bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permeability of the Abdominal Nerve Cord of the American Cockroach, Periplaneta Americana L. to Quaternary Ammonium Salts
Authors: Eldefrawi M. E. , O’Brien R. D. 
Published: April 2021

ABSTRACT
The influx and efflux of two series of quaternary alkylammonium cations in the abdominal nerve cord of the American cockroach have been studied. The data are interpreted as showing that increasing liposolubility tends to increase penetration, and increasing size (with respect to the smallest cross-sectional area) decreases it. The influx rates of the quaternary alkylammonium cations into the cockroach central nervous system (C.N.S.) is 2-7 times lower than Na+ when equimolar concentrations are compared. Acetylcholine penetrates into the C.N.S. rapidly due to its metabolism, since in the presence of eserine its influx rate becomes similar to that of the analogous alkylammonium cation which is unmetabolized. The alkylammonium cations that penetrate into the C.N.S. appear to be distributed into fast and slow pools, as judged by their relative rates of efflux. These may represent the distribution of cations between extracellular and intracellular spaces or possibly free and bound cations in the extracellular spaces. Although the alkylammonium cations penetrate the C.N.S., they apparently encounter a regulatory system that discriminates against large size, positive charge and polarity. This research project was financed in part by NIH Grant GM 07804-06.
Studies on the Effects of the Removal of the Frontal Ganglion in Locusta Migratoria L
Authors: Clarke Kenneth U. , Gillott Cedric 
Published: April 2021

ABSTRACT
Studies were made on the third, fourth-, and fifth-instar nymphs of Locusta migratoria L. from which the frontal ganglion had been removed, on controloperated animals, and on starved animals. The effects of this operation on protein metabolism were observed by study of: electrophoresis of haemolymph proteins, chromatography of haemolymph amino acids, production of protease in the midgut, and the incorporation of 14C-glycine into protein by the body cells. The total protein concentration in the haemolymph of operated locusts did not increase with time as did that of the controls, in which the increase was almost entirely due to changes in the second of the three bands which normally separate out. The concentration of the free amino acids in the haemolymph fell to about 70% of that found in the operated controls. In operated locusts the proportions of the amino acids relative to one another changed. The incorporation of 14C-glycine into protein was slower and the equilibrium concentration less in operated as compared with control-operated animals. The time taken to reach equilibrium was the same in both cases. In both operated and control-operated animals the protease activity of the midgut wall was very low; no difference could be detected between them. The protease activity of the mid-gut contents expressed per mid-gut was lower in operated than in control-operated animals. The protease activity expressed per mg. was found to be the same in operated, control-operated and starved animals. The hypothesis that the effects of the removal of the frontal ganglion were mediated through changes in the secretion of hormones from the corpus cardiacum was tested by giving daily injections of freshly prepared corpus cardiacum extract to locusts from which the frontal ganglion had been removed, and observing the growth in weight of these animals. A permanent increase in weight amounting to 100% of their initial weight was found. Animals injected with distilled water showed a temporary increase amounting to 30% of their initial weight. Uninjected animals maintained approximately constant weight.
Giant Neurons and Axon Pathways in the Brain of Tritonia
Authors: Dorsett D. A. 
Published: April 2021

ABSTRACT
The anatomy and histology of the brain of Tritonia hombergii are described. The brain contains giant neurons which are regularly found in the same positions: cerebral ganglia, one in each; pleural, nine; pedal, eight; buccal, two. The two cerebral giant neurons show spontaneous activity which is inhibited by stimulation of the cerebral nerves. The two largest cells in the pleural ganglia are not spontaneously active but have orthodromic excitatory connexions with axons in the pleural nerves. The branching of the axons of the giant cells has been followed using electrophysiological methods. The axons of a particular giant cell are distributed in a symmetrical fashion to nerves arising on both sides of the brain. This pattern of distribution is similar to that of the corresponding cell in the opposite half of the brain.
The Penetration of Acetylcholine into the Central Nervous System of the Cockroach Periplaneta Americana L
Authors: Lord K. A. , Gregory G. E. , Burt P. E. 
Published: April 2021

