bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Solar Radiation and Wind Speed on Metabolic Heat Production by Two Mammals With Contrasting Coat Colours
Authors: Walsberg Glenn E. , Wolf Blair O. 
Published: April 2021

ABSTRACT
We report the first empirical data describing the interactive effects of simultaneous changes in irradiance and convection on energy expenditure by live mammals. Whole-animal rates of solar heat gain and convective heat loss were measured for representatives of two ground squirrel species, Spermophilus lateralis and Spermophilus saturatus, that contrast in coloration. Radiative heat gain was quantified as the decrease in metabolic heat production caused by the animal’s exposure to simulated solar radiation. Changes in convective heat loss were quantified as the variation in metabolic heat production caused by changes in wind speed. For both species, exposure to 780W m-2 of simulated solar radiation significantly reduced metabolic heat production at all wind speeds measured. Reductions were greatest at lower wind speeds, reaching 42 % in S. lateralis and 29 % in S. saturatus. Solar heat gain, expressed per unit body surface area, did not differ significantly between the two species. This heat gain equalled 14–21 % of the radiant energy intercepted by S. lateralis and 18–22 % of that intercepted by S. saturatus. Body resistance, an index of animal insulation, declined by only 10 % in S. saturatus and 13 % in S. lateralis as wind speed increased from 0.5 to 4.0 m s-1. These data demonstrate that solar heat gain can be essentially constant, despite marked differences in animal coloration, and that variable exposure to wind and sunlight can have important consequences for both thermoregulatory stress experienced by animals and their patterns of energy allocation.
Octopaminergic Dorsal Unpaired Median (Dum) Neurones Innervating the Colleterial Glands of the Female Cockroach Periplaneta Americana
Authors: Sinakevitch I. G. , Geffard M. , Pelhate M. , Lapied B. 
Published: April 2021

ABSTRACT
The musculature of the colleterial glands receives innervation from branch 4B4a of the nerves designated 4B, which arise from the posterior part of the terminal abdominal ganglion in the female cockroach Periplaneta americana (L). Using Methylene Blue staining, the gross anatomy of the colleterial gland innervation has been described. Cobalt backfilling via branch 4B4 of nerve 4B revealed about 21 dorsal unpaired median (DUM) neurones located on both median and posterior parts of the terminal abdominal ganglion. Octopamine immunohistochemistry has shown that at least 15 octopamine-immunoreactive DUM neurones from median and posterior groups projected via branch 4B4a to the left and right colleterial glands. These data, together with results reporting the presence of octopamine-immunoreactive branches supplying these colleterial glands, make octopaminergic DUM neurones suitable candidates to modulate the muscle activity of the colleterial glands in female Periplaneta americana.
Ammonia and Urea Metabolism in Relation to Gill Function and Acid–Base Balance in A Marine Elasmobranch, the Spiny Dogfish (Squalus Acanthias)
Authors: Wood Chris. M. , Pärt Peter , Wright Patricia A. 
Published: April 2021

ABSTRACT
Nitrogenous waste excretion in resting dogfish occurred largely (&gt;90 %) as urea-nitrogen (urea-N) efflux across the gills, with a very small urea efflux via the kidney. Ammonia excretion, almost entirely at the gills, accounted for less than 3 % of total nitrogen excretion. Given the extremely high blood urea levels (approximately 640 mmol-N l−1) ‘retained’ for osmoregulation, and blood ammonia levels (approximately 80 μmol-N l−1) comparable to those of teleosts, the gills of resting dogfish were exceptionally impermeable to both urea and ammonia. Experiments investigated the origins of these low permeabilities and the responses of urea-N and ammonia-N excretion and acid–base status to 6 h infusions with iso-osmotic solutions of NaCl (control), NH4Cl, NaHCO3, urea and its analogues thiourea and acetamide. NaCl had no effects, whereas NH4Cl loading caused intense acidosis and marked elevation of acidic equivalent, ammonia-N and urea-N excretion rates, the latter despite unchanged blood levels of urea-N. Apparent branchial ammonia permeability increased greatly. Acidosis resulted from both stimulated urea production and branchial NH3 loss, the former making the larger contribution. NaHCO3 loading caused intense alkalosis, a marked elevation of basic equivalent excretion and a moderate stimulation of urea-N excretion. Blood urea-N levels were again unchanged. Infusion of urea itself raised blood urea-N levels, but initially reduced branchial urea-N excretion. Acetamide and thiourea infusions both moderately elevated branchial urea-N excretion. We suggest that the low ammonia permeability may arise metabolically from an ammonia scavenging system in the gills, that a ‘back-transport’ mechanism in the gills may contribute to the low urea permeability, and that the dissociation between blood urea-N levels and excretion rates may reflect urea production at extrahepatic sites. These studies demonstrate that urea synthesis in the dogfish is linked more to nitrogen availability than to acid–base status.
Effects of Feeding and Confinement on Nitrogen Metabolism and Excretion in the Gulf Toadfish Opsanus Beta
Authors: Walsh Patrick J. , Milligan C. Louise 
Published: April 2021

