bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the Absorption and Metabolism of D-(u-14C) Glucose by Polymorphus minutus (Acanthocephala) in vitro
Authors: Crompton D. W. T. , Lockwood A. P. M. 
Published: April 2021

ABSTRACT
The absorption and initial metabolism of glucose by the acanthocephalan Polymorphus minutus have been studied in vitro under conditions designed to approximate to those in vivo. The results of the investigation of the absorption of glucose are compatible with the assumption that a carrier system is involved in the transport of glucose. The carrier system is half-saturated at an external glucose concentration of about 0·25 mg./ml. and is tending towards full saturation when the external glucose concentration reaches 2·0 mg./ml. P. minutus has been shown to be capable of absorbing glucose against a concentration gradient. The rate of glucose absorption, at a given glucose concentration, has been found to fall when the worms have been acclimatized to that concentration. It has been estimated that P. minutus requires about 4 μg. glucose/mg. wet weight of worm/hr. in vivo, assuming that the external glucose concentration is at least 2·0 mg./ml. After 4 hr. incubation with radioactive glucose the radioactive label has been detected in a variety of metabolites extracted from the worms. Evidence is presented indicating that these include : glucose, sugar phosphates, maltotriose, UDPG, glycogen, amino sugars, amino acids and organic acids. Trehalose has not been detected in P. minutus, and a possible evolutionary significance of this result is discussed.
The Oxygen Consumption of An Echiuroid, Bonellia viridis Rolando
Authors: Brafield A. E. 
Published: April 2021

ABSTRACT
The oxygen consumption of the echiuroid Bonellia viridis has been investigated by means of a continuous-flow polarographic respirometer. The general rate of oxygen consumption per unit dry weight is similar to that characteristic of polychaetes, and declines exponentially with increasing body size. The rate of oxygen consumption rises in the light and falls again if darkness is restored. The oxygen consumption of the isolated proboscis plus that of the isolated body region corresponds closely to that of the entire animal. The oxygen consumption per unit dry weight of the proboscis is considerably higher than that of the body region. The oxygen consumption of an isolated body region increases in the presence of light, but that of an isolated proboscis does not. These findings are discussed in relation to the biology of the animal, observed muscular activity, and the occurrence of the pigment bonellin.
Effects of Sub-Lethal High Temperature on An Insect, Rhodnius prolixus (Stål.)
Authors: Okasha A. Y. K. 
Published: April 2021

ABSTRACT
Protease activity of the mid-gut of 5th-stage larvae was studied under different conditions. The activity is not detectable in the unfed insect, but increases after feeding, reaching a maximum just before ecdysis. In insects kept at high temperature immediately after feeding, protease activity is approximately normal for the first 2 days, but thereafter it decreases; after transfer to normal temperature the activity starts to increase. Decapitation reduces protease activity under normal temperature conditions. Possible hormonal control of digestion is discussed, and it is suggested that the brain hormone is involved. The concentration of free amino acids in the haemolymph greatly increases at high temperature, but returns to the normal level after transfer to normal temperature. The adjustment to the normal level does not occur if the insects are decapitated immediately after transfer. The concentration of protein in the haemolymph at high temperature does not recover from the initial decrease. After transfer to normal temperature there is a tendency to a very slow increase. Protein synthesis is impaired at high temperature and thus amino acids accumulate in the haemolymph, since they are not used in protein metabolism. It is concluded that the impairment of protein synthesis results in the cessation of moulting, of cell division in the epidermis during wound healing, and of the secretion of the brain hormone
Changes in the Nucleic Acid and Protein Composition of the Nasal Glands from the Duck (Anas platyrhynchos) During the Period of Adaptation to Hypertonic Saline*
Authors: Holmes W. N. , Stewart D. J. 
Published: April 2021

