Structural and functional characteristics of various forms of red pigment of yeast Saccharomyces cerevisiae and its synthetic analog

Structural and functional characteristics of the yeast red pigment (product of polymerization of N¹-(β-D-ribofuranosyl)-5-aminoimidazole), isolated from ade1 mutant cells of Saccharomyces cerevisiae and its deribosylated derivatives (obtained by acid hydrolysis) and its synthetic pigment analogue (product of polymerization of N¹-methyl-5-aminoimidazole in vitro) were obtained. Products of in vitro polymerization were identified using mass spectrometry. The ability of these pigments to inhibit amyloid formation using insulin fibrils was compared. All the studied compounds are able to interact with amyloids and inhibit their growth. Electron and atomic force microscopy revealed a common feature inherent in the insulin fibrils formed in the presence of these compounds—they are merged into conglomerates more stable and resistant to the effects of ultrasound than are insulin aggregates grown without pigments. We suggest that all these compounds can cause coalescence of fibrils partially blocking the loose ends and, thereby, inhibit attachment of monomers and formation of new fibrils.     

Cytogenetic Effects of γ-Radiation in Onion (<Emphasis Type="Italic">Allium cepa</Emphasis> L.) Seedlings

The effect of γ-radiation on the cytogenetic parameters of root meristem cells of onion seedlings was studied in laboratory experiments (Allium-test). An increase in the overall frequency of chromosomal aberrations and micronucleus frequencies in seedling cells at low γ-radiation doses (≤0.1 Gy) was detected for the first time. At a maximum absorbed dose of 13 Gy, chromosomal aberrations were detected in the majority of cells in the anaphase and telophase stages of the cell cycle, and the number of cells with multiple aberrations increased. The main contribution to the overall frequency of chromosomal aberrations, in addition to multiple aberrations, is made by the bridge-type aberrations, fragments, and lagging chromosomes. The data obtained allow using the cytogenetic indices of Allium cepa seedlings to assess the biological effects of lowdose γ-radiation.     

New data on the effect of ionizing radiation on the growth of the aquatic plant <Emphasis Type="Italic">Elodea canadensis</Emphasis> in the laboratory

Toxicological experiments with radioactive bottom sediments and extrinsic γ-irradiation have demonstrated that the growth of common elodea roots is suppressed by irradiation at doses several times lower than the established threshold dose. The effect of γ-irradiation on the growth of elodea stems has not been observed at any dose used. The data obtained show that elodea could be recommended for use as an indicator of biological effects of radiation in the range of low radiation doses.     

The effect of γ-radiation on resting eggs and life cycle of cladoceran <Emphasis Type="Italic">Moina macrocopa</Emphasis>

We investigated the effects of γ-irradiation on the survival of resting eggs of the cladoceran Moina macrocopa and on the parameters of the life cycle of neonates hatched from the irradiated eggs. It was shown that γ-irradiation in a wide range of doses (from the background level to 100 Gy) had no effect on survival of eggs and mortality of neonates hatched from the irradiated eggs. However, exceeding the absorbed dose of 40 Gy sharply decreased the reproductive potential of the neonates hatched from irradiated eggs.     

Age-dependent accumulation of <Superscript>137</Superscript>Cs by pike <Emphasis Type="Italic">Esox lucius</Emphasis> in the Yenisei River

Age-dependent accumulation of ¹³⁷Cs in the muscles and bodies of the pike Esox lucius (aged two to seven years) inhabiting a section of the Yenisei River polluted with artificial radionuclides has been studied. The content of ¹³⁷Cs in muscles varied from 0.5 to 7.0 Bq/kg of fresh weight. The maximum content of the radionuclide has been found in juveniles. The content of ¹³⁷Cs in pike muscles and body decreased considerably with age. The high content of ¹³⁷Cs in the muscles of juveniles is probably a consequence of their higher intensity of feeding as compared to older individuals, which is due to the intense growth of juveniles.     

Genotoxicity assessment of low-level doses of gamma radiation with the SOS chromotest and the Ames test

This is the first study to present data on the genotoxicity of low γ-irradiation doses for E. coli and S. typhimurium cells obtained using the SOS chromotest and the Ames test. The most pronounced effect was recorded in the first 24 h of γ-irradiation. After 72 h in the Ames test and after 96 h in the SOS chromotest, a significant effect of γ-irradiation on bacterial cells was detected. The absence of genotoxicity at the later stages can be explained by the adaptation of bacterial cells to the conditions of exposure. The findings allow the bacterial test system to be used for studying the effects of low doses at the early stages of exposure to radiation.     

Genetics of Color in the Ornamental Carp: The Inheritance of Underlying Dark Coloration

In ornamental carps from the collection of the Experimental Station, All-Russia Research Institute of Fresh-Water Fisheries, fish with a dirty dark tint of body color among orange and white fish were found. This coloration was shown to be due to the presence of black pigment cells in the lower skin layer. In the outer skin layers these cells were almost entirely absent. This color type was found to be determined by the presence of at least one of alleles B"₁or B"₂of digenic system B ₁, B ₂, which is responsible for the development of melanophores in fish skin. Each of the genes of this digenic system is represented by three alleles with the following order of dominance: B> B" > b.     

The modifying effect of nitrites, nitrates and increased temperature on 14C metabolism

The paper deals with the experimental findings regarding the effects of non-radiational factors, such as sodium nitrite and nitrate and increased temperature, on the metabolism kinetics of 14C inorganic and organic compounds (14C-sodium bicarbonate, 14C-glucose) in conditions of long-term internal exposure to the nuclide. The authors determined the time which elapses before the steady state is achieved as well as the maximum concentration, the accumulation factor and the dose strength. At a concentration of 3 g/l, nitrites and nitrates were shown to produce no significant modifying effect on the kinetics of 14C metabolism. In hyperthermic conditions, 14C metabolism proved to be more intensive. The findings reported herein may have practical applications in setting up hygienic norms and evaluating the hazards of 14C accumulation in the environment.     

Characteristics of genetic material with reference to patent documents

Characteristics of genetic material: plasmids, vectors, recombinant DNA and DNA fragments were, studied from 235 patent documents. These documents were from the patent offices of the Federal, Republic of Germany (38), the German Democratic Republic (15), the European Patent Office (53), Finland (43), Great Britain (65), the Soviet Union (3), and the United States of America (18). Attention was paid also to the terminology used in the patent documents. According to this study the way in which the genetic material was characterized in patent documents of different countries was quite variable, and the terminology used was sometimes confusing.     

Effect of Gamma Radiation on Cytogenetic and Growth Endpoints of Allium cepa Seedlings in Long-Term Experiments

Doklady Biochemistry and Biophysics - The effect of γ-radiation on the growth and cytogenetic endpoints of Allium cepa L. seedlings in a long period after irradiation in absorbed doses from...