Uptake and utilization of n-octacosane and n-nonacosane by Arthrobacter nicotianae KCC B35

Arthrobacter nicotianae KCC B35 isolated from blue-green mats densely covering oil sediments along the Arabian Gulf coast grew well on C₁₀ to C₄₀ n -alkanes as sole sources of carbon and energy. Growth on C₂₀ to C₄₀ alkanes was even better than on C₁₀ to C₁₈ alkanes. Biomass samples incubated for 6 h with n -octacosane (C₂₈) or n -nonacosane (C₂₉) accumulated these compounds as the predominant constituent alkanes of the cell hydrocarbon fractions. The even chain hexadecane C₁₆ and the odd chain pentadecane C₁₅ were the second dominant constituent alkanes in C₂₈ and C₂₉ incubated cells, respectively. n -Hexadecane-incubated cells accumulated in their lipids higher proportions of C₁₆-fatty acids than control cells not incubated with hydrocarbons. On the other hand, C₂₈ and C₂₉-incubated cells did not contain any fatty acids with the equivalent chain lengths, but the fatty acid patterns of the cell lipids suggest that there should have been mid-chain oxidation of these very long chain alkanes. This activity qualifies A. nicotianae KCC B35 to be used in cocktails for bioremediating environments polluted with heavy oil sediments.     

Evidence for the occurrence of the alternative, vanadium-containing nitrogenase in the cyanobacterium Anabaena variabilis

Abstract Anabaena variabilis can be grown with dependence on either molybdenum (Mo) or vanadium (V) in the medium with essentially the same growth rates. Vanadium cultures reduce C₂H₂ to C₂H₄ and partly (to 2–3%) to C₂H₆. These C₂H₄ and C₂H₆ formations can be shown to be strictly light dependent, proving that the gases are formed by the cyanobacterium. C₂H₄ and C₂H₆ productions are accompanied by a H₂ formation which is much higher than in Mo cultures. Maximal C₂H₂-formation rates are 2/3 lower in V-grown cells compared to Mo control cultures. This is the first demonstration of a light-dependent ethane formation and of the occurrence of the alternative nitrogenase in any phototroph.     

An Endogenous Aminoenkephalinase Inhibitor: Purification and Characterization of Arg0-Met5-Enkephalin from Bovine Striatum

Abstract: Arg⁰-Met⁵-enkephalin (Arg⁰-MEK) was isolated from bovine striatum and purified to homogeneity. The peptide was extracted with trichloroacetic acid, followed by column chromatography successively on Bio-Sil C₈, semipreparative HPLC Radial-Pak C₁₈, fast protein liquid chromatography (FPLC) Mono S, HPLC Ultrasphere-ODS, Supelco C₁₈, Lichromsorb C₁₈, and μBondapak C₁₈. The peptide content was followed by radioimmunoassay with an antibody against synthetic Met-enkephalin. For each of the six HPLC and FPLC systems, the elution time of the immunoreactive fractions coincided exactly with that of synthetic Arg⁰-MEK. The purified peptide showed a highly homogeneous profile in three different analytical HPLC systems. Its retention time and three-dimensional UV spectrum were identical to those of the synthetic Arg⁰-MEK. The structure of the purified material was identified by microsequencing as the hexapeptide Arg-Tyr-Gly-Gly-Phe-Met. Ninety percent of the purified peptide was in oxidized form containing equimolar amounts of Met-( R )- and Met-( S )-sulfoxide. The reduced Arg⁰-MEK inhibited aminoenkephalinase with a K _i of 2.2 µ M , and its sulfoxide analogue inhibited it with a K _i of 8.9 µ M . The reduced or oxidized peptide suppressed the electrically induced contraction of rat vas deferens with an ED₅₀ of 5 µ M , and the effect could be reversed by equimolar naloxone. Our data indicate that Arg⁰-MEK is an immediate Met-enkephalin precursor and an endogenous inhibitor.     

