Non-irradiated Females Research Articles

Gamma-Irradiated Female Aedes aegypti Mosquitoes Exhibit Greater Susceptibility to Mayaro Virus.

Mayaro virus (MAYV) is an alphavirus endemic in many parts of Central and South America transmitted to humans by Aedes aegypti. Currently, there is no vaccine or treatment of Mayaro infection, and therefore it is essential to control transmission by reducing populations of Ae. aegypti. Unfortunately, Ae. aegypti are extremely difficult to control with traditional integrated vector management (IVM) because of factors such as growing resistance to a dwindling list of registered insecticides and cryptic immature and adult habitats. The sterile insect technique (SIT) by irradiation is gaining traction as a novel supplemental tool to IVM. The SIT is being used operationally to release large numbers of sterilized colony-reared male mosquitoes in an intervention area to overwhelm females in the natural population, eventually causing population decline because of high frequencies of unfertilized eggs. However, little is known about the effect of irradiation on vector competence for mosquito-borne viruses such as MAYV in females that may be accidentally reared, irradiated, and released alongside males. In this investigation, we exposed female Ae. aegypti pupae to radiation and evaluated vector competence after inoculation with MAYV. Infection and dissemination rates of irradiated (10 and 40 Gy) Ae. aegypti were higher than those of non-irradiated cohorts at 7 and 14 days after infection. Although these results indicate a need to maintain effective sex sorting prior to irradiation and release of Ae. aegypti, our results are consistent with several previous observations that vectorial capacity and vector competence are likely lower in irradiated than in nonirradiated females.

Rearing and 60Co radiation do not affect attractiveness but alter the volatile profiles released by Anastrepha obliqua calling males.

Calling males of Anastrepha obliqua release volatile compounds to attract conspecific males to form leks and females to mate. Male volatiles from Mexican and Brazilian populations of A. obliqua have been previously identified. However, there are differences in the number and identity of volatile compounds between the populations. These differences in volatile profiles may be due to male origin (e.g. wild or mass-reared flies) or methodological issues (e.g. sampling techniques). In this study, we evaluated the attractiveness of wild, laboratory non-irradiated, and laboratory-irradiated flies under semi-field conditions. Male volatiles were collected using dynamic headspace sampling (DHS) and solid-phase microextraction (SPME) techniques, and identified using gas chromatography-coupled mass spectrometry. The results showed no difference in the attractiveness of wild, laboratory non-irradiated, and irradiated males to females. However, the number of captured females differed according to the origin; wild and non-irradiated females were captured more frequently than the irradiated flies. A total of 21 compounds were found using SPME, whereas only 12 were collected using DHS, although the relative amounts of these compounds were higher than those obtained using the former sampling technique. In addition, only laboratory non-irradiated males released α-pinene and menthol, which have not been previously reported in this fruit fly species. Additionally, we identified novel compounds in A. obliqua; however, certain compounds previously reported were not detected. This study suggests that despite the qualitative and quantitative variations in the volatile profiles of A. obliqua males, their attractiveness was unaffected.

Assessment of combining biosynthesized silver nanoparticles using Bacillus thuringiensis and gamma irradiation for controlling Pectinophora gossypiella (saunders) (lepidoptera: Gelechiidae)

