bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Quantitative Study of Potassium Movements in the Central Nervous System of Periplaneta Americana
Authors: Treherne J. E. , Lane N. J. , Moreton R. B. , Pichon Y. 
Published: April 2021

ABSTRACT
Using the electrical response of giant axons in the isolated abdominal nerve cord of the cockroach, Periplaneta americana, as an indication of the ionic composition of the fluid bathing their surfaces, it has been shown that the movement of potassium ions from the bathing medium to the extra-axonal fluid, following an increase in the external concentration of this cation, involves an appreciable degree of restriction. This effect is associated with an extracellular diffusion potential, which appears to result from the more rapid penetration of potassium relative to the outward diffusion of sodium ions from the extracellular system. It is suggested that the restriction of intercellular diffusion may occur in the region containing tight junctions and separate desmosomes at the inner end of the intercellular clefts which traverse the perineurium. If the connectives are stretched during mounting, a more rapid depolarization of the giant axons is observed. Comparison of the calculated and the experimentally observed half-times for diffusion of potassium ions to the axon surface indicates that in these preparations the rate of movement of inorganic ions from the external medium is largely determined by the extended intercellular diffusion pathway represented by the mesaxon cleft. In de-sheathed preparations penetration of potassium ions is still more rapid, an effect which is postulated to result from damage to the perineurium, and the consequent production of a shorter, intracellular diffusion channel through the glial system.
Central Control of An Insect Sensory Interneurone
Authors: McKAY J. M. 
Published: April 2021

ABSTRACT
The T fibre habituates little to a series of sine-wave pulses, and recovery is complete within 10 min. Both response level and rate of habituation are increased when the posterior thoracic ganglia are disconnected from the prothoracic ganglion. This indicates that response level and rate of habituation are maintained at a low level in the intact animal by an inhibitory input or inputs to the prothoracic ganglion, which arise within the pterothorax. These inputs are entirely central in origin, and are independent of extratympanal sensory input. The function of the posterior branch of the T fibre to the posterior thorax may be to initiate a feedback loop which is completed by the input from the posterior thorax. It is suggested that such feedback stabilization of the response level would reduce loss of directional information at high stimulus amplitude, preserve discrimination at high stimulus repetition rates and reduce habituation. The implications of these findings for a warning neurone system are discussed.
Host Discrimination in A Gregarious Parasitoid Nasonia Vitripennis (Walker) (Hymenoptera: Pteromalidae)
Authors: King P. E. , Rafai Jamal 
Published: April 2021

ABSTRACT
Females of Nasonia vitripennis cannot distinguish newly parasitized hosts from unparasitized ones but after 60 hr parasitization the parasitized puparia are rejected as oviposition sites. The sheath and stylets of the ovipositor have nerves passing down their canals leading to several types of receptor at the tip of the ovipositor shaft. Differences are detectable in the chemical composition of host haemolymph after 3 days parasitization as compared with the unparasitized condition. These may be the factors bringing about discrimination.
Effects of Sub-Lethal High Temperature On an Insect, Rhodnius Prolixus (Stål.)
Authors: Okasha A. Y. K. , Hassanein A. M. M. , Farahat A. Z. 
Published: April 2021

ABSTRACT
Heat-treatment of Rhodnius adults for 14 or 15 days before feeding may either inhibit egg production during the first reproductive cycle at normal temperature, or cause a great reduction in the number of eggs deposited. In the latter case, oviposition is long delayed. During the subsequent cycles commencement of oviposition and egg production seem to be normal. If heat-treatment is performed immediately after feeding for a similar period, subsequent egg production at normal temperature is apparently not affected, while oviposition is slightly delayed. During subsequent cycles, however, the reproductive activity of the females is not markedly different from normal. The majority of eggs produced under either type of treatment show progressive sterility over a period covering four reproductive cycles. Allowing heat-treated females to copulate with freshly fed normal males results in a great increase in the fertility of the eggs produced. Egg-production, however, does not seem to be affected. The significance of these results is discussed.
Water Relations of the Desert Scorpion, Hadrurus Arizonensis
Authors: Hadley Neil F. 
Published: April 2021

