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991.
Alla Shvaleva Filipe Costa e Silva Joaquim Miguel Costa Alexandra Correia Margaret Anderson Raquel Lobo-do-Vale David Fangueiro Catarina Bicho João Santos Pereira Maria Manuela Chaves Ute Skiba Cristina Cruz 《Plant and Soil》2014,374(1-2):883-898
Background and aims
During the recent decades, cork oak (Q. suber) mortality has been increasing in Mediterranean oak woodland endangering the economical and environmental sustainability of the “montado” ecosystem. This fact in combination with climate change and conversion of forestland to pasture may significantly affect the soil-atmosphere greenhouse gases (GHGs) exchange. Our study evaluates the impact of oak trees as compared to pasture on net ecosystem GHG (CH4, N2O, and CO2) exchange as well as the main environmental factors influencing this exchange.Methods
We used field chamber measurements for the collection of GHGs under three different conditions: 1) open area (OA), 2) under tree canopy area (UC) and 3) improved pasture (IP). Experiments were done under typical Mediterranean climate at central Portugal in 2010 and 2011.Results
The UC had higher nitrification potential, soil C/N ratio, electrical conductivity, litter input and soil organic matter (SOM) than OA and IP. SOM positively correlated with soil CH4 and N2O fluxes but not with soil CO2 respiration rates. Soil water content (SWC) drives both CH4 and N2O fluxes. Under certain conditions, when SWC reached a threshold (7 % for CH4 and 3 % for N2O) the result was net uptake and that net uptake increased with SWC. This was the case for the UC and OA. Conversely, for the IP soil water content above 4 % promoted net CH4 release.Conclusions
Our results show that cork oak influences soil properties and consequently GHGs fluxes. In the UC the input of litter for SOM together with soil moisture, favoured microbiological activity and related GHGs fluxes. Soil temperature is a secondary factor in the studied conditions. Our results also emphasized the potential impact posed by decreased cork oak tree density in the functioning of the “montado” ecosystem. 相似文献992.
Ralph Ewald Christiane Hoffmann Alexandra Florian Ekkehard Neuhaus Alisdair R. Fernie Hermann Bauwe 《Plant physiology》2014,165(3):978-990
Prosthetic lipoyl groups are required for the function of several essential multienzyme complexes, such as pyruvate dehydrogenase (PDH), α-ketoglutarate dehydrogenase (KGDH), and the glycine cleavage system (glycine decarboxylase [GDC]). How these proteins are lipoylated has been extensively studied in prokaryotes and yeast (Saccharomyces cerevisiae), but little is known for plants. We earlier reported that mitochondrial fatty acid synthesis by ketoacyl-acyl carrier protein synthase is not vital for protein lipoylation in Arabidopsis (Arabidopsis thaliana) and does not play a significant role in roots. Here, we identify Arabidopsis lipoate-protein ligase (AtLPLA) as an essential mitochondrial enzyme that uses octanoyl-nucleoside monophosphate and possibly other donor substrates for the octanoylation of mitochondrial PDH-E2 and GDC H-protein; it shows no reactivity with bacterial and possibly plant KGDH-E2. The octanoate-activating enzyme is unknown, but we assume that it uses octanoyl moieties provided by mitochondrial β-oxidation. AtLPLA is essential for the octanoylation of PDH-E2, whereas GDC H-protein can optionally also be octanoylated by octanoyltransferase (LIP2) using octanoyl chains provided by mitochondrial ketoacyl-acyl carrier protein synthase to meet the high lipoate requirement of leaf mesophyll mitochondria. Similar to protein lipoylation in yeast, LIP2 likely also transfers octanoyl groups attached to the H-protein to KGDH-E2 but not to PDH-E2, which is exclusively octanoylated by LPLA. We suggest that LPLA and LIP2 together provide a basal protein lipoylation network to plants that is similar to that in other eukaryotes.Lipoic acid (LA; 6,8-dithiooctanoic acid) prosthetic groups are essential for the catalytic activity of four important multienzyme complexes in plants and other organisms: pyruvate dehydrogenase (PDH), α-ketoglutarate dehydrogenase (KGDH), branched-chain α-ketoacid dehydrogenase (BCDH), and the Gly cleavage system (glycine decarboxylase [GDC]; Perham, 2000; Douce et al., 2001; Mooney et al., 2002). In all these multienzyme complexes, LA is