bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of Cell Ageing on Metabolism in Rainbow Trout (Oncorhynchus Mykiss) Red Blood Cells
Authors: Phillips M. C. L. , Moyes C. D. , Tufts B. L. 
Published: April 2021

ABSTRACT
The effects of cell age on metabolism in the nucleated red blood cells of rainbow trout (Oncorhynchus mykiss) were examined. Red blood cells were separated according to age using fixed-angle centrifugation. The mean erythrocyte haemoglobin concentration in old red blood cells was found to be 120 % of that in young red blood cells. In young red blood cells, the activities of the mitochondrial enzymes citrate synthase and cytochrome oxidase were 135–200 %, respectively, of those measured in old red blood cells. The activity of the glycolytic enzyme lactate dehydrogenase in young red blood cells was 170 % of that in old red blood cells, whereas the activity of the glycolytic enzyme pyruvate kinase was not significantly affected by cell age. In addition, young red blood cells consumed over twice as much O2 and devoted 50 % more O2 to protein synthesis and the activity of Na+/K+-ATPase than old red blood cells. Red blood cell age did not significantly affect the rate of lactate production. This study shows that ageing in rainbow trout nucleated red blood cells is accompanied by a significant decline in aerobic energy production and the processes it supports, as well as a corresponding increase in the glycolytic contribution to metabolism.
Analysis of the Three-Dimensional Trajectories of Organisms: Estimates of Velocity, Curvature and Torsion From Positional Information
Authors: Crenshaw Hugh C. , Ciampaglio Charles N. , Mchenry Matthew 
Published: April 2021

ABSTRACT
Most biological motions are three-dimensional. This includes the trajectories of whole organisms and of their appendages. While recordings of three-dimensional trajectories are sometimes published, quantitative analysis of these trajectories is uncommon, primarily because there are no standard techniques or conventions in biology for the analysis of three-dimensional trajectories. This paper describes a new technique, finite helix fit (FHF), based on the geometry of three-dimensional curves, whereby a three-dimensional trajectory is completely described by its velocity, curvature and torsion. FHF estimates these parameters from discretely sampled points on a trajectory (i.e. from positional data such as x,y,z coordinates). Other measures of motion can be derived from these parameters, such as the translational and rotational (or angular) velocities of an organism. The performance of the algorithms is demonstrated using simulated trajectories and trajectories of freely swimming organisms (a flagellate, Chlamydomonas reinhardtii; a ciliate, Paramecium tetraurelia; spermatozoa of a sea urchin, Arbacia punctulata; larvae of an ascidian, Botrylloides sp.).
Lack of Effect of Ageing on Acetate Oxidation in Rat Skeletal Muscle During Starvation: A 13C NMR Study
Authors: Mezzarobba V. , Bielicki G. , Jeffrey F. M. H. , Mignon M. , Renou J. P. , Grizard J. , Meynial-Denis D. 
Published: April 2021

ABSTRACT
Acetate oxidation was examined by 13C nuclear magnetic resonance in skeletal muscle from adult and old rats. Rats fasted for 5 days were perfused with [2-13C]acetate over 2 h, and muscle extracts were analyzed for [13C]glutamate isotopomers. This study shows that approximately 80 % of acetyl-coenzyme A entering the tricarboxylic cycle was derived from substrate infusion in both adult and old rats, and that the flux through anaplerotic pathways was approximately 21 % of the flux through citrate synthase. These data demonstrate that skeletal muscle from adult and old rats oxidizes the same proportion of exogenous acetate.
Lateral Optic Flow Does Not Influence Distance Estimation in the Desert Ant Cataglyphis Fortis
Authors: Ronacher B. , Gallizzi K. , Wohlgemuth S. , Wehner R. 
Published: April 2021

