bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extracellular accumulation of proline, serine and trehalose in the haemolymph of osmoconforming brackish-water mosquitoes
Authors: Garrett M. A. , Bradley T. J. 
Published: April 2021

ABSTRACT
Larvae of Culex tarsalis, a mosquito, are capable of surviving and developing in dilutions of sea water ranging from 0 mosmol l−1 to 700 mosmol l−1. In waters more dilute than 400 mosmol l−1, the larvae osmoregulate, whereas in those more concentrated than 400 mosmol l−1, the osmotic strength of the haemolymph parallels that of the medium, i.e. the larvae osmoconform. Over the full range of external concentrations tested, the larvae regulate the levels of Na+, K+, Mg2+, Ca2+ and Cl− in the haemolymph. Analyses of haemolymph samples from larvae adapted to media of 50 mosmol l−1 or 600 mosmol l−1 indicate that the increase in haemolymph osmotic concentration observed in media above 400 mosmol l−1 is due to the accumulation of organic compounds, particularly proline, serine and trehalose.
Neural Control of Heart Beat in the African Giant Snail, Achatina Fulica Férussac: II. Interconnections Among the Heart Regulatory Neurones
Authors: Furukawa Yasuo , Kobayashi Makoto 
Published: April 2021

ABSTRACT
The synaptic connections between identified heart regulatory neurones were examined in the central nervous system of the African giant snail, Achatina fulica Férussac. Two cerebral ganglion cells, the dorsal right and left cerebral distinct neurones (d-RCDN and d-LCDN), were found to have excitatory connections with several neurones in the suboesophageal ganglia (the periodically oscillating neurone, PON, the tonically autoactive neurones, TAN, TAN-2 and TAN-3, and the visceral intermittent firing neurone, VIN) and the connections are probably monosynaptic. VIN had a weak electrical coupling with PON. VIN inhibited TAN, TAN-2 and TAN-3, and the connections were considered to be monosynaptic. At the same time, TAN, TAN-2, TAN-3 and the visceral ganglion neurone (VG1) inhibited PON and VIN although the connections are unlikely to be monosynaptic. Another neurone in the pedal ganglia, the dorsal left pedal large neurone (d-LPeLN), was found to excite PON, VIN, TAN, TAN-2 and TAN-3. These connections were not monosynaptic. These results are interpreted in relation to heart regulation in Achatina.
Thermal dependence of maximum Ca2+-activated force in skinned muscle fibres of the toad Bufo marinus acclimated at different temperatures
Authors: Rees B. B. , Stephenson D. G. 
Published: April 2021

ABSTRACT
Mechanically skinned muscle fibres from the twitch region of the iliofibularis muscle of cool-(16 ± 1°C) and warm- (32 ± 1°C) acclimated cane toads (Bufo marinus) were activated maximally by Ca2+ in solutions of different pH and at different temperatures (approx. 1–35°C). Acclimation of up to 12 weeks at 16°C and up to 8 weeks at 32°C did not modify the marked thermal dependence of isometric force in the skeletal muscle fibres of the cane toad. The prominent decline of maximum Ca2+-activated force at lower temperatures, a property which is not characteristic of muscles from other anurans, was associated with an obvious decline in fibre stiffness at temperatures below about 20°C, regardless of the temperatures at which the toads were kept prior to experimentation. The results suggest that the decline of isometric force at lower temperatures is due both to a reduction in the number of cross-bridges and to a decrease in the force output per cross-bridge. The maximum Ca2+-activated force response increased when fibres were activated in solutions of increasing pH at all temperatures investigated. This trend is expected to have a compensatory effect on the thermal dependence of the maximum Ca2+-activated force under physiological conditions, because of the elevation of intracellular pH as temperature declines. 4.The isometric force did not depend on the concentration of the zwitterionic species of the pH buffer in solutions. 5.The skinned fibre preparation developed a Ca2+-insensitive residual force following maximal activation. The increment in residual force followed a linear relationship with the duration of activation at a given temperature and a power relationship of activation temperature for a given duration of activation. Fibres from warm-acclimated animals developed less residual force following activations at 15 °C than did fibres from cool-acclimated animals, suggesting that thermal acclimation may substantially reduce the magnitude of this phenomenon at temperatures below 20°C.
A local interneurone which receives differential input from the medial and lateral giant axons
Authors: Takahata M , Wine JJ 
Published: April 2021

