Academic literature on the topic 'Dorso-longitudinal muscles'

Manduca Sexta present excellent flight performances which make this insect an ideal candidate for bio-inspired engineered micro air vehicles. The actual insect presents an energetically very efficient thorax-wing flight system which needs to be fully understood for an effective design of artificial flying machines. This work discusses a preliminary finite element model which simulates the thorax-wing system and the muscles involved in the flapping motion. Both upstroke and downstroke conditions are statically analyzed with the application of load sets that simulate the contractions of the dorso-ventral and dorso-longitudinal muscles (indirect flight). Comparison with commercial software and experimental results is also presented and discussed.

The responses to topical application of neurotransmitters to the mantle and fin muscles of the spear squid, Loligo bleekeri, were examined. In the mantle, the circular fibres contract in response to L-glutamate and the radial and longitudinal fibres contract in response to acetylcholine. 5-hydroxytryptamine (5-HT) did not affect contractions of any of the mantle muscle fibres. The structure of the fin is similar to that of the mantle, with muscles arranged in three orthogonal planes. Topically applied L-glutamate causes all three muscle types to contract. Acetylcholine does not affect them. Pre-treatment with 5-HT blocks the L-glutamate response of the transverse and dorso-ventral muscles but has no effect on the longitudinal fibres. These results suggest that a secondary innervation pathway exists in musculature responsible for producing complex movements, such as the fin, but not in those with a simpler mode of action, like the mantle.

The six Dorsal Longitudinal flight Muscles (DLMs) of Drosophila develop from three larval muscles that persist into metamorphosis and serve as scaffolds for the formation of the adult fibers. We have examined the effect of muscle scaffold ablation on the development of DLMs during metamorphosis. Using markers that are specific to muscle and myoblasts we show that in response to the ablation, myoblasts which would normally fuse with the larval muscle, fuse with each other instead, to generate the adult fibers in the appropriate regions of the thorax. The development of these de novo DLMs is delayed and is reflected in the delayed expression of erect wing, a transcription factor thought to control differentiation events associated with myoblast fusion. The newly arising muscles express the appropriate adult-specific Actin isoform (88F), indicating that they have the correct muscle identity. However, there are frequent errors in the number of muscle fibers generated. Ablation of the larval scaffolds for the DLMs has revealed an underlying potential of the DLM myoblasts to initiate de novo myogenesis in a manner that resembles the mode of formation of the Dorso-Ventral Muscles, DVMs, which are the other group of indirect flight muscles. Therefore, it appears that the use of larval scaffolds is a superimposition on a commonly used mechanism of myogenesis in Drosophila. Our results show that the role of the persistent larval muscles in muscle patterning involves the partitioning of DLM myoblasts, and in doing so, they regulate formation of the correct number of DLM fibers.

The development and degeneration of the flight muscles in adult crickets, Gryllus bimaculatus, were studied (1) by determination of the total protein content, (2) by SDS one-dimensional polyacrylamide gel electrophoresis (SDS­PAGE) of muscle protein and (3) by in vitro culturing of the muscle. The total protein content of the dorso-longitudinal muscle (DLM) and metathoracic dorso-ventral muscle (DVM) increased during the early days of adult life in both sexes. This high protein content was maintained for at least a further 10 days in some individuals, while in others it declined to a low level. Mesothoracic DVMs in males also showed an increase in protein content after adult emergence but did not undergo histolysis, whereas those in females showed no significant temporal change in protein content. Removal of hind wings or artificial de-alation was found to be useful in inducing degeneration of DLMs and metathoracic DVMs. This treatment also stimulated ovarian development in females. An analysis by SDS­PAGE provided no evidence for new protein synthesis prior to or during flight muscle degeneration. A high rate of [3H]- or [35S]methionine incorporation was observed in DLMs taken from newly emerged adults, but, in intact crickets, the rate declined rapidly during the first 3 days of adult life, a pattern consistent with that obtained from the measurement of total protein content. Compared with DLMs removed from intact crickets, DLMs taken from de-alated crickets showed reduced rates of protein synthesis during in vitro culturing. This, together with the onset of protein degradation, appears to cause the rapid decrease in total protein content of the muscle in de-alated crickets.

