bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Promotion of Catecholamine Release in Rainbow Trout, Salmo Gairdneri, By Acute Acidosis: Interactions Between Red Cell pH and Haemoglobin Oxygen-Carrying Capacity
Authors: Boutilier R. G. , Iwama G. K. , Randall D. J. 
Published: April 2021

ABSTRACT
A fall in blood pH was generated either by infusion of HCl or by reducing gill ventilation and raising blood in rainbow trout, Salmo gairdneri Richardson. The acute acidosis resulting from HCl infusion caused an increase in plasma adrenaline and noradrenaline concentrations, the adrenaline increase being proportional to the decrease in blood pH. Fish subjected to a prolonged respiratory acidosis, caused by a reduction in gill ventilation, showed no increase in catecholamines 24 h after the change in gill ventilation. We suggest that catecholamine levels increase in response to a pH decrease, but if acidotic conditions are maintained, circulating catecholamines return to low levels.
There was a much smaller decrease in erythrocytic pH with a fall in plasma pH when catecholamine levels were high. This ameliorating effect of catecholamines on erythrocytic pH during a plasma acidosis maintains the oxygen-carrying capacity of the haemoglobin. If erythrocytic pH was decreased by increasing blood vitro, then there was a fall in haemoglobin oxygen-carrying capacity which was proportional to the reduction in pH.
We conclude that catecholamines are released into the blood in proportion to the fall in blood pH but if the pH is maintained the circulating catecholamines return to their initial low levels. The elevated catecholamine concentrations in blood safeguard against any impairment of haemoglobin oxygen-carrying capacity by maintaining erythrocytic pH in the face of a plasma acidosis.
Spontaneous and Elicited Bag Cell Discharges in Gonadectomized Aplysia
Authors: Ferguson Graham P. , Parsons David W. , Maat Andries Ter , Pinsker Harold M. 
Published: April 2021

ABSTRACT
The neuroendocrine bag cells of the hermaphroditic marine gastropod, Aplysia, secrete peptide hormones that induce release of ripe eggs from the ovotestis. The egg string is subsequently deposited on the substrate by means of a complex sequence of rhythmic head and neck movements. Gonadectomy (removal of the ovotestis) was performed in two closely related species of Aplysia to prevent completely the synthesis, build-up and release of eggs. Chronically implanted electrodes were used either to monitor spontaneous bag cell discharges (A. brasiliana) or to selectively elicit bag cell discharges (A. californica) in gonadectomized and mock-operated animals. Gonadectomized animals showed the normal occurrence of spontaneous bag cell discharges in the complete absence of eggs, indicating that feedback from ripe eggs in the ovotestis is not necessary for normal activation of the bag cells. However, gonadectomized animals showed a significant decrease in specific head and neck movements following elicited bag cell discharges. This finding indicates that, once the bag cells fire and the eggs are released, input from the eggs is necessary for normal expression of the behaviour associated with egg deposition.
Oxygen Consumption During Hover-Feeding in Free-Ranging Anna Hummingbirds
Authors: Bartholomew George A. , Lighton John R. B. 
Published: April 2021

ABSTRACT
Rates of oxygen consumption during hover-feeding of wild, unrestrained, adult male Anna hummingbirds (Calypte anna) were measured with an artificial outdoor feeder converted into a respirometer mask. A computer sampled changes in O2 concentration in air drawn through the mask, automatically detecting the presence of a hummingbird from a drop in the O2 concentration, and photoelectrically timing the duration over which the feeder functioned as a mask. Birds coming to the feeder were weighed on a trapeze perch suspended from a force transducer. Feeding bouts consisted of sallies which carried the head in and out of the feeding mask about once a second. The volume of O2 consumed per feeding sally was linearly related to the length of the sally. The energy cost of hover-feeding in five hummingbirds, mean mass 4·6 g, was 41·5 ± 6·3 ml O2g−1 h−1.
Cardiac Performance in Response to Loading Pressures and Perfusion With 5-Hydroxytryptamine in the Isolated Heart of Busycon Canaliculatum (Gastropoda, Prosobranchia)
Authors: Smith P. J. S. , Hill R. B. 
Published: April 2021

