bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serotonin-Mediated Release of Catecholamines in the Rainbow Trout Oncorhynchus Mykiss
Authors: Fritsche Regina , Reid Steve G. , Thomas Serge , Perry Steve F. 
Published: April 2021

ABSTRACT
The effects of serotonin (5-hydroxytryptamine; 5-HT) on catecholamine release from chromaffin tissue were investigated in the rainbow trout (Oncorhynchus mykiss) in vivo and in situ. Intra-arterial injections of serotonin in vivo caused dose-dependent (50–250nmolkg−1) increases in both plasma noradrenaline and adrenaline levels. Pre-treatment of fish with the serotonergic receptor antagonist methysergide did not abolish these increases.
An in situ saline-perfused head kidney preparation was developed and validated to study the potential direct effect of serotonin on catecholamine release. The chromaffin cells in the preparation showed a dose-dependent release of catecholamines in response to bolus injections of the cholinergic receptor agonist carbachol (10−7–10−4 molkg-1). The carbachol-induced release of noradrenaline, but not of adrenaline, was reduced significantly when the nicotinic receptor antagonist hexamethonium (10−4 mol l−1) was present in the perfusion fluid. The removal of calcium from the perfusion fluid prevented the usual release of catecholamines evoked by carbachol.
Bolus injections of serotonin (250nmolkg−1) into the inflowing perfusion fluid resulted in significantly increased levels of adrenaline and noradrenaline in the outflowing perfusate. Addition of hexamethonium to the perfusion fluid did not abolish this serotonin-induced release of catecholamines. The serotonin-induced release of adrenaline, however, was abolished totally by the addition of methysergide. Serotonin is present in high concentrations (44.61±5.96 μgg−1 tissue) in the anterior region of the posterior cardinal vein within the head kidney. Carbachol (10−5 molkg−1) did not elicit release of the stored serotonin from the perfused head kidney preparation.
We conclude that the chromaffin cells in the perfused trout head kidney preparation display characteristics similar to those of other vertebrates and that this preparation is a useful tool for studying the control of catecholamine release in fish. The results demonstrate that serotonin has a direct impact on the chromaffin cells by interacting with methysergide-sensitive receptors to initiate the release of adrenaline. The potential physiological role of serotonin on catecholamine release in trout is discussed.
The Effects of Manduca Sexta Diuretic Hormone on Fluid Transport by the Malpighian Tubules and Cryptonephric Complex of Manduca Sexta
Authors: Audsley Neil , Coast Geoffrey M. , Schooley David A. 
Published: April 2021

ABSTRACT
Manduca sexta diuretic hormone (Mas-DH) stimulates fluid secretion by adult Malpighian tubules of M. sexta, demonstrating its site of diuretic action in M. sexta for the first time. It was not possible to develop a suitable bioassay to measure fluid secretion in larval proximal tubules. Mas-DH has an antidiuretic action on the cryptonephric complex of larval M. sexta because it increases fluid absorption from the rectum. It appears that in this complex Mas-DH is acting on a Na+/K+/2Cl− co-transporter, presumably on the basal membrane of the cryptonephric Malpighian tubules, because Mas-DH-stimulated fluid absorption by the cryptonephric complex is inhibited by bumetanide or the removal of Cl-, Na+ or K+ from the haemolymph side of the tissue. This is the first demonstration of hormonal control of fluid absorption by the cryptonephric complex. Concomitant with the stimulation of fluid transport, Mas-DH increases the amount of cyclic AMP secreted by adult Malpighian tubules and the cryptonephric complex. In addition, Mas-DH promotes cyclic AMP production by the larval proximal tubules.
A Comparison of Avian and Reptilian Chorioallantoic Vascular Density
Authors: Birchard Geoffrey F. , Reiber Carl L. 
Published: April 2021

ABSTRACT
Oviparous amniotes exchange respiratory gases across a specialized vascular membrane, the chorioallantois. Although many investigations into the physiology of amniote eggs, particularly those of the chicken, have been carried out, there is no comparative information about the chorioallantoic membrane. Given the differences in size and phylogeny, it might be expected that significant morphological differences exist in this gas-exchange organ.
Ecological Correlates of Hovering Flight of Hummingbirds
Authors: Wells Dominic J. 
Published: April 2021

