Gamma Irradiation on Fermentation Mashes Consisting Mainly of Cane Molasses

The application of the radiopasteurization method to fermentation media consisting mainly of molasses was investigated. γ-Irradiation was found to have an excellent pasteurization effect on the fermentation media and at the same time to bring about an increase in the fermentation rate and yield of ethanol. Percent survivals in molasses decreased to ca. 70% by heating at 80°C for 30 min, to ca. 10% by irradiation with 3.0 × 10⁵ rad and to ca. 1% by 6.0 × 10⁵ rad. Irradiated mash was suitable for the medium of the “starter”, since the rate and the degree of the growth of Saccharomyces cerevisiae in irradiated mash did not differ from those of the growth in heat-pasteurized mash.

In the case of the molasses mash supplemented with nitrogen sources, the fermentation rate and yield of ethanol in irradiated mash were larger than those in heated mash. Besides, in the absence of nitrogen sources a 14% difference in fermentation yield was seen between the mash irradiated with 3.0 × 10⁵ rad and the mash heated at 80°C. With the doses ranging from 1.0 × 10⁵ to 9.5 × 10⁵ rad, concentrations of total sugar and direct reducing sugar, pH, and optical density of molasses were little affected by irradiation.     

The effect of radiation therapy combined with natural killer cells against spontaneous murine fibrosarcoma

The effect of radiation therapy combined with lymphoid cells against spontaneous murine fibrosarcoma (FSa-II) was investigated bothin vivo andin vitro. In thein vivo experiment, syngeneic C3H mice were divided into 3 groups. Animals in the first group were injected with 1 x 10⁵ tumor cells into the right hind leg. Animals in the second and third groups were injected with 1 x 10⁵ tumor cells mixed with 1 x 10⁷ normal lymphoid cells (NLC) or effector lymphoid cells (ELC), respectively. ELC were obtained from spleen and lymph nodes of FSa-II-bearing mice and incubatedin vitro for 40 hr to eliminate suppressor T cell function. NLC were obtained from normal mice and incubated in the same way. Irradiation was given using¹³⁷Cs unit 3 days after cell inoculation. 12 out of 14 mice (85.7%) inoculated with tumor cells mixed with NLC did not show any tumor growth at 60 Gy local irradiation. 12 out of 21 mice (57.1 %) inoculated with tumor cells alone and 6 out of 10 (60%) with tumor cells mixed with ELC rejected tumors at the same radiation dose. This synergistic effect with NLC was not observed when NLC was inoculated after irradiation, indicating that lymphoid cells should be in contact with tumor cells before irradiation. In the⁵¹Cr release assay, lymphoid cells obtained from whole body irradiated (WBI) mice showed 17.8% lysis without irradiation and 28.8% lysis at 5 Gy irradiation. Untreated NLC showed almost no cytotoxic effect at the same radiation dose. This synergistic effect disappeared when WBI lymphoid cells were treated with anti asialo GM1 and complement. These results suggested that NK cells might be important in this synergistic effect with irradiation. To obtain a sufficient level of synergistic effect by in vitro combined treatment of mixed tumor cell - NLC culture and irradiation - incubation for more than 12 hrs and 8 hrs appeared to be necessary before and after irradiation, respectively.     

Phosphoinositide-specific phospholipase C forms a complex with 14-3-3 proteins and is involved in expression of UV resistance in fission yeast

The fission yeast plc1 ⁺ gene encodes phosphoinositide-specific phospholipase C. The two- hybrid interaction assay with plexA-plc1 ⁺ as a bait revealed that Plc1p interacted with the 14-3-3 proteins Rad24p and Rad25p. Formation of a complex containing Plc1p and Rad24p in vivo was confirmed by an immunological method. As predicted from the fact that rad24 null mutant cells are hypersensitive to UV irradiation, plc1 null mutant cells were almost as sensitive to UV irradiation as rad24 null mutant cells. In addition, deletion of rad24 in the plc1 null mutant cells did not enhance the UV sensitivity, indicating that plc1 ⁺ and rad24 ⁺ belong to the same epistasis group with respect to UV sensitivity. Whereas Rad24p has been reported to be involved in the DNA damage checkpoint pathway, the delay to mitosis after UV irradiation was not defective either in rad24 null mutant cells or in plc1 null mutant cells in our analysis. Thus, Plc1p is responsible for resistance to UV irradiation, but not for the DNA damage checkpoint pathway, in cooperation with 14-3-3 proteins. Received: 10 July 1997 / Accepted: 15 December 1997     

