bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Hormone Effecting Immobilization in Pupariating Fly Larvae
Authors: Zdarek Jan , Rohlf Rebecca , Blechl Jim , Fraenkel Gottfried 
Published: April 2021

ABSTRACT
The haemolymph of 1–2 h old (orange) puparia of Sarcophaga bullata contains a factor (PIF) which immobilizes mature fly larvae, most strongly 6–24 h before pupariation. It has all the properties of a protein: a mol. wt. of between 100000 and 300000 daltons, it is heat labile, non-dialysable, destroyed by trypsin, and precipitated by NH4SO4. It is possibly identical with the anterior retraction factor (ARF) because the activity of both always went hand in hand. Its action seems to be unspecific in cyclorrhaphous flies. Much about PIF has been learned from studying changes in internal haemolymph pressure of larvae injected with PIF before and during pupariation. Its function is probably to shut off muscular activity after the puparium is completed. It may also function in very small dosages at the beginning of pupariation when the activity of the larvae decreases.
The Effect of Salt Adaptation and Amiloride on the In Vivo Acid-Base Status of the Euryhaline Toad Bufo Viridis
Authors: Katz U. 
Published: April 2021

ABSTRACT
The acid-base status of the blood of the toad Bufo viridis was studied during adaptation to high salinity and in tap water containing amiloride. Both salt adaptation and immersion for 2 – 3 days in 5 × 1−4 M amiloride in tap water resulted in a decrease in blood pH (from 7·720 ± 0·026 in tap water to 7·4561 0·051 in 500 mOsm NaCl-adapted toads ; mean ± S.E.), and a simultaneous decrease in the concentration of HCO3− (from 17·8 ±1·4 in tap water to 9·5 + 1·2 in salt-adapted toads). In vitro determination of Na+/H+ exchange across the skin showed a 1:1 relation in skins from tap-water-adapted toads; this exchange was inhibited by amiloride. H+ secretion was abolished in skins from salt-adapted toads and the uptake of sodium was reduced.
Landing Reaction of Musca Domestica
Authors: Chillemi S. , Taddei-Ferretti Cloe 
Published: April 2021

ABSTRACT
Electrophysiological recordings from the sub-oesophageal ganglion and cervical connective of Musca domestica have revealed the existence of units which integrate visual stimuli that elicit landing behaviour (light-off stimulus or expansion of a spatial pattern) and those which cause inhibition of a landing behaviour already in progress (light-on stimulus or contracting pattern).
Energetics of Cockroach Locomotion
Authors: Herreid Clyde F. , Full Robert J. , Prawel David A. 
Published: April 2021

ABSTRACT
Cockroaches, Gromphadorhina portentosa, were run at different speeds for 20 min on a miniature treadmill enclosed in a lucite respirometer while oxygen consumption was continuously monitored. The data collected on these 5 g insects are remarkably similar to those obtained on vertebrates.
rises rapidly with the onset of exercise ; the on-response was about 1 min with steady-state reached within 4 min at the fastest speed, 0-12 km/h. Recovery was rapid ; the off-response was 4-6 min, with total recovery achieved in less than 1 h. The tracheal system appears to be a highly efficient mode of O2 conductance in contrast to the crustacean method of delivery involving gills and circulation.
(ml O2/g.h) at steady-state running varies directly with velocity (V). The regression equation at 24 °C is . The F-intercept, at zero velocity, is 2·4 times the actual resting rate of 0-19 ml O2/g.h. Temperature does not change the slope of the regression line but shifts it up or down in accordance with a simple Q10 effect. Incline running produces no changes compared to level running.
The minimum cost of transport, the lowest necessary to transport a given mass a specific distance, is high in cockroaches (4-92 ml O2/g.km) and comparable to that expected for a small quadrupedal or bipedal pedestrian vertebrate.
Physiological Identification and Asymmetry of Lobster Claw Closer Motoneurones
Authors: Govind C. K. , Lang F. 
Published: April 2021

