bluuebunny/crossref_metadata_2025_split huggingface dataset:
Na and Cl Transport across the Isolated Anterior Intestine of the Plaice Pleuronectes Platessa
Authors: Ramos M. M. P. , Ellory J. C. 
Published: April 2021

ABSTRACT
The tissue was found to have a serosa negative potential, and shortcircuit currents equivalent to the net Cl transport. A significant part of the Cl uptake was Na dependent and a similar fraction of the Na uptake was Cl dependent. Short-circuit current and uptake of both ions were inhibited by loop diuretics and analogues. 4. Isc and p.d. were abolished by ouabain. The observations are consistent with the idea of a coupled NaCl entry into the cell, using the energy inherent in the Na gradient; Na being pumped out of the cells by the Na pump and followed electrically by Cl−. Net chloride transport and the serosa negative potential would be a consequence of the permselective properties of the junctions allowing Na but not Cl to recycle back to the mucosal solution.
An Aerodynamic Analysis of Bird Wings as Fixed Aerofoils
Authors: Withers Philip C. 
Published: April 2021

ABSTRACT
The aerodynamic properties of bird wings were examined at Reynolds numbers of 1·5 × 104 and were correlated with morphological parameters such as apsect ratio, camber, nose radius and position of maximum thickness. The many qualitative differences between the aerodynamic properties of bird, insect and aeroplane wings are attributable mainly to their differing Reynolds numbers. Bird wings, which operate at lower Reynolds numbers than aerofoils, have high minimum drag coefficients (0·03–0·13), low maximum lift coefficients (0·8–1·2) and low maximum lift/drag ratios (3–17). Bird and insect wings have low aerofoil efficiency factors (0·2–0·8) compared to conventional aerofoils (0·9–0·95) because of their low Reynolds numbers and high profile drag, rather than because of a reduced mechanical efficiency of animal wings.
For bird wings there is clearly a trade-off between lift and drag performance. Bird wings with low drag generally had low maximum lift coefficients whereas wings with high maximum lift coefficients had high drag coefficients. The pattern of air flow over bird wings, as indicated by pressure-distribution data, is consistent with aerodynamic theory for aeroplane wings at low Reynolds numbers, and with the observed lift and drag coefficients.
Instantaneous Measurements of Oxygen Consumption During Pre-Flight Warm-Up and Post-Flight Cooling in Sphingid and Saturniid Moths
Authors: Bartholomew George A. , Vleck David , Vleck Carol M. 
Published: April 2021

ABSTRACT
A method for instantaneous measurement of oxygen consumption in an open flow respirometry system is described. During pre-flight warm-up in both sphingids and saturniids, oxygen consumption reaches levels 20 to 70 times resting values. , required to maintain the thorax at flight temperature by intermittent wing-quivering and fluttering is about one-third the maximum , during warm-up. The Q10 of resting , averages 2 ·4 in both sphingids and saturniids. At any given thoracic temperature, during post flight-cooling exceeds , at rest.
Factorial scope (maximum resting ) during warm-up is independent of mass and thoracic temperature. In sphingids it averages 39, in satuniids, 43. Absolute metabolic scope in both groups increases with thoracic temperature and is roughly proportional to . In saturniids about 49 % of the heat produced during warm-up is stored in the thorax; in sphingids the figure is about The data on metabolic scope, power requirements for flight, Q10 and body mass are used to develop equations that predict thoracic temperature during flight for both sphingids and saturniids.
Changes in Membrane Properties of the Drosophila Dorsal Longitudinal Flight Muscle Induced by Sodium Pump Inhibitors
Authors: Henon Barbara K. , Ikeda Kazuo 
Published: April 2021