ABSTRACT
The present account answers the question of whether desert ants (Cataglyphis fortis) gauge the distance they have travelled by using self-induced lateral optic-flow parameters, as has been described for bees. The ants were trained to run to a distant food source within a channel whose walls were covered with black-and-white gratings. From the food source, they were transferred to test channels of double or half the training width, and the distance they travelled before searching for home and their walking speeds were recorded. Since the animals experience different motion parallax cues when walking in the broader or narrower channels, the optic-flow hypothesis predicted that the ants would walk faster and further in the broader channels, but more slowly and less far in the narrower channels. In contrast to this expectation, neither the walking speeds nor the searching distances depended on the width or height of the channels or on the pattern wavelengths. Even when ventral-field visual cues were excluded by covering the eyes with light-tight paint, the ants were not influenced by lateral optic flow-field cues. Hence, walking desert ants do not depend on self-induced visual flow-field cues in gauging the distance they have travelled, as do flying honeybees, but can measure locomotor distance exclusively by idiothetic means.
Active Osmoregulatory Ion Uptake Across the Pleopods of the Isopod Idotea Baltica (Pallas): Electrophysiological Measurements on Isolated Split Endo- and Exopodites Mounted in a Micro-Ussing Chamber
Authors: Postel Ute , Becker Wilhelm , Brandt Angelika , Luck-Kopp Susanne , Riestenpatt Sven , Weihrauch Dirk , Siebers Dietrich 
Published: April 2021

ABSTRACT
The mechanism of active, osmoregulatory ion uptake was investigated in the pleopods of the marine isopod Idotea baltica (Pallas). Using isolated split half-podites of isopods acclimated to brackish water (20 ‰ salinity) mounted in a micro-Ussing chamber and symmetrically superfused with identical haemolymph-like salines, a mean short-circuit current Isc of −445 µA cm−2 was measured in endopodites 3–5, corresponding to an inwardly directed transcellular movement of negative charge. Application of ouabain (5 mmol l−1) to the basolateral superfusate resulted in the almost total abolition of the Isc (reduced from −531 to −47 µA cm−2), suggesting that the Na+/K+-ATPase is the driving force for active, electrogenic uptake of NaCl. In contrast, mean Isc values close to zero were found in preparations of all exopodites and in endopodites 1 and 2. The specific activities of Na+/K+-ATPase corresponded with these results. Specific activities were highest in posterior endopodites 3–5 and depended on ambient salinity. In all other rami, the activities were much lower and independent of ambient salinity. Activities in posterior endopodites 3–5 were lowest in isopods acclimated to 30 ‰ salinity (2–4 µmol Pi mg−1 protein h−1), increased in individuals kept in 20 ‰ salinity (8.4 µmol Pi mg−1 protein h−1) and were highest in isopods acclimated to 15 ‰ salinity (18.2 µmol Pi mg−1 protein h−1). When specimens were transferred from 30 to 40 ‰ salinity, Na+/K+-ATPase activity increased in the posterior endopodites. The electrophysiological and Na+/K+-ATPase activity measurements show that active electrogenic ion transport in this species occurs almost exclusively in posterior endopodites 3–5. The endopodite of the fifth pleopod of I. baltica exhibited a microscopic structure remarkably similar to that described for the lamellae of the phyllobranchiae of brachyurans. It is composed of two opposed epithelial monolayers of ionocytes, each covered by cuticle. Bundles of pillar cells are located within the ionocyte layers, which are separated by a fenestrated lamellar septum of connective tissue. The results obtained in this study indicate that endopodites 3–5 play the main role in osmoregulatory ion uptake of the isopod I. baltica. Moreover, the Na+/K+-ATPase is the only driving force behind active electrogenic ion uptake across the epithelial cells.
Insulin and Igf-I Receptors in Trout Adipose Tissue are Physiologically Regulated by Circulating Hormone Levels
Authors: Planas Josep V. , Méndez Eva , Baños Núria , Capilla Encarnación , Navarro Isabel , Gutiérrez Joaquim 
Published: April 2021

