bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flight of Auks (Alcidae) and Other Northern Seabirds Compared with Southern Procellarhformes: Ornithodolite Observations
Authors: Pennycuick C. J. 
Published: April 2021

ABSTRACT
Airspeeds in flapping and flap-gliding flight were measured at Foula, Shetland for three species of auks (Alcidae), three gulls (Landae), two skuas (Stercorariidae), the fulmar (Procellariidae), the gannet (Sulidae) and the shag (Phalacrocoracidae). The airspeed distributions were consistent with calculated speeds for minimum power and maximum range, except that observed speeds in the shag were unexpectedly low in relation to the calculated speeds. This is attributed to scale effects that cause the shag to have insufficient muscle power to fly much faster than its minimum power speed. The wing adaptations seen in different species are considered as deviations from a ‘procellariiform standard’, which produce separate effects on flapping and gliding speeds. Procellariiformes and the gannet flap-glide in cruising flight, but birds that swim with their wings do not, because their gliding speeds are too high in relation to their flapping speeds. Other species in the sample also do not flap-glide, but the reason is that their gliding speeds are too low in relation to their flapping speeds.
The effects of forced activity on circulating catecholamines and pH and water content of erythrocytes in the toad
Authors: Tufts B. L. , Mense D. C. , Randall D. J. 
Published: April 2021

ABSTRACT
In vivo experiments were carried out to determine the effect of forced activity on circulating catecholamine levels, haematocrit, and the pH and water content of erythrocytes in the toad, Bufo marinus. In addition, the effect of the beta-adrenergic agonist isoproterenol on erythrocte pH and water content was examined in vitro.
Forced activity caused a significant decrease in both whole blood and erythrocyte pH, while haematocrit and circulating adrenaline and noradrenaline levels increased. Erythrocyte water content did not change following forced activity. Addition of isoproterenol to toad blood in vitro had no effect on either erythrocyte pH or water content. The apparent absence of beta-adrenergic effects on erythrocyte pH and water content in the toad is in sharp contrast to the response of teleost fish erythrocytes to beta-adrenergic stimulation. The significance of these differences is discussed.
Evidence that myoglobin does not support heart performance at maximal levels of oxygen demand
Authors: Canty AA , Driedzic WR 
Published: April 2021

ABSTRACT
Myoglobin binds reversibly with oxygen and can facilitate oxygen diffusion across artificial membranes in vitro (Wittenberg, 1970). Myoglobin-enhanced oxygen consumption in heart is particularly important under conditions of hypoxia. This has been established directly with fish heart models (Bailey & Driedzic, 1986; Driedzic, Stewart & Scott, 1982) and indirectly by following discharge of high-energy phosphates in rat heart (Taylor, Matthews & Radda, 1986). Simple mathematical models are consistent with the importance of myoglobin during hypoxia and, in addition, predict that the protein should play a role in the support of oxygen consumption at maximal rates of respiration (Meyer, Sweeney & Kushmerick, 1984). In this study, the hypothesis that myoglobin-enhanced oxygen consumption is vital in meeting the demands of elevated levels of respiration by a teleost heart is tested indirectly. Myoglobin’s importance was assessed by monitoring isometric force development of ventricle strips from sculpin bathed in media with a constant level of either 21 % or 1 % O2. Additions to the bathing media included 2,4-dinitrophenol (DNP) to uncouple mitochondria and induce maximal oxygen consumption, and hydroxylamine which effectively converts myoglobin into the iron III form incapable of binding oxygen (Driedzic, 1983; Wittenberg, Wittenberg & Caldwell, 1975). The major finding is that myoglobin does not play a critical role in the maintenance of performance under normoxia at maximal rates of oxygen consumption.
Energy Partitioning in Fish: The Activityrelated Cost of Osmoregulation in a Euryhaline Cichlid
Authors: Febry Ricardo , Lutz Peter 
Published: April 2021

