bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study of the Deformability of Red Blood Cells of A Teleost Fish, the Yellowtail (Seriola Quinqueradiata), and A Comparison with Human Erythrocytes
Authors: Hughes G. M. , Kikuchi Y. , Watari H. 
Published: April 2021

ABSTRACT
The blood of a carangid fish, the yellowtail (Seriola quinqueradiata) has been studied with particular reference to the deformability properties of the red blood cells. The rate at which blood flows through a Nuclepore filter containing 5 μm pores has been determined under the same conditions that have been used with human blood. Marked differences were found in the flow of yellowtail blood which depended on the particular way in which the blood had been sampled. Such differences seem to be due to a sensitivity of fish red blood cells to their environmental conditions. Blood flow through filters is temperature-dependent, the rate increasing with a rise in temperature. Measurements made at 37 °C gave values which were similar to those normally obtained for human red blood cells, in spite of their greater dimensions (10·4 × 6·8 × 3·4μm), and nucleated nature. It was also found that the blood flow rate of human blood was slower than that of yellowtail blood when measured at the normal environmental temperatures (15 °C) for these fish.
The Effects of Tetraethylammonium and Other Agents On the Potassium Mechanoreceptor Current in the Ciliate Stylonychia
Authors: Deitmer Joachim W. 
Published: April 2021

ABSTRACT
The membrane response to mechanical stimulation was investigated under voltage-clamp conditions in the hypotrich ciliate Stylonychia mytilus (Protozoa). The mechanoreceptor current shows high ionic selectivity, unlike that in metazoans. It is exclusively carried by potassium ions and is selectively inhibited by tetraethylammonium and 4-aminopyridine. Procaine, tetramethylammonium, caesium and divalent cations have no or little effect on this receptor current. The ionic channels mediating the currents differ from voltage-dependent channels in the ciliate membrane in their low sensitivity to divalent cations, and their relatively high sensitivity to tetra-ethylammonium and 4-aminopyridine.
Respiration and Acid-Base Physiology of the Spotted Gar, A Bimodal Breather
Authors: Smatresk Neal J. , Cameron J. N. 
Published: April 2021

ABSTRACT
Elevation of temperature from 20 to 30 °C, increased the pulmonary ventilation and pulmonary oxygen consumption (from 0·18 to 0·43 ml O2.kg−1. min−1). The total CO2 excretion also rose, but branchial ventilation and branchial oxygen consumption did not change significantly.
The blood pH dropped quickly when temperature was elevated, with a slope (dpH/dT°) of −0·015, but the OH−/H+ ratio did not change significantly. This change in pH resulted from an elevation in arterial , without any concomitant change in plasma HCO3−. Arterial per se was probably not actively regulated, but rose passively as a consequence of the gar’s utilization of the lung for increased oxygen uptake, and the inefficiency of the lung in CO2 exchange. The lung had an exchange ratio (R) of about 0·1.
Temperature change produced no significant alteration in the net acid excretion from either the kidney or the gills, despite an increased ammonia excretion rate at 30 °C. The urine formation rate was very low (74 μl. 100 −1.h− 1) which imposed a limitation on the importance of the kidney in acid-base regulation.
Hypercapnia produced a respiratory acidosis which was partially compensated by an elevation in blood HCO3− after 24 h of exposure. The gill ventilation rose only slightly, and later fell as compensation proceeded. Air-breathing frequencies were not greatly affected by hypercapnia.
The Physiology and Morphology of Median Nerve Motor Neurones in the Thoracic Ganglia of the Locust
Authors: Burrows Malcolm 
Published: April 2021

