bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isosmotic Regulation in Various Tissues of the Diamondback Terrapin Malaclemys Centrata Centrata (Latreille)*
Authors: Gilles-Baillien M. 
Published: April 2021

ABSTRACT
Osmotic adjustment is achieved by blood and intracellular fluids in the diamond-back terrapin when acclimatized either to fresh water or to sea water. The muscle adjusts its composition to a higher blood osmotic pressure by greater concentrations in ammonia, in taurine and in urea and to a lesser extent in all amino acids (aspartate excepted). The inorganic ion content is not affected. In the bladder mucosa ammonia, taurine and all amino acids are more concentrated in sea-water animals. But essentially urea is responsible for the higher osmotic pressure. Of the inorganic ions only potassium shows a (slight) increase in sea-water animals. In the colon mucosa there is a slight increase in the total amino acid content, in the concentrations of sodium and chloride, and a larger increase in urea. In the jejunum mucosa the concentrations of amino acids, urea and K are much higher in sea-water animals. The results are discussed within the framework of isosmotic regulation of intracellular fluids.
Control of Heart Rate in Cecropia Moths; Response to Thermal Stimulation
Authors: Hanegan James L. 
Published: April 2021

ABSTRACT
The site for regulation of heart rate is the pterothoracic ganglia. Heart rate increases when the animal goes from an inactive to an active state. At low air temperatures the transition is from torpor to warm-up and above 35 °C the transition is from torpor directly to flight. The heart of Cecropia moths isolated from neural connexions to the thoracic ganglia responds directly to temperature changes. In actively flying animals the heart rate increases in response to thoracic heating.
The Circulatory Physiology of Helix Pomatia: I. Observations on the Mechanism by Which Helix Emerges from its Shell and on the Effects of Body Movement on Cardiac Function
Authors: Sommerville Barbara A. 
Published: April 2021

ABSTRACT
1. Helix uses the muscular floor of the mantle cavity to effect several movements. The contraction and relaxation of these muscles is concerned primarily with filling the lung and absorption of oxygen under pressure. The movement is linked with that of the pneumostome, which is open while the floor is depressed and closed when it is raised. An exaggeration of the breathing movements serves to generate the pressure in the cephalopedal haemocoel, which propels the anterior part of the body out of the shell. 2. The rate and regularity of heart-beat vary during the breathing cycle, being slow and irregular when the pneumostome is closed and fast and regular when it is open. 3. Observation of the intact heart of Helix showed changes in the degree of filling indicating an increased blood flow from the haemocoel to the pulmonary veins and heart when the mantle cavity floor was depressed. The total volume of the heart and pericardial cavity was greater at ventricular diastole than at ventricular systole. 4. When the cardiac nerve was severed a significant but inconsistent relationship between the heart activity and the breathing cycle remained. 5. Helix pomatia, H. aspersa, Archachatina, Monodonta and Arion ater all have a semilunar valve on the common aorta directed so as to prevent blood flowing from the aorta into the ventricle. H. pomatia and H. aspersa have a second semilunar valve in the anterior aorta while in Archachatina the anterior aorta passes through a muscular constriction.
The Circulatory Physiology of Helix Pomatia
Authors: Sommerville Barbara A. 
Published: April 2021

ABSTRACT
In isolated heart preparations of Helix pomatia perfused with Hedon Fleig solution, a minimum of 5% Helix blood was necessary for sustained rhythmical beating. In the absence of the first aortic valve the heart was unable to pump fluid against a negative pressure gradient, the frequency of beat was directly proportional and the amplitude of beat inversely proportional to the arterial pressure while the frequency was inversely proportional to the venous pressure. When the first aortic valve was included in the preparation the heart pumped efficiently and the frequency response was reversed in each case.
Studies on the Mechanism Of Chloride Absorption by the Goldfish Gill: Relation With Acid-Base Regulation
Authors: Renzis G. De , Maetz J. 
Published: April 2021

