bluuebunny/crossref_metadata_2025_split huggingface dataset:
Secretion of Hypo-osmotic Fluid by the Lower Malpighian Tubules of Rhodnius Prolixus
Authors: Maddrell S. H. P. , Phillips J. E. 
Published: April 2021

SUMMARY
The ability of Rhodnius to excrete an hypo-osmotic fluid at high rates can be attributed to the activity of the lower lengths of the Malpighian tubules. In the presence of a stimulant (such as 10−8 M 5-HT) they can absorb KC1 from fluid in the lumen at rates as high as 0·5 /μ mol.min−1 cm−2. The solution absorbed is strongly hyperosmotic (900 mM KC1) so that the fluid in the lumen becomes hypo-osmotic (as low as 75 mOsm) and its flow is not much slowed. The rate of absorption of KC1 from the lumen depends on the potassium content of fluid there; the highest rates are achieved when K-rich fluid is run through the tubule at high speed from a cannula. Rubidium ions are partly effective substitutes for potassium ions in the system, but sodium ions are not absorbed at measurable rates. The wall of the lower tubule has a much lower permeability top-amino-hippuric acid, xylose, sucrose and inulin than has the upper tubule - as expected in a system able to maintain a large osmotic concentration difference.
Integumentary Amino Acid Transport and Metabolism in the Apodous Sea Cucumber, Chiridota Rigida
Authors: Ahearn Gregory A. , Townsley Sidney J. 
Published: April 2021

ABSTRACT
The apodous sea cucumber, Chiridota rigida, was found to transport exogenous amino acids to intracellular free amino acid pools in the integument, the gastrointestinal epithelium making only a minimal contribution to total animal uptake. Amino acids entering the integumentary free amino acid pool were either completely catabolized to CO2, incorporated into large molecular weight compounds, such as proteins, or left unchanged. The latter fraction was available for efflux through both apical and basal cellular membranes through saturable or non-saturable transport processes. Influx of natural (glycine) and analog (AIB) amino acids into the integumentary epithelium was achieved by a combination of saturable and non-saturable transport mechanisms: the former displaying Michaelis-Menten kinetics, being Na+-dependent, and transporting both glycine and AIB; the latter involving a simple diffusion of amino acid across the apical cell membranes and/or through the intercellular septate desmosomes. Preloaded AIB exhibited both homo-and hetero-exchange diffusion with exogenous amino acids when a relatively large internal analog pool had been established. With a small internal pool of AIB, homo-exchange diffusion persisted, but high external concentrations of glycine inhibited the washout of the analog. Transintegumentary influx of AIB to the coelomic fluid was a linear function of the exogenous amino acid concentration and was unchanged when choline chloride was used as a substitute saline. At steady-state the coelomic fluid analog concentration was maintained at a much lower level than the incubation medium or the epithelial free amino acid pool, due to apparent absorptive processes of the dermis and muscle layers of the integument, as well as by possible carrier-mediated re-uptake mechanisms on the basal membranes of the epithelial cells. A tentative model of integumentary amino acid transport and metabolism in C. rigida is presented.
Potassium-induced motion increase in a central nervous ganglion
Authors: Sattelle D. B. , Piddington R. W. 
Published: April 2021

ABSTRACT
By means of light-beating spectroscopy, a four-fold increase in the modulation of laser light scattered at right angles by a locust (Schistocerca gregaria, Forskâl) ganglion is detected when potassium ions replace sodium ions in the Ringer solution. This is interpreted as an increased level of motion of the scattering particles (size 0·3–3·0 μm, if viscosity is taken to be o-oi poises). The amplitude of the potassium-response is similar at all frequencies in the range 6·3-150 Hz and is reversible on return to normal (Na+) Ringer. Desheathing the ganglion reduces the half-time of the potassium-response by 3-4 times. By means of photon-correlation spectroscopy it was estimated that less than 10% of the tissue contributes to the motion detected. Cyanide (1-2 HIM) typically enhances the potassium-response and renders it irreversible, suggesting that the response is thermally rather than metabolically-driven. In addition, the dependence of both the correlation function and the power spectrum on the scattering angle is in the direction predicted for a diffusive process. Cobaltous ions (2-10 HIM), which block calcium entry into nerve cells, depress the potassium-response. It is proposed that potassium-depolarization and the resultant calcium entry into the cells causes a partial liquefaction of the cytoplasm which is detected as an increase in the level of Brownian motion. This mechanism could be used in vesicular release or in growth.
Hormonal control of integumentary water-loss: evidence for a novel neuroendocrine system in an insect (Periplaneta americana
Authors: Treherne J. E. , Willmer P. G. 
Published: April 2021

