bluuebunny/crossref_metadata_2025_split huggingface dataset:
Innervation Patterns of Fast and Slow Motor Neurones During Development of A Lobster Neuromuscular System
Authors: J Costello Walter , Hill Russell , Lang Fred 
Published: April 2021

ABSTRACT
Relationships between motor innervation and muscle fibre type were examined in the closer muscle of the claws of the lobster Homarus americanus. The dimorphic claws of the adult-the cutter and crusher-were compared with the claws of the juvenile (stages 4–6) when differentiation takes place. The muscle is known to receive a fast and a slow motor axon. Previous findings have shown that the crusher contains mostly slow fibres ; the cutter and juvenile claws have both fast and slow fibres. In the adult, the majority of fibres in the crusher received fast and slow axons; in the cutter most fibres received the fast axon. Fast fibres in the cutter claw were innervated by the fast axon, alone or with the slow axon. Slow fibres in both claws could receive the slow axon only, or both axons. Some slow fibres in the crusher claw were innervated primarily or solely by the fast axon. In the juvenile, most fibres in each claw were innervated by both axons. The juvenile synapses were immature; postsynaptic potentials fluctuated greatly with frequent failures. The homologous fast axons in these claws formed fatigue-resistant synapses. In both adult and juvenile, regardless of fibre type, fast axon synapses had poor facilitation ; slow axon synapses had moderate-to-high facilitation.
A Note On the Cell Water Density in Amphibian Eggs
Authors: Mild Kjell Hansson , Løvtrup Søren 
Published: April 2021

ABSTRACT
In a recent publication of ours on cell water density in amphibian eggs (Hansson Mild, Løvtrup & Forslind, 1979), the relation between the egg density, ρ, and the water content was established experimentally. It was then assumed that ρ could be theoretically related to the cell water density, ρω, and the density of the solids in the cell, ρs, on a weight average basis (equation (10) in Hansson Mild et al. 1979). However, this assumption is not correct, a fact which has been brought to our attention by Drs W. Drost-Hansen and J. Clegg (personal communication, 1980). Instead the egg density should be related to ρω and ρs on the basis of volume fractions as derived below.
Underwater Hearing in the Frog, Rana Catesbeiana
Authors: Lombard R. Eric , Fay Richard R. , Werner Yehudah L. 
Published: April 2021

ABSTRACT
Comparable auditory sound pressure level (SPL) and sound intensity level (SIL) threshold curves were determined in air and under water in Rana catesbeiana. Threshold curves were determined using chronic metal electrode implants which detected multi-unit responses of the torus semicircularis to incident sound. In terms of SPL, hearing thresholds in water and air are similar below 0·2 kHz. Above 0·2 kHz, the sensitivity under water falls off at about 16 dB/octave to reach an average loss of about 30 dB above 0·4 kHz. In terms of SIL, the organism is about 30 dB more sensitive under water than in air below 0·2 kHz and equally sensitive in air and water above 0·4 kHz. The relative merits of the two measures are discussed and an attempt is made to relate the results to morphology of the middle and inner ears. This report is the first to compare aerial and underwater hearing abilities in any organism using electrode implants.
Hindlimb Muscular Activity, Kinetics and Kinematics of Cats Jumping to Their Maximum Achievable Heights
Authors: Zajac Felix E. , Zomlefer Michael R. , Levine William S. 
Published: April 2021

ABSTRACT
Cats were trained to jump from a force platform to their maximum achievable heights. Vertical ground reaction forces developed by individual hindlimbs showed that the propulsion phase consists of two epochs. During the initial ‘preparatory phase’ the cat can traverse many different paths. Irrespective of the path traversed, however, the cat always attains the same position, velocity and momentum at the end of this phase. Starting from this dynamic state the cat during the subsequent ‘launching phase’ (about 150 ms long) generates significant propulsion as its hindlimbs develop force with identical, stereotypic profiles. Cinematographic data, electromyographic data, and computed torques about the hip, knee and ankle joints indicate that during the jump proximal extensor musculature is activated before distal musculature. During terminal experiments when the hindlimb was set at positions corresponding to those in the jump, isometric torques produced by tetanic stimulation of groups of extensor and flexor muscles were compared with computed torques developed by the same cat during previous jumps. These comparisons suggest that extensor muscles of the hindlimb are fully activated during the maximal vertical jump.
The Effect of Long-Term Aerial Exposure on Heart Rate, Ventilation, Respiratory Gas Exchange and Acid-Base Status in the Crayfish Austropotamobius Pallipes
Authors: Taylor E. W. , Wheatly Michèle G. 
Published: April 2021