ABSTRACT
Simultaneous intracellular recordings have been made from the two expiratory, and from the two inspiratory motor neurones which have their axons in the unpaired median nerves of the thoracic ganglia. Each motor neurone has an axon that branches to innervate muscles on the left and on the right side of one segment.
The expiratory neurones studied were those in the meso-and metathoracic ganglia which innervate spiracular closer muscles. The depolarizing synaptic potentials underlying the spikes during expiration are common to the two closer motor neurones in a particular segment. Similarly, during inspiration when there are usually no spikes, the hyperpolarizing, inhibitory potentials are also common to both motor neurones. The synaptic input to the neurones can be derived from four interneurones; two responsible for the depolarizing potentials during expiration and two for the inhibitory potentials during inspiration.
The inspiratory neurones studied were those in the abdominal ganglia fused to the metathoracic ganglion which innervate dorso-ventral abdominal muscles. During inspiration the two motor neurones of one segment spike at a similar and steady frequency. The underlying synaptic input to the two is common. During expiration, when there are usually no spikes, the hyperpolarizing synaptic potentials are also common to both neurones. In addition they match exactly the depolarizing potentials occurring at the same time in the closer motor neurones. The same set of interneurones could be responsible.
No evidence has been revealed to indicate that the two closer, or the two inspiratory motor neurones of one segment are directly coupled by electrical or chemical synapses.
The morphology of both types of motor neurone is distinct from that of other motor neurones in these ganglia. Both types branch extensively in both the left and in the right areas of the neuropile.
Auditory Acuity in the Sea Catfish (Arius Felis)
Authors: Tavolga William N. 
Published: April 2021

ABSTRACT
Frequency discrimination limens and signal-to-noise ratios were determined for the sea catfish, Arius felis, using avoidance-conditioning techniques. The lowest frequency discrimination limens had values of about 2·5 % at 100 Hz. Other determinations were 3·5 % at 200 Hz, and 5 % at 400 Hz, but these values were significantly greater if the test frequencies were higher than the reference. Signal-to-noise ratios were 14 dB at 100 Hz, 18 dB at 200 Hz, and 24 dB at 400 Hz, with reference to the spectrum level of broad-band noise. These findings, and previous measurements of acuity, are discussed in relation to echolocation in Arius, which is known to involve sounds in the 100-200 Hz range.
Resting Tension and Posture in Arthropods
Authors: Yox Daniel P. , Dicaprio Ralph A. , Fourtner Charles R. 
Published: April 2021

ABSTRACT
This study was prompted by reports of resting tension in muscles of various arthropods (Machin & Pringle, 1959; Hoyle, 1968; Burns & Usherwood, 1978; Hoyle, 1978; Hawkins & Bruner, 1979) and our observation that when the legs of the cockroach and crab are severed from the thorax, the joints appear to assume rather fixed angles. Recently Chesler & Fourtner (1981) have shown that significant resting tension exists in one of the femoral extensors of the cockroach (muscle 177 d) (Carbonell, 1947). The purpose of this study was to determine if resting tension is characteristic of all the limb muscles and if it could account for the fixed angle of the joint. We present evidence in this report that resting tension in the leg muscles of the cockroach, Periplaneta americana, and the crab, Carcinus maenas, is responsible for maintaining a relatively fixed angle in the joints of the limbs. These data, along with other evidence, provide a good argument for a system in which posture is partially maintained in these arthropods by resting tension which appears to be passive in nature. The maintenance of posture by this passive mechanism could result in an energetic savings in a quiescent arthropod.
The Effects of Calcium On Sodium Fluxes in the Brown Trout, Salmo Trutta, in Neutral and Acid Water
Authors: McWILLIAMS P. G. 
Published: April 2021

ABSTRACT
It is well established that external calcium can have a marked effect on sodium fluxes in both marine and freshwater organisms (Potts & Fleming, 1971; Cuthbert & Maetz, 1972; Fleming, Nichols & Potts, 1974; Eddy, 1975; Carrier & Evans, 1976; Isaia & Masoni, 1976). In the few fish species which have so far been examined the effects of external calcium appear to be primarily on sodium efflux, which is reduced in the presence of calcium (Fleming et al. 1974; Eddy, 1975; Isaia & Masoni, 1976). The influence of calcium on sodium influx shows considerably more variation between species (Shaw, 1960; Sutcliffe, 1971; Eddy, 1975) making it difficult to propose a suitable mechanism to account for the observed effects.
Skylight Polarization Patterns and Animal Orientation
Authors: Brines Michael L. , Gould James L. 
Published: April 2021

