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Uahengo, Veikko et al (2014), Three-channel ferrocene-based chemosensors for Cu(II) and Hg(II) in aqueous environments, Sensors and Actuators, B: Chemical, vol. 190, 937 - 945
Three-channel ferrocene-based chemosensors for Cu(II) and Hg(II) in aqueous environmentsUahengo, Veikko, Xiong, Bi, Zhao, Pingping, Zhang, Yan, Cai, Ping, Hu, Kai, Cheng, Gongzhen (2014), Sensors and Actuators, B: Chemical, vol. 190, 937 - 945
Ferrocene-based conjugated complexes, benzenediamine (A), benzidine (B) and disulfanediyldianiline (C) are synthesized and their spectroscopic, electrochemical and cation sensing properties are studied. Three complexes are high sensitive color systems for determination of Hg(II) and Cu(II) in DMSO-H2O (10:0.5) solution. The absorption spectral changes were observed upon the addition of either Hg(II) or Cu(II), with the dramatic naked eye detectable color changes from yellow to red or green respectively. Moreover, the addition of cations showed strong fluorescent quenching, while new redox peaks were observed during electrochemical titrations. The DFT calculations were carried out to investigate the electronic coupling between the ferrocene centers. © 2013 Elsevier B.V.
Uenoyama, Y. et al (2006), Hypoxia induced by benign intestinal epithelial cells is associated with cyclooxygenase-2 expression in stromal cells through AP-1-dependent pathway, Oncogene, vol. 25, 3277 - 3285
Hypoxia induced by benign intestinal epithelial cells is associated with cyclooxygenase-2 expression in stromal cells through AP-1-dependent pathwayUenoyama, Y., Seno, H., Fukuda, A., Sekikawa, A., Nanakin, A., Sawabu, T., Kawada, M., Kanda, N., Suzuki, K., Yada, N., Fukui, H., Chiba, T. (2006), Oncogene, vol. 25, 3277 - 3285
Cyclooxygenase-2 (COX-2) plays important roles in tumor development. Especially in the early-stage colorectal tumors, COX-2 expression is often observed in the tumor stroma. However, the mechanism regulating such stromal expression of COX-2 remains unknown. In the present study, we simulated the indirect interaction between epithelial cells and stromal cells in the process of colorectal tumor development using an in vitro co-culture model in which NIH3T3 fibroblasts were co-cultured with 'sparsely' or 'densely' populated intestinal epithelial cells, Intestine-407 as a model of premalignant or benign intestinal epithelial cells, and DLD-1 and Caco-2 as models of malignant epithelial cells. COX-2 expression in NIH3T3 fibroblasts was upregulated when co-cultured with the 'dense' epithelial cells regardless of their character. Interestingly, there was pericellular hypoxia in the vicinity of NIH3T3 fibroblasts when co-cultured with 'dense' epithelial cells, and the recovery of the partial pressure of oxygen level resulted in the reduction of enhanced COX-2 expression only in NIH3T3 fibroblasts co-cultured with 'dense' Intestine-407 cells. Furthermore, COX-2 expression was also reduced by the inhibition of transcription factor AP-1. Thus, pericellular hypoxia of the stromal cells caused by densely populated epithelial cells may be one of the potent COX-2 enhancers before completion of malignant transformation during intestinal tumor development.
Ullsten, Sara et al (2015), Vascular heterogeneity between native rat pancreatic islets is responsible for differences in survival and revascularisation post transplantation, Diabetologia, vol. 58, 132 - 139
Vascular heterogeneity between native rat pancreatic islets is responsible for differences in survival and revascularisation post transplantationUllsten, Sara, Lau, Joey, Carlsson, Per Ola (2015), Diabetologia, vol. 58, 132 - 139
AIMS/HYPOTHESIS: Highly blood-perfused islets have been observed to be the most functional islets in the native pancreas. We hypothesised that differences in vascular support of islets in donor pancreases influence their susceptibility to cellular stress and capacity for vascular engraftment after transplantation.\n\nMETHODS: Highly blood-perfused islets in rats were identified by injection of microspheres into the ascending aorta before islet isolation. Cell death was evaluated after in vitro cytokine or hypoxia exposure, and 2 days post transplantation. One month post transplantation, islet engraftment, including vascular density, blood perfusion and oxygen tension (pO2) in the tissue, was evaluated.\n\nRESULTS: Microsphere-containing islets had a similar frequency of cell death during standard culture conditions but increased cell death after exposure to cytokines and hypoxia in comparison with other islets. Two days after transplantation the percentage of apoptotic or necrotic cells was also higher in grafts of such islets and 1 month post transplantation these grafts were composed of substantially more connective tissue. Grafts of highly blood-perfused islets in the native pancreas regained a higher vascular density, blood perfusion and pO2 in comparison with grafts of other islets.\n\nCONCLUSIONS/INTERPRETATION: Native islets that are highly blood-perfused regained this feature after transplantation, indicating a superior capacity for revascularisation and post-transplant function. However, the same group of islets was more vulnerable to different kinds of cellular stress, which limited their early survival post transplantation. Preferential death of these most active islets may contribute to the high number of islets needed to provide cure with islet transplantation.
