bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Osmotic Relations Between White and Yolk in the Hen’s Egg
Authors: Bateman J. B. 
Published: April 2021

ABSTRACT
The osmotic relations between white and yolk in the fertilised and unfertilised hen’s egg have often been investigated. The complexity of these relations is presumably due largely to peculiar physico-chemical properties of the colloid constituents of the egg. The purpose of this paper is primarily to confirm the existence of a considerable osmotic difference between white and yolk in the unfertilised hen’s egg, in reply to a recent denial, and then to describe some preliminary experiments on the state of water and of several dissolved substances in the egg. The bearing of these experiments on the relations between white and yolk in the intact egg will then be discussed briefly.
The Effect of Temperature on Haemolytic Systems Containing Propyl Alcohol
Authors: Gordon Albert S. 
Published: April 2021

ABSTRACT
The effect of temperature on haemolytic systems in which saponin and sodium taurocholate respectively were used as lysins has been described by Ponder and Yeager (1930 a). They have found that in these cases the Arrhenius equation cannot be applied, mainly because of the complexity of these apparently simple systems.
A Function of the Subelytral Chamber of Tenebrionid Beetles
Authors: Slobodchikoff C. N. , Wismann Kim 
Published: April 2021

ABSTRACT
The subelytral chamber is an air space between the elytra and the dorsum of the abdomen of some Tenebrionid beetles. Postulated functions for the subelytral chamber have been a reduction of transpiratory water loss and a thermal buffer for heat flow from the elytra to the abdomen. We show that there is a significant correlation between water loss and the depth of the subelytral chamber. This implies that the chamber may be a structure that permits the rapid expansion of the abdomen, providing the beetles with a mechanism by which they can quickly drink large quantities of water from an ephemeral source such as a rain puddle. As the beetles drink, the abdomen greatly expands, and the chamber shrinks.
The Activity and Characteristics of the Ca2+ ATPase of Fish Gills in Relation to Environmental Calcium Concentrations
Authors: Shephard K. L. 
Published: April 2021

ABSTRACT
The concentration of plasma calcium and the activity of the gill Ca2+ - ATPase has been measured in roach from several waters. Plasma calcium concentrations in these fish vary very little (2·62 ± 0·17 him) despite great variation in the external calcium concentration between waters (0·40 to 2·92 mm). There is, however, a close correlation between Ca2+ ATPase activity and external calcium concentration, consistent with the view that differences in the requirement for calcium transport are accommodated by variation in the Ca2+ ATPase system.
These results are discussed in relation to those of a previous experiment, where the short term effects of changing external calcium were considered. It is suggested that variation in the absolute level of Ca2+ATPase activity represents the long term adaptation of the roach to different calcium concentrations.
Reversal of a Walking Leg Reflex Elicited by a Muscle Receptor
Authors: DiCaprio R. A. , Clarac F. 
Published: April 2021

ABSTRACT
Passive movement of the basal (thoracic-coxal) leg joint in the shore crab Carcinus maenas normally elicits a resistance reflex in the promotor and remotor motoneurones. Remotion of the joint excites promotor moto-neurones and promotion excites remotor motoneurones. This reflex behaviour may reverse and become an assistance reflex, where movement of the joint excites the motoneurones innervating the muscle which would assist the passive movement. This reversal of reflex activity appears to be dependent upon the central state of activity of the animal.
Proprioceptive Control of the Bilaterally Organized Rhythmic Activity of the Oesophageal Neuronal Network in the Cape Lobster Jasus Lalandii
Authors: Nagy F. , Moulins M. 
Published: April 2021

