bluuebunny/crossref_metadata_2025 huggingface dataset:
Post-exercise lactate production and metabolism in three species of aquatic and terrestrial decapod crustaceans
Authors: Henry R. P. , Booth C. E. , Lallier F. H. , Walsh P. J.
Published: April 2021

Aquatic and terrestrial crustaceans are dependent on both aerobic and anaerobic metabolism for energy production during exercise. Anaerobic energy production is marked by an accumulation of lactate in both muscle tissue and haemolymph, but the metabolic fate of lactate is not clear. Lactate recycling via gluconeogenesis and the potential role of carbonic anhydrase (CA) in supplying bicarbonate for the carboxylation of pyruvate were investigated in three species of decapod crustaceans: Callinectes sapidus (aquatic), Cardisoma guanhumi (semi-terrestrial) and Gecarcinus lateralis (terrestrial). CA activity was found in mitochondria and cytoplasmic fractions of gill, hepatopancreas and muscle of all three species. Significant activities of key enzymes of gluconeogenesis (e.g. pyruvate carboxylase, phosphoenolpyruvate carboxykinase and fructose bisphosphatase), however, could not be detected. Exercise to exhaustion produced a species-specific pattern of accumulation and clearance of lactate in tissue and haemolymph, indicating a differential degree of reliance on anaerobic energy production. Treatment with acetazolamide, a CA inhibitor, did not significantly alter the pattern of lactate dynamics in animals given repeated bouts of exhaustive exercise interspersed with periods of recovery. Injection of [U-14C]lactate resulted in the appearance of label in both muscle glycogen and excreted carbon dioxide, suggesting multiple metabolic fates for lactate. Lactate turnover rates for G. lateralis were similar to those reported for fish. In these animals, gluconeogenesis possibly proceeds via the reversal of pyruvate kinase, or via the typical Cori cycle but so slowly that the uncatalysed supply of bicarbonate is sufficient to keep pace with the low activities of pyruvate carboxylase and the subsequent low rates of pyruvate carboxylation.
The Na+-independent taurine influx in flounder erythrocytes and its association with the volume regulatory taurine efflux
Authors: Thoroed S. M. , Fugelli K.
Published: April 2021

95 % of the Na+-independent influx of taurine in flounder erythrocytes at normal osmolality (330 mosmol kg−1) and 0.30 mmol l−1 taurine was mediated by a saturable system (Vmax=0.689 nmol g−1 dry mass min−1; Km=0.47 mmol l−1). The influx was inhibited by taurine analogues, but was not significantly affected by reduced osmolality. This saturable influx of taurine was probably mediated by the so-called Na+-dependent influx system for taurine operating in the 0 Na+: 1 taurine mode. The remaining 5 % of the Na+-independent influx was mediated by a diffusional pathway (Kd=0.050 µl g−1 dry mass min−1), since it did not show saturation kinetics, was not inhibited by taurine analogues and did not mediate counter-exchange. This non-saturable influx system for taurine was strongly, but transiently, stimulated by reduction of osmolality. The time course for this stimulatory effect was the same as that for the system that mediates the volume regulatory efflux of taurine. The relative inhibitory effect of bumetanide, furosemide, DIDS and quinine on the fluxes mediated by these two transport systems were also the same. We suggest that these unidirectional fluxes of taurine were mediated by only one transport system: a taurine channel. The effect of reduction of osmolality on the rate coefficient for efflux of β-alanine was equal to the effect on the efflux of taurine, but greater than the effect on the efflux of choline. This difference probably reflects structural and/or electrical restrictions on the substrates to be transported by the taurine channel. The volume regulatory efflux of taurine was inhibited in the presence of the anti-calmodulin drug trifluoperazine and, in a Ca2+-free medium, added EGTA. The 5-lipoxygenase inhibitor nordihydroguaiaretic acid completely blocked the volume regulatory efflux of taurine. We suggest that both Ca2+/calmodulin and leukotrienes contribute to the control of the transport mediated by the taurine channel.
The effects of acclimation temperature on the dynamics of catecholamine release during acute hypoxia in the rainbow trout Oncorhynchus mykiss
Authors: Perry S. F. , Reid S. G.
Published: April 2021

The response of cannulated rainbow trout (Oncorhynchus mykiss) to acute hypoxia was studied in fish acclimated to two temperatures (5 and 15 °C). Blood/water respiratory variables and plasma catecholamine levels were measured before and 15 min after exposure to hypoxic water varying between 4.0 and 10.7 kPa (30–80 mmHg) oxygen partial pressure . Arterial blood and oxygen content fell during hypoxia in a similar manner at both temperatures, although the changes in were often more pronounced in the fish acclimated to 15 °C. Regardless of acclimation temperature, plasma catecholamine levels were consistently elevated at values below 8.0 kPa (60 mmHg); the largest increases in plasma catecholamine levels occurred below =5.3 kPa (40 mmHg). Adrenaline was the predominant catecholamine released into the circulation. Adrenaline was released at values of 8.0 kPa or below, whereas noradrenaline was released at values of 6.7 kPa or below.