Effects of Pb2+, Ni2+, Hg2+ and Se4+ on cultured cells. Analysis of uptake, toxicity and influence on radiosensitivity

Effects of Pb²⁺, Ni²⁺, Hg²⁺ and Se⁴⁺ on cultured human glioma U-343MG cells were investigated considering uptake, toxicity and, in combination with radiation, clonogenic cell survival. The cells were exposed to 0-100 m of the metals for a week before the evaluation. The tests showed a tendency to toxicity with 10 m nickel although not significant (P > 0.05). Selenium, lead and mercury exerted a significant toxicity (P < 0.05) at 2.5 m, 10 m and 1 m, respectively. To challenge the clonogenic cell survival capacity, the cells were irradiated with⁶⁰Co photons after being exposed to the highest nontoxic concentration of the different metals. The clonogenic cell survival tests, after irradiation, showed no significant change if the cells were exposed to 5 m nickel, 0.5 m selenium or 5 m lead compared with those not exposed. Mercury, 0.1 m, gave a relative reduction in survival compared with only irradiated cells of 58 ± 17%. Thus, only mercury affected the radiation-induced damage and/or repair. When exposed to the highest nontoxic concentrations of the different metals, the cultures did not display a significant uptake ratio (metal concentration ratio of exposed cells to control cells) of nickel (3.1 ± 3.3), only a small uptake ratio of selenium (4.0 ± 0.4), while there was a large uptake ratio of both lead (2.6 ± 1.7) x 10² and mercury (1.5 ± 0.2) x 10¹. The results indicated that nickel was neither especially toxic nor influenced the clonogenic cell survival after irradiation. Mercury was more toxic and also influenced the radiation sensitivity. Lead was taken up strongly but did not influence the radiation sensitivity. Selenium accumulated but gave no detectable effect on the radiation sensitivity.     

Radiation-induced chromosomal aberrations in human lymphocytes. I. Dependence on the dose of gamma-rays and an anomaly at low doses

Cultures of human lymphocytes obtained from blood of healthy adult donors were irradiated with different doses of ⁶⁰Co γ-rays and the irradiated cells were analysed in metaphase 50 h after irradiation. The effect (total yield of abberations of chromosome type, or total yield of exchange type abberations) produced by the lowest dose (5 rad) appears to be statistically significant in a sample of 1500 cells. In the usual dose range (25–400 rad), both parabolic and linear-quadratic equations give a satisfactory fit of experimental data (dicentrics, fragments, or all aberrations of chromosome type). Low doses of γ-rays, however, produced more aberrations than expected, if one extrapolates dose-effect curves from higher doses. Both relations should be considered, therefore, merely as empirical equations. Dicentrics show at low doses (10–30 rad) a plateau which appears to be statistically significant. Some indications are obtained that the total number of chromosome-type aberrations is a more reliable criterion of cytogenetic damage than the usually accepted yeild of dicientrics and rings.     

Effects of heavy ions on rabbit tissues: Induction of DNA strand breaks in retinal photoreceptor cells by high doses of radiation

