Band 40, Heft 11-12

The triple helical structure of β-ᴅ-1,3 xylan is described. The 0-value is reduced to 3.447 from 4.417 by number of small modifications to the structure including variations in the position of water molecule. The R-value after the refinement is found to be 0.37. The present calculations indicate that water is certainly involved with the structure possibly in a more complicated way as proposed by earlier workers. The present work supports the previous finding of Haleem and Parker that the molecule should be 8% smaller in radius.

Isolation, identification and characterization of a new bile pigment, A-α-hydroxymesobiliverdin, is described.

Seed, sprout and plant oils from soybean (Soja hispida), lupine (Lupinus mutabilis), sunflower (Helianthus annuus) and wheat (Triticum aestivum) were assayed for their tocochromanol content and composition. High-performance liquid chromatography (HPLC) with fluorescence detection was used to determine tocopherols and tocotrienols of laboratory-extracted oils. In general, leaves of lupine, soja, and wheat with a high chlorophyll-a-content also were found to be rich of alpha-tocopherol; roots contained very little or no tocopherol. Contents of gamma-and delta-tocopherol in soja and lupine decreased during germination and growth, whereas the alpha-tocopherol concentration increases significantly. This evidence suggests that non-alpha-to-copherols might be methylated enzymatically to alpha-tocopherol. Tocochromanol pattern of wheat also changes characteristically in an analogous manner during plant development. Germ i­ nation of sunflower seeds also resulted in a conversion of beta-and gamma-tocopherols and in a slight decrease of the predominantly occurring alpha-tocopherol. In relation to the lipid content, the concentration of total tocopherols in oil plants increases significantly during growth. Possible implications for the biosynthesis of tocochromanols are discussed.

The alkaloid patterns during germination and seedling development of Lupinus polyphyllus, L. angustifolius, L. albus, L. pubescens, Cytisus scoparius, Baptisia australis, Spartium junceum and Laburnum anagyroides were studied by capillary glc and EI-MS and CI-MS. The alkaloid contents were relatively high in the seeds and decreased by 20-100% during germination and the early developmental stages. The plants with fully developed leaves were able to synthesize new alkaloids. The decrease of alkaloid concentrations during germination was interpreted in terms of alkaloid turnover and use of the alkaloidal nitrogen for seedling development. The ability of plants to rely on the alkaloidal nitrogen as a nitrogen source could also be shown in lupin cell cultures which could survive and even grow on media which contained sparteine as the sole nitrogen source.

Upon treatment of whole filaments of Anabaena variabilis with a French pressure cell, the activity of sucrose synthase (UDP glucose; D-fructose 2-α-ᴅ-glucosyl transferase, EC 2.4.1.13) was found to be associated almost exclusively with the vegetative cells. The sucrose-cleaving enzyme, an alkaline invertase (β-ᴅ-fructofuranoside fructohydrolase, EC 3.2.1.26), appears to be localized solely within the heterocysts. The implications of these findings, in the light of relevant data from the literature, are summarized in a model representing the physiological differentiation and molecular exchange between vegetative cells and heterocysts.

The crystal structure of ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidine carboxylic acid) isolated from the extremely halophilic phototrophic bacterium Ectothiorhodospira halochloris was determined by X-ray analysis. This novel cyclic amino acid forms zwitterionic molecules with delocalized π-bonding in the N-C-N group of the hydrated pyrimidine ring. The molecules are connected by N-H ...O hydrogen bonds. The excellent solubility of ectoine in water can be explained by its structural features which also account for its function as a compatible solute in halophilic bacteria.