ABSTRACT
Total water-loss rates for Hadrurus arizonensis (0·028% wt/h at 30°C in dry air) are comparable to rates for Old World species and are well below rates for other desert arthropods under similar conditions. Cuticular and respiratory transpiration constitute the two major avenues of water loss, cuticular water loss predominating at temperatures up to approximately 38°C and respiratory transpiration predominating at temperatures above 40°C. The cuticular transpiration/temperature curve exhibits a two-plateau configuration with abrupt increases in cuticular permeability occurring between 35 and 40°C and between 65 and 70°C. Cuticular water-loss values in dead scorpions exceed those of total water loss in living scorpions. The increased cuticular permeability after death is interpreted as evidence for the existence of an active cuticular water-retaining mechanism. Water-loss rates are significantly reduced at lower saturation deficits; however, scorpions are unable to absorb significant quantities of water from near-saturated atmospheres or moist substrates, regardless of their hydration state. The importance of water conserving versus water regaining mechanisms are discussed in relation to the total adaptations of these animals to hot, dry environments.
Calcium Spike in the Longitudinal Muscle of the Lobworm, Tylorrynchus Heterochaetus, (Nereidae)
Authors: Ito Y. , Tashiro N. 
Published: April 2021

ABSTRACT
The mechanical and electrical activities of the longitudinal somatic muscle of the nereid Tylorrynchus heterochaetus were studied by intra-and extracellular stimulating methods. The contraction elicited by electrical stimulation under isometric conditions consisted of two components, i.e. early phasic contraction and sustained contraction. The sustained contraction lasted more than 1 min after the cessation of the tetanic stimulation. The membrane potential was 62·8 mV, and spontaneous discharges with overshoot (mean 18 mV) were recorded. A similar amplitude of the spike could be recorded by the intra-cellular polarizing method. The maximum slope of the membrane potential change against a tenfold change in [K]o was 39 mV in the presence of Na+ and 48 mV in the absence of Na+. The membrane was hyperpolarized by reduction of [Na]o but not by reduction of [Cl]o. Tetrodotoxin (10−5 g/ml) blocked neither spontaneous spike generation nor spikes evoked by electrical stimulation. The spike amplitude (overshoot) was proportionally increased with increased [Ca]o in the absence of Na+. The electrical threshold and the membrane potential remained the same in the ranges of 2 and 200 mM [Ca]o in the absence of Na+. Sr2+ and Ba2+ could produce spike generation in the absence of Na+ and Ca2+. Prolongation of the spike (plateau) was observed when 20 mM Ba2+ was added to the solution containing no Na2+ and Ca2+. The electrical and mechanical properties of the muscle were discussed in comparison with those observed of the longitudinal muscle of the earthworm.
Activity Patterns and Energetics of the Moth, Hyalophora Cecropia
Authors: Hanegan James L. , Heath James Edward 
Published: April 2021

ABSTRACT
The time of activity and the duration of active periods (flight) of moths of the species Hyalophora cecropia has been determined by monitoring thoracic temperature. The metabolic cost of flight per day and per adult life has been determined directly by measuring O2 consumption and indirectly by analysis of cooling curves of individual moths. An energy balance sheet has been derived which gives the metabolic cost of flight and maintenance (during torpor) over the insect’ s adult life. The metabolic stores mobilized for daily activity appear to be fixed and independent of air temperature. This mobilization of fat stores may be under hormonal control. It is metabolically more expensive for moths to be active at low air temperatures. The number and duration of active periods at low air temperatures is reduced, but, the metabolic expenditure for activity is equal to that of animals held at higher air temperatures. Females have a smaller total energy reserve than males. The number of active periods per day is not significantly different between the sexes at any given temperature, but in females the active periods are significantly shorter in duration. The flight speed has been determined, and estimates of the flight range per day and per adult life have been calculated. The ecology of H. cecropia has been discussed with respect to the timing and duration of active periods, the range and speed of flight, and the energetic cost of flight and maintenance metabolism.
Do the Monoamines in Crab Pericardial Organs Play A Role in Peptide Neurosecretion?
Authors: Berlind A. , Cooke I. M. , Goldstone Martha W. 
Published: April 2021