Excised retinas from New Zealand white (NZW) rabbits were irradiated at 0° C with 9–260 Gy (depending on the type of radiation) of 300 kVp X-rays, or the first 5 cm (range: 14 cm in water) of 365 MeV/u Ne ions or 530 MeV/u Ar ions (LET's : 1, 35 ± 3 and 90 ± 5 keV/µm, respectively). Other positions (LET's) in the Ne-ion beam (Bragg curve) were employed in more limited experiments. The retinas were frozen and stored in liquid nitrogen until analysis.Total strand breakage in the DNA of retinal photoreceptor (sensory) cells was determined from sedimentation profiles obtained by velocity sedimentation through reoriented alkaline sucrose gradients under conditions free from anomalies related to rotor speed. For the radiation doses employed: the reciprocal of the number average molecular weight,M _n , was related linearly to dose for each radiation quality and extrapolation to zero dose in each case gave positive intercepts for which the mean unitradiated molecular weight,M ₀, was 6.1 ± 1.0 × 10⁸ daltons; the efficiencies of total strand breakage for the different radiations were 50 ± 3, 110 ± 2 and 240±6 eV/strand break, respectively. For the heavy ions, accurate analogous calculations for other positions in the Bragg curves were precluded by beam degeneration due to fragmentation of the primary particles, etc.Overall, the experimental results support the concept that ionizing radiations damage cellular DNA by two general processes. One process causes localized damage, which under our experimental conditions is revealed as strand breaks and/or alkali-labile bonds in regions between molecules of sizecirca 10⁹ daltons (subunits); the other causes essentially random damage. Base damage caused by either process would not have been delineated in our experiments.     

Clonal analysis of the T lymphocytes involved in parent versus Fn1 graft-versus-host reaction

A systemic graft-versus-host reaction (GVHR) leading to 50% mortality by day 20 was elicited by the injection of CBA (10⁵) or B10 (10⁶) parental T lymphocytes into irradiated (750 rad) and bone marrow protected (CBA x B10)F₁ recipients. Between days 12 and 28 the spleens of the sick mice were analyzed by limiting dilution, performed with irradiated F₁ cells and a source of interleukin-2 (IL-2), to determine the frequency of cells with an antihost proliferative or cytolytic activity and to derive T lymphocyte clones. The frequency of cells with antihost proliferative or cytolytic activity was approximately 10^–3 in either combination. In the CBA vs F₁ GVHR, all eight clones isolated with anti-F₁ activity were Lyt-2^–, noncytolytic, mixed lymphocyte reaction (MLR) responders and IL-2 producers, three of which mapped to the A ^b locus, while in the B10 anti-F1 combination, eight of the nine anti-F₁ clones isolated were Lyt-2⁺, poor MLR responders and non-IL-2 producers, but cytolytic and mapping to K _k . These findings suggest a much higher frequency of T cells recognizing the A-locus antigens in the CBA than in the B10 strain.     

Opioid receptor binding in rat spinal cord

The interaction of various radioligands with spinal opioid receptors has been characterized under variable experimental conditions. Binding to , , and sites was measured in all (cervical, thoracic, lumbar) segments. The apparent affinity constant (K) of [³H]Ethylketocyclazocine (EKC) was similar in Tris, 2.09 (±1.06)×10⁸ M^–1, and phosphate buffer, 2.16 (±0.02)×10⁸ M^–1, when its interaction with and sites was blocked. Without blocking ligands, EKC binding was resolved in two components:K ₁=1.01 (±0.21)×10⁹ M^–1 andK ₂=0.95 (±0.61)×10⁷ M^–1. Likewise, the binding of [D-Ala², MePhe⁴, Gly(ol)⁵]enkephalin (DAGO) or [D-Ala², D-Leu⁵]-enkephalin (DADLE) alone was represented by a 2-site model. By adjusting the radioligand and receptor concentration or by the addition of blocking ligands, binding was represented by a 1-site model for DAGO,K=4.35 (±1.41)×10⁸ M^–1, and DADLE,K=2.44 (±0.08)×10⁸ M^–1.The abbreviations used are DADLE [D-Ala², D-Leu⁵]enkephalin - DAGO [D-Ala², MePhe⁴, Gly(ol)⁵]enkephalin - EKC ethylketocyclazocine - DYN dynorphin (1–17)     

Gamma-irradiation depletes endogenous germ cells and increases donor cell distribution in chimeric chickens