The synaptic potentials generated in neuromodulatory octopaminergic dorsal unpaired median (DUM) neurones by afferents excited by twitch contractions of a dorso-ventral flight muscle were investigated in the locust. Responses to stimulation of the metathoracic wing elevator muscle 113 were obtained in locusts in which all sensory feedback from the thorax had been removed, except for feedback from the thoracic chordotonal organs, the axons of which enter via the purely sensory nerve 2. Afferents in nerve 2C, which originates from two chordotonal organs, responded reliably to twitch contractions of this flight muscle. Octopaminergic neurones innervating leg muscles (DUM5 neurones) received depolarising inputs and often spiked following stimulation of the muscle. In contrast, those innervating the wing muscles themselves (DUM3 and DUM3,4 neurones) received inhibitory inputs. The responses of DUM3,4,5 neurones, which project mainly to leg muscles, were more complex: most were excited by twitch contractions of M113 but some were inhibited. DUMDL, which innervates the dorsal longitudinal indirect flight muscles, showed no clear response. Direct stimulation of nerve 2C evoked depolarising inputs and spikes in DUM5 neurones and hyperpolarising inputs in DUM3 and DUM3,4 neurones. Our data suggest that sensory feedback from thoracic chordotonal organs, which are known to be activated rhythmically during flight, contributes to the differential activation of efferent DUM neurones observed during flight.

We have investigated the pattern of metabolic changes during tethered flight with and without lift generation in the African fruit beetle Pachnoda sinuata. Two distinct metabolic phases occur during lift-generating flight. The first phase is characterised by a high rate of oxygen consumption and a rapid change in proline and alanine levels in the haemolymph and flight muscles and in glycogen level in the flight muscles. Carbohydrates are released from the fat body into the haemolymph. These carbohydrates are oxidised during the second phase. Changes in proline and alanine levels in the haemolymph and flight muscles and in glycogen level in the flight muscles are minor during the second phase and the rate of oxygen consumption is reduced. During lift-generating flight, metabolic changes are rapid. Proline concentrations in the haemolymph and flight muscles fall dramatically during the first 30 s of flight, while alanine concentrations rise concomitantly. While haemolymph concentrations of proline and alanine remain virtually unchanged thereafter, further changes in the levels of these amino acids occur in the flight muscles during 5 min of flight. The initial levels of the two amino acids in the flight muscles are re-established over 1 h of rest following a 5 min flight, while this process takes longer in the haemolymph. The concentration of haemolymph carbohydrates increases during the first 30 s of flight and declines thereafter during 5 min of flight. The pre-flight levels are restored after 1 h of subsequent rest. The stores of glycogen in the flight muscles are rapidly diminished during the first 10 s of flight and decrease at a lower rate during further flight lasting up to 5 min. A subsequent 1 h of rest is sufficient almost to restore pre-flight levels. Haemolymph lipid levels are slightly but significantly increased during 11 min of flight and after 1 h of subsequent rest. During flight without lift production, the metabolic changes are considerably slower and beetles fly approximately seven times longer than during lift-generating flight. Resting basalar (BM), dorso-ventral (DVM) and dorso-longitudinal (DLM) flight muscles show no differences in levels of proline, alanine and glycogen. After different periods of flight, during which lift and wing loading were minimised, the DVM was found to have the highest level of proline after 5 min of flight. Levels of alanine in the DVM were lower than in the DLM. There was no evidence to suggest that different flight muscles are specialised for either proline or carbohydrate utilisation. Proline and carbohydrates participate equally in supplying energy to the flight muscles during lift-generating flight. The contribution to the energy supply by the flight muscles is 54 %, while that of the haemolymph is 46 %.

Two new genera of geoplaninid land planarians are described. Cephalic specialisations, mainly external morphology and musculature development, partially define each genus. Cephaloflexa, gen. nov. shows some peculiar characteristics, such as a gradual narrowing of the anterior third of the body and an upwards roll of the anterior tip, the absence of eyes and sensory pits on the apex, and the existence of a retractor muscle derived from the ventral cutaneous longitudinal musculature. Geoplana bergi Graff, 1899 is allocated to Cephaloflexa and is designated as the type species. The ventral cutaneous longitudinal muscles of Supramontana, gen. nov. (monotypic), are partially sunk into the mesenchyme, thus constituting a cephalic retractor muscle. A new species of each genus is also described. The external morphology and anatomy of the cephalic region of the new genera and of Geoplana Stimpson, 1857, Choeradoplana Graff, 1896 and Issoca C. G. Froehlich, 1955 are analysed. Emendations to the diagnoses of Issoca and Choeradoplana are proposed based on cephalic differentiations. Spanish abstractSe decriben Cephaloflexa, gen. nov. y Supramontana, gen. nov., dos nuevos géneros de planarias terrrestres de la subfamilia Geoplaninae, ambos caracterizados por especializaciones cefálicas, como la morfología externa y el desarrollo muscular. Se describe una nueva especie de cada género. Se transfiere Geoplana bergi Graff, 1899 para el género Cephaloflexa y se la designa especie tipo. Cephaloflexa, gen. nov. presenta características peculiares, como el tercio anterior del cuerpo muy fino, región anterior enrollada hacia el dorso, ausencia de ojos y fosetas sensoriales en el ápice anterior del cuerpo, y un músculo retractor derivado de la musculatura subcutánea longitudinal ventral. Supramontana, gen. nov., género monotípico, tiene parte de la musculatura subcutánea longitudinal ventral hundida en el mesénquima y transformada en la región anterior en un músculo retractor cefálico. Se analiza la morfología externa y la anatomía de la región cefálica de Geoplana Stimpson, 1857, Choeradoplana Graff, 1896 e Issoca Froehlich, 1955 y se proponen enmiendas a las diagnosis de Choeradoplana e Issoca basadas en las diferenciaciones cefálicas.

