bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Modulation of Feeding Behavior in Response to Prey Type in the Frog Rana Pipiens
Authors: Anderson Curtis W. 
Published: April 2021

ABSTRACT
Using high-speed video motion analysis, the kinematics of feeding behavior was studied in Rana pipiens. Rana pipiens exhibits differing behavior patterns depending upon prey type. When feeding on small prey such as waxworms, R. pipiens uses tongue protraction to catch prey, minimizing head and body movements. When feeding on the larger earthworm, it arches its body, flexes the head downwards and uses jaw prehension to capture the prey. Time to completion of tongue retraction, time to completion of mouth closing, duration of tongue retraction, duration of mouth closing, total time that the mouth is open and maximum tongue reach were significantly longer during waxworm feedings than during earthworm feedings. The tongue angle and degree of head flexion were significantly greater during earthworm feedings. These different kinematic patterns correspond to differences in feeding behavior among major taxa of anurans. Phylogenetically primitive archaeobatrachian frogs have short tongues which can be protracted only a few millimeters. In contrast, many neobatrachians have long tongues which they project to catch small prey. The similarity between the behavior that neobatrachians use to catch large prey and the movement patterns of archaeobatrachians suggests that Rana pipiens has retained the plesiomorphic archaeobatrachian motor pattern and uses it to catch large prey, while evolving a new motor pattern for catching small prey.
Effect of Temperature on Central Chemical Control of Ventilation in the Alligator Alligator Mississippiensis
Authors: S. Branco Luiz Guilherme , Wood Stephen C. 
Published: April 2021

ABSTRACT
Central chemoreceptor function was assessed in unanesthetized alligators, Alligator mississippiensis, at body temperatures of 15, 25 and 35°C. Two experiments were performed. In the first experiment, the fourth ventricle was perfused with mock cerebrospinal fluid (CSF) solutions of different pH values (7.1–7.9). Changes in pulmonary ventilation were evaluated with a pneumotachograph and arterial pH (pHa) was measured. Perfusion with low-pH solutions increased ventilation and arterial pH. Perfusion with high-pH solutions decreased ventilation and arterial pH. Mock CSF pH had a greater effect at higher temperatures. In the second experiment, the relative contributions of central and peripheral chemoreceptor drive to breathing were evaluated using hypercapnic gas mixtures to stimulate both central and peripheral chemoreceptors. Hypercapnia caused an increase in ventilation which was larger at higher temperatures. To stimulate only the peripheral chemoreceptors, the same hypercapnic gas mixtures were applied while the CSF pH of the fourth ventricle was kept constant by perfusion with a mock CSF solution. This reduced significantly the ventilatory response induced by hypercapnia. These data indicate that, regardless of the temperature, central chemoreceptors play a major role in the ventilatory regulation of the alligator. The change in pHa with temperature is compatible with the alphastat hypothesis.
Quantitative Determination of Myotropic Neuropeptide in the Nervous System of the Cockroach Leucophaea Maderae: Distribution and Release of Leucokinins
Authors: Muren J. Eric , Lundquist C. Tomas , Nässel Dick R. 
Published: April 2021

ABSTRACT
Being interested in the distribution and function of insect myotropic peptides, we developed a sensitive radioimmunoassay (RIA) using an antiserum directed against the cockroach neuropeptide leucokinin I. The levels of leucokinin immunoreactivity were measured in extracts of different portions of the nervous system, in the retrocerebral complex and in the hemolymph of the cockroach Leucophaea maderae. The brain contains about 1.9pmol of immunoreactive material while the ganglia of the ventral nerve cord each contain less than 10% of this amount. Large amounts of leucokinin immunoreactivity (6.6pmol per tissue) were found in the corpora cardiaca–corpora allata (CC–CA) complex and in the hemolymph the titer was in the nanomolar range. When levels of leucokinins were compared in male and female cockroaches, no differences could be detected in any of the sample tissues. A calcium-dependent release of leucokinin-immunoreactive material could be induced from isolated CC–CA complexes by high-potassium depolarization. The amount of released immunoreactivity, as measured in the bathing saline by RIA, was about 2% of the extractable leucokinin immunoreactivity in the CC–CA complex. In Leucophaea maderae, the leucokinins apparently act both as neuroactive substances in the central nervous system and as neurohormones released into the circulation.
Modulation of Ca2+ and K+ Conductances in an Identified Insect Neurone by the Activation of an α-Bungarotoxin-Resistant Cholinergic Receptor
Authors: David Jonathan A. , Pitman Robert M. 
Published: April 2021

