bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Kinetic Method for the Measurement of Zinc Influx in vivo in the Rainbow Trout, and the Effects of Waterborne Calcium on Flux Rates
Authors: Spry D. J. , Wood C. M. 
Published: April 2021

ABSTRACT
Three methods were evaluated to measure rate of influx of Zn into rainbow trout. The first two, disappearance of 65Zn from the water and whole-body counting, overestimated influx when compared with a third method which used a terminal plasma sample to calculate influx. The cause of the overestimate was a short-term adsorption phenomenon to both the experimental apparatus and the exterior of the fish. The third method measured only Zn which entered the fish. This method entailed ‘calibration’ of cannulated trout by constant infusion of small amounts of radiolabelled Zn. This was analogous to the entry of Zn into fish across the gill. After 24-36 h of infusion, plasma radioactivity reached a steadystate concentration which was a simple linear function of the rate of infusion. This relationship was then used to predict influx from a single terminal plasma sample from uncannulated trout exposed to radiolabelled Zn in the water. Trout acclimated to tapwater (Ca2+= 2·0 mequiv P1) and exposed to Zn (1·5–45·9 /μequiv I−1; 0·05–1·5 mg I−1) showed saturable uptake which was apparently first order with no significant linear component. The apparent Jmax and Km were 314nequivkg−1 h−1 and 7·3iμequivl_1 (0·24mgl−1), respectively. Acutely raising the waterborne [Ca2+] (4·7 and 9·7 mequiv I−1) over the same range of [Zn] revealed a competitive type of interaction -little change in Jmax, with increased Km. When Ca2+ was acutely removed (0-05 and 1-02 mequiv I−1) by the use of artificial soft water, significant linear influx occurred in addition to the saturable uptake noted at higher [Ca2+], suggesting the opening of a paracellular leak. Calculation of the inhibitor constant for Ca2+ yielded a value of 0·48 mequiv I−1. This value is similar to the Km for Ca2+ when it was a transported substrate (0·28 ± 0·07 mequiv I−1). The true Km for Zn transport in the absence of Ca2+ was 1-Oqequivl−1 (0·06mgl−1). These data showed Zn influx to be saturable and strongly dependent upon waterborne [Ca2+], perhaps traversing the gill in a manner similar to Ca2+.
The Visual Acuity of Octopuses For Gratings of Different Orientations
Authors: Muntz W. R. A. , Gwyther J. 
Published: April 2021

ABSTRACT
A recent study has shown that the minimum separable angle of visual acuity of Octopus pallidus and O. australis lies between 4·4′ and 9·7′ when vertical and horizontal gratings are used as test objects (Muntz & Gwyther, 1988). In view of other observations - the horizontal rectangular shape of octopus pupils, the pronounced astigmatism of the lens of Eledone cirrhosa (SroczyŃski & Muntz, 1985), the difficulty that O. vulgaris has in discriminating between oblique rectangles (Sutherland, 1957), and the vertically and horizontally arranged rectilinear organization of both retina and neurones in the optic lobe of O. vulgaris (Young, 1960) - it seemed worthwhile testing the effect of grating orientation on visual acuity in more detail, and in particular extending the measurements to include oblique gratings oriented at 45° with respect to gravity.
Small Cardioactive Peptide B Modulates Limax Feeding Motoneurones
Authors: Hess Stephen D. , Prior David J. 
Published: April 2021

ABSTRACT
Although first described for its actions on the heart of the snail, Helix (Lloyd, 1978), small cardioactive peptide B (SCPB) has since received attention primarily for its neuronal effects. The effects of SCPB on the feeding neuronal networks of gastropods are particularly well characterized (e.g. Lloyd et al. 1984; Murphy et al. 1985; Sossin et al. 1987; Willows et al. 1988). However, less is known about cellular mechanisms by which the peptide enhances feeding responsiveness. The isolated central nervous system (CNS) preparation of the terrestrial slug Limax maximus is particularly useful for studies which examine the role of peptides in the expression of feeding, since the feeding motor programme can be reliably elicited by chemical stimulation of the lips (Gelperin et al. 1978) or electrical stimulation of the lip nerves (Phifer & Prior, 1985). SCPB increases both the responsiveness of the feeding motor programme and the burst frequency of the fast salivary burster neurone of Limax (Prior et al. 1985; Prior & Watson, 1988). We therefore used intracellular recordings to examine the membrane responses which underlie the ability of SCPB to increase the burst frequency of the fast salivary burster neurone (FSB). Portions of this work have appeared in an earlier abstract (Hess & Prior, 1986).
Length-Tension Relationships of Masseter and Digastric Muscles of Miniature Swine During Ontogeny
Authors: Anapol Fred , Herring Susan W. 
Published: April 2021

