Wings Of Flies Research Articles

GEOMETRIC MORPHOMETRICS OF DEVELOPMENTAL INSTABILITY: ANALYZING PATTERNS OF FLUCTUATING ASYMMETRY WITH PROCRUSTES METHODS.

Although fluctuating asymmetry has become popular as a measure of developmental instability, few studies have examined its developmental basis. We propose an approach to investigate the role of development for morphological asymmetry by means of morphometric methods. Our approach combines geometric morphometrics with the two-way ANOVA customary for conventional analyses of fluctuating asymmetry and can discover localized features of shape variation by examining the patterns of covariance among landmarks. This approach extends the notion of form used in studies of fluctuating asymmetry from collections of distances between morphological landmarks to an explicitly geometric concept of shape characterized by the configuration of landmarks. We demonstrate this approach with a study of asymmetry in the wings of tsetse flies (Glossina palpalis gambiensis). The analysis revealed significant fluctuating and directional asymmetry for shape as well as ample shape variation among individuals and between the offspring of young and old females. The morphological landmarks differed markedly in their degree of variability but multivariate patterns of landmark covariation identified by principal component analysis were generally similar between fluctuating asymmetry (within-individual variability) and variation among individuals. Therefore there is no evidence that special developmental processes control fluctuating asymmetry. We relate some of the morphometric patterns to processes known to be involved in the development of fly wings.

Antigenotoxicity studies in Drosophila melanogaster

The fruit fly Drosophila melanogaster with its well developed array of genotoxicity test systems has been used in a number of studies on antigenotoxicity of various compounds and mixtures. In recent years, the newly developed Somatic Mutation and Recombination Tests (SMART) have mainly been employed. These one-generation tests make use of the wing or eye imaginal disc cells in larvae and have proven to be very efficient and sensitive. They are based on the principle that the loss of heterozygosity of suitable recessive markers can lead to the formation of mutant clones of cells that are then expressed as spots on the wings or eyes of the adult flies. We have employed the wing spot test with the two markers multiple wing hairs ( mwh, 3-0.3) and flare ( flr, 3–38.8). Three-day-old larvae, trans-heterozygous for these markers, are treated chronically or acutely by oral administration with the test compound(s) or complex mixtures. For antigenotoxicity studies, chronic co-treatments can be used, as well as separate pre-treatments with an antigenotoxic agent followed by a chronic treatment with a genotoxin. After eclosion, the wings of the adult flies are scored for the presence of single and twin spots. These spots can be due to different genotoxic events: either mitotic recombination or mutation (deletion, point mutation, specific types of translocation, etc.). The analysis of two different genotypes (one with structurally normal chromosomes, one with a multiply inverted balancer chromosome) allows for a quantitative determination of the recombinagenic activity of genotoxins. Results of two separate studies are presented: (1) instant coffee has antirecombinagenic but not antimutagenic activity in the wing spot test; and (2) ascorbic acid and catechin are able to protect against in vivo nitrosation products of methyl urea in combination with sodium nitrite.

Vestigial gene expression in Drosophila melanogaster is modulated by the dTMP pool.

The vestigial (vg) gene of Drosophila melanogaster encodes a nuclear protein which plays a key role in wing formation but is also involved in other developmental processes. We have previously shown that depletion of the dTMP pool by aminopterin, an inhibitor of the enzyme dihydrofolate reductase, or by fluorodeoxyuridine, an inhibitor of thymidylate synthetase, induces nicks in the wings of wild-type flies and a strong vg phenotype in vgBG/+ flies and also in individuals heterozygous for a deficiency of the vg locus (vgB/+). Furthermore, specific alterations of the vg locus, caused by intronic insertions, are associated with resistance to these drugs. In this paper, we show that: (1) depletion of the dTMP pool by aminopterin leads to a decrease in the amount of vg transcripts; (2) insertion of the retrotransposon 412 in the vgBG mutant, which is resistant to aminopterin, leads to the formation of a truncated transcript that is prematurely terminated in the long terminal repeat of this transposable element; and (3) aminopterin also affects the level of this truncated transcript. These results indicate that alterations of the wing by inhibitors of dTMP synthesis are caused by an effect of these drugs on levels of vg transcripts; the resistance to such agents observed for the vgBG strain is not due to a qualitatively different effect of this drug on the vg transcript but, rather, is related to the expression of a modified Vg protein encoded by a truncated transcript. These results are compatible with a role for vestigial in modulating cell proliferation.

