Abdominal pigmentation in Drosophila melanogaster females from natural Indian populations

Females of Drosophila melanogaster collected from five geographically distant populations in India were analysed for the intensity of pigmentation in the 5th, 6th and 7th segments of the abdomen. In all three segments, this intensity was found to vary among individuals of any given population, and, furthermore, different populations differ with respect to this phenotypic trait. Statistical analysis revealed significant intra- and interpopulational variation. A clinical pattern was detected: females from populations closer to the equator tended to have lighter cuticle, in which case differences between the three segments could not be detected and all three segments responded both independently and jointly to latitudinal variation, as indicated by a statistically significant positive correlation between latitude and pigmentation score. This is the first report on abdominal pigmentation analysis in natural populations of D. melanogaster that provides evidence that phenotypic flexibility reflects temperature differences, as a result of which abdominal pigmentation shows geographic differentiation.     

Ambient temperature affects free-flight performance in the fruit fly Drosophila melanogaster

To gain insight into how temperature affects locomotor performance in insects, the limits of flight performance have been estimated in freely flying fruit flies Drosophila melanogaster by determining the maximum load that a fly could carry following take-off. At a low ambient temperature of 15 °C, muscle mechanical power output matches the minimum power requirements for hovering flight. Aerodynamic force production rises with increasing temperature and eventually saturates at a flight force that is roughly equal to 2.1 times the body mass. Within the two-fold range of different body sizes, maximum flight force production during free flight does not decrease with decreasing body size as suggested by standard aerodynamic theories. Estimations of flight muscle mechanical power output yields a peak performance of 110 W kg⁻¹ muscle tissue for short-burst flight that was measured at an ambient temperature of 30 °C. With respect to the uncertainties in estimating muscle mechanical power during free flight, the estimated values are similar to those that were published for flight under tethered flight conditions. Accepted: 5 January 1999     

Remating and male-derived nutrients in Drosophila melanogaster

Laboratory natural selection and environmental manipulations were used to investigate the importance of male-derived nutrients to female Drosophila melanogaster. No evidence for the importance of such nutrients was found. Females from the same wild type base stock exposed as adults to low quality food did not show elevated fecundity or survival when they remated more frequently, and on high quality food the females showed a ‘cost of mating’ in reduced survival. Laboratory evolution on low quality food did not lead to elevated rates of remating by females; females from each selection regimen remated more frequently than one another when kept on the food type to which they had been exposed for the previous 5 years, on which they also showed higher fecundity than one another. Even under conditions of extreme nutritional stress, when females were exposed to short term (4-day) cycle of exposure to very low and high quality food, they remated more frequently immediately after exposure to high quality food. The results of this last experiment suggested that, under these circumstances, current nutrition, fecundity or rate of sperm usage was more important than number of sperm in store or cumulative fecundity in determining the probability that a female would remate.     

The genetic basis of adaptive pigmentation variation in Drosophila melanogaster

In a broad survey of Drosophila melanogaster population samples, levels of abdominal pigmentation were found to be highly variable and geographically differentiated. A strong positive correlation was found between dark pigmentation and high altitude, suggesting adaptation to specific environments. DNA sequence polymorphism at the candidate gene ebony revealed a clear association with the pigmentation of homozygous third chromosome lines. The darkest lines sequenced had nearly identical haplotypes spanning 14.5 kb upstream of the protein-coding exons of ebony. Thus, natural selection may have elevated the frequency of an allele that confers dark abdominal pigmentation by influencing the regulation of ebony.     

The dynamics of height stabilization in Drosophila

ABSTRACT. Frequency analysis of the height stabilizing system in Drosophila hydei Sturtevant was performed by moving a striped pattern sinusoidally up and down around free-flying flies. The results show that height is controlled by the flies' vertical acceleration which is set linearly by the velocity of image movement past their eyes in the vertical direction, with a lag of 0.05 s at 25C. No evidence was found of any reaction to the position of the striped pattern relative to the eyes. The gain of the vertical acceleration-controlling reaction decreased with increasing frequency of visual stimulation. The dynamics of this decrease showed that it was not brought about by an integration step in the movement detector, but was due to the flies reaching the limit to the rate at which they could change their acceleration. The reaction time of the flies decreased with increasing temperature from 0.1 s at 15C to 0.04 s at 30C; the gain of the reaction increasing with temperature. When the vertical acceleration and the vertical velocity were determined every 0.02 s, the acceleration rather than the velocity was proportional to the flies' lift, and they took at least 0.3 s to reach their terminal velocity. This means that the acceleration-controlling response found here is equivalent to the lift-controlling responses of tethered flies.     

