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PubMed2006

Patterns of variation in wing morphology in the cactophilic Drosophila buzzatii and its sibling D. koepferae.

Drosophila buzzatii and D. koepferae are two sibling species that breed on the necrotic tissues of several cactus species and show a certain degree of niche overlap. Also, they show differences in several life history traits, such as body size and developmental time, which probably evolved as a consequence of adaptation to different host plants. In this work we investigate the ecological and genetic factors affecting wing morphology variation both within and between species. Three wing traits were scored, distal and proximal wing length and width in isofemale lines reared in two of the most important host cacti: Opuntia sulphurea and Trichocereus terschekii. Our results revealed that differences between species and sexes in wing size and shape were significant, whereas the cactus factor was only significant for wing size. Intraspecific analyses showed that differences among isofemale lines were highly significant for both size and shape in both species, suggesting that an important fraction of variation in wing morphology has a genetic basis. Moreover, the line by cactus interaction, which can be interpreted as a genotype by environment interaction, also accounted for a significant proportion of variation. In summary, our study shows that wing size is phenotypically plastic and that populations of D. buzzatii and D. koepferae harbour substantial amounts of genetic variation for wing size and shape. Interspecific differences in wing size and shape are interpreted in terms of spatial predictability of the different host plants in nature.

Animals↗
PubMedDate not supplied

Wing disc development during caste differentiation in the ant Pheidole megacephala (Hymenoptera: Formicidae).

The genus Pheidole has three distinct castes in females: queen, major, and minor workers. It has been believed that the larvae of major workers have prominent mesothoracic wing discs, although the minor worker larvae lack them. Here we conducted histological examinations of wing discs during larval development in P. megacephala. We show that all three castes have mesothoracic wing discs, at least in their early stage of the final larval instar, and that the wings degenerate differently in the dimorphic worker castes. The minute wing discs of minor workers neither grow nor metamorphose but disappear during the prepupal stage. On the contrary, the wing discs of major workers evaginate at the onset of the prepupal stage but subsequently degenerate by apoptotic cell death. This apoptotic wing degeneration in the prepupal stage was contradistinguished from wing degeneration in some lepidopteran insects, in which apoptosis occurs in the pupal wing buds. Our results suggest that each worker caste shows a different degeneration process to express the wingless character and that apoptotic degeneration has been adopted in association with the evolution of worker dimorphism.

Animals↗
PubMed1993

Production of [14C]-labeled 3-hydroxy-L-kynurenine in a butterfly, Heliconius charitonia L. (Heliconidae), and precursor studies in butterfly wing ommatins.

A method was developed to produce radiolabeled 3-hydroxy-L-kynurenine by injection of [14C]-L-tryptophan into pupae of the heliconid butterfly, Heliconius charitonia, which was converted into [14C]-3-hydroxy-L-kynurenine and deposited as a wing pigment. Extractions of 3-hydroxykynurenine (3-OHK) with 60% methanol from wings yielded in 14.4 micrograms per mg dry weight. In extracts from yellow wing areas, 3-OHK represented 100% of detectable amino acids. Resulting specific radioactivity of [14C]-3-OHK was between 0.05 and 0.07 mCi/mmol when 0.5 microCi [14C]-tryptophan was injected into pupae 1 or 2 days before emergence of the butterfly. Incorporation of [14C]-3-OHK into wing ommochromes was studied in nymphalid butterflies, Araschnia levana and Precis coenia. After injection into pupae [14C]-3-OHK as well as [14C]-tryptophan were specifically incorporated into red and red-brown wing scales as shown by autoradiography. The same incorporation occurred in isolated wings after incubation in Grace's medium containing [14C]-3-OHK. In Araschnia levana, [14C]-3-OHK offered to left wing pairs was incorporated into dihydroxanthommatin six times more effectively than [14C]-tryptophan offered to right wing pairs from the same specimen. Therefore, 3-OHK seems to be the ultimate precursor of wing ommatins.

Amino Acids↗
PubMed1998

Interactions among Delta, Serrate and Fringe modulate Notch activity during Drosophila wing development.