The response of Drosophila parabipectinata to simulated courtship songs

Abstract. Apparatus for simulating the long and short songs of Drosophila parabipectinata , and for measuring and specifying their sound particle velocity level is described, together with methods for observing courtship behaviour in the presence of the simulated songs. Removal of both wings of male flies significantly reduced their courtship success but removal of only one wing had no significant effect: this shows that the wings, as sound producers, are important for courtship success. Simulated D. parabipectinata short song significantly increased the locomotor activity of, and number of courtship interactions between, wingless male flies in the absence of female flies when played at sound levels of 78-84 dB. At 114-120 dB, although the flies became very active, the number of courtship interactions was not significantly different from that with silence at the start of the experiment. Pre-stimulation with simulated long song at 84 dB for 5 min followed by simulated short song at 84 dB during courtship significantly enhanced mating by wingless male D. parabipectinata compared with silence, or with stimulation during courtship by simulated short song alone or by long song alone.

Somatic mutation in the wings of Drosphila melanogaster females dysgenic due to P elements when reared at 29°C

The possibility of somatic mobilisation of P elements in Drosphila melanogaster was investigated. Flies, trans-heterozygous for the genetic markers mwh and flr 3 were obtained by crossing males containing transposition-competent P elements with females having M cytotype. The hybrid dysgenic flies were reared at 29°C and their wings examined for mutant clones. The frequency of mutant spots found on the wings of the female flies was significantly higher than that of female control flies. We postulate that this increase in frequency may be due to P element mobilisation at high temperature in the wing cells of dysgenic hybrids. This is in direct contrast to the large body of reasearch which indicates that P-transposition-mediated mutation is restricted to the germline.

Selection on wing allometry in Drosophila melanogaster.

Five bivariate distributions of wing dimensions of Drosophila melanogaster were measured, in flies 1) subjected to four defined environmental regimes during development, 2) taken directly from nature in seven U.S. states, 3) selected in ten populations for change in wing form, and 4) sampled from 21 long inbred wild-type lines. Environmental stresses during development altered both wing size and the ratios of wing dimensions, but regardless of treatment all wing dimensions fell near a common allometric baseline in each bivariate distribution. The wings of wild-caught flies from seven widely separated localities, and of their laboratory-reared offspring, also fell along the same baselines. However, when flies were selected divergently for lateral offset from these developmental baselines, response to selection was rapid in every case. The mean divergence in offset between oppositely selected lines was 14.68 SD of the base population offset, after only 15 generations of selection at 20%. Measurements of 21 isofemale lines, founded from wild-caught flies and maintained in small populations for at least 22 years, showed large reductions in phenotypic variance of offsets within lines, but a large increase in the variance among lines. The variance of means of isofemale lines within collection localities was ten times the variance of means among localities of newly established wild lines. These observations show that much additive genetic variance exists for individual dimensions within the wing, such that bivariate developmental patterns can be changed in any direction by selection or by drift. The relative invariance of the allometric baselines of wing morphology in nature is most easily explained as the result of continuous natural selection around a local optimum of functional design.

Vestigal mutants of Drosophila melanogaster live better in the presence of aminopterin: Increased level of dihydrofolate reductase in a mutant

Vestigial (vg) mutants of Drosophila melanogaster are characterized by atrophied wings. In this paper we show that: (1) aminopterin an inhibitor of dihydrofolate reductase (DHFR) and fluorodeoxyuridine (FUdR), an inhibitor of thymidylate synthetase induce nicks in the wings of wild-type flies and phenocopies of the vg mutant phenotype when vg/+ and vgB/+ flies are reared on these substances (vgB is a deficiency of the vg locus). Only thymidine and thymidylate can rescue the flies from the effect of aminopterin. We propose that the vg phenotype is due to a decrease in the dTMP pool in the wings. (2) Mutant vg strains yield more offspring on medium containing aminopterin than on normal medium. The resistance of vg larvae to the inhibitor seems specific to the gene. This is the first case of aminopterin resistance in living eucaryotes. In contrast sensitivity of the vg larvae to FUdR is observed. (3) An increase in the activity and amount of DHFR is observed in mutant strains as compared with the wild-type flies. Our data suggest that the vg+ gene is a regulatory gene acting on the DHFR gene or a structural gene involved in the same metabolic pathway.