ABSTRACT
Simultaneous recordings of oxygen consumption and wing kinematics were collected from hummingbirds hovering at artificial flowers of different dimensions or when loaded by the addition of small weights to simulate increased fat stores. Hovering at wide-diameter flowers required increased wingbeat frequencies to compensate for decreased wingbeat amplitude, and it was 5% more metabolically expensive than at narrow flowers. Loaded birds increased their wingbeat amplitude to support the extra load whilst maintaining a nearly constant wingbeat frequency. A 10% increase in load required a 5.7% increase in mass-specific oxygen consumption. Although the variation in wing kinematics was associated with an increased metabolic cost, there was very little effect on flight efficiency. This ability to vary wing kinematics allows hummingbirds to exploit a wide range of flower types and to accommodate increased energy stores for seasonal migration.
Exhaustive Exercise in the Sea Lamprey (Petromyzon Marinus): Relationship Between Anaerobic Metabolism and Intracellular Acid–Base Balance
Authors: Boutilier R. G. , Ferguson R. A. , Henry R. P. , Tufts B. L. 
Published: April 2021

ABSTRACT
We measured intracellular acid–base balance and indicators of carbohydrate and high-energy phosphate metabolism as lampreys recovered from exhaustive exercise.
A combined respiratory and metabolic acidosis was observed in the locomotory muscle following ‘burst’ exercise. Muscle pH decreased from approximately 7.2 to 6.7, whereas intracellular rose from approximately 0.6 to 1.6kPa. Unlike the situation in similarly stressed teleost fish such as rainbow trout, the respiratory acidosis in muscle persisted for several hours. This apparent CO2 retention in lamprey muscle may be the result of a restricted ability of the circulatory system to transport CO2 due to reduced erythrocyte anion exchange, or it could represent a restricted ability of the muscle itself to clear the intracellular pool of CO2 due to reduced carbonic anhydrase activity.
Maximal lactate dehydrogenase activity of lamprey muscle exhibited a marked dependence on pH, increasing in activity by 30% as pH decreased from 7.2 to 6.7 (reflecting the ‘resting’ to ‘post-exercise’ pH change observed invivo).
Following exhaustive exercise, the acid–base balance of the muscle is influenced by both proton-consuming (e.g. AMP deamination, glycogen replenishment) and proton-producing (e.g. rephosphorylation of creatine) metabolic processes. The net effect is that, although intracellular pH is maximally depressed, energy stores such as phosphocreatine and glycogen are partially restored within 1h of exhaustive exercise, placing the animal in good stead for further locomotory work.
The Effect Of Solid And Porous Channel Walls On Steady Swimming Of Steelhead Trout Oncorhynchus Mykiss
Authors: Webb Paul W. 
Published: April 2021

ABSTRACT
Kinematics and steady swimming performance were recorded for steelhead trout (approximately 12.2cm in total length) swimming in channels 4.5, 3 and 1.6cm wide in the centre of a flume 15cm wide. Channel walls were solid or porous. Tail-beat depth and the length of the propulsive wave were not affected by spacing of either solid or porous walls. The product of tail-beat frequency, F, and amplitude, H, was related to swimming speed, u, and to harmonic mean distance of the tail from the wall, z. For solid walls:

and for grid walls:

where ±2 S.E. are shown for regression coefficients. Thus, rates of working were smaller for fish swimming between solid walls, but the reduction due to wall effects decreased with increasing swimming speed. Porous grid walls had less effect on kinematics, except at low swimming speeds. Spacing of solid walls did not affect maximum tail-beat frequency, but maximum tail-beat amplitude decreased with smaller wall widths. Maximum tail-beat amplitude similarly decreased with spacing between grid walls, but maximum tail-beat frequency increased. Walls also reduced maximum swimming speed. Wall effects have not been adequately taken into account in most studies of fish swimming in flumes and fish wheels.
The Body Temperature of the Frog
Authors: Mellanby Kenneth 
Published: April 2021

