Responses of Crepis japonica induced by supplemental blue light and UV-A radiation.

Crepis japonica (L.) D.C. (Asteraceae), a weed with antioxidant, antiallergenic, antiviral and antitumor properties displays both medicinal properties and nutritional value. This study aims to assess the effects of a supplementation of blue light and UV-A radiation on the growth, leaf anatomical structure and phenolic profile of the aerial parts of Crepis japonica. Plants were grown under two light treatments: W (control - white light), W + B (white light supplemented with blue light) and W + UV-A (white light supplemented with UV-A radiation). We recorded the length, width, and weight of fresh and dry leaves, the thickness of the epidermis and mesophyll, and stomata density. The phenolic profiles of the aqueous extracts of the aerial parts were analyzed by HPLC-DAD. There was an increase in the leaf size, stomatal density, and phenolic production, and a thickening of the mesophyll and epidermis. UV-A radiation increased the phenolic production more than blue light. Blue light and UV-A radiation both improved the production of caffeic acid by about 6 and 3 times, respectively, in comparison to control. This compound was first reported as a constituent of the extract from the aerial parts together with caftaric acid. UV-A also promoted the production of chlorogenic acid (about 1.5 times in comparison to the control). We observed that the morphological and chemical parameters of C. japonica are modified in response to blue light and UV-A radiation, which can be used as tools in the cultivation of this species in order to improve its medicinal properties and nutritional value.

[Genetic effects in plant populations in the zone of the Chernobyl accident].

During 6 years, starting from 1986, the monitoring of the dynamics of the frequency of embryo lethal and of chlorophyll mutations was carried out in arabidopsis populations in areas with different levels of radioactive contamination by the Muller embryo-test in the 30 km of ChNPP. The dose rate of chronic irradiation in the examined areas varied from 0.014 to 17 nA/Kg. Monitoring of the dynamics of the mutation process in natural arabidopsis populations showed the correlation between the level of the mutation process and the dose rate of chronic irradiation. The genetic effects of different levels of radioactive contamination were estimated by determining the frequency of mutations occurred in this generation and by calculating the dose of irradiation of one was found. That the dependence of the mutation frequency on the dose of irradiation presents a power function with a power index less 1, which suggests a higher efficiency of low radiation doses per unit dose. Possible explanations of this phenomenon are considered in the work. The studies of cytogenetic effects in chronically exposed Crepis tectorum populations in the zones of the Chernobyl accident showed that starting from the second year after the Chernobyl disaster there appeared plants with an altered karyotype and their frequency of chromosome aberrations correlates in root meristem cells.

Evaluation of solar UV damage to Crepis capillaris by chromosome aberration test.

Ultraviolet (UV) radiation comprises only a small portion of the electromagnetic spectrum of solar light, but it exerts a disproportionally greater genotoxic effect on all organisms, including water plants. However, genotoxicity evaluation of solar UV is complicated because of the simultaneous actions of UVB, UVA, and photoreactivating light (PHL). The latter very effectively repairs the main type of DNA lesions, pyrimidine dimers (PD), which are induced specifically only by UV. However, other types of DNA lesions are induced by UV; they are unrepairable by PHL and present a real danger to the plant genome. To evaluate this part of DNA lesions, the frequency of chromosome aberrations (CA) was determined after solar UVB and UVB+UVA irradiation with or without PHL. Meristematic cells of Crepis capillaris were irradiated in special chambers with filters. The 4-year investigation showed that only about half of CA had been repaired with PHL. Both findings of the study, of the part of CA that remained after PHL and of the stronger genotoxicity of UVB+UVA, are discussed.

The action of space flight factors on the radiation effects of additional gamma-irradiation of seeds.

The action of space flight factors (SFF) on radiosensitivity and the effects of preflight irradiation of air-dried Crepis capillaris (L) Wallr and Arabidopsis thaliana (L) Heynh seeds aboard the spaceships of the Cosmos, Soyuz and Salyut series was studied. The results have shown that vibration and linear acceleration (VA) cause damage of the meristematic embryonic cells and simultaneously decrease the radiosensitivity of seeds. SFF enhance the effect of preflight gamma-irradiation of seeds with respect to a number of characteristics. This can be explained partly by the action of VA. The basis of all observed effects is chromosomal aberrations which are expressed in a series of successive cell divisions and which decrease the survival and fertility of plants that grow from flight-exposed seeds.

Cytogenetic analysis of seeds of Crepis capillaris (L) Wallr. exposed on board the earth artificial satellite Cosmos 613.

