An indirect method for quantitation of cellular zinc content of timm-stained cerebellar samples by energy dispersive X-ray microanalysis

Summary The absolute concentration of zinc in the Purkinje cells of the rat cerebellum was determined by means of energy dispersive X-ray microanalysis (EDAX). Gelatine blocks with known zinc concentrations were stained by Timm's sulphide-silver method, and their silver concentrations were measured by EDAX. A linear correlation was found between the zinc and silver concentrations and this linear function was used as a quantitative calibration for evaluation of sulphide-silver staining, after perfusion with sodium-sulphide solution, fixation with glutaraldehyde, cryostat sectioning and staining of cerebellar samples in Timm's reagent.     

Enzyme patterns during substrate shifts between phenol,acetate and glucose in continuous culture of Trichosporon cutaneum

Summary The soil yeast Trichosporon cutaneum was grown in continuous culture on phenol, acetate or glucose as sole carbon source. The activities of enzymes participating in the tricarboxylic acid cycle, glyoxylate cycle, 3-oxoadipate pathway, pentose phosphate pathway and glycolysis were determined in situ during shifts of carbon sources. Cells grown on phenol or glucose contained basal activity of the glyoxylate-cycle-specific isocitrate lyase. The derepression of the glyoxylate cycle enzymes was partly hindered in the presence of phenol but not in the presence of low levels of glucose. Phenol and glucose caused repression of isocitrate lyase. In the presence of either phenol or glucose, acetate accumulation in the medium increased. However, part of the supplied acetate was utilized simultaneously with phenol or glucose, the utilization rate of either carbon source being reduced in the presence of the other carbon source. Acetate caused repression but not inactivation of the phenol-degrading enzymes, phenol hydroxylase and catechol 1,2-dioxygenase. The simultaneous utilization of phenol and other carbon sources in continuous culture as well as the observed repression-derepression patterns of the involved enzymes reveal T. cutaneum to be an organism of interest for possible use in decontamination processes. Offprint requests to: H. Y. Neujahr Offprint requests to: H. Y. Neujahr     

A possible pathomechanism of the idiopathic cold contact urticaria.

Urtica is characterized by an erythematous wheal surrounded by a flare and is frequently caused by physical agents (e.g. cold). The exact mechanism and mediators involved in the mechanism of physical urticaria are not known. This study of the role of the neurogenic factors in cold urticaria showed, that local capsaicin treatment (desensitization) of the skin in patients with cold urticaria resulted in the abolition of whealing in response to cold. This result suggests that C-fibers might play an important role in the pathomechanism of idiopathic contact cold urticaria.     

Stability of solvent formation in Clostridium acetobutylicum during repeated subculturing

Summary Clostridium acetobutylicum ATCC 824 was submitted to repeated subculturing at 24-hour intervals for 218 days. The organism retained its ability to form solvents, although the fermentation slowly became increasingly acidogenic during the first 200 days. Except for the initial spore inoculum, the cultures were not subjected to heat shocking between the serial transfers. When the inoculum volume was doubled from 3.3% to 6.7% after 200 days of subculturing, the product formation pattern quickly shifted back from acids to primarily butanol. Acetone production also resumed after being undetectable for more than 50 days. The relative formation of acetate and ethanol remained nearly constant throughout the experiments, while the formation of butyrate mirrored that of butanol.     

Isolation and characterization of a 23 kDa protein essential for photosynthetic oxygen evolution

A 23 kDa protein has recently been demonstrated to participate in photosynthetic oxygen evolution by reconstitution experiments on inside-out thylakoid vesicles (Åkerlund H-E, Jansson C and Andersson B (1982) Biochim Biophys Acta 681:1–10). Here we describe the isolation of the 23 kDa protein from a spinach chloroplast extract using ion-exchange chromatography. The protein was obtained in a yield of 25% and with less than 1% of contaminating proteins. The ability of the protein to stimulate oxygen evolution in inside-out thylakoids was preserved throughout the various fractionation steps. The isolated protein was highly water soluble and appeared as a monomer. Its isoelectric point was at pH=7.3. The amino acid composition showed a high content of polar amino acids, resulting in a polarity index of 49%. The isolated protein lacked metals and other prosthetic groups. Its function as a catalytic or regulating subunit in the oxygen evolving complex is discussed.     

Relative positions of some epitopes on carcinoembryonic antigen

Summary To investigate whether anti-(carcinoembryonic antigen) monoclonal antibodies (mAb) react with single or repeated epitopes, sandwich radioimmunoassays in homologous and heterologous combinations were performed. Four mAb (I-27, I-47, II-17 and to some degree II-16) gave homologous binding while two mAb (I-38S1 and II-10) did not. Taken together with previous immunoprecipitation studies we conclude that all these mAb except II-10 react with repeated epitopes. The relative positions of the epitopes recognized by these mAb and of three additional mAb (II-6, II-7 and CB-CEA-1) were investigated using a plate antibody competition test with enzyme-labelled carcinoembryonic antigen (CEA). mAb I-38S1, II-6, II-7, II-10, II-16 and CB-CEA-1 were mutually cross-reactive, and were classified as belonging to one epitope group. mAb I-27 and I-47 fell outside this group and did not interfere with the binding of CEA conjugate to mAb II-17 either. They therefore represent a second epitope group. mAb II-17 showed no interference with the binding of CEA to any of the other mAb and must therefore represent a third epitope group. The slopes of the plate antibody competition curves were used for calculation of a correlation matrix, which in turn was used to depict the relative positions of the epitopes recognized by the mAb in the large group.     

Predation on artificial,solitary and aggregated wader nests on farmland

Predation rates on artificial wader nests, solitary curlew (Numenius arquata) and lapwing (Vanellus vanellus) nests and lapwing nests in colonies were studied on a farmland site in central Sweden. Predation rates were highest on artificial wader nests, intermediate on solitary curlew and lapwing nests and lowest on lapwing nests in colonies, probably because of active defence of adults at real nests and/or because of selection of nest sites with lower predation risk by breeding birds. A comparison of nests close to (50 m) and far away from (200 m) forest edges revealed no increased predation risk close to edges for any of the studied nest types. Predation risk changed during the season for artificial nests (highest in the middle of May), while predation rates on lapwing and curlew nests were more stable. Artificial nests seem to be inappropriate for measuring actual predation rates and temporal differences in predation rates on real nests, but they might be suitable for use as an index of spatial differences.