The construction of in vivo oxygen dissociation curves demonstrated an obvious effect of acclimation temperature on haemoglobin (Hb) oxygen-affinity; the P50 values at 15 °C and 5 °C were 3.6 kPa (26.7 mmHg) and 1.9 kPa (14.0 mmHg), respectively. At 15 °C, catecholamines were released into the circulation abruptly at a threshold of 4.6 kPa (34.5 mmHg) while at 5 °C the catecholamine release threshold was lowered to 3.3 kPa (24.5 mmHg). The difference in the catecholamine release thresholds was roughly equivalent to the difference in the P50 values at the two distinct temperatures. Catecholamine release thresholds, calculated on the basis of arterial blood oxygen-saturation (expressed as /[Hb]), were similar at both temperatures and were approximately equal to 53–55 % Hb O2-saturation.

The results support the contention that the lowering of blood oxygen content/saturation rather than per se is the proximate stimulus/signal causing catecholamine release in rainbow trout during acute hypoxia.
Effects of barium Chloride on electrolyte transport across isolated colons from normal and Aldosterone-treated lizards (Gallotia Galloti)
Authors: Díaz Mario , Lorenzo Antonio , Gómez Tomás , Badía Pilar , Bolaños Ana
Published: April 2021

Addition of BaCl2 to the solution bathing colons of normal lizards did not alter the absorptive Na+ flux, but did reverse the net absorption of Cl− to become net secretion. Cl− secretion resulted from an increase in its serosal-to-mucosal movement and was positively correlated to an increase in short-circuit current. Ba2+-induced short-circuit current was dependent on the presence of both Na+ and Cl− in the serosal medium. Ba2+-induced Cl− secretion could be reversed by serosal amiloride (10−4 mmol l−1). Colons from acutely or chronically aldosterone-treated lizards exhibited a considerably higher short-circuit current, potential difference and net Na+ absorption than did untreated colons. Net Cl− transport was unaltered by acute treatment, but was totally abolished after chronic treatment. BaCl2 rapidly decreased the potential difference, short-circuit current and tissue conductance across colons from aldosterone-treated lizards. Net Na+ transport was markedly inhibited by Ba2+ in both acutely and chronically treated tissues, but barium did not change unidirectional or net Cl− fluxes in these. The present results support the following hypotheses: (1) that BaCl2 inhibits electrogenic Na+ absorption induced by acute or chronic aldosterone treatment and (2) that Ba2+ induces an electrogenic Cl− secretion by stimulating a basolateral Na+-dependent Cl− intake in normal but not in aldosterone-treated colons. This also suggests that aldosterone could exert an antisecretory influence in colonic epithelia.
Characterization of macrophages and neutrophilic granulocytes from the pronephros of carp (Cyprinus carpio)
Authors: Kemenade B. M. Lidy Verburg-Van , Groeneveld Adrie , Rens Birgitte T. T. M. Van , Rombout Jan H. W. M.
Published: April 2021

To analyse the functional activity of different leucocyte types, carp pronephros cells were separated on Percoll density gradients and by use of fluorescence-activated cell sorting. Cell populations were characterised by light and electron microscopy and by flow cytometry. Fractions enriched in macrophages and neutrophilic granulocytes were subsequently analysed for phagocytic activity in vitro by quantification of the uptake of Escherichia coli bacteria or yeast cells, and for respiratory burst response by measurement of the production of the reactive oxygen intermediates O2∸ and H2O2. Both cell types showed very active in vitro phagocytosis and production of both O2∸ and H2O2. When activated with phorbol myristate acetate or bacteria, it was evident that the neutrophilic granulocytes were significantly more active than the macrophages.

Analysis of single-cell respiratory burst activity in fish phagocytes was investigated after preloading of cells with dihydrorhodamine123. Cells were subsequently separated and analysed for fluorescence using flow cytometry. Both the macrophage-enriched fraction and the granulocyte-enriched fraction appeared to consist of active and inactive subpopulations. In comparison with the inactive populations, active populations had characteristic high forward/sideward scatter profiles.
Aquatic prey transport and the comparative kinematics of ambystoma tigrinum feeding behaviors
Authors: Gillis G. B. , Lauder G. V.
Published: April 2021

Four definable feeding behaviors used during the metamorphic life history of tiger salamanders are terrestrial prey capture and transport (as adults) and aquatic prey capture and transport (as larvae). Previous studies have focused primarily on the first three of these behaviors and thus aquatic prey transport is poorly understood. These studies have indicated that terrestrial prey capture has unique kinematic and motor patterns, whereas the other behaviors are quite similar to one another. Using high-speed video analysis, the kinematics of aquatic prey transport in larval Ambystoma tigrinum are described using both lateral and ventral views. These kinematic patterns are statistically compared with the kinematic patterns of aquatic prey capture, terrestrial prey capture and terrestrial prey transport. Statistical analyses allow us to assess the similarities and differences among the four behaviors and to determine the effect of the metamorphic environmental transition (water to land) and morphological changes of the feeding mechanism (suction-to lingual-based) on feeding kinematics. Our data do not support the notion that lingual-based terrestrial prey capture uses unique kinematic patterns compared with the other three behaviors, which consist of similar movements. Rather, each of the feeding behaviors has unique kinematic features that distinguish it from the others. In addition, variation in tiger salamander feeding kinematics is more a function of the feeding event (whether it is capture or transport) than of the environment in which the feeding takes place or the morphology of the feeding mechanism. Finally, we encourage the use of parsimony-based methods of phylogenetic analysis to analyze shared traits (such as kinematic and/or electromyographic variables) in comparative studies of behavior within a single species.
Gadolinium is a powerful blocker of the activation of nematocytes of Pelagia noctiluca
Authors: Salleo Alberto , La Spada Giuseppina , Barbera Rosa
Published: April 2021

