bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction Between Haemoglobin and Synthetic Peptides of the N-Terminal Cytoplasmic Fragment of Trout Band 3 (AE1) Protein
Authors: Jensen Frank B. , Jakobsen Mogens H. , Weber Roy E. 
Published: April 2021

ABSTRACT
Two acidic peptides corresponding to the first 10 and 20 amino acid residues of the N-terminal, cytoplasmic fragment of rainbow trout band 3 (AE1) protein were synthesised in order to study their interaction with trout and human haemoglobin (Hb). The peptides did not influence the oxygen affinity of the main anodic trout Hb component (Hb IV) when tested at surplus peptide concentration ([peptide]/[Hb4]=16), at high and low ionic strength and at pH values ranging from 6.5 to 7.6. With human Hb, however, the 20-mer peptide markedly decreased the oxygen affinity and increased the Bohr effect. These data suggest that the trout band 3 peptide binds preferentially to the deoxy (T) conformation of human Hb, probably at the organic phosphate binding site in the central cavity between the β-chains, which is known to be the binding site for the acidic N terminus of human band 3. In trout Hb IV, the presence of negatively charged Asp at position NA2 of the β-chains (in contrast to positive or neutral residues in mammalian Hb) may weaken any interaction with the highly negatively charged peptides.
Effects of Temperature, Adrenaline and Ryanodine on Power Production in Rainbow Trout Oncorhynchus Mykiss Ventricular Trabeculae
Authors: Shiels H. A. , Stevens E. D. , Farrell A. P. 
Published: April 2021

ABSTRACT
This study is the first to examine the contractility of teleost ventricular muscle in an oscillating muscle preparation. The experiments were designed to test the relative importance of Ca2+ released from the sarcoplasmic reticulum (SR) and Ca2+ influx across the sarcolemma (SL) to cardiac performance in rainbow trout Oncorhynchus mykiss. Adrenaline and ryanodine were used to modulate Ca2+ flux through the SL and SR, respectively. Experiments were conducted at two temperatures (12 °C and 22 °C) (1) to investigate the effect of an acute temperature change (from 12 °C to 22 °C) on power production, and (2) to test the effects of acute temperature change on the relative contributions of the SR and SL Ca2+ flux to power production. Concordant with isometric studies, the results showed that trans-sarcolemmal influx was the major source of Ca2+ (approximately 90 %) for cardiac power production at all temperatures. This SL Ca2+ influx was increased with adrenergic stimulation. The power curves generated in this study suggest an optimum frequency for power production of approximately 1.0 Hz at 12 °C, which corresponds well to typical in vivo heart rates for rainbow trout at that temperature. Further, this study indicated that temperature-induced changes in power output cannot be predicted from temperature-induced changes in isometric tension because the temperature-sensitivity of work and power proved to be greater than that of isometric tension. This finding is important because many previous studies have assessed cardiac contractility using only isometric tension.
Energetics Of Bipedal Running II. Limb Design and Running Mechanics
Authors: Roberts Thomas J. , Chen Michael S. , Taylor C. Richard 
Published: April 2021

ABSTRACT
Compared with quadrupeds, bipedal runners of the same weight have longer legs, take longer steps and can presumably use slower, more economical muscle fibers. One might predict that bipedal running is less expensive, but it is not. We hypothesized that bipeds recruit a larger volume of muscle to support their weight, eliminating the potential economy of longer legs and slower steps. To test our hypothesis, we calculated the relative volume of muscle needed to support body weight over a stride in small dogs (Canis familiaris) and wild turkeys (Meleagris gallopavo) of the same weight. First, we confirmed that turkeys and dogs use approximately the same amount of energy to run at the same speed, and found that turkeys take 1.8-fold longer steps. Higher muscle forces and/or longer muscle fibers would require a greater volume of active muscle, since muscle volume is proportional to the product of force and fascicle length. We measured both mean fascicle length and mean mechanical advantage for limb extensor muscles. Turkeys generated approximately the same total muscle force to support their weight during running and used muscle fascicles that are on average 2.1 times as long as in dogs, thus requiring a 2.5-fold greater active muscle volume. The greater volume appears to offset the economy of slower rates of force generation, supporting our hypothesis and providing a simple explanation for why it costs the same to run on two and four legs.
A Peritracheal Neuropeptide System In Insects: Release Of Myomodulin-Like Peptides At Ecdysis
Authors: O’brien Martha A. , Taghert PAul H. 
Published: April 2021

