The Grundproblem in the Theory of Art

Ivanov's article presents background information and a methodological approach to Sergei Eisenstein's two-volume work on the method of art. Eisenstein himself considered film to be an art in which the basic problem of art is clearly visible. He argued that successfully combining regressive and progressive elements in art can solve the problem of form and content. The article demonstrates the personal cooperation that took place between Eisenstein, Marr, Luria, and Vygotsky at the beginning of 1930's.     

Pr-SNTX,a short-chain three-finger toxin from Papuan pigmy mulga snake,is an antagonist of muscle-type nicotinic acetylcholine receptor (α2βδε)

Three-finger toxins (3FTxs) are one of the major components in snake venoms. In this study, we isolated a cDNA encoding a short-chain 3FTx, Pr-SNTX, from Pseudechis rossignolii. The amino acid sequence of Pr-SNTX is nearly identical to that of its ortholog in Pseudechis australis. Pr-SNTX protein inhibited muscle-type (α₂βδε), but not neuronal α7 nicotinic acetylcholine receptor (nAChR) activity.     

Pattern of tonic activity in different groups of rabbit superior cervical ganglion neurons

Tonic activity in rabbit superior cervical ganglion neurons was investigated using intracellular recording techniques as well as changes produced when the animal breathed a gaseous mix with a raised CO₂ level. The test neurons were divided into three groups depending on the pattern of their tonic activity and reflex change. Action potentials were produced by the activity of dominant and accessory preganglionic inputs in the firing pattern of all neuronal groups, implying the existence of other types of inputs into the neurons innervating different organs. Having analyzed changes in action potential rate and EPSP in the tonic activity of neurons from different groups, it was presumed that preganglionic fibers with a similar activity pattern converge on the majority of neurons in each group.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 5, pp. 665–672, September–October, 1987.     

Calcium permeability of synaptosomes induced by alpha-latrotoxin

The paper deals with characteristics of ionic alpha-latrotoxin-induced permeability of rat brain synaptosomes. It has been shown that the addition of alpha-latrotoxin to synaptosomes in the Ca2+-containing media resulted in an extensive and rapid uptake of 45Ca2+ in synaptosomes. alpha -Latrotoxin was not able to enhance the 22Na+ and 86Rb+ uptake or efflux in the Ca2+-containing and Ca2+- and Mg2+-free media. The dye di-O-C3 was used to monitor the membrane potential changes as a consequence of alpha-latrotoxin treatment of synaptosomes. It has been found that alpha-latrotoxin increased synaptosomal fluorescence in the Ca2+-containing media, but failed to induce any increase of fluorescence in Ca2+- and Mg2+-free media. It has been also shown that the calcium uptake induced by alpha-latrotoxin depends on free calcium concentration in synaptosomes. Toxin-induced calcium flows are shown to be of the vector character.     

The lack of ability of carcinogens and non-carcinogenic analogs to induce sex-linked recessive lethals in Drosophila melanogaster

The mutagenic activity of two known carcinogens (benzo(a) pyrene and 2-acetylaminofluorene) and that of two structurally closely related but not carcinogenic compounds (pyrene and 4-acetylaminofluorene) was examined by the Muller-5 test for sex-linked recessive lethals (SRL). The chemicals tested were applied to the food medium for larvae of Canton-S Drosophila melanogaster. No statistically significant differences in frequencies of induced SRL were found either within pairs of chemicals or between treated and untreated animals.     

Mitogenic action of substance P on the epithelial cells of the tongue

Substance P (10 and 100 ng/ml) stimulates the proliferation of basal cells from rat's tongue epithelium in primary cultures with 2.5% fetal calf serum. In serum-free medium substance P have no effect on the epithelial cell growth. This neuropeptide secreted by afferent nerve fibers of the tongue epithelium is suggested to have a neurotrophic influence on epithelial cells controlling their proliferation.     

Determination of plasmid copy number by the "boiling" method

A fast and reliable approach for determination of plasmid copy number in Escherichia coli is proposed, based on the "boiling" method (5) for separation of plasmid and chromosomal DNA. The method includes in vivo uniform labeling of total bacterial DNA, separation of DNA into plasmid and chromosomal DNA fractions, and quantitation of DNA in the two fractions by radioactivity measurement. No isolation and purification of native DNA are necessary.     

Spectral features of amines of 2-phenylbenzazoles upon interaction with DNA

Absorption and fluorescent spectra of various synthetic aminophenyl derivatives of benzoxazole, benzothiazole and benzimidazole have been studied to estimate the efficiency of their binding with DNA. The significance of different functional groups of the fluorochromes for their interaction with DNA was determined, and main demands are formulated to the compounds to be used as potential fluorescent probes for DNA studies.     

Amplification of bacterial plasmids without blocking protein biosynthesis

The effect of amino acids (presence or absence from the growth media) and metal ions on the replication of Escherichia coli plasmids in rel A+ strains was studied. It was found that: (i) The absence of one amino acid from the growth media had no effect on the plasmid copy number in prototrophic E. coli strains: (ii) The presence of only one amino acid in artificial media free of amino acids had a negligible effect on the plasmid copy number for the amino acids Ala, Arg, Glu, His, Leu, Phe, Thr, Trp, and Tyr: (iii) The combination of Met and Thr caused a rise in pBR322 plasmid copy number up to 90-100 plasmid copies per cell: (iv) The Fe3+ concentration had an amplification effect on E. coli plasmids. The pBR322 plasmid copy number for media free of amino acids and supplemented with 0.2-0.4 mM FeCl3 was 60-80 plasmid copies per cell: (v) The combination of Fe3+ with certain amino acids (Ala, Arg, Glu, Leu, Thr, and Trp) leads to a dramatic increase in the plasmid copy number reaching 180-270 plasmid copies per cell for the plasmid pBR322 and 20-24 for the plasmid pR100.