bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Late Cenozoic age for long‐wavelength surface uplift of the Atlas Mountains of Morocco
Authors: Babault Julien , Teixell Antonio , Arboleya Maria Luisa , Charroud Mohammed 
Published: February 2008

AbstractThe Atlas Mountains have been uplifted by two mechanisms: Cenozoic thickening of the crust and thinning of the mantle lithosphere due to a buoyant thermal anomaly, previously inferred by indirect criteria to have started some 15 Ma. Because crustal shortening‐related uplift and mantle‐related uplift affect the topography at different spatial scales, we use scattered direct surface evidence to clarify the palaeoelevation dynamics. Uplifted Messinian shallow marine sediments in the southern margin of the Saïss Basin and in the northern Middle Atlas, tilted Pliocene lacustrine deposits in the Saïss Basin and in the piedmont of the southern High Atlas and drainage‐network reorganization in the Saïss Basin underscore the long‐wavelength rock uplift of the Atlas domain of mantle origin. The low erosion of the aforementioned deposits indicates that such uplift is a true surface uplift that occurred in post‐Miocene times at a minimum rate ranging from 0.17 to 0.22 mm yr−1.
MAPK phosphorylation‐induced stabilization of ACS6 protein is mediated by the non‐catalytic C‐terminal domain, which also contains the cis‐determinant for rapid degradation by the 26S proteasome pathway
Authors: Joo Sunjoo , Liu Yidong , Lueth Abraham , Zhang Shuqun 
Published: February 2008

SummaryEthylene is an important hormone in plant growth, development and responses to environmental stimuli. The ethylene‐signaling pathway is initiated by the induction of ethylene biosynthesis, which is under tight regulation at both transcriptional and post‐transcriptional levels by exogenous and endogenous cues. 1‐Aminocyclopropane‐1‐carboxylic acid synthase (ACS) is the rate‐limiting enzyme that catalyzes the committing step of ethylene biosynthesis. Recently, we found that ACS2 and ACS6, two isoforms of the Arabidopsis ACS family, are substrates of a stress‐responsive mitogen‐activated protein kinase (MAPK) cascade. Phosphorylation of ACS2/ACS6 by MPK6 leads to the accumulation of ACS proteins and the induction of ethylene. In this report, we demonstrate that unphosphorylated ACS6 protein is rapidly degraded by the 26S proteasome pathway. The degradation machinery targets the C‐terminal non‐catalytic domain of ACS6, which is sufficient to confer instability to green fluorescent protein and luciferase reporters. Phosphorylation of ACS6 introduces negative charges to the C‐terminus of ACS6, which reduces the turnover of ACS6 by the degradation machinery. Consistent with this, other nearby conserved negatively charged amino acid residues are essential for ACS6 stability regulation. Protein degradation and phosphorylation are two important post‐translational modifications of proteins. This research reveals an intricate interplay between these two important processes in controlling the levels of cellular ACS activity, and thus ethylene biosynthesis. The post‐translational nature of both processes ensures a rapid response of ethylene induction, which is detectable within minutes after plants are exposed to stress.
Mutation of a mitochondrial outer membrane protein affects chloroplast lipid biosynthesis
Authors: Xu Changcheng , Moellering Eric R. , Fan Jilian , Benning Christoph 
Published: February 2008