ABSTRACT
The hydrolysis of acetylcholine and acetylthiocholine by cockroach ventral nerve cords was examined by biochemical and histochemical methods, and used as an indication of the penetration of the substrates into the nerve cord. The rate of penetration of acetylcholine into intact nerve cords, measured biochemically, agrees well with estimates by Treherne & Smith (1965b) using a more direct method. A barrier to the penetration of the two cholinesterase substrates is destroyed by treatment with acetone, which increased the rate of hydrolysis of acetylcholine five- to tenfold. Histochemical tests showed that acetylthiocholine is probably prevented from penetrating freely to the neuropile of the ganglia by the glial cell layer. When the restriction is abolished by treating the cord with acetone, acetylthiocholine reaches the neuropile but penetrates it for only a short distance, probably because it is decomposed by the cholinesterase in this region.
Osmoregulation in the Diamondback Terrapin, Malaclemys Terrapin Centrata
Authors: Bentley P. J. , Bretz W. L. , Schmidt-Nielsen Knut 
Published: April 2021

ABSTRACT
While in hypertonic environment diamondback terrapins (Malaclemys centrata) slowly lose water by osmosis through the integument and as urine through the kidney. Small amounts of sodium are gained, probably largely as a result of diffusion through the integument rather than by drinking, and this sodium is principally excreted extrarenally. Nevertheless, the solute concentration in the blood of such turtles increases. When returned to fresh water the animals rehydrate and excrete accumulated excess sodium. In these ways they could undoubtedly survive for extended periods in the absence of fresh water, but it is not clear whether they could do so indefinitely.
The Respiration of Pteroides Griseum (Bohadsch) a Pennatulid Coelenterate
Authors: Brafield A. E. , Chapman G. 
Published: April 2021

ABSTRACT
It has been shown that the oxygen consumptions of various anthozoans are generally comparable with those of other invertebrates if the dry weights rather than the wet weights are considered (Brafield & Chapman, 1965). We have also suggested that the endoderm is probably the major site of oxygen uptake in pennatulids, associated with water movements into and out of the enteron. Three main sources of evidence support this view. First, the enteric water has a low oxygen concentration. Secondly, a fully contracted specimen consumes oxygen at a low rate, possibly due to a severely limited enteric circulation. Thirdly, measurements of the oxygen concentration of the water around a specimen in a closed vessel are sometimes inconsistent. Such variations might well be partly due to fairly regular movements of water in and out of the enteron, the inconsistent estimations having been made either just before or after an efflux of relatively deoxygenated enteric water. This source of inaccuracy in measuring consumptions can be avoided only if the oxygen concentration is measured continuously. Consequently experiments have been conducted in which a continuous-flow respirometer was used in an attempt to demonstrate whether a rhythmic enteric irrigation does occur in pennatulids; for if it does, and water which has become partly deoxygenated by oxygen uptake through the endoderm is periodically expelled from the enteron, a continuous record of the oxygen concentration of water which has been flowing slowly past the animal should show a rhythmic rise and fall. Pteroides griseum was used in these experiments because this species has a spacious enteron, and because a good supply of large specimens was available.
Respiratory Function in the South American Lungfish, Lepidosiren Paradoxa (Fitz)*
Authors: Johansen Kjell , Lenfant Claude 
Published: April 2021

ABSTRACT
Few animal species have aroused as much excitement upon their discovery as the South American lungfish. Its possession of distinct piscine as well as amphibian characters made the animal a link in the transition of vertebrate life from water breathing to air breathing. Its special attributes are clearly reflected in its name, Lepidosiren paradoxa.
Active Transport of Potassium and Oxygen Consumption in the Isolated Midgut of Hyalophora Cecropia
Authors: Harvey W. R. , Haskell J. A. , Zerahn K. 
Published: April 2021

