Progeny: Sperm ratios and segregation-distorter inDrosophila melanogaster

Progeny: sperm ratios (P/S) were determined from crosses ofSD/cn bw males ofDrosophila melanogaster with females of eight different genotypes. Thek value was about 1.0. P/S ratios of 0.88, 0.81, and 0.76, respectively, were observed from crosses with females of three genotypes, and ratios in the 0.3–0.4 range from five. These results support the suggestion ofZimmering & Fowler (1968) that P/S ratios may vary widely and depend at least in part on the genotype of the female. Morcover, since P/S ratios of 0.9 may be observed whenk is about 1.0, it follows that the vast majority of sperm stored in these females areSD.Supported by NSF grant GB 8565.NSF Undergraduate Research Participant.     

Remating inhibition in female Queensland fruit flies: effects and correlates of sperm storage

Reproductive success of male insects commonly hinges both on their ability to secure copulations with many mates and also on their ability to inseminate and inhibit subsequent sexual receptivity of their mates to rival males. We here present the first investigation of sperm storage in Queensland fruit flies (Tephritidae: Bactrocera tryoni; a.k.a. 'Q-flies') and address the question of whether remating inhibition in females is directly influenced by or correlated with number of sperm stored from their first mates. We used irradiation to disrupt spermatogenesis and thereby experimentally reduce the number of sperm stored by some male's mates while leaving other aspects of male sexual performance (mating probability, latency until copulating, copula duration) unaffected. Females that mated with irradiated rather than normal males were less likely to store any sperm at all (50% vs. 89%) and, if some sperm were stored, the number was greatly reduced (median 11 vs. 120). Despite the considerable differences in sperm storage, females mated by normal males and irradiated males were similarly likely to remate at the next opportunity, indicating (1) number of sperm stored does not directly drive female remating inhibition and (2) factors actually responsible for remating inhibition are similarly expressed in normal and irradiated males. While overall levels of remating were similar for mates of normal and irradiated males, factors responsible for female remating inhibition were positively associated with presence and number of sperm stored by mates of normal but not irradiated males. We suggest seminal fluids as the most likely factor responsible for remating inhibition in female Q-flies, as these are likely to be transported in proportion to number of sperm in normal males, be uninfluenced by irradiation, and be transported without systematic relation to sperm number in irradiated males.     

Effect of irradiation on mating performance and mating ability in the West Indian sweetpotato weevil, Euscepes postfasciatus

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 not only damages the reproductive cells but the somatic cells as well. The mating behavior of irradiated males may be altered over time due to the depressed metabolic activity brought about by sterilization. In this study, we evaluated the mating behavior (copulation behavior, mating performance, and ability of sperm transfer) of irradiated males in Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) for 16 days after irradiation in the laboratory. The mating performance of males irradiated with a 150 Gy dose, as currently used in the SIT program in Okinawa prefecture for E. postfasciatus, decreased compared to that of control after day 7. As a result, we considered that irradiation had no major effect on male mating behavior for approximately 1 week after irradiation.     

Observations on the effect of X-ray alone and in combination with ultrasound on human chromosomes

Summary Human peripheral blood was treated with ultrasound either before or after irradiation, and chromosome aberrations in lymphocytes of peripheral blood cultures compared to those resulting from an equivalent dose of irradiation given alone.When peripheral blood is sonicated at a high intensity (3 W/cm²) for 10 min after irradiation, there is an increase in aberration frequency as compared to control samples receiving the equivalent radiation dose alone. However, should the blood be sonicated at the same frequency and for the same time period before radiation there is no significant increase in total chromosome aberrations over the irradiated controls. On the contrary a significant decreases occurs in certain classes of aberration.When sonification with a lower intensity (20 mW/cm²) was used in combination with irradiation the reverse effect was noted. Ultrasound administered for 10 min after radiation caused no significant increase in aberrations. On the contrary increasing the period of sonification to one hour resulted in a lowering of all types of aberration, significant in the case of dicentrics and total chromosome aberrations, when compared to irradiation alone. Reversing the order of treatment again resulted in the opposite effect to that achieved with comparable experiments at high intensities of sonification. Ultrasound before radiation did not produce lower breakage rates. Instead, when the period of sonification was increased to one hour, the number of aberrant cells, fragments, and total aberrations rose significantly over controls.It is suggested that sonification produces chemical changes affecting cellular repair systems, which when combined with ionising radiation, results in an increased or decreased repair effect depending on the dose, duration, and order of treatment.Dedicated to Prof. Dr. Felix Mainx on the occasion of his 80th birthday     

