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Ultraviolet-inactivation of conidia from heterokaryons of Neurospora crassa containing uv-sensitive mutations

Description: From 7th neurospora information conference; Asilomar, California, USA (25 Mar 1974). The effect of three uv-sensitive mutations of Neurospora crassa, upr-1, uvs-4 and uvs-6, on the ultraviolet-inactivation of conidia from two- component heterokaryons was investigated. In twocomponent heterokaryons with wild-type sensitivity to radiation inactivation, all three conidial fractions exhibited similar ultraviolet-inactivation curves. Each uv-sensitive mutation studied uniquely modified the ultraviolet-inactivation curves of conidia from two- component heterokaryons. In heterokaryons heterokaryotic for upr-1, the upr-1 mutation was recessive and the repair function determined by the wild-type allele was functional to some degree in homokaryotic upr-1 conidia. All three conidial fractions of heterokaryons containing upr-1 in both components showed increased sensitivity to ultraviolet light. The uvs-4 mutation was recessive and resulted in conidia with increased uv-sensitivity only when included in both components of a heterokaryon. Homokaryotic uvs-4 conidia, which arose from heterokaryons containing both uvs-4 and wild-type components, exhibited wild-type survival. Therefore, as with upr-1, there was a carryover of the repair capability to conidia which were genetically uv-sensitive. The uvs-6 mutation, when included in one component of a two-component heterokaryon, resulted in increased uv- sensitivity of both heterokaryotic and homokaryotic uvs-6 conidia. When both components contained uvs-6, the uv-sensitivity of all three conidial fractions was increased and all showed similar inactivation curves. Thus, as with upr-1 and uvs-4, there was a carryover of the wildtype repair capability to geneticaily uvs-6 conidia. Heterokaryon tests for complementation between two non-allelic uv- sensitive mutations showed that in heterokaryotic conidia, complete complementation occurred between upr-1 and uvs-4. (auth)
Date: January 1, 1973
Creator: Shelby, M.D.; de Serres, F.J. & Stine, G.J.
Partner: UNT Libraries Government Documents Department

Rb and p53 gene deletions in lung adenocarcinomas from irradiated and control mice

Description: This study was conducted on mouse lung adenocarcinoma tissues that were formalin-treated and paraffin-embedded 25 years ago to investigate the large gene deletions of mRb and p53 in B6CF{sub 1} male mice. A total of 80 lung tissue samples from irradiated mice and 40 lung samples from nonirradiated controls were randomly selected and examined in the mRb portion of this study. The results showed a significant (P < 0.05) higher percentage of mRb deletions in lung adenocarcinomas from mice exposed to 60 once-weekly {gamma}-ray doses than those from mice receiving 24 once-weekly {gamma}-ray doses at low doses and low dose rates; however, the percentage was not significantly different (P > 0.05) from that for spontaneous lung adenocarcinomas or lung adenocarcinomas from mice exposed to single-dose {gamma} irradiation at a similar total dose. mRb fragments 3 (71%) and 5 (67%), the parts of the gene that encoded the pocket binding region of Rb protein to adenovirus E1A and SV40 T-antigen, were the most frequently deleted fragments. p53 gene deletion analysis was carried out on normal lungs and lung adenocarcinomas that were initially found to bear mRb deletions. Exons 1,4,5,6, and 9 were chosen to be analyzed.
Date: August 1, 1997
Creator: Zhang, Y. & Woloschak, G.E.
Partner: UNT Libraries Government Documents Department

Argonne Radiological Impact Program (ARIP). Part I. Carcinogenic hazard from low-level, low-rate radiation

Description: The entire Argonne Radiological Impact Program is briefly outlined, and part of the program dealing with radiation hazards from nuclear power plants is discussed in detail. Various models and predictions of carcinogenic hazard are examined and compared with actual experience in U. S. and foreign populations. All of the models predict a significant increment in malignant mortality with increasing background. Observation of the actual populations at risk shows not only no increment, but an actual decrement, so that these predictions are left quite without observational support. It is concluded that extrapolation of high- rate and usually hlgh dose-level studies to low rates and low levels is probably invalid, and that radiation at such levels and rates does not constitute an environmental carcinogen of significance. (auth)
Date: September 1, 1973
Creator: Frigerio, N.A.; Eckerman, K.F. & Stowe, R.S.
Partner: UNT Libraries Government Documents Department

Lethal and mutagenic effects in microorganisms grown in $sup 3$H$sub 2$O. Final report

Description: Results are summarized from studies of lethal and mutagenic effects in microorganisms grown in tritiated water. It was concluded that the effects of radiation alone are sufficient to explain the biological effects observed. Studies on the effect of tritium decays accumulated during growth of organisms in the presence of tritiated nucleic acid precursors showed that the mutation rates per decay for continuous growth and for storage conditions were identical and that tritium-labeled adenine and cytosine both caused a local mutagenic effect. A list of publications that give a complete account of the work is included. (CH)
Date: January 1, 1974
Partner: UNT Libraries Government Documents Department