ABSTRACT
An accelerated water-loss was observed in decapitated individuals, no equivalent increase being obtained following severance of the nervous connectives in the neck. Injection of brain and, to a lesser extent, corpus cardia-cum extract resulted in a significant reduction in the rate of loss of water from decapitated individuals. The accelerated water-loss observed following decapitation appeared not to result from significant increase in excretory output or loss of water through the spiracles. It is suggested that integumentary transpiration may be affected by a blood-borne factor, or factors, which originate in the brain and corpus cardiacum.
Peripheral specialization for fine analysis of doppler-shifted echoes in the auditory system of the ‘CF-FM’ bat Pteronotus parnellii
Authors: Suga N. , Simmons J. A. , Jen P. H.-S. 
Published: April 2021

ABSTRACT
Pteronotus parnellii uses the second harmonic (61–62 kHz) of the CF component in its orientation sounds for Doppler-shift compensation. The bat’s inner ear is mechanically specialized for fine analysis of sounds at about 61-62 kHz. Because of this specialization, cochlear microphonics (CM) evoked by 61–62 kHz tone bursts exhibit prominent transients, slow increase and decrease in amplitude at the onset and cessation of these stimuli. CM-responses to 60–61 kHz tone bursts show a prominent inputoutput non-linearity and transients. Accordingly, a summated response of primary auditory neurones (N1) appears not only at the onset of the stimuli, but also at the cessation. N1-off is sharply tuned at 60–61 kHz, while N1-on is tuned at 63–64 kHz, which is 2 kHz higher than the best frequency of the auditory system because of the envelope-distortion originating from sharp mechanical tuning. Single peripheral neurones sensitive to 61–62 kHz sounds have an unusually sharp tuning curve and show phase-locked responses to beats of up to 3 kHz. Information about the frequencies of Doppler-shifted echoes is thus coded by a set of sharply tuned neurones and also discharges phase-locked to beats. Neurones with a best frequency between 55 and 64 kHz show not only tonic on-responses but also off-responses which are apparently related to the mechanical off-transient occuring in the inner ear and not to a rebound from neural inhibition.
Central control of feeding in the diapausing adult blowfly Phormia regina
Authors: Stoffolano J. G. 
Published: April 2021

ABSTRACT
The tarsal acceptance threshold of non-diapausing adult blowflies rises with age. Diapausing flies have a non-significantly elevated tarsal acceptance threshold, but drink significantly less sucrose solution than their non-diapausing counterparts. Removal of diapausing flies to non-diapause inducing conditions resulted in a lowering of the threshold. Failure to demonstrate a significant difference between the input signal from the peripheral receptors of non-diapausing and diapausing flies showed that the inhibition of feeding in diapausing flies was not due to peripheral inhibition but was controlled centrally.
Metabolism during flight in two species of bats, Phyllostomus hastatus and Pteropus gouldii
Authors: Thomas S. P. 
Published: April 2021

ABSTRACT
The energetic cost of flight in a wind-tunnel was measured at various combinations of speed and flight angle from two species of bats whose body masses differ by almost an order of magnitude. The highest mean metabolic rate per unit body mass measured from P. hastatus (mean body mass, 0·093 kg) was 130·4 W kg−1, and that for P. gouldii (mean body mass, 0·78 kg) was 69·6 W kg−1. These highest metabolic rates, recorded from flying bats, are essentially the same as those predicted for flying birds of the same body masses, but are from 2·5 to 3·0 times greater than the highest metabolic rates of which similar-size exercising terrestrial mammals appear capable. The lowest mean rate of energy utilization per unit body mass P. hastatus required to sustain level flight was 94·2 W kg−1 and that for P. gouldii was 53·4 W kg−1. These data from flying bats together with comparable data for flying birds all fall along a straight line when plotted on double logarithmic coordinates as a function of body mass. Such data show that even the lowest metabolic requirements of bats and birds during level flight are about twice the highest metabolic capabilities of similar-size terrestrial mammals. Flying bats share with flying birds the ability to move substantially greater distance per unit energy consumed than walking or running mammals. Calculations show that P. hastatus requires only one-sixth the energy to cover a given distance as does the same-size terrestrial mammal, while P. gouldii requires one-fourth the energy of the same-size terrestrial mammal. An empirically derived equation is presented which enables one to make estimates of the metabolic rates of bats and birds during level flight in nature from body mass data alone. Metabolic data obtained in this study are compared with predictions calculated from an avian flight theory.
The energetics of the jump of the locust Schistocerca gregaria
Authors: Bennet-Clark H. C. 
Published: April 2021

