A wing synchronous receptor for the Dipteran flight motor

The existence of proprioceptive influences has been inferred in the Dipteran flight motor system but the sensory receptors(s) responsible has not been identified. We describe a wing-base structure which is widespread, and probably universal in the Diptera, which possesses the requisite mechanical and neurophysiological properties to provide such proprioceptive feedback.     

The motor pattern of locusts during visually induced rolling in long-term flight

Desert locusts (Schistocerca gregaria F.), mounted in a wind tunnel on a low-mechanical-impedance torque meter, flew for at least 30 min in the posture typical of long-term flight. As they flew, they were induced to rotate about their long axis (roll) by rotation of an artificial horizon. All maintained departures from the horizontal attitude were brought about actively, by the animal's own efforts. In the roll maneuver, the hindlegs and abdomen were bent toward the side ipsilateral to the direction of rotation. However, these rudderlike movements were not adequate to initiate and maintain a constant roll angle.During a roll, there was a change in the pattern of excitation of all the wing muscles that were monitored: the depressorsM81, 97, 99, 112, 127, and 129, and the elevatorsM83, 84, 89, 113, 118, 119 (numbering according to Snodgrass 1929). Hence all 12 muscles probably not only provide power for the flight but also steer it. Evidently, then, for these muscles a rigid distinction between power and steering muscles is not appropriate.The period of the contraction cycle changed in correlation with the roll angle, but was not a parameter for control of the roll maneuver, because the changes were the same in all muscles (Fig. 2).Even with constant burst length, the phase shifts between the muscles changed. These changes were the main control parameter for rolling (Figs. 3–9).There was a latency coupling between elevators and the following depressors (Fig. 3).The changes in phase shift were tonic or phasic (sometimes phasic-tonic) in different muscle pairs (Fig. 4).When a roll angle of ca. 15° was adopted, the phase shifts between depressor muscles in a given fore- or hindwing (e.g.,M127R vs.M129R) changed by about 5 ms, whereas the elevators changed by less than 1 ms (Fig. 6).The phase shifts between the anterior elevators and depressors of a given wing, as well as the posterior elevators and depressors, changed by ca. 5 ms (in some cases with different time courses) when the animal rolled to an angle of ca. 15° (Fig. 7).The changes in phase shift between muscles of the fore-and hindwing on one side of the body amounted, as a rule, to about 4 ms at ca. 15° roll (Fig. 8).Corresponding muscles on the two sides of the body change in phase with respect to one another by as much as 10 ms (Fig. 9). The phase shifts of all such contralateral muscle pairs except for the posterior basalar muscles,M127, have the same sign, such that the muscle ipsilateral to the direction of rotation becomes active sooner.     

Manipulation of the endocrine system ofLocusta and the development of the flight motor pattern

Journal of Comparative Physiology A - By chemical allatectomy (precocenetreatment) or implantation of corpora allata, precocious adults (adultiforms) and supernumerary larval instars respectively...     

Pre-imaginal flight motor pattern in Locusta

In a wind stream, larval stages of Locusta usually show a tonic muscle activity but they can also exhibit a rhythmic motor output. With ageing such a pattern can be released sooner, the trains become longer. The basic rhythm of 10 Hz does not change. The initial co-contraction of specific muscles is substituted later in development by an antagonistic recruitment. This activity resembles the flight motor pattern of young locusts which lack phasic sensory feedback from the wing region. Azadirachtin, an insect growth regulator, has been used to produce a permanent 5th larval instar. However, the extension of the last larval stage does not lead to a further development of the motor pattern to a level comparable to mature animals.     

The effects of dietary astaxanthin on the carotenoid pattern of the prawn Penaeus japonicus during postlarval development

Penaeus japonicus postlarvae, reared under laboratory conditions, were fed an astaxanthin enriched diet to the investigate carotenoid metabolic capabilities during the postlarval development. Animals fed astaxanthin were found to absorb this carotenoid. The decrease of pigment concentration in the carotenoid starved group is related to the duration of the experimental feeding conditions; the carotenoid depletion depends upon the postlarval status at the starting point. As has been shown for adult prawns, the carotenoid pattern of postlarval stages, regardless of the diet, consists mainly of free and esterified astaxanthin; the relative amounts of these fractions undergo slight variations depending on the diet.     

