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At least 199 records · Page 11Linked to original sources
PubMed2004

Ability of scalloped deletion constructs to rescue sd mutant wing phenotypes in Drosophila melanogaster.

Scalloped (SD) and Vestigial (VG) proteins physically interact to form a selector complex that activates genes involved in wing development in Drosophila melanogaster. SD belongs to a conserved family of transcription factors containing the TEA/ATTS DNA-binding motif. VG is also a nuclear protein providing the activator function for the SD VG complex. The TEA DNA-binding domain and the VG interacting domain (VID) of SD have been previously identified and described. However, they, and possibly other functional domains of SD, have not been thoroughly characterized in vivo. Herein, transgenic constructs encoding various truncations of SD were used to assess their respective ability to rescue the mutant wing phenotype of two viable sd recessive mutations (sd(ETX4) and sd(58d)). The transgenic strains produced were also tested for the ability to induce further sd expression, an ability possessed by full length SD. The functional dissection of SD confirms that specific regions are necessary for wing development and provides further information as to how the SD VG complex functions to promote wing fate. Previous experiments have shown that expression of full length SD can cause a dominant negative wing phenotype. We show that expression of constructs that delete the SD DNA-binding domain can also cause a dominant negative phenotype in a background with either of the two tester sd strains. In contrast, SD constructs that delete the VID have no effect on the wing phenotype in either tester background. Finally, a significant portion of SD at the N-terminal end appears to be dispensable with respect to normal wing development, as this construct behaves the same as full length SD in our assays.

Animals↗
PubMed2003

Genetic requirements of vestigial in the regulation of Drosophila wing development.

The gene vestigial has been proposed to act as a master gene because of its supposed capacity to initiate and drive wing development. We show that the ectopic expression of vestigial only induces ectopic outgrowths with wing cuticular differentiation and wing blade gene expression patterns in specific developmental and genetic contexts. In the process of transformation, wingless seems to be an essential but insufficient co-factor of vestigial. vestigial ectopic expression alone or vestigial plus wingless co-expression in clones differentiate 'mixed' cuticular patterns (they contain wing blade trichomes and chaetae characteristic of the endogenous surrounding tissue) and express wing blade genes only in patches of cells within the clones. In addition, we have found that these clones, in the wing imaginal disc, may cause autonomous as well as non-autonomous cuticular transformations and wing blade gene expression patterns. These non-autonomous effects in surrounding cells result from recruitment or 'inductive assimilation' of vestigial or wingless-vestigial overexpressing cells.

Animals↗
PubMed2003

Defective proventriculus is required for pattern formation along the proximodistal axis, cell proliferation and formation of veins in the Drosophila wing.

Many genes have been identified that are required for the establishment of the dorsoventral (DV) and anteroposterior (AP) axes of the Drosophila wing. By contrast, little is known about the genes and mechanisms that pattern the proximodistal (PD) axis. Vestigial (Vg) is instrumental in patterning this axis, but the genes that mediate its effects and the mechanisms that operate during PD patterning are not known. We show that the gene defective proventriculus (dve) is required for a region of the PD axis encompassing the distal region of the proximal wing (PW) and a small part of the adjacent wing pouch. Loss-of-function of dve results in the deletion of this region and, consequently, shortening of the PD axis. dve expression is activated by Vg in a non-autonomous manner, and is repressed at the DV boundary through the combined activity of Nubbin and Wg. Besides its role in the establishment of the distal part of the PW, dve is also required for the formation of the wing veins 2 and 5, and the proliferation of wing pouch cells, especially in regions anterior to wing vein 3 and posterior to wing vein 4. The study of the regulation of dve expression provides information about the strategies employed to subdivide and pattern the PD axis, and reveals the importance of vg during this process.

Animals↗
PubMed1996

The Drosophila Serum Response Factor gene is required for the formation of intervein tissue of the wing and is allelic to blistered.

