bluuebunny/crossref_metadata_2025_split huggingface dataset:
Age-Dependent Changes in Volume and Haemoglobin Content of Erythrocytes in the Carp (Cyprinus Carpio L.)
Authors: Speckner W. , Schindler J. F. , Albers C. 
Published: April 2021

ABSTRACT
Carp erythrocytes were fractionated by angle-head centrifugation which yielded fractions with a linear increase in density. Haematological examinations revealed that the heavier red blood cells of carp had greater volumes (MCV), more haemoglobin (MCH) and higher haemoglobin concentrations (MCHC) than light ones. The same experiments with human red cell fractions yielded a decrease in MCV, constant MCH and an increase in MCHC. Haemoglobin content in individual erythrocytes was also determined by scanning stage absorbance cytophotometry to establish the frequency distribution of the cellular haemoglobin contents. In carp, the distribution was symmetrical with the means increasing with density. No such change with cell density was found in human erythrocytes.
Both carp and human erythrocytes incorporated [2-14C]glycine in vitro. After gel filtration, radioactivity was detected in carp, but not in human, haemoglobin fractions. 14C was found in all three haemoglobin fractions, obtained by isoelectric focusing, and was present in the haem and in the globin. [2-14C]glycine-labelled erythrocytes were reinjected into chronically cannulated carp and followed in vivo for several months. With time, the main peak of scintillation counts shifted from red cell fractions of low to high density.
This is considered as evidence that density and age of red cells in carp are positively correlated and that erythrocytes can synthesize haemoglobin while circulating in the peripheral blood.
Ionic and Total Calcium Levels in the Blood of the European Eel (Anguilla Anguilla): Effects of Stanniectomy and Hypocalcin Replacement Therapy
Authors: Hanssen Robert G. J. , Lafeber Floris P. , Flik Gert , Bonga Sjoerd E. Wendelaar 
Published: April 2021

ABSTRACT
Removal of the corpuscles of Stannius (STX) in the freshwater European eel causes a marked increase in the concentrations of blood ionic calcium and proteinbound calcium. The hypercalcaemia peaks 20 days after STX and lasts at least another 20 days. In stanniectomized eels hypocalcin decreased both blood ionic and total calcium concentrations. The reduction of plasma total calcium concentration by hypocalcin is attributed to a reduction in blood ionic calcium concentration. We conclude that hypocalcin regulates blood ionic calcium levels in fish.
Physical Properties, Sensory Receptors and Tactile Reflexes of the Antenna of the Australian Freshwater Crayfish Cherax Destructor
Authors: Sandeman David C. 
Published: April 2021

ABSTRACT
The antennal flagellum of the crayfish Cherax destructor is very flexible, tapered and is almost as long as the body in mature animals. It consists of a series of short segments, oval in cross-section, that take the form of flattened rings at the base and slender tubes at the tip. There are no muscles in the flagellum. The flagellum’s mechanical resistance to being bent is not the same in all directions. It is most easily bent dorsally and least easily bent medially, when held stretched out horizontally in front of the animal. The resistance to bending is 10 times less than that of Astacus. The individual segments of the flagellum form curved articulating surfaces that may assist in reducing torsional movement of the flagellum when it is bent and, together with the tapered form, provide the flagellum with unique mechanical properties. Four main types of hairs are found on the flagellum. They are distributed in a specific manner, and total about 7000 hairs on the flagellum of a mature animal. Cross-sections through the sensory nerve reveal only about 2000 axons. Methylene blue applied to fresh preparations stains dendrites to all smooth hairs but never to procumbent feathered hairs. Physiological recordings from the sensory axons of the flagellar nerve allowed the characterization of the sensory hair response to displacement. Recordings were also made from slowly adapting receptors, sensitive to bending the flagellum in particular directions, but not related to mechanoreceptive hairs. Intracellular recordings from identified extensor and flexor motoneurones revealed the ordered projection of the inputs from the receptor hairs, and also provided a model that correlates specific receptor inputs with particular antennal reflexes, and links the unique mechanical properties of the flagellum with the detection of the distance of near objects.
Invariance of Oscillator Interneurone Activity During Variable Motor Output by Locusts
Authors: Reichert H. , Rowell C. H. F. 
Published: April 2021