The Notch signalling pathway plays an important role during the development of the wing primordium, especially of the wing blade and margin. In these processes, the activity of Notch is controlled by the activity of the dorsal specific nuclear protein Apterous, which regulates the expression of the Notch ligand, Serrate, and the Fringe signalling molecule. The other Notch ligand, Delta, also plays a role in the development and patterning of the wing. It has been proposed that Fringe modulates the ability of Serrate and Delta to signal through Notch and thereby restricts Notch signalling to the dorsoventral boundary of the developing wing blade. Here we report the results of experiments aimed at establishing the relationships between Fringe, Serrate and Delta during wing development. We find that Serrate is not required for the initiation of wing development but rather for the expansion and early patterning of the wing primordium. We provide evidence that, at the onset of wing development, Delta is under the control of apterous and might be the Notch ligand in this process. In addition, we find that Fringe function requires Su(H). Our results suggest that Notch signalling during wing development relies on careful balances between positive and dominant negative interactions between Notch ligands, some of which are mediated by Fringe.

Animals↗
PubMed2000

Activation of knot (kn) specifies the 3-4 intervein region in the Drosophila wing.

Hedgehog (Hh) plays an important role in Drosophila wing patterning by inducing expression of Dpp, which serves to organize the wing globally across the A-P axis. We show here how Hh signalling also plays a direct role in patterning the medial wing through the activation of the Hh-target gene, knot (kn). kn is expressed in Hh-responsive cells near the A-P compartment boundary, where its expression is dependent on fu, a component of Hh signalling. kn is required for the proper positioning of veins 3 and 4 and to prevent ectopic venation between them. Furthermore, the expansion anteriorly of the normal kn expression domain causes an associated anterior shift in the position of vein 3 in the resultant wing. Ectopic expression of kn elsewhere in the wing imaginal disc results in the failure to properly activate the vein initiation genes, rho and Dl. Expression of the gene encoding the EGF-receptor (EGFR), which is required for vein initiation and subsequent differentiation, is normally depressed in the 3-4 intervein region. This downregulation of EGFR in the medial portion of the imaginal disc is dependent on kn activity and ectopic expression of kn inactivates EGFR elsewhere in the wing primordium. We propose kn expression in Hh-responsive cells of the wing blade anlagen during the late third instar creates a zone of cells in the medial wing in which vein primordia cannot be induced. The primordia for veins 3 and 4 are laid down adjacent to the kn-imposed vein-free zone, presumably by a signalling factor (such as Vn) also synthesized in the medial region of the wing.

Animals↗
PubMed2000

Function and regulation of homothorax in the wing imaginal disc of Drosophila.

The gene homothorax (hth) is originally expressed uniformly in the wing imaginal disc but, during development, its activity is restricted to the cells that form the thorax and the hinge, where the wing blade attaches to the thorax, and eliminated in the wing pouch, which forms the wing blade. We show that hth repression in the wing pouch is a prerequisite for wing development; forcing hth expression prevents growth of the wing blade. Both the Dpp and the Wg pathways are involved in hth repression. Cells unable to process the Dpp (lacking thick veins or Mothers against Dpp activity) or the Wg (lacking dishevelled function) signal express hth in the wing pouch. We have identified vestigial (vg) as a Wg and Dpp response factor that is involved in hth control. In contrast to its repressing role in the wing pouch, wg upregulates hth expression in the hinge. We have also identified the gene teashirt (tsh) as a positive regulator of hth in the hinge. tsh plays a role specifying hinge structures, possibly in co-operation with hth.

Animals↗
PubMed2004

The effects of intense wing molt on diving in alcids and potential influences on the evolution of molt patterns.

Large and medium-sized alcids have a very intense wing molt wherein many flight feathers are shed in rapid succession and wing surface area is reduced by as much as 40%. Although these birds are rendered flightless during wing molt, they must still use their wings to propel themselves underwater. A molt-induced loss of wing area could simply reduce wing propulsion such that more muscular work would be required to maintain a given speed. Alternatively, molt could reduce drag on the wings, making a bird more penguin-like and actually enhancing diving ability. I addressed this issue by filming captive common guillemots Uria aalge and tufted puffins Fratercula cirrhata using an array of video cameras to plot the birds' movements in three dimensions. From these coordinate data I calculated swimming velocities, angles of descent and absolute depths. These values allowed me to estimate the forces due to drag and buoyancy that must be counteracted by flapping, which in turn yielded estimates of the amount of work generated during each flap as well as the average power and cost of transport. Within-bird comparisons of diving performance when wings were intact and during several stages of wing molt indicated that molt is associated with more frequent flapping, reduced displacement during the flap cycle, and possibly reduced work per flap. These negative effects on diving may explain why primary and secondary molts were offset in the birds I studied such that the period during which all of the flight feathers are effectively missing is minimized.