Possible Involvement of Interleukin-1 in Cyclooxygenase-2Induction After Spinal Cord Injury in Rats

Abstract : A standardized compression injury of rat spinal cord brought about a time-dependent biphasic production of thromboxane A₂ (detected as thromboxane B₂) and prostaglandin I₂ (detected as 6-ketoprostaglandin F_1α. Thromboxane B₂ was predominant during the first 1 h, whereas the 6-ketoprostaglandin F_1α level exceeded that of thromboxane B₂ at 8 h postinjury. As examined by inhibitor experiments and northern blotting, cyclooxygenase-1 was responsible for the first phase, and cyclooxygenase-2 was involved in the second phase. On compression injury the levels of interleukin-1α and -1β detected as mRNA and protein increased and peaked at 2-4 h. Injection of exogenous interleukin-1 α into the spinal cord resulted in an increase of cyclooxygenase-2 mRNA content and a predominant production of 6-ketoprostaglandin F_1α resembling the second phase of eicosanoid production. Concomitantly, extravascular migration of polymorphonuclear leukocytes was enhanced after the interleukin-1α injection. These cells together with vascular endothelial cells and glial cells were stained positively with an anti-cyclooxygenase-2 antibody. The results suggest that the immediate eicosanoid synthesis after spinal cord injury was due to the constitutive cyclooxygenase-1 and the delayed synthesis of eicosanoids was attributable to the induction of cyclooxygenase-2 mediated by interleukin-1 α.     

Metabolism of C19- and C20-gibberellins by cell-free preparations from immature Phaseolus coccineus seed

Gibberellin biosynthesis pathways were investigated using isotopically-labelled C₁₉- and C₂₀-gibberellins and cell-free preparations from immature seed of Phaseous coccineus cv. Prizewinner. The initial steps in an early 13-hydroxylation pathway involved the conversion gibberellin A₁₂-aldehyde (GA₁₂-aldehyde) to GA₁₂ which was 13-hydroxylated to yield GA₅₃, Metabolism of GA₅₃ yielded GA₄₄. In contrast to other cell-free systems, GA₄₄ was not further converted, either as a δ-lactone or an open-lactone structure, to the C-20 aldehyde GA₁₉. GA₁₉ was, however, metabolised to GA₂₀, GA₅ and GA₁. GA₂₀ represented a branch point in the pathway as it was converted both to GA₁, which was an end product, and GA₅ which was further converted to GA₆. Like GA₁, GA₆ was also an end-product of the early 13-hydroxylation pathway.
A non-13-hydroxylation pathway involving GA₄, GA₁₅, GA₂₄ GA₃₇ and GA₃₆ also originated from GA₁₂. The terminal product of this pathway was the 3β-hydroxy C₁₉-gibberellin, GA₄.     

Chromosome numbers of C3 and C4 variants within the species Alloteropsis sernialata (R.Br.) Hitchc. (Poaceae)

FREAN, M. L. & MARKS, E., 1988. Chromosome numbers of C₃ and C₄ variants within the species Alloteropais semialata (R.Br.) Hitch. (Poaceae). In a study of mid-lamina leaf sections, different variants of A. semialata were found to have C₃ or C₄ anatomy. The C₄ leaf showed a specialized photosynthetic vascular bundle sheath not present in the C₃ form. Chromosome counts made from pollen mother cell squashes showed that the C₃ form of A. semialata is a fertile diploid 2n = 2x = 18 and the C₄ form, a fertile allohexaploid 2n = 6x = 54. The cytological evidence suggests that the two forms should be considered as separate species.     

Seasonal differences in photosynthesis between the C3 and C4 subspecies of Alloteropsis semialata are offset by frost and drought

The regional abundance of C₄ grasses is strongly controlled by temperature, however, the role of precipitation is less clear. Progress in elucidating the direct effects of photosynthetic pathway on these climate relationships is hindered by the significant genetic divergence between major C₃ and C₄ grass lineages. We addressed this problem by examining seasonal climate responses of photosynthesis in Alloteropsis semialata , a unique grass species with both C₃ and C₄ subspecies. Experimental manipulation of rainfall in a common garden in South Africa tested the hypotheses that: (1) photosynthesis is greater in the C₄ than C₃ subspecies under high summer temperatures, but this pattern is reversed at low winter temperatures; and (2) the photosynthetic advantage of C₄ plants is enhanced during drought events. Measurements of leaf gas exchange over 2 years showed a significant photosynthetic advantage for the C₄ subspecies under irrigated conditions from spring through autumn. However, the C₄ leaves were killed by winter frost, while photosynthesis continued in the C₃ plants. Unexpectedly, the C₄ subspecies also lost its photosynthetic advantage during natural drought events, despite greater water-use efficiency under irrigated conditions. This study highlights previously unrecognized roles for climatic extremes in determining the ecological success of C₃ and C₄ grasses.     