ABSTRACT
The effects of activation of a population of α-bungarotoxin (α-bgt)-insensitive cholinergic receptors on the soma of the cockroach fast coxal depressor motor neurone (Df) have been examined under two-electrode voltage-clamp conditions. Activation of these receptors was achieved by bath-application either of acetylcholine (ACh) in the presence of α-bgt or of the muscarinic agonist McN-A-343 (McN). Since these receptors have been shown previously to respond to some nicotinic agonists, we refer to them as ‘McN-sensitive or mixed pharmacological profile muscarinic receptors’ (mMAChRs). Activation of these receptors normally results in a biphasic response consisting of an initial outward current component, which reverses near −70 mV, and a later (delayed) inwardly directed current, which is only observed at membrane potentials more positive than −40 to −20 mV.
The initial outwardly directed component of the McN-induced current appears to result from an increase in K+ conductance since it reverses at potentials close to the K+ equilibrium potential (EK) (approximately −70 mV under the experimental conditions used) and is blocked by internal Cs+. This increase in K+ conductance is probably due to an increase in Ca2+-activated K+ current (IK,Ca) which is known to form a large proportion of the outward current observed when this neurone is depolarized.
The delayed inwardly directed current induced by McN results from suppression of a Ca2+ current (ICa) which, in turn, causes a decrease in IK,Ca. The net effect is a reduction in outward current, because IK,Ca is considerably larger than ICa. Evidence for an action of McN upon Ca2+ channels is provided by experiments in which K+ currents have been suppressed by internal Cs+ to reveal inward currents produced by the movement of Ba2+ through voltage-dependent Ca2+ channels. Ba2+ currents observed under these conditions are suppressed by bath application of McN. The inwardly directed current component of the McN response is unlikely to involve direct regulation of IK,Ca, since McN has no effect upon this current when it is induced by brief intracellular Ca2+ injections.
Both the initial outwardly directed component and the delayed inwardly directed component of the McN-induced current were suppressed by intracellular injection of the Ca2+ chelator BAPTA. These observations suggest that a rise in [Ca2+]i mediates the electrophysiological effects of McN in Df somata.
Evidence That Histamine is a Neurotransmitter in an Insect Extraocular Photoreceptor Pathway
Authors: Lundquist C. Tomas , Baines Richard A. , Bacon Jonathan P. 
Published: April 2021

ABSTRACT
The pair of vasopressin-like immunoreactive (VPLI) neurones of the locust Locusta migratoria have cell bodies in the suboesophageal ganglion and extensive arborization throughout the central nervous sytem. The activity of the VPLI neurone is regulated by a spontaneously active excitatory descending interneurone (DI) that is, in turn, inhibited by an uncharacterised extraocular photoreceptor (EOP) system located in the brain. Light directed at the brain results in inhibition of DI activity, which thereby deprives the VPLI neurone of its major synaptic input. We present evidence that histamine plays an important role in the EOP–DI–VPLI pathway. Histamine mimics the EOP-mediated inhibition of the DI, and the H2-specific histamine antagonists cimetidine and ranitidine block its inhibitory action. Histamine application to various areas of the brain localises the area where histaminergic inhibition occurs; this region is confined to the medial protocerebrum. At least six bilaterally paired histamine-like immunoreactive neurones send axonal projections into this area. Depolarisation of the brain region containing the soma of these neurones with high-K+ saline deactivates the VPLI neurone through the removal of the DI excitatory synaptic input.
The Trap-Jaw Mechanism in The Dacetine Ants Daceton Armigerum and Strumigenys Sp.
Authors: Gronenberg Wulfila 
Published: April 2021

