Cytogenetic effects of ß-particles in Allium cepa cells used as a biological indicator for radiation damages.

Analysis of cytogenetics effects of ionizing radiation for flora and fauna is essential to determine the impact on these communities and may produce an efficient warning system to avoid harm to human health. Onion (Allium cepa) is a well-established in vivo standard model, and it is widely used in cytogenetics studies for different environmental pollutants. In this work, onion roots were exposed to 0.04-1.44 Gy of ß-particles from a 90Sr/90Y source. We investigated the capacity of brief external exposures to ß-particles on inducing cytogenetic damages in root meristematic cells of onion aiming to verify if onion can be used as a radiation-sensitive cytogenetic bioindicator. A nonlinear increase in the frequencies of chromosomal aberrations and cells with micronuclei was observed. Onion roots exposed to doses 0.13 Gy or higher of ß-particles showed a significant difference (p<0.05) in these frequencies when compared to the unirradiated group. The frequencies of these endpoints showed to be suitable to assess the difference in the dose of beta radiation received from 0.36 Gy. Our research shows the potential of using cytogenetic effects in Allium cepa cells as a biological indicator for a first screening of genotoxic damages induced by brief external exposures to ß-particles.

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

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 1.0 to 10.7 Gy were examined. The chromosome aberration rate was most sensitive to the radiation: it increased immediately after exposure at all doses. In the recovery period (up to 216 h) after irradiation, the chromosome aberration frequency naturally decreased but at the end of experiment in maximum doses remained above the control values. The impact of the initial level of chromosome aberrations on the inhibition of onion roots growth in the long terms after irradiation is discussed.

Biometric traits of onion (Allium cepa L.) exposed to 137Cs and 243Am under hydroponic cultivation.

To elucidate the features of bioaccumulation and phytotoxic effects of long-lived artificial radionuclides, a hydroponic experiment was carried out with the cultivation of onion (Allium cepa L.) in low-mineralized solutions spiked with 137Cs (250 kBq L-1) or 243Am (9 kBq L-1). After the 27-day growth period, ≈70% of 137Cs and ≈14% of 243Am were transferred from the solutions to onion biomass with transfer factor values ≈ 400 and ≈ 80, respectively. Since the bioaccumulation of both radionuclides mainly took place in the roots of onion (77% 137Cs and 93% 243Am of the total amount in biomass), edible organs - bulbs and leaves - were protected to some extent from radioactive contamination. At the same time, the incorporation of the radionuclides into the root tissues caused certain changes in their biometric (geometric and mass) traits, which were more pronounced under the 243Am-treatment of onion. Exposure to 243Am significantly reduced the number, length, and total surface area of onion roots by 1.3-2.6 times. Under the influence of 137Cs, the dry-matter content in roots decreased by 1.3 times with a corresponding increase in the degree of hydration of the root tissues. On the whole, the data obtained revealed the specific features of 137Cs and 243Am behaviour in "hydroponic solution - plant" system and suggested that biometric traits of onion roots could be appropriate indicators of phyto(radio)toxicity.

Effects of tri-frequency ultrasound-ethanol pretreatment combined with infrared convection drying on the quality properties and drying characteristics of scallion stalk.

BACKGROUND: Having short drying time and attractive product quality are important in fruit and vegetable dehydration processing. In this work, tri-frequency (20, 40 and 60 kHz) ultrasound-ethanol pretreatment, ultrasound-water pretreatment and ethanol pretreatment were employed before infrared convection drying (ICD) of scallion stalks, which was aimed at improving the drying process and quality of the end products. The mass transfer, drying characteristics (moisture ratio and drying rate and quality properties of scallion (rehydration, color, flavor, optical microscope image, moisture distribution and microbiological quality) were analyzed. RESULTS: All pretreatments have decreased the drying time by 33.34-83.34% compared to the control, while ultrasound-ethanol pretreatment provided the highest time reduction (83.34%). The reason is that the volatility of ethanol have replaced air in the tissue, which produced a better osmotic dehydration effect and the cavitation effect of ultrasound changed the cell function of the material, so that the food tissue was rapidly compressed and expanded, resulting in damage to the cell structure. Ultrasonic-ethanol pretreatment has greatly reduced the water loss and dry matter of fresh scallion, improved the rehydration effect of dried scallion, better retained the color and flavor of scallion and effectively reduced the microbiological quality of the scallion. CONCLUSION: The tri-frequency ultrasound-ethanol pretreatment has effectively improved the drying process and quality characteristics of the dried scallion. Therefore, this research has a great contribution to the drying technology, as evident in the remarkable reduction in drying time and the improvement in the quality of the end product. © 2020 Society of Chemical Industry.

The long-term effects of γ-radiation on the growth of Allium cepa plants.

PURPOSE: The purpose of this study was to assess the long-term effects of gamma-radiation, including low-dose radiation, on growth parameters of onion (Allium cepa) seedling roots 6-10 days after irradiation. MATERIALS AND METHODS: Onion seedlings were exposed to a 137Cs gamma source at doses ranging from 0.1 to 10 grays (Gy). Responses of root and shoot length growth were studied 6 and 10 days after irradiation. RESULTS: Our results showed inhibition of the root and shoot length growth 6 days after exposure at all doses, including the low dose - 0.1 Gy. At a later point in time (day 10), root and shoot inhibition was only observed after irradiation at high doses (above 5 Gy), and that suggested the occurrence of cell repair after irradiation at low doses. The results indicated that the length of seedling roots was more sensitive to gamma-irradiation than the shoot length. CONCLUSION: The results of the study suggested that short-term gamma-irradiation of onion seedlings (absorbed doses of 0.1-10 Gy) caused inhibition of plant growth 6 and 10 days after irradiation. The dose dependence of the onion root length was linear. The present study showed for the first time that short-term low-dose gamma-irradiation could induce long-term negative effects on plant growth.

Photosynthetic characteristics and chloroplast ultrastructure of welsh onion (Allium fistulosum L.) grown under different LED wavelengths.

BACKGROUND: The optimized illumination of plants using light-emitting diodes (LEDs) is beneficial to their photosynthetic performance, and in recent years, LEDs have been widely used in horticultural facilities. However, there are significant differences in the responses of different crops to different wavelengths of light. Thus, the influence of artificial light on photosynthesis requires further investigation to provide theoretical guidelines for the light environments used in industrial crop production. In this study, we tested the effects of different LEDs (white, W; blue, B; green, G; yellow, Y; and red, R) with the same photon flux density (300 µmol/m2·s) on the growth, development, photosynthesis, chlorophyll fluorescence characteristics, leaf structure, and chloroplast ultrastructure of Welsh onion (Allium fistulosum L.) plants. RESULTS: Plants in the W and B treatments had significantly higher height, leaf area, and fresh weight than those in the other treatments. The photosynthetic pigment content and net photosynthetic rate (Pn) in the W treatment were significantly higher than those in the monochromatic light treatments, the transpiration rate (E) and stomatal conductance (Gs) were the highest in the B treatment, and the intercellular CO2 concentration (Ci) was the highest in the Y treatment. The non-photochemical quenching coefficient (NPQ) was the highest in the Y treatment, but the other chlorophyll fluorescence characteristics differed among treatments in the following order: W > B > R > G > Y. This includes the maximum photochemical efficiency of photosystem II (PSII) under dark adaptation (Fv/Fm), maximum photochemical efficiency of PSII under light adaptation (Fv'/Fm'), photochemical quenching coefficient (qP), actual photochemical efficiency (ΦPSII), and apparent electron transport rate (ETR). Finally, the leaf structure and chloroplast ultrastructure showed the most complete development in the B treatment. CONCLUSIONS: White and blue light significantly improved the photosynthetic efficiency of Welsh onions, whereas yellow light reduced the photosynthetic efficiency.

Comparative cyto- and genotoxicity of 900 MHz and 1800 MHz electromagnetic field radiations in root meristems of Allium cepa.

In the last few decades, tremendous increase in the use of wireless electronic gadgets, particularly the cell phones, has significantly enhanced the levels of electromagnetic field radiations (EMF-r) in the environment. Therefore, it is pertinent to study the effect of these radiations on biological systems including plants. We investigated comparative cytotoxic and DNA damaging effects of 900 and 1800 MHz EMF-r in Allium cepa (onion) root meristematic cells in terms of mitotic index (MI), chromosomal aberrations (CAs) and single cell gel electrophoresis (comet assay). Onion bulbs were subjected to 900 and 1800 MHz (at power densities 261 ±â€¯8.50 mW m-2 and 332 ±â€¯10.36 mW m-2, respectively) of EMF-r for 0.5 h, 1 h, 2 h, and 4 h. Root length declined by 13.2% and 12.3%, whereas root thickness was increased by 46.7% and 48.3% after 4 h exposure to 900 MHz and 1800 MHz, respectively. Cytogenetic studies exhibited clastogenic effect of EMF-r as depicted by increased CAs and MI. MI increased by 36% and 53% after 2 and 4 h exposure to 900 MHz EMF-r, whereas it increased by 41% and 67% in response to 1800 MHz EMF-r. Aberration index was increased by 41%-266% and 14%-257% during 0.5-4 h of exposure to 900 MHz and 1800 MHz, respectively, over the control. EMF-r exposure decreased % head DNA (DNAH) and increased % tail DNA (DNAT) and olive tail moment (OTM) at both 900 and 1800 EMF-r. In 4 h exposure treatments, head DNA (%) declined by 19% and 23% at 900 MHz and 1800 MHz, respectively. DNAT and OTM were increased by 2.3 and 3.7 fold upon exposure to 900 MHz EMF-r over that in the control, whereas 2.8 and 5.8 fold increase was observed in response to 1800 MHz EMF-r exposure for 4 h and the difference was statistically significant. The study concludes that EMF-r in the communication range (900 and 1800 MHz) adversely affect root meristems in plants and induce cytotoxic and DNA damage. EMF-r induced DNA damage was more pronounced at 1800 MHz than that at 900 MHz.

Chromosomal aberrations and micronuclei induced in onion (Allium cepa) by gamma-radiation.

The Allium-test is commonly used to assess genotoxicity of chemical and physical factors. In the present study, the roots of germinating onion (Allium cepa) were exposed to 0.02-13 Gy of γ-radiation. The dose dependencies of the frequency of chromosomal aberrations and micronuclei were nonlinear. An increase in the frequency of chromosomal aberrations in germinating seed root cells was first found under exposure to low doses of γ-radiation (0.05 and 0.1 Gy). Micronuclei inductions at low doses of radiation were not significantly different from the control. Our study suggests that germinating onion seed roots are a sensitive bioassay material for assessing the genotoxic effects of low-dose γ-radiation.

Understanding the effect of Pulsed Electric Fields on multilayered solid plant foods: Bunching onions (Allium fistulosum) as a model system.

While it is well known that the nature of the applied electric field and the heterogeneity of the tissue can influence the impact of PEF treatment on the plant tissues found in plant-based foods, few studies have investigated the influence of PEF on plant structures that are made up of multiple structurally similar organs. The aim of this study was to understand the effect of pulsed electric fields (PEF), at different electric field strengths (0, 0.3, 0.7 and 1.2 kV/cm) and specific energy (7, 21 and 52 kJ/kg), on a multilayered plant material, with bunching onion bulb tissues being used as a model system. The present study found that carbohydrates leakage was an appropriate index to assess PEF induced damage and that plasmolysis of epidermal cells was a good indicator of plasma membrane integrity after PEF. In addition, electric field strength had a greater impact on the cell integrity than specific energy applied. While other studies have shown that different cell types have different sensitivities to PEF, using plasmolysis as an indicator of cell damage, this study clearly showed that the same PEF treatment conditions had a greater effect on the epidermal cells of the outer scales compared to the inner scales. Hence, while different plant cell types vary in their sensitivities to PEF the spatial location of the same cell type within a complex plant material made up of multiple similar organs, i.e. an onion bulb, can also influence how cells respond to the PEF treatment. Despite PEF induced disruption at the cellular level being detected by carbohydrate leakage, the epidermal cell plasmolysis test and by cryo-scanning electromicroscopy (cryo-SEM), no gross structural changes at the organ level were observed using cryo-SEM or fluorescence microscopy. This study also reports for the first time that PEF treatment can enhance fructan leakage from onion bulbs, which means that PEF treatments have the potential to manipulate the fructan contents of some plant-based foods.

Effects of Gamma-Radiation on DNA Damage in Onion (Allium cepa L.) Seedlings.

The effect of γ-radiation on the level of nuclear DNA damage in onion seedlings (Allium-test) was studied using the comet assay. DNA breaks were first found in cells of onion seedlings exposed to low-dose radiation (≤ 0.1 Gy). Dose dependence of DNA damage parameters showed nonlinear behavior: a linear section in the low-dose region (below 0.1 Gy) and a dose-independent plateau in the dose range between 1 and 5 Gy. Thus, the comet assay can be used to estimate the biological effects of low-dose γ-radiation on Allium cepa seedlings.

Cytogenetic Effects of γ-Radiation in Onion (Allium cepa 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.

Light acclimation strategies change from summer green to spring ephemeral as wild-leek plants age.

PREMISE OF THE STUDY: Spring-ephemeral forest-herbs emerge early to take advantage of the high-light conditions preceding canopy closure; they complete their life cycle in a few weeks, then senesce as the tree canopy closes. Summer greens acclimate their leaves to shade and thus manage to maintain a net carbon gain throughout summer. Differences in phenology among life stages within a species have been reported in tree saplings, whose leaf activity may extend beyond the period of shade conditions caused by mature trees. Similar phenological acclimation has seldom been studied in forest herbs. METHODS: We compared wild-leek bulb growth and leaf phenology among plants from seedling to maturity and from under 4 to 60% natural light availability. We also compared leaf chlorophyll content and chl a/b ratio among seedlings and adult plants in a natural population as an indicator of photosynthetic capacity and acclimation to light environment. KEY RESULTS: Overall, younger plants senesced later than mature ones. Increasing light availability delayed senescence in mature plants, while hastening seedling senescence. In natural populations, only seedlings acclimated to the natural reduction in light availability through time. CONCLUSIONS: Wild-leek seedlings exhibit a summer-green phenology, whereas mature plants behave as true spring ephemerals. Growth appears to be more source-limited in seedlings than in mature plants. This modulation of phenological strategy, if confirmed in other species, would require a review of the current classification of species as either spring ephemerals, summer greens, wintergreens, or evergreens.

Oxidative potential of ultraviolet-A irradiated or nonirradiated suspensions of titanium dioxide or silicon dioxide nanoparticles on Allium cepa roots.

The effect of ultraviolet-A irradiated or nonirradiated suspensions of agglomerates of titanium dioxide (TiO(2)) or silicon dioxide (SiO(2)) nanoparticles on roots of the onion (Allium cepa) has been studied. The reactive potential of TiO(2) nanoparticles, which have photocatalytic potential, and the nonphotocatalytic SiO(2) nanoparticles with the same size of agglomerates was compared. The authors measured the activity of antioxidant enzymes glutathione reductase, ascorbate peroxidase, guaiacol peroxidase, and catalase as well as lipid peroxidation to assess the oxidative stress in exposed A. cepa roots. A wide range of concentrations of nanoparticles was tested (0.1-1000 µg/mL). The sizes of agglomerates ranged in both cases from 300 nm to 600 nm, and the exposure time was 24 h. Adsorption of SiO(2) nanoparticles on the root surface was minimal but became significant when roots were exposed to TiO(2) agglomerates. No significant biological effects were observed even at high exposure concentrations of SiO(2) and TiO(2) nanoparticles individually. Plants appear to be protected against nanoparticles by the cell wall, which shields the cell membrane from direct contact with the nanoparticles. The authors discuss the need to supplement conventional phytotoxicity and stress end points with measures of plant physiological state when evaluating the safety of nanoparticles.

Comparison of cytotoxic and genotoxic effects of plutonium-239 alpha particles and mobile phone GSM 900 radiation in the Allium cepa test.

The goal of this study was to compare the cytotoxic and genotoxic effects of plutonium-239 alpha particles and GSM 900 modulated mobile phone (model Sony Ericsson K550i) radiation in the Allium cepa test. Three groups of bulbs were exposed to mobile phone radiation during 0 (sham), 3 and 9h. A positive control group was treated during 20min with plutonium-239 alpha-radiation. Mitotic abnormalities, chromosome aberrations, micronuclei and mitotic index were analyzed. Exposure to alpha-radiation from plutonium-239 and exposure to modulated radiation from mobile phone during 3 and 9h significantly increased the mitotic index. GSM 900 mobile phone radiation as well as alpha-radiation from plutonium-239 induced both clastogenic and aneugenic effects. However, the aneugenic activity of mobile phone radiation was more pronounced. After 9h of exposure to mobile phone radiation, polyploid cells, three-groups metaphases, amitoses and some unspecified abnormalities were detected, which were not registered in the other experimental groups. Importantly, GSM 900 mobile phone radiation increased the mitotic index, the frequency of mitotic and chromosome abnormalities, and the micronucleus frequency in a time-dependent manner. Due to its sensitivity, the A. cepa test can be recommended as a useful cytogenetic assay to assess cytotoxic and genotoxic effects of radiofrequency electromagnetic fields.

[Genetic effects of root extracts of Glycyrrhiza glabra L. on different test-systems].

The antimutagenic and geroprotective activities of root extracts of Glycyrrhiza glabra have been demonstrated both on plant test systems--Allium fistulosum L., Allium cepa L., Vicia faba L. and on animals--Vistar rats. The possibilities of the mobilization of Glycyrrhiza glabra root extracts as antimutagenic agents are discussed.

Effect of irradiation on Salmonella survival and quality of 2 varieties of whole green onions.

Two varieties of green onions, Banner and Baja Verde, were inoculated with a cocktail of 3 Salmonella strains using dip and spot inoculation and irradiated at 0, 0.3, 0.6, 0.9, and 1.2 kGy using electron beam. Salmonella survivors were enumerated using a XLD underlay/TSAYE overlay plating method. The D values were in the range of 0.26 to 0.32 kGy depending on variety but not on the method of inoculation. This indicated that a 5-log reduction of Salmonella can be achieved at a dose of 1.6 kGy. For the quality study, both varieties of green onions were irradiated at 0, 1.5, 2.0, and 2.5 kGy and evaluated for changes in microbial counts, color, texture, and visual quality during storage at 4 °C. Irradiation reduced total plate counts and psychrotrophs by 3 logs. Although the counts increased during storage, they did not exceed the initial counts of control. No significant difference was observed in color and texture between irradiated samples and control. The control maintained good visual quality for about 13 d as compared to 15 d for 1.5 and 2.5 kGy samples. The 2.0 kGy samples maintained good visual quality for 17 d suggesting that irradiation can increase shelf life by reducing spoilage microorganisms but higher doses can be detrimental to quality. At the dose levels required to achieve a 5-log reduction in Salmonella, the shelf life of whole green onion can be extended. This study shows that irradiation can be used to enhance safety without adverse effects on quality.

Induction of micronuclei in germinating onion seed root tip cells irradiated with high energy heavy ions.

