bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heart Rate, Respiratory Frequency and Wing Beat Frequency of Free Flying Barnacle Geese Branta Leucopsis
Authors: Butler P. J. , Woakes A. J. 
Published: April 2021

ABSTRACT
Two barnacle geese (Branta leucopsis) were successfully imprinted on a human and encouraged to fly behind an open-topped truck containing the foster parent. A two channel radio-transmitter was implanted into these geese so that heart rate and respiratory frequency could be recorded before, during and after flights of relatively long duration. The resting value for heart rate was 72 ±4 (10) beats min-1 and for respiratory frequency, 8.5±0.6(10) breaths min-1. Five flights of a mean duration of 14.4 ± 1.3 (5) min and at a mean air velocity of 18*7 ± 0.3 (54) m s-1 were performed. Both heart rate and respiratory frequency increased before the birds began to flap their wings for take off. Mean heart rate during flight was 512 ±4 (54) beats min-1 (7.24 x resting). At take off, wing beat frequency was 356 ± 7 (4) beats min-1 and respiratory frequency was 121 ± 10 (5) breaths min-1. Both of these variables then declined and reached average flight values of 287 ± 3 (37) beats min-1 and 99 ±2 (54) breaths min-1 (11.7X resting) respectively. There was no relationship between any of the measured variables and flight velocity. There was however, 3:1 correspondence between wing beat frequency and respiratory frequency and a tight phase locking between the two. The wings were fully elevated at 6.0 + 1.1(20)%, 40.5 + 1.1(20)% and 74.0+ 1.1(20)% of the respiratory cycle. On two occasions the birds slope soared on the air rising over the top of the cab for a mean duration of 52 s and at a mean air velocity of 14.2 ± 0.5 (4) m s-1. Heart rate was 261 ± 18 (4) beats min-1 and respiratory frequency was 68 ± 5 (4) breaths min-1. Upon landing, heart rate returned to its preflight value within 3 min. Respiratory frequency, however, increased as the birds began to pant and reached a maximum value of 255 ± 11 (5) breaths min-1 4 min after landing.
The Permeability of the Cuticular Lining of the Insect Alimentary Canal
Authors: Maddrell S. H. P. , Gardiner B. O. C. 
Published: April 2021

ABSTRACT
The permeability of the cuticle lining the foregut and hindgut of adults of Schistocerca gregaria, Gromphadorhina portentosa, and Leucophaea maderae, and larvae of Manduca sexta was investigated. In Schistocerca, Manduca, Leucophaea, and Gromphadorhina the cuticle lining the foregut has a very low permeability, while that lining the ileum (Schistocerca, Manduca, Leucophaea, and Gromphadorhina) and the rectum (Schistocerca and Manduca) is much more permeable. The low permeability of cuticle lining the crop in the insects examined is suited to the crop’ s function as a temporary store of ingested material. In Schistocerca gregaria, the cuticular lining of the ileum and rectum were found to be equally permeable. Each allows relatively rapid passage of small neutrally charged hydrophilic molecules. Both, however, showed a reduced permeability to anions and an enhanced permeability to cations. The cuticular lining of the hindgut would thus not be a barrier to the reabsorption of useful substances known to appear in the fluid reaching the hindgut from the Malpighian tubules, but it would, to some extent, retain in the lumen the relatively large anions actively excreted by the Malpighian tubules. The cuticle lining the colon of Schistocerca gregaria has a much lower permeability than has that lining the rest of the hindgut. This accords with the idea that the colon is thought not to be involved in absorption.
Plasma Melatonin Levels in the Scincid Lizard Trachydosaurus Rugosus : The Effects of Parietal eye and Lateral eye Impairment
Authors: Firth B. T. , Kennaway D. J. 
Published: April 2021

ABSTRACT
At a constant temperature of 24 °C there was a diel fluctuation in plasma melatonin concentration; highest levels occurring in the scotophase of a reversed daily light-cycle. Parietalectomy did not appear to affect melatonin titres under these conditions. When lizards were subjected to a photoperiod together with a thermoperiod (31 °C in the photophase, 24 °C in the scotophase), nocturnal plasma melatonin levels were almost twice as high as those in animals subjected to a photoperiod at constant temperature. Capping the lateral eyes of T. rugosus under these conditions did not alter the phase or amplitude of the rhythm in plasma melatonin content. However, removal of the parietal eye abolished the rhythm, owing mainly to reduced levels during the mid-scotophase and elevated levels during the midphotophase. It is concluded that plasma melatonin levels are regulated extraretinally, and that the parietal eye may help to mediate environmental input to centres secreting melatonin. It is suggested that the parietal eye may mediate thermal as well as photic information.
The Mechanics of Labriform Locomotion
Authors: Blake R. W. 
Published: April 2021