ABSTRACT
When first removed into air, crayfish showed transient increases in heart rate (fH) and scaphognathite rate (fR) which rapidly recovered to submerged levels and were unchanged for 24 h. The rate of O2 consumption increased from an initially low level and was then maintained for 24 h in air at the same level as in settled submerged animals. There was an initial acidosis in the haemolymph which was both respiratory and metabolic due to the accumulation of CO2 and lactate. Progressive compensation by elevation of the levels of bicarbonate buffer in the haemolymph and reduction of circulating lactate levels returned pH towards submerged levels after 24 h in air. Exposure to air resulted in a marked internal hypoxia with haemolymph O2 tensions, both postbranchial and prebranchial remaining low throughout the period of exposure. The oxygen content of the haemolymph was initially reduced, with content difference close to zero. Within 24 h both and had returned towards their levels in submerged animals. These changes are explained by the Bohr shift on the haemocyanin consequent upon the measured pH changes. After 48 h in air, and fH were significantly reduced and ventilation became intermittent. There was a slight secondary acidosis, increase in lactic acid levels and reduction in content difference in the haemolymph. When crayfish were returned to water after 24 h in air, ,fH and fR were initially elevated by disturbance and there was a period of hyperventilation. In the haemolymph there was an initial slight alkalosis, and an increase in and lactic acid. All variables returned to their settled submerged levels within 8 h.
Branchial Ionic Uptake and Acid-Base Regulation in the Rainbow Trout, Salmo Gairdneri
Authors: Perry S. F. , Haswell M. S. , Randall D. J. , Farrell A. P. 
Published: April 2021

ABSTRACT
Amiloride (10−4 M) inhibited sodium uptake in rainbow trout by 78% and was associated with a pronounced acidosis and decreases in both plasma total CO2* and [HCO3−]. 4-acetamiao-4′-iso-thiocyanatostilbene-2,2′disulphonicacid (SITS) (10−4 *m) in the bathing medium inhibited chloride uptake by 66% and following 6 h a significant decrease in plasma [H +] and significant increases in and [HCO3−] were observed. Inhibition of chloride uptake (50%) with external sodium bicarbonate (12 mm) resulted in a more rapid and pronounced alkalosis than did SITS inhibition. Hypercapnic acidosis had no significant effect on the rates of branchial sodium and chloride uptake. Increasing the concentration of sodium in the bathing water resulted in a less pronounced acidosis and a more rapid pH recovery during hypercapnia. These results are discussed with reference to the gill as an acid-base regulating structure. These findings are consistent with a gill model previously presented by Haswell, Randall & Perry (1980).
Locomotion in Burrowing and Vagrant Wolf Spiders (Lycosidae)
Authors: Ward T. M. , Humphreys W. F. 
Published: April 2021

ABSTRACT
Locomotion in the vagrant wolf spider Trochosa ruricola is compared to that in the burrow dwelling wolf spider Lycosa tarentula (Araneae: Lycosidae). L. tarentula takes relatively shorter steps than T. ruricola. At high speeds T. ruricola approximates an alternating tetrapod gait but this does not occur in L. tarentula. Phase lag differs between species and varies marginally with speed except for ipsilateral phase lags in L. tarentula which are erratic if they include leg 1. In both species the protraction/retraction ratio is directly related to both running speed and stepping frequency, but the relationship is more marked in L. tarentula. The protraction/retraction ratio is more variable in leg 1 and varies between legs along the body but by a greater amount in L. tarentula. In these spiders, in contrast to the situation in many insects, both the duration of protraction and retraction show marked inverse relationships to stepping frequency. The power stroke (retraction) occupies a variable proportion of the stepping cycle, which is not the case in other spiders, and this proportion is lower than for other spiders.
It is suggested that the first pair of legs is used more for sensory than for locomotory purpose and that this is more marked in the burrow dwelling species, L. tarentula.
Short Communications: Steady State Potential in the Developing Oocytes of Locusta Migratoria: Passive and Active Components
Authors: Wollberg Z. , Cocos R. 
Published: April 2021

