bluuebunny/crossref_metadata_2025_split huggingface dataset:
Station-Holding by three Species of Benthic Fishes
Authors: Webb Paul W. 
Published: April 2021

ABSTRACT
Station-holding performance was determined on a smooth substratum and on a grid substratum for three species of benthic fishes differing in body shape, surface texture, density, friction coefficient and behavioural repertoire. The grid was made of wires parallel to the flow, which raised fish into the free stream. Limited observations were also made on the benthopelagic cod. Station-holding performance was evaluated at two speeds. The first was defined as the slip speed, above which activities such as swimming, fin-beating, body arching, body clamping and gripping the substratum were required to hold position on the substratum. The second was defined as the swim speed, when fish began swimming out of ground contact. Cod and lasher started swimming when they began slipping, so that slip and swim speeds were the same, averaging 6cms−1 for cod and 32cms−1 for lasher on the smooth surface. Body postures and fin-beating delayed swimming from a slip speed of about 20 cm s−1 to swim speeds of 47–58 cm s−1 for plaice and rays. The grid had relatively little effect on slip and swim speeds of plaice and rays. Lasher grasped the grid with their pectoral fins, increasing swim speeds to 55cms−1. Amputation of the posterior portion of the median fins of plaice reduced swim speeds on the smooth surface to 36cms−1. Amputation of the pectoral fins of lasher reduced the swim speed on the grid to 38cms−1.
Estimates of drag coefficients for fish were made using published data for blisters. These were used to determine lift coefficients and the effects of grasping the substratum on the friction coefficient. Comparison of lift coefficients of rays on the smooth substratum with those on the grid showed that flow beneath the body reduced lift. Amputation of the posterior of the median fins of plaice and the rarity of body posturing by plaice and rays on the grid showed that the major role of this station-holding behaviour was reduction of lift through induction of flow beneath the body. Lashers were able to hold station at speeds comparable to plaice and rays when they could utilize the small amount of surface structure of the grid to increase friction.
Benthic fishes tend to have either ‘flattened’ plaice-or ray-like forms with low drag coefficients but high lift coefficients, or more fusiform lasher-like forms with high drag coefficients and low lift coefficients. High-lift forms use behaviour to reduce lift coefficients, whereas high-drag forms use behaviour to increase friction.
The neural encoding of the location of targets for saccadic eye movements
Authors: Sparks David L. 
Published: April 2021

ABSTRACT
Current models of the saccadic system imply that there are at least three neural representations of a visual target to which a saccade is made: representations in retinal, spatial (head or body) and motor coordinates. This paper presents the evidence supporting these models and summarizes the available neurophysiological data concerning neural representations of target location. In the superior colliculus, neurones in the superficial layers encode target location in retinal coordinates. Neurones in the deeper layers responsive to auditory and visual stimuli carry motor error signals. Evidence is also accumulating that some neurones in the thalamus and the frontal and parietal cortex convey information about target position with respect to the head or body, but these studies are far from complete.
Coding and processing of electrosensory information in gymnotiform fish
Authors: Heiligenberg W. 
Published: April 2021

ABSTRACT
Studies of the electrosensory system of gymnotiform fish have revealed principles of neuronal coding and processing of information which also character-ize more advanced systems, such as vision and audition in higher vertebrates.
Animals may have different classes of receptors adapted to code different variables within a given modality, and the separation of their central projections provides the basis for independent initial processing of these variables by higher-order neurones. These separate pathways, however, eventually converge at the level of still higher-order neurones which are adapted to ‘recognize’ particular spatial and temporal constellations, or patterns, of the stimulus variables conveyed by these pathways. As different stimulus patterns may control different forms of behavioural responses, corresponding neuronal structures can be identified which are adapted to recognize specific patterns. Neurones at an early level of pattern discrimination may still show very general response properties, whereas neurones closer to the ultimate control of a given behaviour show more specific response properties. These latter are less sensitive to stimulus features which are irrelevant to the control of the behaviour, and they code relevant features more purely and with higher acuity than do lower-level neurones. The acuity of stimulus discrimination displayed by some high-order neurones may rival that observed at the behavioural level. This high sensitivity is achieved through pooling and integration of information supplied by large populations of less-sensitive receptors and lower-order neurones.
The neuroethology of acoustic startle and escape in flying insects
Authors: Hoy R. , Nolen T. , Brodfuehrer P. 
Published: April 2021

