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101.
The effects of nickel on hydrogen uptake and the post-translational processing of the large subunit of the hydrogenase protein
in three Frankia strains (one isolated from an Alnus-Frankia symbiosis and two from Casuarina-Frankia associations) were investigated. All three strains responded to the addition of nickel with an increase in hydrogen uptake.
Additional nickel did not affect nitrogenase activity, however evolved hydrogen was detected in Frankia KB5 in the absence of additional nickel, indicating that hydrogenase was not active. No increase in the processing rate of
the hydrogenase large subunit was found with increasing nickel concentrations for any of the strains, indicating that the
strategy for regulating hydrogenase in Frankia is different from that in other microorganisms.
Received: 23 April 2001 / Accepted: 29 May 2001 相似文献
102.
103.
Rehab Alnabhan Ahmed Gaballa Lisa-Mari Mörk Jonas Mattsson Michael Uhlin Isabelle Magalhaes 《Cytotherapy》2018,20(7):941-951
Background
The use of CD19 chimeric antigen receptor (CAR) T cells to treat B-cell malignancies has proven beneficial. Several groups use serum to produce CD19 CAR T cells. Today, ready-to-use serum-free media that require no addition of serum are commercially available. Therefore, it becomes important to evaluate the production of CD19 CAR T cells with and without the addition of serum.Methods
T cells from buffy coats were cultured in AIM-V and TexMACS (TM) supplemented with 5% human serum (A5% and TM5%, respectively), and in TM without serum. Cells were activated with OKT3 and expanded in interleukin (IL)-2. Viral transduction was performed in RetroNectin-coated plates using the spinoculation method. CD19 CAR T cells were tested for their viability, expansion, transduction efficacy, phenotype and cytotoxicity.Results
CD19 CAR T cells expanded in A5% and TM5% showed significantly better viability and higher fold expansion than cells expanded in TM. TM promoted the expansion of CD8+ T cells and effector phenotype of CD19 CAR T cells. The transduction efficacy and the cytotoxic function were comparable between the different media. Higher CD107a+ cells were detected in TM and TM5%, whereas higher IL-2+ and IL-17+ cells were detected in A5%. CD19 CAR exhibited co-expression of inhibitory receptors such as TIM-3+LAG-3+ and/or TIM-3+PD-1+.Conclusion
Our results indicate that serum supplementation promotes better CD19 CAR T-cell expansion and viability in vitro. CD19 CAR T cells produced in TM medium showed lower CD4/CD8 ratio, which warrants further evaluation in clinical settings. Overall, the choice of culture medium impacts CD19 CAR T-cell end product. 相似文献104.
Leaf-Atmosphere NH3 Exchange in Barley Mutants with Reduced Activities of Glutamine Synthetase 总被引:5,自引:0,他引:5 下载免费PDF全文
Mutants of barley (Hordeum vulgare L. cv Maris Mink) with 47 or 66% of the glutamine synthetase (GS) activity of the wild type were used for studies of NH3 exchange with the atmosphere. Under normal light and temperature conditions, tissue NH4+ concentrations were higher in the two mutants compared with wild-type plants, and this was accompanied by higher NH3 emission from the leaves. The emission of NH3 increased with increasing leaf temperatures in both wild-type and mutant plants, but the increase was much more pronounced in the mutants. Similar results were found when the light intensity (photosynthetic photon flux density) was increased. Compensation points for NH3 were estimated by exposing intact shoots to 10 nmol NH3 mol-1 air under conditions with increasing temperatures until the plants started to emit NH3. Referenced to 25[deg]C, the compensation points were 5.0 nmol mol-1 for wild-type plants, 8.3 nmol mol-1 for 47% GS mutants, and 11.8 nmol mol-1 for 66% GS mutants. Compensation points for NH3 in single, nonsenescent leaves were estimated on the basis of apoplastic pH and NH4+ concentrations. These values were 0.75, 3.46, and 7.72 nmol mol-1 for wild type, 47% GS mutants, and 66% GS mutants, respectively. The 66% GS mutant always showed higher tissue NH4+ concentrations, NH3 emission rates, and NH3 compensation points compared with the 47% GS mutant, indicating that NH4+ release was curtailed by some kind of compensatory mechanism in plants with only 47% GS activity. 相似文献
105.
