碳离子辐照对菘蓝药性品质和分子水平的诱变效应

以野生菘蓝种子为材料,以不同剂量的碳离子(12 C6+)进行辐照处理(辐照剂量分别为30Gy、60Gy、90Gy、120Gy),分析12 C6+辐照对菘蓝种子萌发、幼苗生长、主要药用成分含量及其基因和蛋白质多态性变化的影响,为菘蓝品质育种、分子生物学研究和重离子辐照诱变的应用提供依据。结果显示:(1)12 C6+辐照处理后菘蓝的成苗率和根鲜重均随辐照剂量增加而逐步显著降低,其中30Gy处理对菘蓝生长抑制程度最小,但处理后菘蓝根中的主要药效成分4(3H)喹唑酮和靛玉红的含量增加幅度最大且最高,分别为野生型的2.2倍和2.3倍。(2)SRAP分子标记分析表明,菘蓝基因组的变异度随着辐照强度的增强而增大,其中30Gy处理的突变体与野生型相比有33.59%的多态性变异。(3)SDS-PAGE考马斯亮蓝染色和磷酸化染色分析表明,菘蓝的总蛋白和磷酸化蛋白表达水平均随辐照剂量变化出现了不同程度的改变,但并不与辐照强度呈正相关,说明植物在防御重离子辐照伤害时存在补偿机制。研究发现,30Gy的12 C6+辐照是菘蓝诱变的最佳剂量,能够显著提高其有效成分的含量,为优质菘蓝诱变育种奠定了基础。     

Does exposure of male Drosophila melanogaster to acute gamma radiation influence egg to adult development time and longevity of F1–F3 offspring?

Two‐ to three‐day‐old male Drosophila melanogaster flies were irradiated with 1, 2, 4, 6, 8, 10, 20, 25, 30, 40 and 50 Gy doses of gamma radiation. The longevity and rate of development were observed for three successive generations to assess the impact of irradiation. The mean lifespan of irradiated flies was significantly increased at 1, 2 and 8 Gy, while it was vice versa for high doses at 30, 40 and 50 Gy. Paternal irradiation had an impact on F₁ generation, with significantly increased mean longevity at 2 (female), 4, 6, 8 and 10 and decreased mean longevity at 40 and 50 Gy (male and female). Significant increase in the longevity was observed in the F₂ generation of the 8 (male and female) and 10 Gy (male) irradiated groups, while decreased longevity was observed in F₂ female progeny at 40 Gy. In the case of F₃ progeny of irradiated flies, longevity did not show significant difference with the control. Paternal exposure to radiation had a significant impact on the mean egg to adult developmental time of the F₁ generation; it was shortened at 2 Gy and extended at 25, 30, 40 and 50 Gy compared to the control. Mean development time at 30, 40 and 50 Gy was significantly increased in the F₂ generation, while there were no significant changes in the F₃ generation. The present study concludes that the effect of acute gamma irradiation on longevity and “egg to adult” development time of D. melanogaster may persist to following generations.     

Morphological changes in the kidney after 5/6 nephrectomy and low-dose radiation

In the present study, we investigated the effect of low-dose irradiation of experimental nephrectomized rats. We hypothized that the low-dose irradiation may slow down the development of focal-segmented glomerulosclerosis (FSGS) after 5/6 nephrectomy. Experiments were performed with 32 male Wistar rats, divided into four groups. The first group contained only operated animals. Animals in the second and third groups were irradiated on the next day after operation with 1 and 3 Gy, respectively. The healthy animals made the forth, control group. Attention was focused on physiological and morphological changes after low-dose (1 and 3 Gy) irradiation. We measured blood pressure, proteinuria, serum creatinin and cysC. Morphological changes of glomerulus and tubules were studied. Animals of the first group had significantly thicker glomerular basement membrane, compared to animals of other groups. The morphological study demonstrated degeneration of the tubular epithelium, tubular atrophy and FSGS. Besides, it was shown that changes in the third group (3 Gy) were less than in nephrectomized (first group) and 1 Gy (second group). The animals of the third group (3 Gy) had significantly lower proteinuria and FSGS. We conclude that our hypothesis, suggesting that low-dose irradiation slows down the development of FSGS, was confirmed.     

