bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glycogen Content and Release of Glucose from Red blood cells of the Sipunculan Worm Themiste Dyscrita
Authors: Ingermann Rolf L. , Virgin Garth L. 
Published: April 2021

ABSTRACT
The coelomic red blood cells, or haemocytes, of the sipunculan worm Themiste dyscrita (Fisher, 1952) were found to contain high concentrations of glycogen: the haemocytes accounted for approximately 56 % of the total glycogen in the organism. Haemocytes, incubated in a glucose-free medium in vitro, released D-glucose into the medium. At 10°C and at a physiological haematocrit, the concentration in the initially glucose-free medium reached physiological plasma levels of D-glucose (0·27 mmol l−1) in about 3 h. The cells continued to release D-glucose and the medium concentration reached about 0·65 mmol l−1 after 24 h. Cells resuspended in plasma also released D-glucose to produce medium concentrations that also appeared to exceed physiological levels. Kinetic analysis of membrane transport of D-glucose suggested that membrane transfer was not the rate-limiting step in this release. Mammalian insulin, epinephrine and glucagon were not effective in influencing D-glucose release. No reduction in the medium concentration of D-glucose could be detected when haemocytes were incubated in 2 mmol l−1 D-glucose in plasma or sea water. The results suggest that the haemocyte is involved in the glucose regulation of the organism, although the regulatory mechanism(s) remains to be elucidated. Furthermore, the results suggest that, in addition to its function in oxygen transport, the red blood cell is the principal storage tissue for glycogen in this organism.
Measurement of Host Curvature by The Parasitoid Wasp Trichogramma Minutum, and Its Effect on Host Examination and Progeny Allocation
Authors: Schmidt J. M. , Smith J. J. B. 
Published: April 2021

ABSTRACT
The parasitoid wasp Trichogramma minutum Riley (Hymenoptera: Chalcidoidea: Trichogrammatidae) adjusts its progeny allocation and host examining behaviour to the exposed volume of its host – an insect egg. The female wasp examines a potential host by walking over its surface while drumming its antennae against it, spending a longer time examining larger hosts. If wasps of different sizes are presented with glass beads of the same diameter, examining time increases significantly the larger the bead is relative to the wasp. Since the wasps’ velocities do not differ with wasp size, the total distance travelled during host examination also increases with relative host diameter.
When large and small wasps are placed on large and small hosts such that the relative curvature is constant, examining time and total path length are the same. Smaller wasps take more steps to travel the same distance, therefore the duration of the examination walk, rather than step number or relative distance, is adjusted to host curvature. This adjustment of examination time may ensure that the surface of hosts of different sizes are examined adequately, despite differences in total area.
Progeny allocation, usually dependent only on exposed host surface area, can be affected by the wasps’ measure of curvature. When hosts are mounted on the tips of thin wires rather than on the substrate, no finite cues dependent on surface area are available to the wasps. Such hosts receive only 25 % more progeny, either in the light or in total darkness, than hosts which are resting on the substrate, demonstrating that an upper limit to clutch size is set by cues dependent on curvature. The structure of the compound eyes suggests that the visual acuity of Trichogramma is insufficient to account for their ability to discriminate between small differences in host curvature. By placing large and small wasps on point-mounted hosts of fixed diameter, we show that the clutch size limit is set according to the relative size of the host.
These observations are discussed in terms of a mechanosensory mechanism of curvature measurement.
Lunar cycles of coho salmon, Oncorhynchus kisutch: I. Growth and feeding
Authors: Farbridge K. J. , Leatherland J. F. 
Published: April 2021

ABSTRACT
Coho salmon (Oncorhynchus kisutch Walbaum) parrs and smolts, maintained in a laboratory under a fixed artificial 12h light: 12h dark photoperiod from the time of hatching, exhibited a pattern of alternating periods of rapid and slow growth in body mass; the peaks and troughs in growth rate were significantly different from one another. The alternating growth rate changes were rhythmic in nature, of approximately 14 to 15 days in length.
Evidence for cyclic patterns of growth in relative length and in food consumption was also found in coho salmon parr. Peak food intake appeared to occur 2–4 days after each peak of growth in relative mass. Although the pattern of growth in relative length was less clear, there was evidence to suggest that growth in length might be out of phase with growth in mass.
There was no pattern of cycling growth rates in coho salmon parr subsampled from a common stock. The significance of this is discussed.
The data suggest that the lunar cycle acts as a Zeitgeber for synchronization of the growth rate rhythms.
Lunar Cycles of Coho Salmon, Oncorhynchus kisutch: II. Scale amino acid uptake, nucleic acids, metabolic reserves and plasma thyroid hormones
Authors: Farbridge K. J. , Leatherland J. F. 
Published: April 2021