ABSTRACT
The crayfish ventral nerve cord contains two pairs of giant axons which are termed command axons for escape because impulses in either pair of cells trigger a complex series of neural events that culminates in a rapid flexion and extension of the abdomen, i.e. a ‘tailflip’ (Wine & Krasne, 1982). Each pair of axons triggers a specific trajectory of escape by virtue of differences in its intersegmental pattern of synapses with flexor motor neurones (Larimer, Eggleston, Masukawa & Kennedy, 1971 ; Wine & Krasne, 1972; Mittenthal & Wine, 1973; Miller, Hagiwara & Wine, 1985; Dumont & Wine, 1987b). However, while some of the flexor motor pathways are differentiated in a way that is consistent with the observed behaviour, a persistent puzzle has been the extraordinary degree of overlap in the output connections of the two kinds of giant axons to other portions of the flexor motor pathway. These overlapping connections should blur the distinction between the escape trajectories, and thus are inconsistent with the observed behaviour.
Roles of individual honeybee workers and drones in colonial thermogenesis
Authors: Harrison J. M. 
Published: April 2021

ABSTRACT
The individual roles of honeybee workers and drones in heat regulation were investigated using single combs of bees and brood (about 1000 individuals) placed in boxes at 1S°C. After 1h and before cluster formation, I measured the elevation of bee thoracic surface temperature (Tths) above local ambient temperature (Ta). Bees were then left overnight at 15 °C. During the preclustering period, the density of bees over the brood slowly increased. In the clusters left overnight, bees in the innermost layer were significantly younger than bees in the outermost layer. One-day-old bees and drones were always located in the innermost cluster layer. 89% of all workers measured had Tths−Ta 3 ⩾ 2°C, indicating that most workers contribute to colonial thermogenesis. Average Tths−Ta was 4·1 °C. Drones measured had the same average Tths−Ta as unmarked workers. Tths−Ta did not differ among bees 2 days of age and older. Location on or off the brood did not affect Tths−Ta. Cooling constants of dead bees placed near the comb in the box averaged 1·036 min−1 and were independent of location on the comb. Calculated average thoracic conductance was 0·829 calg−10C−1 min−1. Average calculated heat production per worker was 0·095 cal min−1, less than 15 % of the maximal oxygen consumption of 4-day-old bees. Calculations indicate that the larger drones contribute more heat per bee than do the workers. Brood warming prior to clustering is due to relatively uniform heat production by individual bees and the attraction of bees to the brood area. This results in a higher heat production per unit volume of air over the brood than away from the brood.
The Function of the Calciferous Glands of Earthworms
Authors: Robertson James D. 
Published: April 2021

ABSTRACT
In the Lumbricidae the secretion of the calciferous glands consists mainly of calcium carbonate, the percentage of carbonate in the calcite concretions being 95−97 per cent. Feeding experiments indicate that the calcium of the secretion can be derived from the common inorganic salts such as the carbonate, sulphate, phosphate, oxalate, chloride, and nitrate, and also from pear leaves. Measurements of the hydrogen-ion concentration of the gut, soil, and castings of specimens of Lumbricus terrestris show that the tendency of the cast to be more neutral than the soil is due to the secretions of the gut as a whole, and not to the secretion of the calciferous glands. The optimum pH’s of two of the main intestinal enzymes have been −measured. Amylase has an optimum at pH 6-8-yo, and lipase at pH 6’4-6-6 and 7-37-7 depending on the substrate. The amount of carbon dioxide bound as carbonate by the glands was measured in a series of experiments with earthworms kept in different calcium salts. The percentage of carbon dioxide excreted as carbonate never exceeded 10 per cent, of the total metabolic carbon dioxide. Absorption of iron saccharate injected into worms took place occasionally, in groups of adjacent cells in the intestine and in isolated cells in the calciferous glands. The true function of the calciferous glands is excretion, calcium carbonate being passed into the gut as crystals of calcite which are chemically inactive in the gut.
The Mechanism of Urine Formation in Invertebrates
Authors: Picken L. E. R. 
Published: April 2021