ABSTRACT
The somata of the fast closer exciter (FCE) and slow closer exciter (SCE) motoneurones to the dimorphic claw muscles of the lobster Homarus americanas were physiologically identified in an isolated claw-ganglion preparation, by recording from a cell body simultaneously with recording from an identified axon. The FCE, SCE, and opener exciter (OE) somata are the largest cells in the anterior ventral region of the ganglion and appear consistently as a triad. A marked asymmetry occurred in the responsiveness of the identified FCE and SCE somata to sensory stimulation via the 2nd root. The SCE soma produced a longer burst with higher spike frequencies than the FCE soma in either cutter or crusher claw. When homologous somata were compared, the crusher FCE and SCE produced higher frequencies and longer bursts of spikes than their cutter counterparts. Since this occurred in response to both sensory stimulation via the 2nd root and depolarization of the soma it suggests that differences in motor output between homologous motoneurones have an extrinsic and intrinsic origin. Furthermore, asymmetry sometimes occurred within an individual motoneurone with a larger number of spikes in the soma than in the axon. Thus the homologous FCE and SCE motoneurones are differentiated into physiologically different types.
Possible Roles of Vertebrate Neuroglia in Potassium Dynamics, Spreading Depression and Migraine
Authors: Gardner-Medwin A. R. 
Published: April 2021

ABSTRACT
The membranes of glial cells are highly selectively permeable to potassium. The implications of this and the possible reasons for it are discussed. Glial cells may contribute to buffering the extracellular K+ concentration of brain tissue through several mechanisms. However, the only one that benefits from the K+ selective permeability is the so-called ‘spatial’ buffer mechanism, which acts more effectively than extracellular diffusion in many situations to speed the dispersal of local accumulations of potassium.
The role of glial cells in buffering the extracellular K+ concentration may help to prevent the occurrence of a phenomenon called Leão’s spreading depression (SD). A K+-induced K+ efflux from neurones, occurring when the EC K+ concentration rises above critical levels, is probably crucial in causing SD. The models that have been proposed to describe this process are discussed and related.
Spreading depression is not known definitely to occur in man. It seems probable, however, that it occurs during attacks of ‘classical’ migraine, associated with neurological symptoms. These neurological symptoms have often been attributed to vasoconstriction rather than to SD since certain vasodilators can relieve the symptoms. Experiments with SD in anaesthetized rats show that at least one of these vasodilator interventions (administration of a CO2/O2 mixture) stops also the propagation of a wave of SD. This strengthens the evidence for a possible relationship between migraine and SD. The involvement of SD in migraine probably deserves more critical attention than has hitherto been devoted to it.
Glial Versus Neuronal Uptake of Glutamate
Authors: Currie D. Neil , Kelly John S. 
Published: April 2021

ABSTRACT
Inactivation of amino acid neurotransmitters is generally held to be via high-affinity uptake into pre-synaptic neurones and glia, a model well established for monoaminergic systems. GABA for instance, is taken up at high affinity by glia and GABAergic neurones, and the two uptake systems have been distinguished by the use of competitive analogues in vivo and in vitro. Consequently, autoradiographic location of neuronal GABA uptake has become a useful method for recognition of GABAergic neurones. However, in the case of glutamate, the site(s) of high-affinity uptake are not well established and there are contradictions in the literature between results obtained by different methods. Biochemical studies on compartmentation in the metabolism of glutamate and the related amino acids GABA, aspartate and glutamine indicate strongly that glutamate uptake is exclusively located in glia. This is in accordance with the hypothesis of a neuronal-glial cycle in which glutamate passes from neurones to glia, and is returned to the neurones as glutamine. In vitro studies of uptake into isolated cell types show a high glial capacity for glutamate uptake. Studies of neuronal glutamate uptake in vitro are few and the results, although equivocal, indicate a lack of high-affinity uptake. Autoradiography of uptake of glutamate, or the non-metabolisable analogue, D-aspartate, has been performed in vivo by several groups of workers at the light and EM level. Some have reported only glial uptake, while others have reported a predominantly neuronal uptake of glutamate and have used this as a criterion for the presence of glutamatergic neurones. Considerable support for this interpretation comes from the finding that transection of the relevant pathways leads to a substantial reduction in the target tissue capacity for high-affinity glutamate uptake. Selective killing of supposed glutamatergic populations of neurones such as cerebellar granule neurones also leads to loss of glutamate uptake.
The Role of Support Cells in the Growth and Differentiation of Neurones in the Abdominal Ganglion of Aplysia
Authors: Schacher Samuel M. 
Published: April 2021

