ALBERT

Notes: Summary The energy transfer ability of free and polymer-bound acetophenone and benzophenone has been studied. The polymeric sensitizers were prepared by acetylation or benzoylation of atactic polystyrene (¯Mn=67.000). Trans-cis isomerization of stilbene, monitored by UV-spectrophotometry, has enabled the energy transfer process to be probed. The values of the Stern-Volmer constants, determined by following this technique, indicate that the energy transfer efficiency of both ketones is higher when they are in free state than when they are polymer-bound.

Notes: Summary The solution polymerization of phosphonitrilic chloride trimer has been studied by using 50% by weight monomer in Chlorobenzene. Polymerization reactions were conducted at temperatures between 198° and 240°C, and reaction times ranged from 12 to 96 h. Mostly soluble polymer was obtained up to a conversion of 30%. insoluble product was detected only above 240°C and 72 h. of reaction time. Polymers were characterised by intrinsic viscosity and weight average molecular weight, Mw, by light scattering (Zimm plot).

Notes: Abstract A systematic study on autolysis of the cell walls of fungi has been made on Neurospora crassa, Botrytis cinerea, Polystictus versicolor, Aspergillus nidulans, Schizophyllum commune, Aspergillus niger, and Mucor mucedo. During autolysis each fungus produces the necessary lytic enzymes for its autodegradation. From autolyzed cultures of each fungus enzymatic precipitates were obtained. The degree of lysis of the cell walls, obtained from non-autolyzed mycelia, was studied by incubating these cell walls with and without a supply of their own lytic enzymes. The degree of lysis increased with the incubation time and generally was higher with a supply of lytic enzymes. Cell walls from mycelia of different ages were obtained. A higher degree of lysis was always found, in young cell walls than in older cell walls, when exogenous lytic enzymes were present. In all the fungi studied, there is lysis of the cell walls during autolysis. This is confirmed by the change of the cell wall structure as well as by the degree of lysis reached by the cell wall and the release of substances, principally glucose and N-acetylglucosamine in the medium.

Notes: Abstract Certain groups of fungi share chemical structures which makes difficult the isolation and differentiation of specific antigens by the usual methods of extraction and purification. Therefore, we have oriented our studies to the immunological and biochemical characterization of differences and similarities of molecular structures from fungi, etiologic agents of systemic mycoses, hoping to establish criteria for the utilization and handling of these antigens. A deproteinized polysaccharide-protein complex (D-PPC) was isolated from Histoplasma capsulatum and Blastomyces dermatitidis. The immunological studies with humoral tests indicate a variable cross reaction between antigens of both species. In immunodiffussion systems, the reaction was specific for each species using saline solution or phosphate buffer solution, while using an agarose veronal system, the cross reactions were very evident. In addition, differences in cross reactions were obtained with immunoelectrophoresis, haemagglutination and complement fixation microtest. This variation in cross reaction responses suggest that these antigens (D-PPC) share common structures but at the same time must have some different component owned by each one of the fungi which makes them more specific than crude antigens.

Notes: Summary A total of 2363 Cuban newborns were screened for genetic hemoglobin abnormalities; 2187 (92.56%) had a normal electrophoretic pattern. Of the 176 samples with abnormal electrophoretic patterns, 102 (4.32%) had hemoglobins A, F plus Bart's; 54 (2.29%) had hemoglobins A, F and S; 3 (0.13%) had hemoglobins A, F, S plus Bart's; 14(0.59%) had hemoglobins A, F and C; 1 (0.04%) had hemoglobins A, F, C and Bart's. The frequency of Hb Bart's was 4.46% in AA phenotype, 5.25% in AS, and 6.67% in AC. Two newborns were found to have rare variants. A close correlation was found between the observed and expected phenotypes, which indicates the accuracy of the diagnostic methods used. The results of all hemoglobin abnormalities were entered on the infants' hospital records. In addition, these families received genetic counseling.

Notes: Abstract The core of the El Tormes thermal dome, situated in the central part of one of the main metamorphic belts of the Iberian Peninsula, is formed by garnet-cordierite-biotite-sillimanite pelitic gneisses. These rocks, that very often are cut by minor intrusions of Al-rich S-type granites, are metatexitic gneisses in which there exists garnet showing different stages of resorption and transformation into an aggregate of cordierite±plagioclase±biotite. The garnet, mantled and corroded mainly by cordierite, has never been found to occur in contact with the prismatic sillimanite of the matrix, thus indicating that the continuous reaction Gr+Sill+Q = Cd has taken place. The presence of corroded biotite inside the garnet-rimming cordierite of the aggregates as well as inside the cordierite of the matrix, which usually includes remmants of sillimanite, indicates that the continuous reaction Bi+Sill+Q = Cd+FK+H2O has occurred too. Therefore, a realistic net reaction for these aggretates should be represented by the univariant, at a given $$X_{{\text{H}}_{\text{2}} {\text{O}}} $$ , equilibrium: Biotite+Sillimanite+Garnet+Quartz = Cordierite+K-feldspar+H2O (1) The important garnet resorption near the anatectic granitic veins implies that this process is favoured by a decrease in $$X_{{\text{H}}_{\text{2}} {\text{O}}} $$ , this factor being otherwise buffered by the reaction (1) assemblage. The most probable P-T path, assuming these conditions, consistent with the AFM projection of the former (inferred) and present assemblages in the aggregates and in the matrix, implies a decrease in P coeval with a decrease in T (Fig. 4, path 2). The most reliable P-T determination for the final stage of garnet breakdown through reaction (1), based on the coexistence of the seven phase assemblage garnet — cordierite — biotite — sillimanite — plagioclase — potash feldspar — quartz plus melt, gives 695° C, 4.3 kbar, $$X_{{\text{H}}_{\text{2}} {\text{O}}} $$ = 0.5, The maximum pressure for this process, obtained from the garnet — plagioclase equilibrium, is 6.5±1 kbar at the same temperature. The estimates of the T for the garnet core-garnet included biotite pairs are consistently lower, ca. 550° C, than those obtained for the garnet rim-biotite in aggregates, ca. 645° C, or garnet rim-adjacent cordierite pairs, ca. 695° C. It may, therefore, be supposed that, during their evolution these rocks underwent first an increase in T and then, during the last stages, as garnet and biotite brokedown, a decrease in P and T. This represents an uplift of the core of El Tormes dome under high grade amphibolite to low pressure granulite facies conditions, accompanied by a process of partial melting with local decrase in $$X_{{\text{H}}_{\text{2}} {\text{O}}} $$ . It is suggested, from mineral growth-deformation relationships, that this process took place during the late hercynian deformation phases, P-3 or doming stage.