ABSTRACT
Pretreatment of Carassius auratus in artificial media (de-ionized water, sodium sulphate or choline chloride solutions), resulted in simultaneous loss of internal Na and Cl2 variations in the total CO2 and NH3 plasma content; blood pH shifts towards alkalosis in fish treated with sodium sulphate and towards acidosis in fish treated with de-ionized water or choline chloride. Fish kept in de-ionized water and in sodium sulphate solution were compared with control (tap water) fish. Branchial chloride fluxes were studied as a function of external chloride concentration, the accompanying cation being impermeant (choline) or permeant (sodium). For chloride influx saturation kinetics prevails, the maximal rate of uptake being about 3 times faster in sodium sulphate than in fish kept in deionized water, the apparent affinity of the uptake mechanisms (Km) remaining the same. Substitution of choline by sodium increases the maximal rate of influx without changing the Km or efflux in all types of fish. The quantity of base excreted is correlated to the quantity of Cl− absorbed confirming the Cl−/HCO3−exchange process. The degree of linkage between Na and Cl absorption is discussed in relation to the maintenance of acid-base balance by the gill.
Modification of the Motor Reflex Responses Due to Repetition of the Peripheral Stimulus in the Cockroach
Authors: Zilber-Gachelin N. F. , Chartier M. P. 
Published: April 2021

ABSTRACT
In the cockroach Blabera craniifer repeated air puffs to the cerci induce a habituation of the corresponding escape reflex, which we have tried to relate to the transfer properties of the two central relays of the reflex. In this paper transmission through the first relay, the 6th abdominal ganglion (A.G.), was studied both by electrical stimulation of the sensory cereal nerve and by application of natural stimuli (air puffs) on the cerci, while recording simultaneously on the cereal nerve and the abdominal cord, i.e. respectively before and beyond the synaptic relay. The electrical stimulation study shows transmission to be relatively labile. This property is still more apparent if air puffs are delivered. If they are separated by less than about 10 sec the cereal nerve response decreases, which is a sign of a receptor adaptation. For longer intervals, although this adaptation disappears, the response nevertheless decreases on the cord, implicating the ganglionic relay as the centre of a habituation phenomenon. The characteristics of this habituation are the following: with repetition of the stimuli, the response decreases down to a non-zero plateau (decrease of about 50 % if a puff is delivered every 20 sec); it recovers spontaneously if stimulations are suppressed; habituation is potentiated when successive series of habituations followed by spontaneous restorations are accumulated; it is more pronounced as the stimulation frequency is increased; finally, it does not show generalization. These results confirm that the 6th A.G. independently exhibits a real habituation process. The mechanism of this habituation process is discussed. A post-excitatory pre-synaptic depression intrinsic to the reflex’s excitatory synapses themselves is tentatively proposed.
Modification of the Motor Reflex Responses Due to Repetition of the Peripheral Stimulus in the Cockroach
Authors: Zilber-Gachelin N. F. , Chartier M. P. 
Published: April 2021

ABSTRACT
The synaptic transfer properties within the 3rd thoracic ganglion (T.G.) from the abdominal cord axons to the motoneurones has been studied in the cockroach. This ganglion was completely de-afferented except for motor nerve 4, whose links with the muscles of the posterior legs were left intact. The response of one of these nerves to electrical stimulation of the abdominal cord involves activation of 2 types of units : Slow excitatory fibres which have a tonic discharge and respond to each low-threshold abdominal cord stimulation by a transient increase of this firing rate; these units are responsible for muscular tonus and for low amplitude movements (startle reactions). Fast excitatory fibres, which have no tonic discharge and require for their activation higher intensity and frequency of stimulation, i.e. an important temporal and spatial summation. They are responsible for larger and more rapid movements. They fire without any precise chronological relation with the stimuli, often in bursts which continue after the end of the stimulations and cause sudden rhythmic movements. During repetition of the stimuli, the two types of synaptic pathways show both habituation and facilitation through temporal summation and post-tetanic potentiation. These two phenomena persist after the end of the stimulations and have long (minutes) but different time courses. Moreover, habituation always prevails over facilitation if stimulations are continued during a sufficient time. These antagonistic properties existing at the same time might explain the complex way in which the motor responses develop with the application of repetitive trains of stimuli to the cord. The role of these properties in the changes of the reflex motor responses to successive air puffs applied to the cerci has been studied. These properties appear to be responsible for the sensitization of the responses which can be sometimes observed. They lead, in conjunction with the habituation properties of the 6th abdominal ganglion (A.G.), to the disappearance of the escape reflex involving firing of both fast and slow fibres. Finally, they seem to have a minor role in habituation of the startle reactions (involving firing of only the slow fibres) which would be mainly due to the 6th A.G. habituability.
Evidence For an Auditory Function of the Swimbladder in the Cod
Authors: Sand Olav , Enger Per S. 
Published: April 2021

