bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of external sodium concentration upon sodium fluxes in Chironomus dorsalis (Meig.) and Camptochironomus tentans (Fabr.), and the effect of other ions on sodium influx in C. tentans
Authors: Wright D.A. 
Published: April 2021

ABSTRACT
In comparison with other freshwater animals, the sodium uptake mechanism in fourth instar larvae of both C. tentans and C. dorsalis has a moderate affinity for sodium. In both species half maximum influx (Km) occurs at about 0·57 mm-Na+ and is unaltered by salt depletion. Maximum influx is achieved in steady-state C. tentans at 1·9 mm-Na+, and in steadystate C. dorsalis at 3·0 mm-Na+. Both of these values increase on depletion. Efflux also appears to be saturable at higher external sodium concentrations.
In C. tentans, sodium may be transported independently of chloride, although it seems likely that sodium movement is enhanced by chloride. Sulphate strongly inhibits sodium influx. Nitrate apparently inhibits sodium influx at low concentrations, but this inhibition is progressively overcome at external sodium concentrations approaching 4 mm.
A number of cations interfere with sodium influx in depleted C. tentans, notably H+, Li+ and, to a lesser extent NH4+. It is suggested that these ions compete with sodium for carrier sites. Potassium is apparently transported independently of sodium.
Sodium and lithium movements and axonal function in cockroach nerve cords
Authors: Bennett R.R. , Buchan P.B. , Treherne J.E. 
Published: April 2021

ABSTRACT
Exposure to sodium-deficient (tris) saline caused an appreciable decline in the sodium content of intact connectives in the absence of equivalent reduction in the amplitude of the recorded action potentials. Return of sodium-depleted connectives to normal saline resulted in a rapid recovery of axonal function despite only a partial ( &lt; 70%) recovery in sodium content. Replacement of sodium ions by those of lithium in the bathing medium resulted in a substantial accumulation of this cation. Lithium movements exhibited a marked asymetry, no significant decline in concentration being observed upon return to normal saline. These results are tentatively interpreted in terms of an exchangeable glial sodium fraction and are discussed in relation to extra-axonal sodium regulation.
Transport of Exogenous D-glucose by the Integument of a Polychaete Worm (Nereis Diversicolor Müller)
Authors: Ahearn Gregory A. , Gomme Jørgen 
Published: April 2021

ABSTRACT
Integumentary exchange of radio-labelled D-glucose in the brackish-water polychaete worm Nereis diversicolor (Annelida; Polychaeta) was investigated. In animals acclimated to 50% sea water, the influx of D-glucose was measured, and shown to occur largely across the outward-facing membranes of the epidermal cells. Transfer of exogenous D-glucose across the outer membranes occurs by facilitated transfer, involving two different transport systems. One of these has a Kt (transport constant) of ≃ 5 μM, i.e. of the order of magnitude of environmental D-glucose concentrations. The Kt for the other system is at least ten times higher. The D-glucose is rapidly metabolized by the epidermal cells. Small amounts of unmetabolized D-glucose are released to the extracellular fluid, and probably to the medium. The maximal D-glucose outflux through the apical border of the epidermal cells is at least 4 times smaller than the outflux through the baso-lateral border. A maximum value is given for the diffusion permeability of D-glucose through the intercellular spaces of the integument. Applying this figure, the loss by intercellular diffusion was found not to exceed the D-glucose influx into the epidermal cells.
Transport of amino acids by isolated gills of the mussel Mytilus californianus Conrad
Authors: Wright S. H. , Johnson T. L. , Crowe J. H. 
Published: April 2021

ABSTRACT
The unidirectional influx of cycloleucine into in vitro preparations of gill tissue of the mussel, Mytilus califomianus, was determined. Influx was found to be linear for at least an hour, and the kinetics of cycloleucine influx conformed to Michaelis-Menten type kinetics. The transport mechanism(s) for cycloleucine is relatively specific for the L-enantiomorph of neutral amino acids, and is capable of accumulating cycloleucine to intracellular concentrations much higher than those of the surrounding medium. Evidence is presented that the transport of amino acids by gill tissue plays a significant role in whole animal nutrition.
Factors affecting the heart activity and blood pressure of the swan mussel Anodonta cygnea
Authors: Sommerville B. A. 
Published: April 2021