The activation properties of in situ nematocytes of Pelagia noctiluca (Scyphozoa) were investigated by physical contact with a gelatin probe that, besides stimulating the nematocyte battery, retains the discharged nematocysts, thereby allowing a quantitative evaluation of the response. In oral arms previously treated with 2 mmol l−1 La3+ the discharge was inhibited. This result confirms the Ca2+-dependence of nematocyte activation. A similar inhibitory effect was induced by treatment with 20 μmol l−1 Gd3+, a powerful blocker of mechanosensitive ion channels. It is therefore proposed that Ca2+-permeable mechanosensitive channels are involved in the activation of nematocytes. 50 μmol l−1 Gd3+ added to the gelatin probe was effective in otherwise untreated oral arms. This result suggests that Gd3+ could be useful in preventing stings from harmful Cnidaria.
The effects of acheta Diuretic peptide on isolated malpighian tubules from the house cricket Acheta domesticus
Authors: Coast Geoffrey M. , Kay Iain
Published: April 2021

Acheta diuretic peptide (Acheta-DP) is a corticotropin-releasing factor (CRF)-related peptide found in head extracts of the house cricket Acheta domesticus. The peptide causes a dose-dependent increase in fluid secretion by cricket Malpighian tubules isolated in vitro, and the apparent EC50 is 1.3 nmol l−1, which is within the physiological range for a peptide hormone. The CRF antagonist α-helical CRF(9-41) blocks the action of Acheta-DP in a dose-dependent manner, and the IC50 is estimated to be in the micromolar range. Addition of Acheta-DP to isolated Malpighian tubules is followed by a rapid and marked increase in the level of intracellular cyclic AMP. This precedes any change in voltage or fluid secretion, which strongly suggests that cyclic AMP is the intracellular mediator of Acheta-DP activity. Consistent with this, diuretic activity is potentiated by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine, and there is a close relationship between the dose–response curves for cyclic AMP production and for fluid secretion. However, exogenous 8-bromo-cyclic AMP does not mimic all the effects of Acheta-DP, and the peptide may have a dual action on isolated tubules.

Fluid secretion by tubules dosed repeatedly with Acheta-DP returns to near basal levels after 3–5 h. This cannot be explained by degradation of the peptide, but might be due in part to oxygen and/or metabolite deficiency. However, tubules that are refractory to Acheta-DP can be stimulated by forskolin, 8-bromo-cyclic AMP and extracts of corpora cardiaca, which is indicative of a homologous desensitization of membrane receptors for the diuretic peptide.

Differences in the rate of secretion by morphologically distinct regions of cricket Malpighian tubules have been assessed. In unstimulated tubules, the rate of secretion per unit length by the short distal segment is about twice that of the main tubule. However, diuretic peptides (Acheta-DP and achetakinin-I) have little effect on distal tubule secretion, but evoke a two-to fourfold increase in fluid secretion by the main tubule segment.
Effect of the external concentration of calcium on the postmoult uptake of calcium in blue crabs (Callinectes Sapidus)
Authors: Neufeld Douglas S. , Cameron James N.
Published: April 2021

The rate of calcium uptake in blue crabs (Callinectes sapidus Rathbun) acclimated to 2 ‰ sea water with a calcium concentration of 1.4 mmol l−1 was dependent on the magnitude and direction of the electrochemical gradient for calcium. When transferred to water with a high calcium concentration (6 mmol l−1), the electrochemical gradient for calcium favoured diffusive influx, and calcium uptake and apparent H+ excretion increased by approximately 50 %. When transferred to water with a low calcium concentration (0.10 mmol l−1), where the electrochemical gradient for calcium strongly favoured diffusive efflux, calcium uptake ceased but apparent H+ excretion continued at a reduced rate. Crabs regulated the free calcium concentration in their blood at approximately 8 mmol l−1 when the external concentration of calcium was 1.4 mmol l−1 or higher, but the concentration of free calcium in the blood decreased to 5.6 and 4.6 mmol l−1, respectively, at external concentrations of calcium of 0.25 and 0.10 mmol l−1. Crabs transferred to water with 0.10 mmol l−1 calcium for the first 2 days after moult accumulated only 2.5 g calcium kg−1 wet mass, about one-quarter of the mass normally accumulated. Seawater-acclimated crabs transferred to 2 ‰ salinity at 1 day postmoult took up calcium at a reduced rate, indicating that a period of acclimation is necessary for a component of the active transport system to increase its capacity, for diffusive efflux to be reduced, or for both to occur.
Doppler-Shift compensation by the mustached Bat: Quantitative Data
Authors: Keating A. W. , Henson O. W. , Henson M. M. , Lancaster W. C. , Xie D. H.
Published: April 2021