The production of chimeric birds is an important tool for the investigation of vertebrate development, the conservation of endangered birds, and the development of various biotechnological applications. This study examined whether gamma (γ)-irradiation depletes endogenous primordial germ cells and enhances the efficiency of somatic chimerism in chickens. An optimal irradiation protocol for stage X embryos was determined after irradiation at various doses (0, 100, 300, 500, 600, 700, and 2,000 rad). Exposure to 500 rad of γ-irradiation for 73 s significantly decreased the number of primordial germ cells (P < 0.0001). Somatic chimera hatchlings were then produced by transferring blastodermal cells from a Korean Oge into either an irradiated (at 500 rad) or intact stage X White Leghorn embryo. An analysis of feather color pattern and polymerase chain reaction-based species-specific amplification of various tissues of the hatchlings confirmed chimerism in most organs of the chick produced from the irradiated recipient; a lesser degree of chimerism was observed in the non-irradiated control recipient. In conclusion, the exposure of chick embryos to an optimized dose of γ-irradiation effectively depleted germ cells and yielded greater somatic chimerism than non-irradiated control embryos. This technique can be applied to interspecies reproduction or the production of transgenic birds.     

H2 production from maltose derived from starch using the visible light, photosensitization of Mg chlorophyll-a from Spirulina

A photoinduced H₂ production system, coupling d-maltose degradation by glucoamylase and glucose dehydrogenase (GDH) and H₂ production with colloidal platinum as a catalyst using the visible light-induced photosensitization of Mg chlorophyll-a (Mg Chl-a), has been developed. H₂ production was continuous when the reaction mixture containing d-maltose, glucoamylase, GDH, NAD⁺, Mg Chl-a, Methyl Viologen (MV²⁺, an electron relay reagent) and colloidal platinum was irradiated by visible light. The amount of H₂ production was estimated to be 5 ± 0.5 mol after 4 h irradiation. The yield of the conversion of d-maltose to H₂ in this system was ca. 1.8 %.     

Induction of c-mutations in extracellular phage lambda by gamma-rays

Summary Mutagenic action of ⁶⁰Co -rays on extracellular phages red ⁺ and red1 13 after irradiation in 4% nutrient broth in the absence or in the presence of 0.1 M cysteamine or in dried samples was studied. The yield of c mutations was almost independent of the repair genotype of the host cells (uvrA6, polA1, recA13, lexA102, uvrE502, uvrD3 or xthA9), of the phage Red function and of the conditions of -irradiation and was 1·10^-12 per base pair and 1 rad. When the SOS-repair system of the host cells was induced by moderate UV irradiation, the yield of c-mutations was drastically enhanced in phage irradiated in broth, but not in phage irradiated in the dried state. These data allow us to suppose that the direct action of -rays induces, in phage DNA, premutational lesions that are fixed into mutations by replication. On the other hand after -irradiation in broth, when indirect radiation effects are only partially suppressed, about 85% of premutational lesions are converted into mutations by means of the inducible, errorprone SOS-repair system.     

Promotion of somatic embryo production from embryogenic calluses of monocotyledonous and dicotyledonous plants by heavy-ion beam irradiation

Effect of heavy-ion beam irradiation on the growth and development of embryogenic calluses was examined in the liliaceous monocotyledon Tricyrtis hirta and the umbelliferous dicotyledon Daucus carota. Embryogenic calluses of T. hirta were irradiated with 5, 10, 20 or 50 Gy of ¹²C⁶⁺, ¹⁴N⁷⁺ or ²⁰Ne¹⁰⁺ ions, and those of D. carota were irradiated with 5, 10, 20 or 50 Gy of ¹⁴N⁷⁺ ions. In both species, irradiation at 10–50 Gy inhibited growth of embryogenic calluses, and callus growth rate decreased as irradiation dose increased. Interestingly irradiation at low doses greatly promoted somatic embryo production from embryogenic calluses in both species. In T. hirta, calluses irradiated with 5 and 10 Gy ¹²C⁶⁺ ions, 10 Gy ¹⁴N⁷⁺ ions, and 5 Gy ²⁰Ne¹⁰⁺ ions produced more than twice as many embryos as the control, non-irradiated calluses. In D. carota, embryogenic calluses irradiated with 5 Gy ¹⁴N⁷⁺ ions produced more than one and a half times as many embryos as the control. Somatic embryo production in both species was inhibited by irradiation at 20 and 50 Gy.     