ABSTRACT
Flux measurements with 42K reveal that in the isolated midgut of Hyalophora cecropia 90 to 100 % of the short-circuit current is carried by the active transport of potassium from the blood-side to the lumen. When K-transport is strongly depressed, either by withholding potassium from the blood side or by imposing a large positive potential on the lumen, the oxygen uptake of the isolated gut remains virtually unchanged. If the K-transport were to be energized by the negligible increase in oxygen uptake about 40 μ-equiv. of potassium would have to be transported for every μ-equiv. of extra oxygen taken up. This ratio of K-transport to oxygen uptake is thermodynamically impossible. The ratio of potassium transported to total oxygen consumed when the midgut is bathed with 32 mM potassium on both sides is about 1·3 at temperatures of 25° and 15° C. The ratio must be smaller at lower potassium concentrations and is 2·0 at 73·5 mM-K, which may be approaching the maximum value. Although the oxygen uptake is independent of the K-transport, the reverse is not true. There is a close dependency of K-transport on oxygen consumption. K-transport by the midgut contrasts with Na-transport by the frog skin because Na-transport stimulates oxidative metabolism whereas K-transport does not. Evidently the coupling of transport to energy supply is different in the two systems.
Changes in Blood Pressure, Heart Rate and Breathing Rate During Moderate Swimming Activity in Rainbow Trout
Authors: Stevens E. Don , Randall D. J. 
Published: April 2021

ABSTRACT
Changes in blood pressure in the dorsal aorta, ventral aorta and subintestinal vein, as well as changes in heart rate and breathing rate during moderate swimming activity in the rainbow trout are reported. Blood pressures both afferent and efferent to the gills increased during swimming and then returned to normal levels within 30 min. after exercise. Venous blood pressure was characterized by periodic increases during swimming. The pressure changes were not in phase with the body movements. Although total venous return to the heart increased during swimming, a decreased blood flow was recorded in the subintestinal vein. Heart rate and breathing rate increased during swimming and then decreased when swimming ceased. Some possible mechanisms regulating heart and breathing rates are discussed.
Changes of Gas Concentrations in Blood and Water During Moderate Swimming Activity in Rainbow Trout
Authors: Stevens E. Don , Randall D. J. 
Published: April 2021

ABSTRACT
Changes in partial pressures of O2 and CO2 in blood and water afferent and efferent to the gills are reported. These variables were measured before, during and after moderate swimming activity in rainbow trout. Neither blood nor water , afferent or efferent to the gills, changed markedly before, during or after exercise. Arterial blood was always more than 95 % saturated with oxygen. Venous blood was 38% saturated, falling to a minimum of 28% during exercise. of arterial blood was 2-3 mm. Hg. of venous blood increased from 5·7 to 8·0 mm. Hg during exercise and remained elevated throughout the recovery period. Cardiac output (calculated using the Fick principle) stroke volume, ventilation volume and the volume of water pumped per breath all increase by a factor of between 4 and 5 during exercise. All tended to remain elevated for between 10 and 30 min. after exercise and then gradually decrease to pre-exercise levels.
Lactic and Succinic Acids as Excretory Products of Polymorphus Minutus (Acanthocephala) in Vitro
Authors: Crompton D. W. T. , Ward P. F. V. 
Published: April 2021

ABSTRACT
The acanthocephalan parasite, Polymorphus minutus, has been found to excrete radioactive lactic and succinic acid, and a small amount of radioactive, volatile material, when incubated with [U-14C]-glucose under conditions designed to simulate those in vivo. The acids were identified by paper and gas chromatography, and the identity of succinic acid was confirmed with an enzyme preparation.
Flight in Drosophila
Authors: Vogel Steven 
Published: April 2021

ABSTRACT
The variation of the lift and drag of fruit-fly wings with angle of attack and velocity was compared with that of thin plates. High drag and low ratios of lift to drag characterized these airfoils, the primary difference being the absence of stalling in the fly wings. Flow photographs and determinations of stall point on thin plates suggested that the fly wing behaves as if encountering a Reynolds number below the actual value. At positive angles of attack camber improved the aerodynamic characteristics of fly wings; at negative angles uncambered wings were superior. The structural basis for the performance of fly wings and the relationship of their characteristics to their opening conditions are discussed.
Excitation and Inhibition of the Reflex Eye Withdrawal of The Crab Carcinus
Authors: Sandeman D. C. 
Published: April 2021