Segregation distorter in D. melanogaster males: An effect of female genotype on recovery

Summary Segregation Distorter (SD) is a gene affecting sperm recovery in Drosophila melanogaster. In a cross SD/SD ⁺ x SD⁺, the proportion of SD/SD ⁺ zygotes recovered (k) is larger than the 0.50 expected. Previous investigations have shown that the relative recovery of SD- and SD ⁺-bearing sperm is determined at or before the meiotic divisions. Evidence is presented here that k is influenced by the genotype of the female parent. It is suggested that the SD gene product causes a difference in the enzymatic or structural complement of the SD- and SD ⁺-bearing sperm which largely determines their relative functionality. The effect of the female genotype on recovery is interpreted as an interaction between this physiological difference and the environment of the female reproductive tract.Adapted from a dissertation presented by the senior author in partial fulfillment of the degree of Doctor of Philosophy. This investigation was supported by PHS Training Grant No. GM 00337 and PHS Research Grant No. GM 12334 from the National Institute of General Medical Sciences.     

Impedance Measuring Technique for Identifying Irradiated Potatoes

The magnitude, resistance, and reactance of impedance of potato tubers were significantly influenced by irradiation. Although different types ofelectrode resulted in different values of these impedance parameters, the ratios of the impedance parameters at 5 kHz to 50 kHz got rid of the influence of the type of electrodes. The ratio of impedance magnitude at 5kHz to 50kHz (Z_5k/Z_50k) resulted in a larger difference between unirradiated and irradiated potatoes than those of resistance and reactance. The degree of difference in Z_5k/Z_50k between unirradiated and irradiated potatoes was dependent upon the measuring temperature and the region of the tuber punctured with electrodes. The impedance ratio (Z_5k/Z_50k) measured at 22–25°C at an apical region of potato tuber with 1 mA of alternating current resulted in the best identification of irradiated potatoes and enabled differentiation of irradiated potatoes from unirradiated ones for up to 6 months.     

Ultrastructural Analysis of Spermiogenesis in Segregation Distorter Males of DROSOPHILA MELANOGASTER: The Homozygotes

We have studied spermiogenesis at the ultrastructural level in males of genotype SD(NH)-2/SD-72, which are nearly sterile owing to the dysfunction of virtually all of their sperm. Ultrastructural aspects of spermiogenesis in these homozygous SD males are qualitatively similar to those found among dysfunctional sperm produced by heterozygous SD males. In particular, chromatin condensation and/or compaction has been found to be abnormal. However, major quantitative differences have been noted. Most of the dysfunctional sperm in SD(NH)-2/SD-72 males are individualized and coiled. Then, the sperm evidently undergo degeneration, as few mature sperm can be found in the seminal vesicle. The relevance of these findings to the mechanism leading to near sterility in homozygous SD males is discussed.     

Sperm precedence in <Emphasis Type="Italic">Callosobruchus chinensis</Emphasis> estimated using the sterile male technique

P₂, the proportion of offspring sired by the second male to mate, is an indicator of the outcome of postcopulatory sexual selection, which occurs through sperm competition and/or cryptic female choice. We determined the appropriate dose of gamma radiation for sterilization of adult males and, using the sterile male technique, measured P₂ in the adzuki bean beetle, Callosobruchus chinensis. Adult males of C. chinensis were almost completely sterilized when irradiated at 80 Gy. Thus, we obtained sterile males through irradiation at this dose. Neither the probability of female first mating nor the probability of female remating was affected by whether females were paired with normal or sterile males. The P₂ calculated from the hatching success of eggs laid by females that mated both with normal and sterile males did not differ between reciprocal mating sequences, indicating that the sterilization has no effect on sperm fertilizing ability. The P₂ was estimated at 0.25. This study shows that female remating in C. chinensis means the coexistence of sperm from two males and thus the occurrence of postcopulatory sexual selection within the female reproductive tract, resulting in first-male sperm precedence.     