The zwitterionic radicals HO-ĊH-CH(COO - )NH 3 + (4a) and HO-Ċ(CH 3 )-CH(COO - )NH 3 + (4b) are the main species produced upon OH · radical attack in aqueous solutions at pH 3-7 at the amino acids serine, HO-CH 2 -CH(COO - )NH 3 + , or threonine, HO-CH(CH 3 )-CH(COO - )NH 3 + , respectively. Both radicals undergo elimination of NH 4 + ion to form the radicals O=CH-ĊH-COO - (7) or CH 3 -CO-ĊH-COO - (9) respectively. The pK a of the serine-derived cationic radical HO-ĊH-CH(COOH)NH 3 + (3a) (3a ⇄ 4a + H + ), was determined by ESR spectroscopy to 2.2 ± 0.1 at 276 K. From kinetic data the pK a (OH) of radical 4a (4a ⇄ O-ĊH-CH(COO - )NH 3 + (5a) + H + ) was calculated to 7.0. The elimination of NH 3 takes place from the ketyl radical 5a (type-B mechanism), the rate constant was calculated from kinetic data to 2.4 × 10 6 s -1 at 290 K. The half-lives of radicals 4a and 4b were measured by time-resolved conductivity changes upon pulse radiolysis, 170 ± 10 μs for 4a and 26 ± 2 μs for 4b, at 290 K and pH 5.8 . With the threonine derived radicals elimination of NH 3 takes place at the stage of the α-hydroxyalkyl radical 4b (type-A mechanism). In this series the pK a of the product radical CH 3 -CO-ĊH-COOH (8) (8 ⇄ 9 + H + ), was determined by ERS spectroscopy to 2.7 ± 0.1. The reasons for the observed mechanistic differences (type-A versus type-B decay) are discussed. As further examples for a type-B decay some preliminary data on the elimination of HF from the radicals CF 3 -Ċ(OH)-CF 3 and CF3-ĊH-OH have been added.

Normal and starved adult chickens were injected intraperitoneally with ᴅ-galactosamine hydro­ chloride (0.5 g/kg body weight) and 6 h later liver chromatin acid-soluble proteins were isolated. These proteins were resolved by a two-dimensional polyacrylamide gel electrophoresis in the presence of non-ionic detergent, Triton X-100, in the first dimension and anionic detergent, sodium dodecyl sulfate, in the second dimension. Although spotting patterns of acid-soluble chromatin proteins were remarkably similar between normal and starved control birds and those receiving ᴅ-galactosamine, a disappearance of a 24-kDa protein after administration of this agent was found. Moreover, it was shown that this protein was also completely absent in the chicken erythrocyte chromatin which was known to be inactive in RNA synthesis. It seems that the disappearance of the 24-kDa chromatin protein may be associated with inhibiting of transcription in hen liver after ᴅ-galactosamine administration and during hen erythrocyte maturation.

The ʟ-amino acid oxidase from Anacystis nidulans is inhibited by cations as well as anions. The inhibition by cations has been previously described (E. K. Pistorius, Eur. J. Biochem. 135, 217-222 [1983]). We have shown that the order of effectiveness was M 3+ > M2 + > M + , when e.g. La 3+ , Ca 2+ and K + were compared. However, in the concentration range where the monovalent cations inhibited, the inhibition was not entirely due to the cation, but an influence of the anion could also be observed. When monovalent anions were compared as the corresponding sodium salts, the order of effectiveness was SCN - > NO 3 - > CL - , Br - > I - > F - > HCOO - > CH 3 COO - . The inhibition of the ʟ-amino acid oxidase activity by the various salts was strongly influenced by the pH of the reaction mixture. It could be shown that the inhibition by cations increased in the alkaline pH region, while the inhibition by anions increased in the acidic pH region. Our previous results have also shown that a functional relationship might exist between ʟ-amino acid oxidase activity and photosynthetic O 2 evolution (E. K. Pistorius and H. Voss, Eur. J. Biochem. 126, 203-209 [1982]). Since the water-splitting complex of photosystem II is affected by a number of anions, although only Cl - and Br - lead to activation of O 2 evolution, we investigated whether a correlation could be obtained between the anion effect on the ʟ-amino acid oxidase and on photosynthetic O 2 evolution. The results show that those anions which have a higher affinity for the enzyme than CL - or Br - , are especially effective in causing inactivation of the O 2 evolution. Moreover, we show that ʟ-arginine which is a substrate of the ʟ-amino acid oxidase, and Cl - have antagonistic effects on the ʟ-amino acid oxidase reaction and on photosynthetic O 2 evolution. We suggest that this flavoprotein with ʟ-amino acid oxidase activity is modified by Ca 2+ and CL - in such a way that it can now interact with Mn 2+ and catalyze the water-splitting reaction of photosystem II.

