bluuebunny/crossref_metadata_2025_split huggingface dataset:
Respiration in An Air-Breathing Fish, The Climbing Perch Anabas Testudineus Bloch
Authors: Hughes G. M. , Singh B. N. 
Published: April 2021

ABSTRACT
Respiration of the climbing perch Anabas has been studied under five different experimental conditions, (a) The mean O2 consumption of a fish allowed free access to air, is about 113 c.c./kg/h at 25 °C. The fish obtain nearly equal amounts of oxygen through the gills and through the accessory organs. (b) The overall O2 consumption from water of a fish allowed free access to nitrogen is nearly the same as during normal respiration from water with access to air. (c) The O2 consumption is reduced when the fish is out of water and obtains all its oxygen from air. (d) The O2 consumption from air increases considerably when the fish is maintained in de-oxygenated water and depends upon surfacing for its oxygen supply, (e) The O2 consumption of a fish kept in aerated water and prevented from surfacing remains at a minimum level relative to the other four conditions. Much more carbon dioxide is released through the gills than through the accessory organs (10:1) when the fish respires from aerated water with access to air. The accessory organs are much more important for O2 uptake. The respiratory quotient is approximately 1 when the fish is in aerated water, with or without access to air, but is only 0·7 when the fish is out of water. Anabas can live out of water for 6–10 h if protected from dehydration. It continues to breathe quietly in air-saturated water using its gills alone for shorter periods (6–8 h) when denied free access to air.
Properties of Action Potentials from Insect Motor Nerve Fibres
Authors: Pearson K. G. , Stein R. B. , Malhotra S. K. 
Published: April 2021

ABSTRACT
The properties of nerve action potentials in small insect motor nerves were studied using extracellular recording electrodes. A length of nerve was lifted out of solution and recordings were made with respect to the solution either from an intact nerve (triphasic recording) or from near a cut end of the nerve (monophasic recording). In a cockroach nerve, the number of spontaneously active fibres was small enough that corresponding nerve fibres could be identified in each preparation by their action potential amplitude and their pattern of activity. Under controlled conditions, the absolute amplitudes of either monophasic or triphasic records were reproducible and could be used to calculate fibre diameter. The calculations were confirmed from histological sections of the nerve. Conduction velocity varied approximately as the 0·78 power of fibre diameter in a cockroach nerve and as 0·7 power of fibre diameter in a locust nerve. These values are considerably larger than the square root relation predicted if membrane properties are independent of fibre diameter. Membrane properties probably vary with fibre diameter since the action potential duration increases dramatically for fibres below 5 μ in diameter. For the cockroach nerve systematic structural differences between fibres of different sizes are also seen with the electron microscope and the relation of these to the functional differences is considered.
Regulation of Cellular Osmolarity and Volume in Tetrahymena
Authors: Stoner Larry C. , Dunham Philip B. 
Published: April 2021

ABSTRACT
Tetrahymena pyrifor mis are hyperosmotic to external media of osmolarities from 2 to 171 m-osmole/1. The intracellular osmolarity, determined by freezing-point depression, is 111 m-osmole/kg cells in dilute media, and increases linearly with increasing external osmolarities. Over 80% of the intracellular osmolarity can be attributed to the concentration of sodium, potassium, chloride and the free amino acids. In response to an increase in the external osmolarity, Tetrahymena regulates its intracellular osmolarity by increasing the concentrations of free amino acids. The regulation of cellular volume under conditions of osmotic stress is achieved by an increase in the amount of osmotically active solutes and the regulation of the rate of elimination of fluid by the contractile vacuole.
The Effects of Laser Microbeam Irradiation On the Flagellum of Crithidia (Strigomonas) Oncopelti
Authors: Goldstein S. F. , Holwill M. E. J. , Silvester N. R. 
Published: April 2021

