bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms of Body-Temperature Regulation in Honeybees, Apis Mellifera
Authors: Heinrich Bernd
Published: April 2021

Honeybees when endothermically heated maintained an elevated head temperature (TH) During free flight at 17 °C TH was approximately 7 °C above ambient temperature (TA). However, during flight at TA near 46 °C, head temperature averaged 3 °C below TA. When tethered bees were heated on the head till TH reached 46 °C, they regurgitated nectar from their honeycrop, held it on their ‘tongue’, and initiated violent aortic pulsations in the head and in-out movements of the nectar droplet. Temperature changes in the head corresponded with heart pulsations. Head temperature was prevented from rising and was stabilized. The heart pulsations in the abdomen and aortic pulsations in the head (and abdominal ventilatory movements) were often synchronous, but during heating of the head they were often independent of each other in both frequency and amplitude. The fluid droplet was several degrees Centigrade below head, thoracic and ambient temperatures, and it remained in motion in and out of the body. It caused TH to be 4-8 °C lower, by the resulting evaporative cooling, than is possible without the droplet. It is concluded that at low TA the elevation and regulation of automatically results in the elevation of TTh. However, at low TH heat flows from the heated thorax to the head, not only by passive conduction but also by physiologically facilitated blood circulation.
Neural Interactions Controlling Timing of Flight Muscle Activity in Drosophila
Authors: Koenig J. H. , Ikeda Kazuo
Published: April 2021

Simultaneous intracellular recordings were made from the six ipsilateral dorsal longitudinal muscle fibres of Drosophila in stationary flight. The influence of the firing of one motor unit upon the firing of another was analysed by observing the relationship between the interspike interval of a unit and the relative firing times of the other motor units within that interval. The analysis suggests that the influence is insignificant except when one unit would have fired soon after another. Then, a neural interaction occurs that can cause a unit to fire either earlier or later, depending on its firing relationship with the other units. Thus, the observation that no DLM fibre fires soon after another is the result of both a delaying effect and an effect which causes a cell to fire earlier than it normally would have fired.
Interspike Interval Relationship Among Flight Muscle Fibres in Drosophila
Authors: Koenig J. H. , Ikeda Kazuo
Published: April 2021

Simultaneous intracellular recordings were made from the 10 motor units (12 fibres) comprising the bilateral pair of dorsal longitudinal flight muscles in Drosophila melanogaster while in stationary flight. The neural input which commonly drives these units was characterized by observing the influence which this input has on the interspike intervals of the various units. It was observed that the intervals of these units (both ipsilateral and contralateral), when considered collectively (that is, as a series of successively occurring intervals without regard for which unit represents which interval), fluctuate in a serially correlated manner. These interval fluctuations collectively define a fluctuation of complex waveform. The characteristics of this waveform suggest that two (or more) oscillating inputs are involved in commonly driving these units. In addition, a coupling in frequency and timing was observed between certain pairs of ipsilateral units, as well as between the units of one side relative to those of the other side. This coupling suggests that the neural pathway leading from the oscillating driving source might diverge, first to left and right sides, and then at a more peripheral level into three separate pathways, one leading to units 1 and 2, another to units 3 and 4, and a third to unit 5/6.
Extracellular Potassium in Neuropile and Nerve Cell Body Region of the Leech Central Nervous System
Authors: Schlue W. R. , Deitmer J. W.
Published: April 2021

Potassium-sensitive double-barrelled microelectrodes were used to measure the potassium content of extracellular spaces in leech ganglia, both intact and with the ganglion capsule opened. When the ganglion capsule was opened, the extracellular concentrations of potassium in the ganglion were similar to that of the bathing medium (4 mM). With intact ganglia the extracellular potassium concentration in the neuropile averaged 6·3 ± 0·7 mM and in the nerve cell body region 5·8±0·6mM. The potential measured in these parts of the ganglion was between + 2 and – 8 mV, averaging – 1·9 mV. The change of potassium concentration in the extracellular spaces following increase or decrease in the concentration of potassium ions in the bath declined exponentially. This rate of change, which would be expected of a first-order diffusion process, was found in both the neuropile and the nerve cell body region. In a medium containing 5 × 10−4M ouabain, the potassium concentration in both parts of the ganglion increased transiently, by an average of 3× 8 ± 1× 0 mM in the neuropile and 1× 2 ±0× 4 mM in the nerve cell body region. Negatively charged polyelectrolytes in extracellular spaces of leech ganglia could affect the distribution of potassium ions to give a Donnan distribution. It is also possible, that the endothelial layer influences the extracellular potassium concentration in a ganglion under resting conditions.
The Retention of Amino Acids in the Haemolymph During Diuresis in Rhodnius
Authors: Maddrell S. H. P. , Gardiner B. O. C.
Published: April 2021

The haemolymph of Rhodnius is rich in amino acids. During the rapid diuresis after a blood meal, no more than trace amounts of amino acids are lost in the urine. There is no significant reabsorption of amino acids in the excretory system. That they escape elimination can instead be attributed to a combination of the low permeability of the Malpighian tubules to amino acids, the very high rate of fluid secretion by the tubules, and the dilution of the haemolymph by an expansion in its volume after feeding. Amino acid losses are low in spite of the fact that the tubules actively accumulate high concentrations of amino acids in their cells and passive losses from these stores augment to some extent the flux of amino acids into the lumen.