ABSTRACT
In the lobster Jasus lalandii the activity of the oesophageal nervous system (monitored through the firing of its main motor neuron, OD1) is modulated by a pair of proprioceptors, the posterior stomach receptors (PSRs). The in vitro preparation used consisted of the oesophageal nervous system, the suboesophageal ganglion and the two PSRs, which provide the only source of sensory input. Stimulation of a PSR activates only the oesophageal oscillator located in the ipsilateral commissural ganglion. When spike conduction is blocked in the ipsilateral connective, the stimulation of a PSR activates the contralateral oesophageal oscillator. Inputs from each PSR project to the different parts of the distributed oesophageal network (in the two commissural ganglia and the oesophageal ganglion), but at a given time only one of the PSRs’ projections is effective. The relative efficacy of the PSRs’ projections is controlled by the oesophageal motor network itself and requires that the superior oesophageal nerves be intact (sons). The PSRs’ inputs are integrated in the suboesophageal ganglion before reaching the oesophageal network. However, this premotor step is not involved in the control of the unilaterality of PSRs’ effects. The PSRs are stimulated by at least two different rhythmical muscular sequences of the foregut (the gastric mill sequence and the cardiac sac sequence) and provide a source of rhythmical inputs to the CNS. The oesophageal nervous system exhibits a periodically varying sensitivity to the PSRs’ inputs, which is illustrated by a phase-response curve. Each oesophageal oscillator can be entrained by the rhythmical PSRs’ inputs over a range of period. This range includes the period of the spontaneous gastric rhythm. It is proposed that the PSRs enable the oesophageal and the gastric mill rhythms to be coordinated through a peripheral loop. The participation of PSRs in the coordination of different motor sequences of the foregut is discussed.
Cyclic Adenosine Monophosphate Mediation of Peptide Neurohormone Effects on the Lobster Cardiac Ganglion
Authors: Lemos Jose R. , Berlind Allan 
Published: April 2021

ABSTRACT
Two cardioexcitors which can be extracted or released from crustacean neurohaemal structures, the pericardial organs, alter the endogenous bursting activity of isolated lobster cardiac ganglia in different ways. A small peptide increases the burst frequency of the ganglion, the duration of each burst, and the number of spikes per burst, while 5-hydroxytryptamine (5-HT) increases burst frequency, but decreases the burst duration and number of spikes per burst. Four lines of evidence are presented that cyclic adenosine monophosphate (cAMP) mediates the effects of peptide on the ganglion, but does not play a significant role in 5-HT action: (1) exogenous cAMP mimics the effects of peptide but not of 5-HT on burst parameters; (2) inhibition of the enzyme phosphodiesterase, which increases endogenous levels of cAMP, mimics the effects of peptide and potentiates peptide action but not that of 5-HT; (3) putative blockers of adenylate cyclase block the action of peptide but not of 5-HT; (4) peptide causes a large increase in cAMP content of the ganglion, while 5-HT application results in a much smaller increase.
Comparison of Potassium Transport in Three Structurally Distinct Regions of the Insect Midgut
Authors: Cioffi Moira , Harvey William R. 
Published: April 2021

ABSTRACT
Active potassium transport across the isolated midgut of the Tobacco Hornworm larva, Manduca sexta, was studied by measuring the short circuit current (Isc) and unidirectional 42-potassium fluxes. The midgut is composed of structurally distinct anterior, middle and posterior regions, all of which are shown to transport potassium, so that by comparing and contrasting their structural and functional properties new information on the mechanism of midgut potassium transport was obtained. It has previously been shown that the potassium pump is located on the apical membrane of the goblet cell. In the anterior and middle regions of the midgut the goblet cell has a large cavity and mitochondria are closely associated with the apical membrane while in the posterior midgut the goblet cavity is much smaller, and mitochondria are not associated with the apical membrane. However, the apical membrane particles which have been implicated in active potassium transport in a number of other insect epithelia are present in all three regions. This observation suggests that the particles are a structural requirement for active transport, and that close association between mitochondria and the transporting membrane is not essential. Comparison of the kinetic influx pool size and the differences in the Isc decay profiles between the three midgut regions suggest that part of the influx pool is a transported pool located in the goblet cavity. A new model to explain the driving force for potassium transport in the midgut is proposed, in which the rate of potassium transport controls the entrance of potassium into the cell, rather than the opposite, currently accepted view.
A Quantitative Model for the Adhesive Locomotion of The Terrestrial Slug, Ariolimax Columbianus
Authors: Denny Mark W. 
Published: April 2021

