bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of escape tailflip in crayfish during backward walking and the defense posture
Authors: Beall SP , Langley DJ , Edwards DH 
Published: April 2021

ABSTRACTA major question in neuroethology is how animals coordinate transitions between incompatible behavior patterns. The recent demonstration that the lateral giant (LG) tailflip is inhibited during eating (Krasne and Lee, 1988) suggested to us that inhibition may play a general role in preventing maladaptive transitions between incompatible behavior patterns. We wished to determine whether the LG tailflip is inhibited during other incompatible behavior such as backward walking and the defense posture.
Integration of Colour Signals in the Medulla of the Swallowtail Butterfly Larva
Authors: Ichikawa Toshio 
Published: April 2021

ABSTRACTSpatial and chromatic properties of 25 types of medulla neurones which integrate input from different optical units (stemmata) of the larval eye in the swallowtail butterfly were examined by illuminating individual stemmata with chromatic stimuli. Eleven neurones received different types of colour (opponent) input from a few stemmata; thus, the receptive fields are spectrally heterogeneous. The stemmata dominating these complex neurones were usually located in the frontal (central) region of the eye. Seven neurones showed a relatively homogeneous spectral profile over the receptive field by receiving similar spectral input from two or three stemmata which were usually located in the dorsolateral (peripheral) region of the eye. Three of these simple units showed tonic or phasic responses. The remaining seven were also spectrally simple neurones but with larger receptive fields covering four to all six stemmata. Some units showed a spatial summation of responses or a spatial antagonism between central and peripheral or dorsal and ventral regions of the eye.
Characterization of Receptors Mediating The Actions of Dopamine on an Identified Inhibitory Motoneurone of the Cockroach
Authors: Davis Julian P. L. , Pitman Robert M. 
Published: April 2021

ABSTRACTThe effects of a number of dopaminergic agonists and antagonists upon the soma of a prothoracic inhibitory motoneurone of the cockroach (Periplaneta americana) have been recorded under voltage-clamp conditions. Dopamine generates inward currents that are extremely voltage-dependent: currents increase rapidly at membrane potentials more negative than about —120 to —150 mV and also show a peak at membrane potentials of approximately —20 mV. As a result of this voltage-dependence, dopamine induces a region of negative resistance in the current-voltage relationship of the neurone. The dopaminergic agonists apomorphine, bromocryptine, ergometrine and A-6,7-DTN mimic the action of dopamine on this neurone, all having a similar voltage-dependence to that of dopamine. The selective D-l receptor agonist SK&F 82526 and the D-2 agonist LY171555, however, were both inactive on the preparation. Responses to dopamine were suppressed by a number of D-l and D-2 receptor antagonists, indicating that the pharmacological profile of the dopaminesensitive receptor in this insect preparation is different from that of vertebrate dopamine receptors.
The Transmission of Bush-Cricket Calls in Natural Environments
Authors: Stephen R. O. , Hartley J. C. 
Published: April 2021

ABSTRACT
This study discusses the structure of the calls of bush crickets Steropleurus nobrei and examines the way the structure of records of a bush-cricket call, comprising pure tone bursts and bursts of white noise, changes as these sounds propagate through different environments. Measurements of the coherence and spectral composition at different distances from the sound source are made in open and thickly vegetated environments. The results show that coherent frequency components in reproductions of the records of the natural call propagate over greater distances than do other components. The results are discussed in relation to the possible sources of information contained in insect calls and how the environment degrades these information sources as the call propagates away from the source. The consequences of the structure of the calls on the properties of the auditory organs of bush crickets is also discussed.
Lactate Utilization By AnIn SituPerfused Trout Heart: Effects Of Workload And Blockers Of Lactate Transport
Authors: Milligan C. Louise , Farrell Anthony P. 
Published: April 2021

