Bimodal changes in germinability of pea seeds under the influence of low doses of gamma-radiation

Pea seeds (cv. 'Nemchinovskii-85', harvest of 2002, 80%-germination percentage) were exposed to gamma-radiation with doses ranging from 19 cGy to 100 Gy. One week after the irradiation with doses of 19 cGy and 3 Gy. the germination percentage decreased to 58 and 45%, respectively; at doses of 7 and 10 Gy it was 73 and 70% respectively. At greater doses (25, 50, and 100 Gy), germination percentage decreased in proportion. Anomalous changes in seed germination percentage (as a function of irradiation dose) were caused by the redistribution of irradiated seeds between fractions I and II. The measurements of room temperature phosphorescence in air-dry seeds and the phosphorescence of endogenous porphyrines of imbibing seeds showen that the germination decrease after the irradiation with low doses (19 cGy and 3 Gy) was caused by the increase in the number of weak seeds of fraction II, which had high rates of water uptake and suffered from hypoxia under seed coat. Some of these seeds suffocated from hypoxia, and other seeds produced seedlings with morphological defects (such seeds were considered incapable of germination). During storage of seeds irradiated at doses 19 cGy-10 Gy, the recovery of germination percentage (after its initial decrease) was caused by the decrease in seed number in fraction II. The subsequent germination decrease was caused by seed death. The higher was the irradiation dose, the faster were changes in germination percentage during storage of irradiated seeds. Bimodal changes in pea seed germination with the increase of y-irradiation dose has apparently the same origin as the changes in seed germination during accelerated ageing.     

γ射线对人淋巴细胞cx43和ANLN基因转录表达的影响

目的研究γ射线对人外周血淋巴细胞cx43和ANLN基因转录表达的影响。方法对数生长期的淋巴细胞,分别给予1、2、3、4、5、6 Gy的^60Coγ射线照射,照射后12h,以及2Gy照射后4、8、12、24、36、48、72h,分别提取总RNA,反转录成cDNA。利用实时荧光定量PCR技术,检测各组cx43和ANLN基因表达改变。结果人外周血淋巴细胞cx43 mRNA表达水平在2Gy照射后4、8、12h明显增高,分别为对照组（未照射组）的6．74、9．06、7．22倍（P〈0．05）;24～72h,其表达水平与对照组相比没有明显变化。1、2、3、4、5、6Gy剂量照射后12h,cx43 mRNA表达水平显著增高（P〈0．05）。ANLN mRoNA表达水平在2Gy不同时间点及1～5Gy照射后12h,表达降低（P〈0．05）,6Gy照射后12h其表达开始升高,为对照组的6．08倍（P〈0．05）。结论γ射线照射2Gy不同时间点及不同剂量照射后12h,cx43基因表达上调,ANLN基因表达下调。1～3Gy剂量照射后12h,cx43 mRNA表达在此范围内有时间和剂量的依赖性。cx43可能会发展为核事故受照射人员的分子生物学剂量标记物。     

Mechanism of injury of air-dry pea seeds under the influence of low doses of gamma-radiation

The aim of this work was to determine which processes in air-dry seeds result in bimodal changes of the pea seed quality under the influence of low doses of gamma-radiation. Pea seeds (cv. "Nemchinovsky-85", harvest 2006, 82% germination persentage) were exposed to gamma-radiation at doses of 3, 10 and 100 Gy The germination percentage decreased to 45% four days after irradiation at the dose of 3 Gy, rised up to 87% at doses of 10 Gy, while the dose of 100 Gy killed the most part of seeds. Seed fractions differing in quality were selected using the metod of Room temperature phosphorecsence (RTP): strong seed frasction I from non-irradiated seeds; weak seed fraction II from the seeds irradiated at a dose of 3 Gy; dead seeds from the seeds irradiated at a dose of 100 Gy. ThermoChemiLuminecnsece (TCL) of seed powders and cotyledons was used. It was shown that the increase of the TCL level in the temperature range from 50 to 110 degreesC was associated with the lipid peroxidation products. The TCL level of seeds subjected to gamma-irradiation at a dose of 3 Gy was similar to that of non-irradiated seeds in the temperature range 50 to 100 degreesC. Therefore, lipid peroxidation was not the cause of the abnormal seedling appearance. The TCL level within this temperature range was increased only in seeds subjected to y-irradiation at a dose of 100 Gy. The TCL level at 150 degreesC was in proportion with the exogenous glucose amount. The increased TCL level of seeds subjected to y-irradiation at a dose of 3 Gy at 150 degreesC resulted from the increase of the glucose content. This means that the transition from the fraction of strong seeds into the fraction of weak ones was the result of the activation of hydrolysis processes. Decrease in the water content of seeds testified to utilization of bound water in this process. The decrease of the glucose content in the "improved" seeds subjected to gamma-irradiation at a dose of 10 Gy most probably indicates the participation of glucose in the amino carbonyl reaction. The latter could be the reason for the increased water content in the "improved" seeds and a decreased water permeability of cell membranes.     

