bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of afferent activity in the maintenance of primate neocortical function
Authors: Jones E. G.
Published: April 2021

The major neuronal populations of the primate cerebral cortex can be classified immunocytochemically according to their transmitters and in terms of the differential expression of certain other molecules such as neuropeptides, calcium-binding proteins and protein kinases. We have been able to chart the time course of developmental expression of these molecules and to show that gene expression for many of them is regulated in adult and infant animals by afferent activity entering the cortex.

In the visual cortex of adult monkeys, levels of immunocytochemically detectable gamma aminobutyric acid (GABA), of its synthesizing enzyme glutamic acid decarboxylase (GAD) and of the tachykinins are greatly reduced in deprived ocular dominance columns within 24 h of blocking impulse activity in the optic nerve by intraocular injection of tetrodotoxin (TTX). Conversely, levels of immunocytochemically detectable calcium-calmodulin-dependent protein kinase (CAM II kinase) are increased in deprived eye dominance columns. These effects are quickly reversible on restoration of binocular vision, and experiments involving in situ hybridization and S1 nuclease protection assays show that the changes are associated with parallel changes in mRNA levels for preprotachykinin and CAM II kinase, but not for GAD, which appears to be regulated by post-transcriptional mechanisms. Experiments in the primate somatic sensory cortex suggest comparable activity-dependent effects on gene expression there also.

It is proposed that effects of this type underlie the establishment of cortical maps during development and their activity-dependent mutability in adulthood.
Morphological plasticity of postsynaptic neurones in reactive synaptogenesis
Authors: Hamori J.
Published: April 2021

Partial deafferentation of certain brain regions (septal nuclei, hippocampus, etc.) in adult animals results (1) in the disappearance of degenerating axon terminals and (2) in the short-term persistence of vacant postsynaptic sites. These postsynaptic sites have been shown to be re-supplied by sprouted axon terminals of intact axons. This paper will demonstrate that, in brain regions (e.g. cerebellar cortex, lateral geniculate nucleus) where axonal sprouting of local elements or of persisting afferent axons is negligible or absent, synaptic reorganization involves the active participation of postsynaptic dendritic and somatic elements of surviving local nerve cells. Synaptic regeneration can be demonstrated by morphological means both in developing and in adult central nervous system. The dendrites may show two types of response to deafferentation: (1) the formation of presynaptic specializations along their otherwise ‘classical’ postsynaptic membrane (the axonization of dendrites) resulting in the formation of new, dendro-dendritic synapses, and (2) the ‘adaptive’ (structural) reduction in size (‘atrophy’) of the denervated nerve cell dendritic arborization, leading to a relative increase in density of the surviving (though non-sprouting) afferent axon terminals. In both cases a partial functional recovery can be demonstrated.
Development of the mammalian retinogeniculate pathway: target finding, transient synapses and binocular segregation
Authors: So K. F. , Campbell G. , Lieberman A. R.
Published: April 2021

This review is concerned with the development of the mammalian retinogeniculate projection from the perspective of our studies on the hamster and to a lesser extent on the cat. In these, and other mammalian species, axons from the two eyes initially spread throughout the dorsal lateral geniculate nucleus (dLGN) and thus completely overlap. Later they segregate, the axons from each eye coming to occupy discrete, non-overlapping territories within the dLGN. The process of segregation to establish the adult pattern coincides with the death of retinal ganglion cells projecting to inappropriate areas of the dLGN and with the loss, by degeneration or retraction, of the axons and/or axonal branches initially located within inappropriate territory of the dLGN. These events occur in the early postnatal period in hamsters, before the eyes have opened, and in cats and monkeys they occur entirely during embryonic life: thus, they do not depend on the onset of normal visual function. If one eye is removed before segregation has begun, the terminal fields of the crossed and uncrossed axons from the remaining eye do not segregate, suggesting that segregation in normal development may depend on some form of interaction between retinal ganglion cells from the two eyes. Attractive and/or repulsive influences exerted by the dLGN on retinogeniculate axons may also be involved in the formation of eye-specific territories.

Experimental ultrastructural studies in hamster and cat show that the overlap phase is associated with the formation, by inappropriately located axons, of transient synapses similar to those made by retinogeniculate axons in appropriate parts of the dLGN. In the cat, the transient synapses are made by the axon trunk and by side branches of retinogeniculate axons with terminal arbors in appropriate parts of the nucleus; the transient synapses disappear as the side branches are shed or retracted during the segregation period.

Because of good evidence that electrical activity of the retinogeniculate axons may be involved in binocular segregation of inputs, we suggest that the formation and elimination of transient synapses play a significant role in the development of the orderly retinogeniculate projections.
The Role of Series Elastic Structures in Prestretch-Induced Work Enhancement During Isotonic and Isokinetic Contractions
Authors: Ettema G. J. C. , Soest A. J. Van , Huijing P. A.
Published: April 2021

The influence of series elastic structures on the dynamics of the contractile machinery was examined in the gastrocnemius medialis (GM) of five male Wistar rats, with respect to enhancement of work of a muscle-tendon complex after active stretch. Imposed isotonic and isokinetic contractions were preceded by either an isometric phase (PI) or an active stretch (PS). The effects of fibre length differences at the onset of shortening, due to differences of extension of tendinous structures, were studied. For the isotonic experiments fibre length and shortening velocity were estimated 30 ms after release and compared with the PI length velocity curve determined at the same force level. For shortening above the optimum length, about half of the enhanced shortening found after prestretch could be explained by PS—PI fibre length differences. Below the optimum length, PS shortening velocity was somewhat lower than expected on the basis of length-velocity characteristics. Enhancement of work output due to stretch was different for isokinetic and isotonic shortening. In isokinetic shortening, following prestretch, fibre work was limited because of enhanced shortening of the tendinous structures.