ABSTRACTIn Carcinus maenas : (a) The blood may be hypertonic, isotonic or hypotonic to the external medium. (b) The urine may be hypertonic, isotonic or hypotonic to the blood, and its concentration may differ in the two antennary glands. (c) The hydrostatic pressure of the body fluid is c. 13 cm. of water. (d) The colloid osmotic pressure of the blood is c. 11 cm. of water. (e) The urine probably contains protein and has a colloid osmotic pressure of c. 3 cm. of water. In Potamobius fluviatilis : (a) The blood is hypertonic to the external medium. (b) The urine is hypotonic to the blood but hypertonic to the external medium and its concentration may differ in the two antennary glands. (c) The hydrostatic pressure of the body fluid is c. 20 cm. of water. (d) The colloid osmotic pressure of the blood is c. 15 cm. of water. (e) The urine may contain protein and has a colloid osmotic pressure (calculated) of c. 2 cm. of water. In Peripatopsis spp. : (a) The blood is hypertonic to the urine. (b) The hydrostatic pressure of the body fluid is c. 10 cm. of water. (c) The colloid osmotic pressure (calculated) of the blood is c. 5 cm. of water. (d) The urine may contain protein and has a colloid osmotic pressure (calculated) of c. 2-5 cm. of water. (e) It is concluded that filtration is possible and that secretion and resorption almost certainly occur in the formation of the urine. (f) A microthermopile is described. (g) Methods are described for measuring the hydrostatic pressure and the colloid osmotic pressures of the body fluids in small animals.
Blood Gases, and Extracellular/Intracellular Acid-Base Status as a Function of Temperature in the Anuran Amphibians Xenopus Laevis and Bufo Marinus
Authors: Boutilier R. G. , Glass M. L. , Heisler N. 
Published: April 2021

ABSTRACT
Blood gases, and parameters of the extracellular and intracellular acid-base status, were measured in the anuran amphibians Bufo marinus and Xenopus laevis acclimated to temperatures of 10, 20 and 30°C for 12 days. Arterial rose with temperature so that approximately constant oxygen saturation of the blood was maintained, a phenomenon explained on the basis of models for O2 transport in animals with central vascular shunts and temperature-dependent shifts in O2 equilibrium characteristics. Arterial plasma pH of both species varied inversely with temperature, the pH/temperature coefficient being not significantly different from that required for constant relative alkalinity or dissociation of imidazole. The change in plasma pH was brought about mainly by changes in , although plasma bicarbonate concentration also changed significantly. Intracellular pH/temperature relationships were found to be non-linear in most of the tissues. There was considerable variability among body tissue compartments and between the two species. These data confirm that the various tissue compartments in ectotherms maintain unique ΔpH/ Δt relationships, and indicate that measurement of extracellular pH as a function of temperature is not a good indicator for alphastat-type, temperature-dependent, acid-base regulation.
Oxygen and Carbon Dioxide Transport Characteristics of the Blood of the Nile Monitor Lizard (Varanus Niloticus)
Authors: Hicks James W. , Ishimatsu Atsushi , Heisler Norbert 
Published: April 2021

ABSTRACT
Oxygen and carbon dioxide dissociation curves were constructed for the blood of the Nile monitor lizard, Varanus niloticus, acclimated for 12h at 25 and 35°C. The oxygen affinity of Varanus blood was low when was in the range of in vivo values (25°C: P50 = 34·3 at 35°C: P50 = 46·2mmHg at 1 mmHg = 133·3 Pa), and the oxygen dissociation curves were highly sigmoidal (Hill’s n = 2·97 at 25°C and 3·40 at 35°C). The position of the O2 curves was relatively insensitive to temperature change with an apparent enthalpy of oxygenation (ΔH) of −9·2kJmol−1. The carbon dioxide dissociation curves were shifted to the right with increasing temperature by decreasing total at fixed , whereas the state of oxygenation had little effect on total blood CO2 content. The in vitro buffer value of true plasma (Δ [HCO3−]pl/−ΔpHp1) rose from 12·0mequivpH−11−1 at 25°C to 17·5 mequivpH−11−1 at 35°C, reflecting a reversible increase of about 30 % in haemoglobin concentration and haematocrit levels during resting conditions in vivo.
Body Accelerations During the Wingbeat in Six Bat Species: The Function of the Upstroke in Thrust Generation
Authors: Aldridge H. D. J. N. 
Published: April 2021

