An electrophoretic karyotype for Schizosaccharomyces pombe by pulsed field gel electrophoresis.

The three chromosomal DNAs of S. pombe have been fractionated by pulsed field gel electrophoresis. The resulting molecular karyotype will greatly speed gene mapping in this organism, and it indicates that the separation range of the technique extends to DNA molecules as large as 9,000,000 base pairs.     

Simultaneous butyrate oxidation by Syntrophomonas wolfei and catalytic olefin reduction in absence of interspecies hydrogen transfer

Methanogenesis by a Syntrophomonas wolfei/ Methanospirillum hungatei coculture was inhibited in presence of ethylene and the hydrogenation catalyst Pd-BaSO₄. However, butyrate oxidation by S. wolfei continued and ethylene was reduced to ethane. Per mol of butyrate oxidized, 2.4 mol acetate was produced and 0.8 mol ethylene was reduced. Acetylene, propylene and butene were less effective as H₂ acceptors than ethylene, and addition of bromoethanesulfonic acid was necessary to inhibit methanogenesis in the presence of the two longer-chain olefins. Other hydrogenation catalysts were less effective in the order Pd-charcoal < PE-asbestos < Pd-PEI beads < Pt-Al₂O₃, Pd-CaCO₃. Optimal ethylene hydrogenation was achieved with still incubation in presence of 7.2 mg Pd-BaSO₄ and 0.7 g sand per ml medium. The higher catabolic rate of S. wolfei in presence of the methanogen indicated that the biological H₂ removal mechanism was more efficient than the catalytic olefin reduction.Abbreviations BES bromoethane sulfonic acid - VFA volatile fatty acid     

Morphological correlates of serotonin-neuropeptide Y interactions in the rat suprachiasmatic nucleus: Combined radioautographic and immunocytochemical data

Summary The morphological substrate of putative serotonin (5-HT)/neuropeptide Y (NPY) interactions in thé suprachiasmatic nucleus (SCN) was investigated by combined radioautography and immunocytochemistry after intraventricular administration of (³H)5-HT in the rat. In the ventral portion of the SCN, the distribution of (³H)5-HT uptake sites overlapped closely the NPY-immunoreactive terminals. Previous investigations have shown that the dense 5-HT and NPY innervations of the SCN originate in different structures, i.e., the midbrain raphe nuclei and the ventral lateral geniculate nucleus, respectively. Accordingly, in the present study, destruction of 5-HT afferents by 5,7-dihydroxytryptamine was not found to induce any modification in NPY staining and, in ultrastructural immuno-radioautographic preparations, two distinct pools of axonal varicosities could be identified. Both 5-HT and NPY terminals established morphologically defined synaptic junctions, sometimes on the same neuronal target. Some cases of direct axo-axonic appositions between the two types of terminals were also encountered. These data constitute additional criteria for characterizing the cytological basis of the multiple transmitter interactions presumably involved in the function of the SCN as a central regulator of circadian biological rhythms.     

The periplasmic nitrate reductase of Rhodobacter capsulatus; purification,characterisation and distinction from a single reductase for trimethylamine-N-oxide,dimethylsulphoxide and chlorate

The periplasmic dissimilatory nitrate reductase from Rhodobacter capsulatus N22DNAR⁺ has been purified. It comprises a single type of polypeptide chain with subunit molecular weight 90,000 and does not contain heme. Chlorate is not an alternative substrate. A molybdenum cofactor, of the pterin type found in both nitrate reductases and molybdoenzymes from various sources, is present in nitrate reductase from R. capsulatus at an approximate stoichiometry of 1 molecule per polypeptide chain. This is the first report of the occurrence of the cofactor in a periplasmic enzyme. Trimethylamine-N-oxide reductase activity was fractionated by ion exchange chromatography of periplasmic proteins. The fractionated material was active towards dimethylsulphoxide, chlorate and methionine sulphoxide, but not nitrate. A catalytic polypeptide of molecular weight 46,000 was identified by staining for trimethylamine-N-oxide reductase activity after polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The same polypeptide also stained for dimethylsulphoxide reductase activity which indicates that trimethylamine-N-oxide and dimethylsulphoxide share a common reductase.Abbreviations DMSO dimethylsulphoxide - LDS lithium dodecyl sulphate - MVH reduced methylviologen - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecyl sulphate - TMAO trimethylamine-N-oxide     