ABSTRACT
Simultaneous intracellular recordings were made in locusts from (a) flight motor neurones and (b) output interneurones of the flight oscillator. The insects were mounted with the head at the centre of rotation of an artificial horizon. During fictive flight, these animals responded to simulated deviations from course with the changes in motor output appropriate to course-correction manoeuvres, as previously described. In the motor neurone of depressor muscle MN98 (meso-thoracic second basalar) these changes take the form of systematic variation in amplitude in the cyclical depolarization seen in the neurone in flight which, in turn, leads to variation in the number of action potentials per cycle (from 0·3) and in the latency of the first spike (up to 19 ms difference). These changes are closely related to the perceived movement of the horizon. The oscillator output, as recorded in metathoracic interneurone 511, shows, in contrast, very little change. The fraction of its variation which is correlated with horizon movement is vanishingly small (e.g. for number of action potentials per burst r2 = 0·008). The exteroceptive sensory inputs which modify motor output during steering do not, therefore, affect the oscillator appreciably. Thus, by exclusion, the motor patterns of compensatory steering are due exclusively to summation of the oscillator drive with the sensory inputs. This takes place in the motor neurones and especially in the premotor interneurones, as previously described.
Skylight Polarization Patterns and the Orientation of Migratory Birds
Authors: Able Kenneth P. 
Published: April 2021

ABSTRACT
Patterns of polarized light present in the clear dusk sky provide directional information relevant to the orientation behaviour of migratory birds. Experiments performed with white-throated sparrows (Zonotrichia albicollis) and American tree sparrows (Spizella arborea), North American night migrants, examined migratory orientation between the time of sunset and the first appearance of stars under several manipulations of skylight polarization patterns. Under clear skies, birds tested in Emlen funnel orientation cages oriented their hopping basically parallel to the E-vector of polarized light, with a bias towards the brightest part of the sky (sunset direction). Under solid, thick overcast conditions (no polarized light from the natural sky), birds showed axially bimodal hopping orientation parallel to an imposed E-vector. When birds were tested in cages covered with depolarizing material under a clear sky, their hopping orientation was seasonally appropriate and indistinguishable from controls viewing an unaltered clear sky. Skylight polarization patterns are not necessary for the occurrence of migratory orientation, but birds respond strongly to manipulations of the E-vector direction. The results reported here support the hypothesis that the relevant stimulus is the E-vector orientation rather than other parameters of skylight, e.g. intensity or colour patterns, degree of polarization. It appears that these night migrants are using skylight polarization at dusk as one of a set of multiple compass capabilities. Because of the necessarily artificial nature of the polarized light stimuli used in the experimental manipulations, it has not been possible to establish the relationship between this orientation cue and other known mechanisms (magnetic, sun and star compasses).
Water Balance in Manduca Sexta Caterpillars: Water Recycling from the Rectum
Authors: Reynolds Stuart E. , Bellward Karen 
Published: April 2021

ABSTRACT
Tobacco hornworm (Manduca sexta) caterpillars are able to regulate the water content of their body when fed on diets of markedly different water content. This regulation extends to the water content of food within the gut. Regulation of body water is achieved by adjusting the amounts of water lost with the faeces. The rectum is shown to be the principal site of water reabsorption from the faeces. The rate of rectal water absorption is shown to vary with the water content of the food and thus according to need. Water reabsorbed from the rectal contents is recycled and added to the contents of the midgut. The ultrastructural appearance of epithelial cells in the rectal wall is that expected of a fluid-transporting tissue. The ileum appears to play little or no part in water recycling.
Circulating Catecholamines and Swimming Performance in the Atlantic Cod, Gadus Morhua
Authors: Butler P. J. , Axelsson M. , Ehrenström F. , Metcalfe J. D. , Nilsson S. 
Published: April 2021

