Volume 43, Issue 5-6

Both chiral and racemic phosphatidylethanolamines are known to crystallize in a similar polymorphic form with nearly the same lamellar spacing; yet published lamellar X-ray diffraction intensity data for those materials do not agree with one another, even though the peak positions in Patterson maps are nearly the same. Translational structural searches based on the crystal structure of the racemic compound also lead to similar packing models with both data sets, although the agreement between model and observed data is poor for the chiral compound. A separate analysis of ʟ-DMPE based on lamellar electron diffraction data again leads to a similar lamellar structure with a better agreement between calculated and observed structure factors. The major difference seen for enantiomeric vs. racemic compounds is that, for the racemic lipid, the lateral unit cell spacings are about 3% larger than the chiral form, perhaps indicating a more stable hydrogen bonding network, in agreement with the higher melting point of the racemic compound. Attempts to explain this difference with other head group conformations, however, have not yet produced an improved structural model.

A leaf-differentiating tissue culture which produced substantial amounts of pseudoisoeugenol- (2-methylbutyrate) has been used to examine the origin of the pseudoisoeugenol skeleton. 14 Cand 13 C-labelling revealed ʟ-phenylalanine, trans-cinnamic acid and p-coumaric acid as precursors. 13 C-labelled precursors proved to be especially useful.

Eriodictyon sessilifolium, an endemic Hydrophyllaceae of Baja California (Mexico), has been studied for the natural products exuded by glandular trichomes covering its leaves and stems. Major components of this exudate were isolated and identified by spectroscopic methods to be 4-hydroxy-3-(2,3-dihydroxy-3-methylbutyl)-benzoic acid methyl ester (1), the natural methyl ester of anodendroic acid (2), and 2,2-dimethyl-3-hydroxychroman-6-carboxylic acid methyl ester (3). Possible biosynthetic relations between these new natural products are considered. In addition, 9 known flavonoid aglycones were identified as exudate constituents.

The volatile components of the leaves of four species and five varieties of the section Bicornes of Heterotropa were examined by gas chromatography and gas chromatograph-mass spectrometry. The analytical results showed that the species of the section contain phenylpropanes, terpenes, and a paraffin as main components. The components have been used to construct phylogenetic trees of the section Bicornes. Despite some discrepancies, the phylogenetic tree obtained for the section seems to be relevant at the tribal revel. Among the species of the section, geographical variation of twelve localities of H. takaoi also were examined and three chemical types (myristicin, safrole, n-pentane-elemicin types) of H. takaoi are distinguished on the basis of their components.

A low molecular weight, heat-stable factor has been purified from Euglena gracilis supernatant fraction by employing gel filtration, cation and anion exchange and paper chromatography. This endogenous compound stimulates porphobilinogenase (PBG-ase) (EC 4.3.1.8) activity, an enzyme of the porphyrin biosynthetic pathway. 10 -7 ᴍ folic acid and 10 -4 ᴍ 6-biopterin produced a significant activation, equivalent to 2-4 units of the purified factor. Elution patterns from the columns and fluorescence and UV absorption peaks suggest that this compound is a pteridine. This conclusion is further supported by the fact that both, folic acid and 6-biopterin can replace the action of the isolated factor on PBG-ase. The mechanism of stimulation is discussed.

A low molecular weight compound which stimulates the synthesis of porphyrinogens from PBG was isolated and purified from etiolated Euglena gracilis Z. Absorption and fluorescence excitation and emission spectra, as well as the molecular weight, revealed its structure as an unconjugated pteridine. FTIR bands and 1 H NMR signals of the purified compound were identical with those of an authentic sample of 6-biopterin. The structural formula of this compound is given in Fig. 1.

Carbon 14-labelled cadaverine, Δ1-piperideine and α-tripiperideine were administered to leaf disks of Lupinuspolyphyllus in short term experiments of 12-20 h duration. Whereas cadaverine was readily incorporated into lupanine in good yields, a 7 to 60 times lower incorporation was observed for tripiperideine or Δ1-piperideine. In L. arboreus the incorporation of cadaverine into sparteine was 9 times better than that of Δ1-piperideine. These results indicate that Δ1-piperideine and tripiperideine are not direct intermediates of lupanine or of sparteine biosynthesis.

