The chemical-transformation products of 1,6-dibromo-1,6-dideoxygalactitol and 1,2:5,6-dianhydrogalactitol in aqueous solution

After hydrolysis of 1,6-dibromo-1,6-dideoxygalactitol (1) and 1,2:5,6-dianhydrogalactitol (2), 11 compounds were isolated, three of them as tritylated derivatives. Their structures were established on the basis of chemical evidence and, for four compounds, by X-ray diffraction. The main product of the hydrolysis of 1 was 3,6-anhydro-1-bromo-1-deoxy-dl-galactitol; the end-products of the hydrolysis of 2 were 1,5-anhydro-dl-galactitol, 2,5-anhydro-dl-altritol, and galactitol.     

Somatic cell fusion of Trichoderma reesei resulting in new genetic combinations

Summary A selection method has been developed for the isolation of recombinant strains of Trichoderma reesei QM 9414. The method is based on somatic hybridization via anastomosis or protoplast fusion, and on the difference in growth rate of the resulting heterokaryons and synkaryons. The more intensive growth of the synkaryons as due to allelic complementation of adenine-requiring auxotrophic strains mutated in the adenylosuccinate synthetase gene. The synkaryons appeared is energetically growing spots in the heterokaryotic background. Stable diploids could not be isolated, which points to the transient nature of the diploid state in this species.     

Alga consumption of four dominant planktonic crustaceans in Lake Balaton (Hungary)

Between 1981–83 the gut contents ofDaphnia galeata, D. cucullata, Eudiaptomus gracilis, andCyclops vicinus were examined with light and scanning electron microscope to obtain information on the feeding of these species in Lake Balaton. The twoDaphnia species feed mainly on abioseston, and it is assumed that their primary nutrient source was organic matter adsorbed onto the surfaces of the abioseston granules plus bacteria and detritus.E. gracilis feeds on algae, showing a preference for green algae and diatoms.C. vicinus is also a prodigious consumer of algae in Lake Balaton, utilizing the whole size spectrum of phytoplankton. Concerning the trophic relationships between phytoplankton and zooplankton in Lake Balaton, that between diatoms and bothE. gracilis andC. vicinus is the most conspicouos. Convincing evidence for an extensive utilization of blue-green algae was not found. Though there is no firm evidence yet, it is likely that theDaphnia are dependent on organic matter adsorbed on the abioseston.     

Immunogold localization of photosynthetic fructose-1,6-bisphosphatase in pea leaf tissue

An enriched IgG serum fraction obtained from rabbits immunized against pea chloroplast fructose-1,6-bisphosphatase (FBPase) was used, coupled to colloidal gold (15 nanometer particles) goat anti-rabbit IgG, to analyze by electron microscopy the location of photosynthetic FBPase in pea (Pisum sativum L.) leaf ultrathin sections. In accordance with earlier biochemical studies on distribution of FBPase activity, the enzyme was visualized both in the stromal space and bound to the chloroplast membranes. Some gold particles also appear in the cytoplasm, which can be related to the presence in the cytosol of a high molecular weight precursor of this nuclear coded enzyme.     

Photoreactions of bacteriorhodopsin at acid pH.

It has been known that bacteriorhodopsin, the retinal protein in purple membrane which functions as a light-driven proton pump, undergoes reversible spectroscopic changes at acid pH. The absorption spectra of various bacteriorhodopsin species were estimated from measured spectra of the mixtures that form at low pH, in the presence of sulfate and chloride. The dependency of these on pH and the concentration of Cl- fit a model in which progressive protonation of purple membrane produces "blue membrane", which will bind, with increasing affinity as the pH is lowered, chloride ions to produce "acid purple membrane." Transient spectroscopy with a multichannel analyzer identified the intermediates of the photocycles of these altered pigments, and described their kinetics. Blue membrane produced red-shifted KL-like and L-like products, but no other photointermediates, consistent with earlier suggestions. Unlike others, however, we found that acid purple membrane exhibited a very different photocycle: its first detected intermediate was not like KL in that it was much more red-shifted, and the only other intermediate detectable resembled the O species of the bacteriorhodopsin photocycle. An M-like intermediate, with a deprotonated Schiff base, was not found in either of these photocycles. There are remarkable similarities between the photoreactions of the acid forms of bacteriorhodopsin and the chloride transport system halorhodopsin, where the Schiff base deprotonation seems to be prevented by lack of suitable aspartate residues, rather than by low pH.     