Dipteran insect flight dynamics. Part 2: Lateral-directional motion about hover

The purpose of this study is to determine computationally tractable models describing the lateral-directional motion of a Drosophila-like dipteran insect, which may then be used to estimate the requirements for flight control and stabilization. This study continues the work begun in Faruque and Humbert (2010) to extend the quasi-steady aerodynamics model via inclusion of perturbations from the hover state. The aerodynamics model is considered as forcing upon rigid body dynamics, and frequency-based system identification tools used to derive the models. The analysis indicates two stable real poles, and two very lightly damped and nearly unstable complex poles describing a decoupling of roll/sideslip oscillatory motion from a first order subsidence yaw behavior. The results are presented with uncertainty variation for both a smaller male and larger female phenotype.     

Ontogenetic changes in biochemical composition during larval and early postlarval development of Lepidophthalmus louisianensis, a ghost shrimp with abbreviated development

Changes in growth and biochemical composition during the transition from egg through zoea to decapodid in the ghost shrimp, Lepidophthalmus louisianensis (Schmitt, 1935), were documented in terms of dry weight, lipid classes, fatty acid composition, and carbon to nitrogen (C:N) ratios. Larvae of the ghost shrimp were mass-reared in the laboratory (28°C; 20‰ S) from hatching to the decapodid stage. Iatroscan lipid class analysis revealed that major lipid classes in recently produced eggs were phospholipids (80.8±1.3%) and triglycerides (16.0±1.1%), which decreased during the incubation period. Polar lipids (zoea I: 77.4±1.7%; zoea II: 77.5±2.1%; decapodid: 80.0±1.7%) and neutral lipids, of which free fatty acids (zoea I: 10.5±2.7%; zoea II: 13.1±5.2%; decapodid: 7.8±2.1%) were dominant, represented the major lipid classes in the zoeal and decapodid stages. Triglycerides were present in small amounts. The predominant fatty acids of L. louisianensis eggs, zoeae and decapodids were palmitic (16:0), stearic (18:0), eicosapentaenoic (20:5ω3), oleic (18:1ω9), and arachidonic (20:4ω6). Elemental composition of eggs, larvae, and the decapodid stage revealed conspicuous changes in the C:N ratio, with N being relatively stable during larval development but C decreasing during the decapodid stage. These data suggest independence of newly hatched L. louisianensis on external energy resources. This combined with the ability to incorporate saturated fatty acids into polar lipids provides a selective advantage for fast development of new tissue and growth, characteristic of decapod crustacean larvae with lecithotrophic development.     

Maturation of the flight motor pattern without movement inManduca sexta

The development of the flight motor pattern was studied by recording acutely with fine wire electrodes inserted in the thoracic muscles of pharate moths of known age and by recording chronically for up to 8 days with implanted electrodes. Externally visible morphological characteristics by which the age of a pharateManduca sexta can be established were identified (Table 1). Bouts of activity lasting approximately 30 min to 2 h and alternating with inactive periods of similar duration were recorded as early as the ninth day after pupation and on all successive days until early on the day of eclosion, typically 19 days after pupation (Figs. 1,5). During the 3 days preceding the day of eclosion a rhythmic flight motor pattern was produced (Fig. 2). The rhythmic activity ceased 5^1/2–10^1/2 h before eclosion and only an occasional, large potential change was recorded from the thoracic muscles during this time (Fig. 3). During the 3 days of rhythmic activity the percent-age of time that the animal was active did not change (Fig. 4). The flight motor pattern matured, in that the cycle-time decreased and became less variable (Fig. 6). The approximate flight phase relationship between an elevator muscle and the dorsal longitudinal depressor muscle did not become less variable as the cycle-time improved. The flight motor pattern produced by pharate moths caused neither movement of the scutum nor an increase in thoracic temperature in marked contrast to the consequences of adult motor activity (Fig. 7). Intracellular recording from the dorsal longitudinal muscle of pharate moths 20–30 h before eclosion showed that, after repeated stimulation of the motor nerve at 2/s, only small junctional potentials were elicited (Fig. 8). A burst of 6 stimuli at 50/s elicited 2–5 active membrane responses and a contraction. These observations explain the absence of thoracic movement in immature animals producing the flight motor pattern and the presence of movement in immature animals stimulated to eclose. They also show that the neuromuscular junction matures rapidly during the day before eclosion.     