ABSTRACT
Damage to the statocysts or section of the oesophageal connectives of Carcinus causes repeated ‘spontaneous’ eye withdrawals or ‘blinking’ on the damaged side. When the eyes and brain are isolated from the body, repetitive blinking persists and concomitant bursts of large impulses appear in a single motor axon in the optic tract. The length of these bursts varies from 80 to 180 impulses and the interburst intervals from 5 to 60 sec. There is no obvious correlation between burst length and interburst interval. The bursts are inhibited by stimulating the inside half of the ipsilateral oesophageal connective or initiated by stimulation of the oculomotor and tegumentary nerves. If stimulated with a continuous train of pulses these pathways also cause an increase or decrease in the interburst intervals. The actively spiking portion of the eye-withdrawal motor neuron extends into the brain at least as far as the tegumentary/antennary neuropile. Here it is particularly sensitive to cathodal stimulation, yielding trains of spikes to maintained d.c. stimulation. This point is considered to be near the spike initiating locus for the bursts.
Non-Dependence of the Saturation of Depot Fat on Temperature and Photoperiod in a Hibernating Mosquito
Authors: Van Handel Emile 
Published: April 2021

ABSTRACT
The opinion that fat cells can sense and respond to temperature so as to provide a triglyceride mixture with a melting point just below the environmental temperature (Lands, 1965) is widely held. This view disregards the fact that the body fat of most marine animals, including homeotherms, is highly unsaturated and has melting points much below environmental temperatures, whereas the final melting point of beef tallow and lard may be considerably above body temperature. In the bat, brown adipose tissue fat is less saturated in the summer than during hibernation (Wells, Makita, Wells & Krutzsch, 1965). In hamsters, body fat becomes less saturated after cold exposure, but this effect may be only indirectly due to temperature, because the same effect results from semi-starvation or cortisone treatment at normal temperature (Kodama & Pace, 1963). Furthermore, the fatty acid composition of the diet may greatly affect the body-fat composition and influence the results obtained by variation of temperature.
Some Responses to Light in a Specimen of Pelagohydra Mirabilis Dendy, 1902 (Coelenterata: Hydrozoa)
Authors: Pilgrim R. L. C. 
Published: April 2021

ABSTRACT
A single specimen of P. mirabilis was subjected to varying degrees of illumination. In constant light occasional spontaneous reactions occurred, the tentacles flexing in an oral direction and moving the animal aborally a very insignificant distance each time. When the level of illumination was reduced suddenly and almost completely there occurred a sequence of such reactions; successive reactions in the sequence occurred with increasing vigour and at diminishing frequency. Readmission of light was shown to act as an inhibitory condition, since it interrupted the reaction sequence. When the illumination was reduced in a series of steps, each step was followed by a sequence of reactions, the sequences showing increase in vigour and decrease in frequency. Each such sequence appeared to be freshly initiated by the stepwise reduction in light.
The Sodium Balance Mechanism in the Fresh-Water Amphipod, Gammarus Lagustris Sars
Authors: Sutcliffe D. W. , Shaw J. 
Published: April 2021

ABSTRACT
The sodium balance mechanism of Gammarus lacustris in fresh water is virtually identical with that found in G. pulex. The sodium transporting system at the body surface has a very high affinity for sodium ions. The system is half-saturated at an external concentration of about 0·14 mM/1. and fully saturated at about 1 mM/1. sodium. The lowest external concentration at which sodium balance was maintained was 0·06 mM/1. Both the total sodium loss rate and the sodium influx rate remained approximately constant in animals acclimatized to the range of external concentrations from 2 to 0·3 mM/1. NaCl. At lower concentrations the loss rate was reduced and the influx increased by a factor of about 1·5. Changes in the sodium influx and loss rates are very closely linked together, and it is shown how these changes are related to the external sodium concentration.
Iodine Accumulation in a Nemertine, Lineus Ruber
Authors: Balfour W. E. , Willmer E. N. 
Published: April 2021

ABSTRACT
Studies with radioactive tracers show that the nemertine Lineus ruber actively accumulates iodide in its pharynx, and stores it mostly as iodide. When the sodium chloride concentration of the ambient sea water is raised, the amount of iodide accumulated is increased, and traces of a ‘thyronine’ can be detected. When the osmotic pressure was raised with sucrose (instead of NaCl) there was no increased uptake of iodine.
Hyperphagia in the Blowfly*
Authors: Dethier V. G. , Gelperin A. 
Published: April 2021

