bluuebunny/crossref_metadata_2025_split huggingface dataset:
The cardioregulatory system of crayfish: neuroanatomy and physiology
Authors: Field L. H. , Larimer J. L. 
Published: April 2021

ABSTRACT
The anatomical arrangement of the cardioregulatory nerves and their physiological activity during cardiac modulation were analysed in Procambarus clarkii. The bilaterally arranged pairs of cardioinhibitors and cardioaccelerator axons, in nerves SN II and SN III respectively, were physiologically identified by correlating spikes in SN II and SN III with the same spikes in the dorsal nerve, which innervates the heart. The cardioinhibitor neurone fired tonically in varied sporadic bursts. During periods of cardiac inhibition, however, this neurone discharged in a long chain of spikes at a characteristic frequency of 40–50 Hz. The cardioaccelerator neurone fired tonically at 2–3 Hz but on occasion its activity reached 12 Hz. Three inhibitory cardiac reflexes were analysed. The sensory modalities for the reflexes included (a) stretch of the dorsal pericardial wall, (b) chemical stimulation of coxal hair sensilla with glucose and (c) tactile stimulation of hair sensilla in and below the gill chamber, on the antennae, the antennules and on the anterior cephalothorax. The discharge of both cardioinhibitor neurones showed a weak temporal correlation suggesting a common presynaptic drive, while the pair of cardio-accelerators appeared to have a reciprocal relationship With the cardio-inhibitors.
Optic gland implants and their effects on the gonads of Octopus
Authors: Wells M. J. , Wells J. 
Published: April 2021

ABSTRACT
Optic glands transplanted from one Octopus vulgaris into another cause enlargement of the gonads and ducts of the recipient. Enlargement occurs whether or not the gland was secreting when implanted and regardless of the sex of the donor or recipient. Glands derived from Eledone moschata or Octopus macropus implanted into O. vulgaris are as effective as glands derived from O. vulgaris. Implants derived from Sepia officinalis or LoHgo vulgaris appear to be ineffective.
Anaerobiosis: A Possible Source of Osmotic Solute for High-salinity Acclimation in Marine Molluscs*
Authors: Baginski Richard M. , Pierce Sidney K. 
Published: April 2021

ABSTRACT
When stressed with high-salinity exposure, cell volume is restored in ventricles of Modiolus demissus demissus by a rapid accumulation of intracellular free amino acids. Although the total amino acid pool increases and remains at a constant high level thereafter, the pattern and time course of accumulation is different for each major amino acid (glycine, alanine, taurine, and proline). Initially, cell volume is restored by a rapid accumulation of alanine, but later its concentration decreases while glycine and taurine accumulate. Although at first not detected, the proline concentration increases, peaks and subsequently disappears again. Isolated ventricles recover normal activity after large environmental salinity increases. During recovery the intracellular free amino acid changes in isolated ventricles are similar to the initial pattern of accumulation in whole animals, i.e., alanine, and to a lesser extent, proline and glycine accumulate. Finally, isolated ventricles undergo a period of decreased oxygen consumption on exposure to an increased salinity. These results suggest that the initial stages of high-salinity acclimation in molluscs depends upon the synthesis of amino acids via a known anaerobic biochemical pathway.
Habituation and inhibition of the crayfish lateral giant fibre escape response
Authors: Wine J. J. , Krasne F. B. , Chen L. 
Published: April 2021

ABSTRACT
Decrement of the lateral giant fibre escape response was studied in intact, restrained, crayfish and in those with the ventral nerve cord transected at the thoracic-abdominal level. Taps (delivered at rates of 1 per 5 min to the abdomen) depressed responsiveness to about 50% of its initial value in 10 trials, for both intact and operated animals. With additional stimulation, responsiveness dropped to near zero for both groups. Recovery was negligible 2 h later, but nearly complete after an additional 24 h rest. Protection against response decrement in this situation was obtained by directly activating the cord giant fibres 30 msec prior to the tactile stimulus. The directly-elicited giant fibre spikes which follow the tactile stimulus do not influence the course of response decrement. The results establish the decrement as centrally mediated habituation, and minimize the role of receptor alterations or descending neuronal influences in the behavioural change. A comparison is made between the properties of habituation and the homosynaptic depression of afferent to interneurone synapses that is presumed to be the physiological mechanism of habituation in this situation.
Patterns of activity in the antennular motoneurones of the hermit crab Pagurus alaskensis (Benedict)
Authors: Snow P. J. 
Published: April 2021