The disruption of aquaporin function in cell membranes as a cause of changes in germinability of pea seeds after exposure to low doses of gamma-radiation

Pea seeds (Pisum sativum L.) from the seed lot with 80% germinability were separated in fractions according to room temperature phosphorescence: strong seeds were assigned to fraction I, and weak seeds formed to fraction II. During imbibition, the seeds of fraction II exhibited twofold higher rates of water uptake and experienced hypoxia. Some of these seeds suffocated from hypoxia, and other seeds produced seedlings with morphological defects (such seeds were considered incapable of germination). One week after irradiation with the dose of 3 Gy, germination percentage decreased to 45%, which was caused by the increase of number of weak seeds. The germinability of seeds subjected to gamma-irradiation at doses of 7 and 10 Gy was similar to that of control seeds. In these sub-lots, there appeared so-called "improved" seeds, which were similar to non-irradiated seeds in terms of phosphorescence level, the rate of water uptake and germination percentage. It was shown with the use of PCMB that the difference in the rates of water uptake by seeds of fraction I and II depended on the permeability of cell membranes. The permeability was determined by the state of aquaporins ("open"-"closed"). The experiments with phosphatase inhibitor (NaF) shown that in seeds irradiated with dose of 3 Gy (fraction II), the mechanism of aquaporins closing was broken (phosphatase was inactivated). In "improved" seeds (after irradiation with dose of 10 Gy), aquaporins were closed irreversibly in air-dry state, when aquaporin dephosphorylation was unlikely. It was concluded that the abnormal increase (following the initially decrease) in germination of pea seeds after irradiation can be explained without invoking the hypothesis on hyper function of reparatory mechanism of at low doses of irradiation.     

不同剂量的X-射线全身照射对小鼠健康状况及涎腺的影响

目的:通过直线加速器全身照射昆明小鼠建立辐射损伤模型,探索不同放射剂量对小鼠健康状况及涎腺功能和结构的影响。方法:选取八种不同剂量对昆明小鼠行体外全身照射,于照射后一个月内观察小鼠生长情况、体重变化;照射后一周、一个月检测各组小鼠血象的变化;测定放射半数致死剂量;照射后两个月,测定各组小鼠的唾液流量及唾液淀粉酶含量,并对下颌下腺组织切片行HE染色。结果:13Gy和15Gy照射组小鼠的体重逐渐下降,一周后死亡,其余组小鼠体重最终呈增加趋势。X-射线全身照射的半数致死量为10Gy。照射后一周,照射组小鼠的白细胞数目明显降低,与对照组比较有明显统计学差异(P0.01);在其他血象方面,除了7Gy组外,其他照射组与对照组比较也均有统计学差异(P0.05)。照射一个月后,各照射组小鼠的血象均恢复正常。照射后两个月,9Gy组和11Gy组小鼠的唾液流量及唾液淀粉酶含量均显著低于0Gy组,且11Gy组较9Gy组亦明显降低,差异均有统计学意义(P0.05)。随照射剂量的增加,小鼠的下颌下腺腺泡细胞数目逐步减少,结构排列紊乱,组织损伤逐渐加重。结论:X-射线全身照射引起小鼠健康状况受损,免疫功能减低,损伤程度与放射线强度呈剂量依赖性,小鼠半数致死量为10Gy,该剂量适合建立全身放射损伤模型。     

Wheat plant DNA methylation pattern changes at chronic seed γ irradiation

Alterations of DNA methylation patterns of two wheat sorts Al’batros odesskii and Donetskaya-48 whose seeds were irradiated with a low dose rate (3 × 10^?7 Gy/s) for 4 months have been studied. Six restriction endonucleases were used in the experiments. Primary distinction in DNA methylation patterns of the studied sorts has been demonstrated. Chronic irradiation resulted in an increase of the methylation level on the recognion site for GluI and Sou3AI and in a decrease of this index in recognion sites for endonucleases GlaI and HpaII. The alterations of the methylation level in recognition sites for restrictases MboI and MspI were not found. The considerable increase of chromosome aberration level at the same dose of chronic irradiation has been shown. The role of DNA methylation pattern changes in development of irradiation damage and organism protective reactions is discussed.     

