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161.
Toft AD Jensen LB Bruunsgaard H Ibfelt T Halkjaer-Kristensen J Febbraio M Pedersen BK 《American journal of physiology. Cell physiology》2002,283(1):C289-C295
To examine the plasma interleukin(IL)-6 response in elderly (E) and young (Y) humans, 10 E and 10 Ysubjects completed 60 min of eccentric lower limb exercise at the samerelative oxygen uptake. Plasma IL-6 was measured before, immediatelyafter, and 5 days into recovery from exercise, as were the biochemicalmarkers of muscle damage, creatine kinase (CK), and myoglobin. In both groups, IL-6 increased (P < 0.05) immediately afterexercise and peaked 4 h after exercise at 4.35 ± 1.7 vs.5.05 ± 3.17 pg/ml for E and Y subjects, respectively. However,the increase in IL-6 in both groups was modest relative to theincreases in CK peaking at 539 ± 413 vs. 10,301 ± 5,863 U/lfor E and Y subjects, respectively. In addition, the increase in IL-6was less pronounced (P < 0.05) in E subjects comparedwith Y subjects. These results suggest that IL-6 increasesprogressively after eccentric exercise, suggesting that this increaseis related to muscle damage. However, the modest increase in IL-6,despite large increases in CK, suggests that the IL-6 response tomuscle damage does not make an important contribution to the largeincrease in IL-6 observed during concentric exercise of long duration.Our data also suggest that aging may be associated with impaired repairmechanisms for exercise-induced muscle damage. 相似文献
162.
L. P. S. Van Der Geest A. Cornelissen H. P. Tjon-A-Joe W. Helle 《Entomologia Experimentalis et Applicata》1978,23(3):269-278
Polymorphism was studied for a number of enzyme systems in the tsetse fly Glossina morsitans. Enzyme polymorphism was observed for -glycerophospate dehydrogenase, aldehyde oxidase and esterases. For esterases, the operation of null alleles was assumed, as otherwise no explanation could be given for the observed frequencies of the variants.Two laboratory colonies and two field populations were compared with respect to their variation at the leucine aminopeptidase (Lap) loci, for which polymorphism was shown to occur in previous work. Conspicuous differences were found between material originating from Tanzania and from Rhodesia. In addition, allelic relationships were established for the Lap
3-locus.
Résumé Faisant suite à des études antérieures, le polymorphisme d'un certain nombre de systèmes enzymatiques a été étudié chez Glossina morsitans. Un polymorphisme a été observé pour l' -glycerophosphate déhydrogénase, pour l'aldéhyde-oxydase et pour les estérases. Pour les estérases, on a supposé l'intervention d'allèles nuls, les fréquences observées chez les variants ne pouvant être expliquées d'autre façon.Deux colonies élevées au laboratoire et deux populations naturelles ont été comparées quant à leur variation au niveau des loci (Lap) pour la leucine aminopeptidase, pour lesquels un travail antérieur avait mis en évidence un polymorphisme. Des différences nettes ont été trouvées entre le matériel provenant de Tanzanie et celui de Rhodésie. En outre des parentés alléliques ont été établies en ce qui concerne le locus Lap 3.相似文献
163.
A quantitative assay for ciliate chemotaxis 总被引:1,自引:0,他引:1
A quantitative bioassay for ciliate chemotaxis based on the capillary principle is described using Tetrahymena thermophila as test organism. The attractant-containing assay tube designed for the bioassay attracts up to 4 X 10(4) cells in 2 h which makes electronic cell counting of the chemotactic response feasible. The attractants used are solutions of proteose peptone and yeast extract which also are growth media for this organism. 相似文献
164.
165.
The role of complementary spectral utilization of light for the zonation of different groups of oxygenic phototrophic organisms in sediments was studied. The marine sediment was covered by a dense population of diatoms with an underlying population of cyanobacteria. Action spectra for photosynthesis and spectral scalar irradiance, E0, were measured directly in the sediment at a spatial resolution of 0.1 mm by the use of oxygen and light microsensors. The action spectrum for the diatoms was similar to the attenuation spectrum of the scalar irradiance, K0, in the diatom layer with Chl.a. and carotenoids being the major photosynthetic pigments. The action spectrum of the cyanobacteria showed photosynthesis maxima at the absorption regions of Chl.a. and phycocyanin. The measured depth distribution of spectral scalar irradiance and the action spectra of diatoms and cyanobacteria were used to calculate the spectral quality for photosynthesis of the 400–700 nm light to which the two populations were exposed. This spectral quality was compared to that of the light incident on the sediment surface. Due to preferential extinction of wavelengths, at which their photosynthetically active pigments had maximal absorption, the relative light quality for diatoms was reduced to 85% of the quality of d incident light at a similar total quantum flux. This effect was partly due to spectral alterations of light backscattered from the underlying sediment with cyanobacteria. The cyanobacteria at the bottom of the euphotic zone, in contrast, experienced a light spectrum which was favorably altered, to 10% in quality, due to absorption by the overlying diatoms. It was concluded that these changes in spectral light quality can be considered as only one of more factors explaining the zonation of the two phototrophic populations, and that total light intensity and the chemical microenvironment are probably more important factors. 相似文献
166.
