bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maintenance of Neutral Buoyancy by Depth Selection in the Loggerhead Turtle Caretta Caretta
Authors: Minamikawa Shingo , Naito Yasuhiko , Sato Katsufumi , Matsuzawa Yoshimasa , Bando Takeharu , Sakamoto Wataru 
Published: April 2021

ABSTRACT
Time-series data of swimming speed and dive depth were recorded in six female loggerhead turtles Caretta caretta during the internesting period. The dive profiles of all animals indicated that they stayed at particular depths without swimming and that these depths were correlated with dive duration. These results support the hypothesis that lung air is used to achieve neutral buoyancy in the loggerhead turtle.
To test this hypothesis, female turtles were equipped with lead weights and time/depth recorders. The residence depth of the turtles increased when their specific gravity was artificially decreased. This indicates that they control depth rather than lung volume, suggesting that the residence depth of loggerhead turtles during the internesting period is not determined actively. They presumably remain at a particular depth exclusively to save energy for egg maturation during the internesting period.
Lung volume was estimated from the change in depth of weighted animals to be 50–150 ml kg−1. The resulting residence depth of all turtles was within the range at which they maintained the neutral buoyancy.
Sniffing by a Silkworm Moth: Wing Fanning Enhances air Penetration Through and Pheromone Interception by Antennae
Authors: Loudon C. , Koehl M. A. R. 
Published: April 2021

ABSTRACT
Many organisms increase the air or water flow adjacent to olfactory surfaces when exposed to appropriate chemical stimuli; such ‘sniffing’ samples fluid from a specific region and can increase the rate of interception of odorant molecules. We used hot-wire anemometry, high-speed videography and flow visualization to study air flow near the feathery olfactory antennae of male silkworm moths (Bombyx mori L.). When exposed to conspecific female sex pheromone, male B. mori flap their wings through a stroke angle of 90–110 ° at approximately 40 Hz without flying. This behavior generates an unsteady flow of air (mean speed 0.3–0.4 m s−1) towards the antennae from the front of the male. A pulse of peak air speed occurs at each wing upstroke. The Womersley number (characterizing the damping of pulsatile flow through the gaps between the sensory hairs on the antennae) is less than 1; hence, pulses of faster air (at 40 Hz) should move between sensory hairs. Calculation of flow through arrays of cylinders suggest that this wing fanning can increase the rate of interception of pheromone by the sensory hairs on the antennae by at least an order of magnitude beyond that in still air. Although wing fanning produces air flow relative to the antennae that is approximately 15 times faster than that generated by walking at top speed (0.023 m s−1), air flow through the gaps between the sensory hairs is approximately 560 times faster because a dramatic increase in the leakiness of the feathery antennae to air flow occurs at the air velocities produced by fanning.
Properties of a Carbonic Anhydrase Inhibitor Protein in Flounder Serum
Authors: Peters Thomas , Papadopoulos Frauke , Kubis Hans-Peter , Gros Gerolf 
Published: April 2021

ABSTRACT
The blood serum of the European flounder Platichthys flesus strongly inhibits soluble erythrocytic carbonic anhydrase from the same species. The inhibition is of the uncompetitive type. Hence, the mechanism of the carbonic anhydrase inhibition is different from that of all other known carbonic anhydrase inhibitors. The serum showed no inhibitory effect on carbonic anhydrase from human and bovine red blood cells. By applying the 18O exchange reaction, it could be demonstrated that the presence of the carbonic anhydrase inhibitor in the extracellular fluid has no effect on carbonic anhydrase in intact red blood cells. Thus, this carbonic anhydrase inhibitor seems to act only within the plasma space of the circulatory system.
However, the carbonic anhydrase inhibitor does appear to reduce the bicarbonate permeability of flounder red cells to approximately one-quarter of normal levels as measured by the 18O exchange reaction. The 28 kDa carbonic anhydrase inhibitor was isolated from the serum by gel filtration. The isolated inhibitor was detected in acrylamide gels as a single band representing a 7 kDa protein. The denaturing conditions used in electrophoresis presumably led to a dissociation of the native protein into subunits.
Ecdysteroids Regulate Secretory Competence in Inka Cells
Authors: Kingan Timothy G. , Adams Michael E. 
Published: April 2021