ABSTRACTLactate utilization was studied in an in situ perfused trout heart preparation that was capable of performing at levels similar to in vivo maximum cardiac performance. Hearts were perfused with modified Cortland saline containing 0.5 mmol l-1 iodoacetic acid (to block endogenous glycolysis) and varying amounts of lactate (1 or 10 mmol l-1). We confirmed previous observations that lactate utilization is limited by substrate availability. However, contrary to previous observations, exogenous fuel availability did not limit cardiac performance, even at the high workload. Furthermore, when plentiful (i.e. 10mmoll-1), exogenous lactate was preferred over endogenous fuel and was able to supply the heart’s energy requirements at both the low and high workloads. Pyruvate at 10fold greater concentration, had no apparent effect on lactate utilization at the high workload. α-Cyano-4-hydroxycinnamate (α-CIN) (2.5 mmol l-1) proved to be an unsuitable probe of lactate transport in the trout heart as it caused a reduction in both lactate utilization and cardiac performance. However, addition of 20 μmol l-1 isobutyl carbonyl lactyl anhydride or 100μmoll-1 4-acetamido-4 ′-isothiocyano-stilbene-2,2 ′-disulphonic acid (putative lactate transport blockers) to the perfusate virtually abolished lactate oxidation at the high workload without affecting cardiac performance. These observations suggest that lactate uptake by the in situ perfused trout heart is carrier-mediated.
Acid–Base Transport and Control in Locust Hindgut: Artefacts Caused by Short-Circuit Current
Authors: Thomson R. Brent , Audsley N. , Phillips John E. 
Published: April 2021

ABSTRACT
The commonly used method of passing short-circuit current (Isc) across insect epithelia through Ag-AgCl electrodes, without the use of salt bridges, leads to significant OH− production at the cathode (lumen side) when high currents are applied. The alkalization of the lumen previously reported when cyclic AMP was added to short-circuited locust hindgut is a result of this phenomenon rather than cyclic-AMP-mediated stimulation of acid-base transport in the hindgut. When salt bridges are used to pass short-circuit current across locust hindgut, acid secretion (JH) into the lumen equals alkaline movement (JOH) to the haemocoel side, and JH is similar under both open- and short-circuit conditions. JH is similar (1.5μequiv cm_2h_1) in recta and ilea. Addition of cyclic AMP inhibits JH across the rectum by 42–66 %, but has no effect on the ileum when salt bridges are used. Electrical parameters (Isc, Vt, Rt) reflecting hindgut Cl− transport (JC1) before and after stimulation with cyclic AMP are the same whether or not salt bridges are used. We found no evidence of any coupling between JcI and JH / JOH.
Distinct Receptors, Second Messengers and Conductances Underlying the Dual Responses to Serotonin in an Identified Leech Neurone
Authors: Sanchez-Armass Sergio , Merz David C. , Drapeau Pierre 
Published: April 2021

ABSTRACT
Pressure-sensitive mechanosensory (P) neurones of the leech Hirudo medicinalis produce two responses to serotonin (5-HT): activation of a Cl−conductance and of a non-selective monovalent cation conductance. The effects of channel blockers, the receptor pharmacology and the second-messenger dependence of these responses were studied in voltage-clamped P cells in culture. Antagonists were applied by superfusion and agonists by pressure ejection. Zn2+ (100μmoll−1) and H+ (pH 6.5 and lower) reversibly reduced the Cl−conductance activated by 5-HT. The cation conductance was impermeant to calcium ions and was reduced by micromolar concentrations of the Na+ channel inhibitors amiloride and 3,4-dichlorobenzamil. High concentrations of antagonists or agonists of 5-HT1 receptors and an antagonist of 5-HT3 receptors had no effect on either response of P cells to 5-HT. Micromolar concentrations of ketanserin or cyproheptadine, which selectively antagonize 5-HT2 receptors, reduced the cation but not the Cl− conductance. From these results, the receptor underlying the cation conductance appears to be of the 5-HT2 subtype, whereas the receptor activating the Cl− conductance does not fit within the mammalian classification scheme. Brief (&lt;500 ms) application of membrane-permeant agonists of the second messenger cyclic AMP elicited a Cl− conductance, whereas antagonists of cyclic-AMP-dependent protein kinase A reversibly suppressed the Cl− conductance elicited by 5-HT and by cyclic AMP agonists. Compounds affecting other second messenger pathways were without effect on the Cl− conductance. It therefore appears that the Cl− conductance is activated by cyclic-AMP-dependent protein kinase A. Cyclic nucleotide agonists and antagonists were without effect on the cation conductance. However, brief application of phorbol esters, which activate protein kinase C, elicited an amiloride-sensitive cation current. An inhibitor of protein kinase C reduced the cation conductance activated by 5-HT and by phorbol esters. Therefore, the cation conductance appears to depend on activation of protein kinase C. We conclude that 5-HT activates two types of receptor coupled to separate ionic channels via different second messenger pathways in P cells. A receptor that is distinct from the mammalian subtypes activates Cl− channels via cyclic-AMP-dependent protein kinase A. 5-HT2 receptors appear to activate cation channels by means of protein kinase C.
Forces Generated by the Jaws of Clypeasteroids (Echinodermata: Echinoidea)
Authors: Ellers Olaf , Telford Malcolm 
Published: April 2021