Stirred fluidised-bed reactor developed for low-density biocatalyst supports

Summary A new type of multistage fluidised-bed reactor was constructed to avoid the fluidisation irregularities by slow stirring of the bed. Aminoacylase immobilized on a polyacrylamide type bead polymer was used as biocatalyst for resolution of racemic amino acids. The efficiency was considerably higher than that of a traditional packed-bed reactor.     

Lipid Saturation Induced Microviscosity Increase Has No Effect on the Reducibility of Flash-Oxidized Cytochrome f in Pea Thylakoids

Homogeneous catalytic hydrogenation was used to modify the level of fatty acid unsaturation of thylakoid membranes in the pea chloroplast. Fluidity alteration has been monitored simultaneously using the spin-label probe, 16-doxyl stearate. Even in the case of 30% hydrogenation, no change in the reduction rate of flash-oxidized cytochrome f was observed, in contrast to the fact that the same decrease in the double-bond content of the thylakoid membrane resulted in a pronounced inhibition in the full-chain electron transport. We conclude that the rate of lateral diffusion of reduced plastoquinone is unaffected by the lowering of the fluidity of the thylakoid lipid matrix.     

Short-term effects of carbon dioxide on carnation callus cell respiration

The addition of potassium bicarbonate to the electrode cuvette immediately stimulated the rate of dark O₂ uptake of photomixotrophic and heterotrophic carnation (Dianthus caryophyllus L.) callus, of Elodea canadensis (Michx) leaves, and of other plant tissues. This phenomenon occurred at pH values lower than 7.2 to 7.8, and the stimulation depended on the concentration of gaseous CO₂ in the solution. These stimulatory responses lasted several minutes and then decreased, but additional bicarbonate or gaseous CO₂ again stimulated respiration, suggesting a reversible effect. Carbonic anhydrase in the solution increased the stimulatory effect of potassium bicarbonate. The CO₂/bicarbonate dependent stimulation of respiration did not occur in animal tissues such as rat diaphragm and isolated hepatocytes, and was inhibited by salicylhydroxamic acid in carnation callus cells and E. canadensis leaves. This suggested that the alternative oxidase was engaged during the stimulation in plant tissues. The cytochrome pathway was severely inhibited by CO₂/bicarbonate either in the absence or in the presence of the uncoupler carbonylcyanide m-chlorophenyl hydrazone. The activity of cytochrome c oxidase of callus tissue homogenates was also inhibited by CO₂/bicarbonate. The results suggested that high carbon dioxide levels (mainly free CO₂) partially inhibited the cytochrome pathway (apparently at the oxidase level), and this block in electron transport elicited a large transient engagement of the alternative oxidase when present uninhibited.     

Resolution of a missense mutant in human genomic DNA by denaturing gradient gel electrophoresis and direct sequencing using in vitro DNA amplification: HPRT Munich.

The combination of denaturing gradient gel electrophoresis (DGGE) and in vitro DNA amplification has allowed us to (1) localize a DNA mutation to a given 100-bp region of the human genome and (2) rapidly sequence the DNA without cloning. DGGE showed that a mutation had occurred, but the technique revealed little about the nature or position of that mutation. The region of the genome containing the mutation was amplified by the polymerase chain-reaction technique, providing DNA of sufficient quality and quantity for direct sequencing. Amplification was performed with a 32P end-labeled primer that allowed direct Maxam-Gilbert sequencing of the amplified product without cloning. HPRTMunich was found to contain a single-base-pair substitution, a C-to-A transversion at base-pair position 397. We report the generation of a 169-bp, wild-type DNA probe that encompasses most of exon 3 of the human hypoxanthine guanine phosphoribosyltransferase (HPRT) gene and contains a low-temperature melting domain of approximately 100 bp. HPRTMunich, an HPRT mutant isolated from a patient with gout, has a single amino acid substitution; the corresponding DNA sequence alteration must lie within the low-temperature melting domain of exon 3. We report the separation of HPRTMunich from the wild-type sequence using DGGE. In addition to base-pair substitutions, DGGE is also sensitive to the methylation state of the molecule. The cDNA for HPRT was cloned into a vector and propagated in Escherichia coli dam+ and dam- strains; thus, methylated and unmethylated HPRT cDNA was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)