Differences in human chemosensory evoked potentials to olfactory and somatosensory chemical stimuli presented to left and right nostrils

The aim of the present study was to determine whether the recordingof chemosensory evoked potentials (CSEP) in healthy subjects(n = 11) can be helpful in differentiating the olfactory ortrigeminal component possessed by odorants. By recording fromseveral positions on the surface of the skull it was attemptedto ascertain whether different generators are responsible forCSEP associated with the different sensory components of odorants.Birhinal stimulation was used in order to establish an interactionbetween the stimulated side and the stimulated sensory channel.The four substances carbon dioxide, menthol, hydrogen sulphideand vanillin were tested. EEG was recorded from eight positions. The CSEPs' topographical distribution revealed differences inthe location of maximum amplitudes following stimulation withdifferent types of stimulants. Largest amplitudes always appearedat the vertex when trigeminal stimulants (menthol, carbon dioxide)were presented, whereas olfactory substances (vanillin, hydrogensulphide) elicited maximal amplitudes at parietal and centralsites. This suggests that at least two neuronal populationsare involved in the cortical generation of CSEP. Another interestingfinding was that the evoked potentials differed in relationto the stimulated side. Generally, responses to carbon dioxide,menthol and hydrogen sulphide had shorter latencies and smalleramplitudes after stimulation of the left nostril. In contrast,after stimulation with vanillin latencies were shorter and amplitudestended to be smaller after stimulation of the right side. Sincevanillin was the only substance which always evoked pleasantand positive associations, it was assumed that the differencesin CSEP after stimulation of the two nostrils are related tothe different processing of emotional information within thetwo hemispheres.     

A detailed study of the regulation and evolution of the two classes of patatin genes in Solanum tuberosum L.

The class-specific expression of patatin genes was investigated by analysing four new patatin genes. A class I patatin gene from cv. Berolina as well as a class I and two class II patatin genes from the monohaploid cultivar AM 80/5793 were isolated and partially sequenced. Sequence comparison indicates rearrangements as the major source for the generation of diversity between the different members of the classes. The expression of single genes was studied in potato plants transformed with chimaeric genes where the putative patatin promoters were fused to the GUS reporter gene. A detailed histochemical analysis reveals that both class I genes are expressed as the previously described class I patatin gene B33 from cv. Berolina [1], i.e. in the starch-containing cells of potato tubers and in sucrose-induced leaves. The class II gene pgT12 shows the same pattern as the previously described class II gene pgT2 [2], i.e. expression in root tips and in the vascular tissue of tubers, whereas no activity was detectable for pgT4. Thus the expression pattern of both classes of genes seems to be stable at least within or even between different cultivars.     

Mutations in Methanobacterium formicicum conferring resistance to anti-80S ribosome-targeted antibiotics

Summary Mutants of Methanobacterium formicicum resistant to the anti-80S ribosome-targeted inhibitor anisomycin were isolated and characterized. The resistance phenotype is correlated with a mutationally altered 50S ribosomal subunit. Anisomycin resistance in the mutants is accompanied by cross-resistance to other inhibitors of the 80S peptidyl-transferase centre like narciclasine, bruceantin, trichodermin and verrucarin A and by hypersensitivity to sparsomycin. This phenotype is identical to that reported for anisomycin-resistant mutants of yeast; it appears therefore, that the anisomycin interaction sites on the 70S ribosomes from M. formicicum bear the structural features typical of eukaryotic 80S organelles.     

Studies of the GTPase domain of archaebacterial ribosomes

Ribosomes from the methanogens Methanococcus vannielii and Methanobacterium formicicum catalyse uncoupled hydrolysis of GTP in the presence of factor EF-2 from rat liver (but not factor EF-G from Escherichia coli). In this assay, and in poly(U)-dependent protein synthesis, they were sensitive to thiostrepton. In contrast, ribosomes from Sulfolobus solfataricus did not respond to factor EF-2 (or factor EF-G) but possessed endogenous GTPase activity, which was also sensitive to thiostrepton. Ribosomes from the methanogens did not support (p)ppGpp production, but did appear to possess the equivalent of protein L11, which in E. coli is normally required for guanosine polyphosphate synthesis. Protein L11 from E. coli bound well to 23S rRNA from all three archaebacteria (as did thiostrepton) and oligonucleotides protected by the protein were sequenced and compared with rRNA sequences from other sources.     