ABSTRACT
It is likely that the ‘undulatory propulsora’ employed by many fish are capable of producing a usefully directed thrust force over most of the tail-beat cycle. In contrast, fish which employ the ‘paddling pectoral fin propulsor’ only produce thrust during the power stroke phase of their fin-beat cycle, after which a recovery stroke occurs, when little usefully directed thrust force is produced. However, in order to gain a complete understanding of the mechanics of the paddling propulsor it is necessary to investigate the recovery stroke fully.
Head Movements in Flies (Calliphora) Produced by Deflexion of the Halteres
Authors: Sandeman David C. , Markl H. 
Published: April 2021

ABSTRACT
The heads of resting flies will twitch to the side if the haltere is deflected rapidly forwards. Head movements are always away from the stimulated haltere and do not occur if the haltere is deflected up, down or backwards. The anatomy and action of the neck muscles is described. Cobalt fills of the whole haltere nerve show that the sensory axons project to the neuropiles of the ipsi- and contralateral pro- and mesothoracic neuropiles, to the ipsilateral metathoracic neuropiles and to the cerebral ganglion. Cobalt fills of the nerves to the neck muscles and from the prosternal organs show that the central projections of these nerves end in the ipsilateral prothoracic neuropile. Recordings from the motoneurones to the neck muscles show that they are phasically activated by forward deflexion of the halteres after a latency of 2.5-3 ms. Spikes in the motoneurones follow the vibration of the haltere, one to one, up to 200 Hz. Recordings from the ipsilateral mesothoracic wing nerve (N. alae) show two large units which respond after a 2.5-3 ms latency to forward deflexion of the halteres. Behavioural observations of walking flies show that the presence or absence of halteres has a small but nevertheless significant effect on the animals’ ability to detect angular accelerations during walking or to orient with respect to gravity.
Exercise Training in Skeletal Muscle of Brook Trout (Salvelinus Fontinalis)
Authors: Johnston Ian A. , Moon Thomas W. 
Published: April 2021

ABSTRACT
The differentiation of myotomal muscles in the brook trout (Salvelinus fontinalis Mitchill) has been investigated using p-phenylene diamine stained semi-thin sections and cytochemical and quantitative determinations of enzyme activities. Evidence is presented that the range of fibre size in white muscle represents stages in growth rather than distinct fibre types. Electromyography shows that both red and white muscles are recruited for sustained swimming. The threshold swimming speed for recruitment of white fibres is around 1·8 body length/s (L/s). White muscle citrate synthetase and cytochrome oxidase activities are 25–35% that of red muscle. Hexokinase, phosphorylase and phosphofructokinase activities are 2, 4 and 2 times higher in white than red muscles. It is considered that the aerobic capacity of white muscle is sufficient to support sustained swimming, and that blood glucose could be an important fuel source. Endurance exercise training has been investigated in fish swimming, continuously, for 21 days at 3 L/s. This training regime restricts spontaneous high-speed swimming activity and resulted in a general decline of white muscle glycolytic enzyme activities. Red fibres underwent hypertrophy relative to non-exercised controls (530± 64μm2 non-exercised, 901 ± 63 μm2 trained). Aerobic enzyme activities in red muscle and the fraction of fibre volume occupied by mitochondria (30·2± 0·8%) did not change in response to the training programme, but glycolytic enzyme activities were elevated. 3-OH Acyl Co A dehydrogenase activities increased in both red and white muscles indicating an enhanced capacity for fatty acid catabolism with training. Plasma and muscle lactate levels were not statistically different between tank-rested and trained fish swimming at 3 L/s. Adaptations of fish muscle to endurance training are discussed and compared with results for other vertebrates.
The Statistical Analysis of Pontaneous Transmitter Release at Individual Junctions on Cockroach Muscle
Authors: Washio H. M. , Inouye S. T. 
Published: April 2021