Manoeuvring flight in animals requires precise adjustments of mechanical power output produced by the flight musculature. In many insects such as fruit flies, power generation is most likely varied by altering stretch-activated tension, that is set by sarcoplasmic calcium levels. The muscles reside in a thoracic shell that simultaneously drives both wings during wing flapping. Using a genetically expressed muscle calcium indicator, we here demonstrate in vivo the ability of this animal to bilaterally adjust its calcium activation to the mechanical power output required to sustain aerodynamic costs during flight. Motoneuron-specific comparisons of calcium activation during lift modulation and yaw turning behaviour suggest slightly higher calcium activation for dorso-longitudinal than for dorsoventral muscle fibres, which corroborates the elevated need for muscle mechanical power during the wings’ downstroke. During turning flight, calcium activation explains only up to 54 per cent of the required changes in mechanical power, suggesting substantial power transmission between both sides of the thoracic shell. The bilateral control of muscle calcium runs counter to the hypothesis that the thorax of flies acts as a single, equally proportional source for mechanical power production for both flapping wings. Collectively, power balancing highlights the precision with which insects adjust their flight motor to changing energetic requirements during aerial steering. This potentially enhances flight efficiency and is thus of interest for the development of technical vehicles that employ bioinspired strategies of power delivery to flapping wings.

In addition to true tagmata, various pseudotagmata are present in chelicerates. Greatly miniaturized and morphologically simplified phytoparasitic acariform mites of the superfamily Eriophyoidea demonstrate a distinct ability to form pseudotagmata. The prodorsum and opisthosoma are the primary divisions of the eriophyoid body. In more evolutionary derived lineages, there is a trend towards the formation of additional opisthosomal subdivisions (pseudotagmata). These subdivisions are termed here “cervix”, “postprodorsum”, “pretelosoma”, “telosoma” and “thanosoma”. Among phytoptids, only the telosomal pseudotagma is present in several sierraphytoptine genera. In diptilomiopids, pseudotagmata have not been recorded. The most diverse examples of pseudotagmatization concern vagrant mites from the family Eriophyidae. Remarkably, well developed and unusually shaped pseudotagmata are peculiar to phyllocoptines from palms, especially in the new vagrant mite Pseudotagmus africanus n. g. & n. sp., found on leaves of Hyphaene coriacea (Arecaceae) in South Africa. Pseudotagmosis is one form of body consolidation in Eriophyoidea, reducing flexibility and therefore decreasing the ability for worm-like locomotion. Consequently, the legs become more important for locomotion. The other form of body consolidation is strengthening of the exoskeleton via armoring with microtubercles, and topographical changes (e.g. formation of opisthosomal ridges and furrows). The data at hand suggest that ancestrally, eriophyoids had an elongate body comprising many annuli, which can be regarded as pseudosegments. Later, they convergently evolved various pseudotagmata via the apparent fusion of these pseudosegments. Two morphotypes of vagrant mites (“armadillo” and “pangolin”) are proposed based on the difference in the modification of dorsal opisthosomal annuli. The minimal number of dorsal annuli (six) is equal to the number of dorso-longitudinal peripheral body muscles; however, this number is unlikely to reflect the true number of segments situated behind the prodorsum in Eriophyoidea. Although legs III and IV are absent in Eriophyoidea, the cervical pseudotagmata might be reminiscent of metapodosomal segments. Future comparative myo- and neuroanatomy studies of groups of genes involved in segmentation development are necessary to reach the final conclusion on the pattern of body segmentation in Eriophyoidea.