ABSTRACT
Sectioning the first four pairs of spinal nerves prevents the large increase in circulating catecholamine concentrations seen in Atlantic cod swimming at their critical velocity (Ucrit). There is also a significant reduction in the swimming performance of the fish. To test whether this reduced performance results from the lack of increase in plasma catecholamine levels or from the fact that other organs are also denervated by the operative procedure, a mixture of adrenaline and noradrenaline was infused into swimming, denervated fish. This caused a significant increase in their Ucrit-It is concluded, therefore, that the rise in plasma catecholamine levels seen in Atlantic cod swimming at their maximum sustainable velocity enhances the swimming performance of these fish.
Relationship Between Respiratory Pumping and Oxygen Consumption in Aplysia Depilans and Aplysia Fasciata
Authors: Levy Miriam , Achituv Yair , Susswein Abraham J. 
Published: April 2021

ABSTRACT
Respiratory pumping in Aplysia is a well-characterized behaviour controlled by identified neurones, but its function is unknown. To gain insight into the function of this behaviour, respiratory pumping and oxygen consumption were examined under identical conditions, in Aplysia fasciata Poiret and in A. depilans Gmelin. A. fasciata is found in less turbulent environments than is A. depilans, suggesting that control of respiratory pumping may differ in the two species.
Rates of respiratory pumping and oxygen consumption were poorly correlated. The basal rate of respiratory pumping was similar in both species and was not significantly dependent on animal mass, but the resting rate of oxygen consumption was higher in A. depilans than in A. fasciata and was an inverse function of animal mass in both species. Brief, moderate hypercapnia led to an increase in oxygen consumption in both Aplysia species. In A. fasciata, the increase was much greater. Increase in oxygen consumed was not accompanied by changes in the rate of respiratory pumping. Longer, more severe periods of hypercapnia led to decreases in oxygen consumption in both Aplysia species, and an increase in the rate of respiratory pumping. Decreased oxygen consumption was more gradual in A. fasciata. Severe hypoxia produced a decrease in the rate of oxygen consumed, and an increase in the rate of respiratory pumping.
Acid-Base Regulation Following Exhaustive Exercise: a Comparison Between Freshwater-and Seawater-Adapted RainbowTrout (Salmo Gairdneri)
Authors: Tang Y. , Mcdonald D. G. , Boutilier R. G. 
Published: April 2021

ABSTRACT
Blood acid-base regulation following exhaustive exercise was investigated in freshwater-(FW) and seawater-(SW) adapted rainbow trout (Salmo gairdneri) of the same genetic stock. Following exhaustive exercise at 10°C, both FW and SW trout displayed a mixed respiratory and metabolic blood acidosis. However, in FW trout the acidosis was about double that of SW trout and arterial blood pH took twice as long to correct. These SW/FW differences were related to the relative amounts of net H+ equivalent excretion to the environmental water, SW trout excreting five times as much as FW trout. The greater H+ equivalent excretion in SW trout may be secondary to changes in the gills that accompany the adaptation from FW to SW. It may also be related to the higher concentrations of HCO3− as well as other exchangeable counter-ions (Na+ and Cl−) in the external medium in SW compared to FW.
Adrenaline and Branchial Nerve Stimulation Inhibit 45Ca Influx into the Gills of Rainbow Trout, Salmo Gairdneri
Authors: Donald John A. 
Published: April 2021

ABSTRACT
The tissues in the core of the gill filaments of Salmo gairdneri are innervated by cholinergic and adrenergic nerves (Donald, 1984, 1986, 1987). It is unlikely that the nerves are involved in vasomotor regulation, because the wall of the filament venous sinus of S. gairdneri is a simple endothelium, lacking any muscular elements (Donald, 1986). Since many of the nerves are closely associated with the filament epithelium (Donald, 1986), they might be involved in the regulation of some aspect of epithelial function.
Dye Transport Across the Retinal Basement Membrane of the Blowfly Calliphora Erythrocephala
Authors: Weyrauther E. , Roebroek J. G. H. , Stavenga D. G. 
Published: April 2021

