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21.
22.
A role for the transient increase of cytoplasmic free calcium in cell rescue after photodynamic treatment. 总被引:1,自引:0,他引:1
L C Penning M H Rasch E Ben-Hur T M Dubbelman A C Havelaar J Van der Zee J Van Steveninck 《Biochimica et biophysica acta》1992,1107(2):255-260
Chinese hamster ovary (CHO) cells and T24 human bladder transitional carcinoma cells were treated with the photosensitizers aluminum phthalocyanine (AlPc) and hematoporphyrin derivative (HPD), respectively. Exposure of both sensitized cell lines to red light caused an immediate increase of cytoplasmic free calcium, [Ca2+]i, reaching a peak within 5-15 min after exposure and then returning to basal level (approximately 200 nM). The level of the peak [Ca2+]i depended on the light fluence, reaching a maximum of 800-1000 nM at light doses that kill about 90% of the cells. Loading the cells with the intracellular calcium chelators quin2 or BAPTA prior to light exposure enhanced cell killing. This indicates that increased [Ca2+]i after photodynamic therapy (PDT) contributed to survivability of the treated cells by triggering a cellular rescue response. The results of experiments with calcium-free buffer and calcium chelators indicate that both in CHO cells treated with AlPc and with HPD-PDT of T24 cells extracellular Ca2+ influx is mainly responsible for elevated [Ca2+]i. PDT is unique in triggering a cell rescue process via elevated [Ca2+]i. Other cytotoxic agents, e.g., H2O2, produce sustained increase of [Ca2+]i that is involved in the pathological processes leading to cell death. 相似文献
23.
Tom Zee Frans Stellaard Cornelis Jakobs 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1992,574(2)
A sensitive and accurate stable isotope dilution assay was developed for the measurement of pipecolic acid in body fluids using capillary gas chromatography with electron-capture detection. The method utilizes [2H11]pipecolic acid as the internal standard. Sample preparation consisted of derivatization in aqueous solution (pH 11.5) of the amine moiety with methyl chloroformate to the N-methylcarbamate, followed by acidic ethyl acetate extraction at pH ≤ 2 and further derivatization of the carboxyl moiety with pentafluorobenzyl bromide, the excess of which was removed by solid-phase extraction. Control values have been determined in the plasma of at-term infants, age > 1 week (n = 21, mean = 1.36 μM, range = 0.47–3.27 μM). The utility of the method was demonstrated by quantitating pipecolic acid in biological fluids derived from patients with peroxisomal disorders. The method was validated against an established electron-capture negative ion mass fragmentographic technique. 相似文献
24.
S. -Y. Zee 《Protoplasma》1981,107(1-2):21-26
Summary The petiole expiants of coriander when cultured on a solid or liquid Murashige and Skoog's medium supplemented with 0.5 mg/l 2,4-D developed a large number of meristemoids. These meristemoids could then be induced to form adventive embryos when transferred into a liquid MS-medium without 2,4-D. The development of the expiants leading to the formation of meristemoids was followed anatomically and by using SDS-polyacrylamide gel electrophoresis of soluble proteins at various days of culture. 相似文献
25.
26.
Isaac Okyere Juliet Afrah Obeng Samuel Ayitey Jouke Rients Van der Zee Herman Meeus 《Journal of fish biology》2021,99(2):411-417
Aside from ornamental uses, there is growing interest in using killifishes for a multiplicity of purposes including baitfish and mosquito biocontrol. This experiment explored the spawning habits and embryonic development of the banded lampeye, Aplocheilichthys spilauchen in ex situ freshwater (0.04‰) and brackish water (5.01‰) to ascertain the captive breeding prospects for mosquito control in areas where they occur. Significantly higher number of eggs were laid in the brackish water than the freshwater (X2 = 1613.0, P < 0.05), and black mop was the most preferred spawning substrate, followed by green, blue and white mops. Microscopic monitoring of embryos revealed that cleavage occurred within the first 30 min after fertilization, organogenesis commenced on average in the 25th hour and hatching in approximately 230 h. Although freshwater eggs were relatively bigger than brackish water eggs and certain embryonic developmental stages occurred faster in the freshwater than brackish water, these differences were overall not significant and had no effects on the development and hatching. The observed outcome that A. spilauchen can be optimally propagated with black mops in brackish water offers a significant step in its use for the mosquito biocontrol programme, as well as other potential uses not yet explored. 相似文献
27.