A rabbit antiserum was prepared against the purified 33-kDa herbicide-binding protein (HBP) from the alga Bumilleriopsis filiformis. Specificity at 1:10,000 dilution (v/v) of the unpurified serum is detectable in the immunoblotting assay with both the 33-kDa protein from the alga Bumilleriopsis as well as that from Spinacia. Agglutination can be observed with photosystem-II particles only, not with intact thylakoids, indicative of a hidden location of the protein determinants in the membrane. Neither herbicide binding nor electron transport is influenced by the antibody. Apparently, the antigenic site of the HBP for the antibody used here is different from the herbicide-binding region.

An enzyme associated with carthamin formation in Carthamus tinctorius L. (carthamin-synthe-sizing enzyme) was isolated from the soluble protein extract of the hypocotyl tips of the etiolated seedlings and purified up to 157-fold by the procedures applying (NH 4 ) 2 SO 4 fractionation, Ca(CH 3 CO 2 ) 2 precipitation, protamine sulfate treatment, Celite adsorption chromatography, and Sephadex G-100 gel filtration. Results from atomic absorption spectral analysis of the enzyme protein showed to contain K as a major component, and Ca and Mg as minor ones. Fe, Cu, and Mn could not be detected in the preparation. At pH 4.8 in 50.0 mᴍ acetate buffer, the partially purified enzyme reacted positively with a flame-coloured precarthamin to produce a reddish product in open cuvettes with incubation medium. The reaction product was identified as carthamin by examining its colour, chromatographic mobilities in different developing solvents and spectroscopic properties inclusive shifts, often by comparing with those of an authentic specimen. Anaerobic incubation reduced the enzyme activity, while exogenously applied O 2 slightly enhanced the catalytic rate of carthamin formation. The enzyme was sensitive to phosphorus sub­ stances. Among those compounds tested at 1.2 mᴍ level, orthophosphate showed the most striking inhibitory action on the enzyme. Metal ions affected on the enzyme activity by different extents. Mn2+ stimulated the enzyme reaction, while Cu 2+ and Mo 6+ exhibited reverse effects. Fe 2+ , Fe 3+ , Zn 2+ , Mg2+, and Co 2+ were also unfavourable to the enzyme catalyzed carthamin formation. The preparation of the carthamin-synthesizing enzyme showed no activity of polyphenol oxidase or peroxidase under the conditions specifically designed for detecting both enzyme activities.

The flash-induced oscillation of a slowly decaying component of delayed luminescence (half time ~ 42 s) was investigated in spinach chloroplasts for various redox states of the secondary acceptor pool (Q B ). In preilluminated chloroplasts (30 s light followed by 5 min dark) the slow component exhibited a period-4 oscillation as a function of flash number. Upon oxidation of a major part of the Q B pool by dark-adaptation or by ferricyanide treatment of chloroplasts, the period-4 oscillation was converted into a period-2 oscillation, providing direct experimental evi­ dence of the participation of Q B - in the charge recombination reaction. The measured oscillatory patterns could be simulated in model calculations by assuming that the slow component originates from charge recombination of the redox couples S 2 Q B - and S 3 Q B - .

Absorption spectra and room temperature fluorescence variations upon light excitation were studied in etioplasts in which the protochlorophyllide had been reduced to chlorophyllide prior to the experiment. In the presence of 1 mᴍ NADPH, the absorption band was located around 682 nm and the fluorescence variations reflected the occurrence of the chlorophyllide microcycle (reversible phototransformation of chlorophyllide P 682 into chlorophyllide P 678 ), whereas, in the absence of NADPH, the absorption band was located around 676 nm and the fluorescence exhibited only a slow decrease with illumination time. After washing, NADPH-treated etioplasts still exhibited an absorption maximum of 682 nm, which shifted irreversibly to 678 nm upon illumination. Re-addition of only 10 μᴍ NADPH restored the reversibility of the reaction. Plastids were also prepared after a brief illumination of the intact leaves. These plastids contained the P 682 chlorophyllide. In this preparation, essentially the same phenomena were observed as in NADPH-treated etioplasts after washing. Moreover, enzymic oxidation of NADPH resulted in the transformation of P 682 into P 678 in darkness. Addition of the Hill electron acceptors 2,6- dimethylbenzoquinone on FeCN caused an acceleration of the phototransformation of P 682 into P 678 . We interpret these results as being due to the oxidation of NADPH during the phototransformation of P 682 into P 678 . The nature of the electron acceptor and the physiological role of this reaction is discussed.

