bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alteration of the Respiratory System at the Onset of Locust Flight: I. Abdominal Pumping
Authors: Ramirez J. M. , Pearson K. G. 
Published: April 2021

ABSTRACT
The respiratory behaviour of Locusta migratoria is altered at the onset of flight. The neuronal processes and some of the mechanisms underlying these alterations were studied by using intracellular recording and staining techniques.
It has previously been reported that abdominal pumping ceases for the first seconds of flight. Our data indicate that this phenomenon is not due to inhibition of the respiratory system, since most interneurones and some motoneurones maintain a respiratory rhythm during the onset of flight activity. Likely explanations for the cessation of the abdominal pumping are: (1) increased stiffness of the abdomen due to maintained activation of abdominal muscles and (2) decreased rhythmic modulation in abdominal motor units due to tonic excitatory input.
Two major changes occur in the respiratory system at the onset of flight: (1) the rhythm is reset by an activation of inspiratory and inactivation of expiratory neurones, and (2) the respiratory rate is increased. The increase in the respiratory rate at the onset of flight is in part due to an activation of inspiratory interneurones which are capable of accelerating the respiratory rhythm.
The changes in the respiratory system coinciding with the initiation of flight suggest a feedforward mechanism linking both behaviours. Tonic interneurones, involved in the initiation of flight and influencing respiration, might be involved in linking respiration and flight. At flight onset, one group of these simultaneously disinhibited respiration and flight and thus contributed both to an increase in the respiratory rate and to an activation of the flight system. Another group evoked flight and had variable effects on respiration. One tonic interneurone had a depressing effect on the respiratory rate.
We conclude that respiration is centrally linked to flight in part by the same interneurones controlling the initiation of flight. The existence of such a feedforward mechanism in the locust resembles the situation found in vertebrates, where locomotory and respiratory behaviour can be driven from the same brainstem region.
Photoinactivation of A Portion of A Neurone For Long-Term Studies of Its Role In Behaviour
Authors: Libersat Frederic , Selverston Allen , Camhi Jeffrey M. , Goldstein Ronald S. 
Published: April 2021

ABSTRACT
An important method in the study of the neural basis of behaviour is the removal from a nerve circuit of a single cell in vivo and the subsequent search for changes in behaviour (Atkins et al. 1984; Comer, 1985). In such studies it can also be useful to remove only a part of a cell, such as a segment of its dendritic tree or axon. This can be done by filling the cell with the fluorescent dye Lucifer Yellow (LY) and irradiating the particular segment to be removed (Jacobs & Miller, 1985). However, for behavioural testing, it is often necessary to wait 1 day for the animal to recover from surgery. It is not yet clear in any system whether a small part of cell inactivated in this way repairs itself or remains inactive after 1 day. In this paper we examine this question of the permanence of LY photoinactivation (Miller & Selverston, 1979), and carry out behavioural tests showing the usefulness of this method.
A Critical Analysis of the Use of High-Speed Film to Determine Maximum Accelerations of Fish
Authors: Harper David G. , Blake Robert W. 
Published: April 2021

ABSTRACT
High-speed cinematography is often employed in studies on fish swimming, particularly where performance is estimated (e.g. Wardle, 1975; Eaton et al. 1977; Webb, 1978b; Dorn et al. 1979; Videler, 1981). One commonly reported aspect of performance is the acceleration of fish during fast-starts (bursts of swimming from a standing start; e.g. Weihs, 1973; Webb, 1975, 1976, 1977, 1978a,b, 1982, 1983, 1986; Rand & Lauder, 1981). The present study is a critical examination of the use of cinematography to estimate the maximum acceleration of fish during fast-starts.
Inertial and Aerodynamic Torques on the Wings of Diptera in Flight
Authors: Ennos A. Roland 
Published: April 2021

