bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Acid–Base Balance of the Outer Mantle Epithelium of Anodonta Cygnea
Authors: Machado J. , Ferreira K. G. , Ferreira H. G. , Fernandes P. L. 
Published: April 2021

ABSTRACT
Under short-circuit conditions the outer mantle epithelium of Anodonta cygnea is known to produce an acidification of the solution bathing the shell side and an alkalinization of the solution bathing the haemolymph side. At steady state, the rates of secretion of acid and base were numerically equal to the simultaneously measured short-circuit current, expressed in the same units. The rates of acid and base secretion, and the short-circuit current, showed close similarity in the reductions caused by anoxia, diamox, DIDS (from haemolymph side), DNP and iodoacetamide. The short-circuit current (Isc) was sensitive to the concentration of CO2, bicarbonate or protons in the solution on the shell side. The short-circuit current was insensitive to vanadate or oligomycin, was slowly inhibited by DCCD added under anoxia to the shell side, and was almost completely inhibited within seconds by TBTO (shell side) which also caused a 40% reduction in transepithelial conductance. It is suggested that Isc is due to a Cl−/HCO3−exchange shunted by a Cl− recirculation across the basolateral membrane and to the operation of an electrogenic proton pump located in the apical membrane.
Lethal and Quasi-Lethal Effects Produce by Monochromatic Ultra-Violet Irradiation
Authors: McAulay A. L. , Taylor M. C. 
Published: April 2021

ABSTRACT
Lethal and quasi-lethal effects produced by monochromatic ultra-violet irradiation of biological material representing the phyla Bacteria, Fungi, Angiospermae, Protozoa and Arthropoda have been observed and recorded over a range of wavelengths from 254 to 365 mµ. Although the materials represent high and low forms in both vegetable and animal kingdoms, there is a striking similarity in their behaviour. There is a sudden increase in the lethal effect between 313 and 297 mµ in every case.
Although the curves connecting lethal dose with wave-length are closely similar in all cases, the absolute magnitudes of doses are widely different. The ratio of lethal doses for different material may be as high as two hundred to one at corresponding wave-lengths. The ratio of the greatest to the least dose recorded is of the order of a million to one.
Tables and curves are given recording lethal and quasi-lethal doses for the different materials at different wave-lengths, and brief accounts of the conditions in which the experiments were conducted are given in the text.
An interesting correlation is exhibited between the form of the lethal dose curves and the ultra-violet radiation in daylight.
Energy-Saving Mechanisms in Walking and Running
Authors: Alexander R. McN. 
Published: April 2021

ABSTRACT
Energy can be saved in terrestrial locomotion in many different ways. The maximum shortening speeds (vmax) of the muscles can be adjusted to their optimum values for the tasks required of them. The moments exerted by the muscles at different joints can be adjusted to keep the ground force in line with the leg so that muscles do not work against each other. The joints of the legs can be kept as straight as possible, minimizing muscle forces and work requirements. Walking gaits should be selected at low Froude numbers (a dimensionless speed parameter) and running gaits at high Froude numbers. Tendon and other springs can be used to store elastic strain energy and to return it by elastic recoil. This paper aims to show how these energy-saving mechanisms work and to what extent mammals exploit them. Arguments based on our rather limited knowledge of the relationship between the mechanical performance of muscle and its metabolic energy consumption are used throughout. They suggest that muscles that are optimally adapted for their tasks in running should do positive work with constant efficiency.
A Model of Rapid-Start Swimming at Intermediate Reynolds Number: Undulatory Locomotion in the Chaetognath Sagitta Elegans
Authors: Jordan Christopher E. 
Published: April 2021

ABSTRACT
The mechanics and kinematics of accelerational undulatory locomotion by the chaetognath Sagitta elegans (Verrill, 1873) are studied with a combination of highspeed cinematography (200 frames s−1) and mathematical modeling. The model is constructed such that it predicts body velocity for an organism starting from rest and accelerating rapidly by swimming with prescribed wave kinematics. The speed of the undulatory propulsive waves and the number of these waves on the body is highly conserved across 11 individuals, while the wave amplitude is positively related to distance traveled in the first 65 ms of swimming. There is excellent agreement between these data and predictions of body translations that are based on a mathematical model for this mode of locomotion. The model also shows that instantaneous forces generated by the undulating body are much larger than average forces and consist of non-trivial inertial terms, even for such small organisms. The model also shows that the distance traveled over a fixed time interval is limited by the maximum muscle stress that can be physiologically generated. Peak instantaneous force represents a mechanical upper boundary to thrust production and, hence, a limit to performance.
Regulation of Pulmonary Blood Flow and of Blood Pressure in a Mangrove Crab (Goniopsis Cruentata)
Authors: Wilkens J. L. , Young R. E. 
Published: April 2021

