bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some In Vivo and In Vitro Characteristics of Aplysia Californica Haemolymph*
Authors: Defur P. L. , Lukowiak Ken 
Published: April 2021

ABSTRACT
The nervous system of the opisthobranch mollusc, Aplysia californica Cooper has been extensively studied and a great deal is known about the electrophysiological properties of a number of identifiable neurones (see Kandel, 1976, 1979). A variety of synaptic and electrical connections have been mapped, permitting identification of the mode in which nervous control is exerted over certain motor functions. Substantially less is known regarding other physiological systems of Aplysia (Kandel, 1979), particularly the respiratory system, and this limits the description of how nervous control is affected by internal physiological state. Chalazonitis & Nahas (1965) reported data for haemolymph pH, CO2 tension and O2 tension in the related species, Aplysia fasciata, and Bevelaqua et al. (1975) identified the respiratory pigment, haemocyanin, in the haemolymph of A. californica. However, there has been no detailed study of in vivo oxygen levels or acid-base status of A. californica. Neither are there any data for the in vitro properties of A. californica haemolymph, such as oxygen carrying capacity, oxygen affinity or buffering properties. Such data are of particular importance in A. californica, for two reasons. Firstly, motor function, such as the often-studied gill withdrawal reflex, may be directly influenced by factors such as pH, or as are the respiratory performances of other marine invertebrates (Mangum & Burnett, 1975; McMahon & Wilkens, 1975; Bayne, 1976; Batterton & Cameron, 1978). Secondly, Chalazonitis (1974) has shown clearly that membrane potential, spike frequency and membrane resistance of many single cells in A. fasciata are directly affected by pH, and of the bathing fluid. Therefore, the present study was undertaken to describe some of the in vivo and in vitro properties of the haemolymph of A. californica with regards to acid-base status and oxygenation characteristics.
Osmoregulation in Salmon and Sea Trout Alevins
Authors: Talbot C. , Eddy F. B. , Johnston J. 
Published: April 2021

ABSTRACT
Changes in survival, body-water content, body electrolyte concentration and Na+ turnover rates were studied in alevins of Atlantic salmon (Salmo salar L.) and sea trout (Salmo trutta L.) at different developmental stages following exposure to various dilutions of sea water. In 100% sea water, salmon alevins at 9 days post-hatch survived approximately 6 h, and sea trout alevins 13 days post-hatch survived approximately 4 h. In both species, survival in hyperosmotic media decreased and rates of dehydration and Na+ turnover increased with age and development. The progressive change in resistance to osmotic stress is associated with a decrease in body surface area occupied by the relatively impermeable vitelline membrane and to the development of functional gills, leading to an increase in permeability to water and salt.
Noninvasive Recording of the Mauthner Neurone Action Potential in Larval Zebrafish
Authors: Prugh John I. P. , Kimmel Charles B. , Metcalfe Walter K. 
Published: April 2021

ABSTRACT
We describe the identification of Mauthner (M –) cell action potentials in an intact zebrafish larva, utilizing recording electrodes located outside the fish: The externally recorded spike occurs at approximately the same time, and its waveform changes with recording site in the same way, as the extracellular M-spike recorded within the central nervous system.The externally recorded M-spike may be readily distinguished from other forms of neural activity.The M-spike can be identified in recordings from unrestrained larvae.
This finding permits the direct study of M-cell function in the freely behaving animal.
Intermittent Gliding in the Hunting Flight of the Kestrel, Falco Tinnunculus L
Authors: Videler J. J. , Weihs D. , Daan S. 
Published: April 2021

ABSTRACT
The hunting flight of the kestrel (Falco tinnunculus) consists of short bouts of flight at wind speed against the wind with the eyes in a fixed position relative to the ground, and of short flights from one such position to the next.
High speed films taken with a camera in a fixed position of a hunting kestrel of known weight and dimensions, allow estimates to be made of the amount of energy required for this behaviour.
A theoretical model shows how a bird could economise by alternating flapping flight with short gliding bouts, without changing the position of the eyes above the ground, by mere displacement of the centre of gravity relative to the head. High speed film data confirm predictions from this model.
Electrophysiological and Morphological Identification of Action Potential Generating Secretory Cell Types Isolated from the Salivary Gland of Ariolimax
Authors: Goldring James M. , Kater Joanne W. , Kater Stanley B. 
Published: April 2021

