bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vacuolar ATpase of Neurospora Crassa: Electron Microscopy, Gene Characterization and Gene Inactivation/Mutation
Authors: Bowman Barry J. , Dschida William J. , Bowman Emma Jean 
Published: April 2021

ABSTRACT
We are using three approaches to investigate the vacuolar ATPase, V-ATPase, from Neurospora crassa. (1) Examination in the electron microscope shows the enzyme has a ‘ball and stalk’ structure like the F-type ATPases. However, the vacuolar ATPase is significantly larger, has a prominent cleft in the head sector, and has extra components associated with the stalk and membrane sectors. (2) Genes encoding three of the major subunits of the vacuolar ATPase and the homologous subunits of the mitochondrial F-ATPase have been isolated. The exon/intron structures of the genes have been analyzed and the chromosomal locations have been determined. Two of the vacuolar ATPase genes map very close to each other, suggesting the possibility of a cluster of ATPase genes. (3) The function of the ATPase is being investigated by isolating strains with altered or inactivated ATPase. We are characterizing strains that are resistant to bafilomycin A1, a potent and specific inhibitor of the vacuolar ATPase. Initial attempts to inactivate a vacuolar ATPase gene indicate that the enzyme may be essential for growth.
Identification, Characterisation and In Vitro Reconstruction of an Interneuronal Network of the Snail Helisoma Trivolvis
Authors: Syed N. I. , Roger I. , Ridgway R. L. , Bauce L. G. , Lukowiak K. , Bulloch A. G. M. 
Published: April 2021

ABSTRACT
We describe three interneurones and their follower cells in the central ganglionic ring of Helisoma trivolvis. The largest neurone on the dorsal surface of the left pedal ganglion is shown to be an interneurone that contains dopamine and makes monosynaptic connections with a large number of follower cells in the visceral and left parietal ganglia. This neurone is designated as left pedal dorsal 1 (LPeD1). Another giant neurone is located on the dorsal surface of the right pedal ganglion. Although the position and morphology of this cell, designated right pedal dorsal 1 (RPeD1), are similar to those of LPeD1, it contains serotonin rather than dopamine. This neurone was found to synapse only on LPeD1, no other follower cells have so far been discovered. The connections between LPeD1 and RPeD1 are mutually inhibitory. A small FMRFamide-immunoreactive neurone, identified here as visceral dorsal 4 (VD4), is located on the dorsal surface of the visceral ganglion. This neurone has a large number of follower cells throughout the central ganglionic ring. Among these follower cells are LPeD1 and RPeD1. The transmitter utilized by VD4 at these synapses is probably FMRFamide. In addition, VD4 receives excitatory inputs from LPeD1 that appear to be chemical and monosynaptic. To test further the monosynaptic and specific nature of the connections within the network, the three interneurones were isolated and cultured in vitro. In these circumstances, the three neurones extended neurites and formed synapses which, with one exception (occasional electrical coupling between LPeD1 and RPeD1), were of similar type to those observed invivo. The identification and characterization of these three interneurones and their follower cells should greatly facilitate future studies of the Helisoma trivolvis nervous system. Furthermore, the possibility that this three-cell network can be reconstructed in vitro should aid our understanding of the mechanisms underlying synapse formation and neuronal plasticity.
Electrophysiological Evidence for the Modulation of Acetylcholine Release by Endogenous Acetylcholine in the Cockroach Central Nervous System
Authors: Corronc H. Le , Hue B. 
Published: April 2021

ABSTRACT
Biochemical studies of the central nervous system (CNS) of locusts (Breer and Knipper, 1984; Knipper and Breer, 1988) have provided evidence for a muscarinic negative feedback mechanism in which muscarinic antagonists and agonists, respectively, enhance and decrease the acetylcholine (ACh) output. More recently, this inhibitory action of presynaptic muscarinic acetylcholine receptors (mAChrs) has been demonstrated in cockroach (Hue et al. 1989; Le Corronc et al. 1991) and in tobacco hornworm (Trimmer and Weeks, 1989) using electrophysiological methods. However, in insects, most experiments have not been performed under physiological conditions but in the presence of acetylcholinesterase inhibitors or exogenous agonists. The aim of this study was to determine whether the release of ACh at a central synapse in the cockroach, Periplaneta americana, could be modulated by endogenous ACh acting on presynaptic muscarinic receptors.
Indications for Two Bioactive Principles in the Corpuscles of Stannius
Authors: Verbost P. M. , Butkus A. , Willems P. , Bonga S. E. Wendelaar 
Published: April 2021