ABSTRACT
Miniature excitatory post-synaptic potentials (MEPSPs) were recorded extra-and intracellularly from the coxal depressor muscle of the cockroach, Periplaneta americana. Statistical analysis of the time intervals between MEPSPs showed that the variance-to-mean curve for the extracellular data sets lay significantly above the line predicted for a Poisson process. A shuffling procedure, however, made the series almost random. The serial correlation coefficients for the extracellular data sets exceeded the confidence limits for various lags and most of them were positive. In comparison with the intensity function, the departure from the random process appeared to be mainly due to large positive correlation of intervals. It is concluded that in insect neuromuscular junctions, the spontaneous release of transmitter at individual sites is more clustered than that predicted by a Poisson process.
Water Balance and Urine Production in the Australian Arid-Zone Crab Holthuisana Transversa
Authors: Greenaway Peter 
Published: April 2021

ABSTRACT
The permeability to tritiated water (hourly exchange fraction = 0·164) and the rate of urine flow (0·47% body weight/day) are lower than recorded in other freshwater decapods. The calculated net osmotic water flux (2·71 % body weight/day) is 5 times the water output in the urine, indicating that there is extrarenal excretion of water. Water balance is maintained in the absence of urine production, again indicating an extrarenal excretory site. Water turnover is greater for crabs in burrows than for crabs kept in air of 98% R.H., indicating relatively favourable conditions of moisture availability at the base of the burrow.
Burst Reset and Frequency Control of the Neuronal Oscillators in the Cardiac Ganglion of the Crab, Portunus Sanguinolentus
Authors: Benson Jack A. 
Published: April 2021

ABSTRACT
The five large and four small neurones in the cardiac ganglion of the crab, Portunus, are electrotonically coupled and behave as a single relaxation oscillator, exhibiting periodic bursting activity in vitro. Recorded from the large neurone somata, this activity consists of 200–400 ms slow depolarizations called ‘driver potentials’ (Tazaki & Cooke, 1979a), accompanied by attenuated action potentials and EPSP’s from small neurone input. There is a strong positive correlation between the duration of the driver potential and the duration of the following interburst interval in the spontaneously active ganglion. This correlation is preserved during prolonged depolarization and hyperpolarization. When a driver potential is prematurely terminated by an injected current pulse, the following interburst interval is shortened in direct proportion to the decrease in driver potential duration. When a driver potential or a burst of high-frequency action potential activity is evoked by a depolarizing current pulse, the cardiac oscillator resets to the point of maximum hyperpolarization of the burst cycle, and the following interburst interval is of normal duration. Resetting following an evoked driver potential is complete. Partial resetting occurs only after short, evoked action potential bursts in the absence of a driver potential. Reset of the oscillator causes phase shifts in the subsequent cycles of activity, which vary with the phase of application and duration of the injected current pulse. Response curves have been constructed for a comprehensive range of durations and intensities of hyperpolarizing and depolarizing current pulses applied at all phases of the oscillator cycle. The phase shifts are composed of contributions from the duration of the current pulse, from the premature initiation of the slow depolarizing pacemaker potential due to early termination of the burst, and from the change in interburst interval correlated with truncation of the driver potential. Considering the cardiac ganglion as a relaxation oscillator, frequency control by entrainment to periodically applied current pulses was quantitatively predicted from the phase-response curves and experimentally confirmed. A high concentration (10−5 M) of octopamine can inhibit driver potential activity in the large neurones. This was used to examine possible frequency modulating effects of electrotonic feedback from the large neurone driver potentials onto the small neurone pacemaker activity. The observations are discussed in relation to the ionic model for driver potentials and slow pacemaker potential activity in the cardiac ganglion, as proposed by Tazaki & Cooke (1979a, b).
The Regulation of Sodium, Potassium and Chloride in an Aphid Subjected to Ionic Stress
Authors: Downing N. 
Published: April 2021

ABSTRACT
The aphid Myzus persicae has been cultured on the sea aster, Aster tripolium, which was grown in fresh water or sea water nutrient medium. Samples of sieve tube sap, obtained through the severed stylets of feeding aphids, haemolymph, and honeydew were analysed for sodium, potassium and chloride content. On fresh water plants the blood sodium level of the aphids was found to be exceptionally low. At 0·2 mmol 1−1 it is the lowest recorded sodium concentration in the blood of any animal. The result is discussed in relation to the functioning of the insect’s nervous system. Under the sea water condition all three ions are maintained in the blood at levels below those found in the imbibed or excreted fluid.
Small Motor Axons in Orthopteran Insects: A Reinvestigation of the Innervation of the Femoral Retractor Unguis Muscle in a Stick Insect and two Species of Locust
Authors: Walther Christian 
Published: April 2021