ABSTRACT
Ants of three different subfamilies, among them the tribe Dacetini, have evolved very fast snapping mandibles called trap-jaws. The two dacetine genera examined, the large Daceton and the small Strumigenys, employ the same mechanism for their mandible strike. Video analysis reveals that, in Strumigenys sp., the strike takes less than 2.5 ms. It is released within 5 ms by contact of trigger hairs on the labrum. The ants employ a catapult mechanism to generate such a fast movement. Before the strike, the mandibles are opened wide and locked in the open position by the labrum, which functions as a latch. They stay open even when the large slow closer muscles contract. Upon trigger hair stimulation, the labrum is pulled backwards by a small, fast trigger muscle. The mandibles are thus freed from the catch and close rapidly. This reflex is controlled by giant sensory and motor neurones in the labral neuromere that are probably monosynaptically coupled. The short latency of the reflex thus results from the combination of a catapult mechanism, fast trigger muscles, high neuronal conduction velocities and small synaptic delays. Comparison with the trap-jaw mechanism of the ant genus Odontomachus reveals a remarkable example of convergent evolution.
Homing Experiments on Pigeons Subjected To Bilateral Destruction Of The Paratympanic Organ
Authors: Giannessi F. , Fattori B. , Ruffoli R. , Gagliardo A. 
Published: April 2021

ABSTRACT
The paratympanic organ (PO) in birds is a specialised sensory organ whose function is still unknown. G. Vitali, who first described the PO from observations of the behaviour of PO-lesioned pigeons, proposed that this organ was needed to maintain normal wing muscle function and called it the ‘organ of flight’. This interpretation has since been disputed. To solve this controversy and to test whether the PO is involved in flight and navigation, we performed release tests on homing pigeons subjected to bilateral destruction of this organ. No impairment of either flight or navigation was observed in the lesioned pigeons.
Effects of Hypoxia and Hyperoxia on Oxygen-Transfer Properties of the Blood of a Viviparous Snake
Authors: Herman Jay K. , Ingermann Rolf L. 
Published: April 2021

ABSTRACT
Red cell oxygen affinity, red cell nucleoside triphosphate (NTP) levels and blood oxygen-carrying capacity were determined for male, nonpregnant and pregnant female, and fetal garter snakes Thamnophis elegans exposed to hypoxia (5 % oxygen) and hyperoxia (100 % oxygen). Male and nonpregnant female snakes were maintained under these conditions for up to 3 weeks and exhibited an apparent maximal change in oxygen affinity after 14 days of hypoxia and hyperoxia. Red cell NTP levels decreased and oxygen affinity increased with exposure to hypoxia, while exposure to hyperoxia promoted an increase in red cell NTP concentrations and a decrease in red cell oxygen affinity in the males. Hyperoxia-exposed nonpregnant females did not show a significant change in oxygen affinity. After 14 days of hypoxia, the pregnant females showed an increase in red cell oxygen affinity which was associated with a decrease in red cell NTP concentration and in the molar ratio of NTP/hemoglobin relative to normoxic controls. Fourteen days of hyperoxia did not result in a change in oxygen affinity of red cells from the pregnant female, but did promote a slight increase red cell NTP concentrations. The blood parameters of fetuses from females exposed to hypoxia or hyperoxia did not differ from those of normoxic control fetuses. The fetuses of females exposed to hypoxia suffered greater mortality, appeared less developed and had a lower average wet mass than the fetuses of normoxic-and hyperoxic-exposed females. Neither hypoxia nor hyperoxia altered the oxygen-carrying capacity of the blood in any group of snake.
Effects Of Antifreeze Proteins on Red Blood Cell Survival During Cryopreservation
Authors: Chao Heman , Davies Peter L. , Carpenter John F. 
Published: April 2021

ABSTRACT
Antifreeze protein (AFP) types I, II and III were tested for their ability to protect red blood cells from lysis during warming, after cryopreservation in hydroxyethyl starch. All three types reduced hemolysis to 25 % of control values at similar micromolar concentrations but enhanced lysis as the AFP concentration approached millimolar levels. Site-directed mutants of type III AFP with different thermal hysteresis activities were tested for their ability to protect the cryopreserved cells from lysis. Their relative efficacy in protecting the cells correlated closely with their thermal hysteresis activity. Cryomicroscopy indicated that the protection of red cells by type III AFP and the mutant forms was due to inhibition of ice recrystallization.
Polarization Vision in Cuttlefish – A Concealed Communication Channel?
Authors: Shashar Nadav , Rutledge Phillip S. , Cronin Thomas W. 
Published: April 2021