ABSTRACT
The anatomy of the metathoracic leg is redescribed with particular reference to storage of energy in cuticular elements and the way in which the stored energy is used in jumping.
The jump of adult male locusts requires an energy of 9 mJ and that of the female requires 11 mJ. The semilunar processes of each metafemur store 4 mJ at a stress of 15 N, and the extensor tibiae apodeme stores a further 3 mJ at the same stress. The total stored energy in both metathoracic legs is 14 mJ.
The extensor tibiae muscle produces a maximum isometric force of over 15 N at 30°C and, when loaded with the extensor apodeme and semilunar processes, attains this force in 0·3 sec with a strain of 0·8 mm. The peak power output is 36 mW or 0·45 W.g−1. The peak isometric force is attained when the tibia is fully flexed and the force falls as the tibia extends. The extensor tibiae muscle A band is 5·5 μm long and the peak force is over 0·75 N.m−2. The peak velocity of shortening is 7 mm.sec−1 or about 1·75 lengths/sec at 30°C.
The tensile strength of the extensor apodeme is 0·6 kN. mm−2 and Young’s modulus is 19 kN.mm−2. The safety factor does not exceed 1·2 and the safety factor of the semilunar processes and tibial cuticle is little higher.
The jump impulse lasts 25–30 msec. A velocity of 3·2 m.sec−1 is reached after a peak acceleration of 180 m.sec−2. The peak power output is 0·75 W at close to maximum velocity. Energy losses in rotating the femur and tibia are small and it is shown that the leg is able to extend at 7 times the normal rate with losses of about 20 %. Most of the stored energy is converted to kinetic energy as the animal jumps.
A model based on the relaxation of a spring that has the properties of the elastic elements of the locust leg into a lever with the same kinematics as the locust leg produces a force-distance curve similar to that measured for locust jumps. The major part of the jump energy is stored before the jump.
The effect of hypophysectomy and prolactin therapy on water balance of the brown trout Salmo trutta
Authors: Oduleye S. O. 
Published: April 2021

ABSTRACT
A technique for the hypophysectomy of the brown trout is described which might be applicable to other salmonids. Hypophysectomy produced a decrease in water turnover which was corrected by prolactin therapy.
Hypophysectomy resulted in a decrease in the net flux of osmotic water. Both osmotic and diffusional water permeabilities were evenly decreased after hypophysectomy, such that the ratio of the osmotic and diffusional permeability coefficients (Pos/Pd) retained a value of approximately unity.
The data suggest that calcium and prolactin have opposing actions on water balance and that their modes of action are likely to separate.
Acceleration Performance of Rainbow Trout Salmo Gairdneri and Green Sunfish Lepomis Cyanellus
Authors: Webb P. W. 
Published: April 2021

ABSTRACT
High unsteady (acceleration) performance of rainbow trout (L = 14.3 cm) and green sunfish (L = 8.0 cm) was studied in response to electric shock stimulus. Acceleration movements were divisible into a preparatory stage 1 and a main propulsive stage 2. Locomotory behaviour varied between faststarts and turning manoeuvres.
Taking the centre of mass for the stretched straight body as the reference point, distance covered with time was described by the equation;