Tony Hadibarata Zee Chuang Teh Rubiyatno Meor Mohd Fikri Ahmad Zubir Ameer Badr Khudhair Abdull Rahim Mohd Yusoff Mohd Razman Salim Topik Hidayat 《Bioprocess and biosystems engineering》2013,36(10):1455-1461
The use of biomaterials or microorganisms in PAHs degradation had presented an eye-catching performance. Pleurotus eryngii is a white rot fungus, which is easily isolated from the decayed woods in the tropical rain forest, used to determine the capability to utilize naphthalene, a two-ring polycyclic aromatic hydrocarbon as source of carbon and energy. In the meantime, biotransformation of naphthalene to intermediates and other by-products during degradation was investigated in this study. Pleurotus eryngii had been incubated in liquid medium formulated with naphthalene for 14 days. The presence of metabolites of naphthalene suggests that Pleurotus eryngii begin the ring cleavage by dioxygenation on C1 and C4 position to give 1,4-naphthaquinone. 1,4-Naphthaquinone was further degraded to benzoic acid, where the proposed terepthalic acid is absent in the cultured extract. Further degradation of benzoic acid by Pleurotus eryngii shows the existence of catechol as a result of the combination of decarboxylation and hydroxylation process. Unfortunately, phthalic acid was not detected in this study. Several enzymes, including manganese peroxidase, lignin peroxidase, laccase, 1,2-dioxygenase and 2,3-dioxygenase are enzymes responsible for naphthalene degradation. Reduction of naphthalene and the presence of metabolites in liquid medium showed the ability of Pleurotus eryngii to utilize naphthalene as carbon source instead of a limited glucose amount. 相似文献
28.
Predicting zinc bioavailability to wheat improves by integrating pH dependent nonlinear root surface adsorption 总被引:1,自引:0,他引:1
Andreas Duffner Ellis Hoffland Liping Weng Sjoerd E. A. T. M. van der Zee 《Plant and Soil》2013,373(1-2):919-930
Aim
Our aim was to improve the prediction of Zn bioavailability to wheat grown on low-Zn soils. The classical approach that directly relates Zn in a certain soil extract to Zn uptake has been shown to be inadequate in many cases. We tested a stepwise approach where the steps of the uptake process are characterized with, respectively, Zn solid-solution distribution, adsorption of Zn to root surface, Zn uptake into root and Zn translocation to shoot.Methods
Two pot experiments were done with wheat grown on nine low-Zn soils varying widely in pH, clay and organic matter content. Soluble Zn concentrations in two soil extracts (DTPA and CaCl2) were measured. Free Zn ion concentrations in CaCl2 soil extracts were determined with the Donnan Membrane Technique. These Zn concentrations were then related to plant Zn uptake following both the direct and the stepwise approach.Results
In the direct approach, Zn in the DTPA extract was a better predictor for shoot Zn uptake than Zn in the CaCl2 extract. In the stepwise approach, the relationship between Zn in CaCl2 extracts and the root surface adsorbed Zn was pH-dependent and nonlinear. Root surface adsorbed Zn was linearly related to root Zn uptake, and the latter was linearly related to the shoot Zn uptake. The stepwise approach improved the Zn uptake prediction compared to the direct approach and was also validated for different wheat cultivars.Conclusions
The adsorption of Zn on the root surface is pH dependent and nonlinear with respect to the soil Zn concentration, and a useful proxy for bioavailable Zn over a wide range of soils. 相似文献29.
Manaswini Sivaramakrishnan Tristan I. Croll Rajesh Gupta Dario Stupar Derek R. Van Lonkhuyzen Zee Upton Gary K. Shooter 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2013,1833(12):3176-3185
Numerous studies have reported associations between IGF-I and other extra cellular matrix (ECM) proteins, including fibronectin (FN), integrins, IGF-binding proteins (IGFBPs) and through IGFBPs, with vitronectin (VN). Nevertheless, the precise nature and mechanisms of these interactions are still being characterised. In this paper, we discuss transglutaminases (TGases) as a constituent of the ECM and provide evidence for the first time that IGF-I is a lysine (K)-donor substrate to TGases. When IGF-I was incubated with an alpha-2 plasmin inhibitor-derived Q peptide in the presence of tissue transglutaminase (TG2), an IGF-I:Q peptide cross-linked species was detected using Western immunoblotting and confirmed by mass spectrometry. Similar findings were observed in the presence of Factor XIIIa (FXIIIa) TGase. To identify the precise location of this K-donor TGase site/s on IGF-I, all the three IGF-I K-sites, individually and collectively (K27, K65 and K68), were substituted to arginine (R) using site-directed mutagenesis. Incubation of these K→R IGF-I analogues with Q peptide in the presence of TG2 or FXIIIa resulted in the absence of cross-linking in IGF-I analogues bearing arginine substitution at site 68. This established that K68 within the IGF-I D-domain was the principal K-donor site to TGases. We further annotated the functional significance of these K→R IGF-I analogues on IGF-I mediated actions. IGF-I analogues with K→R substitution within the D-domain at K65 and K68 hindered migration of MCF-7 breast carcinoma cells and correspondingly reduced PI3-K/AKT activation. Therefore, this study also provides first insights into a possible functional role of the previously uncharacterised IGF-I D-domain. 相似文献
30.