Quantitative data for Doppler-shift compensation by Pteronotus parnellii parnellii were obtained with a device which propelled the bats at constant velocities over a distance of 12 m. The bats compensated for Doppler shifts at all velocities tested (0.1–5.0 m s−1). The main findings were (1) that compensation was usually accomplished by a progressive lowering of the approximately 61 kHz second harmonic constant-frequency component of emitted sounds in small frequency steps (93±72 Hz); (2) that the time needed to reach a steady compensation level averaged 514±230 ms and the number of pulses required to reach full compensation averaged 10.78±5.16; (3) that the animals compensated to hold the echo (reference) frequency at a value that was slightly higher than the resting frequency and slightly lower than the cochlear resonance frequency; (4) that reference frequency varied as a function of velocity, the higher the velocity of the animal, the higher was the reference frequency (slope 55 Hz m−1 s−2); and (5) that the mean reference frequency was always an undercompensation. The average amount of undercompensation was 15.8 %. There was a significant difference (P::s0.005) in Doppler-shift compensation data collected at velocities that differed by 0.1 m s−1. A velocity difference of 0.1 m s−1 corresponds to a Doppler-shift difference of about 35 Hz in the approximately 61 kHz signals reaching the ear.
Jumping performance of hylid frogs measured with high-speed cine film
Authors: Marsh Richard L. , John-Alder Henry B.
Published: April 2021

Jumping performance at 20 °C was assessed in five species of hylid frogs using high-speed cine film. Mean takeoff velocities (Vt) varied from 1.5 to 2.4 m s−1 among the species. Peak Vt varied from 1.9 to 2.9 m s−1. Body-mass-specific power output averaged over the entire takeoff period varied from 29 to 91 W kg−1 during the jumps with the highest takeoff velocities. These values are similar to those predicted from jumping distance. As the mass of muscles available to power the jump probably amounts to no more than 17 % of the body mass, average muscle-mass-specific power can be over 500 W kg−1. The performance during jumping is even more impressive in view of the fact that the peak power during takeoff is about twice the average power. These frogs must use elastic storage to redistribute power during takeoff to produce the peak power required and may use pre-storage of elastic energy to boost the average power available.
Role of urea and methylamines in buoyancy of elasmobranchs
Authors: Withers Philip C. , Morrison Garrick , Hefter Glenn T. , Pang Tek-Siong
Published: April 2021

The possible role of urea and trimethylamine oxide (TMAO) in providing positive buoyancy has been examined for elasmobranch fishes. TMAO has a considerably lower density than an equimolar solution of urea, and solutions of both TMAO and urea are considerably less dense than equimolar solutions of most other body fluid solutes. The body fluid composition of three elasmobranchs, the whiskery shark Furgaleus ventralis, the black whaler shark Carcharhinus obscurus and the shovelnosed ray Aptychotremata vincentiana, is typical for marine elasmobranchs, with plasma concentrations of about 260 mmol l−1 Na+, 250 mmol l−1 Cl−, 340 mmol l−1 urea and 70 mmol l−1 trimethylamine oxide. A plasma density of 1.015 was calculated for the whaler shark (from the concentrations, relative molecular masses and absolute molal volumes of plasma solutes), which would contribute a positive lift of 8.45 g l−1. There is a large positive contribution to buoyancy by urea (3.7 g l−1), trimethylamine oxide (1.8 g l−1) and Cl− (4.0 g l−1), whereas slight negative buoyancy is conferred by Na+ (−0.8g l−1). Divalent cations (Ca2+, Mg2+) contribute minimal negative buoyancy (about −0.1 g l−1 each) despite their rather negative partial molal volumes, because of their low concentrations. Muscle fluids contain about 40 mmol l−1 Cl−, 365 mmol l−1 urea, 160 mmol l−1 trimethylamine oxide, 16 mmol l−1 betaine and 69 mmol l−1 sarcosine. The organic solutes contribute about 12.1 g l−1 lift. Although urea and TMAO act as balancing osmolytes, and TMAO as a counteracting solute, a positive buoyancy role must be considered as a further adaptive function of urea and TMAO accumulation in chondrichthyean fishes.
An investigation of the midgut K+ pump of the tobacco hornworm (manduca Sexta) using specific inhibitors and amphotericin B
Authors: Schirmanns K. , Zeiske W.
Published: April 2021

Active K+ secretion in isolated posterior midguts of Manduca sexta was studied by measuring the short-circuit current. One aim of this study was to verify the postulate from biochemical reports that the cooperative apical arrangement of a vacuolar-type H+-ATPase (V-ATPase) and a K+/H+ antiporter drive the short-circuit current. Hence, we tested several specific inhibitors of the V-ATPase on the in vitro midgut preparation. Nitrate, bafilomycin A1, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl) and amiloride all reduced the short-circuit current. This suggests that the H+-ATPase is involved in transepithelial K+ secretion. However, even at relatively high doses of these inhibitors, the block of the short-circuit current was not complete. Two other agents, thallium ions (Tl+, at millimolar concentrations) and trimethyltin chloride (TMT, 50 μmol l−1), did abolish the short-circuit current.

