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491.
492.
Rasmussen MA Madsen SM Stougaard P Johnsen MG 《Applied and environmental microbiology》2008,74(22):7070-7072
Secretion of beta-1,3-glucanases by the arctic bacterial isolates 4221 and 4236, related to the genera Flavobacterium and Pedobacter, was discovered. Escherichia coli and Lactococcus lactis expression of beta-1,3-glucanases Glc4221-1 and Glc4236-1 from the respective isolates was achieved. The enzymes hydrolyzed fungal cell walls and retained activity at low temperatures. 相似文献
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Succession of Indigenous Pseudomonas spp. and Actinomycetes on Barley Roots Affected by the Antagonistic Strain Pseudomonas fluorescens DR54 and the Fungicide Imazalil 下载免费PDF全文
In recent years, the interest in the use of bacteria for biological control of plant-pathogenic fungi has increased. We studied the possible side effects of coating barley seeds with the antagonistic strain Pseudomonas fluorescens DR54 or a commercial fungicide, imazalil. This was done by monitoring the number of indigenous Pseudomonas organisms and actinomycetes on barley roots during growth in soil, harvest after 50 days, and subsequent decomposition. Bacteria were enumerated by traditional plate spreading on Gould's S1 agar (Pseudomonas) and as filamentous colonies on Winogradsky agar (actinomycetes) and by two quantitative competitive PCR assays. For this we developed an assay targeting Streptomyces and closely related genera. DR54 constituted more than 75% of the Pseudomonas population at the root base during the first 21 days but decreased to less than 10% at day 50. DR54 was not successful in colonizing root tips. Initially, DR54 affected the number of indigenous Pseudomonas organisms negatively, whereas imazalil affected Pseudomonas numbers positively, but the effects were transient. Although plate counts were considerably lower than the number of DNA copies, the two methods correlated well for Pseudomonas during plant growth, but after plant harvest Pseudomonas-specific DNA copy numbers decreased while plate counts were in the same magnitude as before. Hence, Pseudomonas was 10-fold more culturable in a decomposition environment than in the rhizosphere. The abundance of actinomycetes was unaffected by DR54 or imazalil amendments, and CFU and quantitative PCR results correlated throughout the experiment. The abundance of actinomycetes increased gradually, mostly in numbers of DNA copies, confirming their role in colonizing old roots. 相似文献
495.
Plant growth and adaptation to cold and freezing temperatures in a CO2 -enriched atmosphere have received little attention despite their predicted effects on plant distribution and productivity. In this study we looked at the interaction between elevated CO2 and development of freezing tolerance in Norway spruce ( Picea abies (L.) Karst.). First-year seedlings were grown under controlled conditions in an atmosphere enriched in CO2 (70 Pa) for one simulated growth season. We measured shoot growth, registered the timing of growth cessation and bud set, measured needle net photosynthetic rate, and determined needle carbohydrate concentration (fructose+pinitol, glucose, sucrose, inositol, raffinose and starch). Freezing tolerance (LT50 ) was determined after exposing whole seedlings to temperatures ranging from −6.5 to −36.0°C and scoring for visual needle browning. Elevated CO2 did not affect height growth or the timing of growth cessation and bud set. The only statistically significant effects of CO2 treatment were on seedling dry weight, percent dry matter and starch content. During the three weeks after growth cessation and bud set, freezing tolerance increased from −10 to −35°C, and there was a marked increase in all soluble sugars except inositol. However, neither freezing tolerance nor the concentration of soluble sugars was significantly influenced by elevated CO2 . 相似文献
496.
Elsa Sverrisdóttir Stephen Byrne Ea Høegh Riis Sundmark Heidi Øllegaard Johnsen Hanne Grethe Kirk Torben Asp Luc Janss Kåre L. Nielsen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(10):2091-2108
Key message
Genomic prediction models for starch content and chipping quality show promising results, suggesting that genomic selection is a feasible breeding strategy in tetraploid potato.Abstract
Genomic selection uses genome-wide molecular markers to predict performance of individuals and allows selections in the absence of direct phenotyping. It is regarded as a useful tool to accelerate genetic gain in breeding programs, and is becoming increasingly viable for crops as genotyping costs continue to fall. In this study, we have generated genomic prediction models for starch content and chipping quality in tetraploid potato to facilitate varietal development. Chipping quality was evaluated as the colour of a potato chip after frying following cold induced sweetening. We used genotyping-by-sequencing to genotype 762 offspring, derived from a population generated from biparental crosses of 18 tetraploid parents. Additionally, 74 breeding clones were genotyped, representing a test panel for model validation. We generated genomic prediction models from 171,859 single-nucleotide polymorphisms to calculate genomic estimated breeding values. Cross-validated prediction correlations of 0.56 and 0.73 were obtained within the training population for starch content and chipping quality, respectively, while correlations were lower when predicting performance in the test panel, at 0.30–0.31 and 0.42–0.43, respectively. Predictions in the test panel were slightly improved when including representatives from the test panel in the training population but worsened when preceded by marker selection. Our results suggest that genomic prediction is feasible, however, the extremely high allelic diversity of tetraploid potato necessitates large training populations to efficiently capture the genetic diversity of elite potato germplasm and enable accurate prediction across the entire spectrum of elite potatoes. Nonetheless, our results demonstrate that GS is a promising breeding strategy for tetraploid potato.497.
