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LARSSON MARIE; LARSSON CARL-MAGNUS; GUERRERO MIGUEL G. 《Journal of experimental botany》1985,36(9):1373-1386
Larsson, M., Larsson, C.-M. and Guerrero, M. G. 1985. Photosyntheticnitrogen metabolism in high and low CO2-adapted Scenedesmus.I. Inorganic carbon-dependent O2 evolution, nitrate utilizationand nitrogen recycling.J. exp Bot. 36: 13731386 Scenedesmus obtusiusculus Chod. was grown on an inorganic mediumflushed with either air or air supplemented with 3% CO2. Inair-grown cells, O2 evolution dependent on low, but not high,HCO3 concentrations was strongly inhibited by the carbonicanhydrase inhibitor acetazolamide. Cells grown with 3% CO2 exhibitedlow rates of O2 evolution at low external inorganic C; however,after 30 min in air O2 evolution rates at low inorganic C approachedthose of air-grown cells. These results are compatible withthe view that Scenedesmus develops a CO2 concentratingmechanism in air, with carbonic anhydrase as an importantconstituent When 3% CO2-grown cells were subjected to air-level of CO2,just a transient decline in NO3 utilization was observed,but in the presence of acetazolamide the rate of the processdecreased drastically in response to the decrease in the CO2level. In CO2-free air NO3 was taken up at high ratesbut in a deregulated manner, leading to release of NH4+. A portionof the NO3 taken up in the absence of CO2 was apparentlyassimilated Cellular nitrate reductase (NR) activity initially decreasedbut subsequently recovered after a transition from 3% CO2 toair. In the presence of acetazolamide, a persistent decreasein NR activity was observed. Cellular glutamine synthetase (GS)activity increased after transition from 3% CO2 to air, theactivity increase being unaffected by acetazolamide. NH4+ releaseto the medium in the presence of L-methionine-D, L-sulphoximine(MSO) transiently increased in 3% CO2-grown cells in responseto a transfer to air. MSO-induced NH4+ release was in fact higherin air-grown cells than in 3% CO2-grown cells. Glycollate wasinitially released after transition from 3% CO2 to air, butthere was no difference in glycollate release between MSO-treatedand untreated cells. In air-adapted Scenedesmus, N recyclingseems to be of minor importance in comparison to primary N assimilation Key words: CO2-fixation, N recycling, nitrate uptake, Scenedesmus 相似文献
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LARSSON CARL-MAGNUS; LARSSON MARIE; GUERRERO MIGUEL G. 《Journal of experimental botany》1985,36(9):1387-1395
Larsson, C.-M., Larsson, M. and Guerrero, M. G. 1985. Photosyntheticnitrogen metabolism in high and low CO2-adapted Scenedesmus.II. Effect of ammonium and methionine sulphoximine on nitrateutilization.J. exp. Bot. 36: 13871395 In 3% CO2-grown Scenedesmus obtusiusculus Chod. utilizing NO3J as the N source, NH4+ addition caused a prompt inhibitionof NO3 utilization. Nitrate reductase (NR) activity declinedrapidly in response to the presence of NO4+, but the cessationof NO3 utilization was too rapid to be accounted forby the loss in NR activity. The first site of NO4+ inhibitionin these cells seems to be the entrance of NO3 into thecells. Upon exhaustion of NO4+ from the medium, NO3 utilizationwas rapidly restored and NR activity increased. Air-grown cellswere much less sensitive to the effect of NO4+, more than 30min being required for added NO4+ to cause complete inhibitionof NO3 utilization. In these cells, NO3 uptakeand NR activity decreased in parallel in response to NO4+ addition.In 3% CO2-grown cells simultaneously subjected to NO4+ and air-levelof CO2, NO4+ initially inhibited NO3 utilization completely,but a slight recovery took place after approximately 20 min The glutamine synthetase (GS) inhibitor L-methionine D, L-sulphoximine(MSO) behaved as a potent inhibitor of NO3 uptake in3% CO2-grown cells, but had considerably less effect in air-growncells, although the time-course of the MSO-induced inhibitionof GS was the same in both cases Key words: Ammonium, nitrate utilization, Scenedesmus 相似文献
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LEONOR E. ROVAI AGUSTIN AOKI NELIA M. GEREZ DE BURGOS ANTONCO BLANCO 《The Journal of eukaryotic microbiology》1990,37(4):280-286
Bloodstream Trypanosoma cruzi trypomastigotes isolated from infected mice undergo reduction of motility and structural damages after 5 to 45 min exposure to gossypol at concentrations ranging from 5 to 50 μM. When 1% serum albumin is added to the incubation medium, no alterations of parasites are observed, even with 100 μM gossypol. Intracellular T. cruzi amastigotes in infected Vero cell cultures exposed to 5 μM gossypol for 2 h do not show changes. Incubation with 5 μM gossypol for 48 h produces complete disruption of host cells; however, the amastigotes they contain show only mineor alterations. The observations indicate that, in protein-rich media, gossypol is complexed into associations which have no activity on the different forms of the T. cruzi biological cycle. 相似文献