SummaryLipid biosynthesis in plant cells is associated with various organelles, and maintenance of cell lipid homeostasis requires nimble regulation and coordination. In plants, environmental cues such as phosphate limitation require readjustment of the lipid biosynthetic machinery to substitute phospholipids by non‐phosphorous glycolipids. Biosynthesis of the galactoglycerolipids predominant in plants proceeds by a constitutive and an alternative pathway that is known to be induced in response to phosphate deprivation. Plant lipid galactosyltransferases involved in both pathways are associated with the plastid envelope membranes and are encoded by nuclear genes. To identify mechanisms governing the activity of the alternative galactoglycerolipid pathway, a genetic suppressor screen was conducted in the background of the digalactolipid‐deficient dgd1 mutant of Arabidopsis. A suppressor line that partially restored digalactoglycerolipid content in the dgd1 background carries a point mutation in a mitochondrial protein, which was tentatively designated DGD1 SUPPRESSOR 1 (DGS1). Presumed orthologs of this protein are present in plants, algae and fungi, but its molecular function is not yet known. In the dgd1 dgs1 double mutant, expression of nuclear genes encoding enzymes of the alternative galactoglycerolipid pathway is increased and hydrogen peroxide levels are elevated. This increase in hydrogen peroxide is proposed to be the reason for activation of the alternative pathway in the dgd1 dgs1 double mutant. Accordingly, hydrogen peroxide and treatments producing reactive oxygen also activate the alternative pathway in the wild‐type. These results likely implicate the production of reactive oxygen in the regulation of the alternative galactoglycerolipid pathway in plants.
Purification of an α‐L‐arabinofuranosidase from carrot cell cultures and its involvement in arabinose‐rich polymer degradation
Authors: Konno Haruyoshi , Yamasaki Yoshiki , Katoh Kenji 
Published: February 2008

Konno, H., Yamasaki, Y. and Katoh, K. 1987. Purification of an α‐L‐arabinofurano‐sidase from carrot cell cultures and its involvement in arabinose‐rich polymer degradation.An α‐L‐arabinofuranosidase (α‐L‐arabinofuranoside arabinofuranohydrolase, EC 3.2.1.55) was isolated from a homogenate of cell suspension cultures of carrot (Daucus carota L. cv. Kintoki). The buffer‐soluble enzyme was purified to homogeneity by a procedure involving ammonium sulfate fractionation, chromatography on DEAE‐Sephadex A‐50, Sephadex G‐150, Con A‐Sepharose 4B and CM‐Sephadex C‐50, and preparative polyacrylamide gel electrophoresis. The size of this enzyme as determined by polyacrylamide gel electrophoresis in the presence of sodium laurylsulfate and by Sephadex G‐200 gel filtration was 94 and 110 kDa, respectively. The isoelectric point was at pH 4.7. The Km and Vmax values for p‐nitrophenyl α‐L‐arabinofuranoside were 1.33 mM and 20.2 μimol (mg protein)‐1 h‐1, respectively. The optimal activity occurred at pH 4.2 with Mcllvaine buffer. The enzyme was stimulated by Ca2+ and Zn2+, whereas it was strongly inhibited by Cu2+, Ag2+, Hg2+, p‐chloromercuri‐benzoate and L‐arabono‐l,4‐lactone. The enzyme acted on beet arabinan in an exo‐fashion. Furthermore, the enzyme was partially involved in the hydrolysis of the ara‐binogalactan and pectic polymer purified from carrot cell walls.
Low temperature spectrophotometry of the phototransformation of Pfr to Pr in pelletable pea phytochrome
Authors: Manabe Katsushi 
Published: February 2008

Manabe, K. 1987. Low temperature spectrophotometry of the phototransformation of Pfr to Pr, in pelletable pea phytochrome.Low temperature spectrophotometry was used to study the phototransformation of Pfr to Pr in 1000–7000 g pelletable fractions extracted from dark grown pea (Pisum sativum L. cv. Alaska) epicotyls which had been irradiated with red and then far‐red light. At ‐170°C, far‐red irradiation of the pelletable phytochrome which had been pre‐irradiated with saturating fluence of red light before freezing caused formation of an intermediate (named I660), the difference spectrum of which showed a marked ab‐sorbance decrease at 740 nm and a concomitant small increase at about 660 nm. The inermediate I660 was converted to another intermediate (I660) when it was warmed above ‐80°C. The difference spectrum of this intermediate showed a positive peak at 670 nm. This intermediate was photoconverted to Pfr by red irradiation and also underwent dark reversion to Pfr at ‐60°C. I660 formed Pr if the temperature was above ‐10°C. The basic features of the phytochrome intermediates resemble those obtained in vivo and in degraded purified phytochrome.
Chilling injury and recovery in detached and attached leaves measured by chlorophyll fluorescence
Authors: Smillie Robert M. , Nott Robyn , Hetherington Suzan E. , Öquist Gunnar 
Published: February 2008