ABSTRACT
The rate of heart beat increased with temperature and was three times as high in the active as in the inactive animal. The rate of shell valve movement rose and the rate of heart beat fell when the foot was extended. The rates of heart beat and shell valve movement decreased when the water was saturated with carbon dioxide. This heart response remained when the visceral ganglion was destroyed. Ventricular contraction occurred simultaneously over the whole chamber. The passage of blood into the posterior aorta could be restricted by the protuberances on its wall. Pericardial cavity pressure rose by about 5 cm H2O at shell valve adduction and 0·25–0·6 cm H2O at ventricular diastole. Pulse pressure changes of 0·25–0·6 cm H2O occurred in the auricle and 1–3 cm H2O in the ventricle and anterior aorta.
Modes of stimulation of the teleost ear
Authors: Fay R. R. , Popper A. N. 
Published: April 2021

ABSTRACT
Microphonic potentials were recorded from the inner ears of a catfish (Ictalurus punctatus) and an African mouthbreeder (Tilapia macrocephala) in response to underwater sound stimulation and direct vibration of the head. The shape of the vibratory isopotential functions of frequency was similar in both species up to 600 Hz. Above 600 Hz, the sensitivity of Ictalurus continued to increase to 4000 Hz while the sensitivity of Tilapia declined.
Deflation of the swim bladder did not affect the response to vibration in either species, the response of Tilapia to the underwater sound stimulus being minimal and unaffected by removal of the swim bladder.
Ictalurus was pressure-sensitive to above 4000 Hz, there being a significant decline in the response with deflation of the swimbladder.
The transmission of impulses in the ectodermal slow conduction system of the sea anemone Calliactis parasitica (Couch)
Authors: Shelton G. A. B. 
Published: April 2021

ABSTRACT
The SS 1 fatigues in response to repetitive electrical stimulation. This fatigue is manifested by an increased conduction delay and a decreased SS 1 pulse amplitude. Continued repetitive stimulation leads to the failure of the system. Recovery may take many seconds. Narrow strips of column fail more rapidly than wide strips. The increased conduction delay is explained in terms of a decrease in the population of spiking cells. A computer model is described and analysed. It suggests that conduction between electrically coupled ectoderm cells could be the basis for the SS 1. The SS 1 may have properties not so far experimentally demonstrated; for example, under certain conditions it could behave as a local system.
An in vitro bioassay for a molluscan gonadotropin
Authors: Wells M. J. , O’Dor R. K. , Buckley S. K. L. 
Published: April 2021

ABSTRACT
Protein synthesis occurs at a high rate in the ovaries of maturing Octopus vulgaris and can be measured from the incorporation of [14C] leucine in vivo and in isolated groups of eggs in vitro. Removal of the optic glands in vivo 1–3 days prior to testing markedly reduces amino acid incorporation in vivo or in vitro. After 5 days in vivo incorporation stops. The rate of incorporation in vitro is increased by the addition of optic gland extract. Analysis of the kinetics of leucine uptake and incorporation in vitro indicates that the hormone has an effect on the inward transport of leucine which is independent of its action on protein synthesis. Electron-microscope studies of the follicle cells and ova show that the former are the site of protein synthesis. Changes in either uptake or incorporation into protein by the follicle cells can be used as a qualitative biological assay for the optic gland hormone. Uptake is very easy to measure but incorporation is the more sensitive parameter. Either is potentially suitable as a quantitative assay for this and perhaps also for other molluscan gonadotropins.
Corpus allatum activity in vitro during ovarian maturation in the desert locust, Schistocerca gregaria
Authors: Tobe S. S. , Pratt G. E. 
Published: April 2021

ABSTRACT
Radiochemical in vitro assays show that there are large and rapid changes in the spontaneous rate of juvenile hormone synthesis and release during the course of sexual maturation in the locust. Parallel observations on glands incubated with farnesenic acid show that the rate-limiting step is always prior to the stage of esterification of farnesenic acid to the final intermediate, methyl farnesoate. Corresponding changes in oocyte morphometrics do not reveal any clear correlation between endocrine activity of the corpus allatum and either the induction or maintenance of rapid vitellogenesis. Peaks of synthetic activity in the corpus allatum correspond well with the onset of previtellogenic growth in the oocytes. The data do not provide any evidence that ‘corpus allatum insufficiency’ is responsible for resorption of growing oocytes. It is concluded that short-term in vitro radio-assays provide a valid method for estimating quantitatively the physiological activity of the corpus allatum.
The Mechanism of Statocyst Operation in the Mysid Shrimp Praunus Flexuosus
Authors: Neil D. M. 
Published: April 2021