The dynamics of cytogenetic anomalies output in seedling merysteme at the chronic irradiation of seeds

The dynamics of chromosomal aberrations in seedling root merysteme is explored in various terms of irradiation of two genotype corn dry seeds. The effects of chronic irradiation with low rate dose, with acute and with combined irradiation are explored in the different terms of seed storage. It is shown that the output of chromosomal aberrations and of the efficiency of irradiation (1/Gy) change depending on the accumulated dose of chronic irradiation and for both genotypes are described by unmonotonous functions. Efficiency of acute irradiation changes the dependence on the terms of seed storage. The efficiency of chronic irradiation considerably exceeds the efficiency of acute irradiation. Antagonistic effect of combined irradiation dry seeds of one of genotypes is marked.     

Stability of a second-generation cephalosporin veterinary mastitis formulation after electron beam irradiation

This study focused on the chemical stability of the cephalosporin {ie28-1} acid, sodium salt (cephem 1) formulation after electron beam (e-beam) irradiation. The cephem 1 concentrations of samples irradiated at 5, 10, and 15 kilograys for glass vials and low-density polyethylene (LDPE) cannula syringes were not statistically different from the concentrations of the nonirradiated control samples. Samples from each irradiation dose stored in controlled-temperature chambers at 5°C and 30°C for 24 months did not show any concentration changes within statistical limits compared with the nontreated samples. Samples from each irradiation dose stored at 40°C for 12 months also did not show any concentration changes within statistical limits compared with the nontreated samples. The percentage of related substances increased slightly with the increase in ebeam irradiation level and storage temperature, but this increase was within the proposed label claim of 90% to 110% (45–55 mg/g). In conclusion, e-beam sterilization did not affect the chemical stability of cephem 1 intramammary formulation in LDPE cannula syringes, suggesting that e-beam irradiation may be a feasible method for terminal sterilization of this cephem 1 formulation.     

重离子辐照玉米种子引起的基因组DNA变异分析

利用HI-13串列加速器产生的10 Gy、20 Gy、30 Gy和50 Gy ~7Li和~(12)C重离子束对玉米自交系478的干种子进行辐照,并用RAPD分析技术分析其变异情况.结果表明重离子~7Li和~(12)C辐照玉米种子可引起当代基因组DNA水平上的变异,一定范围内变异频率与注入剂量有关,在相同剂量下~7Li离子辐照的诱变率高于~(12)C离子辐照.     

Effect of X irradiation on adenosine triphosphate and glucose-6-phosphate dehydrogenase in the CaNT mouse tumor

The levels of adenosine triphosphate (ATP) in the transplantable CaNT murine tumor grown in CBA mice at various times following 5, 10, and 15 Gy X rays (100 kVp) were increased within 45 min. Maximal ATP levels occurred at 2.5 h following the 10 Gy dose (3.8 times that of unirradiated controls), returning almost to control levels by 13 h after irradiation. The specific activity of glucose-6-phosphate dehydrogenase (G-6-PDH) after 10 Gy increased about 1.5-fold 1 h after irradiation, returning to control levels by 48 h. It is suggested that the increased ATP following irradiation might play a major role in energy provision when cellular repair processes are able to operate. The increased G-6-PDH activity after irradiation may reflect enhanced metabolism associated with cellular repair mechanisms.     