ABSTRACT
Using electromyogram recordings from the antennular muscles of intact animals and recordings from the antennular nerves of partially dissected preparations, the patterns of activity in specific antennular moto- neurones have been described during antennular flicking and antennular withdrawal. The slow extensor motoneurone A30S is active during flicking in addition to the phasic component of the antennular motor system (A30F, A31F and A32F). The flexion phase of a flick is the result of a burst of variable duration and number of spikes within flexor motoneurones A31F and A32F. The extension phase of a flick is the result of a burst of variable duration and number of spikes in extensor motoneurones A30F and A30S. Extension-withdrawal and slow flexion-withdrawal reflexes, tonic flexion withdrawal and maintained flexion at the MS-DS joint usually result from activity in part of the tonic component of the antennular motor system: moto-neurones A30S, A31S and A32S. Fast flexion-withdrawal reflexes result from a burst of spikes in motoneurone A31F-S which constitutes the phaso-tonic component of the antennular motor system. During high-frequency activity (15–60/sec), reciprocity exists between the slow flexor motoneurones A31S an A32S and slow extensor motoneurone A30S.
The effect of progressive hypoxia on respiration in the dogfish (scyliorhinus canicula) at different seasonal temperatures
Authors: Butler P. J. , Taylor E. W. 
Published: April 2021

ABSTRACT
Dogfish were acclimated to 7, 12 or 17°C and exposed to progressive hypoxia at the temperature to which they had been acclimated. During normoxia, the Q10 values for oxygen uptake, heart rate, cardiac output and respiratory frequency over the full 10°C range were: 2·1, 2·1, 2·1 and 2·5 respectively. Increased acclimation temperature had no effect on cardiac stroke volume or systemic vascular resistance, although there was a decrease in branchial vascular resistance, pHa and . Progressive hypoxia had no effect on heart rate or oxygen uptake at 7°C, whereas at 12°C and 17°C there was bradycardia, and a reduction in O2 uptake, with the critical oxygen tension for both variables being higher at the higher temperature. Cardiac stroke volume increased during hypoxia at each temperature, such that cardiac output did not change significantly at 12 and 17°C. Neither pHa nor changed significantly during hypoxia at any of the three temperatures. The influence of acclimation temperatures on experimental results from poikilotherms is pointed out. Previously-published results show quantitative differences. The significance of the present results with respect to the functioning and location of oxygen receptors is discussed. It is argued that as the metabolic demand and critical oxygen tension of the whole animal are increased at high acclimation temperatures the same must be the case with the oxygen receptor. This would raise the stimulation threshold and could account for the bradycardia seen during hypoxia becoming manifest at higher values of and the acclimation temperature is raised.
The effect of caffeine on calcium efflux and calcium translocation in skeletal and visceral muscle
Authors: Huddart H. , Syson A. J. 
Published: April 2021

ABSTRACT
KCl-induced depolarization resulted in a large stimulation of the 46Ca efflux from both cockroach skeletal muscle and rat ileal smooth muscle. Caffeine (10 mM) induced a large stimulation of 45Ca efflux from skeletal muscle, but a fall in the efflux from ileal muscle, especially if the efflux was previously stimulated by KCl depolarization. Caffeine inhibited calcium uptake by skeletal muscle mitochondria and sarcoplasmic reticulum, was without effect on ileal muscle mitochondria, but significantly increased calcium binding by ileal muscle membrane vesicular preparations. The induction of contractures and stimulation of46Ca efflux in skeletal muscle by caffeine are clearly related to inhibition of intracellular calcium binding by the sarcoplasmic reticulum and mitochondria. The relaxation of ileal muscle by caffeine and the inhibition of fibre calcium efflux correlate well with caffeine enhancement of intracellular calcium binding. These experiments suggest that the membrane vesicular compartment may be the main agency centrally involved in fibre calcium regulation in this muscle during the contraction-relaxation cycle.
The Removal of Sulphate by the Excretory Apparatus of the Blowfly Calliphora Vomitoria
Authors: Knowles G. 
Published: April 2021