ABSTRACTAristotle’s lantern acts like a five-toothed ‘vice grip.’ Contraction of the interpyramidal muscles creates tangential stresses that are converted to radial forces along the teeth. Two mechanical models are proposed to explain this conversion. In the first, the lantern is regarded as a thick-walled cylinder resisting internal pressure; in the second, it is treated as a cluster of wedges. The two models differ primarily in the allowance of radial forces within the muscle in the cylinder and their exclusion in the wedge model. Maximum muscle stress required for a given force along the teeth depends on the ratio of external to internal lantern radii (ro/ri). Maximal force requires that ro/ri should be greater than 2, which is the case in Clypeaster rosaceus (L.). The models allow calculation of a dimensionless number,. ℱ, which scales the force exerted by the teeth for changes in lantern size and the number of pyramids. Biting force was measured in C. rosaceus and used to calculate the muscle stress required by the mechanical models. For the thick-walled cylinder, maximum interpyramidal muscle stress was calculated to be 2.8×106Nm−2. For the wedge model it was 1.9×105Nm−2. The models were supported by comparison of predicted with observed biting forces in another clypeasteroid, Encope michelini L. Agassiz.
The Inorganic Composition of the Body Fluids of Three Marine Invertebrates
Authors: Robertson James D. 
Published: April 2021

ABSTRACT
Analyses have been made of the body fluids of Echinus esculentus, and two decapod Crustacea, Homarus vulgaris and Cancer pagurus, before and after dialysis with sea water in which they were living. The composition of the perivisceral fluid of Echinus is identical with that of seawater, complete physico-chemical equilibrium existing between the two fluids. The blood plasmas of Homarus and Cancer are maintained in dynamic equilibrium with sea water. They contain more Na, K and Ca and less Cl, Mg and SO4 than sea water. The antennary gland fluid of Cancer contains less Na, K, Ca and Cl and more Mg and SO4 than the blood plasma. The importance of the antennary glands and the surface membranes in regulating the inorganic composition of the blood is discussed.
Invertebrate Athletes: Trade-Offs Between Transport Efficiency and Power Density in Cephalopod Evolution
Authors: O’dor R. K. , Webber D. M. 
Published: April 2021

ABSTRACT
Jet propulsion concentrates muscle power on a small volume of high-velocity fluid to give high thrust with low Froude efficiency. Proponents are typically escape artists with high maintenance costs. Nonetheless, oceanic squids depend primarily on jets to forage over large volumes of relatively unproductive ocean (low power density, Wm−3). A survey of locomotor performance among phyla and along an ‘evolutionary continuum’ of cephalopods (Nautilus, Sepia, Loligo and Illex) suggests that increasing speed and animal power density are required if animals are to compete effectively in environments of decreasing power density. Neutral buoyancy and blood oxygen reserves require unproductive volume, keeping drag high. Undulatory fins increase efficiency, but dependence on muscular hydrostats without rigid skeletal elements limits speed. Migratory oceanic squids show a remarkable range of anatomical, physiological and biochemical adaptations to sustain high speeds by maximizing power density. Muscle mitochondrial density increases 10-fold, but metabolic regulation is realigned to optimize both aerobic and anaerobic capacity. The origins of these adaptations are examined (as far as possible, and perhaps further) along the continuum leading to the most powerful invertebrates.
The Influence of Temperature on Muscle Function in the Fast Swimming Scup : I. Shortening Velocity and Muscle Recruitment During Swimming
Authors: Rome Lawrence C. , Choi In-Ho , Lutz Gordon , Sosnicki Andrzej 
Published: April 2021