Metallothionein induction as a potent means of radiation protection in mice

A striking resistance to lethal damage from a single dose of 6-8 Gy of X rays has been found in mice which had received various pretreatments to induce metallothionein (MT) synthesis in the liver prior to irradiation. Mice were injected with manganese (10 mg Mn/kg) or cadmium (3 mg Cd/kg) salt subcutaneously, or a patch of dorsal skin (2 X 2 cm2) was excised 1 or 2 days prior to irradiation. The increased tolerance of these mice to radiation was established by a marked decrease of mortality rate, an increase of mean survival time, a reduction of weight loss, and a smaller decrease in the number of leukocytes as compared with the control group. The LD50/30 for control mice was 6.3 Gy, while the corresponding values for the groups pretreated with Mn, Cd, and skin excision were 7.5, 7.7, and 7.9 Gy, respectively. The normal level of MT in mouse liver was approximately 25 micrograms/g tissue. This level increased 2.5- to 3-fold 24 h after 6.3 Gy irradiation. The MT levels of mice pretreated with Cd, Mn, and skin excision were increased 8-, 5-, and 7-fold, respectively, prior to irradiation as compared with the preirradiation control. These results indicate that the induction of MT in mouse liver is a significant factor in the mechanism of protection against radiation.     

Effect of low doses of gamma irradiation on in vitro growth of grapevine

Shoot tips and single node explants of two rootstocks (R.99 and 3309) and two varieties (‘Helwani’ and ‘Cabernet Franc’) of grapevine cultured on DSD1 media for a period of 60 days, were irradiated with 0, 2, 5 and 7 Gy doses of gamma irradiation. Shoot length of ‘Helwani’ and ‘Cabernet Franc’ was increased by 7 Gy irradiation. The 5 Gy dose increased the number of roots in plants of the two rootstocks and ‘Helwani’. Root length of ‘Helwani’ and ‘Cabernet Franc’ at the 2 and 7 Gy doses were significantly higher than those of the non-irradiated control. A similar effect was noticed on R.99 rootstock subjected to 5 Gy. Five Gy also increased the dry weight of the R.99 rootstock, whereas 2 and 7 Gy had a similar effect on ‘Helwani’ and ‘Cabernet Franc’. Number of leaves of plants exposed to 5 and 7 Gy was increased when compared with the non-irradiated control. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of gamma irradiation on microbial load and sensory characteristics of aniseed (Pimpinella anisum)

Seeds of anise (Pimpinella anisum) were exposed to doses of 0, 5, 10, 15 and 20kGy in a (60)Co package irradiator. Irradiated and unirradiated samples were stored at room temperature. Microbial populations on seeds, total and inorganic soluble solids in water extract and sensory properties of the latter were evaluated after 0, 6 and 12 months of storage. Results indicated that gamma irradiation reduced the aerobic plate counts of aniseed. Immediately after irradiation, the total soluble solids in an extract of irradiated seeds were greater than those of unirradiated ones. The total soluble solids in an extract of irradiated and un-irradiated seeds increased after 6 and 12 months of storage. There were no significant differences (p>0.05) in inorganic soluble solids between the water extract of irradiated and unirradiated aniseeds. Sensory evaluation indicated that gamma irradiation improved sensory characteristics of aniseed water extract tested immediately after irradiation; however, after 12 months of storage, no significant differences (p>0.05) were found in color, taste or flavor between extract of irradiated and unirradiated seeds.     

Physiological effects of glycinebetaine on gamma-irradiated stressed fenugreek plants

Irradiation stress adversely affects plant growth and development. The radio protective activity by glycinebetaine in plants has not been reported, and its mechanism has not been known. Gamma rays at doses 0.0, 25, 50, 100, and 150 Gray (Gy) when applied pre-sowingly to dry seeds of fenugreek from a cobalt source (⁶⁰Co) with strength of 500 Ci and the dose rate of 0.54 Gy/min significantly reduced chlorophyll content, total protein, photosynthetic efficiency (¹⁴CO₂-fixation), total dry weight, the accumulation of reducing, non-reducing and total soluble sugars in comparison with un-irradiated control. It also significantly repressed the activities of hydrolytic enzymes (α-amylase and invertase), the carboxylating enzyme (ribulose-1,5-bisphosphate-carboxylase/oxygenase) in the developed fenugreek plants. Soaking irradiated seeds with glycinebetaine (50 mM) for 24 h partially alleviated the depression effects of irradiation in these parameters. γ-irradiation treatment increased significantly H₂O₂ content. Presoaking irradiated seeds with GB decreased significantly the H₂O₂ level. The magnitude of the reversal decreased with increasing the irradiation dose. γ-irradiation induced a significant decrease in the level of nucleic acids (DNA and RNA) accompanied by a corresponding induction of hydrolytic activities of DNase and RNase in the developed plants in comparison with un-irradiated control. Those changes were more significant at higher γ-ray doses. Post-treatment of irradiated seeds with GB partially alleviated the adverse effects of radiation. It significantly increased nucleic acid levels and repressed the activities of DNase and RNase. The protective role played by glycinebetaine was more significant at lower γ-ray doses. Pretreatment of seeds with GB may play an effective role in the radio-repair mechanism.     