ABSTRACT
In the blowfly, Calliphora erythrocephala, transport of dye into or out of the retina, following injection into the eye or thorax, was investigated, mainly by microspectrophotometry and fluorimetry. After injection into the eye, Phenol Red, Trypan Blue, Lucifer Yellow and 9-amino-acridine were transported out of the retina; Procion Yellow and Rhodamine-123 stayed in it. The time constants of this transport process were in the range 45–80 min at 23°C, depending on the dye. When Lucifer Yellow was injected into the thorax, it was transported into the retina. The transport of these dyes across the retina was inhibited by nitrogen, ouabain and low temperature, indicating that active processes are involved.
The Effects of Hypersaline Exposure on Oxygen-Affinity of the Blood of the Freshwater Teleost Catostomus Commersoni
Authors: Walker R. L. , Wilkes P. R. H. , Wood C. M. 
Published: April 2021

ABSTRACT
After 10 days’ exposure to an environmental salinity of 300mosmol kg−1 NaCl, the freshwater stenohaline teleost Catostomus commersoni exhibited an increase in plasma osmolality and a reduction in plasma strong ion difference (SID). There were reductions in plasma pH (pHe), red blood cell (RBC) pH (pHi), plasma total CO2 and erythrocyte nucleoside triphosphate (NTP) concentration, and increases in mean erythrocyte volume and plasma catecholamine levels. Despite the acidosis, the in vitro haemoglobin oxygen-affinity of blood from saline-acclimated fish was not significantly different from that of control fish (held in fresh water) which had higher pHe and pHi values at the tensions used. In vitro adjustment of SID of blood from control fish to approximate that of the saline-acclimated fish by the addition of NaOH and HC1 significantly reduced pHe, pHi and the haemoglobin oxygen-affinity. Adjustment of the plasma osmolality of blood from control fish to values identical to those of the saline-acclimated fish by the addition of NaCl in vitro did not alter the haemoglobin oxygen-affinity. An increase in catecholamine concentration and a decrease in red blood cell N IP concentration in the saline-acclimated fish may have been compensatory mechanisms to maintain haemoglobin oxygen-affinity against acidosis-induced Bohr and Root effects during saline exposure.
A New Analysis of Ammonia and Sodium Transport Through the Gills of the Freshwater Rainbow Trout (Salmo Gairdneri)
Authors: Avella Martine , Bornancin Michel 
Published: April 2021

ABSTRACT
The mechanism of ammonia excretion and sodium absorption was re-examined in trout using the isolated-perfused head preparation. Preliminary experiments in which ammonia concentration was increased on the blood side (internal) showed that ammonia and sodium transport was uncoupled.
For ammonia excretion, our results showed that gill tissue endogenously produces ammonia. A correlation was demonstrated between ammonia excretion and the internal-external ammonia gradient. We conclude that diffusion in the form of NH3 was responsible for ammonia efflux and we were therefore able to estimate its diffusion coefficient and permeability coefficient (6 × 10−3cms−1). This ammonia diffusion was shown to be modified according to the external proton availability.
For sodium absorption, significant changes were caused by indirect modifications of intracellular pH brought about by addition of acetazolamide inside or ammonia outside or by acidification of the internal or external medium. The relationship between sodium and proton transport was further confirmed by the action of the drug amiloride and the measurement of H+ excretion.
A possible model representing sodium, proton and ammonia transport through the gill epithelium is proposed.
The Role Of Water In Tarsal Taste Thresholds To Sugar In The Blowfly Phormia Regina
Authors: Edgecomb Robert S. , Pyle Angela R. , Murdock Larry L. 
Published: April 2021