ABSTRACT
For a long time it was thought that the corpuscles of Stannius (CS) of holostean and teleostean fishes produce a single hormone reducing Ca2+ influx from the water via the gills. We here present data showing that two separate bioactive principles are present in the CS: stanniocalcin (STC), a 56kDa glycoprotein, and teleocalcin (TC), a 3kDa glycopeptide. STC indeed inhibits Ca2+ influx (as reported many times before) but does not affect the Ca2+-and Mg2+-dependent phosphatase activity located in the gill plasma membrane. TC does not affect Ca2+ influx but inhibits the Ca2+-and Mg2+-dependent phosphatase activity. Thus, the Ca2+-and Mg2+-dependent phosphatase activity appears not to be involved in transbranchial Ca2+ transport. We conclude that STC is the pivotal calcium-regulating hormone in fish and that TC has an as yet unidentified role in gill physiology through its phosphatase-reducing activity.
Effect of Adenosine on Glucose Metabolism of Rana Ridibunda Erythrocytes
Authors: Kaloyianni Martha , Michaelidis Basile , Moutou Katerina 
Published: April 2021

ABSTRACT
The effects of adenosine and inosine on Rana ridibunda erythrocyte metabolism were studied. Adenosine can be metabolized by Rana ridibunda erythrocytes as a carbon source for glycolysis to maintain ATP levels, whereas neither inosine nor glucose could maintain ATP levels. The rate of lactate production was maximal (2.89 μmolml-1 redcell h-1) in the presence of adenosine together with glucose compared with that in the presence of glucose or adenosine alone. Inosine sustained a similar rate of lactate production as did glucose. The concentrations of phosphorylated hexoses increased during 4h of incubation in the presence of adenosine either with or without glucose. The presence of sodium iodoacetate accelerated the loss of ATP; furthermore, levels of lactate and pyruvate were significantly reduced in the presence of either adenosine or inosine. Ouabain strongly inhibited ATP and lactate formation in the presence of adenosine, whereas the levels of ATP and lactate were almost unchanged in the presence of inosine. An inhibitor of adenosine transport, dipyridamole, impeded the increases in erythrocyte lactate and ATP concentration in the presence of adenosine but did not modify the effects of inosine.
The Gleaning Attacks of the Northern Long-Eared Bat, Myotis Septentrionalis, Are Relatively Inaudible to Moths
Authors: Faure Paul A. , Fullard James H. , Dawson Jeff W. 
Published: April 2021

ABSTRACT
This study empirically tests the prediction that the echolocation calls of gleaning insectivorous bats (short duration, high frequency, low intensity) are acoustically mismatched to the ears of noctuid moths and are less detectable than those of aerially hawking bats. We recorded auditory receptor cell action potentials elicited in underwing moths (Catocala spp.) by echolocation calls emitted during gleaning attacks by Myotis septentrionalis (the northern long-eared bat) and during flights by the aerial hawker Myotis lucifugus (the little brown bat). The moth ear responds inconsistently and with fewer action potentials to the echolocation calls emitted by the gleaner, a situation that worsened when the moth’s ear was covered by its wing (mimicking a moth resting on a surface). Calls emitted by the aerial-hawking bat elicited a significantly stronger spiking response from the moth ear. Moths with their ears covered by their wings maintained their relative hearing sensitivity at their best frequency range, the range used by most aerial insectivorous bats, but showed a pronounced deafness in the frequency range typically employed by gleaning bats. Our results (1) support the prediction that the echolocation calls of gleaners are acoustically inconspicuous to the ears of moths (and presumably other nocturnal tympanate insects), leaving the moths particularly vulnerable to predation, and (2) suggest that gleaners gain a foraging advantage against eared prey.
Cardiac regulation by endogenous small cardioactive peptides and FMRFamide-related peptides in the snail Helix aspersa
Authors: Lesser W. , Greenberg M. J. 
Published: April 2021

