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Analysis of bud exudate of Populus tristis by GC/MS revealed 61 phenolic components representing 55 phenolic compounds. Caffeic acid esters and chalcones made up the bulk of the exudate.

Propolis and propolis balsam from two different Spanish Regions were analyzed by GC-MS. The majority of the compounds were typical of poplar bud exudate of P. nigra. No significant differences were found between the balsam and the entire propolis analyzed, apart from the components of beeswax added to the plant exudate by the bees.

Bud exudates of Populus simonii and Populus yunnanensis were similar and contained primarily caffeic acid and its esters together with the flavanones pinocembrin and pinobanksin-3-acetate. The terpenoid patterns of the specimens examined varied, but this variation was not species related. On the basis of bud exudate analysis P. simonii and P. yunnanensis may be considered to represent a single species.

Analysis of GC-MS data revealed 76 components of bud exudates from Populus koreana, P. maximowiczii and P. suaveolens (Section Tacamahaca), of which 49 were phenolics. The bulk of the exudates were composed of phenones, pinobanksin-3-acetate and aliphatic esters of caffeic acid. Bud exudates of P. koreana and P. m aximowiczii were virtually identical in composition and closely resembled those of P. suaveolens. The three poplars were alike in having as major com ponents of their bud exudate pentanophenones, which do not occur in the bud exudates of most other poplars. These three Asiatic poplars appear more closely related chemotaxonomically to Section Aigeiros poplars than to those of Section Tacamahaca.

Analysis of bud exudates of Populus deltoides , P. fremontii , P. sargentii and P. wislizenii (Section Aigeiros ) by GC-MS identified a total of 78 components, of which 58 were phenolics. The composition of the bud exudate of all four species was highly similar, the most abundant components being pinocembrin and its chalcone, pinobanksin and its 3-methyl ether, pinobanksin-3-acetate and galangin.

Analysis of GC-MS data revealed 58 com ponents of bud exudate from P. cathayana (Section Tacamahaca) and 40 components of bud exudate from P. szechuanica (Section Tacamahaca) of which 47 and 35 respectively were phenolics. The bud exudates were very similar in composition, containing flavanones and chalcones (61% and 51% respectively), flavones (15% and 12%) and pentenyl caffeates (11% and 6%). The major single component of the exudate of both poplars was pinobanksin- 3-acetate (26% and 33%). The bud exudates of P. cathayana and P. szechuanica are similar to those of European and American Section Aigeiros poplars and unlike those of North American Section Tacamahaca poplars.

Analysis by gas chromatography – mass spectrometry of bud exudates of Populus deltoides and Populus trichocarpa showed that they each contained a number of different compounds. Exudates of P. trichocarpa contained dihydrochalcones and sesquiterpenols, which were absent from the exudate of P. deltoides, but lacked the flavones, flavanones, and flavanonols present in the exudate of P. deltoides. Exudates of their hybrid, P. × generosa (P. × interamericana), contained compounds typical of both parent plants. Bud exudates of Populus angustifolia and Populus sargentii were qualitatively similar in their flavonoid composition but the exudate of P. angustifolia contained in addition caffeate esters, which were absent from P. sargentii. The exudate from the hybrid P. × acuminata was intermediate. Bud exudates of P. angustifolia and P. × acuminata were more like those of P. deltoides and P. sargentii (section Aigeiros) than they were to those of P. trichocarpa (section Tacamahaca). It is therefore suggested that P. angustifolia and P. × acuminata might be more correctly classified together with P. sargentii and P. deltoides within the section Aigeiros. Key words: Populus, bud exudate, chemotaxonomy, gas chromatography – mass spectrometry.

Gas chromatography – mass spectrometry analysis of the bud exudate of seven specimens of Populus tremuloides (section Leuce) revealed a different chemical composition from that previously observed for poplars of sections Aigeiros and Tacamahaca. The bud exudate consists of three principal groups of compounds; benzoic and phenylpropenoic acids and their esters, the flavanones isosakuranetin and sakuranetin and their corresponding chalcones, and hydrocarbons. The flavonoids characteristic of section Aigeiros and section Tacamahaca poplars were found to be either missing, as in the case of flavanonols and dihydrochalcones, or present in very small amounts. The seven specimens of P. tremuloides analysed were classified into three categories depending on the relative proportions of these three groups of compounds present in their bud exudate, and the exudate composition was compared with that of four specimens of Populus grandidentata analysed. Key words: Populus tremuloides, bud exudate, gas chromatography – mass spectrometry.