covalently attached to the ε-amino group of a particular lysyl residue of the respective protein subunit. Lipoylated E2 subunits of PDH, KGDH, and BCDH are dihydrolipoyl acyltransferases that interact with E1 and E3 subunits to pass acyl intermediates to CoA (Mooney et al., 2002). By contrast, the lipoylated H-protein of GDC acts as a cosubstrate of three other GDC proteins and has no enzymatic activity itself (Douce et al., 2001). In the course of their respective reaction cycles, LA becomes reduced to dihydrolipoic acid. Most of these enzymes are confined to the mitochondrion. As the only exception, PDH is also present in plastids, where it provides acetyl-CoA for fatty acid biosynthesis (Ohlrogge et al., 1979; Lernmark and Gardeström, 1994; Lin et al., 2003).Mitochondria and plastids each have their own route of de novo LA synthesis, both of which start with the synthesis of protein-bound octanoyl chains (Shimakata and Stumpf, 1982; Ohlrogge and Browse, 1995; Wada et al., 1997; Gueguen et al., 2000; Yasuno et al., 2004). These octanoyl moieties are passed on by organelle-specific octanoyltransferases (Wada et al., 2001a, 2001b) to the respective target apoproteins where lipoyl synthase (LIP1) inserts two sulfur atoms to finally produce functional lipoyl groups (Yasuno and Wada, 1998, 2002; Zhao et al., 2003). A similar pathway has been identified in mammalian mitochondria (Morikawa et al., 2001; Witkowski et al., 2007). In quantitative terms, leaf mesophyll mitochondria have an extraordinarily high requirement for lipoate, because they contain very large amounts of GDC to catalyze the photorespiratory Gly-to-Ser conversion (Bauwe et al., 2010). For this reason, leaf mesophyll mitochondria are the major site of LA synthesis in plants (Wada et al., 1997).It was thought that the octanoyl chains provided by mitochondrial β-ketoacyl-acyl carrier protein synthase (mtKAS) represent the solitary source for protein lipoylation in plant mitochondria (Yasuno et al., 2004). As we reported earlier, however, leaves of mtKAS-deficient knockout mutants show considerable lipoylation of mitochondrial PDH-E2 and KGDH-E2 subunits and some residual lipoylation of GDC H-protein; roots are not at all impaired. Accordingly, the phenotype of such mutants can be fully cured in the low-photorespiratory condition of elevated CO2 (Ewald et al., 2007). These observations indicated that plant mitochondria, in addition to the mtKAS-LIP2-LIP1 route of protein lipoylation, can resort to an alternative pathway. This would not be uncommon. In Escherichia coli, for example, a salvage pathway utilizes free octanoate or LA in an ATP-dependent two-step reaction catalyzed by the bifunctional enzyme lipoate-protein ligase A (LPLA; Morris et al., 1995). Archaea (Christensen and Cronan, 2009; Posner et al., 2009) and vertebrates (Tsunoda and Yasunobu, 1967) require two separate enzymes to first activate octanoate or LA to lipoyl-nucleoside monophosphate (NMP) and then, in a second step, to convey the activated lipoyl group to the respective target proteins. The lipoate-activating enzyme (LAE) of mammals was identified as a refunctioned medium-chain acyl-CoA synthetase that utilizes GTP to produce lipoyl-GMP (Fujiwara et al., 2001). LIP3 from yeast (Saccharomyces cerevisiae) can use octanoyl-CoA to octanoylate apoE2 proteins (Hermes and Cronan, 2013), whereas octanoyl groups from fatty acid biosynthesis are first attached to H-protein and then passed on to apoE2 proteins (Schonauer et al., 2009).The physiological significance of lipoyl-protein ligases in plants is not exactly known. Such enzymes do not operate in plastids (Ewald et al., 2014) but could be present in mitochondria. A single-gene-encoded LPLA with predicted mitochondrial localization has been identified in rice (Oryza sativa; Kang et al., 2007). Complementation studies with the lipoylation-deficient E. coli mutant TM137 (Morris et al., 1995) suggested that OsLPLA belongs to the bifunctional type of LPLAs. We report the identification of the homologous enzyme in Arabidopsis (Arabidopsis thaliana), provide evidence for its mitochondrial location, and show that Arabidopsis LPLA requires a separate enzyme for octanoate/lipoate activation. We also examine the interplay between LPLA, LIP2, and the mtKAS route of protein lipoylation and suggest a model for protein lipoylation in plant mitochondria. 相似文献
993.