ABSTRACT
The putative heptapeptide pQDPFLRIamide, previously known only from its appearance in a cDNA clone from Helix aspersa, was isolated from circumoesophageal ganglia extracts and sequenced.
Extracts of several tissues were fractionated by high performance liquid chromatography and the fractions analysed by radioimmunoassay (RIA). The results indicate that ten cardioactive peptides, FMRFamide, FLRFamide, six FMRFamide-related heptapeptides and two nonapeptide analogues of the small cardioactive peptides (SCPs), are present in the circumoesophageal ganglia (brain), the visceral nerve trunk (from which the cardiac nerve branches) and the aorta. The heart contains the two tetrapeptides, FMRFamide and FLRFamide, and the SCPs, but the heptapeptides were completely undetectable in this organ. The levels of tetrapeptide were high enough to allow their calcium-dependent release from the heart to be demonstrated. Immunohistochemistry revealed a diffuse SCP and FMRFamidergic innervation distributed throughout the heart. These data support the idea that, although the ten peptides are probably acting as neurotransmitters throughout most of the cardiovascular system, the heptapeptides probably also have a neurohormonal rôle on the Helix aspersa heart itself. The binding affinities of the various antisera used in these studies were examined in competitive RIAs, in non-competitive dot-blot assays or in both.
Muscle Performance in Hovering Hummingbirds
Authors: Wells Dominic J. 
Published: April 2021

ABSTRACT
The flight energetics of hovering hummingbirds was examined by simultaneous collection of metabolic and kinematic data followed by a morphometric analysis of wing characteristics. These data were then used for an aerodynamic analysis of the power output required to generate sufficient lift; this, together with the metabolic power input, allowed an estimate of the flight efficiency. The use of two closely related species demonstrated common design features despite a marked difference in wing loading. Considerations of the inertial power costs strongly suggest that hummingbirds are able to store kinetic energy elastically during deceleration of the wing stroke. This analysis predicts that hummingbirds hover with a muscle power output close to 100–120 W kg−1 at 9–11% mechanochemical efficiency.
The Effect of Ionic Copper on the Oxygen Consumption of Gammarus Pulex and Polycelis Nigra
Authors: Erichsen Jones J. R. 
Published: April 2021

ABSTRACT
The suggestion has been put forward that the oligodynamic action of certain heavy metals is the result of the destruction or inactivation of substances essential for cellular respiration. In a study of the effect of copper sulphate solutions on the oxygen consumption of Polycelis nigra it is found that solutions of concentration 0·001–0·001 N, fatal in 2 hr. or less, induce a marked preliminary rise in the respiration rate ; this appears to be due to the inhibition of ciliary locomotion and increased muscular activity. A similar increase is produced by increasing the activity of the animals by mechanical means, or by a muscle stimulant (barium chloride). Over the latter part of the survival time the respiration rate drops rapidly and disintegration of the animals begins when it falls to about 60 % of the normal value. A 0·0004 N copper sulphate solution does not inhibit ciliary locomotion, does not stimulate muscular activity, and the oxygen consumption undergoes a steady decline. A 0·0002 N NaCN solution rapidly depresses the respiration rate to less than 20 % of the normal value, but is not fatal, the animals surviving over 4 days. Hydrogen ions, at the concentrations resulting from the hydrolysis of the salt, have no appreciable effect on the oxygen consumption, but at lethal concentrations (pH 2·6, 2·8) effect a speedy depression. The results suggest that the depression of respiration rate observed is insufficient to account for the death of the animals, and is no more than a symptom of the toxic process.
A similar general result was obtained in experiments with silver nitrate and mercuric chloride, and also in experiments on the comparative effect of copper sulphate and sodium cyanide solutions on the oxygen consumption of Gammarus pulex.
The Role of the Pituitary and the Thyroid in the Development of Teleosts
Authors: Landgrebe F. W. 
Published: April 2021

