bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Training on the Swimming Muscles of the Goldfish (Carassius Auratus)
Authors: Davison William , Goldspink Geoffrey 
Published: April 2021

ABSTRACT
Goldfish (Carassius auratus) were exercised continuously for periods of 28 days at swimming speeds of 1·5, 3·0 and 4·5 body lengths per second and their rates of growth were determined. Changes in muscle fibre size were examined, as were changes which occurred in the concentrations of the major chemical constituents of these cells.
These fish, typical of the carp family in that they are found only in still or slowly moving water, did not adapt well to the flowing water environment at any swimming speed. They often grew less than the controls, although consuming much more food. Changes in the composition of the muscle fibres indicated that excess food was not being stored, and also indicated that the major fuel for swimming at all speeds was glycogen. The fish survived well at high speeds and it was suggested that this was due to the ability of the species to metabolize glycogen anaerobically without the production of lactic acid.
Internal Volume and Pressure Regulation in Carcinus Maenas
Authors: Norfolk J. R. W. 
Published: April 2021

ABSTRACT
In Carcinus, in dilute media, internal volume and pressure were found to be regulated by the intermittent release of urine which maintained internal pressure at a mean value of 15 cm water, compared to a mean value of 10 cm for crabs in sea water. Following transfer of crabs from 100 % to 50% sea water, urine production (measured by a continuous collection method) was observed to increase within 5 min of dilution of the medium, by which time the estimated increase in internal pressure would have been only 1·3 cm water. Such a pressure increase is considered inadequate to stimulate a rise in urine production, since artificially raising internal pressure of crabs in sea water did not result in an increase in urine flow, until the pressure was in excess of 20 cm water.
The results support the hypothesis that the stimulus to increase urine production by crabs in dilute media is not raised internal pressure due to osmotic influx of water. An alternative hypothesis, namely that of changes in urine production being in response to direct monitoring of the external environment, is suggested.
The Optokinetic Basis of Head-Bobbing in the Pigeon
Authors: Frost B. J. 
Published: April 2021

ABSTRACT
Head-bobbing of pigeons during walking and landing was studied using high-speed motion photography. The analysis of film records indicated that head-bobbing whilst walking consists of two phases: one where the head is ‘locked’ in space but moves backward relative to its forward moving body; and another where it is thrust rapidly forward to a new position. The fact that head-bobbing is abolished when pigeons walk on a treadmill suggests it is primarily a visual response rather than an equi-libratory response. Data are presented which show that stabilization during the ‘lock’ phase allows a small degree of slippage which is the probable source of error signals for compensatory head movements. The head-bobbing that appears to occur during landing is shown to be illusory.
The Effect of Hypertonic Solutions on The Rate of Relaxation of Contracture Tension in Mytilus Smooth Muscle
Authors: Tameyasu T. 
Published: April 2021

ABSTRACT
The effect of the bathing solution tonicity on the mechanical properties of the anterior byssal retractor muscle (ABRM) of Mytilus edulis was examined. The rate of relaxation of contracture tension produced by acetylcholine (ACh) was greatly reduced when the bathing solution tonicity was increased by adding NaCl, KC1 or LiCl after the removal of ACh, whereas a decreased tonicity increased the rate of relaxation. The contracted ABRM in hypertonic solutions showed no active shortening after an isotonic release and barely redeveloped active tension after a quick release. The resistance to stretch increased with increasing tonicity of the bathing solution. The wet weight of the ABRM decreased much more markedly in sucrose-hypertonic solution than in Na-, K- or Li-hypertonic solutions, but the decrease in the rate of relaxation was less marked in the former, indicating that there may be little relation between the rate of relaxation and the degree of osmotic deformation of the ABRM fibres. It is suggested that the elevated ionic strength in the myoplasm may be related to a reduction in the rate of detachment of the cross-linkages between the thick and thin filaments.
Respiratory and hydrostatic functions of the intestine of the catfishes Hoplosternum Thoracatum and Brochis Splendens (Callichthyidae)
Authors: Gee John H. , Graham Jeffrey B. 
Published: April 2021