Myelin Gangliosides: An Unusual Pattern in the Avian Central Nervous System

Abstract: Gangliosides were isolated from purified myelin obtained from brain and spinal cord of mature chickens and pigeons. Total concentrations were approximately two- to fivefold greater than for previously reported mammalian species, and their patterns also differed in containing significantly more sialosylgalactosylceramide (G_M4). The latter comprised one-third to one-fourth of total myelin ganglioside, approximately equivalent to G_M1 (II³NeuNAc-GgOse₄Cer). As in mammals, G_M4 of avian CNS appeared to be localized in myelin. Fatty acids of this ganglioside included both the hydroxy- and unsubstituted types. and, long-chain bases were almost entirely C₁₈. Ganglioside G_M1 split into two closely migrating bands on TLC, the slower of which resembled mammalian G_M1 in having stearate as the main fatty acid with a measurable amount (10%) of C₂₀-sphingosine; the faster band had predominantly longer-chain fatty acids and very little C₂₀-sphingosine.     

A survey of photosynthetic carbon metabolism in 4 ecotypes of Phragmites australis in northwest China: Leaf anatomy, ultrastructure, and activities of ribulose 1,5-bisphosphate carboxylase, phosphoenolpyruvate carboxylase and glycollate oxidase

Four ecotypes of Phragmites australis from different habitats in northwest China were examined to compare their photosynthetic characteristics. In a swamp ecotype, the Δ ¹³C value of leaf materials was −34.0‰, and bundle sheath cells contained a small amount of organelles and round-shaped chloroplasts, as being similar to typical C₃ plants. In a dune ecotype, the Δ ¹³C value was −20.9‰ and bundle sheath cells contained oval-shaped chloroplasts with poorly-developed grana. In light and heavy salt meadow ecotypes, Δ ¹³C values were −30.6‰ and −35.6‰, respectively. The shape of bundle sheath chloroplasts in the light salt meadow ecotype was intermediate between those of the swamp and dune ecotypes. Abundance of bundle sheath organelles in the heavy salt meadow ecotype was intermediate. The swamp ecotype had photosynthetic enzyme activities typical of C₃ type plants, whereas the dune ecotype had an increased activity of phosphoenolpyruvate carboxylase (PEPC), a key C₄ enzyme, and a decreased ribulose 1,5-bisphosphate carboxylase (Rubisco) activity. The light salt meadow and heavy salt meadow ecotypes had substantial activities of PEPC, which indicates potential for C₄ photosynthesis. These data suggest that this species evolved the C₃-like ecotype in swamp environments and the C₄-like C₃-C₄ intermediate in dune desert environments, and C₃-like C₃-C₄ intermediates in salt environments.     

Ozone induced emissions of biogenic VOC from tobacco: relationships between ozone uptake and emission of LOX products

Volatile organic compound (VOC) emissions from tobacco ( Nicotiana tabacum L. var. Bel W3) plants exposed to ozone (O₃) were investigated using proton-transfer-reaction mass-spectrometry (PTR-MS) and gas chromatography mass-spectrometry (GC-MS) to find a quantitative reference for plants' responses to O₃ stress. O₃ exposures to illuminated plants induced post-exposure VOC emission bursts. The lag time for the onset of volatile C₆ emissions produced within the octadecanoid pathway was found to be inversely proportional to O₃ uptake, or more precisely, to the O₃ flux density into the plants. In cases of short O₃ pulses of identical duration the total amount of these emitted C₆ VOC was related to the O₃ flux density into the plants, and not to ozone concentrations or dose–response relationships such as AOT 40 values. Approximately one C₆ product was emitted per five O₃ molecules taken up by the plant. A threshold flux density of O₃ inducing emissions of C₆ products was found to be (1.6 ± 0.7) × 10⁻⁸ mol m⁻² s⁻¹.     

Induction of acetoacetate decarboxylase in Clostridium acetobutylicum

Abstract Factors that may initiate the biosynthesis of acetoacetate decarboxylase were investigated in resting cells of Clostridium acetobutylicum . Linear acids from C₁ to C₄ were inducers, whereas branched acids and linear acids from C₅ to C₇ were not inducers of acetoacetate decarboxylase biosynthesis. Induction of acetoacetate decarboxylase was maximal at pH 4.8 in the presence of acid concentrations comparable with those found during fermentation. In growth conditions repression of acetoacetate decarboxylase biosynthesis was found. This fact explains that acetone production by Clostridium acetobutylicum occurs when growth slows down.     