ABSTRACT
In order to elucidate further the cues for, and the biochemical mechanisms of, the transition to ureogenesis in the gulf toadfish Opsanus beta, experiments on the effects of feeding (i.e. nitrogen loading) were carried out. Baseline nitrogen excretion rates were first measured on solitary toadfish in large water volumes (i.e. unconfined conditions). These nitrogen excretion rates were higher, and had a higher proportion as ammonia (61 %), than previously published ‘control’ measurements. Feeding of unconfined toadfish elevated total nitrogen excretion approximately threefold, with little change in the proportion of urea versus ammonia. During the first 24 h of confinement of unfed toadfish, absolute levels of urea excretion remained constant while ammonia excretion rates fell to near zero, so that toadfish became 90 % ureotelic. When fed prior to confinement, urea excretion rates remained constant for the first 24 h, and the bulk of the nitrogen was excreted as ammonia (80 %); excretion of the excess dietary nitrogen took up to 48 h to complete. If pre-adapted to confinement and then fed, toadfish excreted only about 55 % of their nitrogenous waste as ammonia, and excretion of excess dietary nitrogen was completed by 24 h. Elevations of hepatic glutamine synthetase (GNS) activities accompanied confinement and were shown to be almost exclusively in the cytosolic compartment and to be correlated with a decrease in the ratio of hepatic levels of glutamate:glutamine. These GNS activity increases also appear to account in part for the decrease in the percentage of ammoniotely in toadfish under conditions of nitrogen loading after confinement. However, additional means of regulating total nitrogen excretion (e.g. changes in protein turnover rates) and the degree of ureogenesis versus ammoniogenesis (e.g. N-acetylglutamate stimulation of carbamoylphosphate synthetase) must be postulated to account fully for changes in nitrogen excretion rates and activation of ureogenesis under some circumstances.
Hydroplaning by Ducklings: Overcoming Limitations to Swimming at the Water Surface
Authors: Aigeldinger Terrye L. , Fish Frank E. 
Published: April 2021

ABSTRACT
Rapid escape behavior by mallard (Anas platyrhynchos) ducklings is restricted to burst swimming at the water surface. Maximum speed may be limited because of the pattern of waves created as the duckling’s body moves through the water (hull speed). Burst speeds for 9-day-old ducklings were compared with predicted hull speeds, based on the waterline length of ducklings either resting in water or actively swimming. Kinematic analysis of video tapes showed a mean maximum burst speed of 1.73 m s-1, which was four times greater than the predicted hull speed. At burst velocities, stroke frequency was 1.9 times higher than the stroke frequency measured during steady low-speed paddling. Transition to burst speeds from steady paddling occurred near predicted hull speed. The paddling motions of the webbed feet were used to generate both thrust and lift. By using lift to raise the body above the water surface, the influence of waves in restricting maximum swimming speed is negated. The duckling’s body becomes a planing type of hull and skims on the water surface.
Small-Diameter White Myotomal Muscle Fibres Associated With Growth Hyperplasia in the Carp (Cyprinus Carpio) ExPress a Distinct Myosin Heavy Chain Gene
Authors: Ennion Steven , Gauvry Laurent , Butterworth Peter , Goldspink Geoffrey 
Published: April 2021