Smillie, R. M., Nott, R., Hetherington, S. E. and Öyustt, G. 1987. Chilling injury and recovery in detached and attached leaves measured by chlorophyll fluorescenceChilling injury was compared in detached and attached leaves chilled at 0 or 0.5°C by measuring the decrease in induced chlorophyll fluorescence in vivo. The fluorescence parameter measured was FR, the maximal rate of rise of induced chlorophyll fluorescence emission after irradiating dark‐adapted leaves. The plants used were bean, Phaseolus vulgaris L. cv. Pioneer, and maize, Zea mays L. cvs hybrid GH 390 and Northern Belle. Leaves were detached and placed on wet paper and covered with thin polyethylene film to prevent water loss during chilling. Leaves left attached on plants were treated similarly. When chilled in this way at 100% relative humidity, the chilling‐induced decrease in FR was the same in detached and attached leaves. For the attached leaves, the same result was obtained whether just a single leaf was chilled or the whole plant. Expression of chilling injury was greatest in fully turgid leaves and comparisons can be invalid unless the water status of the detached and attached leaves are the same. Problems arising from diurnal fluctuations in water potential of plants grown in a glasshouse were circumvented by placing leaves on the wet filter paper under polyethylene film prior to chilling, which allowed high water potentials to be regained, or mist sprays in the glasshouse were employed. Determinations of the time course for changes in FR of maize (cv. Northern Belle) during chilling at 0°C showed that FR decreased exponentially, at the same rate (time to 50% decrease in FR was 9.3 h) in detached and attached leaves. Chilling injury was largely reversible for the first 20 h of chilling stress as both detached and attached leaves recovered their pre‐chilling values of FR after a further 20 h at 20°C in darkness. Leaves chilled for 48 h showed partial recovery, while those chilled for 72 h did not recover. Recovery was impeded by light. Inability to recover from chilling as indicated by measurements of FR was paralleled by the incidence of visible symptoms of injury. It is concluded that detached and attached leaves behave similarly during chilling and short‐term recovery, provided a similarity in treatments is rigorously maintained.
Studies on [14C]‐glucose metabolism during shoot bud induction in cultured cotyledon explants of Pinus radiata
Authors: Bender Ludwig , Joy Richard W. , Thorpe Trevor A. 
Published: February 2008

Bender, L., Joy IV, R. W. and Thorpe, T. A. 1987. Studies on [14C]‐glucose metabolism during shoot bud induction in cultured cotyledon explants of Pinus radiala.Excised cotyledons of Pinus radiata D. Don, cultured under shoot‐forming (plus N6‐benzyladenine) and elongating (minus N6‐benzyladenine) conditions, were fed U‐[14C]‐glucose for 3 h in the light followed by a 3 h chase period immediately after excision (day 0) and after 3 days of culture (day 3). The incorporation of l4C into individual soluble metabolites as well as into protein was followed. No labelled citrate could be detected at day 0, however, a flow of 14C from glucose to glutamate/ glutamine occurred. During this stage the synthesis of glutamine strongly increased in the cotyledons supplied with N6‐benzyladenine, which suggests a positive influence of this cytokinin on nitrogen incorporation prior to differentiation. After 3 days of cultivation large amounts of labelled citrate were detected. An increased incorporation of label into protein due to the cytokinin treatment was not detected during the early culture period (days 0 and 3). Labelled amino acids were incorporated into protein to different degrees, but this was not influenced by the hormonal treatment.
Symbiotic properties ofLotus pedunculitisroot nodules induced byRhizobium lotiandBradyrhizobiumsp. (Lotus)
Authors: Vance Carroll P. , Reibach Paul H. , Pankhurst Clive E. 
Published: February 2008

