bluuebunny/crossref_metadata_2025_split huggingface dataset:
Odorant Intensity as a Determinant for Olfactory Conditioning in Honeybees: Roles in Discrimination, Overshadowing and Memory Consolidation
Authors: Pelz Corinna , Gerber Bertram , Menzel Randolf 
Published: April 2021

ABSTRACT
Stimulus intensity is an important determinant for perception, learning and behaviour. We studied the effects of odorant concentration on classical conditioning involving odorants and odorant-mechanosensory compounds using the proboscis-extension reflex in the honeybee.
Our results show that high concentrations of odorant (a) support better discrimination in a feature-positive task using rewarded odorant-mechanosensory compounds versus unrewarded mechanosensory stimuli, (b) have a stronger capacity to overshadow learning of a simultaneously trained mechanosensory stimulus, and (c) induce better memory consolidation. Furthermore, honeybees were trained discriminatively to two different concentrations of one odorant. Honeybees are not able to solve this task when presented with rewarded low versus unrewarded high concentrations.
Taken together, our results suggest that high concentrations of odorant support stronger associations (are more ‘salient’) than low concentrations. Our results, however, do not indicate that honeybees can treat two different concentrations of one odorant as qualitatively different stimuli. These findings fill a gap in what is known about honeybee olfactory learning and are a first step in relating behaviour to recent advances in the physiological analysis of coding for odorant concentration in honeybees.
Thermally Induced Changes in Intracellular pH and Modulators of Phosphofructokinase in Trout White Muscle
Authors: Lehoux Eric A. , Guderley Helga E. 
Published: April 2021

ABSTRACT
The intracellular pH (pHi) and the concentrations of lactate and selected modulators of phosphofructokinase (PFK; EC 2.7.1.11) were measured in white epaxial muscle of 15 °C-acclimated rainbow trout (Oncorhynchus mykiss) maintained at 8, 15 or 22 °C for 48 h and sampled at rest and after 10 min of exhaustive exercise. The lactate accumulation resulting from exercise was 13 % smaller at 22 °C than at 8 and 15 °C. The estimated duration of burst performance was shorter at cold than at warm temperatures, whereas the average rate of lactate accumulation during burst performance was higher at 8 °C than at 15 and 22 °C. pHi rose when temperature decreased, but less than predicted by the imidazole alphastat hypothesis of Reeves. The effects of temperature on the pre-exercise concentrations of PFK modulators [adenylates, fructose 6-phosphate (F6P) and fructose 1,6-bisphosphate (FBP)] were generally negligible. In exhausted trout, adenylate concentrations were almost unaffected by temperature. In contrast, post-exercise FBP and F6P concentrations were significantly higher at low than at high temperatures. We interpret the response of F6P to temperature as an indication that the covariation of pHi and temperature is insufficient to prevent a cold-enhancement of PFK inhibition. Since F6P is a potent activator of PFK, we conclude that, in trout white muscle, thermally induced changes in F6P concentration probably help buffer the effects of temperature change on PFK activity.
Possible Mediation of G-Proteins in Cold-Sensory Transduction in Paramecium Multimicronucleatum
Authors: Nakaoka Yasuo , Tanaka Tohru , Kuriu Toshihiko , Murata Tomohisa 
Published: April 2021

ABSTRACT
The possible involvement of G-proteins in cold-sensory transduction was examined using voltage-clamped Paramecium multimicronucleatum into which non-hydrolyzable guanosine nucleotide analogues had been applied intracellularly. Guanosine-5′-O-3-thiotriphosphate, guanosine-5′-O-2-thiodiphosphate and aluminium fluoride all reduced the transient inward current in response to cooling, suggesting the possibility that G-proteins mediate cold-sensory transduction. Internal application of a Ca2+ chelator, EGTA, also reduced the current response. In addition to their effect on reducing the cold-sensory response, application of these chemicals modulated both the resting potential and the membrane conductance. Possible correlations between G-protein activity and the regulation of intracellular Ca2+ levels are discussed.
Local Interneurons Define Functionally Distinct Regions Within Lobster Olfactory Glomeruli
Authors: Wachowiak M. , Diebel C. E. , Ache B. W. 
Published: April 2021