ABSTRACT
In fish, insulin is believed to act on adipose tissue to promote lipid accumulation, but a direct role for insulin in fish adipose tissue lipogenesis has yet to be demonstrated. To investigate the role of insulin and insulin-like growth factor I (IGF-I) in fish adipose tissue function, we have investigated the presence and the regulation of insulin and IGF-I receptors in adipose tissue of brown trout (Salmo trutta). Receptors for insulin and IGF-I were detected in trout adipose tissue, with IGF-I receptors being more abundant (two- to tenfold) and having a higher affinity (twofold) than insulin receptors. In contrast to the situation in mammals, arginine treatment, which elevates the levels of insulin and IGF-I in plasma, increased the number of insulin receptors 1.7-fold and the number of IGF-I receptors 2.3-fold. When plasma levels of insulin and IGF-I were decreased by fasting, insulin receptor numbers fell 3.6-fold and IGF-I receptor numbers fell 2.2-fold. These results demonstrate for the first time the presence of specific insulin and IGF-I receptors in adipose tissue of ectothermic vertebrates and suggest that adipose tissue may be a target for the actions of insulin and IGF-I in fish.
Heat Production and Oxygen Consumption During Metabolic Recovery of White Muscle Fibres from the Dogfish Scyliorhinus Canicula
Authors: Lou F. , Laarse W. J. Van Der , Curtin N. A. , Woledge R. C. 
Published: April 2021

ABSTRACT
Oxygen consumption and heat production were measured during contraction and recovery of isolated, white muscle fibres from dogfish (Scyliorhinus canicula) at 19 °C. The contraction period consisted of 20 isometric twitches at 3 Hz; this was followed by a recovery period of 2 h without stimulation.
We tested the hypothesis that recovery is wholly oxidative (not glycolytic) in these fibres. The following features support this hypothesis. (i) The ratio of total heat produced to oxygen consumed, 451±34 kJ mol−1 (mean ± S.E.M., N=29), was close to that expected for either the oxidation of carbohydrate, 473 kJ mol−1, or the oxidation of fat, 439 kJ mol−1. Even assuming the maximum value (95 % confidence limit) of the observed heat production, glycolysis could account for resynthesis of at most 18 % of the ATP used during the contractions. (ii) When the difference in rates of diffusion of oxygen and heat within the muscle are taken into account, the time courses of oxygen consumption and heat production match each other well during the entire recovery period.
The efficiency of recovery (=energy used for ATP synthesis/energy available for ATP synthesis) was estimated from the results. This value, 84.0±20.1 % (mean ± S.E.M., N=29), is relatively high and represents the first such measurement in functioning muscle.
Branchial Receptors and Cardiorespiratory Reflexes in A Neotropical Fish, The Tambaqui (Colossoma Macropomum)
Authors: Sundin Lena , Reid Stephen G. , Rantin F. Tadeu , Milsom William K. 
Published: April 2021

ABSTRACT
This study examined the location and physiological roles of branchial chemoreceptors involved in the cardiorespiratory responses to hypoxia and hypercarbia in a neotropical fish that exhibits aquatic surface respiration, the tambaqui (Colossoma macropomum). Fish were exposed to abrupt progressive environmental hypoxia (18.6–1.3 kPa water ) and hypercarbia (water equilibrated with 5 % CO2 in air, which lowered the water pH from 7.0 to 5.0). They were also subjected to injections of NaCN into the ventral aorta (to stimulate receptors monitoring the blood) and buccal cavity (to stimulate receptors monitoring the respiratory water). All tests were performed before and after selective denervation of branchial branches of cranial nerves IX and X to the gill arches. The data suggest that the O2 receptors eliciting reflex bradycardia and increases in breathing frequency are situated on all gill arches and sense changes in both the blood and respiratory water and that the O2 receptors triggering the elevation in systemic vascular resistance, breathing amplitude, swelling of the inferior lip and that induce aquatic surface respiration during hypoxia are extrabranchial, although branchial receptors also contribute to the latter two responses. Hypercarbia also produced bradycardia and increases in breathing frequency, as well as hypertension, and, while the data suggest that there may be receptors uniquely sensitive to changes in CO2/pH involved in cardiorespiratory control, this is based on quantitative rather than qualitative differences in receptor responses. These data reveal yet another novel combination for the distribution of cardiorespiratory chemoreceptors in fish from which teleologically satisfying trends have yet to emerge.
The Effects of Temperature on the Burial Performance and Axial Motor Pattern of the Sand-Swimming of the Mojave Fringe-Toed Lizard Uma Scoparia
Authors: Jayne Bruce C. , Daggy Matthew W. 
Published: April 2021