ABSTRACT
The air-breathing mangrove crab Goniopsis cruentata ventilates the branchial chambers with its scaphognathites (SG). Ventilation is predominantly in the forward direction, but is punctuated by bouts of reversed pumping. Reversals are more frequent when crabs are in air than in water, and yet more frequent during respiratory stress (hypoxia or exercise). Reversed SG pumping is tightly coupled with bursts of impulses to the dorsal-ventral muscles (DVM) which span the anterolateral thorax. Phasic contractions of the DVMs increase the hemolymph pressure in the dorsal sinuses. These pressure pulses help drive hemolymph through the lungs. The coupled SG reversed ventilation and DVM-assisted increases in lung perfusion appear to be an adaptation to increase gas exchange at the lungs.
When crabs are made hyper-or hypotensive by changes in hemolymph volume, the EMG activity of the DVMs dramatically decreases or increases, respectively. The resultant expansion or constriction of the dorsal sinuses is an effective baroreceptor reflex producing short-term adjustments in hemolymph pressure.
Pectoralis Muscle Force and Power Output During Flight in the Starling
Authors: Biewener Andrew A. , Dial Kenneth P. , Goslow G. E. 
Published: April 2021

ABSTRACT
Force recordings of the pectoralis muscle of European starlings have been made in vivo during level flight in a wind tunnel, based on bone strain recordings at the muscle’s attachment site on the humerus (deltopectoral crest). This represents the first direct measurement of muscle force during activity in a live animal based on calibrated bone strain recordings. Our force measurements confirm earlier electromyographic data and show that the pectoralis begins to develop force during the final one-third of the upstroke, reaches a maximal level halfway through the downstroke, and sustains force throughout the downstroke. Peak forces generated by the pectoralis during level flight at a speed estimated to be 13.7ms−1 averaged 6.4N (28% of maximal isometric force), generating a mean mass-specific muscle power output of 104 W kg−1. Combining our data for the power output of the pectoralis muscle with data for the metabolic power of starlings flying at a similar speed yields an overall flight efficiency of 13 %. The force recordings and length changes of the muscle, based on angular displacements of the humerus, indicate that the pectoralis muscle undergoes a lengthening-shortening contraction sequence during its activation and that, in addition to lift and thrust generation, overcoming wing inertia is probably an important function of this muscle in flapping flight.
Kinematics of Aquatic Prey Capture in the Snapping Turtle Chelydra Serpentina
Authors: Lauder G. V. , Prendergast T. 
Published: April 2021

ABSTRACT
The kinematics of feeding on two prey types is studied quantitatively in the common snapping turtle, Chelydra serpentina, to provide a description of prey capture mechanisms and to determine whether kinematic patterns can be altered in response to prey that vary in escape capability. High-speed video recordings of prey capture (200 fields s-1) provide data for field-by-field analysis of 12 kinematic variables characterizing head and neck movement. Feedings on fish were accomplished in 78 ms, with peak head extension velocities of 152.5 cm s-1. Worm feedings lasted 98 ms with maximum head extension velocities of 54cms-1. Both univariate and multivariate statistical analyses demonstrate significant differences in kinematic patterns between fish and earthworm feedings: Chelydra serpentina possesses the ability to modulate its kinematic pattern depending on the prey. The pattern of bone movement during the fast opening phase of the gape cycle is similar to that found in ray-finned fishes, lungfishes and aquatic salamanders. However, movements of the cranium and lower jaw during the closing phase are markedly different. Our data show Chelydra to be predominantly a ram-feeder, with any intraoral negative pressures generated during the strike having a negligible effect on the prey, which remains largely stationary relative to a fixed background. Hyoid and esophageal expansion during the closing phase may function to allow a unidirectional flow of water and prey into the mouth until the gape closes and to delay reverse flow until the prey has been trapped inside the mouth. The independent evolutionary acquisition of aquatic feeding in fishes and turtles reveals some kinematic similarities that may be the result of hydrodynamic constraints on aquatic prey capture systems, as well as kinematic differences that result from the fundamentally different morphological design of the prey capture apparatus.
Antibodies to Mammalian and Plant V-Atpases Cross React With the V-Atpase of Insect Cation-Transporting Plasma Membranes
Authors: Russell Virginia E. W. , Klein Ulla , Reuveni Moshe , Spaeth Daniel D. , Wolfersberger Michael G. , Harvey William R. 
Published: April 2021