ABSTRACT
Flagella and cell bodies of Crithidia (Strigomonas) oncopelti were irradiated at preselected points with a pulsed ruby laser microbeam. Results were recorded by high-speed cinephotomicrography. A flagellum could be completely amputated at the irradiated point. The portion of the flagellum between the cell body and the irradiated point beat from the base after irradiation. The amputated portion of the flagellum could beat from either the tip or the irradiated point, and could beat first from the tip and then from the irradiated point or vice versa. Beating could continue for up to ten cycles. For flagellar activity in this organism neither a unique region of the flagellum nor the cell body is necessary. Wave propagation appears to involve the transmission of a signal at a greater velocity than that of the wave. The results favour a model of bend propagation which allows for a distribution of autonomous initiators along the flagellar length.
Symmetry and Non-Linearity of Osmotic Flow Across Rectal Cuticle of the Desert Locust*
Authors: Phillips J. E. , Beaumont C. 
Published: April 2021

ABSTRACT
A method for measuring osmotic flow of water across rectal cuticle of the desert locust in vitro is described. The osmotic permeability coefficient decreases as the average osmolality of the two bathing solutions increases, probably due to dehydration of the cuticle. This is supported by a corresponding decrease in the diffusion permeability coefficient, as measured by flux of tritiated water in the absence of osmotic flow. Osmotic permeability is at least fifty times greater than diffusion permeability. This supports the hypothesis that osmotic flow occurs by bulk flow or single-file diffusion through pores. Isotopic flux measurements during net flow support this view. The osmotic permeability of the cuticle differs by less than 25% if at all, in the two directions of flow; that is, rectification or ‘valve-like’ behaviour is not significant. The cuticle represents only 2·6 to 13% of the total resistance to osmotic flow across the whole rectal wall and is not responsible for the asymmetry of the latter. Application of Beament’s model for water transport to the rectal wall of insects can be excluded in the case of the desert locust.
Factors Regulating the Discharge Frequency in Optomotor Fibres of Carcinus Maenas
Authors: Wiersma C. A. G. , Fiore L. 
Published: April 2021

ABSTRACT
The influence of the excited state of the animal on various motor neurone discharges and accompanying muscle action potentials was studied in the eyestalk of the crab, Carcinus maenas. In most cases large increases in firing frequency could be obtained during such states. An exception is the tonic eye-withdrawal system in which an inhibitory effect is caused. A pronounced difference in habituation to constant stimuli between spring and summer was found for the position fibres; in spring it was slow and in summer much quicker.
The Effect of Thermal Acclimation On the Heat Tolerance of the Intertidal Prosobranchs Littorina Littorea (L.) and Monodonta Lineata (Da Costa)
Authors: Newell R. C. , Pye V. I. , Ahsanullah M. 
Published: April 2021

ABSTRACT
The effect of exposure time and acclimation temperature on the survival of the winkle Littorina littorea and the topshell Monodonta lineata is described. It was found that acclimation to temperatures between 5 and 16°C enhanced survival whereas acclimation to temperatures above 21°C resulted in little further elevation of the heat-lethal temperature. The process of thermal acclimation is accomplished by raising the heat tolerance of the less-resistant individuals more than that of other members of the population. The increase in sea temperatures which occurs with the onset of summer is sufficient to extend the thermal tolerance so that unusually high temperatures can be tolerated when the animals are uncovered by the tide.
Coxal Depressor Muscles of the Cockroach and the Role of Peripheral Inhibition
Authors: Iles J. F. , Pearson K. G. 
Published: April 2021

ABSTRACT
Mechanical properties of the coxal depressor muscles of cockroaches have been studied and found to be compatible with the pattern of innervation determined by microelectrode recording. During walking activity excitatory and inhibitory axons to the slow depressor muscles are alternately active in bursts. Firings of the three inhibitory axons are positively correlated. The rate of relaxation of the slow muscles is increased by activation of the inhibitory axons innervating them. It is proposed that one functional significance of peripheral inhibition in insects is to increase the rate of relaxation of slow muscles used in rapid movements.
Electrical Correlates of Ciliary Reversal in Oikopleura
Authors: Galt C. P. , Mackie G. O. 
Published: April 2021