ABSTRACT
A carp myosin heavy chain gene isoform was isolated from a genomic clone, restriction mapped and partially sequenced to reveal the location of various exons. The clone contains a complete gene of approximately 12.0 kb which is half the size of the corresponding mammalian and avian myosin heavy chain genes. The mRNA transcript of this gene, however, is the same size as mammalian and avian striated muscle myosin heavy chain genes (about 6000 nucleotides), illustrating that the difference in size at the genomic level is due to shorter introns. A 169 bp NsiI restriction fragment containing only the 3′ untranslated region of this gene was subcloned and used as an isoform-specific probe to study the expression of this particular isoform. Hybridisation analysis could only detect expression of this myosin heavy chain gene in the white muscle of adult carp that had been subjected to an increased environmental temperature. No expression of this gene was detected in carp under 1 year of age. In situ hybridisation demonstrated that expression of this gene is limited to small-diameter white muscle fibres of adult carp, which are thought to be responsible for muscle growth by fibre hyperplasia.
Fluid Reabsorption And Ion Transport By The Lower Malpighian Tubules Of Adult Female Drosophila
Authors: O’Donnell Michael J. , Maddrell Simon H. P. 
Published: April 2021

ABSTRACT
The properties of the Malpighian tubules of Drosophila melanogaster change along their length. The upstream main segments secrete K+-rich fluid at a high rate. From this, the lower tubules reabsorb significant amounts of water and K+. Under stimulation, K+ reabsorption is accelerated. In addition, the lower tubules acidify the fluid passed to them by the main segments and secrete Ca2+ into it, adding to that transported there by the upstream epithelium. In contrast to the lumen-positive transepithelial potential difference (TEP) of the main segments, the TEP in the lower tubules is much lower and becomes lumen-negative close to their downstream junction with the common ureter. We suggest that the role of the lower tubule is to reduce the flow of K+-rich fluid that passes to the hindgut; this allows the hindgut to process the flow of excretory fluid more thoroughly.
The Moment of Inertia of Bird Wings and the Inertial Power Requirement for Flapping Flight
Authors: Berg Coen Van Den , Rayner Jeremy M. V. 
Published: April 2021

ABSTRACT
The agility and manoeuvrability of a flying animal and the inertial power required to flap the wings are related to the moment of inertia of the wings. The moments of inertia of the wings of 29 bird species and three bat species were determined using wing strip analysis. We also measured wing length, wing span, wing area, wing mass and body mass. A strong correlation (r2=0.997) was found between the moment of inertia and the product of wing mass and the square of wing length. Using this relationship, it was found that all birds that use their wings for underwater flight had a higher than average moment of inertia. Assuming sinusoidal wing movement, the inertial power requirement was found to be proportional to (body mass)0.799, an exponent close to literature values for both metabolic power output and minimum power required for flight. Ignoring wing retraction, a fairly approximate estimate showed that the inertial power required is 11–15 % of the minimum flight power. If the kinetic energy of the wings is partly converted into aerodynamic (useful) work at stroke reversal, the power loss due to inertial effects may be smaller.
An Elaborate Tension Receptor System Highlights Sensory Complexity in the Hind Leg of the Locust
Authors: Matheson Thomas , Field Laurence H. 
Published: April 2021

ABSTRACT
The tibia of each leg of the locust is moved by two antagonistic muscles, the extensor and flexor tibiae. A variety of sense organs on and in each leg provide feedback about this joint’s position and movement and about forces acting on the exoskeleton and muscles. One such organ is a muscle tension receptor found within the flexor tibiae muscle of the mesothoracic leg. We now show that an apparently homologous multipolar receptor is present in the hind leg, but that here it is associated with a specialised flexor muscle, the accessory flexor. This muscle comprises 13 fibres, innervated by five of the thirteen motor neurones that innervate the main flexor muscle and, since these are slow motor units, the response properties of the receptor are constrained. The multipolar receptor attaches to the muscle fibres near their proximal insertion onto the femoral cuticle. It generally has four primary dendrites, which do not branch extensively within the muscle.
We show that the receptor responds strongly to active, isometric contractions but only poorly to imposed changes of accessory flexor muscle length (i.e. passive changes in tibial position). It does not respond to tension generated by the main flexor muscle or by the extensor muscle. The tension receptor causes short-latency (0.9–1.8 ms) excitatory inputs onto the three common inhibitory motor neurones and longer-latency (3.7–8.1 ms) inhibitory inputs onto the slow extensor tibiae motor neurone. In quiescent animals, it causes excitatory inputs onto flexor tibiae motor neurones (2.2–3.8 ms) but, in more active animals, its inputs onto these neurones are often inhibitory, with delays of 6–10 ms.
The slow nature of the accessory flexor muscle and the pattern of central connections of the receptor suggest that together they are involved in the control of slow movements or posture, potentially acting through a servomechanism.
Ventilation and pulmonary Gas Exchange During Exercise in the Savannah Monitor Lizard (Varanus Exanthematicus)
Authors: Hopkins S. R. , Hicks J. W. , Cooper T. K. , Powell F. L. 
Published: April 2021