ABSTRACT
The motor innervation of the femoral retractor unguis muscle in a stick insect and two species of locust was investigated morphologically and electrophysiologically. In all three insects a somewhat variable number of axons with diameters less than 2 μm, some even less than 0·5 μm, accompany much larger ones in the motor nerve supplying the muscle. In the stick insect Carausius probably more than six motoneurones, including at least one inhibitory, control the muscle. In the two species of locust two populations of muscle fibres, ‘red’, and ‘white’, can be distinguished according to their respectively high and low levels of succinate dehydrogenase and their different patterns of innervation. The ‘red’ muscle fibres in Schistocerca have, in addition to one or two ‘fast’ excitors, two inhibitors, and in Locusta ‘red’ fibres receive a further one or sometimes two ‘slow’ excitors, giving a more complex innervation pattern of the ‘red’ compared to the ‘white’ fibres. An additional neurosecretory control by at least one neurone is indicated by the presence of characteristic nerve endings throughout the muscle. Of the two ‘fast’ motor axons in both locusts, one innervates the ‘red’ and the other the ‘white’ muscle fibres but both axons, to a lesser extent, also synapse with muscle fibres of the other type. The synaptic responses they evoke here are, however, only of small or intermediate amplitude. The existence of ‘slow’ excitatory innervation in Locusta ‘red’ fibres shows that functional synaptic contacts from one motoneurone can be restricted to a small region of a muscle fibre whilst those from other motoneurones are present along almost the entire length of the same fibre. Some of the difficulties in comparing morphologically demonstrated numbers of axon profiles with electrophysiologically derived numbers of motoneurones are discussed.
Direct Microprobe Evidence of Local Concentration Gradients and Recycling of Electrolytes During Fluid Absorption in the Rectal Papillae of Calliphora
Authors: Gupta Brij L. , Wall Betty J. , Oschman James L. , Hall T. A. 
Published: April 2021

ABSTRACT
The concentrations of sodium, potassium and chloride and dry mass were measured by electron-probe X-ray micro-analysis in 1 μm thick frozen-hydrated sections from Calliphora rectum in 5 different states of absorptive function. In all cases the average concentrations of sodium + potassium + chloride was consistently higher in the fluid in the lateral intercellular spaces than in the cytoplasm, the average ratio being 2:1 in water-fed flies and higher in water-deprived flies. The highest concentration of electrolytes was found in the extracellular channel of complex lateral membrane stacks, which is consistent with the histochemical localization of major cation pumps at these sites (Berridge & Gupta, 1968). This concentration exceeded the electrolyte concentration in other tissue compartments by some 80 m-equiv/1 H2O in water-fed flies and about 700 m-equiv/1 H2O in water-deprived flies. The potassium and sodium concentration ratio of this extracellular fluid was nearly 1:1 in water-fed flies, 3:1m water-deprived flies with KC1 in the rectal lumen, and 0·5:1 with NaCl in the rectal lumen. Results suggest that the extracellular fluid is generated in membrane infoldings along the intercellular channels, and that this fluid gains water and sodium, but loses a variable amount of potassium and chloride, as it passes to the haemolymph, thus supporting the idea of local osmosis and ion recycling.
Effects Of pH on Sodium Uptake in Norwegian Brown Trout (Salmo Trutta) from An Acid River
Authors: McWILLIAMS Philip G. 
Published: April 2021

ABSTRACT
Sodium uptake rates were measured in wild and hatchery reared Norwegian brown trout (Salmo trutta) exposed to media of a range of pH. Sodium uptake was strongly dependent on external acidity, being reduced in media of low pH. Wild fish from the naturally acid R. Tovdal (S. Norway) were more tolerant of acid media than hatchery reared fish. The effects of increasing external sodium concentrations were strongly influenced by low external pH. The results are discussed with respect to brown trout population decline in certain areas of S. Norway.
Acclimation To an Acid Medium in the Brown Trout Salmo Trutta
Authors: McWILLIAMS P. G. 
Published: April 2021