ABSTRACT
Whole-cell recording coupled with biocytin injection revealed four types of interneurons intrinsic to the olfactory lobe (OL) of the spiny lobster Panulirus argus. Each type of neuron had a distinct pattern of arborization within the three anatomically defined regions of OL glomeruli (cap, subcap and base). Type I interneurons innervated all three regions, while types II, III and IV branched only in the cap, subcap and base, respectively. Type I interneurons responded to electrical stimulation of the antennular (olfactory) nerve with a burst of 1–20 action potentials and a 1–10 s depolarization. Type II (cap) interneurons responded to the same input with a burst of 1–3 action potentials followed by a shorter hyperpolarization. Type III (subcap) interneurons responded with a burst of 1–6 action potentials followed by a delayed, 0.5–4 s depolarization. Type IV (base) interneurons responded with a brief depolarization or a burst of 1–3 action potentials followed by a 1 s hyperpolarization. The regionalized arborization and the different response properties of the type II, III and IV interneurons strongly imply that lobster olfactory glomeruli contain functionally distinct regions, a feature that should be useful in understanding the multiple synaptic pathways involved in processing olfactory input.
Recovery after Contraction of White Muscle Fibres from the Dogfish Scyliorhinus Canicula
Authors: Curtin N. A. , Kushmerick M. J. , Wiseman R. W. , Woledge R. C. 
Published: April 2021

ABSTRACT
Recovery after contraction of white muscle fibres of dogfish was investigated using 31P-NMR and measurements of heat production. The muscle fibres were stimulated to perform either a single isometric tetanus or a series of brief isometric tetani; the NMR measurements showed that approximately half of the phosphocreatine (PCr) was used. The period of activity was followed by a recovery period without stimulation.
Both NMR and heat measurements agreed in showing that recovery was very slow, requiring at least 60 min for PCr resynthesis and for the production of recovery heat. The NMR results showed that changes in intracellular pH and in the concentrations of PCr and intracellular phosphate (Pi) had very similar time courses. Intracellular pH moved in the alkaline direction during the period of activity and then returned monotonically during recovery. The non-phosphate buffer power was 13.0±3.1 mmol l−1 intracellular water per pH unit (N=4, mean ± S.E.M.).
The results are consistent with the view that oxidative processes resynthesize PCr during recovery, which is slow because of the low mitochondrial content of these muscle fibres.
Central Nervous Processing of Sex Pheromones in Two Strains of the European Corn Borer Ostrinia Nubilalis (Lepidoptera: Pyralidae)
Authors: Anton Sylvia , Löfstedt Christer , Hansson Bill S. 
Published: April 2021

ABSTRACT
Antennal lobe neurones were investigated in the pyralid moth Ostrinia nubilalis using intracellular recording and staining techniques. Response characteristics of antennal lobe neurones from males in the so-called E and Z strains, in F1 hybrids and in parental backcrosses were studied. The antennal lobe of a male O. nubilalis comprises approximately 30 ordinary glomeruli and three enlarged glomeruli making up the macroglomerular complex (MGC). Receptor neurones enter the antennal lobe via the antennal nerve and arborize in single glomeruli. Intracellularly stained, pheromone-responding projection neurones in both parental strains arborized in different glomeruli within the MGC, irrespective of their response characteristics. Neurones were grouped according to their specificity to single pheromone components and to pheromone blends. Component-specific, blend-specific and generalist neurones were found. Specificity only occurred at low stimulus concentrations and disappeared as concentrations increased. Although all neuronal types were present in both pheromone strains and crossings, differences in abundance and sensitivity were found. In the parental strains, neurones responding to the major pheromone component and to the respective strain-specific blend were more abundant than neurones responding to the minor component and the blend produced by the other strain. Neurones investigated in Z×E hybrids responded similarly to those of E-strain males, whereas neurones in EZ×Z paternal backcrosses responded similarly to those of Z males. In the hybrids and paternal backcrosses, hybrid-blend-specific neurones were present that were not found in parental-strain males.
Stability Of Nucleoside Triphosphate Levels In The Red Cells Of The Snake Thamnophis Elegans
Authors: Ingermann Rolf L. , Bencic David C. , Herman Jay K. 
Published: April 2021

