The DNA content of polytene nuclei in midgut and Malpighian tubule cells of adultDrosophila melanogaster

Summary The amounts of DNA in midgut and Malpighian tubule cells of adult maleDrosophila melanogaster have been determined by Feulgen-DNA cytophotometry. The DNA values fall into discrete classes reflecting different levels of polyteny. The maximum level is 64C in the midgut, 256C in Malpighian tubules, and the modal values are 32C and 128C respectively. The data provide no evidence for extensive underreplication of heterochromatin. It is suggested that the reduced amount of satellite DNA found in the tissues of young adult flies may be a consequence of the fact that cycles of DNA replication started in the pre-adult stages are not completed until some hours after eclosion.     

Rover/sitterDrosophila melanogaster larval foraging polymorphism as a function of larval development,food-patch quality,and starvation

The genetically based rover/sitter behavioral difference in Drosophila melanogasterlarval foraging is expressed throughout most of the larval instars when larvae forage on food patches of differing food quality. The amount of locomotor behavior decreases when third-instar larvae of both rover and sitter strains are starved just prior to the behavioral test. Such strain differences in locomotor behavior are maintained despite the starvation-induced decrease in locomotion found in both strains. Measurements of larval body length and width, taken at 24, 48, 72, and 96 h posthatching, reveal that rover and sitter larval growth rates do not differ. The finding that rover/sitter differences are expressed in a variety of environments and throughout the majority of the larval instars should aid in attempts to uncover selection pressures which may differentially affect the two morphs in environmentally heterogeneous natural populations.     

Multiple mating and sperm displacement in a natural population of Drosophila melanogaster

Summary Mother-offspring data for alcohol dehydrogenase genotypes of a vineyard cellar population of D. melanogaster are best explained by a model that allows 21% of females in the population to mate twice with an 83% level of sperm displacement. A population model with multiple mating and sperm displacement is examined theoretically. A formula for the effective population size is derived under this model. Multiple mating increases the effective population size relative to single mating.     

Inbreeding depression and male-mating behavior inDrosophila melanogaster

There have been relatively few studies designed to investigate the effects of inbreeding on behavioral traits. To study this phenomenon, five experimental lines ofDrosophila melanogaster made isogenic for chromosome 2 were evaluated for their male-mating ability and, subsequently, male courtship behavior. All lines showed significant reductions in overall mating ability, and males from all of these lines displayed impaired mating behavior, with two lines displaying particularly aberrant courtship patterns. Line 16 displayed an inability to successfully initiate copulation following successful courtship, while line 17 displayed significant reduction in locomotor activity, resulting in virtually no successful courtship or copulatory activity. The implications of these findings for competitive mating ability in wildDrosophila populations are presented. Further, the importance of mating success as a fitness component in the management of potentially highly inbred populations of endangered species is discussed.     

Development time and pupation behavior in theDrosophila melanogaster subgroup (Diptera: Drosophilidae)

This study is an in-depth analysis of intersexual, intraspecific, and interspecific variability in larvopupal developmental time, pupation site preference, and larval and pupal survival of a number of isofemale lines of the speciesDrosophila mauritiana, D. melanogaster, D. sechellia, D. simulans, D. teissieri, andD. yakuba. There was no significant sex differences in pupation height, but females eclosed significantly earlier than males in all species. In addition, the suggestion of a strong negative correlation between larval developmental time and pupation height could not be confirmed in this study. The hypothesis that differences in pupation height provide a basis for niche partitioning between closely related species with overlapping distributions was tested by three planned orthogonal contrast analyses of variance. First, the two speciesD. teissieri andD. yakuba, with largely overlapping distribution, were significantly different in pupation height. Second, the two allopatric, nonoverlapping island speciesD. mauritiana andD. sechellia did not significantly differ in pupation height. However, the absence of a significant difference in the final contrast between the two cosmopolitan speciesD. melanogaster andD. simulans, which are often found together, makes us cautious to accept the hypothesis.     