ABSTRACT
Data are presented which demonstrate acclimation of brown trout (Salmo trutta) to an acid medium. Sodium fluxes, transepithelial gill potentials and plasma electrolyte concentrations were measured in brown trout exposed to an acid medium of pH 6·0 for a period of 6 weeks.
Sodium loss rates in acid exposed fish are reduced compared to normal fish, and sodium uptake is insensitive to external pH following long-term acid exposure.
Changes in gill potential and sodium turnover rate following acid exposure can be accounted for by changes in the relative permeability of the gills to sodium and chloride. In neutral media the permeability ratio ϕNa+/ϕC1_ = 1·12 but this falls to 0·76 during acid exposure.
The ability to acclimate to acid conditions seems to depend largely on changes in gill permeability to sodium.
Ca-Induced K+-Outward Current in Paramecium Tetraurelia
Authors: Satow Youko , Kung Ching 
Published: April 2021

ABSTRACT
Late K-outward currents upon membrane depolarization were recorded in Paramecium tetraurelia under a voltage clamp. A Ca-induced K-outward component is demonstrated by subtracting the value of the outward current in a pawn A mutant lacking functional Ca-channels (pwA500). The Ca-induced K-outward current activates slowly, reaching a peak after 100 to 1000 ms. The current then remains steady or reaches the steady state after a decline of several seconds.
EGTA2− injection experiments show that the Ca-induced K-outward current is dependent on the internal Ca2+ concentration. The current is shown to depend on the voltage-dependent Ca conductance, by study of the leaky pawn A mutant (pwA132), which has a lowered Ca conductance as well as a lowered Ca-induced K-current. The Ca-induced GK is thus indirectly dependent on the voltage. The maximal GK is about 40 nmho/cell at + 7 mV in 4 mm-K+.
The Ca-induced K current is sustained throughout the prolonged depolarization and the prolonged ciliary reversal.
Calcium Metabolism in Bullfrog Tadpoles (Rana Catesbeiana)
Authors: Baldwin Geraldine F. , Bentley P. J. 
Published: April 2021

ABSTRACT
Non-feeding bullfrog (Rana catesbeiana) tadpoles can maintain their body Ca concentration in artificial pond waters containing a range of Ca concen-trations. The rate of uptake of 45Ca increases when the tadpoles are pre-adapted to a low-Ca pond water and declines when they are pre-adapted to high Ca. Measurement of drinking rate shows that drinking could account for only 5% of the influx. From in vitro experiments, it is estimated that about 70% of the influx occurs accoss the gills, and about 25% through the skin. Calcitonin decreases accumulation of 45Ca while 1,25-(OH)2 vitamin D3 increases it; parathyroid hormone was without effect. Efflux of 45Ca was unchanged by calcitonin or parathyroid hormone.
The Effects of Substance P and Baclofen on Motoneurones of Isolated Spinal Cord of the Newborn Rat
Authors: Otsuka Masanori , Yanagisawa Mitsuhiko 
Published: April 2021

ABSTRACT
The effects of substance P (SP) and baclofen were studied in the isolated spinal cord of newborn rats. Potential changes generated in motoneurones were recorded extracellularly from the ventral root (L3-L5). When SP (8×10− 5 M) was introduced into the bath, the depolarization of motoneurones began with a delay of 1·1 s. A large part of this delay can be explained as a time needed for SP to reach the site of action on spinal neurones.
When the preparation was perfused with artificial cerebrospinal fluid (CSF) containing low Ca (0·1 mm) and high Mg (1·6–3·5 mm), the spinal reflexes induced by dorsal root stimulation and recorded from the corresponding ventral root were completely abolished. The depolarizing action of SP (10−7 M) on the motoneurones was potentiated in the low-Ca medium, suggesting that SP acts directly on the motoneurones.
Baclofen at 10−6 M depressed the monosynaptic reflex by about 75%. The SP-induced depolarization of motoneurones was greatly depressed by baclofen in both normal and 0·1 mm-Ca mediums. The effects of baclofen (10−5 M) on the responses to various depolarizing agents were compared with that on the response to SP in artificial CSF containing 0–1 mm-Ca and 1·6–2 mm-Mg. The SP response was reduced by about 80%, whereas the responses to acetylcholine and glycine were not appreciably affected, and those to L-glutamate, GABA and noradrenaline were depressed by 10–22% by baclofen. These results suggest that baclofen blocks transmission at certain primary afferent synapses by antagonizing the action of SP that is released as a transmitter.