ABSTRACT
We have investigated how the maintenance, net cost of swimming and total (maintenance + net cost of swimming) metabolic rates of red, hybrid tilapia (Oreochromis mossambicus ♀ × O. homorum ♂) responded to different acclimation salinities, and if these responses correlated with changes in ion-osmoregulation (= osmoregulation) costs.
Three groups of fish were acclimated to either fresh water (FW, 0‰), isosmotic sea water (ISW, 12‰) or full strength sea water (SW, 35 ‰) and oxygen consumption was measured while they swam at 10, 20, 30 and 40cms−1. Maintenance oxygen consumption (estimated by extrapolation), for an average fish (63g), increased among groups in the following order: FW &lt; ISW &lt; SW. The net cost of swimming increased in the order ISW &lt; SW &lt; FW, and total oxygen consumption (maintenance + net cost of swimming) increased in the order ISW &lt; FW &lt; SW.
We assumed that the contribution of cardiac, branchial and swimming muscles to the net cost of swimming was proportional to swimming speed only, and therefore, at similar speeds, differences in the net cost of swimming among salinities were due to changes in the activity-related cost of osmoregulation. Consequently, the order in which the net cost of swimming increases from one group to another is the same as the order in which the cost of osmoregulation increases. Since the sequences for maintenance and total metabolic rates differed from that for the net cost of swimming, salinity-related increases in these rates cannot be attributed exclusively to changes in osmoregulation cost.
We conclude, based on the differences in the net cost of swimming, that osmoregulation in FW is more expensive than in SW, and that it is cheapest in ISW. Although we were not able to estimate the total cost of osmoregulation in FW and SW, we estimated the activity-related cost, relative to the cost in ISW, at different swimming speeds (net cost of swimming in FW or SW minus net cost of swimming in ISW at each speed). For a 63-g fish in FW, this cost increased from zero at rest, to 41 mgO2kg−1 h−1 (16% of the total metabolic rate, 24% of the net cost swimming) at 40 cm s−1. In SW the same cost increased only to 32 mg O2 kg−1 h−1 ( 12 % of the total metabolic rate, 20% of the net cost of swimming) at 40cms−1. The net cost of swimming in FW or SW increased with swimming speed at a rate 3-4 times faster than the rate of increase in osmoregulation costs, suggesting that the latter did not limit the delivery of oxygen to the swimming, and other supporting, muscles.
Coronary flow in a perfused rainbow trout heart
Authors: Farrell A. P. 
Published: April 2021

ABSTRACT
A preparation was developed to perfuse the coronary circulation in working hearts from rainbow trout (Salmo gairdneri Richardson). The preparation was used to examine pressure–flow relationships for the coronary circulation as the heart generated physiological and subphysiological work loads. Coronary vascular resistance increased exponentially as coronary flow rate decreased. Coronary resistance was also influenced by cardiac metabolism and acclimation temperature. When heart rate was increased, extravascular compression increased in coronary resistance. Direct vasoconstriction of the coronary vessels, produced by injections of adrenaline into the coronary circulation, was temperature-dependent.
Apical Membrane Permeability of Mytilus Gill: Influence of Ultrastructure, Salinity and Competitive Inhibitors on Amino Acid Fluxes
Authors: Wright Stephen H. , Secomb Timothy W. , Bradley Timothy J. 
Published: April 2021

ABSTRACT
The apical membrane of gill integumental cells from the mussels Mytilus edulis and M. californianus serves as a permeability barrier separating sea water from a cytoplasm rich in amino acids and other small organic molecules. Morphometric analysis of transmission electronmicrographs indicates that the membrane area of these cells is increased between 10-and 18-fold by the presence of a microvillous brush border. The microvilli do not appear to influence the kinetics of solute transport across the cell apex, as determined using a mathematical model of the relationship between membrane structure and the kinetics of transport. Rates of amino acid loss from the integument were low, and estimates of the upper limit of the passive permeability of the apical membrane to amino acids ranged from 0·5 to 10 × 10−10 cm s−1. Abrupt exposure of intact mussels or isolated gill tissue to 60 % sea water (19%o salinity) resulted in a transient, 40-to 80-fold increase in the rate of loss of all amino acids from integumental tissues. Upon exposure to full-strength sea water, efflux rates returned to near control values. Exposure to 60 % sea water also inhibited the carrier-mediated accumulation of amino acid: uptake of 0·5 μmol l−1 [l4C]alanine and [14C]taurine was reduced by 80% compared to control uptake in 100% sea water. This inhibition was not adequate to account for the increase in net efflux of taurine from gill tissue into 60% artificial sea water (ASW), though the inhibition of alanine uptake may have contributed significantly to the increased loss of this amino acid. Efflux of discrete structural classes of amino acid occurred when integumental tissues were exposed to 50 μmol l−1 concentrations of structurally related analogues. It is concluded that the apical membrane of gill cells has a very low passive permeability to amino acids, and that the overall permeability of the gill can be increased in a reversible fashion by exposure to reduced salinity or to high external concentrations of amino acid.
Phenyliminoimidazolidine Derivatives Activate Both Octopamine1 and Octopamine2 Receptor Subtypes in Locust Skeletal Muscle
Authors: Evans Peter D. 
Published: April 2021

