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161.
Characterization of an Autotrophic Nitrogen-Removing Biofilm from a Highly Loaded Lab-Scale Rotating Biological Contactor 总被引:7,自引:2,他引:5
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Kris Pynaert Barth F. Smets Stijn Wyffels Daan Beheydt Steven D. Siciliano Willy Verstraete 《Applied microbiology》2003,69(6):3626-3635
In this study, a lab-scale rotating biological contactor (RBC) treating a synthetic NH4+ wastewater devoid of organic carbon and showing high N losses was examined for several important physiological and microbial characteristics. The RBC biofilm removed 89% ± 5% of the influent N at the highest surface load of approximately 8.3 g of N m−2 day−1, with N2 as the main end product. In batch tests, the RBC biomass showed good aerobic and anoxic ammonium oxidation (147.8 ± 7.6 and 76.5 ± 6.4 mg of NH4+-N g of volatile suspended solids [VSS]−1 day−1, respectively) and almost no nitrite oxidation (< 1 mg of N g of VSS−1 day−1). The diversity of aerobic ammonia-oxidizing bacteria (AAOB) and planctomycetes in the biofilm was characterized by cloning and sequencing of PCR-amplified partial 16S rRNA genes. Phylogenetic analysis of the clones revealed that the AAOB community was fairly homogeneous and was dominated by Nitrosomonas-like species. Close relatives of the known anaerobic ammonia-oxidizing bacterium (AnAOB) Kuenenia stuttgartiensis dominated the planctomycete community and were most probably responsible for anoxic ammonium oxidation in the RBC. Use of a less specific planctomycete primer set, not amplifying the AnAOB, showed a high diversity among other planctomycetes, with representatives of all known groups present in the biofilm. The spatial organization of the biofilm was characterized using fluorescence in situ hybridization (FISH) with confocal scanning laser microscopy (CSLM). The latter showed that AAOB occurred side by side with putative AnAOB (cells hybridizing with probe PLA46 and AMX820/KST1275) throughout the biofilm, while other planctomycetes hybridizing with probe PLA886 (not detecting the known AnAOB) were present as very conspicuous spherical structures. This study reveals that long-term operation of a lab-scale RBC on a synthetic NH4+ wastewater devoid of organic carbon yields a stable biofilm in which two bacterial groups, thought to be jointly responsible for the high autotrophic N removal, occur side by side throughout the biofilm. 相似文献
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Nancy R. Stevenson Filippo Ferrigni Kris Parnicky Susan Day Jeffrey S. Fierstein 《生物化学与生物物理学报:生物膜》1975,406(1):131-145
The activities of rat intestinal enzymes, sucrase, lactase, maltase, trehalase, γ-glutamyltransferase, leucylnaphthylamide-hydrolyzing activity, and the transport system for glucose follow diurnal rhythms on ad libitum and restricted feeding regimes. In response to 6 days of restricted feeding, food available between 1400 and 1800 Eastern Standard Time, all rhythms shifted in time and the daily levels of activities were changed. Alkaline phosphatase activity followed a diurnal rhythm only in restricted fed animals.In restricted fed rats several activity patterns were observed, some with short periods of maximum activity, 3 h or less, and some with plateaus of maximum activity, 5–9 h long. In respect to the time of day of the synchronizer, sucrase peaked before feeding, glucose transport peaked during feeding, alkaline phosphatase peaked after feeding, and the other enzymes had higher levels of activity before, during and after feeding. The effect of restricted feeding on the daily activity levels were: a decrease in leucylnaphthylamide-hydrolyzing activity, no change in alkaline phosphatase, and increases in the others.These enzyme and transport systems exhibit a large amount of individual regulation or control as reflected by the lack of a uniform activity pattern and response to the synchronizer, and the variation in direction and magnitude of the adaptations to restricted feeding. 相似文献
166.
Kris Somers 《BMJ (Clinical research ed.)》1957,1(5027):1086-1088
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Masaki Iguchi Kris Baldwin Charles Boeyink Carol Engle Michael Kehoe Anish Ganju Andrew J Messaros Richard K Shields 《Journal of electromyography and kinesiology》2008,18(2):308-316
It is well accepted that a low intensity/long duration isometric contraction induces more low frequency fatigue (LFF) compared to a high-intensity/short-duration contraction. However, previous reports examined the intensity/duration of the contraction but did not control the level of fatigue when concluding fatigue is task dependent. The purpose of this study was to determine whether a long duration/low intensity fatiguing contraction would induce greater LFF than a short duration/high-intensity contraction when the quadriceps muscle was fatigued to similar levels. Eighteen healthy male subjects performed quadriceps contractions sustained at 35% and 65% of maximal voluntary contraction (MVC) on separate days, until the tasks induced a similar amount of fatigue (force generating capacity=45% MVC). Double pulse torque to single pulse torque ratio (D/S ratio) was obtained before, immediately and 5min after fatigue along with the electromyographic (EMG) signal from vastus medialis (VM) and rectus femoris (RF). The D/S ratio significantly (p<0.05) increased by 8.7+/-8.5% (mean+/-SD) and 10.2+/-9.2% after 35% and 65% tasks, respectively, and remained elevated 5min into recovery; however, there was no significant difference in ratio between the two sessions immediately or 5min post-fatigue (p>0.05) even though the endurance time for the 35% fatigue task (124+/-39.68s) was significantly longer (p=0.05) than that of the 65% task (63+/-17.73s). EMG amplitude and median power frequency (MPF) analysis also did not reveal any significant differences between these two sessions after fatigue. These findings indicate that LFF fatigue is fatigue dependent as well as task intensity/duration dependent. These findings assist us in understanding task dependency and muscle fatigue. 相似文献
168.
