Structural and chemical characterization of S-layers of selected strains ofBacillus stearothermophilus andDesulfotomaculum nigrificans

The structures, amino acid- and neutral sugar compositions of the crystalline surface layers (S-layers) of four selected strains each ofBacillus stearothermophilus andDesulfotomaculum nigrificans were compared. Among the four strains of each species a remarkable diversity in the molecular weights of the S-layer subunits and in the geometry and constants of the S-layer lattices was apparent. The crystalline arrays included hexagonal (p6), square (p4) and oblique (p2) lattices. In vitro self-assembly of isolated S-layer subunits (or S-layer fragments) led to the formation of flat sheets or open-ended cylindrical assembly products. The amino acid composition of the S-layers exhibited great similarities and was predominantly acidic. With the exception of the S-layers of two strains ofB. stearothermophilus (where only traces of neutral sugars could be detected), all other S-layer proteins seemed to be glycosylated. Among these strains significant differences in the amount and composition of the glycan portions were found. Based on this diversity interesting questions may be asked about the biological significance of the carbohydrate units of glycoproteins in prokaryotic organisms.     

An inverse problem in neural processing

Any neural network aimed at the coding sensory events must contain computational properties which generally allow the organism to reconstruct the input signals with some degree of accuracy-else the association between stimulus and response would, at best, be uncertain. In this paper we investigate the problem of reconstructing external input signals to neural networks when the activity profiles of only some of its member cells are known. The evolution and activities of such cells are defined by an earlier formulation of one of us (Ouztöreli 1979) and, here, we restrict our application to local curcuits within the vertebrate retina. Solutions to this inverse coding problem are presented for specific network equations and examplified with 1, 3, and 5 neuron cases.This work was partially supported by the Natural Sciences and Engineering Research Council of Canada under Grant A-4345 to M.N.O. and grant A-4395 to T.M.C. through the University of Alberta     

Control mechanisms of a neural network

In this paper we consider some classical control theoretic properties of a nonlinear neural network proposed by Ouztöreli (1979) to represent the activities of constiuent neurones in terms of the input signals and coupling (associative) properties. By breaking the network into linear and nonlinear components we have been able to localize the nonlinearities in the individual neural response latencies through the system.This work was partially supported by the Natural Sciences and Engineering Research Council of Canada by Grant NSERC-A 4345 to M.N.O. and Grant NSERC-A 2568 to T.M.C. through the University of Alberta     

The comparison of seed protein patterns within the genusArachis by polyacrylamide gel electrophoresis

The seed protein patterns of 12Arachis species were compared by polyacrylamide gel electrophoresis (PAGE), similarities between patterns were measured by the Jaccard index. Results obtained confirm the close relationships established between members of the genus on morphological grounds and support the more recent classification schemes.A. villosa andA. correntina could well be regarded as distinct species on grounds of protein differences whileA. macedoi andA. villosulicarpa (although members of the same section, Extranervosae) show considerable differentiation of their protein patterns. Surprisingly, the formA. ×batizogaea showed less similarity in protein pattern to those of its parental species than might have been expected. The principle value of seed protein pattern data appears to be in distinguishing species within sections.     

Interferon affects intracellular calmodulin levels

Interferon lowers calmodulin levels in two cell lines sensitive to its antiproliferative effect. Further, in synchronized cells, interferon strongly inhibits the increase in calmodulin observed when control cells enter the S phase, and concomitantly inhibits DNA synthesis. Calmodulin has been implicated in the control of cell proliferation and an increase in this protein seems to be necessary for the progression of cells into the S phase of the cell cycle. Therefore, the effect of interferon on calmodulin content might constitute part of the molecular mechanism by which interferon inhibits DNA synthesis.     

Restriction map of Tn7

Tn7, a transposon of 14 kb, encodes resistance to trimethoprim (Tp) and streptomycin (Sm). A cleavage site map of this transposon for twenty-two different restriction enzymes as determined by comparison of restriction enzyme cleavage patterns of the plasmids ColE1 and ColE1::Tn7 is presented. The precise localization of these sites was facilitated by the use of two deletion derivatives of ColE1::Tn7: pGB2 and ColE1::Tn7Δ6, and by the use of pOB14 and pOB15 which contain a part of Tn7 cloned into the plasmid pBR322. This map should aid in the study of the structural and genetic organization of this transposon.     