ABSTRACT
During the late premetamorphic stages of development, the abdominal ganglion of Aplysia is surrounded by a group of support cells which later develop morphological properties characteristic of glial cells. These support cells contain large secretory granules whose contents are released primarily after the onset of the metamorphic phase. The release of the granule contents may signal the burst of neuronal growth and maturation that occurs following metamorphosis. The evidence supporting this idea is the following: (1) The release of the granule material after the onset of metamorphosis coincides with an increase in cell body growth and a more marked increase in the density of synapses within the neuropil. Both release and neuronal maturation can be blocked when metamorphosis is postponed by withholding the appropriate macroalgal substrate. (2) Premature release of the granule contents 2–3 weeks before metamorphosis with artificial sea water containing a high concentration of potassium results in an increase in cell body growth, density of synapses, and the number of spines formed and contacts received by specific identified cells. (3) Artificially inducing the release of the granule material in animals whose metamorphosis has been prevented (by withholding the appropriate substrate) still produces an increase in cell body growth and density of synapses. These results suggest that the release of material from support cell granules provides a general stimulus for neuronal differentiation including cell body growth, spine development, and synapse formation.
Invertebrate Neuroglia-Junctional Structure and Development
Authors: Lane Nancy J. 
Published: April 2021

ABSTRACT
The morphological characteristics of the neuroglial cells of invertebrates are reviewed, including the ultrastructural and enzyme cytochemical features of their cell bodies and attenuated cytoplasmic processes, the various ways they ensheath the nerve cells, including the loosely myelinated condition, their modifications due to intraganglionic localization and their interactions with other glial cells in the form of homocellular junctions. The spectrum of heterocellular axo-glial associations that occur in invertebrates is considered with particular reference to the different kinds of intramembranous organization they exhibit as revealed by freeze fracture. Recent studies on glial cell development in a range of arthropods, during embryonic and pupal stages, reveal the importance of glial cell tight junctions in forming the tracer-excluding blood-brain barrier. These occluding junctions are now shown to be, in some cases, vertebrate-like in their complexity. The stages in their assembly, which may be concurrent with those of gap junction formation, reveal a number of differences from vertebrate glia. During metamorphosis, glial cells dissociate and the dynamics of the concomitant interglial junctional disruption and their intramembranous particle dispersal without apparent internalization, as well as their subsequent reassembly, are examined. The stimuli triggering these glial events and the physiological significance of the various glial modifications are considered.
Behavioural and Mechanosensory Neurone Responses to Skin Stimulation in Leeches
Authors: Kristan William B. , McGIRR STEPHEN J. , Simpson Gregory V. 
Published: April 2021

ABSTRACT
Behavioural responses to electrical stimulation of mechanosensory neurones were characterized in two species of leeches, Hirudo medicinalis and Macrobdella decora. Depending upon the site and intensity of stimulation, the stimuli elicited one or a combination of five different responses: local bending, curling, shortening, whole-body bending or swimming. The electrical threshold for activating identified mechanosensory neurones, T (touch) cells and P (pressure) cells, was the same in all regions of the body. The voltage range over which the electrical stimuli produced progressively more mechanosensory impulses was the same as the range that produced different behavioural responses. These results suggest that the T and P mechanosensory neurones provide the entire sensory input for all the behavioural responses. The production of different behavioural responses to stimuli of different intensities at the same location are attributable to different firing rates of the same sensory cells, and different responses to the same stimulus at different locations suggest different interneuronal targets for the T and P cells in different body regions.
Changes in Vascular and Extravascular Volumes of Eel Muscle in Response to Catecholamines: The Function of the Caudal Lymphatic Heart
Authors: Davie Peter S. 
Published: April 2021