Dose-response relations for dicentric yields in G0 lymphocytes on man and crab-eating monkey following acute and chronic γ-irradiations

A comparison has been made of dicentric yields in G₀ lymphocytes between man and crab-eating monkey, Macaca fascicularis, after acute and chronic γ-irradiations. With acute irradiation (49.6 rad/min) there was no significant difference between them, but for the chronic irradiation (17.1 rad/h) a significant difference was observed between the species. When the dose-response relations were fitted to the linear-quadratic model (Y = αD + βD²), the species-difference observed for chronic irradiation was almost entirely due to change in the value of β. In addition, after chronic irradiation the β-value for monkey was almost negligible, but that for man was significant. Post-irradiation incubation experiment showed that cells with dicentrics were partly eliminated during the course of chronic irradiation, because there were appreciable reductions of dicentric yields (ca. 25% for both man and monkey at 400 rad) together with mitotic indices (ca. 30% and 60% for man and monkey, respectively, at 400 rad). Accordingly, it would be reasonable to postulate that G₀ repair for dicentrics other than selection mechanism must play a major role in the effects of low dose rate. It can be further suggested that G₀-repair capacity for chromosal damages leading to dicentrics may be different among different primate species.     

Effects of Gamma-Radiation in Oogenesis of Drosophila Mutants Defective for Repair and Meiotic Recombination

Effects of mutations rad201, mei-9, and mei-41on cell sensitivity to gamma-radiation in Drosophilaoogenesis were studied. Females of the control (Oregon R) and mutant strains were irradiated at a dose of 15 Gy. For 9 days after the irradiation, the number of eggs in consecutive day batches, the frequency of dominant lethals (DLs) among the eggs, and the cytologically recorded distribution of oocytes for stages of their development, and the frequency of egg chamber degeneration in female ovaries were estimated. As a result of joint analysis of the data, different oogenesis stages were characterized with regard to the frequency of two radiation-induced events: appearance of DLs in oocytes and degeneration of egg chambers due to apoptosis of nurse cells. It was shown that the mutations affect these parameters only at particular stages of early oogenesis, at which previtellogenetic growth of egg follicles and meiotic recombination in oocytes occur. Mutation rad201 ^G1increased the frequency of DLs and egg chamber degeneration, mei-41 ^D5affected only the DL frequency, and mei-9 ^a, in addition to enhancing the chamber degeneration frequency, promoted radiation rescue of some oocytes from the DL induction.     

Radiosensitivity and recovery of mouse L cells during the cell cycle

Summary Mouse fibroblasts, subline L-929 F were synchronized by mitotic detachment. The synchronized cell cultures were irradiated with 200 kVp X-rays at different time after mitosis, and age reponse functions and dose effect curves were determined using the colony test. The cell age in the mitotic cycle was obtained from a computer analysis of flow cytometric DNA histograms. Both intrinsic radiosensitivity 1/D ₀ and extrapolation numbern were found to vary during the cell cycle. TheD ₀ has a maximum value of 176 ± 1 rad in the middle ofG ₁ phase and a minimum of 71 ± 1 rad at theS/G ₂ transition, while the extrapolation number is rather constant from the beginning ofG ₁ phase (1.9 ± 0.1) to the middle ofS phase (2.3 ± 0.1) and reaches a steep maximum of 9.3 ± 1.1 atS/G ₂ transition. The values ofn in the various phases of cell cycle are compared with the respective values of the recovery factor determined after fractionated irradiation. - Cell survival after a single dose of 616 rad has minima for irradiation atG ₁/S transition and in earlyG ₂ phase; the survival in earlyG ₂ being about 40 times smaller than in earlyG ₁ phase. Implications for a cell cycle specific therapy are discussed.Supported by the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg     

Inducible reactivation of UV-irradiated cholera phage e5 in Vibrio cholerae MAK757

Summary The survival of UV-irradiated cholera phage e5 was found to increase when the host cells, Vibrio cholerae MAK757, were exposed to a low dose of UV irradiation before phage infection (Weigle reactivation), indicating the existence of a UV-inducible DNA repair pathway (SOS repair) in V. cholerae MAK757. The induction signal generated by UV irradiation was transient in nature and lasted about 20–30 min at 37°C. Maximal weigle reactivation of the phage was obtained when the host cells were irradiated with a UV dose of 16 J/m². V. cholerae MAK757 was also found to possess efficient photoreactivation and host cell reactivation of UV-damaged DNA in phage e5.     