ABSTRACT
The salivary glands of the terrestrial slug, Ariolimax, are composed of several morphologically distinct cell types which are observable in thin pieces of living glands and in sectioned tissue viewed with the light or electron microscope. ‘Blind’ penetration via microelectrode into the gland reveals different classes of electrical activity including: (1) cells with fast action potentials; (2) cells with slow action potentials; and (3) cells with large resting potentials but which display only delayed rectification. After isolation of cells by enzymatic dissociation we could electrophysiologically characterize individual cell types and relate these to cell types identified morphologically in the living gland and under the light and electron microscopes. Microelectrode recordings from identified cell types have demonstrated: (1) the large granule cell type (granule diameter = 8–12μm) displays a characteristic long duration, slow rise time action potential whose inward current is primarily carried by Ca2+ ; (2) the medium granule cell type (granule diameter = 3–6 μm) displays only delayed rectification and (3) the small granule cell type (granule diameter = 1–2 μm) displays fast rise time, short duration action potentials whose inward current is also carried primarily by Ca2+ ions.
The finding that morphologically distinct cell types display distinct electrical activity may indicate that different secretory products are released only under a specific set of conditions associated with changes in membrane potential.
The Interaction of Environmental Calcium and Low pH on The Physiology of the Rainbow Trout, Salmo Gairdneri
Authors: McDONALD D. G. , Walker R. L. , Wilkes P. R. H. 
Published: April 2021

ABSTRACT
Adult rainbow trout, acclimated to external calcium concentrations ranging from 60–5700 μequiv/1, were exposed to pH 4·0–4·1 for 44 h. Initially, this exposure provoked massive net losses of sodium and chloride across the gills which arose through a combination of an inhibition of active transport and, more importantly, a stimulation in diffusional efflux. Subsequently, ion losses declined substantially, largely due to a rapid decline in passive efflux but also to a slower, partial recovery in sodium transport. External calcium concentration was virtually without effect on ion fluxes either prior to or following acid exposure but had a definite effect during acid exposure. This effect was initially upon the ratio of Cl− to Na+ loss and later upon the degree of inhibition of sodium and chloride transport. Possible mechanisms to explain the complex interactions of calcium and pH are proposed.
The Role of An Identified Brain Neurone in Mediating Optomotor Movements in A Moth
Authors: Rind F. Claire 
Published: April 2021

ABSTRACT
Completely unrestrained moths show an optomotor turning response to horizontal movement during pre-flight warm up or flight. As the moth warms up there is a sequential recruitment of first neck, then abdominal, leg and finally some wing muscles, into the optomotor turning response. Extracellular motoneurone spikes were recorded from neck muscles during optomotor stimulation. As the stimulus is oscillated from side to side, motoneurones on the ipsilateral side are excited. The latency of this response increases greatly in dim light. Flight motoneurones were not observed to spike in response to movements of the optomotor stimulus, but subthreshold oscillations of 5–10 mV, in phase with the response of the identified optomotor interneurone DI, were observed. Three motoneurones, the second pleuroaxillary, the subalar and the dorsal longitudinal to the more medial, ventral fibre bundle, showed depolarizations in phase with the response of the ipsilateral DI interneurone. Synaptic potentials in these motoneurones followed action potentials in DI, suggesting that DI provides a direct, excitatory input to them. An excitatory postsynaptic potential (EPSP) from D1 sums with a steady depolarization of all three directly postsynaptic motoneurones to produce an action potential.
The Transport of Orthovanadate and Similar Oxyanions in Relation to Salt and Water Transport Across the Isolated Intestine of the Common Eel, Anguilla Anguilla
Authors: Bell M. V. , Kelly K. F. , Sargent J. R. 
Published: April 2021

ABSTRACT
An intestinal preparation from the common eel (Anguilla anguilla) was characterized for both mucosal to serosal and serosal to mucosal transport of water, alanine, sodium and chloride. The preparation showed a net outflux of water and a net influx of alanine, and no net fluxes of sodium or chloride. The influxes of all four substances and the outflux of water were inhibited by ouabain, while the outfluxes of alanine, sodium and chloride were increased by ouabain. Influxes and outfluxes of the oxyanions orthovanadate, phosphate, arsenate, sulphate, selenate and chromate were measured over a range of concentrations from 10−8M to 10−4M. The entry of each anion was dependent on the mucosal concentration, not saturable within the concentration range used or competitive with chloride. There were no net fluxes of these anions and pertechnecate from solutions containing equal mucosal and serosal concentrations of the anion.
Adrenergic Control of Oxygen Transfer in Perfused Gills of the Cod, Gadus Morhua
Authors: Pettersson Knut 
Published: April 2021