ABSTRACT
Vascular volume changes in an isolated saline-perfused eel tail preparation in response to catecholamines were small (&lt; 2 %) and are explicable in terms of changes in volume of pre-capillary resistance vessels. Extravascular-extracellular (interstitial) volume increased less than 3 % during infusion of adrenaline (AD) at concentrations of 1 × 10−6 to 1 × 10−3 M. Injection of doses of AD and noradrenaline (NA) between 1 nmol and 100 nmol caused maximum interstitial volume changes of less than 11%. Isoprénaline caused only very small changes in vascular and interstitial volumes. Caudal lymph heart frequency increased when high concentrations (&gt; 1 × 10−6 M) and doses (&gt; 1 nmol) of AD and NA were administered. Caudal lymph heart frequency increases were significantly correlated with changes in outflow after vascular volume adjustments. One function of the caudal lymph heart is to return interstitial fluid to the vascular system.
Long-Term Submergence At 3 °C of the Turtle, Chrysemys Picta Bellii, In Normoxic and Severely Hypoxic Water
Authors: Jackson Donald C. , Ultsch Gordon R. 
Published: April 2021

ABSTRACT
Plasma [Na+], [K+], and [Cl-] were measured on blood sampled periodically from turtles submerged in Na-equilibrated (low-O2) or air-equilibrated (high-O2) water. Plasma osmolality and total [Ca2+] and [Mg2+] were measured on selected samples. Previously we reported that a severe metabolic acidosis developed under these conditions; in low-O2 turtles, plasma [lactate-], rising to over 200 m-equiv/1, was only partially buffered by [HCO3-], which fell from 40 to 5 m-equiv/1.
The balance of the buffering was accomplished by changes in strong ions which included (in low-O2) a fall in [Cl−] from 79·5 ±1·4 m-equiv/1 to below 60 m-equiv/1, a rise in [Ca2+] from 3 to over 100 m-equiv/1, and a rise in [Mg2+] from 3 to over 30 m-equiv/1. Together, all ionic changes balanced the increase in [lactate-], but this analysis is tentative because we do not know the distribution of Ca2+ and Mg2+ between free and bound forms in vivo. Plasma osmolality rose from 233 ±4·1 to 382 ± 12·4 mosmol after 162 days in low-O2, even though the turtles showed a gain in body weight. The ionic changes that occurred in plasma also occurred in the pericardial and peritoneal fluids, suggesting general extracellular fluid participation in lactate buffering. Bladder urine contained significant concentrations of both lactate and calcium, indicating that some acid excretion may have occurred during the submergence.
An Endogenous Crepuscular Rhythm of Rainbow Trout (Salmo Gairdneri) Photomechanical Movements
Authors: Douglas R. H. 
Published: April 2021

ABSTRACT
The position of the epithelial pigment and cones in the retina of Salmo gairdneri was determined during extended periods of darkness in fish entrained to both artificial and natural light/dark cycles. An endogenous rhythm of such photomechanical movements, unique among species so far examined, was observed in both groups of fish, with two peaks of light adaptation coincident with dawn and dusk. It is suggested that such an apparently non-adaptive physiological rhythm is related to the behavioural pattern of trout and reveals a basic crepuscular organisation. No endogenous rhythm was observed in continual light. These results suggest that control of photomechanical changes in rainbow trout has two components : an endogenous component, that causes the bimodal pattern in maintained darkness, and a direct effect of light, that maintains light adaptation throughout a normal day.
The Transition to Air Breathing in Fishes
Authors: Graham Jeffrey B. , Baird Troy A. 
Published: April 2021

