Determination of the Spontaneous Locomotor Activity in Drosophila melanogaster

Drosophila melanogaster has been used as an excellent model organism to study environmental and genetic manipulations that affect behavior. One such behavior is spontaneous locomotor activity. Here we describe our protocol that utilizes Drosophila population monitors and a tracking system that allows continuous monitoring of the spontaneous locomotor activity of flies for several days at a time. This method is simple, reliable, and objective and can be used to examine the effects of aging, sex, changes in caloric content of food, addition of drugs, or genetic manipulations that mimic human diseases.     

Correlated changes in circadian clocks in response to selection for faster pre-adult development in fruit flies Drosophila melanogaster

Although, circadian clocks are believed to be involved in the regulation of life-history traits such as pre-adult development time and lifespan in fruit flies Drosophila melanogaster, there is very little unequivocal evidence either to support or refute this. Here we report the results of a long-term study aimed at examining the role of circadian clocks in the temporal regulation of pre-adult development in D. melanogaster. We employed laboratory selection protocol for faster pre-adult development on four large, outbred, random mating populations of Drosophila. We assayed pre-adult development time and circadian period of locomotor activity rhythm of these flies at regular intervals of 5–10 generations. After 50 generations of selection, the overall egg-to-adult duration in the selected stocks was reduced by ~29 h (~12.5 %) relative to controls, with the selected populations showing a concurrent reduction in time taken to hatching, pupation and wing pigmentation, by ~2, ~16, and ~25.2 h, respectively. Furthermore, selected populations showed a concomitant reduction in the circadian period of locomotor activity rhythm, implying that circadian clocks and development time are correlated. Thus, our study provides the first ever unequivocal evidence for the evolution of circadian clocks as a correlated response to selection for faster pre-adult development, suggesting that circadian clocks and development are linked in fruit flies D. melanogaster.     

Mutagen sensitivity of Drosophila melanogaster. I. Isolation and preliminary characterization of a methyl methanesulphonate-sensitive strain

Sensitivity to the monofunctional alkylating agent methyl methanesulfonate (MMS) has been tested as a selection technique to isolate mutant strains which can provide insights into the genetic control of DNA replication, DNA repair and recombination in the complex eucaryote, Drosophila melanogaster. The successful isolation of an X-linked MMS-sensitive strain, mut^s, has suggested that mutagen sensitivity is a feasible methodology for the selection of mutant strains of Drosophila which will be useful in the genetic and biochemical analysis of these cellular functions. Preliminary characterization of this mutant strain indicates that: (A) it is extremely sensitive to killing by MMS; (B) it is more mutable by MMS than the parent wildtype strain; and (C) it appears to possess mutator gene activity.     

Analysis of disproportionate replication of ribosomal DNA in Drosophila melanogaster by a microhybridization method

A microhybridization technique is described which requires only 1% of the starting material normally needed for filter-bound methods. Employing this technique, we have investigated the disproportionate replication (compensation) of ribosomal DNA in larval and adult stages of two strains of Drosophila melanogaster. Both stages of the Oregon R strain demonstrate XO compensation while neither stage of Canton S shows a significant elevation of ribosomal DNA content in XOs. It is demonstrated that the lack of disproportionate replication in the latter strain does not result from the absence of the genetic site cr⁺ which normally controls this process.     

The Response of Enzyme Polymorphisms to Developmental Rate Selection in DROSOPHILA MELANOGASTER

Two strains of Drosophila melanogaster derived from different geographical localities were subjected to selection for fast and slow developmental rate. Four enzyme polymorphisms were monitored for their response to such selection. Significant changes in allele frequencies were effected for the αGpdh and 6Pgd polymorphisms under fast developmental rate selection. The strain from Rhode Island exhibited a correlated change in body weight during developmental rate selection, whereas the Georgia strain did not.     

The Role of Storage Lipids in the Relation between Fecundity,Locomotor Activity,and Lifespan of Drosophila melanogaster Longevity-Selected and Control Lines

The contribution of insect fat body to multiple processes, such as development, metamorphosis, activity, and reproduction results in trade-offs between life history traits. In the present study, age-induced modulation of storage lipid composition in Drosophila melanogaster longevity-selected (L) and non-selected control (C) lines was studied and the correlation between total body fat mass and lifespan assessed. The trade-offs between fecundity, locomotor activity, and lifespan were re-evaluated from a lipid-related metabolic perspective. Fewer storage lipids in the L lines compared to the C lines supports the impact of body fat mass on extended lifespan. The higher rate of fecundity and locomotor activity in the L lines may increase the lipid metabolism and enhance the lipolysis of storage lipids, reducing fat reserves. The correlation between neutral lipid fatty acids and fecundity, as well as locomotor activity, varied across age groups and between the L and C lines. The fatty acids that correlated with egg production were different from the fatty acids that correlated with locomotor activity. The present study suggests that fecundity and locomotor activity may positively affect the lifespan of D. melanogaster through the inhibition of fat accumulation.     