ABSTRACT
Under most conditions the amount of metabolic heat produced by a frog is so small that the animal behaves like a non-living system and its temperature is controlled by external physical conditions.
The frog’s skin is so permeable that when the animal is exposed to moderately rapidly moving air (1 m. per sec. or over) evaporation reduces its internal temperature to the wet-bulb temperature.
About 25 % of the frog’s weight may be lost by evaporation before death ensues. After death water continues to evaporate at the same rapid rate until 50 % of the animal’s weight is lost.
On Oviposition, Olfactory Conditioning and Host Selection in Rhizopertha Dominica Fab. (Insecta, Coleoptera)
Authors: Crombie A. C. 
Published: April 2021

ABSTRACT
The senses used in food finding and the factors inducing oviposition in Rhizo-pertha dominica (Fab.), a Bostrichid beetle pest of stored grain, were investigated. The sense of smell appears to be the most important in leading the animal to an environment where food is present. Responses were obtained in an olfactometer with maize, wheat, oats and barley and with different extracts of wheat and maize. The use of the sense of sight was also investigated.
Once within an environment having the odour of food the sense of touch appears to be paramount in the selection of oviposition site. The influence of size, shape and texture were investigated. But in the absence of appropriate patterns of stimuli involving both olfactory and tactile sensations, restraint from ovippsition was exercised.
No predilection was shown for oviposition or feeding in the food in which they were reared as larvae. Neither did the larvae especially choose for entry substances in which their parents have been reared.
The animal can be made tolerant to the odour of peppermint instead of repelled by it in an olfactometer by exposing the adults to the odour of peppermint for a few weeks. The effect wears off after 10-14 days’ isolation from peppermint in wheat.
Olfactory receptors which appear to be located on the antennae and legs were used in both food-finding and recognition of the opposite sex.
A list is given of the substances in which the animal was reared.
The bearing of these results on the problem of “gestalt” in conditioning, and on changes in habit in economic insects, is discussed.
Osmotic Behaviour of the Fairy Shrimp Chirocephalus Diaphanus Prévost
Authors: Panikkar N. Kesava 
Published: April 2021

ABSTRACT
Nothing is known of the osmotic concentration of the blood of fresh-water phyllopods. In the cladoceran Daphnia magna, Fritzsche (1917) obtained freezing-point depressions for blood varying between—0·2 and—0·67° C. Krogh (1939) did some preliminary experiments on Branchipus (.? grubii) and Apus (Lepidurus) productus and found that these animals can be kept alive without food only for a day or two, whether they are in tap water, distilled water or in Ringer/100. Regular loss of chloride occurred in all experiments, which indicated the absence of active regulation and the necessity of food to make good the constant loss of salts. Artemia, which is closely related to Branchipus, inhabits concentrated salines up to about 35 % salt and shows highly developed powers of regulation involving ability to maintain hypotonicity to the external medium. By Barger’s method, Medwedewa (1927) and Kuenen (1939) found that the osmotic pressure of its blood varied only between 1 · 2 and 2 · 6% NaCl for a change in the external medium from 4 · 7 to 17 · 7% NaCl. Chirocephalus, which belongs to the same tribe of phyllopods as Artemia and Branchipus, is an essentially fresh-water form, though by frequent drying and flooding the pools in which it lives may accumulate slight quantities of salt. Weldon (1909) found them alive in an aquarium where, by evaporation, the chloride content of water had risen up to 0 · 019% NaCl. The following experiments were performed in order to study the osmotic properties of Chirocephalus when a limited supply was available in the summer of 1940.
The Biology and Behaviour of Ptinus Tectus Boie. (Coleoptera, Ptinidae), a Pest of Stored Products
Authors: Bentley E. W. , Gunn D. L. , Ewer D. W. 
Published: April 2021

ABSTRACT
In alternating light and darkness at 25 ° C., Ptinus tectus shows a diurnal rhythm of locomotory activity with maximum activity occurring in the dark period. The rhythm is continued for a few days in continuous light.
In continuous light, no inherent 24 hr. rhythm is apparent, but in subsequent alternating light and darkness, within 1 day, activity becomes practically confined to the dark period.
The rhythm can be reversed by reversing the hours of light and darkness and the reversed rhythm is similarly continued in continuous light.
In conditions of alternating light and darkness with fluctuating temperature (10–20 ° C. with low temperature in thé dark periods) Ptinus shows greater activity than at 25 ° C., and maximum activity occurs in the cold, dark period.
In constant light and daily fluctuating temperature (17–23 ° C.), the period of greatest activity occurs when the temperature is falling. After transfer to constant temperature, this period still occurs at the same time of day for a few days.
A Comparative Study of Peripheral Inhibition in Decapod Crustaceans
Authors: Wiersma C. A. G. , Ellis C. H. 
Published: April 2021