ABSTRACT
The magnitude and distribution of the torques caused by inertial and aerodynamic forces on the wings of Diptera in flight are calculated. The bending torque at stroke reversal due to the inertia of the virtual mass of air bound to the wing is only slightly less than the torque due to the inertia of the wing mass itself. The maximum inertial torque due to both wing mass and virtual mass is usually slightly greater than the maximum aerodynamic torque encountered by the wings. Bending torques decrease rapidly away from the wing base. Pitching torques are much smaller than bending torques at the wing base, but do not decrease much until near the tip. The pattern of loading affects the wing design. Wings are thicker nearer the base to resist bending, but thin and light near the tip to minimize inertial energy expenditure. Their open, corrugated structure resists bending, while allowing them to be twisted as a result of the weak pitching moments.
Primary Culture of Identified Neurones From a Cnidarians
Authors: Przysiezniak Jan , Spencer Andrew N. 
Published: April 2021

ABSTRACT
Several types of neurones were dissociated from the nerve-rings of the hydrozoan jellyfish Polyorchis penicillatus, using collagenase digestion preceded, and if necessary followed, by removal of external divalent cations. The neurones were cultured for up to 2 weeks in artificial sea water, on a mesogloeal substratum.
One subset of large neurones, the swimming motor neurones (SMNs; soma approx. 20×50 μm), exhibited distinct morphological features in vitro, such as large size, wide processes, clear cytoplasm and membranous inclusions around the nucleus. These neurones retained their characteristic action potential shape in culture, with spikes measuring 50 ±11 mV (N=18) in peak amplitude and 37 ± 11 ms in duration. SMNs could be labelled in vivo with carboxyfluorescein or Lucifer Yellow, subsequently dissociated, and identified in vitro.
Two subsets of small neurones were also identifiable. One exhibited electrophysiological similarities with B system neurones, known to be presynaptic to the SMNs in vivo, showing a burstlike pattern of spikes of short duration (5·4 ± 1·4 ms; N=6) and small amplitude (25 ±7mV). Another subset of small neurones could be labelled with antiserum against the carboxy-terminal peptide moiety, Arg-Phe-amide.
Biophysical and neurotransmitter studies at the level of the single identified hydrozoan neurone will be easier in isolated cell culture. This approach will avoid problems encountered in studying the semidissected nerve-ring preparation.
Microelectrode Evidence for the Electrical Isolation of Goblet Cell Cavities in Manduca Sexta Middle Midgut
Authors: Dow Julian A. T. , Peacock Jillian M. 
Published: April 2021

ABSTRACT
The middle midgut of Manduca sexta is known to transport K+ actively from the basal to the apical side, and is thought to be involved in the generation of an extremely high pH in the midgut lumen.
An experimental configuration is described which allows visually guided microelectrode impalements to be made of any compartment in the midgut tissue, with simultaneous verification by fluorescent dye ionophoresis in the live tissue. In this way, many impalements can be performed and verified on a single gut.
The potential differences between impalement sites and the apical compartment were plotted against transepithelial potential difference (TEP) for three sites: goblet cell cytoplasm, columnar cell cytoplasm and goblet cell cavities. In all three cases, the potentials recorded varied significantly and linearly with gross TEP.
Goblet and columnar cell cytoplasm impalements resembled each other both in size and direction of potential, being always negative relative to the lumen. This implied electrical coupling was confirmed by the observation that the two cell types were linked by gap junctions.
Goblet cavity impalements were characterized by a positive potential relative to the lumen. The goblet cavities were isolated from the lumen by a high resistance, and no leakage of Lucifer Yellow or 6-carboxyfluorescein markers through the apical valve was detected.
Using sensible estimates for midgut intracellular pH and in vivo TEP, it was shown that the potential difference across the goblet cavity apical membrane in vivo would agree closely with the Nernst potential for protons across the membrane, in agreement with a model for generation of high pH.
Metabolic–Membrane Coupling in Red Blood Cells of Trout: The Effects of Anoxia and Adrenergic Stimulation
Authors: Ferguson R. A. , Boutilier R. G. 
Published: April 2021