ABSTRACT
Analysis of the compensatory eyestalk responses of mysid shrimps before and after the removal of one statocyst has revealed, in the light of statocyst anatomy, that the two statocysts co-operate in their action at all angles of body tilt.Many features of statocyst operation in mysids are shared by decapod crustaceans, but an important difference exists between the geometries of the two statocyst systems. The consequences of this difference highlight the structural constraints on systems of statolithic gravity receptors for which shear magnitude is the adequate stimulus.
Problems associated with the use of tetraethylammonium to test for monosynaptic connexions
Authors: Berry M. S. , Pentreath V. W. 
Published: April 2021

ABSTRACT
Several investigators of the molluscan nervous system have used TEA, injected into presynaptic neurones, to determine whether the connexions made by these neurones are monosynaptic. The increase in spike duration produced by the TEA causes an increase in transmitter release, and hence an increase in the amplitude of the postsynaptic potential if the connexion is direct. If the connexion is indirect, the spike in an intercalated neurone will not be affected by the TEA, and the postsynaptic response will remain constant. Experiments described here show that TEA can cross electrotonic junctions in the gastropod mollusc Planorbis comeus. They also show that each TEA-prolonged presynaptic impulse may produce more than one postsynaptic impulse. A larger postsynaptic potential could therefore be produced by presynaptic injection of TEA in the case of an indirect connexion. This indicates that care must be taken when interpreting the results of experiments using TEA to test for monosynaptic connexions.
The control of diuresis in the tsetse fly Glossina austeni: a preliminary investigation of the diuretic hormone
Authors: Gee J. D. 
Published: April 2021

ABSTRACT
The rate of secretion of the Malpighian tubules of Glossina austeni is controlled by a diuretic hormone. This hormone is present in the nervous tissue of the fly together with a degradative enzyme that can be inactivated by boiling. It is demonstrated that the Malpighian tubules are able to destroy the diuretic hormone; they may therefore participate in the control of diuresis. The diuretic hormone appears to be a heat-stable, non-dialysable, alcohol-soluble molecule, containing amino acid, glucose and sialic acid residues.
Localization and electrical activity of the distance chemoreceptors that mediate predator avoidance behaviour in Acmaea limatula and Acmaea scutum (gastropoda, prosobranchia)
Authors: Phillips David W. 
Published: April 2021

ABSTRACT
The marine gastropods Acmaea (Collisella) limatula and Acmaea (Noto-acmea) scutum respond to distant predatory starfish (i.e. to starfish scent) by moving up a vertical surface. The distance chemoreceptors that mediate this avoidance behaviour are located on the mantle margin. Heat cauterization of the limpets’ mantle margin eliminates their responsiveness to Pisaster ochraceus scent, while a similar cauterization of the ctenidium and the osphradia does not diminish the avoidance behaviour. Primary afferent electrical activity can be recorded from the chemo-receptors on the mantle margin that are responsive to starfish scent and also from other physiologically distinct receptors that are responsive to contact with starfish tube feet.
The innervation of the salivary gland of the moth, Manduca sexta: evidence that dopamine is the transmitter
Authors: Robertson H. A. 
Published: April 2021

ABSTRACT
Using the Falck-Hillarp histochemical technique for monoamines, evidence was found for the presence of a catecholamine in the salivary gland nerves of the moth, Manduca sexta. The innervation was studied with the electron microscope. Only the fluid-secreting region of the gland is innervated and the nerve endings are characteristic of monoamine-containing terminals. Using a sensitive enzymatic-isotopic assay for catecholamines, it was found that whole salivary glands contain 0·33 μ g/g dopamine but no nor-adrenaline. It seems likely that dopamine mediates fluid-secretion in the salivary gland of Manduca as it does in a number of other arthropods.
Regeneration of peripheral nerves to supernumerary legs in cockroaches
Authors: Westin J. , Camhi J. M. 
Published: April 2021