ABSTRACT
Ovarioles of the African migratory locust (Locusta migratoria) are of the panoistic type, where each oocyte is surrounded by a layer of follicle cells, and a single ovariole forms a longitudinal chain of ‘follicles’ held together by an ovariole sheath. In an earlier publication (Wollberg, Cohen & Kalina, 1976) we demonstrated that in this species, a potential difference exists across the ‘follicle’ wall (defined hereafter as ‘oocyte potential’), ranging between 30 and 55 mV (inside oocyte negative in respect to external grounded medium), with the more mature oocytes possessing larger potential differences than the less-mature oocytes. We have also shown that all the follicles along a single ovariole were electrotonically and histologically coupled by oocyte follicle cell gap junctions. The ionic basis of oocyte and egg potentials have been investigated in several animal species, invertebrates and vertebrates (e.g. Powers & Tupper, 1975; Miyazaki & Hagiwara, 1976; Shen & Steinhardt, 1976; Ziegler & Morrill, 1977). In most of these cases, oocyte membrane potentials were determined, primarily, by the passive distribution of potassium ions and to a lesser extent by sodium ions. For some species the involvement of an undefined metabolic electrogenic pump, in maintaining the steady-state oocyte potential, was proposed (Powers & Tupper, 1975; Miyazaki & Hagiwara, 1976; Ziegler & Morrill, 1977). In the present report we show that the steady-state oocyte potential of Locusta migratoria is mainly determined by the passive distribution of potassium ions and by an ouabain-sensitive electrogenic Na/K pump.
The Hydrodynamic Drag of Swimming Bluefish (Pomatomus Saltatrix) in Different Intensities of Turbulence: Variation With Changes of Buoyancy
Authors: Ogilvy Christopher S. , Dubois Arthur B. 
Published: April 2021

ABSTRACT
Thrust and drag were calculated for ten bluefish using Newton’s law, F = ma, the measured acceleration of the fish, and one essential assumption, without which only the sum of thrust and drag could be determined. Any time the thrust is zero, the drag equals the mass of the fish times its negative acceleration. For reasons given in the full text, the thrust is believed to drop to zero twice per swimming cycle, and never become negative. Zero thrust thus occurs at the negative acceleration peaks. For acceleration waveforms that are symmetric, zero acceleration lies at a level half way between the levels of the positive and negative peaks, so the peak negative acceleration is half the peak-to-peak height of the waveform. It is further assumed that the instantaneous drag thus measured at the negative acceleration peaks equals the mean drag averaged over the whole swimming cycle, which in turn equals the mean thrust. Turbulence, induced in the water tunnel by two flat metal plates placed in the stream in front of the fish, or by rotation of a mixing rod, did not change the drag, or the fish’s ability to produce thrust, as indicated by the maximal swimming speed. The attachment of two pressure transducer enclosures to the tail did not alter the maximal swimming speed. Changes of buoyancy were produced by inflation or deflation of balloons sewn into the swim bladders of three fish. The thrust calculated from fluctuations in the forward acceleration of the fish measured at zero speed during neutral buoyancy was 0·0 to 0· 14 N. If the non-zero values are genuine, they must be balanced by rearward forces from the pectoral fins. The thrust increased linearly with speed at the rates of 0· 40, 0· 64, and 0· 71 N per m.s•1, respectively, at speeds between 0 and 0· 8 m.s−1. The mean tail thrust of a negatively buoyant fish at zero water speed equalled or exceeded the body’s weight in water. Its forward component must be balanced by a rearward component of the lift force from the flapping pectoral fins. Upward components of the two forces support the weight of the fish. With 45 ml air removed from the swim bladder of a bluefish, the tail thrust diminished from 0·64 N at zero water speed to a value of 0·46 N as the water speed was increased to between 0· 2 and 0· 4 m.s−1, and then increased to 0· 71 N at a water speed of 1 m.s−1.
Contribution of Compound Eyes and Ocelli to Steering of Locusts in Flight
Authors: Taylor Charles P. 
Published: April 2021

ABSTRACT
Locusts (Orthoptera, Acrididae) were tethered inside a simulated horizon visual display. Rotation of the horizon elicited following motions of the animal’s head and rudderlike movements during flight. Head and steering motions were still elicited after either the compound eyes or the ocelli were surgically ablated. Head motions after ocellar cautery suggested that the ocelli may function synergistically with the compound eyes to (a) minimize the delay of visual responses and (b) augment visual responses when no sharp horizontal border is present. Flight steering motions were found not to depend on proprioception of head position. Three other species (Diptera and Odonata) also followed horizon rotations with head motion after their compound eyes had been ablated.
Differentiation of the Chloride Extrusion Mechanism During Seawater Adaptation of A Teleost Fish, the Cichlid Sarotherodon Mossambicus
Authors: Foskett J. Kevin , Logsdon Craig D. , Turner Timothy , Machen Terry E. , Bern Howard A. 
Published: April 2021