ABSTRACT
Drosophila dorsal longitudinal flight muscle fibres made anoxic by passing nitrogen through the tracheal system or treated with 10−5m ouabain or strophanthidin show a reversible fall in resting membrane potential of 16·5 mV (s.e. 0·96), 13·7 mV (s.e. 0·87), and 17·0 mV (s.e. 2·8), respectively. The reversible depolarization obtained with these sodium pump blockers occurred within 10–15 min. The depolarization of the muscle fibres was accompanied by a decrease in input resistance of 21·2% (s.e. 3·8) in anoxia, 21·4% in ouabain, and 25·6% (s.e. 6·7) in strophanthidin. The resistance decrease in strophanthidin and ouabain was transient and returned to above the resting level while the muscle fibres were still exposed to these agents. Recovery of membrane potential in cells exposed to anoxia is biphasic. An initial ‘fast’ phase of recovery occurs within 15 s upon return to air followed by a late ‘slow’ phase lasting several minutes. Recovery of input resistance in cells exposed to N2 coincided with the ‘fast’ phase of the recovery of resting membrane potential. Recovery of membrane potential following exposure to strophanthidin is a long, slow process which occurs at conductance values at the resting level or below. The tendency towards spontaneous action potentials was increased by anoxia and the action potentials occurring in anoxia were elongated into plateau potentials of about 18 s duration. These results are consistent with the hypothesis that anoxia and cardioactive steroids inhibit a metabolic process, possibly an electrogenic ion pump, that is essential for maintenance of the resting membrane potential in Drosophila flight muscle. Exposure to these agents also results in changes in input resistance. Both of these effects could contribute to the depolarization and affect the excitable properties of the muscle fibre membrane.
Studies on Water in Barnacle Muscle Fibres I. The Dry Weight Components of Fresh Fibres
Authors: Clark M. E. , Hinke J. A. M. 
Published: April 2021

ABSTRACT
The dry weight components comprise 25 % of the total weight of fresh muscle fibres of the giant barnacle Balanus nubilis. Half of the solids are water insoluble; 6 % of this material is fat, and the rest is mostly myofilament protein. Less than 3 % of the dry weight consists of inorganic ions, and these account for only a quarter of the osmotic activity in the fibre water. Seventy per cent of the osmotic activity is due to nitrogenous solutes which comprise 18% of the dry weight. Glycine predominates, followed by TMAO + betaine, proline, glutamine + asparagine, arginine, and taurine. About 13% of the dry weight is soluble protein and not more than 10 % is an unidentified soluble substance of high molecular weight. Thus, Balanus conforms with other marine invertebrates in the high content of osmotically active nitrogenous solutes in its myoplasm.
The Exoskeleton and Insect Proprioception. I. Responses of Tibial Campaniform Sensilla to External and Muscle-Generated Forces in the American Cockroach, Periplaneta Americana
Authors: Zill Sasha N. , Moran David T. 
Published: April 2021

ABSTRACT
The tibial campaniform sensilla are a group of mechanoreceptors in the cockroach leg that respond to cuticular strain. Each sensillum consists of a single bipolar neurone whose dendrite inserts into an ovoid cuticular cap embedded in the exoskeleton. The tibial campaniform sensilla are consistently separable into two subgroups with mutually perpendicular cap orientation: the long axis of the caps of proximal subgroups are oriented perpendicular to the tibial long axis; caps of the distal subgroup are parallel to the tibia. The responses of individual, identified sensilla from both subgroups were tested to the following forces: bending forces (perpendicular to the leg long axis), axial forces (parallel to the leg axis), torques (twisting about the leg long axis) and forces generated by the tibial muscles. The tibial campaniform sensilla respond vigorously to bending forces imposed in the plane of movement of the adjacent femorotibial joint. Individual sensilla exhibit orientation-dependent directional sensitivity in their response: the proximal sensilla respond only to dorsal bending; the distal sensilla respond only to ventral bending. Sensilla respond less vigorously to bending forces in other planes. Responses are weak but directionally sensitive to axial forces: the proximal sensilla fire upon axial compression; the distal sensilla fire upon axial tension. Both subgroups respond simultaneously but weakly to imposed torques. Contractions of the tibial muscles produce strong orientationdependent responses: the proximal sensilla respond only to flexor muscle contractions; the distal sensilla respond only to extensor muscle contractions. These responses are accurately predicted from a simple model in which the tibia behaves as a cylinder under stress. The tibial campaniform sensilla respond as directionally sensitive strain gauges. Each individual sensillum responds only to compressions perpendicular to the long axis of its cuticular cap. Tibial campaniform sensilla respond best to those forces that the animal can most effectively control.
Effects of Afference Sign Reversal on Motor Activity in Walking Stick Insects (Carausius Morosus)
Authors: Graham D. , Bässler U. 
Published: April 2021