The adult Drosophila wing is formed by an epithelial sheet, which differentiates into two non-neural tissues, vein or intervein. A large number of genes, many of them encoding components of an EGF-receptor signaling pathway, have previously been shown to be required for differentiation of vein tissue. Much less is known about the molecular control of intervein differentiation. Here we report that the Drosophila homolog of the mammalian Serum Response Factor gene (DSRF), which encodes a MADS-box containing transcriptional regulator, is expressed in the future intervein tissue of wing imaginal discs. In adult flies carrying only one functional copy of the DSRF gene, additional vein tissue develops in the wing, indicating that DSRF is required to spatially restrict the formation of veins. In mitotic clones lacking DSRF, intervein tissue fails to differentiate and becomes vein-like in appearance. Genetic and molecular evidence demonstrates that DSRF is encoded by the blistered locus, which produces ectopic veins and blistered wings when mutant. Our results show that DSRF plays a dual role during wing differentiation. It acts in a dosage-dependent [correction of dosage-dependant] manner to suppress the formation of wing veins and is required cell-autonomously to promote the development of intervein cells. We propose that DSRF acts at a key step between regulatory genes that define the early positional values in the developing wing disc and the subsequent localized expression of intervein-specific structural genes.

Alleles↗
PubMed2000

Restricted patterning of vestigial expression in Drosophila wing imaginal discs requires synergistic activation by both Mad and the drifter POU domain transcription factor.

The Drosophila Vestigial protein has been shown to play an essential role in the regulation of cell proliferation and differentiation within the developing wing imaginal disc. Cell-specific expression of vg is controlled by two separate transcriptional enhancers. The boundary enhancer controls expression in cells near the dorsoventral (DV) boundary and is regulated by the Notch signal transduction pathway, while the quadrant enhancer responds to the Decapentaplegic and Wingless morphogen gradients emanating from cells near the anteroposterior (AP) and DV boundaries, respectively. MAD-dependent activation of the vestigial quadrant enhancer results in broad expression throughout the wing pouch but is excluded from cells near the DV boundary. This has previously been thought to be due to direct repression by a signal from the DV boundary; however, we show that this exclusion of quadrant enhancer-dependent expression from the DV boundary is due to the absence of an additional essential activator in those cells. The Drosophila POU domain transcriptional regulator, Drifter, is expressed in all cells within the wing pouch expressing a vgQ-lacZ transgene and is also excluded from the DV boundary. Viable drifter hypomorphic mutations cause defects in cell proliferation and wing vein patterning correlated with decreased quadrant enhancer-dependent expression. Drifter misexpression at the DV boundary using the GAL4/UAS system causes ectopic outgrowths at the distal wing tip due to induction of aberrant Vestigial expression, while a dominant-negative Drifter isoform represses expression of vgQ-lacZ and causes severe notching of the adult wing. In addition, we have identified an essential evolutionarily conserved sequence element bound by the Drifter protein with high affinity and located adjacent to the MAD binding site within the quadrant enhancer. Our results demonstrate that Drifter functions along with MAD as a direct activator of Vestigial expression in the wing pouch.

Animals↗
PubMed2002

A characterization of the effects of Dpp signaling on cell growth and proliferation in the Drosophila wing.

Cell proliferation and patterning must be coordinated for the development of properly proportioned organs. If the same molecules were to control both processes, such coordination would be ensured. Here we address this possibility in the Drosophila wing using the Dpp signaling pathway. Previous studies have shown that Dpp forms a gradient along the AP axis that patterns the wing, that Dpp receptors are autonomously required for wing cell proliferation, and that ectopic expression of either Dpp or an activated Dpp receptor, Tkv(Q253D), causes overgrowth. We extend these findings with a detailed analysis of the effects of Dpp signaling on wing cell growth and proliferation. Increasing Dpp signaling by expressing Tkv(Q253D) accelerated wing cell growth and cell cycle progression in a coordinate and cell-autonomous manner. Conversely, autonomously inhibiting Dpp signaling using a pathway specific inhibitor, Dad, or a mutation in tkv, slowed wing cell growth and division, also in a coordinate fashion. Stimulation of cell cycle progression by Tkv(Q253D) was blocked by the cell cycle inhibitor RBF, and required normal activity of the growth effector, PI3K. Among the known Dpp targets, vestigial was the only one tested that was required for Tkv(Q253D)-induced growth. The growth response to altering Dpp signaling varied regionally and temporally in the wing disc, indicating that other patterned factors modify the response.

Animals↗
PubMed2004

Unsteady aerodynamic forces of a flapping wing.

