IV. Chemical Restoration in Irradiated Micro-Organisms

Latarjet, R; Caldas, L.R.; Miletić, B; Morenne, P

doi:10.1259/0007-1285-27-313-54

Cited by 12 publications

(7 citation statements)

References 2 publications

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“…Irradiation procedure CV-1 cells grown in 14.5 cm plastic Petri dishes ( Greiner -Germany) were irradiated, after removal of the culture medium, with a single dose of UV-irradiation at different time intervals before the preparation of cellular crude extracts for DNA ligase assay (time zero). A Philips germicidal tube was used with a maximal emission at 254 m. The dose rate was 0.5 watt/m2, as measured by a Latarjet dosimeter (12). After irradiation, the medium previously removed was added back to the cultures which were incubated at 37C in the dark until time 0.…”

Section: Cellsmentioning

confidence: 99%

DNA ligase activity in UV-irradiated monkey kidney cells

Mezzina

Nocentini

1978

Nucl Acids Res

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The DNA ligase activity of monkey kidney CV-1 cells has been measured at different stages of culture growth and after different time intervals following ultraviolet irradiation. Results indicate that: - The level of enzyme activity is about twice higher in non synchronous, rapidly dividing cells than in confluent cultures. - UV-irradiation of cells induces a "de novo" synthesis of DNA ligase. - This induction is dose dependent in its extent and kinetics, and may lead to a DNA ligase level in UV-irradiated stationary cultures of the same order as observed in unirradiated exponentially growing cells. - This induction seems to be independent of semiconservative DNA synthesis since it is not affected by fluorodeoxyuridine.

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Section: Cellsmentioning

confidence: 99%

DNA ligase activity in UV-irradiated monkey kidney cells

Mezzina

Nocentini

1978

Nucl Acids Res

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“…for 120 seconds. This corresponded to a 3200 erg/mm,S dose of 254 m~ radiation as calibrated from the rate of inactivation of "1"2 bacteriophage (20). The liquid layers irradiated were approximately 1 ram.…”

Section: Ultra~olet Irradiation Of Transforming Factor--mentioning

confidence: 99%

Photoreactivation in Vitro of Ultraviolet Inactivated Hemophilus Influenzae Transforming Factor

Rupert

Goodgal

Herriott

1958

The Journal of General Physiology

189

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/mSTRAC¢H~mopkilus influen~--transforming DNA, which has been inactivated by ultraviolet radiation, is reactivated by visible light in the presence of a cell-free extract of Eschcric~ia coli B.The time rate of reactivation is increased by increasing the E. coli extract concentration, the temperature, and the intensity of illumination.Only DNA containing an ultraviolet-damaged genetic marker exhibits increased transforming activity after treatment with the photoreactivatlng system.The reactivating capacity of the extract remains in the top supernatant after centrifugation at 110,000 X g for 1 hour and is not present in the pellet. This capacity is destroyed by heating to 90°C. for 1 minute.The active system of the E. cdi extract is separable into dialyzable, heat-stable and non-dialyzable, heat-labile fractions. The dialyzable fraction contains at least one component which limits the max-imum degree of recovery attained.Photoreactivation, the reversal of short wave length ultraviolet effects on organisms by subsequent treatment with visible light, was first specifically described by Keiner (1, 2) for survival of the ultraviolet-irradiated conidia of Streptomyces griseus. It has since been recognized for a variety of other ultraviolet effects in a large number of species and tissues (3), including interruption of DNA synthesis (4), production of mutations (5), induction of vegetative phage in lysogenic bacteria (6), inhibition of adaptive enzyme formation in yeast (7), spheration of nudeoli in the grasshopper neuroblast (8), delaying of cleavage in eggs (9), and delaying of division in protozoa (10). Its detailed mechanism is unknown. A possible outline of the process, however, is suggested by existing evidence. * Present address:

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“…Failure of been shown to occur in inorganic medium with reciprocity in this case may be caused by loss of 3400 to 5500 A, but is masked by killing in photoreactivability with time after inactivation. organic medium (109). Although the killing Kelner photoreactivated unwashed cells in saline, effect of near UV decreases rapidly as the wave * The Qio has been calculated from the data of the author(s).…”

Section: B/r Undergoes An Initial Lag Period That Is Notmentioning

confidence: 99%