ABSTRACT
Clusters of legs were grown from metathoracic coxae of the cockroach. Legs of a cluster had different segmental origins, sizes, and orientations. Regenerating metathoracic nerves tended to enter the nearest leg, and to a lesser extent of the largest leg, but showed no significant tendency to penetrate metathoracic rather than prothoracic legs, or normally oriented rather than abnormally oriented legs. Movements of legs were evoked by nerve stimulation significantly more often in nearest, largest, and normally oriented legs, but were equally frequent in prothoracic and metathoracic legs. Close proximity of peripheral nerves is not required for the differentiation of the legs, since nerves were visible in the legs only at the later stages of their development, and many of the legs were apparently never innervated.
Motor innervation within supernumerary legs of cockroaches
Authors: Westin J. , Camhi J. M. 
Published: April 2021

ABSTRACT
Clusters of legs having prothoracic and metathoracic origins were grown from the metathoracic coxa of the cockroach. Of these legs, those which were innervated contained only one, or occasionally two, of the three major nerves innervating the cockroach leg. Stimulation of a particular leg nerve (no. 3, 5 or 6) evoked movement at the same joints and in the same directions in a leg having only one nerve as in a normal leg. Stimulation of a particular metathoracic nerve generally produced the same movements in a prothoracic leg transplanted to the metathoracic site as it did in a regenerated or intact metathoracic leg.
The branchial chloride pump in the goldfish Carassius auratus: relationship between Cl-/HCO3- and Cl-/Cl- exchanges and the effect of thiocyanate
Authors: de Renzis G. 
Published: April 2021

ABSTRACT
The effect of thiocyanate on chloride and sodium fluxes across the gill was studied in the goldfish Carassius auratus. At low external chloride concentrations, addition of SCN− to the bathing solution markedly inhibited chloride influx and efflux, the net flux being reversed. SCN− injection was without effect. SCN− had no effect on sodium fluxes when injected or added to the external medium. The inhibition of chloride influx by SCN− was of a mixed type involving simultaneous modifications of the affinity constant of the carrier for Cl− and of the maximal Cl− influx. The affinity constant of the carrier for SCN− was 10 times lower than that for Cl−. The gill of the goldfish was found to be practically impermeable to SCN−. In the presence of external SCN−, the C1−/HCO3− exchange was reversed : Cl− was lost against HCO3− which is absorbed. This suggests an obligatory exchange. Exchange diffusion for chloride was also demonstrated. A kinetic model is proposed to explain chloride and bicarbonate transport across the gill of Carassius auratus.
An automatic respirometer for determining oxygen uptake in crayfish (Austropotamobius pallipes (Lereboullet)) over periods of 3-4 days
Authors: Sutcliffe D. W. , Carrick T. R. , Moore W. H. 
Published: April 2021

ABSTRACT
An automatic respirometer has been developed for continuous measurements over 3–4 days on 1–15 g crayfish. The sensor is a modified Mack-ereth oxygen electrode. Respiration is recorded on a millivolt potentiometric pen recorder during closed periods when the O2 concentration in the medium falls to a predetermined level. A solenoid-operated valve is then opened via a relay circuit energized by a reed switch mounted on the recorder. Medium flows through the respirometer until the O2 concentration is raised back to another predetermined level. Artificial media containing little or no nutrient salts are used to restrict the growth of microbes. Respiration was determined chiefly on crayfish (Austropotamobius pallipes) with body wet weights of 7·0–12·5 g at 10·0°C. In unrestrained but relatively quiescent animals, standard metabolism is described by the regression equation, In O2 uptake = 3 ·3037 +1 ·002 In body wt. In restless crayfish active metabolism is described by the equation, In O2 uptake = 4 ·4412 + 0 ·861 In body wt.
Co-ordinating interneurones of the locust which convey two patterns of motor commands: their connexions with ventilatory motoneurones
Authors: Burrows M. 
Published: April 2021