The relationship between first and second chromosome segregation ratios from Drosophila melanogaster males bearing Segregation Distorter

Summary Drosophila melanogaster males heterozygous for the second chromosome locus Segregation Distorter preferentially transmit this chromosome to their progeny due to a dysfunctioning of SD ⁺-bearing sperm. SD males with a normal sex chromosome constitution produce more females than males among SD ⁺ progeny. This report shows that this unequal recovery of sexes is enhanced from XY/Y; SD/SD ⁺ males and enhanced still further from XY/O; SD/SD ⁺ males. It is argued that the probability that a SD ⁺-bearing sperm will dysfunction is related to its sex chromsome complement, with the relative probabilities of dysfunction ranked O> Y> X> XY. It is shown that a modified probit analysis accounts for the relationship between sex ratio and second chromosome segregation frequency for all paternal genotypes. Finally, SD/SD ⁺ males show no increase in sex chromosome nondisjunction with respect to a control.R. E. Denell was supported by U.S.P.H.S. Training Grant No. GM00337 and by a U.S.P.H.S. Postdoctoral Fellowship; George L. Gabor Miklos was supported by A.E.C. Contract No. AT (04-3)-34 PA150.     

Proceedings: Heterochromatin and chromosome aberrations: a comparative study of normal and tumour cells of mouse with various distributions of heterochromatin.

Seedlings of Crepis capillaris were irradiated after pulse-labelling with tritiated thymidine ([³H]TdR), and both chromosomal aberrations and presence of silver grains were recorded in the same metaphase cells at various intervals throughout the whole mitotic cycle. The following results were obtained: (a) irradiated roots were homogeneous with respect to the number of aberrations, and heterogenous with respect to labelling index (LI); (b) time-effect curves for labelled (L) and unlabelled (U) cells showed no significant difference from one another; (c) no significant quantitative difference of aberration spectra produced in S and G₂ stages was found. These results support the view that the major factor which determines both quantitative and qualitative variation in the production of chromosomal aberrations by radiation is the time lapse between irradiation and fixation rather than relation of the time of irradiation to the time of DNA synthesis. In addition, it was found that labelling with [³H]TdR modifies the effect of radiation on chromosomes.     

X-irradiation of theDrosophila male and its effect on the number of sperm transferred to the female

Summary Experiments were carried out to determine the number of sperm transferred by the maleDrosophila after X-irradiation. Acute doses (1000 r/min) of 5,000 r, 25,000 r and 50,000 r delivered to the male results in reductions of some 20–25%, 60–65%, and 85–90%, respectively, in the number of sperm scored in the ventral receptable of inseminated females. It appears, further, that sperm in ejaculates of relatively small size (50 or fewer) from irradiated as well as unirradiated males distribute themselves such that 20–50% or more found in the spermathecae. The bearing of this observation on the apparent 1:1 sperm: progeny ratio reported byPeacock andErickson (1965) from ejaculates with low sperm number is noted.Supported by National Science Foundation Grant GB-3117.     

The feasibility of using the sterile insect technique against Liriomyza trifolii (Diptera: Agromyzidae) infesting greenhouse chrysanthemum

Liriomyza trifolii is a serious pest of chrysanthemum greenhouses and other crops around the world. The larvae feed within the leaves of the host plants and create serpentine mines. The Sterile Insect Technique (SIT) has been successfully used against some Dipteran species in the field, and it is especially efficient against isolated populations like those on islands. Therefore, SIT against pest populations in confined environments such as greenhouses should have high potential for success. The objectives of this study were to determine the optimum gamma‐irradiation dosage required for the sterilisation of L. trifolii adults, and to determine the quality (emergence percentage, flight ability, longevity, copulatory success, and sperm transfer) of the irradiated males compared with that of non‐irradiated (normal) males. We found that sterility (< 0.7 mine per female) was achieved with the dose of 170 ± 5% Gy. The copulatory success and sperm transfer during copulation of the sterile males were not significantly different from those of normal males. Moreover, the longevity, emergence percentage and flight ability of irradiated males were also not significantly different from normal males. The SIT experiments suggest that the release of sterile L. trifolii can significantly reduce the reproductive capacity of a wild leafminer population. Our studies indicate that sterilisation of L. trifolii flies is feasible and that sterile males are of high quality and competitive with normal males. Based on these data, research on the use of SIT against L. trifolii populations in greenhouses is ongoing.     

