bluuebunny/crossref_metadata_2025 huggingface dataset:
Hormonal control of integumentary water-loss: evidence for a novel neuroendocrine system in an insect (Periplaneta americana
Authors: Treherne J. E. , Willmer P. G.
Published: April 2021

An accelerated water-loss was observed in decapitated individuals, no equivalent increase being obtained following severance of the nervous connectives in the neck. Injection of brain and, to a lesser extent, corpus cardia-cum extract resulted in a significant reduction in the rate of loss of water from decapitated individuals. The accelerated water-loss observed following decapitation appeared not to result from significant increase in excretory output or loss of water through the spiracles. It is suggested that integumentary transpiration may be affected by a blood-borne factor, or factors, which originate in the brain and corpus cardiacum.
Peripheral specialization for fine analysis of doppler-shifted echoes in the auditory system of the ‘CF-FM’ bat Pteronotus parnellii
Authors: Suga N. , Simmons J. A. , Jen P. H.-S.
Published: April 2021

Pteronotus parnellii uses the second harmonic (61–62 kHz) of the CF component in its orientation sounds for Doppler-shift compensation. The bat’s inner ear is mechanically specialized for fine analysis of sounds at about 61-62 kHz. Because of this specialization, cochlear microphonics (CM) evoked by 61–62 kHz tone bursts exhibit prominent transients, slow increase and decrease in amplitude at the onset and cessation of these stimuli. CM-responses to 60–61 kHz tone bursts show a prominent inputoutput non-linearity and transients. Accordingly, a summated response of primary auditory neurones (N1) appears not only at the onset of the stimuli, but also at the cessation. N1-off is sharply tuned at 60–61 kHz, while N1-on is tuned at 63–64 kHz, which is 2 kHz higher than the best frequency of the auditory system because of the envelope-distortion originating from sharp mechanical tuning. Single peripheral neurones sensitive to 61–62 kHz sounds have an unusually sharp tuning curve and show phase-locked responses to beats of up to 3 kHz. Information about the frequencies of Doppler-shifted echoes is thus coded by a set of sharply tuned neurones and also discharges phase-locked to beats. Neurones with a best frequency between 55 and 64 kHz show not only tonic on-responses but also off-responses which are apparently related to the mechanical off-transient occuring in the inner ear and not to a rebound from neural inhibition.
Central control of feeding in the diapausing adult blowfly Phormia regina
Authors: Stoffolano J. G.
Published: April 2021

The tarsal acceptance threshold of non-diapausing adult blowflies rises with age. Diapausing flies have a non-significantly elevated tarsal acceptance threshold, but drink significantly less sucrose solution than their non-diapausing counterparts. Removal of diapausing flies to non-diapause inducing conditions resulted in a lowering of the threshold. Failure to demonstrate a significant difference between the input signal from the peripheral receptors of non-diapausing and diapausing flies showed that the inhibition of feeding in diapausing flies was not due to peripheral inhibition but was controlled centrally.
Metabolism during flight in two species of bats, Phyllostomus hastatus and Pteropus gouldii
Authors: Thomas S. P.
Published: April 2021

The energetic cost of flight in a wind-tunnel was measured at various combinations of speed and flight angle from two species of bats whose body masses differ by almost an order of magnitude. The highest mean metabolic rate per unit body mass measured from P. hastatus (mean body mass, 0·093 kg) was 130·4 W kg−1, and that for P. gouldii (mean body mass, 0·78 kg) was 69·6 W kg−1. These highest metabolic rates, recorded from flying bats, are essentially the same as those predicted for flying birds of the same body masses, but are from 2·5 to 3·0 times greater than the highest metabolic rates of which similar-size exercising terrestrial mammals appear capable. The lowest mean rate of energy utilization per unit body mass P. hastatus required to sustain level flight was 94·2 W kg−1 and that for P. gouldii was 53·4 W kg−1. These data from flying bats together with comparable data for flying birds all fall along a straight line when plotted on double logarithmic coordinates as a function of body mass. Such data show that even the lowest metabolic requirements of bats and birds during level flight are about twice the highest metabolic capabilities of similar-size terrestrial mammals. Flying bats share with flying birds the ability to move substantially greater distance per unit energy consumed than walking or running mammals. Calculations show that P. hastatus requires only one-sixth the energy to cover a given distance as does the same-size terrestrial mammal, while P. gouldii requires one-fourth the energy of the same-size terrestrial mammal. An empirically derived equation is presented which enables one to make estimates of the metabolic rates of bats and birds during level flight in nature from body mass data alone. Metabolic data obtained in this study are compared with predictions calculated from an avian flight theory.
The energetics of the jump of the locust Schistocerca gregaria
Authors: Bennet-Clark H. C.
Published: April 2021

The anatomy of the metathoracic leg is redescribed with particular reference to storage of energy in cuticular elements and the way in which the stored energy is used in jumping.

The jump of adult male locusts requires an energy of 9 mJ and that of the female requires 11 mJ. The semilunar processes of each metafemur store 4 mJ at a stress of 15 N, and the extensor tibiae apodeme stores a further 3 mJ at the same stress. The total stored energy in both metathoracic legs is 14 mJ.