ABSTRACT
The foot of pulmonate gastropods adheres to the surface upon which the animal crawls, the adhesive being a thin layer of pedal mucus. The power for locomotion in these animals is provided by rhythmic muscular contractions (pedal waves) on the ventral surface of the foot, and the force due to these waves is coupled to the substratum by the pedal mucus. Movement of the animal is consequently a result of a balance of forces: if the reactive force provided by the adhesive beneath the stationary portions of the foot is sufficient to offset the frictional force caused by portions of the foot moving forward, the animal is able to crawl. Mechanisms previously proposed to explain this adhesive crawling require that the frictional resistance to forward movement be minimized by the foot being lifted during the passage of a pedal wave. This lifting, however, cannot be reconciled with the properties of the pedal mucus and epithelium, and the terrestrial slug, Ariolimax columbianus, is shown to not lift its foot when crawling. A new mechanism is proposed which does not require lifting of the foot and explains several difficulties inherent in previous studies. Based on this mechanism and the mechanical properties of pedal mucus, a quantitative model is constructed which predicts the frictional and reactive forces, and these predictions are tested against force measurements made under crawling slugs. The model accurately predicts the magnitude of forces under slugs crawling horizontally, but is less accurate in predicting forces under slugs crawling vertically.
The Mechanisms and Energetics of Honeybee Swarm Temperature Regulation
Authors: Heinrich Bernd 
Published: April 2021

ABSTRACT
Free (active) honeybee swarms regulated their core temperature (Tc) generally within 1 °C of 35 °C. They maintained the same temperature around freshly built honeycomb, and in the brood nest of the hive, from ambient temperatures of between at least 1 and 25 °C. Captive (inactive) swarms in the laboratory often allowed Tc to decline below 35 °C. The temperature of the swarm mantle (Tm) varied with the general activity of the swarm as well as with ambient temperature (TA), but in captive swarms (and sometimes at night in free swarms), Tm was generally held above 17 °C, even at TA&lt; 5 °C. Within the swarm, temperatures varied between 36 °C, an upper temperature set-point, and 17 °C, a lower temperature set-point. Before swarm take-off, all temperature gradients in the swarm were abolished and Tm equalled Tc. The regulated Tc and Tm were unrelated to size and passive cooling rates in swarms ranging from 1000 to 30000 bees. The weight-specific metabolic rate of swarms was correlated with TA and Tc, but relatively little affected by swarm size. Bees on the mantle experiencing low temperatures pushed inward, thus contracting the mantle, diminishing the mantle porosity, and filling interior passageways. As a result, their own rate of heat loss, as well as that from the swarm core, decreased. In large tightly clumped swarms, even at TA&lt; 5 °C, the resting metabolic rate of the bees in the swarm core was more than sufficient to maintain Tc at 35 °C or above. The active thermoregulatory metabolism was due to the bees on the swarm mantle. There was little physical exchange of bees between core and mantle at low (&lt; 5 °C) TA. In addition, there was no apparent chemical or acoustic communication between the bees in the swarm mantle that are subjected to the changes of the thermal environments and the bees in the swarm interior that constantly experience 35 °C regardless of TA. The data are summarized in a model of Tc control indicating a primary role of the mantle bees in controlling heat production and heat loss. The possible ecological significance of swarm temperature regulation is discussed.
Carbonic Anhydrase Activity During the Larval-Pupal Transformation of Hyalophora Cecropia Reared on Foliage and Synthetic Diet: Effects of Potassium and Chloride on Midgut, Fat Body and Integumentary Enzymes
Authors: Johnston James W. , Jungreis Arthur M. 
Published: April 2021

ABSTRACT
Carbonic anhydrase was measured in tissues of silkmoths, Hyalophora cecropia, reared on either a wheatgerm-based synthetic diet or wild cherry foliage in feeding fifth-instar larvae, throughout the larval-pupal transformation and in newly ecdysed pupae. Carbonic anhydrase activity was present in fat body, midgut and intgeumentary epithelial cells, but not in haemolymph, cuticle or the integumentary musculature. Approximately 70 % of the total carbonic anhydrase present per animal is localized within the epidermal cells of the integument. The midgut is without measurable carbonic anhydrase activity from the day of apolysis (through the newly ecdysed pupal stage in development) until after the larval-pupal ecdysis. In tissues analysed during the feeding fifth larval instar, 150 toward acetazolamide was between 10−8 and 10−7 M. With the exception of larval midgut, regardless of stage, tissue or diet, both potassium and chloride normally inhibit carbonic anhydrase, with the effects of potassium and chloride being additive. In larval midgut, chloride at concentrations of 50 or 150 mmstimulates carbonic anhydrase activity 30 or 100%, respectively. In foliage-reared insects, potassium enhances chloride stimulation of larval midgut carbonic anhydrase, whereas in synthetic-diet-reared insects, potassium antagonizes the stimulatory effects of chloride. Removal of a heat-stable, dialysable factor associated with the larval midgut of foliage-reared insects converts properties of the foliage midgut enzyme to those characteristic of the synthetic diet type, and vice versa.
A Study of In Vivo Glycine Absorption by Fed and Fasted Rainbow Trout (Salmo Gairdneri)
Authors: Bogé G. , Rigal A. , Pérès G. 
Published: April 2021