ABSTRACT
The acoustic startle/escape response is a phylogenetically widespread be-havioral act, provoked by an intense, unexpected sound. At least six orders of insects have evolved tympanate ears that serve acoustic behavior that ranges from sexual communication to predator detection. Insects that fly at night are vulnerable to predation by insectivorous bats that detect and locate their prey by using biosonar signals. Of the six orders of insects that possess tympanate hearing organs, four contain species that fly at night and, in these, hearing is sensitive to a range of ultrasonic frequencies found in the biosonar signals of bats. Laboratory and field studies have shown that these insects (including some orthopterans, lepidopterans, neuropterans and dictyopterans), when engaged in flight behavior, respond to ultrasound by suddenly altering their flight, showing acoustic startle or negative phonotaxis, which serve as bat-avoidance behavior.
A neural analysis of ultrasound-mediated escape behavior was undertaken in the field cricket Teleogryllus oceanicus. An identified thoracic interneuron, int-1, was shown to trigger the escape response, but only when the cell was driven (synaptically or electrically) at high spike rates, and only when the insect was performing flight behavior; avoidance steering only occurs in the appropriate behavioral context: flight. Thus, significant constraints operate upon the ability of int-1 to trigger the escape response. The integration of auditory input and flight central pattern generator output occurs in the brain. It is found that neural activity descending from the brain in response to stimulation by ultrasound is increased when the insect is flying compared to when it is not. Although the behavioral act of avoidance steering may appear to be a simple reflex act, further analysis shows it to be anything but simple.
A subpopulation of cerebral B cluster neurones ofAplysia californicais involved in defensive head withdrawal but not appetitive head movements
Authors: Teyke T. , Weiss K. R. , Kupfermann I. 
Published: April 2021

ABSTRACTThe cerebral B cluster neurones of Aplysia californica were studied under experimental conditions designed to evoke head movements in a selective fashion: either to approach an appetitive stimulus, or to withdraw from an aversive one. Intracellular recordings indicated the presence of two types of B cluster neurones: Bn cells that had fast (narrow) spikes, and Bb cells that had slow (broad) spikes. Tactile stimulation of the tentacles, rhinophores and lips excited Bn neurones, but inhibited Bb neurones. Intracellular stimulation of Bn cells evoked contractions of body wall muscles. No contractions were observed when Bb cells were fired, indicating that it is unlikely that the Bb neurones are motor neurones. Several lines of evidence indicated that the Bn type neurones are involved in withdrawal responses but not in appetitive head turning. (1) Elimination of the descending axons of the Bn cells by lesioning the cerebropleural connectives (C-Pl connectives) did not affect the head-turning response. This lesion significantly altered the head-withdrawal response by selectively eliminating an initial fast component of the withdrawal movement. (2) In chronic recordings from the C-Pl connective, unit activity was obtained which was correlated with the presentation of an appetitive stimulus rather than with evoked or spontaneous turning movements. A substantial increase in activity also occurred during head withdrawal of the animal. On the basis of these data, we postulate that separate populations of motor neurones are responsible for the aversive withdrawal of the head, and for the directed turning response towards a stimulus.
Regulation of Intracellular pH by Toadfish (Opsanus Beta) Hepatocytes
Authors: Walsh Patrick J. 
Published: April 2021