Analysis of Variance↗
PubMed2004

The fluid dynamics of flight control by kinematic phase lag variation between two robotic insect wings.

Insects flying with two pairs of wings must contend with the forewing wake passing over the beating hindwing. Some four-winged insects, such as dragonflies, move each wing independently and therefore may alter the relative timing between the fore- and hindwing stroke cycles. The significance of modifying the phase relationship between fore- and hindwing stroke kinematics on total lift production is difficult to assess in the flying animal because the effect of wing-wake interference critically depends on the complex wake pattern produced by the two beating wings. Here we investigate the effect of changing the fore- and hindwing stroke-phase relationship during hovering flight conditions on the aerodynamic performance of each flapping wing by using a dynamically scaled electromechanical insect model. By varying the relative phase difference between fore- and hindwing stroke cycles we found that the performance of the forewing remains approximately constant, while hindwing lift production may vary by a factor of two. Hindwing lift modulation appears to be due to two different fluid dynamic phenomenons: leading edge vortex destruction and changes in strength and orientation of the local flow vector. Unexpectedly, the hindwing regains aerodynamic performance near to that of the wing free from forewing wake interference, when the motion of the hindwing leads the forewing by around a quarter of the stroke cycle. This kinematic relationship between hind- and forewing closely matches the phase-shift commonly used by locusts and some dragonflies in climbing and forward flight. The experiments support previous assumptions that active neuromuscular control of fore- and hindwing stroke phase might enable dragonflies and other functionally four-winged insects to manipulate ipsilateral flight force production without further changes in wing beat kinematics.

Animals↗
PubMed2001

The control of flight force by a flapping wing: lift and drag production.

We used a dynamically scaled mechanical model of the fruit fly Drosophila melanogaster to study how changes in wing kinematics influence the production of unsteady aerodynamic forces in insect flight. We examined 191 separate sets of kinematic patterns that differed with respect to stroke amplitude, angle of attack, flip timing, flip duration and the shape and magnitude of stroke deviation. Instantaneous aerodynamic forces were measured using a two-dimensional force sensor mounted at the base of the wing. The influence of unsteady rotational effects was assessed by comparing the time course of measured forces with that of corresponding translational quasi-steady estimates. For each pattern, we also calculated mean stroke-averaged values of the force coefficients and an estimate of profile power. The results of this analysis may be divided into four main points. (i) For a short, symmetrical wing flip, mean lift was optimized by a stroke amplitude of 180 degrees and an angle of attack of 50 degrees. At all stroke amplitudes, mean drag increased monotonically with increasing angle of attack. Translational quasi-steady predictions better matched the measured values at high stroke amplitude than at low stroke amplitude. This discrepancy was due to the increasing importance of rotational mechanisms in kinematic patterns with low stroke amplitude. (ii) For a 180 degrees stroke amplitude and a 45 degrees angle of attack, lift was maximized by short-duration flips occurring just slightly in advance of stroke reversal. Symmetrical rotations produced similarly high performance. Wing rotation that occurred after stroke reversal, however, produced very low mean lift. (iii) The production of aerodynamic forces was sensitive to changes in the magnitude of the wing's deviation from the mean stroke plane (stroke deviation) as well as to the actual shape of the wing tip trajectory. However, in all examples, stroke deviation lowered aerodynamic performance relative to the no deviation case. This attenuation was due, in part, to a trade-off between lift and a radially directed component of total aerodynamic force. Thus, while we found no evidence that stroke deviation can augment lift, it nevertheless may be used to modulate forces on the two wings. Thus, insects might use such changes in wing kinematics during steering maneuvers to generate appropriate force moments. (iv) While quasi-steady estimates failed to capture the time course of measured lift for nearly all kinematic patterns, they did predict with reasonable accuracy stroke-averaged values for the mean lift coefficient. However, quasi-steady estimates grossly underestimated the magnitude of the mean drag coefficient under all conditions. This discrepancy was due to the contribution of rotational effects that steady-state estimates do not capture. This result suggests that many prior estimates of mechanical power based on wing kinematics may have been grossly underestimated.

