bluuebunny/crossref_metadata_2025_split huggingface dataset:
Control of A Central Pattern Generator by an Identified Modulatory Interneurone in Crustacea: II. Induction and Modification of Plateau Properties in Pyloric Neurones
Authors: Dickinson P. S. , Nagy F. 
Published: April 2021

ABSTRACT
In the isolated stomatogastric nervous system of the lobster Jasus lalandii, the strong modifications of the pyloric motor pattern induced by firing of the single anterior pyloric modulator neurone (APM) are due primarily to modulation by APM activity of the regenerative membrane properties which are responsible for the ‘burstiness’ of all the pyloric neurones and particularly of the non-pacemaker neurones (constrictor motoneurones).
This modulation has been studied under experimental conditions where the main extrinsic influences usually received by the pyloric constrictor neurones (intra-network synaptic interactions, activity of pacemaker neurones, and phasic central inputs from two premotor centres) are minimal. Under these conditions a brief discharge of neurone APM induces long plateaus of firing in all of the pyloric neurones.
The non-pacemaker neurones of the pyloric network are not simply passive follower neurones, but can produce regenerative depolarizations (plateau potentials) during which the neurones fire spikes. The ability of the pyloric constrictor neurones to produce plateau potentials (plateau properties) contributes greatly to the generation of the rhythmical pyloric motor pattern. When these neurones spontaneously express their plateau properties, firing of neurone APM amplifies these properties. When most of the central inputs usually received by the pyloric constrictor neurones are experimentally suppressed, these neurones can no longer produce plateau potentials. In such conditions, firing of the single modulatory neurone APM can reinduce plateau properties of the pyloric constrictor neurones.
In addition, firing in APM neurone slows down the active repolarization phase which terminates the plateau potentials of pyloric constrictor neurones. This effect is long-lasting and voltage-dependent.
Modulation by APM of the plateau properties of the pyloric neurones also changes the sensitivity of these neurones to synaptic inputs. This effect can explain the strong modifications that an APM discharge exerts on a current pyloric motor pattern. Moreover, it might render the motoneurones of the pyloric pattern generator more sensitive to inputs from a command oscillator, and contribute to switching on the pyloric motor pattern.
Proton Secretion by the Gastric Parietal Cell
Authors: Rabon E. , Cuppoletti J. , Malinowska D. , Smolka A. , Helander H. F. , Mendlein J. , Sachs G. 
Published: April 2021

Abstract
The parietal cell occupies a unique niche among eukaryotic cells in that it develops a proton gradient of more than 4 million-fold across the membrane of the secretory canaliculus. At rest, the cell is still able to develop a proton gradient across intracellular membranes, such that the acid compartment has a pH of less than 4. Acidification depends on the simultaneous presence of ATP, K+ and Cl− as demonstrated in permeabilized cells. With acidification of the luminal side of the proton pump, there is a corresponding alkalinization of the cytosolic face as revealed by carboxyfluorescein fluorescence enhancement. Disposal of the resultant alkali depends on carbonic anhydrase activity and the functioning of a coupled Na+:H+ and Cl−: OH − antiport across the basal lateral membrane. Accordingly, with secretion there is an increased cellular Cl− level, which is exported across the apical membrane in association with K+. The Na+ pump dependent secretion of KCl across this membrane is one of the major sites of regulation of acid secretion since K+ is required at the luminal face of the gastric ATPase. Membranes isolated from secreting tissue contain a KC1 permeation pathway largely absent from membranes isolated from resting tissue. The pump itself acts as an H+ for K+ exchange ATPase which is most probably composed of at least two peptides of 100000Mr. That catalytic cycle consists of formation and breakdown of a covalent aspartyl phosphate. Formation of the intermediate depends on loss of K+ from cytosolic binding sites, and breakdown of the intermediate depends on K+ binding to the luminal face of the enzyme. During breakdown, an acid labile E P is formed, and, at high ATP concentrations, loss of this form of the enzyme is probably the rate limiting step.
Regulation of Proton Transport in Urinary Epithelia
Authors: Al-Awqati Qais , Gluck Stephen , Reeves Westley , Cannon Christopher 
Published: April 2021