The extensor tibiae muscle produces a maximum isometric force of over 15 N at 30°C and, when loaded with the extensor apodeme and semilunar processes, attains this force in 0·3 sec with a strain of 0·8 mm. The peak power output is 36 mW or 0·45 W.g−1. The peak isometric force is attained when the tibia is fully flexed and the force falls as the tibia extends. The extensor tibiae muscle A band is 5·5 μm long and the peak force is over 0·75 N.m−2. The peak velocity of shortening is 7 mm.sec−1 or about 1·75 lengths/sec at 30°C.

The tensile strength of the extensor apodeme is 0·6 kN. mm−2 and Young’s modulus is 19 kN.mm−2. The safety factor does not exceed 1·2 and the safety factor of the semilunar processes and tibial cuticle is little higher.

The jump impulse lasts 25–30 msec. A velocity of 3·2 m.sec−1 is reached after a peak acceleration of 180 m.sec−2. The peak power output is 0·75 W at close to maximum velocity. Energy losses in rotating the femur and tibia are small and it is shown that the leg is able to extend at 7 times the normal rate with losses of about 20 %. Most of the stored energy is converted to kinetic energy as the animal jumps.

A model based on the relaxation of a spring that has the properties of the elastic elements of the locust leg into a lever with the same kinematics as the locust leg produces a force-distance curve similar to that measured for locust jumps. The major part of the jump energy is stored before the jump.
The effect of hypophysectomy and prolactin therapy on water balance of the brown trout Salmo trutta
Authors: Oduleye S. O.
Published: April 2021

A technique for the hypophysectomy of the brown trout is described which might be applicable to other salmonids. Hypophysectomy produced a decrease in water turnover which was corrected by prolactin therapy.

Hypophysectomy resulted in a decrease in the net flux of osmotic water. Both osmotic and diffusional water permeabilities were evenly decreased after hypophysectomy, such that the ratio of the osmotic and diffusional permeability coefficients (Pos/Pd) retained a value of approximately unity.

The data suggest that calcium and prolactin have opposing actions on water balance and that their modes of action are likely to separate.
Acceleration Performance of Rainbow Trout Salmo Gairdneri and Green Sunfish Lepomis Cyanellus
Authors: Webb P. W.
Published: April 2021

High unsteady (acceleration) performance of rainbow trout (L = 14.3 cm) and green sunfish (L = 8.0 cm) was studied in response to electric shock stimulus. Acceleration movements were divisible into a preparatory stage 1 and a main propulsive stage 2. Locomotory behaviour varied between faststarts and turning manoeuvres.

Taking the centre of mass for the stretched straight body as the reference point, distance covered with time was described by the equation;

The mean value of b was 1.60 for trout and 1.71 for sunfish. The overall mean distance covered and time to the end of stage 2 was 5.36 cm in 0.078 sec for trout and 2.85 cm in 0.079 sec for sunfish. Velocity increased curvilinearly with time. Maximum values of 20 L/sec were observed, but overall mean values at the end of stage 2 were 8.5 L/sec for trout and 8.3 L/sec for sunfish. Acceleration rate was not uniform but decreased with time. Mean maximum values were calculated of 42 m/s2 for trout and 16 m/s2 for sunfish, but overall mean values for an acceleration movement were 13 m/s2 and 8 m/s2 for the two species respectively.

The observed acceleration behaviour is more advantageous than uniform acceleration because a greater distance is covered and greater velocities acquired in a shorter time, while the increased energetic cost is only 2–3 % of the total energy expended.
Water flow dynamics in the respiratory tract of the carp (Cyprinus carpio L.)
Authors: Holeton G. F. , Jones D. R.
Published: April 2021

Simultaneous measurements of water velocity in the buccal chamber, and buccal and opercular hydrostatic pressure of carp have revealed surprisingly high water velocities. The high flow velocities mean that, at times, the kinetic energy of flow makes a substantial contribution to the total fluid energy. This suggests that there may be unequal distribution of hydrostatic pressures within the buccal chamber. Anatomical examinations showed that fluid channels in the buccal chamber and gill raker sieve are complex and can be expected to vary spatially and temporally throughout the respiratory cycle. It appears that there is a potential for error in many of the previous analyses of ‘gill resistance’ and energetics of fish breathing based solely on hydrostatic pressure measurements and the simplifying assumption of steady-state conditions.
Reflex modulation of motoneurone activity in the cheliped of the crayfish Astacus leptodactylus
Authors: Vedel J. P. , Angaut-Petit D. , Clarac F.
Published: April 2021

The reflex activity elicited by movement of the mero-carpopodite (M-C) joint in the cheliped of the crayfish Astacus leptodactylus is investigated and the role of the different proprioceptors (chordotonal and myochordotonal organs) separately studied. The reflex discharge involves mainly the tonic motoneurones of the extensor (E), the flexor (F) and the accessory flexor (AF) muscles. M-C joint posture is also regulated by the cuticular stress detector (CSD2) afferents: they increase mainly the F discharge and secondarily the AF command. The activity of the motor axons supplying the muscles of the meropodite can be also influenced by a variety of natural stimuli applied to other appendages. The effect usually produced is a general flexion reaction which is characterized by a reciprocity between E and F involving both central and peripheral mechanisms. The AF muscle is innervated by two antagonistic motoneurones, an excitatory neurone functionally linked in its discharge with one of the four excitors supplying F and an inhibitory motoneurone, common with E. The resulting competitive effect between these two neurones has been recorded intracellularly in AF muscle fibres. The role of the myochordotonal organ (MCO) in the crayfish is discussed. In particular the modulation of the AF command in relation to the discharges of the motor nerves to the main muscle E and F is studied.
Allometry of post-flight cooling rates in moths: a comparison with vertebrate homeotherms
Authors: Bartholomew G. A. , Epting R. J.
Published: April 2021