Apical, but not basal, use of the ionophore amphotericin B largely eliminated the short-circuit current. This supports the view that the current-generating source resides in the apical membranes. An apical (and probably intracellular) site of action for NO3−, Tl+ and TMT is suggested by the observation that basal amphotericin B is needed for blockage by NO3− but does not, however, influence the effect of Tl+ and TMT. Likely sites of action are the V-ATPase (for nitrate and TMT) and the K+/H+ antiporter (for Tl+).
The effects of muscle fatigue on bone strain
Authors: Yoshikawa Tomoaki , Mori Satoshi , Santiesteban A. J. , Sun T. C. , Hafstad Else , Chen Jie , Burr David B.
Published: April 2021

There is anecdotal evidence that bone strains may increase to the point that bone becomes susceptible to rapid failure when muscles become fatigued. To determine whether neuromuscular response could be a factor in accelerating bone failure, we tested the hypothesis that muscle fatigue causes a significant increase in peak principal and shear strains in bone. Ten adult foxhounds were subjected to rigorous exercise that caused muscular fatigue while myoelectrical activity of the quadriceps and hamstrings and strain on the distal tibia were monitored simultaneously. Ground reaction forces on the dog hindlimbs were measured before and after strain gauges had been applied to the tibia. The data show a significant shift to lower median myoelectrical frequencies in the quadriceps, indicating muscular fatigue, following the 20 min exercise period. In conjunction with this shift, peak principal and shear strains increased on both compressive and tensile cortices of the tibia and shear strain on the tensile cortex increased significantly (P=0.02). The largest changes were along the anterior and antero-lateral surfaces of the tibia, where peak principal strain increased by an average of 26–35 % following muscular fatigue. The cross-sectional strain distribution was calculated at the gauge site at peak strain at the beginning of the exercise period and at peak strain after 20 min of exercise. These data show a change in strain distribution when muscle becomes fatigued. Strains on the posterior cortex of the bone showed the greatest change. Correlation analysis demonstrated a significant inverse association between median myoelectrical frequency and bone strain after 20 min of exercise (Spearman r2=1.00; P=0.05). These data show that muscle fatigue may be associated with increased bone strain.
Architecture and composition of the muscles that drive stomatopod eye movements
Authors: Jones Jeremy
Published: April 2021

The peculiar structure of the stomatopod eye requires it to make complicated movements. These include slow ‘scans’, which relate to the animal’s colour vision system, as well as faster ‘saccades’. The myology of the eyecup is investigated and shown to consist of eight individual muscles which are divided, on kinematic grounds, into six functional groups. These groups form three pairs of dominant prime movers, with each having primary control over one of the eye movement axes (longitude, latitude and bearing). This is important as it allows each rotational axis to move independently of the other two. Histochemical typing reveals at least four distinct classes of fibre within each muscle. The relationship between the number of types of fibre and classes of eye movement is discussed, as are the implications of coordinate prime movers for neuromuscular control.
Motor neurones of the crayfish walking system possess tea+-Revealed regenerative electrical properties
Authors: Cattaert Daniel , Araque Alfonso , Buno Washington , Clarac François
Published: April 2021

In crustaceans, some motor neurones (MNs) have been shown to be part of the central pattern generator in the stomatogastric system (Harris-Warrick et al. 1992; Moulins, 1990), the swimmeret system (Heitler, 1978) or the walking system (Chrachri and Clarac, 1990). These MNs induce changes in the central rhythm when depolarized and are conditional oscillators in the stomatogastric ganglion. Moreover, in the walking system, rhythmic activity can be triggered by muscarinic cholinergic agonists (Chrachri and Clarac, 1987). We have recently analyzed the role of muscarinic receptors in crayfish walking leg MNs (D. Cattaert and A. Araque, in preparation) and demonstrated that oxotremorine, a muscarinic agonist, evoked long-lasting depolarizing responses associated with an increased input resistance. The outward current blocked by oxotremorine is likely to be carried by K+, as is the case for the M current (IM) in vertebrates (Brown and Adams, 1980). In most neurones, K+ conductances play a principal role in maintaining the membrane potential at rest: for example, IM is active at the resting membrane potential, thus contributing to its maintenance, and the ‘delayed-rectifier’ (IK) assists the fast repolarization after an action potential. Some K+ conductances are Ca2+-dependent (IK,Ca) and are activated by an increase in internal Ca2+ concentration. In such cases, Ca2+ currents may result in hyperpolarization of the neurone through activation of IK,Ca. In opposition to these K+ currents, the direct effect of Na+ and Ca2+ conductances is to depolarize the neurone. For example, the persistant Na+ current (INap) that is responsible for the slow subthreshold depolarization termed slow pre-potentials (Gestrelius et al. 1983; Leung and Yim, 1991) participates in the formation of pacemaker depolarization (Barrio et al. 1991) and generates plateau-type responses in control conditions (Barrio et al. 1991; Llinas and Sugimori, 1980). Similarly Ca2+ or non-specific (Na+/Ca2+) conductances generate such events in Aplysia californica burster neurones (Adams and Benson, 1985), crustacean cardiac ganglion (Tazaki and Cooke, 1990), insect neurones (Hancox and Pitman, 1991) and crustacean stomatogastric ganglion (Kiehn and Harris-Warrick, 1992). Since crustacean MNs can participate in rhythm production, such depolarizing conductances may exist in most of them and may contribute to the long-lasting MN depolarizations and spike bursts present during locomotion.
Gas transport in the haemolymph of arachnids: II. Carbon dioxide transport and acid–Base balance
Authors: Paul R. J. , Pfeffer-Seidl A. , Efinger R. , Pörtner H. O. , Storz H.
Published: April 2021