Changes in osteoclasts after irradiation with carbon ion particles

We examined the effects of radiation on decreases in osteoclast numbers after regional irradiation of rats with carbon ions and gamma rays. Male Wistar rats were subjected to hind-leg irradiation with carbon ions (290 MeV/u) or gamma rays at doses of 15, 22.5, or 30 Gy. The effects of carbon ions and gamma rays on osteoclasts were studied using histologic and morphometric methods. At doses of 15 Gy and 22.5 Gy, osteoclast numbers increased transiently until day 5 after irradiation and then decreased rapidly in both the carbon ion and gamma ray irradiation groups. The carbon ion group showed reduced osteoclast size compared with the gamma ray group. Carbon ion irradiation had a more marked effect on osteoclast activity, and suppressed maturation to a greater extent than gamma irradiation. These observations suggest that carbon ion irradiation induces differential modulation of osteoclast growth factor expression.     

Inverse dose-rate effect of DNA breaks and inactivation of transforming activity induced by tritiated water and60COγ-rays

Summary When an aqueous solution of plasmid DNA at a constant low concentration of 5 µg/cm³ was irradiated with⁶⁰Co-rays, D₃₇ dose of single-strand breaks was decreased from 18 Gy at a dose-rate of 6.77 Gy/h of acute irradiation to 2.3 Gy at a dose-rate of 0.00212 Gy/h. OrG value was increased from 0.0010 to 0.0081. Similar dose-rate dependency of D₃₇ dose andG value were also found when the plasmid DNA solution was treated with various concentrations of tritiated water at various dose-rates, ranging from 5.13 Gy/h to 0.000118 Gy/h. RBE of tritiumß-rays for single-strand breaks was ranged from 0.3 to 0.5 in a wide range of dose-rates. When the DNA solution was saturated with argon to remove oxygen, the dose-rate dependency of-rays was abolished and that of tritiumß-rays was significantly supressed. When the DNA solution in air was kept at 4° C for 50 h or 25 days after acute irradiation, theG value of DNA breaks was the same as that kept at —20° C for the same period, but much lower than that of the solution irradiated for the same period at a lower dose-rate to give the same total doses. This shows that the inverse dose-rate effect could not be induced from the different exposure periods but from continuous irradiation of different dose-rates. The inverse dose-rate effect for inactivation of transforming activity of DNA irradiated with tritiated water was also observed in the range from 0.0588 Gy/h to 0.00118 Gy/h.     

Fecundity,fertility and reproductive recovery of irradiated Queensland fruit fly Bactrocera tryoni

Pupae of the Queensland fruit fly or Q‐fly Bactrocera tryoni (Froggatt) are irradiated routinely to induce reproductive sterility in adults for use in sterile insect technique programmes. Previous studies suggest that adult sexual performance and survival under nutritional and crowding stress are compromised by the current target dose of radiation for sterilization (70–75 Gy), and that improved mating propensity and survival under stress by irradiated males may be achieved by reducing the target sterilization dose without reducing the level of induced sterility. This raises the question of the amount by which the irradiation dose can be reduced before residual fertility becomes unacceptable. The present study measures the levels of residual fertility in male and female irradiated Q‐flies at different irradiation doses (20, 30, 40, 50, 60 and 70 Gy), and investigates the possibility that fecundity and fertility increase between 10–15 and 30–35 days post emergence. Male flies require a higher dose than females to induce sterility, with no residual fertility found in females irradiated at doses of 50 Gy or above, and no residual fertility found in males irradiated at doses of 60 Gy or above. Irradiated females are more fecund at 30–35 days post emergence than at 10–15 days. However, fertility does not increase between 10 and 15 days post emergence and 30–35 days, even at doses below 50 Gy. The present study shows that there is scope to reduce the target sterilization dose for Q‐flies below that of the current dose range (70–75 Gy) at the same time as retaining an adequate safety margin above radiation doses at which residual fertility can be expected.     