ABSTRACT
In this study, electromyography showed that scup can swim to a maximum speed of 80 cm s−1 with their red muscle whereas previous results showed that carp can swim to only 45cms−1. Our aim was to evaluate the adaptations that enable scup to swim nearly twice as fast as carp. Although we anticipated that, at their respective maximum speeds, the red muscle of scup would be shortening at twice the velocity (V) of carp muscle, we found that the values of V were the same (2.04 muscle lengths s−1). At any given swimming speed, V was higher in carp than in scup because carp had a larger sarcomere length excursion and higher tail-beat frequency. The smaller sarcomere excursion in scup is primarily associated with using a less undulatory style of swimming (i.e. with a smaller backbone curvature). This less undulatory style of swimming may be an important adaptation that not only reduces V but may also reduce drag. At their respective maximum speeds, however, the 28 % lower sarcomere length excursion in scup is balanced by a 26 % higher tail-beat frequency, giving an equal V to that of carp. Although the scup in this study were somewhat longer than the carp in the previous one (19.7 vs 13.4cm), we believe that many of the observed differences are species-related rather than size-related.
We also found that scup swam in a kinematically similar fashion at 10°C and 20°C. However, at 10°C, the scup could swim to only 54cm s−1 before recruiting their white muscle whereas, at 20°C, they could swim to 80cms−1. The difference in speed of initial white muscle recruitment, as well as information on muscle mechanics (see the following paper), suggests that the scup compress their recruitment order into a narrow speed range at low temperatures, thereby recruiting more muscle fibres. Quantitative analysis of red muscle electromyograms in this paper supports this hypothesis.
5′-p-Fluorosulfonylbenzoyladenosine Binds to the 28Kda Subunit of Larval Manduca Sexta Midgut Vacuolar-Type ATPase
Authors: Zheng X. Y. , Spaeth D. D. , Harvey W. R. , Wolfersberger M. G. 
Published: April 2021

ABSTRACT
The larval lepidopteran midgut contains a mechanism for the active transport of potassium ions from blood to lumen (Harvey and Nedergaard, 1964). This insect K+ pump has been localized to the apical membrane of the midgut goblet cells (Dow et al. 1984). Recently it has been shown to consist of a proton-motive ATPase of the vacuolar class (V-ATPase) functioning in conjunction with a K+/ nH+ antiporter (Wieczorek et al. 1991).
Factors Influencing Facilitation in Actinozoa. The Action of Certain Ions
Authors: Ross D. M. , Pantin C. F. A. 
Published: April 2021

ABSTRACT
In at least some of the muscles in Coelenterates the size of response is controlled by the neuromuscular junction. The sphincter in Calliactis and the longitudinal mesenteric retractor muscles of Metridium senile are served by part of the nerve network which acts as a single excitable system. The response is not graded through a large number of separate motor units. A single stimulus applied to this nerve net is ineffective, or only causes a trivial response ; but it leaves behind it an effect which facilitates the transmission of a second impulse to the muscle. Each impulse in a series facilitates the transmission of excitation to more and more muscle fibres. After each stimulus the facilitating effect gradually dies away (Pantin, 1935 b). In a short discussion, the relation of this “facilitation” process to other cases of junctional transmission was considered (Pantin, 1937). The process by which excitation is only effective if one stimulus follows its predecessor before the period of facilitation has departed, is analogous to the condition of vertebrate skeletal muscle during partial curarization. But at present the nature of the facilitation process is still unknown. A study of the action of ions and other substances throws considerable light upon its nature, and it is the object of this paper to describe and discuss these effects.
Stepping Patterns in Ants: III. Influence of Load
Authors: Zollikofer Christoph P. E. 
Published: April 2021