Abstract
In urinary epithelia, like the turtle bladder, protons are transported by a H+-trans locating ATPase located in the luminal membrane. We have recently discovered that the H+ pump is stored in small vesicles that lie underneath the luminal membrane. CO2, a major regulator of H+ transport, causes these vesicles to fuse with the membrane thereby inserting more H+ pumps.
We have now isolated these vesicles from the turtle bladder and from beef kidney medulla. Based on inhibitor sensitivity and substrate specificity this proton translocating ATPase is different from the mitochondrial F0-F1 ATPase, yeast plasma membrane and the gastric H+,K+-ATPase. Solubilization and reconstitution of the enzyme into liposomes shows retention of transport activity and inhibitor sensitivity.
Mechanism and Control of Hyperosmoticnacl-Rich Secretion by the Rectal Gland of Squalus Acanthias
Authors: Epstein Franklin H. , Stoff Jeffrey S. , Silva Patricio 
Published: April 2021

ABSTRACT
Secretion of chloride from blood to lumen is accomplished in the rectal gland of elasmobranchs by a process of secondary active transport involving the co-transport of Cl− with Na+ across the basolateral membranes of rectal gland cells. Energy is provided by ATP via membrane Na-K-ATPase, which establishes an electrochemical gradient favouring Na+ influx into the cell. The involvement of K+ in the co-transport mechanism, so as to provide a ratio of 1 Na+: 1 K+: 2 Cl− entering the cell, would increase the energetic efficiency of the process, and is consistent with the CI/O2 ratio of 27–30 observed in secreting rectal glands. Secretion is stimulated by cyclic AMP (cAMP) and by vasoactive intestinal peptide (VIP) and adenosine, which activate adenylate cyclase. Activation of the gland in vivo probably occurs via VIP-secreting nerves as well as circulating agents; it is inhibited by somatostatin. Cyclic AMP probably stimulates chloride secretion by at least three mechanisms: (1) increasing chloride conductance across the luminal cell membrane, (2) enhancing the co-transport pathway for transmembrane movements of Na+, K+ and Cl− and (3) activating Na-K-ATPase.
Effects of Potassium and Osmolality on Spermatozoan Motility of Salmonid Fishes
Authors: Morisawa M. , Suzuki K. , Morisawa S. 
Published: April 2021

ABSTRACT
In salmonid fishes, rainbow trout and masu salmon, and the plecoglossid fish, ayu, seminal plasma had an osmolality around 300 mosmol kg−1, isotonic to the blood plasma, and contained a higher concentration of potassium than the blood plasma. Spermatozoa of salmonid fishes were motile when semen was diluted 1:100 with solutions of sodium chloride or mannitol, over the osmotic range of 0-300 mosmol kg−1. They were immotile in sodium chloride solution containing several mm potassium. This indicates that osmolality is not an essential determinant of sperm motility in the Salmonidae, and that sperm motility in these species is suppressed by the seminal potassium in the sperm duct, and initiated by a decrease in potassium concentration surrounding spawned spermatozoa when they are released into fresh water.
The Identification of Motor Neurones Innervating an Abdominal Ventilatory Muscle in the Locust
Authors: Yang Qin-Zhao , Burrows Malcolm 
Published: April 2021

ABSTRACT
Motor neurones to abdominal ventilatory muscles, with their axons in nerve 6 of the metathoracic ganglion of the locust, have been identified by intracellular recording and staining. Three muscles are innervated by the larger branches of this nerve: nerve 6a contains six motor neurones innervating the ventral diaphragm; nerve 6b contains four motor neurones innervating the median internal ventral muscle, and nerve 6d contains five motor neurones innervating the longitudinal dorsal muscle. All motor neurones innervate muscles on one side of the body only. Both the median internal ventral and the longitudinal dorsal muscles contract during the expiratory phase of ventilation. Three excitatory motor neurones to the median internal ventral muscles spike during expiration whilst the fourth, an inhibitory motor neurone, is active during both expiration and inspiration. Two of the excitatory motor neurones have cell bodies in the half of the ganglion ipsilateral to the muscle they innervate. Their neuropilar branches, however, are in both left and right halves of the ganglion. The third excitatory motor neurone has its cell body close to the midline and has most of its neuropilar branches in the half of the ganglion ipsilateral to its axon. The inhibitory motor neurone has its cell body just to the contralateral side of the midline, and three distinct areas of neuropilar branches, two contralateral and one ipsilateral to its axon.
Partitioning of Energy in Fish: Can Reduction of Swimming Activity Compensate for the Cost of Production?
Authors: Koch Franz , Wieser Wolfgang 
Published: April 2021

