bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition by Recurrent Excitation: A Mechanism for Spike Synchronization in A Network of Coupled Neuronal Oscillators
Authors: Egelhaaf M. , Benjamin P. R. 
Published: April 2021

ABSTRACT
Two bilateral clusters of 2–7 peripheral-neurones (‘Peripheral Bursters’) are located on the left and right branches of the post-buccal nerve of the snail Lymnaea stagnalis quite separate from the ganglia of the CNS (Carriker, 1946; Egelhaaf, 1981 a, A; M. Egelhaaf & P. R. Benjamin, in preparation). Isolation of single cells from these peripheral clusters shows that they are endogenously capable of bursting (Egelhaaf, 1981a; M. Egelhaaf & P. R. Benjamin, in preparation). In addition, the cells within one cluster as well as in heterolateral clusters are electrotonically coupled to one another, the coupling being stronger in the former case. Detailed evidence for this is given elsewhere (Egelhaaf, 1981a; M. Egelhaaf & P. R. Benjamin, in preparation). This has allowed the investigation of the interactions between the endogenous oscillatory properties of single cells and network properties due to electrotonic coupling in a system which can easily be separated from the influence of other neurones (Egelhaaf, 1981a, A; M. Egelhaaf & P. R. Benjamin, in preparation). In this paper interactions among homolateral Peripheral Bursters will be discussed and it will be shown phenomenologically how spike synchrony can be established within bursts of cells which tend to fire asynchronously due to slightly different levels of excitability.
Fast-Start Resistance of Trout
Authors: Webb P. W. 
Published: April 2021

ABSTRACT
Rainbow trout (Salmo gairdneri Richardson) with a body mass of 268 ± 36 g were used to determine the acceleration resistance of a fish during fast-starts. The mass of the fish was increased by mass loads of 75, 150, 225 and 335 g. The loads were made from nesting horseshoe-shaped brass saddles which fitted snugly over the fish so that the extra mass was equally distributed in all planes about the stretched-straight body centre of mass. The weight of the saddles was taken up by a 291 cm line attached to the dorsal surface of the fish above its centre of mass. The other end of the line was attached to the ceiling. The performance of the fish with and without saddles was measured during fast-starts, initiated by a 1 v.cm−1 d.c. electric shock. Performance was determined in terms of the distance travelled with time, measured from high speed movie films (240 frames s−1). The relationships between distance travelled and time were described by power functions for fish with and without mass loads. Exponents were not significantly different for the fish with various mass loads showing that frictional and form drag made negligible contributions to acceleration resistance in a fast-start. The resistance of the fish in a fast-start, due to fish mass and a resistance component of added water mass (apparent mass), was calculated using hydromechanical theory for representative fast-start sequences. The apparent mass was estimated at 320 g, which is 1·2 × fish body mass.
Physiological and Ultrastructural Studies on the Longitudinal Retractor Muscle of a Sea Cucumber Stichopus Japonicus: I. Factors Influencing the Mechanical Response
Authors: Sugi H. , Suzuki S. , Tsuchiya T. , Gomi S. , Fujieda N. 
Published: April 2021

ABSTRACT
The physiological properties of contraction and the ultrastructure of the longitudinal retractor muscle (LRM) of a sea cucumber Stichopus japonicus were studied to give information about the sources of activator Ca in echinoderm somatic smooth muscles. The magnitude of ACh- and K-induced contractures was dependent on [Ca]0, and both contractures were eliminated in Ca-free solution, while they were not markedly influenced by Mn ions (10 mM) and low pH (4·0). Procaine (5 mM) decreased ACh-contracture tension with a long lasting after-effect, which was removed by the application of high [K]o. ACh-contractures were markedly potentiated shortly after the termination of mechanical response to the removal of external Na. The LRM could also be made to contract by caffeine (10 mM), the removal of external divalent cations and hypertonic solutions, indicating the presence of intracellularly stored Ca available for the activation of the contractile mechanism. The LRM fibres contain poorly developed intracellular membranous structures. The inner surface of the plasma membrane and small vesicles located underneath the plasma membrane seem to be two of the sources of activator Ca.
Physiological and ultrastructural studies on the longitudinal retractor muscle of a sea cucumber Stichopus japonicus. II. Intracellular localization and translocation of activator calcium during mechanical activity
Authors: Suzuki S. , Sugi H. 
Published: April 2021