ABSTRACT
Saccular microphonic potentials in cod (Gadus morhua) were recorded by means of implanted electrodes during sound stimulation with different swimbladder volumes. To obtain acceptable acoustic conditions, the experiments were conducted at 6 m depth in the sea. Swimbladder volume had no effect on the microphonic potentials at 100 Hz, whereas its effect was marked at higher frequencies. The sound pressure necessary to evoke microphonic potentials just above the electric background noise was about 20 dB higher for the empty bladder, compared to the full bladder at 300 Hz. The microphonic potentials are ultimately linked to excitation of eighth-nerve fibres, and it is concluded that the existence of gas in the cod swimbladder has a positive effect on hearing sensitivity for all frequencies from a lower transient frequency to the upper frequency limit of hearing. Gas in the swimbladder will furthermore extend the audible frequency range. The upper frequency limit for the saccular microphonic potentials is in good agreement with the upper audible frequency limit determined from behavioural audiograms for cod, thus indicating that this frequency cut-off may be due to inadequacy of the peripheral auditory apparatus.
Directional Sensitivity of Saccular Microphonic Potentials in the Haddock
Authors: Enger P. S. , Hawkins A. D. , Sand O. , Chapman C. J. 
Published: April 2021

ABSTRACT
Microphonic potentials from the sacculus in the haddock have been recorded by implanted electrodes during horizontal vibration of the fish in air. This gives a good simulation of sound stimulation in water. The microphonic potential amplitude was a function of the vibration angle, and from most recording loci maximal amplitudes were obtained for vibration directions parallel to the long axis of the fish. The sensory cells contributing to this response are therefore most sensitive to displacements in the same direction as sound-induced swimbladder pulsations would produce. This result thus supports the theory of an accessory role of the swimbladder in sound reception. Highest sensitivity to vibration directions other than parallel to the long axis of the fish has been obtained from other recording loci. One example of highest sensitivity to a vibration direction at right angle to the long axis of the fish is presented. The findings that different sensory cells appear to have different axes of maximal sensitivity to vibration provides one possible neurological explanation for the ability of fish to detect the direction to a sound source.
The Initiation and Control of Free Amino Acid Regulation of Cell Volume in Salinity-Stressed Marine Bivalves*
Authors: Pierce Sidney K. , Greenberg Michael J. 
Published: April 2021

ABSTRACT
Molluscan cells maintain constant volume in decreasing salinities by releasing intracellular free amino acids as osmotic solute. During a salinity decrease both osmotic pressure and ion concentrations decline simultaneously. Either condition might initiate the amino acid release. Under constant osmotic conditions a decrease in Na+, K+ or Cl− concentration in the medium surrounding the isolated bivalve heart, did not result in an amino acid efflux. On the other hand, removal of Ca2+ and Mg2+ resulted in a vigorous amino acid efflux which continued until the divalent ion concentration was restored. The hypo-osmotically induced amino acid efflux could be partially blocked by raising the external divalent ion concentration. Similarly, lanthanum proved to be an effective blocking agent, both in low osmotic pressures and in Ca2+- and Mg2+-free SW. These results show that salinity-induced free amino acid regulation is initiated by a decrease in external osmotic pressure. The time course of the efflux is dependent on external divalent ion concentration. Finally, the site of divalent ion action is at the external membrane surface. A hypothetical membrane model is proposed.
The Stability of the Free Amino Acid Pool in Isolated Peripheral Nerves of Carcinus Maenas (L.)
Authors: Evans P. D. 
Published: April 2021