ABSTRACT
At incremental whole muscle lengths, active isometric and passive elastic forces were recorded from the masseter and digastric muscles of anaesthetized miniature pigs (Hanford) weighing 2·0−20·0 kg. Wet muscle mass and maximum tetanic tension values for masseter exceed those for digastric and increase more rapidly with body mass (age). At any body mass, masseter exceeds digastric in the ratio of optimum length (that length at which maximum tetanic tension is produced) to in situ muscle length (that length which corresponds to the jaw in a closed position) and the proportion of passive tension comprising total (passive plus active) tension. Passive elastic tension begins to rise in masseter at lengths as short as 87 % of optimum (in younger pigs). In digastric, passive tension is absent until the muscle is stretched to a length slightly longer than optimum in younger pigs but occurs at shorter lengths in older pigs.
Contractile properties explain functional differences between masseter and digastric more clearly than they explain ontogenetic changes in either muscle. The behavioural transition from infant suckling to adult mastication of solid food is best characterized by a disproportionate increase in mass (and force) of the masseter, relative to digastric, and increased reliance upon active (rather than passive) tension.
Properties of a Set of Internal Receptors in the Medicinal Leech: The Nephridial Nerve Cells Monitor Extracellular Chloride Concentration
Authors: Wenning Angela 
Published: April 2021

ABSTRACT
In the leech, Hirudo medicinalis, the functional properties of the peripheral nephridial nerve cells (NNCs) were investigated using long-term extracellular recordings from both intact and isolated preparations.
The NNCs respond selectively to changes in external Cl− concentration: their electrical activity is highest in fluid containing normal (i.e. low) extracellular [Cl−]. Their sensitivity to Cl− is confined to the dendritic tree. Extracellular [Cl−] is a control factor for ion homeostasis. It increases drastically after a blood meal, and after the animal has left the water or invaded brackish water. The NNCs continuously monitor the extracellular Cl− concentration: their burst rate changes, without adapting, by a factor of 4 in the physiological range between 40 and 90 mmoll−1.
Intracellular recordings from the NNC in isolated nephridial complexes suggest that a high Cl− conductance in combination with active transport of Cl− could be responsible for the observed Cl− sensitivity.
Energy Metabolism in Trout Red Cells: Consequences of Adrenergic Stimulation in Vivo and in Vitro
Authors: Ferguson R. A. , Tufts B. L. , Boutilier R. G. 
Published: April 2021

ABSTRACT
β-Adrenergic stimulation of salmonid red cells results in a rapid decrease (within 5 min) in the nucleotide triphosphate: haemoglobin ratio (NTP:Hb), which is thereafter maintained at a constant level, presumably through increased ATP turnover via matched aerobic metabolism and energy-consuming processes. Addition of the β-adrenergic agonist isoproterenol to rainbow trout red cells in vitro leads to a rise in intracellular pH (pHi), a corresponding decrease in extracellular pH (pHe) and an increase in red cell oxygen consumption . Moreover, the extent to which red cell pHi is maintained constant in the face of an acute extracellular acidosis in vitro or in vivo is proportional to the adrenergically stimulated increase in red cell . In the absence of oxygen, these red cells remain capable of pH regulation, but cannot maintain NTP:Hb constant. As a result, membrane and metabolic functions become uncoupled in the stimulated deoxygenated cells.
Phosphocreatine Represents a Thermodynamic and Functional Improvement Over Other Muscle Phosphagens
Authors: Ellington W. Ross 
Published: April 2021