The unsteady aerodynamic forces of a model fruit fly wing in flapping motion were investigated by numerically solving the Navier-Stokes equations. The flapping motion consisted of translation and rotation [the translation velocity (u(t)) varied according to the simple harmonic function (SHF), and the rotation was confined to a short period around stroke reversal]. First, it was shown that for a wing of given geometry with u(t) varying as the SHF, the aerodynamic force coefficients depended only on five non-dimensional parameters, i.e. Reynolds number (Re), stroke amplitude (Phi), mid-stroke angle of attack (alpha(m)), non-dimensional duration of wing rotation (Delta tau(r)) and rotation timing [the mean translation velocity at radius of the second moment of wing area (U), the mean chord length (c) and c/U were used as reference velocity, length and time, respectively]. Next, the force coefficients were investigated for a case in which typical values of these parameters were used (Re=200; Phi=150 degrees; alpha(m)=40 degrees; Delta tau(r) was 20% of wingbeat period; rotation was symmetrical). Finally, the effects of varying these parameters on the force coefficients were investigated. In the Re range considered (20-1800), when Re was above approximately 100, the lift ((L)) and drag ((D)) coefficients were large and varied only slightly with Re (in agreement with results previously published for revolving wings); the large force coefficients were mainly due to the delayed stall mechanism. However, when Re was below approximately 100, (L) decreased and (D) increased greatly. At such low Re, similar to the case of higher Re, the leading edge vortex existed and attached to the wing in the translatory phase of a half-stroke; but it was very weak and its vorticity rather diffused, resulting in the small (L) and large (D). Comparison of the calculated results with available hovering flight data in eight species (Re ranging from 13 to 1500) showed that when Re was above approximately 100, lift equal to insect weight could be produced but when Re was lower than approximately 100, additional high-lift mechanisms were needed. In the range of Re above approximately 100, Phi from 90 degrees to 180 degrees and Delta tau(r) from 17% to 32% of the stroke period (symmetrical rotation), the force coefficients varied only slightly with Re, Phi and Delta tau(r). This meant that the forces were approximately proportional to the square of Phi n (n is the wingbeat frequency); thus, changing Phi and/or n could effectively control the magnitude of the total aerodynamic force. The time course of (L) (or (D)) in a half-stroke for u(t) varying according to the SHF resembled a half sine-wave. It was considerably different from that published previously for u(t), varying according to a trapezoidal function (TF) with large accelerations at stroke reversal, which was characterized by large peaks at the beginning and near the end of the half-stroke. However, the mean force coefficients and the mechanical power were not so different between these two cases (e.g. the mean force coefficients for u(t) varying as the TF were approximately 10% smaller than those for u(t) varying as the SHF except when wing rotation is delayed).

Animals↗
PubMed2005

Dynamic pressure maps for wings and tails of pigeons in slow, flapping flight, and their energetic implications.

Differential pressure measurements offer a new approach for studying the aerodynamics of bird flight. Measurements from differential pressure sensors are combined to form a dynamic pressure map for eight sites along and across the wings, and for two sites across the tail, of pigeons flying between two perches. The confounding influence of acceleration on the pressure signals is shown to be small for both wings and tail. The mean differential pressure for the tail during steady, level flight was 25.6 Pa, which, given an angle of attack for the tail of 47.6 degrees , suggests the tail contributes 7.91% of the force required for weight support, and requires a muscle-mass specific power of 19.3 W kg(-1) for flight to overcome its drag at 4.46 m s(-1). Differential pressures during downstroke increase along the wing length, to 300-400 Pa during take-off and landing for distal sites. Taking the signals obtained from five sensors sited along the wing at feather bases as representative of the mean pressure for five spanwise elements at each point in time, and assuming aerodynamic forces act within the x-z plane (i.e. no forces in the direction of travel) and perpendicular to the wing during downstroke, we calculate that 74.5% of the force required to support weight was provided by the wings, and that the aerodynamic muscle-mass specific power required to flap the wings was 272.7 W kg(-1).

Acceleration↗
PubMed2006

Dual leading-edge vortices on flapping wings.