At times other than during diuresis, fluid secretion by the Malpighian tubules is slow. Calculations show that haemolymph solutes can then passively reach the higher concentrations in the lumen that are required for the operation of the excretory system (which relies on unselective passive entry and active reabsorption of useful substances).

An advantage of the extraordinarily high rate of fluid secretion during diuresis is that fluid excretion can be rapidly completed. There is then little time for significant amounts of haemolymph solute to be lost passively.
Frequency Selectivity in The Parakeet Studied by Isointensity Masking Contours
Authors: Saunders James C. , Pallone Robert L.
Published: April 2021

The effect of masking tones at fixed sound pressure levels on the threshold detection of probe-tone signals was studied in the parakeet using avoidance conditioning and a psychophysical method of limits. Between two and six masker levels were used at each of six centre frequencies to describe isointensity masking contours. The shape of the masking contours appeared to be independent of masker level and all exhibited a band-pass filter curve whose sharpness depended on the centre frequency. These data provide an indication of the frequency resolving power of this avian species.
A Transmesogloeal Conduction System in the Swimming Sea Anemone Stomphia
Authors: Lawn I. D.
Published: April 2021

A conduction system in Stomphia transfers information across the mesogloea from ectodermal receptors to endodermal effectors. In the column, this transmesogloeal system has numerous and widespread connexions. It is suggested that the connexions may be processes from multipolar nerve cells located in the endoderm. Certain aspects of behaviour are controlled by this conduction system which provides yet another pathway to co-ordinate electrical activity.
The Role of Vagal Afferent Information and Hypercapnia in Control of the Breathing Pattern in Chelonia
Authors: Milsom W. K. , Jones D. R.
Published: April 2021

The normal breathing pattern of the turtle, Chrysemys picta (Schneider), consists of periods of continuous breathing interspersed with periods of breath holding. During each ventilatory period respiratory frequency and tidal volume are controlled independently. There is a large variability in inspiratory and expiratory gas-flow rates yet tidal volumes are maintained within narrow limits by adjustments of the lengths of the active inspiratory and expiratory intervals. Lung volume information carried within the vagus nerve is responsible for the careful regulation of tidal volume as well as for modulation of the air flow rates and lowering of the threshold of the mechanism initiating expiration following breath holding.

Increases in pulmonary minute ventilation during hypercapnia are caused by increases in respiratory frequency due solely to a shortening of the periods of breath holding. There is some increase in tidal volume but the breath length remains constant and thus the frequency of breathing within each ventilatory period also remains constant.

After vagotomy, changes in minute ventilation due to hypercapnia stem primarily from changes in tidal volume while changes in respiratory frequency are greatly reduced.
Mechanical Properties of Contour Feathers
Authors: Macleod G. D.
Published: April 2021

Young’s moduli (E) in bending and extension were measured for selected contour feather shafts from the chicken (Gallus domesticus), turkey (Meleagris gallopavo), ring-necked pheasant (Phasianus colchicus) and herring gull (Larusargentalas). These were treated mechanically as tapering beams. In extension, E ranged from 45 to 181 MN m−2 and from 210 to 682 MN m−2 for the proximal and distal regions, respectively. Values obtained for the same regions in bending were from 5 to 24 MN m−2 and 457 to 1850 MN m−2. These results suggested that the cortex of the proximal region generally has a lower Young’s modulus than the medulla, while for the distal region this is reversed. This was confirmed by further measurements on treated shafts. The observed systematic differences in the mechanical properties of the proximal and distal parts of contour feather shafts are consistent with their probable mechanical functions.
The Pharmacological Profile of the Acetylcholine Response of A Crustacean Muscle
Authors: Marder Eve , Paupardin-Tritsch Danièle
Published: April 2021

A pharmacological analysis was made of the depolarizing acetylcholine (ACh) response found on the gastric mill 1 muscles of the crabs Cancer pagurus, Cancer irroratus and Cancer borealis.

Acetylcholine, carbamylcholine, trimethylammonium, nicotine, and dimethyl-4-phenyl-piperazinium were effective in producing contractures and depolarizations in these muscles. No response to decamethonium, suberyldicholine, acetyl-β-methylcholine, carbamyl-β-methylcholine, pilocarpine and oxotremorine could be detected.

High concentrations of muscarinic agonists (10−4 to 10−3M) potentiated and prolonged the ACh iontophoretic response. When the acetylcholinesterase activity was inhibited with neostigmine, or when the response was elicited with carbamylcholine, muscarinic agonists partially inhibited the response.

ACh responses were most effectively blocked by vertebrate nicotinic ganglionic antagonists, including dihydro-β-erythroidine, pempidine, and mecamylamine.