ABSTRACT
In vertebrate tissues, the only phosphagen is phosphocreatine (PC), and the corresponding phosphotransferase is creatine phosphokinase (CPK). Among invertebrates, a variety of phosphotransferase reactions are found in addition to CPK, including arginine phosphokinase (APK), glycocyamine phosphokinase (GPK), taurocyamine phosphokinase (TPK) and lombricine phosphokinase (LPK). Although there is some uncertainty about the exact value, the apparent equilibrium constant for the CPK reaction ( = [creatine][ATP]/[PC][ADP]), under physiological conditions similar to those of vertebrate muscle, ranges from 100 to 160. The corresponding K′ value for the APK reaction is somewhat controversial, and K′ values for the GPK, TPK and LPK reactions are not known. In this study, conventional and 31P-NMR methods were used to evaluate the equilibrium constants for the APK, GPK, TPK and LPK reactions relative to that of CPK. The corresponding K′values for the APK, GPK, TPK and LPK reactions, expressed as a percentage of , are 13, 29, 29 and 32 %, respectively. The exclusively invertebrate phosphagens exist as a cohort of thermodynamically more stable compounds. Thus, PC constitutes a thermodynamic (and functional) improvement, in that the CPK reaction is able to buffer ATP at much higher ATP/ADP ratios than are other phosphagens. However, possession of a phosphagen system with a lower K′value may be advantageous under certain specific physiological conditions such as intracellular acidosis.
Hydrogen Ion Equilibria in Fish Haemoglobins
Authors: Jensen Frank B. 
Published: April 2021

ABSTRACT
H+ titration studies on oxygenated and deoxygenated haemoglobins from carp, rainbow trout, spiny dogfish and pig are reported, and compared with Hb-H+ equilibria in other species and structural information deduced from amino acid sequences. The buffer values of oxygenated and deoxygenated teleost haemoglobins are low in comparison with elasmobranch and mammalian haemoglobins. This correlates with a much lower content of histidine residues and α-amino groups in teleost haemoglobins, than that in elasmobranch, dipnoan, amphibian, reptilian, avian and mammalian haemoglobins. The low total histidine content in teleost haemoglobins is paralleled by a reduced number of titratable histidine residues compared with that in mammals. An inverse relationship is observed between the magnitude of buffer values and the magnitude of fixed-acid Haldane effects. The largest Haldane effect and smallest buffer values are seen in carp, followed by trout, whereas the smallest Haldane effect and largest buffer values are seen in dogfish. The H+ equilibria of pig haemoglobin are intermediate between those of teleost and elasmobranch haemoglobins.
Oxidative Properties of Carp Red and White Muscle
Authors: Moyes C. D. , Buck L. T. , Hochachka P. W. , Suarez R. K. 
Published: April 2021

ABSTRACT
Substrate preferences of isolated mitochondria and maximal enzyme activities were used to assess the oxidative capacities of red muscle (RM) and white muscle (WM) of carp (Cyprinus carpio). A 14-fold higher activity of citrate synthase (CS) in RM reflects the higher mitochondrial density in this tissue. RM mitochondria oxidize pyruvate and fatty acyl carnitines (8:0, 12:0, 16:0) at similarly high rates. WM mitochondria oxidize these fatty acyl carnitines at 35–70% the rate of pyruvate, depending on chain length. WM has only half the carnitine palmitoyl transferase/CS ratio of RM, but similar ratios of beta-hydroxyacyl CoA dehydro-genase/CS. Ketone bodies are poor substrates for mitochondria from both tissues. In both tissues mitochondrial alpha-glycerophosphate oxidation was minimal, and alpha-glycerophosphate dehydrogenase was present at low activities, suggesting the alpha-glycerophosphate shuttle is of minor significance in maintaining cytosolic redox balance in either tissue. The mitochondrial oxidation rates of other substrates relative to pyruvate are as follows: alpha-ketoglutarate 90% (RM and WM); glutamate 45% (WM) and 70% (RM); proline 20% (WM) and 45% (RM). Oxidation of neutral amino acids (serine, glycine, alanine, beta-alanine) was not consistently detectable. These data suggest that RM and WM differ in mitochondrial properties as well as mitochondrial abundance. Whereas RM mitochondria appear to be able to utilize a wide range of metabolic fuels (fatty acids, pyruvate, amino acids but not ketone bodies), WM mitochondria appear to be specialized to use pyruvate.
New Growth Elicited in Adult Leech Mechanosensory Neurones by Peripheral Axon Damage
Authors: Bannatyne B. A. , Blackshaw S. E. , Mcgregor M. 
Published: April 2021