ABSTRACT
After transfer of the freshwater-maintained ducks to a hypertonic saline regimen the wet weight, the protein content and the RNA content of the nasal glands showed a two-fold increase. The RNA content of the nasal glands was maximal after approximately 24 hr. whereas the maximum wet weight and protein content did not occur until after approximately 14 days of exposure to hypertonic saline. The DNA content of the nasal glands increased by approximately 42% during the period of adaptation to hypertonic saline and at the same time the weight of gland per unit DNA increased by about 58%. The wet weights, nucleic acid concentrations and the protein concentrations of Harderian glands, liver, kidney and adrenal glands did not change upon adaptation of the ducks to the hypertonic saline regimen for 14 days. Upon return of the birds to the freshwater diet, the weight, protein content and RNA content of the nasal gland declined. No loss of DNA was apparent. The weight of the gland per unit DNA and the protein content per unit DNA and the total RNA content of the nasal glands all returned to the level observed in the freshwater-adapted birds. When the birds were again transferred to the hypertonic saline diet the nasal glands returned to the state of development previously observed when the birds were maintained on the hypertonic saline regimen. The significance of these data in relation to the changes known to occur in the active sodium-transporting properties of the nasal gland are discussed.
A Method of Estimating the Relative Volumes of Water Flowing Over the Different Gills of A Freshwater Fish
Authors: Paling J. E. 
Published: April 2021

ABSTRACTA technique is described which uses marker parasites to estimate the relative volumes of water flowing over the different gills of a freshwater fish. It was found that in brown trout from Windermere most of the respiratory current flows over the second and third pairs of gills, less flows over the first pair on each side and least of all across the most posterior pairs of gill. Similarly, the median pair of gill slits carries more of the respiratory current than any of the other slits whereas first and fifth pairs of gill slits together carry only about one-sixth of the total water flow. Hatchery-bred brown trout showed a slight but significant difference in pattern of water movement over their gills following vigorous exercise. Possible reasons for this are discussed.
Analysis of the Distribution of Sodium, Potassium and Osmotic Pressure in the Urine of Crayfishes
Authors: Riegel J. A. 
Published: April 2021

ABSTRACT
Osmotic pressures of urine removed from the crayfish antennal gland have been re-measured. The results fail to confirm those obtained earlier which indicated a marked fall in the distal portion of the antennal gland. The possible reasons for this discrepancy are discussed. No significant fraction of the sodium in the urine is localized within the formed bodies found there. Potassium is localized within the formed bodies, but the relative amount cannot be ascertained. There is an inverse relationship between sodium and potassium concentrations in the tubular (distal) portions of the antennal gland. No such relationship exists in the coelomosac and labyrinth (proximal) portions of the gland.
Inherent Asymmetry and Reflex Modulation of the Locust Flight Motor Pattern
Authors: Wilson Donald M. 
Published: April 2021

ABSTRACT
In this paper I will present new data and ideas on two interrelated questions regarding the nervous control of insect flight. The answers to these two questions may be important for understanding other aspects of insect behaviour as well. The two problems are: (1) How perfect is the motor score which is built into the thoracic ganglia? (2) How is this motor score modified when anatomical damage makes the inherent score inappropriate? In addition to providing partial answers to these questions the results show that the phenomenon of adaptation of locomotory patterns to limb loss, called Plasticität by Bethe (1930), does not imply that locomotion is coordinated purely by proprioceptive reflexes. Although Bethe did not hold this view, later authors have often interpreted his work in this sense. They show also that two categories of possible central organization of locomotory behaviour, motor scores or sensory templates (the ‘motor tapes’ and ‘sensory tapes’ of Hoyle, 1964), are not mutually exclusive.
Dishabituation and Arousal in the Response of Single Nerve Cells in an Insect Brain
Authors: Fraser Rowell C. H. , Horn G. 
Published: April 2021

ABSTRACT
The background activity of neurones in the tritocerebrum of the locust responding to objects moved in the contralateral visual field can be influenced, possibly trans-synaptically, by electrical stimulation of the contralateral neck connective. These changes in background activity are always excitatory and may outlast the period of stimulation by several minutes. The effect of stimulating the ipsilateral cord on the discharge is weak or non-existent. If the contralateral connective is shocked when the response to a moving disk has waned, the recorded cell responds to the disk again. The response continues at a high level for many presentations following stimulation of the connective. Such dishabituation does not follow stimulation of the ipsilateral neck connective. Dishabituation sometimes occurs ‘spontaneously’ and cannot be accounted for as a recovery following a lapse of time. Some units show diurnal variations in their responsiveness to visual stimulation.
Effect of Drugs On Luminescence in Larval Fireflies
Authors: Carlson Albert D. 
Published: April 2021

