Effects of caffeine on chromosomal loss and nondisjunction in Drosophila melanogaster

Three types of male larvae, normal X males and two types with structurally abnormal X chromosomes (ring X and short X sc ⁴ sc ³, y) were treated during the third instar with 0.5 per cent caffeine in nutrient medium. Upon eclosion, these males were mated to yellow and Oregon-R wild type females. The F₁ generation of each cross was scored for normal (XX and XY) and abnormal (XO and XXY) progeny. Statistical analyses of data demonstrate that caffeine increases chromosomal loss for all genotypes tested. The effect of caffeine on nondisjunction, however, is not clear. There are at least marginal increases in all cases when Oregon-R females are used. Slight increase and decreases noted for offspring of yellow females appear to be dependent upon the genotype of the inseminating male.     

Effects of hyperthermia on radiation-induced chromosome breakage and loss in excision repair deficient Drosophila melanogaster

Hyperthermia increased radiosensitivity with respect to gamma-ray induced chromosome loss and breakage in all stages of spermatogenesis in the wild type Oregon R strain of Drosophila melanogaster, whereas hyperthermia increased radiosensitivity to a lesser extent in cn mus (2) 201D1, an excision repair mutant with 0 per cent excision capacity and in mus (3) 308D1, a strain with 24 per cent excision capacity. The differences in hyperthermia-induced radiation sensitivity between the excision repair mutants and the wild strain may be due to the hyperthermia affecting the excision repair mechanism, suggesting that one of the possible mechanisms involved in hyperthermia-increased radiosensitivity is an effect on excision repair.     

The effect of caffeine on repair systems in oocytes of Drosophila melanogaster. I

Young Drosophila females were treated with caffeine, then mated for 24 h to males that had been irradiated with 2000 R X-irradiation, so that only mature spermatozoa were sampled. The radiation-induced frequency of dominant lethals and sex chromosome loss in the paternal genome was determined. The results show that treatment of females with caffeine leads to an increase in the frequencies of radiation-induced dominant lethals and to sex-chromosome loss.When young virgin females of the radioresistant stock RöI₂ were treated with caffeine and then irradiated with 3000 R X-irradiation, a striking increasein dominant lethals (in the maternal genome) was observed; caffeine treatment increased the X-ray response of the radioresistant stock to the level of the normal (+60) stock. It is suggested that caffeine reduces the efficiency of a system in Drosophila oocytes that repairs X-ray-produced chromosome breaks in both the paternal and maternal genomes.     

Hyperthermia increases chromosome breakage and loss induced by fission neutrons in Drosophila melanogaster

Pretreatment with hyperthermia did significantly increase the breakage and chromosome loss induced by 0.85-MeV fission neutrons from the JANUS biological research reactor in spermatozoa, early and late spermatids and spermatocytes. Radiation-induced breakage of chromosomes was also enhanced by hyperthermia in early spermatogonia.     

Aneuploidy in Drosophila, I. Genetic test systems in the female Drosophila melanogaster for the rapid detection of chemically induced chromosome gain and chromosome loss

An account is provided of two genetic schemes in the Drosophila melanogaster female designed as rapid detectors of chemically induced aneuploidy, including both chromosome gain and chromosome loss. One scheme is referred to as FIX, in which the female carried free (heterozygously) inverted X (chromosomes) and the other, ZESTE, where females do not carry inversions and the X-linked sexually dimorphic zeste mutation plays the key role in the detection of aneuploid offspring. The principle attribute of the FIX system is that all euploid offspring are wild-type for body and eye color whereas aneuploid females have a yellow body and aneuploid males white eyes; int he ZESTE system all euploid individuals are wild-type for eye color, aneuploid females possess zeste-colored eyes and aneuploid males white eyes. In addition induced polyploidies (2X:2A gametes) appear as yellow and zeste male intersexes in the FIX and ZESTE systems, respectively. In this way all aneuploids are recognized immediately. Consequently, detection of compounds with weak effects requiring large sample sizes may be made in a fraction of the time associated with more traditional schemes for aneuploidy detection in Drosophila.     