Mitochondrial DNA and life span changes in normal and dewinged Drosophila at different temperatures

At 11 and 30 °C there was no change in the amount or in the bouyant density of nuclear DNA of male Oregon R Drosophila melanogaster with aging. When normal flies were maintained at 11 °C (at which temperature they do not fly), mitochondrial DNA content declined gradually with aging and 39.4% of the original mitochondrial DNA was lost at the median survival time of 152 days of age. For normal flies maintained at 30 °C, 86.5% of the mitochondrial DNA was lost during aging at the median survival time of 25 days. In contrast only a 39.2% decrease in the mitochondrial DNA occurred in dewinged flies maintained at 30 °C. A slow phase of mitochondrial DNA loss appears to be related to aging and a fast phase to flight activity. Removing the wings of flies eliminates the fast phase of DNA loss but only slightly improves life span (by less than 10%). Lowering the environmental temperatures to 11 °C also eliminates fast phase DNA loss and decreases the rate of the slow phase DNA loss. We conclude that mitochondrial DNA loss is related to both physical activity and to the aging process itself.

Genotoxicity of 5-azacytidine in somatic cells of Drosophila

The newly developed somatic mutation and recombination test, utilizing the wing-hair mutations mwh and flr3, was used to evaluate the genotoxicity of the base analog 5-azacytidine in larvae of Drosophila melanogaster. Third instar larvae were fed media wetted with various concentrations of the compound, and wings of surviving adults were removed and scored for the presence of clones of cells possessing malformed hairs. Wings of exposed flies trans-dihybrid for mwh and flr3 had significantly increased frequencies of twin spots, small single spots and large single spots. Significant linear regression of twin-spot frequencies upon concentration was also obtained. Induction of twin spots by 5-azacytidine unambiguously demonstrates its recombinogenic activity in somatic cells of Drosophila. Significantly increased frequencies of large single spots on wings of inversion-heterozygous flies were also observed and suggest that 5-azacytidine may also be inducing somatic gene mutations (or deletions).

The central projections of mesothoracic sensory neurons in wild-type Drosophila and bithorax mutants

Sensory axons entering the CNS from large campaniform sensilla on the normal, mesothoracic wings of four-winged flies of the genotype bx 3pbx Ubx 130 follow the same two tracts as do the corresponding axons in wild-type flies. However, they produce more branches along the ventromedial tract (including some in the mesothoracic neuromere), more fibers crossing the midline in the metathorax, and several other modifications of the wild-type pattern. No morphological differences between the receptors in normal and mutant flies could be detected, even with the SEM. The extra branching and other altered characteristics are present in bithorax flies which are also genetically wingless and do not form the homeotic appendages, so they appear to be due to the bx 3pbx Ubx 130 or bx 3 Ubx 130 genotype and not to some effect of the axons from the homeotic wings.

Clonal analysis of two wing-scalloping mutants of Drosophila

Development in two wing-scalloping mutants ( scalloped and vestigial) was analysed in mosaic flies. In strong alleles of these mutants the wings are reduced to vestiges. When a temperature-sensitive allele of scalloped was treated with heat pulses, particular wing areas were eliminated in a specific order. Homozygous mutant clones were made in heterozygous flies: Marginal clones in either the dorsal or ventral wing surface caused local scalloping, affecting both surfaces to the same extent. Internal Minute + clones survived well when surrounded by weaker Minute cells, but poorly when surrounded by normal Minute + cells. Large Minute + clones of either scalloped or vestigial could make distal parts that are never seen in the wings of mutant flies.

Relation of Sexual Dimorphism in the Wings, Potential Stridulation, and Illumination to Mating of Oriental Fruit Flies1, Melon Flies1, and Mediterranean Fruit Flies1 in Hawaii3

The wings of male oriental fruit flies, Dacus dorsalis Hendel; melon flies, D. cucurbitac Coquillett; and Mediterranean fruit flies, Ceratitis capitata (Wiedemann), all have deeper and more sharply incised wing margins at the distal tip of Cu1+1A than the females. However, the difference is most evident in melon flies and least evident in Mediterranean fruit flies. In addition, the male Mediterranean fruit fly has an emargination at the terminus of M3+M4 that is not found in the female. Any supposed mating call of male oriental fruit flies or melon flies resulting from stridulation of the wings on the abdominal cilia (or produced in any other manner) was not necessary for mating and insemination, judged from the percentages of egg hatch for females paired in an ambient laboratory environment with males with the wings removed. Male Mediterranean fruit flies do not have abdominal cilia.