ABSTRACT
Reversal of the water current through the pharynx of Oikopleura is brought about by a change in the action of the cilia of the two stigmatal ciliated rings. These ‘ciliary reversals’ occur synchronously in the two ciliated rings and can be evoked by the addition of particulate material to the incoming water or by tactile or electrical stimulation of the lips. Nerves run from the lips via the brain to individual ciliated cells, and it is therefore likely that the ciliated cells are under nervous control. At each ciliary reversal an electrical potential can be picked up on the body surface. The same events are recorded by microelectrodes inserted into the ciliated rings. The microelectrode recordings resemble intracellular recordings, and the reversal potentials are considered to represent depolarizations of the membranes of the ciliated cells. Ciliary reversals continue after removal of the brain, suggesting the existence of a peripheral pacemaker.
Preliminary Observations on the Ionic Regulation of the Arctic Char Salvelinus Alpinus
Authors: Roberts R. A. 
Published: April 2021

ABSTRACT
The degree of euryhalinity in a fresh-water resident population of the arctic char, Salvelinus alpinus, has been determined. Although isolated in fresh water for c. 10000 –12000 years these fish still show a high degree of salinity tolerance characteristic of their ancestral stock, but this is variably developed in individuals. In fresh water, blood sodium concentration is regulated at 150 mM/1 and chloride at 130 mM/1. These increase to 233 and 218 mM/1 respectively in sea water. Fish in sea water show a large increase in muscle sodium, although the potassium concentration is only slightly higher than that maintained in fresh water. The total sodium content of the fish reflects the increase observed in the intracellular and extracellular compartments. The rate of sodium turnover in sea-water-adapted fish is some ten times higher than in fresh-water-adapted fish, although it is significantly lower than that observed in most sea-water-adapted teleosts.
The Effect of Environmental Calcium and Ovine Prolactin on Sodium Balance in Fundulus Kansae
Authors: Potts W. T .W. , Fleming W. R. 
Published: April 2021

ABSTRACT
The sodium contents and rates of turnover of sodium have been determined in both intact and hypophysectomized Fundulus kansae in a variety of media. A reduction of the calcium content of fresh water from 1·0 to 0·1 mM/1 increased the rate of sodium efflux by half while transter to calcium-free water increased the rate several fold. The rate of sodium efflux increased fourfold in sea water containing no magnesium and only 1 mM/l calcium. Hypophysectomy increased the rate of efflux in fresh water but reduced it in sea water. Intact fish adapted to sea water and treated with prolactin showed a net gain of sodium probably due to a reduction in the activity of the sodium efflux pump. Both intact and hypophysectomized fish on transfer from sea water to fresh water reduced the rate of efflux of sodium in a series of stages. Studies of the rate of efflux of sodium before and after transfer between various media showed no evidence of exchange diffusion or of a linked sodium-potassium efflux pump, but did show evidence or interaction between sodium and chloride fluxes probably as a consequence of potential changes. The rate of efflux of sodium from F. kansae doubled following hypophysectomy. The ability of hypophysectomized F. kansae to survive in fresh water after hypophysectomy, unlike F. heteroclitus, is due to a more effective uptake system.
The Organization of Escape Behaviour in the Crayfish
Authors: Wine Jeffrey J. , Krasne Franklin B. 
Published: April 2021

ABSTRACT
Invertebrate escape reflexes have long been favoured preparations for investigating neuronal substrates of behaviour. The large size of many of their component neurones make them accessible to current micro-electrode techniques, and selection pressures for rapidity of response have probably caused them to evolve in the direction of the maximal neurological simplicity consistent with their function. Indeed, given our current technical and conceptual limitations, they are probably among the very few behaviour patterns that we may presently hope to analyse with any degree of completeness.
Adaptation in the Compound Eye and Interaction with Screening Pigment
Authors: Yinon U. 
Published: April 2021

ABSTRACT
The electroretinogram pattern in the compound eye of T. molitor and the appearance of irregular small potentials and spikes superimposed on the ERG are influenced during dark and light adaptation procedures.
The amplitude of the principal negative potential reflects bleaching and recovery of the photochemical process. This is not true for the latency values. The delay of the electrical response increases in the dark and decreases in the light adapted eye. These changes were influenced by the intensity of the adapting light.
Mutant eyes only lack screening pigment and have normal visual neural pathways. The absence of this pigment lowered the threshold sensitivity of the unscreened eye in dark adaptation. The difference between the adaptation processes in mutants and normal animals has been suggested as a criterion for measuring the net effect of the screening pigment in the compound eye.
A Study of the Function of the Neural Fat-Body Sheath in the Stick Insect, Carausius Morosus
Authors: Treherne J. E. 
Published: April 2021