Propolis was analyzed by gas chromatography-mass spectrometry for both its headspace volatiles and for the less volatile components of its alcoholic extract (propolis balsam). 181 peaks were located of which 171 representing 150 compounds were identified, including 28 identified in propolis for the first time. The majority of compounds were typical of poplar bud exudate.

Analysis of bud exudate by gas chromatography-mass spectrometry (GC–MS) of 14 clones belonging to a natural hybrid swarm involving Populus angustifolia, P. balsamifera, and P. deltoides produced results consistent with those obtained by previous analysis of leaf characteristics. Specimens that had leaves most characteristic of a pure species also produced bud exudate GC–MS profiles which were characteristic of those species. GC–MS profiles of interspecific hybrid clones were intermediate between the parental species. This demonstrates the usefulness of GC–MS analysis of bud exudate as a chemo-taxonomic method for the study of intersecific poplar hybrids and also supports the accuracy of analysis of foliar morphology for taxonomic assessment. Key words: Populus, bud exudate, gas chromatography – mass spectrometry.

The nove 3-methyl-3-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl and 2-phenylethyl esters of 3-acetyloxycaffeic acid and 4-acetyloxycaffeic acid were synthesised on a micro scale and characterised by gas chromatography—mass spectrometry. These compounds are identified for the first tiem in poplar bud exudates.

Analysis by GC-MS separated 50 components of bud exudate from P. sieboldii (Section Leuce ) of which 36 were phenolics. The bulk of the bud exudate (66.7%) was composed of the flavanone naringenin and its methyl ethers sakuranetin and isosakuranetin, together with their corresponding chalcones. These flavanones are minor components (

GC-MS analysis of bud exudate composition of a number of poplars of the section Leuce indicated that Populus alba, P. grandidentata and P. tomentosa were similar in secreting bud exudate containing only hydrocarbon material whereas P. sieboldii, P. tremula and P. tremuloides secreted bud exudate which also included phenolics. The latter three species were distinct from other poplars in secreting an exudate containing flavanones produced only by the first steps of flavonoid biosynthesis, such as naringenin and its methyl ethers, sakuranetin and isosakuranetin, together with their chalcones. Principal component analysis indicated that there are hybrids which are not clearly distinct morphologically from one of the parent species.

The complex mixture of phenolic compounds which is present in the bud exudate of many poplars may be resolved by single ion reconstructions of gas chromatography-mass spectrometry data. The prominent [M − 15]+ ions of the trimethylsilyl derivatives of chalcones, dihydrochalcones, flavones and flavanones render them particularly suitable for location by single ion reconstructions.

GC-MS analysis of bud exudate composition of Populus angustifolia indicated that it was not related chemotaxonomically to the sect. Tacamahaca poplars P. balsamifera and P. trichocarpa but was related to the sect. Aigeiros poplars P. deltoides and P. nigra .

Bud Exudate, GC-MS Bud exudates from twelve clones of Populus nigra originating from seven countries were analyzed by gas chromatography-mass spectrometry and the principal compounds identified. Specimens of P. nigra var betulifolia differed in bud exudate com position from the other specimens analyzed, and were more similar in exudate com position to P. deltoides than were the other specimens. The range of bud exudate com position was greater than that which would be expected to occur within a single coherent species.

Paracoccus denitrificans was grown on either unlabelled glucose, [1-13C]glucose or [6-13C]glucose as the sole carbon source for growth. The cells were then incubated with a range of 14C-glucose substrates to compare the 14CO2-evolution rates between cells grown on the glucose and the 13C-labelled glucose. Cells grown on 13C-glucose had significantly faster rates of 14CO2-evolution than those grown on unlabelled glucose. The % yields of 14CO2, per [1-14C]-, [6-14C]- and [U-14C]glucose supplied were also substantially greater than those measured for cells grown on unlabelled glucose. The data indicated that growth of Paracoccus on 13C-enriched glucose substrates resulted in cells with notably different 14C-glucose oxidation metabolism compared to that observed in cells grown on unlabelled glucose.

