bluuebunny/crossref_metadata_2025_split huggingface dataset:
Muscle Action During Locomotion: A Comparative Perspective
Authors: Johnston Ian A. 
Published: April 2021

ABSTRACT
This essay explores how the properties of striated muscles are matched to the tasks they perform during running, swimming and flying. During exercise the major locomotory muscles undergo alternate cycles of lengthening and shortening. Force development is greatly influenced by the timing of stimulation in relation to the length-change cycle and by the nature of elastic structures connecting the muscle fibres to the skeleton. The storage and recovery of elastic strain energy by the tendons (apodema in insects) results in a considerable saving of metabolic energy. Strain is independent of locomotory frequency, body size and muscle temperature. In contrast, the frequency of cycles, and hence strain rate, generally increases with speed and is inversely proportional to body size. The maximum isometric stress (P0) striated muscles can exert is rather similar. During steady running or hopping in mammals the peak muscle stress is around one-third of P0. Behaviours such as vertical jumping impose higher stresses requiring disproportionately larger muscles and tendons, which may limit the storage of elastic strain energy. Muscles of small animals consume significantly more energy per gram than do those of large ones. This may be because they need to activate and deactivate their muscles at a higher rate to move at an equivalent speed. When differences in force production are normalised, by multiplying the energy consumed per stride by stride frequency, similar values for the mass-specific cost of locomotion are found in animals with different leg architectures, numbers of legs, skeletal type, body sizes and muscle temperatures.
The power output of isolated muscle fibres can be measured by imposing cyclical strain fluctuations and stimulating briefly during each cycle to approximate normal operating conditions in vivo. This approach yields values for maximum power output of 76–130 W kg−1 for synchronous insect flight muscles at temperatures and wingbeat frequencies appropriate for flight. Frog sartorius muscle produces 20 W kg−1 at the hopping frequency used during escapes at 20°C. The strain rates and deactivation rates of muscle fibres are optimised to produce maximum power over a particular range of locomotory frequencies. In vertebrates this necessitates the sequential recruitment of muscle fibre types with faster maximum strain rates and shorter contraction times as speed increases. Estimates of overall muscle efficiency during locomotion in insects, fish and small mammals are mostly in the range 6–20%.
The Energetics and Cardiorespiratory Correlates of Mammalian Terrestrial Locomotion
Authors: Baudinette R. V. 
Published: April 2021

ABSTRACT
Energy costs of locomotion in mammals can be predicted from running speed and body mass, with the minimum cost decreasing regularly with increasing mass (Mb−0.30). The predictive value of this model is surprising, given the differences in gait and limb structure among mammals. The decrease in mass-specific cost cannot be explained by the work done in moving the limbs and the centre of mass, as animals of different sizes do the same amount of work to move a unit mass a unit distance. The magnitude of the muscle forces involved and the shortening velocity are more likely causes. Terrestrial mammals use a variety of gaits to minimise locomotory energy costs with a ‘preferred speed’ within each of those gaits correlating with the point of greatest economy. The maximum mass-specific energy cost during locomotion is about 10 times the resting level, but there is marked variation among species, especially between wild and domestic forms.
The total cost for locomotion in mammals lies between 1 and 6% of the daily energy budget. Hopping is an energetically cheap way of moving in large animals and correlates with phase-locking of respiratory and limb frequencies. This form of coupling is also seen in most other mammals, especially at higher running speeds.
Comparison of the relative costs of running, flying and swimming for a given body mass shows a respective decrease, but each of these costs scales similarly with body size.
Limitations on Animal Flight Performance
Authors: Ellington C. P. 
Published: April 2021