ABSTRACT
The apodeme of the femoral chordotonal organ of a middle leg can be moved from its normal position close to the extensor tendon and inserted into a clot cut in the flexor tendon. This inverts the output of the sense organ and produces a ‘wrong’ afference.
During walking on a pair of light wheels the operated leg either makes walking steps or is raised and extended in a ‘salute’ posture. The coordination is similar to that for an intact animal if the operated leg walks but changes to the middle leg amputee timing when the operated leg ‘salutes’.
The transitions between saluting and the normal walking behaviour of the operated leg can be explained if it is assumed that the animal depends heavily upon the C.O. for determining the tibia position during both walking and the saluting behaviour.
Motor output to the levators and depressors of the femur and the protractors and retractors of the coxa shows bursting activity during the salute at the frequency of 3–4 Hz. The depressor bursts are also modulated at a frequency of ∼ 1 Hz and produce strong regular depressions of the femur which are co-ordinated with the movements of the other legs.
The maintenance of regular depressor contractions during the salute shows that an important part of the motor output to the saluting leg (depressor activity) arises from an internal oscillation or rhythmic command which maintains its co-ordinated activity when the normal peripheral sensory input to the leg it is attempting to operate is absent. Retractor activity wanes during the salute suggesting that propulsion is much more dependent upon peripheral input than is the support musculature (depressors),
The creation of a ‘wrong’ afference can be used to map the importance of the operated organ in different sub-units of behaviour.
Synchronous and Asynchronous Muscles in Cicadas*
Authors: Josephson Robert K. , Young David 
Published: April 2021

ABSTRACT
The tymbal muscles of the cicada Cyclochila australasiae Donovan are synchronous, those of Platypleura capitata (Oliv.) asynchronous. The tymbal structure and the individual sound pulses are similar in the two species. The sound pulse frequency during calling song is higher in P. capitata (389 Hz) than in C. australasiae (234 Hz). Muscle action potentials during protest songs are simultaneous in the two tymbal muscles of P. capitata, alternating in C. australasiae. Each action potential, or direct electrical stimulus to the muscle, is followed by a single, sometimes bimodal, sound pulse in C. australasiae, and by a burst of sound pulses in P. capitata. The isometric twitch duration (30 °C) is much longer in P. capitata (107 ms) than in C. australasiae (18 ms) and the tetanic fusion frequency correspondingly lower. Myofibrils are slightly wider and sarcoplasmic reticulum much sparser in tymbal muscles of P. capitata than in those of C. australasiae;, otherwise the muscles are structurally similar. Flight muscles in both species are synchronous with an action potential for each contraction. Tymbal muscles of the two species are used to illustrate the diagnostic features of synchronous and asynchronous muscles.
Cardiovascular Changes in the Lingcod (Ophiodon Elongatus) Following Adrenergic and Cholinergic Drug Infusions
Authors: Farrell A. P. 
Published: April 2021

ABSTRACT
Adrenergic and cholinergic agonists were infused into the ventral aorta to evoke gill vasoactivity in the lingcod, Ophiodon elongatus. Arterial blood pressures were changed, and cardiac output and stroke volume were increased. As a consequence both the pressure and flow profiles across the gill were altered, and these changes should alter the pattern of lamellar perfusion. The changes in cardiac function were apparently reflexly mediated.
A 24-Hour Cycle in Single Locust and Mantis Photoreceptors
Authors: Horridge G. A. , Duniec J. , Marčelja L. 
Published: April 2021

ABSTRACT
When fixed during the night the rhabdom of the locust and mantis is much broader than when fixed during the day. Dark-adapted ommatidia of the locust and mantis by day and night have a zone of vacuoles around the rhabdom tip, but when light-adapted this zone is replaced by cytoplasm rich in mitochondria. Illumination of the rhabdom in the night state causes the microvilli to swell and the rhabdom to break down over the course of about 1 h. A diurnal rhythm is apparent in the spontaneous breakdown of the rhabdom in the morning even though the eye has seen no light for 12 h. Intensity/response curves (peak of the response in mV plotted against log intensity of stimulus) show an increase in sensitivity during the night even though the stimulus is a point source on axis. On the other hand, counts of bumps (quantal responses to individual photons) show no change in photon capture efficiency at night when the stimulus is a point source. Strong illumination of the eye in the night state causes a desensitization which continues for 1 h. Measurements of the acceptance angle in the dark-adapted day and night states show that field size is an indicator of the diameter of the rhabdom tip, but actual fields are larger than those calculated from the anatomical dimensions.
Na+Fluxes Across Isolated Perfused Gills of the Chinese Crab Eriocheir Sinensis
Authors: Pequeux A. , Gilles R. 
Published: April 2021