By means of GC and GCMS 31 constituents of the essential oil of Elsholtzia pilosa have been identified, 1.8-cineol representing the main component (50%). The oil composition with respect to its major constituents has been compared with other Elsholtzia species.

The quaternary structure of ribulose-1,5-bisphosphate carboxylase/oxygenase from tobacco (Nicotiana tabacum) was investigated in solution by means of small angle X-ray scattering. The most important molecular parameters as the radius of gyration (Rg) and the maximum diameter (Dmax) were determined. Both the active and the inactive form of the enzyme were measured at 5 °C and at 20 °C. A more distinct difference in size could be detected between the inactive forms at these two temperatures (Rg = 4.80 nm (5 °C) and 4.68 nm (20 °C)) than between the active forms (Rg = 4.73 nm and 4.69 nm). The maximum diameters were determined to be 13.1 nm for the inactive form at 5 °C and 12.8 nm for the other forms. A model is proposed consisting of eight large and eight small subunits arranged in the way that seems to be typical for this enzyme in higher plants.

NDP kinase and thymidylate kinase are essential for DNA precursor formation in that they phosphorylate the products of de novo deoxyribonucleotide biosynthesis, deoxyribonucleoside 5′-diphosphates and thymidine 5′-monophosphate to the corresponding triphosphates which then serve as DNA polymerase substrates. The two enzymes have been measured in synchronous cultures of the green algae, S. obliquus. Thymidylate kinase exhibits an activity peak at the 11 -12th hour of the 24-hour cell cycle, coinciding with DNA synthesis. Enzyme activity is markedly stimulated in presence of fluorodeoxyuridine in the culture medium. This behaviour of dTMP kinase is very similar to that of three other S phase-specific peak enzymes previously analyzed in synchronous algae, viz. ribonucleotide reductase, thymidylate synthase, and dihydrofolate reductase. In contrast, NDP kinase exhibits high and constant activity through the entire cell cycle. The two kinases have been isolated from cell-free extracts, and separated from each other by chromatography on Blue Sepharose. The peak enzyme, dTMP kinase, has been purified to near homogeneity and its catalytic properties are described; the molecular weight is 56,000. NDP kinase activity is separable into two enzyme fractions, both of molecular weight 100,000 (or higher), which are unspecific with respect to ribonucleotide and deoxyribonucleotide substrates. Characterization and purification of the whole series of deoxyribonucleotide-synthesizing enzymes from one organism provides a basis for in vitro experiments towards reconstitution of an S phase-specific DNA precursor/DNA replication multienzyme aggregate.

The yeast Saccharomyces cerevisiae is shown to be equipped with cyclic GMP, the level of which ranges from 6 pmol/10 9 cells with pressed baker’s yeast to 21 pmol/10 9 cells with exponentially growing cells. In extracts from synchronized growing yeast, cyclic GMP increases stepwise, being doubled at the time of each mitosis. Theophylline and 3-isobutyl-1-methylxanthine induce a rapid increase of cyclic GMP, followed by a premature formation of the septal cell wall between mother cell and bud. The effects of 3-isobutyl-1-methylxanthine are reversible. Dibutyryl-cyclic GMP, and, after a pronounced lag, also dibutyryl-cyclic AMP, induce a premature cell division, too. Cholera toxin induces premature cell divisions without a preceding increase in cyclic GMP. Neither theophylline nor 3-isobutyl-1-methylxanthine, cholera toxin or one of the dibutyryl-cyclic nucleotides modify the growth rate of the culture. None of the agents has significant effects on the level of cyclic AMP. The results suggest that cyclic GMP possibly controls an early step of mitosis, whereas ADP-ribosylation might govern a subsequent event.

The N-trimethylsilyl compounds of the cyclic imides derived from cis-cyclohexan-1,2-dicarboxylic acid, cis-4-cyclohexen-1,2-dicarboxylic acid and phthalic acid were prepared. Reaction of the N-silylated cyclic imides 2 and 10 with 1,2,3,5-tetra-O-acetyl-β-ᴅ-ribofuranose in the presence of tin tetrachloride yielded the appropriate unusual ribonucleosides 4 and 12 whereas 14 led only to traces of the ribosylated derivative. The silylation and ribosylation sites in the aforementioned bicyclic imides were proved by 1 H, 13 C, and 29 Si NMR spectroscopy and compared with data found for the monocyclic imides N-succinimide and N-maleinimide.