ABSTRACT
In immunobiochemical blots, polyclonal antibodies against subunits of plant and mammalian vacuolar-type ATPases (V-ATPases) cross-react strongly with corresponding subunits of larval Manduca sexta midgut plasma membrane V-ATPase. Thus, rabbit antiserum against Kalanchoe daigremontiana tonoplast V-ATPase holoenzyme cross-reacts with the 67, 56, 40, 28 and 20kDa subunits of midgut V-ATPase separated by SDS-PAGE. Antisera against bovine chromaffin granule 72 and 39 kDa V-ATPase subunits cross-react with the corresponding 67 and 43 kDa subunits of midgut V-ATPase. Antisera against the 57 kDa subunit of both beet root and oat root V-ATPase cross-react strongly with the midgut 56 kDa V-ATPase subunit.
In immunocytochemical light micrographs, antiserum against the beet root 57 kDa V-ATPase subunit labels the goblet cell apical membrane of both posterior and anterior midgut in freeze-substituted and fixed sections. The plant antiserum also labels the apical brush-border plasma membrane of Malpighian tubules. The ability of antibodies against plant V-ATPase to label these insect membranes suggests a high sequence homology between V-ATPases from plants and insects.
Both of the antibody-labelled insect membranes transport K+ and both membranes possess Frlike particles, portasomes, on their cytoplasmic surfaces. This immunolabelling by xenic V-ATPase antisera of two insect cation-transporting membranes suggests that the portasomes on these membranes may be V-ATPase particles, similar to those reported on V-ATPase-containing vacuolar membranes from various sources.
The Synchronization of Ventilation and Locomotion in Horses (Equus Caballus)
Authors: Young Iain S. , Alexander R. McN. , Woakes A. J. , Butler P. J. , Anderson Lloyd 
Published: April 2021

ABSTRACT
Ciné film and synchronized records of respiratory flow were obtained from Thoroughbred racehorses cantering on a treadmill at speeds of 9 and 11ms−1.
Horses and some other galloping and hopping mammals link their breathing and locomotion, taking exactly one breath per stride. Three theoretical mechanisms by which the movements of locomotion might drive ventilation are considered.
(i) Flexion of the lumbosacral joint and the resulting forward sweep of the pelvis pushes the viscera against the diaphragm. However, back flexion lags behind ventilation at 11ms−1 and could not exclusively drive ventilation at this speed. (ii) Loading of the thorax by the impact of the forelimbs with the ground might force air out of the lungs. If the respiratory system were damped sufficiently to perform as this mechanism requires, the work of driving ventilation would make up approximately 15 % of the total work of running. In comparison with other estimates of the work of ventilation this seems improbably high, (iii) The observed phase relationship between displacements of the viscera, caused by the accelerations of the body during running, and respiratory airflow is not consistent with a tuned visceral piston mechanism driving breathing.
Thus, it would seem likely that back flexion is likely to contribute towards driving ventilation but loading of the thorax and the visceral piston mechanism do not.
An Analysis of Control of the Ventricle of the Mollusc Mercenaria
Mercenaria: II. Ionic Mechanisms Involved in Excitation By 5-Hydroxytryptamine
Authors: Devlin C. Leah 
Published: April 2021