ABSTRACT
The BCECF [2’,7’-bis(carboxyethyl)-5(6)-carboxyfluorescein] method for measurement of intracellular pH (pHi) was successfully applied to toadfish (Opsanus beta Goode and Bean) hepatocytes and used for investigating the pHi regulatory properties of the hepatocytes. As in previous studies of fish hepatocytes, toadfish hepatocyte pHi showed a marked dependence on extracellular pH (pHe) with characteristic values of about 0.15–0.2 units below pHe. Measurement of membrane potential (–33.76±3.07mV, N=3) in toadfish hepatocytes by the S14CN− distribution method allowed calculation of equilibrium pHi values and, despite the close tracking of pHi and pHe, proton equilibration across the membrane was never observed. Furthermore, when toadfish hepatocytes were acidified by the NH4CI prepulse method, recovery to normal pHi values could be inhibited by addition of 0.5 mmol I−1 amiloride or replacement of extracellular Na+, indicating that these cells possessed a Na+/H+ exchanger. These experiments led to the conclusion that pHi is regulated in toadfish hepatocytes. I next exposed toadfish hepatocytes to a physiological range of several extracellular variables that change during exercise (pHe, [lactate], [catecholamine], [glucose]), in the presence and absence of amiloride, in an attempt to determine the importance of Na+/H+ exchange to hepatocyte pHi regulation in a physiological context. The exchanger plays a significant role in post-exercise recovery from acidosis induced by changes in and pHe. Further experiments employing inhibitors of lactate metabolism (3-mercaptopicolinic acid and amino-oxyacetic acid) and amiloride established that the increased lactate metabolism associated with ‘post-exercise’ recovery creates an intracellular acid load, and that Na+/H+ exchange protects the cell from changes in pHi caused by lactate metabolism.
Ion Homeostasis in the Leech: Contribution of Organic Anions
Authors: Hoeger Ulrich , Wenning Angela , Greisinger U. T. E. 
Published: April 2021

ABSTRACT
Organic anion concentrations in the blood of Hirudo medicinalis were determined in samples from individual animals using reverse-phase high-pressure liquid chromatography (HPLC) and ultraviolet detection. Quantitatively important anions were malate, α-ketoglutarate, succinate, lactate and fumarate, constituting about 70% of total blood anions. Malate had the highest concentration, 34–68 mehquiv l−1 blood, which could (depending on metabolic state) exceed the level of blood Cl− (approx. 36mequivl−1). Organic acid concentrations in the blood were considerably higher than in the tissue.
Blood organic acid concentrations changed more with than with temperature. They were unaffected by short periods of aerobic exercise, but stress due to handling and prolonged restraint led to a drastic increase of blood lactate and succinate levels, while malate, fumarate and α-ketoglutarate levels decreased.
After feeding on hypertonic, Cl−-rich meals, the Cl− concentration in leech blood increased far more than the cation concentrations. This was not compensated by a decrease of organic acid levels. The regulatory mechanisms for inorganic and organic ion homeostasis function independently.
The Larval Eclosion Hormone Neurones inManduca Sexta:Identification of the Brain-Proctodeal Neurosecretory System
Authors: Truman James W. , Copenhaver Philip F. 
Published: April 2021

ABSTRACTLarval and pupal ecdyses of the moth Manduca sexta are triggered by eclosion hormone (EH) released from the ventral nervous system. The major store of EH activity in the latter resides in the proctodeal nerves that extend along the larval hindgut. At pupal ecdysis, the proctodeal nerves show a 90 % depletion of stored activity, suggesting that they are the major release site for the circulating EH that causes ecdysis. Surgical experiments involving the transection of the nerve cord or removal of parts of the brain showed that the proctodeal nerve activity originates from the brain. Retrograde and anterograde cobalt fills and immunocytochemistry using antibodies against EH revealed two pairs of neurons that reside in the ventromedial region of the brain and whose axons travel ipsilaterally along the length of the central nervous system (CNS) and project into the proctodeal nerve, where they show varicose release sites. These neurons constitute a novel neuroendocrine pathway in insects which appears to be dedicated solely to the release of EH.
The Scaling of Aerobic and Anaerobic Muscle Power in Rainbow Trout(Salmo Gairdneri)
Authors: Goolish Edward M. 
Published: April 2021