Biological and Behavioral Effects of Heavy Metals in Drosophila melanogaster Adults and Larvae

Heavy metals are essential components of biological systems but are extremely toxic at high doses. As a result, we hypothesized that perception of heavy metals through gustation may exist in Drosophila melanogaster. In this study, we investigated the behavioral effects of iron, copper, zinc, and cadmium on D. melanogaster gustation, oviposition, and pupation-site selection. In addition, we examined the biological effects of heavy metals on the fruit fly survival and reproductive success. Our results illustrate that D. melanogaster responds behaviorally to the presence of high concentrations of heavy metals in food. All metals acted as repellents to the fruit flies at high doses, with the egg-laying and feeding of the female flies significantly decreasing. Furthermore, supplementation of heavy metals in the culture medium reduced survival to the adult stage and shortened the life span of adult flies. From these observations, we speculate that D. melanogaster avoidance behavior towards high concentrations of heavy metals may have a positive effect on their survival and reproductive success in nature, particularly in the presence of metal-contaminated food sources.     

The foraging locus: behavioral tests for normal muscle movement in rover and sitter Drosophila melanogaster larvae

We used Drosophila melanogaster larvae with different alleles at the foraging (for) locus in a variety of behavioral tests to evaluate normal muscle usage of rover and sitter phenotypes. The results show that sitter and lethal sitter alleles of for do not affect larval behavior through a mutation which affects larval muscle usage. In general the behavior of rovers and sitters differed on food but not on non-nutritive substrates. Rovers and sitters moved equally well on non-nutritive substrates, and measures such as the time to roll over and length of forward stride showed no significant strain differences. Larvae with different alleles at for did not differ in body length. Rovers took more strides, not longer ones, than sitters while on foraging substrates. We conclude that differences in larval locomotion during foraging found in larvae with different alleles at for can not be explained on the basis of muscle usage alone. It is more likely that for affects larval ability to perceive or respond to the foraging environment.     

Rover/sitter foraging behavior inDrosophila melanogaster: Genetic localization to chromosome2L using compound autosomes

Genetic control of the rover/sitter behavioral polymorphism in Drosophila melanogasterlarvae was localized to the left arm of chromosome 2.Ten independent left and right compound second chromosomes were generated in isogenic rover and sitter strains by gamma irradiation and substituted into 25 different lines. Comparisons were made between lines to determine the chromosome arm contributions to rover/sitter phenotype expression.     

Phenotypic expression of ADH regulatory genes inDrosophila melanogaster: a comparative study between a paleartic and a tropical population

In vitro ADH activity was studied inD. melanogaster males from two sets of third chromosome substitution lines, one from a paleartic population (Gigean, France), the other from a tropical population (Brazzaville, Congo). As a linear model with raw ADH activity dependent on fresh weight was significant in both sets of lines, the raw activity was adjusted by regression on weight. Two main results were found: (a) the well-known substantial intrapopulation variability; and (b) third chromosome geographical origin did not affect the mean ADH activity. Unlike the structuralAdh gene polymorphism which allows the two populations to be distinguished, the polymorphism of the third chromosome ADH regulatory genes (or more exactly their phenotypic expression) does not allow to discriminate between them. These results are discussed in the context of the adaptation ofD. melanogaster to the alcoholic substrates in light of a model proposed by Hedrick and McDonald (1980) in order to interpret variations in both structural and regulatory gene polymorphisms.     

