Genetic variability for regional brain gangliosides in five strains of young mice

The quantitative and qualitative distributions of gangliosides were determined in the cerebrum, cerebellum, and brain stem of five inbred strains (C57BL/6J, DBA/2J, LG/J, C3H/HeJ, BALB/cJ) of mice at 21 days of age. Genetic differences were found among the strains for wet weight, absolute amount of gangliosides per region, and concentration of ganglioside (expressed on both a wet and a dry weight basis) in all three regions of the brain. The water content of the various brain regions showed the least amount of genetic variability. Coefficients of genetic determination were used to estimate the magnitude of genetic influence on these traits in each brain region. Significant differences were also found among the five strains for the distribution of certain gangliosides. The DBA strain, which is susceptible to audiogenic seizure at this age, had the highest level of the myelin-enriched ganglioside G_M1 in all brain regions. Most of the genetic variation that influences the content and distribution of gangliosides among neurologically normal mice can be considered polygenic. Several possible sources of this genetic variation that may contribute to the differences observed among the strains are discussed.This work was supported by USPHS Grant NS 11853 and by a grant from the Swebilius Fund. T. N. S. is the recipient of a USPHS postdoctoral fellowship (1F32NS0443).     

Chemical characterization of a new Japanese variant of carbonic anhydrase I,CA INagasaki 1 (76 Arg→Gln)

A new inherited variant of carbonic anhydrase I (CA I), designated CA I_{Nagasaki 1} (CA I_{NGS 1}), was discovered during a survey of hemolysates from 5852 individuals from the cities of Hiroshima and Nagasaki in Japan. Analysis of the amino acid composition of a tryptic peptide from the CA I_{NGS 1} variant indicated that a glutaminyl residue was substituted for an arginyl residue at position 76. Heat degradation studies showed that the CA I_{NGS 1} variant was less stable than normal CA I. The CO₂ hydrase and esterase activities of the normal and variant carbonic anhydrases I, as well as the relative amounts of the two enzymes in heterozygotes, were similar.This work was supported in part by Contract E(11-1)-1552 with the Energy Research and Development Administration, Washington, D.C. (to J. V. Neel), and by U.S. Public Health Service Grant GM-24681.     

Mosaic autosomal trisomy in cultures from spontaneous abortions.

In a consecutive series of 592 karyotyped spontaneous abortions, ten of 103 autosomal trisomies were mosaic, with a normal cell line also present. The frequency of mosaicism (10%) is much higher than that reported in Down syndrome, but similar to that reported in amniotic fluid cultures and in induced abortions. The most likely explanations for this discrepancy are (1) previous underestimation of mosaicism in live births or (2) mosaicism which is often restricted to extraembryonic fetal tissue.     

Effect of β-phenylethylamine on dopaminergic systems of the rat brain

The time course of changes in the dopamine concentration in dopaminergic neurons of the nigro-neostriatal and mesolimbic systems of the rat brain during 1 h after intraperitoneal injection of -phenylethylamine (100 mg/kg) was studied by quantitative fluorescence-histochemical analysis. The results showed that -phenylethylamine causes a marked fall in the dopamine level in neurons of dopaminergic systems of the brain. The dopamine level in the bodies of dopaminergic neurons changes more than in their axon terminals. The fall in the dopamine concentration in the dopaminergic systems of the brain during the first hour is irregular in character: in the terminals between 10 and 30 min and in the bodies between 30 and 45 min there is actually a temporary increase in the dopamine concentration. The rise in the dopamine concentration in the terminals coincides with a sharp fall in the dopamine level in the neuron bodies, and conversely, the fall in the dopamine concentration in the terminals after 30 min is accompanied by some increase in the dopamine concentration in the neuron bodies. The results suggest that the increase in motor activity described in the literature in animals after injection of -phenylethylamine is connected with its action on catecholaminergic, especially dopaminergic, brain systems.Institute of Biophysics, Academy of Sciences of the USSR, Pushchino-on-Oka. Translated from Neirofiziologiya, Vol. 11, No. 6, pp. 578–584, November–December, 1979.     

Possible use of an analgesic (fentanyl) during electrophysiological investigations of the cerebellar cortex

The effect of the central analgesic fentanyl on evoked potentials and responses of single Purkinje cells in the cerebellar cortex to stimulation of the sensomotor cortex and of somatic nerves was investigated in unanesthetized cats. Injection of fentanyl in an analgesic dose (10–30 µg/kg, intravenously) had no appreciable effect on evoked potentials and led only to very slight changes in spontaneous activity and responses of Purkinje cells. As a rule fentanyl, in a dose of 30 µg/kg, depressed, but in a dose of 10 µg/kg, facilitated responses and spontaneous activity of Purkinje cells. This effect of fentanyl is negligible compared with the action of barbiturate anesthetics on responses of cerebellar cortical neurons. Consequently, fentanyl can be used for analgesia during electrophysiological investigations of the cerebellar cortex in unanesthetized cats.Institute for Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol. 11, No. 6, pp. 585–592, November–December, 1979.     