ABSTRACT
Synephrine and other related monophenolic drugs were tested for potency of luminescence induction in the extirpated lantern of larval fireflies. Synephrine was found to be the most potent drug so far tested, with a threshold concentration of 10−6 M. Immersion of glowing lanterns in a solution containing 10−8 M synephrine and 10−8m-KCN resulted in rapid extinction of luminescence. Luminescence extinction times in KCN were found to be proportional to synephrine concentration and suggest that only a small ATP pool exists in the lantern. It is hypothesized that synephrine must stimulate ATP production in order to maintain high luminescence intensities. The vertebrate adrenergic blocking agent, dichloroisoproterenol (D.C.I.), was found to slowly induce luminescence which eventually declined to extinction. Synephrine was ineffective in luminescence induction after the declining phase of D.C.I. action began. A close analogue of D.C.I., isoproterenol, acted in a weak but similar manner to synephrine. It is suggested that D.C.I. prevents synephrine action by blocking the photocyte receptor sites.
Ionic Composition of Haemolymph and Nervous Function in the Cockroach, Periplaneta Americana L
Authors: Pichon Y. , Boistel J. 
Published: April 2021

ABSTRACT
Resting and action potentials have been recorded in giant axons of the cockroach when the intact nerve cord was bathed in the insect’s own haemolymph. Low resting potentials (43·0 + 4·8 mV.) and large action potentials (105·1 + 6·8 mV.) were obtained in these preparations as compared with those recorded in de-sheathed nerve cords. Recordings of the maximum rates of rise and fall have shown that the shape of the action potential was essentially similar in de-sheathed preparations and in intact nerve cords. These results have been discussed in terms of the unequal distribution of ions between the haemolymph, the extracellular fluid and the axoplasm of the giant axons. The low measured resting potential agrees with a K+ concentration in the haemolymph of about 20 mM./l., a value which is only slightly lower than the measured one (Pichon, 1963). The occurrence of large action potentials in these apparently depolarized axons may be related to the stabilizing action of divalent cations such as Ca2+ which are contained in the extracellular fluid in relatively large amounts. The very large recorded overshoots (62·1 ±7·0 mV.) may be linked with a low sodium concentration in the axoplasm and a high sodium concentration in the extracellular fluid of the giant axons of intact nerve cords, thus resulting in a high sodium equilibrium potential, ENa.
The Action of Iontophoretically Applied Glutamate On Insect Muscle Fibres
Authors: Beránek R. , Miller P. L. 
Published: April 2021

ABSTRACT
Electrophoretic application of L-glutamate from glass capillary micro-pipettes was used to investigate the ‘spot sensitivity’ of the membrane of coxal adductor muscle fibres from adult specimens of Schistocercagregaria Forskål and Locusta migratoria (L.). Circumscribed spots could be detected on the fibre surface where brief applications of L-glutamate produced transient depolarizations (glutamate potentials). Extracellular recording of excitatory junction potentials revealed that focal points of glutamate sensitivity are closely related to, and probably identical with, neuromuscular junctions. Large doses readily de-sensitized the membrane to L-glutamate for periods greatly exceeding the duration of the glutamate potentials. In chronically denervated muscles peaks of sensitivity could still be detected. Spots sensitive to L-glutamate were not depolarized by D-glutamate. The equilibrium point for glutamate potentials coincides with the equilibrium point of miniature excitatory potentials and lies between –10 and –25 mV.
The Action of the Eyecup Muscles of the Crab, Carcinus, During Optokinetic Movements
Authors: Burrows M. , Horridge G. A. 
Published: April 2021