ABSTRACT
Although many invertebrate animals orient by means of ultraviolet sky-light polarization patterns, existing measurements of these patterns are inadequate for full analysis of the biologically relevant information available from the sky. To fill this gap we have used a precision scanning polarimeter to measure simultaneously the intensity, degree, and direction of vibration (E-vector orientation) of polarized light at 5° intervals over the sky. The resulting sky maps were constructed for u.v. (350 nm) and visible wavelengths (500 and 650 nm) under a variety of atmospheric conditions. Our measurements confirmed that the patterns of radiance and degree of polarization of skylight are highly variable and hence unreliable as orientation cues; but patterns of E-vector orientation are relatively stable and predictable over most of the sky under all but very hazy or overcast conditions. The observed E-vector patterns correspond more closely to predictions based on first order (Rayleigh) scattering at 650 and 500 nm than at 350 nm. This is true both in terms of absolute accuracy and the proportion of the sky with relatively ‘correct’ information. Yet most insects respond to polarization patterns only at u.v. wavelengths. This apparent paradox can perhaps be resolved by assuming that there is no great selective advantage for any particular wavelength when large areas of blue sky are visible, but that under special and difficult conditions ultraviolet has advantages over longer wave-lengths. Measurements under partially cloud-covered sky, for instance, or under extensive vegetation, show that both spuriously polarized and un-polarized light resulting from reflexions present more troublesome interference at longer wavelengths than in the u.v. The accuracy of orientation achieved by dancing honey bees appears to be greater than can readily be accounted for by assuming that they use a strictly geometrical or analytical processing system for their orientation to polarized light.
Energetic advantages of burst-and-coast swimming of fish at high speeds
Authors: Videler J. J. , Weihs D. 
Published: April 2021

ABSTRACT
A theoretical model describes how an intermittent swimming style can be energetically advantageous over continuous swimming at high average velocities. Kinematic data are collected from high-speed ciné pictures of free swimming cod and saithe at high velocities in a burst-and-coast style. These data suggest that fish make use of the advantages shown by choosing initial and final burst velocities close to predicted optimal values. The limiting role of rapid glycogen depletion in fast white anaerobic muscle fibres is discussed.
Oxygen uptake in air and water in the air-breathing reedfish Calamoichthys calabaricus: role of skin, gills and lungs
Authors: Sacca R. , Burggren W. 
Published: April 2021

ABSTRACT
The reedfish Calamoichthys calabaricus (Smith) is amphibious, making voluntary excursions on to land (in a simulated natural environment) an average of 6 + 4 times/day for an average duration of 2·3 ± 1·3 min.
Oxygen uptake is achieved by the gills, skin and large, paired lungs. In water at 27 °C, total oxygen uptake is 0·088 ml O2/g. h. The lungs account for 40%, the gills 28%, and the skin 32% of total .
Total oxygen uptake during 2 h of air exposure increases from 0·117 ml O2/g.h to 0·286 ml O2/g.h, due largely to an enhanced lung and a small increase in skin .
Calamoichthys is both capable of aerial gas exchange and adapted to maintain O2 uptake during brief terrestrial excursions.
Structure and Function of the Auditory System in the Clown Knifefish,Notopterus Chitala
Authors: Coombs Sheryl , Popper Arthur N. 
Published: April 2021

ABSTRACTHearing sensitivity and the anatomy of the auditory system in the clown knifefish, Notopterus chitala, were studied using behavioural techniques and scanning electron microscopy. While many structural features of the inner ear were similar to those found in other teleost species, the saccular endorgan in Notopterus was unusual in having three discrete epithelial regions. These regions could be distinguished from one another by regional differences in portions of the otolith overlaying them, by hair-cell orientation patterns, and by their position relative to the swimbladder. Notopterus was found to be able to detect sounds from 100 to 1000 Hz and best sensitivity occurred at 500 Hz, where the mean threshold was – 30 dB (re : 1 microbar). For frequencies from 300 to 700 Hz there was substantial variation in threshold values and indications of a bimodal distribution of thresholds. One hypothesis that may tie the ultrastructural and behavioural results together is that the ear in Notopterus is anatomically and functionally differentiated to mediate independent detection of two sound properties: changes in pressure and particle motion.
The effect of temperature on the oxygen dissociation curves of whole blood of larval and adult lampreys (Geotria australis)
Authors: Macey D. J. , Potter I. C. 
Published: April 2021