We studied the effect of space flight factors on air-dry seeds of Crepis capillaris (L) Wallr. and on radiation injury of seeds exposed to gamma-radiation (3 kr, 525 r/min) before and after the flight on the satellite Cosmos 613. Space flight factors induced little increase (which was statistically insignificant) in the rate of chromosome aberrations in cells of the root meristem of Crepis capillaris sprouts, but they enhanced the effect of preliminary irradiation of seeds and decreased their radiosensitivity. The modification of radiation injury was statistically significant.

Modifying effect of dynamic space flight factors on radiation damage of air-dry seeds of Crepis capillaris (L) Wallr.

The influence of dynamic factors (vibration and linear acceleration) on the rate of chromosome aberrations in Crepis capillaris was studied. The vibrational process simulated was similar in its characteristics to that occurring at the launch of spaceships. In combination with linear acceleration it caused a statistically significant increase in the rate of chromosome aberrations compared with the control (R=7.70). The dynamic factors modified the effect of radiation damage induced by acute gamma-irradiation (3 krad). Pre-radiation treatment with vibration and acceleration on the seeds caused a significant decrease (R=10.23) of the effect of radiation damage, from 15.57% to 9.74%. The post-radiation treatment of C. capillaris seeds with the dynamic factors did not change the rate of chromosome aberrations significantly (from 15.57% to 15.90%).

Biological investigations of higher and lower plants aboard Soyuz 19.

Biological investigations carried out aboard Soyuz 19 consisted of three independent complex experiments. All biological materials aboard the spacecraft were kept in "Biocat" thermostats which maintained the required temperature. The objective of the experiment "Genetic investigations" was to determine the effect of space flight factors on the heredity of lower (Chlamydomonas reinhardi Dang) and higher (Crepis capillaris (L) Wallr and Arabidopsis thaliana (L) Heynh) plants, and on the radiosensitivity of plant seeds and the radiation effect of prior gamma-irradiation. The space flight factors decreased the survival of Chlamydomonas cells and A. thaliana plants of the first generation. They decreased the germination of seeds, increased the rate of chlorophyll mutations and embryonal lethals, produced no effect on the rate of visible mutations in unicellular algae, increased the rate of chromosome aberrations in root meristem cells C. capillaris, induced disturbances in mitosis of unicellular algae and modified the effect of prior gamma-irradiation. The experiment "Growth of micro-organisms" was conducted with a culture of Proteus vulgaris in a growth chamber. After return to the laboratory the experimental and control variants were studied for twenty-two tests. The control and experimental material differed in the average cell size, biomass distribution, the character of haemotaxis, the rate of cell migration over the substratum surface, dehydrogenase activity, ribosomal aggregation, and ultrastructural peculiarities of cells. The experiment "Embryological investigations" was carried out to study the effect of space flight factors on embryogenesis of the bony fish Brachyodanio rerio. No abnormalities were noted in the course or rate of the development of spawn cultivated in a special thermostat.

Biological investigations on the orbital station "Salyut-5".

Genetic and embryological investigations were continued on the orbital station Salyut-5. The effect of space flight factors on dry Crepis capillaris (L) Wallr seeds and seedlings, dry Arabidopsis thaliana (L) Heynh seeds, Polyporus brumalis Pers. ex. Fries culture as well as on spawn development and fish behaviour was studied. Space flight factors are shown to have adverse effects with respect to some characteristics in seeds and seedlings, and to change the morphology of the fungus. Fishes appear to adapt themselves to weightlessness.

Effects of space flight factors on the heredity of higher and lower plants.

The effects were studied of a long-term space exposure (72 days) aboard the Salyut orbital station on the following: dry seeds of Crepis capillaris (L.) Wallr. and Arabidopsis thaliana (L.) Heynh, haploid and diploid strains of Saccharomyces cerevisiae mutant for adenine locus (ad) and strain LARG-I of Chlorella vulgaris Beijer. A modifying effect of space factors on radiobiological action of gamma-irradiation from 137Cs was determined with the higher plant seeds and Chlorella culture. For this, the material was partly irradiated prior to, and partly after the flight at doses of 3, 30 and 10 kr for C. capillaris, A. thaliana and Chl. vulgaris, respectively. It was shown that: (1) Space factors caused reduced survival of Arabidopsis seedlings and Chlorella and yeast cultures, reduced productivity of Chlorella cells, increased mutability of Chlorella and yeast cells and increased frequency of chromosome aberrations in cells of Crepis root meristem. There are, however, a few exceptions: cell germination of C. capillaris was enhanced while mutability of A. thaliana seeds declined. (2) Space factors increased the adverse effects of the pre-flight irradiation on all the parameters of the cultures tested. (3) Space factors had no genetic effect on the objects tested. They have, however, caused a stronger inhibition of seed germination and augmenting survival of A. thaliana seedlings and Chlorella cells.