ABSTRACT
In this study the effects of a molluscan neurotransmitter, 5-hydroxytryptamine (5-HT), were examined on the isolated and pumping heart of the gastropod mollusc Busycon canaliculatum. Unlike in previous studies, the response was measured in such a way as to equate it with cardiac output. In addition, the effects on the myogram form and the manner of perfusate ejection were also examined.
As would be expected from previous studies, 5-HT affects heart rate, showing a positive chronotropic response at a threshold of around 10−9moll−1. Stroke volume shows little evidence of being regulated by 5-HT concentration. This observation was unexpected as 5-HT is commonly reported to regulate the ‘force’ of contraction in a molluscan heart and, at constant perfusion conditions, this might have been expected to find expression as an increase in stroke volume. 5-HT does, however, have a very clear dose-dependent effect on the aortic pressure pulse amplitude and duration. Amplitude increases markedly (250%) over the concentrations used (10−10-10−6mol 1−1) with a threshold around 10−8moll−1. The effect on the duration has the same threshold but the opposite result, with a reduction to approximately 50% of the original value. The same amount of perfusate is therefore being ejected at a higher pressure and flow rate. It is suggested that this might have important implications for a soft-bodied animal with a hydrostatic skeleton.
The electrical activity of the heart was also examined and showed that 5-HT increased the amplitude of both the spike and plateau phase of the action potential. The duration of the latter was reduced. This is discussed with reference to other studies.
Bone Strain: A Determinant of Gait and Speed?
Authors: Biewener Andrew A. , Taylor C. Richard 
Published: April 2021

ABSTRACT
Principal strains were recorded in vivo from the radial and tibial midshafts of three goats as they increased speed and changed gait. These data were compared with strain data measured for the radius and tibia of the dog (Rubin & Lanyon, 1982) and the horse (Biewener, Thomason & Lanyon, 1983b) in order to test the hypothesis that similar peak bone strains (stresses) occur at functionally equivalent points in the gaits of different species. Multiple recordings of in vivo strain along the caudal diaphyses of the radius and tibia of one goat were made to test the validity of this technique for measuring peak locomotor stress. Measured strains were extremely consistent over the animal’s full range of speed (coefficient of variation for the radius 0·05–0·08, and for the tibia 0·06–0·11). The data from the three gauges, which were spaced 15 mm apart, demonstrated that maximal strains act at the midshaft, substantiating the use of this technique to measure peak locomotor bone strains. Strain levels recorded at the trot-gallop transition and top galloping speeds of the goat were similar to the values reported for the dog and horse, despite large differences in absolute speed (goat, 4·3ms-1; dog, 6·9ms-1; horse, 7·5ms-1 at maximum gallop). The second moments of area of the tibia and radius (+ ulna) of the dog are 29 % and 113 % greater than for goats of equal size, explaining how similar strains are achieved in the dog at higher speeds than the goat. Furthermore, peak bone strains recorded at the fastest trotting speed were similar to those recorded at the fastest galloping speed for each species. Peak strains recorded for the goat at a maximum gallop correspond to stresses of +37·9 MPa (cranial) and —47·7 MPa (caudal) in the radius and +36·3 MPa (cranial) and —50·3 MPa (caudal) in the tibia, representing a safety factor to yield failure of three.
Regeneration of Fibre Types in Paired Asymmetric Closer Muscles of the Snapping Shrimp, Alpheus Heterochelis
Authors: Govind C. K. , Mearow K. M. , Wong A. 
Published: April 2021

ABSTRACT
The fibre composition of the closer muscle in the paired asymmetric (snapper and pincer) chelipeds of the snapping shrimp, Alpheus heterochelis (Say), was determined in the pristine and in the regenerated conditions. In the pristine condition, the snapper muscle has exclusively slow fibres in both male and female shrimps. The pincer muscle has a central band of fast muscle sandwiched by slow muscle. This band of fast muscle is proportionately and significantly larger in the female than in the male (36% compared to 21%), thus demonstrating a subtle form of sexual asymmetry.
The chelipeds were induced to regenerate following their removal within 24 h of a moult. During the intervening intermoult, limb buds formed which, at the next moult, transformed into newly regenerated chelipeds. In these regenerated chelipeds the snapper muscle was usually entirely composed of slow fibres as in the pristine muscle. In a few animals, however, a scattering of fast fibres occurred in the central region; a condition reminiscent of the pincer muscle. The regenerated pincer muscle resembled its pristine counterpart in having a central band of fast fibres sandwiched by slow fibres. In male shrimps, the proportion of fast fibres in the regenerated muscle was similar to that in the pristine muscle. In females, however, the proportion of fast muscle was significantly smaller in the regenerated than in the pristine condition (21 % compared to 36 %). Since a closer muscle with a central band of fast fibres sandwiched by slow is found during regeneration in pincer and occasionally snapper chelipeds, such a pattern represents an early developmental stage which is being recapitulated during regeneration. There is no evidence in Alpheus heterochelis that the pincer muscle initially regenerates exclusively fast fibres as was reported for A. californiensis.
Haemolymph Acid-Base, Electrolyte and Gas Status During Sustained Voluntary Activity in the Land Hermit Crab (Coenobita Compressus)
Authors: Wheatly Michèle G. , Mcmahon Brian R. , Burggren Warren W. , Pinder Alan W. 
Published: April 2021