ABSTRACT
By using a new video activity monitoring processor (Kaufmann, 1983) in conjunction with a large respirometer, we have measured swimming activity, oxygen consumption and reproductive investment (in the form of gonadal growth) of roach (Rutilus rutilus L.) during a seasonal cycle. If the effect of temperature on metabolism is taken into account it can be shown that swimming activity is drastically reduced during the period of gonadal synthesis (July–December). On the basis of a calibration curve established for the preproductive phase (Januar–June), the reduction in locomotor activity is estimated to represent a saving of 1485 kJ kg−1 of metabolizable energy during a period in which 364 kJ worth of gonadal tissue per kg of fish are being synthesized. Our data provide the first evidence that even in a poikilothermic animal reduction of locomotor activity may compensate for the costs of producing gonadal tissue.
Wing Hair Plates in Crickets: Physiological Characteristics and Connections with Stridulatory Motor Neurones
Authors: Elliott C. J. H. 
Published: April 2021

ABSTRACT
Hairs in the subcostal hair plates of the wings of crickets have a high angular stiffness (5·5 μNmrad−1) when bent about their base. The mean threshold required to elicit action potentials is 15°. Viscous drag from air movements will not deflect the hairs sufficiently to excite them; this will only occur when the hair is bent by the opposite wing. The hair sensillae project to the ventral association area of the mesothoracic ganglion, but the endings of the stridulatory motor neurones are all in dorsal or lateral neuropiles of the thoracic ganglia. Electrical stimulation of the hair plates evokes reliable EPSPs in opener (M99), closer (M90) and wing folding (M85) motor neurones, after latencies of 4–20 ms, depending on the neurone. Properties of the hairs and motor neurones suggest that these EPSPs in the wing folding muscle (M85) and closer (M90) could play an important role in the control of wing position seen in recent behavioural study.
Quantitative Analysis of Walking in A Decapod Crustacean, the Rock Lobster Jasus Lalandii II. Spatial and Temporal Regulation of Stepping in Driven Walking
Authors: Chasserat C. , Clarac F. 
Published: April 2021

ABSTRACT
Spatial and temporal stepping parameters have been studied in a rock-lobster walking on a treadmill moving at a wide range of speeds. The stride and the return stroke (RS) duration remain more or less stable and independent of the belt speed. Nevertheless, these ‘invariant’ parameters can act as spatial and temporal buffers resulting in a very precise adjustment of individual steps.
A careful study of the power stroke (PS) duration demonstrates that the rock-lobster, although constrained to walk at an imposed belt speed, continues to correct its leg speed over a narrow range when the speed is considerably different from its natural one. Ipsilateral phases are always speed dependent, with an interleg ascending delay that is almost constant. The contralateral phase between legs of the same pair is approximately constant.
Some of the parameters described are greatly influenced by gradual or abrupt variations in the belt speed. For a given speed, there is no absolute significance in the step period and ipsilateral phase. At very slow speeds, the interleg relations are significantly changed and have been studied separately. The metachrony observed at other speeds is discussed in relation to data from other arthropods.
Optokinetic Responses, Visual Adaptation and Multisensory Control of Eye Movements in the Spiny Lobster, Palinurus Vulgaris
Authors: Neil D. M. , Schöne H. , Scapini F. , Miyan J. A. 
Published: April 2021

ABSTRACT
The optokinetic responses of the spiny lobster, Palinurus vulgaris, were measured in the vertical roll plane. The eyes followed the stripes without nystagmus, and demonstrated incomplete bilateral coupling. Closed-loop responses to oscillating stripes (20 ° peak-to-peak) showed marked habituation at frequencies above 0·l Hz, but at lower frequencies continued undiminished, with amplitude-gain values approaching 1·0. Changes in illuminance level demonstrated that the optokinetic response exhibited a threshold below which the eye initially failed to detect and follow the stripes. However, over a period of several minutes, the previous response level could be restored or even exceeded. The optokinetic response could be antagonized by a response to the irradiance gradient, which also had a threshold and showed adaptation. Migration of visual screening pigments may underlie these adaptation processes. Optokinetic stimuli could interact with proprioceptive inputs arising from displacements of the legs on a moving platform. When the proprioceptive inputs were of equal frequency and in antiphase, the optokinetic response was reduced in amplitude; it was in phase with the visual stimulus at low frequencies, and in phase with the platform in the high-frequency range. When the inputs had unequal frequencies, the eyes followed the drum if its frequency was low, but failed to follow either drum or platform if drum frequency was high. We conclude that multisensory control extends the frequency range of operation of compensatory eye movements, and is dominated by the low-frequency optokinetic response.
Mechanical Responses of A Crustacean Slow Muscle
Authors: Chapple William D. 
Published: April 2021