ABSTRACT
Although lateral axial bending is widespread for the locomotion of ectothermic vertebrates, the axial motor patterns of terrestrial taxa are known only for a limited number of species and behaviors. Furthermore, the extent to which the trunk and tail of ectothermic tetrapods have similar motor patterns is poorly documented. We therefore recorded the activity of the epaxial muscles in the trunk and tail of sand-swimming Mojave fringe-toed lizards (Uma scoparia) to determine whether this specialized behavior has features of the motor pattern that differ from those of diverse ectothermic vertebrates. Muscle activity during initial sand-swimming was a standing-wave pattern in the trunk and tail. Next, the hind limbs moved alternately and the caudofemoralis muscles and nearby axial muscle in the trunk and tail had similar long-duration electromyographic bursts, whereas the anterior trunk had shorter, more frequent electromyographic bursts. The final tail burial involved a traveling wave of posteriorly propagated axial muscle activity within localized regions of the tail. With increased temperature (from 22 to 40 °C), the mean frequencies of axial oscillations increased from approximately 7 to 21 Hz, and the greatest value (33 Hz) was nearly twice the maximal limb cycling frequency during running. The mean burial time at the lowest temperature (3.8 s) was nearly twice that for a 10 °C higher temperature. For the axial electromyograms, a decrease in temperature of 18 °C more than doubled the electromyographic and cycle durations, whereas the duty factors and intersegmental phase lags changed only slightly with temperature.
Oxygen-Sensitive Membrane Transporters in Vertebrate Red Cells
Authors: Gibson J. S. , Cossins A. R. , Ellory J. C. 
Published: April 2021

ABSTRACT
Oxygen is essential for all higher forms of animal life. It is required for oxidative phosphorylation, which forms the bulk of the energy supply of most animals. In many vertebrates, transport of O2 from respiratory to other tissues, and of CO2in the opposite direction, involves red cells. These are highly specialised, adapted for their respiratory function. Intracellular haemoglobin, carbonic anhydrase and the membrane anion exchanger (AE1) increase the effective O2- and CO2-carrying capacity of red cells by approximately 100-fold. O2 also has a pathological role. It is a very reactive species chemically, and oxidation, free radical generation and peroxide formation can be major hazards. Cells that come into contact with potentially damaging levels of O2have a variety of systems to protect them against oxidative damage. Those in red cells include catalase, superoxide dismutase and glutathione. In this review, we focus on a third role of O2, as a regulator of membrane transport systems, a role with important consequences for the homeostasis of the red cell and also the organism as a whole. We show that regulation of red cell transporters by O2is widespread throughout the vertebrate kingdom. The effect of O2 is selective but involves a wide range of transporters, including inorganic and organic systems, and both electroneutral and conductive pathways. Finally, we discuss what is known about the mechanism of the O2 effect and comment on its physiological and pathological roles.
Cranial Kinesis in Geckoes: Functional Implications
Authors: Herrel Anthony , Aerts Peter , Vree Frits De 
Published: April 2021

ABSTRACT
Although it is generally assumed that cranial kinesis is a plesiomorphic characteristic in squamates, experimental data tend to contradict this hypothesis. In particular, coupled kinesis (i.e. streptostyly and mesokinesis) presumably arose independently in only a limited number of highly specialised groups. In this study, we investigated cranial kinesis in one of the most specialised of these groups: geckoes. On the basis of cineradiographic and electromyographic data, the fast opening and the slow closing/power stroke phases were modelled to elucidate possible functions of the observed kinesis. The results of these analyses show that the retraction of the muzzle unit during crushing is a self-reinforcing system that increases bite force and reduces the joint forces; the active protraction of the kinetic system during jaw opening, in contrast, enhances opening speed through the coupling of the intracranial units. It can be argued that cranial kinesis in geckoes is probably not an adaptive trait as such but, instead, a consequence of the ‘Bauplan’ of the cranial system in these animals. Presumably as a result of constructional constraints on the size of the jaw musculature and eyes, the supratemporal and postorbital bars were lost, which resulted in enormous mobility in the skull. To counteract the potential negative factors associated with this (decrease in bite force, skull damage), the kinetic system may have become coupled, and thus functional.
Changes in the Electric Organ Discharge After Pausing the Electromotor System Of Gymnotus Carapo
Authors: Schuster Stefan 
Published: April 2021