ABSTRACT
Flight performance seems to change systematically with body size: small animals can hover and fly over a wide range of speeds, but large birds taxi for takeoff and then fly over a narrow speed range. The traditional explanation for this is that the mass-specific power required for flight varies with speed according to a U-shaped curve, and it also scales between m0 and m1/6, where m is body mass. The mass-specific power available from the flight muscles is assumed to scale as m−1/3 As available power decreases with increasing body size, the range of attainable flight speeds becomes progressively reduced until the largest animals can only fly in the trough of the U-shaped curve. Above a particular size, the available power is insufficient and flapping flight is not possible.
The underlying assumptions of this argument are examined in this review. Metabolic measurements are more consistent with a J-shaped curve, with little change in power from hovering to intermediate flight speeds, than with a U-shaped curve. Scaling of the mass-specific power required to fly agrees with predictions. The mass-specific power available from, the muscles, estimated from maximal loading studies, varies as m0.13. This scaling cannot be distinguished from that of the power required to fly, refuting the argument that power imposes an intrinsic scaling on flight performance. It is suggested instead that limitations on low-speed performance result from an adverse scaling of lift production with increasing body size
Rotational Movement of a Spermatozoon Around Its Long Axis
Authors: Ishijima Sumio , Hamaguchi Miyako S. , Naruse Masakazu , Ishijima Sanae A. , Hamaguchi Yukihisa 
Published: April 2021

ABSTRACT
The rotational movement of a spermatozoon around its longitudinal axis was investigated by two methods: by observing a spermatozoon attached vertically to a coverslip by the tip of its head, and by observing a spermatozoon freely swimming in a medium by means of ‘double-focal microscopy’, which yielded simultaneous images at two different focal planes.
Similar results were obtained by these two methods. Sea urchin, starfish, medaka, human, golden hamster and bull spermatozoa rolled in both clockwise and counterclockwise directions, although there was a large difference in the proportion of spermatozoa rolling in each direction in the different species. The majority of sea urchin and starfish spermatozoa rolled in a clockwise direction when an observer viewed the cell from its anterior end, whereas the majority of medaka, golden hamster, human and bull spermatozoa rolled in a counterclock-wise direction relative to the same observer. Moreover, some spermatozoa occasionally changed their rotational direction.
These results suggest that the mechanism regulating the direction of rotation of the spermatozoa is lax. As rotational movement of a spermatozoon around its longitudinal axis is due to the three-dimensional component of the beat of the flagellum, the direction of the three-dimensional movement presumably changes as the spermatozoa swim.
Penetration of Water Into Blind-Ended Capillary Tubes and Its Bearing on the Functional Design of the Lungs of Soldier Crabs Mictyris Longicarpus
Authors: Maitland David P. , Maitland Arthur 
Published: April 2021

ABSTRACT
Soldier crabs, Mictyris longicarpus Latreille, inhabit intertidal sand-flats of Eastern Australia. Their gill chambers are modified for both water circulation and air-breathing. Water circulates through the lower gill compartments. The upper regions of the gill chambers are air-filled and function as lungs. The deep vascular parenchyma lining the upper gill chambers, or lungs, is penetrated by a regular series of fine branching airways. Scanning electron micrographs of lung architecture are shown. Measurements relating to lung structure were made on plastic casts.
Because of the lung’s design, water circulating through the lower gill compartments does not interfere with lung function. The airways are blind-ended and nonanastomosing, acting in effect as air-filled capillary tubes sealed at one end. A mathematical model and explanation show how the air trapped within this lung structure substantially reduces water penetration, despite surface tension (capillary) processes. This same lung design also facilitates the shedding of the lung cuticle at each moult.
Response Properties Of Interneurons Of The Cricket Cercal Sensory System Are Conserved In Spite Of Changes In Peripheral Receptors During Maturation
Authors: Chiba Akira , Kämper Günter , Murphey R. K. 
Published: April 2021

ABSTRACT
During postembryonic development of the cricket, the total number of filiform hair sensilla in the cereal sensory system increases approximately 40-fold. In addition, individual receptor hairs grow in size, changing the transducer properties of the sensilla and, thereby, the information transmitted to the central nervous system (CNS) by the sensory neurons. Interneurons MGI and 10-3 receive monosynaptic inputs from these sensory neurons and send outputs to anterior ganglia. We show that, in spite of the changes in the periphery, the response properties of these interneurons are relatively constant during development. The two interneurons differ in their frequency response, intensity response and rate of response decrement. Their respective response properties are conserved during the postembryonic period. The results suggest that systematic rearrangement of the sensory neuron-to-interneuron synapses plays an important role in maintaining a constant output of this sensory system to higher centers of the CNS during maturation of the cricket.
Individual and Sex Specificity in the Electric Organ Discharges of Breeding Mormyrid Fish (Pollimyrus Isidori)
Authors: Crawford John D. 
Published: April 2021