ABSTRACT
Under oxygenated conditions, in vitro, the highly aerobic red cells of the rainbow trout (Salmo gairdneri) exhibit tight coupling between energy (i.e. nucleotide triphosphate, NTP)-consuming and NTP-producing metabolic activity, as shown by strict maintenance of red cell NTP: haemoglobin ratios. This coupling is maintained following adrenergic stimulation of oxygenated red cells when the increased NTP demands of ion transporting systems are met by enhanced energy production via aerobic metabolism. In unstimulated anoxic red cells, membrane–metabolic coupling is preserved via the arrest of NTP-consuming processes. Adrenergic stimulation of anoxic red cells, however, leads to a functional uncoupling of membrane metabolism with the result that NTP levels decline rapidly. At this time, cellular [NTP] is negatively correlated with [Na+]i and [Cl−]i and positively correlated with [K+]i. This, in addition to the fact that the pH of the intracellular compartment is also highly dependent on cellular NTP levels, provides evidence for the integration of energy and membrane metabolisms.
Electromyography of the Fin Musculature of the Cuttlefish Sepia Officinalis
Authors: Kier William M. , Smith Kathleen K. , Miyan Jaleel A. 
Published: April 2021

ABSTRACT
The musculature of the fins of the cuttlefish Sepia officinalis (Mollusca, Cephalopoda) was studied with electromyography to test predictions of the functional role of the various muscle masses. Previous research had shown the fins to consist of a tightly packed, three-dimensional array of muscle with distinct zones of anaerobic glycolytic and oxidative muscle fibres. In addition, a network of crossed oblique connective tissue fibres was observed within the musculature. In a previous paper a model of the function of the muscle and connective tissue was presented. In the present paper, we present recordings of electrical activity from the various muscle bundles in the fin, in conjunction with the output from an electronic movement-monitoring device, and correlate muscle activity with both the phase and the intensity of the fin-beat cycle. The results obtained here support the hypothesis that the oxidative muscle fibres produce gentle fin movements and are consistent with the hypothesis that the network of crossed oblique connective tissue fibres provides skeletal support. The results also support predictions that the anaerobic glycolytic muscle fibres both produce vigorous fin movements and provide support for that movement. This study provides a critical test of models of the role of the tightly packed, three-dimensional array of muscle found in muscular hydrostats such as the arms and tentacles of cephalopods and tongues of mammals and lizards.
Endothermy and Temperature Regulation in Bees: A Critique of ‘Grab and Stab’ Measurement of Body Temperature
Authors: Stone G. N. , Willmer P. G. 
Published: April 2021

ABSTRACT
‘Grab and stab’ methods have become standard in the measurement of insect body temperatures. The gradient of the best-fit regression of body temperature on ambient temperature is often used as a measure of the thermoregulatory ability of a species. The temperatures recorded are commonly accepted as slight underestimates of actual values prior to capture due to passive cooling between capture and insertion of the thermocouple. Here we present laboratory experiments involving tethered flight which show that bees often warm up on cessation of flight, and that errors due to warm-up over the time interval typically associated with ‘grab and stab’ sampling may be significant. More importantly, the errors due to warm-up in two species are shown to change with ambient temperature, thus affecting the form of the relationship between ambient and body temperatures. We compare laboratory and field data to illustrate the way in which warm-up errors may exaggerate apparent thermoregulatory ability, and we urge greater caution in the interpretation of ‘grab and stab’ data.
Parachlorophenylalanine Retards Tail Regeneration in the Gekkonid Lizard Hemidactylus Flaviviridis Exposed to Continuous Light
Authors: Ramachandran A. V. , Ndukuba Patrick I. 
Published: April 2021

