bluuebunny/crossref_metadata_2025_split huggingface dataset:
Renal Electrolyte and Fluid Excretion in the Atlantic Hagfish Myxine Glutinosa
Authors: Alt Jeannette M. , Stolte Hilmar , Eisenbach Georg M. , Walvig Finn 
Published: April 2021

ABSTRACT
Hagfishes (Myxine glutinosa, Cyclostomata) are the only vertebrates whose body fluids are isoosmotic to seawater due to high sodium and chloride concentrations in the plasma. The unique mode of fluid and electrolyte handling of Myxine has been studied by micropuncture methods at the single nephron level. In the archinephric duct, which assumes the function of the tubular apparatus of higher vertebrates, no fluid or sodium is reabsorbed from the glomerular filtrate. Calcium, glucose and magnesium are reabsorbed whereas potassium and phosphate are excreted. The intravascular volume of M. glutinosa is mainly regulated by the filtration rate which greatly increases with increasing arterial as well as venous pressure.
Na+ and C1– Effluxes and Ionic Regulation in Tilapia Grahami, a Fish Living in Conditions of Extreme Alkalinity
Authors: Eddy F. B. , Bamford O. S. , Maloiy G. M. O. 
Published: April 2021

ABSTRACT
The osmoregularity ability of the cichlid Tilapia grahami enables this fish to live in conditions of extreme alkalinity (Reite, Maloiy & Aashaug, 1974; Maloiy et al. 1978). In this paper we describe the ionic balance of T. grahami from Lake Magadi (East African Rift Valley) which has a pH value of around 10, temperature in the range 30–40 °C and an osmotic pressure of about 500 mOsm, the principal inorganic ions being sodium carbonate and bicarbonate (Table 1). We also describe ionic balance of fish in water with a high NaCl concentration and in fresh water.
Ocellar Excitation of the Dcmd: An Identified Locust Interneurone
Authors: Simmons Peter J. 
Published: April 2021

ABSTRACT
Locusts, like most other insects, possess three ocelli, or simple eyes, in addition to two large compound eyes. Focussed images are not formed on the retinae of the ocelli (Parry, 1947; Wilson, 1978a) and ocellar neurones are influenced by changes in light intensity occurring over wide areas of the visual field. Some of the second-order neurones which extend from the retina of each ocellus to the brain have large axons -amongst the largest found in the locust central nervous system. They are expected to convey information about changes in light intensity to the brain with some urgency. At least two different ways in which these large second-order ocellar neurones (L-neurones) could influence the behaviour of a locust have been suggested. First, by monitoring changes in the orientation of the visual horizon they could contribute to the stability of flight (Wilson, 1978a; Stange & Howard, 1979; Simmons, 1980a). Second, they could facilitate the responses of some central neurones, such as those driven by the compound eyes, when light intensity is reduced (Parry, 1947) – for instance, when a shadow falls over the locust. The observations reported here show that the L-neurones boost the responsiveness of a pair of well-characterized central neurones when the overall light intensity is rapidly decreased.
Correlation of Flight-Muscle Size and Body Mass in Cooper’s Hawks: A Natural Analogue of Power Training
Authors: Marsh Richard L. , Storer Robert W. 
Published: April 2021

ABSTRACT
Muscle hypertrophy in response to increased load (e.g. power training) is well documented in laboratory animals and in man (see, for example, Thorstensson, 1976; Gonyea, Ericson & Bonde-Peterson, 1977), but this phenomenon has not been quantitatively linked to changes in the use of muscles by wild animals. In free-living animals, and sometimes even in those used in laboratory studies, predicting the stress placed on an individual muscle is difficult. Thus, evaluating a compensatory response in relation to a change in muscle use is also difficult. The flight muscles of birds, however, represent a system in which changes in muscle size can be quantitatively compared to the power output required for flight. We describe here a correlation of flight-muscle mass with body mass in Cooper’s hawks (Accipiter cooperii). We believe this correlation represents a natural analogue of power training. The variation in muscle mass between individuals can be directly related to differences in the power requirements for flight caused by differences in body mass.
The Effect of Progressive Hypoxia on Heart Rate, Ventilation, Respiratory Gas Exchange and Acid-Base Status in the Crayfish Austropotamobius Pallipes
Authors: Wheatly Michèle G. , Taylor E. W. 
Published: April 2021