The rates of post-flight cooling in 25 saturniid moths of 8 genera ranging in weight from 81 to 2650 mg were measured and compared with cooling rates in sphingids, birds and mammals. The initial and terminal cooling rates of the saturniids did not differ significantly. Large saturniids have relatively smaller thoraxes than small ones. In saturniids the rate of post-flight cooling is inversely related both to thoracic volume and total weight. Cooling rate is less dependent on thoracic volume in saturniids than in sphingids. Weight-specific conductance calculated on the basis of total weight, shows that moths are not as well insulated as birds or mammals. However, when considered on the basis of thoracic weight, the weight-specific conductance of saturniids and sphingids closely approximates that predicted by the regression of weight-specific conductance on total body weight in birds and mammals. Since the insulation of saturniids and sphingids is no more effective for animals of their size than is that of birds and mammals, their high body temperatures during activity appear to depend primarily on high levels of heat production.
Pursuit and prediction in the tracking of moving food by a teleost fish (Acanthaluteres spilomelanurus)
Authors: Lanchester B. S. , Mark R. F.
Published: April 2021

The path, eye and body movements of a teleost fish (the leatherjacket Acanthaluteres spilomelanurus) approaching and taking food were measured by cinematography. Fixation of the food by movement of the eyes is an invariable feature of the approach. The eyes then remain aligned with the target while the body moves forward and round to bring the mouth to the food. When pursuing pieces of food moving vertically at constant velocity through the water these fish normally trace out the pathway that can be calculated by assuming the fish aims constantly at the food. Predictive pathways that imply anticipation of the point of intersection with the food are not regularly seen. Deviations from pursuit occur sporadically, usually in the direction of a predictive path, particularly when the fish approach falling food from below. The geometry of the situation suggests that predictive paths may sometimes be generated if the alignment of eye and body during the pursuit of moving food can be delayed. In approaches from below this may be because forward movement of the fish would tend to stabilize the image of the falling food in the retina. We suggest that a simple linked control system using both eye and body movements to fixate retinal images will on occasions generate predictive pathways without any need for the central nervous system to calculate them in advance.
Blood oxygen transport and metabolism of the confined lugworm Arenicola marina (L.)
Authors: Toulmond A.
Published: April 2021

Oxygen consumption , haemoglobin oxygen saturation level and pH in prebranchial blood were measured in lugworms experimentally confined in sea water at 15 ·C. Total blood flow through the gills was estimated. For seawater oxygen partial pressure between 120 and 150 Torr, , and were high and nearly constant. For < 120 Torr, fell quickly, progressively dropped, and metabolism remained aerobic at the expense of the prebranchial blood oxygen store. For < Torr, and values were extremely low, and the low and the modified buffer power of the surrounding sea water showed that anaerobic metabolism was occurring. Changes in respiratory gas exchanges and metabolism during the tidal cycle are deduced from the comparison of these results with data obtained in the field.
Respiration in relation to ion uptake in the crayfish Austropotamobius pallipes (Lereboullet)
Authors: Sutcliffe D. W. , Carrick T. R.
Published: April 2021

O2 uptake was determined for periods of 23–46 h in salt-depleted crayfish held in deionized water (DW) or Na-free media at 10°C. These media were replaced by artificial lakewater media (ALW) containing 0·20–6 mM Na and O2 uptake was again determined for periods of 24–66 h. During net ion uptake in ALW the metabolic rate was either elevated or depressed. Standard metabolism in ALW altered by amounts equivalent to 0·1–15·5% (mean 6·4 (15)14·4% s.D.) of the metabolic rate measured during salt-depletion. On three occasions the metabolic rate was elevated by 22·0–66·7%, but some of this increase may have been due to locomotor activity. The calculated values for thermodynamic work involved in ion transport were 0·056–0·268 J/10 g.h at 10°C, or 1·5–7·2% of the mean standard metabolic rate. Most of the observed changes in metabolic rate lie within the limits of experimental error (ca. ± 7 %). Hence the energetic cost of ion transport is too small for direct measurement in intact crayfish.
Co-ordinating interneurones of the locust which convey two patterns of motor commands: their connexions with flight motoneurones
Authors: Burrows M.
Published: April 2021

Some flight motoneurones receive two superimposed rhythms of depolarizing synaptic potentials when the locust is not flying; a slow rhythm which is invariably linked to the expiratory phase of ventilation, and a fast rhythm with a period of about 50 ms which is similar to the wingbeat period in flight. By recording simultaneously from groups of motoneurones, the synaptic potentials which underly these rhythms have been revealed in 30 flight motoneurones in the three thoracic ganglia. The inputs occur in elevator motoneurones and some depressors but are of lower amplitude in the latter. The inputs have not been found in leg motoneurones. The rhythmic depolarizations are usually subthreshold but sum with sensory inputs to evoke spikes in flight motoneurones at intervals equal to or multiples of the wingbeat period in flight. Both rhythms originate in the metathoracic ganglion and are mediated by the same interneurones. They can be adequately explained by supposing that there are two symmetrical interneurones which each make widespread connexions with left and right flight motoneurones in the three ganglia. The slow rhythm is coded in the overall burst of interneurone spikes during expiration and the fast rhythm in the interval between the spikes of a burst.
NaCl adaptation in Rana ridibunda and a comparison with the euryhaline toad Bufo viridis
Authors: Katz U.
Published: April 2021