α-Bungarotoxin was without effect on the ACh response.
Excitable Epithelial Cells in the Bioluminescent Scales of A Polynoid Worm; Effects of Various Ions On the Action Potentials and On the Excitation-Luminescence Coupling
Authors: Bilbaut André
Published: April 2021

The bioluminescent scales of the polynoid worm Acholoe astericola are covered with photogenic and non-photogenic excitable epithelial cells which are electrically coupled. The luminescent activity is intracellular and occurs in brief flashes. All the epithelial cells produce non-overshooting action potentials which have been shown to be Na-dependent. In the photogenic epithelial cells (photocytes) the increase of the stimulus strength elicits another action potential specifically correlated with a flash. This membrane response begins by a fast overshooting Ca-dependent spike potential followed by a Na-dependent secondary depolarization. The excitationluminescence coupling is dependent on Ca entry into the photocytes.
Divalent Cations as Charge Carriers During two Functionally Different Membrane Currents in the Ciliate Stylonychia
Authors: Peyer Jacques E. De , Deitmer Joachim W.
Published: April 2021

We have investigated the ability of various divalent cations to carry current through membrane channels in ciliates activated by mechanical stimulation and by membrane depolarization. Both types of channels are identified as Ca2+ channels. Whereas Ba2+ ions and Sr2+ ions can replace Ca2+ ions as charge carriers during either kind of current, Mg2+ ions can carry the current evoked by mechanical stimulation but not the current elicited by membrane depolarization. Mn2+ ions did not carry either of these currents, and they reduced the currents carried by Ca2+ions. Our experiments suggest that the mechano-sensitive and the voltage-senstive channels exhibit different selectivities for divalent cations.
Experimental Analysis of Adhesion Of Chrysolina Polita (Chrysomelidae: Coleoptera) On A Variety of Surfaces
Authors: Stork N. E.
Published: April 2021

Pulling forces of Chrysolina polita (L.) on glass, perspex and cloth have been recorded and are plotted against body weight. The additional weight of eggs in many of the females is probably the main reason that, in females, pulling forces do. not increase significantly with body weight, whereas those of males do. Pulling forces on glass and perspex are significantly correlated but, in general, neither are significantly correlated with those on cloth. This is because traction on glass and perspex is achieved by the adhesive setae, and on cloth by the tarsal claws. Counts of the adhesive setae in 14 individuals indicate that numbers of climbing setae in females and males and females (combined), male setae in males, and the total number of adhesive setae in males, all show a significant increase with body weight. Pulling force increases with the total number of adhesive setae in females, and males and females (combined). Multiple regression analysis confirms the view that pulling force is a function of the number of adhesive setae. Hooks, suction, electrostatic forces and seizure are largely discredited, and molecular adhesion between the setae and the substratum, and possibly the cohesive forces and surface tension of a thin fluid layer, are confirmed as the most likely modes of adhesion on smooth surfaces in C. polita and most beetles. It is proposed that the main forces of detachment acting on a leaf beetle are probably drag and the whiplash effect of the leaves and branches. Estimates for the wind speeds required to remove beetles from glass and cloth by drag forces alone are calculated.
Amines and A Peptide As Neurohormones in Lobsters: Actions on Neuromuscular Preparations and Preliminary Behavioural Studies
Authors: Kravitz Edward A. , Glusman Silvio , Harris-Warrick Ronald M. , Livingstone Margaret S. , Schwarz Thomas , Goy Michael F.
Published: April 2021

In this communication we report that four substances, thought to function as neurohormones in Crustacea, all produce long-term changes in the physiological properties of lobster opener muscle preparations. The substances are the amines, octopamine, serotonin and dopamine, and the peptide, proctolin. The actions of these substances are superimposed on the normal synaptic apparatus that utilizes the amino acids GABA and glutamate (probably) as the inhibitory and excitatory neurotransmitter compounds.

Serotonin acts on excitatory and inhibitory nerve endings to facilitate transmitter release and directly on muscle fibres to produce a contracture and to induce the appearance of Ca2+ action potentials. The latter two actions of serotonin are shared by proctolin and octopamine as well. Dopamine, on the other hand, relaxes muscle baseline tension. The mechanism of action of these substances at their target site (or sites) has been explored with electrophysiological and biochemical techniques and the results will be presented.

In addition preliminary behavioural experiments have been carried out with serotonin and octopamine. These substances produce opposite postures when injected into lobsters. The amines act on central ganglia to produce these effects where they cause a programmed readout of firing of neurones that will produce either a flexed posture (serotonin) or an extended posture (octopamine).
Feed-Back Modulation of Cone Synapses by L-Horizontal Cells of Turtle Retina
Authors: Gerschenfeld H. M. , Piccolino M. , Neyton J.
Published: April 2021

Light stimulation of the periphery of the receptive field of turtle cones can evoke both transient and sustained increases of the cone Ca2+ conductance, which may become regenerative. Such increase in the cone Ca2+ conductance evoked by peripheral illumination results from the activation of a polysynaptic pathway involving a feed-back connexion from the L-horizontal cells (L-HC) to the cones. Thus the hyperpolarization of a L-HC by inward current injection can evoke a Ca2+ conductance increase in neighbouring cones. The cone Ca2+ channels thus activated are likely located at its synaptic endings and probably intervene in the cone transmitter release. Therefore the feed-back connexion between L-HC and cones by modifying the Ca2+ conductance of cones could actually modulate the transmitter release from cone synapses. Such feed-back modulation of cone synapses plays a role in the organization of the colour-coded responses of the chromaticity type-horizontal cells and probably of other second order neurones, post-synaptic to the cones. The mechanisms operating the feed-back connexion from L-HC to cones are discussed.
Primary and Secondary Regulation of Quantal Transmitter Release: Calcium and Sodium
Authors: Rahamimoff Rami , Lev-Tov Aharon , Meiri Halina
Published: April 2021

Calcium is the prime regulator of quantal acetylcholine liberation at the neuromuscular junction; its entry through the presynaptic membrane and the level of free [Ca]in most probably determine the number of transmitter quanta liberated by the nerve impulse. The level of free [Ca]in, in turn, is controlled by a number of subcellular elements: mitochondria, endoplasmic reticulum, vesicles, macromolecules and the surface membrane.