ABSTRACT
Male and female crayfish, Austropotamobius pallipes (Lereboullet) maintained a constant rate of O2 uptake during a progressive reduction in ambient O2 tension down to a critical tension (Pc) of 40 mmHg at 15 °c. Heart rate (fH) slowed progressively during hypoxia but blood flow was maintained by an increase in cardiac stroke volume. At a , of 50 mmHg the rate of ventilation had increased to 2·8 times the normoxic value. This was effected by a doubling in respiratory frequency (fR) accompanied by increases in both the mean amplitude of the pressure pulse and the mean hydrostatic pressure recorded in the branchial chambers. The effectiveness of removal of O2 from the water ventilating the gills was maintained (Ew), and there is evidence that the ability of the respiratory surface to transfer O2 improved during hypoxia. The hyperventilation enhanced CO2 elimination so that CO2 tensions were halved and respiratory alkalosis occurred in the haemolymph. This alkalosis had the effect of increasing the affinity of the blood pigment for O2, reducing the half saturation pressure (P50) from 8 to 4·5 mmHg. Thus despite reductions in pre- and postbranchial O2 tensions by 50% the arteriovenous O2 content difference was maintained and the effectiveness of removal of O2 into the blood (Eb) remained high in moderately hypoxic water ( 63 ± 1 mmHg). At , levels below 40 mmHg, when crayfish were denied access to air, they were unable to sustain the hyperventilation. Haemolymph O2 content and the a – v O2 content difference decreased, and as the haemolymph was no longer saturated with O2 on its passage through the gills, Eb was reduced. As a consequence of these changes fell. Under these conditions a partial switch to anaerobic metabolism occurred, with lactic acid accumulating in the haemolymph. The resultant metabolic acidosis partially offset the respiratory alkalosis.
Aerodynamic Capabilities of Flies, as Revealed by a New Technique
Authors: Blondeau Jean 
Published: April 2021

ABSTRACT
Forces and torques exerted by fixed flying Calliphora erythrocephala were monitored with strain gauges. Calliphora was shown to have independent control of all possible parameters of motion (lift, thrust, side-slip, roll, yaw, pitch). During voluntary manoeuvres, the fly modulated several or all of these parameters simultaneously. Modulations of certain parameters were strongly correlated. Possible applications of the strain gauge apparatus and limitations in the use of open-loop experiments for the study of flight behaviour are discussed.
Neural Control of the Male Photuris Versicolor Firefly Flash
Authors: Carlson Albert D. 
Published: April 2021

ABSTRACT
Continuous electrical stimulation of the ventral nerve cord or the lantern of the decapitated male Photuris versicolor firefly over a wide range of stimulus frequencies can produce a flash that is multi-peaked, like the courtship flash of this species. The central nervous system does not shape these stimulated compound flashes because they can be induced in deganglionated posterior lantern segments. The stimulated compound flashes show a fixed oscillatory character with peak frequencies independent of stimulation frequency. They can be generated by individual lantern areas. Compared with the peaks of courtship flashes the peaks of stimulated flashes show higher frequency, significantly lower temperature coefficients (Q)10, and incomplete extinction. P. lucicrescens males produce a courtship flash that has a single peak and their lanterns respond to continuous stimulation with an unstructured glow.
Ultrafiltration in the Branchial Heart Appendage of Dibranchiate Cephalopods: A Comparative Ultrastructural and Physiological Study
Authors: Schipp R. , Hevert F. 
Published: April 2021

ABSTRACT
It is shown that ultrafiltration could be the first step in urine formation in Sepia officinalis and Octopus vulgaris. The organization of the podocytes indicates that ultrafiltration can occur through these cells. They have a thick basal lamina in contact with the peripheral blood lacunae, and the cell apices lie in infoldings of the lumen of the appendage. Comparison between the colloid-osmotic and the hydrostatic pressures of the fluids in the branchial heart and the pericardial coelom shows that an ultrafiltration can take place during the branchial heart systole as well as during a long phase of the diastole. Comparison of the osmolalities of blood, coelomic fluid, renal-sac fluid, and sea water shows that these species are hypoosmotic regulators.
The Effect of Filming Speed on the Interpretation of Arthropod Locomotion
Authors: Ward T. M. , Humphreys F. 
Published: April 2021