Types of activity of skeletal muscle motor units during cold tremor in cats

Discharges of 184 motor units of the sartorius muscle functioning during cold tremor were investigated in acute experiments on anesthetized cats. Units whose discharges correlated with respiration cycles and units functionally independent of the rhythm of respiration were discovered. Discharges of both types of motor units possessed the same mean frequency (4–12 spikes/sec) and the same low variability of interspike intervals. Additional temperature stimulation of the vascular temperature receptors and changes in the frequency and depth of the respiratory excursions during cold tremor evoked identical responses in the two types of units. It is concluded that both types of motor units have similar thresholds and are of the slow, phasic type.O. V. Kuusinen State University, Petrozavodsk. Translated from Neirofiziologiya, Vol. 11, No. 4, pp. 355–361, July–August, 1979.     

Possibility of analytical application of the partition in aqueous biphasic polymeric systems technique

The partition behaviour of a number of ionic and nonionic surface-active substances in the dextran-polyethylene glycol system was examined. The strictly linear dependence of the logarithm of the partition coefficient on the alkyl chain length for a homologous series of nonionic surfactants provides a measure of the difference in the relative hydrophobicity between the two phases of the system, in terms of the free energy of transfer of a CH₂ group from the bottom phase to the top phase of the system. This difference is found to be altered in the presence of NaCl or KCl depending on the salt concentration. It is concluded that the influence of the salt composition of the system on the distributed solutes' behaviour may be due to the effect of the ions on the hydrophobicity difference between the phases.The partition of ionic amphiphiles is found to be dependent on the relative hydrophobicity of the compounds as well as on their charge. It is shown that at salt concentrations up to about 0.1 M NaCl the charged solute partition is determined by its charge as well as its relative hydrophobicity, in the presence of 0.1–0.2 M NaCl the substance distribution is highly dependent on its charge and slightly on its lipophility. At the salt concentrations above 0.2 M the solute partition is determined just by its hydrophobic character and seems to be totally independent of its charge. It is concluded that the partition technique can be used for analytical purposes. The method seems to be unique in providing quantitative information on the amphiphilic surface properties of the solutes being partitioned.     

Evidence for the existence of a ubiquinone protein and its radical in the cytochromes b and c1 region in the mitochondrial electron transport chain.

A highly purified cytochrome $\text{b}\text{?}\text{c}{}_1$ complex which is free of QP_s (see BBRC $\text{78}\text{, 259 and}\text{79}$, 939) yields 20–30% of semiubiquinone (based on the total Q content in the system) in the presence of catalytic amounts of QP_s and succinate dehydrogenase (at or lower than 2 × 10^{?9 M}. The radical shows typical $\text{g}\text{= 2.00}$ signals with line widths of 8 and 9 gauss, respectively, at about 22°C and 77°K. The appearance of the radicals approximately parallels that of $\text{b}$ reduction but not its disappearance. However, addition of theonytrifluoroacetone or antimycin A immediately abolishes both radical formation and $\text{b}$ reduction. These and other observations indicate that the true carrier property of Q is through its binding with proper proteins but not the protei-free form.     

Different families of double-stranded conformations of DNA as revealed by computer calculations

An algorithm has been developed that permits one to find all possible conformations of the sugar-phosphate backbone for any given disposition of DNA base pairs. For each of the conformations thus obtained, the energy of the helix was calculated by the method of atom-atom potentials. Several isolated regions in the space of the bases′ parameters (Arnott's parameters) have been found for energetically favorable helical structures. Two parameters, the distance of a base pair from the helix axis, D, and the windling angle, τ, allow one to subdivide possible conformations into the families of closely related forms. Two regions (ravines) on the (D, τ) map correspond to the know A and B families. In the B family a continuous transition has been obtained in which the double helix undergoes increasing winding, while the base pairs are moving toward the major (nonglycosidic) groove. Interrelationships between the variables, characterizing the spatial structure of the double helix, D, τ, TL and χ, when going along the bottom of the B ravine, were also obtained. Besides the Known A and B families, several new ones were found to be energetically possible. Among these the strongly underwound helices with the negative D values, as well as the forms with the C4-C5 angle in a trans position, should be mentioned. Biological roles of the different double-stranded conformations, in particular, in protein-nuclei acid interaction are discussed.