ABSTRACT
Oxygen dissociation curves of the whole blood of larvae and adults of the Southern Hemisphere lamprey Geotria australis have been determined between pH 6·8 and 8·2 at 5, 15 and 25 °C. The P50’s at temperatures of 5, 15 and 25 °C and a pH of 7·75 were respectively 0·57,0·92 and 1·19 mmHg in larvae and 6·9,10·3 and 19·0 mmHg in adults. The relatively very high affinity of larval blood for oxygen may reflect an adaptation to low environmental oxygen tensions. The Bohr shift was not significantly affected by either temperature or life-cycle stage. The slope (n) in Hill plots increased with temperature and oxygen saturation, and was greater in adults than in larvae.
Cardiovascular changes associated with treadmill running in the Pekin duck
Authors: Bech Claus , Nomoto Shigekt 
Published: April 2021

ABSTRACTSix adult white Pekin ducks were trained to run on a treadmill for 10 min at a speed of 1·43 km h−1. O2 consumption, CO2 production, breathing rate, blood gas tension and pH, sciatic and carotid blood flows and colonic and skin temperatures were measured in the experiments.A 2·6 times increase in oxygen consumption was observed when going from resting on the treadmill to exercise. The increased oxygen delivery was achieved by a 61% increase in cardiac output and a 51% increase in the arterio-venous oxygen content difference. Probably the reported resting oxygen consumption was higher than a true resting level causing the increment in oxygen consumption to be more correctly 3·6 times the resting level.Sciatic and carotid blood flow increased by 3·7 times and 2·3 times, respectively, during exercise. At cessation of exercise, the carotid blood flow decreased very rapidly, while the sciatic blood flow decreased more slowly. An increased web temperature above the exercise level was seen in the post-exercise period.The results suggest that the ducks prefer to use non-evaporative heat loss in the post-exercise period, respiratory evaporative cooling being of minor importance. This strategy may be correlated to the small internal heat load induced by the running (body temperature increased by only 0·3 °C).
Interneurones Co-Ordinating the Ventilatory Movements of the Thoracic Spiracles in the Locust
Authors: Burrows Malcolm 
Published: April 2021

ABSTRACT
A pair of interneurones has been identified by intracellular recording and staining which co-ordinates the movements of the thoracic spiracles in the ventilatory rhythm.
An interneurone has its cell body on the left or on the right side of the metathoracic ganglion and an axon which ascends to the other thoracic ganglia in the contralateral connective. Each interneurone produces bursts of spikes in time with the inspiratory phase of ventilation. These spikes evoke inhibitory post-synaptic potentials (IPSPs) in thoracic spiracular closer motor neurones. Both interneurones synapse upon the closer motor neurones in each thoracic segment. These connexions, which may be direct, inhibit the spiking of the closer motor neurones during inspiration.
The interneurones do not appear to have an innate rhythmicity but instead receive a periodic synaptic input which inhibits their spikes during expiration. The underlying cause of the spikes is less clear. Apart from brief periods at the start and end of a burst, the spikes occur at a constant frequency that is independent of the ventilatory rate.
The pattern of the spiracular motor output could be altered by manipulating the frequency and number of spikes in an interneurone. When the frequency of spikes in the interneurone was raised, the motor bursts had a higher initial frequency and were of briefer duration ; when the frequency was lowered, the motor bursts were of lower initial frequency and of longer overall duration. Altering the spikes in one interneurone, however, could not affect the frequency of the ventilatory rhythm, or reset the rhythm.
The Distances at Which a Primitive Jumping Spider,Portia Fimbriata, Makes Visual Discriminations
Authors: Jackson R. R. , Blest A. D. 
Published: April 2021

ABSTRACTThe anterior median (AM) or principal eyes of the primitive jumping spider, Portia fimbriata (Doleschall), are miniature telephoto systems (Williams & McIntyre, 1980). Another study on the AM eyes of Plexippus suggests that most salticid principal eyes may be of similar design (Blest, Hardie, McIntyre and Williams, 1982). Both studies assumed, from anecdotal evidence (e.g. Forster, 1979), that jumping spiders can make visual discriminations between prey and mates at distances of ca. 20 cm. This estimate is necessary to the functional analyses that were essayed; because it is impossible to make sufficiently accurate direct measurements of some of the parameters of these small eyes, their optics can only be modelled with confidence when something is known about what they are designed to see. Land (1969 a, b), in an elegant optical study, followed Drees (1952) in stating that jumping spiders respond to significant objects some 5-10 body-lengths in front of them. In the case of Portia, this would be a distance of no more than 10 cm at most. Recognition of objects is mediated through the AM eyes (Drees, 1952).
The effects of hypercapnia on intracellular and extracellular acid-base status in the toadBufo marinus
Authors: Toews D. P. , Heisler N. 
Published: April 2021