d-2-hydroxyisocaproate dehydrogenase from Lactobacillus casei

Summary The new enzyme d-2-hydroxyisocaproate dehydrogenase (NAD⁺-dependent) was detected in strains of the genus Lactobacillus and related genera. Straight and branched chain aliphatic as well as aromatic 2-ketocarboxylic acids are stereospecifically reduced to the corresponding d-2-hydroxycarboxylic acids according to the following equation:R-CO-COOH + NADH + H⁺ R-CHOH-COOH + NAD⁺ The enzyme is called d-hydroxyisocaproate dehydrogenase by us because 2-ketoisocaproate is the substrate with the lowest K_M-value. NAD(H) as a cofactor cannot be replaced by NADP(H). Because of its broad substrate specificity we chose the strain Lactobacillus casei ssp. pseudoplantarum (DSM 20 008) for enzyme production and characterization. d-2-hydroxyisocaproate dehydrogenase could be purified 180-fold starting with 500 g of wet cells.The purification procedure involved liquid-liquid extraction with aqueous two-phase systems and ion-exchange chromatography. At this stage the enzyme has a specific activity of 25 U/mg and can be used for technical applications. Further purification up to a homogeneous protein with a specific activity of 110 U/mg can be achieved by chromatography on Amberlite CG 50 at pH 3.5. Properties important for technical application of the d-HicDH were investigated, especially the substrate specificity and the optimum pH- and temperature ranges for activity and stability of the catalist.     

The effects of various nutritional supplements on the growth,migration and differentiation ofxenopus laevis neural crest cells in vitro

Summary This study investigates the nutritional requirements ofXenopus laevis neural crest cells and melanophores developing in vitro. A comparison is made between the growth and differentiation of cells in serum-containing medium and a chemically defined, serum-free medium that we have designed. Our chemically defined medium is more efficient than serum-supplemented medium in promoting proliferation of these cells. Several supplements are required to enhance culture development. These include insulin, α-melanocyte stimulating hormone, somatotropin, luteotrophic hormone, linoleic acid, uridine, and putrescine. In addition, collagen and fibronectin provide the most conductive environment tested for cell migration and adhesion. This work was supported by establishment and major equipment grants from the Alberta Heritage Foundation for Medical Research to N. C. M. Nadine C. Milos is a Heritage Medical Research Scholar of the Alberta Heritage Foundation for Medical Research.     

Properties of cytosolic components activating rat hepatic 5'' [corrected]-deiodination in the presence of NADPH.

The effects of cytosol, NADPH and reduced glutathione (GSH) on the activity of 5'-deiodinase were studied by using washed hepatic microsomes from normal fed rats. Cytosol alone had little stimulatory effect on the activation of microsomal 5'-deiodinase. NADPH had no stimulatory effect on the microsomal 5'-deiodinase unless cytosol was added. 5'-deiodinase activity was greatly enhanced by the simultaneous addition of NADPH and cytosol (P less than 0.001); this was significantly higher than that with either NADPH or cytosol alone (P less than 0.001). GSH was active in stimulating the enzyme activity in the absence of cytosol, but the activity of 5'-deiodinase with 62 microM-NADPH in the presence of cytosol was significantly higher than that with 250 microM-GSH in the presence of the same concentration of cytosol (P less than 0.001). The properties of the cytosolic components essential for the NADPH-dependent activation of microsomal 5'-deiodinase independent of a glutathione/glutathione reductase system were further assessed using Sephadex G-50 column chromatography to yield three cytosolic fractions (A, B and C), wherein A represents pooled fractions near the void volume, B pooled fractions of intermediate Mr (approx. 13 000), and C of low Mr (approx. 300) containing glutathione. In the presence of NADPH (1 mM), the 5'-deiodination rate by hepatic washed microsomes is greatly increased if both A and B are added and is a function of the concentrations of A, B, washed microsomes and NADPH. A is heat-labile, whereas B is heat-stable and non-dialysable. These observations provide the first evidence of an NADPH-dependent cytosolic reductase system not involving glutathione which stimulates microsomal 5'-deiodinase of normal rat liver. The present data are consistent with a deiodination mechanism involving mediation by a reductase (other than glutathione reductase) in fraction A of an NADPH-dependent reduction of a hydrogen acceptor in fraction B, followed by reduction of oxidized microsomal deiodinase by the reduced acceptor (component in fraction B).     