Ibraheem Adetunji Glenda Willems Hendrik Tschoep Alexandra Bürkholz Steve Barnes Martin Boer Marcos Malosetti Stefaan Horemans Fred van Eeuwijk 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2014,127(3):559-571
Key message
Linkage disequilibrium decay in sugar beet is strongly affected by the breeding history, and varies extensively between and along chromosomes, allowing identification of known and unknown signatures of selection.Abstract
Genetic diversity and linkage disequilibrium (LD) patterns were investigated in 233 elite sugar beet breeding lines and 91 wild beet accessions, using 454 single nucleotide polymorphisms (SNPs) and 418 SNPs, respectively. Principal coordinate analysis suggested the existence of three groups of germplasm, corresponding to the wild beets, the seed parent and the pollen parent breeding pool. LD was investigated in each of these groups, with and without correction for genetic relatedness. Without correction for genetic relatedness, in the pollen as well as the seed parent pool, LD persisted beyond 50 centiMorgan (cM) on four (2, 3, 4 and 5) and three chromosomes (2, 4 and 6), respectively; after correction for genetic relatedness, LD decayed after <6 cM on all chromosomes in both pools. In the wild beet accessions, there was a strong LD decay: on average LD disappeared after 1 cM when LD was calculated with a correction for genetic relatedness. Persistence of LD was not only observed between distant SNPs on the same chromosome, but also between SNPs on different chromosomes. Regions on chromosomes 3 and 4 that harbor disease resistance and monogermy loci showed strong genetic differentiation between the pollen and seed parent pools. Other regions, on chromosomes 8 and 9, for which no a priori information was available with respect to their contribution to the phenotype, still contributed to clustering of lines in the elite breeding material. 相似文献994.
Romy Hribal Alexandra Hachen Katarina JewgenowJennifer Zahmel Lorena Fernandez-GonzalezBeate C. Braun 《Theriogenology》2014
Oviductin is known to be a key player providing a convenient environment for the process of fertilization affecting this by direct interaction with oocytes and sperm. As in vitro embryo production in the context of assisted reproduction for endangered felids is still in the process of optimization, oviductin might be used to improve IVF results. Recombinant His-tagged feline oviductin was expressed by transformed Escherichia coli BL21DE3 cells. The protein was purified by immobilized metal ion affinity chromatography. The effect of the recombinant protein was characterized in three experiments: a hemizona assay for sperm binding analysis, the IVF outcome, and the relative mRNA expression levels in blastocysts after IVF. A significant higher number of bound sperm cells were found after incubation in oviductin. No significant effect on cleavage, morula, and blastocyst rates with or without oviductin incubation during IVF could be observed. However, the relative mRNA abundance of GJA1, a gene, whose expression level is known to be a marker of embryo quality, was significantly increased (P value less than 0.05) in blastocysts after oviductin treatment. In contrast to this, expression of OCT4, HSP70, DNMT1, DNMT3A, BAX, IGF1R, and GAPDH was not significantly affected. We assume that our recombinant oviductin in its current nonglycosylated form is able to enhance sperm binding. Despite of a missing significant effect on IVF outcome, embryo quality in terms of relative GJA1 expression is influenced positively. These promising results demonstrate the value of recombinant oviductin for the IVF in cats. 相似文献
995.