ABSTRACT
We identified of a set of neuropeptide-expressing cells sited along the respiratory system of Drosophila melanogaster using an antibody to the molluscan neuropeptide myomodulin. The number and positions of these ‘peritracheal’ myomodulin (PM) cells were reminiscent of the epitracheal Inka cells in the moth Manduca sexta. These Inka cells release the peptide ecdysis-triggering hormone, which helps elicit ecdysial behavior at the molt, and we show that they are also recognized by the myomodulin (MM) antibody. In both D. melanogaster and M. sexta, the PM and Inka cells are the only MM-positive cells outside the central nervous system. In both insects, MM immunoreactivity disappears at the end of the molt. In D. melanogaster, we have monitored the PM cells throughout development using two enhancer trap lines; the PM cells persist throughout development, but at larval, pupal and adult ecdyses, they display a loss of MM immunoreactivity. This transient loss occurs at a predictable time, just prior to ecdysis. In contrast, MM-positive neurons in the central nervous system do not show these changes. The PM cells also reveal a concomitant loss of immunostaining for an enzyme contained in secretory granules. The results are consistent with the hypothesis that the PM cells release MM-like peptides just prior to each ecdysis.
In addition, we demonstrate that peritracheal cells of five widely divergent insect orders show a myomodulin phenotype. The peritracheal cell size, morphology, numbers and distribution vary in these different orders. These data suggest that peritracheal cells release MM-like peptides as part of a conserved feature of the endocrine regulation of insect ecdysis.
Different Functions of Different Eye Types in the Spider Cupiennius Salei
Authors: Schmid Axel 
Published: April 2021

ABSTRACT
The Central American hunting spider Cupiennius salei Keys relies mainly on its mechanosensory systems during prey-catching and mating behaviour. The behavioural relevance of its eight eyes has not been studied before, although their optics and sensitivity suggest highly developed visual capabilities. The visual system was examined in a twofold simultaneous-choice experiment. Two targets were presented at a distance of 2 m from the animals, and their walking paths towards the targets were monitored. Spiders showed no preference when choosing between two identical targets, but when choosing between two different targets they strongly preferred a vertical bar to a sloping bar or a V-shaped target. By covering all eyes except the anterior median or posterior median eyes, it could be shown that the spiders were able to detect the targets using any of the eyes. Discrimination between different targets was only possible with the anterior median eyes uncovered, although the visual fields of the anterior median and posterior median eyes overlap completely. It seems most likely that the animals separate visual information in the periphery and therefore that the eyes have different functions. The posterior median eyes support a target-detecting mechanism and the anterior median eyes a target-discrimination mechanism.
Modelling Quantitative Structure–Activity Relationships Between Animal Behaviour And Environmental Signal Molecules
Authors: Browne Kenneth A. , Tamburri Mario N. , Zimmer-Faust Richard K. 
Published: April 2021

ABSTRACT
Quantitative structure–activity relationships (QSARs) between the physicochemical properties of environmental signal molecules and animal behaviour have been determined. Past work has shown that oyster and barnacle larval settlement and mud crab abdominal pumping (for larval dispersal) are stimulated by small peptide cues. In all the peptides examined that were active at ecologically relevant concentrations, arginine or lysine was found at the carboxy terminus, but the amino acids found at preceding positions were highly variable. We used the multivariate partial least squares algorithm to relate composite properties for the hydrophilicity, size and charge of each amino acid and the sequence position to oyster, barnacle and crab behaviour patterns. From the information in these QSAR models, the apparent variability in amino acid sequences eliciting behavioural responses was explained in each case, and more potent peptide analogues are hypothesized on the basis of untested amino acid sequences. Remarkably, these peptide signals are all structurally related to the carboxy-terminal sequence of mammalian C5a anaphylatoxin, a potent white blood cell chemoattractant. Even more striking is the fact that these different animal species should rely on apparently similar environmental signal molecules when residing within a common habitat (southeastern US estuaries). Through the physicochemical properties of amino acids, the current QSAR models clearly differentiate between the optimal sequences for eliciting oyster, barnacle and mud crab behaviour. Thus, QSARs provide a novel and powerful method not only for relating the physicochemical properties of molecules to animal behaviour but also for differentiating responses to chemicals by individuals of different species.
Morphological, Physiological and Metabolic Comparisons Between Runner-Like and Sheet-Like Inbred Lines of a Colonial Hydroid
Authors: Blackstone Neil W. 
Published: April 2021