ABSTRACT
During exercise, pulmonary gas exchange in reptiles was predicted to differ from that in mammals because of their less complex lung structure, which might reduce ventilation–perfusion heterogeneity at the expense of pulmonary diffusion limitation. To investigate this, the multiple inert gas elimination technique was used in six Varanus exanthematicus at rest and during maximal exercise. Trace amounts of six inert gases were infused into the external jugular vein and blood samples were collected from the pulmonary artery and the left atrium. Mixed expired gas samples and ventilatory and metabolic data were acquired. Indices of heterogeneity, calculated using a 50-compartment model, were low at rest (log standard deviation of perfusion distribution, logSDQ⨗=0.39) and increased significantly with exercise (logSDQ⨗=0.78). Oxygen diffusion limitation was apparent during exercise and was comparable to reported mammalian values. A molecular-mass-dependent limitation, suggesting limited intrapulmonary gas mixing, was evident only at rest. An increase in left atrial from 82 mmHg at rest to 96 mmHg during exercise was associated with a corresponding decrease in . These data indicate adequacy of pulmonary ventilation and gas exchange for metabolic demands in exercising varanid lizards and suggest that less complex lung structures are not necessarily linked to increased pulmonary diffusion limitation.
Taurine Metabolism In Larvae Of Marine Molluscs (Bivalvia, Gastropoda)
Authors: Welborn J. R. , Manahan D. T. 
Published: April 2021

ABSTRACT
Nonfeeding larvae of the gastropod Haliotis rufescens maintained a constant amount of taurine during embryonic and larval development and, since no de novo synthesis of taurine was observed in these larvae, the maternal endowment of taurine to the egg was sufficient for larval development to metamorphosis. In contrast, feeding larvae of the bivalve Crassostrea gigas increased their taurine content by a factor of 43 during growth to metamorphosis (from 86 to 311 μm, valve length). Taurine was not present in algae used to feed the larvae, suggesting that de novo synthesis of taurine by the larvae met their requirements. In unfed larvae, cysteic acid, cysteine sulfinic acid and hypotaurine were labeled from a [35S]cysteine precursor, but taurine was not. Hyperosmotic treatment (from 33 ‰ to 44 ‰ salinity for up to 3 h) did not induce taurine synthesis in unfed larvae. However, larvae fed the alga Isochrysis galbana up-regulated their taurine synthesis from [35S]cysteine by a factor of 11 (fed, 11.7±2.2 fmol taurine larva-1 h-1; unfed controls, 1.08±0.33 fmol taurine larva-1 h-1; means ± S.E.M.). Fed larvae also synthesized taurine from [35S]methionine (18.4 fmol larva-1 h-1). I. galbana contained 5 fmol cell-1 of cysteine and methionine (combined) and, based on known feeding rates, we calculated that there were sufficient taurine precursors in the algae to supply the taurine requirements of growing larvae. The lack of significant de novo taurine synthesis reported for adult bivalve molluscs has led to the conclusion that taurine is a dietary requirement. Our findings for larval forms differ in that there is significant de novo synthesis of taurine during development.
The Mechanical Power Output and Hydromechanical Efficiency of Northern Pike (Esox Lucius) Fast-Starts
Authors: Frith H. Russ , Blake Robert W. 
Published: April 2021

