Changes in levels of p53 protein, immunoglobulin L-chains, and iron complexes in mice of leukosis strain AKR following low dose irradiation

Changes in the content of protein p53 (regulator of the cell cycle) L-chains of immunoglobulins, and iron complexes (Fe2+) during the development of spontaneous leukosis in AKR mice and upon irradiation of animals with a dose of 1.2 cGy were studied by ESR spectroscopy, electrophoresis, and immunoblotting. It was found that irradiation leads to an increase in the incidence of leukoses in males by 7% and a decrease in life duration of females. A decrease in the content of protein p53 and L-chains in immunoglobulins in males and females was observed; however, in females, the decreases was less pronounced because the content of these proteins in females is naturally decreased. In mice irradiated with low doses at the age of three- to four months, a decrease in the amount of iron complexes at a later age (seven- to eight months) was registered. These data suggest that there is a relationship between the induction of protein p53 and the content of immunoglobulin L-chains in the blood serum of animals.     

Irradiation of Anastrepha obliqua (Diptera: Tephritidae) revisited: optimizing sterility induction

The effects of irradiation doses increasing from 0 to 100 Gy (1 Gy is energy absorbed in J kg(-1) of irradiated material) on fertility, flight ability, survival, and sterile male mating performance were evaluated for mass-reared Anastrepha obliqua (Macquart). High sterility values (> 98.2%) for irradiated males were obtained for doses as low as 25 Gy. Egg hatch was inhibited for irradiated males crossed with irradiated females at a low dose of 20 Gy. However, we estimated that to achieve 99.9% sterility (standard goal of many sterile insect technique programs), irradiation doses had to be increased to a dose between 50 and 75 Gy. At doses of 25 Gy and greater, we observed a decreasing trend in adult flight ability and an increasing trend in adult mortality. Such differences were greater for pupae irradiated at a young age compared those irradiated 24 h before emergence. Our single most relevant finding was that sterility induction (i.e., oviposition of nonfertilized eggs) was two times greater for males irradiated at low doses (40 Gy) than for males irradiated at high doses (80 Gy) when used at a 3:1:1 sterilized male to fertile male to fertile female ratio. Males irradiated at high doses may have been outcompeted by unirradiated males when courting unirradiated females. Implications of our findings for sterile insect technique programs are discussed.     

Comparison of cytogenic response of human lymphocytes to in vivo and in vitro exposure to low doses of gamma-rays. Unstable chromosomal exchanges detected by FPG techniques

On peripheral lymphocytes of eight cancer patients undergone whole-body therapeutic irradiation (at daily dose of 10 cGy up to total dose of 50 cGy of 60Co gamma-rays) the dose-response of unstable chromosome exchanges (dicentrics and centric rings) was studied. This dose response fitted well linear function. The lower slope of dose-response curve was found for in vivo irradiated lymphocytes as compared to the dose response curve obtained for in vitro irradiated lymphocytes of the same patients. This finding seems to provide evidence that in case of protracted irradiation of individuals an absorbed dose could be underestimated if for biological dosimetry an in vitro dose response curve for unstable chromosome aberrations is used as referent one.     

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.     

Sterility and Sexual Competitiveness of Tapachula-7 Anastrepha ludens Males Irradiated at Different Doses

A genetic sexing strain of Anastrepha ludens (Loew), Tapachula-7, was developed by the Mexican Program Against Fruit Flies to produce and release only males in programs where the sterile insect technique (SIT) is applied. Currently, breeding are found at a massive scale, and it is necessary to determine the optimum irradiation dose that releases sterile males with minimum damage to their sexual competitiveness. Under laboratory and field conditions, we evaluated the effects of gamma irradiation at doses of 0, 20, 40, 60 and 80 Gy on the sexual competitiveness of males, the induction of sterility in wild females and offspring survivorship. The results of the study indicate that irradiation doses have a significant effect on the sexual behavior of males. A reduction of mating capacity was inversely proportional to the irradiation dose of males. It is estimated that a dose of 60 Gy can induce more than 99% sterility in wild females. In all treatments, the degree of offspring fertility was correlated with the irradiation dose of the parents. In conclusion, the results of the study indicate that a dose of 60 Gy can be applied in sterile insect technique release programs. The application of this dose in the new genetic sexing strain of A. ludens is discussed.     