ABSTRACT
Nucleated red cells in the nonpregnant garter snake (Thamnophis elegans) contain relatively high concentrations of nucleoside triphosphate (NTP), largely in the form of ATP, which is found at concentrations of approximately 10 mmol l− 1 relative to cell volume and 15 mmol l− 1 relative to cell water. During pregnancy, levels of NTP in adult red cells rise by approximately 50 % concomitant with an increase in blood progesterone level. The stability of the NTP pool within these red cells was assessed by maintaining cells in vitro at 20 °C, without exogenous nutrients, and in the presence and absence of the metabolic inhibitors iodoacetate and/or cyanide. After 96 h, NTP levels in adult red cells not exposed to the inhibitors had decreased by only approximately 10 %, while in the presence of both inhibitors NTP levels had fallen by less than 50 %. Red cell NTP levels were not affected by acute exposure to high concentrations of progesterone either in vivo or in vitro. NTP levels were much more labile when the cells were maintained in vitro at either low or high pH. Maintenance of red cells at pH 6.0 for 24 h resulted in a decrease in NTP levels of approximately 50 % and at pH 10.0 the levels fell by approximately 80 %, while buffers containing only ATP caused no detectable degradation. Incubation at low or high pH promoted some cell swelling; however, the magnitude of the decreases in intracellular NTP concentration prompted by these pH levels could not be mimicked by incubation of red cells in hypotonic buffer. Total nonspecific ATPase activity at pH 6.0 was approximately 55 % greater than that at pH 7.4, while at pH 10.0 it was approximately 6 % of that at pH 7.4. The pH-dependent decrease in intracellular NTP levels cannot, therefore, be due to stimulation of ATPase activity, at least not at high pH. Overall, the data are consistent with the hypothesis that an appreciable portion of the NTP within these cells is compartmentalized in a stable, but pH-sensitive, pool sequestered from intracellular ATP-hydrolyzing processes.
Locomotion in the Abalone Haliotis Kamtschatkana: Pedal Morphology and Cost of Transport
Authors: Donovan Deborah A. , Carefoot Thomas H. 
Published: April 2021

ABSTRACT
Morphological analyses of pedal sole area and pedal waves were conducted for a range of speeds and body sizes in the abalone Haliotis kamtschatkana. The pedal sole of resting abalone increased in size disproportionately with animal volume (slope of log10-transformed data, b=0.83; expected slope for isometry, b0=0.67) and length (b=2.51; b0=2.0). Pedal wave frequency increased linearly with speed, confirming that abalone increase speed by increasing the velocity of pedal waves. Total area of the pedal sole decreased by 2.1 % for each shell length per minute increase in speed. Likewise, the area of the foot incorporated into pedal waves increased by 1.8 % for each shell length per minute increase in speed. Together, these changes translated into a 50 % decrease in the pedal sole area in contact with the substratum at a maximum escape speed of 15 shell lengths min−1, relative to the pedal sole at rest. The amount of mucus secreted by resting animals during adhesion to the substratum increased isometrically with foot area (slope of log10-transformed data, b=1.08). The amount of mucus secreted during locomotion did not vary with speed, but was less than the amount needed for adhesion. We suggest that these morphological and physiological changes reduce the energy expenditure during locomotion. Cost of transport was investigated for a range of speeds and abalone sizes. The rate of oxygen consumption (in μl O2 g−1 h−1) increased linearly with increasing absolute speed v (in cm min−1): =40.1+0.58v−0.15m (r2=0.35, P=0.04), where m is body mass (in g). Minimum cost of transport, calculated from the slope of absolute speed on , was 20.3 J kg−1 m−1. Total cost of transport (COTT) and net cost of transport (COTN) were high at low speeds and decreased as speed increased, to minima of 86.0 J kg−1 m−1 and 29.7 J kg−1 m−1, respectively, at speeds measured in the respirometer. Log10-transformation of both cost of transport and speed data yielded linear relationships with the following regression equations: log10COTT=3.35−0.90log10v−0.21log10m (r2=0.89; P&lt;0.006) and log10COTN=2.29−0.69log10v−0.09log10m (r2=0.48; P&lt;0.006), respectively.
Power Output From a Flight Muscle of the Bumblebee Bombus Terrestris : I. Some Features of the Dorso-Ventral Flight Muscle
Authors: Josephson Robert K. , Ellington C. P. 
Published: April 2021