Two-phase response of rat pineal melatonin to lethal whole-body irradiation with gamma rays.

Male Wistar rats adapted to artificial light:dark (LD) regimen 12:12 h were whole-body irradiated with a single dose of 9.6 Gy of gamma rays and sham/irradiated in the night in darkness. The rats were examined 60 min, 1, 3 and 5 days after exposure between 22:00 and 01:30 h in the darkness. The results obtained indicate a two-phase reaction of pineal melatonin after the lethal irradiation of rats: the decline of melatonin concentration early after the exposure (at 60 min) with unchanged serotonin N-acetyltransferase (NAT) activity followed by an increase of melatonin synthesis, accompanied by an increase of pineal and serum melatonin on day 5 after the exposure. NAT activity was increased on day 3 after the exposure. Serum corticosterone concentrations in irradiated rats were increased 60 min and 3 days after exposure. With respect to the antioxidant, immunomodulating and stress-diminishing properties of melatonin, we consider the increase in melatonin synthesis during later periods after irradiation as part of adaptation of the organism to overcome radiation stress.     

Survival and reproduction of Liposcelis paeta (Pearman) (Psocoptera: Liposcelididae) when irradiated by electron beams

Electron beam irradiation has been evaluated for the survival and reproduction of Liposcelis paeta Pearman (Psocoptera: Liposcelididae). All effects increased with increasing doses from 50 to 1000 Gy when the electron energy was 2 MeV. Eggs were unable to develop into adults following a dose of 100 Gy. Complete (100%) mortality was achieved about 5 weeks after adult emergence from nymphs irradiated at 300 Gy, whereas 100% mortality of adults was achieved 9 weeks after irradiation at 300 Gy. The fecundity was greatly reduced to 1.82% of that of control when L. paeta adults were irradiated at 250 Gy. A dose of 300 Gy caused complete reproductive sterility in adults. These results suggest that the most susceptible stage was the egg stage, then nymph and adult stages. A dose of 300 Gy is suggested for quarantine treatment of commodities infested by L. paeta.     

Acute and long-term effects of two different static stretching training protocols on range of motion and vertical jump in preadolescent athletes

This study examined the acute and long-term effects of two static stretching protocols of equal duration, performed either as a single stretch or multiple shorter duration repetitions on hip hyperextension range of motion (ROM) and single leg countermovement jump height (CMJ). Thirty female gymnasts were randomly assigned to stretching (SG) or control groups (CG). The SG performed two different protocols of static stretching, three times per week for 9 weeks. One leg performed repeated stretching (3 × 30 s with 30 s rest) while the other leg performed a single stretch (90 s). The CG continued regular training. ROM and CMJ were measured pre- and 2 min post-stretching on weeks 0, 3, 6, 9, and 3 weeks into detraining. CMJ height increased over time irrespective of group (main effect time, p = 0.001), with no statistical difference between groups (main effect group, p = 0.272). Three-way ANOVA showed that, CMJ height after stretching was not affected by either stretching protocol at any time point (p = 0.503 to 0.996). Both stretching protocols equally increased ROM on weeks 6 (10.9 ± 13.4%, p < 0.001, d = 0.42), and 9 (21.5 ± 13.4%, p < 0.001, d = 0.78), and this increase was maintained during detraining (17.0 ± 15.0%, p < 0.001, d = 0.68). No increase in ROM was observed in the CG (p > 0.874). Static stretching of long duration applied either as single or multiple bouts of equal duration, results in similar acute and long-term improvements in ROM. Furthermore, both stretching protocols do not acutely affect subsequent CMJ performance, and this effect is not influenced by the large increase in ROM and CMJ overtime.     

Dentin hypersensitivity induces anxiety and increases corticosterone serum levels in rats

Aims

Investigate the relationships between experimentally induced dentin hypersensitivity (DH) with behavioral, endocrine and dentin erosion data.