ABSTRACT
Sodium transport processes in the branchial epithelium of euryhaline crustaceans have been investigated using a perfused preparation of gills isolated from Chinese crabs Eriocheir sinensis acclimated to dilute (FW) and to concentrated (SW) media.
The results clearly establish the existence of a functional difference between the different pairs of branchiae with respect to their participation in the regulation of the blood Na+ content.
In FW-acclimated animals, the Na+ active uptake which counterbalances the salt loss along the concentration gradient is mostly achieved across the three posterior pairs of gills. Conversely, the Na+ fluxes measured in the three anterior pairs are essentially passive and carrier-mediated.
Further characterization of the Na+ uptake system present in the posterior gills by means of inhibitors like ouabain and ethacrynic acid indicates the existence of at least two spatially separated components of the Na+ carrying system.
It is shown that NH4+ may be used as co-ion for Na+ but that such a coupling can only account for a very small part of the Na+ actively transported inward. The existence of an electrogenic mechanism or of another coupled system has thus to be postulated but remains at present a matter of speculation.
To study FW-to-SW and SW-to-FW acclimation, Na+ fluxes were measured in isolated gills of SW-acclimated crabs and of FW crabs perfused and incubated in SW conditions.
During acclimation to SW the Na+ active uptake in the posterior gills is abolished primarily as a result of inhibition of the Na+carrier activity.
Coordinated Walking of Stick Insects on a Mercury Surface
Authors: Graham D. , Cruse H. 
Published: April 2021

ABSTRACT
Adult stick insects walk on a mercury surface at step frequencies in the range 1–4 Hz with a coordination similar to that found in free-walking adults at their maximum step frequency of 3 Hz. The amplitude of leg movement covers the same range as that found in free-walking animals. The use of a mercury substrate effectively removes mechanical interactions between the legs, showing that such influences cannot be the cause of the coordinated behaviour observed in this experimental situation. The dependence of the maximum step frequency upon the resistance to retraction provided by the substrate suggests that feedback from the periphery determines the step period. The variation in the anterior extreme position of a leg is less than that of the posterior extreme position, indicating that the latter may be more strongly influenced by coordinating interactions between the legs.
The Effect of Load on Locomotion in Crayfish
Authors: Grote J. R. 
Published: April 2021

ABSTRACT
Leg movements and leg muscle activity were monitored in unrestrained crayfish walking freely under several different load conditions. A variety of changes in the character of locomotion was found to vary with load including: (1) the timing and frequency of the step cycle and in particular the power stroke duration; (2) significant leg-positional changes which result in increased mechanical advantage under load; and (3) the (load-induced) recruitment of the depressor muscle. In restrained, immobile animals, isometric loading of depression resulted in inhibition of motor activity in the depressor-remotor nerve, an effect similar to the vertebrate tendon reflex.
Ferromagnetic crystals (magnetite?) in human tissue
Authors: Kirschvink JL 
Published: April 2021

ABSTRACT
In recent years, a variety of animals have been found which are able to synthesize the ferromagnetic mineral magnetite (Fe3O4). Lowenstam (1962) originally recognized biogenic magnetite in the radular teeth of a primitive marine mollusc, the chiton (Polyplacophora), and since then it has been identified as a precipitate in several magnetically sensitive organisms, including honey bees (Gould, Kirschvink & Deffeyes, 1978), homing pigeons (Walcott, Gould & Kirschvink, 1979) and in magnetotactic bacteria (Frankel, Blakemore & Wolfe, 1979). Zoeger, Dunn & Fuller (1980) also report a localized concentration of magnetite in dolphin heads, although magneto-sensory behavioural experiments have not as yet been done on them.
Is the Position of the Femur-Tibia Joint Under Feedback Control in the Walking Stick Insect ?
Authors: Cruse H. , Pflüger H.-J. 
Published: April 2021

ABSTRACT
From earlier force measurements it was assumed that the system controlling the position of the femur-tibia joint in the middle leg of the stick insect is active in walking animals. This hypothesis is confirmed by electro physiological recordings and is discussed in relation to several earlier findings concerning the function of the control system of the femur-tibia joint.
Branchial and Renal Acid and Ion Fluxes in the Rainbow Trout, Salmo Gairdneri, at Low Environmental pH
Authors: McDONALD D. G. , Wood C. M. 
Published: April 2021