ABSTRACT
Isolated peripheral nerves of Carcinus maenas (L.) were capable of maintaining their free amino acid levels steady for the first hour of incubation in saline. The addition of a presumed blood concentration of D-glucose (7 ·2 mg/100 ml) caused a rapid drop in the amino acid levels, whereas incubation in actual fresh samples of blood did not. It is possible therefore that much of the glucose in crab blood might be effectively sequestered into the haemocyte fraction. It is suggested that metabolism might play an important part in the maintenance of the very steep free amino acid concentration gradients across the neuronal membranes of this species. The efflux of amino acids from this tissue is complex. It consists of a slow component T0·5 = 77 ·7 min) and a fast component (T0·5 = 3 ·1 min) which account for about 50% and 40% respectively of the total intracellular radioactivity accumulated after a 20 min incubation. In experiments where the nerves retained connexion with the thoracic ganglion, the levels of amino acids were higher than in controls which were isolated from the ganglion by a ligature. The possible significance of these findings is discussed.
Blood Pressure and Its Hydraulic Functions in Helix Pomatia L.
Authors: Dale B. 
Published: April 2021

ABSTRACT
Blood pressure has been measured in several parts of the haemocoele of a representative terrestrial pulmonate, Helix pomatia. A venous pressure of 8 cm of water is required to overcome the resistance presented by the branchial plexus and to effect the process of ultrafiltration in the renal plexus. Visceral sinus and sub-renal sinus blood is at a pressure barely exceeding this value and need only perform the two named functions before returning to the auricle. Blood in the cephalopedal sinus and general haemocoele of the foot is at a higher pressure, of up to 16 cm, and has obvious hydraulic functions. Partly by review of the literature and partly by direct observation these functions are discussed. The distribution of blood during different states of activity and the importance of the heart in maintaining the high haemocoelic pressure of pulmonates is also briefly discussed.
Central Control of Postural Orientation in Flatfish
Authors: Platt Christopher 
Published: April 2021

ABSTRACT
Visual influences on postural responses mediated by the otolith organs were studied in behavioural and physiological experiments on two species of flatfish, the bothid Citharichthys stigmaeus and the pleuronectid Hypsopsetta guttulata. Ocular compensation to lateral tilt is altered toward a directional light stimulus ; the light effect is independent of the tilt effect, and sums with it. Maximum light effect is roughly one-fourth the magnitude of the maximum tilt response. Single shocks to the optic tectum evoke up to three responses in the cut stump of the ipsilateral vestibular nerve, falling into three latency groups at roughly 5, 10 and 20 msec; all three follow stimulation of the anterior lateral tectum. The two later groups suggest by their delay and extinction at low stimulus rates that their path involves at least one synapse. Some units determined as primary otolith-organ afferents by their response characteristics to lateral tilts show a change in rate following a burst of shocks to the tectum, but no response to single shocks. The usual effect is excitatory, with a latency of 50 –100 msec, and lasting 200 –500 msec after the stimulus. Some of these units also show tonic alteration in rate while a light is shining into one eye. The alteration is either an increase with light to either eye, or a directiondependent increase or decrease, with a latency of 50 –100 msec, and lasting ionically during stimulation times of up to 1 min. The effect is independent of tilt. While the proportion of affected units is small, the elimination of mechanical, muscular, autonomic or antidromic effects and the specificity of many of the responses demonstrate that optic-vestibular integration can involve an efferent control system from the tectum to the otolith organs. The presence of such visual interactions with vestibular input in adult flatfish leads to the hypothesis that the central control of the 90 ° postural change occurring during flatfish metamorphosis may involve crucial optic influences during the period of eye migration.
Maintenance of Constant Wave Parameters by Sperm Flagella at Reduced Frequencies of Beat
Authors: Brokaw C. J. , Josslin R. 
Published: April 2021

