bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endothelin‐1 is secreted after total knee arthroplasty regardless of the use of a tourniquet
Authors: Matziolis G. , Drahn T. , Schröder J. H. , Krocker D. , Tuischer J. , Perka C. 
Published: January 2005

AbstractEarly infections and wound healing disorders after implantation of a total knee replacement occur regardless of the intraoperative use of a tourniquet. The biochemical regulatory processes responsible for the disturbances in microcirculation and thus the potential therapeutic options have yet to be elucidated. The hypothesis of the present paper was that endothelin‐1 (ET‐1), a mediator of microcirculation disturbances in parenchymatous organs, also is released after major operations on peripheral joints.The concentration of ET‐1 in the plasma was determined preoperatively and at 10 postoperative time points (5 min–48h) with (group A, n = 10) and without the use of a tourniquet (group B, n = 10). The ET‐1 concentration achieved its maximum 6h after opening the tourniquet, which corresponded to 3.3 times the preoperative value. Without a tourniquet, the concentration maximum (2.9 times the baseline value) was achieved already 1.5 h after the end of the operation. However, the total amount of ET‐1 secreted over 24 h was identical in both groups (p > 0.5).We conclude that the tissue hypoxia resulting from the use of a tourniquet modulates ET‐1 secretion, but that traumatization during the operation has a much stronger influence on the total amount secreted.ET‐1 antagonists thus should be discussed for the drug prophylaxis of wound healing disorders, regardless of the use of a tourniquet. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Wound-Inducible Biosynthesis of Phytoalexin Hydroxycinnamic Acid Amides of Tyramine in Tryptophan and Tyrosine Decarboxylase Transgenic Tobacco Lines
Authors: Guillet Gabriel , De Luca Vincenzo 
Published: January 2005

Abstract
The wound-activated biosynthesis of phytoalexin hydroxycinnamic acid amides of tyramine was compared in untransformed and transgenic tobacco (Nicotiana tabacum) lines that express tryptophan decarboxylase (TDC), tyrosine decarboxylase (TYDC), or both activities. Transgenic in vitro-grown tobacco lines expressing TDC activity accumulated high levels of tryptamine but not hydroxycinnamic amides of tryptamine. In contrast, transgenic tobacco lines expressing TYDC accumulated tyramine as well as p-coumaroyltyramine and feruloyltyramine. The MeOH-soluble and cell wall fractions showed higher concentrations of wound-inducible p-coumaroyltyramine and feruloyltyramine, especially at and around wound sites, in TYDC and TDC ×TYDC tobacco lines compared to wild-type or TDC lines. All the enzymes involved in the biosynthesis of hydroxycinnamic acid amides of tyramine were found to be similarly wound inducible in all tobacco genotypes investigated. These results provide experimental evidence that, under some circumstances, TYDC activity can exert a rate-limiting control over the carbon flux allocated to the biosynthesis of hydroxycinnamic acid amides of tyramine.
Functional Genomics of the Regulation of the Nitrate Assimilation Pathway in Chlamydomonas
Authors: González-Ballester David , de Montaigu Amaury , Higuera José Javier , Galván Aurora , Fernández Emilio 
Published: January 2005

Abstract
The existence of mutants at specific steps in a pathway is a valuable tool of functional genomics in an organism. Heterologous integration occurring during transformation with a selectable marker in Chlamydomonas (Chlamydomonas reinhardtii) has been used to generate an ordered mutant library. A strain, having a chimeric construct (pNia1::arylsulfatase gene) as a sensor of the Nia1 gene promoter activity, was transformed with a plasmid bearing the paramomycin resistance AphVIII gene to generate insertional mutants defective at regulatory steps of the nitrate assimilation pathway. Twenty-two thousand transformants were obtained and maintained in pools of 96 for further use. The mutant library was screened for the following phenotypes: insensitivity to the negative signal of ammonium, insensitivity to the positive signal of nitrate, overexpression in nitrate, and inability to use nitrate. Analyses of mutants showed that (1) the number or integrated copies of the gene marker is close to 1; (2) the probability of cloning the DNA region at the marker insertion site is high (76%); (3) insertions occur randomly; and (4) integrations at different positions and orientations of the same genomic region appeared in at least three cases. Some of the mutants analyzed were found to be affected at putative new genes related to regulatory functions, such as guanylate cyclase, protein kinase, peptidyl-prolyl isomerase, or DNA binding. The Chlamydomonas mutant library constructed would also be valuable to identify any other gene with a screenable phenotype.
Tonoplast Intrinsic Proteins AtTIP2;1 and AtTIP2;3 Facilitate NH3 Transport into the Vacuole
Authors: Loqué Dominique , Ludewig Uwe , Yuan Lixing , von Wirén Nicolaus 
Published: January 2005

