bluuebunny/crossref_metadata_2025 huggingface dataset:
Suprarenal “Virilism” in A Domestic Hen, Its Possible Significance
Authors: Mcgowan J. P.
Published: April 2021

The great majority of hermaphrodites or sex reversals, hitherto described in domestic fowls, have been in old hens and have usually been associated with disease of the ovary and neoformation of testicular tissue. The present case differs essentially in several respects.
Reflex and Rhythmical Movements in the Dogfish
Authors: Le Mare D. W.
Published: April 2021

The active part played by the two dorsal and anal median fins, and the passive part played by the caudal fin in the normal swimming of Scylliorhinus are emphasised. It is pointed out that when the nerve cord of Scylliorhinus is transected at any level, that part of the trunk below the level of transection produces rhythmical swimming movements. This is interesting when compared with certain teleosts, in which rhythmical swimming movements are only produced when the transection of the cord is at the anterior end of the medulla. In these teleosts the neurons controlling swimming are probably confined to the medulla, while in the dogfish they are dispersed throughout the length of the cord, representing a more primitive condition. The movements are accentuated during and after mechanical stimulation, the tip of the caudal fin and the ventral region near the cloaca being the most sensitive regions. Mechanical stimulation of certain regions produces well-defined reflexes of the body which are superimposed upon the rhythmical swimming movements. These distortions of the normal swimming movements thus produced are interpreted as foreshadowing the more marked, typical reflexes seen in the teleosts. The swimming movements may be inhibited by holding either of the dorsal fins. On release of the inhibitory stimulus, a post-inhibitory rebound in the swimming movements of the fish occurs. A regular secondary periodic rhythm superimposed upon the normal swimming rhythm of the fish is described. On supplying the dogfish with the nerve cord transected at the anterior end of the medulla with extra carbon dioxide, or stopping the oxygen supply, the Cheyne-Stokes rhythm, which is typical of respiration in mammals under abnormal conditions of oxygen and carbon dioxide supply, was found to take the place of the normal swimming rhythm. In spinal fish no such change was recorded. Consequently it is concluded that the neurons in the medulla which control the respiratory movements in some way also influence those responsible for the trunk musculature, so that this typical respiratory rhythm was translated into the swimming rhythm.
Observations on Pigmentary Co-Ordination in Elasmobranchs
Authors: Wykes Ursula
Published: April 2021

Section of the spinal nerves to the pectoral fins in Raia brachyura, R. maculata and Scyllium canicula had no effect on the state of the chromatophores in the black adapted fish, nor did it prevent the development of uniform pallor on a white ground. Electrical stimulation of (a) spinal nerves to the pectoral fins, (b) the haemal canal, (c) the skin, in Raia brachyura, Rhina squatina and Scyllium catulus did not result in any chromatophore changes. Excised skin of Raia brachyura, R. mandata, Rhina squatina and Scyllium canicula placed in adrenaline chloride solution showed little or no change in melanophore index during one hour and could not be differentiated from control pieces placed in elasmobranch Ringer. The injection of adrenaline chloride caused a slight paling in Raia brachyura and Rhina squatina. This may be a secondary effect due to the vaso-constrictor action of this hormone. White adapted specimens of Raia brachyura, which were placed on a black ground after ligature of the dorsal aorta, became dark anterior to the point of ligature within 3 hours. The posterior region was still completely pale at this time and did not become fully dark for 24 hours.
Electrophysiological Properties of Crayfish Retinal Photoreceptors
Authors: Picones Arturo , Aréchiga Hugo
Published: April 2021

Electrical properties of crayfish retinular photoreceptors were studied in the dark-adapted state and during responses to light. In fully dark-adapted photoreceptors, the resting potential was −49.8±3.3 mV and input resistance was 31.3±5.4MΩ (mean±S.E.). The current-voltage relationship showed rectification near the resting potential, with decreased resistance within the depolarizing range. A value of 29.8±5.0kΩcm2 was calculated for specific resistance, and 3.0±0.4 μFcm−2 for specific capacitance. Electrotonic analysis showed that the photoreceptor was isopotential.

During the light response, membrane conductance increased depending on the stimulus intensity. This relationship was steeper for the conductance change during the initial transient of the receptor potential than during the plateau. A depolarizing afterpotential usually ensued at the end of the light response, concurrent with a residual increased conductance. The time course of the conductance increase during the receptor potential showed two kinetic components, suggesting that at least two distinct membrane processes were involved in its generation.
Predicting Wingbeat Frequency and Wavelength of Birds
Authors: Pennycuick C. J.
Published: April 2021

Wingbeat frequencies were observed in the field for 32 morphologically diverse bird species, representing 18 families, and ranging in mass from 20 g to nearly 5 kg. A combination of multiple regression and dimensional analysis was used to show that wingbeat frequency (f) may be estimated by: where m is the bird’s body mass, g is the acceleration due to gravity, b is the wing span, S is the wing area and ρ is the air density. The predicted wingbeat frequency can be used to estimate the power available from a bird’s flight muscles, and an estimate of the power required to fly can be obtained for comparison from the computer programs of Pennycuick (1989a). Field observations of airspeed are given for 30 of the 32 species. These are combined with the observations of wingbeat frequency to estimate wingbeat wavelength, and the ratio of wavelength to wing span, which is closely related to the ‘advance ratio’ as used by Ellington (1984).
Reversible Alkalinization by Manduca Sexta Midgut
Authors: Dow Julian A. T. , O’Donnell Michael J.
Published: April 2021