Sofía Feliziani Rasmus L. Marvig Adela M. Luján Alejandro J. Moyano Julio A. Di Rienzo Helle Krogh Johansen S?ren Molin Andrea M. Smania 《PLoS genetics》2014,10(10)
The advent of high-throughput sequencing techniques has made it possible to follow the genomic evolution of pathogenic bacteria by comparing longitudinally collected bacteria sampled from human hosts. Such studies in the context of chronic airway infections by Pseudomonas aeruginosa in cystic fibrosis (CF) patients have indicated high bacterial population diversity. Such diversity may be driven by hypermutability resulting from DNA mismatch repair system (MRS) deficiency, a common trait evolved by P. aeruginosa strains in CF infections. No studies to date have utilized whole-genome sequencing to investigate within-host population diversity or long-term evolution of mutators in CF airways. We sequenced the genomes of 13 and 14 isolates of P. aeruginosa mutator populations from an Argentinian and a Danish CF patient, respectively. Our collection of isolates spanned 6 and 20 years of patient infection history, respectively. We sequenced 11 isolates from a single sample from each patient to allow in-depth analysis of population diversity. Each patient was infected by clonal populations of bacteria that were dominated by mutators. The in vivo mutation rate of the populations was ∼100 SNPs/year–∼40-fold higher than rates in normo-mutable populations. Comparison of the genomes of 11 isolates from the same sample showed extensive within-patient genomic diversification; the populations were composed of different sub-lineages that had coexisted for many years since the initial colonization of the patient. Analysis of the mutations identified genes that underwent convergent evolution across lineages and sub-lineages, suggesting that the genes were targeted by mutation to optimize pathogenic fitness. Parallel evolution was observed in reduction of overall catabolic capacity of the populations. These findings are useful for understanding the evolution of pathogen populations and identifying new targets for control of chronic infections. 相似文献
167.
Melanie Ghoul Stuart A. West Helle Krogh Johansen S?ren Molin Odile B. Harrison Martin C. J. Maiden Lars Jelsbak John B. Bruce Ashleigh S. Griffin 《Proceedings. Biological sciences / The Royal Society》2015,282(1814)
Bacteriocins are toxins produced by bacteria to kill competitors of the same species. Theory and laboratory experiments suggest that bacteriocin production and immunity play a key role in the competitive dynamics of bacterial strains. The extent to which this is the case in natural populations, especially human pathogens, remains to be tested. We examined the role of bacteriocins in competition using Pseudomonas aeruginosa strains infecting lungs of humans with cystic fibrosis (CF). We assessed the ability of different strains to kill each other using phenotypic assays, and sequenced their genomes to determine what bacteriocins (pyocins) they carry. We found that (i) isolates from later infection stages inhibited earlier infecting strains less, but were more inhibited by pyocins produced by earlier infecting strains and carried fewer pyocin types; (ii) this difference between early and late infections appears to be caused by a difference in pyocin diversity between competing genotypes and not by loss of pyocin genes within a lineage over time; (iii) pyocin inhibition does not explain why certain strains outcompete others within lung infections; (iv) strains frequently carry the pyocin-killing gene, but not the immunity gene, suggesting resistance occurs via other unknown mechanisms. Our results show that, in contrast to patterns observed in experimental studies, pyocin production does not appear to have a major influence on strain competition during CF lung infections. 相似文献
168.
Several Wolf-Hirschhorn syndrome patients have been studied, mouse models for a few candidate genes have been constructed and two WHS critical regions have been postulated, but the molecular basis of the syndrome remains poorly understood. 相似文献
169.
Variation in grain arsenic assessed in a diverse panel of rice (Oryza sativa) grown in multiple sites 总被引:3,自引:0,他引:3
Norton GJ Pinson SR Alexander J McKay S Hansen H Duan GL Rafiqul Islam M Islam S Stroud JL Zhao FJ McGrath SP Zhu YG Lahner B Yakubova E Guerinot ML Tarpley L Eizenga GC Salt DE Meharg AA Price AH 《The New phytologist》2012,193(3):650-664
? Inorganic arsenic (As(i) ) in rice (Oryza sativa) grains is a possible threat to human health, with risk being strongly linked to total dietary rice consumption and consumed rice As(i) content. This study aimed to identify the range and stability of genetic variation in grain arsenic (As) in rice. ? Six field trials were conducted (one each in Bangladesh and China, two in Arkansas, USA over 2 yr, and two in Texas, USA comparing flooded and nonflood treatments) on a large number of common rice cultivars (c. 300) representing genetic diversity among international rice cultivars. ? Within each field there was a 3-34 fold range in grain As concentration which varied between rice subpopulations. Importantly, As(i) correlated strongly with total As among a subset of 40 cultivars harvested in Bangladesh and China. ? Genetic variation at all field sites was a large determining factor for grain As concentration, indicating that cultivars low in grain As could be developed through breeding. The temperate japonicas exhibited lower grain As compared with other subpopulations. Effects for year, location and flooding management were also statistically significant, suggesting that breeding strategies must take into account environmental factors. 相似文献
170.
Burns JS Kristiansen M Kristensen LP Larsen KH Nielsen MO Christiansen H Nehlin J Andersen JS Kassem M 《PloS one》2011,6(7):e21888