ABSTRACT
The effects of variation in the sodium concentration of the bathing media on axonal function has been measured in de-sheathed connectives in the presence of the overlying neural fat-body sheath. The response to solutions of the same sodium concentration as the haemolymph (15 mM/1) was found to be essentially similar to that recorded in de-sheathed connectives in the absence of the fat-body sheath, there being a rapid decline in amplitude of the recorded action potentials in both preparations. On the basis of these observations it is concluded that the neural fat-body sheath is unlikely to be involved in the regulation of the extra-neuronal sodium level.
The Corpus Allatum and Oogenesis in Rhodnius Prolixus (Stål.)
Authors: Pratt G. E. , Davey K. G. 
Published: April 2021

ABSTRACT
In females which have been re-fed after various periods of fasting there is a delay in the resumption of ovarian growth which becomes greater with longer periods of starvation. In females kept without food for 28 days before re-feeding, vitellogenesis is not resumed until 4 or 5 days after the meal, whereas the concentration of yolk antigen in the haemolymph returns to its normal level by the third day after the meal. A period of starvation induces an accumulation of oocytes in the size range below that of activation until the fourth or fifth day after re-feeding, when the terminal oocytes pass rapidly through the critical size range and enter vitellogenesis. The tropharia of starved females exhibit a remarkably reduced affinity for the protein stain Ponceau S, and enlarged trophocytes with their characteristic inclusions are absent during the first 6 days after re-feeding.
The Corpus Allatum and Oogenesis in Rhodnius Prolixus (Stål.)
Authors: Pratt G. E. , Davey K. G. 
Published: April 2021

ABSTRACT
Mated females lay more eggs than virgin females. They also oviposit earlier in the cycle, and at a higher rate, than virgins. Mated females produce, slightly more than two oocytes per ovariole. Virgin females produce a little more than one oocyte per ovariole. The first wave of oogenesis proceeds at the same rate in mated and virgin females, whereas the second wave is inhibited in virgins. The concentration of yolk protein in the haemolymph remains high for longer in virgins than in mated females. The inhibition of egg production during the second wave of oogenesis in virgins is thus not a consequence of a previous decline in yolk protein titre. Virgin females digest their blood meal more slowly than mated females. The follicular epithelium of an oocyte in the second wave of oogenesis in a virgin shows sparsely scattered intercellular spaces, whereas that of an oocyte from the first wave exhibits the abundant spaces characteristic of a follicle from a mated female. During the time when vitellogenesis is inhibited in virgins there is an accumulation of oocytes in the size range below that of activation. The corpora allata of both mated and virgin females undergo a cycle of increase in size associated with the cycle of oogenesis. There are no differences which can be correlated with the differences in the activities of the ovaries of mated and virgin females. Topical application of farnesyl methyl ether (FME) to decapitated mated females brings about egg development equivalent to that of virgin females. Topical application of FME to virgin females results in the production of the number of eggs characteristic of mated females, but very high doses are necessary to achieve this. These dose levels also result in an increase in rate of oviposition. These effects of high doses of FME are abolished if the virgin females lack their neurosecretory cells. It is concluded that the virgin inhibition of oogenesis results not from a deficiency of allatum hormone, but from the presence of an antigonadotropin released from ovaries which contain mature eggs.
Active Chloride Transport by the Gills of Rainbow Trout (Salmo Gairdneri)
Authors: Kerstetter Theodore H. , Kirschner Leonard B. 
Published: April 2021