ABSTRACT
A perfused and ventilated gill preparation is described in which the pO2 of the perfusion medium and the irrigating water is controlled. Dorsal aorta effluent pO2 and flow were measured together with the branchial vascular resistance.
Decreasing pO2 in the perfusion fluid caused increased branchial vascular resistance, probably by constriction of efferent lamellar arterioles, α-adrenoceptor stimulation caused constriction of arteriovenous connections and of efferent lamellar arterioles, and enhanced oxygenation of the perfusion fluid. β-adrenoceptor stimulation also increased O2 transfer, but to a lesser extent.
It is suggested that both hypoxia and α-adrenoceptor stimulation improved O2 transfer via constriction of efferent lamellar arterioles. Both stimuli may also increase systemic blood flow by constriction of the arteriovenous connections, although such an effect of hypoxia has not been clearly shown, β-stimulation probably increased O2 transfer by dilation of afferent lamellar arterioles, thereby causing recruitment of unperfused lamellae.
Copper and Zinc Inhibit Chloride Transport Across the Opercular Epithelium of Seawater-Adapted Killifish Fundulus Heteroclitus
Authors: Crespo Sílvia , Karnaky Karl J. 
Published: April 2021

ABSTRACT
Effects of heavy metals on osmoregulation in aquatic organisms have recently been reviewed by Bouquegneau & Gilles (1979). Whereas most of the data in the literature deal with the toxic effects of mercurials, only a few reports can be found on the toxicity of essential trace elements such as Cu and Zn. Rainbow trout exposed to lethal (Skidmore, 1970) and sublethal (Watson & Beamish, 1980) concentrations of Zn maintain a relatively constant internal ionic environment. On the other hand Lewis & Lewis (1971) showed, in the channel catfish, a decreased osmolarity of blood serum after treatment with either Cu or Zn, and Katz (1979) reported an increased Na efflux in freshwater teleosts exposed to heavy metals. An increased gill Na, K-ATPase activity was described in the Zn-treated rainbow trout (Watson & Beamish, 1980). Shephard & Simkiss (1978) showed, in the same species, an increase in the gill protein content of fish exposed to Cu and Zn. These data agree with reports from Cu-treated winter flounder (Baker, 1969) and from Zn-treated dogfish (Crespo, Soriano, Sam-pera & Balasch, 1981; Crespo, 1982) each of which shows an increase in the number of the gill chloride cells.
Relationship Between Haemoglobin O2 Affinity and the Ventilatory Response to Hypoxia in the Rhea and Pheasant
Authors: Boggs Dona F. , Birchard Geoffrey F. 
Published: April 2021

ABSTRACT
The ventilatory response to hypoxia appears to be controlled largely by carotid body chemoreceptors in birds, as it is in mammals, and the stimulus to these chemoreceptors is probably the partial pressure of oxygen in the arterial blood (Bouverot, 1978; Bouverot, Douguet & Sebert, 1979). There are, however, interspecific differences in the threshold arterial stimulating the hypoxic ventilatory response. Black & Tenney (1980) found that a high-altitude species, the bar-headed goose, initiates an increase in ventilation at a lower arterial than a lowland species, the Pekin duck. The bar-headed goose also has a higher affinity haemoglobin, presumably as an adaptation to its high altitude habitat. Van Nice, Black & Tenney (1980) noted that when the ventilatory response to hypoxia is expressed in terms of the percent saturation of haemoglobin in arterial blood , the bar-headed goose and Pekin duck exhibit a similar threshold . It seems unlikely that the receptors sense haemoglobin O2 saturation directly and experimental reductions in O2 content do not stimulate ventilation in the duck (D. F. Boggs, unpublished observation). Nonetheless a relationship between the threshold of the ventilatory response to hypoxia and the ‘knee’ of the oxyhaemoglobin dissociation curve would be a reasonable evolutionary development in both birds and mammals, as Van Nice et al. (1980) have pointed out. If threshold arterial for the hypoxic ventilatory response were an interspecific constant, then those species with relatively high-affinity haemoglobins would be responding prematurely, and, therefore, ‘wastefully’, whereas those with relatively low-affinity haemoglobins would be in danger of suffering substantial arterial unsaturation before the ventilatory response is initiated. The latter eventuality would be particularly hazardous for tissue oxygen supply in those animals with low affinity haemoglobins, since these animals are in most cases small, with high weightspecific metabolic rates (Lutz, Longmuir & Schmidt-Nielsen, 1974; Schmidt-Nielsen & Larimer, 1958).
Selective Recruitment of Interganglionic Interneurones During Different Motor Patterns in Pleurobranchaea
Authors: Cohan Christopher S. , Mpitsos George J. 
Published: April 2021