Methods

Male Wistar rats divided into four groups, two controls and two experimental, received tap water or isotonic solution (Gatorade®, lemon, pH 2.7) for 30 or 45 days. The DH test was performed by a cold water stimulus on molars. A score (0–3) was given to the rats' pain response. Anxiety was evaluated by the elevated plus maze model and by serum corticosterone levels. The dentin erosion was observed by scanning electron microscopy (SEM). Anatomopathological studies were performed on the stomach, adrenal, kidney, and liver.

Results

Relative to control groups, experimental rats showed: 1) increased hypersensitivity scores (control group, 0; experimental groups, 2 (limits 0.5–3) on the 30th day and 2 (limits 1–3) on the 45th day); 2) reduced percentage of time and entries in the open arms and in serum corticosterone levels; 3) totally exposed dentinal tubules on the 30th day in SEM analysis of the teeth; and 4) no alterations in the anatomopathological and histological evaluations.

Conclusions

The treatment with isotonic solution for 30 days was able to induce DH after erosive challenge and severe DH was observed after isotonic solution treatment for 45 days. The pain induced by cold stimuli was consistent with the grade of DH. The close relationships between dental erosion, response to pain, serum levels of corticosterone and the EPM behavior responses reveal the effects of DH at several levels.     

Effects ofin Planta gamma-irradiation on growth, photosynthesis, and antioxidative capacity of red pepper (Capsicum annuum L.) plants

We investigated the effects of low-dose inplanta irradiation on red pepper plants treated with gamma rays of 2, 4, 8, and 16 Gy. Growth was stimulated at 2 and 4 Gy but inhibited at 8 and 16 Gy. Photochemical quenching (qP) increased slightly in all treatment groups for 1 d after irradiation (DAl), whereas non-photochemical quenching (NPQ) decreased more noticeably. These changes in qP and NPQ were transient and had almost recovered to the control level by 2 DAl. Although carotenoid pigments also fluctuated during the experimental period, chlorophylls were almost entirely insensitive to the gamma rays. Irradiation also partially protected leaves from a decrease in photochemical efficiency (Fv/Fm) under conditions of UV-B (2.2 W m^-2) and high light intensity (800 μmol m^-2 s^-1). This enhanced stress resistance could be partly explained by higher levels of SOD and APX activities, as well as ascorbate content. Our results demonstrate for the first time that the carotenoid pigments are the most radio-sensitive and fastest recovering compounds in plants, and that SOD, APX, and ascorbate are important inducible factors for improving stress resistance through the use ofin planta gamma-irradiation.     

Decay of γ-H2AX foci correlates with potentially lethal damage repair and P53 status in human colorectal carcinoma cells

The influence of p53 status on potentially lethal damage repair (PLDR) and DNA double-strand break (DSB) repair was studied in two isogenic human colorectal carcinoma cell lines: RKO (p53 wild-type) and RC10.1 (p53 null). They were treated with different doses of ionizing radiation, and survival and the induction of DNA-DSB were studied. PLDR was determined by using clonogenic assays and then comparing the survival of cells plated immediately with the survival of cells plated 24 h after irradiation. Doses varied from 0 to 8 Gy. Survival curves were analyzed using the linear-quadratic formula: S(D)/S(0) = exp-(αD+βD²). The γ-H2AX foci assay was used to study DNA DSB kinetics. Cells were irradiated with single doses of 0, 0.5, 1 and 2 Gy. Foci levels were studied in non-irradiated control cells and 30 min and 24 h after irradiation. Irradiation was performed with gamma rays from a ¹³⁷Cs source, with a dose rate of 0.5 Gy/min. The RKO cells show higher survival rates after delayed plating than after immediate plating, while no such difference was found for the RC10.1 cells. Functional p53 seems to be a relevant characteristic regarding PLDR for cell survival. Decay of γ-H2AX foci after exposure to ionizing radiation is associated with DSB repair. More residual foci are observed in RC10.1 than in RKO, indicating that decay of γ-H2AX foci correlates with p53 functionality and PLDR in RKO cells.     