Relation between mutation yield and cell lethality over a wide range of x ray and fission neutron doses in maize

Description: From effects of neutron irradiation upon cell function; Neuherberg, F. R. Germany (22 Oct 1973). Seeds of maize were exposed to x rays at a dose rate of 1658 to 1845 rad/min; other seeds were exposed to fission neutrons at a dose rate of 27.5 to 198 rad/min. The irradiated seeds and controls were sown in moist soil. When mature the fourth and fifth seedling leaves were harvested and scored for frequency of yellow-green sectors. Tables and graphs are presented to show dose-response data for frequency of yellow-green sectors per leaf, frequency of mutations as a function of absorbed dose, neutron-induced yield of mutations and RBE of neutrons in comparison to x radiation. (HLW)
Date: January 1, 1973
Creator: Smith, H.H.; Rossi, H.H. & Kellerer, A.M.
Partner: UNT Libraries Government Documents Department

Future research in mouse radiation genetics

Description: From thirteenth international congress of genetics; Berkeley, Ca1ifornia, USA (20 Aug 1973). The specific-locus method was used to investigate the effect of various biological and physical factors on radioinduced mutation frequency at a sample of seven gene loci of mice. The biological factors include sex, cell stage, and the interval between irradiation and fertilization. The physical factors include radiation dose, dose rate, dose fractionation, and radiation quality. It is suggested that the studies be extended to determine the effects of the various biological and physical factors on mutation frequency at low radiation dose rates in mouse spermatogonia and dictyate oocytes; investigations on the actual nature and effect of the individual mutations induced by radiation; and studies on the nature, extent, and persistence of the actual anatomical and physiologica1 damage expressed in the descendents of irradiated populations. (CH)
Date: January 1, 1972
Creator: Russell, W.L.
Partner: UNT Libraries Government Documents Department

Mice, myths, and men

Description: The author discusses some examples of how different experimental animal systems have helped to answer questions about the effects of radiation, in particular, carcinogenesis, and to indicate how the new experimental model systems promise an even more exciting future. Entwined in these themes will be observations about susceptibility and extrapolation across species. The hope of developing acceptable methods of extrapolation of estimates of the risk of radiogenic cancer increases as molecular biology reveals the trail of remarkable similarities in the genetic control of many functions common to many species. A major concern about even attempting to extrapolate estimates of risks of radiation-induced cancer across species has been that the mechanisms of carcinogenesis were so different among different species that it would negate the validity of extrapolation. The more that has become known about the genes involved in cancer, especially those related to the initial events in carcinogenesis, the more have the reasons for considering methods of extrapolation across species increased.
Date: December 31, 1994
Creator: Fry, R.J.M.
Partner: UNT Libraries Government Documents Department

Lung cancer in uranium miners: A tissue resource and pilot study. Progress report, September 25, 1992--May 31, 1993

Description: This project involves two related activities directed toward understanding respiratory carcinogenesis in radon-exposed former uranium miners. The first activity involves a continuation of the tissue resource of lung cancer cases from former underground uranium miners and comparison cases from non-miners. The second activity is a pilot study for a proposed longitudinal study of respiratory carcinogenesis in former uranium miners. The objectives are to facilitate the investigation of molecular changes in radon exposed lung cancer cases and to develop methods for prospectively studying clinical, cytologic, cytogenetic, and molecular changes in the multi-event process of respiratory carcinogenesis, and to assess the feasibility of recruiting former uranium miners into a longitudinal study that collects multiple biologic specimens.
Date: May 1, 1993
Creator: Samet, J.M.
Partner: UNT Libraries Government Documents Department

Rat mammary carcinogenesis following neutron- or x-radiation

Description: From effects of neutron irradiation upon cell function; Neuherberg, F. R. Germany (20 Oct 1973). Sprague-Dawley female rats, 61 to 63 days of age, were given a single dose of either 0.10, 0.40, 1.6, or 6.4 rads of 0.43-MeV neutrons, or 28, 56, or 85 rads of 250-kVp x rays, or no radiation in a single experiment. The interim results, either in terms of percent of rats with mammary neoplasia or mean number of mammary neoplasms per rat, at the end of 14 months after irradiation, indicate that 0.10 to 0.40 neutron rads was followed by a mammary neoplastic response much like that following 28 xray rads. The mammary neoplastic response to either 6.4 neutron rads or 56 to 85 x-ray rads was similar. Thus the RBE for neutrons for the induction of mammary neoplasia in the SpragueDawley rat is much larger at low neutron doses than at high doses. (auth)
Date: January 1, 1973
Creator: Shellabarger, C.J.; Kellerer, A.M.; Rossi, H.H.; Goodman, L.J.; Brown, R.D.; Mills, R.E. et al.
Partner: UNT Libraries Government Documents Department