Radioprotective effect of six chemicals against X-ray-induced genetic damage in D. melanogaster

In Drosophila melanogater six chemicals were tested for radioprotectiveeffect against X-ray-induced genetic damage such as sex-linked recessive lethals and autosomal translocations using Oster's ring-X chromosome stock. A 2-day brood pattern was followed to score the damage induced at different spermatogenic stages separately. In all cases the chemicals were injected before X-irradiation. 10-mM solution of reduced glutathione (GSH) provided statistically significant protection against sex-linked recessive lethals in all broods. In translocation tests this chemical reduced the frequency in all broods but the result is not statistically significant. Cysteamine (MEA) did not show any protective effect but the frequency of lethals was slightly reduced in the first and fourth broods. 2-Aminoethyl isothiuronium Br·HBr (AET) showed a statistically significant protective effect when the data of the replicate experiments were pooled. Negative results were obtained for 5-hydroxytryptamine (5-HT) in sex-linked lethal tests. Aminoethyl phosphorothioate (AEPT) reduced the frequencies of both sex-linked lethals and autosomal translocations in all broods consistently but the results are not statistically significant. In tests for both lethals and translocations the reduction was largest in the stages with highest radiosensitivity. N(3-Aminopropyl)aminoethyl phosphorothioate (3AP-AEPT) gave no protection.     

Effects of a small X-ray exposure to Drosophila melanogaster females on the recovery of genetic damage from X-irradiated males.

Wild-type (Oregon-K) Drosophila melanogaster males were X-irradiated and mated to Oster females (y sc^s1 In49sc⁸; bw; st p^p) that had received a 20 R X-ray exposure (Group MF) or no irradiation (group M). Mature spermatozoa of the irradiated males were sampled and the frequencies of dominant lethals, sex-linked recessive lethals and 2–3 translocations were measured. In the group in which the irradiated males were mated to irradiated females, the survival of eggs was significantly higher than in the group in which only the males were irradiated. However, there was no consistent and detectable difference between the two groups with respect to the frequencies of recessive lethals and translocations.The relatively higher egg survival in the MF group is amenable to an interpretation based on an inducible repair process in females that acts on radiation damage induced in spermatozoa but, such an explanation is inadequate to explain the other results. It is concluded that the observations considered together preclude a general and unifying interpretation based on a low-dose-X-ray-inducible genetic repair process in females (acting on damage in spermatozoa). Possible reasons for the discrepancy between the expectation of differences in response between the MF and M groups (in sex-linked lethal and translocation frequencies) and the observation of no consistent differences between them are discussed.     

Studies on mutagen-sensitive strains of Drosophila melanogaster I. The enhanced X-ray sensitivity of a mutant strain (ebony) which is UV-sensitive and also deficient in photorepair

Yegorova and colleagues (1978) showed that a mutant strain of Drosophila melanogaster (ebony) was more sensitive to UV-induced killing of embryos and also less proficient in photoreactivating (PR) ability than a wild-type (Canton-S) strain and that the genes governing UV sensitivity and PR ability were different and presumably located on the autosomes. The experiments reported in the present paper were designed to compare the patterns of sensitivity of these 2 strains and their hybrids to X-irradiation. The sensitivity of the larvae to the killing effects of X-irradiation, and of male and female germ-cell stages to the X-ray induction of genetic damage was studied.It was found that the larvae of the ebony strain are more sensitive to X-ray-induced killing than those of the Canton-S strain. The frequencies of radiation-induced dominant lethals and sex-linked recessive lethals are higher in spermatozoa sampled from ebony males than in those of Canton-S males. In spermatozoa sampled from hybrid males, the yields of dominant lethals are no higher than in those sampled from Canton-S males and do not seem to depend on the origin of the X-chromosome. There are no statistically significant differences between the ebony and Canton-S strains in the sensitivity of their spermatozoa to the induction of autosomal translocations.Stage-7 oocytes sampled from ebony females are more sensitive to the X-ray induction of dominant lethality than are those from Canton-S females; oocytes sampled from hybrid females manifest a level of sensitivity that is significantly lower than that in either parental strain. The frequencies of X-chromosome losses induced in in this germ-cell stage are significantly lower in ebony than in Canton-S females at least at the exposure level of 3000 R at which 3 experiments were carried out. There are no measurable differences in the amount of dominant lethality induced in stage-14 oocytes of ebony, Canton-S and hybrid females.When X-irradiated Berlin-K males are mated to ebony or Canton-S females, the yields of dominant lethals are higher when ebony females are used, showing that there is a “maternal effect” for this kind of damage. Such a maternal effect is also found for sex-linked recessive lethals (irradiated Muller-5 males mated to ebony or Canton-S females). However, when irradiated ring-X-chromosome-carrying males are mated to ebony or Canton-S females, the frequencies of paternal sex-chromosome losses (scored as XO males) are lower when ebony females are used.These results have been interpreted on the assumption that the ebony strain is homozygous for recessive, autosomal genes that confer increased radiosensitivity and that the Canton-S strain carries the normal, wild-type alleles for these genes. The higher yields of dominant and recessive lethals in mature spermatozoa and of dominant lethals in stage-7 oocytes are a consequence of an enhanced sensitivity to the mutagenic (in particular, to the chromosome-breaking) effects of X-irradiation and/or of defective repair of radiation-induced genetic damage. The lower yield of XO males from irradiated stage-7 oocytes of ebony females is probably a consequence of a defect in the repair of chromosome-breakage effects, resulting in the conversion of potential X losses in females into dominant lethals. The “maternal effects” for dominant lethals, sex-linked recessive lethals and for the loss of ring-X chromosomes are assumed to have a common causal basis, namely, a defective repair of chromosome-breakage events in the females of the ebony strain.     