ABSTRACT
Pericardial organs of Libinia emarginata and L. dubia were isolated, the nerves from the thoracic ganglion were stimulated electrically, and propagated electrical activity was recorded. Fluid which bathed the neurohaemal organ was assayed for cardio-excitor effects on the isolated crab heart, when necessary, made tachyphylactic to drugs. Neither 10−6 M 5-hydroxytryptamine (5-HT), 10−6 M dopamine (DA), nor 10−5 M UML applied directly to the pericardial organ evoke release, nor do DA or UML alter release in response to stimulation. The rate of cardio-excitor release is normal in pericardial organs taken from reserpinized animals. Histochemical examination of the pericardial organs by the formaldehyde-induced fluorescence method confirmed depletion of the monoamines. These experiments, taken together, provide strong evidence against a role of monoamines in the release of cardio-excitor hormone from this neurosecretory structure.
The Mechanism of Burrowing of the Mole Crab, Emerita
Authors: Trueman E. R. 
Published: April 2021

ABSTRACT
The mechanism used by the mole crab Emerita for burial in sand has been studied by the analysis of cine film and electronic recordings. Digging is initiated by tactile stimulation of the base of the telson and is carried out by the fourth thoracic legs and uropods continuously excavating a cavity in the substrate. The crab moves into this in a series of steps by the action of the first three pairs of legs. These limbs function in the manner of oars, being feathered during the recovery stroke. The efficiency of locomotion and the power required for burial are determined.
The Involvement of Sodium Transport in the Volume Regulation of the Amphipod Crustacean, Gammarus Duebeni
Authors: Lockwood A. P. M. 
Published: April 2021

ABSTRACT
The effect on sodium influx of reduction in the fluid volume of the amphipod Gammarus duebeni has been investigated. Removal of water and sodium by exposure to isotonic sucrose or mannitol results in no significant change in blood concentration but is followed subsequently by a marked increase in sodium influx. The increased influx is due, at least in part, to increased active uptake of sodium. Physical removal of blood by pipette stimulates a greater degree of increased uptake in some individuals by comparison with the controls. For technical reasons the increases as measured are smaller than in §2 above and in some individuals there is no response. When the blood concentration is caused to rise at the same time as body volume is reduced there is subsequent decrease in sodium influx. It is concluded that a mechanism is present which initiates an increase in sodium uptake on reduction of blood volume. This mechanism may be of value in replacing fluid loss resulting from haemorrhage, if water uptake accompanies sodium uptake. The evolutionary significance of such a mechanism is discussed in relation to development of active transport mechanisms in present-day freshwater and brackish-water forms.
Water Flow and Gas Exchange at the Gills of Rainbow Trout, Salmo Gairdneri
Authors: Davis John C. , Cameron James N. 
Published: April 2021

ABSTRACT
Ventilation volume was measured directly in rainbow trout using a rubber membrane attached to the mouth which separated inspired and expired water and allowed collection of the latter. Mean ventilation volume at 8·6°C for 18 trout weighing approximately 200 g was 37±1·8 ml/min/fish. Mean ventilation rate and ventilatory stroke volume averaged 74 breaths/min and 0·5 ml/breath respectively. Ventilation volume could be increased nearly sevenfold during moderate, shortterm hypoxia as a result of a large increase in ventilatory stroke volume and a small increase in ventilation rate. The ratio between the flow rates of water and blood through the gills was approximately 10. Percentage utilization of oxygen from inspired water had a mean of 46 ± 1·5% and ranged from 23 to 64%. Artificial perfusion of the gills with water at different flow rates was achieved by tying a tube into the mouth of trout. Perfused fish could not saturate their arterial blood with oxygen at a perfusion rate of 45 ml/min but could do so at rates ranging from 85 to 1200 ml/min. Low arterial tensions at a perfusion rate approximating the mean of fish with oral membranes are probably the result of a poor pattern of water flow over the gills during perfusion. Opercular movements occurred only at perfusion rates below 700 ml/min and increased in frequency as perfusion rate dropped. This ventilatory activity may have resulted from receptors sensitive either to water flow over the gills or to arterial . As perfusion rate went up cardiac output and oxygen uptake increased. These changes were accompanied by a drop in dorsal aortic pressure which reflected vasodilation of the gills and peripheral circulation. This change in the pattern of blood flow through the gills contributed to a 50% increase in oxygen transfer factor across the gills. At the highest perfusion rates there was no apparent impairment of gas exchange even though anatomical deadspace was probably high.
Bird Respiration: Flow Patterns in the Duck Lung
Authors: Bretz William L. , Schmidt-Nielsen Knut 
Published: April 2021