ABSTRACT
Hydractiniid hydroids display a range of morphological variation from sheet-like forms (i.e. closely spaced polyps with high rates of stolon branching) to runner-like forms (i.e. widely spaced polyps with low rates of stolon branching), thus exemplifying the patterns of heterochrony found in many colonial animals. A sheet-like and a runner-like inbred line of Podocoryne carnea were produced to investigate this heterochronic variation further. Selection on colony morphology at the time of the initiation of medusa production resulted in dramatic differences by the F5 and F6 generations. Compared with colonies of the sheet-like inbred line, runner-like colonies exhibited smaller sizes at the initiation of medusa production, more irregular colony shapes and diminished stolon development relative to polyp development. In addition to these differences in colony morphology, runner-like colonies also exhibited larger medusae and a greater amount of gastrovascular flow to the peripheral stolons. To assess differences in the metabolic capacity underlying this variaton in flow, the redox state of the polyp epitheliomuscular cells was measured using the fluorescence of NAD(P)H. In response to feeding-induced changes in gastrovascular flow, runner-like colonies show greater redox variation than sheet-like ones, plausibly corresponding to the greater amounts of flow generated by the former colonies relative to the latter. Perturbing the system with dilute solutions of 2,4-dinitrophenol similarly indicates that runner-like colonies contain more functionally oxidizable NAD(P)H. The correlation between gastrovascular flow and morphological differences supports the hypothesis that the former mediates the timing of colony development, perhaps in concert with the observed variation in the redox state of polyp epitheliomuscular cells.
Mechanics of Lung Ventilation in a Larval Salamander Ambystoma Tigrinum
Authors: Brainerd Elizabeth L. 
Published: April 2021

ABSTRACT
The larval stage of the tiger salamander Ambystoma tigrinum is entirely aquatic, but the larvae rely on their lungs for a large proportion of their oxygen uptake. X-ray video and pressure measurements from the buccal and body cavities demonstrate that the larvae inspire using a two-stroke buccal pump and exhale actively by contracting the hypaxial musculature to increase body pressure. Larvae begin a breath by expanding the buccal cavity to draw in air through the mouth, while simultaneously exhaling air from the lungs to mix with the fresh air in the buccal cavity. The mouth then closes, and the buccal cavity compresses to pump a portion of the mixture into the lungs. The remaining air in the buccal cavity is then released as bubbles from the mouth and gill slits. Ventilatory volumes estimated from X-ray video records indicate that approximately 80 % of the air pumped into the lungs is fresh air and 20 % is previously expired air. Exhalation in larval tiger salamanders is active, powered by contraction of all four layers of lateral hypaxial musculature. Electromyography indicates that the transverse abdominis (TA) muscle is active for the longest duration and shows the highest-amplitude activity, but the external oblique superficialis, the external oblique profundus and the internal oblique also show consistent, low-level activity. The finding that the TA muscle is active during exhalation in larval tiger salamanders contributes to a growing body of evidence that the use of the TA for exhalation is a primitive character for tetrapods.
Determinants of the center of mass trajectory in human walking and running
Authors: Lee Cynthia R. , Farley Claire T. 
Published: April 2021

