bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Feeding and Food Deprivation on Oxygen Consumption, Muscle Protein Concentration and Activities of Energy Metabolism Enzymes in Muscle and Brain of Shallow-Living (Scorpaena Guttata) and Deep-Living (Sebastolobus Alascanus) Scorpaenid Fishes
Authors: Yang Tzung-Horng , Somero George N. 
Published: April 2021

ABSTRACT
The effects of feeding and fasting were examined on the deep-living short-spine thornyhead (Sebastolobus alascanus) and the confamilial shallow-living spotted scorpionfish (Scorpaena guttata) to determine whether the low metabolic rate of the deeper-living species was in part a consequence of food deprivation in its habitat. Laboratory acclimation for periods of 90–115 days under either ad libitum feeding or complete fasting did not lead to similar rates of respiration in individuals of the two species held under identical conditions. Respiration of fish fed ad libitum was 52 % (S. guttata) or 68% (S. alascanus) higher than for fasted fish of the same species. Furthermore, the metabolic rates of freshly collected specimens of S. alascanus resembled those of laboratory-fasted fish. In white skeletal muscle, both total protein concentration and the activities of four enzymes of ATP metabolism, lactate dehydrogenase (LDH) and pyruvate kinase (PK) of glycolysis, malate dehydrogenase (MDH) and citrate synthase (CS, a citric acid cycle indicator), were lower in S. alascanus than in S. guttata. Within a species, protein concentration and activities of the four enzymes in white muscle, but not in brain, were higher in fed than in starved fish, although these differences were greater in S. alascanus than in S. guttata. During fasting, LDH and PK activity in white muscle of S. alascanus decreased much more than MDH and CS activity; decreases in enzyme activities in red muscle were smaller than those in white muscle. Activities of enzymes in white skeletal muscle of field-collected S. alascanus generally resembled those of the fasted specimens. In contrast, red muscle of field-collected S. alascanus, compared with that of either fed or starved laboratory-held specimens, had a highly glycolytic poise (high LDH and PK activities relative to MDH and CS activities), which may suggest that muscle enzyme activities in the field-collected fish reflect adaptation to the low oxygen level in its adult habitat, the oxygen minimum layer. The strong correlations found between tissue biochemical properties and respiration rate allow us to develop a predictive index for metabolic rate from simple biochemical analyses, e.g. white muscle protein content or CS activity. We conclude that the low metabolic rate of S. alascanus is due to at least four depth-related factors: reduced abundance of food, low temperature, low ambient oxygen concentration and darkness, which may select for reduced locomotory activity.
Pharmacological and Electrophysiological Characterization of a Postsynaptic Muscarinic Receptor in the Central Nervous System of the Cockroach
Authors: Corronc H. Le , Hue B. 
Published: April 2021

ABSTRACT
The properties of the postsynaptic muscarinic receptors of a ventral giant interneurone in the sixth abdominal ganglion of the cockroach were studied using the single-fibre oil-gap technique.
Pressure-ejections of 10−4 mol l−1 arecoline (ARE) and muscarine evoked a small (approximately 1mV), prolonged slow depolarization whereas the muscarinic agonist McN-A-343 (10−3 mol l−1) elicited only a fast transient depolarization. At a higher concentration, ARE (10−3 mol l−1) produced a biphasic depolarization composed of a fast depolarization followed by the slow depolarization. The fast depolarization was specifically inhibited by the nicotinic antagonist d-tubocurarine (dTC; 5×10−5 mol l−1) and the slow depolarization was blocked by muscarinic antagonists such as atropine (ATR; 10−5 mol l−1), scopolamine (10−6 mol l−1) and quinuclidinyl benzilate (10−6 mol l−1). The ARE-induced slow depolarization was reduced by 10−5 mol l−1 pirenzepine, but neither methoctramine (10−5 mol l−1) nor 4-DAMP (10−5 mol l−1) modified the slow depolarization. The McN-A-343-induced depolarization was fully blocked by dTC. The slow depolarization was tetrodotoxin-insensitive and was unchanged when the external Na+ concentration was reduced by half. Tetraethylammonium (5×10−3 moll−1) and Ba2+ (5.4×10−3 moll−1) inhibited the slow depolarization. The inward K+ current induced by pressure-ejections of high-K+ saline was reduced by ARE but no increase of the membrane resistance was observed. The calcium channel blockers Co2+ (2×10−3 mol l−1), Cd2+ (10−3 moll−1) and La3+ (10−3 moll−1) did not modify the muscarinic response. The threshold of action potentials triggered by presynaptic stimulation was reduced by ARE and increased by ATR.
These results suggest that muscarinic receptors are present on cockroach ventral giant interneurones and that they can reduce a K+ conductance and increase an unknown conductance. The physiological role of these receptors might be to reduce the spike threshold and consequently to modify the integrative properties of giant interneurones.
Thermal Acclimation Alters Both Adrenergic Sensitivity and Adrenoceptor Density in Cardiac Tissue of Rainbow Trout
Authors: Keen John E. , Vianzon Daisy-Mae , Farrell Anthony P. , Tibbits Glen F. 
Published: April 2021