Seasonal variation of particulate organic carbon, dissolved organic carbon and the contribution of microbial communities to the live particulate organic carbon in a shallow near-bottom ecosystem at the Northwestern Mediterranean Sea

Microbial planktonic communities (i.e. bacteria and protozoa), phytoplankton, dissolved organic carbon (DOC) and particulate organic carbon (POC) were seasonally examined at Medes Islands (Northwestern Mediterranean) to assess their variation in abundance and composition throughout the year in a near-bottom littoral ecosystem. From October 1995 to November 1996, samples were collected between two and six times per month at 0.5 m above the bottom. Mean DOC and POC values throughout the year were 2560 180 (SE) and 387 ± 35 g C l^-1, respectively. All year, detrital organic carbon (detrital=total POC - live carbon) represented the main POC fraction, and mean live carbon was 24 ± 9 g C l^-1. Winter and spring had maximum values of POC, and spring and summer had maximum values of DOC. Heterotrophic bacteria, with a mean abundance of 5.16 ± 0.08 x 10⁵ cells ml^-1, were the main contributor to live carbon (26 ± 7%). During winter, heterotrophic bacterial biomass decreased 40% due to a decrease in mean biovolume per cell. Synechococcus sp. and Prochlorococcus sp. abundance were 2.24 ± 0.09 x 10⁴ and 1.05 ± 0.07 x 10⁴ cells ml^-1, respectively. However, while Synechococcus sp. were present all year, Prochlorococcus sp. were not observed from April to July. Mean phytoplankton (i.e. diatoms and dinoflagellates) abundance was 2.06 ± 0.40 x 10⁴ cells l^-1 with biomass at a maximum during the winter months, the period with the lowest temperature and the highest nutrient concentration. The size composition of live carbon showed two clearly distinct periods: from December to March, live carbon was dominated in biomass by microplankton, while from April to November, pico- and nanoplankton cells were dominant. Overall, the dynamics of the near-bottom planktonic communities was characterized by a low biomass of heterotrophic and autotrophic bacteria, phytoplankton and ciliates in contrast to previous water column studies. This pattern and the high temporal heterogeneity of the different planktonic communities are discussed in relation to the physical and chemical characteristics of the environment, as well as to the potential role that benthic communities may be exerting in the control of the near-bottom planktonic communities.      

Cellular kinetics of the peripheral nerve and striated muscle after a single dose of X-rays

Summary Thirtysix mice were irradiated with a single dose of X-rays (2760 rad) on one leg, while the rest of the body was shielded by lead. The animals were killed 1–270 days after the irradiation and ³H-thymidine was injected 2 hours before death. Sections from the sciatic nerve and its innervated muscles were examined by autoradiography and by special methods for the mast cells. No changes in the endoneurial mast-cell component could be disclosed after irradiation. At all times after the irradiation, the numbers of labelled Schwanncell nuclei and the sarcolemna-cell nuclei were moderately decreased on the irradiated side, when compared with the control side.Supported by a grant from the Swedish Medical Research Council.     

The Interaction of the rad201Gene with Genes mei-9and mei-41in Germline Cells of DrosophilaFemales

The effect of Drosophilamutation rad201 ^G1together with mutations mei-41 ^D5and mei-9 ^aon the sensitivity of oocytes to induction of dominant lethals (DLs) was studied. To this end, the frequencies of spontaneous and gamma-radiation-induced DLs in consecutive egg batches of females carrying double or single mutations were estimated. Since the effects of the mutations examined are expressed only at the previtellogenetic stages of oogenesis, only newly hatched (0–5-hour-old) females, whose oocytes did not develop farther than stage 7, were irradiated. The results obtained indicated that in intact and irradiated oocytes of double mutants mei-9 ^a rad201 ^G1and mei-41 ^D5 rad201 ^G1, mutation rad201 ^G1epistatically suppresses the mutations of the both meigenes.