Ultrastructural and functional changes in the myocardium and coronary vessels after massive blood loss

The ultrastructure of cardiomyocytes and circulatory bed has been compared to transmembrane cAMP-dependent Ca2+ transport in experiments on the hearts of 14 dogs immediately after massive blood loss. The results an hour after non-compensatory hemorrhage have shown extra- and intracellular myocardial edema, central destruction of sarcomers, steep increase in the volume of agranular sarcomplasmic reticulum and T-system, different degree of damage of other organoids, and also disturbances in the ultrastructure of venous capillary and postcapillary section. The biochemical techniques used have shown a decrease in Ca2+ transporting ability of sarcolemma due to its AMP-dependent regulation of cardiomyocytes. Excessive Ca2+ storage in cytosole promoted the appearance of "constriction bands" in myofibrils.     

Reaction of fluorescein bimercuric acetate with a molybdenum center of xanthine oxidase from milk

Inhibition of milk xanthine oxidase by fluorescein bimercuriacetate (FMA) allows for the classification of S-containing groups according to their localization and role in the catalytic activity of the enzyme. The enzyme (E) complexes with FMA (E--FMA I and E--FMA II) differing in their activity, stoichiometry and spectral properties were studied at various experimental conditions, reaction time and FMA concentrations. The enzyme molecule contains 5 groups that are reactive towards FMA (E--FMA I) and are localized outside the active center. That these groups have no concern with activity and are subjected to modification irrespective of whether or not the xanthine oxidase molecule has an intact Mo-center. The formation of an inactive E--FMA II complex is associated with an additional (in comparison with E--FMA I) binding of two FMA molecules per molecule of the active enzyme. The stoichiometry of the E--FMA II complex was determined by the X-ray fluorescent method from the amount of the Hg in enzyme. A kinetic scheme of xanthine oxidase inhibition by FMA is proposed, according to which the inhibition is a result of modification of two groups in the enzyme active center, of which only one is essential for the enzyme activity. This scheme also postulates the role of reversible E--FMA complexes in the course of irreversible inhibition. Xanthine oxidase is protected against FMA by the substrate (xanthine), competitive inhibitors (azaxanthine and allopurinol) and acceptor (2,6-dichlorophenolindophenol), i. e., compounds which interact with the Mo-center of the enzyme. The EPR spectra of the dithionite-reduced E--FMA II complex were found to contain a "slow" signal, Mo(V), typical of the Mo-center devoid of labile sulphur. It was assumed that the essential group interacting with FMA in the active center of xanthine oxidase as a terminal sulphur which is a component of the coordination region of Mo.     

Presence of nucleosomes inPenicillium chrysogenum

We have studied the chromatin structure ofPenicillium chrysogenum. This fungus presents the typical nucleosomal repeat and the core DNA size characteristic of all the eukaryotes. The repeat length (about 180 base pairs) is in the range of those obtained for most fungi (160–180 base pairs) and shorter than in higher eukaryotes. Knowledge aboutP. chrysogenum chromatin structure opens the way to the study of the mechanisms of genetic regulation in this filamentous fungus.     

Isolation ofAcholeplasma oculi from human amniotic fluid in early pregnancy

Acholeplasmas have been isolated from a variety of animals, insects, and plants, but onlyAcholeplasma laidlawii has previously been found in humans. We have isolatedAcholeplasma oculi in pure culture from the amniotic fluid of a woman at 19 weeks of gestation. The organism was positively identified by growth inhibition, epi-immunofluorescence, and arbutin hydrolysis. Demonstration of organisms directly in amniotic fluid by DNA fluorochrome and immunofluorescence staining provided additional evidence that the isolate was genuine and not a medium contaminant. The remainder of the pregnancy was unremarkable, and a full-term male infant was delivered without complications. Even though there is some evidence possibly associatingA. oculi with various diseases in livestock, the prevalence and significance ofA. oculi in humans has not been determined.