Lethal and Mutagenic Action of Black Light (325 to 400 nm) on Haemophilus influenzae in the Presence of Air

Abstract

Near-ultraviolet (UV) light (325 to 400 nm), in the presence of air and the absence of exogenous photosensitizing compounds, is lethal and mutagenic for Haemophilus influenzae. The lethal effect is the same for both wild type and streptomycin-resistant mutants, indicating that the mutants are not selected by the irradiation. The inactivation and mutagenicity show a large shoulder, suggesting the existence of repair systems. Filters were used to eliminate the possibility of short-UV irradiation. The effective radiation is between 325 to 400 nm. The lethal and mutagenic effects are higher during mid and late log phase than during early log or stationary phase.on August 1, 2020 by guest

GENETIC CONTROL OF NEAR‐UV (300–400nm) SENSITIVITY INDEPENDENT OF THE recA GENE IN STRAINS OF ESCHERICHIA COLI K12

“…We have attempted to measure far-UV coming through pyrex glass and find the material opaque to these wavelengths. Fourth, in a single experiment with the strain AB2463, we used a napthalene filter (Blanc et al, 1976;Cabrera-Juarez and Espinosa-Lara, 1974) and observed that following a 1.2 Jm-' x dose of unfiltered near-UV survival was approximately 55% while filtering yielded 100% survival. Following a 1.8 Jm-2 x dose of near-UV, survival with filtered near-UV was 23.3% while survival with unfiltered near-UV was 17.8%.…”

“…The sensitivity of bacterial cell populations to inactivation by both far-UV (Tyrrell et al, 1972) and near-UV varies with growth phase (Cabrera-Juarez and Espinosa-Lara, 1974;Hartman and Eisenstark, 1978;Mackay et a/., 1976). Our results and those of others (Peak, 1970;Webb, 1977) show that resistance to near-UV increases exponentially when the cells enter the transition from the exponential to stationary growth phase (Fig.…”

“…At present, we cannot distinguish between these alternatives. Although many workers have investigated near-UV sensitivity using exponentially growing bacterial cell populations (Cabrera-Juarez and Espinosa-Lara, 1974;Eisenstark, 1970;Gopalakrishna and Bhattacharjee, 1976;Mackay et a/., 1976;Peak, 1970;Tyrrell, 1974;Tyrrell and Webb, 1973), we have chosen to center our attention on stationary cells to eliminate the possibility that some exponentially growing cells might have entered the transition from exponential to stationary growth where sensitivity changes dramatically. The complex near-UV inactivation curves presented for non-stationary cells of H .…”

BLACKLIGHT AND SHORTWAVE UV SENSITIVITY OF NEUROSPORA CRASSA AS A FUNCTION OF CULTURE AGE

“…Inactivation by blacklight (BL; 300-400 nm) has been investigated in procaryotes (Cabrera-Juarez and Espinosa-Lara, 1974;Eisenstark, 1970;Hollaender, 1943;Kock et al, 1976;Peak, 1970;Lorenz, 1970;Webb and Tai, 1970) and eucaryotes (Blanc et a!., 1976;Elkind and Han, 1977;Hollaender and Emmons, 1941). BL inactivation of transforming DNA (Blanc et ul., 1976;Cabrera-Juarez, 1964;Peak et al, 1973a, b, c).…”

“…BL inactivation of transforming DNA (Blanc et ul., 1976;Cabrera-Juarez, 1964;Peak et al, 1973a, b, c). and evidence for mutagenesis by BL in Escherichiu coli (Kubitschek, 1967;Webb and Malina, 1970) and Hapmophilus influenme (Cabrera-Juarez and Espinosa-Lara, 1974) have implicated DNA as the target for lethal damage. However, mutagenesis by BL irradiation could not be demonstrated in spores of either Neurospora crassu (Tuveson and Satterthwaite, 1976) or Trichophyton mentugrophytes (Hollaender and Emmons, 1941).…”