Studies assessing the effect and mechanism of probiotics on diseases of the upper gastrointestinal tract (GI) including gastric ulcers are limited despite extensive work and promising results of this therapeutic option for other GI diseases. In this study, we investigated the mechanisms by which the probiotic mixture VSL#3 (a mixture of eight probiotic bacteria including Lactobacilli, Bifidobacteria and Streptococcus species) heals acetic acid induced gastric ulcer in rats. VSL#3 was administered orally at low (6×109 bacteria) or high (1.2×1010 bacteria) dosages from day 3 after ulcer induction for 14 consecutive days. VSL#3 treatments significantly enhanced gastric ulcer healing in a dose-dependent manner. To assess the mechanism(s) whereby VSL#3 exerted its protective effects, we quantified the gene expression of several pro-inflammatory cytokines, protein and expression of stomach mucin-Muc5ac, regulatory cytokine-IL-10, COX-2 and various growth factors. Of all the components examined, only expression and protein production of VEGF was increased 332-fold on day 7 in the ulcerated tissues of animals treated with VSL#3. Predictably, animals treated with VEGF neutralizing antibody significantly delayed gastric ulcer healing in VSL#3 treated animals. This is the first report to demonstrate high efficacy of the probiotic mixture VSL#3 in enhancing gastric ulcer healing. Probiotic efficacy was effective at higher concentrations of VSL#3 by specifically increasing the expression and production of angiogenesis promoting growth factors, primarily VEGF. 相似文献
169.
The relationships among micro RNA-122 (miR-122) expression in the liver, hepatitis C virus (HCV) replication and hepatic damage were analyzed in three chimpanzees observed for 180 days after inoculation with HCV genotype 1a. Levels of miR-122 in the liver and serum were measured by real-time RT PCR in serial liver biopsies and serum samples. Hepatic miR-122 levels were normalized separately for each of three chimpanzees with small RNAs and microRNAs that are endogenous to the liver and are stably expressed. Two- to 4-fold rise in hepatic miR-122 levels was observed at the onset of HCV infection (the first 4 weeks) when HCV titers in the liver and serum increased rapidly in all three chimpanzees in concordance with in vitro data indicating the miR-122 significance for HCV replication. Between 10 to 14 weeks after inoculation, when hepatic and serum HCV RNA titers exceeded 3 logs and alanine aminotransferase (ALT) activity was elevated, hepatic miR-122 levels were in decline. Cumulative data derived from all three chimpanzees from 180 days of observation documented an inverse (negative) correlation between hepatic miR-122 and HCV RNA in the liver and serum and positive correlation between level of serum miR-122 and HCV replication. Subsequent rise of miR-122 level during HCV clearance and ALT normalization suggested a tri-phasic occurrence of the relationship among hepatic miR-122 expression, HCV replication and hepatic destruction, which was the most apparent in one chimpanzee but less evident in two other animals. In vivo kinetics of hepatic and serum miR-122, HCV replication and hepatic destruction reflects complexities of the virus-host interaction during the acute phase of HCV infection. 相似文献
170.
The SER Standards: a globally relevant and inclusive tool for improving restoration practice—a reply to Higgs et al.
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George D. Gann Tein McDonald James Aronson Kingsley W. Dixon Bethanie Walder James G. Hallett Kris Decleer Donald A. Falk Emily K. Gonzales Carolina Murcia Cara R. Nelson Alan J. Unwin 《Restoration Ecology》2018,26(3):426-430
In response to a critique by Higgs et al., this article clarifies the content and intent of the Society for Ecological Restoration's (SER) International Standards for the Practice of Ecological Restoration. Higgs et al. expressed concern that the SER Standards are not sufficiently underpinned by principles and risk disenfranchising some practitioners by narrowing what qualifies as ecological restoration. To demonstrate that these concerns are unfounded, we discuss the policy context and principles on which the Standards are based, its organizational structure, the innovative and inclusive approach used for development, and highlight significant errata by Higgs et al. 相似文献