ABSTRACT
This study focuses on the ionic mechanisms involved in serotonergic control of the ventricle from the mollusc MercenariaMercenaria. The effects of calcium (Ca2+), sodium (Na+), potassium (K+), magnesium (Mg2+) and chloride (Cl−) ions on the action of 5-hydroxytryptamine (5-HT) were tested using a sucrose-gap technique. 5-HT increased the amplitude and frequency of the cardiac action potentials (APs) and coupled systolic force in a range of concentrations from the threshold, at 10−10 mol l−1, to 10−6 mol l−1. Low, physiological doses of 5-HT increased the rate of rise and amplitude of the fast rising phase of the AP, and hastened the process of repolarization. Doses of 5-HT higher than 10−5mol l−1caused systolic arrest.
The action of 5-HT was highly dependent on the presence of physiological levels of extracellular Ca2+. It had a maximal effect on systolic activity in a calcium chloride concentration range of 9–18mmol l−1. The activity of 5-HT was blocked by treatment with Ca2+-free saline, with inorganic Ca2+ blockers (lanthanum or cobalt) or with an organic Ca2+ entry blocker (verapamil). The effects of 5-HT were potentiated by treatment with barium ions (Ba2+), by a dihydropyridine-sensitive Ca2+ agonist, Bay K 8644, or by a vertebrate Ca2+ entry blocker, diltiazem.Removal of extracellular Na+ or treatment with a Na+ ionophore, monensin, did not significantly affect excitation by 10−6 mol l−15-HT; nor did the removal of Cl− or Mg2+. Unlike Ca2+, these three ions probably did not have a critical role during the excitatory action of 5-HT.
The excitatory action of 5-HT was not significantly altered by treatment with K+-free saline. When the membrane was depolarized by high-K+ salines, however, 5-HT was unable to elicit any APs or systolic contractions, suggesting that its mechanism may involve voltage-sensitive channels.
Anomalous Glutamate/Alkali Cation Symport In Larval Manduca Sexta Midgut
Authors: Xie Tao , Parthasarathy R. , Wolfersberger Michael G. , Harvey William R. 
Published: April 2021

ABSTRACT
Rapid filtration assays were used to characterize glutamate/cation uptake in brush-border membrane vesicles from the larval midgut of the lepidopteran Manduca sexta. At pH 10.5, which is close to the physiological pH in the midgut of M. sexta, an inwardly directed K+ gradient stimulated glutamate uptake, suggesting that glutamate was symported. Gradients of Na+ or Li+ were less effective. Neither Rb+ nor Cs+ stimulated glutamate uptake. Anion-specificity was less pronounced: the accumulation maximum was only slightly higher with thiocyanate (SCN−) than with Cl−, although initial uptake was noticeably faster with thiocyanate.
A distinct set of amino acids that would cis-inhibit or trans-elicit glutamate uptake was not found. Even L-glutamate itself did not elicit accumulations of labeled glutamate. Taken together, these results suggest that a glutamate-specific symporter may not be present. Moreover, because glutamate symport was found to be electroneutral in vitro whereas amino acid uptake is electrophoretic in vivo, we infer that symport with K+ may not be an important mechanism of glutamate translocation by M. sexta midgut.
Transepithelial Potential And Alkalization in an in Situ Preparation of Tobacco Hornworm (Manduca Sexta) Midgut
Authors: Moffett David F. , Cummings Stacey Ann 
Published: April 2021

ABSTRACT
The midgut of larval lepidopteran insects rapidly raises the pH of the entering food from approximately neutral values to as high as pH 12 in some species (Waterhouse, 1949; Dow, 1984). These values are among the highest achieved by biological systems and are all the more remarkable in view of the high rate of food consumption relative to body mass in lepidopteran larvae.
Head Waving in Aplysia Californica: I. Behavioural Characterization of Searching Movements
Authors: Kuenzi Frederick M. , Carew Thomas J. 
Published: April 2021

ABSTRACT
Searching is an important component of several types of goal-directed behaviour. In soft-bodied animals, searching behaviour can appear quite complex because the range of body movement is not constrained by joints, limbs or muscles with discrete areas of origin and insertion. In addition, animals exhibiting this type of behaviour utilize their maximum freedom of movement. In this paper, we describe the head-waving searching behaviour of the sea hare Aplysia californica by characterizing patterns of movements and the changes in body shape that underlie these movements. A bout of head waving consists of a series of discrete movements separated by pauses. Each discrete movement lasts 4–10 s and is directed either horizontally or vertically with respect to the stationary part of the animal. Large movements, such as bending from the extreme right to the extreme left, consist of a series of these shorter movements separated by pauses lasting 1–2 s. In all head-waving movements, the transverse axis of the head is kept relatively parallel with the substratum. Thus, vertical movements require only bending of the body, whereas horizontal movements require twisting of the body, particularly when the posture is more erect. During head waving, the anterior two-thirds of the body is free to move, but most of the bending occurs immediately posterior to the head region. There is no periodicity of movements within a bout of head waving, although isolated instances of repeated movements are sometimes observed. Therefore, although the individual movements during head waving are relatively simple, the absence of a patterned sequence accounts for the complexity of the overall behaviour. These observations both constrain models of the neural organization of head waving and provide criteria for categorizing head-waving movements in further behavioural and physiological studies.
Physiological Modelling of Oxygen Consumption In Birds During Flight
Authors: Bishop C. M. , Butler P. J. 
Published: April 2021