In stretch-shortening cycles imposed on a muscle-tendon complex, the length of the complex affected all prestretch effects, i.e. potentiation of the contractile element, contractile element interaction with the tendinous structures, and elastic energy release.

It is concluded that, besides potentiation effects and enhanced elastic energy release, the influence of series elastic structures on fibre dynamics determines active stretch-induced work enhancement. The contribution by these mechanisms to this work enhancement depends largely on the type of stretch-shortening cycle.
The Work and Energetic Cost of Locomotion: I. The Effects of Limb Mass Distribution in Quadrupeds
Authors: Steudel Karen
Published: April 2021

Does limb design influence the cost of locomotion in quadrupedal mammals? If not, morphologists must dismiss the economy of locomotion from consideration when assessing the adaptive factors shaping limb structure. Several studies have recently used externally applied loads to demonstrate a relationship between limb mass distribution and energy costs in human subjects. It is not clear whether a similar correlation would hold for quadrupeds, given their very different gaits. The present study addresses this question by measuring the rate of oxygen consumption in domestic dogs running on a treadmill with mass added either to the limbs or to the back. Trials with no additional mass were used as a control. The use of externally applied loads has the advantage of allowing limb mass to be altered in a system in which other aspects of physiology that might influence cost of locomotion are held constant. The cost of adding mass to the limbs in dogs was found to be significantly greater than that of adding it at the center of mass. Limb mass distribution does affect the cost of locomotion in quadrupeds. A comparison of the results from a variety of studies in which the energetic cost of adding external loads has been measured in animals across a wide size range suggests a qualitative difference in the factors determining the cost of locomotion in large and small animals.
The Work and Energetic Cost of Locomotion: II. Partitioning the Cost of Internal and External Work within a Species
Authors: Steudel Karen
Published: April 2021

Previous studies have shown that large animals have systematically lower mass specific costs of locomotion than do smaller animals, in spite of there being no demonstrable difference between them in the mass-specific mechanical work of locomotion. Larger animals are somehow much more efficient at converting metabolic energy to mechanical work. The present study analyzes how this decoupling of work and cost might occur. The experimental design employs limb-loaded and back-loaded dogs and allows the energetic cost of locomotion to be partitioned between that used to move the center of mass (external work) and that used to move the limbs relative to the center of mass (internal work). These costs were measured in three dogs moving at four speeds.

Increases in the cost of external work with speed parallel increases in the amount of external work based on data from previous studies. However, increases in the cost of internal work with speed are much less (<50 %) than the increase in internal work itself over the speeds examined. Furthermore, the cost of internal work increases linearly with speed, whereas internal work itself increases as a power function of speed. It is suggested that this decoupling results from an increase with speed in the extent to which the internal work of locomotion is powered by non-metabolic means, such as elastic strain energy and transfer of energy within and between body segments.
Speed, Jet Pressure and Oxygen Consumption Relationships in Free-Swimming Nautilus
Authors: O’dor R. K. , Wells J. , Wells M. J.
Published: April 2021

Neutrally buoyant, ultrasonically telemetering, differential pressure transducers were attached to Nautilus pompilius L. to record mantle cavity pressures while the animals were induced to swim in a flume in response to food. Synchronized videotapes and computer data files showed that jet pressures (p, Pa) increased linearly with swimming speed (u, ms−1), p=1565 u – 8. Because of their stereotyped responses to food, Nautilus could be induced to produce similar pressures in 51 respirometers, where oxygen consumption () increased as a power function of pressure, . Combining these equations gave an oxygen consumption-speed relationship, . We used this equation to show that the cost of transport for Nautilus is dramatically lower than that for squid and, at speeds below 0.05 m s−1, even lower than that of an undulatory swimmer, the salmon. Calculated power inputs and outputs suggest that squid have increased their power density (W kg−1) 100-fold over their ectocochleate ancestors, and that Nautilus is very efficient in its low-speed, low-energy environment. These laboratory ‘calibrations’ are a basis for field studies using telemetered pressure data to develop energy budgets for this unique living fossil as a reference for comparing the energetic requirements of ancient and modern seas.
Effects of Cold Exposure on Oxygen Consumption, Ventilation and Interclavicular Air-Sac Gases in the Little Penguin (Eudyptula Minor)
Authors: Johannesen Hege , Nicol Stewart C.
Published: April 2021

Oxygen consumption , tidal volume, respiratory frequency and the composition of the gas in the interclavicular air sac were measured in the little penguin Eudyptula minor (Forster) at ambient temperatures (Ta) of 5 and 20 °C.

increased from 14.60 ml 02 kg−1 min−1 at 20°C to 18.29 ml 02 kg−1 min−1 at 5 °C. However, the elevated at the low Ta was not matched by a similar rise in total inspiratory ventilation . The ventilatory requirement thus decreased from 0.5751 mmol−1 at 20°C to 0.4401 mmol−1 at 5°C. An increased gas exchange efficiency during cold exposure was also shown by the composition of the gas in the interclavicular air sac. decreased from 11.95 kPa at 20°C to 10.24kPa at 5°C, while the corresponding increase in was from 6.61 to 7.50 kPa.