ABSTRACT
The effectiveness with which different contractions in a number of muscles can be inhibited was investigated. As a measure of this effectiveness the frequency of inhibition which can just inhibit a contraction with a given frequency of excitation was determined. It was found that in all systems the ratio (Rc) of such inhibitory frequencies to that of the excitatory frequencies they can suppress was constant for a wide range of frequencies.
At high frequencies either the inhibition or the excitation may become less effective. This is explained by failure of the respective system to function normally at such a frequency.
The effectiveness of inhibition of different systems was determined. Some systems show a very constant Rc value; in a second group Rc varies within wider limits; and a third group shows two distinct Re’s sometimes in the same preparation at different times.
Rc values have been found to vary widely. For instance, in the bender inhibitor-slow bender system of Pachygrapsus three excitatory impulses are suppressed by one inhibitory impulse; in the closer inhibitor-slow closer system of Cambarus one excitatory impulse needs five inhibitory impulses to counteract its effect. The fast closer contraction of Cambarus and the fast closer and fast bender contraction of Pachygrapsus were found to be uninhibitable, i.e. no effect of inhibition what-soever was noticed on any of these contractions. All three systems are distinguished by giving a mechanical response to a single stimulus in contrast with all the inhibitable systems which do not respond to single impulses.
Reduction of the action potentials during inhibition is obtainable in only a few systems, namely, the opener inhibitor-opener and the stretcher inhibitor-stretcher systems of Cambarus and the crabs. (In the crabs this applies only to the ‘true1 inhibitors.) In all other systems, including every system of Panultrus, no reduction of the muscle action potential is obtained.
Carbohydrate Metabolism of Chick Fibroblasts in Vitro
Authors: Willmer E. N. 
Published: April 2021

ABSTRACT
The glucose consumption of osteoblasts growing in a medium of plasma and embryo juice has been compared with that of the same cells in plasma and Tyrode medium. Embryo juice causes an initial increased glucose consumption which later falls below the level characteristic of a Tyrode-plasma medium. A modification of a method of measuring the nucleoprotein phosphorus content of tissue cultures is described and among other data obtained the changes which occur in this figure have been noted for fourth passage chick osteoblast cultures and for fresh heart explants during the first 4 days of culture in media of plasma and Tyrode and of plasma and embryo juice. The figures for nucleoprotein content have been correlated with those for glucose consumption and lactic acid production and pronounced differences have been observed in the behaviour of the two types of tissue. The possible significance of the findings is discussed. There is no absolute correlation between high growth rate and high sugar consumption or lactic acid production. The data discussed are consistent with the idea that an increased protein metabolism, and a decreased carbohydrate metabolism result from the addition of embryo juice to osteoblast cultures. Embryo juice has no detectable effects on the carbohydrate metabolism of fresh heart cultures.
Leading Edge Section and Asymmetric Twisting in the Wings of Flying Butterflies (Insecta, Papilionoidea)
Authors: Wootton Robin J. 
Published: April 2021

ABSTRACT
Insect wings are mounted on hinges, restricting the extent to which their bases can be supinated for the upstroke. The forewings of many insects therefore include devices that allow the distal part of the wing to twist relative to the base under aerodynamic loading in the upstroke, but restrict such twisting in the downstroke where the effect would be detrimental. In the broad forewings of butterflies, this asymmetric resistance to aerodynamic twisting seems to be a consequence of the curved section of the leading edge. The wing can be modelled as a cantilevered, thin cambered plate. Torsional tests on the forewings of four butterfly species and on a paper wing of curved section confirm the effect. Differences between the results for the four species appear to fit their morphological and kinematic differences. The nature of the mechanism is outlined.
H+ -ATPase Activity in Crude Homogenates of Fish Gill Tissue: Inhibitor Sensitivity and Environmental and Hormonal Regulation
Authors: Lin Hong , Randall David J. 
Published: April 2021