The mutational spectrum of procarbazine in Drosophila melanogaster.

The antineoplastic agent Procarbazine was tested for the induction of genetic damage in Drosophila melanogaster. The compound was administered to adult males by oral application. The following types of genetic damage were measured: (1) sex-linked recessive lethals; (2) dominant lethals; (3) total and partial sex-chromosome loss; and (4) translocations. Procarbazine is highly mutagenic in causing recessive lethal mutations in all stages of spermatogenesis. In sperm a clear-cut concentration-effect relationship is not apparent, but in spermatids such a relationship is obtained for mutation induction at low levels of procarbazine exposure, while at high concentrations the induction of recessive lethals is not a function of concentration. A low induction of total sex-chromosome loss (X,Y) and dominant lethals was observed in metabolically active germ cells (spermatids), but procarbazine failed to produce well-defined breakage events, such as partial sex-chromosome loss (YL,YS) and II-III translocations. The results obtained in Drosophila melanogaster are discussed and compared with the mutational pattern reported in the mouse after procarbazine treatment.     

Mutagenicity studies in Drosophila melanogaster with Lannate 20

Lannate 20 a carbamate pesticide was evaluated for its mutagenicity in Drosophila melanogaster by the sex-linked recessive lethals and chromosome II-III translocation tests by continuous larval feeding. The 3 sublethal doses of 0.2, 0.4 and 0.6 microliter of Lannate per 100 ml of the food medium induced a significant (P less than 0.01) increase in the number of sex-linked recessive lethals over the controls. However, no translocations were observed either in the treated or the control series.     

Radiosensitivity of Drosophila lines. VII. The effect of the maternal genotype on the yield of recessive and dominant lethal mutations induced by the gamma irradiation of males

The effect of material repair on induction of paternal mutations was tested with radiosensitive rad(2)201G1 mutant. Basc males were irradiated at doses from 0 to 60 Gy of gamma-rays and mated to the radiosensitive mutant or control females. Frequencies of sex-linked recessive lethals and dominant lethals (induced in the paternal genome) were determined. With control females, the rate of recessive lethals increased linearly from 0 to 60 Gy. With rad(2)201G1 mutant, an increase in spontaneous and induced rates of paternal dominant lethals was observed; the rate of sex-linked recessive lethals increased non-linearly from 0 to 60 Gy.     

Mutagenicity of hycanthone in drosophila: Additional results and a comparison with some analogs

The data reported in this paper extend earlier results on the effects of hycanthone in Drosophila. The main findings are the following. (1) A refined brood-pattern analysis of hycanthone-induced sex-linked recessive lethals confirmed the specific sensitivity of mid- and late spermatids. Injection of young males (0–20 h old) did not cause a shift in the brood pattern, but tended to produce higher rates of recessive lethals than injection of 4-day-old males, although the difference was not significant. (2) An autosomal recessive lethal test (chromosome 2) similarly showed a low sensitivity of premeiotic stages. (3) Feeding of hycanthone was much less effective than injection. This difference was not observed for the methyl analog lucanthone. From the observation that hycanthone- and lucanthone-induced mutations exhibited different germ-cell-stage sensitivity patterns, it was concluded that lucanthone does not (at least not exclusively) act via metabolic activation to hycanthone. (4) After injection, the hycanthone analogs IA-4-N-oxide and IA-4-N-oxide were marginally mutagenic. (5) It was shown previously that hycanthone was ineffective in producing breakage events, in Drosophila. In this report, hycanthone is shown to be weakly active in inducing ring-X chromosome loss. This emphasizes the relat ive sensitivity of the ring-X-loss test, in comaprison with the tests that etect translocations or dominant lethals.     