An experimental investigation was performed with two aims: (1) to clarify the existence of the dual leading-edge vortices (i.e. two vortices with the same sense of rotation located close to the leading edge above the leeward wing surface) observed on flapping wings in previous studies; (2) to study systematically the influences of kinematic and geometric parameters on such a vortical structure. Based on a scaled-up electromechanical model flapping in a water tank, the leading-edge vortex (LEV) cores were visualized via dye flow visualization, and the detailed sub-structures of LEV were revealed through digital particle image velocimetry (DPIV) with high spatial resolution. Five wing aspect ratios (AR) (1.3, 3.5, 5.8, 7.5 and 10), eight mid-stroke angles of attack (alpha(m)) (10-80 degrees), and six Reynolds numbers (Re) (160-3200) were examined. In addition, the well-studied case of the fruit fly Drosophila was re-examined. The results confirm for the first time the existence of dual LEVs on flapping wings. The sectional flow structure resembles the dual-vortex observed on non-slender delta wings. Insensitive to AR, a dual LEV system such as this could be created when alpha(m) and Re reached certain high levels. The primary vortex was attached to the wing, while at the outer wing the minor vortex shed, generating a same-sense vortex behind.

Animals↗
PubMed1993

The active control of wing rotation by Drosophila.

This paper investigates the temporal control of a fast wing rotation in flies, the ventral flip, which occurs during the transition from downstroke to upstroke. Tethered flying Drosophila actively modulate the timing of these rapid supinations during yaw responses evoked by an oscillating visual stimulus. The time difference between the two wings is controlled such that the wing on the outside of a fictive turn rotates in advance of its contralateral partner. This modulation of ventral-flip timing between the two wings is strongly coupled with changes in wing-stroke amplitude. Typically, an increase in the stroke amplitude of one wing is correlated with an advance in the timing of the ventral flip of the same wing. However, flies do display a limited ability to control these two behaviors independently, as shown by flight records in which the correlation between ventral-flip timing and stroke amplitude transiently reverses. The control of ventral-flip timing may be part of an unsteady aerodynamic mechanism that enables the fly to alter the magnitude and direction of flight forces during turning maneuvers.

Animals↗
PubMed2000

Soaring and non-soaring bats of the family pteropodidae (flying foxes, Pteropus spp.): wing morphology and flight performance.

On oceanic islands, some large diurnal megachiropteran bat species (flying foxes; Pteropus spp.) frequently use thermal or slope soaring during foraging flights to save energy. We compared the flight morphology and gliding/soaring performance of soaring versus non-soaring Pteropus species, one pair on American Samoa and one pair on the Comoro Islands, and two other soaring/flap-gliding species and one non-soaring species. We predicted that the soaring species should have a lower body mass, longer wings and, hence, lower wing loadings than those species that use mainly flapping flight. This would give a lower sinking speed during gliding, a higher glide ratio, and enable the bats to make tighter turns with lower sinking speeds than in the non-soaring species. We theoretically calculated the gliding and circling performances of both the soaring and non-soaring species. Our results show that there are tendencies towards longer wings and lower wing loadings in relation to body size in the gliding/soaring flying foxes than in the non-soaring ones. In the species-pair comparison of the soaring and non-soaring species on American Samoa and the Comoro Islands, the soarers on both islands turn out to have lower wing loadings than their non-soaring partners in spite of opposite size differences among the pairs. These characteristics are in accordance with our hypothesis on morphological adaptations. Most differences are, however, only significant at a level of P<0.1, which may be due to the small sample size, but overlap also occurs. Therefore, we must conclude that wing morphology does not seem to be a limiting factor preventing the non-soarers from soaring. Instead, diurnality in the soaring species seems to be the ultimate determinant of soaring behaviour. The morphological differences cause visible differences in soaring and gliding performance. The glider/soarers turn out to have lower minimum sinking speeds, lower best glide speeds and smaller turning radii than the non-soarers. When the wing measurements and soaring performance are normalized to a body mass of 0.5 kg for all species, the minimum sinking speed becomes significantly lower (P<0.05) in the three soaring and the one flap-gliding species (0.63 m s(-)(1)) than in the three non-soaring species (0.69 m s(-)(1)). Interestingly, the zones in the diagrams for the glide polars and circling envelopes of these similar-sized bats become displaced for the glider/soarers versus the non-soarers. The glide polars overlap slightly only at the gliding speeds appropriate for these bats, whereas the circling envelopes do not overlap at the appropriate bank angles and turning radii. This points towards adaptations for better gliding/soaring performance in the soaring and gliding species.