Propylglyoxal Bis(guanylhydrazone). Ethylglyoxal Bis(guanylhydrazone), Adenosylmethionine Decarboxylase Inhibition. Tumor Cells, Cellular Uptake Propylglyoxal bis(guanylhydrazone) sulfate, a novel analog of the well-known antileukemic drug methylglyoxal bis(guanylhydrazone), has been prepared from 2,2-dibromopentanal, and the compound has been characterized biochemically. Although it is a powerful inhibitor of S-adenosylmethionine decarboxylase, its K i , value (0.2 μᴍ) is considerably higher than that of ethylglyoxal bis(guanylhydrazone) (0.06 μᴍ). The compound is only poorly taken up by tumor cells, and its accumulation is not stimulated by a prior exposure of the tumor cells to di-fluoromethylornithine, a compound that causes polyamine depletion. Thus, the uptake charac­ teristics of the compound are similar to those of ethylglyoxal bis(guanylhydrazone), but in striking contrast to those of methylglyoxal and glyoxal bis(guanylhydrazones). Since the configuration of the double bonds in glyoxal, methylglyoxal and propylglyoxal bis(guanylhydrazones) has been shown to be identical, the different uptake characteristics are probably only due to differences in side chain size and/or hydrophobicity.

The antiproliferative activity of divers ferricenium complexes [Cp 2 Fe] + X - (X - = [CCl 3 COO] - · CCl 3 COOH (I); X - = [CCl 3 COO] - · 2 CCl 3 COOH (II); X - = ½ [Cl 3 FeOFeCl 3 ] 2- (III); X - = [FeCl 4 ] - (IV); X = [2 ,4, 6-(NO 2 ) 3 C 6 H 2 O] - (V)) was investigated against solid, subcutaneously growing Ehrlich ascites tumor (EAT) in vivo as well as against EAT cells cultivated in vitro as permanent suspension culture. In vivo, triple intraperitoneal injections of the complexes II (3 × 200 mg/kg), III (3 × 100, 140, 180 mg/kg) or IV (3 × 160 mg/kg) markedly suppressed tumor development thus that the sizes of treated tumors were reduced to 42-48% related to control tumors (100%); these results point to the systemic character of the antitumor action by ferricenium complexes in vivo. In vitro, all ferricenium complexes inhibited cellular proliferation to an equal extent; application of 10 -5 ᴍ diminished the increase in cell number by 20-40%, application of 10 -4 ᴍ resulted in a total cessation of cellular proliferation. In comparison to cis-diamminedichloroplatinum(II), the cell growth-inhibiting effect of ferricenium complexes was less pronounced and required 10-to 50-fold higher concentration levels to evoke equivalent cytostasis.

In addition to the previously identified wing gland lactone, eldanolide, and the tail brush components, vanillin and p-hydroxybenzaldehyde, several further terpenoid compounds, saturated and unsaturated alcohols and acids, a thioalcohol, as well as two saturated macrocyclic lactones, were identified in the wing gland and tail brush secretions of the male African sugarcane borer Eldana saccharina (Walker).

3,5-Dihydroxy-4-pyrone 3,5-dihydroxy-4-pyrone (Rubiginol) has been identified as a presumed sex pheromone from the cotton harlequin bug Tectocoris diophthalmus (Thunberg). It accumulates as a temporary crystal­ line deposit in the male adult on the external surface of the androconial glands which occur in three pairs on abdominal sternites IV to VI.

There are non-random features in the occurrences of nucleotides in the DNA’s of certain organisms which are detectable by statistical analyses of the entire sequence. Earlier, using the bacteriophage Phi-X 174 DNA sequence, we had reported that the self-information values for one type of dinucleotide association showed a marked periodicity when their autocorrelation coefficients were graphed. A similar, but computationally simpler, analysis has been developed which gives a comparable indication of periodicity. The difference, in average autocorrelation coefficients obtained with this analysis, between the peak values and all others has been used as an index to compare the extent of periodic non-randomness for a series of natural DNA sequences and for various artificial sequences. Calculations show that triplet periodicity, the relationship between dinucleotides separated by a single nucleotide, is characteristic only of the natural sequences of certain filamentous phages and is not found prominently in any other DNA analyzed (including sequences of similar length from plasmids, yeast, bacteria and higher animals). By shuffling nucleotides in a given sequence or by substituting selected nucleotides to alter various positions in both periodic and aperiodic sequences, we have found that an excess or deficiency of a given nucleotide at one of the three positions in a triplet reading frame can simulate the periodic characteristic. Thus, it appears that this global statistical analysis detects the tendency for single­ strand phages to utilize a specific nucleotide, rather than one randomly selected, to constitute codons.