ABSTRACT
Ecdysis, or molting behavior, in insects requires the sequential action of high levels of ecdysteroids, which induce accumulation of ecdysis-triggering hormone (ETH) in Inka cells, followed by low levels of ecdysteroids, permissive for the onset of the behavior. Here, we show that high ecdysteroid levels suppress the onset of the behavioral sequence by inhibiting the development of competence to secrete ETH. In pharate pupae of Manduca sexta, Inka cells in the epitracheal glands normally develop competence to secrete ETH in response to eclosion hormone (EH) 8 h before pupation. Injection of 20-hydroxyecdysone (20E) into precompetent insects prevents this acquisition of competence, but does not affect EH-evoked accumulation of the second messenger cyclic GMP. Precompetent glands acquire competence in vitro after overnight culture, and this can be prevented by the inclusion of 20E at concentrations greater than 0.1 μg ml−1 in the culture medium. Actinomycin D completely inhibits the acquisition of competence, demonstrating that it is dependent on transcriptional events. Cultured epitracheal glands become refractory to the inhibitory effects of 20E in the acquisition of competence at least 3 h earlier than for Actinomycin D, indicating that 20E acts on an early step in a sequence of nuclear events leading to transcription of a structural gene. Our findings suggest that declining ecdysteroid levels permit a late event in transcription, the product of which is downstream of EH receptor activation and cyclic GMP accumulation in the cascade leading to ETH secretion.
Intraspecific Scaling of Feeding Mechanics in an Ontogenetic Series of Zebrafish, Danio Rerio
Authors: Hernández Luz Patricia 
Published: April 2021

ABSTRACT
While a vast literature and long tradition of examining the scaling of locomotory function exists, scaling studies on feeding mechanics are relatively rare. A recent increase in research activity examining the scaling of feeding kinematics has led to conflicting results. These divergent findings may be due to the inherent differences in the biophysical systems being examined. The present study examines the role of growth in the scaling of feeding kinematics in an ontogenetic series of zebrafish, Danio rerio. Although many other studies have investigated aquatic feeding, this study represents the first to quantify detailed feeding kinematics in first-feeding larvae. This study examines both the effects of violating assumptions of geometric similarity when examining scaling relationships and the role water viscosity plays in molding scaling coefficients derived from feeding kinematics. The effects of Reynolds number, generally not relevant in vertebrate feeding studies, play a crucial role in determining scaling relationships in this species. Many scaling coefficients reflect the functional challenges of feeding at low Reynolds numbers. Moreover, scaling patterns in feeding mechanics often reflect allometric growth during early ontogeny. The advent of high-speed video recording (1000 frames s−1) now allows the kinematics of feeding at these small sizes to be rigorously examined.
Effects of Nonylphenol and 17β-Estradiol on Vitellogenin Synthesis and Testis Morphology in Male Platyfish Xiphophorus Maculatus
Authors: Kinnberg Karin , Korsgaard Bodil , Bjerregaard Poul , Jespersen Åse 
Published: April 2021

ABSTRACT
Nonylphenol has been found to exert estrogenic effects in fish and may influence the fertility of male fish. In the present study, the effects of nonylphenol and 17β-estradiol on vitellogenin synthesis and testis morphology in platyfish Xiphophorus maculatus were investigated. Vitellogenin was observed in the plasma of all fish exposed to nonylphenol or 17β-estradiol. Exposure to 17β-estradiol resulted in a significant reduction in the gonadosomatic index. A tendency for a dose-dependent reduction in the gonadosomatic index in the nonylphenol exposed groups was observed. Histological examination revealed dose-dependent effects of nonylphenol on the testis structure. The testes of control fish contained numerous cysts with spermatogenetic cells. The testes of fish exposed to nonylphenol or 17β-estradiol showed a decrease in the number of cysts concomitant with an increase in the amount of hypertrophied Sertoli cells present. Formation of spermatozeugmata is compulsory for this species, but free spermatozoa were observed in the efferent ducts of the treated fish. The study indicates that nonylphenol has estrogenic potency, and that both nonylphenol and 17β-estradiol have marked effects on the testis morphology of X. maculatus. The ambient concentration of nonylphenol was measured by high pressure liquid chromatography during the experiment. The measurements revealed that the actual concentrations of nonylphenol in the water were about 30–40 % of the nominal concentrations.
Escape Behaviour in the Stomatopod Crustacean Squilla Mantis, and the Evolution of the Caridoid Escape Reaction
Authors: Heitler W. J. , Fraser K. , Ferrero E. A. 
Published: April 2021