ABSTRACT
The kinematics and aerodynamics of Rhinolophus ferrumequinum, R. hipposideros, Myotis nattereri, M. mystacinus, Plecotus auritus and Eptesicus serotinus in horizontal flight at various flight speeds are described. Three kinematic patterns can be recognized. At low speeds M. nattereri, M. mystacinus and P. auritus use a ‘tip-reversal’ upstroke in which thrust is generated during the backward ‘flick’ of the chiropatagium. R. hipposideros also uses this kinematic pattern, but does not appear to generate thrust during the upstroke. Both R. ferrumequinum flying at 3·12ms−1 and E. serotinus flying at 3·44ms−1 accelerate during the ‘vertical’ upstroke (in which the wings move perpendicularly to the flight path), indicating that their wings are active. When flying at 4·16 m s−1, E. serotinus also uses a’vertical’upstroke, but in this case it decelerates, which suggests that thrust is not being generated. At minimum power speed (4·8ms−1), R.ferrumequinum uses a ‘reduced-span’ upstroke, thrust is not generated during the upstroke and the animal decelerates.
A new microcomputer-based method for measuring walking phonotaxis in field crickets (Gryllidae)
Authors: Doherty JA , Pires A 
Published: April 2021

ABSTRACT
Calling songs of male crickets attract sexually mature, conspecific females for mating (for recent reviews see Elsner & Popov, 1978; Huber & Thorson, 1985; Doherty & Hoy, 1985). This communication system has been the subject of many behavioural studies on the relevant properties of the male’s calling song for recognition by females (e.g. Walker, 1957; Popov & Shuvalov, 1977; Pollack & Hoy, 1979, 1981; Thorson, Weber & Huber, 1982; Stout, DeHaan & McGhee, 1983; Doherty, 1985b; Doolan & Pollack, 1985). The behavioural investigations have required some means of measuring the female’s phonotaxis (her locomotion or turning towards a sound source). These include ‘closed-loop’ methods in which the animal moves freely in acoustic space and ‘open-loop’ methods in which the animal is tethered and is not allowed to experience changes in sound intensities as it runs in the direction of the sound source. Closed-loop methods include free walking in arenas (e.g. Murphey & Zaretsky, 1972; Paul, 1976; Hoy, Hahn & Paul, 1977; Pollack & Hoy, 1979; Stout et al. 1983); open-loop methods include tethered flight (Moiseff, Pollack & Hoy, 1978; Pollack & Hoy, 1979, 1981; Pollack, Huber & Weber, 1984), tethered walking on Y-maze globes (Hoy & Paul, 1973) and free walking on a spherical locomotion compensator (Wendler, Dambach, Schmitz & Scharstein, 1980; Thorson & Huber, 1981; Thorson et al. 1982; Pollack et al. 1984; Doherty, 1985a,b,c; Schmitz, 1985).
Ca2+-Dependent Photoreceptor Potential in Paramecium Bursaria
Authors: Nakaoka Yasuo , Kinugawa Kohsaku , Kurotani Tohru 
Published: April 2021

ABSTRACT
Photostimulation of deciliated specimens of chlorella-free P. bursaria elicited a transient depolarization of the membrane potential. The amplitude of this receptor potential became larger as light intensity was increased and the relationship showed a Michaelis equation. The action spectrum of the receptor potential showed two peaks at around 420 and 560 nm. When constant current was injected to depolarize the membrane gradually, the receptor potential showed a decrease in amplitude. The potential at which the response disappeared depended on the external concentration of Ca2+ (27 mV/log [Ca2+]o), and the amplitude of the receptor potential was also dependent upon external Ca2+ concentration. Therefore, the receptor potential is primarily caused by a transient increase in the membrane conductance to Ca2+.
Gamma-Aminobutyric Acid Receptors on Cultured Cockroach Brain Neurones
Authors: Shimahara T. , Pichon Y. , Lees G. , Beadle C. A. , Beadle D. J. 
Published: April 2021