ABSTRACT
There is no satisfactory evidence for regarding the organ of Syrski as the male gonad of Anguilla. Silvering of the eel, salmon and trout is independent of gonad development and cannot therefore be regarded as a ‘breeding dress ‘ Injection of either pregnancy urine, ox anterior lobe extracts, pig anterior lobe extracts and thyroid extracts, as also pituitary homeo-implantation. were all without effect on the gonads of eels treated in this way. Ox anterior lobe extracts produced premature smoltification in Salmo salar, had no visible effect on S. trutta or on Anguilla vulgaris, and did not affect the gonads in either species. Injection of thyroid extracts produced silvering in salmon and brown trout but had no effect on the eel. After two months’ treatment with thyroid extract brown trout are externally indistinguishable from sea trout.
The Action of Potassium on Echinoderm, Molluscan and Crustacean Muscle
Authors: Wells G. P. 
Published: April 2021

ABSTRACT
Some years ago, the writer published an account of the action of potassium on the crops of Aplysia and Helix, and the hearts of Maia and Homarus (Wells, 1928). It was pointed out that the preparations used show a general resemblance in their responses to changes in potassium concentration, although they include plain and striped muscle, and are taken from molluscs and crustaceans. Since that time he has made similar experiments on other preparations. The results are now described and discussed from a comparative standpoint. It appears that potassium—in contrast to calcium, which has the most diverse effects—-produces essentially similar responses in muscles from animals of various different phyla, and of quite different histological and functional nature. The suggestion is made that all types of rhythmic muscle are essentially alike in their responses to comparable changes in the potassium concentration of the environment.
Chromatic Behaviour of Scyllium Canicula
Authors: Waring H. , Landgrebe F. W. , Bruce J. R. 
Published: April 2021

ABSTRACT
Dermal melanophores of intact Scyllium equilibrate at μ = 4·9 and μ — 1·4 respectively on black and white background with overhead illumination. They equilibrate at μ = 2·9 in complete darkness. Normal responses are of the ‘slow’ type. Expanded melanophores in skin strips immersed in saline contract in 30 min. In pituitary extract they expand in 60 min. So we may interpret the slow responses of intact fish as indices of the slow rise and fall of co-ordinating hormones in circulation. The time relations of normal responses are not consistent with a one-hormone hypothesis. Thyroids removed from animals hypophysectomized a month previously afford no evidence for pituitary control of thyroid activity.
Coupled Versus Uncoupled Functional Systems: Motor Plasticity In The Queen Triggerfish Balistes Vetula
Authors: Wainwright Peter C. , Turingan Ralph G. 
Published: April 2021

ABSTRACT
Teleost fishes typically capture prey with the oral jaws and perform most types of prey-processing behavior with the pharyngeal jaw apparatus. In these fishes, the motor patterns associated with the different stages of feeding are quite distinct, and fish can modify muscle activity patterns when feeding on different prey. We examined motor pattern variation in the queen triggerfish, Balistes vetula, a versatile predator that both captures and processes prey with its oral jaws. During feeding on three prey that differed in hardness and elusiveness, three distinct patterns of behavior could be identified on the basis of patterns of muscle activity: prey capture, buccal manipulation and blowing. During prey capture by suction feeding, the retractor arcus palatini muscle (RAP) commenced activity before the levator operculi muscle (LOP). In both buccal manipulation and blowing, the RAP began activity well after the onset of activity in the LOP. Both prey capture and buccal manipulation motor patterns varied when fish fed on different prey. When capturing hard-shelled and non-elusive prey, B. vetula did not employ suction feeding but, instead, the fish directly bit parts of its prey. The motor pattern exhibited during direct biting to capture prey was different from that during suction feeding, but was indistinguishable from the pattern seen during the repeated cycles of buccal manipulation. Harder prey elicited significantly longer bursts of activity in the jaw adductor muscles than did soft prey. In spite of the involvement of the oral jaws in virtually all stages of feeding, B. vetula shows levels of variation between patterns of behavior and types of prey characteristic of previously studied teleost fishes. Thus, the coupling of capture and processing behavior patterns in the repertoire of the oral jaws does not appear to constrain the behavioral versatility of this species.
Behaviour of Dogs During Olfactory Tracking
Authors: Thesen Aud , Steen Johan B. , Døving Kjell B. 
Published: April 2021