Evaluation of partial sterility in mating performance and reproduction of the West Indian sweetpotato weevil,Euscepes postfasciatus

The sterile insect technique (SIT) is based on population and behavioral ecology and is widely used to suppress or eradicate target pest insect populations. The effectiveness of SIT depends on the ability of the released sterile males to mate with and inseminate wild females. The use of gamma‐radiation to induce sterility is, however, associated with negative impacts not only on reproductive cells but also on somatic cells. Consequently, irradiation for sterilization diminishes mating performance over time. In this study, we evaluated the balance between the irradiation dose and both fertility and mating propensity in Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) for 22 days following irradiation. The mating propensity of males irradiated with a 150‐Gy dose, as currently used to induce complete sterility of E. postfasciatus in the SIT program in Okinawa Prefecture, was equal to that of non‐irradiated weevils for up to 6 days, and the mating propensity of males irradiated with a dose of 125 Gy was equal to that of non‐irradiated weevils for twice this period (12 days). The fertilization ability of weevils irradiated with a dose of 125 Gy was reduced by 4.6% in males and 0.6% in females, compared to the potential fertilization ability. We also discuss the possibility of the application of partially sterilized insects in eradication programs.     

Genetic efficacy of low doses of ionizing radiation in chronically-irradiated small mammals

Earlier we have established the genetic effects of low dose chronic irradiation in bank vole (somatic and germ cells, embryos), in pond carp (fertilized eggs, embryos, fry) and in laboratory mice (somatic and germ cells) in the range of doses from near-background to 10 cGy. These low dose effects observed in mammals and fish are not expected from extrapolation of high dose experiments. For understanding reasons this discrepancy the comparative analysis of genetic efficiency of low dose chronic irradiation and the higher doses of acute irradiation was carried out with natural populations of bank vole which inhabited the two sites differing in ground of radionuclide deposition. For comparing efficiency the linear regression model of dose-effect curve was used. Dose-effect equations were obtained for animals from two chronically irradiated bank vole populations. The mean population absorbed doses were in the range 0.04-0.68 cGy, the main part of absorbed doses consisted of external radiation of animals exposed to 137Cs gamma-rays. Dose-effect equations for acute irradiation to 137Cs gamma-rays (10-100 cGy) were determined for the same populations. Comparison of genetic efficiency was made by extrapolation, using regression coefficient beta and doubling dose estimation. For chronic exposure the doubling doses calculated from low-dose experiments are 0.1-2 cGy and the doubling doses determined from high-dose experiments are in the range of 5-20 cGy. Our hypothesis that the doubling dose estimate is calculated in higher-dose ionizing radiation experiments should be much higher than the deduced from the low dose line regression equation was verified. The doubling dose estimates for somatic cells of bank vole and those for germ cells of laboratory mice are in close agreement. The radiosensitivity of bank vole chromosomes were shown is practically the same as that for human lymphocytes since doubling dose estimates for acute irradiation close to each other. For low LET radiation a higher genetic efficiency of chronic low doses in comparison with the higher doses of acute gamma-irradiation (137Cs source) was proved by three methods.     

Effect of irradiation on mating ability in the male sweetpotato weevil (Coleoptera: Curculionidae)

The sterile insect technique (SIT) is widely used for suppressing or eradicating target pest insect populations. The effectiveness of SIT depends on the ability of released sterile males to mate with and inseminate wild females. Irradiation is the effective manner to sterilize mass-reared insects. The negative impacts of this procedure are not limited to damage on reproductive cells. Gamma-radiation damages the epithelial tissue of midgut, which affects the alimentation in insects. Irradiated males alter their mating behavior over time because of the depression of metabolic activity by sterilization. In this study, we evaluated the male mating performance and sexually compatibility of irradiated male Cylas formicarius elegantulus (Summers) (Coleoptera: Curculionidae) with a 200-Gy dose, as currently used in the SIT program in Okinawa Prefecture, throughout 16 d after irradiation in the laboratory. The mating ability of irradiated males did not differ from that of control males for about a week. However, the mating ability of irradiated male drastically decreased thereafter. We consider that irradiated male C. formicarius elegantulus with a 200-Gy dose had no major effect on male mating behavior approximately for a week after irradiation.     

Effects of gamma radiation on the reproduction biology and mating competitiveness of citrus leafminer Phyllocnistis citrella Stainton

The citrus leafminer (CLM), Phyllocnistis citrella Stainton, is one of the most serious pests of Iran's citrus nursery stocks. In this study, the effects of gamma radiation at doses of 100–450?Gy on the biological and reproductive parameters of P. citrella were determined. The results showed that the mean percentage of pupal mortality increases with a rise in the dose. Also, the mean values of this parameter were higher for irradiated females, indicating higher sensitivity. The mean fertility of the irradiated females mated with normal males was affected drastically and reached zero at 300?Gy. The hatchability of the eggs laid by normal females mated with irradiated males dropped to 2% at the highest irradiation dose of 450?Gy. The results of this test showed that females have a higher radio-sensitivity than males. The competitiveness values fluctuated from 0.2 to 0.6 at doses higher than 200?Gy. The results showed that the male CLMs irradiated with sterilizing doses could compete suitably with the untreated males in laboratory conditions.     