ABSTRACT
Gamma-aminobutyric acid (GABA) at 10−4 mol l−1 inhibited spontaneous activity and produced conductance changes in 60% of cultured cockroach neurones tested. The reversal potential for the GABA-evoked response was between −65 mV and−75 mV. Under whole-cell voltage-clamp conditions, with 114 mmol l−1 potassium chloride in the electrode, the reversal potential had a similar value to that predicted for a chloride current. The response was blocked by 10−5 mol l−1 picrotoxin but was not affected by 10−5moll−1 bicuculline. In the whole-cell voltage-clamp conditions, 50 μmol l−1 GABA evoked an inward current that was accompanied by an increase in current noise. Fluctuation analysis of the noise gave a mean channel opening time of 11·8 ms for GABA and 6 5 ms for muscimol. The single-channel conductance was 18·6 pS for GABA and 15·2 pS for muscimol. When 50 μmoll−1 GABA was applied in the presence of the benzodiazepine, flunitrazepam, there was an increase in both the evoked current and the accompanying current noise. Analysis of this noise gave values of 14·3 ms for the mean channel opening time and 18·3 pS for the singlechannel conductance. The variance of the noise was increased by approximately 60% in the presence of flunitrazepam, suggesting that this drug potentiates the GABA responses of cockroach neurones by increasing the frequency of channel events.
Statocyst Control of Uropod Righting Reactions in Different Planes of Body Tilt in the Norway Lobster, Nephrops Norvegicus
Authors: Newland Philip L. , Neil Douglas M. 
Published: April 2021

ABSTRACT
The righting reactions of the uropod exopodites of the Norway lobster, Nephrops norvegiens, induced by stimulation of the statocysts, were studied during both imposed body tilts in different vertical planes and freely expressed manoeuvres. The opening and closing movements of the uropod exopodite were brought about by the reciprocal activity of the dorsal abductor muscles and the reductor muscles, respectively. The uropods were held symmetrically open when the animal was upright, but adopted an asymmetrical pattern, with the downward uropod open and the upward uropod closed, during imposed body roll. In an imposed pitch of the body, the uropods closed symmetrically on headdown movement and opened symmetrically on head-up movement. The response pattern which occured in roll persisted through intermediate vertical planes to within 10° of true pitch. Removal of the statolith from a single statocyst caused the zone of symmetrical uropod responses to shift towards the operated side, but did not alter its angular dimensions. Bilateral statolith removal abolished the uropod reaction to tilt. Animals released in mid-water exactly in the pitch plane recovered their upright posture by a pitching movement, using symmetrical motor reactions of the abdomen and its appendages. Animals released at all other possible orientations used an initial rolling movement, involving an asymmetrical disposition of the appendages. The chelipeds did not contribute significantly to righting in roll, but both the lateral beating of the swimmerets and the asymmetrical disposition of the uropods produced righting torques as the animal descended through the water. These results are discussed in terms of the hydromechanical effect of asymmetrical uropod postures, and the functional significance of the distinct switching between symmetrical and asymmetrical patterns. Implications for the mechanisms of statocyst control of uropod righting reactions, in terms of both the magnitude and the direction of body tilt, are also considered.
Structure and innervation of the third axillary muscle of Manduca relative to its role in turning flight
Authors: Rheuben M. B. , Kammer A. E. 
Published: April 2021

ABSTRACT
The morphology, ultrastructure, innervation and physiology of the third axillary muscle in Manduca sexta were examined to investigate the role of this muscle in flight. The muscle consists of three parts: the upper bundle, which originates on the episternum, and the middle and lower bundles, which originate on the epimeron; all three parts insert on the tip of a projection from the third axillary sclerite. The middle bundle is composed of tonic fibres, and is innervated by a single slow axon, while the other two bundles consist of intermediate fibres and are each innervated by a single fast axon. The shape and position of the third axillary sclerite within the wing hinge are such that its primary function appears to be remotion of the wing. The length of the third axillary muscle determines the amount of remotion, independently of the degree of elevation or depression of the wing and independently of the amount of remotion of the contralateral wing. Electrophysiological recordings from the three parts of the muscle during tethered flight indicate that they may each function independently of each other and in different ways. The tonic (middle) bundle is capable of maintaining tension to hold the wings in the folded position at rest and is active when the wings are folded at the end of flight. The intermediate (upper and lower) bundles are activated phasically with impulses that may occur with various relationships to the timing of activation of a direct depressor, the subalar, or of several of the elevators. The findings are consistent with the hypothesis that the third axillary muscles on both sides are important in determining the asymmetric degrees of remotion observed in turning flight.