Vance, C. P., Reibach, P. H. and Pankhurst, C. E. 1987. Symbiotic properties ofLotus pedunculatusroot nodules induced byRhizobium lotiandBradyrhizobiumsp. (Lotus).Symbiotic properties of root nodules were evaluated in glasshouse‐grownLotus pedunculatusCav. cv. Maku inoculated with either a fast‐growingRhizobium lotistrain NZP2037 or a slow‐growingBradyrhizobiumsp. (Lotus) strain CC814s. Although the nodule mass of plants inoculated with NZP2037 was twice that of plants inoculated with CC814s, the yield of NZP2037 shoots and roots was 50% that of CC814s shoots and roots. Nodules induced byBradyrhizobiumfixed substantially more N than nodules induced byR. loti.Glucose requirements [mol glucose (mol N2fixed)‐1] of nodules induced by CC814s and NZP2037 were 7.1 and 16.6, respectively. Nodule enzymes of carbon and nitrogen assimilation reflected the disparity of the two sym‐bioses. Xylem sap of the symbiosis with the higher yield contained a higher concentration of asparagine [9.86 μmol (ml xylem sap)‘] than did the lower yielding symbiosis [5.80 umol (ml xylem sap)“’]. Nodule CO2fixation was directly linked to nodule N assimilation in both symbioses. The results indicate that the difference between the two symbioses extend to nodule N and C assimilation and whole plant N transport. The data support a role for host plant modulation of bacterial efficiency and assimilation of fixed N.
Multiple‐site inhibition by colloidal elemental sulfur (S°) of respiration by mitochondria from young dormant α spores of Phomopsis viticola
Authors: Beffa TYello , Pezet Roger , Turian Gilbert 
Published: February 2008

Beffa, T., Pezet, R. and Turian, G. 1987. Multiple‐site inhibition by colloidal elemental sulfur (S°) of respiration by mitochondria from young dormant α spores of Phomopsis viticola.Mitochondria from young dormant α spores of Phomopsis viticola Sacc. (ATCC 44940) were isolated by grinding and differential centrifugation. They presented a good integrity of their inner and outer membranes as measured by biochemical assays. Electron microscopic analysis revealed an homogenous population. The highest respiratory activities were observed with NADH and ascorbate + tetra‐methyl‐p‐phenylenediamine (TMPD). Malate stimulated the oxidation of pyruvate, citrate or α‐ketoglutarate. The coupling of respiration to oxidative phosphorylation appeared at the time of spore germination. The respiratory activities of mitochondria isolated from young dormant α spores of P. viticola were strongly inhibited by S°. The sensitivity of mitochondrial oxidation of different substrates (NADH, pyruvate + malate, succinate and ascorbate + TMPD) to S° was heterogenous and indicated multiple‐site action. Thus preincubation of mitochondria with 30 μM S° before addition of substrates fully prevented NADH oxidation (>98%), and strongly inhibited oxidation of pyruvate + malate (85%), succinate (60%) and ascorbate + TMPD (74%). S° inhibited more rapidly the oxidation of succinate than that of other substrates. In the presence of dithiothreitol (DTT), S°‐inhibited oxidation of all substrates (except ascorbate + TMPD) could only be transiently and weakly reestablished. The inhibitory action of S° on the oxidation of NADH, pyruvate + malate and succinate was higher than that observed with sulfhydryl group reagents such as mersalyl, Hg‐acetate or p ‐ chloromercuribenzoate. In contrast to S° these SH‐group reagents could not inhibit oxidation of ascorbate + TMPD.S°, by its dual capacity to oxidize the SH‐groups and to self‐reduce, probably at the level of cytochrome c oxidase, could produce a modification of the oxidation state of the respiratory complexes thereby disturbing the electron flux.
The effect of UV‐A light on cAMP level in the basidiomycete Schizophyllum commune
Authors: Yli‐Mattila Tapani 
Published: February 2008