Distribution of C3 and C4 grasses along an altitudinal gradient in Central Argentina

The distribution pattern of C₃ and C₄ grasses was studied in eight sites located between 350 m and 2100 m along an altitudinal gradient in Central Argentina. Of 139 taxa fifty-nine are C₃ and eighty C₄. Species of the C₃ tribes (Stipeae, Poeae, Meliceae, Aveneae, Bromeae and Triticeae) and C₃ Paniceae species increase in number at higher elevations; only one C₃ species was found below 650 m. C₄ Aristideae, Pappophoreae, Eragrostideae, Cynodonteae, Andropogoneae and Paniceae increase at lower altitudes. The floristic crossover point is at about 1500 m; the ground cover cross-over point is at about 1000 m. Analysis of the relationships between % C₄ species along the gradient and nine climatic and environmental variables showed the highest correlation with July mean temperature, but all temperature variables show highly significant correlations with % C₄. Correlation with annual rainfall is lower but also significant. These results are consistent with previous research showing the relative importance of C₄ grasses as temperature increases. C₃ species make a high contribution to relative grass coverage below the C₃/C₄ floristic crossover point but are rare below 1000 m.     

Biodegradation of linear alkylbenzenesulphonates (LAS) by mixed methanotrophic-heterotrophic cultures

The biodegradation of undecylbenzenesulphonate (C₁₁LAS) was studied in shake flasks at 21°C using two mixed bacterial cultures. The first culture, MM1, contained a type II methanotroph and four heterotrophs, and was enriched from a groundwater aquifer. The second culture, MC, consisted of five heterotrophic strains, most of them belonging to the genus Pseudomonas , and was isolated from the wastewater of a detergent plant. Methane, carbon dioxide and oxygen concentrations were determined by gas chromatography. Concentrations of C₁₁LAS and the aromatic intermediates were determined by reversed-phase HPLC. In spite of faster transformation of the alkyl side-chain by the culture MC, the culture MM1 containing type II methanotroph was capable of further degradation of C₁₁LAS aromatic intermediates (sulphophenylalkanoates). The most probable mechanism for the degradation of the alkyl part of the C₁₁LAS molecule by both cultures was β-oxidation of the terminal methyl group followed by β-oxidation. Studies of methane utilization demonstrated an approximately three times higher second-order rate coefficient for methane consumption ( k _max/ K _s) in the absence of C₁₁LAS. This indicates a possible metabolic activity of methanotrophs in the transformation of the complex LAS molecule due to the methane monooxygenase enzyme system.     

Ceramide Induces Apoptosis in Cultured Mesencephalic Neurons

Abstract: The death of dopaminergic and other neurons in primary cultures of the mesencephalon could be induced by treatment with ceramide, as in lymphocytes where it mediates activation by the cytokines tumor necrosis factor-α and interleukin-1β of a novel sphingomyelin-dependent signaling pathway leading to apoptosis. The morphological hallmarks of this form of cell death—bleb formation, cell body shrinkage, nuclear chromatin condensation, and fragmentation—were observed in degenerating neurons. Internucleosomal DNA degradation could also be evidenced by gel electrophoresis. The C₂ and C₆ analogues as well as native ceramide, administered in a dodecane suspension, had a similar effect, whereas the closely related C₂-dihydroceramide, which lacks the 4–5 trans double bond in the sphingosine chain, failed to induce apoptosis. Neuronal death could be delayed by serum factors, dibutyryl cyclic AMP, and the protein synthesis inhibitor cycloheximide.     

Alkane composition diversity among populations of dwarf forms of Juniperus communis L.: comparison between western Europe and northern American populations

The cuticular wax composition of leaves has been analysed in three western European populations (Corsica, central Pyrenees, northern Alps) of Juniperus communis var. saxatilis Pall. (=  J. nana Willd., nom illeg.) and in one population of J. communis L. var. depressa Pursh. from North America (Sierra Nevada). Gas chromatography shows the presence of 13 alkanes in all samples ranging from C₂₃ to C₃₅ with important intraspecific polymorphism in alkane content. The dominant alkanes range from C₃₃ to C₃₅. Alkanes C₂₁ and C₂₂ were found only in Corsica and Sierra Nevada populations. Canonical discriminant analysis separated the J. communis L. var. depressa Pursh. of the population of Sierra Nevada from other populations of J. communis var. saxatilis Pall. on the basis of their higher C₃₁ content and the constant presence of C₂₁ and C₂₂ alkanes. J. communis var. saxatilis Pall. populations from the Pyrenees are close to northern Alps populations characterized by high concentrations of C₃₃, C₃₄ and C₃₅ alkanes. This paper confirms the existence of Juniperus var. saxatilis Pall. in the Pyrenees (France).  © The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 165–168.     