ABSTRACT
The intracellular localization and translocation of activator Ca in the longitudinal retractor muscle (LRM) of a sea cucumber Stichopus japonicus were studied by fixing the LRM in a 1 % OsO4 solution containing 2 % K pyroantimonate. In the resting LRM fibres, electron-opaque pyroantimonate precipitate was mostly localized along the inner surface of the plasma membrane and at the subsarcolemmal vesicles in close apposition to the plasma membrane. In the LRM fibres fixed during the mechanical response to ACh and high [K]o, the precipitate was diffusely distributed in the myoplasm in the form of numerous particles with corresponding decrease in the amount of the precipitate at the peripheral structures. Electron probe X-ray microanalysis showed the presence of Ca in the precipitate, indicating that the precipitate provides a valid measure of Ca localization. These results accord with the view that, in the LRM, the contractile mechanism is activated by the release of Ca from the intracellular structures as well as by the inward movement of extracellular Ca.
Properties of synapses made by IVN command-interneurones in the stomatogastric ganglion of the spiny lobsterPanulirus interruptus
Authors: Sigvardt Karen A. , Mulloney Brian 
Published: April 2021

ABSTRACTThe IVN command interneurones synapse directly onto 11 identified neurones in the stomatogastric ganglion : the two pyloric dilators (PDs), the anterior burster (AB), ventricular dilator (VD), the four gastric mill neurones (GMs), the two lateral posterior gastric neurones (LPGNs), and Interneurone 1 (Int 1). The IVN p.s.p.s in PD and AB are biphasic, and consist of a fast depolarizing component followed by a slower hyperpolarizing component. The hyperpolarizing component of this biphasic postsynaptic potential is inhibitory, and appears to be the result of a conductance increase to K+ and Cl-. The IVN p.s.p. in VD is excitatory and can drive VD one-for-one. The IVN p.s.p.s in GM and LPGN are inhibitory. The amplitude of a single p.s.p. is small but, at high frequency, summation of p.s.p.s holds the postsynaptic membrane potential below threshold. The facilitation characteristics of the p.s.p.s in each neurone are described. The functional significance of these synaptic characteristics is discussed in terms of the modification of motor output caused by a burst of the IVN interneurones.
Importance of Calcium And Magnesium Ions for Postexcitatory Hypersensitivity in the Jumping Spider (Menemerus) Eye
Authors: Tateda Shigeki Yamashita and Hideki 
Published: April 2021

ABSTRACT
Hypersensitivity of the anterior median eye of the jumping spider Menemerus confusus, following illumination, was unaffected by the concentration of Na+ or K+, was depressed by increase of Ca2+ concentration, and was dependent upon the presence of Mg2+. Sensitivity of the dark-adapted eye was also inversely related to Ca2+ concentration, but to a lesser extent.
Acid Tolerance and Effects of Sublethal Acid Exposure on Iono-Regulation and Acid-Base Status in Two CrayfishProcambarus ClarkiandOrconectes Rusticus
Authors: Morgan D. O. , Mcmahon B. R. 
Published: April 2021

ABSTRACTAcid-toxicity tests were performed using two crayfish species, Procambarus clarki Girard and Orconectes rusticus Girard to determine the median lethal pH (LC5O) after 4 days exposure to acid. Four-day LC50 values of pH 2*5-2-8 were observed, indicating that these animals are more acid-tolerant than most fish species. Haemolymph acid-base variables and major ion concentrations were measured during 4 days exposure of P. clarki to sublethal acid H2SO4, pH 3-8) levels. A major haemolymph acidosis was observed. While minimal changes were seen in haemolymph [Cl−], [K+], and [Mg2+], haemolymph [Na+] decreased. Haemolymph [Ca2+] increased significantly during acid exposure, suggesting that dissolution of exoskeletal carbonate buffers was being employed as a compensatory mechanism for the acidosis; this process would be expected to contribute to exoskeletal rigidity problems in the long term.
The effect of temperature on the tension responses of the anterior byssal retractor muscle (abrm) ofMytilus edulis
Authors: Linehan Catherine M. 
Published: April 2021

ABSTRACTThe effect of ambient temperature on the response of the ABRM of Mytilus edulis to acetylcholine and 5-hydroxytryptamine has been examined. As the ambient temperature was increased, the latent period and the maximum tension developed decreased while the rate of tension development and the rate of relaxation increased. The relationship between temperature and the rate of tension development showed three distinct linear phases from 2–25, 25–35 and 35–45 °C. The reduction in peak tension with temperature could also be resolved into three portions from 2–25, 25–40 and above 40 °C. As the temperature was increased above approximately 27 °C the rate of relaxation in the absence of 5-HT approached the rate of relaxation in the presence of 5-HT. The significance of these results and possible explanations for them are considered.
Effects of Body Size and Slope on Sprint Speed of a Lizard (Stellio (Agama) Stellio)
Authors: Huey Raymond B. , Hertz Paul E. 
Published: April 2021