ABSTRACTThe scaling of anaerobic metabolism and red muscle mass was examined in rainbow trout (Salmo gairdneri) ranging in size from 2 to 1200 g. The initial rate of white muscle lactate production during maximal burst activity was significantly higher in large (28·lcm) than in small (8·0cm) fish. ‘Resting’ lactate concentrations in anesthetized trout (approximately 30 s of stress) increased with fish size, also reflecting higher glycolytic potential for larger fish. Maximum muscle lactate concentrations following 6 min of exhaustive exercise increased from approximately 25 to 45 μmolg−1 with increased fish size (= L0·36, where L is fish length). Total white muscle lactate production, including changes in muscle mass, scaled as L3·52. A scaling comparison of total anaerobic capacity with theoretically predicted power requirements indicated decreased burst swimming performance with increased size. Red muscle mass increased from approximately 1 to 3 % of body mass with increased fish size. The positive allometry in red muscle mass (= L3·62) is greater than the scaling of power requirements during aerobic swimming predicted from hydrodynamic theory, and may provide compensation for decreased mass-specific power output with increased size.
Combined Effects of Environmental PO2 and Temperature on Ventilation and Blood Gases in the Carp Cyprinus Carpio L.
Authors: Glass M. L. , Andersen N. A. , Kruhøffer M. , Williams E. M. , Heisler N. 
Published: April 2021

ABSTRACT
The effects of changes in environmental temperature and oxygen tension on gill ventilation, arterial , pH and [HCO3−] were evaluated in carp (Cyprinus carpio L.). Gill ventilation was measured continuously in specimens acclimated to 10 or 20°C, combining the method of electromagnetic flow determination with the application of a rubber mask technique. After establishing control values in airequilibrated water the environmental water was reduced from about 150 mmHg (20 kPa) during control conditions to 110 or 75 mmHg (14.7 or 10 kPa), respectively. Measurements of blood gases and acid-base parameters were performed repeatedly before, and 1 and 4 h after, initiation of hypoxia. Regardless of temperature, these moderately hypoxic conditions caused considerable and lasting increases in gill ventilation of about 70% or 180% , relative to the respective normoxic control values of about 50ml kg−1 min-1 at 10°C and 230 ml kg−1 min−1 at 20°C. These increases in ventilation reduced substantially, resulting in a rise in pHa by about 0.1 units at of 110 mmHg (14.7 kPa) and by about 0.2 units at of 75mmHg (10 kPa). Arterial was low under normoxic conditions at both temperatures (≈15 mmHg, ≈2kPa). During hypoxia, was marginally reduced, whereas the arterial O2 content and saturation remained at normoxic levels, mainly because of the increase in the blood O2-affinity induced by respiratory alkalosis. This lack of any clear relationship between arterial O2 content and ventilatory response to moderate hypoxia contrasts with previously reported data for trout, and supports the hypothesis that a change in is an adequate stimulus for the adjustment of ventilation in carp.
The considerable ventilatory response, together with small and inconsistent reductions in arterial , may also represent an expression of the action of waterfacing oxygen receptors on the regulation of breathing. A striking feature of the regulation of ventilation in carp compared with that in air-breathing lower vertebrates is that the hypoxic response is maintained at low temperatures, possibly indicating a relatively small safety margin for complete tissue oxygen supply in fish.
Prey capture in the praying mantis Tenodera aridifolia sinensis: coordination of the capture sequence and strike movements
Authors: Corrette B. J. 
Published: April 2021