ABSTRACT
Isometric contractions from the asynchronous dorso-ventral flight muscle of the bumblebee Bombus terrestris were slow and rather weak. The twitch duration (onset to 50 % relaxation) was approximately 300 ms at 30 °C and 170 ms at 40 °C. The maximum tetanic tension was approximately 40 kN m−2; the ratio of twitch force to tetanic force was approximately 0.2. The unstimulated muscle was quite resistant to stretch, with a low-frequency stiffness of 730 kN m−2 at muscle lengths close to that of the muscle in vivo. The length–tension curve for active tetanic tension (that is the increase in tension above the passive level during stimulation) was very narrow, with a half-width equal to only 17 % of the optimal length. The muscle strain during tethered flight was approximately 2 % peak-to-peak, occasionally reaching 3 %. Strain amplitude increased with wing stroke frequency. The thoracic vibration frequency of escape buzzing, during which the wings are not extended but are folded over the abdomen, was approximately twice that of tethered flight but the muscle strain was similar to that of flight.
Honeybee Flight Muscle Phosphoglucose Isomerase: Matching Enzyme Capacities to Flux Requirements at a Near-Equilibrium Reaction
Authors: Staples James F. , Suarez Raul K. 
Published: April 2021

ABSTRACT
In honeybee flight muscle, there are close matches between physiological flux rates and the maximal activities (Vmax; determined using crude homogenates) of key enzymes catalyzing non-equilibrium reactions in carbohydrate oxidation. In contrast, phosphoglucose isomerase (PGI), which catalyzes a reaction believed to be close to equilibrium, occurs at Vmax values greatly in excess of glycolytic flux rates. In this study, we measure the Vmax of flight muscle PGI, the kinetic parameters of the purified enzyme, the apparent equilibrium constants for the reaction and the tissue concentrations of substrate and product. Using the Haldane equation, we estimate that the forward flux capacity (Vf) for PGI required to achieve physiological glycolytic flux rates is between 800 and 1070 units ml−1 cell water, approximately 45–60 % of the empirically measured Vmax of 1770 units ml−1 cell water at optimal pH (8.0) and low ionic strength (no added KCl). When measured at physiological pH (7.0) and ionic strength (120 mmol l−1 KCl) with saturating levels of substrate, PGI activity is 1130 units ml−1 cell water, a value close to the calculated Vf. These results reveal a very close match between predicted and measured PGI flux capacities, and support the concept of an economical design of muscle metabolism in systems working at very high metabolic rates.
Contraction Kinetics of Red Muscle in Scup: Mechanism for Variation in Relaxation Rate Along the Length of the Fish
Authors: Swank Douglas M. , Zhang Guixin , Rome Lawrence C. 
Published: April 2021

ABSTRACT
We studied possible mechanisms for the twofold difference in red muscle relaxation times between the posterior (207.2 ms) and anterior (98.4 ms) musculature of scup Stenotomus chrysops, which has been shown to have a large effect on power generation during swimming. This difference was not due to contamination of the anterior bundles with faster fiber types, as histological examination showed that all bundles contained more than 98.9 % red fibers. Further, maximum velocities of shortening (Vmax) at 20 °C were nearly identical, 5.37 ML s−1 (where ML is muscle length) for the anterior musculature and 5.47 ML s−1 for the posterior musculature, suggesting that the difference in relaxation times was not due to a difference in the crossbridge detachment rates associated with different myosin isoforms. The possibility of differences in the Ca2+ pumping rate influencing relaxation rate was explored using cyclopiazonic acid (CPA), a sarcoplasmic reticulum (SR) Ca2+-ATPase inhibitor. The concentration of CPA could be adjusted to slow the relaxation rate of an anterior muscle to that of a posterior muscle. However, SDS gels showed no difference in the intensity of SR Ca2+-ATPase protein bands between muscle positions. These results suggest that differences in the Ca2+ pumping could account for the observed difference in relaxation rate, but do not support the simplest hypothesis that the difference in relaxation rates is due to differences in numbers of Ca2+ pumps. Other possible mechanisms for this difference are explored.
Release of Atrial Natriuretic Factor Prohormone Peptides 1-30, 31-67 And 99-126 From Freshwater- and Seawater-Acclimated Perfused Trout (Oncorhynchus Mykiss) Hearts
Authors: Cousins K. L. , Farrell A. P. , Sweeting R. M. , Vesely D. L. , Keen J. E. 
Published: April 2021