ABSTRACT
[14C]glycine uptake by scales in vitro was measured in coho salmon (Onco- rhynchus kisutch Walbaum) smolts at different times during several semi-lunar cycles. There was a clear cyclical pattern of glycine uptake during the semi-lunar period.
Evidence for semi-lunar cycles of liver and muscle RNA:DNA ratios, carcass water content, haematocrit, and plasma triglyceride, glucose and cholesterol levels was also found in coho salmon parrs.
Plasma L-thyroxine (T4) levels exhibited a cyclical pattern during the semi-lunar cycle in parrs sampled in March when plasma T4 levels tended to be low, but no such pattern was seen in parrs sampled in January when the plasma T4 levels were relatively high (l·39–l·88 μg dl−1 in January compared with 0·38–0·83 μg dl−1 in March).
There were no apparent semi-lunar cycles in liver mass:body mass ratios and plasma triiodo-L-thyronine (T3) levels.
Changes in growth parameters (nucleic acid levels and glycine uptake by scales) and the content of nutrient reserves are discussed in relation to the semi-lunar patterns of growth in length, growth in mass, and food intake in this species.
Temperature affects the diffusion of small molecules through cytosol of fish muscle
Authors: Sidell B. D. , Hazel J. R. 
Published: April 2021

ABSTRACT
Undiluted cytosolic extracts were prepared from fast glycolytic muscle tissue of white perch (Morone americanus). Diffusion coefficients (D) through the cytosol preparations were estimated in vitro for a series of selected low molecular weight compounds using an experimental diffusion chamber. Determinations were made at 5° and 25 °C to assess thermal sensitivity of the process. Non-metabolizable analogues of naturally occurring compounds were employed to avoid chemical alteration of solutes by the catalytically competent preparations during diffusion experiments. Kinematic viscosity of cytosolic extracts, which is a major determinant of diffusive resistance, increases from 2·94 ± 0·06 to 5·35 ± 0·02 × l0−2cm2s−1 between temperatures of 25° and 5 °C (Q10 = 1·35 ± 0·01). The diffusion coefficients (D) of D-lactic acid are 2·26 ± 0·84 and 0·79 ± 0·15 × 10−6cm2S−1 at 25° and 5°C, respectively (Q10= 1·84 ± 0·36). The D values of 2-deoxyglucose are 2·87 ± 1·01 and 1·22 ± 0·36× 10−6cm2s−1 at 25° and 5°C (Q10 = 1·75 ± 0·54). The D values of Ca2+ are 2·47 ± 0·28 and 1·09 ± 0·36× 10−6cm2s−1 at 25° and 5°C (Q10 = 2·04 ± 0·36). The D values for the ATP analogue, AMP-PNP, are 0·87 ± 0·33 and 0·81 ± 0·15× 10−6cm2s−1 at 25° and 5°C (Q10 = 0·98 ± 0·12). AMP-PNP is the only compound tested which did not show significant thermal sensitivity of diffusion. Recently reported changes in muscle cell ultrastructure induced by temperature acclimation of fishes may serve to counteract the effect of temperature change on diffusion of key small molecules through the aqueous cytoplasm, thus maintaining flux rates between cellular compartments. These mechanisms may be of considerable import in achieving relative temperature independence of cellular function that is characteristic of many eurythermal aquatic animals.
Neural Control of Heart Beat in the African Giant Snail, Achatina Fulica Férussac: I. Identification of the Heart Regulatory Neurones
Authors: Furukawa Yasuo , Kobayashi Makoto 
Published: April 2021

ABSTRACT
Seven heart regulatory neurones (PON, TAN, TAN-2, TAN-3, d-RCDN, d-LCDN and VG1) were identified in the central nervous system of the African giant snail, Achatina fulica Férussac. Among these neurones, the periodically oscillating neurone (PON) was the most effective heart excitor, producing heart excitation at rather low firing frequencies. The tonically autoactive neurones (TAN, TAN-2 and TAN-3) were tonically firing neurones and their spontaneous activity was found to produce tonic heart excitation which supplemented the myogenic heart activity. There was some evidence that two cerebral ganglion cells (the dorsal right and left cerebral distinct neurones, d-RCDN and d-LCDN) were also likely to be heart excitors although the direct connection to the heart was somewhat doubtful in some specimens. No direct inhibitory neurone was found, but the high firing frequency of the visceral ganglion neurone (VG1) usually produced heart inhibition.
Hearing and Echolocation in the Australian Grey Swiftlet, Collocalia Spodiopygia
Authors: Coles Roger B. , Konishi Masakazu , Pettigrew John D. 
Published: April 2021