A minimal topological difference (MTD) approach is made to describe quantitative structure-activity relationships (OSAR) for the Na + , K + -ATPase inhibitory activity of cardiotonic steroids. The calculations take into account 20 derivatives of digitoxigenin, digoxigenin, and gitoxigenin with small substituents at different sites of the steroid backbone. A multiple correlation coefficient of r = 0.916 is obtained using the MTD and an indicator variable for the presence of a 15β substituent. The corresponding receptor map reveals receptor wall vertices in the C11 , C12, C15, and C22 regions. Both 3β and 16β substituents are found to contain receptor cavity vertices. The MTD results are discussed with respect to lactone-ring conformational investigations presented and they are compared with findings of previous structure-activity studies.

Several model compounds containing thiol and/or amino groups (mercaptoethanol, glutathione, cysteine, ethanolamine, glycine) were studied with respect to their reactivity towards fluorescein isothiocyanate (followed spectrophotometrically at 504 and 412 nm), stability of product and long­ wave absorption maximum of the fluorescein residue attached. Thiol groups reacted by far more readily than amino groups. A specific effect was observed with cysteine, indicating an intramolecular transfer of the fluorescein residue from SH to NH 2 . With sarcoplasmic vesicles both types of reactions were observed. The ratio of products, which can be distinguished by their different stabilities and absorption spectra, depended on the absence or presence of detergents. While with native vesicles the NH 2 reaction predominated, with vesicles solubilized with sodium dodecylsulfate, octaethyleneglycol mono-n-dodecyl ether or 1-0-tetradecyl-propanediol-(1,3)-3-phosphorylcholine the SH reaction became prevailing. Already 0.35 mg sodium dodecylsulfate per mg protein were sufficient to give rise to dithiourethane formation exclusively. Excess fluorescein isothiocyanate reacted with several thiol groups of dodecylsulfate-solubilized vesicles. In the presence of ATP binding of fluorescein isothiocyanate to native vesicles was significantly reduced. Total blockage of the vesicular SH groups with N-ethyl-maleimide led to preparations that reacted with fluorescein isothiocyanate much more slowly, compared to native vesicles. Octaethy­ leneglycol mono-n-dodecyl ether or 1-0-tetradecyl-propanediol-(1,3)-3-phosphorylcholine in the assay accelerated the thioureide formation from N-ethylmaleimide modified vesicles, whereas sodium dodecylsulfate prevented it almost completely. Our results support the suggestion that one or several thiol groups in vicinity of the highly reactive lysyl residue might play a role in the fast specific reaction, which is only observed with intact native vesicles.

The calcium free sarcoplasmic reticulum calcium transport ATPase incorporates in the presence of magnesium ions approx. 8 nmol monovanadate per mg protein, indicating the formation of a complex containing one vanadate residue per enzyme molecule. On ligand-removal or dilution, the saturated enzyme complex displays biphasic decay kinetics, while the unsaturated complex slowly dissociates monophasically. - Ligand competition by raising the concentrations of unlabeled vanadate results in a progressive decrease of the dissociation rate of the unsaturated enzyme. The complicated dissociation kinetics indicate a sequential mode of interaction between two ligand binding sites. The one to one stoichiometry of the complex suggests that the two sites are located at adjacent ATPase molecules. - It appears unlikely that the decay of the enzyme, vanadate complex is retarded by the formation of a stable quaternary complex between the enzyme, magnesium, mono-and polyvanadate.

For the first time linear dichroism spectroscopy has been extended to the picosecond time regime. 11-cis retinal, all-trans retinal and 1,8-diphenyl-1,3,5,7-octatetraene (DPOT) are incorporated into polyethylene films and oriented by stretching the films. By measuring picosecond transient absorption spectra polarized parallel and perpendicular to the stretching direction and calculating the dichroic ratio we get informations about the molecular geometry in excited singlet and triplet states. The results may have relevance to vision.

