Zeitschrift fur Naturforschung. Section C, Biosciences最新文献

Total lipids from liver, head, skin and muscle of Bogue were separately isolated and their composition was investigated by a combination of analytical determinations, and column and thin layer chromatography. The major components of the neutral lipid fractions from all tissues studied were triglycerides, followed by cholesterol. The triglyceride fraction of skin and head contains significant amounts of glyceryl ether analogs. Low contents of free fatty alcohols were also identified, decreasing in the order: head, muscle, skin and liver. The major components of all phospholipid fractions was phosphatidylcholine (viz. 36-59% of total phospholipids) followed by phosphatidylethanolamine (viz. 23-34% of total phospholipids). Low amounts of sphingomyelin and phosphatidylserine were also identified in all cases. All the tissues studied were found to contain plasmalogens, as well as glyceryl ether analogs in both, the depot fats and the phospholipid fractions.

The possible interaction of DDT with the lipids dimyristoyl lecithin (DML), dipalmitoylphosphatidylethanolamine (DPPE) and tripalmitin (TP) was studied. The work was carried out on oriented films and crystalline powders of DDT-lipid mixtures at different molar ratios by X-ray diffraction techniques. The diagrams showed only the patterns of pure DDT and that of the corresponding lipid. It is concluded that new phases were not formed and, therefore, no interactions occurred.

The decline of the transport ratio of the sarcoplasmic calcium pump observed in a recent study (A. Gafni and P. D. Boyer, Proc. Natl. Acad. Sci. USA 82, 89-101 [1985] ) results from the retardation of calcium oxalate precipitation at low calcium/protein ratios. The prevailing high internal calcium level supports a rapid calcium backflux and a compensatory ATP hydrolysis during net calcium uptake which reduces the transport ratio. Yet, the determined calcium backflux does not fully account for the decline of the transport ratio. A supposed modulation of the stoichiometry of the pump by external calcium (0.1 microM) is at variance with results of previous studies showing a constant transport ratio of two in the same calcium concentration range.

A high yielding production of the trichothecene mycotoxin 3-acetyldeoxynivalenol (3-AcDON) in cultures of Fusarium culmorum is described. By supplying [14C]acetate, 14C-labelled 3-AcDON suitable for further metabolic studies has been obtained. The pattern of labelling has been ascertained by using 13C-labelled acetate precursors, and is in line with established biosynthetic data. A second trichothecene produced in significant amounts by F. culmorum has been identified as 3 alpha, 15-diacetoxy-7 alpha, 8 alpha-dihydroxy-12, 13-epoxytrichothec-9-ene (7 alpha, 8 alpha-dihydroxycalonectrin).

The kinetics of thermal denaturation of ceruloplasmin in water and in water with different percentage of D2O in the temperature range 25-85 degrees C, following the optical density change of the 610 nm charge transfer band of the protein has been investigated. A temperature Tt approximately equal to 65 degrees C above which an irreversible denaturation process of the protein active site takes place has been found. The kinetics of the denaturation process of the protein are fitted by two first order reactions, which have been assigned to a different thermal denaturation behaviour of the two Cu2+ type I sites existing in the protein. Addition of D2O to the protein solution affects the two kinetics in a different way, i.e. the rate of one of them is increased whilst that of the other is decreased. The different effect of D2O on the kinetics of disruption of the two copper sites is discussed in terms of different location and degree of hydrophobicity of the two Cu2+ type I sites.

The labeling of immunocomplexes for scanning electron microscopy (SEM) is a fairly new technique, and the various procedures, that have been proposed, have not yet been compared. Such comparative evaluation was performed with Candida protease as a target antigen. This secretory enzyme of the opportunistic yeast Candida albicans can be localized on the surface of fungal blastopores and mycelia, both after growth in proteinaceous medium and upon infection of murine peritoneal macrophages. The presence of the protease antigen was confirmed by immunofluorescence and by immunoperoxidase-light microscopy. The decoration of protease - anti protease complexes for SEM was attempted with colloids derived from the immunoperoxidase reaction, by the immunogold technique, and by antibodies linked to beads of synthetic polymers (polystyrene, polymethacrylate, polyacrolein). In addition, inactivated Staphylococcus aureus was used, which binds to antibodies through its protein-A. The high resolution by SEM of surface structures was matched only by the colloid based decoration techniques. All conjugates with beads suffered from inconsistent binding, which did not correspond with the distribution of the surface antigen. The comparatively best result with beads was obtained with polystyrene (Latex). Colloid based techniques in addition allow for critical point drying, which cannot be applied to synthetic beads in the usual manner.

Prosomes are small cytoplasmic RNP complexes. We present evidence that their RNA is a potential and selective inhibitor of viral mRNA translation while translation of normal cellular mRNA e.g. rabbit globin mRNA or HeLa cell mRNA is not affected.

The light-induced proton uptake of rod outer segment disc membranes has been investigated in the absence and presence of G-protein. Proton uptake was measured as the alkalisation of the suspending medium using a pH electrode and/or the indicator dye bromocresol purple. It was found that besides the known proton uptake of photolysed rhodopsin additional uptake of one proton accompanies formation of the complex between rhodopsin and G-protein. No measurable proton uptake was found under conditions of rapid redissociation of the complex indicating an only transient protonation during its lifetime. Proton uptake was the same in washed membranes recombined with G-protein and in ordinarily stacked rod outer segments. The additional proton uptake reported here is not due to enhanced formation of the protonated photoproduct metarhodopsin II.

Phytochemical and microscopial analysis of leaves and stems of various species of Encelia showed a strict correlation between the presence of resin ducts and the accumulation of benzopyrans and benzofurans. Fluorescence microscopy of Encelia farinosa proved unambigously that these compounds are stored exclusively in the resin ducts and the surrounding cells.

The sulfhydryl enzyme malate synthase from baker's yeast was X-irradiated with 6 kGy in air-saturated aqueous solution (enzyme concentration: congruent to 10 mg/ml; volume: 120 microliters), in the absence or presence of the specific scavengers formate, superoxide dismutase, and catalase. After X-irradiation, a small aliquot of the irradiated solutions was tested for enzymic activity while the main portion was investigated by means of small-angle X-ray scattering. Additionally, an unirradiated sample without additives was investigated as a reference. Experiments yielded the following results: X-irradiation in the absence of the mentioned scavengers caused considerable aggregation, fragmentation, and inactivation of the enzyme. The dose Dt37 for total (= repairable + non-repairable) inactivation resulted as 4.4 kGy. The mean radius of gyration was found to be about 13 nm. The mean degree of aggregation was obtained as 5.7, without correction for fragmentation. An estimation based on the thickness factor revealed that about 19% of material might be strongly fragmented. When this amount of fragments was accordingly taken into account, a value of 7.1 was obtained as an upper limit for the mean degree of aggregation. The observed retention of the thickness factor and the finding of two different cross-section factors are in full accord with the two-dimensional aggregation model established previously (Zipper and Durchschlag, Radiat. Environ. Biophys. 18, 99-121 (1980)). The presence of catalytic amounts of superoxide dismutase and/or catalase, in the absence of formate, during X-irradiation reduced both aggregation and inactivation significantly. The presence of formate (10 or 100 mM) during X-irradiation led to a strong decrease of aggregation and inactivation.(ABSTRACT TRUNCATED AT 250 WORDS)