bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Three-Compartment Model Describing Temperature Changes in Tethered Flying Blowflies
Authors: Stavenga D. G. , Schwering P. B. W. , Tinbergen J. 
Published: April 2021

ABSTRACT
A three-compartment model is presented that describes temperature measurements of tethered flying blowflies, obtained by thermal imaging. During rest, the body temperature is approximately equal to the ambient temperature. At the start of flight, the thorax temperature increases exponentially with a time constant of 30s; in steady flight, a temperature of approximately 30°C is reached (ambient temperature approximately 25°C). After flight, the temperature of the thorax decreases exponentially with a time constant of 50s. Fitting the time courses of the three body compartments, i.e. head, thorax and abdomen, with the model allows the thermal parameters to be calculated. The metabolic heat produced by a blowfly during tethered flight is estimated to be approximately 23mW.
Anosmia In ZnSO4-Treated Pigeons: Loss of Olfactory Information During Ontogeny and the Role of Site Familiarity in Homing Experiments
Authors: Schmid Jutta , Schlund Wolfgang 
Published: April 2021

ABSTRACT
Depriving homing pigeons of olfactory information by spraying an 18% zinc sulphate solution onto their olfactory ephithelium results in anosmia that persists for at least 5 days (tested using the ‘orienting response’). To study whether anosmic zinc-sulphate-treated pigeons (ZnSO4-pigeons) were able to compensate for their loss of olfactory information by using familiar landmarks, we made releases from two different distances (9–24km, 54–70km). The birds had homed once before from each release site. At shorter distances, ZnSO4-pigeons, sham-treated controls and untreated super controls were well oriented. At the longer distances, the anosmic pigeons and the sham-treated controls did not show any directional preference whereas the super controls were oriented towards home. In all cases, however, fewer anosmic pigeons homed successfully and their homing speed was slower than the speed of either control group.
In order to determine whether experience during ontogeny affects the orientation behaviour, a group of young pigeons was reared anosmically by application of ZnSO4 solution once a week. A second group of experimental pigeons was made anosmic just before the critical release. When released at unfamiliar sites located between 15 and 24km from home, all but the group of short-term ZnSO4-pigeons were well oriented. Neither permanently nor temporarily anosmic ZnSO4-pigeons showed good homing performances. These data indicate that homing pigeons determine their home direction by relying on the navigational factors they have collected during rearing. The paradoxical finding that anosmically reared pigeons were oriented towards home but did not home successfully leads to the questions of whether intra-nasal irrigation with ZnSO4 solution results in extensive brain damage or whether initial orientation and the rest of the homing process are based on different mechanisms.
Interactions of Acid–base Status and Nitrogen Excretion and Metabolism in the Ureogenic Teleost Opsanus Beta
Authors: Barber M. Lee , Walsh Patrick J. 
Published: April 2021

ABSTRACT
The interactions of acid–base status, waste nitrogen excretion and metabolism in the gulf toadfish Opsanus beta, a ureogenic teleost, were examined by exposing toadfish to a variety of water treatments. Our measurements show that, like other marine teleosts, toadfish rapidly regulate acid–base status by manipulating blood [HCO3−]. Several treatments affected nitrogen excretion. The initial stages of hypercapnia (1% CO2) led to significant reductions in ureogenesis, and the later compensated stages (with elevated plasma [HCO3−]) led to significant increases in ureogenesis. Treatment of water with HCl (which lowered pH and reduced the carbonate content) substantially inhibited ureogenesis. Subsequent experiments with NH4Cl loading and several other treatments suggest that this depression is less likely to be the result of acid–base perturbations, but is probably an enhancement of the fish’s ability to excrete waste nitrogen as ammonia, thereby decreasing the drive for ureogenesis. Enzyme activities and hepatocyte ureogenic potential were unaffected by various acid–base treatments, but a significant depletion of plasma amino acid levels was associated with the increase in plasma [HCO3−] induced by hypercapnia. Changes in ureogenesis associated with our treatments appear to be due primarily to changes in substrate levels, rather than to wholesale changes of the biochemical machinery. Our results are discussed in the context of the hypothesis of Atkinson and colleagues, that ureogenesis is a means for acid–base regulation via bicarbonate consumption.
Ventilatory responses to hypoxia in the toad Bufo paracnemis before and after a decrease in haemoglobin oxygen-carrying capacity
Authors: Wang Tobias , Branco Luiz G. S. , Glass Mogens L. 
Published: April 2021

ABSTRACT
The ventilatory and cardiovascular effects of a decreased O2-carrying capacity of the blood were evaluated in the toad Bufo paracnemis. Pulmonary ventilation was monitored using a pneumotachographic technique. Chronic arterial catheters served to record both cardiac frequency and blood pressure and enabled the withdrawal of blood samples for analysis of pH and partial pressure of O2. Haemoglobin concentrations were determined by the cyanmethaemoglobin method. The ventilatory response to hypoxia was not affected by the reduction in blood O2-carrying capacity, which suggests that rather than O2 content is the regulated variable. The reduction in capacity is accompanied by an increased normoxic heart rate and by a reversal of the hypoxic tachycardia normally observed.
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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.