Animals↗
PubMed2005

Morphological comparison of pupal wing cuticle patterns in butterflies.

Butterfly wing color-patterns are determined in the prospective wing tissues during the late larval and early pupal stages. To study the cellular differentiation process of wings, morphological knowledge on pupal wings is prerequisite. Here we systematically examined morphological patterns of the pupal wing cuticular surface in a wide variety of nymphalid butterflies in relation to adult color-patterns. Several kinds of pupal wing patterns corresponding to particular adult color-pattern elements were widely observed in many species. Especially noteworthy were the pupal "focal" spots corresponding to the adult border ocelli system, which were detected in many species of Nymphalinae, Apaturinae, Argynninae, Satyrinae, and Danainae. Striped patterns on the pupal wing cuticle seen in some species of Limenitinae, Ariadnae, and Marpesiinae directly corresponded to those of the adult wings. In Vanessa cardui, eyespot-like pattern elements were tentatively produced during development in the wing tissue underneath the pupal spots and subsequently erased, suggesting a mechanism for producing novel color-patterns in the course of development and evolution. The pupal focal spots reasonably correlated with the adult eyespots in size in Precis orithya and Ypthima argus. We physically damaged the pupal focal spots and their corresponding cells underneath in these species, which abolished or inhibited the formation of the adult eyespots. Taken together, our results clarified that pupal cuticle patterns were often indicative of the adult color-patterns and apparently reflect molecular activity of organizing centers for the adult color-pattern formation at least in nymphalid butterflies.

Animals↗
PubMed1992

Photoperiod and the relationship between wing length and body weight in Anopheles quadrimaculatus.

The effect of photoperiod on wing length, body weight, and relationship between wing length and body weight was investigated in the mosquito species Anopheles quadrimaculatus. Individuals reared under a short photoperiod (8 h light: 16 h dark) had longer wings and larger weights than did those reared under a long photoperiod (16 h light: 8 h dark). Covariance analysis showed that photoperiod and wing length interacted so that photoperiod did not have a uniform effect on body weight at all wing lengths. At small mosquito sizes, body weight was higher in short than in long-photoperiod individuals of the same wing length, but at large mosquito sizes, body weight was higher in long than in short-photoperiod individuals of the same wing length. Thus, among smaller mosquitoes of this species, wings were disproportionately longer in long-photoperiod individuals, but among larger mosquitoes, wings were disproportionately longer in short-photoperiod individuals. These results, together with previous studies, suggest that photoperiod and temperature have similar effects on the developing insect.

Analysis of Variance↗
PubMed2000

Control of growth and differentiation of the wing imaginal disk of Precis coenia (Lepidoptera: Nymphalidae).

During the last larval instar, the wing imaginal disks of Precis coenia grow continuously. The rate of disk growth is not disk-autonomous but closely matches the rate of somatic growth of the larva, so that the size of the disks is a function of the size of the body, irrespective of the growth rate of the larva. When larvae are starved, their wing disks cease growth within 4 h, which indicates the existence of an efficient coupling mechanism between the growth of the soma and growth of the imaginal disks. Disk growth is inhibited by juvenile hormone in a dose-dependent manner. In the presence of the hormone the wing disks stop growing even while the larva continues to grow normally. During the last larval instar the wing imaginal disks also undergo a complex differentiation, consisting of the development of the lacunae and tracheation that define the future adult wing venation system. In normally growing larvae, differentiation of the wing disk is tightly correlated with wing size. Differentiation and size can be dissociated by starvation. If larvae are starved at any time after differentiation has begun, differentiation continues at a normal rate, even though the wing disk does not grow. Differentiation does not begin spontaneously in larvae that are starved before differentiation has begun. These findings indicate that the initiation of differentiation and its continuation are controlled independently. Juvenile hormone inhibits differentiation in a dose-dependent manner. Upon treatment with juvenile hormone, the stage of differentiation becomes fixed. These findings indicate that continued differentiation of the wing disk can only occur in the absence of juvenile hormone. Although the circulating level of juvenile hormone may be elevated during starvation, it is unlikely that this elevation is responsible for the observed effect of starvation on growth and differentiation of the disk.