Morphogenic effects of halogenated thymidine analogues on Drosophila. I. Quantitative analysis of lesions induced by 5-bromodeoxyuridine and 5-fluorouracil

When 5-fluorouracil (FU) is offered simultaneously with 5-bromodeoxyuridine (BUdR) to Drosophila larvae, a variety of bristle modifications and hyperplastic growths are found on the wings of the adult flies. Administration of FU alone will not stimulate growth in Drosophila, while high concentrations of BUdR offered alone will induce a lower frequency of growth modifications than induced by BUdR plus FU. Comparison of the morphological response induced by sequential treatment with the two analogues and that by simultaneous treatment with the analogues at the same concentrations indicates that maximum response is achieved by the presence of both analogues at the same time. These observations suggest that BUdR may be the primary agent in upsetting morphogenesis in Drosophila, while FU plays a subsidiary role leading to intensification of the morphogenic effects when it is present during the treatment period. The incorporation of BUdR-H3 and FU-H3 in Drosophila tissues was demonstrated by autoradiography. BUdR-H3 was incorporated in nuclei of both larval and imaginal disc cells, and the isotopic label was removable by deoxyribonuclease. Following dietary administration of FU-H3, tritium was found in RNA, primarily in cytoplasmic regions. Since BUdR is a known mutagen, consideration was given to the hypothesis that the altered growth patterns in Drosophila wings are the result of somatic cell mutational events induced by BUdR. Validity of the argument that recessive mutations on the X chromosomes can be readily expressed in the somatic cells of the male with one X chromosome as opposed to the female with two X chromosomes was tested by comparing the frequency of the induced somatic cell lesions in male and female zygotes. The males showed a higher frequency of induced supernumeraries, while the icidence of bristle effects and total wings affected was the same in both sexes.

Temperature Effects on Day Old Drosophila Pupae

Day old Drosophila pupae were subjected to a variety of closely controlled temperature shocks. Twenty-five hours after puparium formation (at 23 degrees ), temperatures from 39.5-41.5 degrees (Q(1) = 2.3) differentially disturb the formation of the posterior crossvein. Three other separate treatments disturb posterior crossvein formation: treatments in the range 36.0-37.0 degrees at 25 hours; 37.3-37.8 degrees at 25 hours; and 39.5-41.5 degrees at 19 hours. Certain qualitative effects are associated with certain temperatures: elliptical holes are seen in wings of flies exposed 25 hours after puparium formation to temperatures from 37.3-37.8 degrees . Anterior crossvein defects ensue if animals are similarly exposed to temperatures from 37.9-38.2 degrees . Within the physiological range, animals raised at higher temperatures are more resistant to the effects of temperatures at 39.5-41.5 degrees . An extremely rapid temperature adaptation by exposures to temperatures in the range 31-38 degrees results in markedly greater resistance to heat shock; here resistance to production of crossvein defects increases faster than to death. The association between qualitative effects and treatment temperatures is modified by changing the temperature at which the animals spend their first day of pupal life. Summation experiments support conclusions drawn from the simpler experiments. Genetic variation and interspecific variation are discussed in the present context, as well as implications of the role of protein denaturation in the biological effects of high temperatures and further, more general experiments.

The structure of the heterochromatic part of the Y-chromosome in Drosophila buscki.

In the salivary glands of D. buscki the Y-chromosome was at first shown to be a small euchromatic element whose length is about 1/24 of the Xchromosome, and consisting of some 14-15 bands.l1 2 In ganglial metaphases, this Y-chromosome has the form of a tapering rod, narrow at the proximal end which carries a small knob-like thickening; the length is about equal to the X-chromosome. This non-correspondence between the appearance of the Y-chromosome in the two types of cells was attributed to a heterochromatic or inert part, which is greatly reduced in relation to length, or apparently absent, in salivary glands. Until recently few attempts were made to identify such heterochromatic elements in salivary gland cells. It has been shown previously that the Y-chromosome in D. buscki is necessary for the life of males: XO-males die at an early stage of the development.3-5 As a result of a comprehensive cytogenetic investigation on the Y-chromosome in D. buscki, it has been possible to clarify the role of constituent parts in some detail, and to show their action on the development of males. In particular, it has been shown that the Y-chromosome is two-armed: the right, short arm, is the knob-like thickening at the proximal end, and is the euchromatic element in the salivaries; the left, long arm, is the inert heterochromatic part (unpublished). New information concerning the structure of this inert part has also been obtained in the course of this work, and is reported in the present paper. Experimental Data.-The material for this work was the mutant line CurledY(404) obtained in an F, from crossing X-rayed males to wild type females. The ends of the wings of the mutant flies are bent upwards. This mutant behaves genetically as Y-linked, that is, it is inherited from father to son. Among the offspring of mutant males, about 10-12% of non-mutant males appear. This last class of males have a slightly shortened body, and are completely sterile. Cytological analysis of the mutant males shows a break in region 7 of IIR. The proximal part of the broken IIR usually pairs fully with its