ABSTRACT
New growth in cutaneous mechanosensory neurones elicited by axotomy or axon crush was studied using intracellular injection of horseradish peroxidase at different times after the lesion, ranging from a few days to over a year. Cutting or crushing major, large-calibre axon branches of mechanosensory neurones elicits sprouting of new processes, either centrally within the ganglion neuropile or at the site of the lesion in the peripheral nerve. In contrast, cutting or crushing fine-calibre axon branches supplying accessory parts of the receptive field does not elicit sprouting of the main arbor or main axon branches. Different modalities of mechanosensory neurone respond differently to lesions of their axons. Cutting the axons of high-threshold units responding to noxious stimulation of the skin elicits sprouting of additional processes from the axon hillock region within the central nervous system (CNS), whereas cutting or crushing the axons of low-threshold cells responding to light touch of the skin elicits sprouting at the site of the lesion only, and not within the CNS. In addition to the new growth directed into the peripheral nerve, damaged nociceptive neurones also form new processes that wrap the somata of particular cells within the ganglion. Sprouted processes of axotomized neurones are retained for long periods after the lesion (up to 425 days). The electrical properties of touch and nociceptive cells were studied between 1 and 60 days after axotomy, by intracellular recording from the centrally located cell bodies. The amplitude, width and maximum dV/dt of the action potential and after-hyperpolarization, as well as the resting potential and input resistance, did not change significantly after axotomy, despite the considerable process sprouting known to occur during this time.
Neuromotor Bases of the Escape Behaviour of Nassa Mutabilis
Authors: Lemmnitz G. , Schuppe H. , Wolff H. G. 
Published: April 2021

ABSTRACT
The complex sequence of movements in the escape behaviour of the snail Nassa mutabilis (L.) was described in detail and the neuromotor activity underlying the behaviour was investigated by extra- and intracellular recording. The escape reaction is triggered by a chemical stimulus to the animal ‘s foot, in these experiments either application of KC1 solution or contact with a starfish. It consists of a preliminary phase in which the shell tilts to its side, the actual locomotor phase, and a final righting movement. The snail performs leaps, in which the foot and the shell are repeatedly rotated with respect to one another. EMGs recorded from the columellar muscle during the escape reaction showed that bursts of potentials are coupled to the shell rotations. In the intact animal this burst activity ordinarily began 0 ·6 ± 0 ·3 s after stimulation with KC1. In an animal dissected for recording from the columellar nerve (which supplies the columellar muscle), KC1 stimulation of the dorsum of the foot induced burstlike neuronal activity with a latency of 0 ·5 ± 0 ·3 s. The dorsal foot region, the site at which the escape reaction can be triggered, was found to be supplied by the posterior pedal nerves; electrical stimulation of these nerves elicited bursts in the columellar nerve. The left pleural ganglion, which is known to contain neurones that project into the columellar nerve, was also found to contain neurones responsive to KC1 stimulation of the foot. These findings suggest that the left pleural ganglion contains a motor centre which is involved in control of activity of the columellar nerve, and is also active during the escape reaction.
A Note On The Diffusion of Water Across Oil And Wax Layers and Insect Cuticles
Authors: Croghan P. C. , Noble-Nesbitt J. 
Published: April 2021

ABSTRACT
The terms diffusion and permeability are frequently confused and misused. For example, Barrer (1941) in the preface of his book defines permeability constant in contradictory ways in successive sentences and both are incorrect. In the case of diffusion of gases and water, confusing systems of units have been employed. Taylor et al. (1936) define a coefficient as g/hr/cm/mmHg and Barrer (1941) uses cc(vapour at N.T.P.)/sec/cm2/cmHg/mm thick. The use of more than one solidus leads to ambiguity and may, for example, disguise that the thickness term is in the numerator and Machin (1980) does, indeed, manage to invert this term. Other errors can also easily occur. Thus Beament (1958) writes mmHg when cmHg is intended and this is repeated by Machin (1980). Also Machin & Lampert (1987) use both the coefficients mg h−1 cm−2 torr−1 and cms−1 without relating them.
Intracellular Buffering by Dipeptides at High and Low Temperature in the Blue Crab Callinectes Sapidus
Authors: Cameron James N. 
Published: April 2021