ABSTRACT
After 3 h (50 m) of voluntary walking, the haemolymph pH of the land hermit crab Coenobita compressus (H. Milne Edwards) decreased by 0·4units. This was accompanied by increases in CO2 tension bicarbonate (HCO3- + CO32-) and lactate concentrations. The hypercapnic acidosis was partially compensated by metabolic bicarbonate accumulation and an H+ deficit developed. Unloaded crabs accumulated less of a proton load than crabs transporting mollusc shells. During activity, oxygenation of the haemocyanin (HCy) accounted for the release of 0·3 mmol CO21-1, via the Haldane effect, which was seven times more than in settled crabs. Control acid-base balance was re-established within 1 h of recovery. At this time, acidic equivalents were excreted at a mean flux rate of 5 mequivkg-1 h-1 into a source of external water. [Na+] and the ratio of [Na+] : [Cl-] increased during exercise.
Coenobita haemolymph had a high O2-carrying capacity . HCy oxygen-binding characteristics were typical of other decapods (ϕ = -0·44), yet no lactate sensitivity was apparent. Settled in vivo values of O2 tension and content were located around the half-saturation tension (P50) of the dissociation curve. During exercise, increased and an unopposed Bohr shift decreased the O2-binding affinity, thereby reducing postbranchial saturation. Quantitatively, however, compensations in cardiac output were more instrumental in increasing the O2 delivery to respiring tissues. During recovery, haemolymph remained high and the venous reserve doubled.
Correlations Between Body Angles and Substrate Curvature in the Parasitoid Wasp Trichogramma Minutum: A Possible Mechanism of Host Radius Measurement
Authors: Schmidt J. M. , Smith J. J. B. 
Published: April 2021

ABSTRACT
The parasitoid wasps of the genus Trichogramma use the surface curvature of their insect egg hosts to set an upper limit to the number of progeny allocated to the host, as well as the duration of their host examination. In addition, host recognition and host acceptance are in part mediated by surface curvature. In this paper, the relationships between the positions of body parts of the wasp and surface curvature are examined in order to determine a possible mechanism for curvature detection by ‘the wasp.
Wasps of different sizes were photographed in profile while examining glass bead models of different diameters. The positions of selected body parts were analysed using a digitizer and microcomputer. The height of the wasp above the model surface did not change with surface curvature. Furthermore, the angle of the head relative to the thorax was also constant over the range of models used. Only the scapal-head angle and flagellar-head angle changed significantly with surface curvature.
A curvature detecting mechanism is proposed in which the wasp uses the scapal-head angle to measure the curvature of the surface. The body of the wasp is maintained at a preferred height and angle to the substrate, serving as a fixed platform from which curvature measurements are made. Additional features of this mechanism, as well as its correlation with morphological and behavioural findings, are discussed.
Myocardial Intracellular pH in A Perfused Rainbow Trout Heart During Extracellular Acidosis in the Presence and Absence of Adrenaline
Authors: Farrell A. P. , Milligan C. L. 
Published: April 2021