Utilization of a Photosystem by Drosophila melanogaster Larvae (Diptera: Drosophilidae)

Foraging-stage third-instar larvae from most wild-type (normal) Drosophila melanogaster stocks are generally repelled by light. To identify factors that affect the larval photoresponse, we elucidated the effects of age, temperature, and time on the photoresponse of larvae from a wild-type Canton-S stock. In addition, we analyzed the larvae from the LI2 isofemale line, which are unresponsive to light in a photoassay. To determine whether LI2 larvae behave abnormally on other behavioral paradigms, in comparison to Canton-S controls, we tested larvae in taste and olfactory assays and observed them to determine whether they dispersed in a food source. Like Canton-S larvae, LI2 larvae and other isofemale lines whose progenitors were collected from the same natural population are responsive to taste and olfactory stimuli. Moreover, LI2 larvae disperse in the food source, as do Canton-S larvae tested in the dark. Larvae expressing para^sbl mutations, which respond normally to light but not to chemical stimuli, do not disperse normally in the food source, suggesting that dispersal may be mediated by perception of chemical cues.     

Courtship inDrosophila sechellia: Its structure,functional aspects,and relationship to those of other members of theDrosophila melanogaster species subgroup

The courtship behavior of Drosophila sechelliais described. Male wing displays are mainly vibration and scissoring, with low levels of rowing. As courtship proceeds the proportion of courtship spent in male wing vibration and licking increases, whereas female movement decreases. The male courtship song of sechelliacontains pulse song but no sine song. This species also shows a distinctive copulation song associated with mounting and copulation. The main cuticular hydrocarbon in females is 7,11-heptacosadiene. The number of copulations increased when flies were placed in the presence of food. Visual and acoustic stimuli appear to be important for mating. A multidimensional comparison was used to compare members of the melanogaster species subgroup, based upon courtship behavior, song characteristics, and cuticular hydrocarbons. A multidimensional comparison of courtship sequences in sechellia, melanogaster, simulans,and mauritianashowed differences in variability between the two island species as compared to the two cosmopolitan species. The courtship song of D. orenais described: it shows both sine and pulse song; there is also a copulation song in this species.     

Development of behavioral competence in youngDrosophila melanogaster adults

We have monitored the ontogeny of several behaviors performed by young Drosophila melanogasteradults. Very young flies are less active than older flies and are less responsive to gravity, light, an odorant, and sucrose applied to their tarsi. In addition, very young males do not consume sucrose or perform any courtship behaviors in response to virgin females, which provide chemical and visual stimuli to courting males. The rate at which flies become maximally competent to respond to stimuli is a function of the behavior. Sensory and motor deficits are not solely responsible for young flies' inability to respond to the stimuli, which suggests that the central nervous system continues to develop after eclosion.Deceased     

World-wide variation inDrosophila melanogaster sex pheromone: behavioural effects, genetic bases and potential evolutionary consequences

InDrosophila melanogaster, male wing vibration, a key element of courtship behaviour, is most efficiently induced by a female-specific contact pheromonecis, cis 7,11 heptacosadiene (7, 11 HD), which is the main mature female cuticular hydrocarbon in the CS laboratory strain. A study of 63 strains from around the world revealed that flies from Sub-Saharan Africa and the Caribbean are unique in showing low levels 7,11 HD and high levels of the position isomer 5,9 HD. This difference maps to chromosome III, perhaps indicating a simple genetic control of the 7,11 HD: 5,9 HD ratio. Females from strains with high levels of 7,11 HD showed higher levels of mating and mated more rapidly than females with low levels of 7,11 HD. The results are discussed in light of recent discoveries of genetic differences betweenD. melanogaster strains from Africa and those from elsewhere around the world.     