The relationships between and pH were determined in cell-free undiluted haemolymph of the arachnids Eurypelma californicum, Pandinus imperator and Cupiennius salei. The pH/bicarbonate diagrams and the CO2 equilibrium curves were calculated, using the Henderson–Hasselbalch equation, for haemolymph sampled at rest and during recovery from exercise. The calculations of solubility and dissociation constant (pK‴) were based on additional ion concentration measurements. Blood gas analyses corroborate these results: after locomotor activity, there is a metabolic acidosis linked to the accumulation of lactate in the haemolymph. The concentration of bicarbonate in the haemolymph of resting individuals is quite different in the three species and is related to the extent of post-exercise bicarbonate depletion. During early recovery, buffering in the haemolymph strongly depends upon CO2 release. Potassium and magnesium concentrations in the haemolymph increase after exercise. During cold-acclimation (to 10 °C), there is a metabolic acidosis in the tarantula’s haemolymph that is linked to the accumulation of acetate.
Adrenergic control of swimbladder perfusion in the european eel Anguilla anguilla
Authors: Pelster Bernd
Published: April 2021

Adrenergic control of swimbladder blood flow was analysed in blood-perfused preparations of the European eel as well as in situ by recording the changes in swimbladder blood flow and blood pressure following an injection of catecholamine into the dorsal artery.

In blood-perfused swimbladder preparations, injection of the a-adrenergic agonist phenylephrine into the perfusion loop caused a marked dose-dependent increase in perfusion pressure at constant flow, while injection of the β-agonist isoproterenol slightly decreased perfusion pressure. The β-effect was not as pronounced as the a-adrenergic vasoconstriction and was observed only during the first application of catecholamine in each preparation.

In situ injection of adrenaline (final concentration 10−8-10−9 mol kg−1 body mass) into the dorsal aorta caused a dose-dependent transient increase in dorsal aortic blood pressure and in cardiac output which, after 5–10 min, returned to resting levels. Swimbladder perfusion also increased initially after an injection of adrenaline, but after about 1–2 min suddenly decreased and then slowly recovered to preinjection levels. Following the injection of adrenaline into the dorsal aorta, blood pressure changes in vessels at the swimbladder pole of the rete mirabile revealed a similar biphasic pattern with an initial increase, a subsequent decrease and a slow return to preinjection levels, while pressure in the arterial influx vessel of the rete resembled dorsal aortic pressure.

After injection of the β-blocker propranolol, adrenaline evoked a smaller initial increase in blood flow, but the subsequent reduction in flow was even more pronounced. Injection, in addition, of the a-adrenergic blocker phentolamine abolished the sharp adrenaline-induced decrease in swimbladder perfusion.

It is concluded that a- and β-adrenergically controlled resistance vessels are located close to the rete mirabile, probably at the arterial entrance into the rete. These vessels control perfusion of the rete mirabile and of the swimbladder and are thus involved in the control of gas deposition into the swimbladder.
Energy savings in formation flight of pink-footed geese
Authors: Cutts C. J. , Speakman J. R.
Published: April 2021

Fifty-four skeins of pink-footed geese (Anser brachyrhynchus) were photographed from directly underneath to eliminate the effects of perspective distortion, and the wing-tip spacings (the distance between adjacent birds’ wing tips perpendicular to the flight path at maximum wingspan) and depths (the distance between adjacent birds’ body centres parallel to the flight path) were measured at the same time as local wind speeds. The photographs were used to test for savings in induced power from wing positioning relative to the predicted positions of vortices generated by other wings, using a theoretical model. The mean wing-tip spacing corresponded to a saving in induced power of 14 %, less than one-third of the maximum possible. The saving in total power might be as low as 2.4 %. The high variation in wing-tip spacing suggests that pink-footed geese found difficulty maintaining position and thus adopted a strategy of flying outboard of the optimal position that maximises savings. This may minimise the risk of straying into a zone where savings are negative. There was a significant correlation between depth and wing-tip spacing, supporting an alternative communication hypothesis, whereby the birds position themselves to obtain maximum information on their neighbour’s position. In high winds, there was little change in wing-tip spacing variation but a decrease in depth variation, suggesting a shift towards more regularly spaced skeins.
Determination of protein synthesis in rainbow trout, Oncorhynchus mykiss, using a stable isotope
Authors: Carter C. G. , Owen S. F. , He Z.-Y. , Watt P. W. , Scrimgeour C. , Houlihan D. F. , Rennie M. J.
Published: April 2021