Plasticity of Drosophila melanogaster wing morphology: effects of sex, temperature and density

In this paper we use an adjusted ellipse to the contour of the wings of Drosophila as an experimental model to study phenotypic plasticity. The geometric properties of the ellipse describe the wing morphology. Size is the geometric mean of its two radii; shape is the ratio between them; and, the positions of the apexes of the longitudinal veins are determined by their angular distances to the major axis of the ellipse. Flies of an inbred laboratory strain of Drosophila melanogaster raised at two temperatures (16.5°C and 25°C) and two densities (10 and 100 larvae per vial) were used. One wing of at least 40 animals of each sex and environmental condition were analyzed (total = 380), a measurement of thorax length was also taken. Wing size variation could be approximately divided into two components: one related to shape variation and the other shape independent. The latter was influenced primarily by temperature, while the former was related to sex and density. A general pattern could be identified for the shape dependent variation: when wings become larger they become longer and the second, fourth and fifth longitudinal veins get closer to the tip of the wing. This revised version was published online in July 2006 with corrections to the Cover Date.     

Drosophila melanogaster males respond differently at the behavioural and genome‐wide levels to Drosophila melanogaster and Drosophila simulans females

Drosophila melanogaster are found in sympatry with Drosophila simulans, and matings between the species produce nonfertile hybrid offspring at low frequency. Evolutionary theory predicts that females choose mates, so males should alter their behaviour in response to female cues. We show that D. melanogaster males quickly decrease courtship towards D. simulans females. Courtship levels are reduced within 5 min of exposure to a heterospecific female, and overall courtship is significantly lower than courtship towards conspecific females. To understand changes at the molecular level during mate choice, we performed microarray analysis on D. melanogaster males that courted heterospecific D. simulans females and found nine genes have altered expression compared with controls. In contrast, males that court conspecific females alter expression of at least 35 loci. The changes elicited by conspecific courtship likely modulate nervous system function to reinforce positive conspecific signals and dampen the response to heterospecific signals.     

Adaptive diversity in genetic control of egg-laying behavior in Drosophila melanogaster

Summary

In the absence of insemination or of a suitable oviposition site, Drosophila melanogaster females react with egg retention patterns which differ as to the position in the genital tract at which the mechanism operates (ovarioles for initial retention; uterus for oviposition blocking) and to physiological basis. A study of the first laboratory generation of isofemale lines, founded by using three different samples of wild flies collected the same year from a natural population, showed a significant genetic variability in initial egg retention by virgin females and in the capacity for oviposition blocking by mated flies reacting to an unfavorable oviposition site. Comparison of isofemale lines showed that these two adaptive behavior patterns also differ in their genetic determination. They are controlled, and therefore can react, independently to selection pressures resulting from seasonal variation in the natural environment.     

Two novel LEM-domain proteins are splice products of the annotated Drosophila melanogaster gene CG9424 (Bocksbeutel)

The LEM motif is a sequence of 40-50 amino acids that has been identified in a number of non-related proteins of the inner nuclear membrane including the lamina-associated polypeptides 2 (LAP2), emerin, MAN1 and the Drosophila protein otefin. This evolutionary conserved sequence motif can mediate via the interaction with the small protein BAF the binding of LEM-domain proteins to DNA. Taking advantage of its sequenced genome we analyzed whether Drosophila possesses beside otefin additional genes coding for proteins with a LEM motif. A putative candidate gene was the annotated gene CG9424 which we named Bocksbeutel. Of all putative Drosophila LEM-domain proteins, otefin and Bocksbeutel exhibited the highest similarity in the LEM motif (53% identical amino acids). The Bocksbeutel gene can code for two isoforms of 399 and 351 amino acids that are produced by alternative splicing. In the alpha-isoform a transmembrane domain is localized close to the carboxyterminus. This segment is absent in the shorter beta-isoform. By RT-PCR we could show that in the embryo the mRNA coding for the alpha-isoform and in significantly lower amounts the mRNA coding for the beta-isoform are expressed. When expressed in transfected cells as GFP fusion proteins, the beta-isoform is localized predominantly in the nucleoplasm and the alpha-isoform is targeted to the nuclear envelope, indicating that Bocksbeutel-alpha is localized in the inner nuclear membrane. Bocksbeutel-alpha is the predominant isoform expressed in cells, larvae, and flies. Indirect immunofluorescence with Bocksbeutel-specific antibodies on tissues and cultured cells revealed that Bocksbeutel proteins are localized in the nuclear envelope and in the cytoplasm. By RNA interference we have down-regulated the expression of Bocksbeutel, BAF, otefin, and lamin DmO in Drosophila Kc167 cells. The down-regulation of Bocksbeutel and otefin had no influence on the viability of Kc167 cells and the intracellular localization of all other nuclear and nuclear envelope proteins analyzed. In contrast, when lamin DmO was reduced by RNAi the distribution of Bocksbeutel and otefin in the nuclear envelope of Kc167 cells was significantly altered. We conclude that the two LEM-domain proteins Bocksbeutel and otefin are no limiting components for the maintenance of the nuclear architecture in cultured Drosophila cells at interphase.     

