Partial recovery of ultraviolet-damaged denatured or native transforming DNA from Hemophilus influenzae, has been obtained by exposing the irradiated DNA in the denatured form to nitrous acid. Some factors that affect this recovery are described. An erythromycin marker (E(20)) was not reactivated. The UV damage reactivable by nitrous acid is different from that repaired by the photoreactivating...

Pre-irradiation starvation of exponentially growing Escherichia coli B/r Hcr+ thy-try- strain for thymine and tryptophan causes inhibition of pyrimidine dimer excision from ultraviolet damaged cells DNA. This inhibition of excision repair has not resulted in increasing ultraviolet sensitivity nor in increasing frequency of ultraviolet induced tryptophan revertants. The possible mechanisms of th...

The photocatalytic activity of meso-tetraphenylporphyrins with different metal centers (Fe, Co, Mn and Cu) adsorbed on TiO(2) (Degussa P25) surface has been investigated by carrying out the photodegradation of methyl orange (MO) under visible and ultraviolet light irradiation. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectan...

A facile approach for the preparation of crosslinked polymeric nanocapsules was developed by the combination of the surface-initiated atom transfer radical polymerization and ultraviolet irradiation crosslinking techniques. The well-defined polystyrene grafted silica nanoparticles were prepared via the SI-ATRP of styrene from functionalized silica nanoparticles. Then the grafted polystyrene cha...

Kelner (J. Bacteriol., 65, 252, 1953), has found that ultraviolet irradiation inhibits deoxyribonucleic acid synthesis in Escherichia coli strain B/r. He sometimes observed a resumption of this synthesis after a certain period of postirradiation incubation. This has also been reported by Kanazir and Errera (Cold Spring Harbor Symposia Quant. Biol., 21, 19, 1956). As most of the irradiated cells...

N Habrobracon, unfertilized eggs develop normally and become haploid males; I fertilized eggs become diploid females. It has been observed that when newlylaid eggs from virgin females are exposed to ultraviolet radiation on the nuclear (convex) surfaces, embryo hatchability decreases as the exposure time is increased (VON BORSTEL and MOSER 1956; VON BORSTEL and WOLFF 1955). Most of the deaths o...

Growth of the ultraviolet-irradiated cell is of special interest. Growthmay offer a simpler measure of radiation effect than survival. Growth after irradiation is a reflection of events in the latent or middle period between the irradiation and the end biological result (Kelner, 1954; Latarjet and Gray, 1954; Kelner et al., 1955; Barner and Cohen, 1956). During this period the ultraviolet damag...

We examined the wavelength dependence of ultraviolet (UV) ra-diation (UVR)-induced melanoma in a Xiphophorus backcross hybrid model previously reported to be susceptible to melanoma induction by ultraviolet A (UVA) and visible light. Whereas ultraviolet B (UVB) irradiation of neonates yielded high frequencies of melanomas in pigmented fish, UVA irradiation resulted in melanoma frequencies that ...

Clarified and standardized apple juice was ultraviolet-irradiated to inactivate polyphenol oxidase enzyme and microbiota, and its effect on bioactive compounds and stability during storage was also evaluated. Apple juice was irradiated with 345.6 J/cm² and treatment effect was evaluated in terms of color, antioxidant capacity, polyphenol content, pH, titratable acidity and total soluble solids....