It has been suggested (Houlihan, 1991) that the consumption of 1 g of protein in a variety of species of fish stimulates the synthesis of, approximately, an equal amount of protein. Although synthesis of protein may account for as much as 40 % of the whole-animal oxygen consumption (Lyndon et al. 1992), only about 30 % of the synthesized proteins are retained as growth (Houlihan et al. 1988; Carter et al. 1993a,b). Thus, one focus of attention is the potential advantage gained by fish in allocating a considerable proportion of assimilated energy to protein turnover in contrast to relatively low-cost, low-turnover protein growth (Houlihan et al. 1993). Rates of protein synthesis in several species of fish have been measured using radioactively labelled amino acids, frequently given as a flooding dose (reviewed by Fauconneau, 1985; Houlihan, 1991). These measurements cannot be made for longer than a few hours because of the decline in specific radioactivity in the amino acid free pool. However, as protein synthesis rates vary during the course of a day as a result of the post-prandial stimulation, and since radiolabelled amino acid methodology is invasive, short-term and terminal, it has been difficult to be certain of the relationship between protein growth measured in the long term and protein synthesis rates measured in the short term. This paper addresses these problems by developing a method using 15N in orally administered protein to measure protein synthesis rates in fish over relatively long periods, the aim being to use procedures that are as non-invasive and repeatable as possible. The use of stable isotopes to measure protein metabolism is well established in terrestrial mammals (see Rennie et al. 1991; Wolfe, 1992), but to our knowledge the only published data for aquatic ectotherms are on the blue mussel (Mytilus edulis L.) (Hawkins, 1985). In the present study, rates of protein synthesis of individual rainbow trout [Oncorhynchus mykiss (Walbaum)] were calculated from the enrichment of excreted ammonia with 15N over the 48 h following the feeding of a single meal (dose) containing protein uniformly labelled with 15N by use of an end-point stochastic model (Waterlow et al. 1978; Wolfe, 1992). Application of this type of modelling would appear to be ideal for measuring ammonotelic fish nitrogen metabolism since, unlike the situation in mammals, the catabolic flux of amino acids through urea is very small. Further, ammonia is excreted directly into the surrounding water via the gills and is not stored for any length of time, in contrast to the situation in mammals, so the rate of tracer appearance is easily measurable.
Implications of hyperglycemia for post-exercise resynthesis of glycogen in trout skeletal muscle
Authors: West Timothy G. , Schulte Patricia M. , Hochachka Peter W.
Published: April 2021

Rates of whole-body glucose turnover and muscle-specific glucose utilization were determined in rainbow trout (Oncorhynchus mykiss) at rest and at intervals during recovery from burst swimming. Plasma glucose level was high in the experimental animals (range 6–38 mmol l−1), but hyperglycemia was not related specifically to exercise. Estimated glucose turnover, 19.3±2.6 (rest) and 15.8±3.9 μmol min−1 kg−1 (recovery), was also highly variable, but was linearly associated with plasma glucose concentration (turnover=0.97[glucose]+0.57, r=0.93) in both resting and recovering fish. While utilization of glucose in the whole animal was clearly responsive to plasma glucose availability, estimated total skeletal muscle disposal of glucose accounted for less than 15 % of glucose turnover, indicating that glucose was utilized largely by tissues other than locomotory muscle. Rates of glucose utilization in white muscle (range 0.5–4 nmol min−1 g−1) provide direct evidence that glucose, regardless of plasma concentration, accounted for less than 10 % of glycogen repletion during exercise recovery. In red muscle, glucose uptake was influenced by plasma glucose level below 10–12 mmol l−1 (utilization range 1–15 nmol min−1 g−1), but was independent of glucose concentration above about 12 mmol l−1 (utilization plateaued at 15–20 nmol min−1 g−1). Trout red muscle is similar to mammalian white muscle in the sense that glucose is estimated to account incompletely for glycogen restoration (25–60 %), suggesting dependence on both glycogenesis and glyconeogenesis during recovery. It is concluded that hyperglycemia may be important to the pattern of substrate incorporation into red muscle glycogen and to the rate of repletion observed, but glucose availability has, as predicted from earlier indirect studies, little relevance to white muscle glycogen restoration. The regulatory mechanisms that govern apparently very high glucose turnover rates during extreme hyperglycemia, concomitant with low disposal rates in skeletal muscle, require further investigation.
Immunolocalization of an antigen associated with the invertebrate electrogenic 2Na+/1H+ antiporter
Authors: Kimura Claudine , Ahearn Gregory A. , Busquets-Turner Liz , Haley S. R. , Nagao Cherie , Couet H. Gert De
Published: April 2021

Epithelial plasma membranes from crustacean gut, kidney and gills have been shown recently to display an electrogenic 2Na+/1H+ antiporter that differs considerably in its physiological properties from the vertebrate electroneutral 1Na+/1H+ exchange paradigm. In this study, we describe the histological and cytological localization of an antigen associated with invertebrate electrogenic 2Na+/1H+ antiport in lobster (Homarus americanus) tissues using a monoclonal antibody (MAb 11) raised in mice against purified brush border membranes of the hepatopancreatic epithelium. Previous work showed that MAb 11 inhibited electrogenic 2Na+/1H+ and Ca2+/H+ exchange by hepatopancreatic brush border membrane vesicles, but was without effect on Na+-dependent D-glucose transport, suggesting a restricted inhibitory specificity to the cation exchanger. MAb 11 binding occurred at hepatopancreatic epithelial R-cell brush border membranes, at plasma membranes of the antennal gland and gill podocytes, and at vacuolar membranes of hepatopancreatic B-and R-cells, gill nephrocytes and epithelial cells of the antennal gland labyrinth and gill lamellae, as assessed by FITC-labelled secondary antibodies. Control FITC-labelled antibodies raised in mice against vertebrate keratin proteins displayed only weak non-specific binding to the tissues and cells responding intensely to MAb 11, supporting the specific nature of MAb 11 binding to its cognate antigen. The broad histological and cytological distribution of MAb 11 binding to plasma membranes and vacuolar membranes from several lobster organ systems suggests that the physiological activities regulated by its antigen, possibly an element of the invertebrate electrogenic cation exchanger, may be diverse.
Studies on Nitrogen Fixation by Blue-Green Algae
Authors: Fogg G. E.
Published: April 2021