Asymmetric somatic hybrids between Lycopersicon esculentum and irradiated Lycopersicon peruvianum

Summary Asymmetric somatic hybrids of Lycopersicon esculentum and Lycopersicon peruvianum were obtained by fusion of leaf protoplasts from both species after irradiation of protoplasts or leaf tissue of L. peruvianum with 50, 300, or 1,000 Gy of gamma-rays. These radiation doses were sufficient to abolish the growth of the L. peruvianum protoplasts. The hybrids were selected for their ability to regenerate plants; this regeneration capacity derived from L. peruvianum. All asymmetric hybrid plants were aneuploid. The ploidy level, the morphology, and the regeneration rate were analyzed in relation to the radiation dose applied to L. peruvianum. After a low dose (50 Gy), most hybrids had near-triploid chromosome numbers, whereas after a high dose (300 or 1,000 Gy), most hybrids had near-pentaploid numbers. The morphology of the asymmetric hybrids was intermediate between that of L. esculentum and symmetric somatic hybrids of both species (obtained without irradiation treatment), and approached the morphology of L. esculentum to a greater extent after a high dose of irradiation. The asymmetric hybrids regenerated more slowly than the symmetric hybrids and regeneration proceeded more slowly after a high dose than after a low dose of irradiation. The high-dose hybrids also grew more slowly, flowered less, and set fruits less than the low-dose hybrids. No seeds could be obtained from any asymmetric hybrid.     

Effect of long-term exposure to low dose gamma-irradiation on the rat thyroid status

The effect of long-term exposure to low-dose external radiation on the rat thyroid status was studied. The experiments were carried out on Wistar female rats. The single doses absorbed were 0.1; 0.25; 0.5 Gy. The rats were irradiated 20 times (5 days x 4 weeks). The animals were decapitated after 1, 30 and 180 days following the last irradiation. Blood serum was assayed for content of thyroxin (T4) and triiodothyronine (T3) radioimmunologically. The liver was spectrophotometrically assayed for thyroid-induced NADP-malatedehydrogenase (NADP-MDH). It was shown that the long-term 0.5-Gy irradiation of the animals induced a decrease in blood T4 and T3 concentrations 1.34-1.71-fold and 1.24-1.43-fold after 1, 30 and 180 days, respectively. The T3 level was diminished most pronouncedly after 1 day, whereas that of T4--after 30 days following the exposure. With the doses of 0.1 and 0.25 Gy absorbed, the T4 and T3 concentration remained unchanged throughout all the periods studied. The activity of NADP-MDH was decreased 1.55-2.46-fold in all the experimental animals, and it was held decreased after 180 days (1.43-1.50-fold) in 0.25- and 0.5-Gy-irradiated groups, which indicates a disturbance in thyroid hormone metabolism in rats exposed chronically to low-dose radiation. After 180 days, the experimental animals experienced an elevation of thyroid gland weight on 15-20%. The thyroid status disturbance seemed to be due to both inhibited T4 and T3 biosynthesis in thyroid and disturbed hormone peripheral metabolism under radiation exposure.     

Dominant lethal effect of 60Co gamma radiation in Biomphalaria glabrata (SAY, 1818)

The dominant lethal effects of gamma radiation of 60Co in the snail Biomphalaria glabrata were studied. Three groups of 13 wild-type snails were irradiated with single doses of 2.5; 10 and 20 Gy. Crossings were carried out at intervals of 7, 17, 23, 30 and 36 days after irradiation. The dominant lethal effect was observed only at the first crossing occurring 7 days after irradiation with 2.5 Gy. With 10 and 20 Gy, the induction of lethal mutations was detected at 7, 17 and 23 days after irradiation; a dose-response effect was observed. The effect was stronger 7 days after irradiation, decreasing in the succeeding crossings up to 30 days. Cell-killing effects on germ cells were detected in the crossings at 23 days and 30 days after irradiation with 20 Gy. After 36 days, frequencies of malformations resumed background levels; crossing rates partially recovered. These results show that gamma radiation affected all the stages of spermatogenesis. Germ cells at later phases were more sensitive to the mutagenic effect of radiation and the cell killing effects were observed on the youngest cells. This response was similar to the highly homogeneous pattern observed in widely different species and allowed us to estimate some parameters of spermatogenesis in B. glabrata.