ABSTRACTThe agamid lizard Stellio stellio L. accelerates quickly and reaches maximum speed over short distances. Maximum speed on the level is proportional to body mass to the power. This relation differs from predictions based on an interspecific scaling model of “geometric” similarity (M0) and is intermediate between predictions based on interspecific scaling models of “elastic” similarity and of “static stress” similarity . Maximum speed was also measured on slopes ranging from –15° to + 60°. The effect of slope on speed varies with body mass. The maximum speed of large lizards decreases on steep slopes, but that of small lizards is remarkably independent of slope.
Actions of insect toxin and other toxins derived from the venom of the scorpion Androctonus australis on isolated giant axons of the cockroach (Periplaneta americana)
Authors: Pelhate M. , Zlotkin E. 
Published: April 2021

ABSTRACT
Insect toxin, mammal toxins I and II and crustacean toxin were obtained from the venom of the scorpion Androctonus australis. Their effects on the isolated giant axon of the cockroach Periplaneta americana were investigated by current-clamp and voltage-clamp techniques. ‘ In current-clamp conditions, mammal toxins and crustacean toxin (1·3–13 μM) induced a large prolongation of the falling phase of the evoked action potentials. Insect toxin (0·13–3·3 μM) induced a progressive slow depolarization of the membrane potential and repetitive firing of action potentials. No changes in the time-course of the action potential were induced by insect toxin. In voltage-clamp conditions, mammal and crustacean toxins induced a slowing of the turn-off of the transient inward sodium current, with either no change or a small increase in the peak sodium current. Insect toxin by contrast induced an increase in the peak sodium current and a slowing of the sodium current turn-off, this effect being greatest at lower values of the clamped membrane voltage. It is concluded that the repetitive activity induced by insect toxin results from a voltage-dependent modulation of sodium inactivation coupled with an increase in both the resting and active sodium permeabilities of the cockroach axonal membrane.
Eye Movements of the Crab Leptograpsus Variegatus Elicited By Imposed Leg Movements
Authors: Varju D. , Sandeman D. C. 
Published: April 2021

ABSTRACT
The horizontal component of eyestalk movements elicited by moving the legs of blinded crabs is described. The animals’ bodies were fixed to a stand and the legs were supported on either a sphere or platform and subjected to movement around the three major axes (yaw, pitch, and roll). Both sinusoidal and stepped movements of the legs were studied. The effect of moving the legs on one side only, homolateral or contralateral to the eyestalk was also studied. The eyestalk excursion elicited by sinusoidal leg excursion around the vertical axis (yaw) is a nearly linear function of the leg excursions over the range of 1–40° peak to peak at 0·1 Hz. The amplification of the system is about 0·4 when the animal’s legs are supported on a ball, and 0·8–1·0 when the legs are supported on a platform. The frequency response of the system to yaw is nearly flat for eye excursions of 16° peak to peak, over the range of 0·005–0·1 Hz. The visual system has a powerful braking effect on the eye rotation, when this is generated by the imposed leg movements. Eyestalk responses to yaw can be interpreted to be compensatory in that they stabilize the eyes in space in freely moving animals. Eyestalk movements to pitch and roll are complex. In roll, their horizontal component indicates the presence of considerable rectification in the leg proprioceptor-eye system. The functional significance of the eyestalk movements in the horizontal plane is discussed.
Movements and Motor Patterns of the Buccal Mass ofPleurobranchaeaDuring Feeding, Regurgitation And Rejection
Authors: McClellan Andrew D. 
Published: April 2021