Recent work, particularly that of De (1939), has shown that some blue-green algae are capable of utilizing the free nitrogen of the atmosphere in the synthesis of cell material. Much further work will be necessary, however, before the importance of nitrogen fixation by these organisms in nature can be estimated, our knowledge both of the distribution of the property within the group of the Myxophyceae and of the physiology of the process being very vague.
The Effects of Some Oestrogenic Substances and Cyclic Hydrocarbons On the Rate of Growth of Cells
Authors: Calcutt G.
Published: April 2021

Oestrone in dilutions of 10− 5 to 10− 7 was found to stimulate the growth of Colpidium sp. over periods of about 24 hr. ; with longer exposures retardation and death occurred. Higher concentrations of the oestrone were found to be lethal; whilst lower ones had no detectable effect. Owing to the impossibility of obtaining suitable solutions of oestradiol benzoate and stilboestrol anomalous results were obtained.
The Biology and Behaviour of Ptinus Tectus Boie. (Coleoptera, Ptinidae), A Pest of Stored Products
Authors: Gunn D. L. , Walshe B. M.
Published: April 2021

In a long temperature gradient apparatus, Ptinus tectus aggregates around two distinct temperatures, 4 and 24° C. In a circular temperature alternative chamber there is no marked avoidance of low temperatures if the gradient is steep, but characteristic avoiding reactions occur if the gradient is not very steep. When the stationary animals are subjected to rising or falling temperatures in the long gradient, there is a well-marked evacuation temperature at 30–33° C., but none at lower temperatures. A temperature preference around 24° C. is correlated with favourable temperature for growth and other activities. The aggregation around 4° C. is the result of a failure of co-ordinated behaviour in a particular kind of gradient, and P. tectus is practically immobilized by cold in that temperature region.
Second Report on a Test of McDougall’s Lamarckian Experiment on the Training of Rats
Authors: Agar W. E. , Drummond F. H. , Tiegs O. W.
Published: April 2021

The late Prof. McDougall’s four ‘Reports on a Lamarckian Experiment’ are likely to become a classic of experimental biology, as being the most sustained attempt up to the present to demonstrate the reality of Lamarckian inheritance in a particular instance. Although, as will appear from this account of our own experiment, we do not believe that it will take its’ place in the history of biology as a successful attempt, we take this opportunity of acknowledging our appreciation of his nearly twenty years’ devotion to this very laborious and exacting experiment.
The Relation of Animal Size to Oxygen Consumption in Some Fresh-Water Turbellarian Worms
Authors: Whitney R. J.
Published: April 2021

A size factor is demonstrated for the oxygen consumption at 14·5°C. of four species of fresh-water Turbellaria obtained from different habitats. For three of the species studied (Polycelis cornuta, Crenobia alpina and Planaria polychroa) small animals were found to have a higher oxygen consumption per unit weight than large ones. In the case of Polycelis nigra small animals were shown to have a lower oxygen consumption per unit weight than large ones. The adherence of the size factor to the surface law of Rubner is discussed. Only Crenobia alpina satisfies the theoretical requirements of the law, and in this species it is shown that the size factor is practically unchanged when the oxygen consumptions are determined at 7·0°C. instead of 14·5°C.
Studies On the Fate of Carbohydrates in the Rumen of the Sheep
Authors: Phillipson A. T. , Mcanally R. A.
Published: April 2021

It was shown in a previous paper (Phillipson, 1942) that the rate of fermentation in the rumen of the sheep appeared to be correlated to the type of carbohydrate present, that a feed of mangolds which contain a high content of soluble sugar, mostly cane sugar, fermented rapidly, that a feed of hay which contains mostly cellulose fermented slowly, whilst starchy foods fermented less rapidly.
The Blood Pressure of the Chick Embryo During Development
Authors: Hughes A. F. W.
Published: April 2021

An apparatus is described for the measurement of the pressure in the chorioallantoic artery of the chick embryo. Data are given of such measurements ranging in time from the second to the nineteenth days of incubation. Some measurements are also given of the arterial pressure of the chick within the first five days after incubation.
The Effect of Crowding Upon the Oviposition of Grain-Infesting Insects
Authors: Crombie A. C.
Published: April 2021

The crowding of adults invariably had a depressing effect upon the rate of oviposition in the insects studied here, while egg-fertility was not affected. In unconditioned media, at densities possible in actual populations, the reduction of fecundity was, it appears, entirely a result of competition for the oviposition sites usually for two purposes, viz. oviposition and feeding. That is to say, at such densities the effect of crowding upon oviposition was of a behaviouristic nature. When two species were living in the same environment their mutual effect upon each other’s fecundity was more or less dependent upon the degree of identity of the niches for which they were competing. The reduction of fecundity of Rhizopertha by homotypically and heterotypically conditioned media was at first roughly proportional to the degree of conditioning, but after a time the effect of all media was the same. Homo- and hetero-typical conditioning were not radically different in effect. It is believed that conditioned medium operates upon fecundity through ‘poisoning’, and that the effect is upon oviposition rather than, as that of starvation, upon egg-production. When returned to an optimum environment the insects recovered from all the experimental conditions mentioned here : immediately from conditions of overcrowding, more slowly from conditioned media, and more slowly still from complete starvation.