Modification of sodium inactivation in myelinated nerve by Anemonia toxin II and iodate. Analysis of current fluctuations and current relaxations

(1) Na+ currents and Na+ current fluctuations were measured in single myelinated nerve fibres of Rana esculenta under voltage-clamp conditions. The process of Na+ inactivation was modified by external treatment with 7 microM Anemonia Toxin II or by internal application of 20 or 40 mM IO3(-). (2) At depolarization of 24 and 32 mV the spectral density of Na+ current fluctuations could be described as the sum of two contributions, Sh(f) and Sm(f), representing the spectrum from fluctuations of the inactivation (h) and activation (m) gates, respectively. At higher depolarizations of 40 and 48 mV the low frequency (h) fluctuations could be better fitted by the sum, Sh1(f)+Sh2(f), of two separate Lorentzian functions. (3) The Na+ current and the variance of Na+ current fluctuations between 150 and 450 ms after depolarization are increased by one order of magnitude after application of Anemonia Toxin II or IO3(-). (4) The kinetics of Na+ current inactivation were described as A1 x exp(-t/tau h1) + A2 x exp(-t/tau h2) + B. The constant, tau h1, of fast Na+ inactivation was the same in normal and modified nerve fibres. The slow inactivation time constant, tau h2, increased with increasing depolarizations in modified fibres but decreased under control conditions. In all cases tau h2 showed a similar voltage dependence as the time constant found by fitting the low frequency fluctuations of Na+ current with one Lorentzian function, Sh(f). (5) It is concluded that Anemonia Toxin II and IO3(-) modify a fraction of Na+ channels in an all-or-none manner. A lower limit of the number of modified Na+ channels is estimated from the Na+ current and the variance Na+ current fluctuations. 7 microM external Anemonia Toxin II modifies more than 17% and 20 or 40 mM internal IO3(-) more than 8% of all Na+ channels. The inactivation gates in modified channels experience an electric field different from that in normal fibres.     

Spectrum of chloroperoxidase compound I

When compound I of chloroperoxidase is formed from the native enzyme the absorption peak in the Soret region diminishes in intensity, and shifts to a maximum absorbance at 367 nm. This unusual Soret spectrum decreases in intensity in a linear fashion as the wavelength increases. The first visible spectrum of chloroperoxidase compound I is reported which has a peak at 689 nm as its most prominent feature.     

Chemical and biological consequences of β-decay

Summary Radioactive decay in a labelled molecule leads to specific chemical and biological consequences which are due to local transmutation effects such as recoil, electronic excitation, build-up of charge states and change of chemical identity, as well as to internal radiolytic effects. In the present paper these effects are reviewed emphasizing the relation of the chemical alterations on a molecular level to the biological manifestation. Potential importance of this type of research for biomedical applications is pointed out. In part 1 we review the underlying physical and chemical principles and consequences of -decay of³H,¹⁴C,³²P,³³P,³⁵S and¹²⁵I for gaseous and simple condensed organic systems. Part 2 which will appear in the next issue will include the discussion of biological effects associated with -decay.     

Organization of the stomatogastric ganglion of the spiny lobster

Summary Three direct synaptic connections occur between neurons in the gastric and pyloric systems of the stomatogastric ganglion ofPanulirus interruptus. Two synapses are inhibitory, and one is electrical. This electrical synapse is both excitatory and inhibitory at different times. These synapses, and others within each system, let the two systems interact under some conditions. The synapses also form multisynaptic pathways which modulate the firing of many neurons in both systems. The consequences of these multisynaptic pathways are described and discussed.I thank Allen I. Selverston, Karen Sigvardt, Eve Marder, David Russell and Mary Chamberlin for criticizing a draft of this paper, Forrest Gompf and Doug Tissdale for technical support, and Nina Pollack and Betty Jorgensen for laboratory assistance. The research was supported by USPHS grant NS-12295 to BM and USPHS grant NS-09322 to Alien I. Selverston. BM was a USPHS NIH Postdoctoral Fellow in A.I. Selverston's laboratory during part of this research and is now a Research Fellow of the Alfred P. Sloan Foundation.     

Cholelithiasis in a male rhesus monkey (Macaca mulatta) fed a cholesterol-containing diet.

In this report we describe the development of cholelithiasis in a male rhesus monkey fed a cholesterol-containing diet for 24 months. This represents the only case of cholelithiasis in this species of nonhuman primate that we have observed out of a population of over 500 rhesus monkeys fed similar cholesterol-containing diets. Associated with the appearance of gallstones was the production of bile saturated with cholesterol, and the excretion of bile with an abnormal bile acid composition.     

Mutation in continuous cultures of Schizosaccharomyces Pombe. I. Dependence of the kinetics of mutation accumulation upon the growth-limiting nutrilite

The rate of spontaneous mutation to resistance to the 12,13-epoxytrichothecene trichodermin has been determined under different growth limiting conditions in continuous cultures of the microbial eukaryote Schizosaccharomyces pombe. In agreement with data obtained in bacterial systems by previous workers the kinetics observed for the accumulation of mutations is found to be dependent upon the nutrient used to limit the growth of the population. Under conditions of glucose-limitation mutation accumulation is directly proportional to the rate of cell division, while under histidine-limitation it is proportional to chronological time. Various possible explanations for these observations are discussed.     

Seminars in Virology: A Biological Perspective of Slow Virus Infection and Chronic Disease

Sequential events characterize the interaction of viruses with parenchymal cells, and acute lytic infections of tissues and organs have broad biological attributes. A knowledge of these permits a keener understanding of persistent, intermittent herpesvirus infections and persistent, continuous respiratory virus infections. In addition to unique biochemical mechanisms which may permit the latter chronic infections to evolve, the roles of defective and mutant strains of virus, viral interference, and the genetic, developmental and immunological expressions of the host are of considerable and provocative importance.The traditional view of viral infections embraces a broad spectrum of acute pathological and inflammatory events. The relationship of measles virus to subacute sclerosing panencephalitis, the elucidation of the latency of herpes simplex virus, and the slow unmasking of the pathogenesis of multiple sclerosis have illustrated the subtle elements of persistent viral infections of the human being. These chronic neurological diseases have provided the opportunity and stimulus for sharp dissection of the biological and biochemical processes which embellish the logical link of viral infections to other forms of chronic human illness.     

The isolation of Saumarez Reef virus, a new flavivirus, from bird ticks Ornithodoros capensis and Ixodes eudyptidis in Australia.

Strains of a new flavivirus, for which the name Saumarez Reef Virus is proposed, were isolated from seabird ticks collected from four localities. Two strains were isolated from ticks of the species Ornithodoros capensis Neumann 1901 collected from the nests of Sooty Terns, Sterna fuscata Linnaeus 1766 on coral cays off the east coast of Queensland, Australia. The other three strains were isolated from ticks of the species Ixodes eudyptidis Maskell 1885 taken from two dead Silver Gulls Larus novaehollandiae Stephens 1826 in northern Tasmania. The new virus was compared serologically with 50 other flaviviruses at the Yale Arbovirus Research Unit and was found to be most closely related to Tyuleniy virus.