ABSTRACT
Walking is often modeled as an inverted pendulum system in which the center of mass vaults over the rigid stance limb. Running is modeled as a simple spring-mass system in which the center of mass bounces along on the compliant stance limb. In these models, differences in stance-limb behavior lead to nearly opposite patterns of vertical movements of the center of mass in the two gaits. Our goal was to quantify the importance of stance-limb behavior and other factors in determining the trajectory of the center of mass during walking and running. We collected kinematic and force platform data during human walking and running. Virtual stance-limb compression (i.e. reduction in the distance between the point of foot–ground contact and the center of mass during the first half of the stance phase) was only 26 % lower for walking (0.091 m) than for running (0.123 m) at speeds near the gait transition speed. In spite of this relatively small difference, the center of mass moved upwards by 0.031 m during the first half of the stance phase during walking and moved downwards by 0.073 m during the first half of the stance phase during running. The most important reason for this difference was that the stance limb swept through a larger angle during walking (30.4 °) than during running (19.2 °). We conclude that stance-limb touchdown angle and virtual stance-limb compression both play important roles in determining the trajectory of the center of mass and whether a gait is a walk or a run.
Relative contribution of quantitative and qualitative changes in mitochondria to metabolic compensation during seasonal acclimatisation of rainbow trout Oncorhynchus mykiss
Authors: St-Pierre Julie , Charest Pierre-Mathieu , Guderley Helga 
Published: April 2021

ABSTRACT
This study examined whether changes in the properties of mitochondria from red muscle of rainbow trout Oncorhynchus mykiss are accompanied by ultrastructural changes during cold acclimatisation. We compared measurements at five levels of organisation in red muscle of winter-(1 °C) and summer-(16 °C) acclimatised trout. We examined (1) maximal rates of pyruvate and palmitoyl carnitine oxidation by isolated mitochondria, (2) enzymatic activities [cytochrome c oxidase (CCO), citrate synthase (CS), carnitine palmitoyl transferase (CPT) and phosphofructokinase (PFK)] of the muscle and isolated mitochondria, (3) mitochondrial protein content in the muscle, (4) the ultrastructure of muscle fibres, and (5) the cristae surface density of the mitochondria. All variables were measured on each trout sampled. The mitochondria from winter-acclimatised trout possessed higher maximal capacities for the oxidation of pyruvate and palmitoyl carnitine than those from summer-acclimatised trout.
Muscle activities of CCO, CS and CPT were greater in winter than in summer trout, whereas the levels of PFK did not differ seasonally. Similarly, the mitochondria from winter trout had elevated levels of CCO, CS and CPT compared with those isolated from summer trout. The cristae surface density of the mitochondria from winter trout (40.2±0.6 μm2μm−3; mean ± S.E.M.) was significantly higher than that from summer trout (36.4±1.2 μm2 μm−3), whereas there was no difference in the mitochondrial volume densities of muscle fibres from winter and summer trout. Thus, the considerable compensation of muscle aerobic capacity at low temperatures in trout is not accompanied by changes in mitochondrial volume density, but rather by shifts in enzyme levels and cristae surface density.
INHIBITION OF MIDGUT ION TRANSPORT BY ALLATOTROPIN (Mas-AT) AND MANDUCA FLRFamides IN THE TOBACCO Hornworm MANDUCA SEXTA
Authors: Lee Kyeong-Yeoll , Horodyski Frank M. , Chamberlin M. E. 
Published: April 2021

ABSTRACT
Short-circuit current (Isc) across the posterior midgut of day 2 fifth-instar tobacco hornworms (Manduca sexta) is inhibited by Manduca allatotropin (Mas-AT) and two Manduca FLRFamides (F7G and F7D). Another FLRFamide, F10, and the related molluscan tetrapeptide FMRFamide elicited only a modest inhibition of Isc. Mas-AT, F7G and F7D inhibited the Isc in a dose-dependent manner. Maximal inhibition of Isc by Mas-AT was achieved at a concentration of 50 nmol l−1. At 100 nmol l−1, Mas-AT produced a significantly greater inhibition of Isc than did F7G and F7D. The inhibition caused by Mas-AT was reversed by removing the peptide. Furthermore, the action of Mas-AT could be blocked by preabsorption with its antiserum. When F7G or F7D was added after the Isc had been inhibited by Mas-AT, a further reduction in the Isc was observed. No additive effects were seen when F7G and F7D were added together. In comparison with the anterior and middle regions, the posterior section of the midgut was the most sensitive to these three peptides. The Isc of midguts dissected from feeding fourth instars was inhibited by Mas-AT, F7D and F7G, whereas the Isc of midguts dissected from pharate fifth instars or wandering fifth instars was virtually unaffected by these peptides. Active ion transport across the posterior midgut of the silk moths Hyalophora cecropia and Bombyx mori was unaffected by these peptides.
Self-propelled anguilliform swimming: simultaneous solution of the two-dimensional navier–stokes equations and Newton’s laws of motion
Authors: Carling John , Williams Thelma L. , Bowtell Graham 
Published: April 2021