Investigations on radiosensitive and radioresistant populations of Drosophila melanogaster. IV. The genetics of the relative radioresistance in stage-7 oocytes of the irradiated population RO I

The genetic system that controls the relative radioresistance in an irradiated laboratory population of Drosophila melanogaster (RÖ I) was studied. Comparisons were made between an unirradiated control population (+60, +K), the population RÖ I (after 227–333 generations of irradiation at 2100 R per generation), the sub-population RÖ I₀ (derived from RÖ I after 260 generations of irradiation and kept without irradiation for up to 74 generations), the F₁ hybrids +60/RÖ I, various homo- and heterozygous carriers of the 3 major chromosomes of RÖ I and +60, respectively, in combination with suitable balancers, and several chromosome substitution stocks of +K and RÖ I. The criteria used to assess the magnitude of radiosensitivity were dominant lethals, X-chromosome loss, and sex-linked recessive lethals induced in stage-7 oocytes at various exposure levels of X-irradiation.The data show that the radioresistance in RÖ I is controlled by a stable and homozygous genetic system. The system is semidominant. With respect to the induction of dominant lethals and sex-linked recessive lethals, the relative resistance is mainly contributed by chromosomes I and II. The effects of the two chromosomes are additive, each contributing about half the relative resistance. Resistance to the X-ray induction of X-chromosome loss is solely contributed by chromosome II.The findings suggest that at least 2 different and independent mechanisms are involved in determining the resistance of the RÖ I population.     

Induction of sex-linked recessive lethals and autosomal translocations by beta-propiolactone in Drosophila: influence of the route of administration on mutagenic activity.

Beta-propiolactone (BPL) was tested for the induction of sex-linked recessive lethals and autosomal translocations in Drosophila melanogaster. The compound was administered to adult males either by oral application or by abdominal injection. When injected, BPL was a potent inducer of sex-linked recessive lethals. When BPL was given by feeding, its mutagenic activity was detectable only when the flies were starved and when the BPL-containing solutions were renewed several times. Nevertheless, the recessive-lethal frequency was one order of magnitude higher with injection. This difference in effects is attributed to (1) rapid decomposition of the compound in aqueous feeding solutions, and to (2) rapid degradation in vivo which restricts the activity of BPL mainly to the site of application. These data are compared with other studies in which both routes of application were applied. BPL induced translocations in stored spermatozoa when injected, but not when fed. This finding seems a logical consequence of (1) the difference in effectiveness of the two routes of application for BPL, and (2) the existence of different LECs for mutation induction (recessive lethals) and for chromosome breakage (translocations). In Drosophila, the breakage capacity of BPL was one order of magnitude lower than that of MMS, when a comparison was made on the basis of equal recessive-lethal frequencies.     

Effect of glyoxal pretreatment on radiation-induced genetic damage in Drosophila melanogaster

The effects of glyoxal and of glyoxal pretreatments on radiation-induced genetic damage were investigated in Drosophila melanogaster mature sperm, by means of sex-linked recessive and dominant lethality, reciprocal translocation and chromosome loss tests. In addition, the possible mutagenic effect of glyoxal was assessed in postmeiotic cells up to 7 days after treatment. The results obtained show: (1) the frequencies of recessive lethals after glyoxal treatment were within control values, (2) no clastogenic effect of glyoxal was observed, (3) glyoxal pretreatment did not modify the frequency of recessive lethals induced by X-rays, (4) after pretreatment with glyoxal a consistent, though not significant, increase was seen in the frequency of reciprocal translocations in 3 replicate experiments, (5) the yield of dominant lethals and of complete and partial chromosome loss induced by radiation was significantly increased by pretreatments with glyoxal. It is suggested that the increase of the frequency of genetic endpoints resulting from chromosome breakage, when glyoxal was administered prior to irradiation, could be ascribed to: (a) a sensitizing action of glyoxal to the clastogenic effect of ionizing radiation; (b) the formation of reactive species by the interaction of glyoxal with radiation; and/or (c) interference of glyoxal with the normal handling of radiation-induced lesions in mature postmeiotic male cells.     

