bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interspike Interval Relationship Among Flight Muscle Fibres in Drosophila
Authors: Koenig J. H. , Ikeda Kazuo 
Published: April 2021

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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.
Iodine Compounds and Fertilisation
Authors: Carter G. S. 
Published: April 2021

ABSTRACT
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

ABSTRACT
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.