The mean value of b was 1.60 for trout and 1.71 for sunfish. The overall mean distance covered and time to the end of stage 2 was 5.36 cm in 0.078 sec for trout and 2.85 cm in 0.079 sec for sunfish. Velocity increased curvilinearly with time. Maximum values of 20 L/sec were observed, but overall mean values at the end of stage 2 were 8.5 L/sec for trout and 8.3 L/sec for sunfish. Acceleration rate was not uniform but decreased with time. Mean maximum values were calculated of 42 m/s2 for trout and 16 m/s2 for sunfish, but overall mean values for an acceleration movement were 13 m/s2 and 8 m/s2 for the two species respectively.
The observed acceleration behaviour is more advantageous than uniform acceleration because a greater distance is covered and greater velocities acquired in a shorter time, while the increased energetic cost is only 2–3 % of the total energy expended.
Water flow dynamics in the respiratory tract of the carp (Cyprinus carpio L.)
Authors: Holeton G. F. , Jones D. R. 
Published: April 2021

ABSTRACT
Simultaneous measurements of water velocity in the buccal chamber, and buccal and opercular hydrostatic pressure of carp have revealed surprisingly high water velocities. The high flow velocities mean that, at times, the kinetic energy of flow makes a substantial contribution to the total fluid energy. This suggests that there may be unequal distribution of hydrostatic pressures within the buccal chamber. Anatomical examinations showed that fluid channels in the buccal chamber and gill raker sieve are complex and can be expected to vary spatially and temporally throughout the respiratory cycle. It appears that there is a potential for error in many of the previous analyses of ‘gill resistance’ and energetics of fish breathing based solely on hydrostatic pressure measurements and the simplifying assumption of steady-state conditions.
Reflex modulation of motoneurone activity in the cheliped of the crayfish Astacus leptodactylus
Authors: Vedel J. P. , Angaut-Petit D. , Clarac F. 
Published: April 2021

ABSTRACT
The reflex activity elicited by movement of the mero-carpopodite (M-C) joint in the cheliped of the crayfish Astacus leptodactylus is investigated and the role of the different proprioceptors (chordotonal and myochordotonal organs) separately studied. The reflex discharge involves mainly the tonic motoneurones of the extensor (E), the flexor (F) and the accessory flexor (AF) muscles. M-C joint posture is also regulated by the cuticular stress detector (CSD2) afferents: they increase mainly the F discharge and secondarily the AF command. The activity of the motor axons supplying the muscles of the meropodite can be also influenced by a variety of natural stimuli applied to other appendages. The effect usually produced is a general flexion reaction which is characterized by a reciprocity between E and F involving both central and peripheral mechanisms. The AF muscle is innervated by two antagonistic motoneurones, an excitatory neurone functionally linked in its discharge with one of the four excitors supplying F and an inhibitory motoneurone, common with E. The resulting competitive effect between these two neurones has been recorded intracellularly in AF muscle fibres. The role of the myochordotonal organ (MCO) in the crayfish is discussed. In particular the modulation of the AF command in relation to the discharges of the motor nerves to the main muscle E and F is studied.
Allometry of post-flight cooling rates in moths: a comparison with vertebrate homeotherms
Authors: Bartholomew G. A. , Epting R. J. 
Published: April 2021

ABSTRACT
The rates of post-flight cooling in 25 saturniid moths of 8 genera ranging in weight from 81 to 2650 mg were measured and compared with cooling rates in sphingids, birds and mammals. The initial and terminal cooling rates of the saturniids did not differ significantly. Large saturniids have relatively smaller thoraxes than small ones. In saturniids the rate of post-flight cooling is inversely related both to thoracic volume and total weight. Cooling rate is less dependent on thoracic volume in saturniids than in sphingids. Weight-specific conductance calculated on the basis of total weight, shows that moths are not as well insulated as birds or mammals. However, when considered on the basis of thoracic weight, the weight-specific conductance of saturniids and sphingids closely approximates that predicted by the regression of weight-specific conductance on total body weight in birds and mammals. Since the insulation of saturniids and sphingids is no more effective for animals of their size than is that of birds and mammals, their high body temperatures during activity appear to depend primarily on high levels of heat production.
Pursuit and prediction in the tracking of moving food by a teleost fish (Acanthaluteres spilomelanurus)
Authors: Lanchester B. S. , Mark R. F. 
Published: April 2021

