Ultraviolet Irradiation of Suspensions of Micro‐organisms: Possible Errors Involved in the Estimation of Average Fluence Per Cell*

Jagger, John; Fossum, Tore; Mccaul, Scott

doi:10.1111/j.1751-1097.1975.tb06690.x

Cited by 29 publications

(10 citation statements)

References 3 publications

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“…It is necessary to irradiate at high cell densities in order to obtain sufficient cells in each sample to assay uptake within the period (1 min) during which uptake is linear. Due to light scatter and cell shielding (self absorption) the average dose received by a cell is less than the measured dose especially at short wavelengths (Jagger, 1967;Jagger et al, 1975). However, most of the light scattered by a bacterial suspension is deflected only a few degrees (Koch, 1961) and should be considered as transmitted light for the purposes of correction.…”

Section: Methodsmentioning

confidence: 99%

“…However, most of the light scattered by a bacterial suspension is deflected only a few degrees (Koch, 1961) and should be considered as transmitted light for the purposes of correction. As shown by Jagger (1975). the use of a spectrophotometer provides a true Morowitz (1950) correction, providing its design allows for maximal collection of scattered light by the photomultiplier.…”

Section: Methodsmentioning

confidence: 99%

“…These artifacts may be caused by leakage of photosensitizing cellular constituents in the dense suspensions. Attempts were made to obtain true Morowitz correction factors by measuring the lethal effect of different wavelengths at different cell concentrations, as described by Jagger (1975). This was successful for the shorter wavelengths only where irradiation times are short but was not successful for the longer wavelengths.…”

Section: Methodsmentioning

confidence: 99%

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SIMILAR SPECTRA FOR THE INACTIVATION BY MONOCHROMATIC LIGHT OF TWO DISTINCT LEUCINE TRANSPORT SYSTEMS IN ESCHERICHIA COLI

Robb¹,

Hauman²,

Peak³

1978

Photochem & Photobiology

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Abstract—Kinetics of inactivation of two separate leucine transport systems (leucine specific and LIV) in E. coli by seven wavelengths of monochromatic light have been studied. Loss of leucine uptake is not due to generalized membrane damage causing non‐specific leucine leakage. Inactivations are usually exponential but some wavelengths show shoulders at low doses. Two‐component spectra between 254 and 435 nm occur for both transport systems. Inactivation is most efficient at 290 nm and a second peak occurs at 365 nm. Both leucine transport systems are inactivated similarly.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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SIMILAR SPECTRA FOR THE INACTIVATION BY MONOCHROMATIC LIGHT OF TWO DISTINCT LEUCINE TRANSPORT SYSTEMS IN ESCHERICHIA COLI

Robb¹,

Hauman²,

Peak³

1978

Photochem & Photobiology

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“…The optical densities of such suspensions were high, varying from 1 to 6 from experiment to experiment depending on the extent to which the suspension was depleted of blood and blood cells before irradiation. We have corrected the incident doses to give average doses through mixed samples (16) but the corrections may have large errors (17) and hence a strict dosimetric comparison from one experiment to another is not valid although comparisons within an experiment are valid.…”

mentioning

confidence: 99%

Evidence that pyrimidine dimers in DNA can give rise to tumors.

Hart¹,

Setlow²,

Woodhead³

1977

Proc. Natl. Acad. Sci. U.S.A.