Midguts of the larva of the tobacco hornworm larva, Manduca sexta, were isolated, pinned out and double perfused on the stage of an inverted microscope. The pH gradients across the anterior, middle and posterior regions of the gut were measured with a double-barrelled pH microelectrode, simultaneously with electrical potentials and the transepithelial potential difference (TEP). The microenvironment surrounding the apical surface is more alkaline, and that surrounding the basal surface more acid, than either the perfusion medium or the intracellular pH. Under double perfusion, a stable gradient of 1.4 pH units is observed across the middle midgut. A similar gradient is found across the anterior midgut, but no significant pH difference occurs across the posterior midgut. The pH gradient across the middle midgut is reversibly and symmetrically collapsed by anoxia, implying that it is sustained by a process requiring oxidative phosphorylation. The time course of decay and reconstitution of the pH gradient matches closely the activity of electrogenic K+ pumping, as measured by the TEP. These results are consistent with a model for high pH generation which links electrogenic K+ transport into the goblet cavities with net alkalinization of the lumen of the anterior and middle midgut regions.
Long-term anoxia in crucian carp: changes in the levels of amino acid and monoamine neurotransmitters in the brain, catecholamines in chromaffin tissue, and liver glycogen
Authors: Nilsson G. E.
Published: April 2021

Crucian carp (Carassius carassius L.), which are extremely anoxia-tolerant, were exposed to 17 days of anoxia at 8 °C. One group of fish was transferred to normoxic water for 1–8 h immediately after the anoxic period.

All the eight amino acids measured in brain (including four putative neurotransmitters) were more or less strongly affected by anoxia. Gamma-aminobutyric acid (GABA) displayed a nearly fivefold increase during anoxia. It is hypothesized that the increased level of this inhibitory transmitter, maybe in combination with the decrease seen in excitatory amino acids (glutamate and aspartate), causes a lowered brain activity and, hence, is a key factor behind the decrease in physical activity and systemic energy metabolism seen in anoxic Carassius.

The brain levels of serotonin, dopamine and norepinephrine were remarkably well preserved after anoxia (although their synthesis is oxygen-dependent), suggesting adaptive mechanisms. However, anoxia reduced the norepinephrine level in kidney (chromaffin tissue) by 92 % and, in contrast to previous results on shorter anoxic periods (3–7 days), the peripheral catecholamine store showed little sign of recovery during the subsequent normoxia.

Anoxia was found to deplete the liver glycogen store severely, and the few fish that died after 15–17 days of anoxia contained no detectable liver glycogen.
Effects of Bicarbonate on Salt and Water Transport Across the Intestine of the Seawater EEL
Authors: Ando Masaaki
Published: April 2021

To elucidate whether the Na+/K+/Cl− cotransport system depends on HCO3− in the seawater eel intestine, the effects of HCO3− on the transepithelial potential difference (PD) and on net water and ion fluxes were examined. When HCO3− buffer was replaced with phosphate buffer, the serosa-negative PD and net Na+, Cl− and water fluxes from mucosa to serosa were inhibited, indicating that the Na+/K+/Cl− cotransport system is inhibited in phosphate-buffered solutions. Similar inhibitory effects were also observed in solutions buffered with Hepes, Tris or Tes, indicating that the inhibitory effects are not specific for the phosphate buffer but are caused by omission of the HCO3− buffer system. Although the HCO3− buffer system consists of HCO3− and CO2, higher CO2 pressure with constant HCO3− concentration did not enhance, but inhibited, the PD and the net water flux: this indicates that the inhibition observed after removal of the HCO3− buffer system is due to omission of HCO3− rather than CO2. The inhibition of PD and the net water flux was greater after removal of HCO3− from the serosal side than from the mucosal side. Similarly, the inhibitory effects of 4, ′ -diisothio-cyanostilbene-2,2′-disulphonic acid (DIDS), an inhibitor of HCO3− transport, were more pronounced on the serosal side than on the mucosal side. Mucosal Ba2+ also inhibited PD and the short-circuit current (Isc) and enhanced the tissue resistance (Rt), presumably through partially blocking the apical K+ channels. However, these effects of Ba2+ were completely abolished after pretreatment with serosal DIDS, suggesting that Ba2+ and DIDS evoked the same effect. These results are combined and a possible role for HCO3− in the Na+/K+/Cl− co transport system is discussed.
Potassium and Rubidium Uptake in Freshwater Bivalves
Authors: Dietz T. H. , Byrne R. A.
Published: April 2021

Potassium transport characteristics were investigated in three species of freshwater bivalves: a corbiculid, Corbiculafluminea, and two unionids, Carunculina texasensis and Ligumia subrostrata. Using 42K, all three were found to take up potassium from dilute artificial pondwater ([K+] about 0.05 mmol l−1). The influx (Ji) was 0.72 μequivg−1 dry tissue h−1 in the corbiculid, significantly higher than the value of about 0.40/zequivg−1 dry tissueh−1 in the unionids. The K+ uptake displayed saturation kinetics in the range 0.05–0.36 mmol l−1: in Co. fluminea, there was a Jmax of 3.56 μequivg−1 dry tissueh−1 and the affinity coefficient (Km) was 0.27 mmol l−1; in Ca. texasensis, Jmax had a value of 1.8 μequivg−1 dry tissueh−1 and Km was 0.16 mmol l−1. Using K+-free artificial pondwater containing 0.03–0.04 mmol l−1 Rb+, the Rb+ influx was 0.41μequivg−1 dry tissueh−1 in the corbiculid and 0.28μequivg−1 dry tissueh−1 in Ca. texasensis. All animals lost K+ during the rubidium flux studies, and since they contained no Rb+, the Rb+ efflux was zero and the net flux was equal to the influx. The Jmax values for Rb+ were lower than the corresponding values for potassium: in Co. fluminea, Jmax was 1.4 μequivg−1 dry tissueh−1, significantly higher than in Ca. texasensis, which had a Jmax of 0.84 μequivg−1 dry tissueh−1. The rubidium Km (approx. 0.05 mmol l−1) values were significantly lower than corresponding values for potassium. Salt depletion increased the rubidium transport rate fourfold for both Co. fluminea and Ca. texasensis. High rates of net K+ uptake may account for the bivalves’ inability to tolerate elevated environmental potassium.
The Spleen in Hypoxic and Exercised Rainbow Trout
Authors: Wells R. M. G. , Weber R. E.
Published: April 2021