Genetic effects in the liquidators of consequences of Chernobyl Nuclear Power Plant accident

The purpose of the present research was the estimation of probable genetic consequences at the liquidators of the consequences of Chernobyl accident in 1986-1987. The research is made on two groups of the liquidators. The first group included the liquidators taking place on the account in the branch register and working now at the enterprises of a nuclear industry. The second group included 902 liquidators of consequences of Chernobyl accident in 1986 constantly living in the Ryazan area and which are taking place on permanent observation the account in regional hospital. For an estimation of probable genetic effects analyzed the data on frequency and outcomes pregnancy of the wives of the liquidators, on condition and on diseases of newborn, on switching intrauterine development defects (IDD). The analysis carried out depending on dozes of an irradiation: up to 5 cGy; 5-10 cGy and 10-25 cGy. Received materials testify, that at the liquidators, at a doze of an external irradiation 10-25 cGy, the determined effects--period long sterility, kept at a part them till 3 years come to light. The set of the received data, such as depending from the dose increase of frequency of spontaneous abortions and of inherent defects of development of newborn, the increase of frequency diseases of newborn and share newborn with low weight, allows to make a conclusion about an induction of genetic effects in sexual cells of the liquidators of consequences of Chernobyl accident at dozes of an external irradiation more than 10 cGy. Taking into account high biological efficiency of alpha-radiation (K = 20), and of beta-radiation (K = 2-4), the equivalent effective doze male gonads (testes) in 3-5 times is higher, than estimated only from external gamma-radiation.     

Development of genetic instability in mice in response to chronic irradiation simulating high-altitude flight conditions

The purpose of this work was to study the chronic influence of the high-energy radiation field formed in the atmosphere at an altitude of 10 to 30 km on the level of DNA damage in leukocytes of peripheral blood in mice. The external radiation field (behind the concrete shield) of the U-70 accelerator (Serpukhov, Russia) was used for these studies. This radiation field simulates the components and spectral composition of the high-energy radiation field formed in the atmosphere at an altitude of 10 to 30 km. Two groups of SHK line mice were chronically irradiated with a total dose equivalent to 21.5 and 31.5 cGy. The state of the genome of nucleated blood cells was assessed by the Comet assay (alkaline version) 72 h after completion of chronic irradiation. The level of genome damage in individual peripheral blood leukocytes of irradiated animals was compared with the basal level of DNA lesions in peripheral blood leukocytes of unirradiated control mice. The damage was expressed in %TDNA (the amount of DNA found in the "comet tail" in percent of total DNA in the "comet"). It was found that in mice exposed to the radiation field of the accelerator, the mean value of DNA damage was: %TDNA = 3.88 +/- 0.35% for a dose of 21.5 cGy and % TDNA = 6.00 +/- 0.82% for a dose of 31.5 cGy. In mice irradiated at an X-ray therapeutic device with a dose of 150 cGy 24 h before the examination, %TDNA was 2.27 +/- 0.34% and this did not differ from %TDNA in unirradiated mice, 2.68 +/- 0.56%. We suggest that the increased level of DNA damage observed in mice irradiated with 31.5 cGy from the mixed radiation field at the Serpukhov accelerator points to the development of genetic instability in their leukocytes as a result of chronic exposure of animals to this particular radiation field.     

Lack of sexual experience does not reduce the responses of LH, estrus or fertility in anestrous goats exposed to sexually active males

We investigated whether LH secretion, estrous behavior and fertility would differ between sexually inexperienced and experienced anestrous goats exposed to the males. Male goats were rendered sexually active during the reproductive rest season by exposure to 2.5 months of artificial long days. Two groups of anovulatory sexually inexperienced and sexually experienced does were exposed to males during 15 days (n = 20 per group). LH pulsatility was determined every 15 min from 4 h before to 8 h after introducing males (Day 0). Estrous behavior was recorded twice daily. Pregnancy rates were determined on Day 50. Fertility was determined at parturition. Male sexual behavior was registered on days 1 and 2 during 1 h. Before introducing the males, the number of LH pulses did not differ between groups. After introduction of the males, all females increased their LH pulsatility, but the number of pulses did not differ between sexually inexperienced and experienced goats. The proportion of females displaying estrous behavior with a high pregnancy rate and fertility did not differ between inexperienced and experienced goats. The sexual behavior of the males did not differ significantly between those interacting with sexually inexperienced or experienced goats. We conclude that goats can show substantial endocrine and reproductive responses to males, even in the absence of previous sexual experience, when sexually active bucks are used.     