ABSTRACT
This study combines data on changes in cardiovascular variables with body mass (Mb) and with exercise intensity to model the oxygen supply available to birds during flight. Its main purpose is to provide a framework for identifying the factors involved in limiting aerobic power input to birds during flight and to suggest which cardiovascular variables are the most likely to have been influenced by natural selection when considering both allometric and adaptive variation.
It is argued that natural selection has acted on heart rate (fh) and cardiac stroke volume (Vs), so that the difference in the arteriovenous oxygen content in birds, both at rest and during flight, is independent of Mb. Therefore, the Mb exponent for oxygen consumption during flight can be estimated from measurements of heart rate and stroke volume. Stroke volume is likely to be directly proportional to heart mass (Mh) and, using empirical data, values for the Mb coefficients and exponents of various cardiovascular variables are estimated. It is concluded that, as found for mammals, fh is the main adaptive variable when considering allometric variation, although Mh also shows a slight scaling effect. Relative Mh is likely to be the most important when considering adaptive specialisations.
The Fick equation may be represented as:

where w, x, y, z are the body mass exponents for each variable and the terms in parentheses represent the Mb coefficients. Utilising this formula and data from the literature, the scaling of minimum during flight for bird species with a ‘high aerobic capacity’ (excluding hummingbirds) is calculated to be:

and for hummingbirds (considered separately owing to their unique wing kinematics) it is:

These results are largely dependent on the cardiovascular values obtained from pigeons flying near to the minimum power speed of 10 m s-1, but would appear to provide realistic values. Both the measured and the estimated for hummingbirds appear to scale with a larger Mb exponent than that for all other birds, and it is suggested that this is as a result of the larger Mb exponent for flight muscle mass as the larger species of hummingbirds try to maintain hovering performance. It is proposed that estimated for birds during flight, which is based on Mh in combination with estimates of fh and , gives an indirect measure of relative aerobic power input and, when corrected for the estimated scaling influences of the mechano-chemical conversion efficiency and lift generation with respect to Mb, may be a useful indicator of the relative capacity of the muscle to sustain power output and lift production during flight.
Branchial Chloride Cells in Larvae and Juveniles of Freshwater Tilapia Oreochromis Mossambicus
Authors: Li Jie , Eygensteyn Jelle , Lock Robert A. C. , Verbost Pieter M. , Heijden Angelique J. H. Van Der , Bonga Sjoerd E. Wendelaar , Flik Gert 
Published: April 2021

ABSTRACT
Branchial chloride cells in the developing larvae and juveniles of freshwater tilapia, Oreochromis mossambicus, were identified and the membrane Na+/K+-ATPase was localized in situ through binding of the fluorescent dye anthroylouabain. After co-labelling of the cells with the fluorescent probes DASPMI and Con-A-FITC, the mitochondria and apical crypt in the same chloride cells were visualized using confocal laser scanning microscopy. The high density of apical crypts indicated that many chloride cells were functional. The density of branchial chloride cells in larvae 10 days after hatching was approximately 6000 mm−2. An extremely high Na+/K+-ATPase specific activity of approximately 1500μmol Pi h−1 mg−1 was measured in the gills 10 days after hatching. With the development of secondary lamellae and hence an increase in the amount of branchial epithelial protein, a concomitant decrease in the specific activity of the enzyme in the gill tissues was observed. Total Na+/K+-ATPase activity increased markedly in the early life stages. Our data indicate that in larval stages of fish the gills form a functional ionoregulatory organ before they start functioning as a gas-exchange organ.