Paracoccus denitrificans was grown with either (1-13C) glucose or (6- 13C)glucose as the sole carbon source for growth and the extracts were analysed by gas chromatography/mass spectrometry. The distribution of label observed in the metabolites confirmed that the Embden-Meyerhof pathway was not active in vivo whereas the Entner–Doudoroff and pentose phosphate pathways were operative. However, the pattern of 13C labelling observed in extracts of cells grown on (6-13C) glucose also indicated that a third major glucose oxidation pathway was operative in Paracoccus in addition to the Entner-Doudoroff and pentose phosphate pathways already detected. This additional glucose oxidation pathway decarboxylates the bexose unit in the C-6 position, and is designated the “G6” pathway. It is proposed that the enzymes of the glucuronic acid cycle are used for this decarboxylation sequence. The relative fluxes of glucose carbon through the Entner–Doudoroff, pentose phosphate and G6 pathways calculated for Paracoccus grown on (1- 13C)glucose were substantially different from those calculated for growth on (6-13C)glucose.

Bud exudate of Populus balsamifera contains an array of characteristic compounds. Bud exudate of P. deltoides contains a different array of characteristic compounds. The exudate of P. x jackii contains compounds characteristic of both P. balsamifera and P. deltoides, indicating its hybrid origin.

Bud exudate of Populus deltoides clones originating from six central and eastern American states was examined by gas chromatography/mass spectrometry and the components were identified. The principal components of the bud exudate were the flavone galangin, the flavanone pinocembrin and the flavanonol pinobanksin, together with the related compounds pinocembrin chalcone, pinobanksin methyl ether and pinobanksin-3-acetate. The bud exudate composition was very different from that seen in a North American poplar of the section Tacamahaca, P. balsamifera. The bud exudates from all P. deltoides specimens were similar excepting that from Vermont.

SUMMARY Plants of Dionaea muscipula Ellis fed for 24 h via trap lobes with [13C]glycine or [15N]glycine metabolized the glycine in the fed trap lobes only. Both 13C and 15N labelling was detected in glycine and serine and l5N labelling in alanine, aspartic acid, glutamic acid and 4-aminobutanoic acid extracted from fed trap lobes. Limited amounts of [4-15N]aminobutanoic acid and serine were translocated to the lamina of the fed trap lobes but neither these, nor other labelled amino acids, were detected in other parts of the plant. No 13C labelling was detected in compounds other than glycine and serine.

(1990). The Composition and Plant Origins of Propolis: A Report of Work at Oxford. Bee World: Vol. 71, No. 3, pp. 107-118.

Analysis by GC-MS identified 30 phenolic components of the bud exudate of P. laurifolia. The majority of the exudate was composed of flavanones, flavanonols and chalcones, with pinobanksin-3-acetate being the major component. The bud exudate resembled that of the Asian Section Tacamahaca poplars P. cathayana and P. szechuanica but was unlike that of the North American Section Tacamahaca poplars, P. balsamifera and P. trichocarpa.

Analysis of bud exudate of Populus violascens by GC-MS identified 26 phenolic components. The bulk of the exudate was composed of caffeic acid esters.

Analysis by GC-MS separated 52 components from the bud exudate of P. ciliata of which 38 were phenolics. The exudate was unusual in completely lacking the flavonoids which occur in most poplar bud exudates. Over 70% of the exudate consisted of esters of caffeic acid or acetyloxycafreic acids.

Analysis by GC-MS identified 57 phenolic compounds in the bud exudate of Populus trichocarpa. Of these 11 have not been previously identified in poplar bud exudate. The bulk of the exudate was composed of acetophenones, substituted benzoic acids and their esters, cinnamic acid and its esters, dihydrochalcones, terpenoids and hydrocarbons.

Analysis by GC-MS separated 59 components of the bud exudate from Populus euphratica of which 37 were phenolics. The bulk of the exudate was composed of phenylpropenoic acids and their glyceryl-, monoacetyl glyceryl-and diacetyl glyceryl-esters. Flavonoids, common in many poplar exudates, were lacking.