ABSTRACT
Mechanical properties of the abdominal ventral superficial muscle of the hermit crab, Pagurus pollicarus, were examined under isometric and iso-velocity conditions. The muscle was activated by stimulating its motor nerve at different frequencies. Length-isometric tension relations were measured. Peak tension, P0, was 0·16–0·2 MN m−2 and the sarcomere length of the muscle at the optimum length, L0, was 10·8 + 1·0 μm. Passive tension was high at L0. Correlated measurements of the operating length of the muscle and L0 indicate that the operating length is at a point on the ascending limb of the length-tension curve approximately 0·77 L0. The relationship between activation level of the muscle and the length-tension relation indicates that the curve is not substantially displaced along the length axis by increasing activation level; increased force is primarily due to an increase in the slope of the ascending limb of the curve. The force-velocity relation was obtained by measuring the force at a reference length during iso-velocity shortening of an active muscle. Hill constants of a/P0 = 0·11 + 0·02 and b = 1·07 + 0·24 mm s−1 were obtained. The maximum velocity of shortening per half sarcomere was approximately 4·2μms−1, Stretch of an active muscle did not produce an abrupt short range yield but a gradual transition between short range and terminal stiffness. This behaviour is shown to be due not to differences in cross bridge stiffness between VSM and other muscle but to a non cross bridge stiffness with a value that is one-fifth that of vertebrate muscle. Such a low stiffness may provide an intrinsic mechanism for simplifying load compensation in the absence of rapid proprioceptive reflexes for the control of muscle stiffness.
Effects of Ionophore-Mediated Transport On the Cardiac Resting Potential
Authors: Fahim Mohammad , Mangel Allen , Pressman Berton C. 
Published: April 2021

ABSTRACT
The monovalent carboxylic ionophores form lipid-soluble complexes with alkali cations which transport these ions across membranes. In a biological setting, they promote an electrically neutral exchange of intracellular potassium for extracellular sodium (Pressman, 1976). The ionophore monensin, which has a complexation preference for sodium (Pressman, 1968), has very little capability for complexing or transporting calcium or catecholamines (Pressman, Painter & Fahim, 1980). However, monensin produces a strong positive inotropic effect (Pressman, Harris, Jagger & Johnson, 1967; Sutko et al. 1977; Shlafer, Somani, Pressman & Palmer, 1978; Saini, Hester, Somani & Pressman, 1979) which is attenuated, but not abolished, by β-adrenergic blockade (Sutko et al. 1977; Shlafer et al. 1978; Saini et al. 1979). This indicates that the inotropic effect is partially mediated through an indirect release of catecholamines and, also, through a more direct mechanism, presumably by an alteration of transcellular cation gradients. Studies with cardiac Purkinje fibres show that monensin produces a shortening of the action potential, without an accompanying alteration in the resting potential (Sutko et al. 1977; Shlafer et al. 1978). Inasmuch as monensin should decrease the transcellular gradients of both sodium and potassium, one would expect that not only the action potential, dominated by the sodium diffusion potential, but also the resting potential, dominated by the potassium diffusion potential, should decrease. The present investigation was directed toward resolving the paradox of why monensin fails to alter the resting potential of cardiac muscle segments under the same conditions which alter the action potential. Our results show that depolarization of the resting potential, induced by monensin, is normally masked by the activity of the electrogenic sodium pump, and if the pump is inhibited by ouabain, then the expected depolarization is observed.
‘Instant’ Analysis of Movement
Authors: Godden D. H. , Graham D. 
Published: April 2021