ABSTRACT
Films of spider locomotion taken at about 270 frames per second (f.p.s.) were reanalysed to give effective filming speeds of 100, 50 and 25 f.p.s. Reanalysis of the data shows that mean values and variance for phase lag, period, stepping frequency and protraction/retraction ratios depart from the control values (270 f.p.s.) at slower sampling rates. Guidelines are presented for filming arthropod locomotion with high stepping frequencies and high or low p/r ratios. Most film analysis of arthropod locomotion has had insufficient time resolution to examine resolution-sensitive parameters such as the p/r ratio. Filming speeds giving sampling rates greater than 40 frames per step do not increase accuracy.
Analysis of the Flagellar Beat Pattern of Male Ectocarpus Siliculosus Gametes (Phaeophyta) in Relation to Chemotactic Stimulation by Female Cells
Authors: Geller Annette , Müller Dieter G. 
Published: April 2021

ABSTRACT
Heterocontic male Ectocarpus siliculosus gametes respond to the sexattractant ectocarpen by changing their locomotive behaviour. However, the mode of action of the flagella is not changed by the presence of ectocarpen. High-speed cinemicrography shows that gametes moving close to a coverglass perform planar bending waves with their front flagellum. Straight or slightly curved swimming paths are generated by enhanced upward bends of the front flagellum to compensate for the asymmetrical insertion of both flagella. Narrower curves are connected with increasing downward bends of the front flagellum. There is a negative linear correlation between the average deflexion of the front flagellum (μm) from the cell axis and the radius of track (correlation coefficient 0·94). Additionally, freely swimming gametes exhibit elliptical and rotary wave motions, suggesting a relationship between thigmotaxis and mode of action of the front flagellum. The rigid hind flagellum performs one rapid sideward beat when the gametes swim in narrow curves. This appears to provide a steering function.
The Control of Transepithelial Potential Oscillations in the Salivary Gland of Calliphora Erythrocephala
Authors: Rapp P. E. , Berridge M. J. 
Published: April 2021

ABSTRACT
The effects of the hormone 5-hydroxytryptamine, its analogues and its antagonists on the electrical activity and secretion rate of isolated salivary glands of the blowfly Calliphora erythrocephala were investigated. The secretion rate increases linearly with the logarithm of hormone concentration between 10−9 and 10−8M. At &gt;10−8M the transepithelial potential depolarizes and rapidly attains a new stable value. However, at intermediate hormone concentrations, the potential does not maintain a stable intermediate value but displays sustained oscillations. These oscillations are not an artifact resulting from periodic variations in hormone concentration. The frequency of the oscillations increases with hormone concentration and with the concentration of external calcium and hormone analogues. The frequency decreases following the addition of lanthanum to the perfusion medium.
The experimental results suggest that the potential oscillation may be driven by an oscillation in the intracellular concentrations of cyclic AMP and calcium. It is argued that oscillatory control provides a reliable, noiseresistant strategy for controlling secretion rate.
Intracellular Recording of Electrical Activity in Muscle Cells of Intact and Isolated Dorsal Blood Vessel of the Earthworm Lumbricus Terrestris
Authors: Drewes C. D. , Denney M. R. , O’Gara B. , Vining E. P. 
Published: April 2021

ABSTRACT
Intracellular electrical records from muscle cells in intact dorsal blood vessels of the earthworm, Lumbricus terrestris, showed a polarization rhythm which consisted of : (a) a prolonged ramp of depolarization, (b) one or a series of several non-overshooting spike potentials, (c) a sustained, hump-like depolarization, and (d) a complete repolarization. The polarization rhythm of the intact vessel was reset by intracellular current injection. Simultaneous recordings of intracellular electrical and mechanical activities during rhythmic pulsation waves of the intact vessel indicated that the ramp-like depolarization corresponded temporally to a gradual filling of the vessel with blood. Spike potentials occurred during the later portion of filling, and constriction began near the peak of the slow, sustained depolarization. Simultaneous intracellular and extracellular electrical records during rhythmic pulsations of the intact vessel indicated a close temporal correspondence between spike potentials in both electrical records. The repolarization phase in intracellular records corresponded to a small, slow wave in extracellular records. A polarization rhythm was usually absent in isolated preparations of the dorsal blood vessel, but in a few preparations rhythmic activity persisted for up to 1 h. In quiescent isolated preparations membrane potentials were stable (mean resting potential = −66·7 mV), but active membrane responses (non-overshooting spikes and sustained depolarizations), were evoked by intracellular current injection or by stretching of the vessel. Evidence from dual intracellular recordings in isolated dorsal vessels suggest that muscle cells are electrically coupled. The intracellular activity patterns in intact and isolated vessels, and the responsiveness of cells to current injection and stretching, suggest that both initiation and conduction of pulsation waves in the dorsal blood vessel are myogenic.
The Role of Venous Pressure in Regulation of Output from the Heart of the Octopus, Eledone Cirrhosa (Lam.)
Authors: Smith P. J. S. 
Published: April 2021