ABSTRACT
The kinetics of chloride transport by the irrigated trout gill have been studied. The transport system is saturable, and the half-saturation value is about 0·25 mM. Chloride uptake occurs equally well from solutions of non-penetrating cations and from NaCl solutions. The presence of potassium in the irrigating solution, however, significantly inhibits chloride uptake. The trout gill is permeable to potassium, and there appears to be an active component to potassium influx. Chloride transport is stimulated by injections of NaHCO3 and (NH4)HCO3. The carbonic anhydrase inhibitor, acetazolamide, has no apparent effect on chloride influx, and it is suggested that if a exchange exists in the trout gill, sufficient can be supplied by the blood. The mean intracellular potential (relative to the irrigating solution) of five gill filament cells was − 32 mV. This indicates the presence of an energy barrier to chloride uptake at the outer membrane of the epithelium, and therefore it is postulated that an active step for chloride transport is located on this membrane.
Function of the Neural Sheath in Marine and Freshwater Molluscs. Evidence for Restriction of Sodium Loss in Freshwater Species
Authors: Twarog Betty M. , Hidaka T. 
Published: April 2021

ABSTRACT
Action potentials were observed in cerebrovisceral connectives of a marine bivalve, Mytilus edulis L., and two species of freshwater bivalve, Anodonta cataracta and Elliptio complanata. In Mytilus nerve, responses to stimulation in both the intact and the de-sheathed nerve were blocked after two minutes in a sodium-free saline. Restoration of normal sodium levels reversed the block within 5 min. In nerves of the freshwater species, Anodonta and Elliptio, the action potential of the sheathed nerve altered very slightly after one hour of stimulation in a sodium-free solution. The completely de-sheathed nerve, however, was blocked within one minute in sodium-free saline. The block was rapidly reversible. It is concluded, contrary to conclusions of previous investigators, that the neural sheath in freshwater clams is just as vital to restriction of sodium loss as it is in amphibia and insects, and it would seem logical to seek out a common denominator of sheath function. Several possible mechanisms are put forth and discussed.
Effects of Temperature on Branchial Sodium-Exchange and Extrusion Mechanisms in the Seawater-Adapted Flounder Platichthys Flesus L
Authors: Maetz J. , Evans D. H. 
Published: April 2021

ABSTRACT
The effect of temperature on osmoregulation of teleosts has been investigated in several laboratories. In fresh water acclimatization to low temperature is accompanied by a decline in plasma levels of sodium and chloride, while in sea water, on the contrary, low temperature causes an increase in the concentrations of the major electrolytes (Umminger, 1969, 1970; see review by Pickford, Grant & Umminger, 1969).
Branchial Sodium Exchange and Ammonia Excretion in the Goldfish Carassius Auratus. Effects of Ammonia-Loading and Temperature Changes
Authors: Maetz J. 
Published: April 2021

ABSTRACT
Krogh (1939) first suggested that in freshwater animals branchial or cutaneous excretion of ammonia may be related to sodium absorption. In both freshwater Crustacea (Astacus pallipes) and teleosts (Carassius auratus) independent active transport of Na+ and Cl− from the outside medium have been definitely established (Shaw, 1960a–c; Garcia Romeu & Maetz, 1964). Sodium in particular may be absorbed at very high rates without an accompanying anion. The maintenance of the electroneutrality of the external and internal media necessitates an exchange with an endogenous ion during sodium movement. The possibility that ammonium ions may fulfil this role is suggested by the fact that the gill is the main site of ammonia excretion (Smith, 1929,1953) and indirect experimental evidence has supported this hypothesis. Addition of ammonia to the outside medium, a procedure which inhibits ammonia excretion, interferes with the sodium uptake (Shaw, 1960a; Maetz & Garcia Romeu, 1964). Injection of ammonium ions, a procedure which increases ammonia excretion by the gill, produces an increase of sodium uptake in the goldfish (Maetz & Garcia Romeu, 1964) and in the eel (Garcia Romeu & Motais, 1966). No stoichiometric relationship between ammonia excretion rate and sodium net uptake in relation to experimental external salinity changes is, however, observed in the crayfish (Shaw, 1960b). Thus the exchange cannot be obligatory. In particular when ammonia excretion falls short of sodium uptake, a second exchange process, Na+ against H+, is thought to be operative, or when sodium uptake is blocked at low external sodium concentration, ammonium is thought to be accompanied by endogenous bicarbonate ions excreted by the gill (Shaw, 1960b).