Purpose Combining gamma irradiation and nanotechnology has become one of the most promising new approaches for area-wide (AW) pest management in recent years. The laboratory trials were conducted to determine the combining effects of BT-AgNPs and gamma irradiation for controlling P. gossypiella. Radio-sensitivity of male pupae at different doses of gamma radiation and the effectiveness of biosynthesized silver nanoparticles using Bacillus thuringiensis on larval instar were assayed. Additionally, the ultrastructure changes on the alimentary canal of 4th instar larvae were studied to evaluate the impact of the combined approach at a cellular level. Materials and methods Laboratory- rearing technique was used for rearing Pectinophora gossypiella. The irradiation process was achieved at Co60 - Gamma Chamber (4000 A). Alanine dosimeters were used for measuring the average absorbed dose and dose mapping. Preparation of Silver nanoparticles (AgNPs) using Bacillus thuringiensis (Bt) and their characterization has been investigated. The treated 4th instar larvae by gamma irradiation or ∕and BT-AgNPs were dissected under the stereo microscope. The alimentary canal was obtained anatomically and Transmission Electron Microscope) was used in examining the stained sections. Results Based on the nonhatching eggs produced by irradiated males’ pupae, the values of effective doses were calculated. The effective doses ranged from 16 to 291 Gy for the ED25 - ED75. The sterility index reached 74.1% when irradiated with males by 291 Gy crossed with nonirradiated females and the adult emergence decreased to be 35.3%. The insecticidal potential of Bt-AgNPs on the 2nd and 4th larval instars was dose-dependent and its LC50 toxicity value was 0. 3 and 0. 4 mg/ml, respectively. The lethal concentration LC50 of the 2nd instar larvae increased the larval and pupal mortality to 55% and 44.4%, respectively, and reduced the adult emergence to be 55.6%. The combining effects of Bt-AgNPs with 291 Gy induced 100% pupae mortality and there was no adult emergence in F1 generation. Such effects also severed the ultrastructure deformity of the midgut of the 4th instar larvae after the two-day post-treatment. Conclusions The combining effects are recommended as an effective IPM program to control P. gossypiella by releasing sterile males (derived from pupae irradiated with 291 Gy) crossing with the normal females in the field, and reducing the fertility of the population to 31.2%. Subsequently, the resulted larvae treated with LC50 of Bt-AgNPs prevented the adult emergence and stopped the life cycle of P. gossypiella.

Evaluating Flight Performance of Mass-Reared and Irradiated Navel Orangeworm (Lepidoptera: Pyralidae) for Sterile Insect Technique.

Navel orangeworm (Pyralidae: Amyelois transitella) is a key pest of almonds and pistachios in California. Moths directly infest nuts which leads to reduced crop yield and quality, and infestation can predispose nuts to fungal pathogens that produce aflatoxins. While several integrated pest management strategies have been developed for A. transitella, studies have recently been initiated to explore the use of sterile insect technique (SIT) as an additional control tool. Mass-rearing, sterilization, and transportation methods originally developed for Pectinophora gossypiella (Lepidoptera: Gelechiidae) are currently being used for production of A. transitella in a mass-rearing facility, but the impacts of these processes on performance of A. transitella remain unclear. In this study, computerized flight mills were used to evaluate multiple flight parameters of mass-reared and irradiated A. transitella males and females relative to non-irradiated mass-reared moths and two strains of locally reared moths which were neither mass-reared nor irradiated. Mass-reared non-irradiated females performed similarly to both strains of locally reared females, flying a mean 9.4-11.8 km per night, whereas mass-reared and irradiated males and mass-reared non-irradiated males all flew shorter distances, in the range of 3.0-6.7 km per night. All of the mass-reared moths compared to locally reared moths had significantly more non-fliers that did not engage in more than two minutes of continuous flight. Findings from this study suggest that mass-rearing conditions reduce A. transitella flight capacity, while irradiation interacts with moths in a sex-specific manner.

Assessment of mating competitiveness of sterile Ceratitis capitata in laboratory and field cage tests in northern Iran

AbstractIn recent years, damage by Mediterranean fruit fly (medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) on commercial fruit crops has reached a critical point in Iran. The sterile insect technique is considered the most effective strategy for the area‐wide suppression or eradication of tephritid fruit flies, particularly the medfly. In this study, an area of citrus trees, including 39 field cages in Sari‐Mazandaran province, was used for an experiment to test various irradiation doses and overflowing ratios on male competitiveness‐induced sterility. Treatments 1 and 2 consisted of non‐irradiated females (NF), non‐irradiated males (NM), and irradiated males (IM) which emerged from pupae irradiated with 80 or 100 Gy. The IM:NM:NF ratios per field cage were varied as follows: 0:1:1, 1:0:1, 1:1:1, 3:1:1, 5:1:1, 10:1:1, and 15:1:1. We found that the mating rate of NF copulating with IM was significantly lower than that of NF mated with NM. The numbers of eggs and the percentages of egg hatching were significantly lower in IM × NF than in NM × NF crosses, and no eggs hatched in the 80–130 Gy dose range. The results of Fried's CV (male mating competitiveness value based on egg hatch) ranged from 0.41 to 0.78 at a dose of 80 Gy and from 0.35 to 0.63 at 100 Gy for various mating rates. It can be concluded that IM was fully competitive with NM at the dose range of 80–100 Gy of gamma radiation.

