bluuebunny/crossref_metadata_2025_split huggingface dataset:
Volumes of the Respiratory and Circulatory Systems in Tufted and Mallard Ducks
Authors: Keijer E. , Butler P. J. 
Published: April 2021

ABSTRACT
Tufted ducks habitually dive for their food and may remain submerged for up to 40 s. Mallards, on the other hand, merely upend themselves for_ a few seconds when dabbling. It was decided, therefore, to determine the size of the oxygen storage compartments in these two aquatic birds. Haemoglobin concentration, blood volume, and volume of the respiratory system are all significantly larger in the tufted duck than in the mallard. Myoglobin concentration in the pectoral and leg muscles of the tufted duck is similar to that in the locomotory muscles of terrestrial birds and mammals. Amounts of usable oxygen (at STPD) stored in the body were calculated to be 41·5 ml kg−1 for tufted ducks and 29·0 ml kg−1 for mallards.
Stimulation of Oxygen Consumption With Fluid Absorption in Insect Recta
Authors: Houlihan D. F. , Sell D. 
Published: April 2021

ABSTRACT
The oxygen consumption of excised abdomens of cockroaches and locusts has been measured before and after the injection of fluids into the ligated recta. Fluid injection caused a transient stimulation of oxygen consumption of up to 30% of the resting rate. The extra amount of oxygen consumed is positively correlated with the osmolality of the fluid injected and the amount of fluid absorbed. Parallel experiments were carried out on the time course of fluid uptake ; these experiments revealed a correlation first between a rapid increase in fluid absorption and stimulation of oxygen consumption, and secondly between the final resting rate of oxygen consumption and a slower absorption of fluid. Locusts take up fluid at double the rate of cockroaches and have double the stimulation in oxygen consumption following fluid injection. In locusts the increases in oxygen consumption can also be correlated with the net movement of Na+, K+ and Cl− from the rectum. The stimulation of oxygen consumption during fluid uptake is discussed in relation to the local osmosis model for fluid uptake.
The Morphology and Passive Electrical Properties of Claw Closer Neurones in Snapping Shrimp
Authors: Wilson John A. , Mellon Deforest 
Published: April 2021

ABSTRACT
The morphology and passive electrical properties of the dimorphic pincer and snapper claw closer neurones were examined in the snapping shrimp, Alpheus heterochelis. No differences were found between homologous pincer and snapper neurones for input resistance and length constant in the proximal portion of the axons, or for the proximal axonal and dendritic anatomies using intracellular cobalt staining. To determine the effect of cell body size upon the passive electrical properties of the neurones, we modelled the neurones by computer. The difference in cell body size causes less than a 3 % change in the electrical properties of the neurone at the axon root. Thus, despite the striking behavioural dissimilarities between the pincer and snapper claws, there is no electrical or morphological basis in the claw closer neurones for this difference.
Acoustic Transmission Through the Head of the Common Mole, Talpa Europaea
Authors: Coles R. B. , Gower D. M. , Boyd P. J. , Lewis D. B. 
Published: April 2021

ABSTRACT
Cues for directional hearing in mammals are traditionally based on inter-aural intensity differences (IIDs) established as a result of the diffraction of a progressive sound wave by the head and pinna, or on inter-aural time differences (ITDs) established because of the separation of the two ears in space. This ‘dual hypothesis’ has been extended to other animal groups despite the fact that the majority of submammalian animals have head dimensions that are small relative to the wavelengths of the sounds used in communication. Under these conditions, little if any diffraction can occur and time differences become very small. As an alternative to the pressurereceiver principle of the mammalian ear, crickets (Michelsen, 1979) and the quail (Coles et al. 1980) use the pressure-difference principle for directional hearing. In a pressure-difference receiver, sound has access to both surfaces of the tympanic membrane (TM) because of an air-filled cavity between the ears which allows sound transmission through the head or body. When the sound pressure level (SPL) acting on the inner surface of the TM is equivalent to that acting on the external surface, the response of the TM (and, therefore, the cochlea) will be determined by the phase difference between the external and internal components. At any one frequency this phase difference will, in turn, vary with the angle of incidence of the sound.
A Comparison of CO2 Excretion in A Spontaneously Ventilating Blood-Perfused Trout Preparation and Saline-Perfused Gill Preparations: Contribution of the Branchial Epithelium and Red Blood Cell
Authors: Perry Steve F. , Davie Peter S. , Daxboeck Charles , Randall David J. 
Published: April 2021