ABSTRACT
The study of walking and other dynamic behaviour patterns has challenged the experimental ingenuity of researchers since Muybridge first demonstrated in a series of still pictures that galloping horses raise all four legs from the ground at once. The use of moving film improves the situation but still suffers from a fundamental disadvantage in the time required to process and analyse the changes in the image from frame to frame. A number of suggestions have been made to make film analysis more time effective but the difficulties are an inherent feature of the storage medium.
Aerial Manoeuvring Reflexes in Flightless Grasshoppers
Authors: Arbas Edmund A. 
Published: April 2021

ABSTRACT
Aerial locomotion of many insects involves jumping or dropping from elevated positions. Flight and aerobatic manoeuvring often follow locust jumps, while jumps from elevated positions can carry flightless grasshoppers several metres through the air. Leg postures and orientation movements associated with aerial locomotion have been studied in the flightless grasshopper, Barytettixpsolus (Cohn & Cantrall, 1974).
Regulation Of The Acid-Base Status During Environmental Hypercapnia in the Marine Teleost Fish Conger Conger
Authors: Toews D. P. , Holeton G. F. , Heisler N. 
Published: April 2021

ABSTRACT
Specimens of Conger conger (L.) were exposed to environmental hypercapnia in a closed recirculating seawater system. Arterial plasma pH, Pco2 and bicarbonate concentration, as well as the net transfer of bicarbonate and ammonia between fish and ambient seawater, were monitored for 30 h of hypercapnia. The initial hypercapnia-induced reduction of arterial pH by about 0·4 pH units was restored to near control values within 10 h of hypercapnia by compensatory elevation of plasma bicarbonate concentration. The continuous rise in extracellular bicarbonate from about 5 to 22 mm during this time was the result of two different mechanisms. Initially, there was a net bicarbonate transfer from the intracellular space to the extracellular compartment until the net uptake of bicarbonate from the seawater started. The amount of bicarbonate originally transferred to the extracellular space was then returned to the intracellular compartment and finally the changes in both extracellular and intracellular pH were compensated by bicarbonate taken up from the environmental seawater. Since the ammonia excretion was not increased during hypercapnia and the pattern of plasma electrolyte concentrations does not favour the H+/Na+ ion exchange mechanism, it is concluded that the additional bicarbonate is gained by active HCO3−/Cl− ion exchange against the electrochemical gradient between fish and seawater.
Role of Mosquito Saliva in Blood Vessel Location
Authors: Ribeiro J. M. C. , Rossignol P. A. , Spielman A. 
Published: April 2021

ABSTRACT
In order to ascribe a blood feeding function to the saliva of mosquitoes, we determined whether this secretion may limit the initial probing phase of biting behaviour. The probing of hosts was indeed prolonged when the salivary ducts were severed, but this prolongation was absent when mosquitoes were fed on an artificial meal contained beneath a membrane. In vitro, turbidometric assays demonstrated that saliva inhibits the ADP-and collagen-mediated aggregation of platelets. ATP and ADP were hydrolysed by saliva, and this apyrase activity explains, in part, the observed effect upon platelets. We conclude that the saliva of mosquitoes functions by facilitating location of blood vessels.
Axon Surface Infolding and Axon Size Can be Quantitatively Related in Gastropod Molluscs
Authors: Longley Roger D. 
Published: April 2021

ABSTRACT
A quantitative estimate of infolding and of its effect on electrical characteristics in axons of different sizes is given by expressions based on the allometric equation, y = axβ. These expressions can be used to describe the effect of stretching the axon and the size dependence of the axo-somatic conductance ratio.
The parameters in the allometric equation are determined for a range of axon sizes in three species of opisthobranchs from original and from published data. Analysis of variance for these data suggests that interaxonal variability of infolding is less for axons of an identifiable neurone from different specimens of the same species than for axons of different neurones from the same specimen. With the exception of the Aplysia R2 axon where the infolding size dependence may be less, the ratio of axon volume to surface in these neurones is given approximately by the equivalent axon diameter to the one-half power. For this relation of infolding to size (and if it is assumed that infolding in the soma varies with size in the same way as in the axon), the axo-somatic conductance ratio is inversely proportional to soma diameter to the three-fourths power.
These results suggest that conduction velocity increase with size is small, and because of the penalty in the concomitant increase in axon surface membrane with size, selection for larger axons probably does not occur to satisfy a requirement of decreased response time.