The patch clamp technique has been applied to isolated vacuoles from green suspension cells of Chenopodium rubrum to record electrical parameters of the tonoplast. In a symmetrical K + solution of 46 mᴍ, the membrane displays a near zero voltage, whereas 2 mᴍ ATP will hyper-polarize it to 15 or 20 mV (vacuole positive). The conductance amounts to about one S · m -2 . Fluctuations of the clamp current are explained by an unknown channel species having opening times of 5 - 10 ms. Together with previous work on a tonoplast vesicle preparation and unpublished data on vacuoles from our laboratory, the present results indicate an electrogenic membrane ATPase pumping protons from the cytoplasm to the vacuole.

This study was aimed at investigating whether cells of CFU-C derived colonies could form secondary colonies. Bone marrow cultures of volumes of agar medium between 25 μl and 75 μl contained in glass capillaries were stimulated with mouse lung-conditioned medium (MLCM) containing granulocyte/macrophage colony-stimulating factor (GM-CSF). Agar gels with colonies of up to ≥ 20 were blown out into identical culture medium, completely dispersed on a whirl-mix to single cell suspensions, and used for establishing secondary agar cultures. In these secondary cultures considerable numbers of secondary granulocytic, mixed granulocytic/macrophage and macrophage colonies as well as numerous clusters arose. In contrast, when single colonies were recultured, only few secondary cell aggregates were formed. When primary cultures containing up to ≥ 20 cell aggregates were used for serial reculture at intermittent intervals of 3 and 4 days, a 2 -7-fold increase of colony-forming cells was found in tertiary cultures as was monitored by 7 day colony counts. And by use of different kinds of CSF-containing media, an over 4-fold increase of secondary over primary colonies was obtained with bovine lung-conditioned medium (BLCM) in primary and L-cell-conditioned medium (LCCM) in secondary 7 day cultures. Primary capillary cultures were found to be devoid of CFU-S. Also, setting up bone marrow cultures in petri dishes and stimulating with MLCM, growth of primary as well as secondary colonies was obtained. The results indicate some self-renewal potential of CFU-C in vitro.

We have analysed spermatogenetic cells by flow cytometry to quantify effects of ionizing radiation. The radiation-induced reductions of testicular DNA-synthesizing cells, primary spermatocytes, haploid round and elongated spermatids as well as the increases of numerical chromo­ some aberrations (abnormal diploid spermatids and aneuploidies) in NMRI inbred mice are described. Testicular weights were determined as a parameter of germ cell decrease, and histologic cross sections of the testes were analysed. Since even an exposure of 0.05 Gy (= 5 rad) may be detected by a reduction of DNA-synthesizing cells (Acta Radiol. Oncol. Radiat. Phys. Biol. 21, 349-351 (1982) [1]), the use of the in vivo system “spermatogenesis” as a biological dosimeter to monitor low dose effects and to determine RBE values of different radiation qual­ ities is suggested.

Analytical ultracentrifugation studies on proteins in solutions of the nonionic detergent Triton X-100, by means of a UV scanning system, can be conveniently performed by the following procedure: (1) Scanning of the cells is done at a wavelength of 246 nm. (2) The sedimentation of the deter­ gent is prevented by appropriate adjustment of the solvent density. (3) The reference cell is filled with water. Reliable molecular weight determinations can be performed at detergent concentrations up to 0.4% (w/w) in cells of path-length d = 12 mm and at correspondingly higher concentrations for d - 3 mm. Approx. 10 μg of protein are sufficient for a determination. The method should be useful for studies of membrane proteins.

Root hairs of soybeans (Glycine max), target cells for infection by Rhizobium japonicum accumulate iron more than 10-fold, cobalt more than 8-fold and calcium more than 7-fold compared to the other parts of the root system. In root hairs of wheat (Triticum aestivum) a much smaller accumulation of these elements was found. The symbiont of Glycine max, Rhizobium japonicum, is known to have a high requirement for iron, cobalt and calcium.

A quantitative and qualitative study of the seasonal variation of free flavone aglycones from Sideritis leucantha (Lamiaceae) has been carried out by means of HPLC. The flavonoid pattern remained unvariable with seasonal varia­ tion supporting flavonoid aglycones as idoneous taxonomic markers. Quantitative variations were observed, being the summer months which yielded a higher content in these compounds. These highly methylated flavone aglycones are located in the leaves surface as part of the excretion mate­ rial.