The teleost spleen is a discrete organ containing, in addition to erythrocytes sequestered from the circulation, erythropoietic tissue involved in the synthesis of new erythrocytes. In this division into supply and synthesis, there appear to be some species differences. The eel spleen is an erythrocyte reservoir but is not thought to be a major erythropoietic organ (Johansson-Sjobeck, 1979). The splenic mass in goldfish does not change with induced anaemia (Houston et al. 1988). The trout spleen, in contrast, plays an erythropoietic role during anaemia (Lane, 1979), in addition to serving as a store of erythrocytes (Randall and Daxboeck, 1982). Exercise in trout is accompanied by haemoconcentration (Black et al. 1966; Stevens, 1968) and the spleen appears to contribute to elevated circulating haemoglobin levels (Stevens, 1968). Capture stress induced a 25% reduction in spleen haemoglobin concentration, [Hb], in the marine teleost Girella tricuspidata, and splenic histology revealed melano-macrophagic centres and erythropoietic tissue indicative of a major role in erythrocyte destruction and synthesis (Ling, 1984). Neither role can be played by the spleen of the icefish, which lacks haemoglobin (Wells et al. 1990).
The Intracellular pH of a Molluscan Smooth Muscle During a Contraction–Catch-Relaxation Cycle Estimated by the Distribution of [14C]DMO and by 31P-NMR Spectroscopy
Authors: Zange J. , Pörtner H. O. , Jans A. W. H. , Grieshaber M. K.
Published: April 2021

The intracellular pH (pHi) of the anterior byssus retractor muscle (ABRM) of Mytilus edulis L. was estimated during rest and during a contraction-catch-relaxation cycle by the distribution of [14C]DMO and by 31P-NMR spectroscopy. The pHi of resting muscles was found to be nearly the same whether it was determined with DMO (7.41±0.06, N=51) or by 31P-NMR spectroscopy (7.44±0.02, N=5). During catch the pHi was not significantly different from its value at rest. Serotonin (10−5moll−1) induced a rapid relaxation and a significant increase in pHi (DMO: 7.56±0.05, N=11; 31P-NMR: 7.57±0.02, N=5). In resting ABRM serotonin (⩾10−6moll−1) also induced an alkalosis. It was shown that cyclic AMP, the second messenger of serotonin, elicited an increase of pHi. Dopamine (10−5moll−1) did not cause an increase in either cyclic AMP levels or pHi. The rates by which tonically contracted ABRM loaded at 0.1 N were stretched were significantly increased by an alkalosis elicited by the addition of 10 or 20 mmol l−1 methylamine. Acidosis elicited by 10 mmol l−1 DMO caused a significant decrease in the rate of relaxation.
The Regulation of Intracellular pH Estimated By 31P-Nmr Spectroscopy in the Anterior Byssus Retractor Muscle ofMytilus EdulisL
Authors: Zange J. , Grieshaber M. K. , Jans A. W. H.
Published: April 2021

The regulation of the intracellular pH (pHi) in the anterior byssus retractor muscle (ABRM) of Mytilus edulis L. during an acidic and alkaline load was studied by 31P-NMR spectroscopy. Under aerobic conditions, a total intracellular buffer capacity of 26.5±0.7mmol l−1 pH unit−1 (N=3) was estimated. In the absence of serotonin, active acid extrusion was by a Na+-independent, primary active transport mechanism coupled to anion transport. Base equivalents appear to be extruded by a C1−/HCO3− exchanger. Serotonin (10−5 moll−1) induced an increase in pHi through additional activation of a Na+/H+ exchanger.
Ultrasound-triggered, flight-gated evasive maneuvers in the praying mantisParasphendale agrioninaI. Free flight
Authors: Yager David D. , May Michael L. , Fenton M. Brock
Published: April 2021

Free-flying male praying mantises Parasphendale agrionina (Gerst.) perform evasive maneuvers when stimulated by ultrasound and when attacked by hunting, echolocating bats. They do not, however, respond in any way when standing on a substratum. The maneuvers are graded in intensity with distance from the sound source: far from the source they are simple turns, whereas close to the source they are steep diving turns or spirals. The maneuvers are made under power, and the male’s velocity doubles to almost 4 ms−1 by the end of a steep dive. The mantis does not show any directional preference. The behavioral threshold of 64 dB SPL and minimum latency to course change of 125 ms indicate that these mantises should have adequate time to evade bats using calls of greater than 85-90 dB SPL (at 10 cm). In field experiments.with wild, hunting bats, P. agrionina successfully evaded capture in all five attacks to which they responded with evasive maneuvers. Out of three attacks on P. agrionina and three on a normally non-responding mantis, Miomantis paykullii Stål, in which there were no evasive maneuvers, the mantis was captured in five cases.
The Mechanism by Which Aphids Adhere to Smooth Surfaces
Authors: Dixon A. F. G. , Croghan P. C. , Gowing R. P.
Published: April 2021