ABSTRACT
The mechanical power output and hydrodynamic efficiency of northern pike, Esox lucius, during acceleration from rest (fast-start) are calculated from hydrodynamic theory for two kinematic patterns, C-starts (used in escape) and S-starts (used in prey capture). The Weihs model is employed and modified to calculate the mechanical power produced by a fish during a fast-start. A term is included for the power required to accelerate body sections laterally. Lateral deceleration of fish body sections and their associated added mass are expressed as an active process requiring energy expenditure or as a passive process requiring no energy expenditure. In addition, two methods of calculating useful power (the power used to accelerate the virtual mass of the fish, i.e. fish body mass + longitudinal added mass, in the direction of motion), one derived from the Weihs model and the second by summing the changes in kinetic energy of the virtual mass of the fish during a fast-start, are compared and found to give similar estimates of useful power (not significantly different; differences average 22 %).
Comparisons of the kinematics and performance of C-and S-starts reveal that C-starts are consistently terminated after two tail flips (stages 1 and 2) whereas S-starts continue for 3–6 tail flips (stages 3–6). In addition, acceleration during C-starts is more rapid and velocities are higher (2.3–2.8 m s−1) than during S-starts (0.8–1.8 m s−1) over the first 100 ms. However, the peak velocities achieved during S-starts and C-starts are similar over the duration of a fast-start. The superior acceleration rates achieved during the initial stages of a C-start can be explained, in part, by the use of greater maximum angles of attack, higher lateral and perpendicular velocities and larger maximum forces by the caudal fin.
Hydrodynamic efficiencies for fast-starts range from 0.16 to 0.39, values that are lower than those observed during either burst-and-coast or steady swimming. Efficiencies are lower for S-starts than for C-starts during the first two tail beats. S-start efficiencies increase with each subsequent tail flip and the maximum efficiencies realised are similar to those achieved during C-starts.
Power output during C-and S-starts (449.0 and 394.9 W kg−1 muscle fibre, respectively) approaches the theoretical maximum for vertebrate striated muscle (500 W kg−1). Also, the inferred muscle stress is close to the predicted optimum for maximum power output, at 30 % of the maximum isometric stress recorded for isolated fast muscle fibres. These measurements suggest that fast-start performance is near a physiological limit and is probably constrained by muscle function. The superior acceleration rates achieved by C-starts over S-starts are explained in part by differences in hydrodynamic efficiency, whereas power outputs are similar.
Osmotic and Thermal Effects on In Situ Atpase Activity in Permeabilized Gill Epithelial Cells of the Fish Gillichthys Mirabilis
Authors: Kültz Dietmar , Somero George N. 
Published: April 2021

ABSTRACT
Long-jawed mudsuckers (Gillichthys mirabilis) were acclimated to sea water (SW) at 7 °C, SW at 26 °C or dilute sea water (DSW) at 26 °C for 5 months. Gill cells were isolated and the proportion of mitochondria-rich (MR) cells was determined. The number of cells harvested amounted to 4.7X107±0.6X107 to 10.6X107±1.1X107 and the yield was between 7.1X108±0.6X108 and 10.7X108±1.4X108 cells g-1 gill epithelial mass. Cell viability was 96.8±0.4 to 97.8±0.6 %. The number, size and volume of MR cells decreased significantly during DSW acclimation, but did not change during thermal acclimation. The protein content was not influenced by osmotic or thermal acclimation and ranged between 20.0±1.6 and 22.1±1.5 pg cell−1. Using a new method, which is based on the formation of plasma membrane channels by alamethicin, we were able to permeabilize gill cells. For the first time, the Na+/K+-ATPase and H+-ATPase activities of fish gills were determined in intact cells in situ. The activity of both ATPases was dependent on alamethicin concentration (optimum 100 μg mg−1 protein) and on preincubation time (optimum 10 min). The in situ activity of both ATPases was influenced by osmotic, but not thermal, acclimation. A positive linear correlation was found between in situ Na+/K+-ATPase activity and total MR cell volume. However, we show, for the first time, that a negative linear correlation exists between H+-ATPase activity and total MR cell volume, suggesting a localization of H+-ATPase in pavement cells. In permeabilized cells, the activity of both ATPases was 2.6–3.9 times higher than that of crude homogenates and 1.6–2.1 times higher than that of permeabilized homogenate vesicles. We hypothesize that in crude homogenates three-quarters of Na+/K+-ATPase and two-thirds of H+-ATPase activity are not detectable both because of a mixture of inside-out and right-side-out vesicles and because of the disruption of membrane and enzyme integrity.