Yli‐Mattila, T. 1987. The effect of UV‐A light on cAMP level in the basidiomycete Schizophyllum commune.The level of cyclic AMP was studied in two dikaryotic strains of Schizophyllum commune Fr. In the strain 3×4, requiring light for fruiting, the level of cAMP in 72‐h‐old colonies was 12.1 pmol (mg protein)‐1. The level of cAMP increased ca 50% within 2 h of the beginning of exposure to light (UV‐A, 1 h, 8.3 umol m‐2 s_1). During the following 8 h there was a slight decrease in the level of cAMP. In the dark controls the level of cAMP increased ca 13% within 5 h of the light treatment. This slight increase was continued during the next 19 h. In the strain 245 times 252, which forms more fruit bodies than strain 3×4, the increase was ca 110% within 10 h of the light treatment, while in the dark controls the level of cAMP in 82‐h‐old colonies was the same as in 72‐h‐old colonies [10.3 pmol (mg protein)‐1]. During the following 14 h the cAMP content increased sharply (ca 80%) in the dark controls, which might be connected with the ability of strain 245 × 252 to produce fruit bodies in darkness. In dark‐grown colonies of strain 3×4, the level of cAMP was higher in the marginal than in the central zones. The difference disappeared within 2 h of the beginning of exposure to light, since cAMP increased more in the central zone. This difference may be related to the ability of the marginal zone to form fruit bodies in light.
Effect of sugar level on phleinase induction in stem base of orchardgrass after defoliation
Authors: Yamamoto Shinro , Mino Ydsuke 
Published: February 2008

Yamamoto, S. and Mino, Y. 1987. Effect of sugar level on phleinase induction in stem base of orchardgrass after defoliation.The induction of phleinase (β‐D‐fructan fructohydrolase, EC 3.2.1.80) in stem base of orchardgrass (Dactylis glomerata L. clone N‐377) after defoliation was studied in relation to the concomitant changes in sugar and protein levels. Phleinase activity in the stubble increased accompanied by a decrease in sucrose and glucose levels. This activity also increased under shading conditions without cutting. The induction of phleinase in excised stem base was suppressed by exogenously supplied glucose, fructose or sucrose. The suppression increased with increasing concentrations of glucose and it was not overcome by cyclic adenosine 3′,5′‐monophosphate. Protein level in the stem base decreased after defoliation and the decrease was reversed by exogenous glucose. Some hypotheses concerning the induction mechanism of phleinase are discussed.
Hypocotyl growth of Pinus pinaster seedlings. Changes in α‐cellulose, and in pectic and hemicellulosic polysaccharides
Authors: Lorences Ester P. , Suarez Lisandro , Zarra Ignacio 
Published: February 2008

Lorences, E. P., Suárez, L. and Zarra, I. 1987. Hypocotyl growth of Pinus pinaster seedlings. Changes in a‐cellulose, and in pectic and hemicellulosic polysaccharides.The changes in pectic and hemicellulosic polysaccharides of hypocotyl cell walls during the growth of intact seedlings of Pinus pinaster Aiton were investigated, α‐Cellulose and the water‐soluble hemicellulose presented the most conspicuous changes during hypocotyl growth. The relative amount of the water‐soluble hemicellulose decreased from day 7 to day 13 when hypocotyls were in the rapid growth phase, and stabilized when hypocotyl growth ceased. In this fraction, the relative amount of non‐cellulosic glucose decreased dramatically during hypocotyl growth, while the relative amount of xylose increased. We suggest that these changes may be due to partial degradation of xyloglucan present in the water:soluble hemicellulose fraction, accompanied by the synthesis of a xylan.
Hypocotyl growth of Pinus pinaster seedlings. Changes in the molecular weight distribution of hemicellulosic polysaccharides
Authors: Lorences Ester P. , Suarez Lisandro , Zarra Ignacio 
Published: February 2008