The adhesive force acting between the adhesive organs and substratum for a number of aphid species has been studied. In the case of Aphis fabae, the force per foot is about 10 μN. This is much the same on both glass (amphiphilic) and silanized glass (hydrophobic) surfaces. The adhesive force is about 20 times greater than the gravitational force tending to detach each foot of an inverted aphid. The mechanism of adhesion was considered. Direct van der Waals forces and viscous force were shown to be trivial and electrostatic force and muscular force were shown to be improbable. An adhesive force resulting from surface tension at an air-fluid interface was shown to be adequate and likely. Evidence was collected that the working fluid of the adhesive organ has the properties of a dilute aqueous solution of a surfactant. There is a considerable reserve of fluid, presumably in the cuticle of the adhesive organ.
Effect of activity on performance and morphology in ischaemic rat slow muscles
Authors: Corsi A. , Granata A. L. , Hudlicka O.
Published: April 2021

Muscle performance and structure was studied in rat soleus muscle with limited blood supply in combination with chronic muscle stimulation. Blood supply to the lower leg was restricted by ligation of the common iliac artery, electrodes were implanted in the vicinity of the sciatic nerve and ankle flexors were denervated. Three days later, soleus and gastrocnemius muscles were stimulated at 4 Hz four times a day for a period of 20 min with 2h intervals between stimulations; this procedure was continued for 4 days. Muscle performance, histochemistry and ultrastructure were studied on the eighth day after operation in these muscles and in ischaemic unstimulated muscles with denervated ankle flexors. Both were compared with control animals. Muscles with limited blood supply developed less isometric twitch tension than control muscles (peak twitch tension in ischaemic muscle was 60.3±4.8 g g−1 muscle, mean±s.E.M., compared to 79.7±6.9gg−1 in control muscle; tensions after 5min contraction were 54.5±5.5gg−1in ischaemic muscle compared to 70.6±6gg−1 in controls). Stimulated muscles with limited blood supply had higher peak (85±16.6gg−1) and final (87±12gg−1) tensions, and also fatigued less than muscles with limited blood supply but no stimulation. Histochemical estimation of capillary density (by staining for alkaline phosphatase) and slow (SO) and fast (FOG) fibres (by myosin ATPase staining) revealed similar capillary to fibre ratios (2.5) and a similar proportion of FOG fibres (around 18%) in all muscles. The proportion of glycogen-depleted fibres (estimated from the periodic acid Schiff reaction, PAS) in muscles removed from animals 10 min after a 5 min period of isometric twitches was significantly lower in ischaemic muscles (45.1±1.9%) than in control (80.5±1.5%) or chronically stimulated ischaemic muscles (67.3±4.0 %). Electron microscopy showed disorganised myofibrils with Z-line streaming in 7.48±3.04% of fibres in muscles with limited blood supply. Swollen and degenerated mitochondria, dilated sarcoplasmic reticulum and areas of disrupted sarcolemma were also observed. Stimulated ligated muscles showed a significantly lower proportion of fibres with disorganised filaments (0.65±0.32 %) and other signs of damage were much less frequent. The reduced damage and improved performance of chronically stimulated slow muscle may be the result of improved microcirculation, preventing accumulation of lactate.
Involvement of cyclic AMP in multiple, excitatory actions of biogenic amines on the cardiac ganglion of the horseshoe crabLimulus polyphemus
Authors: Groome J. R. , Watson W. H.
Published: April 2021

Cyclic AMP appears to be involved in several excitatory actions of amines on neurones of the Limulus cardiac ganglion. Amines selectively increase levels of cardiac ganglion cyclic AMP with a magnitude and time course similar to that observed for amine-induced excitation of cardiac ganglion burst rate. With respect to either the physiological or biochemical effect, the apparent order of potency is octopamine>epinephrine≈dopamine>norepinephrine. Elevation of cardiac ganglion cyclic AMP levels by octopamine or dopamine is dose-dependent and is potentiated by the phosphodiesterase inhibitor 3-isobutyl 1-methylxanthine (IBMX).

Several pharmacological agents which influence cyclic nucleotide metabolism, including forskolin, IBMX and 8-substituted cyclic AMP analogues, have amine-like effects on the Limulus cardiac ganglion. These effects include increased burst rate of the isolated cardiac ganglion and decreased burst duration, interburst interval and number of spikes per burst in follower neurones. Forskolin and IBMX increase levels of cardiac ganglion cyclic AMP, and IBMX also increases cyclic GMP levels in this tissue.

Amines, forskolin and IBMX have direct effects on follower neurones pharmacologically isolated from pacemaker cell input. Octopamine, forskolin and IBMX depolarize follower neurones, while dopamine hyperpolarizes these cells. Amines, forskolin and IBMX elicit burst-like potentials in follower neurones, and increase the size of evoked, unitary junction potentials recorded in cardiac muscle fibres. These pharmacological and biochemical data suggest that multiple, excitatory effects of biogenic amines on the Limulus cardiac ganglion are mediated by simultaneous increases in cyclic AMP at several loci within this neural network.
Effects of Catecholamines on Gas Exchange and Ventilation in Rainbow Trout (Salmo Gairdneri)
Authors: Playle Richard C. , Munger R. Stephen , Wood Chris M.
Published: April 2021

