Effects ofStreptococcus sanguinisBacteriocin on Cell Surface Hydrophobicity, Membrane Permeability, and Ultrastructure ofCandidaThallus

Candida albicans(C.a) andCandida tropicalis(C.t) were treated withStreptococcus sanguinisbacteriocin (S.s bacteriocin), respectively; the bacteriostatic dynamics of S.s bacteriocin, their effects on cell surface hydrophobicity, leakage of inorganic phosphorus and macromolecular substance, cytosolic calcium concentration, and ultrastructure changes ofCandidathallus were detected and analyzed. The results showed that inhibitory effect of S.s bacteriocin on C.a and C.t reached peak level at 24 h, the cell-surface hydrophobicity decreased significantly (P< 0.05) after S.s bacteriocin treatment, and there was leakage of cytoplasmic inorganic phosphorus and macromolecular substance from C.a and C.t; cytosolic calcium concentration decreased greatly. After 24 h treatment by S.s bacteriocin, depressive deformity and defect could be found in the cell surface of C.a and C.t; the thallus displayed irregular forms: C.a was shrunken, there was unclear margins abutting upon cell wall and cell membrane, nucleus disappeared, and cytoplasm was inhomogeneous; likewise, C.t was first plasmolysis, and then the cytoplasm was shrunk, the ultrastructure of cell wall and cell membrane was continuously damaged, and the nucleus was karyolysis. It was illustrated that S.s bacteriocin had similar antifungal effect on C.a and C.t; their cell surface hydrophobicity, membrane permeability, and ultrastructure were changed significantly on exposure to S.s bacteriocin.

Characterization of type III kerogen from Tyrolean shale (Hahntennjoch, Austria) based on its oxidation products

A 29-step alkaline permanganate degradation of type III kerogen from Tyrolean (Hahntennjoch, Austria) oil shale was performed. A high yield of oxidation products was obtained (93.7 % relative to the original kerogen): 0.5 % neutrals and bases, 19.5 % ether-soluble acids and 58.9 % of precipitated (PA). A substantial amount of kerogen carbon (14.8 %) was oxidized into carbon dioxide. The organic residue remaining after the final oxidation step was 6.9 %. The PA components were further oxidized and the total yields relative to original PA were 1.0 % neutrals and bases and 59.0 % ether-soluble acids, the non-degraded residue being 29.3 %. Detailed quantitative and qualitative analysis of all oxidation products suggested the Tyrolean shale kerogen to be a heterogeneous macromolecular substance consisting of three types of structures differing in composition and susceptibility towards alkaline permanganate: the first, resistant, presumably composed of aromatic structures linked by resorcinol ethereal bonds; the second, combined in nature, the aliphatic part comprising methyl-substituents and short cross-links, both easily oxidized into CO2, water and low molecular weight acids and aromatic structures yielding aromatic diand tri-carboxylic acids as oxidation products; finally the third, composed of aliphatic cross-links and substituents, alicyclic (and/or heterocyclic) and some aromatic structures, bound into units moderately resistant towards oxidation. The overall yields of kerogen and PA oxidation products lead towards a balance between aromatic, alkane monoand dicarboxylic and alkanepolycarboxylic acids, suggesting a shift of the structure of Tyrolean shale kerogen from typical aromatic reference type III towards a heterogeneous aromatic-aliphaticalicyclic type structure.

A NEW METHOD TO DISTINGUISH SEPARATE COMPONENTS IN CYTOCHEMICALLY STAINED MACROMOLECULES BY ANALYSIS OF THE KINETICS OF THE STAINING AND DESTAINING PROCESSES

A new method making it possible to analyze properties of the end products of cytochemical staining reactions in macromolecular substances not expressed in the absorption spectra is described. Mathematical analysis of the course of changes in the absorbance during staining or destaining of the macromolecular substance provides information about the reaction velocities of these processes for the individual components present as well as about the concentrations of the components thus detected. This analysis is performed by a procedure of computerized curve-fitting between experimentally determined and theoretically expected absorbance curves. The theoretical time course of absorbance is derived for a number of pseudo first-order reaction schemes, and a description is given of the way in which the most appropriate reaction scheme can be recognized and the parameters are estimated, both on the basis of the experimental absorbance curve. Possible complications due to dye impurities, depolymerization and diffusion processes are discussed.

