deformation and internal forces of beams on tensionless foundation materials were studied. The reaction force between the beam the foundation was fitted as a cubic polynomial about the deflection based on the experimental data, and the corresponding control equations of beams were derived by the finite difference method. Results show there are significant differences between tensionless and tensional foundation materials for the deformation and internal forces of beams. The difference is varying with the length of beams. Both the relative errors of the maximum of deflection and slope can be over 20%, and the relative errors of the maximum of shearing force and bending moment are smaller comparatively, so the tensionless effect of foundation materials can not be neglected for the stiffness verification and the strength verification of beams.

The deformation and internal forces of beams on non-linear elastic foundation materials were studied. The reaction force between the beam and the foundation was fitted as a cubic polynomial about the deflection of beams by experimental data, and the corresponding control equations were derived by the finite difference method. MATLAB program with the Newton iteration method was used to obtain numerical results. Results of the numerical example show the deformation and internal force of short non-linear and linear elastic Winkler beams are same, but the relative errors can reach 10%-20% for moderate and long beams, so the non-linear foundation effect on the settlement of beams should be considered in engineering; the relative errors of the deformation and internal force between moderate non-linear and linear elastic Winkler beams vary with the length of beams, but keep invariant for long beams.