The Drosophila proteasome undergoes changes in its subunit pattern during development

The two-dimensional electrophoretic protein subunit pattern of the proteasome, which is a mulifunctional non-lysosomal proteinase, was analyzed throughout the development of Drosophila melanogaster. The experiments show that the proteasome is already present in early embryos and its characteristic gross morphology as judged by the outer diameter of 12 nm and the inner depression of 3 nm remains unaltered. The electrophoretic analysis of the enzyme subunits demonstrates that the proteasome undergoes, dependent on development, alterations in its protein composition. The most simple subunit pattern is observed in Schneider's S-3 tissue culture cells and early embryos while with ongoing fly development the subunit pattern of the proteasome becomes increasingly complex. 32P-Labeling and immunoblotting experiments indicate that post-translational modification of the subunits must in part be responsible for the development-dependent diversification of the subunit pattern. Our data raise the possibility that the in vivo proteolytic activity and the in vivo substrate specificity of the proteasome may be regulated by modification of its subunit composition during fly development.     

Neuromodulation during motor development and behavior

Important recent advances have been made in understanding the role of aminergic modulation during the maturation of Xenopus larvae swimming rhythms, including effects on particular ion channel types of component neurons, and the role of peptidergic modulation during development of adult central patterns generators in the stomatogastric ganglion of crustaceans. By recording from octopaminergic neuromodulatory neurons during ongoing motor behavior in the locust, new insights into the role of this peripheral neuromodulatory mechanism have been gained. In particular, it is now clear that the octopaminergic neuromodulatory system is automatically activated in parallel to the motor systems, and that both excitation and inhibition play important functional roles.     

Protein synthesis during flight muscle development in normal and wupB indirect flight muscles of Drosophila melanogaster

We have looked at protein synthesis in Drosophila pupae during normal and abnormal development of indirect flight muscle. Abnormal development was followed in the dominant flightless mutant wupB isolated by Hotta and Benzer (Genetic Mechanisms of Development, pp. 129–167. Academic Press, New York, 1972). The mutant muscles in adult wupB flies have abnormal morphology and disorganized myofibrils. Protein synthesis in developing muscle was followed on SDS-polyacrylamide gels. During early stages of development (55–60 h) protein synthesis patterns are similar in the mutant and the wild-type. However, at 61 h, the mutant shows a transient increase in synthesis of the 68 and 70 kDa heat shock proteins. This is followed at about 70 h by a divergence of the patterns of synthesis of other proteins seen in the mutant and wild type. These results suggest that induction of heat shock protein synthesis is an early event in abnormal morphogenesis in this mutant.     

On the coordination of motor output during visual flight control of flies

Summary In tethered flying houseflies (Musca domestica), the yaw torque produced by the wings is accompanied by postural changes of the abdomen and hindlegs. In free flight, these body movements would jointly lead to turning manoeuvres of the animal. By recording the yaw torque together with the lateral deflections of either the abdomen or the hindlegs, it is shown that these motor output systems act in a highly synergistic way during two types of visual orientation behavior, compensatory optomotor turning reactions and orientation turns elicited by moving objects. This high degree of coordination is particularly conspicuous for the pathway activated by moving objects. Here, orientation responses either may be induced or may fail to be generated always simultaneously in all three motor output systems. This suggests that the pathway mediating orientation turns towards objects is gated before it segregates into the respective motor control systems of the wings, the abdomen and the hindlegs.