The physiological adaptation of the frog Rana ridibunda to saline environment was studied. It was found that blood was always hypertonic to the external solution, but at the highest salinity tolerated (i.e. 300 mOsM) the osmotic gradient across the skin was nearly abolished. Water uptake by the living frog remained unchanged, whereas sodium transport across the skin decreased markedly. Neurohypophyseal hormone increased water uptake and sodium transport to levels similar to those in tap water frogs. Water content of the tissues was not affected by saline adaptation, although it varied appreciably under acute conditions. Oxygen consumption increased in dehydrated frogs, but not in adapted ones. The results are discussed and compared to the euryhaline toad Bufo viridis ; the importance of high urea levels for high salt adaptation is stressed.
An electrophysiological analysis of extra-axonal sodium and potassium concentrations in the central nervous system of the cockroach (Periplaneta americana L.)
Authors: Thomas M. V. , Treherne J. E.
Published: April 2021

Simultaneous intracellular and sucrose-gap recordings showed, in contrast to previous findings, that the electrical parameters of giant axons were similar in intact and desheathed connectives bathed with the ‘extracellular Ringer’ of Yamasaki & Narahashi. This implies that the extra-axonal sodium concentration, in situ, is likely to be lower than had been previously supposed. Axonal responses showed that, despite the high blood concentration of 24·2 mM-K+ measured by flame photometry, the effective concentration in the blood was 10-15 mM-K+ which corresponds to the measurements made with potassium-selective electrodes. The activity of the blood potassium ions caused a marked reduction in the amplitude of the action potentials following surgical desheathing or disruption of the blood-brain barrier with hypertonic urea. It is suggested that a regulatory mechanism exists in the central nervous system which counteracts the effects of the high blood potassium level.
Energetics of swimming of a sea turtle
Authors: Prange H. D.
Published: April 2021

Young (mean mass 735 g) green turtles (Chelonia my das) were able to swim in a water channel at sustained speeds between 0·14 and 0·35 m.s−1. Oxygen consumption at rest was 0·07kg−1. h−1; at maximum swimming speed oxygen consumption was 3–4 times greater than at rest for a given individual. In comparison with other animals of the same body mass the cost of transport for the green turtle (0·186 1 O2.kg−1. km−1) is less than that for flying birds but greater than that for fish. From drag measurements it was calculated that the aerobic efficiency of swimming was between 1 and 10 %; the higher efficiencies were found at the higher swimming speeds. Based upon the drag calculations for young turtles, it is estimated that adult turtles making the round-trip breeding migration between Brazil and Ascension Island (4800 km) would require the equivalent of about 21 % of their body mass in fat stores to account for the energetic cost of swimming.
Insect blood-brain barrier: an electrophysiological investigation of its permeability to the aliphatic alcohols
Authors: Thomas M. V.
Published: April 2021

The anaesthetic effects of the aliphatic alcohols were used to measure their concentration at the neuronal surfaces of the cockroach central nervous system. The results were in most cases fairly closely described by first-order kinetics. The exchange half-times of the lower alcohols were only a few seconds, being little affected by the removal of the nerve sheath. The half-times for the higher alcohols were somewhat longer, and were more significantly reduced by desheathing; these observations were interpreted in terms of a reservoir effect resulting from their higher liposolubility. It was shown that the ionic diffusion barrier in intact nerve cords remained undamaged in the presence of the alcohols.
The pharmacology of an insect ganglion: actions of carbamylcholine and acetylcholine
Authors: Sattelle D. B. , McClay A. S. , Dowson R. J. , Callec J. J.
Published: April 2021

Methods for presenting dose-response data for the ganglionic actions of cholinergic agonists (e.g. carbamylcholine) are compared, using the mannitol-gap technique for electrophysiological recording of synaptic events at the cereal nerve, giant fibre synapse of the sixth abdominal ganglion of the cockroach Periplaneta americana. At concentrations around 10−5M, carbamylcholine has no effect on ganglionic polarization but potentiates the monosynaptic EPSP. At 10−4 M and higher concentrations, ganglionic depolarization is accompanied by a reduction of EPSP. Pretreatment with eserine ( 10−6 M) considerably shifts the dose-response curve for acetylcholine so that synaptic transmission is consistently sensitive to 10−8 M acetylcholine.
The Influence of the Hatching Factor on the Water Uptake of the Second Stage Larva of the Potato Cyst Nematode Heterodera Rostochiensis
Authors: Ellenby C. , Perry R. N.
Published: April 2021

Larvae-containing eggs of the potato cyst nematode were soaked in root diffusate in artificial tap water or in artificial tap water alone. In one experiment, the eggs were still contained in intact cysts; in another experiment they were in a halved cyst. Eggs were ruptured after 0−5 days treatment and the water content of the liberated larvae immediately estimated by interference microscopy. Larvae from treated eggs from both the halved and intact cysts had a higher water content than controls. Larvae liberated from treated eggs from the halved cyst reached their maximum water content after 24 h treatment; those from intact cysts attained the same value after 2 days. The delay, for the intact cyst, is in keeping with the hatching response for intact cysts and supports the view that the results for water content are due to the activity of the hatching factor. Reasons are advanced for the view that the hatching factor may work via a neurosecretory mechanism.
The regulation of haemolymph calcium concentration of the crab Carcinus maenas (L.)
Authors: Greenaway P.
Published: April 2021