Oxygen extraction, calculated from and O2 content of the inspired air, increased from 24.60% at 20°C to 31.04% at 5°C. Oxygen extraction calculated from the O2 contents of inspired air and interclavicular air-sac gas was 38.73 % at 20°C and 47.18% at 5 °C.

The results confirm previous findings for the little penguin which showed a decrease in the ventilatory requirement with increasing oxygen uptake. However, the improved gas exchange efficiency during cold exposure and the strong correlation found between oxygen extraction and oxygen consumption have not been demonstrated previously for this species.
Characterization of Red Blood Cell Metabolism in Rainbow Trout
Authors: Walsh Patrick J. , Wood Chris M. , Thomast Serge , Perry Steve F.
Published: April 2021

Red blood cell metabolism was studied in vitro using whole blood obtained by catheter from resting rainbow trout (Oncorhynchus mykiss). Preparations were viable as shown by stable NTP, metabolite and catecholamine levels and acid-base status, all of which remained at in vivo levels over the 2h incubation period. Enzymes diagnostic of glycolysis, the tricarboxylic acid (TCA) cycle and phosphagen metabolism were all present-in significant amounts in red blood cells. In direct comparisons of 14C-labelled substrates at normal resting plasma concentrations, rates of CO2 production were in the order: glucose>lactate>ala-nine>oleate. Total CO2 production rates from these four oxidative substrates did not equal directly measured O2 consumption rates, indicating that other substrates may also be important in vivo. Oxidative pathway Km values for glucose (8.4mmoll−1), lactate (3.3mmoll−1) and alanine (0.8mmoll−1) were well within the normal physiological ranges of plasma concentrations. Glucose concentration did not affect lactate oxidation rates, but there was some inhibition (27%) of glucose oxidation by high lactate concentrations (20mmol l−1). The observed Km values and competitive interactions suggest that changes in plasma concentrations associated with environmental stresses can considerably alter the relative rates of oxidation of glucose and lactate in vivo. Considerable pentose-phosphate shunt activity was detected in red cells, as indicated by high activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase and high CO2 production rates from (l-14C)-labelled glucose. Even in the presence of normal O2 levels, a significant percentage (28%) of glucose metabolism was directed to lactate production. Taken together, these results demonstrate that rainbow trout whole blood incubated in vitro constitutes a dynamic and viable system for metabolic studies at the pathway level.
Breathing in Rana Pipiens: the Mechanism of Ventilation
Authors: Vitalis Timothy Zoltan , Shelton Graham
Published: April 2021

The mechanism and pattern of ventilation in unrestrained Rana pipiens were investigated by simultaneous measurements of pulmonary pressure, buccal pressure and air flow at the nostrils. The buccal cavity was ventilated continuously at a rate of 90±3.2 oscillations min−1 by low-amplitude pressure swings above and below atmospheric. The lungs were ventilated intermittently by the buccal pump at a rate of 6.3±0.8 breaths min−1. Expiration of gas from the nostrils occurred on two occasions during a lung ventilation. Ventilation of the lungs was achieved by precise timing of two valves, the nostrils and glottis. The timing of the valves determined the volume of expiratory flow on these two occasions and its relationship to inspiratory flow. Thus, the breathing movements could cause inflation, deflation, or no change in the lung volume. Periodically the lung was inflated by a sequence of successive breaths. During inflations the nostrils closed simultaneously with glottal opening and almost no gas was expired during the first expiratory phase. This caused a complete mixing of buccal contents and pulmonary gas and this mixture was pumped back into the lung. Deflations were characterized by a delay in nostril closing that resulted in a large outflow of gas from the lung and buccal cavity during the first phase of expiration. More gas left the system than was pumped into the lungs. The results suggest that coherent air flow from glottis to nostrils, as required by the ‘jet stream’ hypothesis of Gans et al. (1969), is not likely to occur.
Flight Behaviour and Selective Degeneration of Flight Muscles in the Adult Cricket (Gryllus Bimaculatus)
Authors: Shiga S. , Kogawauchi S. , Yasuyama K. , Yamaguchi T.
Published: April 2021

Tethered adult crickets (Gryllus bimaculatus De Geer) assume a full flight posture: they point the antennae straight ahead, hold the fore-and midlegs close to the body, stiffen the abdomen for steering and extend the hindlegs directly backwards. Tomioka and Yamaguchi (1980) have reported that about 30% of the animals displaying flight behaviour also flap their hindwings, but the remaining crickets vibrate their wings through a narrow range instead of flapping them. They distinguished the latter type of behaviour from normal flight behaviour and designated it ‘pseudo-flight behaviour’.
Do Fish Sniff? A New Mechanism of Olfactory Sampling in Pleuronectid Flounders
Authors: Nevitt Gabrielle A.
Published: April 2021

Although olfaction is known to be a highly developed sense in a variety of fishes, little information is available about behavioral mechanisms by which fishes sample the olfactory environment. This study was undertaken to assess the role of spontaneous jaw protrusion (‘coughing’) as a potential mechanism for olfactory sampling in pleuronectid flounders.