ABSTRACT
The frequency sensitivity of hearing in the grey swiftlet, Collocalia spodiopygia, was determined by neuronal recordings from the auditory midbrain (MLD). The most sensitive best frequency response thresholds occurred between 0·8 and 4·7 kHz, with the upper frequency limit near 6 kHz. Spectral analysis of echolocation click pairs revealed energy peaks between 3·0 and 8·0 kHz for the foreclick, compared to 4·0–6·0 kHz for the principal click. The relationship between good hearing sensitivity and click energy peaks in the swiftlet extends about an octave higher than it does in the oilbird (Steatornis caripensis).
Excretion in the House Cricket (Acheta Domesticus): Stimulation of Diuresis by Tissue Homogenates
Authors: Spring Jeffrey H. , Hazelton Shelia R. 
Published: April 2021

ABSTRACT
A new method is described for maintaining cricket Malpighian tubules in vitro. Warmed, oxygenated saline is circulated rapidly past the tubules, while the secreted urine is collected under oil for analysis. This technique allows the cricket tubules to be observed and manipulated for extended periods (6 h), in contrast to their short life (&lt;1 h) using conventional methods. Cricket tubules show extreme sensitivity to oxygen deprivation, such that 15 min of anoxia represents the median lethal dose (LD50) for in vitro preparations. Homogenates of corpus cardiacum (CC) cause the rate of fluid secretion by the tubules to double. The maximum stimulation is dose-dependent over the range 0·01 to 1·0 CC. Homogenates of brain and other ganglia show much smaller stimulatory effects (0·01–0·02 CC-equivalents). Cyclic AMP mimics the increase in secretion rate, but has an inhibitory effect on the smooth muscle of the ureter. Control preparations maintain a urine osmotic pressure (OP) that is hyperosmotic to the bath by 5–10 mosmol l−1. CC homogenate produces a decrease in urine OP to 10–12 mosmol l−1 hypo-osmotic to the bath. This suggests that active solute reabsorption is occurring in the lower tubule or ampulla. Stimulation by CC homogenate increases the urine potassium concentration slightly less than two-fold, whereas the sodium concentration increases by a maximum of five-fold and remains at a higher concentration than potassium throughout the experiment. Tubule secretion rate is drastically inhibited in nominally sodium-free saline.
The Transition to Air Breathing in Fishes: IV. Impact of Branchial Specializations for Air Breathing on the Aquatic Respiratory Mechanisms and Ventilatory Costs of the Swamp Eel Synbranchus Marmoratus
Authors: Graham Jeffrey B. , Baird Troy A. , Stöckmann Wieland 
Published: April 2021

ABSTRACT
The gills, adjacent buccopharyngeal epithelium, and skin of the swamp eel Synbranchus marmoratus (Bloch) function for both aerial and aquatic respiration. Aquatic cutaneous O2 uptake occurs continuously at rates that, while dependent upon aquatic O2 tension , are in direct proportion to body surface area. Branchial aquatic O2 uptake takes place during intermittent ventilation which occurs in proportion to body mass. Because of reductions in the body surface area to volume ratio that occur with growth, cutaneous oxygen uptake comprises a larger percentage of the total oxygen uptake of small fish and, to compensate, large fish ventilate more. The mass exponent for total rate of oxygen uptake (0·894 ± 0·145) is within the range predicted from the contributions of cutaneous (mass exponent 0·651 ± 0·167) and the number of minutes each hour that branchial ventilation occurs (0·378 ± 0·105). Hyperoxia increases cutaneous and reduces branchial ventilation. Total was also reduced in hyperoxia and calculations relating this to the reduction in ventilation time yield ventilatory cost estimates that increase with body size and that are high compared to those of other fish when the large component of cutaneous respiration in this species is considered. Large ventilatory costs reflect gill and branchial apparatus specialization for aerial respiration. Accessory cutaneous respiration and intermittent aquatic ventilation reduce these costs, and intermittent gill use in aquatic breathing, which is the exact analogue of the pattern for branchial respiratory use during air breathing, seems to optimize aquatic O2 uptake with minimal ventilatory cost.
The Growth Stimulation of Blow-Fly Larvae Fed on Fatigued Frog Muscle. II
Authors: Smith G. Pugh 
Published: April 2021