ABSTRACT
I monitored the electric organ discharges (EODs) of 14 Pollimyrus isidori, (Cuvier and Valenciennes) during an artificially induced breeding season, to examine sex and individual differences in reproductive fish. EODs were repeatedly recorded over an 11-day period to ascertain the stability of each individual’s EOD and to make a quantitative assessment of sex differences. Within days, I found the individual’s EOD to be constant from one EOD to the next. Over the 11-day sampling period, individuals were also quite stable and exhibited only slight changes in EOD duration and relative amplitude of the phases of the waveform. I found that the differences between individuals of the same sex were highly significant in measures of EOD duration and in measures of the relative amplitude of the phases. Differences between the sexes were also highly significant in relative amplitude but were not significant in duration. In a multivariate discriminant function analysis, I have found that individual fish can be correctly classified on the basis of temporal, relative amplitude and spectral cues in the EOD, despite slight changes in these parameters with time. The EOD exhibits characteristics of a good signature in the context of an information system.
The Profile Drag of A Hawk’s Wing, Measured by Wake Sampling in A Wind Tunnel
Authors: Pennycuick C. J. , Heine Carlton E , Kirkpatrick Sean J. , Fuller Mark R. 
Published: April 2021

ABSTRACT
The distribution of dynamic pressure behind a Harris’ hawk’s wing was sampled using a wake rake consisting of 15 pitot tubes and one static tube. The hawk was holding on to a perch, but at an air speed and gliding angle at which it was capable of gliding. The perch was instrumented, so that the lift developed by the wing was known and the lift coefficient could be calculated. The mean of 92 estimates of profile drag coefficient was 0.0207, with standard deviation 0.0079. Lift coefficients ranged from 0.51 to 1.08. Reynolds numbers were nearly all in the range 143000–194000. The estimates of profile drag coefficient were reconcilable with previous estimates of the wing profile drag of the same bird, obtained by the subtractive method, and also with values predicted by the ‘Airfoil-ii’ program for designing aerofoils, based on a digitized wing profile from the ulnar region of the wing. The thickness of the wake suggested that the boundary layer was mostly or fully turbulent in most observations and separated in some, possibly as an active means of creating drag for control purposes. It appears that the bird could momentarily either increase or decrease the profile drag of specific parts of the wing, by active changes of shape, and it appeared to use the carpo-metacarpal region especially for such control movements. Further investigation in a low-turbulence wind tunnel would help to resolve doubts about the possible influence of airstream turbulence on the behaviour of the boundary layer.
The Perception Of The Visual Flow Field By Flying Locusts: A Behavioural And Neuronal Analysis
Authors: Baader Andreas , Schäfer Marcel , Rowell C. H. F. 
Published: April 2021

ABSTRACT
Tethered locusts (Locusta migratoria’) were stimulated with an artificial flow field (FF) device, which produced the visual effect of forward motion (‘progressive flow field’) or backward motion (‘regressive flow field’). Progressive FFs (contrast frequencies, CF, of 2–10Hz and angular period of pattern, λ, of 33° or 42°) can initiate and maintain flight, even without frontal wind. Regressive FFs inhibit flight. The locusts adjust their wingbeat frequency (and thus probably their flight speed) in response to a gradually changing FF contrast frequency; they fly faster when the FF motion is faster and vice versa. Sudden decelerations of FF motion, however, are transiently counteracted by increases in wingbeat frequency. Rotational movements of the entire flow field device, simulating yaw and/or roll deviations during progressive flight, elicit compensatory steering responses of the head and abdomen. Corrective steering behaviour and simultaneously presented FF stimuli do not influence each other. A descending interneurone (FFDN1) is described which reports the progressive visual FF. It receives input from both compound eyes, prefers FFs on the ventral retina, and responds over the range of contrast frequencies of 1–20 Hz. Its response is tonic and adapts only weakly to maintained FF stimuli. It follows changing FF velocities but tends to counteract sudden decelerations. In addition, FFDN1 is excited by frontal and contralateral wind and inhibited by ipsilateral wind. It is also excited by the flight motor and sometimes by light-off at the ocelli. The neurone is generally insensitive to simulated roll and yaw deviations. Electrical stimulation of the cell can result in lifting of the abdomen, inhibition of dorsal neck muscle activity, and occasional flight muscle spikes. FFDN1 is probably a sister cell of the previously described DNM neurone, but the two could be one neurone with very variable responses. At least one further descending interneurone responding selectively to progressive flow fields, but with a different morphology, is present in the central nervous system. Additionally, two different thoracic intemeurones have been found with properties suggesting that they are postsynaptic to FFDNs and presynaptic to the flight circuitry.
5. The possible role of the visual flow field in the regulation of flight activity of locusts and other insects is discussed.
Heart Rates and Swim Speeds of Emperor Penguins Diving Under Sea Ice
Authors: Kooyman Gerald L. , Ponganis Paul J. , Castellini Michael A. , Ponganis Edward P. , Ponganis Katherine V. , Thorson Philip H. , Eckert Scott A. , Lemaho Yvon 
Published: April 2021

