Identification of aromatic dihydroxy acids in biological fluids

3,5-Dihydroxyphenylpropionic acid, 3,5-dihydroxycinnamic acid and 2,3-dihydroxycinnamic acid were detected for the first time to be components of human urine. In the course of this investigation all constitutional isomers of dihydroxy-benzoic, -phenylpropionic, -phenylacetic and -cinnamic acid were synthesized. Mass spectra and retention indices of methyl and trimethylsilyl (TMS) derivatives were determined. In contrast to many other substituted aromatic compounds the mass spectra of methyl and TMS derivatives of dihydroxy aromatic acids often allow a firm distinction to be made between constitutional isomers: TMS derivatives of aromatic acids containing two hydroxy groups located in the ortho position to each other can be recognized by ions resulting from a primary cleavage reaction mainly in the side chain or ester group, followed by loss of tetramethylsilane. In methyl derivatives of 1,2,3-trisubstituted isomers, methoxy groups are lost much more easily from the ions corresponding to the benzylic cleavage than in other isomers. Methyl derivatives of dihydroxycinnamic acids containing at least one methoxy group in the ortho position to the side chain are characterized by a fragmentation reaction, corresponding to the loss of dimethyl ether. TMS and methyl derivatives of 3,5-dihydroxy aromatic acids show unique structure-specific fragmentation reactions.     

Untersuchungen über die lichtabhängige Carotinoidsynthese

Summary In conidia-free submerged cultures of Neurospora crassa the various steps of light-dependend carotenoid synthesis were studied. The mycelium produces small amounts of pigments even in the dark. The data obtained are in part in good agreement with earlier results of Zalokar and show that the light-induced pigment production starts after a lag-period of 40 min and is finished after 6–8 hours; the photoreaction is saturated by relatively small dosages. In contrast to Zalokar's results we found that for photoinduction the reciprocity law holds true. The photoreaction is saturated by a certain amount of light independently of the light-intensity. Actidion (Cycloheximide) inhibits carotenoid synthesis completely when added before or up to 10 min after the onset of illumination, whereas addition 60 min after illumination already has no effect. Comparison with the results obtained with Fusarium shows that the reaction mechanism is very similar in both organisms, though the various steps seem to proceed faster in Neurospora.

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Herrn Prof. Dr. L. Brauner in Verehrung und Dankbarkeit zum 70. Geburtstag gewidmet.     

The effects of host distributional patterns on parasite transmission: Aedes aegypti larvae and Plagiorchis noblei Cercariae

The effects of distributional patterns of the host on the acquisition of Plagiorchis noblei cercariae by Aedes aegypti larvae were determined. Mosquito larvae that were allowed to disperse were more susceptible to infection than confined larvae. Because these mosquito larvae are known to aggregate in light and disperse in darkness, they are more likely to acquire P. noblei infections at night. The timing of cercarial emergence in relation to the distributional patterns of the mosquito host is discussed.     

Initial steps of sophoroselipid biosynthesis by Candida bombicola ATCC 22214 grown on glucose

 Candida bombicola ATCC 22214 produces the glycolipid sophoroselipid when cultivated on a medium with glucose as the sole carbon source. Under phosphate-limiting conditions the product yield rises from 0.033 to 0.143 and the specific product formation rate rises from 0.004 h^-1 to 0.007 h^-1. Enhanced sophoroselipid synthesis is initiated by the decline of the specific activities of NAD- and NADP-dependent isocitrate dehydrogenase (EC 1.1.1.41 and 1.1.1.42) to 2% and 0% of the initial activities respectively. Constantly high specific activity of citrate synthase (EC 4.1.3.7) causes an accumulation of isocitrate and citrate in the mitochondria. Both acids are transported into the cytosol where citrate is cleaved by ATP: citrate lyase (EC 4.1.3.8) giving rise to acetyl-CoA, the precursor of fatty acid synthesis. The ATP: citrate lyase is unaffected by different energy charges; the apparent K _m values for coenzyme A, ATP and citrate are 23 μM, 250 μM and 256 μM respectively. NADPH for fatty acid synthesis might be generated by further metabolism of oxaloacetate, the other product of the citrate-cleaving reaction, by oxidation of the isocitrate by the cytosolic NADP-dependent isocitrate dehydrogenase or via the hexose monophosphate shunt. A possible explanation for sophoroselipid formation during exponential growth is given. Received: 7 November 1995/Received revision: 19 March 1996/Accepted: 25 March 1996     

The C-terminal domain of eukaryotic protein synthesis initiation factor (eIF) 4G is sufficient to support cap-independent translation in the absence of eIF4E.

The foot and mouth disease virus, a picornavirus, encodes two forms of a cysteine proteinase (leader or L protease) that bisects the EIF4G polypeptide of the initiation factor complex eIF4F into N-terminal (Nt) and C-terminal (Ct) domains. Previously we showed that, although in vitro cleavage of the translation initiation factor, eIF4G, with L protease decreases cap-dependent translation, the cleavage products themselves may directly promote cap-dependent protein synthesis. We now demonstrate that translation of uncapped mRNAs normally exhibits a strong requirement for eIF4F. However, this dependence is abolished when eIF4G is cleaved, with the Ct domain capable of supporting translation in the absence of the Nt domain. In contrast, the efficient translation of the second cistron of bicistronic mRNAs, directed by two distinct Internal Ribosome Entry Segments (IRES), exhibits no requirement for eIF4E but is dependent upon either intact eIF4G or the Ct domain. These results demonstrate that: (i) the apparent requirement for eIF4F for internal initiation on IRES-driven mRNAs can be fulfilled by the Ct proteolytic cleavage product; (ii) when eIF4G is cleaved, the Ct domain can also support cap-independent translation of cellular mRNAs not possessing an IRES element, in the absence of eIF4E; and (iii) when eIF4G is intact, translation of cellular mRNAs, whether capped or uncapped, is strictly dependent upon eIF4E. These data complement recent work in other laboratories defining the binding sites for other initiation factors on the eIF4G molecule.     