ABSTRACT
Rainbow trout were exposed for 4 days to an environmental pH averaging 4·2, an exposure which resulted in a continuous net branchial influx of acid. The influx provoked a progressive depression in blood pH and [HCO3−], virtually complete by 48 h, and a marked increase in renal acid excretion, also complete by 48 h. The increase in the latter was sufficient to remove, at maximum, about half of the protons entering at the gills; those remaining were buffered in body fluids. The low pH exposure also impaired gill ion regulation as indicated by continuous net branchial losses of Na+, Cl− and K+ and by a progressive decline in plasma Na+ and Cl− levels. Evidence is presented which indicates that there was a significant contribution by the intracellular compartment both to the total body ion losses and to the buffering of the body acid load.
Ion and Water Transport in Locust Alimentary Canal: Evidence from In Vivo Electrochemical Gradients
Authors: Dow Julian A. T. 
Published: April 2021

ABSTRACT
Sodium occurs at a much lower electrochemical potential in all gut regions than in the blood. The observed gradients do not decrease with time; the maintenance of the high blood sodium levels therefore requires active uptake against an electrochemical gradient. Potassium occurs at a much higher electrochemical potential in all gut regions than in the blood. The observed gradients do not decrease with time; the maintenance of the low blood potassium therefore requires active excretion against an electrochemical gradient. The highest luminal concentration is observed in the posterior midgut. Chloride appears to be passively distributed across the gut. As with potassium, the highest luminal activity is observed in the posterior midgut. Calcium and magnesium are similarly distributed. They both occur at a fairly high level in the blood, crop, caeca and anterior midgut, and at a much lower level in the rest of the gut. The crop and caecal fluids become markedly hyperosmotic to the blood in freshly-fed locusts, but the midgut fluid is isosmotic at all times. The fluid in the ileum is significantly hyposmotic; the shortfall in osmolality, compared with the fluid in the posterior midgut, corresponds to the observed drop in KC1 level. The anterior caeca are the only parts of the alimentary canal to possess a lumen-negative transepithelial potential difference. They differ significantly from the other regions studied, notably the posterior caeca, in this respect.
Dynamic Tensile Properties of the Plantaris Tendon of Sheep (Ovis Aries)
Authors: Ker Robert F. 
Published: April 2021

ABSTRACT
The stresses applied during fast locomotion are sufficient to stretch the tendon far into the linear region of the load-extension plot. The tangent modulus in the linear region is about 1·65 GN.m−2 and is independent of frequency for oscillations in the range 0·22 to 11 Hz. Internal damping dissipates about 7 % of the mechanical energy applied during oscillations. The load range (o to about 1 kN) and frequencies (0·22 to 11 Hz) were comparable to those arising during locomotion. The rate of rise of temperature, during the initial period of an oscillation, was consistent with the mechanical measurement of power loss. The dynamic mechanical properties are appropriate for the hypothesis of energy saving by storage in tendons during fast locomotion.
The Handling of Macromolecules by the Kidney of the River Lamprey, Lampetra Fluviatilis
Authors: Logan A. G. , Morris R. 
Published: April 2021

ABSTRACT
Micropuncture and renal clearance techniques have been used to investigate the effect of molecular size on glomerular permeability in the river lamprey, Lampetra fluviatilis, and to investigate tubular absorption of native and foreign macromolecules.
Polyvinyl pyrrolidone (PVP) molecules of 16 Å in molecular radius were freely filterable but there was significant retention of 37 Å molecules. The estimated sieving coefficients for PVP of 160000 and 360000 in molecular weight (molecular radii &gt; 100 Å) were 07·06 and 07·01 respectively, indicating that the glomerular barrier is relatively leaky.
Up to 50% of microinjected protein was absorbed by the nephron and the results with bovine serum albumin demonstrated that protein uptake occurs chiefly in the proximal brush border segment. The relative rates of uptake for different proteins and different concentrations of injected solutions indicated that the uptake mechanism is easily saturated and unable to distinguish between native and foreign proteins of high molecular weight.
Most lamprey plasma proteins are &gt; 100000 in molecular weight. This, together with other factors such as molecular charge and tubular reabsorption, could account for the low urinary protein concentration of 0-05 mg/ml.