Summary: We have compared the effect of diphenylamine (DPA) on the pigment composition of Rhodopseudomonas sphaeroides f. sp. denitrificans grown in photoheterotrophic culture with the previously reported effect of nitrate. It was demonstrated that the effect of nitrate is due to the nitrite which is produced during denitrification. Both nitrite and DPA caused a decrease in the synthesis of spheroidene, and the accumulation of more-reduced precursors not normally seen. Nitrate (effectively nitrite) caused a decrease in the amount of bacteriochlorophyll, and the reaction centre from denitrifying cells did not contain the 28 kDal polypeptide (RC-H) subunit. These effects did not occur over a range of DPA additions (4 to 8 μ;g ml-1) to cells growing in the absence of nitrate. Denitrifying cells also had 40-50% lower activity of δ-aminolaevulinic acid synthase than those grown with or without DPA. Both nitrite and DPA treatments resulted in the loss of the B870 light-harvesting complex because of a failure to synthesize its 12 kDal polypeptide subunit.

Propolis balsam from four locations in Oxfordshire was analysed. The balsam was qualitatively similar but showed large quantitative differences in composition. These quantitative differences are related to the bud exudate composition of the poplars from which balsam was gathered.

Forty cysteine-requiring mutants of Paracoccus denitrificans were isolated. The growth requirements of these mutants were consistent with sulphite and sulphide being intermediates in the reduction of sulphate to cysteine in P. denitrificans. Fourteen were deficient in ATP sulphurylase and/or APS kinase. Of these, twelve were also unable to transport sulphate into the cell, showing that they were pleiotropic, being deficient in at least two and possibly three enzymes of the cysteine biosynthetic pathway.

Pyruvate kinase (ATP: pyruvate phosphotransferase (EC 2.7.1.40) was partially purified from both autotrophically and heterotrophically grown Paracoccus denitrificans. The organism grown under heterotrophic conditions contains four times more pyruvate kinase than under autotrophic conditions. The enzyme isolated from both sources exhibited sigmoidal kinetics for both phosphoenolpyruvate (PEP) and ADP. The apparent Km for ADP and PEP in the "autotrophic" enzyme were 0.63 mM ADP and 0.25 mM PEP. The effect of several low molecular weight metabolites on the pyruvate kinase activity was investigated. Ribose-5-phosphate, glucose-6-phosphate and AMP stimulated the reaction at low ADP levels; this stimulation was brought about by an alteration in the apparent Km for ADP. The pyruvate kinases differ in their response to adenine nucleotides, but both preparations seem to be under adenylate control. The results are discussed in relation to the role of pyruvate kinase as a regulatory enzyme in P. denitrificans grown under both autotrophic and heterotrophic conditions.

Cysteinyl- and methionyl-tRNA synthetases (EC 6.1.1.-) were purified 1200and 1000-fold, respectively, from sonic extracts of Paracoccus denitrificans strain 8944, and kinetics, substrate specificity and regulatory properties were determined using the ATP-PP i exchange reaction. Both enzymes had pH optima of approx. 8 and were inhibited by sulphydryl-group reagents. Cysteinyl-tRNA synthetase catalysed l -selenocysteine- and α-aminobutyric acid-dependent ATP-PP i exchange and methionyl-tRNA synthetase catalysed l -homocysteine-, l -selenomethionine- and norleucine-dependent ATP-PPg exchange. Both enzymes were inhibited by O -acetylserine. Cysteinyl-tRNA synthetase activity was stimulated by methionine and methionyl-tRNA synthetase activity was stimulated by sulphide, cysteine, and cysteic acid.

Many aerobic bacteria (both facultative and obligate) possess a number of those biochemical features of mitochondria which are concerned with energy metabolism. However, only restricted number, notably Paracoccus denitrificans and Rhodopseudomonas spheroides, have the majority of these features. The theory of endosymbiosis proposes that a primitive eukaryote took up bacteria to yield mitochondria. The present-day Paracoccus then resembles the ancestral bacterium in many respects the primitive amoeba, Pelomyxa palustris, which lacks mitochondria but contains a permanent population of unique symbiotic bacteria, has many of the characteristics of a present-day transitional form. The evolution of mitochondria from endosymbiotic bacteria would involve their integration with the host cell both biochemically and structurally: a number of the intermediate steps are discussed. Attention is drawn to the existence in some ciliates of hydrogenosomes, which function as anaerobic mitochondria.