Investigations were carried out using a combination of physiological, morpho-logical and behavioral techniques. Physiological results show (1) that typical respirations are coupled to measurable olfactory sac pressure fluctuations and (2) that during a coughing event, water is rapidly sucked into the olfactory sac. Morphological results indicate (3) a direct linkage system between the protrusion apparatus and the olfactory or associated accessory sacs, and (4) that coughing is associated with a rapid expansion or stretching of these sacs. Lastly, behavioral studies demonstrate (5) that coughing rates increase significantly over background activity when flounders are presented with attractive food odorants. From these results, I propose that coughing in pleuronectid flounders represents a behavior truly analogous to sniffing in certain air-breathing organisms.
Vertical Flight in the Greater Horseshoe Bat Rhinolophus Ferrumequinum
Authors: Aldridge H. D. J. N.
Published: April 2021

The kinematics, aerodynamics and energetics of vertical flight in Rhinolophus ferrumequinum (Schreber) are described. During the downstroke the resultant force generated by the wings tends to accelerate the animal upwards and forwards. Towards the end of the downstroke the wings generate negative thrust and, consequently, the animal accelerates backwards. When, during the upstroke, the wings are accelerated backwards (the ‘flick’) a significant thrust is generated. Total specific mechanical power is approximately 11.92Wkg-1, of which 84% is required during the downstroke.
Thermoregulation and Energetic Decision-Making by the Honeybees Apis Cerana, Apis Dorsata and Apis Laboriosa
Authors: Underwood Benjamin A.
Published: April 2021

Thoracic flight temperatures (Tth) of workers of three species of honeybees (genus Apis) in Nepal were measured at relatively low ambient temperatures (Ta). At Ta = 18–24 °C, A. dorsata workers arriving at feeders to collect concentrated (⩾=40%) sugar syrup maintained higher temperature gradients (Tth — Ta) than workers arriving at feeders with dilute (6–17%) syrup. Temperature gradients were inversely related to Ta, indicating thermoregulation at low Ta. Similarly, temperature gradients varied inversely with Ta in A. cerana and A. laboriosa workers arriving at feeders at Ta = 12–20 °C. Temperature data suggest that honeybees have the ability to regulate heat production in flight and that they may vary their flight efforts according to expected gains and associated costs. Temperature gradients of A. laboriosa workers in flight are apparently about the same as those of A. mellifera workers, whose body mass is only half that of A. laboriosa. The circulatory systems of A. laboriosa workers show no striking differences from those of other species of Apis and are therefore probably equally effective at retaining heat in the thorax. This suggests that the relatively low (in relation to the body size) Tth— Ta maintained by A. laboriosa may be an indication of a relatively low metabolic rate and consequent low heat production. This is supported by an analysis of mass1,/3-specific wing-loading and, in turn, suggests that A. laboriosa may be grouped with A. dorsata and A. florea as a relatively low-powered, open-nesting honeybee, in contrast to the more high-powered cavity-nesters, A. cerana and A. mellifera.
The Swimmeret Rhythm and its Relationships With Postural and Locomotor Activity in the Isolated Nervous System of the Crayfish Procambarus Clarkii
Authors: Barthe Jean-Yves , Bévengut Michelle , Clarac François
Published: April 2021

An in vitro preparation was developed consisting of the five thoracic and six abdominal ganglia of the crayfish nerve cord, isolated from anterior nervous structures and from peripheral sensory inputs.

The central activities of the thoracic leg, swimmeret and abdominal positioning motor systems and their relationships were studied. When motor outputs were tonic in the thoracic leg nerves (90% of the preparations), continuous rhythmic activity occurred and persisted for several hours in the swimmeret nerves. Interruptions of the swimmeret rhythm were associated with rhythmic motor outputs in the leg nerves (10% of the preparations). Motor activity in the abdominal positioning system was mainly tonic.

Swimmeret rhythm reversibly disappeared during application of a sucrose block between the thoracic and abdominal parts of the nerve cord. Electrical stimulation of the connectives posterior to the block induced bouts of rhythmic swimmeret activity.

Comparisons of the swimmeret rhythm (period) and the metachronal wave (duration, phase) showed that sectioning of the connectives between the thoracic and abdominal ganglia modified the period but did not affect the properties of the metachronal wave.