K Andersson D Chen H Mattsson F Sundler R H?kanson 《The Yale journal of biology and medicine》1998,71(3-4):183-193
In the oxyntic mucosa of the mammalian stomach, histamine is stored in ECL cells and in mucosal mast cells. In the rat, at least 80 percent of oxyntic mucosal histamine resides in the ECL cells. Histamine is a key factor in the regulation of gastric acid secretion. Following depletion of ECL-cell histamine by treatment with alpha-fluoromethylhistidine (alpha-FMH), basal acid secretion was reduced, and gastrin-stimulated acid secretion was abolished. Vagally-induced acid secretion (by insulin injection or pylorus ligation) was unaffected by alpha-FMH treatment but inhibited by an H2 antagonist. These results suggest that gastrin stimulates acid secretion via release of ECL-cell histamine, whereas vagally-induced acid secretion--although histamine-dependent--does not rely on ECL-cell histamine. Gastrin is known to have a trophic effect on the oxyntic mucosa. By combining long-term hypergastrinemia with continuous infusion of alpha-FMH, we were able to show that gastrin-evoked trophic effects in the stomach do not depend on ECL-cell histamine. 相似文献
106.
Therése?Geber-BergstrandEmail authorView authors OrcID profile Christian?Bernhardsson Maria?Christiansson S?ren?Mattsson Christopher?L.?R??f 《Radiation and environmental biophysics》2018,57(1):69-75
In this study the dosimetric properties of alumina (Al2O3) substrates found in resistors retrieved from mobile phones were investigated. Measurements of the decline of optically stimulated luminescence (OSL) generated following exposure of these substrates to ionising radiation showed that 16% of the signal could still be detected after 2 years (735 days). Further, the magnitude of the regenerative dose (calibration dose; D i) had no impact on the accuracy of dose estimates. Therefore, it is recommended that the D i be set as low as is practicable, so as to accelerate data retrieval. The critical dose, D CL, and dose limit of detection, D DL, taking into account the uncertainty in the dose–response relation as well as the uncertainty in the background signal, was estimated to be 7 and 13 mGy, respectively, 1 h after exposure. It is concluded that given the significant long-term component of fading, an absorbed dose of 0.5 Gy might still be detectable up to 6 years after the exposure. Thus, OSL from alumina substrates can be used for dosimetry for time periods far in excess of those previously thought. 相似文献
107.
A comparative study of the antibody titer against Francisella tularensis biovar palaearctica in serum and lung extract was made using different immunoassays. Samples were taken from experimentally-infected goshawks (Accipiter gentilis) and European beavers (Castor fiber), and in a field survey of wild beavers. Good accordance between the antibody titer in serum and in lung extract was found in the experimental studies. However, the antibody titer was generally one- to three-fold lower in lung extract than was the titer of serum. Results in the field survey were less reliable. Estimating antibody titer in lung extract is a practical method for surveys for antibody levels, and an alternative to serological surveys, despite lower sensitivity as compared to serum. 相似文献
108.