ABSTRACT
A spontaneously ventilating blood-perfused trout preparation and saline perfused gill preparations were utilized to investigate the role of the erythrocyte and branchial epithelium in CO2 excretion and acid-base regulation. CO2 excretion blood-perfused preparations was positively correlated with haematocrit (Het), and was abolished completely during plasma-perfusion. Elevating HCO3− concentration of input blood from 10 to 25 mm significantly increased , fourfold in blood-perfused preparations as a result of increased entry of HCO3− into the red blood cell and not into the gill epithelium. Increased HCO3− concentration was without effect in totally saline-perfused coho salmon (Onchorynchus kisutch). The addition of 4-acetamido-4′-iro-thiocyanatostilbene-2,2′ disulfonic acid (SITS; 10−4 M) to input blood significantly reduced and oxygen uptake in blood-perfused fish due to inhibition of erythrocytic HCO3Ȓ/Cl −exchange. Unlike blood-perfused preparations, no saline-perfused preparation (isolated holobranchs or totally perfused rainbow trout or coho salmon) displayed measureable CO2 excretion at physiological and pH. Increased input in both blood-perfused and saline-perfused preparations significantly increased due to enhanced branchial diffusion of molecular CO2. It is concluded that the entry of HCO3− into the erythrocyte is the rate-limiting step in CO2 excretion and that movement of HCO3− from plasma to gill epithelium cells in no way contributes to overall CO2 elimination.
Physiological Response to Acid Water in Brown Trout (Salmo Trutta L.): Cell Volume Regulation in Heart Ventricle Tissue*
Authors: Fugelli Kjell , Vislie Tone 
Published: April 2021

ABSTRACT
In brown trout surviving in acidified brook water, the plasma osmolality is reduced 15–25%. The decrease is much less than that expected from the measured reduction in the plasma concentration of Na+ and Cl−. This discrepancy cannot quantitatively be explained by the increase in plasma concentration of K+ (100%) and free amino compounds (mainly taurine; 280%) but appears mainly attributable to a reduction in plasma volume.
The osmolality of heart ventricle cells is also reduced. Water content of the cells is unchanged, and there is a significant decrease in the intracellular concentration of K+, taurine and to a lesser extent glutamic acid, accounting for 25, 45 and 8%, respectively, of the osmolality reduction. These findings indicate the existence of a cell volume regulation mechanism in the fresh water brown trout which counteracts osmotic swelling of tissue cells during periods of salt loss in acidified water. The significance of this mechanism for survival under such conditions is discussed.
Speed, Acceleration and Manoeuvrability of Two Teleost Fishes
Authors: Webb P. W. 
Published: April 2021

ABSTRACT
Speed, acceleration rate and turning radius were measured for rainbow trout (Salmo gairdneri length 25·7 cm) and smallmouth bass (Micropterus dolomieu; ength 23· 6 cm) attacking live minnows. The observations sampled a range of values for each kinematic variable up to the limits of maximum performance. Minimum turning radius was independent of speed and acceleration rate. Expressed as a ratio of total length, L, minimum radii were 0·18 ± 0·2L for trout and 0·11 ± 0·02L for bass . Differences in minimum turning radius, R, between trout and bass were attributed to differences in the volume of the body and entrained water, V, and projected lateral surface area of the body and median fins, A. For subcarangiform swimmers, the dimensionless minimum specific turning radius R/L = 2V/AL. Since V is numerically equal to the mass of the body, M, and added water mass (approximately 0·2M) for neutrally buoyant fish, R/L can be calculated from two easily measured morphological parameters, M and A.
The Interaction of Environmental Calcium and Low pH on the Physiology of the Rainbow Trout, Salmo Gairdneri
Authors: McDonald D. G. 
Published: April 2021