239

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ABSTRACr The Amazon molly, Poecilia formosa, is a small fish that grows in clones. Hence, cells from one animal may be transplanted to another without danger of rejection. Cells from thyroid and adjacent tissue were irradiated with UV light in vitro and injected into the abdominal cavity of isogeneic recipients. At appropriate UV doses and numbers of cells injected, all recipients showed exuberant thyroid proliferation. We give arguments and data indicating that the proliferation is a tumor, not a goitrogenic response. If the UV irradiation is followed, but not preceded, by photoreactivating illumination, the yield of thyroid growths is markedly decreased. Because other investigtions have shown that photoreactivation monomerizes UV-induced cyclobutylpyimiine dimers in DNA and does not affect other photoproducts, our data indicate that pyrimidine dimers in DNA can give rise to tumors. A number of physical and chemical environmental agents damage DNA in vivo. Many of these agents are carcinogenic (1-3),-and various mutagen test systems show that there is an excellent correlation between carcinogenicity and DNA damage as measured by mutagenesis (4). Nevertheless, because treatment of DNA with carcinogens results in the formation of many products, it has not been possible to identify particular molecular changes in DNA as initiating carcinogenic events. To make such an identification, one needs an experimental trick that will change the relative proportions of the various products and permit observation of how tumor induction depends on these proportions. UV radiation makes many types of photoproducts in DNA. One of these-cyclobutylpyrimidine dimers (pyrimidine dimers)-has been shown to have lethal and mutagenic effects in microorganisms by virtue of the fact that such dimers can be monomerized by photoreactivating (PR) enzyme plus light of wavelength >320 nm (5, 6). Because, to the best of our knowledge, enzymic photoreactivation works only on pyrimidine dimers and not on other products, our finding of a PR effect strongly implicates pyrimidine dimers as the important initial DNA damage in tumor induction.There is excellent evidence that most human skin cancer arises from solar UV radiation (7) and it is a good inference that DNA is the target molecule (8 (12), cooked spinach (6), marine fish meal (6), high-protein baby cereal (4), wheat germ (2), and iodized salt (1).Cell Isolation and Injections. Donor animals (2-3 months old, 2 cm long) were placed on ice for 5 min and then given 3-min washes in each of 2.6% sodium hypochlorite, cold 95% ethanol, and sterile fish Ringer's solution. Scales were removed and tissue was excised from along the ventral aorta. The excised region contained thyroid, muscle, and cardiac tissue (from the thyroid gland, urohyal, and heart, respectively). Tissues were pooled and homogenized in fish Ringer's solution without Ca2+ or Mg2+ and containing isoniazid (0.7 mg/ml), streptomycin (1 ,sg/ml), and penicillin (1000 units/ml). Homogenization yielded primarily small clumps of two to five ...

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“…A 3 mf aliquot of mitochondrial suspension (2 mg mitochondrial protein per mf giving approximately 12% transmittance at 254 nm as measured with an Aminco DW-2 UV-visible spectrophotometer) was added to a small vial to a depth of 5mm. The suspension was maintained on crushed ice and constantly stirred during exposure to mercury vapour ultraviolet light from a General Electric G4T4/1 germicidal fluorescent lamp (90% radiant energy at 254 nm) at a distance of 15 cm for 2.5, 5.0 and 15.0 min, yielding dosages, following correction for turbidity as described by Morowitz (1950) and following the recommendations of Jagger et al (1975) to minimize scattered light losses using the Aminoc DW-2 spectrophotometer in determining turbidity, of 150, 300 and 900J/m2. Fluence rate at 254nm was estimated to be l.OJ/mz/s by potassium ferrioxalate actinometry using an actively stirred 3 me sample in a cylindrical cuvette (2.5 cm in diameter) filled to a depth of 0.5 cm assuming 471 nJ/mol, a quantum yield of 1.26 and total absorption of photons by the actinometer solution.…”

Section: Isolation Of Bean Mitochondriamentioning

confidence: 99%

THE EFFECTS OF FAR ULTRAVIOLET RADIATION ON RESPIRATION AND CATION ACCUMULATION BY ISOLATED MITOCHONDRIA OF PHASEOLUS VULGARIS

Roy

Abboud

1978

Photochem & Photobiology

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Abstract. The respiration rates and respiratory control ratios of isolated bean mitochondria have been measured following exposure to 0, 150, 300 and 900 J/m2 of far UV radiation (190–300 nm) from a mercury vapour light source with 90% total radiant intensity at 254 nm. Loss of respiratory control occurred at 150 J/m2 and inhibition of respiration was significant at the highest exposure dosage. The uptake of both 45Ca and 85Sr have been measured following a 10min incubation of isolated mitochondria with 2 mM cation. Significant decreases in cation accumulation were observed following exposure to 900 J/m2. The effect seemed to be associated with loss of active transport of the ions as a result of respiratory uncoupling or reduced electron transport. There was no significant effect of storage on respiration or ion transport nor was there any indirect effect of irradiated suspending medium on mitochondria.

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Ultraviolet Irradiation of Suspensions of Micro‐organisms: Possible Errors Involved in the Estimation of Average Fluence Per Cell*

Cited by 29 publications

References 3 publications

SIMILAR SPECTRA FOR THE INACTIVATION BY MONOCHROMATIC LIGHT OF TWO DISTINCT LEUCINE TRANSPORT SYSTEMS IN ESCHERICHIA COLI

SIMILAR SPECTRA FOR THE INACTIVATION BY MONOCHROMATIC LIGHT OF TWO DISTINCT LEUCINE TRANSPORT SYSTEMS IN ESCHERICHIA COLI

Evidence that pyrimidine dimers in DNA can give rise to tumors.

THE EFFECTS OF FAR ULTRAVIOLET RADIATION ON RESPIRATION AND CATION ACCUMULATION BY ISOLATED MITOCHONDRIA OF PHASEOLUS VULGARIS

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