ABSTRACT
The excretion of sulphate by the isolated Malpighian tubules of Calliphora vomitoria has been investigated. Contrary to expectation, it was found that the isolated tubules are freely permeable to sulphate. The rate of sulphate secretion is comparable to the rates of secretion of both phosphate and chloride. The excretion of sulphate by the intact fly has also been verified.
The secretion of hyperosmotic fluid by the rectum of a saline-water mosquito larva, Aedes taeniorhynchus
Authors: Bradley T. J. , Phillips J. E. 
Published: April 2021

ABSTRACT
Fourth-instar larvae of the mosquito A. taeniorhynchus (Wiedemann), when living in sea water, drink at a rate of 100 nl h−1 larva−1 and maintain ionic and osmotic levels in the haemolymph at about one-third those of the external medium. Hyperosmotic urine is produced in the rectum by secretion of fluid having an osmotic concentration and ionic composition similar to that of sea water, with the exception that potassium levels are elevated 18-fold in the secretion. The average rate of fluid secretion observed was 19 nl h−1 larva−1 with a maximum of 92 nl h−1 larva−1. The concentration and volume of rectal secretion may be too low to account completely for osmotic balance. The possible role of anal papillae is discussed in this regard.
The effects of calcium on water balance of the brown trout Salmo trutta
Authors: Oduleye S. O. 
Published: April 2021

ABSTRACT
Water space, tritiated water flux, drinking and urine flow rates of the brown trout were decreased by increasing the environmental calcium concentration.
Diffusional and osmotic permeabilities were identical in fresh water. This suggests that water flow across the gill occurs entirely by diffusion. Previous suggestions of a discrepancy between the two permeabilities in freshwater teleosts could have been due to an overestimation of urine flow rate upon which the determination of osmotic permeability coefficient is based.
The wide-ranging effects of calcium on hydro-mineral regulation suggests that the ion interacts with the gills.
Sound localization by the bottlenose porpoise Tursiops truncatus*
Authors: Renaud D. L. , Popper A. N. 
Published: April 2021

ABSTRACT
Sound localization was measured behaviourally for the Atlantic bottlenose porpoise (Tursiops truncatus) using a wide range of pure tone pulses as well as clicks simulating the species echolocation dick. Measurements of the minimum audible angle (MAA) on the horizontal plane give localization discrimination thresholds of between 2 and 3° for sounds from 20 to 90 kHz and thresholds from 2·8 to 4° at 6,10 and 100 kHz. With the azimuth of the animal changed relative to the speakers the MAAs were 1·3–1·5° at an azimuth of 15° and about 5° for an azimuth of 30°. MAAs to clicks were 0·7–-8·8°. The animal was able to do almost as well in determining the position of vertical sound sources as it could for horizontal localization. The data indicate that at low frequencies the animal may have been localizing by using the region around the external auditory meatus as a detector, but at frequencies about 20 kHz it is likely that the animal was detecting sounds through the lateral sides of the lower jaw. Above 20 kHz, it is likely that the animal was localizing using binaural intensity cues. Our data support evidence that the lower jaw is an important channel for sound detection in Tursiops.
The colloid osmotic pressures of invertebrate body fluids
Authors: Mangum C. P. , Johansen K. 
Published: April 2021

ABSTRACT
Colloid osmotic pressures of the body fluids of twenty invertebrate species were measured directly. The results, which are generally lower than predicted values for the same species, pertain to several physiological questions: (1) they do not quantitatively explain the frequently observed hyperosmoticity of body fluids in species believed to be osmoconformers, indicating that the condition cannot be merely a consequence of a Gibbs-Donnan equilibrium; (2) the excess of hydrostatic over colloid osmotic pressure is very small. This result supports the hypothesis that the oxygen transport function of bloods with extracellular haemocyanins and haem proteins is limited by their colligative properties; (3) the pressure relationships and the absence of colloid osmotic activity in urine indicates that filtration contributes to urine formation in several species.
On the Running of the GNU (Connochaetes Taurinus) and other Animals
Authors: Pennycuick C. J. 
Published: April 2021