Chlorsulfuron (CS) is a potent sulfonylurea herbicide inhibiting specifically acetohydroxyacid synthase which catalyzes the first step in the biosynthesis of branched-chain amino acids in plant cells, bacteria and yeast. The peptide portion of some ergot alkaloids contain inter alia branchedchain amino acids. The influence of CS on growth and alkaloid formation in Claviceps was studied. In an ergotoxine strain growth is inhibited by chlorsulfuron in the range of 10-100 μᴍ. Under CS influence ergosine is accumulated besides ergotoxines. Growth inhibition caused by CS could be reversed by addition of ʟ-valine ( ~ 35 mᴍ), but neither by leucine nor isoleucine. Ergosine did not occur under these conditions. Acetohydroxyacid synthase (AHAS) from Claviceps purpurea was partially purified. AHAS preparations are not inhibited even by high concentrations of chlorsulfuron.

Fructose supported the heterotrophic growth of the cyanobiont Anabaena azollae, isolated from the water fern Azolla filiculoides, and also enhanced its growth in the light by 2-3-fold. Fructose was taken up at a high rate in the light and in the dark, in an energy-dependent reaction. The photosynthetic and respiratory activities of the fructose grown cells were modified: O 2 evolution in vivo was decreased by 40%, while PS I activity and dark respiration were 2-3-fold higher than in autotrophically grown cells. These changes were accompanied by 2-3-fold increase in heterocyst differentiation and by a 4-fold stimulation of nitrogenase activity.

Photosystem-II particles exhibit strong photoinhibition. Short-term illumination of photosystem- II particles with high-intensity light (5000 μE/m 2 × s) leads to a typical change of the protein pattern on SDS-PAGE. Two proteins are mainly affected, namely the well-described 32-kDa herbicide-binding protein which probably is degraded [1] and, first published here, the 9-kDa phosphoprotein, whose function in the PS-II complex is still unknown. This protein is not degraded, but seems to be linked to other polypeptides of the PS-II complex. During light treatment new bands of 23, 41, 50 and 54 kDa appear in the protein pattern of SDS-PAGE. A monospecific antiserum was produced against the 9-kDa phosphoprotein to investigate its fate. After light treatment the antibodies reacted with new proteins of higher molecular weights, most pronounced with a 23-kDa and a 41-kDa peptide.

The effects of two pyridazinone herbicides (SAN 9789 and SAN 9785) were studied on the fine structure and carotenoid composition during the transformation of chloroplasts into chromoplasts in daffodil (Narcissus poëticus L.) flowers. SAN 9789 caused the absence of big characteristic carotene crystals and the appearance of numerous nonosmiophilic plastoglobuli in chromoplasts. The accumulation of all carotenoids was drastically reduced and the content of carotenes was 40-fold lower than in the control. SAN 9785 caused no gross abnormalities in ultrastructure of chromoplasts. The synthesis of carotenes was partially reduced to about 75%. In spite of this the accumulation of xanthophylls is two times higher than in the control. The interaction between chromoplast ultrastructure and carotenoid composition is discussed.