After acclimation, Carcinus can maintain calcium balance in dilute (35–100%) but not in low calcium sea water. 71 % of total haemolymph calcium (9·54 ± 0·42 mm) was in ionic form as compared with 90·9 % (9·9 mm) in sea water. On acclimation to dilute sea water the calcium activity of the haemolymph was greater than that of the medium, the difference being maintained by active calcium uptake. Carcinus is highly permeable to Ca2+, influx from sea water being 0·513 ± 0·07 μmoles g−1 h−1 and the time constant for calcium influx 4·3 ± 0·48 h. Calcium space represented ca. 25 % wet body weight independent of body size or salinity of acclimation medium.
Connexions between hair-plate afferents and motoneurones in the cockroach leg
Authors: Pearson K. G. , Wong R. K. , Fourtner C. R.
Published: April 2021

The trochanteral hair-plate afferents in the metathoracic leg of the cockroach, Periplaneta americana, were stimulated electrically and at the same time intracellular recordings were made from either motoneurones, interneurones or afferent terminals within the metathoracic ganglion. Activity in the hair-plate afferents evoked short latency excitatory postsynaptic potentials (EPSPs) in femur extensor motoneurones and inhibitory postsynaptic potentials (IPSPs) in femur flexor motoneurones. The latency of the IPSPs was on average 1·8 ms longer than the latency of the EPSPs. Intracellular recordings from terminal branches of the hair-plate afferents showed that the delay between the peak of the afferent terminal spike and the beginning of the EPSPs is about 0·4 ms. This finding, together with the observations that the amplitude of the EPSPs is increased by the passage of hyperpolarizing current and decreased following high-frequency stimulation, indicates that the EPSPs are evoked via monosynaptic chemical synaptic junctions. The observations of the long latency of the IPSPs, the need for a number of afferents to be simultaneously active for them to be evoked and the occasional variability in latency, all indicate that the IPSPs are evoked via a disynaptic pathway. These findings provide information on the synaptic mechanisms underlying the reflexes from the trochanteral hair plate to femur flexor and extensor motoneurones identified in a previous investigation (Wong & Pearson, 1976).
Cardiovascular dynamics of the chelonia during apnoea and lung ventilation
Authors: Shelton G. , Burggren W.
Published: April 2021

In both Pseudemys and Testudo, blood pressures are identical in all chambers of the ventricle. Systolic pressures are not measurably different in the ventricle and systemic arteries but are 0·5–2·0 cm H2O lower in the pulmonary artery due to the resistance of the pulmonary outflow tract. Diastolic pressures are the same in all systemic arteries but are substantially lower in the pulmonary artery. It is concluded that the systemic and pulmonary circulations are perfused by a single pump during both apnoea and lung ventilation. Flow profiles in pulmonary and systemic arteries are characteristically different. Substantial changes in cardiac output may occur during intermittent breathing and apnoea, especially if there are large fluctuations in heart rate. Pulmonary flow increases during lung ventilation due to vasodilation of the lung vasculature. Systemic flow is also affected though the increase is usually smaller. Any separation in the blood pumped by the single ventricle must be maintained by laminar flow patterns and the composition of the blood in each of the major arteries should reflect their relationship to these patterns.
Activities of antennal and ocellar interneurones in the protocerebrum of the honey-bee
Authors: Suzuki H. , Tateda H. , Kuwabara M.
Published: April 2021

Unit responses to olfactory and mechanical stimuli of the antennae, and illumination of the ocelli, were recorded extracellularly in the protocerebrum of the honey-bee. Bimodal units responded both to antennal and to ocellar stimuli; antennal units responded to the former and the ocellar units to the latter. Some antennal units responded to olfactory stimuli (olfactory units), and others responded to mechanical stimuli (mechanical units). Ocellar units in the brain showed phasic responses at the start and/or cessation of illumination. Six types of responses were found. About two-thirds of the bimodal units showed the same type of response to stimulation of the antennae as to stimulation of the ocelli. Most of them showed excitation by each stimulus. 5. Bimodal units were distributed around the a-lobe in the protocerebral lobe, whereas the antennal and the ocellar units were widely distributed. By turning off the ocellar illumination, background discharge frequency, and the pattern and magnitude of responses to antennal stimuli, were changed. The activities of the ocellar units were altered by inputs from the antenna. It was postulated that antennal and ocellar inputs converge and interact with each other in the protocerebral lobe of the honey-bee.
Control of shell settling in the swimming sea anemone Stomphia coccinea
Authors: Lawn I. D. , McFarlane I. D.
Published: April 2021

Electrical activity has been recorded from Stomphia coccinea during the behavioural sequence in which the detached anemone settles on to a Modiolus shell. When a responsive tentacle contacts the shell, a short, complex burst of pulses is elicited. These remain confined to the region of contact. The endodermal slow-conduction system (SS2) then begins to fire repetitively (a typical example is 16 SS2 pulses at a mean interpulse interval of 5 s) until the pedal disc begins to inflate. Shell-tentacle contact is essential for stimulation of SS2 activity. The complete response, apart from local bending of the column, may be reproduced by electrical stimulation of the SS2 alone. As few as 10 stimuli at frequencies between 1 shock/s and 1 shock/10 s are required to elicit the response.
The different actions of chloride and potassium on postsynaptic inhibition of an isolated neurone
Authors: Meyer H.
Published: April 2021