Chartier-Harlin MC Dachsel JC Vilariño-Güell C Lincoln SJ Leprêtre F Hulihan MM Kachergus J Milnerwood AJ Tapia L Song MS Le Rhun E Mutez E Larvor L Duflot A Vanbesien-Mailliot C Kreisler A Ross OA Nishioka K Soto-Ortolaza AI Cobb SA Melrose HL Behrouz B Keeling BH Bacon JA Hentati E Williams L Yanagiya A Sonenberg N Lockhart PJ Zubair AC Uitti RJ Aasly JO Krygowska-Wajs A Opala G Wszolek ZK Frigerio R Maraganore DM Gosal D Lynch T Hutchinson M Bentivoglio AR Valente EM Nichols WC Pankratz N 《American journal of human genetics》2011,(3):140-406
Genome-wide analysis of a multi-incident family with autosomal-dominant parkinsonism has implicated a locus on chromosomal region 3q26-q28. Linkage and disease segregation is explained by a missense mutation c.3614G>A (p.Arg1205His) in eukaryotic translation initiation factor 4-gamma (EIF4G1). Subsequent sequence and genotype analysis identified EIF4G1 c.1505C>T (p.Ala502Val), c.2056G>T (p.Gly686Cys), c.3490A>C (p.Ser1164Arg), c.3589C>T (p.Arg1197Trp) and c.3614G>A (p.Arg1205His) substitutions in affected subjects with familial parkinsonism and idiopathic Lewy body disease but not in control subjects. Despite different countries of origin, persons with EIF4G1 c.1505C>T (p.Ala502Val) or c.3614G>A (p.Arg1205His) mutations appear to share haplotypes consistent with ancestral founders. eIF4G1 p.Ala502Val and p.Arg1205His disrupt eIF4E or eIF3e binding, although the wild-type protein does not, and render mutant cells more vulnerable to reactive oxidative species. EIF4G1 mutations implicate mRNA translation initiation in familial parkinsonism and highlight a convergent pathway for monogenic, toxin and perhaps virally-induced Parkinson disease. 相似文献
996.
Bounaix Morand du Puch C Barbier E Kraut A Couté Y Fuchs J Buhot A Livache T Sève M Favier A Douki T Gasparutto D Sauvaigo S Breton J 《Archives of biochemistry and biophysics》2011,(2):296-303
Platinating agents are commonly prescribed anticancer drugs damaging DNA. Induced lesions are recognized by a wide range of proteins. These are involved in cellular mechanisms such as DNA repair, mediation of cytotoxicity or chromatin remodeling. They therefore constitute crucial actors to understand pharmacology of these drugs. To expand our knowledge about this subproteome, we developed a ligand fishing trap coupled to high throughput proteomic tools. This trap is made of damaged plasmids attached to magnetic beads, and was exposed to cell nuclear extracts. Retained proteins were identified by nanoHPLC coupled to tandem mass spectrometry. This approach allowed us to establish a list of 38 proteins interacting with DNA adducts generated by cisplatin, oxaliplatin and satraplatin. Some of them were already known interactome members like high mobility group protein 1 (HMGB1) or the human upstream binding factor (hUBF), but we also succeeded in identifying unexpected proteins such as TOX HMG box family member 4 (TOX4), phosphatase 1 nuclear targeting subunit (PNUTS), and WD repeat-containing protein 82 (WDR82), members of a recently discovered complex. Interaction between TOX4 and platinated DNA was subsequently validated by surface plasmon resonance imaging (SPRi). These interactions highlight new cellular responses to DNA damage induced by chemotherapeutic agents. 相似文献
997.