Influence of Irradiation on the Biology of the Brown Marmorated Stink Bug (Hemiptera: Pentatomidae).

Fifth-instar brown marmorated stink bug (Halyomorpha halys Stål) nymphs were treated by gamma-radiation 60Co at different doses of 8-64 Gy to investigate their irradiation biology and potential for the sterile insect technique (SIT). At adult emergence, males were mated with non-irradiated virgin females to assess the longevity of both sexes, female fecundity, and egg sterility. Biological parameters of their F1 progeny were investigated to determine whether negative effects from parental exposure to radiation were inherited. Results showed that irradiation significantly reduced the lifespan of male insects at doses above 20 Gy. Irradiated males did not affect the longevity and fecundity of their female partners, nor of their resulting adult progenies, but it did reduce the developmental duration of nymphs as well as weight gain of male F1 offspring. Egg hatch was significantly reduced at all tested doses and reached complete sterility at 64 Gy. Low hatch of eggs produced by F1 or F1 crossed adults indicated that negative effects from radiation were inherited by the subsequent generation. But F1 male offspring were not less fertile than their irradiated male parent, unlike what was observed in Lepidoptera. The results support the potential for the use of SIT for H. halys management by irradiating the fifth-instar male nymphs at doses from 16 Gy to 64 Gy.

Egg Sterilisation of Irradiated Nezara viridula (Hemiptera: Pentatomidae).

Simple SummaryCertain stink bugs are emerging as a serious threat to food production globally, as they invade new areas and feed on a wide range of crops. The control of these pests relies primarily on potentially harmful pesticides, but the increasing threat posed by stink bug pests has sparked investigation into environmentally-friendly methods that do not exert serious impacts on other species. One method receiving attention is the Sterile Insect Technique (SIT), which involves sterilising large numbers of a pest, through radiation exposure, and releasing them into the wild pest population where mating results in unfertilised eggs that do not hatch. In support of recent studies on SIT for the brown marmorated stink bug, we aimed to ascertain the feasibility of the method for another stink bug pest, the green vegetable bug. We exposed the insects to increasing levels of radiation and allowed mating to occur. Virtually all of the resulting eggs were sterile and did not hatch at the higher radiation doses tested. These results could be used to inform the potential development of SIT against stink bug pests, and in some circumstances, could form the basis of potential eradication programmes against new invasions.Nezara viridula Linnaeus (Hemiptera: Pentatomidae) is a polyphagous pest of a wide range of economically important crops. Because the control of this species and other pentatomids relies primarily on insecticide application, investigation into the Sterile Insect Technique (SIT) is warranted. We aimed to investigate the irradiation biology of N. viridula for the potential application of SIT against this pest. Male and female N. viridula were gamma-irradiated at doses between 4 and 28 Gy and mated with both irradiated and nonirradiated conspecifics. Sterility of the resulting eggs followed a dose-response in each case. Irradiated males crossed with untreated females showed higher F1 egg sterility than crosses where the female was irradiated. The greatest F1 egg sterility was observed when both parents were irradiated. There was no obvious dose-response for the longevity of irradiated males, and for the fecundity of nonirradiated females mated with irradiated males. The fecundity of irradiated females appeared to decrease with irradiation dose. These results can be applied to a potential future application of SIT against N. viridula, but predominantly supports the ongoing development of SIT for Halyomorpha halys Stål (Hemiptera: Pentatomidae) and hemipteran pests in general.