Häufigkeit der Sichttypen in den Erbsystemen Haptoglobin,Gc, saure Erythrocytenphosphatase,Phosphoglucomutase und Adenylatkinase sowie den Erbeigenschaften Gm(1), Gm(2) und Inv(1) bei Deutschen (aus dem Raum Freiburg i. Br. und Köln) und bei Türken

Zusammenfassung Die an 274 Türken und einer mehrfachen Zahl Deutscher (787–5030) durchgeführten Untersuchungen ergaben eine etwas größere Häufigkeit des Gens Hp¹ im Raum Köln und eine größere des Gens Inv¹ im Raum Freiburg i. Br. Bei Türken sind die Allele Hp², Gm¹, P^b und PGM² häufiger, die Allele Hp¹, Gm^1,2, P_a, P_c und PGM¹ seltener als bei Deutschen. Die Frequenzen im Gc- und AK-System stimmen überein.

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Summary There was found a higher frequency of Hp¹ and a lower of Inv¹ in the population of Cologne than in the population of Freiburg. The frequencies of Hp², Gm¹, P^b and PGM² in the Turkish population were found to be higher than those in the German population; the frequencies of Hp¹, Gm^1,2, P^a, P^c and PGM¹ were found to be lower. In the systems Gc and AK the frequencies in the two populations are not significantly different.

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(Direktor: Prof. Dr. R. Haas)

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(Direktor: Prof. Dr. G. Pulverer)

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(Direktor: Prof. Dr. C. Bennholdt-Thomsen)     

Cytosol components from human placenta and rat liver in iodothyronine 5- and 5'-deiodination

Using either human placental microsomal 5-deiodinase as enzyme (5-DI) and thyroxine as substrate or rat liver (RL) microsomal 5'-deiodinase (5'DI) as enzyme and reverse [(3'- or 5'-)-125I]triiodo-L-thyronine ([125I]rT3) as substrate, activation of 5'-DI in the presence of NADPH was observed using either human placental or rat liver cytosolic components, but there was no activation of 5-DI. Both could be activated by DTT, with higher concentrations being required for 5-DI than for 5'-DI. Iopanoic acid, dicumarol, and sodium arsenite inhibited 5'-DI and 5-DI activated by DTT. In the presence of DTT, 1 mM 6-propyl-2-thiouracil had no effect on 5-DI but inhibited 5'DI. Thus, human placental and rat liver cytosolic components are interchangeable in activating hepatic 5'-DI in the presence of NADPH. However, if an endogenous cofactor system involved in the activation of human placental 5-DI exists, it probably differs from the activator of liver 5'-DI.     

The effects of prolonged emersion and submersion by tidal manipulation on marine macrobenthos

Effects of tidal manipulation, resulting in prolonged periods of emersion and submersion or in protracted tidal cycles, on estuarine benthic animals are reviewed.Prolonged submersion periods did not show effects on mortality of most benthic animals tested, with the exception of the crumb-of-bread sponge Halichondrea panicea, which, at low water-flow rates, was covered with a layer of bacteria and subsequently died.Protracted low-water periods of 18 hours during several weeks hardly caused any mortality. However, protracted low-water periods of 30 hours during some weeks or emersion during several days caused a strong increase in mortality, depending on: the duration of emersion, temperature, condition of the animals, species and age. At temperatures below –1 °C and above 24 °C mortality was generally high. Animals with a low glycogen content were more sensitive to emersion than those with a high content. Species with a shell and those that are relatively big were less sensitive than those without a shell or of small size.The reproductive cycle of benthic animals could be delayed or accelerated by both emersion and submersion.