Abstract
While membrane transporters mediating ammonium uptake across the plasma membrane have been well described at the molecular level, little is known about compartmentation and cellular export of ammonium. (The term ammonium is used to denote both NH3 and NH4 + and chemical symbols are used when specificity is required.) We therefore developed a yeast (Saccharomyces cerevisiae) complementation approach and isolated two Arabidopsis (Arabidopsis thaliana) genes that conferred tolerance to the toxic ammonium analog methylammonium in yeast. Both genes, AtTIP2;1 and AtTIP2;3, encode aquaporins of the tonoplast intrinsic protein subfamily and transported methylammonium or ammonium in yeast preferentially at high medium pH. AtTIP2;1 expression in Xenopus oocytes increased 14C-methylammonium accumulation with increasing pH. AtTIP2;1- and AtTIP2;3-mediated methylammonium detoxification in yeast depended on a functional vacuole, which was in agreement with the subcellular localization of green fluorescent protein-fusion proteins on the tonoplast in planta. Transcript levels of both AtTIPs were influenced by nitrogen supply but did not follow those of the nitrogen-derepressed ammonium transporter gene AtAMT1;1. Transgenic Arabidopsis plants overexpressing AtTIP2;1 did not show altered ammonium accumulation in roots after ammonium supply, although AtTIP2;1 mRNA levels in wild-type plants were up-regulated under these conditions. This study shows that AtTIP2;1 and AtTIP2;3 can mediate the extracytosolic transport of methyl-NH2 and NH3 across the tonoplast membrane and may thus participate in vacuolar ammonium compartmentation.
Comparative Genomics of the Pennate Diatom Phaeodactylum tricornutum
Authors: Montsant Anton , Jabbari Kamel , Maheswari Uma , Bowler Chris 
Published: January 2005

Abstract
Diatoms are one of the most important constituents of phytoplankton communities in aquatic environments, but in spite of this, only recently have large-scale diatom-sequencing projects been undertaken. With the genome of the centric species Thalassiosira pseudonana available since mid-2004, accumulating sequence information for a pennate model species appears a natural subsequent aim. We have generated over 12,000 expressed sequence tags (ESTs) from the pennate diatom Phaeodactylum tricornutum, and upon assembly into a nonredundant set, 5,108 sequences were obtained. Significant similarity (E &lt; 1E-04) to entries in the GenBank nonredundant protein database, the COG profile database, and the Pfam protein domains database were detected, respectively, in 45.0%, 21.5%, and 37.1% of the nonredundant collection of sequences. This information was employed to functionally annotate the P. tricornutum nonredundant set and to create an internet-accessible queryable diatom EST database. The nonredundant collection was then compared to the putative complete proteomes of the green alga Chlamydomonas reinhardtii, the red alga Cyanidioschyzon merolae, and the centric diatom T. pseudonana. A number of intriguing differences were identified between the pennate and the centric diatoms concerning activities of relevance for general cell metabolism, e.g. genes involved in carbon-concentrating mechanisms, cytosolic acetyl-Coenzyme A production, and fructose-1,6-bisphosphate metabolism. Finally, codon usage and utilization of C and G relative to gene expression (as measured by EST redundance) were studied, and preferences for utilization of C and CpG doublets were noted among the P. tricornutum EST coding sequences.
Microarray Analysis Confirms the Specificity of a Chlamydomonas reinhardtii Chloroplast RNA Stability Mutant
Authors: Erickson Brian , Stern David B. , Higgs David C. 
Published: January 2005