ABSTRACT
Parachlorophenylalanine (p-CPA) was used for chemical pinealectomy in a study of tail regeneration in the gekkonid lizard, Hemidactylus flaviviridis. Two doses of p-CPA (200 or 400 μg kg−1body mass) were injected into two groups of lizards (5 days prior to and 30 days after caudal autotomy) exposed to continuous light of 2500lx intensity during the summer season (March-May). Our observations show that the initiation of regeneration, the daily growth rate, the total length of new growth (regenerate) produced, and the total percentage replacement of the lost (autotomized) tails 30 days after autotomy were all significantly less with 400 μg kg−1 and insignificantly less with 200 μg kg−1 of p-CPA than in the control group of animals. The results may indicate that the effect of the drug p-CPA, an agent employed for chemical pinealectomy, on tail regeneration in H. flaviviridis is dose-dependent and that p-CPA at the high dose of 400 μg kg−1 has a similar retardation effect to that of complete pineal ablation. The role of the pineal in photoperiodic photoreception, and the effect of p-CPA on serotonin melatonin biosynthesis and the consequent effects on tail regeneration, are discussed.
Size Limits in Escape Locomotion of Carridean Shrimp
Authors: Daniel Thomas L. , Meyhöfer Edgar 
Published: April 2021

ABSTRACT
Escape locomotion of the common dock shrimp, Pandalus danae Stimpson, is the result of a rapid flexion of the abdomen that lasts approximately 30 ms. The hydrodynamic forces that result from this motion lead to body accelerations in excess of 100 ms−2 and body rotations of about 75°. We examined the mechanics and kinematics of this mode of locomotion with both experimental and theoretical approaches. Using a system of differential equations that rely on conservation of both linear and angular momenta, we develop predictions for body movements, thrust forces and muscle stresses associated with escape locomotion. The predicted movements of the body agree to within 10 % with data from high-speed ciné-photography for body translations and rotations. The thrust from rapid tail flexion is dominated by accelerational forces and by the force required to squeeze fluid out of the gap created by the cephalothorax and the abdomen at the end of tail flexion. This squeeze force overwhelms any propulsive drag forces that arise from the tail-flip.
Using the theoretical analysis, we identify two additional features about unsteady, rotational aquatic locomotion. First, as either the relative length of the propulsive appendage increases or the absolute body size increases, rotational motions become disproportionately greater than translational motions, and escape performance decays. Second, if muscle stresses developed during escape cannot exceed the maximum isometric stress, there is a unique body length (6 cm) that maximizes the distance travelled during the escape event.
Functional Wing Morphology and Aerodynamics of Panorpa Germanica (Insecta: Mecoptera)
Authors: Ennos A. Roland , Wootton Robin J. 
Published: April 2021

ABSTRACT
The functional wing morphology of the wings of the scorpion fly Panorpa germanica L. was investigated using a combination of light microscopy, high-speed cinematography, wing manipulation and mechanical testing.
In rising forward flight the wings are flapped 40° out of phase along a shallow stroke plane, the forewings leading. Aerodynamic analysis suggests that unsteady effects are important in flight.
During the downstroke, both wings are straight and cambered, the chord being parallel to the body axis, which is angled 45° upwards from horizontal. Both wings are supinated at lower stroke reversal, the hindwing to a much greater extent, and flex ventrally halfway along their length for the first half of the upstroke. Flexion is parallel to the chord in the hindwing, but is oblique in the forewing, so distal forewing areas are supinated relative to proximal areas.
The behaviour of the wings is related to their structure. Spars at the leading and trailing edges of both wings support the wing during the downstroke, and flexion during the upstroke is facilitated by buckling of the weak ventral thyridium region. The oblique flexion seen in the forewing is due to its relatively longer leading edge spar.
The differences between the wings are, in turn, related to their pitch control mechanisms. The forewing has a well-developed clavus, like that of the forewing of a locust, and pitch is altered by relative movement of this and the leading edge, but only within a narrow range. Oblique flexion is necessary to invert the aerofoil. The weaker and less well-developed clavus of the hindwing, more similar to that of the Diptera, allows a greater degree of supination, effected largely by wing inertia. No oblique flexion is necessary.
Post-Moult Calcification in the Blue Crab, Callinectes Sapidus: Timing and Mechanism
Authors: Cameron James N. 
Published: April 2021