The metabolic pathway for the reduction and incorporation of sulphate in Paracoccus denitrificans strain NCIB 8944 has been elucidated and the control and regulation of the pathway is reported. Several enzymes of the sulphate metabolic pathway have been assayed in P. denitrificans grown on different substrates. In addition, several enzymes have been purified and in vitro inhibitor studies conducted on them. Cysteine plays a primary role in the control of sulphur metabolism in P. denitrificans.

Propolis and bud exudate of Populus x euramericana have been analysed by high-resolution gas chromatography–mass spectrometry; 104 compounds have been identified, including 26 not previously identified in propolis or bud exudate. The compounds identified in propolis are derived from three sources: plant exudate collected by bees, wax secreted by bees, and materials such as sugars, which are probably introduced accidentally either during propolis manufacture or during subsequent passage of bees over the propolis. Previous observations that bees use bud exudate from Populus as a primary source for propolis manufacture are confirmed.

Summary: Metabolic profiles from four stages of differentiation of the fungus Phytophthora palmivora were obtained by gas chromatography/mass spectrometry. The profiles showed the presence of sterols in the asexual reproduction stage of the organism, and confirmed their virtual absence from the mycelial stages. The zoospore stage was characterized by the presence of polyunsaturated fatty acids of C20 and C22 chain length. The transition from zoospore to cyst was also marked by the appearance of disaccharides and by a decrease in the amount of phosphate present. There were also distinctive shifts in the proportions and the total amounts of amino acids present, with γ-aminobutyrate and alanine increasing as germination took place. These distinctive profiles identify some of the metabolic changes which accompany differentiation in this fungus.

A fraction of poplar bud exudate was analyzed by GC/MS and the novel aliphatic hydrocarbon esters 2-methylpropyl-, 2-methyl-2-propenyl-, 2-methylbutyl-, 3-methylbutyl-, 2-methyl-2- butenyl-, 4-methylpentyl-, (5)-methylhexyl- and 3,7-dimethyl-2,6-octadienyl(geranyl)- caffeate were identified.

SUMMARY Two genotypes of perennial ryegrass (Loliutn perenne L.), one (S23) sensitive to SO2 and the other (BR) reported to be resistant, were exposed to 0, 50 or 150 ni SO2 1−1 (0, 133 or 398 μg SO2 m−3 at STP) for four weeks under conditions that gave ‘slow’, ‘medium’ or ‘fast’ rates of growth. These treatments allowed comparisons of the responses between genotypes over a range of conditions within which plants could be expected to exhibit maximum and minimum sensitivities to SO2. Significant effects on growth from exposure to SO2 were observed primarily when growth was slow, when the plants were expected to be most sensitive. Although exposure to 150 nl SO2 1−1 significantly increased stomatal resistance two-fold in both genotypes during slow growth, there was no accompanying diminution in leaf sulphur content, implying that a two-fold increase in stomatal resistance is not sufficient to be considered an avoidance mechanism to SO2. Compared with the sensitive S23 gentoype under control (SO2-free conditions, the resistant BR genotype shows slightly greater stomatal resistance, reduced absorption of sulphate through the roots, and reduced dry matter production. Reduced dry matter production in BR may be attributed to its peculiar isoenzyme of ribulose-1,5-bisphosphate carboxylase, which shows a greater resistance to inhibition by sulphite but lower carboxylation rates than ribulose-1,5-bisphosphate carboxylase from S23.

The metabolism of Paracoccus denitrificans , grown on [1- 13 C]-glucose as the sole carbon source, was investigated by using gas chromatographymass spectrometry and metabolic profiling. The distribution of label in a wide range of metabolites (42 in total) showed that the EmbdenMeyerhoff pathway did not operate in vivo whereas both the EntnerDoudoroff and pentose phosphate pathways were operative under the specified growth conditions. It was calculated that 31% of the [1- 13 C]-glucose was metabolized by the Entner-Doudoroff pathway and 69% by the pentose phosphate pathway.