ABSTRACT
The air-breathing behaviour of Hoplosternum thoracatum and Brochis splendens has been studied and their strategy of coordinating the respiratory and hydrostatic functions of the accessory respiratory organ has been examined. H. thoracatum and B. splendens are continuous but not obligate air-breathers and individuals of the former breathe air in synchrony with each other. Frequency of air-breathing increased with increased activity in H. thoracatum. Aquatic respiration (Vo2) in H. thoracatum decreased in hypoxic water but aerial Vo2 maintained a fairly constant total Vo2 independent of aquatic O2. Total Vo2 is higher when fish breathe both air and water but aerial Vo2 did not exceed 75% of total Vo2. The accessory respiratory organ provides about 75% of the lift required to attain neutral buoyancy whereas the swimbladder provides less than 5%. The mean decreases in volume of the accessory respiratory organ in the period between breaths of B. splendens and H. thoracatum were 13.2 and 7.8% respectively. With a gas phase of O2, B. splendens maintained a similar frequency of air breathing and showed a slightly greater reduction in buoyancy between air breaths when compared to breathing air. With a gas phase of N2, air breathing was less frequent and decreases in buoyancy between air breaths were much less than when breathing air. The respiratory and hydrostatic functions of the accessory respiratory organ are compatible. Buoyancy is maintained by frequent air breaths taken in part in response to a decrease in volume of the accessory respiratory organ. This reservoir of O2 could increase metabolic scope during bursts of activity.
Kinetics of Sodium and Lithium Movements Across the Blood-Brain Barrier of An Insect
Authors: Schofield P. K. , Treherne J. E. 
Published: April 2021

ABSTRACT
The electrical responses of axons were used to monitor the time-course of a change in the concentration of an ion species in the fluid bathing the axons in connectives of isolated cockroach nerve cords. Initial exposure of the connectives to sodium-deficient Ringer resulted in a depletion of extra-axonal sodium which was much slower than the restoration observed on return of the sodium Ringer. It is suggested that this asymmetry could result from a sodium reservoir which delays the initial decline. Subsequent net inward and outward movements of sodium ions were rapid and symmetrical. Unlike sodium ions, lithium ions were apparently unable to reach the axon surfaces following sodium depletion. In view of the similar properties of sodium and lithium ions in many biological systems it is therefore unlikely the the sodium movements were passive. Instead, the results support the idea of net sodium transport by the perineurial and/or glial elements.
The Role of the Thermal Hysteresis Factor in Tenebrio Molitor Larvae
Authors: Patterson Jean L. , Duman John G. 
Published: April 2021

ABSTRACT
The haemolymph of larvae of Tenebrio molitor contains a factor which produces a thermal hysteresis (a difference between the freezing and melting points) of approximately 0·75 °C. When larvae were acclimated to low temperatures or short photoperiod the thermal hysteresis increased more than twofold. Coincident with the increase in thermal hysteresis the supercooling points and lower lethal temperatures of the larvae were depressed. Therefore, the thermal-hysteresis-producing factor seems to function as an antifreeze.
The factor may also act as an adaptation to prevent desiccation. Thermal hysteresis increased almost three-fold in larvae acclimated to low relative humidity. Also, larvae with high levels of the thermal hysteresis factor survived low relative humidities much better than did larvae with lower levels.
Mating Call Recognition in the Green Treefrog (Hyla Cinerea): The Significance of Some Fine-Temporal Properties
Authors: Gerhardt H. Carl 
Published: April 2021

ABSTRACT
Two hundred and eighty-eight female green treefrogs responded in two-choice experiments using synthetic calls. The spectral properties of the sounds were similar ; the fine-temporal properties were systematically varied. Females preferred sounds in which the waveform periodicity was about 300/s, a rate typical of natural mating calls. They discriminated strongly against calls with periodicities of 100/s, 60/s and 50/s. Aperiodic calls and calls with periodicities of 225/s and 900/s were intermediate in attractiveness. The results of four experiments indicated that periodicity preferences depended on corresponding changes in the amplitude-time envelopes of the signals. Neurophysiological correlations and the implications of the behavioural results are discussed. The biological significance in species recognition and in the differentiation of the mating call from other signals in the repertoire of the green treefrog is discussed.
The Effect of Calcium and Magnesium on the Spontaneous Release of Transmitter At Insect Motor Nerve Terminals
Authors: Washio H. M. , Inouye S. T. 
Published: April 2021