Effects of different base populations on selection response in Drosophila

Of two laboratory strains of Drosophila melanogaster used in this study, the +3 strain had slightly higher mean abdominal bristle number and estimated heritability of this character than the Oregon‐R. Their F₁ hybrid exhibited 5 % heterosis. Fourteen generations of the two original strains and the F₃ of the hybrid were selected for high and low numbers of abdominal bristles on the 4th and 5th sternites, at a selection intensity of 20%. A mass‐mated unselected control was maintained for each population. The +3 population responded considerably more to selection for low numbers of bristles than high, and the Oregon‐R population showed a similar, though less marked, tendency; the Crossbred population responded more strongly to selection for high numbers. Except for the Crossbred high selection line, all lines declined in response rate, phenotypic variance, and realised heritability. The average realised heritability of the Oregon‐R and +3 high and low selection lines over 14 selection generations fell short of their predicted base population heritabilities. The deviation from the predicted was particularly pronounced with selection for high bristle number in the +3 line.     

Patterns of puffing activity in the salivary gland chromosomes of Drosophila

The autosomal salivary gland chromosome puffing patterns of Drosophila simulans are described and compared with the puffing patterns of the sibling species D. melanogaster. During the late third larval instar and the prepupal period the patterns of puffing activity of these two species are similar — approximately 50% of the puffs common to both species showing identical activities. The remaining puffs differ in their timing of activity, or in their mean sizes, or in both of these parameters. A number of puffs (14) found in D. simulans have not been regularly observed in the Oregon stock of D. melanogaster but are active in other D. melanogaster strains. One puff (46 A) of D. melanogaster was absent from D. simulans and forms a heterozygous puff in hybrids, when the homologous chromosomes are synapsed. When the homologues are asynapsed a puff at 46 A is restricted to the melanogaster homologue. The puff at 63E on chromosome arm 3L is considerably smaller in D. simulans than in D. melanogaster and this size difference is autonomous in hybrids. Other puffs not common to both species behave non-autonomously in the species hybrid, even when the homologous chromosomes are asynapsed.     

Consequences of selection in highly inbred <Emphasis Type="Italic">Drosophila</Emphasis> strains

The results of three long-term breeding and genetic experiments with Drosophila melanogaster performed at different times are summarized. Selections for different fitness components led to similar results. The data on the concentration of viability mutations in the inbred strains LA, LA⁺, and LA^? after 400 generations of selection and the strain ULA during its breeding are presented for the first time. The results of studying the genetic heterogeneity and spontaneous mutational process in Drosophila inbred strains comply with the idea of M.E. Lobashev that “a change in the direction of selection or acceleration of its rate is always accompanied by a concurrent increase in mutational variation.”     

Temperature-Related Divergence in Experimental Populations of DROSOPHILA MELANOGASTER. I. Genetic and Developmental Basis of Wing Size and Shape Variation

The effects of environmental temperature on wing size and shape of Drosophila melanogaster were analyzed in populations derived from an Oregon laboratory strain kept at three temperatures (18°, 25°, 28°) for 4 yr. Temperature-directed selection was identified for both wing size and shape. The length of the four longitudinal veins, used as a test for wing size variations in the different populations, appears to be affected by both genetic and maternal influences. Vein expression appears to be dependent upon developmental pattern of the wing: veins belonging to the same compartment are coordinated in their expression and relative position, whereas veins belonging to different compartments are not. Both wing and cell areas show genetic divergence, particularly in the posterior compartment. Cell number seems to compensate for cell size variations. Such compensation is carried out both at the level of single organisms and at the level of population as a whole. The two compartments behave as individual units of selection.     

Optimization of wrMTrck to monitor Drosophila larval locomotor activity

An efficient and low-cost method of examining larval movement in Drosophila melanogaster is needed to study how mutations and/or alterations in the muscular, neural, and olfactory systems affect locomotor behavior. Here, we describe the implementation of wrMTrck, a freely available ImageJ plugin originally developed for examining multiple behavioral parameters in the nematode C. elegans. Our optimized method is rapid, reproducible and does not require automated microscope setups or the purchase of proprietary software. To demonstrate the utility of this method, we analyzed the velocity and crawling paths of two Drosophila mutants that affect muscle structure and/or function. Additionally, we show that this approach is useful for tracking the behavior of adult insects, including Tribolium castaneum and Drosophila melanogaster.     

Frequency-Dependent Selection at the LAP Locus in DROSOPHILA MELANOGASTER

Results of fitness estimates for the Lap locus in Drosophila melanogaster revealed that under crowded media conditions gene frequency equilibrium was maintained by frequency-dependent selection. Evidence was obtained that indicated that mating and egg-to-adult viability were frequency dependent.     

Some Behavioral Features of Drosophila melanogasterStrains Carrying a flamencoGene Mutation

Olfactory sensitivity and locomotor activity was assayed in Drosophila melanogasterstrains carrying a mutation of the flamencogene, which controls transposition of retrotransposon gypsy. A change in olfactory sensitivity was detected. The reaction to the odor of acetic acid was inverted in flies of the mutator strain (MS), which carried the flammutation and active gypsycopies and were characterized by genetic instability. Flies of the genetically unstable strains displayed a lower locomotor activity. The behavioral changes in MS flies can be explained by the pleiotropic effect of the flammutation or by insertion mutations which arise in behavior genes as a result of genome destabilization by gypsy.     

