Palaeoecological and phytosociological reconstruction of precultural vegetation in the Bílý Kříž area,the Moravskoslezské Beskydy Mts,Slovak Republic

A combined palynological and phytosociological methodological approach was used in the reconstruction of precultural forest vegetation in a small model area of Bílý Kí-Janík in the Moravskoslezské Beskydy mountains (northwest Slovakia). Two pollen diagrams show the predominance of Fagus sylvatica, Abies alba and Picea abies in past natural mixed forests. The present-day occurrence and distribution of forest herbs allow the differentiation of five past vegetation types with above mentioned forest climax trees covering the area before the beginning of human interference. A map of reconstructed natural vegetation is presented which can be used for revitalization of present secondary spruce plantations, heavily affected by air pollution.     

Superoxide dismutase mimetic activity of a cyclic tetrameric Schiff base N-coordinated Cu(II) complex

A pulse radiolytic study using the cyclic tetrameric Schiff base N-coordinated copper complex Cu(TAAB)²⁺ has been performed. The reaction of the Cu(TAAB)²⁺ complex with superoxide revealed pseudo first-order characteristics with the rate constant of k ₂ = (2.9 ± 0.5) × 10⁸ mol^–1 s^–1 dm³. The complex survive presence of competing serum albumin in physiological concentrations. The complex stability constant K = 1.15 × 10¹⁸ (log K = 18.06) is two orders of magnitude higher than that of Cu(II)-serum albumin (log K = 16.2). Transient changes of the stability during the oxidation/reduction process and in the presence of 600 /mol l^–1 albumin did not affect significantly either the electronic absorption of the complex or its catalytic activity.     

Phosphate regulation of phosphatases in submerged cultures of Claviceps purpurea 129 producing clavine alkaloids

Summary Claviceps purpurea strain 129 was cultivated under submerged conditions in a sucrose-citrate medium containing high (36.8 mM) or low (1.84 mM) KH₂PO₄ concentrations. The permeabilized cells and culture supernatants contained alkaline and acid phosphatases. In the medium containing a high phosphate concentration, the synthesis of extracellular phosphatases was repressed, but that of cellular phosphatases was not. Extracellular phosphatases, especially alkaline phosphatases, were derepressed by transferring the mycelium into a phosphate-free medium. This derepression was inhibited by cycloheximide. In the presence of cycloheximide, the activities of the cellular phosphatases decreased markedly, indicating turnover of these enzymes. The cellular acid phosphatase was inhibited by phosphate (0.025 M–0.1 M) and NaF (0.01 M) while the cellular alkaline phosphatase was only inhibited by phosphate. Both cellular and extracellular alkaline phosphatases were more sensitive to repression by phosphate than the acid phosphatases. The alkaloid synthesizing enzymes were: a) present in mycelia grown in high levels of phosphate and b) activated by decreasing the intracellular phosphate level.     

Studies of γ-glutamyltransferase activity in the brain tissue post mortem

Our experiments showed that the activity of -glutamyltransferase (-GT) did not remarkably change in homogenates of mouse, rat, and bovine brains during the first four days post mortem. In the course of that period, the brain microvessels also retained their -GT activity. -GT of microvessels from bovine brain cortex, solubilized with sodium deoxycholate, was eluted in the void volume V_o when chromatographed on a Sephadex G-200 column with the detergent Triton X-100. In human post mortem brains, the specific activity of -GT in choroid plexi was found to be about five times higher than that in the cerebral cortex, white matter, basal ganglia, pons, and cerebellum but about four times lower than that in the microvessels obtained from the studied brain regions. Our findings suggest that it is possible to study the components of the blood-brain barrier on material from deceased subjects.     

The content and composition of the essential oil in the course of Anthodium development in wild camomile (Matricaria chamomilla L.)

A study was made of the changes in the content of essential oil and its components (farnesene, (-)-α-bisabolol, (-)-α-bisabololoxide A, (-)-α-bisabololoxide B and spathulenol, α-bisabolonoxide A, chamazulene, cis en-in-dicycloether) and of the number of secretory canals in the receptacles during the beginning of flowering, full flowering and the termination of flowering of camomile anthodia. The total content of the essential oil was highest during the beginning of flowering and lowest during its termination. The proportion of the individual sesquiterpenes in the essential oil underwent changes mostly during the beginning and termination of flowering. The number of secretory canals in the basal and middle anthodial parts increased during the beginning of flowering and the full flowering.     

An H-2 haplotype possibly derived by crossing-over between the (A α A β ) duplex and the E βlocus

The B10.STA62 strain carries the H-2 ^w27 haplotype derived from a wild mouse captured in the vicinity of Ann Arbor, Michigan. Products of two class II loci composing this haplotype, A and A , are serologically, biochemically (by tryptic peptide mapping), and functionally indistinguishable from products controlled by the A ^b and A ^/b genes of the B10.A(5R) strain. In contrast, the polypeptide chain controlled by the third class II locus, E , is different from that controlled by the E ^/b gene. This E ^/w27 chain lacks an antigenic determinant present on the E^b molecule and carries determinants lacking on the E^b molecule, the E ^/b and E ^/w27 peptide maps differ in at least six peptides, and cytotoxic T cells specific for the E ^b chains do not react with B10.STA62 target cells. This great difference between the E ^/b and E ^/w27 chains suggests that the corresponding genes have not been derived from one another by a direct mutational conversion; instead, H-2 ^w27 appears to be a recombinant haplotype derived by crossing-over between the A A duplex and the E locus. This is the first recombinant discovered separating these class II loci.