ABSTRACT
A simple optical method was used to observe speed, stride length and stepping frequency in undisturbed walking or running wild animals. Most measurements were made on the gnu (adult and young calf) and Thomson’s gazelle. The hypothesis that stepping frequency is independent of speed is not tenable for any gait. The data are discussed in terms of , the average number of feet in contact with the ground. It is suggested that the value required of by the animal is the main consideration determining its choice of gait. The height of the vertical jumps in galloping does not need to increase indefinitely with speed, and the power needed for the jumps is not likely to limit the maximum galloping speed. Stepping frequency observations in the walk, trot and canter were analysed for 14 mammal species plus the gnu calf. Stepping frequency was found to vary with about the — 0·5 power of the linear dimensions in all three gaits. It is suggested that only three gaits should be recognized, the walk, trot and canter, and that they should be distinguished on the basis of (a) the symmetry or otherwise of the stepping pattern, (b) the range of over which the gait can be used, and (c) the nature of the energy transformations which occur at each step.
Insect blood-brain barrier: a radioisotope study of the kinetics of exchange of a liposoluble molecule (n-butanol)
Authors: Thomas M. V. 
Published: April 2021

ABSTRACT
About 90 % of the butanol uptake by the cockroach abdominal nerve cord washed out with half-times of a few seconds, in good agreement with an electrophysiological estimate, and the temperature sensitivity suggested an activation energy of 3 Kcal mole−1. The remaining activity washed out far more slowly, with a similar time course to that observed in a previous investigation which had not detected the fast fraction. Its size was similar to the non-volatile uptake, and was considerably affected by the butanol concentration and incubation period. It apparently consisted of butanol metabolites, which could be detected by chromatography.
Acid-base balance in rainbow trout (Salmo gairdneri) subjected to acid stresses
Authors: Eddy F. B. 
Published: April 2021

ABSTRACT
The respiratory properties of rainbow-trout blood were investigated in acid-stressed fish. In the first group acid was introduced into the bloodstream and in the second the carbon dioxide content of the ambient water was increased. Initially the introduction of acid to the blood caused a decrease in blood pH and bicarbonate, and increases in oxygen uptake and ventilation volume. After 2-3 h these values had returned to the control levels. Trout subjected to high ambient CO2 (about 10 mmHg) showed a decrease in blood pH while and bicarbonate increased. After 8 h the trout began to show signs of compensation to the acidosis. In each experiment the blood was little changed but blood O2 content was decreased and tended not to resume the control value even after several hours. The results are discussed in terms of the various acid-base mechanisms thought to be available to the fish. These include branchial ion exchanges and the possible buffering roles of the extracellular and intracellular fluids.
Sodium extrusion by the sea-water-acclimated fiddler crab Uca pugilator: comparison with other marine crustacea and marine teleost fish
Authors: Evans D. H. , Cooper K. , Bogan M. B. 
Published: April 2021

ABSTRACT
Measurements of the blood Na concentration and transepithelial electrical potential (T.E.P.) across Uca pugilator acclimated to sea water indicate that Na is maintained out of electrochemical equilibrium with sea water. The resulting net Na influx as well as the sodium gain due to ingestion of the medium must be balanced by extrarenal Na extrusion. The small T.E.P. (– 0·7 mV) and the ‘transport numbers’ of Na and Cl indicate that the permeability to these ions is equivalent. Removal of external K results in a significant stimulation of unidirectional Na efflux that is dependent upon external Na but is not inhibited by ouabain. Transfer of Uca to K and Na-free sea water results in a 54% decline in unidirectional efflux, which is not due to T.E.P. changes. Readdition of 25 mm-K stimulates Na efflux much more than can be accounted for by changes in the T.E.P. Readdition of 25 mm-Na to potassium-free sea water does not change the Na efflux. The results indicate that Na extrusion by Uca is via a Na/K exchange mechanism which partially inhibits Na/Na exchange. Cessation of Na/K exchange (in K-free sea water) removes this inhibition and allows rapid Na/Na exchange. It is not known whether Na/K and Na/Na exchange are via the same or parallel carrier systems.
The effects of hypophysectomy, prolactin therapy and environmental calcium on electrolyte balance of the brown trout Salmo trutta, L.
Authors: Oduleye S. O. 
Published: April 2021

ABSTRACT
Adaptation of the brown trout to fresh water containing increasing concentrations of calcium resulted in a decrease in plasma electrolyte level and total electrolyte excretion. The electrolyte excretion rate was higher at the beginning than at the end of the urine collection periods.
Hypophysectomized fish had a lower plasma electrolyte concentration than the controls. This deficiency was partially corrected by prolactin therapy. High environmental calcium was only effective to a limited extent. There was no difference in the normal renal sodium output between hypophysectomized and intact fish in fresh water. Environmental calcium did not have any significant effect on renal electrolyte output of hypophysectomized fish.
The initiation of diving apnoea in the frog, Rana pipiens
Authors: West N. H. , Jones D. R. 
Published: April 2021