ABSTRACT
The effect of the extracellular calcium and magnesium concentrations and calcium ionophore, X-537A, on the frequency of miniature excitatory post-synaptic potentials (MEPSPs) was studied in cockroach leg muscle fibres. The frequency of MEPSPs increased as the calcium concentration was increased from 0·1to 10 mM In the presence of 10 mm magnesium, how-ever, raising the calcium concentration from 0·1to 1 mM slightly depressed the frequency. In saline containing elevated potassium (20·8 mm), increasing the calcium concentration produced a much higher frequency than that in the normal potassium saline (10·8 mm) in the absence of magnesium. Raising the extracellular potassium concentration was without effect unless the bathing solution contained calcium. The frequency of the miniature potentials was reduced as the magnesium concentration was raised from o to 10 mM, depending on the presence of calcium ions. On the contrary, a slightly increased frequency was observed in the low calcium saline as the magnesium concentration was raised from 1 to 10 mM. The reciprocal relationship between calcium and magnesium and the time course of the effect suggest that both ions act at the same surface sites in the presynaptic membrane. X-537A elicited a transient increase in frequency followed by a fall of the frequency to a very low rate. Further application of the ionophore was without effect. The effect of X-537A on the spontaneous release of transmitter at the insect neuromuscular junction was comparable with that on the spontaneous acetylcholine release in vertebrate neuromuscular junctions.
Effects of the Non-Protein Amino Acids L-Canavanine and L-Canaline on the Nervous System of the Moth Manduca Sexta (L.)
Authors: Kammer Ann E. , Dahlman D. L. , Rosenthal Gerald A. 
Published: April 2021

ABSTRACT
Injection of L-canavanine, a naturally occurring arginine analogue, and of its metabolic derivative, L-canaline, induced almost continuous motor activity in adult tobacco hornworms, Manduca sexta (L.). Initially the moths flew normally, but after a time interval that depended both on the amino acid and on the dose (1−45 μmol/g fresh weight) the moths became disorientated and muscle activity was less patterned. Canaline produced its initial effects 12−30 min after injection, whereas activity in response to canavanine began after a delay of 1−2 h. Canaline (derived from canavanine by an arginase-mediated hydrolytic cleavage) is probably the biologically active factor.
Canaline did not affect axonal conduction of action potentials nor the activity of mechanoreceptors on the forewing. Canaline (22μmol/g fresh weight) prolonged the postsynaptic potential of flight muscle fibres, but after 20−40 min. the electrical activity of muscle fibres was normal. The results show that canaline alters the activity of the central nervous system of adult M. sexta, but its mode of action is unknown.
Control of Salivation in the Blowfly Calliphora
Authors: Bay Christina M. Hansen 
Published: April 2021

ABSTRACT
A technique has been developed for collecting saliva from the salivary duct of flies during feeding. In newly emerged flies salivation is evoked by stimulation of the labellar taste papillae by crystalline sugar, by sugar in solution and by water. Only sugars which excite the sugar receptors are effective. In flies which have previously fed, solid sucrose or meat induce regurgitation of the crop contents, or salivation if the crop is empty. Sucrose in solution provokes neither reaction. Saliva always contains digestive enzymes, even if the ingested food requires no digestion. Blood taken from salivating flies stimulates fluid secretion from isolated glands, whereas blood taken from non-salivating flies is ineffective. Section of the cephalo-thoracic nerve cord abolishes salivation in response to feeding. Section of the ventral nerve cord posterior to the thoracic ganglion, or removal of the abdomen, severely reduces but does not abolish the salivatory response. Saliva secreted by mature flies contains 75 mm-Cl− whereas saliva secreted during the first meal after emergence has a higher Cl− concentration (about 165 mm-Cl−) which gradually declines during the first meal.
Neuronal Control of Swimming in the Medicinal Leech
Authors: Poon Margaret , Friesen W. Otto , Stent Gunther S. 
Published: April 2021