Uptake and utilization of nitrate were investigated in Hordeum vulgare L. cvs Mette and Golf in the vegetative stage, 2 and 4 weeks after sowing. The plants were subjected to a light/dark cycle of 16/8 h (18/12°C). Results obtained with the two genotypes were essentially similar. In the light, xylem nitrate transport and shoot nitrate reduction approximately equalled the amount of nitrate absorbed by the root. A drastic decline in translocation to the shoot in darkness was entirely attributable to decreased transpiration since no major changes in xylem nitrate concentration were observed. Darkening caused only a slight decrease in nitrate uptake, while root nitrate reduction was enhanced. Nitrate starvation for 2 days did not significantlly affect dry matter increment, but resulted in a drastic drop in previously accumulated nitrate, indicating that the stored nitrate is accessible and can sustain unrestricted growth. Uptake increased upon re-addition of nitrate and after 8 h it was about twice that of non-starved plants. During recovery, restoration of root nitrate pools and root nitrate reduction took precedence over shoot nitrate accumulation and reduction. Net nitrate uptake and removal of nitrate from the root to the transpiration stream seem to be decisive for the rate of root nitrate reduction. 相似文献
109.
Changes in inducibility of ornithine decarboxylase activity in differentiating human neuroblastoma cells 总被引:1,自引:0,他引:1
Maria E.K. Mattsson Aino-Inkeri Ruusala Sven Påhlman 《Experimental cell research》1984,155(1):105-112
Human SH-SY5Y neuroblastoma cells could be induced to differentiate morphologically and biochemically in the presence of 12-O-tetradecanoylphorbol-13-acetate (TPA), retinoic acid (RA), or a combination of these two substances. The phenotypical changes induced by these substances differed, but one effect of both was an inhibition of the cell growth. Addition of TPA or RA to non-treated cells had no effect on the activation of ornithine decarboxylase (ODC, EC 4.1.1.17.), while a change to fresh medium stimulated the ODC to maximum activity after 4-6 h. The activity was not altered by the presence of RA in the fresh medium, but TPA partially inhibited the medium-stimulated ODC activity. Cells treated for 4 or 8 days with TPA or a combination of TPA and RA had a low ODC activity which could not be induced by fresh medium. However, RA-treated (and thus growth-inhibited) cells still responded to a change of medium by exhibiting an ODC activity of the same magnitude and duration as in medium-stimulated control cells. The results seem to suggest that the growth inhibition induced by TPA and RA, respectively, is mediated by different mechanisms. 相似文献
110.
Estimating the per‐capita contribution of habitats and pathways in a migratory network: a modelling approach 下载免费PDF全文
Ruscena Wiederholt Brady J. Mattsson Wayne E. Thogmartin Michael C. Runge Jay E. Diffendorfer Richard A. Erickson Paula Federico Laura López‐Hoffman John M. Fryxell D. Ryan Norris Christine Sample 《Ecography》2018,41(5):815-824
Every year, migratory species undertake seasonal movements along different pathways between discrete regions and habitats. The ability to assess the relative demographic contributions of these different habitats and pathways to the species’ overall population dynamics is critical for understanding the ecology of migratory species, and also has practical applications for management and conservation. Metrics for assessing habitat contributions have been well‐developed for metapopulations, but an equivalent metric is not currently available for migratory populations. Here, we develop a framework for estimating the demographic contributions of the discrete habitats and pathways used by migratory species throughout the annual cycle by estimating the per capita contribution of cohorts using these locations. Our framework accounts for seasonal movements between multiple breeding and non‐breeding habitats and for both resident and migratory cohorts. We illustrate our framework using a hypothetical migratory network of four habitats, which allows us to better understand how variations in habitat quality affect per capita contributions. Results indicate that per capita contributions for any habitat or pathway are dependent on habitat‐specific survival probabilities in all other areas used as part of the migratory circuit, and that contribution metrics are spatially linked (e.g. reduced survival in one habitat also decreases the contribution metric for other habitats). Our framework expands existing theory on the dynamics of spatiotemporally structured populations by developing a generalized approach to estimate the habitat‐ and pathway‐specific contributions of species migrating between multiple breeding and multiple non‐breeding habitats for a range of life histories or migratory strategies. Most importantly, it provides a means of prioritizing conservation efforts towards those migratory pathways and habitats that are most critical for the population viability of migratory species. 相似文献