ABSTRACT
N-ethymaleimide-sensitive ATPase activity was measured in crude homogenates of gill tissue from rainbow trout using a coupled-enzyme ATPase assay in the presence of EGTA, ouabain and azide. This NEM-sensitive ATPase activity, determined to be about 1.5 μmolmg−1 protein h−1 at 15°C for freshwater trout, is also inhibited by other H+-ATPase blockers such as DCCD, DES, PCMBS and bafilomycin. It is concluded, therefore, that the NEM-sensitive ATPase activity was generated by a proton-translocating ATPase. Since this NEM-sensitive ATPase was also sensitive to the plasma membrane ATPase inhibitor vanadate, we conclude that the H+-ATPase in fish gill is of the plasma membrane type. The major role of the H+-ATPase in the gill epithelium is to facilitate Na+ uptake from fresh water. Sodium concentration in the external medium was the primary regulator of the H+-ATPase in fish gills, with low sodium levels being associated with high H+-ATPase activity. High external calcium concentration had a marked stimulatory effect on H+-ATPase activity in fish gills when the sodium level was low. Environmental hypercapnia induced a 70% increase in the H+-ATPase activity in fish gills. H+-ATPase activity was also elevated in freshwater fish after chronic cortisol infusion.
Lactate Metabolism In Rainbow Trout
Authors: Milligan C. Louise , Girard Stéphane S. 
Published: April 2021

ABSTRACT
We have investigated the metabolic fate of blood lactate in resting rainbow trout and in fish recovering from a bout of exhaustive exercise. At rest and during recovery from exercise, the majority of blood lactate was oxidized, the proportion increasing with increasing oxygen consumption. It is estimated that, during recovery from exhaustive exercise, lactate released from the muscle has the potential to fuel a significant portion of oxidative metabolism. The bulk of the remaining blood lactate reappeared in the muscle lactate pool, probably via direct uptake by the muscle. There was a significant incorporation of blood lactate into the muscle glycogen pool, providing strong evidence for in situ glycogenesis as the mode for muscle glycogen replenishment. To investigate the role of the liver in blood lactate clearance, trout were functionally hepatectomized by ligation of the hepatic portal circulation. The exercise performance of hepatectomized fish was equal to that of sham-operated fish and controls, indicating that muscle relies primarily on endogenous fuel stores. Furthermore, blood lactate levels immediately after exercise were greater and muscle metabolic recovery was faster in hepatectomized fish than in sham-operated fish and controls. These observations suggest that glycogen resynthesis in trout muscle may be retarded because of a non-recoverable loss of substrate (i.e. lactate) from the muscle, because the lactate released is utilized by the liver. These results are discussed in view of what is known about these processes in other ectothermic vertebrates.
The Renin–Angiotensin System in Blood Pressure Control During Exercise in the Cod Gadus Morhua
Authors: Platzack Björn , Axelsson Michael , Nilsson Stefan 
Published: April 2021

ABSTRACT
The effects of angiotensin I, angiotensin II and exercise on ventral and dorsal aortic blood pressure and heart rate were investigated in the Atlantic cod, Gadus morhua. Both angiotensins produced a marked increase in blood pressure. After injection of the angiotensin-converting enzyme (ACE) inhibitor enalapril, both ventral and dorsal blood pressures decreased significantly and the effect of angiotensin I was abolished. This demonstrates that ACE activity is necessay for conversion of angiotensin I to angiotensin II in the cod, as in other teleosts investigated, and provides a tool for further study of angiotensin function.
During swimming exercise at 2/3 body lengths per second, ventral and dorsal aortic blood pressures increased, but this exercise hypertension was absent in fish pretreated with the α-adrenoceptor antagonist prazosin. Instead, an increase in both ventral and dorsal aortic blood pressures occurred immediately after the exercise period. This post-exercise hypertension could be abolished by injection of enalapril, suggesting that the angiotensin system is the responsible ‘anti-drop’ factor activated in the absence of a functional adrenergic vasomotor control.
We conclude that the angiotensin system provides a major contribution to the resting blood pressure regulation in the cod, and that this system can be activated to offset a decrease in arterial blood pressure.