ABSTRACT
The path, eye and body movements of a teleost fish (the leatherjacket Acanthaluteres spilomelanurus) approaching and taking food were measured by cinematography. Fixation of the food by movement of the eyes is an invariable feature of the approach. The eyes then remain aligned with the target while the body moves forward and round to bring the mouth to the food. When pursuing pieces of food moving vertically at constant velocity through the water these fish normally trace out the pathway that can be calculated by assuming the fish aims constantly at the food. Predictive pathways that imply anticipation of the point of intersection with the food are not regularly seen. Deviations from pursuit occur sporadically, usually in the direction of a predictive path, particularly when the fish approach falling food from below. The geometry of the situation suggests that predictive paths may sometimes be generated if the alignment of eye and body during the pursuit of moving food can be delayed. In approaches from below this may be because forward movement of the fish would tend to stabilize the image of the falling food in the retina. We suggest that a simple linked control system using both eye and body movements to fixate retinal images will on occasions generate predictive pathways without any need for the central nervous system to calculate them in advance.
Blood oxygen transport and metabolism of the confined lugworm Arenicola marina (L.)
Authors: Toulmond A. 
Published: April 2021

ABSTRACT
Oxygen consumption , haemoglobin oxygen saturation level and pH in prebranchial blood were measured in lugworms experimentally confined in sea water at 15 ·C. Total blood flow through the gills was estimated. For seawater oxygen partial pressure between 120 and 150 Torr, , and were high and nearly constant. For &lt; 120 Torr, fell quickly, progressively dropped, and metabolism remained aerobic at the expense of the prebranchial blood oxygen store. For &lt; Torr, and values were extremely low, and the low and the modified buffer power of the surrounding sea water showed that anaerobic metabolism was occurring. Changes in respiratory gas exchanges and metabolism during the tidal cycle are deduced from the comparison of these results with data obtained in the field.
Respiration in relation to ion uptake in the crayfish Austropotamobius pallipes (Lereboullet)
Authors: Sutcliffe D. W. , Carrick T. R. 
Published: April 2021

ABSTRACT
O2 uptake was determined for periods of 23–46 h in salt-depleted crayfish held in deionized water (DW) or Na-free media at 10°C. These media were replaced by artificial lakewater media (ALW) containing 0·20–6 mM Na and O2 uptake was again determined for periods of 24–66 h. During net ion uptake in ALW the metabolic rate was either elevated or depressed. Standard metabolism in ALW altered by amounts equivalent to 0·1–15·5% (mean 6·4 (15)14·4% s.D.) of the metabolic rate measured during salt-depletion. On three occasions the metabolic rate was elevated by 22·0–66·7%, but some of this increase may have been due to locomotor activity. The calculated values for thermodynamic work involved in ion transport were 0·056–0·268 J/10 g.h at 10°C, or 1·5–7·2% of the mean standard metabolic rate. Most of the observed changes in metabolic rate lie within the limits of experimental error (ca. ± 7 %). Hence the energetic cost of ion transport is too small for direct measurement in intact crayfish.
Co-ordinating interneurones of the locust which convey two patterns of motor commands: their connexions with flight motoneurones
Authors: Burrows M. 
Published: April 2021

ABSTRACT
Some flight motoneurones receive two superimposed rhythms of depolarizing synaptic potentials when the locust is not flying; a slow rhythm which is invariably linked to the expiratory phase of ventilation, and a fast rhythm with a period of about 50 ms which is similar to the wingbeat period in flight. By recording simultaneously from groups of motoneurones, the synaptic potentials which underly these rhythms have been revealed in 30 flight motoneurones in the three thoracic ganglia. The inputs occur in elevator motoneurones and some depressors but are of lower amplitude in the latter. The inputs have not been found in leg motoneurones. The rhythmic depolarizations are usually subthreshold but sum with sensory inputs to evoke spikes in flight motoneurones at intervals equal to or multiples of the wingbeat period in flight. Both rhythms originate in the metathoracic ganglion and are mediated by the same interneurones. They can be adequately explained by supposing that there are two symmetrical interneurones which each make widespread connexions with left and right flight motoneurones in the three ganglia. The slow rhythm is coded in the overall burst of interneurone spikes during expiration and the fast rhythm in the interval between the spikes of a burst.