Effects of a chromosome-3 mutator gene on radiation-induced mutability in Drosophila melanogaster females

A series of X-irradiation experiments was carried out using Drosophila melanogaster females homozygous for a third chromosome mutator gene and females which had a similar genetic background except that the mutator-bearing third chromosomes were substituted by normal wild-type chromosomes. The mutator females had been previously shown by Gold and Green to manifest a higher level of radiation-induced mutability (as measured by the X-ray-induction of sex-linked recessive lethals) in their pre-meiotic germ cells compared to normal females at an exposure of 100 R. In the presence work, the sensitivity of the pre-meiotic germ cells of mutator and normal females to the X-ray induction (2000 R) of sex-linked recessive lethals was studied. In addition, experiments were conducted to examine the sensitivity of the immature (stage 7; prophase I of meiosis) oocytes of both kinds of females to the induction of dominant lethals, X-linked recessive lethals and X-chromosome losses. The result show that in pre-meiotic germ cells, the frequencies of radiation-induced recessive lethals are similar in both kinds of females. However, the proportion of these mutations that occur in clusters of size 3 and higher, is higher in mutator than in normal females. In stage-7 oocytes, the frequencies of radiation-induced dominant lethals and sex-linked recessive lethals were similar in both kinds of females. The X-loss frequencies however, were consistently higher in mutator females although statistical significance was obtained only at higher exposures (3000 and 3750 R) and not at lower ones (750-2250 R). Possible reasons for the discrepancy between the present results and those of Gold and Green with respect to pre-meiotic germ cells are discussed.     

Evidence of an essential difference between point mutations and chromosome breaks induced by triethylene melamine inDrosophila spermatozoa

Summary Storing of triethylene melamine-treated mature spermatozoa in untreated females was found to result in increased frequencies of both sex-linked recessive lethals and translocations involving the Y, II and III chromosomes. Frequencies of these mutations in effectively unstored spermatozoa were determined from progenies produced using sperm 2–4 days after treatment. The increase in translocation frequencies was on the order of 12-fold in progenies from sperm utilized 11–13 days after treatment when the sperm were stored at 25°C, and 3- to 6-fold when comparable sperm were stored at 12.5°C. Consistent but much smaller increases in frequencies of sex-linked lethals were found, with the increase in lethals tending to be correlated with relative increase in translocation frequency in a given experiment. On the assumption that sex-linked lethals related to chromosome breakage would be expected to increase in frequency in the same proportion as do translocations, approximate agreement was obtained when the proportions of breakage-related lethals among unstored lethals were estimated from the data in the four experimental series. The data are thus consistent with the hypothesis that chromosome breaks but not point mutations are realized during storage of treated spermatozoa. Possible interpretations of a differential effect of storage on treated chromosomes are discussed.Studies carried out while the author was a guest investigator at the Institute of Animal Genetics on sabbatical leave from the University of Minnesota.     

Effects of storing x-rayed spermatozoa on the frequency of translocations and sex-linked lethalsin Drosophila melanogaster

Summary x-rayed adult males ofDrosophila melanogaster were left with untreated females from 2 to 3 days after which the males were discarded. Sex-linked recessive lethals and translocations were scored in progeny produced during the first 2 or 3 days following irradiation, and after storage of the spermatozoa in the females for 6 days.The results obtained show that the frequencies of sex-linked lethals and of translocation involving the two large autosomes and the x-chromosome were unchanged by storage. In experiments in which Y, 2, 3 translocations were scored both the 2–3, and the Y translocations showed a slight increase. These experiments show that the strong storage effect on translocations produced by certain alkylating agents is peculiar to chromosomes treated by these chemicals.Guest investigator at the Institute of Animal Genetics, Edinburgh, on leave from Assuit University Egypt.     

A preliminary assessment of possible mutagenicity of betel nut and ingredients of the betel quid when administered alone or in combinations to larvae of Drosophila melanogaster.

The "carcinogenic" betel nut and constituents of betel quid were tested for possible mutagenicity in Drosophila. The test compounds were administered either alone or in combinations by larval feeding. The data on sex-chromosome loss, sex-linked recessive lethals and autosomal translocations suggest lack of mutagenicity.     