Journal Article↗
PubMed2000

Creating temperature-sensitive winged helix transcription factors. Amino acids that stabilize the DNA binding domain of HNF3.

Winged helix transcription factors contain two polypeptide loops, or "wings," that make minor groove contacts with DNA from either side of a three-helix bundle that binds the DNA major groove. While wing 1 is stabilized by a beta-sheet, parameters that stabilize wing 2 are unknown. Herein we identify two bulky aromatic residues in wing 2 that stabilize the loop structure and, thereby, the entire protein's DNA binding and transcriptional stimulatory activity by interacting with other residues in the three-helix bundle. Mutations of these wing 2 residues create proteins that are temperature-sensitive for transcriptional activity. Aromatic and/or hydrophobic residues are highly conserved among the 150 known winged helix proteins, suggesting conserved function. We suggest that the winged helix structure evolved by the acquisition of aromatic and/or hydrophobic residues in distal polypeptide sequences that helped stabilize the association of a protein loop (wing 2) with the three-helix bundle, thereby enhancing DNA binding.

Amino Acid Sequence↗
PubMed1995

Wing-beat coupling between flying locust pairs: preferred phase and lift enhancement

Pairs of locusts flying in tandem in a wind tunnel are known to couple their wing-beats intermittently. The rhythmically oscillating air flow from the front locust's wing-beat, detected by the rear individual, appears to convey the timing information for coupling. Three predictions of this arrangement were tested quantitatively in this study. (1) Given that the oscillating air flow has a wavelength of 7.5 cm, placing the rear locust 7.5 or 15 cm behind the front one should produce the same phase of coupling, whereas placing it at an intermediate distance of 11 cm should produce an opposite phase. (2) At any distance, the preferred phase at which wing-beat coupling occurs should depend, in part, on the difference in the wing-beat frequencies of the two locusts just before the coupling began. (3) At the moment that the wing-beats of the two locusts become coupled, a change should be observed consistently in the wing-beat frequency of the rear individual only. Each of these three predictions was fulfilled. We also recorded the instantaneous lift of the rear locust by tethering it to a laser torque meter. Lift varied with the phase of the wing-beats between the two locusts. For a given distance between the two locusts, lift was greater by a mean of 16 % of the locust's body mass at those phases where coupling most commonly occurred than at opposite phases. This lift effect was seen even if the wing-beats of the two locusts drifted through these preferred phases without actually coupling. These results are discussed in terms of a possible energetic advantage conferred to the rear locust by flying in tandem and by coupling its flight rhythm to the leader's wing-beat.

Journal Article↗
PubMed1998

The control of wing kinematics and flight forces in fruit flies (Drosophila spp.).

By simultaneously measuring flight forces and stroke kinematics in several species of fruit flies in the genus Drosophila, we have investigated the relationship between wing motion and aerodynamic force production. We induced tethered flies to vary their production of total flight force by presenting them with a vertically oscillating visual background within a closed-loop flight arena. In response to the visual motion, flies modulated their flight force by changing the translational velocity of their wings, which they accomplished via changes in both stroke amplitude and stroke frequency. Changes in wing velocity could not, however, account for all the modulation in flight force, indicating that the mean force coefficient of the wings also increases with increasing force production. The mean force coefficients were always greater than those expected under steady-state conditions under a variety of assumptions, verifying that force production in Drosophila spp. must involve non-steady-state mechanisms. The subtle changes in kinematics and force production within individual flight sequences demonstrate that flies possess a flexible control system for flight maneuvers in which they can independently control the stroke amplitude, stroke frequency and force coefficient of their wings. By studying four different-sized species, we examined the effects of absolute body size on the production and control of aerodynamic forces. With decreasing body size, the mean angular wing velocity that is required to support the body weight increases. This change is due almost entirely to an increase in stroke frequency, whereas mean stroke amplitude was similar in all four species. Despite the elevated stroke frequency and angular wing velocity, the translational velocity of the wings in small flies decreases with the reduction in absolute wing length. To compensate for their small size, D. nikananu must use higher mean force coefficients than their larger relatives.