ABSTRACT
The ability to detect the direction of a track is of vital importance to animals of prey and is retained in many modern breeds of dogs. To study this ability, four trained German shepherd tracking dogs, equipped with head microphones to transmit sniffing activity, were video-monitored after being brought at right angles to a track where the position of each footprint was known. Three phases could be recognized in the dogs’ behaviour: (1) an initial searching phase, during which the dog tried to find the track, (2) a deciding phase, during which it tried to determine the direction of the track and (3) a tracking phase, in which it followed the track. During ten tests on 20-min-old tracks on grass, and ten tests on 3-min-old tracks on concrete, the dogs always followed the track in the correct direction (i.e. in the direction the track was leading). During the deciding phase the dogs moved at half the speed and their periods of sniffing lasted three times as long as during the other two phases.
The deciding phase lasted 3–5s, while the dogs sniffed at 2–5 footprints. The dogs’ ability to determine track direction in this time must rely on accurate methods of sampling air and a remarkable sensitivity for certain substances.
Effects of Ammonia on Survival, Swimming and Activities of Enzymes of Nitrogen Metabolism in the Lake Magadi Tilapia Oreochromis Alcalicus Grahami
Authors: Walsh Patrick J. , Bergman Harold L. , Narahara Annie , Wood Chris M. , Wright Patricia A. , Randall David J. , Maina J. N. , Laurent Pierre 
Published: April 2021

ABSTRACT
The Lake Magadi tilapia, Oreochromis alcalicus grahami, is remarkable among teleosts in that it flourishes under extremely well-buffered alkaline water conditions (pH10, 180mmol l−1) at temperatures of 30–40°C (Wood et al. 1989). As expected from current models in teleosts, ammonia excretion into such water would be difficult at best (Wood, 1993). Part of the survival strategy of the Lake Magadi tilapia is that it has a complete ornithine–urea cycle (O–UC) in the liver and excretes virtually all of its waste nitrogen as urea (Randall et al. 1989). Ammonia toxicity in ammoniotelic teleosts has been studied extensively, and typical values for unionized ammonia (NH3) 96h LC 50 (the concentration at which half of test subjects die after 96h) are well below 100 μmol l−1 (Haywood, 1983; Thurston et al. 1983a,b; Campbell, 1991). Surprisingly, no ammonia LC50 values are available for ureogenic teleost fish, and one would predict that fish synthesizing and excreting urea for whatever purpose would have higher LC50 values than their ammoniotelic counterparts. Additionally, since ammonia exposure has been implicated in the functional response of urea excretion in the Lake Magadi tilapia (Wood et al. 1989) and another ureogenic teleost (the gulf toadfish Opsanus beta) (Walsh et al. 1990), we reasoned that ammonia exposure in the Lake Magadi tilapia might reveal insights into the biochemical regulation of the O–UC in this species; in particular that it might induce enzyme activity. We report here that the Lake Magadi tilapia has a rather high ammonia LC50 compared to values for other teleosts, but that short-term ammonia exposure has very limited effects on the activities of the enzymes of nitrogen metabolism and on swimming performance.
Control of Body Height in a Stick Insect Walking on a Treadwheel
Authors: Cruse H. , Schmitz J. , Braun U. , Schweins A. 
Published: April 2021

ABSTRACT
The properties of the system that controls the distance between body and ground was investigated in the stick insect Carausius morosus. The insect walked on a lightweight double treadwheel under open-loop or closed-loop conditions. The open-loop investigations show that the dynamic behaviour of the height-control system in the walking animal can be described in terms of a simple proportional system with negligible dynamic properties, and it is therefore much simpler than the height-control system in the standing animal. Under open-loop conditions, we found no coupling between contralateral or ipsilateral legs. This agrees with the findings on standing animals. The force–height characteristic shows two ranges, in each of which the system exhibits a linear relationship but a different slope. Under closed-loop conditions, the force–height characteristic shows the same two linear ranges, but the slopes are greater than under open-loop conditions. Because the height controller of each leg can be considered to act like a spring, this result means that under closed-loop conditions the controller is stiffer than it is under open-loop conditions.