ABSTRACT
The current view of the control feeding in the blowfly Phormia regina Meigen holds that ingestion is initiated by stimulation of oral taste receptors and ultimately terminated by signals from the foregut (Dethier & Bodenstein, 1958). The signals from the foregut originate in stretch receptors which monitor the passage of food from the crop to the mid-gut (Gelperin, 1966b). The recurrent nerve conveys these signals to the brain where they counteract input from peripheral taste receptors. Transection of the recurrent nerve interferes with this inhibitory feed-back system and causes a fly to become hyperphagic (Dethier & Bodenstein, 1958).
Regulation of Heat Production by Large Moths
Authors: Heath James Edward , Adams Phillip A. 
Published: April 2021

ABSTRACT
Moths ‘warm-up’ prior to flight at mean rates of 4·06° C./min. in Celerio lineata and 2·5° C./min. in Rothschildia jacobae. The abdominal temperature rises only 2−3° C. during activity. Oxygen consumption of torpid sphinx moths increases by a factor of 2·27 as temperature changes from 26° to 36° C. Oxygen consumption during ‘warm-up’ increases with duration of ‘warm-up’ from about 1000μl./g. min during the initial 30 sec. to nearly 1600μl./g. min. during the 3rd min. This increase compensates for increasing heat loss from the thorax during ‘warm-up’. When the moths are regulating thoracic temperature, oxygen consumption increases with decreasing air temperature from a mean of about 400 μl./g. min at 31° C. to about 650 μl./g. min. at 26° C Values of O2 consumption calculated from the cooling curve of C. lineata are about 85 % of the measured values of O2 consumption. The giant silk moth, Rothschildia jacobae, regulates thoracic temperature during activity between about 32° and 36°C. at ambient temperature from 17°to 29° C. Moths kept at high temperatures are active longer, have more periods of activity and expend more energy for thermoregulation than moths kept at low temperatures. Large moths increase metabolism during active periods to offset heat loss and thereby maintain a relatively constant internal temperature. In this regard they may be considered endothermic, like birds and mammals. We estimate that male moths use 10% of their stored fat for thermoregulation, while females may use 50 %.
The Effect of Some Anions and Cations Upon the Fluxes and Net Uptake of Chloride in the Larva of Aedes Aegypti (L.), and the Nature of the Uptake Mechanisms for Sodium and Chloride
Authors: Stobbart R. H. 
Published: April 2021

ABSTRACT
The anal papillae of the aquatic larva of Aëdes aegypti are responsible for 90 % of the steady-state exchange of chloride. The relationships between chloride flux and external chloride concentration are approximately described by the Michaelis equation. There is net uptake of chloride, independent of uptake of sodium, from KC1, CaCl2 and NH4C1, probably in exchange for OH’ or , but the rate is much slower than from NaCl. The following ions stimulate influx of chloride from 0·1 mM/1. KC1: H+ = Na+ &gt; K+. The following ions inhibit it: Movements of sodium and chloride ions are explicable in terms of an anionic and a cationic carrier located in an osmotic barrier in the papillae, the carriers being functionally coupled to sodium and chloride pumps located at the inner surface of the barrier. An attempt is made to relate these findings to recent electron microscopical studies of the papillae.
The Jump of the Flea: A Study of the Energetics and a Model of the Mechanism
Authors: Bennet-Clark H. C. , Lucey E. C. A. 
Published: April 2021

ABSTRACT
The energy requirement of a jump of 3·5 cm. height by the rabbit flea, Spilopsyllus cuniadi, is 2·25 ergs. This must be delivered in 0·75−1 ·o msec, over a distance of 0·37−0·5 mm., which is not compatible with direct muscular action. The anatomy of the jumping mechanism has been re-examined and its action studied by high-speed cinematography. The following explanation is offered. The main impulse comes from the depression of the metathoracic femur, whose depressor muscle originates on the notum. In the resting position the attachment of the depressor tendon to the femur is over-centre with respect to the trochanter-femoral joint. When the muscle contracts energy is stored in a resilin pad located between notum and pleuron. This energy is released by a second muscle which pulls the depressor tendon away from the over-centre position, thus enabling it to depress the femur. Operations on live fleas have provided evidence in support of the proposed mechanism. The depressor muscle is capable of providing 1-96 ergs on each side. The resilin pad is capable of storing 4 ergs on each side. Species which are better jumpers have larger resilin pads.