ABSTRACT
We examined the effect of temperature acclimation on the sensitivity of the rainbow trout heart to adrenaline and on the density of β-adrenoceptors. The sensitivity of the heart was assessed using in situ working perfused heart and in vitro isometric ventricular strip preparations. When tested in situ and at acclimation temperature, hearts from fish acclimated to 8°C were approximately 10-fold more sensitive to adrenaline-supplemented perfusate than were hearts from fish acclimated to 18°C. The concentrations required for half-maximal stimulation (EC50) of myocardial power output were 1.9×10-8 mol l-1 adrenaline and 1.7×10-7 mol l-1 adrenaline for hearts acclimated to 8°C and 18°C, respectively. In vitro, isometric ventricular strip preparations demonstrated a similar increase in adrenergic sensitivity with cold-acclimation. The EC50 values for maximal tension development were 2.7×10-7 mol l-1 adrenaline (8°C-acclimated) and 1.1×10-6 mol l-1 adrenaline (18°C-acclimated) when tested at acclimation temperature. This shift in adrenergic sensitivity was a function of the temperature acclimation because changes in bath temperature per se, either from 8°C to 18°C for 8°C-acclimated hearts or from 18°C to 8°C for 18°C-acclimated hearts, had no significant effect on the concentration–response curve for adrenaline.
We conducted radioligand binding studies with [125I]iodocyanopindolol and propranolol to quantify the β-adrenoceptor density (Bmax) of both homogenates and isolated sarcolemmal fractions of ventricles from rainbow trout acclimated to either 8°C or 18°C. The Bmax for isolated sarcolemmal fractions was significantly higher in the 8°C-acclimated group, but the Bmax of ventricular homogenates was not significantly different in the two acclimation groups. No significant differences in dissociation constant (Kd) were apparent in either the homogenates or sarcolemmal fractions. These results suggest that cardiac tissue from rainbow trout acclimated to 8°C has a greater cell surface adrenoceptor population available for -antagonist binding. This might explain the heightened cardiac sensitivity to adrenaline observed in situ and in vitro in 8°C-acclimated fish.
Extracellular Atp Selectively Modulates a High-Voltage-Activated Calcium Conductance in Salivary Gland Cells of the Leech Haementeria Ghilianii
Authors: Wuttke Werner A. , Berry Michael S. 
Published: April 2021

ABSTRACT
Extracellular ATP appears to have a widespread role as a neurotransmitter or neuromodulator in mammals (Gordon, 1986; Burnstock, 1990), but little is known about any similar functions in invertebrates. During studies of the effects of cyclic nucleotides on electrically excitable salivary cells of the leech, we found that cyclic GMP produced a rapid (less than 1min) reduction of spike duration, suggesting an extracellular effect (Wuttke and Berry, 1991). We now show that micromolar concentrations of ATP (and higher doses of other nucleotides) also reduce spike duration, and that this is caused by depression of a specific voltage-dependent Ca2+ conductance. Selective modulation of Ca2+ current by external ATP has rarely been found, and the effect is also unusual because it changes the kinetics of inactivation rather than those of activation.
Vortex Formation During Tethered Flight of Functionally and Morphologically Two-Winged Insects, Including Evolutionary Considerations on Insect Flight
Authors: Grodnitsky Dmitry L. , Morozov Pahvel P. 
Published: April 2021