ABSTRACT
Thirsty blowflies whose tarsi come into contact with water will respond with proboscis extension. When flies were exposed to high or low relative humidities (RH) prior to testing, the tarsal taste thresholds to sucrose in flies that were unresponsive to water alone increased or decreased, respectively. Evidently, thirst can also be subthreshold and recognizable only as a change in threshold to aqueous sucrose.
Thresholds to sucrose and fructose, which were in the millimolar range in 3-day-old adult flies held at 5–70% RH prior to testing, fell significantly after the flies had been held at low humidity (13–20% RH) for several hours. There was no low-humidity-dependent drop in threshold with galactose or xylose, sugars to which flies normally have thresholds in the 102mmoll−1 range.
Flies held at low relative humidity exhibited increased tarsal thresholds to sucrose when they were injected with water or were allowed to drink water ad libitum. When multiple injections of water were given, thresholds rose after successive injections. Changes in threshold to sucrose occurred after injection with aqueous NaCl, the direction and magnitude being dependent on the concentration injected. The threshold declined significantly after injection of 2μl of 75 mmol l−1 NaCl, remained unchanged after injection of 150 or 300 mmol l−1 NaCl, and increased after injection of 600 mmol l−1 NaCl.
Thirst in blowflies can affect thresholds to food stimuli. The changes in water content of the body resulting from a water-rich meal could contribute significantly to the normal post-meal rises in tarsal thresholds.
Intracellular Na+ and the Control of Amino Acid Fluxes in the Integumental Epithelium of a Marine Bivalve
Authors: Wright Stephen H. , Moon Debra A. , Silva Arnold L. 
Published: April 2021

ABSTRACT
The accumulation of amino acids from sea water into the integumental epithelium of the bivalve gill can occur against chemical gradients in excess of 106 to 1. The energy to drive this transport has been proposed to come from the inwardly directed Na+ electrochemical gradient. The present study examined the influence of intracellular and extracellular [Na+] on influx and efflux of amino acids in gill tissue from the mussel, Mytilus californianus. Influx of alanine was inhibited by more than 90% when external [Na+] was reduced from 425 to 2 mmol l−1, and by 85% when intracellular [Na+] was increased from approximately 11 to approximately 100 mmol l−1 (by means of a 30-min exposure to the ionophore, nigericin). Efflux of taurine and alanine from gill tissue into normal-Na+ sea water was very low (&lt;5% of the Jmax of the carrier-mediated influx pathways). Reducing the external Na+ from 425 to 2 mmol l−1 increased taurine efflux by only 20%. Raising cell [Na+] to approximately 100 mmol l−1 increased taurine efflux 2·7-fold; further increases in cell [Na+] increased taurine efflux another 7·5-fold. These data, in conjunction with results from earlier studies, suggest that activation of integumental amino acid transporters requires an interaction of multiple sodium ions with binding sites of low affinity for this ion. This set of characteristics results in transport systems that are well-adapted for the net accumulation of amino acids from sea water.
Insect Cardioactive Peptides: Neurohormonal Regulation Of Cardiac Activity By Two Cardioacceleratory Peptides During Flight In The Tobacco Hawkmoth, Manduca Sexta
Authors: Tublitz Nathan 
Published: April 2021

ABSTRACT
The relationship between two cardioactive neuropeptides, the cardioacceleratory peptides (CAPs), and changes in heart rate during flight was investigated in the tobacco hawkmoth, Manduca sexta. In vivo heart recordings from intact, tethered adults revealed a marked increase in heart rate associated with flying. Both anterior-to-posterior and posterior-to-anterior contraction waves showed a measurable elevation in contraction frequency. These changes in heart activity were noted in animals engaged in short (20 min) or long (60 min) bouts of continuous flight. Bioassay of blood taken from flying animals revealed the presence of an activity-dependent, blood-borne cardioacceleratory factor(s). Biochemical analyses of the blood of flying insects on HPLC identified two cardioacceleratory factors which co-eluted with the two CAPs. A depletion in the ventral nerve cord levels of both CAPs was observed during flight. In vivo injections of an anti-CAP monoclonal antibody blocked the increase in cardiac activity associated with flight. These results confirm the hypothesis that both CAPs act as cardioregulatory neurohormones during flight in Manduca sexta.