摘要:

Abstract—Results of experiments on reactivation of ultraviolet (u.v.)‐irradiatedHaemophilus influenzaeand cellular reactivation of u.v.‐damaged transforming deoxyribonucleic acid (DNA) and bacteriophage are reported. Liquid‐holding recovery (LHR) is small for the u.v.‐sensitive mutant BC100 which, relative to the wild type, also has greatly reduced host‐cell reactivation (HCR) of u.v.‐inactivated phage, and competent cultures show reduced competent cell reactivation (CCR) of u.v.‐inactivated transforming DNA. BC100 cells can be transformed with DNA isolated from the wild type strain Rd to a u.v. resistance similar to that of Rd, and irradiation of the DNA reduces the transformation frequency for this marker (uvr). The u.v.‐resistant mutant BC200 displays very little LHR under the usual conditions where reactivation occurs after plating. The colony‐forming ability (cfa) of irradiated BC200 is greater than that of Rd, but HCR and CCR are the same on this mutant as on the wild type. The major difference between Rd and BC200 is the enhanced u.v. survival ofcfaof the latter. It was determined that this difference reflects cell lysis of irradiated Rd and lack of lysis in BC200 cultures. That lysis is closely correlated with damage to the bacterial chromosome is suggested by the finding that the lytic response of Rd (as determined turbidimetrically) can be negated by the liquid‐holding procedure, but lysis of BC100 (which lacks comparable DNA‐repair ability) can be only partially inhibited by this procedure. LHR occurs when post‐plating dark recovery is incomplete, is temperature‐sensitive, and occurs unimpeded when post‐u.v. protein synthesis is inhibited by chloramphenicol. It is suggested that enzymatically catalyzed reactivation of DNA occurs or is initiated during liquid‐holding of u.v.‐irradiatedH. influenzaeRd and that the necessary enzyme(s) exists prior to appearance of u.v. lesions in the DNA. Results are reported for X‐ray inactivation of transforming DNA as assayed on BC100, Rd and BC20

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05983.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The photosensitized monomerization ofcis‐synandtrans‐syncyclobutane‐type thymine dimers, and thecis‐synthymine‐uracil dimer, using anthraquinone derivatives as sensitizers, i

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05984.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The photoinactivation of an osmotic shock resistant mutant of the bacteriophageT4 can be sensitized by two cationic derivatives of acetophenone. At least part of the sensitized inactivation appears to be due to the formation of thymine dimers in phage DNA by a mechanism which involves triplet excitation transfer from the sensitizer to thymine in the DNA. The photoreactivable sector of the phage inactivated by sensitized irradiation is about 0.6, almost twice as large as the sector for u.v. irradiated phag

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05985.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Chemiluminescence in the visible region during liquid‐phase hydrocarbon oxidation is excited by peroxy radical disproportionation; a carbonyl compound,P, in the triplet state is the emitter. Several types of energy transfer fromPto acceptors are considered. These provide valuable information (lifetimes, rate constants, emission yields) relevant to triplet state molecules. The excitation yields are estimated making use of this information, the absolute chemiluminescence intensities and the reaction rates. Electronic excitation ofP, vibrational excitation of ground statePand reverse decomposition of an intermediate complex into initial peroxy radicals are considered as competing processes strongly dependent on transformation of chemical energy into vibrati

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05986.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Laser micro‐irradiation was used to study the uptake of low levels of strain (Janus Green B) by the mitochondria of tissue culture cells and the selective lesions induced by the irradiation. A comparison of the thermal effects produced in the cells and in a stained model system (albumin), permitted the calculation of the degree of concentration of stain in the mitochondria from the staining media (approximately 500 fold). Evaluation of the various parameters of Laser irradiation, particularly thermal events, resulted in optimal irradiation times for measurement of local stain concentration, as well as for the selective destruction of the stained mitochondria. For the studies of the latter phenomenon a lower limit for irradiation duration is set by optical saturation and dielectric breakd

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05987.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05988.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05989.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05990.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY