长波紫外线辐射对脊椎动物的影响

臭氧层空洞的加剧使紫外辐射不断加强,造成的环境污染已经成为广为关注的问题,但大多数都集中在中波紫外线(UVB)的生物学作用及其与两栖动物衰减关系的研究,有关长波紫外线(UVA)对生物体损伤作用的研究却甚少。本文综述了近年来UVA对脊椎动物损伤的研究概况,从细胞结构、酶活性、遗传物质、膜结构以及免疫系统等方面阐述了UVA的损伤机理,并对低剂量辐射诱导兴奋效应对紫外损伤的保护作用进行了简要概述。最后分析和总结了关于UVA损伤研究所存在的问题及两栖动物作为实验用动物模型在研究紫外线损伤中的作用。     

Assessing effects of radiation on abundance of mammals and predator–prey interactions in Chernobyl using tracks in the snow

To test whether radioactive contamination reduced the abundance of mammals, and whether species differed in susceptibility to radiation, we censused mammals by counting tracks in the snow along 161 100-m line transects around Chernobyl during February 2009. The abundance of mammal tracks was negatively related to level of background radiation, independent of the statistical model, with effects of radiation accounting for a third of the variance. The effect of radiation differed significantly among species. There was a positive relationship between abundance of predators and abundance of prey, modified by the level of background radiation because the number of predators increased disproportionately with the number of prey at high levels of radiation. These findings suggest that predatory mammals aggregate in areas with abundant prey, especially when prey are exposed to high levels of radiation. This study emphasizes the negative effects of level of background radiation on the abundance of mammals and predator–prey interactions.     

UV-B辐射增强对陆地植物次生代谢的影响

平流层臭氧的减薄已导致地表中波紫外辐射(UV-B,280～320nm)增强,由于UV-B能被许多生物大分子如蛋白质和核酸吸收并引起分子构象的变化,因此可对植物的各方面产生影响。本文将近年来特别是近5年的UV-B辐射增强对植物次生代谢物影响的研究工作进行了综述。主要包括：UV-B辐射增强对植物紫外吸收物的影响和可能的机制;环境因子的复合作用对植物紫外吸收物的影响和可能的机制;UV-B辐射增强对次生代谢物影响的生态学意义。并对该领域未来的研究作了展望。     

增强紫外B辐射对植物及生态系统影响研究的发展趋势

介绍了一些有关紫外B辐射增强对植物及生态系统影响研究的新进展：1．许多研究已深入到分子水平;2．注意到对植物生长调控的研究;3．更加重视对植物防御、修复的研究;4．有关信号传导的研究日渐增多;5．对植物群体及生态系统影响的研究在不断扩大与加深;6．复合效应研究正在升温。推断今后在一段时间内,有关UV－B辐射对植物和生态系统影响的研究不但不会削弱,可能还会加强,特别分子水平的研究会大大增加,今后对群体和生态系统的研究会重视野外和长期效应的观测。我国在这一领域的研究起步晚,但近些年发展得较快,有部分研究已赶上国际研究进展的步伐。     

Effect of 7Li radiation on endogenous hormonal level on developing cotton fiber

Influence of radiation doses (7Li) on cellular metabolism, specially endogenous hormonal level, was studied in monolayer of cotton fibers. Changes in endogenous phytohormone level were determined with two different fluences of 7Li equivalent to radiation doses of 1 Gy and 4 Gy. To estimate the endogenous indole-3-acetic acid (IAA), phenoxy acetic acid (PAA), and abscisic acid (ABA) levels, indirect ELISA was performed with the help of antibodies raised against each hormone. In samples at later stage, dose dependent response was apparent in PAA. Results showed that in vivo content of each hormone increased with radiation treatment except ABA.     

Effects of UV radiation on the structure of Arctic macrobenthic communities

At present, information on the effects of ultraviolet radiation (UVR) on structure and diversity of polar, in particular Arctic, benthic communities is scarce. It is unclear whether and to what extent communities of different successional age are susceptible to UVR and whether UVR effects known to be detrimental at the species level can be buffered at the community level. In a subtidal field study on Spitsbergen (Norwegian Arctic), we investigated the potential effect of distinct UVR regimes on macrobenthic communities of different successional ages, grown on ceramic tiles. Total taxon cover, taxon composition, evenness, and richness were assessed after experimental exposure of 4 and 8 weeks. Overall, 17 algal and invertebrate taxa were encountered in the study and diatoms dominated the communities regardless of successional age or radiation treatment. UVR effects were dependent on both exposure time and community age. We did not find overall detrimental UVB effects. In contrast, abundance of several species increased in UVR-exposed communities. Especially, UVA seemed to have a beneficial effect in that several green and brown algal taxa increased in abundance (e.g. Ulothrix flacca, Chlorophyta, and Desmarestia sp., Phaeophyceae). In general, UVR effects depended on species composition and thus on successional age of communities, with later successional communities likely to be able to buffer and alleviate possible negative effects of UVR at species level. Overall, the presented study provides a first insight into the complex role UVR plays in structuring Arctic epibenthic communities.     

Modulated increased UV-B radiation affects crop growth and grain yield and quality of maize in the field

Current research on the effect of increased UV-B radiation on crop production has been limited to exposing plants to improbable UV-B dose or growth condition. The objective of this study was to test the effects of short-term modulated increased UV-B radiation on maize (Zea mays L.) growth, grain yield, and quality under field conditions for three years. A modulated irradiance system was used to maintain UV-B radiation at 30% above the ambient level and was applied daily between the elongation and silking stages of maize. The result indicated that increased UV-B radiation adversely affected maize growth and yield, especially on plant height when UV-B was enhanced at the elongation stage and on yield when UV-B was enhanced near the silking stage. Yield reduction that induced by enhanced UV-B radiation was associated with reductions in number of kernels per row and kernel mass. Protein content of grains was increased with enhanced UV-B radiation, but oil and starch contents were not affected. This study confirmed the sensitivity of maize to increased UV-B radiation under the field condition, and contributed to understand the full negative and positive effects of increased UV-B radiation on crop production.     

Molecular-genetic status of the adolescents living in the condition of the constant influense of low dose radiation

In the present investigation the analysis of the cytogenetic status and some blood characteristics of the adolescents from the contaminated area of Vulka-2 in Belarus has been done. The obtained data testifed that patients living in the condition of chronic radiation influence had essentially increased general frequency of all types of chromosome aberrations. First of all the elevated level of radiation markers is marked (0.54 +/- 0.11 and 0.11 +/- 0.05% in control. group, p < 0.05), the growth of double fragments (1.27 +/- 0.17 and 0.40 +/- 0.09% in control group, p < 0.05). The Spearmen correlation alalysis has revealed statistically significant increase of apoptosis level on the background of increased level of micronuclei (R = 0.832, p < 0.01). Thus our data testify that the degree of the biological homeostasis violation is intimately connected with the level of genome destabilization.     

Effect of low-level radiation on the death of male germ cells

Hormetic and adaptive responses induced by low-level radiation in hematopoietic and immune systems have been observed, as shown by stimulatory effects on cell growth and resistance to subsequent radiation-induced cytogenetic damage. However, in terms of cell death by apoptosis, the effects of low-level radiation are controversial: Some studies showed decreased apoptosis in response to low-level radiation while others showed increased apoptosis. This controversy may be related to the radiation doses or dose rates and also, more importantly, to the cell types. Testes are one of the most radiosensitive organs. The loss of male germ cells after exposure to ionizing radiation has been attributed to apoptosis. In the present study, the effects of low-level radiation at doses up to 200 mGy on mouse male germ cells in terms of apoptosis and the expression of apoptosis-related proteins were examined at different times after whole-body exposure of mice to low-level radiation. In addition, the effect of pre-exposure to low-level radiation on subsequent cell death induced by high doses of radiation was examined to explore the possibility of low-level radiation-induced adaptive response. The results showed that low-level radiation in the dose range of 25-200 mGy induced significant increases in apoptosis in both spermatogonia and spermatocytes, with the maximal effect at 75 mGy. The increased apoptosis is most likely associated with Trp53 protein expression. Furthermore, 75 mGy low-level radiation given pre-irradiation led to an adaptive response of seminiferous germ cells to subsequent high-level radiation-induced apoptosis. These results suggest that low-level radiation induces increased apoptosis in male germ cells but also induces a significant adaptive response that decreases cell death after a subsequent high-dose irradiation.     

Transgenerational transmission of radiation induced genomic instability

Stability of genome is one of the evolutionary important trait of cells. Various mutations (gene, chromosomal, genomic) as well as artificial manipulations with genomes (inbreeding, DNA transfection, introduction of Br-DU in DNA) cause the genetic instability. Ionizing radiation is known as the factor which induced instability of genome in late mitotic descendants of cells after in vitro and in vivo exposure. Radiation induced genetic instability can be transmitted through germline cells. On the cell level both types of radiation induced genomic instability are manifested in elevated frequency of mutations, chromosome aberrations, micronuclei, increased radiosensitivity, disappearance of adaptive response, changes in gene expression. In studies of 1970-1980 years clear evidences on the different morphological and functional injuries in tissues of irradiated organisms as well as in tissues of the progeny of exposed parents were obtained. On the organism level the instability of mitotic and of meiotic progeny of irradiated cells is resulted in increased risk of cancer and of other somatic diseases. It seems to be useful to review the earlier radiobiology literature where delayed and transgenerational effects of ionizing radiation on tissues and on organisms level were clearly shown in animals. For the estimation of pathogenic role of radiation induced genomic instability in humans, particularly in children of exposed parents the parallel study of the same human cohorts using clinical parameters and various characteristic of genomic instability seems to be very important.     

Protein sialylation by sialyltransferase involves radiation resistance

Previously, we identified beta-galactoside alpha(2,6)-sialyltransferase (ST6Gal I) as a candidate biomarker for ionizing radiation. The expression of ST6Gal I and the level of protein sialylation increased following radiation exposure in a dose-dependent manner. Radiation induced ST6Gal I cleavage and the cleaved form of ST6Gal I was soluble and secreted. Sialylation of integrin beta1, a glycosylated cell surface protein, was stimulated by radiation exposure and this increased its stability. Overexpression of ST6Gal I in SW480 colon cancer cells that initially showed a low level of ST6Gal I expression increased the sialylation of integrin beta1 and also increased the stability of the protein. Inhibition of sialylation by transfection with neuraminidase 2 or neuraminidase 3 or by treatment with short interfering RNA targeting ST6Gal I reversed the effects of ST6Gal I overexpression. In addition, ST6Gal I overexpression increased clonogenic survival following radiation exposure and reduced radiation-induced cell death and caspase 3 activation. However, removal of sialic acids by neuraminidase 2 or knockdown of expression by short interfering RNA targeting ST6Gal I restored radiation-induced cell death phenotypes. In conclusion, radiation exposure was found to increase the sialylation of glycoproteins such as integrin beta1 by inducing the expression of ST6Gal I, and increased protein sialylation contributed to cellular radiation resistance.     

Integration and scaling of UV-B radiation effects on plants: the relative sensitivity of growth forms and interspecies interactions

Aims The relative plant type sensitivity and selected community interactions under increased UV-B radiation where examined. Specifically, we investigated: (i) if there are differences among growth forms in regard to their sensitivity to UV-B radiation, (ii) if increased UV-B radiation influences the plant competitive balance in plant communities and (iii) the response mechanisms of the UV-B radiation-sensitive species that might increase their fitness.Methods To answer our research questions, we used a mechanistic model that, for the first time, integrated the effects of increased UV-B radiation from molecular level processes, whole plant growth and development, and community interactions.Important findings In the model simulations, species types exhibited different levels of sensitivity to increased UV-B radiation. Summer C₃ and C₄ annuals showed similar growth inhibition rates, while biennials and winter C₃ annuals were the most sensitive. Perennials exhibited inhibitions in growth only if increased UV-B radiation results in increases in metabolic rates. In communities, species sensitive to UV-B radiation may have a competitive disadvantage compared to resistant plant species. But, sensitive species may have a wide array of responses that can increase their fitness and reproductive success in the community, such as, increased secondary metabolites production, changes in timing of emergence and reproduction, and changes in seed size. While individual plants may exhibit significant inhibitions in growth and development, in communities, these inhibitions can be mitigated by small morphological and physiological adaptations. Infrequent or occasional increased UV-B radiation events should not have any lasting effect on the structure of the community, unless other environmental factors are perturbing the dynamic equilibrium.     

Regulatory role of low-intensity laser radiation on the status of the antioxidant system

On the base of modern literary data it is shown that low level laser red radiation can render the manifested effect on the activity of main antioxidant enzymes. It is determined that the main enzymes of antioxidant system--superoxide dismutase, catalase, ceruloplasmine--absorb in the red part of spectrum and are capable to be reactive under some regimes of red low level laser irradiation. It is one of the main possible mechanisms of biological efficiency of low level red laser radiation of the red part of spectrum.     

UV-B辐射对窄叶野豌豆生长繁殖的影响

采用增补和滤除掉部分自然UV-B辐射的模拟试验,研究了增强和近环境UV-B辐射对高寒草甸一年生牧草窄叶野豌豆生长和繁殖的影响.结果表明:增补UV-B辐射处理后,窄叶野豌豆的株高、生物量、分配向果实的生物量、总花数和种子百粒重均显著下降,花期延迟,开花集中度和繁殖成功率有所提高,而种子产量无显著变化.相对于减弱UV-B辐射处理,近环境UV-B辐射使窄叶野豌豆的株高先降后升,分配向果实的生物量减少,花期、花数和种子产量无显著变化,种子百粒重减小.增强和近环境UV-B辐射对窄叶野豌豆的生长和繁殖有一定的抑制作用,且增强UV-B辐射的影响更大.     

Effects of UV-B radiation on antioxidant parameters of iron-deficient barley plants

Iron deficiency is a stress frequently experienced by plants, owing to the low solubility of Fe(III) salts in neutral or alcaline soils. Iron is an essential plant nutrient as it is involved in fundamental metabolic processes. Furthermore, it is a constituent of important antioxidant enzymes, which are involved in maintaining the balance of cell redox state. UV-B radiation is an environmental problem which can alter the redox state of plants through the increased production of reactive oxygen species. In order to investigate if iron deficiency influences the antioxidant response of plants to UV-B radiation, barley seedlings, Hordeum vulgare L. cv. Express, were exposed to UV-B radiation while growing in nutrient solutions with or without iron. After eight days of growth, plants were harvested and analysed. Results show that, during the 8 days of the experimental period, in neither of the two nutritional conditions considered does UV-B exposure reduce shoot weight or induce evident alterations of thylakoid membranes in respect to controls. However, different responses to UV-B radiation between iron-deficient and iron-sufficient plants were observed at the level of parameters related to oxidative stress. In fact, in iron-sufficient plants the contents of photosynthetic pigments and ascorbate, and the enzyme activities of ascorbate peroxidase (EC 1.11.1.11) and catalase (EC 1.11.1.6) were not affected by UV-B radiation. Conversely, in iron-deficient plants the contents of ascorbate and zeaxanthin and the activity of ascorbate peroxidase increased under UV-B exposure, whereas catalase activity decreased. Furthermore, UV-B radiation induced an increase of hydrogen peroxide content which was higher in iron-deprived plants than in iron-sufficient ones. This may indicate that plants growing in an environment enriched in UV-B radiation may develop a high level of oxidative stress when iron supply is limited.     

The status of the endocrine function of the thymus in acute radiation sickness resulting from the accident at the Chernobyl Nuclear Power Station

Data are presented on the role of inhibition of endocrine function of the thymus in the pathogenesis of acute radiation sickness resulted from the direct and indirect (via the increased glucocorticoid production) effects of ionizing radiation. The complex treatment, including nonspecific active immunotherapy, permitted to normalize the thymic hormone level and certain parameters of the immune system.     

Integration and scaling of UV‐B radiation effects on plants: from DNA to leaf

A process‐based model integrating the effects of UV‐B radiation through epidermis, cellular DNA, and its consequences to the leaf expansion was developed from key parameters in the published literature. Enhanced UV‐B radiation‐induced DNA damage significantly delayed cell division, resulting in significant reductions in leaf growth and development. Ambient UV‐B radiation‐induced DNA damage significantly reduced the leaf growth of species with high relative epidermal absorbance at longer wavelengths and average/low pyrimidine cyclobutane dimers (CPD) photorepair rates. Leaf expansion was highly dependent on the number of CPD present in the DNA, as a result of UV‐B radiation dose, quantitative and qualitative absorptive properties of epidermal pigments, and repair mechanisms. Formation of pyrimidine‐pyrimidone (6‐4) photoproducts (6‐4PP) has no effect on the leaf expansion. Repair mechanisms could not solely prevent the UV‐B radiation interference with the cell division. Avoidance or effective shielding by increased or modified qualitative epidermal absorptance was required. Sustained increased UV‐B radiation levels are more detrimental than short, high doses of UV‐B radiation. The combination of low temperature and increased UV‐B radiation was more significant in the level of UV‐B radiation‐induced damage than UV‐B radiation alone. Slow‐growing leaves were more affected by increased UV‐B radiation than fast‐growing leaves.     

Sensitivity of duckweed (Lemna major) to ultraviolet-B radiation

The sensitivity of an important aquatic macrophyte, duckweed (Lemna major), to UV-B radiation was studied under experimental conditions at three different doses designated as no, mild, and severe injury dose by observing visible injury symptoms and estimating levels of chlorophyll, pheophytin, carotenoids, protein, starch, free sugar, and peroxidase activity. Laboratory-grown duckweed plants were exposed to UV-B radiation at 0.4 mW/cm(2) intensity for different time periods. Mild and severe injury were developed at 6.48 and 8.64 J, respectively. Peroxidase activity increased at all the exposure levels. Dose-dependent decrease in chlorophyll and starch with drastic depletion in protein and free sugar content were observed. Pheophytin and carotenoids content increased at no injury level, but decreased at higher exposure level. The results indicate that ambient UV-B radiation at the indicated level acts as a physiological stress in Lemna major.     

Effect of polyamines on the cellular radiation reaction

The influence of polyamines (e.g. putrescine, spermine and spermidine) on the survival rate of HeLa cells and the mitotic index of A. cepa meristem cells, as well as a change in a radiation response of cells under the effect of polyamines have been investigated. Putrescine was shown to produce the lowest cytotoxic effect on mammalian cells, whereas the cytotoxic effect on plant cells was either insignificant or absent at all. One-hour incubation of HeLa cells with putrescine of 5 x 10(-4)-5 x 10(-5) M prior to or after irradiation with a dose of 6 Gy increased the survived cell fraction. Spermine of 10(-3) M increased considerably the mitotic index of the exposed meristem as compared to irradiated meristem untreated with spermine. The role of polyamines in the formation of radiation damage to a cell is discussed.     

Effects of cadmium and enhanced UV radiation on the physiology and the concentration of UV-absorbing compounds of the aquatic liverwort Jungermannia exsertifolia subsp. cordifolia.

The aquatic liverwort Jungermannia exsertifolia subsp. cordifolia was cultivated for 15 d under controlled conditions to study the single and combined effects of cadmium and enhanced ultraviolet (UV) radiation. Both cadmium and UV radiation caused chlorophyll degradation and a decrease in the maximum quantum yield of photosystem II (PSII), together with an increase in the mechanisms of non-photochemical dissipation of energy (increase in the xanthophyll index). Cadmium was more stressing than UV radiation, since the metal also influenced photosynthesis globally and caused a decrease in net photosynthetic rates, in the effective quantum yield of photosynthetic energy conversion of PSII, and in the maximal apparent electron transport rate through PSII. Ultraviolet radiation increased the level of trans-p-coumaroylmalic acid and cadmium increased trans-phaselic and feruloylmalic acids. The increase in these compounds was probably related to both a more efficient absorption of harmful UV radiation and an enhanced protection against oxidative stress. DNA damage was specifically caused by UV-B radiation, but was intensified under the presence of cadmium, probably because the metal impairs the DNA enzymatic repair mechanisms. Ultraviolet radiation and cadmium seemed to operate additively on some physiological processes, while other responses were probably due to either factor alone.