ABSTRACT
Exposure of adult rainbow trout to low pH (pH 4·3) in soft water (Ca2+ = 223 μequiv/1) caused a substantial ionic disturbance which arose primarily because of large net losses at the gills. In contrast, renal ion losses were low initially and declined even further because of a pronounced reduction in urine flow. A net influx of H+ occurred across the gills but this was not sufficient to cause a blood acid-base disturbance or a renal response. Although branchial ion and H+ fluxes declined with time, blood ion levels did not return to normal and many of the fish died. Further reduction in water calcium (Ca2+ = 69 μequiv/1) provoked a higher mortality and a more substantial ionic imbalance. These results contrast sharply with the effects on trout of acid exposure in hard water (Ca2+ ⩾ 1600μequiv/l), where net ion losses and mortality are reduced and H+ uptake increased. A preliminary model for the interaction of low pH and calcium is proposed and evidence for adaptation to acid stress and for the origin of acid lethality is discussed.
Influence of Circadian Rhythms on Rat Muscle Glycogen Metabolism During and After Exercise
Authors: Garetto L. P. , Armstrong R. B. 
Published: April 2021

ABSTRACT
Marked circadian fluctuations in skeletal muscle glycogen concentrations have previously been reported. The purpose of the present study was to estimate the influence of these rhythms on muscle glycogen metabolism during and after high-intensity treadmill exercise. Male Sprague-Dawley rats ran five 1-min sprints at 75 m min− 1 interspersed by 1–3 min rest intervals either at 08.00 h (morning) or at 20.00 h (night). All muscles sampled lost significant amounts of glycogen during exercise at both time periods. There were no differences in rates of loss between morning and night, even though glycogen levels in several muscles (high-oxidative muscles) were significantly higher before exercise in the morning. Following exercise, glycogen restoration in muscle samples primarily composed of fast-twitch fibres was more rapid in the morning than at night. There was no difference in glycogen restoration rates between the two time periods in the muscle primarily composed of slow-twitch fibres. Although liver glycogen was lower after exercise at night than in the morning, there were no differences in post-exercise blood glucose levels between the two time periods. In conclusion, circadian rhythms do not appear to influence rates of glycogen loss during high-speed running. However, since glycogen loss is the same at all times of day, one would predict that circadian changes in pre-exercise muscle glycogen concentrations would affect muscular endurance. Muscle glycogen restoration after exercise does appear to be affected by circadian rhythms, although interpretation of these data is complicated by possible changes in patterns of muscle fibre contraction at different times of the day. These circadian influences should be considered in the design of exercise studies using laboratory rodents.
The Organization of Flight Motoneurones in the Moth, Manduca Sexta
Authors: Rind F. Claire 
Published: April 2021

ABSTRACT
The morphology and the innervation of the main wing depressor muscles have been studied. The motoneurones to these muscles have dendrites ipsilateral to the muscle they innervate and located in the dorsal neuropile. With the exception of one motoneurone, to the dorsal longitudinal muscle, all motoneurone cell bodies are ipsilateral to the muscle they innervate. The morphologies of individual cobalt stained motoneurones are described. Flight motoneurones to wing depressor muscles are not electrically or chemically coupled to one another.
The Generation of Rhythmic Activity in A Distributed Motor System
Authors: Cohan Christopher S. , Mpitsos George J. 
Published: April 2021

ABSTRACT
Rhythmic activity that is distributed to the brain and buccal ganglia and which underlies several types of behaviour, can be evoked from isolated nervous systems of Pleurobranchaea californica by tonic nerve stimulation. The experiments presented here were designed to test whether this rhythmic activity is produced by independent neuronal oscillators located in each ganglion or whether the rhythmic activity arises from a single oscillatory locus in the buccal ganglion and is transmitted passively to the brain. By interrupting the conduction of activity in the cerebrobuccal connectives (CBC) between brain and buccal ganglia we show that motor output from the brain depends on sustained, cycle to cycle input from the buccal ganglion and cannot be reset with respect to the buccal activity. The production of rhythmic activity in the brain depends on the generation of rhythmic activity in the buccal ganglia whether the rhythms are activated by stimulation of buccal roots or paracerebral command cells in the brain. Simultaneous intracellular recordings from brain motoneurones and buccal interneurones which project to the brain indicate that these interneurones provide both the drive and the pattern for rhythmic motor output in the brain. Tonic stimulation of the CBC can produce rhythmic activity in isolated brains in which all nerve roots and connectives have been cut. This can be explained by the fact that tonic stimulation of the connectives is transformed into phasic activity by the axons within the connective. We conclude therefore, that rhythmic, coordinated activity in the brain and buccal ganglia of Pleurobranchaea arises from oscillatory circuits that are located only in the buccal ganglia.
Electrophysiology of Mosquito Anal Papillae
Authors: Edwards H. A. 
Published: April 2021