Reaction of Chloral with 1,4-Polyisoprene

The cis-1,4-polyisoprenes are composed of 2-methyl-2-butene units, the double bonds of which must be favorable to the addition of strongly electrophylic reagents such as certain aldehydes. Chloral is of this type and its ionic reactions with various simple olefins has been described. We found it worth while to transpose these results to polyisoprenic macromolecules, either natural or synthetic. The ionic reactions generally create less modifications of the chain, such as fission or crosslinking, than would result from free radical reactions. Also, if the formation of free radicals is avoided, the possible fixation of chloral on the halogen carrying carbon (group —CCl2—CHO) becomes very unlikely. Pure anhydrous chloral is used as the reagent. A solution of 2% cis-1,4-polyisoprene (natural) in cyclohexane or decalin (free of peroxides) is heated under a nitrogen atmosphere with the reagent and in presence of a catalyst such as AlCl3 or BF3 at a concentration of 1–3% relative to the polyisoprene. The macromolecular product obtained is then subjected to a fractionation by the chloroform-methanol combination. After purification and desolvation of the main fraction an elemental analysis is made and the level of fixation n calculated based on the chlorine content. Table 1 relates some of the results obtained by using AlCl3 or BF3. In the absence of catalyst (Figure 1, A) the level of fixation is low: n=4 and therefore the nature of the reaction remains uncertain. In the presence of AlCl3 or of BF3, n increases rapidly in function of the temperature and of the relative molar concentration of the reagents, as shown by the curves B and C of Figure 1. The highest level of fixation obtained in these experiments is n=22. Figure 2 demonstrates this limit which is reached beyond the molar ratio of m=4, in the presence of AlCl3 (3%). Table 2 shows the particular action of AlCl3 which among all the catalysts tested proves to be as effective as BF3 without yielding any notable crosslinking of the macromolecular substance.

The Importance of Rheology in the Processing of Rubber. 1. Rheological Investigations of Rubber Solutions

Using the mastication of rubber as an example, it is shown how rheology can be utilized, even in the industrial processing of macromolecular substances, to obtain, from an easily and quickly determined flow curve, a value dependent on the weight average molecular weight, and a numerical value for the polymolecularity. Solutions of chain macromolecules with a sort of Gaussian molecular weight distribution give a symmetrical flow curve with an inflection point which, as the velocity gradient which is independent of the concentration, is a function of the average molecular weight. At the same time the slope of the linearized flow curve provides a numerical value for the polymolecularity of the material in question. In this way, even those changes in a macromolecular substance which occur during factory processing can be measured, as is the case here with masticated rubber.

Secondary Softening Regions of Copolymers, Mixed Polymers, and Graft Polymers

A polymer is a macromolecular substance which is built up from individual monomeric units by a process of chemical linking into a long chainlike substance. Figure 1 is an attempt to give in schematic form a picture of the general structures of three purported types of copolymers, mixed polymers, and graft polymers.

PREPARATION FROM HUMAN RED CELLS OF A SUBSTANCE INHIBITING VIRUS HEMAGGLUTINATION

Methods have been described for the extraction and purification of an agent inhibiting the hemagglutination of red cells by influenza (PR8) and mumps viruses. Human red cells have served as the chief source of the inhibitor but the latter has also been found in human lung. The active extracts have been purified to the extent that 0.1 gamma of material suffices to inhibit one hemagglutinating dose of virus. Incomplete chemical characterization of the most highly purified fractions available indicates the presence of 2.6 per cent nitrogen, at least 50 per cent of polysaccharide, and no phosphorus. In the ultracentrifuge the purified preparation behaves as a polydisperse macromolecular substance. The active material can be obtained from red cell stroma in an ether- and chloroform-soluble form which, on further treatment, can be converted into chloroform-insoluble material. It is possible that the former represents more closely the virus receptor as it exists in the red cell. The purified inhibitor is inactivated on incubation with the virus at 37°C. The nature of this effect is being investigated.