Effects of gamma radiation on spermatophore production and reception and subsequent fecundity and egg viability inAcarus siro L. (Acari: Acaridae)

Gamma radiation at doses higher than 10 krad significantly lowered the fecundity of the grain mite,Acarus siro. The fecundity of irradiated females was inversely correlated with dose, both when control or irradiated males were used in the pairing.Irradiation with ionizing radiation affected sexual activity of males. At doses above 10 krad the number of formed or observed spermatophores was lowered significantly.Sexual attractiveness of irradiated and control females to irradiated males was similar. However, non-irradiated males were observed mating more often with non-irradiated than with irradiated females.No correlation was found between the numbers of spermatophores present in the spermathecae of the female and the fecundity of the female. Irradiation had a greater effect on fecundity of the female than on sexual activity of the male; it did not affect the shape or behavior of spermatophores in the spermathecae of the female.Viability of eggs laid by females decreased by at least 50% when females or males were irradiated with doses above 20 krad. Irradiation also affected the survival of adults, but females were more sensitive than males. Net sterility index indicates that doses higher than 20 krad induce more than 90% sterility.     

Comparison of cytogenetic response of human lymphocytes to in vivo and in vitro exposure to low-dose gamma rays. Translocations and dicentrics detected by the FISH technique

On peripheral lymphocytes of 5 cancer patients undergone wholebody therapeutic irradiation (at daily dose of 10 cGy up to total dose 50 cGy of 60Co gamma-rays) the dose response of unstable and stable chromosomal exchanges detected by FISH was compared with the dose response of the some aberrations in lymphocytes irradiated in vitro. The dose response fitted well to linear function. For dicentrics the lower slope of dose-response curve was found for in vivo irradiated lymphocytes as compared to the dose-response curve obtained for in vitro irradiated lymphocytes of the same patients. No difference between in vivo and in vitro irradiation of lymphocytes was found for translocations. The frequency of translocations increased faster with the dose than the frequency of dicentrics only in lymphocytes irradiated in vivo.     

Effect of irradiation on Mexican leafroller (Lepidoptera: Tortricidae) development and reproduction

The effects of irradiation on egg, larval, and pupal development, and adult reproduction in Mexican leafroller, Amorbia emigratella Busck (Lepidoptera: Tortricidae), were examined. Eggs, neonates, early instars, late instars, early pupae, and late pupae were irradiated at target doses of 60, 90, 120, or 150 Gy, or they were left untreated as controls in replicated factorial experiments. Survival to the adult stage was recorded. Tolerance to radiation increased with increasing age and developmental stage. A radiation dose of 90 Gy applied to neonates and early instars prevented adult emergence. A dose of 150 Gy was not sufficient to prevent adult emergence in late instars or pupae. The effect of irradiation on sterility was examined in late pupae and adult moths. For progeny produced by insects treated as late pupae, a total of three out of 3,130 eggs hatched at 90 Gy, 0 out of 2,900 eggs hatched at 120 Gy, and 0 out of 1,700 eggs hatched at 150 Gy. From regression analysis, the dose predicted to prevent egg hatch from the progeny of irradiated late pupae was 120 Gy, with a 95% confidence interval of 101-149 Gy. The late pupa is the most radiotolerant stage likely to occur with exported commodities; therefore, a minimum absorbed radiation dose of 149 Gy (nominally 150 Gy) has potential as a quarantine treatment. Reciprocal crosses between irradiated and unirradiated moths demonstrated that males were more radiotolerant than females. Irradiation of female moths at a target dose of 90 Gy before pairing and mating with irradiated or unirradiated males resulted in no viable eggs, whereas irradiated males paired with unirradiated females produced viable eggs at 90 and 150 Gy.     

Radiation biology and inherited sterility of light brown apple moth (Lepidoptera: Tortricidae): developing a sterile insect release program

The radiation biology of two geographically isolated populations of the light brown apple moth [Epiphyas postvittana (Walker)] was studied in Australia and New Zealand as an initiation of a SIT/F1 sterility program. Pharate and < or = 2 d pre-emergence pupae were exposed to increasing radiation doses up to a maximum dose of 300 Gy. Fertility and other life history parameters were measured in emerging adults (parental) and their progeny (F1-F3 adults). Parental fecundity was significantly affected by increasing irradiation dose in pharate pupae only. For both populations, parental egg fertility declined with increasing radiation. This was most pronounced for the irradiated parental females whose fertility declined at a higher rate than of irradiated males. At 250 Gy, females < or = 2 d preemergence pupae produced few larvae and no adults at F1. No larvae hatched from 250 Gy-irradiated female pharate pupae. At 300 Gy, males still had residual fertility of 2-5.5%, with pharate pupae being the more radio-sensitive. Radiation-induced deleterious inherited effects in offspring from irradiated males were expressed as increased developmental time in F1 larvae, a reduction in percent F1 female survival, decreased adult emergence and increased cumulative mortality over subsequent generations. Males irradiated at > or = 150 Gy produced few but highly sterile offspring at F1 and mortality was > 99% by F2 egg.     