We conclude that the presence of descending inputs from thoracic ganglia is necessary for persistent swimmeret activity.
Activation by N-Ethylmaleimide of a Cl− -Dependent K+ Flux in Isolated Trout Hepatocytes
Authors: Bianchini Laurence , Fossat Barthélémy , Porthé-nibelle Jacqueline , Lahlou Brahim
Published: April 2021

Isolated trout hepatocytes when swollen in hypotonic medium undergo a regulatory volume decrease (RVD), which occurs via KCl loss. The system shows characteristics similar to those of the transporter described in red cells. This led us to investigate, in trout hepatocytes, the effect of another signal known to activate this flux in red cells, i.e. treatment with the sulphhydryl-group reagent N-ethylmaleimide (NEM). NEM treatment resulted in a striking increase in ouabain-resistant K+ uptake measured by an isotope pulse uptake technique. The time course of the response to NEM was similar to that obtained with a hypotonic shock, indicating that the effect of NEM was immediate and transient. The NEM-stimulated K+ influx demonstrated the same anion sensitivity as the volume-induced K+ influx, i.e. a specific requirement for Br− or Cl−. Efflux experiments showed that NEM treatment produced a stimulation of both K+ and Cl− effluxes leading to a substantial net loss (10 %) of cellular KC1, as confirmed by analysis of ionic contents. This KCl loss is consistent with the rapid cell shrinkage observed after addition of NEM. The Cl−-dependent K+ influx was found to be indepen-dent of external Na+ ; in addition, NEM had no effect on Na+ content, indicating that Na+ is not implicated in this process. The effect of loop diuretics was tested on the NEM-stimulated K+ influx. As observed for the volume-induced K+ flux, a high concentration of furosemide (10−3moll−1) is required for full inhibition of this flux; no effect was obtained with bumetanide (10−4moll−1). Consequently, NEM appears to activate a KCl cotransport similar to the one induced in hypotonically swollen cells. Finally, the combination of the two treatments, NEM and hypotonic shock, was found to increase the K+ fluxes even further, suggesting additivity of the two stimuli by mutual positive interaction.
A New in Vitro Assay for Carbon Dioxide Excretion by Trout Red Blood Cells: Effects of Catecholamines
Authors: Wood Chris M. , Perry Steve F.
Published: April 2021

A new in vitro assay was developed and critically characterized to measure the rate of CO2excretion by trout red blood cells (RBCs) from HCO3- in their natural plasma under normal in vivo conditions of acid-base status. The assay is based on the addition of [14C]bicarbonate to the whole blood and collection of the resultant 14CO2in the overlying gas phase. The assay simulates the exposure of blood passing through the gills, and measured CO2excretion rates are representative of those occurring in vivo. Rates are linear over the 3 min time course of the assay, related to haematocrit in a non-linear fashion, elevated by the addition of carbonic anhydrase, reduced by blockade with acetazolamide, and sensitive to variations of equilibration . Large variations in plasma [HCO3-] have only a small effect on CO2excretion rates when the blood is chronically equilibrated at these levels. Acute elevations in [HCO3-], however, create a non-equilibrium situation, resulting in large increases in CO2excretion. When the blood is acidified, to duplicate typical post-exercise metabolic acidosis, adrenaline causes a marked inhibition of RBC CO2excretion. The response is transient, reaching a peak 5–8 min after addition of adrenaline and disappearing by 30–60 min. The magnitude of the adrenergic inhibition is correlated with the magnitude of the RBC pHi regulatory response, expressed as the RBC transmembrane pH difference (pHe—pHi). These results support the ‘CO2retention theory’ explaining observed increases in blood vivo after exhaustive exercise and catecholamine infusions in fish.
Temporal Analysis of Snail Feeding Rhythms: A Three-Phase Relaxation Oscillator
Authors: Elliott C. J. H. , Andrew T.
Published: April 2021

Rhythmic fictive feeding was recorded from the motoneurones of the buccal ganglia of Lymnaea stagnalis. The times of the action potentials were recorded by microcomputer and the lengths of the three phases (N1, N2 and N3) making up each feeding cycle were determined. During spontaneous rhythmic fictive feeding in Lymnaea stagnalis the cycle period varied randomly. Most of the variation in cycle period arose from alterations in the duration of the N3 (swallowing) phase of the rhythm; the N1 (protraction) and N2 (rasp) phases were fixed in length. The firing rates of feeding motoneurones active in the N1 and N3 phases increased with feeding rate: this was not true of those active in the N2 phase. In rhythms produced by stimulating the SO modulatory interneurone, both the N1 and N3 phases varied in duration. The N2 duration remained constant. The temporal analysis is accounted for by the neuronal model based on the synaptic interactions recorded by Elliott and Benjamin (1985a,b; J. Neurophysiol. 54, 1396-1421).
A Comparative Study of Host Recognition and the Sense of Taste inLeptinotarsa
Authors: Sperling J. L. Haley , Mitchell B. K.
Published: April 2021