Temperature-dependent changes in phospholipid and fatty acid composition and membrane lipid fluidity of Yersinia enterocolitica

Temperature-dependent compositional changes of phospholipids and their fatty acids were analysed in Yersinia enterocolitica grown at 5°, 25° and 37°C. The relative amounts of the four phospholipids, phosphatidylethanolamine (75–78%), phosphatidylglycerol (10–11%), cardiolipin (<7%) and lysophosphatidylethanolamine (<5%), were essentially the same at all growth temperatures. The degree of fatty acid unsaturation of the four phospholipids increased with decrease in growth temperature, mainly due to an increase of C_16:1 and C_18:1 and a corresponding decrease of C_16;0, C_18:0 and cyclo C_17:0. An electron spin resonance spectroscopic study of the membrane lipids showed that membrane lipid fluidity was enhanced by decreasing the growth temperatures. The changes in fatty acid composition of phospholipids in response to varied temperatures were consistent with the temperature-dependent changes in the membrane lipid fluidity of Y. enterocolitica , and were similar to those reported for other bacteria.     

Effects of cyanide and cold treatment on sugar catabolism in apple seeds during dormancy removal

The ratio of glycolysis to the pentose phosphate pathway (PPP, C₆/C₁ ratio), and the activities of glucose 6-phosphate dehydrogenase (EC 1.1.1.49) and pyruvate kinase (PK, EC 2.7,1.40) were determined in apple seeds ( Malus domestica Borb, cv. Antonówka) submitted to cold and warm stratifications. Our results indicated that the elimination of embryonal dormancy in apple seeds was connected with a change from domination of PPP to domination of glycolysis in sugar catabolism during cold stratification. Cyanide pretreatment affected the C₆/C₁ ratio and the activities of the enzymes under study in such a manner that the maxima of PPP and glycolysis appeared earlier during stratification. We suggest a regulatory role of cyanide in removal of dormancy.     

The role of sex pheromones in initiation of copulatory behaviour by male tsetse flies, Glossina morsitans morsitans

ABSTRACT. Copulatory responses to a variety of decoy objects baited with synthetic 15,19,23-trimethylheptatriacontane were induced in adult male Glossina morsitans morsitans Westw., provided the object was of similar shape and size to a female fly. Chemical and configurational (shape and texture) stimuli were important in eliciting and maintaining copulatory behaviour of males. A dose/response relationship was obtained from 7-day-old test males, with an ED₉₅ of 2 μg using as decoys solvent-washed dead males baited with 15,19,23-trimethylheptatriacontane. The quantity of this compound in 5-day-old adult females is more than 4.0 μg; in males, only 0.6 μg. It is considered to have the characteristics of a true contact sex pheromone for the species, and does not act synergistically with other less stimulatory synthetic compounds. Gas chromatographic analysis of adult female cuticular paraffins of G.m.morsitans showed the presence of two large peaks between C₃₇ and C₃₈ which were virtually absent in males. Young adults of both sexes possessed a series of hydrocarbons below C₂₉ which disappeared during the first few days of adult life. The natural pheromone appears on the pharate adult female about 2 days before emergence from the puparium and is present throughout life. This suggests it is a component of the surface cuticular waxes. Responsiveness of males to pheromone-baited decoys increased to a maximum 3–4 days after emergence in regularly fed flies and only declined during the 24 h prior to death from starvation.     

Variations in the dorso-ventral organization of leaf structure and Kranz anatomy coordinate the control of photosynthesis and associated signalling at the whole leaf level in monocotyledonous species

Photosynthesis and associated signalling are influenced by the dorso-ventral properties of leaves. The degree of adaxial/abaxial symmetry in stomatal numbers, photosynthetic regulation with respect to light orientation and the total section areas of the bundle sheath (BS) cells and the surrounding mesophyll (M) cells on the adaxial and abaxial sides of the vascular bundles were compared in two C₄[ Zea mays (maize) and Paspalum dilatatum ] and one C₃[ Triticum turgidum (Durum wheat)] monocotyledonous species. The C₃ leaves had a higher degree of dorso-ventral symmetry than the C₄ leaves. Photosynthetic regulation was the same on each side of the wheat leaves, as were stomatal numbers and the section area of the BS relative to that of the M cells (BS/M section area ratio). In contrast, photosynthetic regulation in maize and P. dilatatum leaves showed a marked surface-specific response to light orientation. Compared to the adaxial sides of the C₄ monocotyledonous leaves, the abaxial surfaces had more stomata and the BS/M section area ratio was significantly higher. Differences in dorso-ventral structure, particularly in Kranz anatomy, serve not only to maximize photosynthetic capacity with respect light orientation in C₄ monocotyledonous leaves but also allow adaxial and abaxial-specific signalling from the respective M cells.