ABSTRACT
Treatment of Ciona spermatozoa with low concentrations of Triton X-100 (less than 0·01 %) causes them to beat at lower than normal frequencies. The wavelength of the flagellar bending waves remains constant over the range from 10 to 40 Hz. There is a small increase in wavelength at lower frequencies; in the range of 1·5–6·2 Hz, the wavelength averaged 114% of the normal value for Ciona spermatozoa. The angle of bend of the bent regions of the flagellar bending waves remained constant within ± 10% over this range of frequencies. Decapitated sperm flagella from Lytechinus beat at a continually declining frequency as they exhaust their content of ATP. Both wavelength and bend angle retain normal values until the frequency falls below about 8 Hz. Both parameters increase at lower frequencies, with a sharp increase below 3 Hz. ATP-reactivated spermatozoa from Lytechinus show relatively small changes in wavelength and bend angle as the frequency is varied over the range from 5 to 25 Hz by varying the ATP concentration. Constancy of wavelength over a wide range of frequencies is consistent with the hypothesis that wavelength is determined by the relative values of viscous bending resistance within a flagellum and external viscosity. No satisfactory explanation is available at present for the constancy of bend angle over a wide range of frequencies nor for the changes in wave parameters which are observed at low frequencies.
Studies on Neurohumoral Induction of Compensatory Mechanisms in Thermal Acclimation of Poikilotherms
Authors: Kale Radha D. , Rao Kandula Pampapathi 
Published: April 2021

ABSTRACT
The effect of cold acclimation, which brings about changes in the total metabolism, has been studied in the two species of earthworms Perionyx excavatus and Lampito mauritii. Of the two species the lowest temperature that could be tolerated by Lampito was only 17 ± 1 °C whereas Perionyx could survive at 9 ± 1 °C. The rate of oxygen consumption of the cold-acclimated Perionyx is higher than the rate of respiration of the normal Perionyx when measured at room temperature. The tissue respiration of Perionyx when measured at 20, 25, 30 and 35 °C shows Prosser ‘s acclimation type IV, i.e. translation at lower temperature range and rotation at high temperature. In Lampito the respiratory rate (measured at room temperature) of worms injected with extract of nervous tissue from cold-acclimated worms (18 °C) is higher than that of worms injected with extract of nervous tissue from normal worms. In Perionyx the respiration of the body-wall muscle tissue from injected worms, measured at 20, 25, 30 and 35 °C, is found to be similar to that of the tissues of cold-acclimated worms. It is suggested that the neurosecretions of nervous system have an important role in controlling the metabolic activities during cold-acclimation in earth-worms.
Yolk Protein Synthesis in the Ovary of Octopus Vulgaris and Its Control by the Optic Gland Gonadotropin
Authors: O ‘dor R. K. , Wells M. J. 
Published: April 2021

ABSTRACT
The synthesis of yolk proteins can conveniently be studied in Octopus where removal of the subpedunculate lobe from the brain causes secretion of a gonadotropin by the optic glands and results in precocious sexual maturation (Wells & Wells, 1959). Maturing animals can thus be prepared as needed. The normal reproductive pattern of the female is a further advantage. All the ova from any single animal are deposited during a short period (Mangold-Wirz, 1963) and therefore tend to develop synchronously (Brock, 1879). This results in a high overall rate of yolk synthesis and provides relatively uniform samples of vitellogenic ova without special selection.
Experimental Disruption of the Blood-Brain Barrier System in An Insect (Periplaneta Americana)
Authors: Treherne J. E. , Schofield P. K. , Lane N. J. 
Published: April 2021

ABSTRACT
The effects of hypertonic urea and hypertonic glucose solutions upon the ‘blood-brain barrier’ in the isolated abdominal nerve cord of the cockroach have been studied. Electrophysiological studies showed that a hypertonic solution of urea, but not of glucose, was effective in reducing the barrier to the entry of potassium and the loss of sodium. Electron-microscopic studies revealed no significant ultrastructural changes, and no disruption of the perineurial barrier to the entry of ionic lanthanum, following comparable exposure to the hypertonic solutions. It is suggested that this alteration of the blood-brain barrier may result from a selective change in permeability of the perineurial membranes or tight junctions.