Isolated stretch receptor neurones from freshwater crayfish were examined in solutions containing different concentrations of chloride and potassium. In normal solution the inhibitory reversal potential (EIPSP) of this preparation was strictly negative with respect to the resting potential and even to the reversal potential of spike after-hyperpolarization. The time courses of resting potential and EIPSP following rapid solution change suggest that the current generating the IPSP is mainly carried by chloride ions and that the participation of potassium is very small. This has also been confirmed by the calculated conductances of the activated inhibitory membrane in the different solutions. The results add further evidence for an outwardly directed pumping of chloride ions which keeps the intracellular concentration of this anion at the low level necessary for hyperpolarizing inhibition.
On the interaction of NH4+ and Na+ fluxes in the isolated trout gill
Authors: Kerstetter T. H. , Keeler M.
Published: April 2021

Sodium influx was measured in isolated, previously perfused gill arches of rainbow trout, Salmo gairdneri, by measuring incorporation of 22Na into gill tissue following timed exposure to a 1 mm22NaCl medium. Transport rates approximated those estimated for intact fish and were linear for at least one min. NH4Cl-containing perfusates at pH 7 and 8 stimulated Na+ influx equally, indicating that only ionized ammonia is important in the transport process. A Na+/NH4+ exchange at basal and/or lateral membranes of the transporting cells is suggested. Low-sodium Ringer perfusate augmented Na+ influx; in one group of gills the transport rate was more than double that of NaCl Ringer controls. The increase in transport induced by internal NH4+ was not additive with the low sodium augmentation. A reduction in intracellular [Na+] is postulated as the mechanism operating in both cases. Ouabain had no appreciable effect on Na+ influx, either with or without NH4+ in the perfusate. Diamox partially blocked the augmented Na+ influx induced by NH4+. Amiloride completely inhibited Na+ influx, both with and without NH4+ in the perfusate.
Flight energetics in sphinx moths: heat production and heat loss in Hyles lineata during free flight
Authors: Casey T. M.
Published: April 2021

Mean thoracic temperature of free-flying H. lineata in the field and in the laboratory increased from about 40 °C at Ta= 16 °C to 42·5 °C at Ta = 32°C. At a given Ta, thoracic temperature was independent of body weight and weakly correlated with wing loading. The difference between abdominal temperature and air temperature increased from 2 °C at low Ta to 4·2 °C at high Ta. At a given Ta, the difference between Tab and Ta was positively correlated with thoracic temperature. Oxygen consumption per unit weight did not appear to vary with Ta from 15 to 30 °C and was inversely proportional to body weight. Thermal conductance of the abdomen (Cab) was greater than thermal conductance of the thorax (Cth) in still air and at wind velocities up to 2·5 m/s. In moving air at speeds approximating flight, Cth was twice as high as in still air. Under the same conditions Cab was 3–4 times as high as in still air. Thoracic and abdominal conductance are inversely proportional to their respective weights. These data are consistent with the hypothesis that thoracic temperature is controlled by regulation of heat loss. However, a heat budget derived from these data suggests that heat dissipation may not be sufficient to offset the decrease in passive cooling of the thorax at high ambient temperatures.
The mobilization of calcium and bicarbonate by raised concentrations of potassium in the haemolymph of the snail, Helix pomatia
Authors: Burton R. F. , Jaufeerally F. R.
Published: April 2021

After the concentration of potassium in the haemolymph of Helix pomatia has been raised by the infusion of KCl, it falls approximately exponentially for a time and then tends to rise. The accompanying rise and fall of calcium concentration can be fitted to a simple mathematical model. The mobilization of calcium is accompanied by the generation of bicarbonate in equivalent amounts, without much change in pH or . There is probably an increased production or retention of carbon dioxide at this time, but the main cause of the changes in calcium and bicarbonate is not respiratory acidosis. The concentration of potassium rises in snalis that have been infused with CaCl2. The adverse responses visible in snails infused with KCl are largely prevented when CaCl2 is infused at the same time. Homeostasis seems to involve the maintenance of a proper balance of calcium and potassium concentrations.
Osmotic and ionic regulation in different populations of the new zealand freshwater crayfish Paranephrops zealandicus
Authors: Wong T. M. , Freeman R. F.
Published: April 2021

Some features of the osmoregulatory mechanism are compared in four populations of Paranephrops zealandicus White collected from freshwaters of different ionic concentrations. Crayfish from freshwaters of ca. 2·0 mm-NaCl concentration show a sustained decrease in blood concentration of ca. 8% when placed in 0·2 mm-NaCl. Populations from freshwaters of ca. o·2−0·4 mm-NaCl show lower rates of net salt loss in distilled water and higher rates of net salt uptake from dilute NaCl solutions than do populations from freshwaters of ca. o·8−2·0 mm-NaCl. Renal salt losses over the first 24 h in distilled water account for ca. 18% of the total salt loss. It is suggested that P. zealandicus from environments of lowest concentration shows a similar degree of adaptation to freshwater as do crayfish of the northern hemisphere. It differs in possessing a substantially higher blood concentration.
Evidence for A Synaptically Mediated Decrease in Conductance in A Crustacean Myocardium
Authors: Delaleu J. C.
Published: April 2021