The effects of X-rays on the chromosomes of locust embryos

Irradiation of Schistocerca gregaria embryo cells during the S and G₂ stages of interphase produces the same general classes of chromatid aberration as have been seen in organisms, such as Vicia faba, which have been used widely in radiocytological work. In addition, however, a series of intrachange aberrations has been found which is novel. In order to account for these Revell's exchange hypothesis has been extended to include the involvement of isolocus primary lesions. The exchange-type hypothesis is preferred because it can more readily accomodate the whole spectrum of aberrations found.     

The influence of X-rays on reproduction in Pseudeucoila bochei (Hymenoptera Cynipidae), a parasite of Drosophila melanogaster

The parasitic wasp Pseudeucoila bochei was the subject in experiments designed to detect a reliable method of mutation induction. Radiation doses of 360, 720, 1080, 1440, 1800 and 2160 R were given to pupae 15 or 18 days old or to freshly eclosed male and female wasps. The irradiation did not influence the survival of pupae. Dose-action responses were established and appeared to be dependent on the stage of development of the wasps at the moment of irradiation. The production of sons by virgin females showed that the germ cells of the adults were the most sensitive to irradiation. In contrast, the sperms of the male wasps irradiated as adults were the most resistant. Irradiation of males as pupae with 1880 or 2160 R on the 15th day or as adults led to a high frequency of amle progeny. The elimination of sperm cells from fertilization is discussed. Comparisons with Habrobracon, Nasonia and Drosophila showed that the germ cells of Pseudeucoila are more sensitive to irradiation. In the progeny from irradiated females and males 2 types of mutant were found, with yellow eye colour and with aberrations in the antennae.     

Sperm storage and viability within females of Euscepes postfasciatus: Effect of irradiation on sperm abundance and viability within female

Irradiation has been widely used in suppression or eradication programs that use the sterile insect technique (SIT) or in studying sperm competition. Although it is well known that irradiation has negative impacts on reproductive (sperm) cells, previous studies have assumed that sperm from irradiated males behave identically to normal sperm in the female reproductive tract after mating. In this study, we used the West Indian sweetpotato weevil Euscepes postfasciatus to investigate the effect of irradiation on the abundance and viability of sperm in female spermatheca for 14 days after copulation. The abundance of sperm in females did not change throughout the experimental period, and sperm viability gradually decreased regardless of irradiation. In this weevil, irradiated sperm appear to behave identically to normal sperm in females for 14 days following irradiation/copulation. Therefore, the effect of irradiation on sperm viability within the female spermatheca is considered to be insignificant.     

Fragmentation par les rayons X de l'organisateur d'une différenciation de chromosome en écouvillon (lampbrush), chez Pleurodeles waltlii

X-rays have been used to induce heritable changes in the specific morphology of the lampbrush chromosomes in the newt Pleurodeles waltlii. The karyotype organization of female progeny of irradiated males was studied. Nine out of ten females were found to have chromosomal aberrations. In one of the nine, one of the breaks occurred at the sphere organizer, the sphere being part of the striking morphological features of chromosome IV. On irradiation the normal sphere organizer had been broken into two fragments each of which, when recombined with other chromosome breaks, still forms a sphere. The relationship of these observations to genome redundancy is discussed.     

THE EFFECT OF IRRADIATED PLASMA ON NORMAL HUMAN CHROMOSOMES AND ITS RELEVANCE TO THE LONG-LIVED LYMPHOCYTE HYPOTHESIS

The persistence of unstable chromosome-type aberrations in peripheral blood lymphocytes of irradiated individuals has led to the proposal that some lymphocytes survive for many years in vivo without undergoing mitosis (Fitzgerald, 1964). It has recently been shown, however, that plasma from irradiated individuals can induce chromosomal damage in cultures of normal blood lymphocytes (Hollowell & Littlefield, 1968) even when the plasma donors were irradiated 7 years earlier (Goh & Sumner, 1968). Goh (1968) has therefore suggested that ‘An alternate explanation to the “long-lived cell” theory proposed by others…would be that a substance is produced or activated by total body irradiation and remains capable of affecting the chromosomes for extensive lengths of time'. The present results show that a lymphocyte chromosome-breaking factor can be induced in the plasma of blood irradiated in vitro as well as in vivo. All of the aberrations induced by this ‘plasma factor’and those reported by other workers can be interpreted as being of the chromatid type. Before the long-lived lymphocyte hypothesis can be brought into serious disrepute, it must be shown that the plasma factor can induce aberrations of the same type as persist after in vivo irradiation (i.e. unequivocal chromosome-type aberrations, such as dicentrics and rings) and that these can be induced in vivo.     