Patterns of Nucleotide Diversity at the Regions Encompassing the Drosophila Insulin-Like Peptide (dilp) Genes: Demography vs. Positive Selection in Drosophila melanogaster

In Drosophila, the insulin-signaling pathway controls some life history traits, such as fertility and lifespan, and it is considered to be the main metabolic pathway involved in establishing adult body size. Several observations concerning variation in body size in the Drosophila genus are suggestive of its adaptive character. Genes encoding proteins in this pathway are, therefore, good candidates to have experienced adaptive changes and to reveal the footprint of positive selection. The Drosophila insulin-like peptides (DILPs) are the ligands that trigger the insulin-signaling cascade. In Drosophila melanogaster, there are several peptides that are structurally similar to the single mammalian insulin peptide. The footprint of recent adaptive changes on nucleotide variation can be unveiled through the analysis of polymorphism and divergence. With this aim, we have surveyed nucleotide sequence variation at the dilp1-7 genes in a natural population of D. melanogaster. The comparison of polymorphism in D. melanogaster and divergence from D. simulans at different functional classes of the dilp genes provided no evidence of adaptive protein evolution after the split of the D. melanogaster and D. simulans lineages. However, our survey of polymorphism at the dilp gene regions of D. melanogaster has provided some evidence for the action of positive selection at or near these genes. The regions encompassing the dilp1-4 genes and the dilp6 gene stand out as likely affected by recent adaptive events.     

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.     

Eine Methode zur Registrierung der Laufaktivität von kleinen Insekten

Summary The method described in this paper enables the locomotor activity of small insects to be recorded. It is based on variations in capacitance within a bridge circuit, the variations being due to movements of the animals. The method is adapted to the use of multi-channel action recorders, thus allowing a greater number of sensor units to be employed simultaneously.As an example of application, a comparison is made between the diurnal rhythmicity patterns of locomotor activity inDrosophila melanogaster andDrosophila azteca. Both species show maximal activity in the morning and in the evening.D. melanogaster is active throughout the middle of the day as well, butD. azteca, being adapted to an arid climate, shows a resting period during this time of day.

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Herrn Prof. Dr. Georg Birukow zum 60. Geburtstag gewidmet.     

The role of auditory stimuli in the courtship of Drosophila melanogaster

Simulated courtship song of male Drosophila melanogaster was played to males or females of this species. Upon receiving the song males increase their locomotor activity and start courting each other, whereas females reduce their locomotor activity. In wingless males the locomotor activity difference between the silent control and the experimental sound situation is much larger than in winged males, due to the inactivity of wingless males in the control situation. Males which had been kept singly up to the time of the experiment exhibit higher locomotor and sexual activity than group housed males. A second component of the male courtship song ‘sine song’ is described, together with experiments which investigate the sensory basis of the effect male courtship song has on males.     

Transplantation of nuclei into the polar plasm of Drosophila eggs

Nuclei of preblastoderm and blastoderm stages of yw strain of Drosophila melanogaster were transplanted into posterior ends of fertilized eggs of the v; bw strain. Several mosaics were obtained, including gynandromorphs with external genitalia of the donor's type. One mosaic was fertile, with gonads derived from the transplanted preblastodermic nuclei. Genetic analysis showed that the genome of these nuclei was not affected by differentiation or by transplantation.     

Spermidine promotes stress resistance in Drosophila melanogaster through autophagy-dependent and -independent pathways

The naturally occurring polyamine spermidine (Spd) has recently been shown to promote longevity across species in an autophagy-dependent manner. Here, we demonstrate that Spd improves both survival and locomotor activity of the fruit fly Drosophila melanogaster upon exposure to the superoxide generator and neurotoxic agent paraquat. Although survival to a high paraquat concentration (20 mM) was specifically increased in female flies only, locomotor activity and survival could be rescued in both male and female animals when exposed to lower paraquat levels (5 mM). These effects are dependent on the autophagic machinery, as Spd failed to confer resistance to paraquat-induced toxicity and locomotor impairment in flies deleted for the essential autophagic regulator ATG7 (autophagy-related gene 7). Spd treatment did also protect against mild doses of another oxidative stressor, hydrogen peroxide, but in this case in an autophagy-independent manner. Altogether, this study establishes that the protective effects of Spd can be exerted through different pathways that depending on the oxidative stress scenario do or do not involve autophagy.     

Investigation of Natural Genetic Variation in the Circadian System of Drosophila melanogaster. II. Biometrical Analyses of Locomotor Activity Rhythms Recorded in Constant Darkness

The locomotor activity rhythms of 24 isochromosomal strains of Drosophila melanogaster were recorded in constant conditions, using an experimental design suitable for the serial screening with so many strains using limited equipment. The data obtained were subjected to biometrical genetic analysis. The results show that four characteristics of the rhythms (period, phase, definition, and waveform) display genetically based variation in expression and that each appears to be affected by a range of genes.