ABSTRACT
The actions of the nine eyecup muscles of the crab during horizontal optokinetic movements are described. Each muscle includes a wide spectrum of fibre types, ranging from phasic, with sarcomere lengths of 3–4 μm., through intermediate, to tonic fibres with sarcomeres of 10–12 μm. Each muscle receives at least one slow and one fast motoneuron, but no inhibitory supply. The slow axons predominantly innervate the tonic muscle fibres while the fast axons innervate the phasic ones. Slow movement and the position of the eyecup in space are controlled by the frequency of slow motoneuron discharges. All muscles collaborate at every position. The phasic system is recruited during rapid eyecup movements of large amplitude. In optokinetic nystagmus the exact form of the impulse sequences are described for each muscle. They are the consequence of a visually driven central programme which takes no account of the movement which it generates. Movements in opposite directions involve different central programmes; the one is not merely the reverse of the other. There is no effective proprioceptive feedback from the eyecup joint or from muscle tension receptors.
Efferent Copy and Voluntary Eyecup Movement in the Crab, Carcinus
Authors: Horridge G. A. , Burrows M. 
Published: April 2021

ABSTRACT
Use is made of the fact that a freely moving blind eyecup is driven by movement perceived by the opposite seeing eye when the crab is in an optomotor drum. Forced extension of the seeing eyecup causes movement of the other blinded eyecup in the opposite direction, because it is driven by the perceived relative motion. Voluntary extension of the seeing eyecup causes no movement of the other blinded eyecup, although simultaneous oscillation of a striped drum round the crab is seen perfectly. Preventing voluntary extension of the seeing eyecup with a mechanical stop causes no movement of the other, blinded, eyecup. With both eyes blinded, or with the crab in the dark, voluntary or forced movement of one eyecup causes no movement of the other. This behaviour is that expected of an animal which can retract and extend either eyecup in the light or in the dark without disturbing the other, but no simple model is compatible with all the experiments."
Electrophysiological Studies On Initiation and Reversal of the Heart Beat in Ciona Intestinalis*
Authors: Anderson Margaret 
Published: April 2021

ABSTRACT
Electrophysiological techniques have been used to define pacemaker characteristics and organization in the heart of the tunicate Ciona intestinalis. The frequency of spontaneous beat initiation was regular or irregular for a given period of time; in any single heart, these frequency modes intermittently changed from one to the other in no regular order. Reversals could take place immediately, after a pause, or after collisions. Trains of electrical stimuli applied to the ends of the heart could drive propagated contractions at a frequency of up to 2·6/sec., and dominance could be controlled by altering the frequency and/or intensity of the stimuli. Each end gave a characteristic response to increasing frequency of driving, and the threshold for one-to-one driving was frequency-dependent. When the middle of a heart was ligatured, the two ends were independently active. Visceral ends exhibited regularly varying levels of high and low frequency with a period of several minutes, whereas the frequency levels of the hypobranchial ends varied irregularly. Intracellular resting potentials were approximately –50 mV., and propagated action potentials associated with contractile events did not show ‘overshoot.’ Partial electrical responses were affiliated with weak or failing mechanical events, and complex, double-peaked intracellular potentials were often associated with collisions. In some cases a cell could show electrical activity that was completely dissociated from the mechanical response of the whole heart. Excitation thus probably spreads passively between cells, and multiple foci of activity may co-exist at any given time. From electrophysiological and anatomical data, an hypothesis is proposed to explain the observed mechanical activity on the basis of the interactions of individual cells and higher-order interactions among groups of cells.
Reversal of A Visual Preference in Octopus After Removal of the Vertical Lobe
Authors: Young J. Z. 
Published: April 2021

ABSTRACT
Normal octopuses tend to attack a black disk more often than a white one, when they are shown against a white background. The difference is not present with a grey background. After removal of the vertical lobe the preference is reversed and attacks are now more frequent at a white than at a black figure, when on a white ground.
Tarsal Receptors and Leg Reflexes in the Locust and Grasshopper
Authors: Runion H. I. , Usherwood P. N. R. 
Published: April 2021

