Heterologous transformation in Bacillus subtilis. 1. Transmission of DNA of the R1drd19 plasmid]

Bac. subtilis 168 (BD-25) cells were infected with DNA of plasmide R1drd19 isolated from E. coli strain; transformants resistant to streptomycin (500 microgram/ml) and kanamycin (40 microgram/ml) appeared with the frequency of 2.10(-6). These transformants retained resistance to the mentioned antibiotics stably. A satellite DNA peak was revealed in centrifugation in the density gradient of cesium chloride with ethidium bromide. It was possible to infect cells of Bac. subtilis 168 (BD-25) with plasmide DNA isolated from the transformants. Plasmide transduction with the aid of phages AR9 and PBSI multiplied on the transformant strains was also effected. Physico-chemical analysis of the transformed plasmide DNA was conducted; its molecular weight was determined.     

Biochemical characteristics of allelopathic activity of germinating seeds

Biochemical characteristics (enzyme activities, contents of vitamins, phytohormones, nucleic acids, proteins, saccharides, etc. ) in germinating seeds and developing seedlings are summarized, and the inhibitory and stimulatory actions of these compounds on plant growth and development are discussed. This paper is based on and employs a broader definition of allelopathy than most other contributions to this collection of colloquium reports, in that it includes all interactions of plants, not merely inhibitory ones     

Sensitivity to stress in the bivalve Macoma balthica from the most northern (Arctic) to the most southern (French) populations: low sensitivity in Arctic populations because of genetic adaptations?

The stress sensitivity, determined in copper exposureexperiments and in survival in air tests, and thegenetic structure, measured by means of isoenzymeelectrophoresis, were assessed in populations of theBaltic clam Macoma balthica (L.) from itssouthern to its northern distribution limit, in orderto test the hypotheses that near the distributionlimit the clams would be more stress sensitive andwould have a lower genetic variability. Thepopulations in west and north Europe show a stronggenetic resemblance. The populations in the sub-ArcticWhite Sea are genetically slightly different, and showa low stress sensitivity. The populations in theArctic Pechora Sea are genetically very distant fromthe other populations, and show the lowest stresssensitivity. Near the southern distribution limit, inagreement with the hypotheses, genetic variability islow and stress sensitivity high. On the other hand, incontrast to expectation, near the northerndistribution limit, in the populations of the PechoraSea, the genetic variability was higher, thus notreduced, and the stress sensitivity was low comparedto all other populations. Yet, it remains a questionif such is due to gradual physiologicalacclimatization (and ongoing differential selection)or to genetic adaptation.     

Kinetic and steady-state characteristics of sodium channels modified by aconitine

Kinetic and steady-state characteristics of sodium channels of the Ranvier node membrane, modified by aconitine, were investigated by the voltage clamp method. Channels modified by aconitine were shown to be only partially inactivated. Dependence of the fraction of uninactivated channels on voltage can be described by a model of a channel with three states: closed, open, and inactivated. It is suggested that aconitine does not significantly change the parameters of the inactivated state. Repolarization of the membrane to between –70 and –110 mV after a long (10 msec) test shift of potential induces initially a rapid decline of the current ("tail"), followed by a slow rise to the steady-state value. To explain the kinetics of this current it is necessary to postulate two or more open states of the channel.Institute of Cytology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 12, No. 6, pp. 612–618, November–December, 1980.     

Search for MHC-associated genes in human: five new genes centromeric to HLA-DP with yet unknown functions

Taking advantage of five mouse genomic or cDNA probes [KE5(probe 14), KE4 (probe11), KE3 (probe7), KE2 (probe5), and SET] mapped on the H-2K region in mouse, we have identified and localized homologues of these five genes in the human major histocompatibility complex region (HKE5, HKE4, HKE3, HKE2, and HSET, respectively). Cosmid cloning and pulsed field gel electrophoresis analyses indicated that a human homologous gene, HKE5, is located 10 kilobases (kb) centromeric of the 2(XI) collagen (COL11A2) gene followed by HKE4. HKE3, closely linked to HKE2, is located 170 kb centromeric of HKE4. Furthermore, HSET is located 50 kb centromeric of HKE2. This gene organization outside the DP subregion is completely identical to that of the mouse H-2K region centromeric of I-Pb 3, a mouse homologue of the DPB gene, except the lack of genes corresponding to the H-2K and -K2 genes in human.     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

Evidence for existence of two acid groups controlling the conductance of sodium channel

The inhibition of the sodium current in nodal membrane at low pH external solutions was studied under voltage clamp conditions. Analysis of the data for membrane potentials from +10 to +150 mV shows that the inhibition of the Na+ currents at high positive potentials cannot be described by a titration curve of a single acid group. The data can be explained on assumption that the conductance of each sodium channel is controlled by two acid groups: one is located within the pore, the other just near the outer mouth of the pore. The affinity of both groups for H+ is estimated.     

Comparative Molecular Genetic Analysis of β-Fructosidases of Yeasts <Emphasis Type="Italic">Saccharomyces</Emphasis>

To study the evolution of the polymeric β-fructosidase (invertase) genes (SUC) of yeasts Saccharomyces, new SUC gene of S. cariocanus was cloned and sequenced and the nucleotide and amino acid sequences were compared for all known β-fructosidases of Saccharomyces species. The proteins showed 90–97% homology. The most divergent was S. bayanus β-fructosidase. The results testified again to high conservation of yeast β-fructosidases. Transitions C-T prevail in the total spectrum of nucleotide substitutions observed in the coding regions of the SUC genes; most of these transitions are in the third codon position and cause no changes in the amino acid sequences of the encoded proteins. The six Saccharomyces species each carry one (probably, non-telomeric) β-fructosidase gene. SUC is on chromosome IX in S. cerevisiae, S. bayanus, S. kudriavzevii, S. mikatae, and S. paradoxus and in a translocation region on chromosome XV in S. cariocanus.__________Translated from Molekulyarnaya Biologiya, Vol. 39, No. 3, 2005, pp. 413–419.Original Russian Text Copyright © 2005 by Korshunova, Naumova, Naumov.