ABSTRACT
A network of intra- and intersegmental synaptic connexions has been identified in the ventral nerve cord of the leech that links the set of oscillatory interneurones of the central swim oscillator to the motor neurones commanding the swimming rhythm. Excitatory connexions lead from oscillatory interneurones to both excitatory and inhibitory motor neurones, whereas inhibitory connexions lead from oscillatory interneurones to only the inhibitory motor neurones. Connexions leading from a motor neurone back to the oscillatory interneurones were found in only one exceptional case, an inhibitory motor neurone previously known to have access to the central swim oscillator. This network of identified connexions can account reasonably well for the mechanism by which the oscillatory interneurones drive their follower motor neurones into the phasic activity pattern characteristic of the swimming movement.
Regulation of Arterial Blood Pressure in Australian Tiger Snakes
Authors: Lillywhite Harvey B. , Seymour Roger S. 
Published: April 2021

ABSTRACT
Blood pressure was measured in the dorsal aorta of restrained, un-anaesthetized tiger snakes (Notechis scutatus) at different body temperatures during graded, passive tilt. Aortic blood pressure in horizontal snakes showed no significant change over a range of body temperatures between 18 and 33 °C (mean of measurements on 16 snakes = 42·2 ± 1·98 mmHg), while heart rate increased logarithmically (Q10 approximately 2·5). Blood pressure was stable during heating and cooling between body temperatures of 15 and 30 °C, but the pressure was 10–50% higher during heating than during cooling. Head-up tilt usually caused a brief fall in pressure at heart level followed by partial or complete recovery and tachycardia. At the cessation of tilt, there was a characteristic overshoot of the blood pressure followed by readjustment to control (pretilt) levels. Head-down tilt typically increased pressure which then either stabilized or returned toward pretilt levels. Heart rate changes during head-down tilt were not consistent in direction or magnitude. Stabilized pressures at mid-body usually increased following head-up tilt and decreased following head-down tilt, indicating physiological adjustment to posture change. Blood pressure control was evident at body temperatures ranging from 10 to 38 °C, but was most effective at the higher and behaviourally preferred temperatures. Propranolol lowered heart rate but did not influence pressure in horizontal snakes. During head-up tilt propranolol eliminated or reduced tachycardia and sometimes reduced the efficacy of pressure compensation for tilt. Phentolamine increased heart rate, lowered blood pressure, and eliminated pressure regulation during tilt. The results suggest that sympathetically mediated reflexes assist central blood pressure regulation in the tiger snake, with vasomotor adjustments having greater importance than changes in heart rate.
How The Locust Dries Itself
Authors: Pflüger Hans-Joachim , Burrows Malcolm 
Published: April 2021

ABSTRACT
All wet locusts perform a series of specific behavioural acts to rid their body of water. These acts included fluttering the wings, kicking with the hind legs and grooming the eyes and antennae. Any one act can follow another, although wing fluttering, walking and hind leg kicking are closely associated. Some locusts may omit a particular movement in some sequences of drying behaviour. All the movements remove water from the body presumably to allow the correct functioning of the sense organs, or to prevent evaporative cooling.
Static Pressure-Volume Curves for the Lung of the Frog (Rana Pipiens)
Authors: Hughes G. M. , Vergara G. A. 
Published: April 2021

ABSTRACT
Static pressure/volume curves have been determined for isolated frog lungs inflated with either air or saline. In both cases a hysteresis was present: the pressure required to produce unit change of volume being greater during inflation than deflation. The pressure necessary for a given volume change was less for the saline-filled than the air-filled lungs. The difference between these curves is due to the surface tension at the air/lung interface. Pressure/volume curves for air-filled lungs in situ were similar to curves for isolated lungs. However, a greater pressure was required for the same volume change during both inflation and deflation. Compliance was calculated from different parts of air pressure/volume curves and gave values greater than those obtained using similar calculations for higher vertebrates. These observations support other evidence for the presence of a surfactant in the lung lining of frogs in spite of the relatively large diameter of their ‘alveoli.’ The precise role of such a lining is uncertain and it is concluded that similar forces may be involved during the inflation and deflation of lungs of frogs and higher vertebrates in spite of differences in gross morphology.
Axonal Adaptations to Osmotic and Ionic Stress in An Invertebrate Osmoconformer (Mercierella Enigmatica Fauvel)
Authors: Skaer H. Le B. , Treherne J. E. , Benson J. A. , Moreton R. B. 
Published: April 2021