ABSTRACT
The actions of the phenyliminoimidazolidine derivatives, NC7 and NC5 on octopamine receptors in the extensor-tibiae neuromuscular preparation of the locust are described. The derivatives activate both OCTOPAMINE1 and OCTOPAMINE2 receptors in this preparation. They are not selective agonists of OCTOPAMINE2 receptors that activate adenylate cyclase. The relative potencies of NC5 and NC7 on OCTOPAMINE1 and OCTOP-AMINE2 receptors differ, suggesting that they may be useful in the development of selective agonists that can distinguish between the different pharmacological subclasses of octopamine receptor. The octopamine-mediated increases in cyclic AMP levels in this preparation can be separated into high-and low-affinity components. NC5 and NC7 appear to activate the high-affinity component of this response selectively.
Effects of Wing Campaniform Sensilla Lesions on Stridulation in Crickets
Authors: Schäffner Karl-Heinz , Koch Uwe T. 
Published: April 2021

ABSTRACT
The degradations in the cricket’s calling song after lesions of the cubital campaniform sensilla (CCS) are investigated using extracellular recording and angular movement recording techniques. In the intact male, nerve potentials from the CCS during the closing stroke are demonstrated. In the lesioned male, syllable shortenings and missing syllables can be traced to abnormalities in the wing motion: irregular stops (‘sticking’), anomalously high closing speeds with sound emission (‘overspeed’), or high closing speeds without sound emission (‘slipping’) are observed. Despite these defects, the activation pattern of the main opener and closer muscles remains completely unaffected. The defects are interpreted as disturbance of a regulatory system normally maintaining proper engaging forces of the wings.
Do cardiorespiratory frequencies show entrainment with hopping in the tammar wallaby?
Authors: Baudinette R. V. , Gannon B. J. , Runciman W. B. , Wells S. , Love J. B. 
Published: April 2021

ABSTRACT
Breathing, heart and gait frequencies, tidal volume, cardiac output, and rates of oxygen consumption were measured in tammar wallabies (Macropus eugenii Desmarest) hopping on a treadmill. At speeds greater than 1·6 ms−1 the rate of metabolic power consumption was independent of hopping speeds. Blood lactate levels within the speed range where was independent of speed showed a mean increase of 4·8 mmol l−1. During bipedal hopping, the frequencies of breathing and limb movement are phase-locked in the ratio of 1:1. Inspiration begins as the animal leaves the ground and may be a passive process driven by a visceral piston. A relatively large central tendon in the diaphragm may correlate this function. Unlike breathing frequencies, cardiac frequencies show no entrainment with hopping. The site of dissipation of the presumed large arterial pressure excursion is unknown.
Single nephron function of the lesser spotted dogfish, Scyliorhinus canicula, and the effects of adrenaline
Authors: Brown J. A. , Green C. 
Published: April 2021

ABSTRACT
Function of the kidney and the nephron in the lesser spotted dogfish, Scyliorhinus canicula, was investigated by clearance, renal tubular micropuncture and ferrocyanide infusion techniques. 70% of the glomerular filtrate was reabsorbed within the renal tubule, producing slightly hypotonic urine. Glomeruli were: perfused and filtering (F); arterially perfused but not filtering (NF); or non-arterially perfused and hence not filtering (NP). Adrenaline reduced the proportion of filtering glomeruli from 94% to 70%. Despite this reduction, a marked overall glomerular diuresis occurred. Single nephron glomerular filtration rates (SNGFRs) ranged from 1·5 to 26 nl min−1 with a mean rate of 9·5 nl min−1 during control periods. Adrenaline elevated SNGFR to a mean value of 22·9 nl min−1 (range 2·4–64·6 nl min−1). Tubular fluid/plasma inulin concentration ratios (TF/Pin) indicated reabsorption of around 74% of the glomerular filtrate by the proximal segments. Comparison of TF/P and urine/plasma inulin concentrations (U/Pin) strongly suggests tubular secretion of water beyond the point of puncture. Adrenaline infusion appears to increase both proximal water reabsorption and distal tubular secretion.
The Physiology of Compensation by Locusts for Changes in Dietary Protein
Authors: Abisgold J. D. , Simpson S. J. 
Published: April 2021