frizzled Gene expression and development of tissue polarity in the Drosophila wing

Almost every cell in the Drosophila pupal wing forms a single, distally pointing cuticular hair. The function of the frizzled (fz) gene is essential for the elaboration of the normal wing hair pattern. In the absence of fz function hairs develop, but they display an abnormal polarity. We have examined the developmental expression of the fi gene at the RNA level via in situ hybridization and at the protein level via Western blotting. We have found that fz is expressed in all regions of the epidermis before, during, and after the fz cold sensitive period. We have also found that fz function is not required for normal fi expression. We have further found that mutations in several other tissue polarity genes do not noticeably alter the expression or the modification state of the Fz protein. © 1994 Wiley-Liss, Inc.     

Constitutive heterochromatin and transposable elements in Drosophila melanogaster

Several families of transposable elements (TEs), most of them belonging to the retrotransposon catagory, are particularly enriched in Drosophila melanogaster constitutive heterochromatin. The enrichment of TE-homologous sequences into heterochromatin is not a peculiar feature of the Drosophila genome, but appears to be widespread among higher eukaryotes. The constitutive heterochromatin of D. melanogaster contains several genetically active domains; this raises the possibility that TE-homologous sequences inserted into functional heterochromatin compartments may be expressed. In this review, I present available data on the genetic and molecular organization of D. melanogaster constitutive heterochromatin and its relationship with transposable elements. The implications of these findings on the possible impact of heterochromatic TEs on the function and evolution of the host genome are also discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Simulation of gene pyramiding in Drosophila melanogaster

Gene pyramiding has been successfully practiced in plant breeding for developing new breeds or lines in which favorable genes from several different lines were integrated.But it has not been used in animal breeding,and some theoretical investigation and simulation analysis with respect to its strategies,feasibility and efficiency are needed before it can be implemented in animals.In this study,we used four different pure fines of Drosophila melanogaster,each of which is homozygous at a specific mutant gene with a visible effect on phenotype,to simulate the gene pyramiding process and analyze the duration and population size required in different pyramiding strategies.We finally got the ideal individuals,which are homozygous at the four target genes simultaneously.This study demonstrates that gene pyramiding is feasible in animal breeding and the interaction between genes may affect the final results.     

Development of the genitalia in Drosophila melanogaster

The imaginal discs of Drosophila melanogaster are an excellent material with which to analyze how signaling pathways and Hox genes control growth and pattern formation. The study of one of these discs, the genital disc, offers, in addition, the possibility of integrating the sex determination pathway into this analysis. This disc, whose growth and shape are sexually dimorphic, gives rise to the genitalia and analia, the more posterior structures of the fruit fly. Male genitalia, which develop from the ninth abdominal segment, and female genitalia, which develop mostly from the eighth one, display a characteristic array of structures. We will review here some recent findings about the development of these organs. As in other discs, different signaling pathways establish the positional information in the genital primordia. The Hox and sex determination genes modify these signaling routes at different levels to specify the particular growth and differentiation of male and female genitalia.     

Simulation of gene pyramiding in Drosophila melanogaster

Gene pyramiding has been successfully practiced in plant breeding for developing new breeds or lines in which favorable genes from several different lines were integrated.But it has not been used in animal breeding,and some theoretical investigation and simulation analysis with respect to its strategies,feasibility and efficiency are needed before it can be implemented in animals.In this study,we used four different pure lines of Drosophila melanogaster,each of which is homozygous at a specific mutant gene ...     

Mechanisms of early neurogenesis in Drosophila melanogaster

The neuroectoderm of insects contains an initially indifferent population of cells which during later development will give rise to the progenitor cells of the neural and epidermal lineages. Experimental evidence indicates that cellular interactions determine which cells will adopt each one of these fates. Transplantation experiments suggest that a signal with neuralising character is required to stabilize the primary neural fate in 25% of all the neuroectodermal cells, which will develop as neuroblasts, and that an epidermalising signal contributes to suppress the neural fate in the remaining 75% of the cells, allowing in this way their development as epidermal progenitor cells. The invoked cell interactions are assumed to be mediated by the products of several genes forming a complex, not yet well understood network of interrelationships. Elements of this network are the proteins encoded by Delta and Notch, which appear to convey the regulatory signals between the cells; the proteins encoded by the achaete-scute gene complex, which regulate neural development; and the proteins encoded by the Enhancer of split gene complex, which give neuroectodermal cells access to epidermal development. © 1993 John Wiley & Sons, Inc.