A transient inhibitory effect of catecholamines on relative CO2 excretion, mediated by an inhibition of HCO3− dehydration through the red blood cell (RBC), has been proposed to cause the increase in routinely observed after strenuous exercise in fish (‘CO2 retention hypothesis’, Wood and Perry, 1985). To evaluate this idea, trout fitted with arterial cannulae, oral membranes and opercular catheters were placed in ventilation chambers. , RBC intracellular pH (pHi) and other blood acid-base parameters were monitored from the arterial cannulae. The ventilation chamber system allowed continuous, almost instantaneous, measurements of water ΔO2 and ΔCO2 across the gills, and therefore of respiratory exchange ratio (RE), as well as Δammonia, mean expired pH and ventilation volume . Physiological doses of adrenaline and noradrenaline (3.2 nmol kg−1), designed to duplicate typical post-exercise concentrations, together with appropriate saline controls, were injected into resting fish. Adrenaline caused an immediate hypoventilation, while the response to noradrenaline was biphasic: hyperventilation followed by hypoventilation. With both drugs, ΔO2 and ΔCO2 increased, but RE remained constant (adrenaline) or increased (noradrenaline). There was no evidence of a specific inhibition of CO2 excretion, nor was there any increase in ; changes in RBC pHi were small (noradrenaline) or non-existent (adrenaline). These results confirm those of Steffensen el al. (1987) and do not support the CO2 retention hypothesis. However, the RBCs of resting trout may be relatively insensitive to catecholamines at normal arterial blood pH (pHa).
Transient behavior of sea urchin sperm flagella following an abrupt change in beat frequency
Authors: Eshel Dan , Shingyoji Chikako , Yoshimura Kenjiro , Gibbons Barbara H. , Gibbons Ian R. , Takahashi Keiichi
Published: April 2021

Within the approximate range of 30–80 Hz, the flagellar beat frequency of a sea urchin sperm held by its head in the tip of a micropipet is governed by the vibration frequency of the micropipet. We have imposed abrupt changes in flagellar beat frequency by changing the vibration frequency of the micropipet within this range and used a high-speed video system to analyze the flagellar wave parameters during the first few cycles following the change. Our results demonstrate that the various flagellar beat parameters differ in the time they take to adjust to the new conditions. The initiation rate of new bends at the base is directly governed by the frequency of the vibration and changes immediately to the new frequency. The length and the propagation velocity of the developed bends become adjusted to the new conditions within approximately 1 beat cycle, whereas the bend angles take more than 4 beat cycles to attain their new steady-state value. Bends initiated shortly before the change in frequency occurs attain a final length and angle that depends on the relative durations of growth at the old and new frequencies. Our results suggest that the flagellar wavelength and bend angle are regulated by different mechanisms with the second not being directly dependent on bend initiation.
Na+ and Cl− Uptake Kinetics, Diffusive Effluxes and Acidic Equivalent Fluxes Across the Gills of Rainbow Trout II. Responses to Bicarbonate Infusion
Authors: Goss Greg G. , Wood Chris M.
Published: April 2021

Adult rainbow trout fitted with arterial and bladder catheters were chronically infused with either bicarbonate (as NaHCO3) or NaCl for 19 h at approximately 410μequivkg−1h−1. NaHCO3 infusion produced a pure exogenous metabolic alkalosis of approximately 0.35 pH units accompanied by a decrease in plasma [Cl−] but no change in plasma [Na+]. Alkalosis stimulated Cl− influx and inhibited Na+ influx (measured at 10-16h infusion), resulting in a negative Na+ balance, a positive Cl− balance and a large net basic equivalent excretion (=acidic equivalent uptake) across the gills. The latter was approximately equal to the rate of HCO3−loading. The kidney accounted for approximately 13 % of the acid-base compensation.

Kinetic analysis revealed that reductions in were accomplished by increases in (463μuquivl−1; NaHCO3-infused vs 276μequivl−1; NaCl-infused) and large decreases in (262μequivkg−1h−1 vs 689μequivkg−1 h−1) while stimulation of was accomplished by large increases in only (674 μequiv kg−1 h−1 vs 360μequivkg−1 h−1). Thus, Jmax can be increased or decreased in response to acid-base disturbance, but Km can only be increased; the Na+ and Cl− carriers operate close to maximum affinity under control conditions. Basic equivalent excretion was described by a virtually identical kinetic curve to that of the Cl− uptake. NaHCO3 infusion also induced a differential diffusive efflux of Na+ over Cl− which could account for up to 35 % of the acid-base compensation during alkalosis.
Urine Production in Octopus Vulgaris
Authors: Wells M. J. , Wells J.
Published: April 2021

In a recent paper (Wells and Wells, 1989) evidence was presented indicating that Octopus vulgaris takes up water and salts through the digestive gland appendages, the so-called ‘pancreas’. Animals with the digestive gland ducts ligated lost weight at around 11 % of the body mass per day and died after about 48 h. Animals with the ducts exteriorised, leaving a sufficient length to perform peristalsis, did not lose weight.
Heat Dissipation, Gas Exchange and Acid-Base Status in the Land SnailOreoheuxDuring Short-Term Estivation
Authors: Rees Bernard B. , Hand Steven C.
Published: April 2021