ABSTRACT
A heated thermistor probe was designed to determine the direction of air flow in the respiratory system of birds. The probes did not significantly affect the respiratory rates, tidal volumes, or body temperatures of birds implanted with the probes as compared to unimplanted birds. Air-flow directions were determined in the primary bronchus, the craniomedial secondary bronchi, and the caudodorsal secondary bronchi in the lungs of ducks which were either unanaesthetized and at rest, anaesthetized, or panting due to heat load. The recorded air-flow directions suggested the following patterns of air flow in the duck lung for resting respiration. During inspiration air flows to the posterior air sacs directly from the primary bronchus (the most direct route), without passing through the tertiary bronchi, while air flows towards the anterior air sacs via the caudodorsal secondary bronchi and the tertiary bronchi (thus by-passing the most direct route, the craniomedial secondary bronchi connecting these sacs to the primary bronchus). During expiration air flows from the anterior sacs to the primary bronchus via the craniomedial secondary bronchi (the most direct route), but from the posterior sacs through the tertiary bronchi and through branches of the craniomedial secondary bronchi to the primary bronchus (by-passing the most direct route, the portion of the mesobronchus posterior to the craniomedial bronchi). The patterns established for panting and anaesthetized respiration were very similar to those described for resting respiration. There was no indication of an effective shunt operating during panting to avoid excessive ventilation of the exchange surfaces of the lung. Flow in the tertiary bronchi appeared to be in the same direction during both inspiration and expiration (from the caudodorsal secondary bronchi towards the craniomedial secondary bronchi). Such unidirectional flow would permit the operation of a counter-current exchange system, provided that the blood vessels are arranged appropriately around the parabronchi.
Orientation by Jumping Spiders in the Absence of Visual Feedback
Authors: Land M. F. 
Published: April 2021

ABSTRACT
Jumping spiders turn to face moving objects. These turns are mediated by the lateral eyes. They can be accomplished accurately whether or not the spider sees the relative movement of the stimulus across the retinae which would normally result from such a turn. The spider’s response to an adequate stimulus may be: (i) to make a ‘complete’ turn resulting in fixation by the antero-median eyes; (ii) to make a ‘partial’ turn of 10–20°, whose magnitude is independent of stimulus position, and which does not result in fixation, or (iii) to ignore it. To be seen, a stimulus must subtend more than 0–7° (slightly less than the distance between receptors) and must move through a minimum angle of about i°. The probability of a turn being made is greatest for stimuli 40–90° from the spider’s front, and decreases to a low value for stimuli behind the animal, and immediately in front of it. Repeated presentation of a stimulus to one part of the retina results in a rapid decrease to zero of the probability of a turn being made, but turns can still be evoked by moving the stimulus a few degrees to a previously unstimulated part of the retina. Habituation does not affect the sizes of the few turns that are made. Dishabituation can be caused by mechanical stimulation, or it may occur spontaneously. The fields of view of the lateral eyes have been measured in the horizontal plane by blinding each eye and determining the parts of the visual field from which turns could not be evoked. Three kinds of response mediated by the lateral eyes, in addition to turns towards the stimulus, are described.
Temperature Regulation of the Sphinx Moth, Manduca Sexta
Authors: Heinrich Bernd 
Published: April 2021