ABSTRACT
The giant axons in Mercierella are overlaid by narrow glial processes which provide an incomplete covering of the axonal surface. Where more complete covering occurs the intercellular clefts are not sealed by tight junctional complexes. Ionic lanthanum penetrates to the surfaces of axons from sea-water-adapted animals (in normal saline and during initial exposure to hyposmotic saline) and, also, to the surface of hyposmotically adapted axons. A relatively free intercellular access to the axon surfaces is also indicated by the rapid electrical responses of sea-water-adapted axons to hyposmotic dilution and of hyposmotically adapted axons to sodium-deficient saline. The giant axon possesses an unusual ultrastructural specialization: hemidesmosome-like structures (associated with the axon membrane) which are connected to a network of neurofilaments within the axon. Theoretical considerations suggest that these structures could enable the axons to withstand appreciable excesses in intracellular hydrostatic pressure resulting from osmotic imbalance during hyposmotic stress.
Short Communication
Authors: Collett T. S. 
Published: April 2021

ABSTRACT
Motion parallax is probably the most important method available to insects for judging the distance of objects, yet with one exception very little is known about the ways in which insects exploit this cue. Almost twenty years ago Wallace (1959) proposed that the side-to-side peering movements of juvenile locusts are performed specifically to obtain parallax information. Leg movements cause the whole body to pivot about the abdomen, shifting the head laterally about 0·5 cm and displacing the retinal image of an object in front of the insect. Provided that the locust knows how far (or fast) it moves its head and that it can measure image displacement (or velocity) it can compute the distance of the object (Fig. 1 a). The following suggests locusts do indeed do something of this kind. When an object on to which a locust is about to jump is moved horizontally in a frontal plane, in synchrony with peering, locusts are fooled into misjudging the object’s distance. For instance, if the object is moved in the opposite direction to that in which the locust peers, so enhancing image movement, the locust jumps short (Wallace, 1959).
The Tymbal Mechanism and Song Patterns of the Bladder Cicada, Cystosoma Saundersii
Authors: Simmons Peter , Young David 
Published: April 2021

ABSTRACT
In Cystosoma saundersii sound is generated by collapse of a pair of tymbals and radiated by a large, resonant, air-filled abdomen. Each tymbal comprises a flexible, biconvex membrane bearing seven long ribs. Tymbal collapse is caused by contraction of a large tymbal muscle, which acts on the tymbal plate. Each tymbal muscle is innervated by one motor neurone. A single collapse of a tymbal produces two distinct pulses of sound, one when rib 1 buckles and one when ribs 2–4 buckle. A quieter sound is produced when the ribs click outwards. A slowly contracting tensor muscle increases the convexity and stiffness of the tymbal, resulting in a reduction in the delay between the first and second sound pulse and in louder pulses. Protest songs contain features of other songs. There is a delay between the spike in one tymbal motor neurone and its partner, and hence between sound produced by one tymbal and the other, of one-quarter of the interval between spikes in one motor neurone alone. Calling songs are produced by males at dusk. Sound pulses have a smooth envelope and are very loud as a result of contraction of the tensor muscles and extension of the abdomen. Courtship songs are triggered in a calling male by the presence of a female. Song is quite quiet, and broken into short chirps.
A Quantitative Analysis of Flagellar Movement in Echinoderm Spermatozoa
Authors: Hiramoto Yukio , Baba Shoji A. 
Published: April 2021

ABSTRACT
Computerized analyses were performed on the movement of spermatozoa recorded with a high-speed camera. These provide evidence for active bending waves over the entire length of the flagellum and a single equation for waves in all cases examined. In the equation, the angular direction of the flagellum at any distance from the base is expressed by a sine function of time plus a constant, and thus flagellar waves are ‘sine-generated’. To explain the waves a model was proposed in which the active force required to generate sliding between peripheral microtubules is propagated along and around the flagellar axoneme.