ABSTRACT
Diving apnoea in Rana pipiens was initiated by submerging the external nares. As the water level was raised above the frog, both buccal and lung pressure increased by an amount corresponding to the water head. During submergence the external nares remained closed, although the apnoeic period was punctuated by ventilation movements which moved gas between the lungs and buccal cavity. Bilateral section of the ophthalmic nerves did not alter the normal pattern of ventilation in air, although it often resulted in the intake of water into the buccal cavity on submergence. Introduction of water into the buccal cavity, either naturally as in denervates or by injection through a catheter in intact frogs, triggered sustained electromyographical activity in some respiratory muscles. Electroneurograms recorded from the cut peripheral end of an ophthalmic nerve showed that receptors in the external narial region were stimulated by movement of a water meniscus across them. Activity could also be recorded in the ophthalmic nerve in response to water flow past the submerged nares. Punctate stimulation of the narial region confirmed that these receptors were mechanosensitive. Bilateral electrical stimulation of the central ends of cut ophthalmic nerves in lightly anaesthetized frogs caused apnoea with a latency of less than 200 ms. The external nares remained closed throughout the period of stimulation although buccal pressure events, resembling underwater ventilation movements, occurred when stimulation was prolonged.
Carbon dioxide combining properties of the blood of the shore crab Carcinus maenas (L.): carbon dioxide solubility coefficient and carbonic acid dissociation constants
Authors: Truchot J. P. 
Published: April 2021

ABSTRACT
The carbon dioxide solubility coefficient, , and the apparent carbonic acid dissociation constants, and , were estimated in the serum of the crab Carcinus maenas at various temperatures and ionic strengths.
At 15 °C, the indirectly determined value is 0·0499 m-mole 1−1 torr−1 for crabs living in normal sea water (salinity ca. 35 ‰). It is apparently independent of the serum protein concentration and of the stage of the moulting cycle.
For crabs living in undiluted sea water, the mean value, determined either gasometrically or titrimetrically, is 6·027 at 15 °C. At the same temperature, . These values approximate to those of sea water at 35‰ salinity. drops as temperature rises; the measured is –0·0053 pH unit °C−1 between 10 and 30 °C. rises as the ionic strength is lowered.
Alignment nomograms have been constructed for the determination of and values in relation to various conditions of temperature and salinity.
Unidirectional ion movements in the hindgut of larval Sarcophaga bullata (Diptera: Sarcophagidae)
Authors: Prusch R. D. 
Published: April 2021

ABSTRACT
Unidirectional Na+, K+, and Cl− fluxes were measured across the isolated hindgut of larval Sarcophaga bullata. Both K+ and Cl− are actively secreted into the hindgut lumen, whereas Na+ is distributed passively. The movements of K+ and Cl− are not entirely independent of each other, and the movement of one ion influences the flux of the co-ion. The NH4+ ion is secreted into the hindgut by a mechanism separate from K+ secretion.
Ciliary propulsion of objects in tubes: wall drag on swimming Tetrahymena (Ciliata) in the presence of mucin and other long-chain polymers
Authors: Winet H. 
Published: April 2021

ABSTRACT
The lubrication effect of three long-chain polymers - mucin, methylcellulose and Ficoll - on ciliary propulsion in tubes is measured by plotting the relative velocities of swimming ciliates as a function of tube bore diameter. Mucin shows the most unequivocal lubrication, which is found at concentrations between 0% and 9·1% (w/v).This observation, coupled with visco-metric measurements which show that ciliary tip shear rates are sufficient to solate mucin, serve as the groundwork for a model of mucin lubrication which explains the optimized lubrication behaviour of thixotropic gelating polymers as an expression of the responses to shear by the various stages of polymer clustering during the gelation process. In addition to the lubricative effect, another wall drag reduction effect by mucin was measured in the clearance region beyond the lubrication layer. This apparent viscosity reduction is optimized in the concentration range between 1·7 and 4·1 % mucin and may also be explained in terms of the properties of gel clustering.