ABSTRACT
Polarization sensitivity is well documented in marine animals, but its function is not yet well understood. Of the cephalopods, squid and octopus are known to be sensitive to the orientation of polarization of incoming light. This sensitivity arises from the orthogonal orientation of neighboring photoreceptors. Electron microscopical examination of the retina of the cuttlefish Sepia officinalis L. revealed the same orthogonal structure, suggesting that cuttlefish are also sensitive to linearly polarized light. Viewing cuttlefish through an imaging polarized light analyzer revealed a prominent polarization pattern on the arms, around the eyes and on the forehead of the animals.
The polarization pattern disappeared when individuals lay camouflaged on the bottom and also during extreme aggression display, attacks on prey, copulation and egg-laying behavior in females. In behavioral experiments, the responses of cuttlefish to their images reflected from a mirror changed when the polarization patterns of the reflected images were distorted. These results suggest that cuttlefish use polarization vision and display for intraspecific recognition and communication.
Sulfide Acquisition By The Vent Worm Riftia Pachyptila Appears To Be Via Uptake Of Hs−, Rather Than H2S
Authors: Goffredi Shana K. , Childress James J. , Desaulniers Nicole T. , Lallier Francois H. 
Published: April 2021

ABSTRACT
Deep-sea hydrothermal vents are home to a variety of invertebrate species, many of which host chemosynthetic bacteria in unusual symbiotic arrangements. The vent tubeworm Riftia pachyptila (Vestimentifera) relies upon internal chemolithoautotrophic bacterial symbionts to support its large size and high growth rates. Because of this, R. pachyptila must supply sulfide to the bacteria, which are far removed from the external medium. Internal ΣH2S ([H2S+HS−+S2−]) can reach very high levels in R. pachyptila (2–12 mmol l−1 in the vascular blood), most of which is bound to extracellular hemoglobins. The animal can potentially take up sulfide from the environment via H2S diffusion or via mediated uptake of HS−, or both. It was expected that H2S diffusion would be the primary sulfide acquisition mechanism, paralleling the previously demonstrated preferential uptake of CO2. Our data show, however, that the uptake of HS− is the primary mechanism used by R. pachyptila to obtain sulfide and that H2S diffusion into the worm apparently proceeds at a much slower rate than expected. This unusual mechanism may have evolved because HS− is less toxic than H2S and because HS− uptake decouples sulfide and inorganic carbon acquisition. The latter occurs via the diffusion of CO2 at very high rates due to the maintenance of an alkaline extracellular fluid pH. ΣH2S accumulation is limited, however, to sulfide that can be bound by the hemoglobins, protecting the animal from sulfide toxicity and the symbionts from sulfide inhibition of carbon fixation.
Why Do Tuna Maintain Elevated Slow Muscle Temperatures? Power Output Of Muscle Isolated From Endothermic And Ectothermic Fish
Authors: Altringham John D. , Block Barbara A. 
Published: April 2021

ABSTRACT
It has been hypothesised that regional endothermy has evolved in the muscle of some tunas to enhance the locomotory performance of the fish by increasing muscle power output. Using the work loop technique, we have determined the relationship between cycle frequency and power output, over a range of temperatures, in isolated bundles of slow muscle fibres from the endothermic yellowfin tuna (Thunnus albacares) and its ectothermic relative the bonito (Sarda chiliensis). Power output in all preparations was highly temperature-dependent. A counter-current heat exchanger which could maintain a 10 °C temperature differential would typically double maximum muscle power output and the frequency at which maximum power is generated (fopt). The deep slow muscle of the tuna was able to operate at higher temperatures than slow muscle from the bonito, but was more sensitive to temperature change than more superficially located slow fibres from both tuna and bonito. This suggests that it has undergone some evolutionary specialisation for operation at higher, but relatively stable, temperatures. fopt of slow muscle was higher than the tailbeat frequency of undisturbed cruising tuna and, together with the high intrinsic power output of the slow muscle mass, suggests that cruising fish have a substantial slow muscle power reserve. This reserve should be sufficient to power significantly higher sustainable swimming speeds, presumably at lower energetic cost than if intrinsically less efficient fast fibres were recruited.
A Physiological Evaluation Of Carbon Sources For Calcification In The Octocoral Leptogorgia Virgulata (Lamarck)
Authors: Lucas Jared M. , Knapp Loren W. 
Published: April 2021