Effects of high LET charged particles on a perfect in-vivo system are an essential theme for the study of the biological effects of radiation. Germinating onion seeds are independent complete organisms and the radiation induced micronuclei in the root chip cells can be examined quantitatively and theoretically. We irradiated with three types of high energy accelerated heavy ions germinating onion seeds using a synchrotron and observed micronuclei in the root tip cells. Micronuclei induction showed characteristic dose responses of an upward convex bell shape and a steep rise near zero doses for all types of the ions. The bell curve dose responses, however, could be explained by a simple mathematical model. A parameter in the model which indicates micronuclei induction frequency and another parameter which indicates induction frequency of lethal damages (or damages delaying cell divisions) per heavy ion track were both proportional to square of the LET. Because we suspected by-stander effect concerning the dose responses rising steeply near zero doses and tapering off for higher doses, we tested acute irradiation to remove time of information transmittance between cells using a single spill (about 0.3 s) of the synchrotron beam. No difference was detected between normal multiple spill irradiations and single spill.

Effects of radiofrequency electromagnetic fields on seed germination and root meristematic cells of Allium cepa L.

The effects of exposure to radiofrequency electromagnetic fields (RF-EMFs) on seed germination, primary root growth as well as mitotic activity and mitotic aberrations in root meristematic cells were examined in Allium cepa L. cv. Srebrnjak Majski. Seeds were exposed for 2h to EMFs of 400 and 900MHz at field strengths of 10, 23, 41 and 120Vm(-1). The effect of longer exposure time (4h) and field modulation was investigated at 23Vm(-1) as well. Germination rate and root length did not change significantly after exposure to radiofrequency fields under any of the treatment conditions. At 900MHz, exposures to EMFs of higher field strengths (41 and 120Vm(-1)) or to modulated fields showed a significant increase of the mitotic index compared with corresponding controls, while the percentage of mitotic abnormalities increased after all exposure treatments. On the other hand, at 400MHz the mitotic index increased only after exposure to modulated EMF. At this frequency, compared with the control higher numbers of mitotic abnormalities were found after exposure to modulated EMF as well as after exposure to EMFs of higher strengths (41 and 120Vm(-1)). The types of aberration induced by the EMFs of both frequencies were quite similar, mainly consisting of lagging chromosomes, vagrants, disturbed anaphases and chromosome stickiness. Our results show that non-thermal exposure to the radiofrequency fields investigated here can induce mitotic aberrations in root meristematic cells of A. cepa. The observed effects were markedly dependent on the field frequencies applied as well as on field strength and modulation. Our findings also indicate that mitotic effects of RF-EMF could be due to impairment of the mitotic spindle.

Evaluation of DNA damage in the root cells of Allium cepa seeds growing in soil of high background radiation areas of Ramsar-Iran.

Plants are unique in their ability to serve as in situ monitors for environmental genotoxins. We have used the alkaline comet assay for detecting induced DNA damage in Allium cepa to estimate the impact of high levels of natural radiation in the soils of inhabited zones of Ramsar. The average specific activity of natural radionuclides measured in the soil samples for 226Ra was 12,766 Bq kg(-1) whereas in the control soils was in the range of 34-60 Bq kg(-1). A positive strong significant correlation of the DNA damage in nuclei of the root cells of A. cepa seeds germinated in the soil of high background radiation areas with 226Ra specific activity of the soil samples was observed. The results showed high genotoxicity of radioactively contaminated soils. Also the linear increase in the DNA damage indicates that activation of repair enzymes is not triggered by exposure to radiation in HBRA.

An electron spin resonance study of dry vegetables before and after irradiation.

The ESR signals were successfully observed for the first time in dry vegetables (DVs) that are prominently used in oriental cuisines. We analyzed ESR signals of DV before and after irradiation. Before irradiation, the ESR signal of DV consisted of the three components: a singlet at g=2.0030, the sextet signals from Mn(2+) ion, and a singlet from Fe(3+). The first originated from a carbon centered organic free radical. The second is attributable to the sextet signal with hyperfine interactions of Mn(2+) ion centered at g=2.0020. The third is a singlet at g=4.0030 due to Fe(3+). After the gamma-ray irradiation, a new pair of signals, or twin peaks, appeared in the ESR spectrum of DV. The intensity of the organic free radical at g=2.0030 of the irradiated DV increased lineally with radiation doses. Progressive saturation behavior of the DV indicates a unique saturation and the signals obeyed various relaxation processes.