Abstract
The expression of chloroplast and mitochondrial genes depends on nucleus-encoded proteins, some of which control processing, stability, and/or translation of organellar RNAs. To test the specificity of one such RNA stability factor, we used two known Chlamydomonas reinhardtii nonphotosynthetic mutants carrying mutations in the Mcd1 nuclear gene (mcd1-1 and mcd1-2). We previously reported that these mutants fail to accumulate the chloroplast petD mRNA and its product, subunit IV of the cytochrome b 6/f complex, which is essential for photosynthesis. Such mutants are generally presumed to be gene specific but are not tested rigorously. Here, we have used microarray analysis to assess changes in chloroplast, mitochondrial, and nuclear RNAs, and since few other RNAs were significantly altered in these mutants, conclude that Mcd1 is indeed specifically required for petD mRNA accumulation. In addition, a new unlinked nuclear mutation was discovered in mcd1-2, which greatly reduced chloroplast atpA mRNA accumulation. Genetic analyses showed failure to complement mda1-ncc1, where atpA-containing transcripts are similarly affected (D. Drapier, J. Girard-Bascou, D.B. Stern, F.-A. Wollman [2002] Plant J 31: 687–697), and we have named this putative new allele mda1-2. We conclude that DNA microarrays are efficient and useful for characterizing the specificity of organellar RNA accumulation mutants.
Beyond Complementation. Map-Based Cloning in Chlamydomonas reinhardtii
Authors: Rymarquis Linda A. , Handley Jocelyn M. , Thomas Mabel , Stern David B. 
Published: January 2005

Abstract
Chlamydomonas reinhardtii is an excellent model system for plant biologists because of its ease of manipulation, facile genetics, and the ability to transform the nuclear, chloroplast, and mitochondrial genomes. Numerous forward genetics studies have been performed in Chlamydomonas, in many cases to elucidate the regulation of photosynthesis. One of the resultant challenges is moving from mutant phenotype to the gene mutation causing that phenotype. To date, complementation has been the primary method for gene cloning, but this is impractical in several situations, for example, when the complemented strain cannot be readily selected or in the case of recessive suppressors that restore photosynthesis. New tools, including a molecular map consisting of 506 markers and an 8X-draft nuclear genome sequence, are now available, making map-based cloning increasingly feasible. Here we discuss advances in map-based cloning developed using the strains mcd4 and mcd5, which carry recessive nuclear suppressors restoring photosynthesis to chloroplast mutants. Tools that have not been previously applied to Chlamydomonas, such as bulked segregant analysis and marker duplexing, are being implemented to increase the speed at which one can go from mutant phenotype to gene. In addition to assessing and applying current resources, we outline anticipated future developments in map-based cloning in the context of the newly extended Chlamydomonas genome initiative.
Faster Rubisco Is the Key to Superior Nitrogen-Use Efficiency in NADP-Malic Enzyme Relative to NAD-Malic Enzyme C4 Grasses
Authors: Ghannoum Oula , Evans John R. , Chow Wah Soon , Andrews T. John , Conroy Jann P. , von Caemmerer Susanne 
Published: January 2005

Abstract
In 27 C4 grasses grown under adequate or deficient nitrogen (N) supplies, N-use efficiency at the photosynthetic (assimilation rate per unit leaf N) and whole-plant (dry mass per total leaf N) level was greater in NADP-malic enzyme (ME) than NAD-ME species. This was due to lower N content in NADP-ME than NAD-ME leaves because neither assimilation rates nor plant dry mass differed significantly between the two C4 subtypes. Relative to NAD-ME, NADP-ME leaves had greater in vivo (assimilation rate per Rubisco catalytic sites) and in vitro Rubisco turnover rates (k cat; 3.8 versus 5.7 s−1 at 25°C). The two parameters were linearly related. In 2 NAD-ME (Panicum miliaceum and Panicum coloratum) and 2 NADP-ME (Sorghum bicolor and Cenchrus ciliaris) grasses, 30% of leaf N was allocated to thylakoids and 5% to 9% to amino acids and nitrate. Soluble protein represented a smaller fraction of leaf N in NADP-ME (41%) than in NAD-ME (53%) leaves, of which Rubisco accounted for one-seventh. Soluble protein averaged 7 and 10 g (mmol chlorophyll)−1 in NADP-ME and NAD-ME leaves, respectively. The majority (65%) of leaf N and chlorophyll was found in the mesophyll of NADP-ME and bundle sheath of NAD-ME leaves. The mesophyll-bundle sheath distribution of functional thylakoid complexes (photosystems I and II and cytochrome f) varied among species, with a tendency to be mostly located in the mesophyll. In conclusion, superior N-use efficiency of NADP-ME relative to NAD-ME grasses was achieved with less leaf N, soluble protein, and Rubisco having a faster k cat.
Alterations in Tocopherol Cyclase Activity in Transgenic and Mutant Plants of Arabidopsis Affect Tocopherol Content, Tocopherol Composition, and Oxidative Stress
Authors: Kanwischer Marion , Porfirova Svetlana , Bergmüller Eveline , Dörmann Peter 
Published: January 2005