ABSTRACT
It had previously been shown that blow-fly larvae fed on fatigued frog muscle grow to a larger size than controls fed on resting muscle.
I have now demonstrated that the growth-stimulating substance is thermolabile and that it passes from the contracting muscle into the blood stream. It does not accumulate in the liver.
The bacterial flora is equally dense on resting and on fatigued muscle on which fly larvae have fed.
Intracardiac Shunting Revealed by Angiocardiography in the Lizard Tupinambis Teguixin
Authors: Johansen K. , Abe A. S. , Andresen J. H. 
Published: April 2021

ABSTRACT
The central circulation in the lizard Tupinambis teguixin (Linné, 1758) was studied using angiocardiographic techniques. Contrast medium was selectively injected into the vena cava superior, the sinus venosus, the right atrium, and the ventricular subcompartments [the cavum pulmonale (CP) and cavum arteriosum (CA)], following catheterization of the heart from the right jugular vein. Contrast medium injection in the vena cava, sinus venosus, right atrium or CP showed that there was an exclusive and selective passage to the pulmonaryy circulation when injections were made during spontaneous or artificial ventilation. Contrast injection during apnoea showed various degrees of right-left shunting to the left aorta but typically not to the right aorta. There was no observable admixture from the CP to the CA. When contrast medium was injected directly into the cavum arteriosum, there was clear selective filling of the right aorta and the cephalad circulation, as well as a lesser but distinct filling of the left aorta. During systole, there was no admixture from the CA to the CP, but a very slight left-right admixture was discernible during ventricular diastole. The selective passage of contrast medium through the heart of Tupinambis showed a relationship to breathing in the intermittent ventilation pattern of Tupinambis. During apnoea, pulmonaryy flow appears to be impeded: this may reflect right—left shunting to the left aorta. This vessel becomes important in the alternation between a balance of pulmonaryy and systemic flow during breathing and a preference for systemic flow during apnoea.
The Efficiency of Sound Production in Two Cricket Species, Gryllotalpa Australis and Teleogryllus Commodus (Orthoptera: Grylloidea)
Authors: Kavanagh Mark W. 
Published: April 2021

ABSTRACT
Males of Gryllotalpa australis (Erichson) (Gryllotalpidae) and Teleogryllus commodus (Walter) (Gryllidae) produced their calling songs while confined in respirometers. G. australis males used oxygen during calling at a mean rate of 4–637ml O2h−1, equivalent to 27·65 mW of metabolic energy, which was 13 times higher than the resting metabolic rate. T. commodus males used oxygen during calling at a rate of 0·728 ml O2 h−1, equivalent to 4·34mW, which was four times the resting metabolic rate. The sound field during calling by males represents a sound power output of 0·27 mW for G. australis and 1·51×10−3mW for T. commodus. The efficiency of sound production was 1·05% for males of G. australis and 0·05 % for males of T. commodus. Comparison with other insect species suggests that none is more than a few percent efficient in sound production.
Functional design of horse hoof keratin: the modulation of mechanical properties through hydration effects
Authors: Bertram J. E. A. , Gosline J. M. 
Published: April 2021

ABSTRACT
Tensile moduli and J-integral fracture toughness values were determined for horse hoof-wall keratin at four hydration levels. The stiffness of hoof-wall was influenced by water content to a greater degree than is the stiffness of other mammalian hard keratins. Young’s modulus increased from 410 MPa at 100 % relative hydration (RH) to 14·6 GPa at 0% RH. Fracture toughness was maximal (22·8 kJ m−2) at an intermediate hydration (75% RH), which represents a two-fold increase over both fully hydrated and dehydrated material. Maximum fracture toughness occurred at a hydration level which is within the range that has been found in vivo in the hoof wall. These results lead to the hypothesis that the density of secondary bonding sites within the hoof-wall keratin matrix proteins provides the hoof organ with the means to modulate tissue properties, even though this epidermal tissue functions after the cells have died.
Locomotion Energetics of the Ghost Crab: I. Metabolic Cost and Endurance
Authors: Full Robert J. 
Published: April 2021