The action potential induced calcium entry is not the only factor responsible for coupling nerve terminal depolarization with increased transmitter release; increased transmitter release occurs also in the virtual absence of calcium ions in the extracellular medium, when a reversed electrochemical gradient for calcium probably exists during action potential activity. Several lines of evidence suggest that the entry of sodium ions is responsible for this augmented transmitter release: the tetanic potentiation observed under reversed calcium gradient is blocked by tetrodotoxin ; tetanic and post-tetanic potentiation are augmented and prolonged by ouabain; the amplitude of the extracellular nerve action potential is reduced with high-frequency stimulation, in parallel with increased spontaneous quantal release. In addition, sodium-filled egg-lecithine liposomes augment quantal liberation.

The augmentory effect of sodium on transmitter release is probably due to an intracellular calcium translocation, since no preferred timing after the action potential is observed. Thus the level of [Na]in in the presynaptic nerve terminal can control indirectly the efficiency of synaptic transmission.
Dual Function During Development of Rat Sympathetic Neurones in Culture
Authors: Potter D. D. , Landis S. C. , Furshpan E. J.
Published: April 2021

Many sympathetic principal neurones of the superior cervical ganglion of the newborn rat are known to be plastic with respect to the choice between norepinephrine (NE) and acetylcholine (ACh) as transmitter; when the neurones are dissociated and placed in culture, a majority of them can be shifted from an initial, immature, adrenergic state to a cholinergic state by co-culture with a variety of non-neuronal cells or by medium conditioned by such cells.

To study this transition it has been helpful to grow single neurones, each in a microculture which also contains cardiac myocytes. The transmitter status of a neurone can be assayed by recording its effect on the myocytes (adrenergic excitation, cholinergic inhibition or dual function); then a fine structural assay of the neurone based on the appearance of the synaptic vesicles can be made and correlated directly with the physiology. In this paper we report the following findings on principal neurones developing in such microcultures, (i) During the transition period, a majority of the neurones were dual in function and in vesicular appearance, (ii) The physiological effects and vesicular appearance varied from mainly adrenergic to mainly cholinergic, (iii) In preliminary attempts to follow the transition by recording at least twice from the same microculture, partial transitions were observed, always in the direction adrenergic-to-cholinergic. (iv) The transitions were not synchronous or fixed in time course even in pairs of neurones grown side by side in the same microculture.
Change of Weight of Marine Animals in Diluted Media
Authors: Hukuda K.
Published: April 2021

Several species of marine invertebrates, and an elasmobranch, have been kept in diluted media. The increase of body weight so caused was compared with the resulting dilution of the body fluids. The bounding membrane of the invertebrates was permeable to salts when the animals were immersed in diluted sea water. The bounding membrane of the elasmobranch was semipermeable, i.e. permeable to water but not to solute. There is a close quantitative agreement between the osmotic swelling observed and the diminution of the osmotic pressure of the blood.
On Phosphorus Metabolism in Embryonic Life
Authors: Needham Joseph , Needham Dorothy Moyle , Yudkin John , Baldwin Ernest
Published: April 2021

In the first paper of this series (16) a survey was made of the phosphorus distribution in developing invertebrate eggs with the object of sketching out the broad outlines of the metabolism of this element during ontogenesis. Representative echinoderms, Crustacea, and a podaxonian were examined with respect to the behaviour of total phosphorus, lipoid, phosphoprotein and nucleoprotein phosphorus, total, organic and inorganic water-soluble phosphorus, etc. But interesting as the results of such a survey were, there remained a number of phosphorus compounds which merited study, among which may be named hexosephosphate phosphorus, adenylic acid phosphorus, glycerophosphate phosphorus, phosphorus in combination with cycloses, and phosphagen phosphorus. It is with the latter of these that this paper will deal.
The Influence of Atmospheric Humidity on the Thermal Death Point of A Number of Insects
Authors: Mellanby Kenneth
Published: April 2021

This work is an attempt to investigate the effects of various atmospheric humidities on the death points of insects at high temperatures. A number of species of insects were used, and an attempt made to correlate the results with those of previous workers.
Iodine Compounds and Fertilisation
Authors: Carter G. S.
Published: April 2021