ABSTRACT
The mantis shrimp Squilla mantis shows a graded series of avoidance/escape responses to visual and mechanical (vibration and touch) rostral stimuli. A low-threshold response is mediated by the simultaneous protraction of the thoracic walking legs and abdominal swimmerets and telson, producing a backwards ‘lurch’ or jump that can displace the animal by up to one-third of its body length, but leaves it facing in the same direction. A stronger response starts with similar limb protraction, but is followed by partial abdominal flexion. The maximal response also consists of limb protraction followed by abdominal flexion, but in this case the abdominal flexion is sufficiently vigorous to pull the animal into a tight vertical loop, which leaves it inverted and facing away from the stimulus. The animal then swims forward (away from the stimulus) and rights itself by executing a half-roll.
A bilaterally paired, large-diameter, rapidly conducting axon in the dorsal region of the ventral nerve excites swimmeret protractor motoneurons in several ganglia and is likely to be the driver neuron for the limb-protraction response. The same neuron also excites unidentified abdominal trunk motoneurons, but less reliably.
The escape response is a key feature of the malacostracan caridoid facies, and we provide the first detailed description of this response in a group that diverged early in malacostracan evolution. We show that the components of the escape response contrast strongly with those of the full caridoid reaction, and we provide physiological and behavioural evidence for the biological plausibility of a limb-before-tail thesis for the evolution of the escape response.
Tracking Clock-Shifted Homing Pigeons From Familiar Release Sites
Authors: Bonadona Fransisco , Holland Richard , Dall’Antonia Luigi , Guilford Tim , Benvenuti Silvano 
Published: April 2021

ABSTRACT
Clock-shifted homing pigeons were tracked from familiar sites 17.1 km and 23.5 km from the home loft in Pisa, Italy, using an on-board route recorder. At the first release site, north of home, the majority of clock-shifted birds had relatively straight tracks comparable with those of control birds. At the second release site, south of home, the clock-shifted birds deflected in the direction predicted for the degree of clock shift, with many birds travelling some distance in the wrong direction before correcting their course. The possible role of large-scale terrain features in homing pigeon navigation is discussed.
The Independent Effects of Gravity and Inertia on Running Mechanics
Authors: Chang Young-Hui , Huang Hsuan-Wen Cathy , Hamerski Chris M. , Kram Rodger 
Published: April 2021

ABSTRACT
It is difficult to distinguish the independent effects of gravity from those of inertia on a running animal. Simply adding mass proportionally changes both the weight (gravitational force) and mass (inertial force) of the animal. We measured ground reaction forces for eight male humans running normally at 3 m s−1 and under three experimental treatments: added gravitational and inertial forces, added inertial forces and reduced gravitational forces. Subjects ran at 110, 120 and 130 % of normal weight and mass, at 110, 120 and 130 % of normal mass while maintaining 100 % normal weight, and at 25, 50 and 75 % of normal weight while maintaining 100 % normal mass. The peak active vertical forces generated changed with weight, but did not change with mass. Surprisingly, horizontal impulses changed substantially more with weight than with mass. Gravity exerted a greater influence than inertia on both vertical and horizontal forces generated against the ground during running. Subjects changed vertical and horizontal forces proportionately at corresponding times in the step cycle to maintain the orientation of the resultant vector despite a nearly threefold change in magnitude across treatments. Maintaining the orientation of the resultant vector during periods of high force generation aligns the vector with the leg to minimize muscle forces.
Periodic Tension Development in the Membrane of the in Vitro Contractile Vacuole of Paramecium Multimicronucleatum: Modification by Bisection, Fusion and Suction
Authors: Tani Tomomi , Allen Richard D. , Naitoh Yutaka 
Published: April 2021