Effect of Irradiation on Wing Morphology of Drosophila suzukii1

The invasive spotted-wing drosophila, Drosophila suzukii (Matsumura, 1931), affects fruit with a thin epidermis and causes great loss of production. In Mexico, it is regulated because of its economic damage. Relevance of the sterile insect technique has been analyzed for integrated pest management (IPM) against D. suzukii through study of effects of irradiation doses on control. Possible effect of irradiation at 200 Gy with Cobalt-60, sex, and condition (wild and reared on artificial diet) on wing morphology were analyzed by geometric morphometry analysis. No effect on wing morphology by irradiation was observed, however, significant differences were found in the centroid size of wild females compared with irradiated and non-irradiated females fed artificial diet (F147,2 = 67.45, P < 0.0001), and they had no significant difference (F144,2 = 0.81, P = 0.4477) in Procrustes distances. Wild males had significant differences in centroid size (F147,2 = 59.55, P <0.0001) and Procruste distances (F144,2 = 3.49, P = 0.0330) compared to irradiated and non-irradiated males fed artificial diet. Changes in the wing of D. suzukii were more related with diets of insects in immature stages. Complementary studies on artificial diets are suggested to produce insects with dimensions similar to wild specimens.

Combined sterile insect technique and incompatible insect technique: sex separation and quality of sterile Aedes aegypti male mosquitoes released in a pilot population suppression trial in Thailand

ABSTRACTBackgroundThe sterile insect technique (SIT), which is based on irradiation-induced sterility, and incompatible insect technique (IIT), which is based on Wolbachia-induced cytoplasmic incompatibility (a kind of male sterility), have been used as alternative methods to reduce mosquito vector populations. Both methods require the release of males to reduce fertile females and suppress the number of natural populations. Different techniques of sex separation to obtain only males have been investigated previously. Our work involves an application of mechanical larval-pupal glass separators to separate Wolbachia-infected Aedes aegypti males from females at the pupal stage, prior to irradiation, and for use in a pilot field release and to assess the quality of males and females before and after sex separation and sterilization.ResultsThis study was the first to demonstrate the efficiency of mechanical glass separators in separating males for use in an Ae. aegypti suppression trial by a combined SIT/IIT approach. Our results indicated that male and female pupae of Wolbachia-infected Ae. aegypti mosquitoes were significantly different (p < 0.05) in weight, size, and emergence-time, which made it easier for sex separation by this mechanical method. During the pilot field release, the percentage of female contamination was detected to be quite low and significantly different between the first (0.10 ± 0.13) and the second (0.02 ± 0.02) twelve-week period. Both males and females were almost completely sterile after exposure to 70 Gy irradiation dose. We observed that both irradiated Wolbachia-infected males and females survived and lived longer than two weeks, but males could live longer than females (p < 0.05) when they were irradiated at the same irradiation dose. When comparing irradiated mosquitoes with non-irradiated ones, there was no significant difference in longevity and survival-rate between those males, but non-irradiated females lived longer than irradiated ones (p < 0.05).ConclusionMechanical sex separation by using a larval-pupal glass separator was practically applied to obtain only males for further sterilization and open field release in a pilot population suppression trial of Ae. aegypti in Thailand. Female contamination was detected to be quite low, and skilled personnel can reduce the risk for female release. The irradiated Wolbachia-infected females accidentally released were found to be completely sterile, with shorter life span than males.

The sterile insect technique for the management of the spotted wing drosophila, Drosophila suzukii: Establishing the optimum irradiation dose.

The spotted wing drosophila Drosophila suzukii Matsumura (Diptera: Drosophilidae), a pest of berries stone fruits, invaded North America and Europe in 2008. Current control methods rely mainly on insecticides. The sterile insect technique (SIT) has potential as an additional control tactic for the integrated management of D. suzukii. As a step towards the development of the SIT, this study aimed at finding the optimum irradiation dose to sterilize D. suzukii under controlled laboratory conditions. Four-day-old D. suzukii pupae were irradiated 12 to 24 hours prior to adult emergence in a 60Co Gamma Cell 220 and in a 137Cs Gamma Cell 3000 with doses of 30, 50, 70, 80, 90, 100 or 120 Gy. Emergence rate (88.1%), percent of deformed flies (4.0%) and survival curves were not affected by the tested irradiation doses. However, some reproductive parameters of the flies were affected by irradiation. Females irradiated with a dose of 50 Gy or more had almost no fecundity. When non-irradiated females were mated with irradiated males, egg hatch decreased exponentially with irradiation dose from 82.6% for the untreated control males to 4.0% for males irradiated with 120 Gy. Mortality of F1 individuals from the irradiated treatment also occurred during larval and pupal stages, with an egg to adult survival of 0.2%. However, descendants produced by the irradiated generation were fertile. These results are an encouraging first experimental step towards the development of the SIT for the management of D. suzukii populations.