ABSTRACTMyocardial intracellular pH was measured in a perfused rainbow trout, Salmo gairdneri, with DMO (5,5-dimethyl-2,4-oxazolidinedione), to test the hypothesis that catecholamines promote active regulation of myocardial pH in order to protect contractility during a respiratory acidosis comparable to that observed after exercise. Under control conditions (extracellular pH= 8·0; ), myocardial pH was 7·53 ± 0·01 (N=5). Acidosis (extracellular pH = 7·45; ) reduced contractility, mechanical efficiency and intracellular pH (7·25 + 0·04), but did not affect myocardial O2 consumption. The addition of 0·5 μmoll-1 adrenaline during extracellular acidosis prevented the loss of contractility, restored mechanical efficiency, but did not change intracellular pH significantly. Thus, adrenaline enabled cardiac contractility to recover, without intracellular pH regulation, possibly by modulation of sarcolemmal calcium changes. The absence of a myocardial acidosis after exercise in vivo is discussed with respect to possible intracellular pH regulation via lactate uptake and metabolism.
Inhibition of A Chloride Pump By Acetazolamide In The Intestine of Aplysia Californica
Authors: Gerencser George A. 
Published: April 2021

ABSTRACT
The isolated intestine of Aplysia californica, bathed in a substrate-free NaCl seawater bathing medium, generates a spontaneous transepithelial potential difference such that the serosal surface is negative relative to the mucosal surface (Gerencser, 1978b). The short-circuit current (Isc) is accounted for by active absorptive mechanisms for both Na+ and Cl−, the Cl− transport mechanism being more vigorous than that for Na+ (Gerencser, 1978a). However, Cl− transport appeared to be independent of Na+ transport, for the Isc measured in an Na+-free seawater bathing medium was shown to be identical to a net active absorptive flux of Cl− (Gerencser, 1984a). It was hypothesized that active Cl− absorption in Aplysia enterocytes was mediated by a primary active transport process, because it had been demonstrated that the intracellular Cl− electrochemical potential was less than that measured in the extracellular medium (Gerencser & White, 1980), even in the absence of extracellular Na+ (Gerencser, 1983). Lending strength to this hypothesis, Gerencser & Lee (1983, 1985a) demonstrated the existence of a CU-stimulated ATPase activity in Aplysia enterocyte plasma membranes, suggesting a cause-and-effect relationship between ATPase activity and Cl− transport. The ATPase activity stimulated by Cl− was strongly inhibited by acetazolamide. In addition, Gerencser (1984b) and Gerencser & Lee (1985b) have demonstrated an ATP-dependent Cl− uptake in Aplysia inside-out enterocyte plasma membrane vesicles (EPMV). Therefore, the present study was undertaken to assess the effect of acetazolamide on the ATP-driven Cl− uptake mechanism in EPMV..
Seahares (Aplysia californica) were obtained from Marinus Inc. (Westchester, CA) and were maintained at 25 °C in circulating filtered seawater. Adult Aplysia (600-1000 g) were used in these experiments. The plasma membrane vesicles were prepared from Aplysia intestinal enterocytes by homogenization and differential and discontinuous sucrose density-gradient centrifugation techniques as described previously (Gerencser & Lee, 1985a). Vesicle transport experiments were also performed as previously described (Gerencser & Lee, 1985b).
Effects of Ionic Environment on Viscosity of Catch Connective Tissue in Holothurian Body Wall
Authors: Hayashi Yutaka , Motokawa Tatsuo 
Published: April 2021

ABSTRACT
The effects of cations (H+, Na+, K+, Ca2+, Mg2+) on the mechanical properties of the catch connective tissue in the dermis of a sea cucumber, Holothuria leucospilota Brandt, were studied. The manipulation of the ionic environment caused rapid (apparent in minutes) and reversible viscosity change. Artificial sea water (ASW) with a high concentration of Ca2+ (50 mmol 1−’) increased the normal viscosity 9 times; Ca2+-free ASW decreased it to one-tenth. Ca2+ was the only ion which caused a viscosity change whose range was as large as the range of the viscosity distribution of the dermis in ASW. Manipulation of the concentration of other ions caused an increase in viscosity. An increase of more than five-fold was observed in the following solutions: ASW with acidic (pH 4) or basic (pH 9, 10) pH ; Na+-free ASW whose Na+ was replaced by either sucrose or choline; ASW with high (100mmoll−1) concentration of K+; ASW with low (0 mmol 1−1) or high (250 mmol 1−1) concentrations of Mg2+. The dermis contracted in distilled water, although this tissue contained no muscle cells.
Salt and Water Balance In the Spider, Porrhothele Antipodiana (Mygalomorpha: Dipluridae): Effects of Feeding Upon Hydrated Animals
Authors: Butt A. G. , Taylor H. H. 
Published: April 2021