ABSTRACT
The effects of 4 and 8 weeks fasting at 16 °C were studied in rainbow trout, Salmo gairdneri Richardson. After 4 and 8 weeks, the wet weights of the intestine of fasted animals are respectively 64% and 69% lower than those of fed animals. These effects especially concern the mucosal tissue.
Glycine absorption (0·5 and 10 mm) was studied using an in vivo perfusion technique. After 4 weeks, the absolute amounts of 0·5 mm glycine absorbed by fasted and fed fish are similar. With 10 mm glycine, the absorption is slightly lower in fasted trout (–19%). After 8 weeks these differences are more marked, with glycine concentrations of 10 mm (– 42%). Results expressed per 100 g body weight showed that these differences result partly from a weight gain of fed trout. Absorption expressed in terms of weight of dry intestine is higher in 4 and 8 weeks fasted animals, principally for the lower amino acid concentration (+61% and +111%). Larger differences were apparent when the absorptions were expressed in terms of dry weight of mucosal tissue (+122% and +225%).
Duration Of Pupal Diapause in the Tobacco Hornworm is Determined By Number of Short Days Received By the Larva
Authors: Denlinger David L. , Bradfield James Y. 
Published: April 2021

ABSTRACT
Daylength monitored by the embryos and larvae of the tobacco hornworm, Manduca sexta, is used to program both the incidence and duration of pupal diapause. Short daylength throughout embryonic and larval development yields a high diapause incidence, but a diapause of short duration. Hornworms transferred from long-to short-day conditions at later stages of larval development enter diapause at a lower rate, but the resulting diapause is of greater duration. The number of short-day cycles the hornworms receive can be varied by partial starvation and the use of different rearing temperatures. Such manipulations consistently support a model in which diapause duration is inversely related to the number of short-day cycles received. Observations with field-reared hornworms are consistent with the model: September hornworms receive more short-day cycles than August hornworms and thus have a shorter diapause. This mechanism apparently functions in synchronizing the initiation of adult development among individuals that pupate at different times. The diapause duration is programmed by the brain and can readily be transferred to other pupae by brain transplantation.
The Fate of Glomerular Filtration Markers Injected into the Haemolymph of the Amphibious Crab Holthuisana Transversa
Authors: Greenaway Peter 
Published: April 2021

ABSTRACT
Three glomerular filtration markers injected into Holthuisana transversa disappeared from the haemolymph at very different rates. Polyethylene glycol 4000 disappeared at a rate ca. 5 times faster than Cr-EDTA and ca. 15 times faster than inulin. Inulin and Cr-EDTA were excreted by the crab but only 5 % of the injected PEG 4000 left the body. Inulin injected into the excretory organs was reabsorbed into the haemolymph. The reliability of commonly used glomerular filtration rate markers as indicators of filtration in decapods is discussed.
Measurements of the Intracellular Potassium Activity of Retzius Cells in the Leech Central Nervous System
Authors: Deitmer Joachim W. , Schlue Wolf R. 
Published: April 2021

