Structure of macrocyclic K+, Rb+-complexon of meso-valinomycin monohydrate, cyclo[-(D-Val-Hyi-Val-D-Hyi)3-].H2O, in a crystalline complex with dioxane by x-ray structural data]

The crystal structure of a valinomycin analogue, cyclo[-(D-Val-Hyi-Val-D-Hyi)3-]x(C60H102N6O18) crystallized with dioxane and water molecules, has been solved by X-ray direct methods. The conformation found is analogous to one established for free meso-valinomycin crystallized from other organic solvents. It is characterized by a centrosymmetric bracelet form, stabilized by six intramolecular 4----1 type hydrogen bonds between amide N-H and C = O groups. One water molecule is fixed asymmetrically by hydrogen bonds in the internal negatively charged cavity of the complexon. The meso-valinomycin molecule "bracelets" in the crystal form stacks alternatively with dioxane molecules.     

Genetic control and expression of the major ejaculatory bulb protein (PEB-me) inDrosophila melanogaster

PEB-me is a predominant protein of matureDrosophila melanogaster ejaculatory bulbs. It is resolved into four or five closely spaced subfractions (apparent molecular weight 35–39 kD) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Four electrophoretic variants of PEB-me differing in apparent molecular weight by 200–800 daltons were found. These appear to be controlled by four alleles of a gene (peb) located by recombination and deletion mapping to the 60F1-2 region of chromosome 2. A minor ejaculatory bulb protein of ca. 80 kD (hPEB) was found to be immunochemically related to PEB and possibly encoded bypeb. PEB is not detected by immunoblotting techniques in virgin females, in male tissues other than the ejaculatory bulb, or during developmental stages preceding the formation of this organ. The results of transplantations of genital imaginal discs and of immature ejaculatory bulbs between two strains having different PEB alleles suggest that the ejaculatory bulb is the site of PEB synthesis. In flies mutant fortra, tra-2, dsx, orix, tissue specificity of PEB localization is retained and the protein is found whenever the ejaculatory bulb is formed, regardless of the chromosomal sex of the fly. The protein is transferred into the female genital duct during mating, where it can be detected for up to 12 hr. Possible functions of PEB inDrosophila reproduction are discussed.     

Phenotype and "critical segments" of chromosomes during partial aneuploidy for chromosome 4 in man

Computerized analysis of sparse matrix, based on the list of involved organs, body parts, extremities, function etc. (total item number about 600) was performed for different cytogenetically identified anomalies of human chromosome 4 (35 cases of 4p-, 32 cases of 4p+, 39 cases of 4q-, 39 cases of 4q+; both published and original data were used). For each of the four types of partial aneusomy, 4 specific enough groups of traits were revealed which had been found in 50% of respective patients, at least. Such "nuclei" of traits were highly similar to those given in comprehensive modern manuals. However, 4p- and 4q- could only be classified as strictly enough delineated chromosomal syndromes. The 4(p14-pter) region was found to be the most likely crucial segment for the Wolf-Hirschhorn syndrome.     

Properties of the slow excitatory postsynaptic potential in mammalian sympathetic ganglion cells

Two types of slow excitatory postsynaptic potentials (EPSPs) with different properties were found in neurons of the rabbit superior cervical sympathetic ganglion. In our group of neurons slow EPSPs increased during artificial hyperpolarization and decreased during depolarization of the membrane. The input resistance of the cells fell or remained unchanged during the development of slow EPSPs. In the second group of cells slow EPSPs increased during depolarization and decreased during hyperpolarization. The reversal potential of these responses, determined by extrapolation, was –78.9±3.6 mV. Depolarization responses to activation of muscarinic cholinergic receptors by acetylcholine or carbachol developed in 53% of neurons with an increase in input resistance and had a reversal potential of –83.2±6.7 mV. It is suggested that in cells of the first group the ionic mechanism of the slow EPSPs is similar to that of the fast EPSPs, whereas in cells of the second group its main component is a decrease in the potassium conductance of the membrane.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 13, No. 4, pp. 371–379, July–August, 1981.     

Reconstruction of the tubular epithelium of allotransplanted kidneys of man in late periods following transplantation]

The structure of allotransplanted kidneys (AK) from human cadavers that remained in the recipient's body for a long time (4 months-6 years) has been studied. AK that preserved good function up to the patient's death not consequent on the transplant insufficiency showed a weak immunocellular connective tissue, with the epithelium of proximal canaliculi being cytologically reconstructed. The reconstruction lay in formation of numerous polykaryocytes having a hypertrophied brush-like outline. This phenomenon ("proximal polykaryocytosis") is assessed as a manifestation of regeneratory potencies of the epithelium of AK proximal tubules in late periods after transplantation. Chronic moderate hypoxia of AK was conducive to reconstruction of the epithelium of the nephron proximal part. Inadequate function of AK was related to the development of chronic rejection resistant to the treatment, and AK demonstrated an intensive immunocellular reaction and developed gross sclerosis that produced atrophy of most AK tubular.     

The development of mouse spinal cord in tissue culture

Summary Whole mouse embryos were grown in vitro from Theiler stage 12 (1 to 7 somites) to Theiler stages 15 and 16 (25 to 35 somites). This procedure gives experimental access to precisely staged embryos during the early period of neurogenesis. To follow the further development of neurons in vitro, fragments of spinal primordia were set up from these cultured embryos. In such cultures, the proliferation of precursor cells, the formation of postmitotic cells and, finally, the cytodifferentiation of neurons were observed. A preliminary account of this work was given at the Tissue Culture Association Meeting in 1977, and the Canadian Federation of Biological Societies Meeting in 1977 (1,2). This work was supported by Grant MT 4235 from the Medical Research Council of Canada.     

Genetic structure of Staphylococcus epidermidis strain No. 17 possessing penicillinase and bacteriocinogenic activity]

The studies on the genetic structure of Staphylococcus epidermidis, strain 17 showed that this strain possessed a factor of bactericinogenicity of the one type, which was an extrachromosomal element not bound with penicillinase activity. The loss of the bacteriocinogenicity factor spontaneously or under the effect of acridine orange at a temperature of 37 degrees C was not observed. Passages of the strain at a temperature of 44 degrees C for 5 days and acridine orange proved to be the most effective eliminating factors. The loss of the bacteriocinogenicity plasmid did not result in changing any biochemical properties of the strain but was accompanied by a loss of the immunity to bacteriocin of the initial strain. The study of the growth regularities of the initial strain and its variant deprived of the bacteriocinogenicity plasmid showed that multiplication of the cells in the presence of the plasmid practically started without the latent period.     

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.     

The mutagenic effect of different types of irradiation on the sex cells of male mice. VIII. Frequency of development of reciprocal translocations in the spermatogonia of mice subjected to chronic gamma-irradiation]

The frequency of reciprocal translocations in mice spermatogonia after the exposure to chronic gamma-irradiation at doses of 100, 200, 300, 600, 920 r, at the dose rate of 4,2 r/day was investigated. It was shown that the mutation frequency increased insignificantly with the increase of the radiation dose (y =0,8+0.0011x). The comparison of the data obtained with earlier results revealed no changes in the yield of translocations at the reduction of the dose rate from 10 r/day to 4,2 r/day. The investigation of the genetic radiosensitivity of mice spermatogonia after a chronic gamma-irradiation showed a tendency to increase in their radioresistance.