Chromoplasts are heterogeneous organelles and their carotenoids can be associated with several different structural elements including globules, tubules and membranes. In the flower petals of some species, carotenoids are absent or present only in trace amounts. Nevertheless, the plastids in such flowers can closely resemble or even be indistinguishable in structure from chromoplasts.

The production of L-glutamic acid-15N in good yield by direct enzymic synthesis from 2-oxoglutaric acid, ammonium chloride-15N (95 atom % 15N) and reduced nicotinamide adenine dinucleotide phosphate (NADPH) is described. The NADPH is continuously regenerated by coupling the first reaction to the oxidation of glucose-6-phosphate, which serves to drive the synthesis of L-glutamic acid to completion. 4-Aminobutyric acid-15N is produced by incubation of L-glutamic acid-15N with glutamic acid decarboxylase. CO2 is lost from the reaction mixture and the conversion of glutamic acid to 4-aminobutyric acid proceeds to completion. L-Pyroglutamic acid-15N is produced by heating aqueous solutions of L-glutamic acid-15N at 135° for 3 hours.

The preparation of creatine-15N monohydrate from glycine-15N with the isolation of sarcosine-15N as an intermediate is described. Glycine-15N (97.3 atom% 15N) is converted to benzenesulphonyl glycine-15N, which is methylated to give benzenesulphonyl sarcosine-15N. The latter is hydrolysed to sarcosine-15N, which is isolated by ion exchange chromatography. Sarcosine-15N is converted to creatine-15N monohydrate by reaction with cyanamide in aqueous solution in the presence of sodium chloride and catalytic amounts of ammonium hydroxide-14N. The creatine-15N monohydrate precipitated from the above reaction mix is recrystallized from boiling water. The yield of sarcosine-15N from glycine-15N is 78% of theory and that of recrystallized creatine-15N monohydrate from glycine-15N is 59% of theory.

Paracoccus and Rhodopseudomonas are unusual among bacteria in having a majority of the biochemical features of mitochondria; blue-green algae have many of the features of chloroplasts. The theory of serial endo-symbiosis proposes that a primitive eukaryote successively took up bacteria and blue-green algae to yield mitochondria and chloroplasts respectively. Possible characteristics of transitional forms are indicated both by the primitive amoeba, Pelomyxa , which lacks mitochondria but contains a permanent population of endosymbiotic bacteria, and by several anomalous eukaryotic algae, e. g. Cyanophora , which contain cyanelles instead of chloroplasts. Blue-green algae appear to be obvious precursors of red algal chloroplasts but the ancestry of other chloroplasts is less certain, though the epizoic symbiont, Prochloron , may resemble the ancestral green algal chloroplast. We speculate that the chloroplasts of the remaining algae may have had a eukaryotic origin. The evolution of organelles from endosymbiotic precursors would involve their integration with the host cell biochemically, structurally and numerically.

Cyclic, pseudocyclic, and noncyclic photosynthetic phosphorylation are mutually interdependent. Evidence for this is reviewed, in particular where it has to do with regulation of net ATP synthesis during the onset and maintenance of photosynthesis in vivo. It is concluded that both cyclic and noncyclic phosphorylation contribute to photosynthesis and that their relative rates may be controlled by redox poising of their respective electron carriers. The effect of phosphorylation of light‐harvesting‐chlorophyll‐protein on electron transport is to maintain the redox poise of intersystem electron carriers, notably plastoquinone; it will thereby regulate both cyclic and noncyclic electron transport. The cyclic pathway of ATP synthesis is energetically advantageous only where there exists a mechanism for redistribution of excitation between the photosystems. Protein phosphorylation is therefore implicated in regulation of coupling and stoicheiometry of ATP production and in the maintenance of efficient energy c...

We here identify five chalcones and six dihydrochalcones. Of these, three chalcones and five dihydrochalcones have not, we believe, been previously identified in Populus bud exudate. The technique of GC-MS has not been previously applied successfully to the resolution of such a complex mixture

Bud exudates of some poplars are compared using GC-MS. P. candicans resembles P. balsami­fera. A sample of "Balm of Gilead" purchased in Oxford proved not to resemble its supposed source, P. candicans. Instead it was similar to P. nigra, from which it was presumably collected in Europe.