Three species of Leptinotarsa beetles (L. decemlineata, L. texana and L. haldemani) with different host plant specificity were studied using behavioural and sensory physiological measures in an attempt to determine whether responses from chemosensory cells in the galeal sensilla of adult beetles vary with host plant preference in an understandable manner. Saps from leaves of Solarium tuberosum, S. elaeagnifolium, S. dulcamara and Lycopersicon esculentum were used as sensory stimuli. Behavioural observations were made on newly emerged adults and approach time, exploration time and number of bites in the first minute of the first meal were recorded. Number of bites in the first minute of the first meal differed across the four plant species for the three beetle species. For L. decemlineata and L. texana, sensory responses from cells in the galeal sensilla showed differences across plant species that could be related to host preference. It is suggested that at least two general types of sensory coding may be involved in host recognition by beetles in this genus. First, a ‘coarse-grained’ code based on degree of variability of input may operate to help the insect distinguish non-solanaceous plants from solanaceous ones. Second, a ‘fine-grained’ code may help distinguish host from non-host within the family Solanaceae or perhaps within the genus Solanum. This fine-grained code may have elements of both the labelled line and across-fibre pattern codes discussed in the literature.
Partitioning of Acid-Base Regulation Between Renal and Extrarenal Sites in the Adult, Terrestrial Stage of the Salamander Ambystoma Tigrinum During Respiratory Acidosis
Authors: Stiffler Daniel F.
Published: April 2021

Adult Ambystoma tigrinum were cannulated non-occlusively in the truncus arteriosus and subjected to 24 h of hypercapnia in 3% CO2. Adults showed the typical compensatory pattern, shared by larvae and many other amphibians, of partial compensation (44%) for the induced respiratory acidosis. Adults whose urinary bladders were ligated to allow the urine to bypass the bladder compensated as well as shams, indicating that the urinary bladder of this species is not necessary for compensation. Radioisotopic measurements of net and unidirectional fluxes of Na+ or Cl- in whole animals showed no effects of hypercapnia. Partitioning of acid-base responses showed that 75–80 % of the regulation takes place across the skin. The rest is accomplished by the kidneys. This did not change during hypercapnia and there was no evidence of renal involvement in the compensation. Total ammonia (NH3+NH4+) comprised only about one-sixth of the total cutaneous acid excretion. The charge associated with the cutaneous excretion of H+ equivalents was balanced by both Na+ uptake and Cl- loss. In contrast to larvae, whose cutaneous electrical potential difference (PD) increases during hypercapnia, adults decrease their PD. This could mean that acidosis stimulates an electrogenic H+ secretion and/or that cutaneous Na+ and Cl-permeabilities change. Both possibilities are consistent with the data.
Function of a Muscle Whose Apodeme Travels through a Joint Moved by Other Muscles: Why the Retractor Unguis Muscle in Stick Insects is Tripartite and Has No Antagonist
Authors: Radnikow G. , Bässler U.
Published: April 2021

The course of the common apodeme of the tripartite retractor unguis muscle is described for the stick insects Carausius morosus and Acrophylla wulfingii. This apodeme travels through the femoro-tibial joint well outside the axis of rotation of the joint, but movements of the femoro-tibial joint do not affect the position of the tarsal claws, which are moved by the retractor unguis muscle. The independence of tarsal position upon tibial position is not produced by a neural compensation mechanism but by a sophisticated morphological arrangement combined with specialized physiological properties. These mechanisms consist of two parts. (1) Moderate claw flexions are mainly produced by the smaller tibial parts of the muscle and their influence on claw position is not affected by tibial position, because they lie distal to the femoro-tibial joint. (2) The retractor unguis muscle works against strong elastic structures and the claw assumes the position where the elastic force is counterbalanced by the muscle force. The maximum muscle force of the strong femoral part of the muscle is nearly independent of muscle length. Therefore, the force it transfers to the elastic structures is also nearly independent of tibial position.
Dynamic Properties of Orientation to a Visually Fixated Target by Walking Colorado Beetles
Authors: Lönnendonker Ulrich
Published: April 2021

The dynamic components of the fixation behaviour of walking Colorado beetles were examined. The beetles walked on top of a locomotion compensator under closed-loop conditions. The fixation target was a yellow disk with small black stripes (‘Colorado dummy’). The paths of beetles walking towards the stationary dummy were characterized by oscillations, and were investigated by applying a fast Fourier transform to the turning-velocity time course. The power density peaks near 0.3 Hz with varying amplitude. Films of the fixation reaction revealed that this frequency was much slower than the stepping-pattern frequency of the beetles. During orientation to other stimuli (wind or gravity), the oscillations were not present, showing that they were not an artefact of the motor output. However, they were present in other forms of visual orientation, such as the optomotor response and during positive phototaxis.

A frequency-response curve (Bode diagram) under closed-loop conditions was obtained for the fixation reaction by changing the dummy position sinusoidally and measuring the phase and amplitude of the tracking response. A simple model of this behaviour, including a low-pass filter and an integrator, describes the reaction. Hence, the reaction can be understood as the simple resonance behaviour of an underdamped closed-position loop. The question of whether this can explain zigzagging paths in other species is discussed.
Sensory Coding for Feeding Deterrence in the Grasshopper Schistocerca Americana
Authors: Chapman R. F. , Ascoli-Christensen A. , White P. R.
Published: April 2021

The electrophysiological responses of sensilla on the tibia of Schistocerca americana (Drury) to six compounds were examined. All the compounds were shown to cause feeding deterrence at high concentrations. Nicotine hydrogen tartrate, quinine, hordenine (all alkaloids) and salicin (a phenolic glycoside) all stimulated one cell in each sensillum. This was shown by differential adaptation experiments to be the same cell. In some sensilla this cell also responded to linamarin (a cyanogenic glycoside). Earlier work had shown that the activity of this cell was correlated with feeding deterrence. However, canavanine (a nonprotein amino acid) did not stimulate this cell, although it caused feeding deterrence. All the compounds, except salicin, produced a marked depression in the activity of cells responding to sucrose, and at higher concentrations of the compounds this inhibition was almost complete.