Carotid intima-media thickness in young survivors of childhood cancer.

Radiotherapy (RT) and some chemotherapy regimens are known risk factors predisposing to the development of premature arterial disease. Vascular ultrasound measurement of carotid intima-media thickness (IMT) is a non-invasive technique, useful to detect early subclinical symptoms of atherosclerosis that can appear in the paediatric population. We analysed the influence of chemotherapy and moderate doses of head or neck irradiation in childhood cancer survivors on the possibility of premature carotid artery disease. Ultrasound measurements of the intima-media thickness (IMT) inthe common carotid artery (CCA), bulb and internal carotid artery (ICA) were performed in 74 young cancer survivors and in 48 age- and sex-matched controls. In the whole study group, we observed higher IMT in all positions as compared with the control, except for comparable thickness in the CCA (bilaterally). We failed to find any differences in IMT between irradiated and non-irradiated females. In irradiated males, all IMT measurements on the right side were higher than in non-irradiated patients. There was no effect of body mass index, blood pressure, serum cholesterol, triglycerides, fibrinogen and thyroid hormones on IMT. In the irradiated group, a positive correlation was observed between IMT in the right bulb and the post-radiation time. Anticancer treatment during childhood, especially including irradiation to the mediastinum, head or neck, affects the IMT, particularly in males. This suggests a possible role of irradiation in the premature development of carotid artery disease.

Flight Activity and Mating Behavior of IrradiatedSpodoptera litura(Lepidoptera: Noctuidae) Males and Their F1Progeny for Use of Inherited Sterility in Pest Management Approaches

Abstract The dose of radiation applied to the Oriental leafworm (also known as the common cutworm), Spodoptera litura (F.) (Lepidoptera: Noctuidae) for use in inherited sterility (IS) sterility programs must not materially reduce the quality and competitiveness of the released males. To assess the quality of sub-sterilized male moths and their F1 progeny, their flight and mating behaviors were investigated. Thus, parental (P) generation S. litura males that had been irradiated with either 100 or 130 Gy and their F1 male descendants were subjected to flight assay tests to assess flight ability, orientation towards a pheromone source and mating behavior, i.e., mating performance using various sex ratios, sequential matings, and effect of female age. The orientation behavior of either P or F1 males towards pheromone-baited traps was not different from that of non-irradiated males. Mating abilities of irradiated P generation males and their F1 male progeny with non-irradiated females were studied using severa...

Development, Reproduction and Sexual Competitiveness ofConopomorpha sinensis(Lepidoptera: Gracillariidae) Gamma-Irradiated as Pupae and Adults

Abstract Male and female litchi stem-end borers, Conopomorpha sinensis (Lepidoptera: Gracillariidae) were γ-irradiated in a 60Co source during several periods of their pupal development and as newly emerged adults. When mature pupae, the most suitable stage for irradiation, received increasing γ-radiation doses, the emergence rate, flight ability and adult longevity were increasingly diminished. Females that emerged from mature pupae irradiated with 200, 250, and 300 Gy did not oviposit any eggs when mated with either non-irradiated males (UM) or treated males (TM), indicating that 200 Gy was a sufficient dose for inducing complete sterility in females. The hatch rates of eggs oviposited by non-irradiated females (UF) mated with males irradiated with either 200, 250 or 300 Gy were 31, 13.5 and 0.67%, respectively. However, if the father—parental generation (P)—of the male in the cross, UF × F1 M, had been irradiated with either 200, 250 or 300 Gy, then the percent hatch of the eggs produced was either 9.3...