It has been shown (Carter, 1931 b) that eggs of Echinus esculentus and E. miliaris which are being washed in a current of sea-water remain fertilisable for a longer time if thyroxine is present in the water of the current. In his investigation of the egg secretions and the part they play in the fertilisation of the egg, Lillie (1914) showed that the rapid decay of echinoderm eggs exposed to a current of sea-water is due to the diffusion of the secretions from the surface of the eggs, and particularly to the loss of one component of the secretions which is essential to the activation of the eggs (“fertilizin”). In view of his work, the results of the previous paper strongly suggest that the manner in which thyroxine acts in prolonging the life of washed eggs is by penetrating the surface of the eggs and causing a change in the cytoplasm by means of which the supply of fertilizin within the egg is maintained for a longer time. The probability that it acts in this way is increased by the evidence given in the earlier papers of this series (1930, 1931 a), where it was shown that the egg secretions and thyroxine act so similarly in other phenomena that it is probable that thyroxine is chemically related to some substance present in the secretions. If this conclusion is accepted, and if the substance to which thyroxine is related is fertilizin itself (and further evidence that this is so will be given in later papers), it is not improbable that thyroxine may definitely replace the fertilizin in the cytoplasm, presumably by being itself transformed into this substance by the activity of the protoplasm.
Iodine Compounds and Fertilisation
Authors: Carter G. S.
Published: April 2021

If fresh and ripe spermatozoa of E. esculentus or E. miliaris are put into a solution of thyroxine in sea-water of a concentration of 1/50,000 by weight and at the hydrogen-ion concentration of sea-water (pH 8-2), they very soon come together by their heads and form clumps. The most favourable concentration of the sperm for observing this phenomenon is a mixture of sea-water and undiluted sperm in a proportion of 500 : 1 or 1000 : 1. This “agglutination” is visible under the microscope in 1-3 min. and becomes very obvious in 10 min. In a short time the larger clumps fall to the bottom and there form a flocculent precipitate, which can be collected into the centre of the dish by shaking, and is easily visible to the naked eye. The clumps are dense and at first spherical, but their shape becomes irregular as they grow larger, probably in part by the coalescence of several small clumps to form one larger one, and in part by uneven addition of spermatozoa on the outside of the clump. The sperm are active, at least for many minutes, after they are agglutinated. The agglutination is permanent. It only occurs in fresh and ripe sperm. Perfectly ripe sperm may show a slight spontaneous agglutination in seawater, but this is always much less than the agglutination in the presence of thyroxine.
The Osmotic Relations Between White and Yolk in the Hen’s Egg
Authors: Bateman J. B.
Published: April 2021

The osmotic relations between white and yolk in the fertilised and unfertilised hen’s egg have often been investigated. The complexity of these relations is presumably due largely to peculiar physico-chemical properties of the colloid constituents of the egg. The purpose of this paper is primarily to confirm the existence of a considerable osmotic difference between white and yolk in the unfertilised hen’s egg, in reply to a recent denial, and then to describe some preliminary experiments on the state of water and of several dissolved substances in the egg. The bearing of these experiments on the relations between white and yolk in the intact egg will then be discussed briefly.
The Effect of Temperature on Haemolytic Systems Containing Propyl Alcohol
Authors: Gordon Albert S.
Published: April 2021

The effect of temperature on haemolytic systems in which saponin and sodium taurocholate respectively were used as lysins has been described by Ponder and Yeager (1930 a). They have found that in these cases the Arrhenius equation cannot be applied, mainly because of the complexity of these apparently simple systems.
A Function of the Subelytral Chamber of Tenebrionid Beetles
Authors: Slobodchikoff C. N. , Wismann Kim
Published: April 2021

The subelytral chamber is an air space between the elytra and the dorsum of the abdomen of some Tenebrionid beetles. Postulated functions for the subelytral chamber have been a reduction of transpiratory water loss and a thermal buffer for heat flow from the elytra to the abdomen. We show that there is a significant correlation between water loss and the depth of the subelytral chamber. This implies that the chamber may be a structure that permits the rapid expansion of the abdomen, providing the beetles with a mechanism by which they can quickly drink large quantities of water from an ephemeral source such as a rain puddle. As the beetles drink, the abdomen greatly expands, and the chamber shrinks.
The Activity and Characteristics of the Ca2+ ATPase of Fish Gills in Relation to Environmental Calcium Concentrations
Authors: Shephard K. L.
Published: April 2021

The concentration of plasma calcium and the activity of the gill Ca2+ - ATPase has been measured in roach from several waters. Plasma calcium concentrations in these fish vary very little (2·62 ± 0·17 him) despite great variation in the external calcium concentration between waters (0·40 to 2·92 mm). There is, however, a close correlation between Ca2+ ATPase activity and external calcium concentration, consistent with the view that differences in the requirement for calcium transport are accommodated by variation in the Ca2+ ATPase system.