A Study on the Closely Linked Genes, Miniature and Dusky, in <i>Drosophila virilis</i>, with some Considerations on the Allelism of Genes

(1) The phenotypes of various miniatures and duskies, m1, m4, m7. m10, dy1, and dy4, found in D. virilis, have been studied by measuring the wings of female flies as indicated in Fig. 3. The absolute lengths have been reduced to lengths, relative to the intercostal length. The results are shown in Table 1.(2) m1 gives by far the strongest effect, the effect of the other miniature genes decreasing in the order of m1, m7. m4, m10; the effect of dy1 is slightly stronger than that of dy4.(3) All the mutant genes are incompletely recessive to the wildtype; the heterozygotes are more or less different from both homozygotes and wild-type. The degree of this difference is roughly parallel to the degree of divergence between the homozygotes and the wild-type.(4) Of the compounds of the mutant genes, those with m1 are all intermediate between m1 and the homozygote of the other gene; m4/m7 and m7/m10 are nearly identical with m4/m4 and m10/m10 respectively, while m4/dy1 and m4/dy4 depart to a smaller degree from the wild-type than do the respective homozygotes, m4/m4, dy1/dy1 and m4/m4, dy4/dy4, from the latter. These findings indicate the allelism of the different kinds of miniatures (or duskies) and are non-allelism of miniature and dusky.(5) From m7/dy1 females, a few crossover wild-type males have been obtained, the recombination value being 0.115 percent in one series of experiments and 0.0336 in the other series.(6) Thus, miniature and dusky are mutants of different loci very closely linked and having similar characters.(7) The relation between miniature and dusky is compared with that between achaete and scute in D. melanogaster.(8) Since the recombination values mentioned above probably represent about the lowest possible normal value, they can be made the basis from which the number of gene loci separable by crossing-over in this species may be calculated. This is about 1480 for the X-chromosome and 8000 for the whole haploid chromosome set, according to one series of experiments, and about 5060 for X and more than 25000 for the whole set, according to the other. The estimate given first roughly coincide with those previously made for D. melanogaster and are probably more accurate.

THE EFFECT OF INCREASING TIME OF DEVELOPMENT AT CONSTANT TEMPERATURE ON THE WING SIZE OF VESTIGIAL OF DROSOPHILA MELANOGASTER

The time of development of an isogenic vestigial stock of D. melanogaster was increased by two methods: (1) by adding nipagin (ethyl parahydroxy benzoate) to the food, and (2) by adding only very little yeast to the food. Both methods are essentially the same in that the developing larvae are under starvation conditions. With increasing concentration 0.05, 0.1, 0.2 and 0.4 per cent, there was an increase in the time of development and increase in the size of the wings, males showing a greater effect than females. The large wings resembled those of other vestigial alleles raised under normal conditions.In another series of experiments 0.1 per cent nipagin and starvation were used. The larvae were removed from the culture as they pupated, to determine the relation between time of pupation and wing size. The first flies to pupate did not differ significantly in wing size from controls at that temperature. With increasing time of development there was an increase in wing size. Larvae which were very much delayed, however, developed into small flies with small wings. These wings, although small, were more differentiated and larger than the control wings.The "carry-over" effect was studied using normal food. The treated females and males were mated with control males and females respectively. Treated males were also mated with treated females. The wings of flies from the latter mating showed the greatest carry-over effect. Treated females by control males resulted in flies having a significantly larger wing size than flies from the reciprocal cross. These results indicate that there is a definite effect on the germ cells of flies raised under starvation conditions, which effect shows itself in the subsequent development of the zygote.