ABSTRACT
Heart rate during overnight rest and while diving were recorded from five emperor penguins with a microprocessor-controlled submersible recorder. Heart rate, cardiac output and stroke volume were also measured in two resting emperor penguins using standard electrocardiography and thermodilution measurements. Swim velocities from eight birds were obtained with the submersible recorder. The resting average of the mean heart rates was 72 beats min−1. Diving heart rates were about 15 % lower than resting rates. Cardiac outputs of 1.9–2.9mlkg−1 s−1 and stroke volumes of 1.6–2.7 ml kg−1 were similar to values recorded from mammals of the same body mass. Swim velocities averaged 3ms−1. The swim speeds and heart rates suggest that muscle O2 depletion must occur frequently: therefore, many dives require a significant energy contribution from anaerobic glycolysis.
Interactive Effects of Seasonal Temperature and Low pH on Resting Oxygen Uptake and Swimming Performance of Adult Brown Trout Salmo Trutta
Authors: Butler P. J. , Day N. , Namba K. 
Published: April 2021

ABSTRACT
Adult brown trout were acclimated for 2–4 weeks to artificial, soft water (Ca2+ 25μmol l-1) at neutral pH and at summer (15°C) or winter (5°C) temperatures. During this period they swam against a current of approximately 0.25 ms-1. They were then exposed to neutral or sublethal pH for 4 days in still water. For fish with their dorsal aorta catheterized, sublethal pH was 4 at 5°C and 4.5 at 15°C.
After 4 days of exposure to sublethal pH, resting oxygen uptake was 40 % higher than that at neutral pH for fish held at 15 °C and 38 % higher for fish held at 5°C. Critical swimming speeds (Ucrit), in contrast, were 35% and 31% lower, respectively. These two phenomena may be related in as much as the ‘metabolic cost’ of exposure to low pH may increase as swimming speed increases, thus reducing the scope for activity. Another important factor could be an impairment of oxygen delivery to the red muscle fibres. Although arterial O2 concentrations and heart rate are both similar for fish at Ucrit in neutral and acid water, there are signs of haemoconcentration in fish exposed to low pH, and the consequent increase in blood viscosity could disrupt the local circulation in the red fibres. Whatever its causes, an impairment of swimming activity resulting from exposure to acid water may have severe consequences for active fish such as salmonids.
Exposure to sublethal pH caused significant reductions in plasma Na+ and Cl-concentrations at both temperatures, although these were more substantial at 5°C than at 15 °C. Swimming at Ucrit had no significant effect on plasma concentrations of Na+, K+ and Cl- except at sublethal pH at 5°C, when there were significant reductions in all three.
Seasonal temperature had significant but small effects on resting and Ucrit, and these are discussed in terms of the possible effects of low temperature and continued swimming activity (training) on hypertrophy of skeletal and cardiac muscles and on the aerobic capacity of the ‘red’ muscle fibres.
Walking of the Shore Crab Pachygrapsus Crassipes in its two Natural Environments
Authors: Hui Clifford A. 
Published: April 2021