ABSTRACT
Previous work has demonstrated that fifth-instar nymphs of Locusta migratoria L. respond to differences in levels of dietary protein by altering intermeal interval but not meal size (Simpson & Abisgold, 1985): insects fed a diet with 14% protein (p) eat the same sized meals more frequently than those fed a diet with 28% protein (P). The physiological basis for this compensatory response is investigated. Insects fed the P-diet had a significantly larger increase in blood osmolality during and after a meal than did those fed the p-diet. Unexpectedly, this difference in blood osmolality did not result in a variation in the rate at which the fore-, mid- and hindgut emptied. Therefore a change in the rate of decline in negative feedback from gut stretch receptors does not underlie the alteration in interfeed interval. 40 % of the difference in blood osmolality between p- and P-fed insects was attributable to changes in the blood concentration of free amino acids. Of the 16 free amino acids found, 11 occurred in significantly higher concentrations in the blood of P-fed insects. There was no significant difference in the polypeptide and protein content of the blood of insects fed the p- or P-diet. Increasing either blood osmolality or free amino acid concentration by injection delayed the next meal:injections that increased both had the greatest effect. A mechanism is discussed whereby both blood osmolality and the concentration of various free amino acids regulate the time between meals, and thus compensatory feeding in response to changes in dietary protein.
Calcium Conductance in An Identified Cholinergic Synaptic Terminal in the Central Nervous System of the Cockroach
Authors: Blagburn Jonathan M. , Sattelle David B. 
Published: April 2021

ABSTRACT
Intracellular microelectrodes were used to study a cholinergic synapse between two identified neurones: the lateral filiform hair sensory neurone (LFHSN) and giant interneurone 3 (GI 3) in the terminal ganglion of the first-instar cockroach Periplaneta americana. The presynaptic cell, LFHSN, was impaled in a region of the axon which forms large numbers of output synapses.
The sign and magnitude of the LFHSN spike afterpotential were shown to depend on [Ca2+]o. l μmol l−1 tetrodotoxin (TTX) abolished LFHSN spikes but the addition of 0·l mmol l−1 4-aminopyridine (4-AP) enabled regenerative depolarizations to be evoked which were followed by large EPSPs in GI3. Addition of 20 mmol l−1 tetraethylammonium ions (TEA+) abolished the cholinergic EPSPs but resulted in long-duration LFHSN spikes. Intracellular injection of caesium ions (Cs+) into LFHSN enabled long-duration spikes to be evoked and had no effect on synaptic transmission. Long-duration LFHSN spikes were (1) increased in amplitude by increased [Caz+]o; (2) accompanied by an increase in conductance; (3) not abolished by replacement of external Na+ with Tris+ or choline+; (4) blocked by 1 mmol l−1 Cd2+ and 10 mmol l−1 Co2+; (5) not supported by substitution of Mg2+ for Ca2+; and (6) supported by Ba2+ substitution. They are thus considered to be Ca2+ spikes. The Ca2+ spikes were blocked by organic Ca2+ channel blockers at 0·5–1 mmol l−1.
The putative Ca2+ spike was followed by a hyperpolarizing afterpotential (HAP), the duration of which was proportional to the amplitude and duration of the Ca2+ spike. The HAP was (1) accompanied by a conductance increase; (2) reversed at potentials 30mV more negative than resting potential; (3) not supported by substituting Ba2+ for Ca2+; and (4) partially blocked by 150 mmol l−1 TEA+. The HAP is considered to result from an increase in Ca2+-dependent K+ conductance.
It is concluded that, in addition to Na+ channels and delayed rectifying K+ channels, Ca2+ channels and Ca2+-dependent K+ channels are present in the axonal membrane of LFHSN, in a region which forms many output synapses.
How does a Fly Cling to The Under Surface of A Glass Sheet?
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
The climbing of flies on glass is a problem that still lacks an agreed solution. West (1862), who introduced the term ‘tenent hairs’ for the trumpet-like structures on the pulvilli, regarded these as suckers which ensured adhesion by atmospheric pressure. But it is generally agreed that they are too small for that. Dahl (1885), studying adhesive organs in insects in general, favoured adhesion by ‘Capillarattraction’ but he considered that other forms of cohesion and adhesion were operating as well. Rombouts (1884) opted for surface tension. In the most recent paper, Walker, Yule & Ratcliffe (1985) give a new description of the adhesive organs in the blowfly Calliphora, and conclude from calculations that surface tension of the lipid secretion under the tenent hairs provides an adequate adhesive force.
The pad of setae at the lower extremity of the tibia of the first two pairs of legs, which is present in the adult of the blood-sucking bug Rhodnius and is used in climbing on a smooth surface (Gillett, 1932), has a totally different structure from that of the adhesive organ of the fly. In making a combined investigation (Gillett & Wigglesworth, 1932) we believed at first that surface tension in the lipid secretion between the oblique endings of the hairs and the surface would prove to be the adhesive force. But after experiments on insects and models, helped by discussions with N. K. Adam, we decided that direct intermolecular attraction, generated when the lipid film breaks down during sliding (i.e. seizure or partial seizure), was probably the more important force.
The tibial organ is present only on the first two pairs of legs of the adult Rhodnius, but these large (2 cm) insects can climb a steeply sloping sheet of glass. When the glass is vertical they slip down very slowly. In the experiments of Edwards & Tarkanian (1970), some Rhodnius adults held on to glass at angles greater than vertical, up to a mean of 109°. Beyond that they fell off. These are characteristic properties of the frictional forces dependent on molecular attraction, which do not resist separation by forces acting in the axis normal to the surface unless the areas in contact are molecularly smooth (Bowden, 1957). Edwards & Tarkanian (1970), in repeating the experiments on Rhodnius, accepted our interpretation – with the proviso that meniscus (surface tension) forces will, of course, be operating at the same time.
Modulated vibration-sensitivity of lamprey Mauthner neurones
Authors: Currie S. N. , Carlsen R. C. 
Published: April 2021