Ulstrup, K. E. et al (2006), Intra-colonial variability in light acclimation of zooxanthellae in coral tissues of Pocillopora damicornis, Marine Biology, vol. 149, 1325 - 1335
Intra-colonial variability in light acclimation of zooxanthellae in coral tissues of Pocillopora damicornisUlstrup, K. E., Ralph, P. J., Larkum, A. W.D., Kühl, M. (2006), Marine Biology, vol. 149, 1325 - 1335
Abstract We investigated heterogeneity of light accli- mation of photosynthesis in sun- and shade-adapted coenosarc and polyp tissues of Pocillopora damicornis. The zooxanthellar community within P. damicornis colonies at Heron Island is genetically uniform, yet they showed a ... \n
Ulstrup, Karin E. et al (2005), Photosynthetic impact of hypoxia on in hospite zooxanthellae in the scleractinian coral Pocillopora damicornis, Marine Ecology Progress Series, vol. 286, 125 - 132
No abstract available.
Ulstrup, Karin E. et al (2007), Zooxanthellae harvested by ciliates associated with brown band syndrome of corals remain photosynthetically competent, Applied and Environmental Microbiology, vol. 73, 1968 - 1975
Zooxanthellae harvested by ciliates associated with brown band syndrome of corals remain photosynthetically competentUlstrup, Karin E., Kühl, Michael, Bourne, David G. (2007), Applied and Environmental Microbiology, vol. 73, 1968 - 1975
Brown band syndrome is a new coral affliction characterized by a local accumulation of yet-unidentified ciliates migrating as a band along the branches of coral colonies. In the current study, morphologically intact zooxanthellae (= Symbiodinium) were observed in great numbers inside the ciliates (>50 dinoflagellates per ciliate). Microscale oxygen measurements and variable chlorophyll a fluorescence analysis along with microscopic observations demonstrated that zooxanthellae within the ciliates are photosynthetically competent and do not become compromised during the progression of the brown band zone. Zooxanthellae showed similar trends in light acclimation in a comparison of rapid light curve and steady-state light curve measures of variable chlorophyll a fluorescence. Extended light exposure of steady-state light curves resulted in higher quantum yields of photosystem II. The brown band tissue exhibited higher photosynthetically active radiation absorptivity, indicating more efficient light absorption due to a higher density of zooxanthellae in the ciliate-dominated zone. This caused relatively higher gross photosynthesis rates in the zone with zooxanthella-containing ciliates compared to healthy coral tissue. The observation of photosynthetically active intracellular zooxanthellae in the ciliates suggests that the latter can benefit from photosynthates produced by ingested zooxanthellae and from photosynthetic oxygen production that alleviates diffusion limitation of oxic respiration in the densely populated brown band tissue. It remains to be shown whether the zooxanthellae form a stable symbiotic association with the ciliate or are engulfed incidentally during grazing on coral tissue and then maintained as active inside the ciliate for a period before being digested and replaced by new zooxanthellae.
Ushiki, Norisuke et al (2017), Nitrite oxidation kinetics of two Nitrospira strains: The quest for competition and ecological niche differentiation, Journal of Bioscience and Bioengineering, vol. 123, 581 - 589
Nitrite oxidation kinetics of two Nitrospira strains: The quest for competition and ecological niche differentiationUshiki, Norisuke, Jinno, Masaru, Fujitani, Hirotsugu, Suenaga, Toshikazu, Terada, Akihiko, Tsuneda, Satoshi (2017), Journal of Bioscience and Bioengineering, vol. 123, 581 - 589
Nitrite oxidation is an aerobic process of the nitrogen cycle in natural ecosystems, and is performed by nitrite-oxidizing bacteria (NOB). Also, nitrite oxidation is a rate-limiting step of nitrogen removal in wastewater treatment plants (WWTPs). Although Nitrospira is known as dominant NOB in WWTPs, information on their physiological properties and kinetic parameters is limited. Here, we report the kinetic parameters and inhibition of nitrite oxidation by free ammonia in pure cultures of Nitrospira sp. strain ND1 and Nitrospira japonica strain NJ1, which were previously isolated from activated sludge in a WWTP. The maximum nitrite uptake rate (Vmax_NO2) and the half-saturation constant for nitrite uptake (Km_NO2) of strains ND1 and NJ1 were 45 ± 7 and 31 ± 5 (?mol NO2?/mg protein/h), and 6 ± 1 and 10 ± 2 (?M NO2?), respectively. The Vmax_NO2and Km_NO2of two strains indicated that they adapt to low-nitrite-concentration environments like activated sludge. The half-saturation constants for oxygen uptake (Km_O2) of the two strains were 4.0 ± 2.5 and 2.6 ± 1.1 (?M O2), respectively. The Km_O2values of the two strains were lower than those of other NOB, suggesting that Nitrospira in activated sludge could oxidize nitrite in the hypoxic environments often found in the interiors of biofilms and flocs. The inhibition thresholds of the two strains by free ammonia were 0.85 and 4.3 (mg-NH3l?1), respectively. Comparing the physiological properties of the two strains, we suggest that tolerance for free ammonia determines competition and partitioning into ecological niches among Nitrospira populations.