Abstract
Tocopherol belongs to the Vitamin E class of lipid soluble antioxidants that are essential for human nutrition. In plants, tocopherol is synthesized in plastids where it protects membranes from oxidative degradation by reactive oxygen species. Tocopherol cyclase (VTE1) catalyzes the penultimate step of tocopherol synthesis, and an Arabidopsis (Arabidopsis thaliana) mutant deficient in VTE1 (vte1) is totally devoid of tocopherol. Overexpression of VTE1 resulted in an increase in total tocopherol of at least 7-fold in leaves, and a dramatic shift from α-tocopherol to γ-tocopherol. Expression studies demonstrated that indeed VTE1 is a major limiting factor of tocopherol synthesis in leaves. Tocopherol deficiency in vte1 resulted in the increase in ascorbate and glutathione, whereas accumulation of tocopherol in VTE1 overexpressing plants led to a decrease in ascorbate and glutathione. Deficiency in one antioxidant in vte1, vtc1 (ascorbate deficient), or cad2 (glutathione deficient) led to increased oxidative stress and to the concomitant increase in alternative antioxidants. Double mutants of vte1 were generated with vtc1 and cad2. Whereas growth, chlorophyll content, and photosynthetic quantum yield were very similar to wild type in vte1, vtc1, cad2, or vte1vtc1, they were reduced in vte1cad2, indicating that the simultaneous loss of tocopherol and glutathione results in moderate oxidative stress that affects the stability and the efficiency of the photosynthetic apparatus.
Multiple Protein Regions Contribute to Differential Activities of YABBY Proteins inReproductive Development
Authors: Meister Robert J. , Oldenhof Harriette , Bowman John L. , Gasser Charles S. 
Published: January 2005

Abstract
Members of the YABBY family of putative transcription factors participate in abaxial-adaxial identity determination in lateral organs in Arabidopsis (Arabidopsis thaliana). Two YABBY genes specifically expressed in reproductive structures, CRABS CLAW (CRC) and INNER NO OUTER (INO), have additional activities, with CRC promoting nectary development and carpel fusion, and INO responding to spatial regulation by SUPERMAN during ovule development. All YABBY coding regions, except YABBY5, were able to restore outer integument growth in ino-1 mutants when expressed from the INO promoter (PRO INO). However, INO was the only YABBY family member that responded correctly to SUPERMAN to maintain the wild-type gynoapical-gynobasal asymmetry of the outer integument. By contrast, INO, FILAMENTOUS FLOWER, and YABBY3 failed to complement crc-1 when expressed from PRO CRC. Roles of individual regions of CRC and INO in these effects were assessed using chimeric proteins with PRO INO and PRO CRC and the relatively constitutive cauliflower mosaic virus PRO35S. Regions of CRC were found to contribute additively to CRC-specific functions in nectary and carpel formation, with a nearly direct relationship between the amount of CRC included and the degree of complementation of crc-1. When combined with INO sequences, the central and carboxyl-terminal regions of CRC were individually sufficient to overcome inhibitory effects of SUPERMAN within the outer integument. Reproductive phenotypes resulting from constitutive expression were dependent on the nature of the central region with some contributions from the amino terminus. Thus, the YABBY family members have both unique and common functional capacities, and residues involved in differential activities are distributed throughout the protein sequences.
Enhanced Photosynthetic Performance and Growth as a Consequence of Decreasing Mitochondrial Malate Dehydrogenase Activity in Transgenic Tomato Plants
Authors: Nunes-Nesi Adriano , Carrari Fernando , Lytovchenko Anna , Smith Anna M.O. , Ehlers Loureiro Marcelo , Ratcliffe R. George , Sweetlove Lee J. , Fernie Alisdair R. 
Published: January 2005