ABSTRACT
Arthropods possess spectacular diversity in locomotor design. Yet it is not clear what unique constraints, if any, variation in design imposes on mechanics, metabolic energy cost or endurance during terrestrial locomotion. In the present study metabolic energy cost and endurance on a treadmill are measured for an arthropod, the eight-legged sideways travelling ghost crab, Ocypode quadrata (Fabricius). In a second paper the mechanics of locomotion are determined during walking and running over a force plate.
Severe limitations in O2 uptake during exercise are not inherent in the design of a crab’s O2 transport system, which consists of gills and an open circulatory system. The ghost crab’s capacity to elevate oxygen consumption rapidly is correlated with a lesser dependence on anaerobic sources than observed in other crab species. Accelerated glycolysis contributed at the onset of submaximal exercise, before O2 uptake adjustments were completed, but played only a minor role during steady-state exercise. O. quadrata elevated 6·4-to 8-fold above resting rates. The ghost crab’s maximal oxygen consumption was not different from that of an ectothermic vertebrate of the same body mass and temperature, such as a lizard, that uses lungs and a closed circulatory system.
The minimum metabolic energy necessary to move 1 g of crab 1 km (Cmin) decreased as a function of body mass and age. Cmin was comparable to that predicted for vertebrates of a similar body mass and, therefore, appears to be relatively independent of locomotor design. This is consistent with the hypothesis that a similarity in the energetic properties of muscle and elastic structures may result in similar metabolic costs of locomotion.
Endurance capacity did not increase with body mass, as predicted from interspecific comparisons of mammals and lizards. Instead, endurance capacity correlated with the speed at which oxygen consumption was maximal. Mean endurance capacity for ghost crabs was similar to that found for lizards, but was far less than the values predicted for mammals. Ghost crabs could only sustain a slow walk. Running at speeds 20 times faster is possible for short periods, but not without the aid of anaerobic metabolism.
Locomotion Energetics of the Ghost Crab: II. Mechanics of the Centre of Mass During Walking and Running
Authors: Blickhan Reinhard , Full Robert J. 
Published: April 2021

ABSTRACT
Terrestrial locomotion involving appendages has evolved independently in vertebrates and arthropods. Differences in the mechanical design of the locomotor apparatus could impose constraints on the energetics of locomotion. The mechanical energy fluctuations of the centre of mass of an arthropod, the ghost crab Ocvpode quadrata (Fabricius), were examined by integrating the ground reaction forces exerted during sideways locomotion. Crabs used a pendulum-type energy exchange mechanism during walking, analogous to an egg rolling end over end, with the same effectiveness as birds and mammals. Moreover, ghost crabs were found to have two running gaits. A switch from a slow to a fast run occurred at the same speed and stride frequency predicted for the trot-gallop transition of a quadrupedal mammal of the same body mass. In addition, the mass-specific mechanical energy developed over a unit distance was independent of speed and was within the limits measured for birds and mammals. Despite the obvious differences in mechanical design between crabs and mammals, energy-conserving mechanisms and the efficiency of locomotion were remarkably similar. These similarities may result from the fact that the muscles that generate forces during terrestrial locomotion have relatively conservative mechanical and energetic properties.
Na+-Cl−-Glutamate Cotransport by Lobster Hepatopancreatic Brush Border Membrane Vesicles
Authors: Ahearn Gregory A. , Clay Laurel P. 
Published: April 2021

ABSTRACT
l-[3H]glutamate uptake by lobster hepatopancreatic brush border membrane vesicles, formed by a magnesium precipitation technique, was stimulated by a transmembrane NaCl gradient (o&gt;i), but not by identical gradients of KCl, TMA-Cl, NaSCN or NaNO3-, suggesting that the amino acid transfer depends specifically upon both Na+ and Cl−. In the presence of a NaCl gradient (o&gt;i), glutamate uptake was strongly dependent upon bilateral pH and increased markedly as pH was lowered from 7·0 to 4·0. NaCl-dependent l-[3H]glutamate uptake was not trans-stimulated by preloading vesicles with K+. At pH 5·0, NaCl-dependent glutamate uptake occurred by an electroneutral process, whereas Na+-dependent d-[3H]glucose uptake at this pH was electrogenic. l-[3H]glutamate influx exhibited both carrier-mediated and apparent diffusional transport components. Decreasing pH had no significant effect on glutamate influx (Kt), but tripled both maximal carrier-mediated entry rate (JM) and the apparent diffusional permeability (P) of the membrane to this compound. l-[3H]glutamate influx was strongly trans-stimulated by vesicles preloaded with l-and d-glutamate, l-and d-aspartate, l-cysteate, l-tyrosine and l-asparagine, but not by vesicles preloaded with l-leucine, l-glutamine, l-proline, l-alanine or l-lysine. l-[3H]glutamate influx at pH 4·0 was a hyperbolic function of both external Na+ and Cl− concentrations at fixed concentrations of the respective counterions, suggesting cotransport between the amino acid and the two ions with a stoichiometry of 1 Na+ : 1 Cl− : 1 glutamate.