Rasmussen encephalitis (RE) sera were screened for antibodies to human alpha7 nicotinic acetylcholine receptors (nAChRs) using electrophysiology, calcium imaging, and ligand binding assays. Sera from two of nine patients with RE blocked ACh-induced currents through alpha7 nAChRs and the ACh-induced rise in intracellular free calcium ([Ca2+]i) and inhibited (125)I-alpha-bungarotoxin binding in cells expressing alpha7 nAChRs. Thus, the alpha7 nAChR is a potential target for pathogenic antibodies in patients with RE.

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Characteristic features of cockroach embryos (Periplaneta americana) are determined for different stages in development. Morphological changes in giant interneurone 2 (GI 2) in the terminal abdominal ganglion during embryogenesis are described based on cobalt injections. A sequential proliferation of branches preceded by filopodial extension is observed between 45 and 80% embryogenesis, by which time the characteristic arborization of the first instar cell is established. The cholinergic agonist carbamylcholine was ionophoretically applied to the cell body and dendritic region of GI 2 at various stages in development, and the responses were recorded intracellularly. Chemosensitivity of GI 2 appears at 40 to 45% embryogenesis, to a similar degree in both cell body and dendrites. The sensitivity of these areas subsequently diverges, and after the 60 to 65% stage, the dendrites are approximately 1000 times more sensitive than the cell body. At 80 to 85% embryogenesis, there is a temporary peak in dendritic sensitivity, and cell body sensitivity increases during postembryonic development. The changes in sensitivity take place before synaptogenesis, and the decline in dendritic sensitivity after the 80% stage may be related to synaptic maturation.

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Photon correlation spectroscopy was used to study the motions of subcellular components of the giant internodal cells of the Characean alga Nitella flexilis both during endoplasmic streaming and during the electrically-induced, transitory arrest of streaming. With the direction of streaming oriented parallel to the scattering wave vector, the streaming of subcellular particles was detected as periodic oscillations in the intensity autocorrelation functions derived from scattered laser light. When streaming was oriented perpendicular to the scattering wave vector, monotonically decaying intensity autocorrelation functions were observed and during the cessation of streaming the decay rate measured at a delay time (τ) of 100 μs became faster, whereas at τ = 2 ms the decay rate became slower. Removal of the chloroplasts from the scattering region did not affect the decay rates recorded from cells in which streaming was oriented perpendicular to the scattering wave vector. The results are discussed in relation to mechanisms proposed for the generation of the motive force of endoplasmic streaming in Characean algae.