ABSTRACT
The physiological properties of hair sensilla found on the metathoracic tarsal segments of the locust and grasshopper are described. The sensilla trichodea are phasically responsive mechanoreceptors. The discharge frequency of these receptors is proportional to the velocity of displacement of the sensory appendage. Phase-related responses are obtained with sinusoidal inputs less than 100 Hz. With higher input frequencies the receptors respond asynchronously. The tarsal sensilla signal contact of the tarsal segments with the substratum and changes in the load on the metathoracic leg. Reflexes involving these tarsal receptors and the ‘fast’ and ‘slow’ excitatory and inhibitory neurones which innervate the metathoracic extensor tibiae muscle have been demonstrated and appear to play a significant role during postural and walking activity.
Desiccation Survival of the Infective Larva of Haemonchus Contortus
Authors: Ellenby C. 
Published: April 2021

ABSTRACT
The ensheathed larva of Haemonchus contortus is far better at surviving desiccation than the exsheathed form. Using interference microscopy, it is shown that, although the sheath is freely permeable to water, the ensheathed larva loses water much more slowly than the exsheathed larva. Close inspection of partially dry ensheathed larvae shows that the sheath becomes dry first and that this slows the rate at which the larva it contains loses water. The results are discussed in relation to other examples among nematodes where desiccation survival appears to be associated with mechanisms to slow the rate of drying.
Oxygen Consumption and Gill Water Flow in the Dogfish Scyliorhinus Canicula L
Authors: Hughes G. M. , Umezawa Shun-Ichi 
Published: April 2021

ABSTRACT
Determinations of the standard oxygen consumption of the dogfish Scyliorhinus canicula, by several different methods, gave values in the range of 20-55 c.c./kg./hr. at 12° C. When the rate of water flow over the resting fish is increased, there is an increase in oxygen consumption, but no marked change in respiratory frequency at the flow rates studied. An increase of respiratory frequency took place when the of the inspired water was reduced. The ventilation volume of the dogfish was measured by collecting the water in chambers after it had passed over the gills. The resting ventilation volume was about 120 c.c./min./kg. at 12° C. The relationship between the flow across the gills and the imposed hydrostatic pressure gradient (Δp) showed a linear relationship. The fish was unable to continue pumping water across the gills against adverse gradients in excess of 0·7 cm. H2O. When the flow across the gills was relatively low, utilization of oxygen of at least 70% was observed, but with increasing flow rates this fell to between 40 and 50%.
The Effect of Loading the Respiratory Pumps on the Oxygen Consumption of Callionymus Lyra
Authors: Hughes G. M. , Knights B. 
Published: April 2021

ABSTRACT
A comparative study of the respiration of fishes from different ecological niches has shown that certain species are suited for the study of particular aspects of respiratory function because of their structure and physiological adaptations. In this context the study of the generally less active bottom-living forms has advantages where movements of the fish must be limited by the experimental arrangement. In the case of the dragonet, Callionymus lyra, there is the added advantage that water issuing from the opercular cavities can be readily collected into tubes fixed round the external openings without impairing the action of the opercular valves. These preparations proved of great value in making direct measurements of the ventilation volume under varying conditions (Hughes & Umezawa, 1968a). The relationship between ventilation volume and muscular activity was also studied very conveniently in this species (Hughes & Ballintijn, 1968).
The Hydraulic System of Urechis Caupo Fisher & Macginitie
Authors: Chapman G. 
Published: April 2021

ABSTRACT
The hydrostatic pressures recorded in the coelom of Urechis during peristalsis, irrigation, burrowing and hind-gut ventilation have been recorded continuously. The main muscular activities except burrowing take place at pressures of a few centimetres of water and, it is suggested, are mainly carried out by the outer circular muscle layer. The high pressures involved in burrowing demand the recruitment of the whole muscle system. The hind-gut ventilation stops when internal pressure is raised, although changes in the contained volume of the body wall do not appear to provide information leading to the maintenance of a fixed volume. Instead this control is probably excercised by the hind gut. An attempt is made to calculate the energy requirements of irrigation and ventilation and it is shown that these are small compared with the respiratory rate, indicating that the movement of large volumes of water for feeding purposes is not an extravagant way of obtaining food in terms of energy expenditure.