ABSTRACT
Tethered flight of six insect species (two pentatomid bugs, a moth, a butterfly, a muscid fly and a crane fly) was studied using several modifications of a dust flow visualization procedure. The spatial structure of the near vortex wake of flying specimens was reconstructed on the basis of two-dimensional flow pictures. The dynamics of the wake was followed during a stroke cycle, revealing interspecific differences in vortex formation.
It is suggested that insects create a single vortex ring during each stroke. Therefore, the hypothesis of double vortex chains advanced by Brodsky is not verified. The same is true of the jet hypothesis of Bocharova-Messner. While pronating at the top of their trajectory, the flapping wings throw air masses off their lower surfaces, but there is not a jet from between their upper sides. Flow separation from leading edges was found to be a rare phenomenon, taking place irregularly during the stroke cycle. That is why, contrary to widespread theoretical expectations, the Weis-Fogh fling mechanism is not likely to contain a leading edge separation bubble, which must follow stalling at the front part of the wings.
It is suggested that flying animals possess special mechanisms for extracting energy back from the near vortex wake. Some hypothetical adaptations for such an extraction in insects are put forward. Possible pathways for the evolution of insect flight are described.
Ion Channel Activity in Lobster Skeletal Muscle Membrane
Authors: Worden Mary Kate , Rahamimoff Rami , Kravitz Edward A. 
Published: April 2021

ABSTRACT
Ion channel activity in the sarcolemmal membrane of muscle fibers is critical for regulating the excitability, and therefore the contractility, of muscle. To begin the characterization of the biophysical properties of the sarcolemmal membrane of lobster exoskeletal muscle fibers, recordings were made from excised patches of membrane from enzymatically induced muscle fiber blebs. Blebs formed as evaginations of the muscle sarcolemmal membrane and were sufficiently free of extracellular debris to allow the formation of gigaohm seals. Under simple experimental conditions using bi-ionic symmetrical recording solutions and maintained holding potentials, a variety of single channel types with conductances in the range 32–380pS were detected. Two of these ion channel species are described in detail, both are cation channels selective for potassium. They can be distinguished from each other on the basis of their single-channel conductance and gating properties. The results suggest that current flows through a large number of ion channels that open spontaneously in bleb membranes in the absence of exogenous metabolites or hormones.
The Behavioural State of Satiation in the Leech is Regulated by Body Distension and Mimicked by Serotonin Depletion
Authors: Groome James R. , Clark Madeline , Lent Charles M. 
Published: April 2021

ABSTRACT
The behavioural state of an organism consists of an array of constituent behaviours or responses which may be altered differentially as the behavioural state of an animal changes (Kupferman et al. 1991). The medicinal leech, Hirudo medicinalis, exhibits a long cycle in feeding behaviour (Dickinson and Lent, 1984). When they have not fed for some months, Hirudo exhibit an array of appetitive behaviours that are associated with the state of hunger. These leeches rest near the water surface and spontaneously initiate swimming bouts. Shadows, mechanical shocks or surface ripples alert hungry Hirudo, after which they swim towards a point source of water waves. Upon contacting a surface, leeches cease to swim and will explore the surface by crawling. If warmth is encountered at this time, hungry leeches will bite; biting is typically localized in or near surface folds.
Maximum Metabolism and the Aerobic Factorial Scope of Endotherms
Authors: Hinds David S. , Baudinette R. V. , Macmillen Richard E. , Halpern E. Annette 
Published: April 2021

ABSTRACT
Minimum and maximum metabolism in response to cold were measured in 30 species of Australian monotremes, marsupials, eutherians and birds. In marsupials and the echidna, maximum metabolism was also determined during treadmill locomotion. These data were used to determine, for the first time, the relationships between maximum metabolism and body mass in the four endothermic groups and to compare aerobic factorial scopes (the ratio of maximum to minimum metabolism) elicited by cold and locomotion. The effect of body mass on maximum metabolism is the same in marsupials and eutherians (the therians) but is significantly less in birds. At the same body mass, there is no difference between the two therian groups for either minimum or maximum metabolism induced by either cold or locomotion. Aerobic scope during cold is significantly higher in marsupials (8.3) than in eutherians (5.1), birds (5.4) and monotremes (5.4). Aerobic scope during locomotion in all groups is almost twice that observed in cold conditions.
Wing Movements and Lift Regulation in the Flight of Desert Locusts
Authors: Wortmann Michael , Zarnack Wolfram 
Published: April 2021