ABSTRACT
The vibration-sensitivity of larval lamprey Mauthner (Mth) neurones is dependent on behavioural state. Animals are maximally vibration-sensitive when at rest and less so when active or aroused. To demonstrate this effect in freely behaving larvae, we provided repeated vibratory or electrical stimuli to the vestibular labyrinths while animals made transitions between rest and activity. Stimuli which were adequate to elicit Mth spikes 100% of the time in a resting animal (recorded extracellularly from the spinal cord) were consistently subthreshold while the animal was swimming. The same effect was seen in semi-intact preparations, both moving and curarized, while recording intracellularly from Mth cell bodies. Mth vibrationsensitivity decreased abruptly with the onset of ‘arousal’, defined here by the presence of tonic, descending spinal cord discharge. During arousal, the Mth soma exhibited a slight depolarization (2–8 mV), an increased membrane conductance, and a strong depression of vibration-evoked excitatory postsynaptic potential (EPSP) amplitude. This Mth PSP depression (MPD) appears to underlie altered vibration-sensitivity.
The Behaviour of Dendrocoelum Lacteum
Authors: Ullyott Philip 
Published: April 2021

ABSTRACT
Dendrocoelum lacteum can orientate itself to a lateral stimulation intensity of less than 7 ergs/cm.2/sec. when not stimulated by other light sources. This orientation is produced equally well by “diffuse” or by point sources of light. The threshold value of lateral stimulation, to which orientation is possible, is a function of the total stimulation to which the animal is subjected. Graber (1884) and workers after him found that if planarian worms were put into a Petri dish one-half of which had been darkened with black paper, they congregated in the darker half. This was described as a phobotactic or non-orientated response. It has been shown that if a random movement brings an animal into the darker half of the dish, it immediately moves in an orientated fashion away from the lighter half, on account of its extreme sensitivity to lateral illumination. In reality tropotaxis and not phobotaxis is responsible for the behaviour observed. A reinvestigation of photophobotaxis is necessary.
The Behaviour of Dendrocoelum Lacteum
Authors: Ullyott Philip 
Published: April 2021

ABSTRACT
Stimulation by non-directional light produces in the animal an increase in random movements, that is to say an increase in the rate of change of direction (r.c.d.). This r.c.d. can be expressed as a function of the stimulating intensity. In total darkness there is a basal r.c.d. In constant stimulation the r.c.d. decreases as the animal becomes adapted. The “shock reaction” is not an essential part of the mechanism of phobotactic behaviour. Photophobotaxis occurs without it. The r.c.d. phenomena and the adaptation associated with them are sufficient to explain the mechanism of photophobotaxis. Alternate adaptation and stimulation occur when the animal is moving down or up a non-directional gradient, as a result of its random movements. This alternate stimulation and adaptation has an effect on the r.c.d. of such a kind that the animal is led automatically to the place of minimal intensity.