ABSTRACT
The influence of perfusion pressure on stroke volume and heart rate was examined in the isolated ventricle. Input pressure, within the physiological range (10–20 cm of water), had a direct effect upon stroke volume and heart rate. Output back pressure had an inverse effect upon stroke volume and no effect upon heart rate. Sites that could vary input pressure were investigated by selective denervation in the whole animal. The results indicated that the efferent branchial vessel and auricle may be involved, as well as the branchial hearts and lateral venae cavae. It is proposed that the pressure of venous blood has a limited effect upon ventricular output in vivo.
Calcium Action Potentials in the Skeletal Muscle Fibres of the Stick Insect Carausius Morosus
Authors: Ashcroft Frances M. 
Published: April 2021

ABSTRACT
The ionic requirements for the generation of action potentials in the ventral longitudinal muscle fibres of the stick insect, Carausius morosus, were investigated. Ca-free Ringer rapidly and reversibly abolished the action potential. In the presence of tetraethylammonium (TEA) ions (to suppress outward currents) the overshoot of the action potential changed 26 mV for a 10-fold change in [Ca]o. The maximum rate of rise of the action potential (measured in TEA Ringer) showed saturation at high [Ca]o. Cobaltous ions (20 mm) and the organic Ca antagonist D 600 (5 × 10−4 g/ml) reversibly inhibited the action potential ; the inhibitory effect of 1 mm-La3+ was irreversible. Barium and strontium, but not magnesium, were able to substitute for calcium as charge carriers. These results suggest that an inward movement of Ca2+ underlies the action potential of Carausius fibres.
Multiple Postsynaptic Actions of the Giant Dopamine-Containing Neurone R.Pe.D.1 of Lymnaea Stagnalis
Authors: Winlow W. , Haydon P. G. , Benjamin P. R. 
Published: April 2021

ABSTRACT
Evidence is presented that the giant neurone R.Pe.D.1 is mono-synaptically connected to follower cells in the right parietal and visceral ganglia and has excitatory, inhibitory and biphasic postsynaptic actions. The spike to e.p.s.p. latency is increased to a new fixed value by high calcium saline, but not by saline in which both the Ca2+ and Mg2+ concentrations have been increased in proportion to one another. Three distinct classes of p.s.p. latency exist. Short e.p.s.p. and b.p.s.p. latencies of ca. 16·0 to 20 ms have been observed, as have longer e.p.s.p. and b.p.s.p. latencies, ca. 38−44 ms. An i.p.s.p. with a latency to onset of ca. 182 ms occurs on the J cells.
Electrical Activity and Relative Length Changes of Dog Limb Muscles as A Function of Speed and Gait
Authors: Goslow G. E. , Seeherman H. J. , Taylor C. R. , McCUTCHlN M. N. , Heglund N. C. 
Published: April 2021

