The enhancement of the mutagenic effect of ultraviolet radiation inEscherichia coli by caffeine and acriflavine

1968 ◽  
Vol 13 (5) ◽  
pp. 379-390 ◽  
Author(s):  
B. Věchet
Keyword(s):  
Ultraviolet Radiation ◽  
Mutagenic Effect ◽  
Inescherichia Coli

The mutagenic effect of ultraviolet radiation and nitrous acid onMycobacterium phlei

1966 ◽  
Vol 11 (3) ◽  
pp. 163-168 ◽  
Author(s):  
Miluše Radochová ◽  
J. Koníček ◽  
I. Málek
Keyword(s):  
Ultraviolet Radiation ◽  
Nitrous Acid ◽  
Mutagenic Effect

Effect of 5-fluorouracil posttreatment on sensitivity to ultraviolet radiation and course of messenger RNA synthesis inEscherichia coli cells

1971 ◽  
Vol 16 (2) ◽  
pp. 114-125 ◽  
Author(s):  
J. Brozmanová ◽  
M. Sedliaková ◽  
E. Štefunková ◽  
V. Slezáriková
Keyword(s):  
Ultraviolet Radiation ◽  
Messenger Rna ◽  
Rna Synthesis ◽  
Inescherichia Coli

COCHLIOBOLUS SATIVUS: III. EFFECT OF ULTRAVIOLET RADIATION

1960 ◽  
Vol 38 (3) ◽  
pp. 275-282 ◽  
Author(s):  
R. D. Tinline ◽  
J. F. Stauffer ◽  
J. G. Dickson
Keyword(s):  
Ultraviolet Radiation ◽  
Ultraviolet Light ◽  
Aerial Mycelium ◽  
Mutagenic Effect ◽  
Cochliobolus Sativus ◽  
Highly Pathogenic ◽  
Wheat Seedlings ◽  
Rate Of Growth ◽  
High Doses ◽  
Sporulation Rate

The lethal and mutagenic effect of ultraviolet light on two isolates of Cochliobolus sativus was studied. Conidia of a dark-spored strain were considerably more resistant to high doses of radiation than those of a white-spored strain. Ultraviolet radiation increased the frequency of mutation in the fungus. Mutants were recovered that differed from their parents in degree of sporulation, rate of growth, pigmentation, amount of aerial mycelium, topography and consistency of colony, and pathogenicity to wheat seedlings. Tetrads from crosses between weakly and highly pathogenic strains indicated that pathogenicity was not a clearly segregating character.

scholarly journals Repression of induction by u.v. of λ phage byexrAmutations inEscherichia coli

1970 ◽  
Vol 15 (1) ◽  
pp. 87-97 ◽  
Author(s):  
John Donch ◽  
Joseph Greenberg ◽  
Michael H. L. Green
Keyword(s):  
Escherichia Coli ◽  
Ultraviolet Radiation ◽  
Elevated Temperatures ◽  
Vegetative Reproduction ◽  
Inescherichia Coli ◽  
Heat Induction

SUMMARYThe effect of ultraviolet radiation (u.v.) onλlysogens ofexrAstrains ofEscherichia coliwas studied.exrAstrains could be lysogenized with, as well as support the vegetative reproduction of, λ. However, though spontaneous induction of λ occurred inexrA(λ) strain at 10% the frequency ofexrA+(λ) strain,exrA(λ) strains were not induced by u.v. Because λ was not induced inexrA(λ) strains, lysogens of these strains were no more sensitive to u.v. than were non-lysogens.The heat-inducible mutant λhcI857could be induced inexrAstrains at elevated temperatures. Furthermore, u.v. irradiation ofexrA(λhcI857) strain did not prevent the heat induction of this λ mutant. TheexrAmutation appeared to interfere only with the inactivation of λ repressor by u.v.Among theexrAstrains studied was strainBs1(exr A uvrB). Whereas the λ lysogen of strain Bsl could not be induced by u.v. and was no more sensitive to u.v. than its non-lysogen, theexrA+uvrB(λ) derivative of strain Bsl could be induced by u.v. and was more sensitive to u.v. than its non-lysogen.

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

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