ABSTRACT
The anal papillae of mosquito larvae are classic transporting epithelia that can absorb inorganic ions from extremely dilute external media. Since the original investigations of Wigglesworth (1933a,b,c) and Koch (1938) studies have been made of the ultrastructure of the papillae (Copeland, 1964; Sohal & Copeland, 1965; Meredith & Phillips, 1973a,b), of radio-cation fluxes (Treherne, 1954; Stobbart, 1959, 1960, 1965, 1967, 1971), of their water permeability (Nicolson & Leader, 1974) and their role in osmoregulation (Edwards, 1979). Quantitative understanding of epithelial salt transporting mechanisms, however, requires knowledge of the appropriate electrochemical gradients. Only one attempt has so far been made to provide this information for mosquito larvae (Stobbart, 1974). These measurements were made by recording the potentials between the larval haemolymph and a drop of fluid surrounding the papillae. However, the potentials measured in this way were found to be very unstable and of variable polarity. This communication describes an attempt to measure the electrical properties of the papilla epithelium using isolated anal papillae of Aedes aegypti.
Reversible Changes in the Intracellular Potassium Ion Activities and Membrane Potentials of Aplysia L2–L6 Neurones in Response to Normoxia and Hypoxia
Authors: Coyer Philip E. , Halsey James H. , Strong Edward R. 
Published: April 2021

ABSTRACT
Exposure of 7 L2–L6 neurones to hypoxia for 65 min resulted in hyperpolarization of the membrane potential (EM) from a mean of –49 ·1 ±2 ·1 to –54 ·l ±3 ·6mV (S.E.). Intracellular potassium ion activities increased significantly from 137 ·7 ±4 ·0 to 155 ·6 ±3 ·4 mM –K+. This is equivalent to a change in EK from –74 ·2 mV commensurate with the observed hyperpolarization of 5 mV. The reversibility of these responses was noted by reoxygenating the solution surrounding the ganglion for a period of 55 min. In another group (n = 7) of L2–L6 neurones, the responses in , EM, and EK were slower, although following hypoxia for 90 –110 min, similar changes in the levels of these membrane phenomena were recorded. PNa/PK ratios were computed for both L2–L6 groups of neurones using a modified version of the Goldman equation. There were only slight decreases in this ratio with hypoxia, which were not significantly different from the control (normoxia). Therefore, we conclude that this period of hypoxia is capable of stimulating the sodium pump of these cells since the membrane potentials seem to hyperpolarize according to the increase in . However, tonic release of neurotransmitter, which could hyperpolarize these neurones and attract intracellular potassium, cannot be ruled out as an effect of hypoxia.
Transport of Uric Acid by the Malpighian Tubules of Rhodnius Prolixus and Other Insects
Authors: O’Donnell M. J. , Maddrell S. H. P. , Gardiner B. O. C. 
Published: April 2021

ABSTRACT
Urate is transported against an electrochemical gradient into the lumen of the lower Malpighian tubule of Rhodnius. In vivo, higher urate transport rates are induced by the increase in haemolymph urate concentration that follows feeding. The induced rate of transport is sufficient to account for the amount of urate eliminated. In vitro experiments with the tsetse fly Glossina suggest a possible induction of transport as a direct response of the tubule cells to an increase in urate concentration in the surrounding fluid.
Urate transport has been shown for Malpighian tubules of insects from several different orders, suggesting that the mechanism is widespread. Insect urate transport differs from that of vertebrates; it is ouabain-insensitive and results in the precipitation of free uric acid instead of urate salts.
Energetic Cost of Active Branchial Ventilation in the Sharksucker, Echeneis Naucrates
Authors: Steffensen John Fleng , Lomholt Jens Peter 
Published: April 2021

ABSTRACT
Sharksuckers use active branchial ventilation when swimming or at rest in stationary water. When attached to a moving object or when placed in a water current, they shift to ram gill ventilation as water velocity exceeds a certain threshold. Water velocities required for the transition from active to ram gill ventilation were from 10–50 cm s −1, depending on the size of the fish. Oxygen consumption increased between 3·7 and 5·7 % when the fish shifted from ram gill ventilation to active branchial pumping. When water velocity was increased beyond the threshold for ram gill ventilation, no further increase in oxygen consumption was observed. It is concluded that the energetic cost of active ventilation in shark suckers is lower than has previously been reported for fish in general.
Haemodynamic Effects of Secretory Agents On the Isolated Elasmobranch Rectal Gland
Authors: Shuttleworth T. J. 
Published: April 2021