Within 4 days following entry into estivation, heat dissipation and oxygen consumption by the land snail Oreohelix spp. decreased by 83% compared to standard non-estivating rates. During both non-estivating and estivating conditions, the quantity of heat dissipated per mole of O2 consumed was indicative of a completely aerobic metabolism. This calorimetric-respirometric (C/R) ratio was –461 ±12 kJ mol−1O2 (S.E.M., N=5) under standard non-estivating conditions and –464±26kJmol−1O2 (N=4) during estivation. Respiratory exchange ratios reflected a primary dependence upon carbohydrate as a metabolic substrate during both states. Carbon dioxide retention occurred during the first 36h of estivation, resulting in an increase in hemolymph and a decrease in pH. The respiratory acidosis during short-term estivation was not compensated by elevation of hemolymph [HCO3−] above levels predicted from the in vitro non-bicarbonate buffer value of hemolymph. A brief period of rapid CO2 release, which caused hemolymph and pH to return to pre-estivation values, preceded the increase in O2 consumption during arousal. Exposure of nonestivating snails to 4.67 kPa (1 kPa=7.5mmHg) caused a rapid and fully reversible 50% suppression of respiration rate. The temporal nature of CO2 retention and release during entry into and arousal from estivation, and the suppression of O2 consumption by artificial hypercapnia, support the hypothesis that elevated or the resultant acidosis may contribute to metabolic suppression during estivation by land snails.
Effects of Combined Abdominal and Thoracic Airsac Occlusion on Respiration in Domestic Fowl
Authors: Brackenbury John , Amaku Jane
Published: April 2021

Ventilation and respiratory and blood gas tensions were monitored at rest and during running exercise, following bilateral occlusion of the cranial and caudal thoracic and the abdominal air sacs. This represents a removal of approximately 70% of the total air-sac capacity. At rest, the birds were strongly hypoxaemic/ hypercapnaemic. Ventilation was maintained at its control value but respiratory frequency was significantly increased and tidal volume diminished. The birds were capable of sustained running at approximately three times the pre-exercise metabolic rate. Minute ventilation during exercise was the same as that of the controls, but breathing was faster and shallower. Exercise had no effect on blood gas tensions in either the control or the experimental birds. There was no evidence of a detrimental effect of air-sac occlusion on the effectiveness of inspiratory airflow valving in the lung: hypoxaemia appeared to be due to the altered respiratory pattern, which resulted in increased dead-space inhalation.
Control of ‘Pulmonary’ Pressure and Coordination with Gill Ventilation in the Shore CrabCarcinus Maenas
Authors: Rajashekhar K. P. , Wilkens J. L.
Published: April 2021

In the shore crab, Carcinus maenas (L.), forward ventilation creates negative pulses of hydrostatic pressure while reversed ventilation causes dramatic positive pressure fluctuations in the branchial chamber. These pressures are transmitted via the gills to the haemolymph of the open circulatory system. The branchiostegal sinus, which is a compliant chamber, may function as a reservoir for displaced haemolymph and may operate as an accessory pump driven by the action of the dorsoventral (DV) muscles. A band of dorsoventral muscles controls the volume of the branchiostegal sinuses. The muscular activity is coordinated with ventilatory activity and may assist in regulating pressure fluctuations caused by ventilatory pressure pulses. During a ventilatory reversal, the haemolymph displaced from the gills is added to the volume of haemolymph in the open circulatory system and this haemolymph may be accommodated in the branchiostegal sinus by relaxation of the DV muscles. Artificially regulating the pressure either in the branchial chamber or in the branchiostegal sinus reflexively alters DV muscle activity, which suggests the occurrence of baroreceptors in this crab. The branchiostegal nerve that innervates the DV muscles contains five neurones identified by cobalt backfills. Three of them are median and two are contralateral. The dendritic field of each neurone is confined to its respective hemiganglia. The electrical activity of one of the motoneurones in the branchiostegal nerve corresponds to the activity of the DV muscles. In vitro observations of the activity of branchiostegal motoneurones in relation to ventilatory motoneurone activity indicate that both are centrally coupled and support the hypothesis that the branchiostegal motoneurones are influenced by the ventilatory central pattern generator.
Red Pigment Concentrating Hormone is A Modulator of the Crayfish Swimmeret System
Authors: Sherff Carolyn M. , Mulloney Brian
Published: April 2021

The crustacean red pigment concentrating hormone (RPCH) has been localized in neurons of the crayfish abdominal nerve cord and modulates the crayfish swimmeret rhythm. An antibody to RPCH labels a small set of cell bodies and axons in each abdominal ganglion. Physiological experiments in which RPCH was perfused into the ganglia of isolated nerve cords showed that RPCH modulated the swimmeret rhythm. In nerve cords that were spontaneously producing the swimmeret rhythm, RPCH lengthened both the period and the duration of bursts of action potentials, but did not alter the phase relationships between bursts in different segments. RPCH did not initiate the swimmeret rhythm in preparations that showed intermittent or no bursting activity. We believe that RPCH is released as a neurotransmitter in the lateral neuropil, where it exerts its effects on the local swimmeret circuits.
The Effects of An Air/Water Surface on the Fast-Start Performance of Rainbow Trout (Oncorhynchus Mykiss)
Authors: Webb Paul W. , Sims Dominique , Schultz William W.
Published: April 2021

Fast-start performance of rainbow trout (mass 0.187±0.022kg; mean±2s.E., N=10) was measured in water of various depths. Relative water depth was defined as z/B, where z is the water depth measured from the air/water surface to the longitudinal midline of the body and B is the span of the caudal fin, 0.062±0.004m. Relative water depths (at absolute depths) tested were; 0.31 (at 0.05m), 1.11 (at 0.1m), 1.92 (at 0.15m), 2.73 (at 0.2m) and 7.56 (at 0.5m). Performance was defined in terms of the motion of the centre of mass as measured by the turning radius and the cumulative distance travelled in a given elapsed time. Turning radius was not affected by water depth and averaged 0.018±0.003m. Distance travelled was a positive function of water depth, although paired r-tests showed no significant effect of depth at 0.15 and 0.2 m after about 70 ms. Energy dispersion due to the formation of surface waves increased with decreasing relative water depth. The largest energy dispersion in wave formation at a relative water depth of 0.31 averaged about 70 % of the useful mechanical work performed in deep water. Energy dispersion in wave generation was negligible for relative water depths larger than approximately 3. Energy dispersion is similar to that for rigid streamlined bodies moving at constant speed.
Electrolyte Transport Through a Cation-Selective ion Channel in Large Intestinal Enterocytes ofXenopus Laevis
Authors: Krattenmacher R. , Voigt Rosita , Heinz M. , Clauss W.
Published: April 2021