ABSTRACT
The contractile vacuole of the freshwater protozoan Paramecium multimicronucleatum is a membrane-bound exocytotic vesicle that expels excess cytosolic water. The in vitro contractile vacuole isolated from P. multimicronucleatum along with a small amount of cytosol and confined under mineral oil showed periodic rounding and slackening at fairly regular intervals. Activity lasted for over 30 min at room temperature (24–27 °C). The rounding of the in vitro contractile vacuole corresponded to the increased membrane tension of the in vivo contractile vacuole that occurs immediately before fluid expulsion. Unlike the in vivo contractile vacuole, the in vitro contractile vacuole did not expel fluid, since it lacked a mechanism to form a pore. The subsequent slackening of the in vitro contractile vacuole corresponded to the fluid-filling phase of the in vivo contractile vacuole that occurs at decreased membrane tension. Fluid filling occurred in the in vitro contractile vacuole only when it was isolated together with its radial arms. In vitro membrane-bound vesicles obtained by ‘bisecting’ (although the two parts were not always identical in size) an in vitro contractile vacuole established their own independent rounding– slackening cycles. In vitro contractile vacuole vesicles could fuse again when the vesicles slackened. The fused vesicle then showed a rounding–slackening cycle with a period closer to that of the vesicle that exhibited the shorter cycle period. An additional rounding phase of the in vitro contractile vacuole could be induced by applying suction to a portion of its membrane with a micropipette when the contractile vacuole was in its slackened phase. This suggests that maximum tension development in the contractile vacuole membrane can be triggered when tension is increased in any part of the contractile vacuole membrane. The time from the start of an extra rounding phase to the next spontaneous rounding and for subsequent rounding–slackening cycles was nearly the same as that before the extra rounding phase. This implies that there is no master pacemaker to control the rounding–slackening cycle in the contractile vacuole membrane. Severed radial arms also became vesiculated and, like contractile vacuole membranes, these in vitro vesicles showed independent rounding–slackening cycles and vesicle–vesicle fusions. Thus, membrane derived from the radial arm seems to be identical in its tension-developing properties with the contractile vacuole membrane. ATP was found to be required for contractile vacuole rounding but inhibitors of actin or tubulin polymerization, such as cytochalasin B and Nocodazole, had no effect on the in vitro contractile vacuole’s rounding–slackening cycle.
The Contribution of a Ca2+-Activated Cl− Conductance to Amino-Acid-induced Inward Current Responses of Ciliated Olfactory Neurons of the Rainbow Trout
Authors: Sato Koji , Suzuki Noriyo 
Published: April 2021

ABSTRACT
To determine whether amino-acid-induced inward currents of ciliated olfactory receptor neurons (ORNs) in rainbow trout (Oncorhynchus mykiss) include a Ca2+-activated Cl− conductance, we first studied changes in reversal potential and the current/voltage relationships of the responses of ORNs to an amino acid mixture (L-alanine, L-arginine, L-glutamate and L-norvaline; all 10 mmol l−1) with different concentrations of Na+ and Cl− in the perfusion and recording pipette solutions. We also examined the effects of six different Cl− channel blockers on the responses of ORNs using a conventional whole-cell voltage-clamp technique. The amino acid mixture and one blocker were applied focally to the cilia of ORNs using a double-barrelled micropipette and a pressure ejection system. The expected shifts in reversal potential, indicating the contribution of the Ca2+-activated Cl− conductance, occurred in both positive and negative directions depending on the external and internal Na+ and Cl− concentrations. Niflumic acid, flufenamic acid, NPPB [5-nitro-2-(3-phenylpropylamino)-benzonate] and DCDPC (3′,5-dichlorodiphenylamine-2-carboxylate), at 0.5 mmol l−1, reversibly blocked both the amino-acid-induced inward currents and the background activity in most ORNs. The effectiveness of these blocking agents varied from 77 to 91 % for ORNs perfused externally with standard Ringer’s solution. SITS (4-acetamido-4′-isothiocyanatostilbene-2,2′-disulphonate), at 5.0 mmol l−1, irreversibly inhibited the physiological response (100 % inhibition), whereas DIDS (4,4′-diisothiocyanatostilbene-2,2′-disulphonate), at 5.0 mmol l−1, had the smallest effect (45 %) of the inhibitors tested. The dose of niflumic acid inducing 50 % inhibition (IC50), determined specifically for the current component of the Ca2+-activated Cl− channels, was 70 µmol l−1. Our results suggest that these blockers are not specific for Ca2+-activated Cl− channels and that the density of these channels varies between individual ORNs. Our results also show that the Ca2+-activated Cl− conductance plays an important role in olfactory transduction and allows fishes to adapt to various ionic environments.
Osteopontin Expression in Spontaneously Developed Neointima in Fowl (Gallus Gallus)
Authors: Kuykindoll Rhonda J. , Nishimura Hiroko , Thomason Donald B. , Nishimoto Satoru K. 
Published: April 2021

