Contribution of a humoral factor to postsynaptic sensitization in heterosynaptic facilitation

It was shown that heterosynaptic facilitation develops in the cerebral ganglia giant neurons of the freshwater gastropod molluskPlanorbis corn eus due to diffuse neurohumoral influences on pre- and postsynaptic structures and not local synaptic action on presynaptic mechanisms. It was also found that n-cholinergic synaptic mechanisms come under this facilitatory influence. Serotonin is the source of facilitation in neurons of bothPlanorbis corneus cerebral ganglion and those of the aplysia abdominal ganglion. Seeing that: a) conditioning stimuli facilitate the effects produced by iontophoretic acetylcholine application, as well as n-cholinergic synaptic transmission and b) the amplitude of EPSP and acetylcholine potential increase 4–6 times during facilitation when the input impedance of the post-synaptic membrane is increased by just 20%, it was deduced that the postsynaptic membrane of the giant neuron makes a significant contribution to heterosynaptic facilitation of the sensitization of n-cholinergic receptors. The part played by n-cholinergic receptors of the postsynaptic membrane in heterosynaptic facilitation and conditioned reflex habituation is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 2, pp. 250–259, March–April, 1986.     

Initiation of anion-selective ionic channels in bilayer membranes at lipid phase transitions

A study was carried out to electric parameters of single ionic channels initiated at phase transition of bromidmetilate 1,2-distearoyl-rac-glycero-3-(O-beta-dimethylaminoethyl)-methylphosphonate, whose molecules under conditions given below are possibly charged. It has been shown that changes of transmembrane current appear at phase transition temperature. Comparison between ionic selectivity of channels initiated at Tph.t in the membranes of DSL and its phosphate analog suggests that the channel walls initiated at phospholipid phase transitions are covered with polar groups of molecules.     

The morphological and functional characteristics of the human aortic endothelium. I. 2 variants of the organization of the endothelial monolayer in atherosclerosis]

The en face organization of human aortic endothelium in zones of low (LP) and high (HP) probability of sudanophilia was examined in preparation impregnated with silver nitrate. It is found that the heterogeneity of endothelial cells (EC) by area is "random" or "clusterized". In the latter case the major part of small and medium-sized EC (less than 800 microns 2) is associated in distinct groups ("clusters") and form foci with high monolayer density. The luminal surface outside the clusters was formed by preferentially large and giant EC. Clusterized endothelium was found with statistically significant higher frequency in HP zones of both "normal" and "atherosclerotic" vessels. The maximum clusterization of EC was revealed on the shoulder region and on the periphery of atherosclerotic plaques which was speculated to be a growth zone of the lesion. It is suggested that the appearance of clusterized endothelium is associated with the active development of atherosclerosis.     

The dynamics of 2',5'-oligoadenylate synthetase activity in the nuclear and cytoplasmic fractions of human fibroblasts treated by double-stranded RNAs, by their complexes with DEAE-dextran and by type-I recombinant interferons. The ratio of double-stranded RNA-activated and -nonactivated froms of the enzyme

Novel original preparations of double-stranded RNAs (dsRNAs), i.e. larifan, ridostin and rifastin, and recombinant alpha 2- and beta-interferons promising for the clinical use were studied. The size and morphology of the dsRNAs in the preparation composition, the dynamics of their induction of interferon and the antiviral state in human fibroblasts and the effect of the DEAE dextran polycation on the activity of the dsRNAs were specified. For the first time the dynamics of 2',5'-oligoadenylate synthetase activity in the nuclei and cytoplasm of the human fibroblasts treated with the dsRNAs of different origin and their complexes with DEAE dextran was defined. To elucidate the specific features of the mechanism of antiviral action of dsRNAs and interferon, the relation of the 2',5'-oligoadenylate synthetase activity to dsRNAs was investigated. In the cells treated with dsRNAs and DEAE dextran there were an early activation of the enzyme and predominance of the enzyme activated forms requiring no addition of poly I.poly C to the reaction mixture. The results were indicative of possible intracellular activation of its isoforms, similar to that in the cells treated with interferon and contaminated with viruses. All the tested preparations of dsRNAs and interferons induced an increase in the activity of 2',5'-oligoadenylate synthetase both in the cytoplasm and the nuclei of human fibroblasts. The same ability was observed in DEAE dextran which is likely to be one of the causes of the increase in dsRNAs antiviral activity under its effect.     

Low-molecular-weight rRNAs sequences and plant phylogeny reconstruction: Nucleotide sequences of chloroplast 4.5 S rRNAs fromAcorus calamus (Araceae) andLigularia calthifolia (Asteraceae)

Chloroplast 4.5 S rRNAs of the monocotAcorus calamus and the dicotLigularia calthifolia have been sequenced. Phylogenetic trees for the chloroplast 4.5 S and 5 S rRNAs and also for cytosol 5 S rRNAs have been constructed by several methods. They are compared with previous studies. Evidently, it is necessary to consider the inequality of nucleotide substitution rates in different lines for adequate phylogenetic reconstructions. Some relevant conclusions are presented. The possibilities and prospects for using data on low-molecular-weight rRNAs from cytosol and organelles for deducing phylogenetic relationships in plants are discussed.Dedicated to the memory ofS. V. Meyen, Vice-president of the International Organization of Palaeobotany (Dec. 17, 1935–March 30, 1987).