ABSTRACT
Video analyses of crabs walking on smooth and rocky terrains when in air and when submerged in water were conducted. Modifications of walking in the two environments, between which the animal’s weight changes sixfold, are consistent with the goals of maximizing ease of walking and minimizing risk of injury. The duty factor (fraction of step cycle in which the dactylus is in contact with the substratum) was greater than 50 % when in air compared to less than 46 % when submerged, indicating a need for greater stability against the destabilizing vertical force of gravity when in air. The duty factors of the trailing and leading leg rows were the same for the two terrains in air but the trailing leg row had a larger duty factor when submerged, indicating a greater pushing effort to overcome drag forces. Width of stance differed among the four conditions and was narrowest in animals walking over rocky terrain in air, the condition which has the greatest potential for injury. The mean phase difference (percentage of a step cycle by which ipsilateral legs differ) between leading and trailing rows did not differ under any condition except for submerged smooth terrain, meeting the unique requirements of that condition. The observed walking speed range had no effect on stance, duty factor or phase difference.
Arterio-Venous Branchial Blood Flow in the Atlantic Cod Gadus Morhua
Authors: Sundin Lena , Nilsson Stefan 
Published: April 2021

ABSTRACT
We have estimated the branchial venous blood flow in the Atlantic cod by direct single-crystal Doppler blood flow measurements in vivo. In the undisturbed animal, this flow amounts to 1.7 ml min−1 kg−1, which corresponds to about 8 % of the cardiac output. Studies of both an isolated perfused gill apparatus in situ and simultaneous measurements of cardiac output and branchial venous flow in vivo were made to assess the effects of some putative vasoregulatory substances. Adrenaline dilates the arterio-arterial pathway and constricts the arterio-venous pathway, thus decreasing branchial venous drainage. 5-Hydroxytryptamine (5-HT), in contrast, produced marked vasoconstriction in the arterio-arterial pathway of the branchial vasculature, increasing the branchial venous blood flow. Cholecystokinin-8 (CCK-8) and caerulein produced similar cardiovascular effects, with marked constriction of both arterio-arterial and arterio-venous pathways. The study demonstrates the ability of the vascular system of the gills to regulate the distribution of branchial blood flow, and summarizes the vasomotor effects of some substances with possible vasomotor function in the cod gills.
Integrating Metabolic Pathways in Post-Exercise Recovery of White Muscle
Authors: Schulte Patricia M. , Moyes Christopher D. , Hochachka Peter W. 
Published: April 2021

ABSTRACT
Purine nucleotides (ATP, ADP, AMP, IMP), creatine, phosphocreatine, lactate, pyruvate and glycogen were measured in rainbow trout (Oncorhynchus my kiss) white muscle following exercise to exhaustion. Estimates of intracellular pH permitted calculation of free concentrations of nucleotides ([nucleotide]f) required for most models of control of energy metabolism. Creatine charge, [PCr]/([PCr]+[Cr]), fell from 0.49±0.05 (mean±S.E.M.) to 0.08±0.02 with exercise but recovered completely by the first sample (2h). Although [ATP] declined to 24% of resting levels and recovered very slowly, RATP, [ATP]/ ([ATP] + [ADP]f+[AMP]f), and energy charge, EC, ([ATP]+0.5[ADP]f)/ ([ATP] + [ADP]f+[AMP]f), recovered as quickly as creatine charge. Changes in [IMP] mirrored those in [ATP], suggesting that AMP deaminase is responsible for maintaining RATP and EC. Recovery of carbon status was much slower than recovery of energy status. Lactate increased from 4 μmol g−1 at rest to 40 μmol g−1 at exhaustion and did not recover for more than 8h. Glycogen depletion and resynthesis followed a similar time course. During the early stages of recovery, calculated [ADP]f declined by more than 10-fold relative to the resting values. The resulting high [ATP]/[ADP]f ratios may limit the rate at which white muscle mitochondria can produce ATP to fuel glycogenesis in situ. It is postulated that the high [ATP]/[ADP]f ratios are required to drive pyruvate kinase in the reverse direction for glyconeogenesis in recovery.