The activity of the deterrent cell and inhibition of the activity of sucrosesensitive cells appear to act together to produce the behavioural effects of most chemicals, but canavanine appears to act only by suppressing the activity of other cells and salicin primarily through activity of the deterrent cell. In addition, quinine disrupts the activity of all the cells and in its presence the deterrent cell adapts very slowly so that the message signalling deterrence is sustained.

At low concentrations, salicin, and probably hordenine, increased the duration of feeding. In the case of hordenine this was due to an increase in the firing rate of sucrose-sensitive neurones; with salicin the increase was associated with a high threshold of response and a rapid rate of adaptation of the deterrent cell.

Thus, similar behavioural effects are produced by a variety of sensory phenomena with each compound acting in a slightly different manner from the others.
Energetics and Power Output of Isolated Fish Fast Muscle Fibres Performing Oscillatory Work
Authors: Moon T. W. , Altringham J. D. , Johnston I. A.
Published: April 2021

Fast myotomal muscle fibres were isolated from the cod (Gadus morhua L.) and the energy cost of contraction was measured under conditions simulating swimming. Fibre bundles were subjected to sinusoidal cycles of shortening and lengthening about their in situ fibre length, and stimulated at selected phases in each cycle. The preparations were poisoned with iodoacetic acid and bubbled with nitrogen to block the synthesis of ATP. After an initial rapid decline over the first 10 cycles, force and net work remained steady in some cases for up to 64 oscillatory length cycles, but more commonly declined slowly after about 30 cycles. The total mechanical work performed increased largely in proportion to the number of work cycles. At the end of each experiment fibres were frozen in isopentane cooled in liquid nitrogen and metabolite concentrations determined by high performance liquid chromatography (HPLC) and enzymatic analysis. Concentrations of adenylates did not differ significantly from control values, although a significant increase in IMP concentrations at 64 cycles accounted for the maintenance of relatively high energy charge values. Creatine (C) concentrations increased and creatine phosphate (CP) concentrations decreased, implying a tight coupling of the ATP/ADP reaction to the CP/C reaction. Muscle economy was calculated as the positive work performed during a work cycle divided by the total chemical energy expended. These values (approx. 7mJ μmol−1) were found to be independent of the number of work cycles performed, although a trend to increase was observed. Muscle efficiency values, calculated assuming a Gibb’s force free energy change for CP splitting in vivo of 55 kJ mol−1, were in the range 12 – 23%.
Efficiency Of Energy Conversion During Shortening Of Muscle Fibres From The Dogfish Scyliorhinus Canicula
Authors: Curtin N. A. , Woledge R. C.
Published: April 2021

Force and heat production were measured during isovelocity shortening of tetanized white myotomal muscle fibres from the dogfish at 12 °C. For each fibre preparation a range of velocities was used. Mechanical power was calculated from force x velocity of shortening. The rate of total energy output during shortening was evaluated as the sum of mechanical power and the rate of heat production. The ratio of mechanical power to total energy rate was taken as a measure of efficiency of energy conversion to mechanical power during shortening. Efficiency was maximal and varied little in the range of shortening velocities 0.42–0.89 fibres lengthss−1 (0.11–0.23 Vmax); maximal efficiency was 0.33±0.01 (±S.E.M., N=23 measurements on seven fibre bundles). The efficiency of the white fibres from dogfish was less than that measured in the same way in earlier experiments on frog muscle and tortoise muscle.
The Pharmacology of Cholinoceptors on the Somatic Muscle Cells of the Parasitic Nematode Ascaris Suum
Authors: Colquhoun L. , Holden-Dye L. , Walker R. J.
Published: April 2021

Acetylcholine (ACh) elicited depolarization and an increase in input conductance of the somatic muscle cells of the parasitic nematode Ascaris suum. The relative potency of nicotinic and muscarinic agents was studied in this preparation. The order of potency of these compounds was metahydroxy phenylpropyltrimethylammonium (HPPT) > 1,1 dimethyl–4-phenylpiperazinium (DMPP) > ACh> carbachol> nicotine> tetramethylammonium (TMA+)> muscarone> furtrethonium> arecoline. Decamethonium was also a weak agonist. McN-A-343 elicited a very weak depolarization at concentrations above 1 mmol 1−1. Bethanechol and methacholine were without effect up to 1 mmol 1−1. Pilocarpine and muscarine elicited a slight hyperpolarization of up to 3 mV with a threshold for the response of around 500 μmol 1−1. Oxotremorine (1 mmol 1−1) was without effect. The nitromethylene insecticide 2(nitromethylene)tetrahydro 1,3-thiazine (NMTHT), an agonist at insect nicotinic receptors, was without effect on Ascaris muscle cells up to 1 mmol 1−1. Mecamylamine and benzoquinonium were the most potent antagonists of the acetylcholine response. The order of potency of the other antagonists was tetraphenylphosphonium (TPP) > quinacrine > pancuronium, curare > trimethaphan > atropine > chlorisondamine, Decamethonium > hexaméthonium > dihydro-β-ery throidine. The agonist profile of the Ascaris muscle cell ACh receptor clearly indicates that it is nicotinic. The potency of ganglionic and neuromuscular nicotinic receptor antagonists in Ascaris does not enable a further subclassification of this nicotinic receptor. The Ascaris nicotinic receptor seems to possess some of the pharmacological properties of each type of vertebrate nicotinic receptor. The pharmacology of the Ascaris nicotinic receptor is discussed in relation to that of nicotinic receptors in other invertebrate preparations and in vertebrate preparations.
The Physiology of the Alligator Heart: the Cardiac Cycle
Authors: Shelton G. , Jones D. R.
Published: April 2021