ABSTRACT
Electrical activity and length changes of 11 muscles of the fore- and hindlimbs of dogs walking, running, and galloping on a treadmill, were measured as a function of forward speed and gait. Our purpose was to find out whether the activity patterns of the major limb muscles were consistent with the two mechanisms proposed for storage and recovery of energy within a stride : a ‘pendulum-like’ mechanism during a walk, and a ‘spring-like’ mechanism during a run.
In the stance phase of the walking dog, we found that the supraspinatus, long head of the triceps brachii, biceps brachii, vastus lateralis, and gastrocnemius underwent only minor length changes during a relatively long portion of their activity. Thus, a major part of their activity during the walk seems consistent with a role in stabilization of the joints as the dog ‘pole-vaulted’ over its limbs (and thereby conserved energy).
In the stance phase of trotting and/or galloping dogs, we found that the supraspinatus, lateral head of the triceps, vastus lateralis, and gastrocnemius were active while being stretched prior to shortening (as would be required for elastic storage of energy), and that this type of activity increased with increasing speed.
We also found muscular activity in select limb flexors that was consistent with storage of kinetic energy at the end of the swing phase and recovery during the propulsive stroke. This activity pattern was apparent in the latissimus dorsi during a walk and trot, and in the biceps femoris during a trot and gallop.
We conclude that, during locomotion, a significant fraction of the electrical activity of a number of the dog’s limb muscles occurs while they undergo little or no length change or are being stretched prior to shortening and that these types of activities occur in a manner that would enable the operation of pendulum-like and spring-like mechanisms for conserving energy within a stride. Therefore these forms of muscular activity, in addition to the more familiar activity associated with muscle shortening, should be considered to be important during locomotion.
Homologies Between Body Movements and Muscular Contractions in the Locomotion of Two Decapods of Different Families
Authors: Paul Dorothy Hayman 
Published: April 2021

ABSTRACT
The movements performed by the abdomen and tailfan during tailflipping in the sand crab Blepharipoda occidentalis (family Albuneidae) are described from an analysis of high-speed cinematic film (Figs. 1, 2, 3 A), and compared with component movements in the swimming-by-uropod-beating behaviour of the sand crab Emerita analoga (Family Hippidae) (Fig. 3 B; Paul, 1971). The most striking qualitative difference is the absence of uropod retraction and protraction in Blepharipoda. Comparisons of clectromyo-grams recorded from some of the principal muscles involved in these overtly very different behaviour patterns reveal that homologous muscles in the two sand crabs tend to be activated at comparable phase positions (Table 1). Tailflipping and uropod beating in the two crabs appear to be homologous, and to have been derived from ancestral macruran tailflipping.
The Involvement of Nerves in the Epithelial Control of Crumpling Behaviour in A Hydrozoan Jellyfish
Authors: King Michael G. , Spencer Andrew N. 
Published: April 2021

ABSTRACT
The excitation pathways mediating the protective crumpling behaviour of Polyorchis penicillatus were studied with electrophysiological and ultrastructural techniques. Stimulating the subumbrellar endoderm consistently resulted in a complex crumpling potential when recorded with suction electrodes from radial muscle (the prime effector). The potential represents the summation of a quick radial muscle potential (RMP) and a slow endodermal canal pulse (ECP). The latencies of ECPs recorded from radial muscle during crumpling were directly proportional to the distance between the recording electrode and the subumbrellar stimulating electrode. Conversely, the latencies of RMPs, which were not tightly time-coupled to ECPs, were more directly related to the distance of the recording and stimulating electrodes from the marginal or apical termini of the radial muscle. Stimulating the exumbrellar ectoderm resulted in a variable crumpling response, typically occurring after facilitation of numerous exumbrellar pulses (EPs). Since exumbrellar stimulation did not usually excite endoderm, the response recorded from radial muscle normally involved a simple RMP, unassociated with an ECP. Typical synaptic junctions were observed between radial muscle processes and marginal neurites and between radial muscle and neurites of the radial nerve bundles along the length of the muscle. The independence of the ECP and RMP conducting pathways demonstrates that endoderm does not provide the direct source of radial muscle excitation and the initiation of RMPs at points of known (marginal) and suspected (apical) nerve-muscle contact suggests the involvement of nerves in the control of crumpling behaviour. These results are discussed in the light of other examples of active neuronal-epithelial interaction.
The Role of the Salivary Glands in Feeding in Rhodnius Prolixus
Authors: Ribeiro J. M. C. , Garcia E. S. 
Published: April 2021

ABSTRACT
The effect of salivarectomy on feeding in Rhodnius prolixus was studied. Salivarectomized insects drew less blood and at a lower rate than controls when fed on a rabbit. Operated insects also pierced host skin much more often (10 times in 5 min) than controls (1 or 2 times in 5 min). None of these differences was observed when feeding was performed artificially through latex membranes. Intradermal injection of salivary secretion in rat tails increased the duration of bleeding induced by small cuts made on the injection site. It is suggested that the antihaemostatic action of saliva is important for positioning of the maxillae inside blood vessels.