ABSTRACT
A series of experiments was conducted to elucidate the events immediately preceding and following moulting (ecdysis) in the blue crab, Callinectes sapidus Rathbun. The crabs gain weight (mostly water) to a level more than twice the premoult value excluding the shed carapace. The gain begins about 4 h before ecdysis, accelerates rapidly to a maximum rate at about the time of ecdysis, and is essentially complete by 2h after ecdysis. Both calcification and net H+ excretion remain at control (intermoult) levels until 1–2 h post-moult, whereupon a very rapid increase in both begins, with the same time course for both processes. The ratio of internal to external calcium concentration drops from 1·4:1 during intermoult to 0·85:1 by 2 days after the moult, reversing the electrochemical gradient during the post-moult period. Calcification is strongly inhibited by the protein synthesis inhibitors actinomycin D and cycloheximide. Isolated whole gills and gill slices do not show significant changes in rates of calcium uptake related to moult stage, indicating that the uptake of calcium across the gills may be largely passive. A low-affinity Ca2+-activated ATPase is present in both gills and epithelium, but only the epithelial activity shows a substantial (fivefold) increase in the hours after ecdysis. The control mechanisms for stimulation of the transport processes remain elusive. Eyestalkless crabs progress normally through moult and post-moult calcification. Peptide profiles from blood and from suspected neurohormone-producing tissues differ markedly with moult stage, but several different approaches to developing a bioassay using peptides from crab tissues and vertebrate sources have been unsuccessful. The physiological events in the hours surrounding ecdysis suggest a complex and precisely timed series of control signals.
Maintenance of Oxygen Consumption in Resting Silurus Glanis at Different Levels of Ambient Oxygenation
Authors: Forgue Jean , Burtin Bernard , Massabuau Jean-Charles 
Published: April 2021

ABSTRACT
The mechanisms of adaptation that allow the teleost Silurus glanis to maintain its resting oxygen consumption constant when the O2 partial pressure in the inspired water varied between 40 and 3 kPa were studied at 13 °C. Steady state values of oxygen consumption, ventilatory and circulatory flow rates, in the inspired and expired water, and O2 concentration in the arterial and venous blood, haematocrit and acid-base status in the arterial blood were determined after 1-day exposures at selected values. Whole-blood O2-binding characteristics were also determined.
The key adaptation after 1 day of acclimation was maintenance of oxygen consumption by ventilatory adjustment with no change in blood flow rate or pH (no Bohr effect). At each value (i) the ventilatory adjustment was minimal as the O2 extraction coefficient from water always remained around 80 –90 % and (ii) stayed constant at about 2 kPa. Data are compared with previous results in crayfish and other teleosts. It is concluded that the principle of a constant O2 status in the milieu intérieur - independent of large changes in for a given state of activity - should be valid in many crustaceans and teleosts.
Involvement of A Circadian Rhythm in the Photoperiodic Ovarian Response of the Yellow-Throated Sparrow, Gymnorhis Xanthocollis
Authors: Dixit Anand S. , Tewary P. D. 
Published: April 2021

ABSTRACT
Groups of the photosensitive female yellow-throated sparrow were placed under various light-dark cycles, in which a fixed ultrashort photophase of 3 h was combined with dark phases of varying duration, resulting in cycles of 18–30 h. Simultaneously, two groups of birds, one in short days (8L/16D) and the other in long days (15L/9D), were kept as controls. Significant ovarian growth, observed at 30 and 60 days, was induced by 3h ultrashort photophase only if it was introduced in the cycles of 18h (3L/15D), 20h (3L/17D), 26h (3L/23D), 28h (3L/25D) and 30 h (3L/27D) as well as under long days (15L/9D), whereas there was no response to the ultrashort photophase in cycles of 22 h (3L/19D) and 24 h (3L/21D) and in short days (8L/16D). It seems that there is an ovarian response to the ultrashort day cycles when a phase advance or delay of photosensitivity of the response system repeatedly produces coincidence of the external photophase (3h) with the photosensitive phase of an endogenous circadian rhythm. The results are thus consistent with the Bünning hypothesis, which suggests the involvement of an endogenous circadian rhythm in photoperiodic time measurement.