Uteau, Daniel et al (2015), Oxygen and redox potential gradients in the rhizosphere of alfalfa grown on a loamy soil, Journal of Plant Nutrition and Soil Science, vol. 178, 278 - 287
Oxygen and redox potential gradients in the rhizosphere of alfalfa grown on a loamy soilUteau, Daniel, Hafner, Silke, Pagenkemper, Sebastian Kouso, Peth, Stephan, Wiesenberg, Guido L.B., Kuzyakov, Yakov, Horn, Rainer (2015), Journal of Plant Nutrition and Soil Science, vol. 178, 278 - 287
Oxygen (O2) supply and the related redox potential (EH) are important parameters for interactions between roots and microorganisms in the rhizosphere. Rhizosphere extension in terms of the spatial distribution of O2 concentration and EH is poorly documented under aerobic soil conditions. We investigated how far O2 consumption of roots and microorganisms in the rhizosphere is replenished by O2 diffusion as a function of water/air-filled porosity. Oxygen concentration and EH in the rhizosphere were monitored at a mm-scale by means of electroreductive Clark-type sensors and miniaturized EH electrodes under various matric potential ranges. Respiratory activity of roots and microorganisms was calculated from O2 profiles and diffusion coefficients. pH profiles were determined in thin soil layers sliced near the root surface. Gradients of O2 concentration and the extent of anoxic zones depended on the respiratory activity near the root surface. Matric potential, reflecting air-filled porosity, was found to be the most important factor affecting O2 transport in the rhizosphere. Under water-saturated conditions and near field capacity up to –200 hPa, O2 transport was limited, causing a decline in oxygen partial pressures (pO2) to values between 0 and 3 kPa at the root surface. Aerobic respiration increased by a factor of 100 when comparing the saturated with the driest status. At an air-filled porosity of 9% to 12%, diffusion of O2 increased considerably. This was confirmed by EH around 300 mV under aerated conditions, while EH decreased to 100 mV on the root surface under near water-saturated conditions. Gradients of pO2 and pH from the root surface indicated an extent of the rhizosphere effect of 10–20 mm. In contrast, EH gradients were observed from 0 to 2 mm from the root surface. We conclude that the rhizosphere extent differs for various parameters (pH, Eh, pO2) and is strongly dependent on soil moisture.
Uusheimo, Sari et al (2018), Mitigating agricultural nitrogen load with constructed ponds in northern latitudes: A field study on sedimental denitrification rates, Agriculture, Ecosystems & Environment, vol. 261, 71 - 79
Mitigating agricultural nitrogen load with constructed ponds in northern latitudes: A field study on sedimental denitrification ratesUusheimo, Sari, Tulonen, Tiina, Aalto, Sanni L., Arvola, Lauri (2018), Agriculture, Ecosystems & Environment, vol. 261, 71 - 79
Constructed agricultural ponds and wetlands can reduce nitrogen loading from agriculture especially in areas where warm climate predominates. However, in cold climate temperature-dependency of microbiological processes have raised the question about the applicability of constructed wetlands in N removal. We measured in situ denitrification rates in a constructed agricultural pond using 15N-isotope pairing technique at ambient light and temperature throughout a year as well as diurnally. The field IPT measurements were combined with a wide set of potentially important explanatory data, including air temperature, photosynthetically active radiation, precipitation, discharge, nitrate plus other water quality variables, sediment temperature, oxygen concentration and penetration depth, diffusive oxygen uptake and sediment organic carbon. Denitrification varied, on average, diurnally between 12 and 314??mol?N?m?2?h?1 and seasonally between 0 and 12409??mol?N?m?2?d?1. Light and oxygen regulated the diel variation of denitrification, but seasonally denitrification was governed by a combination of temperature, oxygen and turbidity. The results indicated that the real N removal rate might be 30–35% higher than the measured daytime rates, suggesting that neglecting the diel variation of denitrification we may underestimate N removal capacity of shallow sediments. We conclude, that by following recommended wetland:catchment – size ratios, boreal agricultural ponds can efficiently remove nitrogen by denitrification in summer and in autumn, while in winter and in spring the contribution of denitrification might be negligible relative to the loading, especially with short residence time.