Notes: Abstract The electrophoretic patterns of esterase (E-1), alcohol dehydrogenase (ADH), and glutamate oxaloacetate transaminase (GOT) isozymes were studied in two Spanish populations of the lily Scilla autumnalis with B-chromosome carrying individuals. The E-1 isozyme activity appears only in those individuals with B-chromosomes. None of the bulbs free of B's show it. Five bulbs, mosaic for B-content, were identified. Electrophoretic analysis shows that these bulbs are characterised by mosaicism for E-1 isozyme activity. An analysis of individual roots by both electrophoretic and cytological methods shows that tissue mosaicism for B-content correlates with tissue mosaicism for E-1 isozyme activity. The electrophoretic analysis of different roots from bulbs heterozygous for the Est-1 locus indicates that the structural gene for E-1 is not located on the B-chromosome itself. Rather there is a derepressor effect of Bs on E-1 isozyme activity. Since ADH and GOT patterns are unaffected by the presence of B-chromosomes it is clear that they do not exhibit a generalised derepressor effect.

Notes: Summary Depolymerization kinetics of microtubules assembled to steady-state by pod ophyllotoxin treatment show a dose-dependent effect of this mitotic poison on the net rate of microtubule disassembly. Pulse-chase experiments with microtubules at steady-state indicate that the depolymerization effect induced by superstoichiometric concentrations of podophyllotoxin relative to tubulin is polar and time-dependent, i.e. the rate of tubulin loss decreases along with the time of treatment in the presence of the drug. Under these conditions the rate of microtubule disassembly is much faster than one could expect from a unique effect of drug-tubulin complex on the microtubule assembly end. Podophyllotoxin-tubulin complex is not able to induce active depolymerization of microtubules, while free podophyllotoxin is. These results are consistent with the hypothesis that this drug acts on the microtubule assembly-disassembly process by two different mechanisms: 1) as a free drug, it actively promotes polar depolymerization of microtubules, and 2) as a drug-tubulin complex, it retards the addition of subunits into the microtubule ends.

Notes: Abstract Orthorhombic single crystals of cytoplasmic aspartate aminotransferase were examined alone or in the presence of substrates or inhibitors to quantitatively compare the interaction of ligands with the active-site chromophore between soluble and crystalline enzyme. As in enzyme solutions, equilibrium kinetic measurements can be made between substrates and single crystals of cytoplasmic aspartate aminotransferase. The absorption spectra of ligand-free enzyme forms and of enzyme-substrate or-inhibitor complexes are as distinctive as when the enzyme is in solution. The dissociation constants for glutamate with the pyridoxal form of the enzyme are identical to those in solution. The substrate analog erythro-β-hydroxyaspartate also binds with equal affinity to the active site in enzyme crystals as in solution; and the affinity of α-ketoglutarate to bind in nonproductive complexes with the pyridoxal form of the enzyme is also unimpaired in the crystal (K d =2 mM). In contrast to the affinity constants, the stoichiometry of the interactions does not appear to correlate to those in solution. In the presence of an amino acid plus keto acid substrates pair, the absorbance values of the enzyme-substrate complex(es) could be interpreted as for occupany of only half the available sites in the crystals. Yet an amino acid, cysteine sulfinate, and α-keto acids such as β, β-difluorooxalacetate convert all active sites in the crystal to the pyridoxamine or pyridoxal form when added to the pyridoxal or pyridoxamine forms, respectively. This ability to completely undergo substrate-induced half-transamination and the apparently conflicting results in trapping half the sites in enzyme-substrate complexes are incorporated into a proposed reciprocating mechanism applicable only to the crystalline state of the enzyme and dictated by crystal packing forces rather than an intrinsic property of the enzyme. Active-site bound pyridoxal phosphate continues to behave as a pH indicator; nevertheless, the pK value of the single crystals is a pH unit (pK=7.15) higher than that in solution. This variation is interpreted as indication of a difference in the environment of the chromophore between the crystal and solution states. While the environmental difference does not significantly alter the affinity for substrates, it could account for the reduced rates in transformation of the enzyme-substrate complexes in half-transamination reactions in the crystalline state.