Lorences, E. P., Suárez, L. and Zarra, I. 1987. Hypocotyl growth of Pinus pinaster seedlings. Changes in the molecular weight distribution of hemicellulosic polysaccharides.The changes in the molecular weight distribution of water‐soluble hemicelluloses and xyloglucan during hypocotyl growth of intact seedlings of Pinus pinaster Aiton were investigated. The mass‐average molecular weight of total polysaccharides of the hemicellulose fraction soluble in 4% KOH dramatically increased during hypocotyl growth while xyloglucan slightly decreased. These phenomena were due to an increase in the degree of polymerization of an arabinogalactan and a slight depolymer‐ization in the xyloglucan present in this fraction. In the hemicellulose fraction soluble in 24% KOH, xyloglucan increased its degree of polymerization from day 7 to 10 after which it decreased slightly. The xyloglucan of the hemicellulose fraction soluble in 4% KOH may thus be involved in cell wall loosening which makes cell wall expansion possible during hypocotyl growth.
Stomatal responses to rapidly imposed water stress and light/dark transition in norflurazon‐treated wheat leaves
Authors: Höglund Hans‐Olof , Klockare Rune 
Published: February 2008

Hoglund, H. O. and Klockare, R. 1987. Stomatal responses to rapidly imposed water stress and light/dark transition in norflurazon‐treated wheat leaves.Stomatal responses to rapidly imposed water stress and to light/dark transition were studied in leaves of wheat (Triticum aestivum L. cv. Starke II) treated with nor‐flurazon (NF) which is known to inhibit abscisic acid (ABA) accumulation. The stomatal response was studied in an open air flow system. It was shown that these plants have the ability to respond to externally added ABA. When the water potential in the nutrient solution was rapidly reduced, stomata in green plants responded with a transient opening followed by a strongly decreased aperture. NF‐treated plants responded with a similar rapid opening of stomata, but the following closure was strongly reduced. Transfer from light to darkness induced a rapid closure of stomata in green plants but the closing response was strongly delayed in NF‐treated plants. These results indicate that NF affects one or more regulators involved in the closure of stomata under rapidly imposed water stress and in the light/dark transition. The possibility that this regulator is ABA is discussed.
Subcellular distribution of pyruvate‐degrading enzymes in Chlamydomonas reinhardtii studied by an improved protoplast fractionation procedure
Authors: Kreuzberg Karlheinz , Klock Gerd , Grobheiser Dorte 
Published: February 2008

The subcellular distribution of pyruvate‐degrading enzymes has been determined in Chlamydomonas reinhardtii (Dangeard) by protoplast induction with autolysine, dig‐itonin lysis and further fractionation by differential centrifugation using a Percoll cushion. Mitochondrial and plastidic fractions contained intact and physiologically competent organelles ‐ RC 1.7, ADP/O 2.7 and rate of malate oxidation 76 nmol O, (mg protein)‐1min‐1 for mitochondria, CO2; fixation 46.8 μmol (mg Chi)‐1 h‐1 for chloroplasts.Results from protoplast fractionation were further confirmed by the determination of enzyme activities within trypsin‐treated organelles. Mitochondria (formate fermentation) and chloroplasts (chlorofermentation) were shown to possess the capacity for anaerobic pyruvate degradation. Pyruvate dehydrogenase (NAD+, EC 1.2.4.1), pyruvate formate‐lyase (EC 2.3.1.54) and lactate dehydrogenase (NADH, EC 1.1.1.27) showed equal distribution between mitochondria and chloroplasts, whereas activities of phosphotransacetylase (EC 2.3.1.8) and acetate kinase (EC 2.7.2.1) were only detectable in the mitochondrial fraction. NADH‐ and NADPH‐dependent activities of both alcohol dehydrogenase (EC 1.1.1.1) and aldehyde dehydrogenase (acylating, EC 1.2.1.10) were localized in the mitochondrial and cytoplasmic or the plastidic and cytoplasmic fractions, respectively, whereas pyruvate decarboxylase (EC 4.1.1.1) was only detected in the cytoplasmic fraction.