Electrogenic ion transport through the colon epithelium of the African clawed toad (Xenopus laevis) was investigated with electrophysiological methods in vitro. Interest was focused on a previously described phenomenon, that removal of Ca2+ from the mucosal Ringer’s solution increases electrogenic sodium absorption. Our results clearly show that Ca2+ removal reveals an apical ion channel that is not a specific Na+ channel, but a non-selective cation channel with an ‘apparent’ ion selectivity of the order K+>Na+=Rb+>Cs+>Li+. This Ca2+-sensitive current increased linearly with the mucosal pH, and could be inhibited by other divalent cations (Mg2+, Ba2+) and the organic ion channel blockers quinidine and verapamil. The mucosal Ca2+ concentration that induced a half-maximal inhibition of the Ca2+-sensitive current was about 1 μmoll−1 and was independent of the mucosal pH. Owing to the high Ca2+ sensitivity, a regulation of the channel conductivity by extracellular Ca2+ is ruled out. It is concluded that this channel, which is almost identical to similar channels found in amphibian skin and bladder, acts as a pathway for cation absorbing or secreting processes. Possibly the binding of extracellular Ca2+ is related to selectivity changes of the Ca2+-sensitive ion channel.
Magnetic Orientation By Hatchling Loggerhead Sea Turtles (Caretta Caretta)
Authors: Lohmann Kenneth J.
Published: April 2021

Laboratory experiments were conducted to test the ability of loggerhead sea turtle hatchlings (Caretta caretta L.) to orient using the magnetic field of the earth. Hatchlings were tethered to a rotatable lever-arm apparatus which tracked swimming orientation in complete darkness. Hatchlings tested in the earth’s magnetic field were nonrandomly oriented with a mean angle of 42°; those tested under an earth-strength field with a reversed horizontal component were also nonrandomly oriented, but with a mean angle of 196°. The distributions under the two magnetic field conditions were significantly different, indicating that loggerhead sea turtle hatchlings can detect the magnetic field of the earth and use it as a cue in orientation.
Sodium- and Calcium-Dependent Excitability of Embryonic Leech Ganglion Cells in Culture
Authors: Schirrmacher Karin , Deitmer Joachim W.
Published: April 2021

Voltage-dependent Na+ and Ca2+ inward currents underlying the action potential in cultured embryonic ganglion cells of the leech Hirudo medicinalis have been investigated using the gigaseal whole-cell current or voltage-clamp technique. Dissociated ganglion cells were isolated from 7-to 14-day-old embryos, and maintained in primary culture for up to 5 days. More than 95 % of the cultured cells had voltage-dependent K+ currents and about 75 % of the cells had voltagedependent inward currents. Action potentials of 60mV amplitude and 4 ms duration, similar to those in embryonic nerve cells in vivo, could be recorded. Three types of inward currents occurred in these cells: (1) an initial Na+ current, which activated and inactivated rapidly; (2) a second Na+ current, which activated slowly and persisted during membrane depolarization, showing very little inactivation, and (3) a Ca2+-dependent inward current. Both types of Na+ currents were resistant to tetrodotoxin (TTX, 0.2–5 μmoll-1). The Ca2+ current was also carried by Ba2+, and was blocked by cobalt and cadmium. The fast Na+ current was first expressed in cells from 8-day-old embryos, 1 day earlier than the Ca2+ current. Between days 8 and 14 the density of the fast Na+ current increased from 22±3 to 51±6μAcm-2 (±S.D., N= 11), while the Ca2+ current grew from 10μAcm-2 (N=2) to 15±4μAcm-2 (N =10) during this time.
Glycolytic and Associated Enzymes of Rainbow Trout (Oncorhynchus Mykiss) Red Cells:In VitroAndIn VivoStudies
Authors: Ferguson Ralph A. , Storey Kenneth B.
Published: April 2021

Studies were undertaken in vitro and in vivo to assess the maximal activities of 26 glycolytic and associated enzymes of rainbow trout (Oncorhynchus mykiss) red cells. The red cells possess a complete sequence of glycolytic enzymes capable of anaerobic oxidation of glucose to lactate. Red cell pyruvate kinase (PK) was inhibited by ATP (I50 ≈ 5 mmol I 1−1), but was not sensitive to alanine inhibition or fructose-1,6-bisphosphate activation. The properties of red cell PK were similar to those of the muscle-type enzyme. Lactate dehydrogenase (LDH) from the trout erythrocyte resembled LDH from trout heart in terms of pyruvate inhibition in vitro. Enzymes associated with phosphagen and amino acid metabolism as well as the pentose phosphate shunt were also present. However, enzyme indicators of glycogenolytic and gluconeogenic potential were either absent or present at very low levels. The capacity for aerobic respiration via the tricarboxylic acid (TCA) cycle was suggested by the presence of citrate synthase activity.