Mia Roest Laursen Jakob Hansen Casper Elkjær Ninna Stavnager Camilla Bak Nielsen Kasper Pryds Jacob Johnsen Jan Møller Nielsen Hans Erik Bøtker Mogens Johannsen 《Metabolomics : Official journal of the Metabolomic Society》2017,13(6):67
Introduction
Remote ischemic conditioning (RIC) is a maneuver by which short non-lethal ischemic events are applied on distant organs or limbs to reduce ischemia and reperfusion injuries caused by e.g. myocardial infarct. Although intensively investigated, the specific mechanism of this protective phenomenon remains incompletely understood and in particular, knowledge on the role of small metabolites is scarce.Objectives
In this study, we aimed to study perturbations in the plasma metabolome following RIC and gain insight into metabolic changes by the intervention as well as to identify potential novel cardio-protective metabolites.Methods
Blood plasma samples from ten healthy males were collected prior to and after RIC and tested for bioactivity in a HL-1 based cellular model of ischemia–reperfusion damage. Following this, the plasma was analyzed using untargeted LC-qTOF-MS and regulated metabolites were identified using univariate and multivariate statistical analysis. Results were finally verified in a second plasma study from the same group of volunteers and by testing a metabolite ester in the HL-1 cell model.Results
The analysis revealed a moderate impact on the plasma metabolome following RIC. One metabolite, α-hydroxybutyrate (AHB) however, stood out as highly significantly upregulated after RIC. AHB might be a novel and more sensitive plasma-biomarker of transient tissue ischemia than lactate. Importantly, it was also found that a cell permeable AHB precursor protects cardiomyocytes from ischemia–reperfusion damage.Conclusion
Untargeted metabolomics analysis of plasma following RIC has led to insight into metabolism during RIC and revealed a possible novel metabolite of relevance to ischemic-reperfusion damage.498.
Pyruvate kinases (PK, EC 2.7.1.40) from three hyperthermophilic archaea (Archaeoglobus fulgidus strain 7324, Aeropyrum pernix, and Pyrobaculum aerophilum) and from the hyperthermophilic bacterium Thermotoga maritima were compared with respect to their thermophilic, kinetic, and regulatory properties. PKs from the archaea are 200-kDa homotetramers composed of 50-kDa subunits. The enzymes required divalent cations, Mg2+ and Mn2+ being most effective, but were independent of K+. Temperature optima for activity were 85 degrees C (A. fulgidus) and above 98 degrees C (A. pernix and P. aerophilum). The PKs were highly thermostable up to 110 degrees C (A. pernix) and showed melting temperatures for thermal unfolding at 93 degrees C (A. fulgidus) or above 98 degrees C (A. pernix and P. aerophilum). All archaeal PKs exhibited sigmoidal saturation kinetics with phosphoenolpyruvate (PEP) and ADP indicating positive homotropic cooperative response with both substrates. Classic heterotropic allosteric regulators of PKs from eukarya and bacteria, e.g. fructose 1,6-bisphosphate or AMP, did not affect PK activity of hyperthermophilic archaea, suggesting the absence of heterotropic allosteric regulation. PK from the bacterium T. maritima is also a homotetramer of 50-kDa subunits. The enzyme was independent of K+ ions, had a temperature optimum of 80 degrees C, was highly thermostable up to 90 degrees C, and had a melting temperature above 98 degrees C. The enzyme showed cooperative response to PEP and ADP. In contrast to its archaeal counterparts, the T. maritima enzyme exhibited the classic allosteric response to the activator AMP and to the inhibitor ATP. Sequences of hyperthermophilic PKs showed significant similarity to characterized PKs from bacteria and eukarya. Phylogenetic analysis of PK sequences of all three domains indicates a distinct archaeal cluster that includes the PK from the hyperthermophilic bacterium T. maritima. 相似文献
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More than 40 peptides belonging to the -Y/FXFGL-NH(2) allatostatin superfamily have been isolated and identified from the central nervous system (CNS) of the tiger prawn, Penaeus monodon (Crustacea: Penaeidea). The peptides can be arranged in seven sub-groups according to the variable post-tyrosyl residue represented by Ala, Gly, Ser, Thr, Asn, Asp, and Glu. Two of the residues (Thr and Glu) have not been observed in this position previously in either insects or crustaceans. Also reported for the first time for allatostatins, two of the peptides are N-terminally blocked by a pyroglutamic acid residue. The yields of certain peptides with similar amino acid sequences to each other were, in some instances, very different. As an example, the yield of ANQYTFGL-NH(2) was 2pmol, compared with ASQYTFGL-NH(2), with a yield of 156 pmol. There are several possibilities to account for this. If, as in all species so far investigated, there is a single allatostatin gene in P. monodon, then it would appear that different sub-populations have contributed mutant forms of particular peptides to the extract. Another, less likely possibility is that this species has more than one allatostatin gene, producing a variable array of peptides albeit in different molar ratios. Several peptides were present apparently as a result of the loss of one or more residues at the N-terminus of a larger form, either due to N-terminal degradation or specific post-translational processing. The number of peptides identified exceeds that for any other insect or crustacean species previously investigated. None is identical to any of the 60-70 insect allatostatins so far identified, and only three are common to other crustaceans. Immunohistochemical study of the CNS of P. monodon, with the same antisera as used to monitor the purification, confirms the widespread nature and complexity of allatostatinergic neural pathways in arthropods. Thus, all neuromeres of the brain, and all except one of the ventral cord ganglia, possess allatostatin neurons and extensive areas of allatostatin-innervated neuropile. In addition to the cytological evidence that the allatostatins act as neurotransmitters, associated with tissues as varied as eyes and legs, their presence in neurohemal areas such as the sinus gland and the perineural sheath of the thoracic ganglia suggests a neuroendocrine function. As well as posing a challenge to physiologists assigning specific functions to the allatostatins, their extensive intra-species multiplicity, linked to their inter-species variability, also presents a complex problem to geneticists and evolutionists. 相似文献