ABSTRACT
The interneurones which make widespread connexions with flight motoneurones also synapse upon ventilatory motoneurones so that in all 50 motoneurones receive synapses. They influence three aspects of ventilation; (a) the closing and opening movements of the thoracic spiracles, (b) some aspects of abdominal pumping movements and (c) the recruitment of some motoneurones controlling head pumping. The two closer motoneurones of a particular thoracic spiracle receive the same excitatory synaptic inputs (EPSPs) during expiration. The EPSPs match those in appropriate flight motoneurones. The closer motoneurones of each thoracic spiracle whose somata are in the pro-, meso-or metathoracic ganglia all receive the same excitatory synaptic inputs. These inputs are an adequate explanation of the pattern of spikes in the closer motoneurones. Both the slow ventilatory and fast rhythms of synaptic potentials are expressed as spikes; the slow as the overall expiratory burst of spikes and the fast as the groups of spikes within that burst. This establishes a ventilatory function for the interneurones. All thoracic closer motoneurones therefore receive the same excitatory commands which will tend to synchronize the movements of each spiracle. Spiracular opener motoneurones are inhibited during expiration, their IPSPs matching the EPSPs in flight or closer motoneurones. Therefore the interneurones have reciprocal effects on the antagonistic motoneurones of the spiracles. The interneurones synapse upon some motoneurones which control the pumping movements of the abdomen and which have their somata in the metathoracic or first unfused abdominal ganglion. Motoneurones in four separate ganglia therefore receive inputs from these interneurones. The interneurones also synapse upon motoneurones which control an auxiliary form of ventilation, head pumping.
The action of the excretory apparatus of Calliphora vomitoria in handling injected sugar solution
Authors: Knowles G. 
Published: April 2021

ABSTRACT
Recent evidence suggests that the isolated Malpighian tubules of Calliphora possess mechanisms which restrict the loss of glucose and trehalose from the insect. This report establishes that the intact, diuresing fly does not excrete glucose or trehalose when solutions of these sugars are injected. When solutions of non-metabolized sugars such as sorbose and xylose are injected into the fly, these sugars are rapidly excreted. High concentrations of sorbose and xylose are found in the urine, suggesting that rapid reabsorption of fluid occurs in the excretory apparatus even during the diuresis which the injections provoke. However, injected sucrose is apparently not excreted in large amounts and it is possible that the Malpighian tubules when functioning in vivo are impermeable to disaccharides.
The receptive fields of Daphnia ommatidia
Authors: Young S. , Downing A. C. 
Published: April 2021

ABSTRACT
The focal length and positions of the principal planes of an isolated Daphnia lens were determined, and the refractive index of the rhabdom was measured. The lens can form an image, but this always lies well behind the rhabdom. This was confirmed by direct observation of images inside a clear-eye mutant Daphnia eye. The rhabdom was shown to be unlikely to function as a waveguide, and a ray optics model is proposed to enable the prediction of ommatidial receptive fields from the lens data. The predicted receptive fields have wide plateaus and steep sides, and there are virtually no totally blind gaps between neighbouring ommatidia.
Properties of the trochanteral hair plate and its function in the control of walking in the cockroach
Authors: Wong R. K. , Pearson K. G. 
Published: April 2021

ABSTRACT
The physiological properties of the group of long hair sensilla of the trochanteral hair plate in the cockroach metathoracic leg were studied. The sensilla were divided into type I and type II according to their responses to imposed displacements. Type I hair sensilla responded to dynamic displacements whereas type II hair sensilla responded to both dynamic and static displacements. The hair sensilla are normally excited by phasic flexion movements of the femur near the end of leg protraction. Activity in the trochanteral hair plate afferents had a short latency excitatory effect on the motoneurone producing slow extension movements of the femur and an inhibitory effect on the femur flexor motoneurones. Removal of the trochanteral hair plate in one leg caused overstepping of that leg in a walking animal due to exaggerated flexion of the femur. This change in leg movement can be explained by the removal of the inhibitory influence from the hair plate afferents to the femur flexor motoneurones. We conclude that one function of the trochanteral hair plate is to limit femur flexion during a step cycle.
Printed circuit microelectrodes and their application to honeybee brain
Authors: Pickard R. S. , Welberry T. R. 
Published: April 2021

ABSTRACT
The application of printed circuit technology to the production of a new type of multi-channel microelectrode is described. Recordings have been obtained from the protocerebrum of the honey bee Apis mellifera L. using printed circuit microelectrodes in both restrained and free-moving preparations. These recordings are compared with those previously obtained from conventional probe microelectrodes and are found to have similar characteristics of transient voltage changes superimposed on an undifferentiated high frequency background. A wide range of development possibilities for the printed circuit microelectrode are discussed.