Pressure recordings from the heart and major arteries of the alligator show that a conventional relationship exists between the left ventricle and the right aorta. Pressure gradients from ventricle to aorta during systole are very small. Right aortic blood flow rises rapidly to a single peak and then falls more gradually until aortic valve closure.

The right ventricle is connected both to the pulmonary arteries and to the left aorta. Right ventricular pressures show that systole is a two-stage process. Initially, blood leaves to the low-resistance lung circuit, though appreciable pressure gradients exist across the pulmonary outflow tract. Active contraction of the pulmonary outflow tract stops pulmonary ejection and a second-stage pressure rise is seen in the right ventricle.

When systemic blood pressures are high, this second-stage pressure does not reach the levels recorded in the left aorta, and the left aortic valves remain closed so that lung and body circuits are functionally separate. An alternation of flow is found in the left aorta under these conditions, with reversed flow during systole and forward flow during diastole. Flow rates are extremely low, compared with those in the right aorta or pulmonary arteries, and the foramen of Panizza has very little significance in the cardiac cycle.

If the systemic blood pressures are low, the second stage of systole in the right ventricle gives rise to pressures that are higher than those in the left aorta, the left aortic valves open and blood is ejected to the systemic circulation, giving a right-to-left shunt. This can occur with no changes in pulmonary pressures or flows. Left aortic flow is not dependent on increased constriction of the pulmonary outflow tract, which continues to function as an on-off active valve. Constriction within the lung vasculature may, on some occasions, be significant in establishing left aortic flow, but it is clear from the present work that low systemic blood pressure is a factor of crucial importance.
Kinematics of Tongue Projection in Chamaeleo Oustaleti
Authors: WAINWRIGHT PETER C. , KRAKLAU DAVID M. , BENNETT ALBERT F.
Published: April 2021

The kinematics of prey capture by the chamaeleonid lizard Chamaeleo oustaleti were studied using high-speed cinematography. Three feeding sequences from each of two individuals were analyzed for strike distances of 20 and 35 cm, at 30°C. Ten distances and angles were measured from sequential frames beginning approximately 0.5 s prior to tongue projection and continuing for about 1.0 s. Sixteen additional variables, documenting maximum excursions and the timing of events, were calculated from the kinematic profiles. Quantified descriptions of head, hyoid and tongue movements are presented. Previously unrecognized rapid protraction of the hyobranchial skeleton simultaneously with the onset of tongue projection was documented and it is proposed that this assists the accelerator muscle in powering tongue projection. Acceleration of the tongue occurred in about 20ms, reaching a maximum acceleration of 486 m s−2 and maximum velocity of 5.8m s−1 in 35 cm strikes. Deceleration of the tongue usually began within 5 ms before prey contract and the direction of tongue movement was reversed within 10 ms of prey contact. Retraction of the tongue, caused by shortening of the retractor muscles, reached a maximum velocity of 2.99 ms−1 and was complete 330 ms after prey contact. Projection distance influences many aspects of prey capture kinematics, particularly projection time, tongue retraction time and the extent of gape and head movements during tongue retraction, all of which are smaller in shorter feedings. Though several features of the chameleon strike have apparently been retained from lizards not capable of ballistic tongue projection, key differences are documented. Unlike members of a related family, the Agamidae, C. oustaleti uses no body lunge during prey capture, exhibits gape reduction during tongue projection and strongly depresses the head and jaws during tongue retraction.

Note:

Present address: Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA.
Linkage Biomechanics and Evolution of the Unique Feeding Mechanism of Epibulus Insidiator (Labridae: Teleostei)
Authors: WESTNEAT MARK W.
Published: April 2021

Epibulus insidiator (Pallas) possesses the most extreme jaw protrusion ever measured in fishes. Biomechanical models of the mechanisms of jaw protrusion and hyoid depression in Epibulus are proposed and tested. The models are designed using principles of four-bar linkages from engineering theory. The models calculate the geometry of the feeding mechanisms from morphometric data on cranial anatomy. Predictions made from the models about the feeding kinematics of Epibulus are tested by comparison with kinematic data. The model of the jaw mechanism is accurate in predicting the unique feeding mechanics of the jaws of Epibulus for most relationships between kinematic variables. A model of simultaneous cranial elevation and sternohyoideus muscle contraction is accurate in predicting hyoid depression during feeding. Biomechanical considerations limit the number of possible pathways of evolution of the jaw mechanism of Epibulus from that of its closest labrid relatives.