The lipids of photosystem II particles, of chloroplasts and leaves are compared in the variegated tobacco mutant NC 95. The mutant differs from other N. tabacum mutants by the phenomenon that it has variegated leaves with green and with yellow-green leaf patches. Chloroplasts from the green leaf areas exhibit photosystem II and photosystem I reactions and have a normal lamellar system with grana and intergrana regions. Chloroplasts from the yellow-green leaf areas, however, yield only photosystem I reactions and have only single stranded isolated thylakoids. Hence, this mutant offers the unique possibility to compare without the use of detergents within the same plant the lipid composition of photosystem II particles with that in intact chloroplasts, exhibiting either photosystem II and I reactions or those exhibiting exclusively photosystem I reactions. The lipids of photosystem II particles are composed of 37 % glycolipids, 4 % phospholipids, 5 % carotenoids and 54 % chlorophyll. Lipids of chloroplasts with grana stacking are composed of 75% glycolipids, 7 % phospholipids, 2 % carotenoids and 16% chlorophyll. Chloroplasts with single isolated thylakoids have a lipid composition consisting of 8 3 % glycolipids, 14% phospholipids and only 0.5% carotenoids and 2 % chlorophyll. The chloroplast lipid mixture is characterized in comparison to the respective leaf lipid mixture by a 16-17% higher glycolipid portion and by a 13-70% lower phospholipid content. The main difference in the lipid composition of photosystem I and II consists in the observation that chloroplasts active in only photosystem I contain more than double the amount of glycolipids and the 4-fold amount of phospholipids in comparison to photosystem II active preparations. The amount of monogalactolipid is even 3 times higher in chloroplasts active only in photosystem I when compared to those in photosystem II particles. In photosystem II particles phosphatidylethanolamine is completely lacking and phosphatidylglycerol and phosphatidylinositol occur only in traces. The fatty acids of the sulfolipid are by 45 % more saturated in the photosystem II particles and the digalactolipids of the photosystem II particles are by 28 % more saturated than in chloroplasts exhibiting photosystem I and II activity.

Cerulenin-induced modifications in the fatty acid composition have been used to investigate the influence of acyl lipids on excitation energy distribution in thylakoid membranes of Petunia hybrida by means of 77 K fluorescence spectroscopy. Although cerulenin has no effect on relative contents of chlorophyll and acyl lipids, changes in the fatty acid composition of all thylakoid acyl lipids have been observed. The main cerulenin effect seems to be an increase in linoleic acid at the expense of saturated and monounsaturated C 16 - and C 18 -fatty acids resulting most likely in an increase in acyl lipid species containing both linoleic and linolenic acid. Low temperature (77 K ) fluorescence kinetics reveal a remarkable decrease in the ratio of the variable divided by the maximal fluorescence of photosystem II (F 2 (v)/F 2(M) ), taken as indicator for cerulenin-induced changes in this photosystem. Calculations of the excitation energy distribution terms based on a grouped bipartite model of photosynthesis suggest that a decrease in this ratio is caused by changes in energy transfer probabilities responsible for both, photochemical trapping of photosystem II and energetic cooperativity (grouping) between different photosystem II-light harvesting complex-units. Moreover, changes in the conformation responsible for spillover energy transfer are most likely to occur. Correlations between cerulenin-induced modifications of fatty acid composition and energy distribution support the assumption that excitation energy transfer depends on the structural state of the lipid matrix.

In Scenedesmus about half of NADH oxidation proceeds via a cyanide-sensitive and the other half via a cyanide-insensitive respiratory pathway. In contrast, respiration is completely cyanide sensitive in pea indicating that the alternative respiratory pathway is absent. Cu deficiency in pea plants and in heterotrophically grown Scenedesmus cells interferes with respiratory activity of mitochondria. In both organisms, the cyanide-sensitive NADH oxidation was strongly decreased during cultivation in low Cu media. Cu sensitivity was also observed for the alternative respiratory pathway in Scenedesmus. These results suggest that a Cu-containing component is involved in the alternative respiratory pathway. This is the main reason why alternative respiration cannot be regarded as a compensation for low cytochrome-oxidase activities during Cu starvation. The Cu dependency of the cyanide-sensitive respiration was located at the site of cytochrome oxidase. A strong coordination of the biosynthesis of the Cu-containing cytochrome-oxidase complex was evident. When the endogenous Cu pool was low, formation of cytochrome aa 3 , another component of cytochrome oxidase, was also decreased.

It has been investigated if photoreduction of NADP + (detected by absorption spectroscopy) may take place in lysed plastids within minutes of exposure to light. This process was made possible by removal of oxidants from the reaction mixture. Lysed plastids were suspended in a medium containing NADP + , catalase, glucose oxidase and glucose; exposure to light simultaneously to addition of ferredoxin and ferredoxin-NADP + reductase, resulted in increased absorbance in the band around 340 n m , while addition of 3-phosphoglycerate resulted in the disappearance of this band. Ferredoxin and ferredoxin-NADP + reductase are only effective when photoactivation takes place before their addition to the medium.