X-ray induction of autosomal translocations in spermatozoa of Drosophila melanogaster and maternal effects of X.Y-chromosomes.

Wild-type ORK Drosophila melanogaster males were given an exposure of 3000 R X-radiation. Mature sperm were then sampled by mating to X.Y/X.Y, X.Y/X, or X/X females that carried markers on the second and third chromosomes for the detection of induced autosomal translocations. Two pairs of maternal stocks were used and heterozygous X.Y/X females were obtained by making both reciprocal crosses. The highest frequencies of induced translocations were obtained with X/X females. In one series these frequencies are higher than those obtained with either X.Y/X or X.Y/X.Y females. In the other series a uniform frequency of translocations was obtained with all types of female, except for one of the two types of heterozygous female, which gave lower frequencies. The experiments have provided data which show that the addition of Y-chromosomes to the maternal genome does not have a specific effect on the recovery of induced paternal autosomal translocations. Maternal Y-chromosomes increased the proportions of fertile F1 males, this effect being consistent in direction but varying in degree.     

The repair-deficient mei-9a drosophila female potentiates chromosome loss induced in the paternal genome by diethylnitrosamine

Following matings of DEN-treated X^c2/B^SYy⁺ males with repair-deficient mei-9^a females and ordinary females, significant increases in complete and partial sex chromosome loss as well as dramatic shifts in sex ratio were found with mei-9^a but not ordinary females. Accordingly, the mei-9^a female enhances the detection of chromosome lesions leading to chromosome loss induced in the male genome by DEN. To date, the 4 compounds tested in this way (DMN, DEN, MMS and procarbazine) exhibit strong potentiation of chromosome loss with mei-9^a females suggesting the possibility that a protocol involving treatment (or not) of X^c2/B^sYy⁺ males mated with mei-9^a females may hold promise as an alternative to traditional tests for chromosome loss using repair-proficient females. Comparison with published translocation data on the 4 compounds indicated above suggests an overall greater sensitivity of the described mei-9^a chromosome-loss test compared with the traditional translocation test in the detection of chemically induced chromosome lesions.     

Hyperthermia of male Drosophila melanogaster meiocytes induces abnormalities in both paternal and maternal sex chromosome sets of the offspring

Nondisjunction and loss of sex chromosomes caused by exposure of male Drosophila melanogaster to heat shock (HS) (37 degrees C for 1 h) has been studied to determine the role of mutation l(1)ts403 (sbr10) in the control of chromosome segregation during cell division. Hyperthermia of males at the pupal stage has been demonstrated to increase the number of offspring with abnormalities of not only paternal, but also maternal sex chromosome sets. According to the criterion used, there is a temperature-sensitive period of spermatogenesis, which presumably coincides with meiosis. Phenotypes of some individuals correspond to the presence of two sex chromosomes of obtained from the same parent. The frequency of abnormal chromosome sets in the offspring of male carriers of the sbr10 mutation is about two times higher than in the offspring of males without this mutation.     

Mosaicism induced by the loss of chromosome X and/or IV in cand mutants of Drosophila melanogaster

A pattern of cuticular mosaicism for X-chromosome markers and for haplo-4 Minute phenotype was studied. Losses of either X- or IV-chromosomes were found to occur mainly in the first two cleavage divisions, being several times higher in the 1st one. X- or IV-chromosomes may be lost either separately or together, the nonrandom coincidence of joint losses in the successive divisions being observed in the latter case. No proliferation delay was found due to Minute (4) gene hemizygosity while this condition caused some enhancement in ssak expression (intersegmental fusions in tarsi) and pronounced suppression of the Hw effect.     

Effect of fagaronine on chromosome breaks and loss in Drosophila melanogaster

Fagaronine, a potent antileukemic agent, was shown to induce chromosome breaks and loss in sperm of Drosophila melanogaster.