ABSTRACT
The sphinx moth, Manduca sexta, maintained an average thoracic temperature of 40–42°C during free flight in ambient temperatures (TA) of about 16·33°C. In the extremes, the excess of thoracic temperature TTh over TA varied from a mean of 25°C at 12·5°C, to a mean of 8°C at a TA of 35°C. During tethered flight TTh increased directly with TA, and the excess of TTh over TA varied from about 11-4°C. The oxygen consumption was about 45-50 c.c. Oa/g h during free flight from ambient temperatures of 15 –30°C. During captive flight the oxygen consumption was about 21 c.c. O2/g h. The wing-beat frequency and amplitude during both free flight and captive flight did not vary significantly with TA. The wing-beat frequency was about the same during free flight and captive flight but the wing-beat amplitude was significantly less in the latter. The moths showed little variation of flight speed with respect to TA on the flight mill. The difference between TTh and TA was strongly correlated with flight speed at low, but not at high, TA. The cooling rate of dead moths was only slightly correlated with air speeds from 2 to 5 m/s. The cooling rate of thoraces without scales was 2·4 times as great as with scales intact at an air flow 2 m/s, but the cooling rate of the abdomen was only slightly increased after the removal of its scales. The data suggest that the rate of metabolism during flight is altered with regard to the flight effort, but not with regard to temperature-regulation. Heat is actively dissipated from the thorax during flight at high TA, or during fast flight when TTh reaches 40°C or above.
Temperature Regulation of the Sphinx Moth, Manduca Sexta: II. Regulation of Heat Loss by Control of Blood Circulation
Authors: Heinrich Bernd 
Published: April 2021

ABSTRACT
The circulatory anatomy of Manduca sexta is such that heat loss from the thorax is minimized when the flow of blood is reduced, and maximized when it is increased. Abdominal temperatures immediately after flight suggested that blood flow was substantially increased during flight at high TA, and greatly reduced during flight at low TA. When the thorax was artificially heated, the pulsation rates of the abdominal blood vessel increased, the amplitudes-of the pulsations became large, and the pulsations were always in the posterior-anterior direction. Heating of the abdomen often resulted in the constriction of the abdominal vessel and a reduction in the amplitude of the pulsations. Transection of the ventral nerve cord reduced the frequency of the high-amplitude pulsations and abolished the ability of the abdominal heart to respond to thoracic heating. When the heat was applied to the thorax, but not to the abdomen: (a) TTh increased while remained near TA, (b) TAb then increased while TTh stabilized near 40–42°C; (c) finally, if the heat input was not excessive, TAb also stabilized at a temperature above TA. Neither stabilization of TTh nor increase of TAb were observed during thoracic heating of dead moths or those with transected nerve chords. The distribution of temperature observed in the abdomen during thoracic heating is not explicable in terms of heating by conduction from the thorax. During modest thoracic heating, decreases of TTh were correlated with intervals during which there were full-length pulsations of the dorsal vessel. During periods where movement of the vessel was observed only at the anterior end of the abdomen, the temperature of the thorax increased. Calculations of blood flow and heat flux indicate that the regulation of TTh in the observed range is physically reasonable by blood circulation alone.
Evidence for Na+/H+ and Cl−/HCO3− Exchanges During Independent Sodium and Chloride Uptake by the Larva of the Mosquito Aedes Aegypti (L.)
Authors: Stobbart R. H. 
Published: April 2021

ABSTRACT
Ionic movements into and out of the starved salt-depleted fourth instar larvae of Aëdes aegypti have been studied during independent uptake of Na+ and Cl−. About 33% of the Na+ taken up from Na2SO4 is balanced electrically by a loss of K+, about 49% is exchanged for H+, and about 17·5% is accompanied by SO4−2. About 36% of the Cl− taken up from KCl is presumably balanced electrically by a loss of unknown and possibly organic ions, about 41% is exchanged for HCO3− (and possibly OH−) and about 23% is accompanied by K+.
Calcium Regulation in the Freshwater Mollusc, Limnaea Stagnalis (L.) (Gastropoda: Pulmonata)
Authors: Greenaway Peter 
Published: April 2021

ABSTRACT
Calcium regulation in normal and calcium-depleted snails has been investigated. L. stagnalis has an uptake mechanism with a high affinity for calcium ions and shows a positive calcium balance in media containing more than 0·062 mM Ca/l. Influx and net uptake of calcium are related to external calcium concentration in a non-linear manner. The uptake mechanism is half-saturated and near-saturated in external media containing 0·3 and 1·0–1·5 mM Ca/l respectively. Calcium uptake from external concentrations of less than 0·5 mM Ca/l is against a small electrochemical gradient whereas from external concentrations greater than 0·5 mM Ca/l there is no adverse gradient. Calcium depletion does not significantly alter the normal influx or net uptake rate of calcium from 1·o mM Ca/l. The calcium concentration in the blood remains constant during net uptake from, and net loss to, the medium. A comparison is made between the mechanisms of sodium regulation and calcium regulation in L. stagnalis.