ABSTRACT
The intracellular K activity of leech Retzius cells was measured using double-barrelled, liquid ion exchanger, microelectrodes. At the normal external K+ concentration of 4 mm (equivalent to 3 mm-K activity, assuming an activity coefficient of 0·75) the mean K activity was 101·3 ± 7·6 mm (S.D., n = 14) in the cell bodies, and 4·35 ± 0·4 mV (n = 27) in the extracellular spaces surrounding them, indicating a K+ equilibrium potential of – 80 mV. The mean membrane potential was –43·6±4·9 mV (n = 14). In a K-free external solution, or in the presence of 5×10−4 M-ouabain, the intracellular K activity decreased by up to 14 mm min−1. This indicates an efflux of K+ ions across the cell membrane of approximately 2 × 10−10 mol cm−2 s, and an apparent K+ permeability coefficient of 8 × 10−8 cms−1. The cell membrane depolarized upon removal of K+ and upon addition of ouabain, and transiently hyperpolarized beyond its initial level on return to the normal external K+ concentration. The recovery from this hyperpolarization paralleled the increase of the intracellular K activity following the re-addition of K+. Our results suggest that, despite the high K+ permeability of the Retzius cell membrane, the intracellular K activity is maintained at a high level by an electrogenic pump.
Voltage Clamp Studies on Insect Skeletal Muscle: II. The Outward Currents
Authors: Yamamoto Daisuke , Washio Hiroshi 
Published: April 2021

ABSTRACT
Two components of outward currents were investigated under voltage clamp conditions in Tenebrio muscle fibres. The instantaneous current-voltage relation for the transient outward current showed outward rectification. The tail currents for the delayed outward currents were made up of either one or two exponential components. The activation process for the delayed current was analysed using positive tails that decayed with a simple exponential time course. The delayed current was half-activated at about + 35 mV. Two rate constants for activation are both monotonic functions of membrane potential. The reversal potential for the delayed current was only partially dependent on the external K-concentration. The role of the two outward currents in the production of the action potential was discussed.
Electrically Evoked Course Control in the Fly Calliphora Erythrocephala
Authors: Blondeau Jean 
Published: April 2021

ABSTRACT
Neurones in the optic ganglia of free-moving and fixed Calliphora were electrically stimulated with extracellular microelectrodes. The maximum diameter of the stimulating focus was 20 μ m in the antero-posterior axis. Course control and landing manoeuvres could be elicited by stimulating in the lobula plate but not in the lobula or medulla. With stimulation in the vicinity of the H neurones, yaw responses were evoked. Direction of the response was dependent on stimulation polarity. This supports the hypothesis that H neurones mediate optomotor responses. Stimulation in the posterior part of the lobula plate, close to the V neurones, elicited pitch, lift and thrust responses as well as landing reactions.
Interneuronal Control of Feeding in the Pond Snail Lymnaea Stagnalis
Authors: Rose R. M. , Benjamin P. R. 
Published: April 2021

ABSTRACT
The Lymnaea buccal ganglion is organized such that the basic feeding rhythm is generated by an interneuronal network which imposes its activity on a set of follower cells. In this paper we extend our earlier observations (Benjamin & Rose, 1979) on the follower cells to show that they receive four consecutive synaptic inputs. The main objective of the paper is to describe the properties of an interneurone called the ‘slow oscillator’ which is capable of initiating feeding cycles. This interneurone will be used in the following paper (Rose & Benjamin, 1981) to drive other members of the interneuronal network in order to determine how it is organized, and to understand the origin and timing of the four synaptic inputs to the follower cells.
Crab Gill Intra-Epithelial Carbonic Anhydrase Plays a Major Role in Haemolymph CO2 and Chloride Ion Regulation
Authors: Burnett Louis E. , Woodson Paul B. J. , Rietow Martha G. , Vilicich Victoria C. 
Published: April 2021

ABSTRACT
The distribution and function of the enzyme carbonic anhydrase in the crab Pachygrapsus crassipes was investigated. Carbonic anhydrase was found in gill epithelial tissue but not in the haemolymph, muscle, heart, hepatopancreas or gonads of male crabs.
Enzyme activity was completely inhibited in vitro by 2 × 10 −4M sodium acetazolamide (Diamox). Radiolabelled Diamox (2 ×10−4M) in sea water was found to equilibrate with the intact crab’s haemolymph within one hour.
Haemolymph CO2 content, pH and chloride ion concentration were measured in crabs acclimated to different salinities and exposed to 2 × 10−4M Diamox. Haemolymph CO2 content increased at all salinities, especially low salinities, while pH remained unchanged, except at low salinities where it increased. Diamox impaired the regulation of haemolymph chloride at low salinities, but had no effect on chloride regulation at high salinities. Measurement of O2 uptake (estimating CO2 production) in crabs before and after Diamox exposure confirmed that elevated haemolymph CO2 was not due to increases in tissue CO2 production.