The action of low doses of gamma radiation on mammalian cells]

Effect of gamma irradiation in low doses (10, 20, 40 and 50 cGy) on HeLa cells was studied. The survival of cells exposed to the irradiation in the dose of 50 cGy was decreased while it remained unchanged in cells irradiated in the dose of 10-40 cGy and their descendants. Nonetheless, their survival following an additional treatment with a mixture of cytosine arabinoside and hydroxyurea was reduced. It was suggested that the genome stability was diminished in irradiated cells and their descendants.     

Dose-response modeling of life shortening in a retrospective analysis of the combined data from the JANUS program at Argonne National Laboratory

Life shortening was investigated in both sexes of the B6CF1 (C57BL/6 x BALB/c) mouse exposed to fission neutrons and 60Co gamma rays. Three basic exposure patterns for both neutrons and gamma rays were compared: single exposures, 24 equal once-weekly exposures, and 60 equal once-weekly exposures. Ten different dose-response models were fitted to the data for animals exposed to neutrons. The response variable used for all dose-response modeling was mean after-survival. A simple linear model adequately described the response to neutrons for females and males at doses less than or equal to 80 cGy. At higher neutron dose levels a linear-quadratic equation was required to describe the life-shortening response. An effect of exposure pattern was observed prior to the detection of curvature in the dose response for neutrons and emerged as a potentially significant factor at neutron doses in the range of 40-60 cGy. Augmentation of neutron injury with dose protraction was observed in both sexes and began at doses as low as 60 cGy. The life-shortening response for all animals exposed to gamma rays (22-1918 cGy) was linear and inversely dependent upon the protraction period (1 day, 24 weeks, 60 weeks). Depending on the exposure pattern used for the gamma-ray baseline, relative biological effectiveness (RBE) values ranged from 6 to 43. Augmentation, because it occurred only at higher levels of neutron exposure, had no influence on the estimation of RBEm.     

The cytogenetic indication of irradiation in persons exposed to the action of the factors in the Chernobyl accident]

363 men who have been working under conditions of additional irradiation in terms from few hours to some months were cytogenetically examined to define individual irradiation. In 111 men with the known dose of irradiation (5-140 cGy), the results of cytogenetic evaluation indicated, as a rule, a less intensive irradiation than physical dosimetry. This could be caused by elimination of chromosome aberrations, individual sensitivity, peculiar irradiation situation, or in some cases by incorrect evaluation of dose. In 252 men with the unknown dose of irradiation a tentative level was determined as based on frequency of metaphases with chromosome type aberrations. According to the study the absorbed dose was below 25 cGy in 209 cases, 26-50 cGy in 39 cases, and reached 51-90 cGy in 4 cases.     

Assessment of effect of partial sterility on mating performance in sweetpotato weevil (Coleoptera: Curculionidae)

The sterile insect technique (SIT) is widely used to suppress or eradicate target pest insect populations. Although the effectiveness of SIT depends on the ability of released sterile males to mate with and inseminate wild females, the use of gamma radiation to induce sterility negatively impacts reproductive cells as well as somatic cells. Consequently, sterilization by irradiation drastically diminishes mating performance over time. In the current study, we evaluated the effect of irradiation dose intensity on fertility, mating propensity, and mating competitiveness in sweetpotato weevil, Cylas formicarius elegantulus (Summers) (Coleoptera: Curculionidae), for 16 d after irradiation. Although the mating propensity of males irradiated with 200 Gy, the dose currently used to induce complete sterility of C. f. elegantulus in the SIT program in Okinawa Prefecture, was equal to that of nonirradiated weevils for the first 6 d, the mating propensity of males irradiated with doses between of 75 and 150 Gy was maintained for the first 12 d. The potential fertilization ability of weevils was highly depressed compared with the control weevils, even in those treated with 75 Gy. Mating performance was severely compromised in weevils that were irradiated with a dose of 100 Gy or more. These results demonstrate that partial sterilization can be highly advantageous in eradication programs for the sweetpotato weevil. We discuss the advantages of the application of partial irradiation in insect eradication programs.