ABSTRACT
The buccal and anterior head structures of the mollusc, Pleurobranchaea, participate in several types of behaviour which are generated largely by rhythmic activity produced in the brain and buccal ganglia. This paper examines the neuronal mechanisms (1) by which motor output from these ganglia is coordinated, and, (2) which underlie the generation of different motor patterns. Preliminary experiments indicated that the neuronal circuitry which produces the rhythms is contained in each of the paired buccal ganglia. The timing characteristics of the rhythms arise in the buccal ganglia and the pattern and symmetry of motor output in the brain roots are determined by activity in buccal cerebral interneurones (BCI) within the buccal ganglia.
Intracellular recordings showed that unique properties of individual cells within two pools of interganglionic interneurones, the BCI and paracerebral cells (PCC), determine in part the types of coordinated patterns that are produced. The BCI, which project to the brain, are a heterogeneous population of cells, based on : ( 1 ) the activity they evoke when they are depolarized ; and (2) their activity patterns during rhythms that are evoked by buccal nerve stimulation. Evidence is presented to show that BCI are selectively recruited to produce the distinguishing features of different motor patterns. Similarly, the PCC were found to be a diverse group of cells that exert both excitatory and inhibitory effects on the nervous system. Stimulation of excitatory PCC in isolated nervous systems elicited a variety of activity patterns. These data suggest that the PCC may selectively recruit the BCI to produce different motor patterns and that differences in patterns can be attributed, in part, to the unique properties of individual cells within each pool of interneurones.
Allosteric Interactions Governing Oxygen Equilibria in the Haemoglobin System of the Spiny Dogfish, Squalus Acanthias
Authors: Weber Roy E. , Wells Rufus M. G. , Rossetti John E. 
Published: April 2021

ABSTRACT
The oxygenation-linked, allosteric interactions of erythrocytic organic phosphates and urea with the haemoglobin (Hb), and the functional significance of the Hb multiplicity, were studied in an elasmobranch, Squalus acanthias.
The autochthonous red cell nucleoside triphosphates (NTP) ATP and GTP (guanosine triphosphate) strongly depress O2 affinity of the stripped (cofactor-free) Hb and increase cooperativity in O2 binding. As previously found in teleost Hbs, GTP exerts a greater effect than ATP at the same concentration. Urea, in contrast, increases O2 affinity and depresses cooperativity. It also antagonizes the modulator effectivity of NTP at physiological NTP/Hb concentration ratios.
Deoxygenation of the Hb raises blood pH. This Haldane effect contrasts with earlier findings for Pacific specimens, but accords with the presence of a Bohr effect (Φ = Δlog P50/ΔpH).
S. acanthias Hb resolves into six main components (three pairs) on the basis of isoelectric point. There is no evidence for radical functional differentiation as found in teleosts with electrophoretically anodal and cathodal Hb components.
The physiological implications of the findings and the possible molecular mechanisms basic to the NTP and urea effects are discussed.
The Ionic Basis of the Depolarizing Mechanoreceptor Potential of Paramecium Tetraurelia
Authors: Satow Youko , Murphy A. Don , Kung Ching 
Published: April 2021