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Contamination studies by ochratoxin A on pork kidney and chicken liver has been carried out in Catalonia (Spain). 73% of the pork kidney samples analyzed did not contain an amount of ochratoxin A over our detection limit (0.5 ng/g) whereas only 7% had contamination higher than 1 ng/g. None of the chicken samples analyzed were contaminated by this toxin above the detection limit. All contamination levels found are below the maximum levels accepted by several countries for this kind of material. A confirmative test is necessary before discarding false positive samples. 相似文献
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Impression cytology is a simple and painless procedure that allows the collection of the superficial layers of the conjunctival epithelium. Each sample is assigned a grade of epithelial metaplasia, and goblet cell density is calculated in each one. We have studied the superior and temporal bulbar conjuctiva of dry eyes and have compared it with that of normal controls. In normal and dry eyes we find a statistically significant difference both in goblet cell density and grade of metaplasia, between superior and temporal bulbar conjunctiva. the differences in grade of metaplasia and goblet cell density between normal and dry eyes are significant in the superior conjunctiva, but in the temporal conjunctiva we only find significant differences in grade of metaplasia. 相似文献
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MARTA GRAU-VORSTER LUCIANO RODRÍGUEZ SÍLVIA TORRENTS-ZAPATA DANIEL VIVAS MARGARITA CODINACH MARGARITA BLANCO IRENE OLIVER-VILA JOAN GARCÍA-LÓPEZ JOAQUIM VIVES 《Cytotherapy》2019,21(1):32-40
Background aims
Multipotent mesenchymal stromal cell (MSC)-based medicines are extensively investigated for use in regenerative medicine and immunotherapy applications. The International Society for Cell and Gene Therapy (ISCT) proposed a panel of cell surface molecules for MSC identification that includes human leukocyte antigen (HLA)-DR as a negative marker. However, its expression is largely unpredictable despite production under tightly controlled conditions and compliance with current Good Manufacturing Practices. Herein, we report the frequency of HLA-DR expression in 81 batches of clinical grade bone marrow (BM)-derived MSCs and investigated its impact on cell attributes and culture environment.Methods
The levels of 15 cytokines (interleukin [IL]-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, interferon-γ, soluble CD40 ligand and tumor necrosis factor-α) were determined in sera supplements and supernatants of BM-MSC cultures. Identity, multipotentiality and immunopotency assays were performed on high (>20% of cells) and low (≤20% of cells) HLA-DR+ cultures.Results
A correlation was found between HLA-DR expression and levels of IL-17F and IL-33. Expression of HLA-DR did neither affect MSC identity, in vitro tri-lineage differentiation potential (into osteogenic, chondrogenic and adipogenic lineages), nor their ability to inhibit the proliferation of stimulated lymphocytes.Discussion
Out of 81 batches of BM-MSCs for autologous use analyzed, only three batches would have passed the ISCT criteria (<2%), whereas 60.5% of batches were compliant with low HLA-DR values (≤20%). Although a cause–effect relationship cannot be drawn, we have provided a better understanding of signaling events and cellular responses in expansion culture conditions relating with HLA-DR expression. 相似文献8.
R. ERNESTO BLANCO ANDRÉS RINDERKNECHT GUSTAVO LECUONA 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2012,45(2):157-163
Blanco R.E., Rinderknecht, A. & Lecuona, G. 2011: The bite force of the largest fossil rodent (Hystricognathi, Caviomorpha, Dinomyidae). Lethaia, Vol. 45, pp. 157–163. An exceptionally well‐preserved skull of the largest fossil rodent Josephoartigasia monesi allows the first analysis of the bite mechanics of this group of South American giant rodents. In this study, we reconstructed the main anatomical features of the skull of this Pliocene rodent, relating them to the bite force at incisors. Bite force was estimated using three different techniques. Two methods suggest that bite forces at incisors of around 1000 N were possible for these mammals. However, the incisors seem to be stronger than expected for this bite force implying that the bite forces may have been greater than 3000 N. We consider three hypotheses: allometric effects, teeth digging or defence against predators, to explain our results. □Bite force, Dinomyidae, incisors, largest rodent, Pliocene. 相似文献
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Previously published allelic frequencies at four polymorphic protein coding loci were used as a basis for examining genetic relationships among 19 European populations of Atlantic salmon, Salmo salar L.--exclusive of Baltic drainages--from the Barents Sea to Spain. The data did not support a model of distinct ancestral (e.g. Boreal and Celtic) origins, but were consistent with all populations descending from a single ancestral group within this region with genetically diverged populations drawn together through limited local migrations. 相似文献