Clonal analysis in hybrids between Drosophila melanogaster and Drosophila simulans

We have analysed the viability of cellular clones induced by mitotic recombination in Drosophila melanogaster/D. simulans hybrid females during larval growth. These clones contain a portion of either melanogaster or simulans genomes in homozygosity. Analysis has been carried out for the X and the second chromosomes, as well as for the 3L chromosome arm. Clones were not found in certain structures, and in others they appeared in a very low frequency. Only in abdominal tergites was a significant number of clones observed, although their frequency was lower than in melanogaster abdomens. The bigger the portion of the genome that is homozygous, the less viable is the recombinant melano-gaster/simulans hybrid clone. The few clones that appeared may represent cases in which mitotic recombination took place in distal chromosome intervals, so that the clones contained a small portion of either melanogaster or simulans chromosomes in homozygosity. Moreover, Lhr, a gene of D. simulans that suppresses the lethality of male and female melanogaster/simulans hybrids, does not suppress the lethality of the recombinant melanogaster/simulans clones. Thus, it appears that there is not just a single gene, but at least one per tested chromosome arm (and maybe more) that cause hybrid lethality. Therefore, the two species, D. melanogaster and D. simulans, have diverged to such a degree that the absence of part of the genome of one species cannot be substituted by the corresponding part of the genome of the other, probably due to the formation of co-adapted gene complexes in both species following their divergent evolution after speciation. The disruption of those coadapted gene complexes would cause the lethality of the recombinant hybrid clones.     

The influence of age and experience with conspecifics on territorial behavior inDrosophila melanogaster

Drosophila melanogastermales initiated aggressive behavior toward other males and defended territories several hours after they were able to court and mate females. Males that were 3 days or more posteclosion were more successful at holding territories than younger males. Three-day-old males established territories more readily and escalated more often against territory residents than males that were 1 day old. Residents did not usually force young males from territories until they were a few hours posteclosion. The development of territorial behavior was not affected by familiarity or prior exposure to females. Males held in isolation established territories more quickly and behaved more aggressively than males held in groups. Males that previously held territories were more likely to reestablish them after a disturbance.     

Genetic Variants Affecting Phenoloxidase Activity in Drosophila melanogaster

In Drosophila melanogaster, two new variants affecting the activity of phenoloxidase were found in natural populations at Gomel in Belorussia and at Krasnodar in Russia. Prophenoloxidases, A ₁ and A ₃ , in these variants had the same mobilities on native electrophoresis as the wild type. However, enzymatic activities in their activated states were much lower than in the wild type, whereas the existence of prophenoloxidase proteins was demonstrated. Egg-to-adult and relative viabilities in the variants did not decrease at temperatures between 18 and 29°C. Genetic analyses indicated that the genes showing the phenotype of variants are new alleles of Mox and Dox-3 on the second chromosome.     

Drosophila melanogaster P Transposable Elements: Mechanisms of Transposition and Regulation

The molecular mechanisms that control P element transposition and determine its tissue specificity remain incompletely understood, although much information has been compiled about this element in the last decade. This review summarizes the currently available information about P element transposition, P-M hybrid dysgenesis and P cytotype features, P element-encoded repressors, and regulation of transposition.     

The pattern of proliferation of the neuroblasts in the wild-type embryo of Drosophila melanogaster

Summary The pattern of neuroblast divisions was studied in thoracic and abdominal neuromeres of wild-type Drosophila melanogaster embryos stained with a monoclonal antibody directed against a chromatin-associated antigen. Since fixed material was used, our conclusions are based upon the statistical evaluation of a large number of accurately staged embryos, covering the stages between the formation of the cephalic furrow up to shortened germ band. Our observations point to a rather stereotypic pattern of proliferation, consisting of several parasynchronous cycles of division. The data suggest that all SI neuroblasts divide at least eight times, all SII neuroblasts six or seven times and all SIII neuroblasts at least five times. This conclusion is based on the mapping of mitotic neuroblasts and is supported by the progressive reduction of the neuroblast volume and by the results of cell countings performed on embryos of increasing age. No conclusive evidence was obtained concerning the fate of the neuroblasts after their last mitosis, i.e. it cannot be decided whether the neuroblasts degenerate or become incorporated as inconspicuous cells in the larval ventral cord. The duration of the cycles of division of the neuroblasts was found to be 40–50 min each, while in the case of ganglion mother cells about 100 min are required to complete one cell cycle.