American Samoa↗
PubMed2006

A gain-of-function screen identifying genes required for vein formation in the Drosophila melanogaster wing.

The formation of the Drosophila wing involves developmental processes such as cell proliferation, pattern formation, and cell differentiation that are common to all multicellular organisms. The genes controlling these cellular behaviors are conserved throughout the animal kingdom, and the genetic analysis of wing development has been instrumental in their identification and functional characterization. The wing is a postembryonic structure, and most loss-of-function mutations are lethal in homozygous flies before metamorphosis. In this manner, loss-of-function genetic screens aiming to identify genes affecting wing formation have not been systematically utilized. As an alternative, a number of genetic searches have utilized the phenotypic consequences of gene gain-of-expression, as a method more efficient to search for genes required during imaginal development. Here we present the results of a gain-of-function screen designed to identify genes involved in the formation of the wing veins. We generated 13,000 P-GS insertions of a P element containing UAS sequences (P-GS) and combined them with a Gal4 driver expressed mainly in the developing pupal veins. We selected 500 P-GSs that, in combination with the Gal4 driver, result in modifications of the veins, changes in the morphology of the wing, or defects in the differentiation of the trichomes. The P-element insertion sites were mapped to the genomic sequence, identifying 373 gene candidates to participate in wing morphogenesis and vein formation.

Animals↗
PubMed2000

Ultrasound therapy for the prevention and correction of contractures and bone mineral loss associated with wing bandaging in the domestic pigeon (Columba livia).

Figure-of-eight wing bandaging is widely used to treat wing injuries, to immobilize wings before and after fracture repair, and during transient wing paralysis. However, prolonged bandaging can lead to bone loss and to contractures and reduced range of joint motion. Studies evaluating the efficacy of therapeutic ultrasound to reverse and prevent bandaging-associated contractures in pigeons (Columba livia) showed a significant increase in elbow and carpal extension after 10 twice weekly ultrasound treatments when started either 4 or 11 days after bandage placement. In addition, after 42 days of wing bandaging, three ultrasound treatments stimulated a faster reversal of carpal wing rotation loss than removal of the bandage over the 10-day treatment period. Finally, bone loss in response to 28 days of bandaging was significant, progressed at 2.8% per week, and was not affected by ultrasound treatment twice weekly during this period. Therefore, therapeutic ultrasound prevented and reversed loss of wing extension associated with figure-of-eight bandaging but did not lessen the disuse osteoporosis created by bandaging in these birds.

Absorptiometry, Photon↗
PubMed2005

Mating success of males with and without wing patch in Drosophila biarmipes.

Some males of D. biarmipes--synonym of D. rajasekari and D. raychaudhuri have a black patch on the wing. The patch extends from the apical margin of wing to the third longitudinal vein. Field and laboratory studies have been carried out in D. biarmipes to study role of male's wing patch in mating success. The field study shows that nature favors D. biarmipes males with patch. Although males without patch mated, males with patch have higher mating success suggesting the role of wing patch during courtship. Further, among mating males, males with patch had longer wings than males without patch. During courtship, males with patch oriented and mated faster; performed courtship acts such as tapping, scissoring, vibration, licking and twist dance more times than males without patch in both competitive and non-competitive situations. The results indicate that there is a casual relationship between the presence of wing patch, mating speed and success. Also there is a correlation between presence of wing patch, size of the flies and mating success.

Animals↗
PubMed1984

Butterfly wing patterns: how good a determining mechanism is the simple diffusion of a single morphogen?