ABSTRACTToads (Bufo marinus) were exposed to environmental hypercapnia of 5 % CO2 in air, and extracellular and intracellular acid-base parameters were determined 1 and 24 h after the onset of hypercapnia.The initial drop in pH was compensated by the elevation of extracellular and intracellular bicarbonate. Relating the pH compensation to the pH drop that is expected to occur by increased at constant bicarbonate concentration, the pH compensation in the extracellular space was 30 % and reached the following values for intracellular body compartments : 65 % in skeletal muscle, 77 % in heart muscle and 44 % in skin. The additional bicarbonate was partly produced by blood and intracellular non-bicarbonate buffers; the major portion of the remainder was related to the excretion of ammonia into the environmental water.The hypercapnia-induced changes of pH were considerably smaller in all tissue cells than in the extracellular space. Thus Bufo marinus exhibits the relative preference of intracellular over extracellular acid-base regulation that has been observed in other vertebrates.
Physiological Evidence for the Occurrence of Pathways Shunting Blood Away from the Secondary Lamellae of Eel Gills
Authors: Hughes G. M. , Peyraud C. , Peyraud-Waitzenegger M. , Soulier P. 
Published: April 2021

ABSTRACT
Several cardiovascular and respiratory measurements have been performed in eels before and after intravenous injections of adrenaline. These experiments have allowed a comparison to be made of values for the cardiac output determined directly () and using the Fick principle () on individual fish under these two conditions. Under control conditions it was shown that = 0·72, indicating that about 30% of the mixed venous blood afferent to the gills is returned directly to the heart and bypasses the lamellar circulation via veno-venous anastomoses between the afferent filament arteries and the central venous space of the gill filaments. Adrenaline, which during winter only has its action due to stimulation of α-adrenoreceptors, induced a hypoventilation but no changes in cardiac output in spite of a bradycardia. The oxygen content of the mixed venous blood was markedly increased whereas remained unchanged as did the percentage utilization of oxygen from the water as it passed over the gills. The efferent blood flow from the gills after injection of adrenaline was almost equal to the total cardiac output.
It is suggested that such a circulatory change was due to adrenaline-mediated constriction of veno-venous anastomoses in the gills of the eel.
Identification of the Bursicon-Containing Neurones in Abdominal Ganglia of the Tobacco Hornworm, Manduca Sexta
Authors: Taghert Paul H. , Truman James W. 
Published: April 2021

ABSTRACT
The abdominal ganglion neurones responsible for the secretion of the peptide hormone bursicon from the transverse nerves of the tobacco hornworm Manduca sexta have been localized. Each unfused abdominal ganglion produced bursicon during adult development. The hormone was then transported to the next posterior transverse nerve for subsequent release following adult emergence. Of the two efferent pathways that connect ganglia to posterior transverse nerves, only one had ultrastructural features consistent with a neurosecretory function. All axons in this pathway contained numerous, elementary, dense-cored granules with diameters ranging from 100 to 300 nm.
In pharate adults, cobalt back-filling of this neurosecretory pathway revealed two groups of cell bodies in abdominal ganglia : three dorso-laterally and eight at the mid-line. Hormonal activity was present in lateral regions of the ganglion but not in mid-line regions. In the dorso-lateral region, four blueish cell bodies could be seen in the living tissue. The two combined clusters of four cells from both sides of the ganglion contained more than 60% of the bursicon activity present in the entire ganglion. More careful dissection of the cluster detected the presence of activity in cell pairs and individual members.
Individual dye-fills of these blue cells demonstrated that three of these were the three lateral neurones that were back-filled from the transverse nerve. The fourth blue cell may be identical to a neurone whose axon travels in the descending, contralateral connective and exits the nervous system via the next posterior ganglion. On the basis of dendritic geometry, each of the neurones in the bursicon cell cluster could be identified as a unique, individual neurone.