We have studied the serological relationship among the human immunodeficiency virus type 1 (HIV-1), and three simian immunodeficiency viruses (SIV). SIVagm was isolated from African green monkeys (Cercopithecus aethiops), and compared with the previously described isolates of SIVmac from a rhesus macaque (Macaca mulatta) and SIVsm from a sooty mangabey (Cercocebus atys). With respect to the glycoproteins, the simian viruses represent a subgroup apparently different from HIV . To classify HIV and SIV isolates further, we compared tryptic peptide maps of the core polypeptides p18 and p24 of HIV-2, three HIV-1 and five SIV isolates. Each peptide map was distinguishable, and differences are most prominent between the HIV-1 group and the SIVmac/SIVsm group. HIV-2 is very similar to SIVmac and SIVsm. The three SIVagm isolates form a more heterogeneous group. The p24s of all SIVagms are more similar to the p24s of HIV-1, but with respect to p18, one isolate is similar to HIV-1, while the two others are more related to SIVmac, SIVsm, and HIV-2.

During locust spermatocyte development, rudimentary cilia originate from all centrioles of the doubled prophasic centrosome, located in the centrosphere and specifically linked to the nuclear envelope. Membranous vesicles at the bases of the centrioles fuse to form an intracellular ampulla that contributes the ciliary membranes. Later in prophase the ampulla’s membrane is integrated into the plasma membrane so that all primary cilia project into the extracellular medium and lose contact with the nucleus. As the centrioles remain ciliated on their way to their polar positions, w e propose a mechanism for this migration which is based on this intimate association between centrosomes and plasma membrane, on membrane fluidity and on a contractile cell cortex. We noted a translocation of the ciliated centrioles below the cell surface at the metaphase/-anaphase transition which may be regarded as “deciliation” by light microscopy. Some possible explanations for the primary cilium’s role in cell cycle regulation are suggested.

Sex attractants for the sibling taxa Diachrysia chrysitis (L.) s.str. and D. tutti (Kost.) were field tested on 9 sites in Hungary. Catches with the two already described attractant blends, Z-5-10:Ac/Z-7-10:Ac in ratios 10:1 and 2:100, were similar to earlier results obtained in areas more to the west, chrysitis s.str. type males responding to the 10:1 while tutti type males to the 2:100 ratio. Substantial chrysitis s.str. catches were also obtained by the intermediate 1:1 blend. On all 9 sites the two taxa were co-occurring.

A recent theory attempts to explain how bees take their compass orientation from the pattern of polarized light in the sky (S. Rossel and R . Wehner, Nature 323, 128-131 (1986)). According to this theory, orientation can be erroneous and lead to the wrong course of a recruited bee in search of the foraging site whenever only a small patch of the blue sky is visible to the bee. It is shown that orientation under natural conditions is not erroneous, if the compass reference is variable in time but equally defined for both, scout bees and recruits.

The prenyl ester and the phenylethyl ester of caffeic acid, formed in the bud excretion of poplar species, were shown recently to be the major contact allergens in bee-glue. A n unambiguous synthesis of these compounds, based on the reaction of caffeic acid with 1-bromo-3-methyl-2-butene and with β-bromoethylbenzene, respectively, is reported. The synthetic products confirm the previously described structures of the natural products and allow further testing of their allergenic properties.

3-Hydroxy retinal acts as visual chromophore instead of retinal in the eyes of several insect orders. A HPLC separation system of the aldehyde and oxime isomers and their identification by 400 MHz 1 H NMR spectroscopy is described.

Corresponding sites of the Euglena chloroplast and yeast small subunit ribosomal RNAs (rRNAs) show only an insignificant match with each other but show extensive matches with the Euglena chloroplast tRNA arg . The match with the tRNA extends farther toward the 5′ end of the Euglena rRNA and toward the 3′ end of the yeast rRNA. The expected number of such configurations given the number of RNAs searched is about 1 in 100,000. Comparison of two sequences with a third sequence frequently reveals relationships where pairwise comparisons fail to do so.