[en] DNA base changes in irradiated rice seeds were studied. Rice seeds were irradiated at 1, 5, 10 and 30 kGy. Extracted DNA samples were hydrolyzed with formic acid, trimethylsilylated and then analyzed by GC-MS. DNA base products were identified as 5-hydroxycytosine, thymine glycol, 8-hydroxyadenine and 8-hydroxyguanine. They were detected in DNA extracted from both irradiated and unirradiated rice seeds, and their amounts showed no significant difference due to irradiation. It was presumed that the amount of radiation-induced base products in rice seed DNA were extremely low at these irradiation doses. (J.P.N.)

[en] Total aerobic bacteria in spices used in this study were determined to be 1x10⁶ to 6x10⁷ per gram. A study on the inactivation of microorganisms in spices showed that doses of 6 to 9 kGy of EB (electron-beams) or gamma irradiation were required to reduce the total aerobic bacteria tobelow 10³ per gram. However, a little increase of resistance was observed on the inactivation of total aerobic bacteria in many spices in case of EB irradiation. These difference of radiation sensitivities between EB and gamma-rays was explained by dose rate effect on oxidation damage to microorganisms from the results of radiation sensitivities of Bacillus pumilus and B. megaterium spores at dry conditions. On the other hand, these high dose rate of EB irradiation suppressed the increase of peroxide values in spices at high dose irradiation up to 80 kGy. Components of essential oils in spices were not changed even irradiated up to 50 kGy with EB and gamma-rays. (author)

[en] Two spotted spider mite, Tetranychus urticae KOCH were irradiated with electron beams (2.5MeV) to develop an alternative quarantine treatment for imported cut flowers. The tolerance of eggs increased with age (1-5-day-old). Immature stages (larva-teleiochrysalis) irradiated at 0.4-0.8kGy increased tolerance with their development. Mated mature females irradiated at 0.4kGy or higher did not produce viable eggs, although temporary recovery was observed at 0.2kGy. Adult males were sterilized at 0.4kGy because non-irradiated virgin females mated with yielded female progeny malformed and sterilized. Various effects of electron beam irradiation were observed when nine species of cut flowers were irradiated in 5MeV Dynamitron accelerator. Chrysanthemum and rose were most sensitive among cut flowers. (author)

[en] Radiation effects on structual and antigenic properties of ovomucoid (OM) were investigated as OM, a protease inhibitor, is a typical allergenic protein of egg. The SDS-PAGE showed that the aggregation of OM was induced by radiation and the molecular mass increased in N₂, whereas the degradation was mainly occurred in O₂. Trypsin inhibiting activity of OM decreased exponentially and the inactivation was larger in N₂ than that in O₂. The antigenicity of OM measured by immunodiffusion method was decreased and the reactivity to anti-OM antibody was diminished at the dose of 0.2-0.25 kGy in N₂ and 0.3-0.35 kGy in O₂, respectively. These results show that the oxygen protects the inactivation and destruction of antigenicity of OM while it enhances the reaction with ovalbumin (OVA). The effect of radiolytically generated radical anions; a pronounced protective action of (CNS)₂^-· and a slight accelerative action of Br₂^-· were the same both on inactivation and decrease in antigenicity. These results suggest that the changes by radiation were mainly due to the conformational change but not to the destruction of essential amino acid residues. (author)

[en] In nature, nitrite reductases located in microorganisms as well as in plants convert nitrite (NO₂^-) into ammonium ion (NH₄⁺). It is rather difficult to isolate nitrite reductase because of very low content in microorganisms and plants. Bovine blood hemoglobin (Hb), horse cardiac muscle myoglobin (Mb) and horse cardiac muscle cytochrome c (Cyt c) in 50μM aqueous solution were treated by gamma-irradiation at doses of 10-30 kGy in the presence of air. The present study shows that NO₂^- is connected into NH₄⁺ by gamma-irradiated hemoprotein in the presence of sodium hydrosulfite as a reducing agent and methyl viologen as an electron carrier. The concentration of NO₂^- and NH₄⁺ after reaction were determined by using diazo-reaction and ninhydrin reaction, respectively, after separation by HPLC. NO₂^- remained and NH₄⁺ formed by 10 kGy irradiated Cyt c, Hb and Mb at pH4 at 60 min were, 0% and 46%, 17% and 31%, 31% and 24%, respectively. Formation of hydroxylamine by reaction of NO₂^- was not recognized in this reaction. The process of conversion of NO₂^- to NH₄⁺ is a net 6 electrons, 8-proton reaction. These results suggest that gamma-irradiated Hb, Mb and Cyt c can be used as a substituent of nitrite reductase. (J.P.N.)