ABSTRACT
The spider, Porrhothele antipodiana, starved and provided with water, produced urine via the anal excretory system (Malpighian tubules, midgut diverticula and stercoral pocket) at a mean rate of about 2·5-μlg-1 day-1 and with a mean Na+/K+ ratio of about 1·0. Salts ingested from the prey were eliminated by two mechanisms. A K+-rich (Na+/K+ about 0·2) anal diuresis lasted about 3 days following a single meal and was maintained at more than 30μg-1 day-1 during feeding ad libitum. The second mechanism, interpreted as coxal secretion, functioned only during feeding itself and delivered Na+ into the prey at a constant rate of about 3 %h-1 of total body Na+. This progressively raised the Na+/K+ ratio of the prey debris from 0·47 to 0·96 and, because of re-ingestion, recycled more Na+ than was originally present in the prey.
Feeding was associated with large net increases in dry weight and ions, particularly K+, which were mainly stored in the diverticular tissue (midgut diverticula and Malpighian tubules embedded in adipose tissue). The stercoral fluid (final urine) was slightly hyposmotic to the haemolymph in starved and fed spiders. Only about half of its osmolarity was accounted for by Na+, K+ and Cl-. The volume of water gained from the meal was about equal to that lost in diuresis, and P. antipodiana drinks to maintain water balance because of relatively high transpirational and other losses. The primary function of the diuresis is probably elimination of ions from the meal, and not volume regulation.
Localization and release of FMRFamide-like immunoreactivity in the cerebral neuroendocrine system of Manduca sexta
Authors: Carroll L. S. , Carrow G. M. , Calabrese R. L. 
Published: April 2021

ABSTRACT
The distribution of FMRFamide-like immunoreactivity (FLI) in the cerebral neuroendocrine system of the moth, Manduca sexta, is described and evidence is provided for calcium-dependent release of FLI from the neurohaemal organs.
FLI was detected by indirect immunofluorescence in approximately 25 bilaterally symmetrical pairs of somata in the pupal protocerebrum. In addition, FLI was observed in neurites in the brain, as well as in axons of the nervi corporis cardiaci and nervi corporis allati, and in terminals in the neurohaemal corpora cardiaca (CC) and corpora allata (CA). All immunocytochemical staining was blocked by preabsorption of the anti-FMRFamide antiserum with synthetic FMRFamide. We localized FLI to identified protocerebral neurosecretory cells (NSCs) by combining intracellular injection of Lucifer Yellow and indirect immunofluorescence. Among the NSCs in each hemisphere, FLI was observed in both group Ila (lateral) cells, in most group lib (lateral) cells, and in two cells of group lb (medial). FLI was extracted from the brain and neurohaemal organs and measured using radioimmunoassay (RIA). Calcium-dependent release of FLI was evoked from isolated CC-CA by high potassium depolarization in vitro and was quantified by RIA of the bathing medium.
These results suggest that FLI may have a neurohormonal or neurotransmitter function in Manduca.
Diving behaviour and heart rate in tufted ducks (Aythya fuligula)
Authors: Stephenson R. , Butler P. J. , Woakes A. J. 
Published: April 2021

ABSTRACT
Diving behaviour and heart rate were monitored in tufted ducks diving under circumstances which simulated various environmental conditions such as feeding under ice in winter.
When distance to food was increased on a covered outdoor pond, dive duration increased proportionately, but it was calculated that time available for feeding was reduced during the longer-distance ‘extended’ dives. There was a gradual reduction in heart rate to 77·3 ± 13·8 beats min-1, which is significantly lower than the resting value of 121·1 ± 14·1 beats min-1, during the course of extended dives, suggesting that the ducks could gradually switch over to a ‘classical’ oxygen-conserving response during these prolonged voluntary dives. The duration of the pre-dive preparatory period was positively correlated with dive distance.
When the ducks were briefly unable to resurface during an otherwise normal feeding dive in an indoor tank, a situation which may occur if they become dis-oriented under ice, there was an immediate switch to a full bradycardia. Reduction in heart rate during these ‘enclosed’ dives occurred only when the ducks were apparently aware of the situation and the rate of onset of bradycardia was very similar to that previously observed during involuntary submersion of tufted ducks. Minimum heart rate was the same at 46 beats min-1 after 15 s of enclosed dives and after 30 s of involuntary submersions, despite the differences in levels of activity in the two situations.