Abstract
Transgenic tomato (Solanum lycopersicum) plants expressing a fragment of the mitochondrial malate dehydrogenase gene in the antisense orientation and exhibiting reduced activity of this isoform of malate dehydrogenase show enhanced photosynthetic activity and aerial growth under atmospheric conditions (360 ppm CO2). In comparison to wild-type plants, carbon dioxide assimilation rates and total plant dry matter were up to 11% and 19% enhanced in the transgenics, when assessed on a whole-plant basis. Accumulation of carbohydrates and redox-related compounds such as ascorbate was also markedly elevated in the transgenics. Also increased in the transgenic plants was the capacity to use l-galactono-lactone, the terminal precursor of ascorbate biosynthesis, as a respiratory substrate. Experiments in which ascorbate was fed to isolated leaf discs also resulted in increased rates of photosynthesis providing strong indication for an ascorbate-mediated link between the energy-generating processes of respiration and photosynthesis. This report thus shows that the repression of this mitochondrially localized enzyme improves both carbon assimilation and aerial growth in a crop species.
Arabidopsis Sphingosine Kinase and the Effects of Phytosphingosine-1-Phosphate on Stomatal Aperture
Authors: Coursol Sylvie , Le Stunff Hervé , Lynch Daniel V. , Gilroy Simon , Assmann Sarah M. , Spiegel Sarah 
Published: January 2005

Abstract
Sphingolipids are a major component of membrane lipids and their metabolite sphingosine-1-phosphate (S1P) is a potent lipid mediator in animal cells. Recently, we have shown that the enzyme responsible for S1P production, sphingosine kinase (SphK), is stimulated by the phytohormone abscisic acid in guard cells of Arabidopsis (Arabidopsis thaliana) and that S1P is effective in regulating guard cell turgor. We have now characterized SphK from Arabidopsis leaves. SphK activity was mainly associated with the membrane fraction and phosphorylated predominantly the Δ4-unsaturated long-chain sphingoid bases sphingosine (Sph) and 4,8-sphingadienine, and to a lesser extent, the saturated long-chain sphingoid bases dihydrosphingosine and phytosphingosine (Phyto-Sph). 4-Hydroxy-8-sphingenine, which is a major sphingoid base in complex glycosphingolipids from Arabidopsis leaves, was a relatively poor substrate compared with the corresponding saturated Phyto-Sph. In contrast, mammalian SphK1 efficiently phosphorylated Sph, dihydrosphingosine, and 4,8-sphingadienine, but not the 4-hydroxylated long-chain bases Phyto-Sph and 4-hydroxy-8-sphingenine. Surface dilution kinetic analysis of Arabidopsis SphK with Sph presented in mixed Triton X-100 micelles indicated that SphK associates with the micellar surface and then with the substrate presented on the surface. In addition, measurements of SphK activity under different assay conditions combined with phylogenetic analysis suggest that multiple isoforms of SphK may be expressed in Arabidopsis. Importantly, we found that phytosphingosine-1-phosphate, similar to S1P, regulates stomatal apertures and that its action is impaired in guard cells of Arabidopsis plants harboring T-DNA null mutations in the sole prototypical G-protein α-subunit gene, GPA1.
β-Maltose Is the Metabolically Active Anomer of Maltose during Transitory Starch Degradation
Authors: Weise Sean E. , Kim Kirsten S. , Stewart Robert P. , Sharkey Thomas D. 
Published: January 2005

Abstract
Maltose is the major form of carbon exported from the chloroplast at night as a result of transitory starch breakdown. Maltose exists as an α- or β-anomer. We developed an enzymatic technique for distinguishing between the two anomers of maltose and tested the accuracy and specificity of this technique using β-maltose liberated from maltoheptose by β-amylase. This technique was used to investigate which form of maltose is present during transitory starch degradation in bean (Phaseolus vulgaris), wild-type Arabidopsis (Arabidopsis thaliana), two starch deficient Arabidopsis lines, and one starch-excess mutant of Arabidopsis. In Phaseolus and wild-type Arabidopsis, β-maltose levels were low during the day but were much higher at night. In Arabidopsis plants unable to metabolize maltose due to a T-DNA insertion in the gene for the cytosolic amylomaltase, (Y. Lu, T.D. Sharkey [2004] Planta 218: 466–473) levels of α- and β-maltose were high during both the day and night. In starchless mutants of Arabidopsis, total maltose levels were low and almost completely in the α-form. We also found that the subcellular concentration of β-maltose at night was greater in the chloroplast than in the cytosol by 278 μ m. We conclude that β-maltose is the metabolically active anomer of maltose and that a sufficient gradient of β-maltose exists between the chloroplast and cytosol to allow for passive transport of maltose out of chloroplasts at night.