ABSTRACT
Opercular membranes isolated from the freshwater-adapted euryhaline teleost, Sarotherodon mossambicus, and mounted in Ussing-style chambers, have low conductance and current and do not actively transport chloride. In contrast, membranes isolated from seawater-adapted S. mossambicus have high conductance and generate large currents representing net chloride extrusion. Full development of this chloride secretion process requires 1–2 weeks, the time-course of which provides the first unambiguous measurement of changes in net extrarenal salt secretion associated with a teleost’s adaptation to seawater. Tissues from seawater-adapted fish contain typical chloride cells, when observed with the electron microscope, which appear as large cells with fluorescence microscopy after staining with dimethylamino-styrylaethylpyridiniumiodine. These cells are absent from the freshwater tissue, although rudimentary chloride cells are present, appearing as small cells with fluorescence microscopy. Following seawater transfer, the number of chloride cells increases only during the first 3 days. Subsequent chloride cell hypertrophy is highly correlated with the quantity of chloride extrusion. These data strongly implicate the chloride cell as the salt-secretory cell-type. When cortisol was injected into freshwater fish, chloride cell density increased but chloride secretion was not activated. It appears that development of salt extrusion involves increased numbers (controlled, at least in part, by cortisol) and differentiation of chloride cells, including activation of membrane active-transport sites. The opercular membrane from S. mossambicus provides a valuable model for studying these physiological and morphological events.
Fluid Balance in the Argasid Tick, Ornithodorus Moubata, Fed On Modified Blood Meals
Authors: Kaufman Susan E. , Kaufman William R. , Phillips John E. 
Published: April 2021

ABSTRACT
The argasid tick Ornithodorus moubata Murray was fed on modified blood meals, the ionic strength and/or osmotic pressure of which was varied by additions of NaCl or glucose, and by dilution with distilled water or isosmotic glucose. The following parameters were monitored: total volume increase of tick, total volume of meal ingested, net increase in haemolymph volume, volume of coxal fluid excreted and ion concentrations and osmotic pressures of the gut contents, haemolymph and coxal fluid, as well as potential differences across the gut lumen. Absorption of fluid from the gut into the haemolymph appeared to be linked to the active transport of Na+ and Cl−, although the rate of absorption was an inverse function of the prevailing osmotic gradient across the gut epithelium. The tick can maintain a reasonably constant [Na+] and [Cl−] in the haemolymph when fed meals in which the concentration of these ions varies up to 6-fold, but only if the meal remains isosmotic with blood. The rate and volume of coxal fluid production are direct functions of the rate and volume of fluid absorption by the gut epithelium. Thus, during the feeding cycle, the coxal organ appears to function chiefly in an osmo- and volume-regulatory capacity in this species of argasid tick.
Localization and Characterization of Water Uptake from the Midgut of the Locust, Schistocerca Gregaria
Authors: Dow Julian A. T. 
Published: April 2021

ABSTRACT
Water, potassium and sodium fluxes were measured across various regions of the locust gut under in vitro internal perfusion. The anterior caeca differed from the other gut regions, notably the posterior caeca, in being able to absorb water in the absence of an applied chemical or osmotic gradient. Absorption of sodium from the caecal lumen was active, and inhibited by 2,4-DNP or ouabain. Potassium was passively distributed across the caecal epithelium, and transmembrane fluxes were unaffected by toxins. A model for caecal water uptake was advanced, in which passive fluxes of potassium and chloride from the KCl-rich luminal fluid, combined with active sodium uptake, drives water into the blood, thus concentrating solutes within the caecal lumen.
Respiration in Exercising Fowl
Authors: Brackenbury J. H. , Gleeson M. , Avery P. 
Published: April 2021