Recessive lethals induced by ethyl methanesulfonate and diethyl sulfate in Drosophila melanogaster post-meiotic male cells pre-treated with butylated hydroxytoluene

The response of Drosophila melanogaster male germ cells to the induction of mutation by ethyl methanesulfonate (EMS) and diethyl sulfate (DES) and the influence of pre-treatments with butylated hydroxytoluene (BHT) were studied. Careful sampling of cell stages revealed that fully mature motile sperm were less sensitive to the induction of sex-linked recessive lethals by EMS than late spermatids, and that the remaining cell stages presented a fairly homogeneous response to the mutagen. The frequency of lethals induced by DES could be grouped into two plateaus: the first one, with a higher mutation rate, comprised motile and immotile sperm and late spermatids, the second one, medium and early spermatids. No sparing action of BHT was detected in any of the developing germ cells treated with EMS or DES, whereas an increase in sex-linked recessive lethal frequency was observed in some experiments in early spermatids. The enhancement of damage is attributed to impairment of repair achieved through the ability of BHT to modify enzymic activity.     

Keine Mutationsauslösung durch 5-Äthyl-2′-desoxyuridin (ÄDU) bei Drosophila melanogaster

Summary The rate of sex-linked recessive lethals as well as of translocations between 2^nd and 3^rd chromosome was determined in a multipurpose strain ofDrosophila melanogaster after intraperitoneal injection of 5-ethyl-2-deoxyuridine. No mutations, however, were observed after that treatment. These findings confirm the results of other investigators with T-2-phages and are in good agreement with theoretical considerations.     

The cytogenetics of mutator gene-induced X-linked lethals in Drosophila melanogaster

A third chromosome mutator gene effectively increases the spontaneous frequency of sex-linked recessive lethals in females but not in females of Drosophila melanogaster. Approximately half the mutator-induced mutants occur as clusters of the same mutant implying a premeiotic origin. An appreciable number of the mutator-induced lethals are associated with comparatively long deficiencies of several salivary gland chromosome bands. The possible modes of mutator gene action are conjectured.     

Investigations on radiosensitive and radioresistant populations of Drosophila melanogaster: XI. The resistance factor rar-3: effects in inmature oocytes

The effects of the radioresistance factor rar-3 on the X-ray induction of various types of genetic damage in immature oocytes (about stage7) of Drosophila melanogaster were studied.

The dose-reduction factors previously postulated for rar-3 with respect to dominant lethals (1.58), sex-linked recessive lethals (1.87), non-disjunction of major chromosomes (1.58), and homologous interchanges (1.58)_were confirmed experimentally. It is concluded that all effects attributed arbitrarily to rar-3 are contributed by the single genetic factor rar-3.

No difference were found in quality of sex-linked recessive lethals (Y suppression, distribution over the X) induced in either rar-3 or rar-3⁺. Recombination frequencies were normal in unirradiated rar-3.     

Modification of radiation-induced genetic damage in Drosophila melanogaster male germ cells with nucleic acid precursors. 3. Effects on the premeiotic cells

Using a 2-day brood pattern, the effect of 5-bromodeoxyuridine (BUdR) or 5-bromodeoxycytidine (BCdR) pre-treatment on the radiation-induced yield of sex-linked recessive lethals and translocations was studied in the spermatocytes and late gonial cells (p.i. DNA synthesis cells) of D. melanogaster. The p.i. DNA synthesis cells were irradiated (I.2 kR γ-radiation) in the pre-meiotic or post-meiotic stage. Irradiation of p.i. DNA synthesis cells in the pre-meiotic stage resulted in enhanced lethal frequency with BUdR (3.0%) and BCdR (2.9%) over the other pre-treatment conditions: saline (S), thymidine (TdR) and deoxycitydine (CdR) in the spermatocytes but not in the late gonial cells. The radiosensitizing property was evident with BCdR even when the p.i. DNA synthesis cells were irradiated in the post-meiotic stage; but not with BUdR pre-treatment. Probable reasons for the contradicting results reported in the literature were discussed.     

Effect of low temperature on radiation-induced genetic damage in Drosophila melanogaster: response of motile sperm and late spermatids.

The response of fully mature motile sperm and late spermatids when challenged with X-radiation at 0 degrees C has been studied in sex-linked recessive lethals, II-III translocations and dominant lethality experiments. At 0 degrees C a significant increase in both mutagenic and clastogenic damage was detected compared to that obtained at 24 degrees C. Furthermore, the results of experiments performed with different postirradiation temperatures demonstrate that the low temperature during irradiation was the sole factor responsible for the observed increase. In the recessive lethal and translocation tests the response of late spermatids was higher than that shown by motile spermatozoa. As a whole, the results, which are rather similar to data reported on the effect of irradiation in oxygen of the same cell stages, suggest that the low temperature acted as a dose-modifying factor.