Journal Article↗
PubMed1988

Wings in the intershaft space contribute to the Mueller-Lyer illusion.

The interference of the wings of the wings-in part of the Mueller-Lyer figure was examined for the version of the illusion in which one part of the figure is placed above the other. Wings were removed in pairs from either above or below the shaft of one of the two parts of the figure. Subjects indicated the apparent difference between the lengths of the shafts of the two parts of the figure. Removal of the wings between the shafts of the wings-in part of the figure reduced the amount of the illusion more than removal of the wings from outside the shafts. Removing wings from the wings-out part of the figure reduced the amount of illusion, but it made no difference whether the wing removal occurred between or outside the shafts.

Humans↗
PubMed2000

The lymphatic endothelium of the avian wing is of somitic origin.

It has recently been shown that there are lymphangioblasts in the early avian wing bud, but fate map studies on the origin of these cells have not yet been performed. The lymphatics in the wings of 10-day-old chick and quail embryos are characterized by both the position along with all major blood vascular routes and by the Vascular Endothelial Growth Factor Receptor-3 (VEGFR-3) expression. In the quail, the endothelium of both blood vessels and lymphatics can be marked with the QH1 antibody. We have grafted the dorsal halves of epithelial somites of 2-day-old quail embryos homotopically into chick embryos. The grafting was performed at the wing level and the host embryos were reincubated until day 10. The chimeric wings were studied with the QH1 antibody alone and with double staining consisting of VEGFR-3 in situ hybridization and QH1 immunofluorescence. Our results show that in the wing the endothelium of both the blood vessels and the lymphatics is derived from the somites. QH1-positive endothelial cells form the vasculature of the chimeric wings. Chimeric lymphatics of the wing can be identified because of their typical position and their VEGFR-3 and QH1 double-positivity. This shows that not only the blood vascular cells but also the lymphatic endothelial cells of the avian wing are born in the paraxial/somitic mesoderm.

Animals↗
PubMed1984

Comparative analysis of the development of wing-flapping and flight in the fowl.

The development of wing-flapping rate, lateral flight, wing area, and the ratio of wing area to body weight are described in the Japanese quail (Coturnix coturnix japonica) and three chickens (Gallus gallus) to determine common developmental phenomena and to assess the effects of domestication. The chickens were the White Leghorn (a commercial egg producer), the Cornish X Rock (a commercial meat producer), and the Red Jungle fowl (the probable ancestor of domestic chickens). All birds performed drop-evoked wing-flapping on the day of hatching, at least 1 week before lateral flight was possible. Flapping rate of chickens doubled between hatching (approximately 4-6 Hz) and 13 days (approximately 9-12 Hz), after which it leveled off. Japanese quail (JQ) maintained a high flapping rate (approximately 11-13 Hz) during the 21 days after hatching. The Jungle fowl (JF) and JQ flapped the fastest and the White Leghorn (WL) and Cornish X Rock (CR) chickens flapped the slowest. The JF, WL, and JQ developed lateral flight at 7-9 days. The CR first flew 1-2 weeks later but subsequently became flightless. The WL, JF, and JQ had similar ratios of wing area to body weight; the ratios increased to a peak at 11-15 days and later declined. The ratio of the very heavy, essentially flightless, CR was approximately one-half that of the flighted JQ, WL, and JF. The wing-flapping frequencies of the domestic WL and CR chickens approximated that of the JF, suggesting that domestication did not affect the motor pattern generator for flight. The artificial selection of the CR for high body weight drastically diminished its flight performance by producing an unfavorable ratio of wing area to body weight. The JF and the domestic WL both flew well and had similar ratios. Domestication affected flight performance but not the neural circuitry producing wing-flapping. The central nervous system is much more conservative in its response to selection than the peripheral effector structures that it drives.

Animals↗