The association of glycolytic enzymes with the particulate fraction of the red cell was assessed for six enzymes. No binding was detected for hexokinase, PK and LDH; low levels of binding by phosphofructokinase (5%), aldolase (1%) and glyceraldehyde-3-phosphate dehydrogenase (3%) were not altered by strenuous exercise. Glycolytic enzyme binding, therefore, does not appear to be an important regulator of energy metabolism in these cells. Intracellular glucose levels, in contrast, appeared to be regulated following exercise stress. An increase in intra-erythrocytic lactate levels at this time may reflect the importance of exogenously produced lactate as a substrate for ATP production. The description of trout red cell metabolism presented here provides a basis for further study of the relationships between organismic gas exchange and molecular-level adaptation of nucleated red cell function.
The Coordinated Action of Abdominal Postural and Swimmeret Motor Systems in Relation to Body Tilt in the Pitch Plane in the Norway LobsterNephrops Norvegicus
Authors: Knox Paul C. , Neil Douglas M.
Published: April 2021

The responses of the abdominal positioning system and the swimmerets of the Norway lobster Nephrops norvegicus to tilts in pitch and in other vertical planes have been investigated in intact and semi-intact preparations. Tilt of the intact animal in the pitch plane evoked abdominal flexion with the head up and extension with the head down. The response amplitudes were largely independent of tilt angle, and the null point for switching between flexion and extension responses was at the 10° head-up position, which corresponds to the normal posture of the animal. Intersegmental joint angles in the abdomen were significantly different for head-up and head-down tilts. These pitch responses were dependent upon the integrity of the statocysts. Tilts in different vertical planes demonstrated that the abdominal flexion/ extension response was restricted to a range of tilts within ±5° of true pitch. Outside this range, tilts in both directions elicited abdominal extension, which was accompanied by asymmetrical movements of the uropods and swimmerets. In semi-intact preparations, recordings from the motor supply to the abdominal superficial flexor muscles demonstrated a modulation of activity in response to tilt in the pitch plane: several small excitatory axons increased their discharge in the head-up position, while the inhibitory axon f5 fired when the head was down. With tilts in different vertical planes this pattern of firing persisted from pitch almost to roll. The effects of tilt in the pitch and roll planes on the temporal and spatial parameters of swimmeret beating were studied in intact animals. Swimmeret beating was bilaterally symmetrical in pitch: vigorous in the head-down position, when the powerstrokes were directed about 25° to the side, and weak in the head-up position, when the powerstrokes were directed to the rear. Responses in roll were asymmetrical, with the powerstroke of the upper swimmerets directed at about 41° to the side. Recordings of the tonic returnstroke motor neurone of the swimmeret demonstrated that its activity was modulated by tilt in the pitch plane: increasing and becoming rhythmic in the head-down position in active preparations, with the activity phase-locked to the tilt stimulus. With tilts in different vertical planes this unit showed a phase shift at intermediate angles between pitch and roll. Simultaneous recordings of motor activity to the abdominal superficial flexor muscles and the swimmeret tonic returnstroke unit demonstrate closely similar, but not completely coupled, patterns of firing. These results are discussed in terms of the nature of statocyst control of postural and rhythmic abdominal motor systems, the different relationships of motor activities and behavioural responses to tilts in pitch and other vertical planes, and possible neuronal mechanisms that control the interaction of the two abdominal motor systems.
The Motor Innervation of a Triply Innervated Crustacean Muscle
Authors: Van Harreveld A.
Published: April 2021

The crustacean muscle is extremely sensitive to mechanical injury. This is due to the fact that the muscle fibres are innervated by a feltwork of nerve fibres which surrounds them. Appare?ntly, there is a lack of a muscular conduction process in these muscles. Contractions have been observed in the same muscle fibres during stimulation of the axon for the fast contraction as well as during stimulation of the fibre for the slow contraction.
Observations On the Blood of Certain Ascidians, with Special Reference to the Biochemistry of Vanadium
Authors: Webb D. A.
Published: April 2021

The blood of a number of species of Ascidiacea has been examined with reference to the presence of the vanadium chromogen described by Henze, and the results are discussed in connexion with the data available from other authors. The chromogen is always contained, together with sulphuric acid, in a special type of cell described as a vanadocyte. These are found only in the Ascidiidae and Perophoridae, though members of certain other families contain vanadium in some other form. The distribution within the group of sulphuric acid in vesicular cells of the blood and test is also discussed. There is no reason to suppose that the pigments of Ascidians, other than the chromogen itself, are vanadium compounds. A curious type of cell inclusion from the orange pigment cells of Ascidia mentula is described.

Experimental evidence and theoretical considerations are brought forward to show that the vanadium chromogen is not in any sense a respiratory pigment. At present no function can be ascribed to it. It is not a protein or porphyrin compound, but seems to consist of vanadium in association with a straight chain complex of pyrrol rings, comparable perhaps to a bile pigment.

It seems possible that sea water provides a sufficiently rich source of vanadium to account for the amounts absorbed.

The phylogenetic aspects of these facts are considered in relation to Berrill’s recent re-classification of the Ascidiacea. The presence of vanadium is a primitive character which has been lost in the more specialized families.
Size and Power in Mammals
Authors: Heusner Alfred A.
Published: April 2021

The relationship between basal metabolism P and body mass M of 391 mammalian species has been analysed by least-squares regression, robust regression and covariance analyses. This relationship is a power function:

where the mass exponent b is 0.678±0.007 (mean±S.D.) and the mass coefficient a takes different values. Theory of measurement revealed that the 2/3 mass exponent is due to an underlying dimensional relationship between the primary quantity of mass and the secondary quantity of power.

This paper shows that the 2/3 mass exponent is not the physiological problem of interest. It is not the slope of the metabolic regression line, but its location in the mass/power plane, that must be explained. This location is given by the value of the mass coefficient, the explanation of which is, and remains, the central question in comparative physiology.