These results are discussed in relation to those of a previous experiment, where the short term effects of changing external calcium were considered. It is suggested that variation in the absolute level of Ca2+ATPase activity represents the long term adaptation of the roach to different calcium concentrations.
Reversal of a Walking Leg Reflex Elicited by a Muscle Receptor
Authors: DiCaprio R. A. , Clarac F.
Published: April 2021

Passive movement of the basal (thoracic-coxal) leg joint in the shore crab Carcinus maenas normally elicits a resistance reflex in the promotor and remotor motoneurones. Remotion of the joint excites promotor moto-neurones and promotion excites remotor motoneurones. This reflex behaviour may reverse and become an assistance reflex, where movement of the joint excites the motoneurones innervating the muscle which would assist the passive movement. This reversal of reflex activity appears to be dependent upon the central state of activity of the animal.
Proprioceptive Control of the Bilaterally Organized Rhythmic Activity of the Oesophageal Neuronal Network in the Cape Lobster Jasus Lalandii
Authors: Nagy F. , Moulins M.
Published: April 2021

In the lobster Jasus lalandii the activity of the oesophageal nervous system (monitored through the firing of its main motor neuron, OD1) is modulated by a pair of proprioceptors, the posterior stomach receptors (PSRs). The in vitro preparation used consisted of the oesophageal nervous system, the suboesophageal ganglion and the two PSRs, which provide the only source of sensory input. Stimulation of a PSR activates only the oesophageal oscillator located in the ipsilateral commissural ganglion. When spike conduction is blocked in the ipsilateral connective, the stimulation of a PSR activates the contralateral oesophageal oscillator. Inputs from each PSR project to the different parts of the distributed oesophageal network (in the two commissural ganglia and the oesophageal ganglion), but at a given time only one of the PSRs’ projections is effective. The relative efficacy of the PSRs’ projections is controlled by the oesophageal motor network itself and requires that the superior oesophageal nerves be intact (sons). The PSRs’ inputs are integrated in the suboesophageal ganglion before reaching the oesophageal network. However, this premotor step is not involved in the control of the unilaterality of PSRs’ effects. The PSRs are stimulated by at least two different rhythmical muscular sequences of the foregut (the gastric mill sequence and the cardiac sac sequence) and provide a source of rhythmical inputs to the CNS. The oesophageal nervous system exhibits a periodically varying sensitivity to the PSRs’ inputs, which is illustrated by a phase-response curve. Each oesophageal oscillator can be entrained by the rhythmical PSRs’ inputs over a range of period. This range includes the period of the spontaneous gastric rhythm. It is proposed that the PSRs enable the oesophageal and the gastric mill rhythms to be coordinated through a peripheral loop. The participation of PSRs in the coordination of different motor sequences of the foregut is discussed.
Cyclic Adenosine Monophosphate Mediation of Peptide Neurohormone Effects on the Lobster Cardiac Ganglion
Authors: Lemos Jose R. , Berlind Allan
Published: April 2021

Two cardioexcitors which can be extracted or released from crustacean neurohaemal structures, the pericardial organs, alter the endogenous bursting activity of isolated lobster cardiac ganglia in different ways. A small peptide increases the burst frequency of the ganglion, the duration of each burst, and the number of spikes per burst, while 5-hydroxytryptamine (5-HT) increases burst frequency, but decreases the burst duration and number of spikes per burst. Four lines of evidence are presented that cyclic adenosine monophosphate (cAMP) mediates the effects of peptide on the ganglion, but does not play a significant role in 5-HT action: (1) exogenous cAMP mimics the effects of peptide but not of 5-HT on burst parameters; (2) inhibition of the enzyme phosphodiesterase, which increases endogenous levels of cAMP, mimics the effects of peptide and potentiates peptide action but not that of 5-HT; (3) putative blockers of adenylate cyclase block the action of peptide but not of 5-HT; (4) peptide causes a large increase in cAMP content of the ganglion, while 5-HT application results in a much smaller increase.
Comparison of Potassium Transport in Three Structurally Distinct Regions of the Insect Midgut
Authors: Cioffi Moira , Harvey William R.
Published: April 2021

Active potassium transport across the isolated midgut of the Tobacco Hornworm larva, Manduca sexta, was studied by measuring the short circuit current (Isc) and unidirectional 42-potassium fluxes. The midgut is composed of structurally distinct anterior, middle and posterior regions, all of which are shown to transport potassium, so that by comparing and contrasting their structural and functional properties new information on the mechanism of midgut potassium transport was obtained. It has previously been shown that the potassium pump is located on the apical membrane of the goblet cell. In the anterior and middle regions of the midgut the goblet cell has a large cavity and mitochondria are closely associated with the apical membrane while in the posterior midgut the goblet cavity is much smaller, and mitochondria are not associated with the apical membrane. However, the apical membrane particles which have been implicated in active potassium transport in a number of other insect epithelia are present in all three regions. This observation suggests that the particles are a structural requirement for active transport, and that close association between mitochondria and the transporting membrane is not essential. Comparison of the kinetic influx pool size and the differences in the Isc decay profiles between the three midgut regions suggest that part of the influx pool is a transported pool located in the goblet cavity. A new model to explain the driving force for potassium transport in the midgut is proposed, in which the rate of potassium transport controls the entrance of potassium into the cell, rather than the opposite, currently accepted view.
A Quantitative Model for the Adhesive Locomotion of The Terrestrial Slug, Ariolimax Columbianus
Authors: Denny Mark W.
Published: April 2021