In the neurogenic heart of the isopod Porcellio dilatatus, electrical stimulation of the cardio-regulatory nerves at rates greater than 20-25 pulses/s elicited inhibitory junctional potentials (IJPs) in the myocardium. Its cessation was followed by a long lasting hyperpolarization of the myocardial membrane (post-stimulus hyperpolarization = PSH). During the PSH the membrane resistance of the heart muscle increased. The PSH was enhanced by myocardium hyperpolarization, decreased by depolarization and reversed around −50 mV. Picrotoxin inhibited the summated IJPs elicited by the stimulation and thus caused the membrane to maximally hyperpolarize during the inhibitory train, thus suggesting a composite nature of the inhibitory processes. The PSH was reversibly reduced in K+-free saline or in ouabain containing saline but partial restoration was obtained by injection of inward current to the myocardium. The PSH was abolished in lithium saline and reduced in Na+-deficient (choline) solution. Cl-deficient solution that markedly affected the summated IJPs shortly after its introduction did not affect the PSH. It is proposed that the PSH results from a decrease in conductance, presumably to both Na+ and K+. The implication of such a mechanism as a component of the inhibitory regulation of this crustacean heart is discussed.
Heat Transfer Between Fish and Ambient Water*
Authors: Stevens E. Don , Sutterlin A. M.
Published: April 2021

The ability of fish gills to transfer heat was measured by applying a heat pulse to blood in the ventral aorta and measuring it before and after passing through the gills of a teleost, Hemitripterus americanus. 80–90 % of heat contained in the blood is lost during passage through the gills. The fraction of heat not lost during passage through the gills is due to direct transfer of heat between the afferent and efferent artery within the gill bar. The major fraction of metabolic heat (70–90%) is lost through the body wall and fins of the sea raven in sea water at 5 °C ; the remainder is lost through the gills.
Aerodynamics, Kinematics, and Energetics of Horizontal Flapping Flight in the Long-Eared Bat Plecotus Auritus
Authors: Norberg Ulla M.
Published: April 2021

The kinematics, aerodynamics, and energetics of Plecotus auritus in slow horizontal flight, 2·35 m s−1, are analysed. At this speed the inclination of the stroke path is ca. 58° to the horizontal, the stroke angle ca. 91 °, and the stroke frequency ca. 11·9 Hz. A method, based on steady-state aerodynamic and momenthum theories, is derived to calculate the lift and drag coefficients as averaged over the whole wing and the whole wing-stroke for horizontal flapping flight. This is a further development of Pennycuick’s (1968) and Weis-Fogh’s (1972) expressions for calculating the lift coefficient. The lift coefficient obtained varies between 1·4 and 1·6, the drag coefficient between 0·4 and 1·2, and the lift: drag ratio between 1·2 and 4·0. The corresponding, calculated, total specific mechanical power output of the wing muscles varies between 27·0 and 40·4 W kg−1 body mass. A maximum estimate of mechanical efficiency is 0·26. The aerodynamic efficiency varies between 0·07 and 0·10. The force coefficients, total mechanical power output, and mechanical and aerodynamic efficiencies are all plausible, demonstrating that the slow flapping flight of Plecotus is thus explicable by steady-state aerodynamics. The downstroke is the power stroke for the vertical upward forces and the upstroke for the horizontal forward forces.
An Electrolytic Method for Determining Oxygen Dissociation Curves Using Small Blood Samples: the Effect of Temperature on Trout and Human Blood
Authors: Hughes G. M. , O’Neill J. G. , Van Aardt W. J.
Published: April 2021

A detailed account is given of an electrolytic method for determining the oxygen dissociation curve of fish blood using a single sample of 50–100 μl for the whole curve. The accuracy and some of the problems arising from its uses are discussed. Oxygen dissociation curves have been determined for trout blood and human blood at temperatures of 15 and 37 °C. The relationship between P50 and temperature is similar to that obtained using other methods. Absolute values of P50 are generally lower than those obtained by other methods, especially in the case of fish blood. The effect of and pH on the oxygen dissociation curve of trout blood is tested and it is shown that , has a more marked effect than pH when the other factor is maintained at a constant level. The Bohr factor (Δlog P50/Δ pH) appears to be approximately the same and independent of the . The P50 of ray blood determined from fish during and after an operation showed an increased Bohr factor.
Effects of Calcium on Flagellar Movement in the Trypanosome Crithidia Oncopelti
Authors: Holwill M. E. J. , Mcgregor J. L.
Published: April 2021

The effects of calcium on the motility of different preparations of flagella from Crithidia oncopelti were studied using stroboscopic and high-speed cine photographic techniques. By varying the concentration of calcium in suspensions of chemically treated samples of the organism it was found that changes occurred in bend shape, wave direction and frequency. Waves on the flagellum of the organism in vivo possess the unusual ability to propagate from tip to base, but reverse in direction during an avoiding response. In chemically extracted and reactivated preparations tip to base propagation was observed only at low concentrations ( < 10−4 mol m−3) of calcium ion; at high concentrations base to tip propagation only was seen. In cells treated with ionophores known to carry divalent ions across membranes, tip to base propagation was seen only in the presence of EGTA ; when calcium was added the majority of organisms propagated waves from base to tip. At certain values (ca. 10−3 mol m−3) of the calcium concentration the wave shape had meander-like characteristics, whereas at higher and lower concentrations it was more sinusoidal. At high calcium concentrations only one wave appeared on the flagellum whereas at low values two or three were observed. A reduction in frequency at high calcium concentrations was probably due to competitive inhibition of magnesium ions. The results suggest that wave reversal in living Crithidia is induced by the release of calcium ions within the flagellum following stimulation of the membrane. In terms of the sliding filament model of flagellar activity the effects of calcium suggest that the ion is effective in modifying the interaction between the spoke head and central sheath and may control the relative direction of microtubular sliding.
Role of Proprioceptive Feedback From Nonspiking Mechanosensory Cells in the Sand Crab, Emerita Analoga
Authors: Paul Dorothy Hayman
Published: April 2021