The formation of the wing pigmentation patterns of three species of butterflies has been modelled using a mechanism based on a tripod of assumptions. First, that there may be morphogen sources in the foci of eyespots and morphogen sinks at some parts of the wing margin, all other cells being passive. Second, that the morphogen has a finite half life and diffuses simply and freely away from the sources throughout a wing of hexagonally packed cells. Third, that the overt pattern derives from cells interpreting the local morphogen concentration with respect to thresholds which determine scale colours. The final pattern thus follows lines of constant morphogen concentration and may, depending on the distribution of sources, comprise rings, curves or bands. With such a model, we have been able to compute stable patterns having the essential topology of the compound spots of Tenaris domitilla, the large rings of Diaethria marchalii and the pattern of eyespots, rings and asymmetric bands of Ragadia minoa. Quantitative analysis of the pattern-forming process shows that, with a biologically realistic diffusion constant (approximately 5.10(-7) cm2 sec-1) and a morphogen half life less than 6h, the patterns form within approximately 12h over a wing of approximately 1000 cells in length. The limitations of the model are that the exact morphology of the eyespots and bands do not match precisely those of the original wings, that there are edge distortions and that optimal patterns may be critically dependent on the exact positions of sources and sinks. An explanation for part of the discrepancy is that we have assumed an adult wing shape and foci coordinates in modelling a process that took place earlier in development. Nevertheless, the limitations of the model argue against a mechanism based on a single morphogen operating in vivo. However, as the model can generate many features of butterfly wing patterns, it may be considered as a degenerate case of that mechanism.

Animals↗
PubMed1996

[Phenotypic plasticity of wing size and shape in Drosophila melanogaster and D. simulans].

Variation of 13 morphometric wing characters in relation to temperature of development was studied in two sibling species Drosophila melanogaster and D. simulans. Three principal components that accounted for 73% of variation of these characters were identified. The first component was interpreted as general wing size, while the second and third components described wing shape. Temperatures of maximal wing size and temperatures corresponding to the highest values of the third principal component (proximal-distal ratio) were different in the species studied. In each of the species, reaction norm curves of the three-principal components were different, indicating qualitative differences between reaction norms of characters belonging to the same organ. Variances of both general wing size and shape were different at different temperatures. Variance of general wing size was lower at intermediate temperatures and higher at high and low temperatures. Correlations between wing measurements were significantly different at different temperatures.

Adaptation, Physiological↗
PubMed1993

Subclassification of children with autism and pervasive developmental disorder: a questionnaire based on Wing's subgrouping scheme.

A questionnaire (the Wing Subgroups Questionnaire, or WSQ) for subclassifying children with autism into one of Wing's three hypothesized subgroups was developed, and the validity of this measure was assessed. Forty parents of children with autism or pervasive developmental disorder not otherwise specified (PDDNOS) completed the questionnaire. Results indicated that the questionnaire has adequate external criterion-referenced validity with similar subgroup ratings made by clinicians, and good internal consistency. Furthermore, results revealed three distinct and separate subgroups corresponding to Wing's subclassification scheme. Other analyses suggested that Wing assignment based on the WSQ was independent of chronological age and age equivalents for social and daily living skills, but not independent of diagnosis of autism vs. PDDNOS, IQ, severity of autism, sex, receptive language mental age, and age equivalents for communication skills. Finally, a discriminant analysis indicated that, of all the dependent variables examined in the present study, the clinicians' Wing assignment was the best predictor of Wing assignment based on the parent-completed WSQ. These findings provide support for Wing's classification system, and suggest that the WSQ is a valid and useful tool for subclassifying individuals with autism.

Adolescent↗
PubMed1995

Comparative nutritive value of winged bean (Psophocarpus tetragonolobus (L) DC) and other legumes grown in Tanzania.

Chemical analyses and feeding experiments using rats were conducted to evaluate the nutritive value of winged bean and other legumes (soyabean, green gram, bambarra nuts, pigeon peas, field beans, cow peas) sources grown in Tanzania. Proximate analyses showed that the composition of winged bean was similar to soyabean, while the composition of the other legumes differed considerably. This was also the case for antinutritional constituents and minerals. As to the amino acid composition, the lysine level was high with the highest value in winged bean (7.5 g/16 g N). However, the concentration of methionine and cystine was low which limits their protein quality. Another important amino acid, threonine, was generally high, especially in winged bean (4.3 g/16 g N). With exception of field bean, true protein digestibility was above 80%, soyabean having the highest value (90.7%). The biological value was also highest in soyabean (76.1%) followed by winged bean (69.9%). Utilizable protein was high in soyabean (28.8%) and somewhat lower in winged bean (23.4%). Energy digestibility was around 80%, soyabean having the highest value of 85.8%. The study findings support the idea that winged bean is a good alternative plant protein source in Tanzania.

Amino Acids↗