ABSTRACT
Fowl show spontaneous elevation of blood pressure and neointimal plaque formation in the abdominal aorta at young ages. A similar neointima can be induced by a balloon-catheter-induced endothelium injury to the fowl aorta. Both spontaneously developed and injury-induced vascular lesions exhibit subendothelial hyperplasia consisting of neointimal cells with a synthetic phenotype and abundant extracellular matrix. The role of the extracellular matrix in the formation of neointima is not known. In this study, we investigated whether osteopontin, an adhesive glycoprotein present in the extracellular matrix, is expressed in aortic smooth muscle tissue of the fowl abdominal aorta, in spontaneously developed neointimal plaques and in the aortic smooth muscle underlying neointimal plaques. Crude protein extracted from isolated aortic smooth muscle tissues and neointimal plaques was fractionated by SDS–polyacrylamide gel electrophoresis and analyzed by immunoblotting with rabbit anti-fowl osteopontin (provided by Dr L. C. Gerstenfeld, Boston University) or anti-alpha smooth muscle actin antibodies. The anti-fowl osteopontin antibody predominantly recognized a 66–70 kDa protein band in neointimal plaques that co-migrated with the osteopontin phosphoprotein from chick bone. In contrast, intact aortic smooth muscle and the smooth muscle underlying neointimal plaques equally expressed three proteins (66–70 kDa, approximately 50 kDa and approximately 43 kDa) recognized by the anti-osteopontin antibody. Anti-alpha smooth muscle actin antibody recognized a 43 kDa protein band, and the expression of alpha smooth muscle actin was higher in aortic smooth muscle than in neointimal plaques. Osteopontin mRNA expression was examined using reverse transcription– polymerase chain reaction (RT–PCR) of total RNA from vascular tissues with specific primers constructed on the basis of the reported fowl osteopontin nucleotide sequence. The PCR products from intact aortic smooth muscle and neointimal plaques correspond to the product from recombinant plasmid cDNA (a gift from Dr L. C. Gerstenfeld) transcribed in vitro. These results suggest that osteopontin is synthesized in intact aortic smooth muscle and neointimal plaques in fowl and that unmetabolized approximately 66 kDa osteopontin protein is a predominant form in the neointima, indicating that osteopontin protein may be actively synthesized in the neointima.
Killer Whales (Orcinus Orca) Feeding On Schooling Herring (Clupea Harengus) Using Underwater Tail-Slaps: Kinematic Analyses of Field Observations
Authors: Domenici Paolo , Batty Robert S. , Similä Tiu , Ogam Erick 
Published: April 2021

ABSTRACT
Killer whales (Orcinus orca) feeding on herring (Clupea harengus) in a fjord in northern Norway were observed using underwater video. The whales cooperatively herded herring into tight schools close to the surface. During herding and feeding, killer whales swam around and under a school of herring, periodically lunging at it and stunning the herring by slapping them with the underside of their flukes while completely submerged. The kinematics of tail-slapping were analysed in detail. Tail-slaps were made up of a biphasic behaviour consisting of two phases with opposite angles of attack, a preparatory phase (negative angles of attack) and a slap phase (positive angles of attack). During the slap phase, the mean maximum angle of attack of the flukes was 47 °. The maximum speed of the flukes, measured at the notch, increased with whale length (Lw) and was 2.2 Lw s−1, while the maximum acceleration of the flukes was size-independent and was 48 m s−2.
When killer whales slapped the herring successfully, disoriented herring appeared on the video at approximately the time of maximum fluke velocity, in synchrony with a loud noise. This noise was not heard when the tail-slaps ‘missed’ the target, suggesting that the herring were stunned by physical contact. Killer whales then ate the stunned herring one by one. Of the tail-slaps observed, 61 % were preceded by lunges into the school. We suggest that lunging was aimed at directing the school rather than at capturing the herring, since it occurred at a relatively low speed and there were no observations of the killer whales attempting to capture the herring during lunging behaviour. Given the high performance of the tail-slaps in terms of speed and acceleration, we suggest that tail-slapping by killer whales is a more efficient strategy of prey capture than whole-body attacks, since acceleration and manoeuvrability are likely to be poor in such large vertebrates.