The two programmes underlying uropod beating in Emerita (‘swimming’ and ‘treading water’) are distinguished by a difference in timing of the power stroke within the interval between return strokes (cycle). While ‘swimming’ (cycles approx. 80–400 ms) the phase and while ‘treading water’ (cycles approx. 100–700 ms) the latency of the power stroke are relatively invariant. Analyses of electromyograms of unrestrained Emerita, before and after bilateral surgical ablation of the four nonspiking mechano- receptive cells associated with each uropod, established that power strokes in ‘treading water’ are dependent upon proprioceptive feedback from the nonspiking cells. As cycle duration increases from 80 to 700 ms, the function of the reafference changes from reinforcement of the centrally generated ‘swimming’ pattern to production of the ‘treading water’ pattern.
Physiology of An Atp Receptor in Labellar Sensilla of the Tsetse Fly Glossina Morsitans Morsitans Westw. (Diptera: Glossinidae)
Authors: Mitchell B. K.
Published: April 2021

Electrophysiological recordings have been made from cells in the eight large, labellar sensilla of G. morsitans. One of these cells in each sensillum was shown to respond to ATP over a concentration range of 10−6–10−3 M. It was also sensitive to several other adenosine phosphates, but much less sensitive to CTP, GTP and ITP. The activity of the receptor was depressed below pH 7, and sometimes considerably increased above pH 9. These aspects of the receptor’s physiology support the results of behavioural studies. It is concluded that the eight receptors mediate the flies’ behavioural response to ATP.
Stretch-Sensitive Neural Units in the Body Wall of the Earthworm, Lumbricus Terrestris L
Authors: Drewes C. D. , Fourtner C. R.
Published: April 2021

Sensory neural units responding to sinusoidal longitudinal stretching of the body wall were studied in the earthworm, Lumbricus terrestris L. A phasic stretch-sensitive unit found in segmental nerve I responded optimally to stretching at frequencies of 4–6/min. The number of spikes per stretch and the spike frequency in the unit were directly related to the amplitude of the applied stretch within a range of 0·2–0·7 mm stretch/segment. The ranges of amplitude and frequency sensitivity for the unit in isolated preparations corresponded closely to stretch parameters seen during peristaltic locomotion in intact animals. Stretch-sensitive responses in segmental nerve II—III were more variable; some units responded to longitudinal stretch while others responded to relaxation.
Nervous Control of Light Responses in the Sea Anemone, Calamactis Praelongus
Authors: Marks Philip S.
Published: April 2021

The burrowing sea anemone, Calamactis praelongus, responds to light with local, non-nervous contractions of the column. There are also more extensive responses of the column and retractor muscles co-ordinated by nerve net pulses (NNP’s) under pacemaker control. NNP’s occur in at least two types of bursts and in sequences which sometimes indicate a rotating site of pulse initiation. Light-evoked NNP sequences can be tape recorded and used later to drive a stimulator to reproduce the original sequences in the same or different anemones, evoking muscular responses which approximate the originals. This technique separates the pacemaker-directed component of the light response from the local effects of light stimulation. Isolated circular and parietal muscles contract slowly when stimulated by light or excited indirectly by NNP’s. Retractor muscles are insensitive to light but produce rapid contractions when excited by closely spaced light-evoked NNP’s. A model for light responses is proposed which incorporates the characteristics of isolated muscles and intact anemones.
Synaptic Transmission in the Sixth Ganglion of the Cockroach: Action Of 4-Aminopyridine
Authors: Hue B. , Pelhate M. , Callec J. J. , Chanelet J.
Published: April 2021

Study was made of the action of 4-aminopyridine (5× 10−5M) on synaptic transmission in the last abdominal ganglion of Periplaneta americana. The ‘oil-gap’ technique was used to record postsynaptic events in a single giant axon. 4-AP quickly increased the ‘background’ of postsynaptic activity, which consisted of ‘spontaneous’ unitary EPSPs and IPSPs. Postsynaptic spikes were also propagated. Both evoked EPSPs (stimulation of cereal nerve XI) and evoked IPSPs (stimulation of cereal nerve X) were greatly increased in amplitude although their duration (half-time) was unaltered. 4-AP triggered presynaptic action potentials in the cereal nerves (recorded with external electrodes). These ‘antidromic’ potentials appeared singly or sometimes repetitively, especially after electrical stimulation of the cereal nerves. They were often in monosynaptic correlation with unitary EPSPs. Neither the resting potential nor the postsynaptic membrane resistance was modified. There were no changes in the equilibrium potentials of the ions involved in postsynaptic events. The results may be essentially explained by an increase in transmitter release after 4-AP treatment, which may be partly the result of a rise in presynaptic terminal excitability, and partly the result of a lengthening of the presynaptic action potentials.