THE STRUCTURE OF FLIGHT MUSCLE SARCOSOMES IN THE BLOWFLY CALLIPHORA ERYTHROCEPHALA (DIPTERA)

SUMMARYTaylor and Weibel's theory of symmorphosis predicts that structures of the respiratory system are matched to maximum functional requirements with minimal excess capacity. We tested this hypothesis in the respiratory system of the migratory locust . Therefore, the principles of symmorphosis are upheld at each step of the oxygen cascade in the respiratory system of the migratory locust. Supplementary material available online at

Section: Mitochondria As Oxygen Sinkssupporting

confidence: 80%

Section: Mitochondria As Oxygen Sinksmentioning

confidence: 73%

Symmorphosis and the insect respiratory system: allometric variation

Snelling

Seymour

Runciman

et al. 2011

“…This is supported by the fact that mitochondrial volume densities found in Clione spp. (Fig.3) are on par with those found in the flight muscle of hummingbirds (~35%), honeybee (~43%) (Suarez et al, 1991;Suarez et al, 2000) and blowfly (~43%) (Smith, 1963). Mitochondrial densities in the fibers of Clione spp.…”

Section: Muscle Ultrastructuresupporting

confidence: 50%

Temperature compensation of aerobic capacity and performance in the Antarctic pteropod,Clione antarctica, compared to its northern congener,C. limacina

Dymowska

Manfredi

Rosenthal

et al. 2012

SUMMARYIn ectotherms living in cold waters, locomotory performance is constrained by a slower generation of the ATP that is needed to fuel muscle contraction. Both polar and temperate pteropods of the genus Clione, however, are able to swim continuously by flapping their parapodia (wings) at comparable frequencies at their respective habitat temperatures. Therefore, we expected polar species to have increased aerobic capacities in their wing muscles when measured at common temperatures. We investigated muscle and mitochondrial ultrastructure of Clione antarctica from the Southern Ocean (-1.8°C) and populations of a sister species, Clione limacina, from the Arctic (-0.5 to 3°C) and from the North Atlantic (10°C). We also measured oxygen consumption and the activity of the mitochondrial enzyme citrate synthase (CS) in isolated wings of the two species. The Antarctic species showed a substantial up-regulation of the density of oxidative muscle fibers, but at the expense of fast-twitch muscle fibers. Mitochondrial capacity was also substantially increased in the Antarctic species, with the cristae surface density (58.2±1.3m ). The values for cold-adapted populations are on par with those found in highperformance vertebrates. As a result of oxidative muscle proliferation, CS activity was 4-fold greater in C. antarctica wings than in temperate C. limacina when measured at a common temperature (20°C). Oxygen consumption of isolated wing preparations was comparable in the two species when measured at their respective habitat temperatures. These findings indicate complete compensation of ATP generation in wing muscles across a 10°C temperature range, which supports similar wing-beat frequencies during locomotion at each speciesʼ respective temperature. The elevated capacity in the wing muscles is reflected in the partial compensation of whole-animal oxygen consumption and feeding rates.

“…In addition, the density of mitochondria in locust flight muscle is only 20% (Snelling et al, 2012), which is also modest compared with reports of around 40% in other insects (Casey et al, 1992;Josephson et al, 2000;Smith, 1963;Suarez et al, 2000). The study also calculated that each tracheole in the locust flight motor supplies oxygen to around 119m 2 of surrounding muscle, which cannot yet be compared against other insects because of a lack of data, but presumably species with flight motors operating at around twice the power-density of locusts should possess tracheoles that service around one-half the area of muscle.…”

Section: Low Energy Expenditure Of Locust Flightmentioning

confidence: 68%

Maximum metabolic rate, relative lift, wingbeat frequency, and stroke amplitude during tethered-flight in the adult locustLocusta migratoria

Snelling

Seymour

Matthews

et al. 2012

. The modest flight metabolic rate of locusts is unlikely to be an artefact of individuals failing to exert themselves, because mean maximum lift was not significantly different from that required to support body mass (95±8%), mean wingbeat frequency was 23.7±0.6Hz, and mean stroke amplitude was 105±5deg in the forewing and 96±5deg in the hindwing -all of which are close to free-flight values. Instead, the low cost of flight could reflect the relatively small size and relatively modest anatomical power density of the locust flight motor, which is a likely evolutionary trade-off between flight muscle maintenance costs and aerial performance.