Semiquantitative detection of cytokine messages in X-irradiated and regenerating rat thymus

We investigated the expression of cytokine mRNA derived from thymocytes or thymic epithelial cells in X-irradiated (8 Gy) and recovering rat thymuses, according to our previous observation (Mizutani et al., Radiat. Res. 157, 281-289, 2002). The changes in mRNA expression level of interleukin 2 (Il2), Il4, tumor necrosis factor alpha (Tnf), interferon gamma (Ifng), and transforming growth factor beta (Tgfb) were examined. The mRNA expression of Il2 and Il4 decreased from day 5 to day 14 after irradiation. Thereafter, the expression level of Il2 mRNA recovered to normal control levels; however, the expression of Il4 mRNA tended toward significantly low levels. Tnf mRNA expression decreased on day 5 after irradiation and then showed a gradual increase back to normal control levels. Tgfb mRNA expression did not change significantly. Ifng mRNA expression was transiently enhanced from day 11 to day 14. The mRNA expression levels of Il10 increased significantly from day 3 to day 7 after irradiation. In addition, the mRNA expression of thymic epithelial cell-derived Il7 showed a transient decrease on day 3; however, then it showed a continuous increase from day 5 to day 21, finally reaching twice the normal control levels after X irradiation. These observations suggest that the expression of cytokine messages in the irradiated thymus changed significantly and did not return to normal for a long time after 8 Gy irradiation.     

Suppression of thymic lymphoma induction by life-long low-dose-rate irradiation accompanied by immune activation in C57BL/6 mice

The induction of thymic lymphomas by whole-body X irradiation with four doses of 1.8 Gy (total dose: 7.2 Gy) in C57BL/6 mice was suppressed from a high frequency (90%) to 63% by preirradiation with 0.075 Gy X rays given 6 h before each 1.8-Gy irradiation. This level was further suppressed to 43% by continuous whole-body irradiation with 137Cs gamma rays at a low dose rate of 1.2 mGy/h for 450 days, starting 35 days before the challenging irradiation. Continuous irradiation at 1.2 mGy/h resulting in a total dose of 7.2 Gy over 258 days yielded no thymic lymphomas, indicating that this low-dose-rate radiation does not induce these tumors. Further continuous irradiation up to 450 days (total dose: 12.6 Gy) produced no tumors. Continuously irradiated mice showed no loss of hair and a greater body weight than unirradiated controls. Immune activities of the mice, as measured by the numbers of CD4+ T cells, CD40+ B cells, and antibody-producing cells in the spleen after immunization with sheep red blood cells, were significantly increased by continuous 1.2-mGy/h irradiation alone. These results indicate the presence of an adaptive response in tumor induction, the involvement of radiation-induced immune activation in tumor suppression, and a large dose and dose-rate effectiveness factor (DDREF) for tumor induction with extremely low-dose-rate radiation.     

碳离子辐照对四尾栅藻光合色素及抗氧化活性的影响

为了探讨重离子辐照对微藻的生物学效应,实验研究了不同剂量碳离子辐照（10~80 Gy）对四尾栅藻（Scenedesmus quadricauda）光合色素及抗氧化活性的影响,分别测定了辐照后短期内其叶绿素a（Chl a）、叶绿素b（Chl b）和类胡萝卜素含量、脂质过氧化物丙二醛(MDA)含量及超氧化物歧化酶（SOD）活性。结果显示：(1)较低剂量（10~20 Gy）辐照后,光合色素含量变化较小或无显著变化,中等剂量（40~60 Gy）辐照后,光合色素含量显著升高,之后又回落,恢复至正常水平,高剂量（80 Gy）辐照后,光合色素含量明显降低,不能恢复正常;(2)低剂量（10 Gy）辐照后,丙二醛（MDA）含量显著上升,8 h后出现回落,到24~48 h时,回升至正常水平,较低剂量（20 Gy）辐照后,MDA含量瞬时有所下降,到24~48 h时,回升至正常水平,中等至高剂量（40~80 Gy）辐照后,MDA含量降低,24~48 h时显著升高,不能恢复正常;(3)低剂量（10 Gy）辐照后,超氧化物歧化酶（SOD）活性显著上升,8 h后出现回落,恢复正常,中等剂量（20~60 Gy）辐照后,SOD活性显著上升,到48 h时回落至正常水平,高剂量（80 Gy）辐照后,SOD活性无明显上升,到48 h时,活性明显降低,不能恢复正常。     