Recherches sur la conservation du virus de la densonucléose

Résumé Le virus de la densonucléose (VDN) conserve une partie de sa virulence en solution aqueuse entre 0°C et 30°C pendant deux mois. Son pouvoir infectieux se maintient à—10°C pendant deux mois mais est supprimé après dix jours de dessication. On peut done considérer ceParvovirus d’Insectes comme un virus relativement résistant aux températures que l’on rencontre ordinairement dans la nature et au laboratoire.

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Summary The persistence of DNV is described. This virus retains a part of its infectivity in aqueous solution between 0°C and 30°C. The log LD₅₀ initially 7,15 drops to 2 after two months. The virus keeps its infectivity at 10°C but it loses all its pathogenicity after 10 days in dry conditions.

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Ce travail a été réalisé en partie dans le cadre d’une convention I.N.R.A.-D.R.M.E.     

Study of the effect of volatile substances from cereal roots

We traced the liberation and biological effect of volatile substances released from the roots of cereals,i. e. barley, wheat, rye and oats, on seedlings of the same and other plant species. Experiments were carried out in a closed glass apparatus with a static or circulating atmosphere in which the CO₂ and O₂ were permanently absorbed and supplemented, respectively. In some experiments the air was bubbled through water or through solutions of boric acid, barium hydroxide and potassium permanganate. The roots of all four cereals tested released volatile substances with a biological activity which appeared to be non-specific with respect to plant species. The effect of volatile substances was partially decreased by bubbling through water, barium hydroxide and boric acid and was completely removed after passing through the solution of potassium permanganate. Volatile substances liberated from roots of barley inhibited elongation of roots and coleoptile, decreased SH-group content and caused excessive formation of root hairs as well as inhibition of both dry matter production and respiration of roots of rye seedlings. Ethylene was found in the atmosphere of experimental vessels.     

Struktur und quantitatives Verhalten des perimitochondrialen granulären endoplasmatischen Retikulums der Mäuseleber

Zusammenfassung In normalen Leberzellen der Maus wurde das quantitative Verhalten des perimitochondrialen granulären endoplasmatischen Retikulums untersucht. 74% der Mitochondrien zeigen Beziehungen zum granulären endoplasmatischen Retikulum. Die einzelnen Mitochondrien werden zu 52%19,5 von den Membranen des granulären endoplasmatischen Retikulums bedeckt. Je Mikrometer Membranstrecke sind auf der mitochondriennahen Seite des granulären endoplasmatischen Retikulums 21 und auf der mitochondrienfernen Seite 20 Ribosomen zu finden, was der Zahl im übrigen granulären endoplasmatischen Retikulum entspricht. Die Befunde stellen die Grundlage für Untersuchungen des perimitochondrialen granulären endoplasmatischen Retikulums unter pathologischen Bedingungen dar.

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Structure and quantitative behaviour of the perimitochondrial granular endoplasmic reticulum in the liver cells of the mouse

Summary The perimitochondrial granular endoplasmic reticulum in normal mouse liver cells has been investigated quantitatively. 74% of the mitochondria are in association with the granular endoplasmic reticulum. The individual mitochondrion is covered by the membranes of the granulated E. R. in 52%19.5. The outer surface of the endoplasmic membrane, facing the mitochondrion, is occupied by 21 ribosomes per m; the corresponding surface of the membrane facing the free cytoplasm is occupied by 20 ribosomes per m. These data are in agreement with those of that fraction of the E. R., which is not in association with mitochondria. These findings represent a basis for investigations of the perimitochondrial endoplasmic reticulum under pathological conditions.

     

Retting of Flax by Aspergillus niger

In this study, retting was carried out by Aspergillus niger. The pH, galacturonic acid (GA), and total reducing sugar were determined; the end point was identified by the classic empirical processes and by the maximal GA content of the retting water. The process gave clear and resistent fibers, and the retting time was similar to that of current industrial processes with bacterial enzymes. Control of total acidity was not required, since the pH remained close to neutrality throughout the entire process.