ABSTRACT
During their entire lives, weakly electric fish produce an uninterrupted train of discharges to electrolocate objects and to communicate. In an attempt to learn about activity-dependent processes that might be involved in this ability, the continuous train of discharges of intact Gymnotus carapo was experimentally interrupted to investigate how this pausing affects post-pause electric organ discharges. In particular, an analysis was conducted of how the amplitude and relative timing of the three major deflections of the complex discharge change over the course of the first 1000 post-pause discharges. The dependence of these variables on the duration of the preceding pause and on water temperature is analysed. In addition, pause-induced small reverberations at the end of the discharge are described. Common to all amplitude changes is a fast initial decrease in amplitude with a slow recovery phase; amplitude changes scale with the duration of the preceding pause and are independent of the interdischarge interval. The absence of changes in the postsynaptic-potential-derived first phase of the discharge together with changes in the amplitude ratio of the third and fourth deflections suggest that the amplitude changes are mainly due to pause-induced changes in the inner resistance of the electric organ. A model is formulated that approximates the pattern of amplitude changes. The post-pause changes described here may provide a new way to test current models of complex discharge generation in Gymnotus carapo and illustrate the speed at which changes of an electric organ discharge can take place.
Graded Neuromuscular Transmission in the Heart Of The Isopod Crustacean Ligia Exotica
Authors: Sakurai Akira , Yamagishi Hiroshi 
Published: April 2021

ABSTRACT
We present several lines of evidence for the occurrence of graded synaptic transmission in addition to impulse-mediated transmission at the neuromuscular junction between cardiac ganglion (CG) neurones and the myocardium in the isopod crustacean Ligia exotica. In the heart of adult Ligia exotica, the CG acts as a primary pacemaker for the heartbeat by generating periodic bursts of impulses and entrains the myogenicity of the myocardium via impulse-mediated excitatory junctional potentials. When impulse generation was blocked by tetrodotoxin (TTX; 50 nmol l−1), the CG neurones and the myocardium periodically exhibited synchronized slow depolarizing potentials. The association between the slow depolarizing potentials in the neurone and the myocardium was eliminated by application of Joro spider toxin (JSTX), a specific glutamate antagonist. When the CG neurone was made quiescent by a higher dose of TTX (1.0 μmol l−1), sinusoidal current injected into the CG neurone induced similar sinusoidal membrane potential responses in the myocardium. The sinusoidal muscle responses were eliminated by application of either JSTX or low-Ca2+ saline. Under voltage-clamp conditions, the myocardium exhibited periodic inward current responses to sinusoidal current stimuli applied to the CG neurone. The reversal potential for the current response of the myocardium was similar to that of the impulse-mediated excitatory junctional current (EJC). Extracellular macropatch recordings of EJCs made at the neuromuscular junctional site revealed the spontaneous appearance of miniature EJCs asynchronous with the CG spikes in addition to large spike-evoked EJCs. The miniature EJCs were present in saline containing TTX, and their frequency was strongly affected by the slow membrane potential change in the CG neurone. These results suggest that the CG neurones drive the myocardium by graded neuromuscular transmission in addition to impulse-mediated transmission in the heart of Ligia exotica.
Learned Discrimination of Pattern Orientation in Walking Flies
Authors: Campbell Holly R. , Strausfeld Nicholas J. 
Published: April 2021

ABSTRACT
To determine the pattern-orientation discrimination ability of blowflies, Phaenicia sericata, a learning/memory assay was developed in which sucrose served as the reward stimulus and was paired with one of two visual gratings of different orientations. Individual, freely walking flies with clipped wings were trained to discriminate between pairs of visual patterns presented in the vertical plane. During training trials, individual flies learned to search preferentially at the rewarded stimulus. In subsequent testing trials, flies continued to exhibit a learned preference for the previously rewarded stimulus, demonstrating an ability to discriminate between the two visual cues. Flies learned to discriminate between horizontal and vertical gratings, +45 ° (relative to a 0 ° vertical) and −45 ° gratings, and vertical and +5 ° gratings. Individual patterns of learning and locomotive behavior were observed in the pattern of exploration during training trials. The features of the visual cue critical for discrimination of orientation are discussed.