ABSTRACT
A depolarizing receptor potential produced by mechanical stimulation was studied in pawn mutants of Paramecium tetraurelia bathed in TEA solution. The potential was dependent upon the strength of the mechanical stimulation until a maximum response was reached. The maximum value was dependent on the concentration of external Ca2+. Discounting the change in resting potential (attributable to change in surface charge), the maximal receptor potential changed by 20 mV per 10-fold change in Ca2+ at the concentrations tested, confirming the result of Ogura & Machemer (1980) that Ca2+ is the major natural cation that carries the receptor current. Mg2+, Sr24-, Ba2+ and Mrr+ can substitute for Ca2+ in the generation of the depolarizing receptor potential. Except for Mn2+, this result is similar to that of de Peyer & Deitmer ( 1980) for Stylonychia. Na+, K+, Li+ and TEA+ cannot effectively substitute for Ca2+.
Ocellar Input to the Flight Motor System of the Locust: Structure and Function
Authors: Rowell C. H. F. , Pearson K. G. 
Published: April 2021

ABSTRACT
This paper deals with the physiology, anatomy and function of the following classes of neurones in the locust Schistocerca : (a) neurones carrying ocellar information to the pterothorax (Descending Ocellar Neurones, DONs), (b) mesothoracic Flight Motor Neurones (FMNs), (c) a heterogenous class of inter- and intraganglionic thoracic interneurones which receive input from the DONs, here called Thoracic Ocellar Interneurones (TONs) without prejudice to their other possible inputs and functions. The thoracic arborizations of five different DONs are characterized. All project unilaterally to the pterothorax, four out of five to the ipsilateral mesothoracic or meso- and metathoracic ganglia. All are phasic OFF units, responding to stimulation either of one lateral ocellus or of the medial ocellus or of both, but none responded to the cephalic wind-hairs. Four of the five DONs showed no response decrement at stimulus frequencies up to 80 Hz. One showed habituation, recovery during a rest interval, and dishabituation in response to mechanical stimulation of a leg. There are more than six DONs, probably more than ten, in each connective. All types of recorded mesothoracic FMNs receive monosynaptic EPSPs from the DONs and/or delayed IPSPs (presumably via TONs) in at least some animals. The pattern of connection is compatible with the hypothesis that a roll or downward pitch deviation induces compensating movements of the wings to correct the deviation. Many of these DON/ FMN connections were, however, only occasionally recorded. None of the ocellar EPSPs recorded in the FMNs elicited spikes. Most TONs receive monosynaptic EPSPs from one or more DONs, sometimes causing them to spike. Two receive delayed IPSPs, presumably via other TONs. At least one third of the recorded TONs spike in phase with either elevator or depressor FMNs during stimulated flight. Intraganglionic TONs in the mesothorax are all unilateral. Their anatomy suggests that they distribute input from DONs to various combinations of ipsilateral FMNs. Interganglionic TONs can be either unilateral or bilateral in the mesothoracic ganglion, and project unilaterally to the metathoracic (or rarely the prothoracic) ganglion, where at least one makes inhibitory synapses with a FMN. Phasic ocellar information reaches the FMNs by two routes. One produces fast subthreshold PSPs in the FMNs directly. The other produces spikes and PSPs in thoracic interneurones, at least some of which are phasic-ally active during flight and are presynaptic to FMNs. The roles of the two pathways are discussed.
Variability in the Structure of an Identified Interneurone in Isogenic Clones of Locusts
Authors: Steeves John D. , Pearson Keir G. 
Published: April 2021

ABSTRACT
Several studies have shown that there can be considerable variability in the morphology of identified neurones. In a recent investigation (Pearson & Goodman, 1979) a great degree of variability was observed in the axon branching patterns of the descending contralateral movement detector (DCMD) interneurones of locusts. Corresponding to the variation in the structure of DCMD was a large variation in the synaptic connections made by this interneuroen; the absence of a monosynaptic connection always correlated with the lack of the appropriate axonal branch of DCMD.
Since this variability could be related to genotypic differences, we investigated the structure and synaptic connections of DCMD in individuals from several different isogenic clones of the locust Schistocerca gregaria. Within a single group of clones the variability in the axonal branching patterns and synaptic connections of DCMD was generally less than that between different clones or in sexually reproduced control animals. More significantly, a few of the clonal groups had consistently unique branching patterns and concomitant synaptic connections. Nevertheless, there was still some variability in the structure of DCMD within each clone. We conclude from these observations that differences in genotype can influence the morphology of individual neurones at the relatively refined level of axonal branching patterns and consequently the neurone’s synaptic connections. However, due to the variability of DCMD structure within a single clone, epigenetic factors must also determine the pattern of axonal branching.