In vitro incubation of intact spinach chloroplasts with 1 mᴍ Pyruvate was used to study the specificity of action of the herbicide Chlorsulfuron on the synthesis of valine, alanine and fatty acids. As a result, increasing concentrations of the herbicide strongly inhibited valine synthesis while fatty acid synthesis via pyruvate dehydrogenase complex (PDC) and alanine formation by transamination reaction was promoted.

Ribonucleotide reductase of green algae (Scenedesmus obliquus) is a radical-containing enzyme which rapidly loses activity under anaerobic conditions. Reactivation in the presence of air is enhanced by 10 μᴍ iron(II)-bleomycin chelate. The reaction lends new biochemical potential to the antibiotic and should be valuable in mechanistic studies of ribonucleotide reduction.

Three growth rate experiments involving several sampling points were performed to investigate the previous finding that very low concentrations of HgCl 2 inhibit the growth of murine lymphoblasts in vitro. However, results presented here do not confirm this, there being no significant differences between the three independent growth rate experiments.

Using pulse radiolysis the UV spectra of the C(6) OH adduct radicals of 1,3-dimethyluracil and 1,3-dimethylthy-mine were obtained by reacting the formate radical with the corresponding 5-bromo-5,6-dihydro-6-hydroxy derivatives. In the reaction of the pyrimidines with OH radicals a mixture of C(5) and C(6) OH adduct radicals is formed. From the known ratios in which these two radicals are formed and the spectra of the C(6) OH adduct radicals, the spectra of the C(5) OH adducts were calculated.

DNA transfection in mouse L-cells was performed by means of the electropermeabilization technique (U. Zimmermann, G. Pilwat, and F. Riemann, Z. Naturforsch. 29, 304 (1974)). The plasmid pSV 2-neo used leads to neomycin-resistance in stably transfected L-cells. Optimized conditions resulted in high yields of clones at relatively low DNA concentration. The influence of temperature during pulse application and during the subsequent resealing process as well as the field parameters and medium com­position are discussed.

DNA has definitely been demonstrated in the nucleomorph of a marine Cryptomonas species by combining thin sectioning of Lowicryl K4M-embedded material and DAPI-induced DNA fluorescence.

The influence of females on the amount of scent-marking behavior displayed by male Mongolian gerbils was investigated. Males isolated from females scent mark at a low level which increases more than two-fold if females are present in the room for three weeks without direct contact with the males. A similar increase is obtained by application of pooled female urine directly onto the males’ noses.

Electrophysiological analysis of male antennal Sensilla trichodea in Xestia triangulum and X. ditrapezium showed that they contain the same five types of receptor cells in both species. These cells responded specifically to the (Z)-alkenyl acetates Z7-12:Ac, Z5-14:Ac, Z7-14:Ac, Z9-14:Ac and Z 11-14:Ac. Yet, in field trapping tests, male X. triangulum were highly attracted to pure Z5-14:Ac as a single compound, whereas male X. ditrapezium responded specifically to a ternary combination of Z5-/ Z7-/ Z9-14: Ac with the Z7 isomer as the major constituent. The four other “key compounds” in X. triangulum, and the other two in X. ditrapezium, inhibited trap captures. The results are considered in view of the close taxonomic relationship of the two species and their potential reproductive isolation from other, pheromonally-related noctuid moths.

The sex-attractant system of the dart moth Agrotis exclamationis (L.) (Noctuidae) was re-investigated with electrophysiological and field trapping tests. The identified pheromone components (Z)-5-tetradecenyl acetate and (Z)-9-tetradecenyl acetate elicited maximum trap captures when combined in a Z5-/Z9-mixture ratio of between 100/10 and 100/20, in contrast to an earlier reported mixture optimum of 100/5. Each compound activated a particular type of receptor cell located in the male antennal hair sensilla. Three further cell types discovered in these sensilla responded specifically to the non-pheromonal compounds (Z)-7-dodecenyl acetate and (Z)-7-and (Z)-11-tetra-decenyl acetate. These latter compounds did not show attractive or synergistic properties in field trapping tests but rather reduced captures when added to the binary pheromone blend as a third component. The biological functions of these three “attraction-inhibitors” remain unidentified.