Alexandra ?imonovi?ov Domenico Pangallo Katarína Chovanová Blanka Lehotská 《Biologia》2011,66(3):562-564
The paper describes macro- and micromorphological features of Geomyces destructans, the fungus which is associated with the white-nose syndrome (WNS) bat disease in North America. This species was isolated
from hibernating Myotis myotis at two sites in Malé Karpaty Mts (the old mine Pod medveđou skalou and the Zbojnícka Cave) in Western Slovakia. Besides Geomyces destructans, the species Isaria farinosa, Cladosporium macrocarpum and Alternaria tenuissima were isolated, too. All strains are deposed at the Department of Soil Science, Comenius University in Bratislava (Slovakia)
and in CMF at Institute of Soil Biology in Českějovice (Czech Republic). 相似文献
998.
Martinez Benitez E Stolz A Becher A Wolf DH 《Biochemical and biophysical research communications》2011,(3):528-532
In eukaryotes, membrane and soluble proteins of the secretory pathway enter the endoplasmic reticulum (ER) after synthesis in an unfolded state. Directly after entry, most proteins are modified with glycans at suitable glycosylation sites and start to fold. A protein that cannot fold properly will be degraded in a process called ER associated degradation (ERAD). Failures in ERAD, either by loss of function or by premature degradation of proteins, are a cause of severe diseases. Therefore, the search for novel ERAD components to gain better insight in this process is of high importance. Carbohydrate trimming is a relevant process in ER quality control. In this work a novel putative yeast mannosidase encoded by the open reading frame YLR057W was identified and named Mnl2. Deletion of MNL2 diminished the degradation efficiency of misfolded CPY* in the absence of the cognate mannosidase Mnl1, indicating a specific role in ERAD. 相似文献
999.
Neundlinger I Poturnayova A Karpisova I Rankl C Hinterdorfer P Snejdarkova M Hianik T Ebner A 《Biophysical journal》2011,(7):1781-1787
Thrombin aptamer binding strength and stability is dependent on sterical parameters when used for atomic force microscopy sensing applications. Sterical improvements on the linker chemistry were developed for high-affinity binding. For this we applied single molecule force spectroscopy using two enhanced biotinylated thrombin aptamers, BFF and BFA immobilized on the atomic force microscopy tip via streptavidin. BFF is a dimer composed of two single-stranded aptamers (aptabody) connected to each other by a complementary sequence close to the biotinylated end. In contrast, BFA consists of a single DNA strand and a complementary strand in the supporting biotinylated part. By varying the pulling velocity in force-distance cycles the formed thrombin-aptamer complexes were ruptured at different force loadings allowing determination of the energy landscape. As a result, BFA aptamer showed a higher binding force at the investigated loading rates and a significantly lower dissociation rate constant, koff, compared to BFF. Moreover, the potential of the aptabody BFF to form a bivalent complex could clearly be demonstrated. 相似文献
1000.
We studied force-induced elongation of filopodia by coupling magnetic tweezers to the tip through the bacterial coat protein invasin, which couples the force generator to the actin bundles (through myosin X), thus impeding the growth of the actin plus end. Single force pulses (15–30 s) with amplitudes between 20 and 600 pN and staircase-like force scenarios (amplitudes, ∼50 pN; step widths, 30 s) were applied. In both cases, the responses consist of a fast viscoelastic deflection followed by a linear flow regime. The deflections are reversible after switching off the forces, suggesting a mechanical memory. The elongation velocity exhibits an exponential distribution (half-width <v1/2>, ∼0.02 μm s−1) and did not increase systematically with the force amplitudes. We estimate the bending modulus (0.4 × 10−23 J m) and the number of actin filaments (∼10) by analyzing filopodium bending fluctuations. Sequestering of intracellular Ca2+ by BAPTA caused a strong reduction in the amplitude of elongation, whereas latrunculin A resulted in loss of the elastic response. We attribute the force-independent velocity to the elongation of actin bundles enabled by the force-induced actin membrane uncoupling and the reversibility by the treadmilling mechanism and an elastic response. 相似文献