[en] The effects of gamma-irradiation on the DNA of corn, soybean and wheat were investigated using a pulsed-field gel electrophoresis technique. In order to avoid strand breaks during the DNA extracting steps, protoplasts prepared from seeds were embedded in agarose plugs and the DNA was purified by the digesting membranes and proteins. Pulsed-field gel electrophoresis can separate large DNA strands of about a few Mb in length. The DNA from unirradiated corn, soybean and wheat had mainly 3 fragments, about 6Mb(Fr.1), 5Mb(Fr.2), a few hundred kb(Fr.3) and so on. After gamma-irradiation, Fr.1 and Fr.2 had decreased depend on irradiation dose. The Fr.4(about 200 kb) of corn and Fr.3 of soybean DNA increased while Fr.3 of wheat did not increase under 10 kGy irradiation, however, the Fr.3 of all samples and the Fr.4 of corn decreased by over 10 kGy irradiation. It can be assumed that the large DNA strands were broken into smaller strands which increased at low irradiation doses, whereas both large and small DNA strands were broken down at higher irradiation doses. The Fr.6(2.5Mb) and Fr.7(1.5Mb) appeared in irradiated wheat DNA. (author)

[en] The antimicrobial activity of black pepper, rosemary and red pepper has been tested against 12 microorganisms. Alcoholic extracts of these spices were not exhibited strong activity against gram-negative bacteria in laboratory media. The growth of Bacillus subtilis and Clostridium botulinum type A was inhibited by 1% of black pepper, 0.5% rosemary and 0.03% red pepper. A little reduction of antimicrobial activity to B. subtilis was observed on extracts of gamma-irradiated black pepper or rosemary at 10 and 50 kGy. In the case of red pepper, irradiation of 10 or 50 kGy enhanced a little of antimicrobial activity to B. subtilis. Similar effect of irradiation was also observed on the inhibition of aflatoxin production by Aspergillus parasiticus in SL broth. (author)

[en] Mutation frequency of Aspergillus oryzae IAM2630 was studied compared with gamma and ultraviolet irradiation. In this study, mutation frequency of morphological changes on survived colonies was increased up to 50% by irradiation of gamma-rays at survival fraction of 10^-3 to 10^-4 on potato-dextrose agar. On the contrary, mutation frequency of ultraviolet was obtained less than 17% at survival fraction of 10^-3. Mutants with improvement of three-to-five hold production of α-amylase were isolated by irradiation of gamma-rays at 1.2 kGy. However, we could not isolate any mutants of higher production of α-amylase by ultraviolet irradiation. (author)

[en] It is well known that the action to living organisms by ionizing radiation or ultraviolet is induced by DNA damage in the cell. The surviving fraction of cells and shapes of a survival curve are to determine the relative sensitivity of microorganisms. In this study, three strains of E. coli B/r, B and B₁ were used for comparative sensitivities of gamma and ultraviolet irradiation plating on either Trypton agar of Glucose-NH₄ agar plates. From this study, high erresistance on survival fraction was observed on the strain B/r at gamma irradiation compared with strains of B and B₁. In case of ultraviolet irradiation, resistance of B/r was not remarkable compared with other strains. From the result of comparative sensitivities on the plating media, effect of photoreactivation was clearly observed on the strain B after ultraviolet irradiation. Strain B₁ is a mutant on reduced photoreactivation which showed similar pattern of survival fraction on the different plating media as like to gamma irradiation. Strain B/r should be to have strong ability of dark repair systems compared with photoreactivation systems after ultraviolet irradiation. Higher repair of cell damage on strain B/r at gamma irradiation is indicating that the enzymatic repair of damaged DNA by gamma-rays is easily available compared with ultraviolet irradiation. (author)

[en] Four kinds of RNA viruses, Bluetongue virus (BT), Bovine Virus Diarrhea-Mucosal Disease virus (BVD·MD), Bovine Respiratory Syncytial virus (RS), Vesicular Stmatitis virus (VS), were subjected to various doses of gamma irradiation to determine the lethal doses. The D₁₀ values, which are the dose necessary to decimally reduce infectivity, ranged from 1.5 to 3.4 kGy under frozen condition at dry-ice temperature, and they increased to 2.6 to 5.0 kGy under frozen condition at dry-ice temperature. Serum neutralzing antibody titer of Infectious Bovine Rhinotracheitis (IBR) was not adversely changed by the exposure to 36 kGy of gamma-rays under frozen condition. Analysis of electrophoresis patterns of the bovine serum also reveales that the serum proteins were not remarkably affected, even when exposed to 36 kGy of gamma radiation under frozen condition. The results suggested that gamma irradiation under frozen condition is an effective means for inactivating both DNA and RNA viruses without adversely affecting serum proteins and neutralizing antibody titer. (author)