ABSTRACT
The union of calcium cations with carbonate anions to form calcium carbonate (CaCO3) is a fundamentally important physiological process of many marine invertebrates, in particular the corals. In an effort to understand the sources and processes of carbon uptake and subsequent deposition as calcium carbonate, a series of studies of the incorporation of 14C-labeled compounds into spicules was undertaken using the soft coral Leptogorgia virgulata. It has been surmised for some time that dissolved inorganic carbon in sea water is used in the biomineralization process. Furthermore, it was suspected that metabolically generated CO2 is also available for calcification. As a means of testing these possible sources of carbon in spicule calcification, key enzymes or transport systems in each pathway were inhibited. First, the enzyme carbonic anhydrase was specifically inhibited using acetazolamide. Second, the active transport of bicarbonate was inhibited using DIDS (4,4′-diisothiocyanato-stilbene-2,2′-disulfonic acid). Third, CO2 generation resulting from glycolysis and the citric acid cycle was arrested using iodoacetic acid, which interferes specifically with the enzyme glyceraldehyde-3-phosphate dehydrogenase. The results indicate that dissolved CO2 is the largest source of carbon used in the formation of calcitic sclerites, followed by HCO3− from dissolved inorganic carbon. In L. virgulata, the dissolved inorganic carbon is responsible for approximately 67 % of the carbon in the sclerites. The other 33 % comes from CO2 generated by glycolysis. Two important conclusions can be drawn from this work. First, carbon for spiculogenesis comes not only from dissolved inorganic carbon in the environment but also from metabolically produced carbon dioxide. While the latter has been theorized, it has never before been demonstrated in octocorals. Second, regardless of the carbon source, the enzyme carbonic anhydrase plays a pivotal role in the physiology of spicule formation in Leptogorgia virgulata.
Light-induced and circadian changes in the compound eye of the haematophagous bug Triatoma infestans (Hemiptera: Reduviidae)
Authors: Reisenman Carolina E. , Insausti Teresita C. , Lazzari Claudio R. 
Published: April 2021

SUMMARY
We analysed dynamic changes in the ommatidial structure of the compound eyes of Triatoma infestans. This nocturnal insect possesses open-rhabdom eyes, in which a ring of six rhabdomeres from retinula cells 1–6 (R1–6) surrounds a central pair of rhabdomeres from retinula cells 7 and 8 (R7–8). Screening pigments are located in all the photoreceptors and in the primary (PPC) and secondary (SPC) pigment cells. During the day, pigments within R1–6 and the PPCs form a small ‘pupil’ above the rhabdom and pigments within R7–8 are clustered around the central rhabdomere, allowing light to reach only the central rhabdomere. At night, the ‘pupil’ widens, and pigments inside R7–8 concentrate in the proximal region of the cells, allowing light to reach the peripheral rhabdomeres. In addition, the distance between the cornea and the rhabdom decreases. These rhythmic changes adapt the sensitivity of the eye by controlling the amount of light reaching and travelling within the rhabdom. Furthermore, the rhythm persists under conditions of constant darkness (DD), i.e. it is controlled by an endogenous oscillator. Remarkably, there are differences in pigment movements between the retinula cells of a single ommatidium. The migration of pigments in R1–6 is regulated by a circadian input, while that in R7–8 is regulated by both direct light and circadian inputs. The rhythm vanishes under constant-light conditions (LL). In this species, the circadian rhythm of photonegative behaviour persists in both DD and LL conditions, suggesting that these two rhythms, in retinal morphology and visual behaviour, may be generated by different circadian oscillators.