ABSTRACT
Perfusion flow rate in the isolated elasmobranch rectal gland, perfused at in vivo pressures, was measured in Scyliorhinus canicula L. and Squalus acanthias L. Flow through the secretory parenchyma of the gland was reduced in the presence of concentrations of catecholamines in the physiological range, an effect mediated via α-adrenergic receptors within the gland vasculature. Flow through the non-secretory vascular shunts of the rectal gland was unaffected. The vasoconstriction induced by noradrenaline was blocked by the addition of cyclic AMP + theophylline or adenosine at concentrations known to stimulate secretion by the gland. In Squalus, a similar effect was seen with the secretagogue vasoactive intestinal peptide, but this agent had no effect in the glands of Scyliorhinus. Experiments indicate that the blockage of the noradrenaline effect by the secretory agents does not involve any stimulation of vasodilatory β-adrenergic receptors and, furthermore, that the vasomotor effects of these agents appear to be entirely independent of their actions on the secretory cells. Evidence is presented indicating that the vasomotor action of adenosine may be mediated via receptors specific for the ribose moiety of the nucleoside (R2 receptors) activating adenylate cyclase, and that this may, in turn, explain the observed effects of the addition of exogenous cyclic AMP. The significance of the observed vascular effects in the overall control of secretion rate by the gland in vivo is discussed.
Aerial Gas Exchange In Australian Freshwater/Land Crabs of the Genus Holthuisana
Authors: Greenaway Peter , Taylor H.H. , Bonaventura J. 
Published: April 2021

ABSTRACT
Holthuisana valentula Riek and H. agassizi (Rathbun) both ventilate their lungs by lateral oscillations of the thoracic walls within the branchial chambers. Air enters and leaves the lungs via the prebranchial apertures and the Milne-Edwards apertures. At rest, active ventilation in H. transversa was low (0·95 mlg−1 h−1) and a high diffusional component was evident. After disturbance, rose to 45·4mlg−1h−1 and % extraction was low (1·1%). Yentilation increased during moderate hypercapnia and marked hypoxia. was high after disturbance (2·95 μmolg−1 h−1) but declined to very low levels at rest (0·45 μmolg−1 h−1). The haemocyanin had a relatively low affinity for oxygen during air-breathing (P50 = 13 Torr) but it was saturated with oxygen at normal (56·1 Torr). CCO2 in the haemolymph (13 mmol l−1) was characteristic of air-breathing crabs. The respiratory performances of H. transversa in air and water are compared.
Reversal of an Intersegmental Reflex Elicited by A Muscle Receptor Organ
Authors: Dicaprio R. A. , Clarac F. 
Published: April 2021

ABSTRACT
One of the most common reflexes observed in invertebrates is the resistance reflex, in which a proprioceptor at a given joint excites the motor neurones innervating the muscles controlling the joint so as to resist imposed movement (Bush, 1962, 1963, 1965; Barnes, Spirito & Evoy, 1972). As well as these intrasegmental reflexes, proprioceptive reflexes in which sensory information is used to control muscles at joints other than the one spanned by a given proprioceptor have been reported (Ayers & Davis, 1977; Clarac, Vedel & Bush, 1978). These intersegmental reflexes may also control the state of excitation of other receptors (Moody, 1970; Clarac et al. 1978). Resistance reflexes and intersegmental reflexes are presumed to have a role in postural maintenance and load compensation (op. cit.; for review see Mill, 1976). However, resistance reflexes can be suppressed during locomotion (Barnes et al. 1972) and intersegmental reflexes may be modified during walking (Ayers & Davis, 1977). In addition, we have recently shown that a resistance reflex elicited by the thoracic-coxal muscle receptor organ (TCMRO) in the crab can be reversed to become a positive feedback assistance reflex (DiCaprio & Clarac, 1981). In this report we demonstrate that an intersegmental reflex activation of the basipodite levator and depressor motor neurones mediated by the TCMRO can also be reversed with respect to movement of the thoracic-coxal (TC) joint.