Asunto(s)
Virus de la Encefalitis Transmitidos por Garrapatas/efectos de la radiación , Rayos Ultravioleta , Activación Viral/efectos de la radiación , Animales , Relación Dosis-Respuesta a Droga , Virus de la Encefalitis Transmitidos por Garrapatas/inmunología , Virus de la Encefalitis Transmitidos por Garrapatas/aislamiento & purificación , Formaldehído/farmacología , Hemaglutinación por Virus/efectos de la radiación , Inmunización , Ratones , Ratones Endogámicos BALB C , Activación Viral/efectos de los fármacosRESUMEN
Kinetics of the UV-induced (lambda = 254 nm) inactivation of phage MS2 is studied for stirred and non-stirred solutions with optical densities ranging from 0.06 to 2.1. The extent of inactivation exhibits exponential dependence on irradiation time for stirred solutions thus indicating the homogeneity of the phage population in respect to photosensitivity of infectivity. Irradiation of the same solution without stirring results in deviation of survival curves from exponential ones (the so called "tailing"), being more pronounced the larger the optical density of the layer under irradiation and degree of inactivation. Such a deviation is conditioned by non-uniform light absorption by virions in solution in the absence of stirring. The inactivation kinetics upon UV-irradiation of the stirred and non-stirred phage solutions is rather accurately expressed by respective equations thus enabling the choice of rational conditions for a given depth of phage inactivation to be performed.
Asunto(s)
Colifagos/efectos de la radiación , Genes Virales/efectos de la radiación , Tolerancia a Radiación , Escherichia coli , Cinética , Matemática , Movimiento (Física) , Rayos UltravioletaRESUMEN
A spectrophotometric method for determination of the modification degrees and molar extinction coefficients for poly(A, epsilonA) and poly(C, epsilonC) copolymers has been developed. Dependence of some absorption and fluorescence parameters of the copolymers on the modification degree has been studied. Distribution of modified residues in copolymers differs from random and depends on modification conditions. Interaction between the TMV protein and copolymers has been investigated. The protein interacts with poly(A, epsilonA) of low or medium modification degree and displays no activity with respect to poly(epsilonA). On the contrary, introduction of epsilonC to the polynucleotide promotes complex formation between poly(C, epsilonC) and TMV protein. Analysis of the fluorescence emission and excitation spectra has revealed energy transfer from tryptophan to epsilonA or epsilon C in the RNP to occur and permits one to estimate the average distance between Trp (presumably Trp 52)o and the RNA base binding region in the virus to be 17 to 20 A.
Asunto(s)
Adenina/análogos & derivados , Citosina/análogos & derivados , Nucleoproteínas , Polirribonucleótidos , Ribonucleoproteínas , Proteínas Virales , Dicroismo Circular , Colorantes Fluorescentes , Conformación de Ácido Nucleico , Poli A , Poli C , Unión Proteica , Espectrometría de Fluorescencia , Virus del Mosaico del TabacoRESUMEN
Interaction of cytidine 5'-phosphate with chloroacetone or p-tosyloxyacetone leads to 2-methyl-5,6-dihydro-5-oxo-6-(5-0-phospho-beta-D-ribofuranosyl)-imidazo/1,2-c/pyrimidine (2-methylethenocytidine 5'-phosphate) whereas analogous reaction with phenacyl bromide produces similar 2-phenyl-derivative. The bicyclic nucleotides obtained showed significant UV absorption at long wavelength where common nucleotides and proteins exhibited no absorption. These derivatives are highly fluorescent when heterocyclic ring is protonated. The absorption and fluorescent properties of the substituted ethenocytidine 5'-phosphoate derivatives seem to be suitable for their use as fluorescent probes or labels in biochemical studies.