| 1. |
- Henriksson, M, et al.
(författare)
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Nuclear colocalization of c-myc protein and hsp70 in cells transfected with human wild-type and mutant c-myc genes
- 1992
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Ingår i: Experimental Cell Research. - 0014-4827. ; 203:2, s. 94-383
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Tidskriftsartikel (refereegranskat)abstract
- Using immunofluorescence and electron microscopy we have studied the localization of wild-type and mutant c-myc proteins transiently expressed in CV-1 cells. In agreement with our previous observations, wild-type c-myc protein accumulated in large amorphous globules in the nucleus. All mutant proteins tested accumulated in the nucleus as well, but gave rise to morphologically different inclusion bodies. Many small globules appeared in cells transfected with D145-262 (deletion of amino acids 145-262), while cells transfected with D371-412 or D414-433 generated structures looking like a fine network or like beads on a string. In addition, a particulate cytoplasmic staining appeared in some cells transfected with the wild-type gene and in cells transfected with mutants D145-262 or D414-433. Since the c-myc protein has been reported to stimulate expression of exogenous hsp70 protein, we also examined the intracellular distribution of hsp70 in the transfected cells. Double immunofluorescence microscopy revealed that hsp70 codistributed with the c-myc protein in distinct globules in the nucleus of many but not all myc-positive cells. However, the levels of hsp70 transcripts were not significantly raised compared to nontransfected and vector-transfected cells. Likewise, the levels of hsp70 protein did not vary significantly. These findings indicate that overexpression of c-myc stimulates translocation of preexisting hsp70 from the cytoplasm into the nucleus, rather than influencing hsp70 expression. Conceivably, this may represent one of several mechanisms whereby the cell deals with excessive amounts of c-myc protein.
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| 2. |
- Sjöberg, M, et al.
(författare)
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A comparison of the counterion binding to ionic micelles in aqueous and nonaqueous systems
- 1992
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Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 8, s. 409-413
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Tidskriftsartikel (refereegranskat)abstract
- The counterion binding to hexadecyltrimethylammonium fluoride (C16TAF) micelles in three different solvents; water, formamide and ethylene glycol, has been studied both experimentally and theoretically. Self-diffusion measurements by NMR spectroscopy was used as the experimental technique, and the counterion binding was determined for surfactant concentrations up to 20 wt%. The degree of counterion binding was found to be very different in the three solvents; high in water and ethylene glycol but much lower in formamide, with an increase with concentration in the latter system. The Poisson-Boltzman equation was used to calculate how the aggregation number and the dielectrical constant of the solvent affect the counterion binding. A comparison between experimental and calculated values of degrees of counterion binding indicates that the micelles are significally smaller in the non-aqueous systems. The concentration dependence of the counterion binding in formamide was explained as aggregate growth with increasing surfactant concentration.
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| 3. |
- Sjöberg, M, et al.
(författare)
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2H Nuclear magnetic relaxation of 1.1-2H hexadecyltrimethylammonium bromide in micellar solutions of nonaqueous polar solvents and their mixtures with water
- 1990
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Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 6, s. 1205-1211
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Tidskriftsartikel (refereegranskat)abstract
- The 2H spin-lattice and spin-spin nuclear magnetic relaxtion rates were measured at different frequencies for α-deuterated hexadecyltrimethylammonium bromide in micellar solutions of nonaqueous and mixed solvent systems. Three nonaqueous polar solvents, viz., formamide, ethylene glycol, and N-methylformamide, and their mixtures with water were used. The two-step model for magnetic relaxation of surfactant aggregates was fitted to the frequency-dependent relaxation rates for the surfactant, yielding a local order parameter and correlation times for a fast local motion and for a slow aggregate motion. The measurements show that the surfactant aggregates in formamide, ethylene glycol, and their mixtures with water. No aggregation occurs in N-methylformamide at water contents lower than 50 wt%. Approximate aggregate radii, obtained from the slow correlation times, show that the aggregates formed in formamide and in ethylene glycol are smaller than in water. The local order parameter, obtained from the relaxation measurements as well as from the quadrupolar splittings in the hexagonal phases, increases with increasing water content both in the formamide and in the ethylene glycol systems.
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