ABSTRACTFeeding, regurgitation, and rejection in the marine gastropod Pleuro-branchaea all involve similar but not identical rhythmic movements of buccal mass structures such as the radula, jaws and lips. The part of the motor pattern which produces rhythmic radula movement, as recorded in the major external muscles of the buccal mass of behaving semi-intact preparations, was similar during the three different types of behaviour, suggesting that they share a common motor-pattern generator. Other parts of the motor pattern were only obviously different during the vomiting phase of regurgitation. Differences in the function and motor patterns of feeding and rejection are presumably accounted for by differences in the activity of muscles which could not be recorded from in this study (e.g. jaw muscles). A general conclusion is that buccal rhythms in gastropods cannot automatically be assumed to underlie feeding, and this is particularly true for dissected preparations which do not execute a clear behavioural response. It would be necessary either to record motor activity that is unique for a given behaviour, or to employ preparations which execute unambiguous behavioural responses.
Anatomy of Motoneurones Innervating Mesothoracic Indirect Flight Muscles in the Silkmoth,Bombyx Mori
Authors: Kondoh Y. , Obara Y. 
Published: April 2021

ABSTRACTThe anatomy and innervation of mesothoracic indirect flight muscles, dorsal longitudinal (DLM) and dorsoventral muscles (DVM) are described. The major DLMs depress the forewing, the major DYMs elevate it. The morphology of the motoneurones and unpaired median neurones (UM-neurone) innervating these muscles was investigated by back-filling with cobalt. The DLMs are innervated by eight paired motoneurones and one UM-neurone: one of these motoneurones has its cell body in the contralateral side of the mesothoracic ganglion, and the others have theirs in the ipsilateral side of the prothoracic ganglion. The DVMs are innervated by nine paired motoneurones and one UM-neurone, with their cell bodies in the ipsilateral and the median portion of the mesothoracic ganglion, respectively. All of the paired DLM and DVM motoneurones have many dendritic processes, mainly in the dorso-ipsilateral neuropile of the ganglia, but the DLM motoneurones also have processes in the contralateral neuropile. Each UM-neurone has its cell body in the postero-medial cortex of the mesothoracic ganglion, extending a single median neurite anteriorly to the dorsal neuropile where it bifurcates to form a right and left axon. The arrangement of the mesothoracic indirect flight motoneurones in different insect orders is discussed in terms of the neural organization of the flight system.
Mechanical Design of Spicule-Reinforced Connective Tissue: Stiffness
Authors: Koehl M. A. R. 
Published: April 2021

ABSTRACTMany animals from different phyla have, embedded in their pliable connective tissues, small bits of stiff material known as spicules. The tensile behaviour of spicule-reinforced connective tissues from various cnidarians and sponges, as well as of model spiculated ‘tissues’, is here investigated in order to elucidate the effects on mechanical properties of spicule size and shape, and of their packing density and orientation within a tissue. The main conclusions are :Spicules increase the stiffness of pliable connective tissues probably by mechanisms analogous to those by which filler particles stiffen deformable polymers -local strain amplification, and interference with molecular rearrangement in response to a load. The greater the volume fraction of spicules, the stiffer the tissue. The greater the surface area of spicules per volume of tissue, the stiffer the tissue. Thus, a given volume of spicules of high surface-area-to-volume-ratio (S/V) have a greater stiffening effect than does an equal volume of spicules of low S/V. Furthermore, a high volume fraction of large spicules in a tissue can have the same stiffening effect as a lower volume fraction of smaller spicules. Spicules that are anisometric in shape have a greater stiffening effect parallel to their long axes. Spicules with very high aspect ratios appear to act like reinforcing fibres -stress is transferred by shearing from the pliable matrix to the stiff fibres, which thus bear in tension part of the load on the composite. Spicule-reinforced tissues exhibit stress-softening behaviour, which is more pronounced in heavily spiculated tissues.
The Function of Chemo- and Mechanoreceptors in Lobster (Homarus Americanus) Feeding Behaviour
Authors: Derby Charles D. , Atema Jelle 
Published: April 2021

ABSTRACT
The behaviour of lobsters preying on live mussels (Mytilus edulis) was observed before and after chemosensory or chemosensory-mechanosensory deafferentation of different sensory appendages. Deafferentation of the antennules, leg tips, or maxillipeds (but not the carapace or proximal leg segments) interfered with feeding performance by causing an increase in the time necessary to crush a mussel after search initiation. In addition, deafferentation of the leg tips or the maxillipeds caused a decline in number of mussels crushed but for different reasons: leg-treated lobsters walked over the mussels without picking them up, whereas maxilliped-treated lobsters grasped the mussels as usual but either did not crush or did not eat them as readily as did normal lobsters. Deafferentation of leg chemoreceptors resulted in the same behavioural deficiencies as deafferentation of leg chemo- and mechanoreceptors, demonstrating that it is the leg chemoreceptors that are essential in releasing this grasping response. Chemoreceptors on different appendages of lobsters therefore fulfill different functional roles in their feeding behaviour.
Mechanism and Characteristics of Coxal Fluid Excretion in the Argasid TickOrnithodorus Moubata
Authors: Kaufman Susan E. , Kaufman William R. , Phillips John E. 
Published: April 2021