The foot of pulmonate gastropods adheres to the surface upon which the animal crawls, the adhesive being a thin layer of pedal mucus. The power for locomotion in these animals is provided by rhythmic muscular contractions (pedal waves) on the ventral surface of the foot, and the force due to these waves is coupled to the substratum by the pedal mucus. Movement of the animal is consequently a result of a balance of forces: if the reactive force provided by the adhesive beneath the stationary portions of the foot is sufficient to offset the frictional force caused by portions of the foot moving forward, the animal is able to crawl. Mechanisms previously proposed to explain this adhesive crawling require that the frictional resistance to forward movement be minimized by the foot being lifted during the passage of a pedal wave. This lifting, however, cannot be reconciled with the properties of the pedal mucus and epithelium, and the terrestrial slug, Ariolimax columbianus, is shown to not lift its foot when crawling. A new mechanism is proposed which does not require lifting of the foot and explains several difficulties inherent in previous studies. Based on this mechanism and the mechanical properties of pedal mucus, a quantitative model is constructed which predicts the frictional and reactive forces, and these predictions are tested against force measurements made under crawling slugs. The model accurately predicts the magnitude of forces under slugs crawling horizontally, but is less accurate in predicting forces under slugs crawling vertically.
The Mechanisms and Energetics of Honeybee Swarm Temperature Regulation
Authors: Heinrich Bernd
Published: April 2021

Free (active) honeybee swarms regulated their core temperature (Tc) generally within 1 °C of 35 °C. They maintained the same temperature around freshly built honeycomb, and in the brood nest of the hive, from ambient temperatures of between at least 1 and 25 °C. Captive (inactive) swarms in the laboratory often allowed Tc to decline below 35 °C. The temperature of the swarm mantle (Tm) varied with the general activity of the swarm as well as with ambient temperature (TA), but in captive swarms (and sometimes at night in free swarms), Tm was generally held above 17 °C, even at TA< 5 °C. Within the swarm, temperatures varied between 36 °C, an upper temperature set-point, and 17 °C, a lower temperature set-point. Before swarm take-off, all temperature gradients in the swarm were abolished and Tm equalled Tc. The regulated Tc and Tm were unrelated to size and passive cooling rates in swarms ranging from 1000 to 30000 bees. The weight-specific metabolic rate of swarms was correlated with TA and Tc, but relatively little affected by swarm size. Bees on the mantle experiencing low temperatures pushed inward, thus contracting the mantle, diminishing the mantle porosity, and filling interior passageways. As a result, their own rate of heat loss, as well as that from the swarm core, decreased. In large tightly clumped swarms, even at TA< 5 °C, the resting metabolic rate of the bees in the swarm core was more than sufficient to maintain Tc at 35 °C or above. The active thermoregulatory metabolism was due to the bees on the swarm mantle. There was little physical exchange of bees between core and mantle at low (< 5 °C) TA. In addition, there was no apparent chemical or acoustic communication between the bees in the swarm mantle that are subjected to the changes of the thermal environments and the bees in the swarm interior that constantly experience 35 °C regardless of TA. The data are summarized in a model of Tc control indicating a primary role of the mantle bees in controlling heat production and heat loss. The possible ecological significance of swarm temperature regulation is discussed.
Carbonic Anhydrase Activity During the Larval-Pupal Transformation of Hyalophora Cecropia Reared on Foliage and Synthetic Diet: Effects of Potassium and Chloride on Midgut, Fat Body and Integumentary Enzymes
Authors: Johnston James W. , Jungreis Arthur M.
Published: April 2021

Carbonic anhydrase was measured in tissues of silkmoths, Hyalophora cecropia, reared on either a wheatgerm-based synthetic diet or wild cherry foliage in feeding fifth-instar larvae, throughout the larval-pupal transformation and in newly ecdysed pupae. Carbonic anhydrase activity was present in fat body, midgut and intgeumentary epithelial cells, but not in haemolymph, cuticle or the integumentary musculature. Approximately 70 % of the total carbonic anhydrase present per animal is localized within the epidermal cells of the integument. The midgut is without measurable carbonic anhydrase activity from the day of apolysis (through the newly ecdysed pupal stage in development) until after the larval-pupal ecdysis. In tissues analysed during the feeding fifth larval instar, 150 toward acetazolamide was between 10−8 and 10−7 M. With the exception of larval midgut, regardless of stage, tissue or diet, both potassium and chloride normally inhibit carbonic anhydrase, with the effects of potassium and chloride being additive. In larval midgut, chloride at concentrations of 50 or 150 mmstimulates carbonic anhydrase activity 30 or 100%, respectively. In foliage-reared insects, potassium enhances chloride stimulation of larval midgut carbonic anhydrase, whereas in synthetic-diet-reared insects, potassium antagonizes the stimulatory effects of chloride. Removal of a heat-stable, dialysable factor associated with the larval midgut of foliage-reared insects converts properties of the foliage midgut enzyme to those characteristic of the synthetic diet type, and vice versa.
A Study of In Vivo Glycine Absorption by Fed and Fasted Rainbow Trout (Salmo Gairdneri)
Authors: Bogé G. , Rigal A. , Pérès G.
Published: April 2021

The effects of 4 and 8 weeks fasting at 16 °C were studied in rainbow trout, Salmo gairdneri Richardson. After 4 and 8 weeks, the wet weights of the intestine of fasted animals are respectively 64% and 69% lower than those of fed animals. These effects especially concern the mucosal tissue.