Antihypertensive activity of transgenic rice seed containing an 18-repeat novokinin peptide localized in the nucleolus of endosperm cells

Novokinin (Arg-Pro-Leu-Lys-Pro-Trp, RPLKPW) is a new potent antihypertensive peptide based on the sequence of ovokinin (2-7) derived from ovalbumin. We previously generated transgenic rice seeds in which eight novokinin were fused to storage protein glutelins (GluA2 and GluC) for expression. Oral administration of these seeds to spontaneously hypertensive rats (SHRs) reduced systolic blood pressures at a dose of 1 g seed/kg of SHR. Here, 10- or 18-tandem repeats of novokinin with an endoplasmic reticulum (ER) retention signal (Lys-Asp-Glu-Leu, KDEL) at the C terminus were directly expressed in rice under the control of the glutelin promoter containing its signal peptide. Only small amounts of the 18-repeat novokinin accumulated, and it was unexpectedly deposited in the nucleolus. This abnormal intracellular localization was explained by an endogenous signal for nuclear localization. The GFP reporter protein fused to this sequence targeted to nuclei by a transient assay using onion epidermal cells. Transgenic seed expressing the 18-repeat novokinin exhibited significantly higher antihypertensive activity after a single oral dose to SHR even at one-quarter the amount (0.25 g/kg) of the transgenic rice seed expressing the fusion construct; though, its novokinin content was much lower (1/5). Furthermore, in a long-term administration for 5 weeks, even a smaller dose (0.0625 g/kg) of transgenic seeds could confer antihypertensive activity. This high antihypertensive activity may be attributed to differences in digestibility of expressed products by gastrointestinal enzymes and the unique intracellular localization. These results indicate that accumulation of novokinin as a tandemly repeated structure in transgenic rice is more effective than as a fusion-type structure.     

High-dose γ-irradiation enhances the expression of a transgene controlled by the immediate-early CMV promoter in stably transfected tumor cells

γ-irradiation is commonly used to inactivate whole-cell anticancer vaccines containing viable tumor cells. To evaluate the effect of γ-irradiation on transgene expression in tumor cells, human and mouse cell lines were stably transfected with constructs expressing the granulocyte macrophage colony-stimulating factor (GM-CSF) or green fluorescent protein (GFP) gene under the control of the immediate-early CMV promoter. Irradiation of cells at 20–100 Gy caused a loss of proliferation capacity and gradual cell death, with the survival depending on the irradiation dose. G2/M cells accumulated in irradiated cultures, while the portion of S-phase cells was reduced. Surviving cells displayed activation of β-galactosidase and morphological changes associated with cell senescence. Mitochondrial dehydrogenase activity did not change with the irradiation dose. Irradiated cells retained transgene expression. Moreover, the amount of secreted GM-CSF and GFP production significantly increased after γ-irradiation, up to tenfold in cells exposed to 100 Gy. Transgene expression increased gradually and positively correlated with the total irradiation dose. The results demonstrate that γ-irradiation at 100 Gy is optimal for whole-cell anticancer vaccine inactivation.     

Restoration of pine plantations after effect of ionizing radiation in the region of the accident at the Chernobyl Atomic Energy Station

The main results of the 12-year radiation-genetic monitoring of radiobiological, cytogenetic, and genetic parameters in the Pinus sylvestris L. forest plantations from the zone of the accident at the Chernobyl nuclear power plant presented. Acute ionizing irradiation at doses > 1 Gy was shown to induce the formation of morphoses and depressed growth; at doses > 2 Gy, the reproductive ability of the trees declined. The radiobiological parameters showed a linear (or close to linear) dose-effect relationship. Acute irradiation at a dose of 0.5 Gy induced cytogenetic and genetic effects that were significantly higher than the corresponding control values. The relationship between the cytogenetic effects and the absorbed dose was exponential. The dependence of the mutation frequency at specific loci on the absorbed dose was described by a nonlinear curve. The results of cytogenetic analysis of sprouts obtained from seeds annually (1986-1998) collected in zones of slight, moderate, and strong damage of Pinus sylvestris L. are presented.