ABSTRACTAdult ticks (Omithodorus moubata Murray, Acari, Argasidae) were fed on human blood at 37 °C in a beaker covered with chicken skin. 14C-labelled inulin and 3–0[14CH3]glucose were rapidly cleared from haemolymph to coxal fluid ; the coxal tubule appeared not to reabsorb either substance. Glucose was reabsorbed from tubular fluid via a phlorrhizin-sensitive mechanism. Reabsorption of amino acids varied between o and 90 % but was greatest for those amino acids which were scarce in the meal. During normal feeding conditions, there was positive correlation between haemocoelic hydrostatic pressure and rate of coxal fluid excretion. Unilateral cannulation of a coxal organ so as to eliminate back pressure of a valve at the coxal orifice led to a twofold increase in rate of coxal fluid production compared to the contralateral side. The above data confirm that coxal fluid excretion occurs by a filtration resorption mechanism.
Protein and Glycoprotein Antifreezes in the Intestinal Fluid of Polar Fishes
Authors: O’grady S. M. , Ellory J. C. , DeVries A. L. 
Published: April 2021

ABSTRACTMeasurements of ion concentrations, freezing points and melting points of intestinal fluid were made for several Antarctic fishes and two North Atlantic species. These measurements indicated that plasma and intestinal fluid are nearly isosmotic. Freezing points of intestinal fluid were approximately 0·9 °C below the melting points, suggesting the presence of glycoprotein antifreeze within the intestinal fluid of the Antarctic fishes. Polyacrylamide gel electrophoresis and specific immunoprecipitation with glycoprotein antifreeze antibody confirmed the presence of appreciable quantities of antifreeze and showed that the major antifreeze fractions present in the intestinal fluid are low molecular weight glycopeptides.
Acid-Base Imbalance in Lizards During Activity and Recovery
Authors: Gleeson Todd T. , Bennett Albert F. 
Published: April 2021

ABSTRACTThe effects of treadmill exercise on oxygen consumption carbon dioxide production arterial blood lactate concentration ([L−]a), arterial blood pH and arterial gas tensions ( and ) were measured in 3 species of lizards (Varanus salvator, V. exanthematicus, Iguana iguana) Varanus salvator was exercised 45 min at an intensity which required 85% of its V. salvator utilized supplementary anaerobic metabolism during the first 10 min of this sustainable exercise, as evidenced by a 16 mmol/1 increase in [L−]a. Respiratory exchange ratios (R, where R =) exceeded 1·2 when [L−]a and [H+]a were maximal. One half of the accumulated lactate was removed from the blood during the remainder of the 45 min exercise period, while blood pH returned to resting levels. In a second set of experiments, high intensity exercise led to exhaustion after 5 to 10 min in all three species, resulting in large lactate ( +Δ [L−]a = 14–20 mmol/l) and hydrogen ion ( + Δ [H+]a = 23–57 nmol/l) accumulations. R values ranged from 1·2–1·8 at exhaustion. Recovery from both sustainable and non-sustainable exercise was characterized as a period of rapid lactate removal. Respiratory exchange ratios were low (0·3–0·5) as metabolic CO2 was retained, replacing depleted bicarbonate stores. We conclude that all three lizard species make ventilatory adjustments during and after exercise that minimize disturbances to resting hydrogen ion concentrations and acid-base balance. Varanus salvator demonstrate the ability to re-establish resting acid-base status during sustained exercise requiring 85% of their Changes in R appear to be a useful non-invasive indicator of net blood lactate accumulation.
A Gold-Plated Suction Electrode for Extracellular Recording and Dye Infusion
Authors: Theophilidis G. , Burns M. D. 
Published: April 2021

ABSTRACT
To record extracellular nerve activity, wires or polyethylene suction electrodes are commonly used, which are modified according to particular experimental requirements. For electrophysiological studies in a dissected animal, a length of the nerve under investigation may be lifted on to silver wires (Pearon, Stein & Malhotra, 1972), or a fine wire hook (Wilkens & Wolf, 1974), often under mineral oil. These methods produce good records but the mineral oil and the wires around the nerve and its associate muscle reduce the visibility of the preparation. This may cause difficulties when simultaneous records are required from other parts of a small preparation.