Glycine absorption (0·5 and 10 mm) was studied using an in vivo perfusion technique. After 4 weeks, the absolute amounts of 0·5 mm glycine absorbed by fasted and fed fish are similar. With 10 mm glycine, the absorption is slightly lower in fasted trout (–19%). After 8 weeks these differences are more marked, with glycine concentrations of 10 mm (– 42%). Results expressed per 100 g body weight showed that these differences result partly from a weight gain of fed trout. Absorption expressed in terms of weight of dry intestine is higher in 4 and 8 weeks fasted animals, principally for the lower amino acid concentration (+61% and +111%). Larger differences were apparent when the absorptions were expressed in terms of dry weight of mucosal tissue (+122% and +225%).
Duration Of Pupal Diapause in the Tobacco Hornworm is Determined By Number of Short Days Received By the Larva
Authors: Denlinger David L. , Bradfield James Y.
Published: April 2021

Daylength monitored by the embryos and larvae of the tobacco hornworm, Manduca sexta, is used to program both the incidence and duration of pupal diapause. Short daylength throughout embryonic and larval development yields a high diapause incidence, but a diapause of short duration. Hornworms transferred from long-to short-day conditions at later stages of larval development enter diapause at a lower rate, but the resulting diapause is of greater duration. The number of short-day cycles the hornworms receive can be varied by partial starvation and the use of different rearing temperatures. Such manipulations consistently support a model in which diapause duration is inversely related to the number of short-day cycles received. Observations with field-reared hornworms are consistent with the model: September hornworms receive more short-day cycles than August hornworms and thus have a shorter diapause. This mechanism apparently functions in synchronizing the initiation of adult development among individuals that pupate at different times. The diapause duration is programmed by the brain and can readily be transferred to other pupae by brain transplantation.
The Fate of Glomerular Filtration Markers Injected into the Haemolymph of the Amphibious Crab Holthuisana Transversa
Authors: Greenaway Peter
Published: April 2021

Three glomerular filtration markers injected into Holthuisana transversa disappeared from the haemolymph at very different rates. Polyethylene glycol 4000 disappeared at a rate ca. 5 times faster than Cr-EDTA and ca. 15 times faster than inulin. Inulin and Cr-EDTA were excreted by the crab but only 5 % of the injected PEG 4000 left the body. Inulin injected into the excretory organs was reabsorbed into the haemolymph. The reliability of commonly used glomerular filtration rate markers as indicators of filtration in decapods is discussed.
Measurements of the Intracellular Potassium Activity of Retzius Cells in the Leech Central Nervous System
Authors: Deitmer Joachim W. , Schlue Wolf R.
Published: April 2021

The intracellular K activity of leech Retzius cells was measured using double-barrelled, liquid ion exchanger, microelectrodes. At the normal external K+ concentration of 4 mm (equivalent to 3 mm-K activity, assuming an activity coefficient of 0·75) the mean K activity was 101·3 ± 7·6 mm (S.D., n = 14) in the cell bodies, and 4·35 ± 0·4 mV (n = 27) in the extracellular spaces surrounding them, indicating a K+ equilibrium potential of – 80 mV. The mean membrane potential was –43·6±4·9 mV (n = 14). In a K-free external solution, or in the presence of 5×10−4 M-ouabain, the intracellular K activity decreased by up to 14 mm min−1. This indicates an efflux of K+ ions across the cell membrane of approximately 2 × 10−10 mol cm−2 s, and an apparent K+ permeability coefficient of 8 × 10−8 cms−1. The cell membrane depolarized upon removal of K+ and upon addition of ouabain, and transiently hyperpolarized beyond its initial level on return to the normal external K+ concentration. The recovery from this hyperpolarization paralleled the increase of the intracellular K activity following the re-addition of K+. Our results suggest that, despite the high K+ permeability of the Retzius cell membrane, the intracellular K activity is maintained at a high level by an electrogenic pump.
Voltage Clamp Studies on Insect Skeletal Muscle: II. The Outward Currents
Authors: Yamamoto Daisuke , Washio Hiroshi
Published: April 2021

Two components of outward currents were investigated under voltage clamp conditions in Tenebrio muscle fibres. The instantaneous current-voltage relation for the transient outward current showed outward rectification. The tail currents for the delayed outward currents were made up of either one or two exponential components. The activation process for the delayed current was analysed using positive tails that decayed with a simple exponential time course. The delayed current was half-activated at about + 35 mV. Two rate constants for activation are both monotonic functions of membrane potential. The reversal potential for the delayed current was only partially dependent on the external K-concentration. The role of the two outward currents in the production of the action potential was discussed.
Electrically Evoked Course Control in the Fly Calliphora Erythrocephala
Authors: Blondeau Jean
Published: April 2021

Neurones in the optic ganglia of free-moving and fixed Calliphora were electrically stimulated with extracellular microelectrodes. The maximum diameter of the stimulating focus was 20 μ m in the antero-posterior axis. Course control and landing manoeuvres could be elicited by stimulating in the lobula plate but not in the lobula or medulla. With stimulation in the vicinity of the H neurones, yaw responses were evoked. Direction of the response was dependent on stimulation polarity. This supports the hypothesis that H neurones mediate optomotor responses. Stimulation in the posterior part of the lobula plate, close to the V neurones, elicited pitch, lift and thrust responses as well as landing reactions.