Slow cortical potential biofeedback and the startle reflex

The negativity of slow cortical potentials (SCP) of the surface EEG is a measure of brain excitability, correlating with motor and cognitive preparation. Selfcontrol of SCP positivity has been shown to reduce seizure activity. Following SCP biofeedback from a central EEG electrode position, subjects gained bidirectional control over their SCP. The current study used a modified feedback methodology, and found a positive relationship between negativity and magnitude of EMG startle response (a measure of cortical and subcortical arousal, particularly aversive response disposition). Greater success in SCP differentiation was associated with self-report of less relaxation during negativity training.This research was supported by the Deutsche Forschungsgemeinschaft under grant No. SFB 307.     

Isolation and chemical characterization of lipopolysaccharides from four Mycoplana species (M. bullata,M. segnis,M. ramosa and M. dimorpha)

Lipopolysaccharides (LPS), isolated from four Mycoplana species, i.e. the type strains of M. bullata, M. segnis, M. ramosa and M. dimorpha, were characterized onto their chemical composition and their respective lipid A-types. Those of M. bullata and M. segnis showed on DOC-PAGE an R-type character and had lipid A's of the Lipid A_DAG-type which exclusively contained 2,3-diamino-2,3-dideoxy-d-glucose as lipid A sugar. LPS's of M. ramosa and M. dimorpha showed, although only weakly expressed, ladder-like patterns on DOC-PAGE indicating some S-type LPS's and lipid A of the d-glucosamine type (Lipid A_GlcN). M. bullata LPS contained mannose and glucose in major amounts and additionally l-glycero-d-mannoheptose, whereas M. segnis LPS was composed of rhamnose, mannose and glucose together with both, d-glycero-d-manno- and l-glycero-d-manno-heptoses in a molar ratio of 1:2. All LPS's contained 2-keto-3-deoxy-octonic acid (Kdo), phosphate and an unidentified acidic component X. In addition to X, M. segnis LPS contained glucuronic and galacturonic acids, whereas M. ramosa LPS contained only galacturonic acid. Acetic acid hydrolysis of the LPS resulted in splitting off lipid A moieties, very rich in 3-hydroxy fatty acids, in particular in 3-OH-12:0 (in Lipid A_DAG), or in 3-OH-14:0 (in Lipid A_GlcN). Analysis of the 3-acyloxyacyl residues revealed major amounts of amide-linked 3-OH(3-OH-13:0)12:0 in lipid A of M. bullata and 3-OH(12:0)12:0 in lipid A of M. segnis. The rare 4-oxo-myristic acid (4-oxo-14:0) was observed only in M. bullata LPS, where it is ester-linked. Amide linked diesters could not be traced in M. ramosa and M. dimorpha. All four lipid A's lacked erster-bound acyloxyacyl residues.Non-standard abbreviations DAG 2,3-diamino-2,3-dideoxy-d-glucose - Kdo 2-keto-3-deoxy-octonate - LPS lipopolysaccharide - PITC phenyl isothiocyanate - NANA N-acetyl neuraminic acid     

Operational Sex Ratio and Individual Mating Frequencies in Two Bushcricket Species (Orthoptera,Tettigonioidea, Poecilimon)

During mating the male bushericket transfers a large spermatophore which is consumed by the female after copulation. Such a ‘nuptial gift' is likely to have strong effects on the mating frequency of both males and females and thus on the operational sex ratio (OSR): For the male a longer time period will be required in which he is prevented from further matings. For the female consumption may be advantageous increasing interest in matings. To quantify these effects field studies were carried out on two species of the genus Poecilimon. Both species differed widely in the mean number of matings observed per day (19% of all females in P. veluchianus compaied to 42% in P. affinis; Fig. 2) and thus in the distribution of female mating intervals (P. veluchianus 2 days, P. affinis 1 day (modes); Fig. 3). Separate experiments on the minimum male mating interval and the spermatophore weight also revealed distinct differences: the mean spermatophore weight was 26% of the male body weight in P. veluchianus and 15% in P. affinis (Fig. 6). Accordingly the refractory period was longer in P. veluchianus; 3 days after a previous mating nearh all males were ready to remate, compared to 2 days in P. affinis (Fig. 5). These differences, however, compensated one another in that the amount of spermatophylax material transferred per day was very similar in both species in relation to female body weight. Using data on female mating frequency per day and male remating ability, an upper estimate for the OSR was calculated. A lower limit for the OSR was given taking into account the most frequent female mating interval (big. 7). In both species the OSR remained relatively constant for large parts of the season. The medians (upper/lower estimate for the ratio males to females ready to mate: 2.95/1.19 in P. veluchianus; 2.22 0.88 in P. affinis) were very low, comparable to that in explosive breeding frog species. Thus in the bushcricket mating system, females may be able to demand large male mating efforts so that the operational sex ratio can come close to unity.