Reduction in Mutation Frequency by Very Low-Dose Gamma Irradiation of Drosophila melanogaster Germ Cells

To determine whether the linear no-threshold (LNT) model for stochastic effects of ionizing radiation is applicable to very low-dose radiation at a low dose rate, we irradiated immature male germ cells of the fruit fly, Drosophila melanogaster, with several doses of (60)Co gamma rays at a dose rate of 22.4 mGy/h. Thereafter, we performed the sex-linked recessive lethal mutation assay by mating the irradiated males with nonirradiated females. The mutation frequency in the group irradiated with 500 microGy was found to be significantly lower than that in the control group (P < 0.01), whereas in the group subjected to 10 Gy irradiation, the mutation frequency was significantly higher than that in the control group (P < 0.03). A J-shaped dose-response relationship was evident. Molecular experiments using DNA microarray and quantitative reverse transcription PCR indicated that several genes known to be expressed in response to heat or chemical stress and grim, a positive regulator of apoptosis, were up-regulated immediately after irradiation with 500 microGy. The involvement of an apoptosis function in the non-linear dose-response relationship was suggested.

成虫照射したアリモドキゾウムシ雄とペア飼育した雌の交尾・産卵行動

The effects of irradiation on copulatory and oviposition behavior in the sweetpotato weevil , Cylas formicarius (Fabricius) were evaluated using females irradiated with 50 Gy gamma rays during the pupal stage, females irradiated at 200 Gy during the adult stage, and non-irradiated normal females. All types of females copulated with males irradiated during the adult stage or normal males. The females irradiated during the pupal stage did not complete oviposition or produce offspring after copulation when paired with irradiated or normal males, similar to females that did not copulate. The females irradiated during the adult stage exhibited oviposition behavior during a short period just after copulation but gradually stopped , and none produced offspring. Normal females that copulated with males irradiated during the adult stage laid eggs but produced no offspring, whereas they produced offspring when mated with normal males. These results can be used to estimate the competitive ability of released males irradiated during the adult stages against wild males. Using a normal virgin female trap in the field, her copulatory experience and partner can be detected; i.e. , if the female lays eggs, then this indicates she has copulated, and if she fails to produce offspring, this indicates that she has copulated with a released male irradiated as an a adult.

INDUCTION OF STERILITY IN ANASTREPHA FRATERCULUS (DIPTERA: TEPHRITIDAE) BY GAMMA RADIATION

Abstract In relation to the application of the sterile insect technique (SIT) for the South American fruit fly Anastrepha fraterculus (Wiedemann), we analyzed the effect on adult fertility of different doses of gamma irradiation and the age of pupae at the time of irradiation. In a first experiment, we applied doses of 50, 70, and 90 Gy to pupae at 24, 48, 72, and 96 h before adult emergence. In a second experiment we irradiated pupae 48 h before emergence with 20, 40, and 60 Gy and estimated male and female fertility and sperm transfer by irradiated males. The results indicated pupal age at irradiation does not significantly affect male fertility. If males irradiated with 60 Gy are crossed to non-irradiated females the fertility is about 1%. Females irradiated with 40 Gy did not lay eggs independently of the male to which they mated. No significant effects of radiation were observed with respect to the ability of males to transfer sperm. A dose of 70 Gy applied 48 h before adult emergence induces 100% st...

Development of a Pupal Color-Based Genetic Sexing Strain of the Melon Fly, &lt;I&gt;Bactrocera cucurbitae&lt;/I&gt; (Coquillett) (Diptera: Tephritidae)

The Þrst genetic sexing system for the melon sy, Bactrocera cucurbitae (Coquillett), based on pupal color was developed. The recessive white pupae mutant, wh, was used in a putative chromosome translocation linking the wildtype allele to the male sex. This system permits the separation of males (wildtype brown pupae) from females (mutant white pupae). Results from laboratory studies indicated that egg hatch averaged 42% for sies 2Ð5 wk old, with higher rates (50%) for younger sies in this age range. Male larvae left the diet to pupate earlier than females, averaging 60% of the pupae in the Þrst day of collection, whereas only 40% on the fourth day of collection. Adult emergence rate was normal, averaging92%. Adult egg fecundity and fertility (both sexes) were very low( 1% of normal) after irradiation at 100 Gy at 1, 2, or 3 d before emergence. Adult sight ability from standard 20-cm tubes averaged 65%. Irradiated females landed on, and oviposited into, zucchini fruit signiÞcantly fewer times than nonirradiated females. Field cage survival tests indicated that the newstrain survived as well ( 80%) as wild males over a 7-d period when provided with food and water. Mating tests indicated that male-only sterile sies mated signiÞcantly more (about double) with wild females than sterile males from bisexual (male and female) sterile populations competing with wild males. Males fed only sugar until tested in the cages failed to mate with wild females, whereas males fed a low protein diet (6:1 sugar:protein) or the standard 3:1 diet mated as well as wild males for wild females. Finally, males exposed to the attractant, cuelure, failed to improve their mating performance compared with control, unexposed males. The results are discussed in the context of the potential for using the newstrain in current or future melon sy sterile insect technique programs in Hawaii and elsewhere.