ABSTRACT
Intracellular buffering is provided mainly by bicarbonate, phosphates and proteins (see Burton, 1978). A part may also be played by free histidine and small peptides containing histidine. Although the free histidine content of most animal tissues is low, a variety have been found to possess substantial amounts of histidine-containing dipeptides, most commonly N-β-alanyl-L-histidine, either without substitutions (carnosine) or methylated at the 1-position (anserine) or at the 3-position (ophidine or balenine). At 25°C the pK of carnosine is 6·83 whereas that of anserine is 7·04, so the combination of appropriate pK and high concentration leads to significant intracellular buffer action.
Effects of Temperature on Gas Exchange and Acid-Base Balance in the Sea Turtle Caretta Caretta at Rest and During Routine Activity
Authors: Lutz Peter L. , Bergey Ann , Bergey Michael 
Published: April 2021

ABSTRACT
Oxygen consumption, lung ventilation, plasma ion concentrations and osmolality, venous blood acid-base status and gas tensions were measured in unrestrained loggerhead sea turtles in sea water at 10, 15, 20 and 30 °C at rest and during routine activity. Moderate activity caused a threefold increase in oxygen consumption, accommodated by a twofold increase in ventilation (the result of increases in breathing frequency) and a 60% increase in lung oxygen extraction. There was an increase in oxygen consumption with temperature (Q10 = 2·4) also due primarily to an increase in oxygen extraction (decline in air convection requirement, ACR) since neither the tidal volume nor the breathing frequency changed.
Over the temperature range 15–30°C venous blood pH decreased by 0·017 units °C−1, indicating that the maintenance of constant relative alkalinity is not confined to species of low aerobic scope. Venous blood and increased with temperature. However, [HCO3−] decreased, suggesting that ventilatory adjustments alone are insufficient for regulating the thermally dependent shifts in blood pH. Plasma [K+] increased with temperature, which may be related to cellular-mediated adjustments in blood pH.
Temperature-related adjustments of blood pH in the loggerhead appear to be managed both at the lung (ACR-driven changes in blood ) and tissue (ion exchange) levels. This mixed regulation is associated with the unique mode of respiration of the sea turtle.
The Volume of Air Within the Swimbladder and Breathing Cavities of the Anabantoid Fish Colisa Laua (Perciformes, Belonthdae)
Authors: Schuster Stefan 
Published: April 2021

ABSTRACT
The swimbladder volume and air volume within the breathing chambers of the anabantoid fish Colisa lalia have been measured. These data help in the understanding of some of the functions of these organs and are necessary for an analysis of their role in hearing and sound production. By means of a simple trick (based on new data) it was possible to analyse the time course of air volume changes in the breathing chambers at different temperatures. The results are well described by a simple diffusion model. The temperature-dependence of the time course suggests an interesting increase of the diffusion constant with temperature.
Under constant conditions the chambers were always filled with about the same volume of air. No excess pressure was found. Typical values of a single chamber’s air content range from 34 to 58 μl. Air content increases with about the third power of fish length. By using the present data, the time course of air volume changes in the chambers of a given fish can be estimated.
Swimbladder volumes, determined using Boyle’s law, ranged from 70 to 220 μ1 and were also found to increase with about the third power of fish length, in accordance with a simple estimation.
The data are discussed in relation to buoyancy, diffusion processes, blood circulation, hearing and sound production and suggest some interesting new work.
Coupling Mechanisms Between the Contralateral Legs of a Walking Insect (Carausius Morosus)
Authors: Cruse H. , Knauth A. 
Published: April 2021

ABSTRACT
Interactions between contralateral legs of stick insects during walking were examined in the absence of mechanical coupling between the legs by studying animals walking on a horizontal plane covered with a thin film of silicone oil. Investigations of undisturbed walks showed that contralateral coupling is weaker than ipsilateral coupling. Two types of influence were found, (i) For each pair of front, middle and rear legs, when one leg started a retraction movement, the probability for the contralateral leg to start a protraction was increased, (ii) For front- and hind-leg pairs, it was found that the probability of starting a protraction in one leg was also increased, the farther the other leg was moved backwards during retraction. Whether such influences exist between middle legs could not be determined. Both ‘excitatory’ mechanisms very much resemble those influences which have been found to exist between ipsilateral legs. However, in contrast to ipsilateral legs, the interaction between two contralateral legs was found to act in both directions.