ABSTRACT
Atrial natriuretic factor (ANF), a 28-amino-acid peptide hormone produced in the heart, circulates in both freshwater and seawater rainbow trout. In mammals, two other peptide hormones, proANF 1-30 and proANF 31-67, derived from the same 126-amino-acid prohormone as ANF (amino acids 99–126), circulate and have natriuretic and diuretic properties. It has never been determined whether these peptides circulate in fish. The present investigation was designed to determine (1) whether proANF 1-30 and/or proANF 31-67 circulate in perfused hearts from freshwater- and seawater-acclimated rainbow trout (Oncorhynchus mykiss) in situ, and (2) if they do, to determine whether increasing the filling pressure of the heart causes their release in trout as it does in mammals. High-performance gel-permeation chromatography of fish plasma revealed that both proANF 1-30 and 31-67 circulate in freshwater- and seawater-acclimated trout plasma at threefold higher concentrations than does ANF. The basal rates of release of ANF and proANF 1-30 and 31-67 were similar in both freshwater and seawater trout, with the rate of release of proANF 1-30 being 10 times higher and that of proANF 31-67 20 times higher than that of ANF. When the filling pressure was increased to the peak of the Starling curve (Q̇max), the rate of release of ANF and proANFs 1-30 and 31-67 increased fivefold for each peptide in the freshwater trout, while in seawater trout the rates of release increased six-to ninefold. We conclude that proANF 1-30 and 31-67, as well as ANF, circulate in both freshwater-and seawater-acclimated trout and do so at concentrations higher than that of ANF. Increasing the filling pressure to the trout heart was found to cause a similar increase in the release rates for each of these peptides, but the maximal increase was higher in the seawater-acclimated trout, apparently because they showed a larger increase in cardiac output.
Coordination of Respiratory Cycles With Wingbeat Cycles in the Black-Billed Magpie (Pica Pica)
Authors: Boggs D. F. , Seveyka J. J. , Kilgore D. L. , Dial K. P. 
Published: April 2021

ABSTRACT
Magpies fly with a variable pattern of wingstroke, including high-amplitude rapid flaps and low-amplitude slower flaps with interspersed brief glides. This allowed us to test the hypothesis that if phasic coordination between respiratory and wingbeat cycles is important mechanically and energetically, then, as a bird changes its wingbeat cycle, its respiratory cycle should change with it. We also tested the strength of the drive to coordinate respiratory to locomotor cycles by stimulating breathing with 5 % CO2 during flight. We found that magpies (N=5) do shorten their breath cycle time when they shorten their wingbeat cycle time and prolong their breath cycle time when they glide. When the coordination ratio of wingbeat cycles to breaths is 3:1, the pattern of phasic coordination ensures two upstrokes per inspiration and two downstrokes per expiration. Upstroke tends to coincide with the transition into inspiration or with early inspiration and late inspiration. Downstroke tends to coincide with the transition into expiration or with early expiration and late expiration. When magpies switch from a 3:1 ratio to a 2:1 ratio of wingbeat cycles to breaths, they shorten inspiratory time to ensure that upstroke occurs through most of inspiration and downstroke corresponds to the transition into expiration. These phasic coordination patterns ensure that the compression of the airsacs during downstroke can provide a net assistance to expiration and that the expansion of the airsacs with upstroke can provide a net assistance to inspiration. The failure of an atmosphere containing 5 % CO2 to disrupt these phasic coordination patterns between respiratory and locomotory cycles suggests that there may be a potent mechanical and energetic benefit to such coordination.