ABSTRACT
In response to progressive aquatic hypoxia, the armoured loricariid cat-fishes Ancistrus chagresi and Hypostomus plecostomus become facultative air-breathers and utilize their stomachs as accessory air-breathing organs. Hypostomus initiates air breathing at a higher aquatic O2 tension than does Ancistrus (60 v. 33 mmHg). Once begun, the air-breathing frequencies of both species increase with decreasing ; the frequency of Ancistrus, however, is greater than and increases more with hypoxia than does that of Hypostomus, which appears to be a more efficient air breather.
Hypoxia acclimation reduces the air-breathing rate of both species. A larger rate reduction occurs in Ancistrus, which, however, continues to require more frequent breaths than Hypostomus. Hypoxia acclimation does not affect the air-breathing threshold of either species, suggesting that external O2 receptors initiate facultative air breathing.
In progressive aquatic hypercapnia Ancistrus has a lower air-breathing CO2 threshold (8·7 mmHg) than Hypostomus (12·8 mmHg). However, in some tests, individual fish of both species did not initiate air breathing even at . as high as 21 mmHg. Also, air breathing evoked by hypercapnia was short-lived; both species quickly compensated for this gas and resumed exclusively aquatic respiration within a few hours of exposure. Thus, CO2 is not an important regulator of air breathing in these species. Between 25 and 35 °C, the air breathing threshold of Ancistrus is temperature-independent, but air-breathing frequency increases with temperature.
Ancistrus and Hypostomus do not breathe air in normoxic (air-saturated) water; their air-breathing responses are evoked by environmental hypoxia. This is fundamentally different from other fish species that breathe air in normoxia in order to meet heightened metabolic demands. Also, the facultative air-breathing adaptations of Ancistrus and Hypostomus differ in scope and magnitude from those utilized by species that breathe air in normoxia and adapt to hypoxia by increasing air-breathing rate.
Energetics and mechanics of terrestrial locomotion. I. Metabolic energy consumption as a function of speed and body size in birds and mammals
Authors: Taylor C. R. , Heglund N. C. , Maloiy G. M. O. 
Published: April 2021

ABSTRACT
This series of four papers investigates the link between the energetics and the mechanics of terrestrial locomotion. Two experimental variables are used throughout the study : speed and body size. Mass-specific metabolic rates of running animals can be varied by about tenfold using either variable.
This first paper considers metabolic energy consumed during terrestrial locomotion. New data relating rate of oxygen consumption and speed are reported for: eight species of wild and domestic artiodactyls; seven species of carnivores ; four species of primates ; and one species of rodent. These are combined with previously published data to formulate a new allometric equation relating mass-specific rates of oxygen consumed during locomotion at a constant speed to speed and body mass (based on data from 62 avian and mammalian species):

where has the units ml O2 s−1 kg−1; Mb is in kg; and vg is in m s−1. This equation can be expressed in terms of mass-specific rates of energy consumption (Ėmetab/Mb) using the energetic equivalent of 1 ml O2 = 20·1 J because the contribution of anaerobic glycolysis was negligible :

where Ėmetab/Mb has the units watts/kg.
This new relationship applies equally well to bipeds and quadrupeds and differs little from the allometric equation reported 12 years ago by Taylor, Schmid-Nielsen & Raab (1970). Ninety per cent of the values calculated from this general equation for the diverse assortment of avian and mammalian species included in this regression fall within 25 % of the observed values at the middle of the speed range where measurements were made. This agreement is impressive when one considers that mass-specific rates of oxygen consumption differed by more than 1400% over this size range of animals.
Sensory alteration of motor patterns in the stomatogastric nervous system of the spiny lobster Panulirus interruptus
Authors: Sigvardt Karen A. , Mulloney Brian 
Published: April 2021

ABSTRACT
Stretching the pyloric region of the lobster’s stomach in a manner that resembles pyloric dilation triggers a prolonged burst of impulses in two interneurones with axons in the inferior ventricular nerve (IVN). The burst is activated in the oesophageal ganglion by sensory axons that traverse the lateral ventricular nerves, the dorsal ventricular nerve and the stomato-gastric nerve. These sensory axons do not appear to make synaptic contacts in the stomatogastric ganglion. Electrical stimulation of sensory branches of the pyloric nerve triggers similar bursts in the IVN interneurones. The burst of impulses in the IVN interneurones lasts from 2 to 30 s and the impulse frequency ranges from 10 to 80 Hz in different parts of the burst. Once triggered, burst structure and burst duration are independent of the intensity or duration of stimuli applied to the sensory nerves. These bursts alter both the gastric and pyloric motor patterns. The IVN interneurones make a complex pattern of synapses with stomatogastric neurones. These are: pyloric dilators (PD) -excitation and slow inhibition; ventricular dilator (VD) -excitation ; gastric mill (GM) neurones -inhibition; lateral posterior gastric neurones (LPGN) -inhibition ; and Interneurone I (Int 1) -excitation and slow inhibition. The size of the p.s.p.s at each of these synapses depends on the duration and impulse-frequency of the burst in the presynaptic neurones, which in turn alters the firing patterns of the stomatogastric neurones in various ways.