Transgenerational genomic instability as revealed by a somatic mutation assay using the medaka fish

We previously established a somatic mutation assay of the medaka wl ( white leucophores) locus based on visual inspection, and showed that somatic mutations at paternally derived alleles frequently arise during the development of F 1 embryos fertilized by sperm/late spermatids that had been exposed to γ-rays. To further study such delayed mutations, we determined the frequency of mutant embryos obtained from three different crosses between irradiated males and non-irradiated females. When sperm and late spermatids were irradiated, the mutant frequency within non-irradiated maternally derived alleles was ∼3 times higher than in the control group. In the F 2 generation, however, no increase in mutant frequency was observed. Similarly, there was no significant increase in the F 1mutant frequency when stem spermatogonia were irradiated. These data suggest that irradiation of sperm and late spermatids can induce indirect mutations in F 1 somatic cells, supporting the idea that genomic instability arises during F 1 embryonic development. Moreover, such instability apparently arises most frequently when eggs are fertilized just after the sperm are irradiated.

Protein consumption by mated, unmated, sterile and fertile adults of the Queensland fruit fly, Bactrocera tryoni and its relation to egg production

Abstract. Female adults of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) at 25 °C require more than 0.1 mg of yeast autolysate per day to mature their oocytes to the vitellogenic stage and mate. Those given 0.2 mg per day from day 2 of adult life mated (when given the opportunity between 11 and 13 days) and each laid approximately 100 eggs (just over one egg per ovariole) by day 56. Females allowed to feed ad libitum from day 2, then 0 or 0.2 mg per day from day 14, laid approximately 75 and 100 eggs, respectively (after mating), whereas those fed ad libitum from day 2 to day 56 laid approximately 540 eggs after mating (averaging just over six eggs per ovariole). The developmental pattern of intake of normal females when on an ad libitum diet showed a rise to a peak at 5–7 days, followed by a decline to sustained low levels if not mated, but rising to a lower peak if mated between days 11–13 followed by a steady decline. Female flies that had been sterilized by 80 Gy gamma irradiation at the puparial stage had a pattern of food consumption similar to that of normal females mated at 7 days but they produced no yolky oocytes and had a darkened fat body. Normal and irradiated males had a feeding pattern similar to that of unmated nonirradiated females but at a lower level. The results are discussed in terms of the control of protein intake and the rate of its conversion to yolk.

Capping of Radiation-Induced DNA Breaks in Mouse Early Embryos

The aim of the study was to investigate the spectrum and frequencies of chromosome aberrations induced by the exposure of different mouse spermatogenic germ cell stages to ionizing radiation. Male mice were exposed in vivo to X-rays. Chromosome aberrations were analyzed in first- and second-embryonic cleavages obtained from mating irradiated males with nonirradiated females at different periods after radiation exposure. A combination of telomeric and centromeric labeling as well as whole Y chromosome painting was used to characterize the rejoining pattern and the telomere status of the radiation-induced DNA breaks. The frequency of chromosome aberrations observed in eggs fertilized with sperm irradiated at the early spermatid stage was markedly higher than the frequency in eggs fertilized with sperm irradiated at the other spermatogenic stages when reference was made to the chromosome aberrations recovered in early embryos. At the first division postirradiation, distal rejoining of broken chromosome ends (in regard to the position of the centromere) was more frequent than proximal rejoining; thus compound acentric fragments were more frequently observed than dicentric chromosomes. The presence of additional telomere signals at the broken chromosome ends in mouse germ cells and early embryos, compatible with de novo formation of telomeres, was not frequent.