X-ray-induced mutation spectra of different germ-cell stages of Drosophila males with a double marked Y-chromosome and either a normal X-or a ring-X-chromosome (author's transl)

Different germ-cell stages of Drosophila males with a double marked Y-chromosome and either a normal X- or a ring-X chromosome were irradiated with X-rays, inducing the following aberrations: chromosome loss, chromosome gain (XYX-females), partial Y loss and isochromosomes of the Y-chromosome.Doses of 520 rad in spermatocytes and spermatids and 2600 rad in sperm, produced the same effect in these stages with regard to the chromosome loss in the males with a normal X, and the following results were obtained: (a) The partial Y loss in postmeiotic stages is small in comparison with spermatocytes in both stocks. This could mean that in spermatocytes this aberration is determined by exchange processes which can only be induced and/or detected in premeiotic stages. (b) In spermatocytes and mature sperm of males with a ring-X chromosome, the chromosome loss was 2.9 times greater than in those with a normal X. In spermatids of the males with a ring-X the rate of loss was only 1.5 times greater. In spermatocytes of either males with a ring-X or a normal X a similar high rate of isochromosomes could be induced. However, in spermatids and mature sperm the rate of induction of isochromosomes was found to be very small. These results seem to indicate that in mature sperm the rejoining of breaks in the Y-chromosome takes place before, and in the X-chromosome usually after the replication. If in post-meiotic stages of Drosophila the X- and Y-chromosomes existed as chromatid-like subunits then in spermatids these should behave as a structural unit.In sperm we were able to induce similar frequencies of individuals with a single isochromosome type in all body cells as of individuals with two types of isochromosomes (isochromosome mosaics). This result seems to indicate that after irradiation of sperm one of the first two division nuclei is lethal in an proportion of the zygotes.     

Radiosensitivity of two strains of the codling moth Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae) originating from different elevations in Armenia

The purpose of this study was to analyse the radiosensitivity of codling moth Cydia pomonella (L.) strains from different elevations, 850 and 2000 m above the sea level. The level of sterility of parental males and inherited sterility of F₁ males in the strain from the higher elevation at all radiation doses (80, 100 and 150 Gy) was significantly lower, than in the strain from the lower elevation. The frequency of chromosomal aberrations in the F₁ generation in the strain from the higher elevation was significantly lower at 80 and 150 Gy than that in strain from the lower elevation. The average number of eupyrene sperm in the F₁ males descended from irradiated males was higher in the strain from the higher elevation than in the strain from the lower elevation. Inheritance of the resistance/susceptible to ionizing radiation were examined by standard genetic cross‐breeding analysis confirming the polygenic nature of the differences in radiosensitivity. The implications of these findings for the implementation of area‐wide integrated pest management programmes that integrate the use of sterile insects are discussed.     

Improvement of stored turkey semen quality as a result of He-Ne laser irradiation

Two experiments were carried out to evaluate the effects of He-Ne laser irradiation at various energy doses on the quality of stored turkey semen. Four semen pools were used in Experiment 1. Each pool was divided into 10 aliquots, nine of which were irradiated with energy doses ranging from 0.144 to 10.8 J/cm2 while the tenth one was not irradiated (control). Each sample was evaluated for motility immediately after irradiation, 24 and 48 h later. Energy doses ranging from 3.24 to 5.4 J/cm2 had higher (P <0.01) sperm motility index (SMI) value compared to the control and samples irradiated with lower and higher laser doses. The energy dose of 3.96 J/cm2 was selected for Experiment 2 to obtain further insight on its effects on turkey sperm preservation for up to 60 h. Each pool of four semen was divided into two aliquots: one represented the control and the other one was irradiated with He-Ne laser at an energy dose of 3.96 J/cm2. Each sample was evaluated for motility and viability immediately after irradiation and then at 12 h intervals up to 60 h. The cell energy charge was also measured by HPLC. Exposure to 3.96 J/cm2 increased the SMI and viability of turkey semen stored for 60 h compared to the control (P <0.05). The cell energy charge of irradiated samples was 200% higher than in the control. Laser irradiation increased the longevity of stored turkey spermatozoa, and might be a useful technique to enhance semen quality in long-term storage.