ABSTRACT
Anguilliform swimming has been investigated by using a computational model combining the dynamics of both the creature’s movement and the two-dimensional fluid flow of the surrounding water. The model creature is self-propelled; it follows a path determined by the forces acting upon it, as generated by its prescribed changing shape. The numerical solution has been obtained by applying coordinate transformations and then using finite difference methods. Results are presented showing the flow around the creature as it accelerates from rest in an enclosed tank. The kinematics and dynamics associated with the creature’s centre of mass are also shown. For a particular set of body shape parameters, the final mean swimming speed is found to be 0.77 times the speed of the backward-travelling wave. The corresponding movement amplitude envelope is shown. The magnitude of oscillation in the net forward force has been shown to be approximately twice that in the lateral force. The importance of allowing for acceleration and deceleration of the creature’s body (rather than imposing a constant swimming speed) has been demonstrated. The calculations of rotational movement of the body and the associated moment of forces about the centre of mass have also been included in the model. The important role of viscous forces along and around the creature’s body and in the growth and dissolution of the vortex structures has been illustrated.
In Vivo Pectoralis Muscle Force–Length Behavior During Level Flight In Pigeons (Columba Livia)
Authors: Biewener Andrew A. , Corning William R. , Tobalske Bret W. 
Published: April 2021

ABSTRACT
For the first time, we report in vivo measurements of pectoralis muscle length change obtained using sonomicrometry combined with measurements of its force development via deltopectoral crest strain recordings of a bird in free flight. These measurements allow us to characterize the contractile behavior and mechanical power output of the pectoralis under dynamic conditions of slow level flight in pigeons Columba livia. Our recordings confirm that the pigeon pectoralis generates in vivo work loops that begin with the rapid development of force as the muscle is being stretched or remains nearly isometric near the end of the upstroke. The pectoralis then shortens by a total of 32 % of its resting length during the downstroke, generating an average of 10.3±3.6J kg−1 muscle (mean ± S.D.) of work per cycle for the anterior and posterior sites recorded among the five animals. In contrast to previous kinematic estimates of muscle length change relative to force development, the sonomicrometry measurements of fascicle length change show that force declines during muscle shortening. Simultaneous measurements of fascicle length change at anterior and posterior sites within the same muscle show significant (P&lt;0.001, three of four animals) differences in fractional length (strain) change that averaged 19±12 %, despite exhibiting similar work loop shape. Length changes at both anterior and posterior sites were nearly synchronous and had an asymmetrical pattern, with shortening occupying 63 % of the cycle. This nearly 2:1 phase ratio of shortening to lengthening probably favors the ability of the muscle to do work. Mean muscle shortening velocity was 5.38±1.33 and 4.88±1.27 lengths s−1 at the anterior and posterior sites respectively. Length excursions of the muscle were more variable at the end of the downstroke (maximum shortening), particularly when the birds landed, compared with highly uniform length excursions at the end of the upstroke (maximum lengthening). When averaged for the muscle as a whole, our in vivo work measurements yield a mass-specific net mechanical power output of 70.2 W kg−1 for the muscle when the birds flew at 5–6 m s−1, with a wingbeat frequency of 8.7 Hz. This is 38 % greater than the value that we obtained previously for wild-type pigeons, but still 24–50 % less than that predicted by theory.