ABSTRACT
We simultaneously recorded lift/body weight, flight speed, body angle and 12 variables of wing movement for locusts performing tethered long-term flight with low movement scatter. The movements of the forewings and hindwings were recorded in three dimensions by means of miniature induction coils. By adjusting the body angle, we could reproducibly manipulate lift generation as a consequence of induced changes in the wings’ movement patterns. We were therefore able to analyse various relationships between the movement patterns and lift. The most prominent variations of kinematic variables were observed for the forewing movements. The relative lift and the steady angle of pitch were positively correlated but there was a negative correlation between relative lift and pitching amplitude. We found no correlation between relative lift and flapping amplitude. Our results seem to correspond to a new theory about unsteady aerodynamics of oscillating aerofoils. We sometimes observed variations in lagging. The forewing downstroke was delayed by 0–8ms following the hindwing downstroke. Relative lift was positively correlated to this delay.
Detection of Intense Ultrasound by the Cod Gadus Morhua
Authors: Astrup Jens , Møhl Bertel 
Published: April 2021

ABSTRACT
The ability of cod to detect intense 38kHz pulses was studied in an anechoic tank, using a classical cardiac conditioning method. All 15 cod studied reacted to 3ms pulses. The average threshold was 194.4dB re 1μPa (S.D. 5.4dB, S.E.M. 0.3dB). The data do not reveal the sensory modality involved. A number of additional experiments indicate that the ultrasonic energy per se is the effective stimulus. The threshold is too high for most sources of marine ultrasound to be detected, but is low enough to allow the cod to detect echolocating odontocetes at a range of 10–30m. The results also indicate that cod can detect echo-sounders of the fishing fleet at similar ranges.
Sensory and Neurosecretory Innervation of Leech Nephridia is Accomplished by a Single Neurone Containing FMRFamide
Authors: Wenning A. , Cahill M. A. , Hoeger U. , Calabrese R. L. 
Published: April 2021

ABSTRACT
The neural control of the excretory system of the medicinal leech Hirudo medicinalis has been characterized morphologically and chemically using light and electron microscopy, immunocytochemistry and biochemistry. Immunoreactivity against RFamide-like peptides revealed elaborate neuronal aborizations of a neurone in the nephridium, around the urinary bladder sphincter and in the central nervous system. The processes arose from the nephridial nerve cell (NNC), a previously identified receptor neurone. Using a combination of reverse-phase high pressure liquid chromatography, radioimmunoassay and subsequent Edman degradation and mass spectrometry, authentic FMRFamide has been identified as the major peptide of the NNC. Sensory and neurosecretory innervation of the nephridia is thus accomplished by a single neurone, which is thought to modulate nephridial performance.
Ventricular and Arterial Dynamics of Anaesthetised and Swimming Tuna
Authors: Jones David R. , Brill Richard W. , Bushnell Peter G. 
Published: April 2021

ABSTRACT
Cardiovascular dynamics of tuna have been investigated by recording blood pressures and flows in the central circulation of both anaesthetised and swimming individuals. In anaesthetised fish (N=5), heart rate averaged 112±21 beatsmin−1 (mean ± S.E.) and stroke volume was 0.67±0.24 mlkg−1 when normoxic water flowed over the gills. Ventricular diastolic pressure was zero until atrial contraction filled the ventricle. Ventral aortic pressures were high (mean 12.08±1.15kPa), and blood flow was continuous in the ventral aorta throughout diastole. Dorsal aortic pressure (mean 6.3±1.28kPa; N=4) and flow were both pulsatile. Pressure pulsatility (pulse pressure as a proportion of mean pressure) was about one-quarter of flow pulsatility, indicating considerable compliance in the dorsal aortic circulation. Total peripheral resistance averaged 0.17±0.4 kPaml−1 kg−1 min−1 of which gill resistance averaged 48±15% (N=4). For the ventral aorta, impedance modulus fell markedly from the mean value and then declined more gradually towards zero with increasing harmonic frequencies. Impedance phase was negative (−0.8 to −1.1rad) meaning that flow leads pressure at all harmonics. In swimming yellowfin tuna (N=5), heart rate averaged 108.8±12.1 beatsmin−1 and mean ventral and dorsal aortic pressures were 11.6±0.5 and 6.8±1.2kPa, respectively, so gill resistance was 42% of total peripheral resistance. Average stroke volume in three swimming kawakawa was 0.54±0.2mlkg−1 at a mean heart rate of 128±48 beatsmin−1. Data from swimming fish were within the range obtained from anaesthetised tuna. A simple model of the fish circulation consisting of two sets of compliant and resistive elements coupled in series (a second-order RC network) gave reasonable predictions of arterial pressure–flow relationships. Hence, we conclude that a ‘Windkessel’ dominates central cardiovascular dynamics of tuna despite heart rates and blood pressures that fall in the mammalian range.
Ontogeny of Hemocyanin Function in the Dungeness Crab Cancer Magister: The Interactive Effects of Developmental Stage and Divalent Cations on Hemocyanin Oxygenation Properties
Authors: Terwilliger Nora B. , Brown A. Christine 
Published: April 2021