ABSTRACT
Coordination of the complete capture sequence of the praying mantis has been studied in detail using several specially developed photographic techniques.
The mantis was able to attack prey throughout a large three-dimensional capture zone by changing body orientation relative to its perch. This orientation centred prey on the median plane and brought it within an attack zone relative to the prothorax. Alignment with the median plane simplifies the attack since the prey can then be localized using only two dimensions. The attack comprised several stereotyped components which together formed a single movement sequence of all six legs. Although too rapid for visual feedback, a simple mechanism permits steering of these movements to capture prey at particular locations within the attack zone.
These findings are contrasted with those from studies of mantis visual behaviour and a simple mechanism is suggested for how prey location is encoded to produce steering of the attack.
Are American Homing Pigeons Genetically Different from Italian Ones?
Authors: Benvenuti S. , Brown A. I. , Gagliardo A. , Nozzolini M. 
Published: April 2021

ABSTRACT
The variable results of experiments on anosmic Cornell pigeons, compared with the consistent effect of olfactory deprivation observed in pigeons in Italy, has sometimes been explained by supposing that pigeons in the two countries belong to different genetic strains.
This hypothesis was tested by performing experiments with the progeny of Cornell pigeons transported to Italy as eggs and placed in the nests of Italian foster parents. The homing behaviour of the American birds raised in Italy was compared with that of Italian pigeons hatched and raised in the same loft.
The results of the experiments show that both the American and the Italian pigeons are severely affected by olfactory deprivation in releases at unfamiliar sites, in contrast to the homeward-oriented control groups of both strains. We conclude that there is no major genetic difference in homing mechanism between Cornell and Italian pigeons.
The results of experiments performed in Italy and in the USA have shown that different rearing and training procedures do not induce the development of maps based on different cues. Therefore, the reported differences between the results obtained in the USA and those obtained in Italy may be due to regional differences in the availability of navigational cues.
Neural Control of Heart Beat in the Pteropod Mollusc Clione Limacina: Coordination of Circulatory and Locomotor Systems
Authors: Arshavsky Yu. I. , Deliagina T. G. , Gelfand I. M. , Orlovsky G. N. , Panchin Yu. V. , Pavlova G. A. , Popova L. B. 
Published: April 2021

ABSTRACT
In the intact pteropod mollusc Clione limacina a correlation between heart beat and locomotor activity has been found. In freely swimming Clione, pauses in locomotor activity arose spontaneously with intervals of a few minutes. During these pauses, the heart stopped beating. A link between the heart and locomotor activity was also observed during defensive reactions: mechanical stimulation of the head resulted in the termination of both locomotion and heart beating, while stimulation of the tail accelerated both the locomotor and the heart rhythms. After transection of the medial abdominal nerve supplying the heart, the link between heart rate and locomotor activity disappeared. The heart rhythm accelerated during hunting behaviour of Clione. Four efferent neurones controlling heart beat were found: one heart excitor (HE) in the left pedal ganglion, and three heart inhibitors (HI) in the left abdominal ganglion. The HE exerted an inhibitory action upon the HIs. Spontaneous or reflex activation of the locomotor generator was accompanied by excitation of the HE and by inhibition of the HIs, while spontaneous or reflex inhibition of the locomotor generator was accompanied by inhibition of the HE and by excitation of the HIs. These effects were due, at least partly, to the direct action of the neurones of the locomotor generator upon the HE and HIs.
Fish Hepatocytes Accumulate Hepes: A Potential Source of Error in Studies of Intracellular pH Regulation
Authors: Walsh Patrick J. 
Published: April 2021

ABSTRACT
Since their introduction in 1966, the so-called ‘Good’s’ hydrogen ion buffers (e.g. Hepes, Pipes, etc.; Good et al. 1966; Good and Izawa, 1972) have been used in many experimental systems. Their popularity is widespread because they appear to fit many of the criteria for ideal biological buffers, including appropriate pKa values, high aqueous solubility, minimal complexation with metal ions, and low membrane permeability (Good et al. 1966; Good and Izawa, 1972). More recently, the fit of Good’s buffers to these criteria has come under closer scrutiny. Under some circumstances, particularly in the in vitro study of metal ion-metallo-protein interactions (Nakon and Krishnamoorthy, 1983) and in studies of free-radical production (Grady et al. 1988), their use may lead to spurious results.