ABSTRACT
Respiratory water loss and rectal temperature were measured in domestic fowl running for 10 min on a treadmill at speeds of 1·24−4·3 hm h-1 in air temperatures of 20 ± 2 °C or 32 ± 2 °C. At given speeds the water loss at 32 ± 2 °C was approximately twice that at 20 ±2 °C and the end-exercise rectal temperature was 0·5−0·8 °C higher. At 20 ± 2 °C, respiratory evaporation accounted for 10−12 % of the total metabolic energy used at all speeds. At 32 + 2 °C, the fractional respiratory heat loss fell from 26−5 % at 1·24 km h-1 to 17 % at 3·6 km h-1. The fraction of the total metabolic energy stored as body heat rose progressively with air temperature.
Turnover of Monovalent Cations in Paramecium
Authors: Hansma Helen G. 
Published: April 2021

ABSTRACT
Regulation of sodium and potassium by Paramecium was studied by measuring fluxes of 22Na and 86Rb respectively. Fluxes of these tracers had the following similarities. (1) Steady-state turnover showed approximately single-pool kinetics with 50% turnover in h. (2) Efflux of both cations showed a specific exchange diffusion when the medium contained the corresponding non-radioactive cation. (3) The net efflux of both cations was slow in the absence of exchange diffusion.
Fluxes showed the following differences. (1) The cells had 2 to 4 times as much K+Rb as Na. Therefore, (2) the K+Rb fluxes at steady state were 2–4 times larger than the Na fluxes, since the fractional turnover was the same for both cations. (3) Membrane excitation by Ba2+ stimulated the efflux of Rb but not Na. The efflux of 86Rb during membrane excitation appeared to represent the outward or delayed rectification that repolarizes the membranes after an action potential, since it was absent in a pawn mutant that is lacking in membrane excitation.
The Bidder Lecture, 1980: The Evolution of Fibrillar Muscle in Insects
Authors: Pringle J. W. S. 
Published: April 2021

ABSTRACT
Fibrillar muscle is a peculiar type of striated muscle found only in the power producing flight muscles of certain higher Orders of insects and in the main timbal* muscle of the sound-production system of certain cicadas. It is recognizable both physiologically and histologically and is distinguishable from the tubular and ‘close-packed’ striated muscles found in nearly all other orders of insects in the flight system (Pringle, 1975). There are good reasons for thinking that tubular and close-packed muscles are the more primitive evolutionarily and that fibrillar muscle has arisen independently many times in the evolution of insects. Since it is inconceivable that, at any stage in these evolutionary developments, there was a loss of the capacity for flight or of sound-production, the problem arises of determining how the change could have come about. This is the subject of this lecture.
Homologies Between Neuromuscular Systems Serving Different Functions in Two Decapods of Different Families
Authors: Paul Dorothy Hayman 
Published: April 2021

ABSTRACT
Evidence is provided for homologies between specific parts of the tailfan neuromusculatures in two sand crabs, Emerita analoga (family Hippidae) and Blepharipoda occidentals (family Albuneidae). The gross anatomy of the tailfan, particularly of the telson, is very different in the two species, the biggest difference being the absence in Blepharipoda of a power-stroke muscle which in Emerita constitutes 50% by wet weight of the telson musculature. Homologies between motoneurones innervating telson muscles in the two crabs are established based on comparisons of their positions and central morphology. The derivation of the sand crab telson muscles and their innervation from neuromusculature in an ancestral macruran is proposed.
Ventilation and Oxygen Extraction in the Bat Pteropus Gouldii During Rest and Steady Flight
Authors: Thomas Steven P. 
Published: April 2021

ABSTRACT
Tidal volume (VT) breathing frequency (f) and oxygen consumption were simultaneously measured in the bat Pteropus gouldii during quiet rest at 24 °C, and oxygen extraction (E) values were calculated from these data. VT and f were also measured at 24 °C from P. gouldii undertaking steady wind-tunnel flight at different speeds and angles, and this information together with appropriate data reported previously for this bat were used to calculate flight E values.
The oxygen extraction of resting P. gouldii was similar to that of a resting non-flying mammal of comparable size but lower than that of a resting bird. P. gouldii increases VT and/almost equally in going from quiet rest to level flight to achieve a 17-fold increase in minute ventilation. Compared to the resting bat, flying P. gouldii hyperventilates its respiratory system relative to its metabolic requirements. The level flight VT of P. gouldii compares favourably with that expected for a flying bird of the same body mass, and represents almost 90 % of the total lung capacity predicted for a non-flying mammal of comparable size. Because of the increased breathing frequency during flight, the minute ventilation requirement of P. gouldii during level flight exceeds that predicted for a similar-sized flying bird. E values calculated for flying P. gouldii are significantly lower than those reported for birds flying at comparable temperatures and flight conditions.