ABSTRACT
Stepping pattern geometry and walking kinematics of individual foragers of Cataglyphis fortis (Formicidae: Hymenoptera) were recorded during outward and homeward trips to and from a food source. While returning homewards, the animals were supplied with food items of defined mass (load ratio from 1.3 to 6.4) and volume. Under the influence of load, the temporal interleg coordination pattern was maintained (alternating tripod gait), but the spatial tripod pattern was modified. Tripod deformation was found to be proportional to the displacement of the centre of mass induced by the load. Stride length and stride frequency were not altered at any speed when animals carried loads compared with trips without a load. However, in order to maintain stability, mean stride length, mean speed and mean stride frequency were reduced while carrying loads.
Carbonic Anhydrase Injection Provides Evidence for the Role of Blood Acid–Base Status in Stimulating Ventilation after Exhaustive Exercise in Rainbow Trout
Authors: Wood Chris M. , Munger R. S. 
Published: April 2021

ABSTRACT
This study tests the hypothesis that the increase in blood and associated respiratory acidosis after exhaustive exercise play an important role in stimulating ventilation during post-exercise recovery in fish. Injection of bovine carbonic anhydrase (10 mg kg−1) into the bloodstream of rainbow trout caused a persistent 40% increase in the HCO3− dehydration capacity of the blood. The treatment was designed to increase CO2 excretion and therefore to reduce build-up and acidosis after exercise. Aerobic and anaerobic swimming performance were not affected by carbonic anhydrase, and there were only very minor effects on arterial blood acid–base status in resting fish. However, carbonic anhydrase attenuated post-exercise increases in and decreases in pHa by about 50% without altering arterial O2 variables, red cell swelling or the intracellular pH of the brain or muscle tissues. The effects on arterial pH (pHa) resulted largely from alleviation of the increase in . In accordance with the original hypothesis, normal post-exercise hyperventilation was greatly attenuated, through reductions in both ventilatory stroke volume and frequency, and excess post-exercise O2 consumption was reduced. Post-exercise increases in plasma levels of adrenaline and noradrenaline were also reduced by the carbonic anhydrase treatment. Overall, there was a strong correlation between increases in relative ventilation and decreases in pHa after exhaustive exercise. The results provide functional significance for the phenomenon of elevation and associated respiratory acidosis after exercise and are consistent with other recent studies indicating an important secondary drive to ventilation in fish based on arterial acid–base status, in addition to the primary drive based on arterial O2 levels.
Head Waving in Aplysia Californica: II. Functional Anatomy and Muscular Activity During Behaviour
Authors: Kuenzi Frederick M. , Carew Thomas J. 
Published: April 2021

ABSTRACT
Bending and twisting movements of the body during head-waving behaviour of the sea hare Aplysia californica are produced by the concerted action of the muscles of the body wall on the hydrostatic skeleton formed by the haemocoel and internal organs. In this study, we describe the orientations and possible mechanical actions of muscles in the body wall. We also describe the spatial and temporal patterns of longitudinal muscle activity during different head-waving movements in a freely moving animal.
The body-wall muscles are arranged as a network of longitudinal, circular and left-and right-handed helical muscle fascicles. Each fascicle consists of a few to several hundred muscle fibres enclosed in a connective tissue sheath. The sheath also connects muscle fascicles of different orientations at the points where they cross, forming a tightly connected network. In addition, a series of large longitudinal muscle fascicles, including the lateral columellar muscles, lies against the inside wall of the dorsal hemicylinder of the animal.
In animals with hydrostatic skeletons, longitudinal and circular muscles are necessary for producing all basic elongation, shortening and bending movements, and in Aplysia, the extensive distribution of helical muscles provides the animal with the ability to twist its body about the longitudinal axis, as is observed during horizontal head-waving movements.
Muscle activity in the lateral muscles is antiphasically coordinated during horizontal bends, and when the animal is bent to one side, movement towards the centre is accompanied by muscle activity on the side of shortening, i.e. there is no passive return to centre. The muscles near the holdfast are the most active during head-waving movements, with relatively little activity in the head region. The activity of dorsal muscles corresponds to both the existing vertical posture of the body and to discrete dorsal bending movements. In most cases, depression of the head is passive, i.e. both dorsal and ventral longitudinal muscles relax, although foot muscles may also be involved. These observations, together with the constancy of the hydrostatic pressure in the haemocoel during all movements in animals attached to the substratum, suggest specific patterns of motor neurone coordination during different movements.