ABSTRACT
Calcium and magnesium ions raise the oxygen affinities of 25S hemocyanins of both first-instar juvenile and adult Cancer magister. A physiologically relevant change in magnesium concentration from 16 to 32mmol l−1 changes first-instar juvenile hemocyanin affinity by 5.6mmHg (0.7kPa) but adult affinity by only 1.1mmHg (0.15kPa). In early juvenile crabs, the higher magnesium sensitivity of the hemocyanin may be compensated for by the lower oxygen affinity, which has been shown previously to be 50% lower than that of the adult under identical experimental conditions. Furthermore, ontogeny of ionic and osmotic regulation occurs during the development of C. magister, with especially high concentrations of magnesium being found in the hemolymph of early juveniles. Intermediate-stage juveniles (fifth to eighth instars) have hemocyanins with subunit stoichiometries and P50 values approaching those of the adult. These findings are significant because they indicate that modulation of C. magister hemocyanin oxygen-affinity during development incorporates differences in intrinsic affinity and differences in divalent cation sensitivity of the stage-specific hemocyanins.
in vivo Muscle Length Changes in Bumblebees and the in vitro Effects on Work and Power
Authors: Gilmour K. M. , Ellington C. P. 
Published: April 2021

ABSTRACT
The amplitude and time course of muscle length changes were examined in vivo in tethered, flying bumblebees Bombus lucorum. A ‘window’ was cut in the dorsal cuticle and aluminium particles were placed on the exposed dorsal longitudinal muscle fibres. Muscle oscillations were recorded using high-speed video and a high-magnification lens. The amplitude of muscle length changes was 1.9% (S.D.=0.5%, N=7), corresponding to the commonly quoted strain of 1–3% for asynchronous muscle. Higher harmonics, particularly the second, were found in the muscle oscillations and in the wing movements. The second harmonic for wing movements was damped in comparison to that for muscle length changes, probably as a result of compliance in the thoracic linkage. Inclusion of the second harmonic in the driving signal for in vitro experiments on glycerinated fibres generally resulted in a decrease in the work and power, but a substantial increase was found for some fibres.
Efficiency of Energy Conversion During Sinusoidal Movement of White Muscle Fibres from the Dogfish Scyliorhinus Canicula
Authors: Curtin N. A. , Woledge R. C. 
Published: April 2021

ABSTRACT
Net work output and heat production of white myotomal muscle fibres from the dogfish were measured during complete cycles of sinusoidal movement at 12°C. The peak-to-peak movement was about 9% of the muscle fibre length; three stimuli at 32ms intervals were given in each mechanical cycle. The frequency of movement and the timing of the stimulation were varied for each preparation to find the optimal conditions for power output and those optimal for efficiency (the ratio of net work output to total energy output as heat+work). To achieve either maximum power or maximum efficiency, the tetanus must start while the muscle fibres are being stretched, before the beginning of the shortening part of the mechanical cycle. The highest power output, averaged over one cycle, was 0.23±0.014 Wg−1 drymass (±S.E.M., N=9, 46.9±2.8mWg−1 wetmass) and was produced during movement at 3.5Hz. The highest efficiency, 0.41±0.02 (±S.E.M., N=13), occurred during movements at 2.0–2.5Hz. This value is higher than the efficiency previously measured during isovelocity shortening of these fibres. The implications of the high efficiency for crossbridge models of muscle contraction are discussed.