bluuebunny/crossref_metadata_2025_split huggingface dataset:
Responses of Anterior Lateral Line Afferent Neurones to Water Flow
Authors: Voigt Rainer , Carton Alexander G. , Montgomery John C. 
Published: April 2021

ABSTRACT
The mechanoreceptive lateral line system detects hydrodynamic stimuli and plays an important role in a number of types of fish behaviour, including orientation to water currents. The lateral line is composed of hair cell receptor organs called neuromasts that occur as superficial neuromasts on the surface of the skin or canal neuromasts located in subepidermal canals. Both are innervated by primary afferents of the lateral line nerves. Although there have been extensive studies of the response properties of lateral line afferents to vibrating sources, their response to water flow has not been reported. In this study, we recorded extracellularly from anterior lateral line afferents in the New Zealand long-fin eel Anguilla dieffenbachii while stimulating the eel with unidirectional water flows at 0.5–4 cm s−1. Of the afferents, 80 % were flow-sensitive to varying degrees, the response magnitude increasing with flow rate. Flow-sensitive fibres gave non-adapting tonic responses, indicating that these fibres detect absolute flow velocity. Further studies are needed to confirm whether flow-sensitive and flow-insensitive fibres correlate with superficial and canal neuromasts, respectively.
Geographic and Altitudinal Variation in Water Balance And Metabolic Rate in a California Grasshopper, Melanoplus Sanguinipes
Authors: Rourke Bryan C. 
Published: April 2021

ABSTRACT
The importance of respiratory patterns and the physical properties of cuticular lipids to insect water balance were investigated in natural populations of the grasshopper Melanoplus sanguinipes. I specifically test the hypotheses that patterns of discontinuous ventilation affect water loss and that increased amounts and melting points of cuticular lipid reduce water loss. Using flow-through respirometry, rates of water loss and carbon dioxide release from grasshoppers were quantified at 25, 35 and 42 °C. Populations displayed substantial variation, with high-elevation populations exhibiting the greatest water loss and metabolic rates. Behavior leading to discontinuous gas exchange was observed in several populations, but its occurrence decreased dramatically at high temperatures and was not correlated with a reduction in the rate of water loss. The amount and melting point of cuticular lipids were determined for each individual using gas chromatography and Fourier-transform infrared spectroscopy. Increased amounts and higher melting points of cuticular lipids were strongly correlated with lower rates of water loss in populations. I show that discontinuous gas exchange is unlikely to be a mechanism for reducing water loss in these insects and that the lipid properties are primarily responsible for variation in overall water loss rates.
Asynchronous Muscle: A Primer
Authors: Josephson Robert K. , Malamud Jean G. , Stokes Darrell R. 
Published: April 2021

ABSTRACT
The asynchronous muscles of insects are characterized by asynchrony between muscle electrical and mechanical activity, a fibrillar organization with poorly developed sarcoplasmic reticulum, a slow time course of isometric contraction, low isometric force, high passive stiffness and delayed stretch activation and shortening deactivation. These properties are illustrated by comparing an asynchronous muscle, the basalar flight muscle of the beetle Cotinus mutabilis, with synchronous wing muscles from the locust, Schistocerca americana. Because of delayed stretch activation and shortening deactivation, a tetanically stimulated beetle muscle can do work when subjected to repetitive lengthening and shortening. The synchronous locust muscle, subjected to similar stimulation and length change, absorbs rather than produces work.
Relationships Between Body Mass, Motor Output and Flight Variables During Free Flight of Juvenile and Mature Adult Locusts, Schistocerca Gregaria
Authors: Fischer Hanno , Kutsch Wolfram 
Published: April 2021

ABSTRACT
Little information is available about how the adult locust flight system manages to match the aerodynamic demands that result from an increase in body mass during postmoult maturation. In Schistocerca gregaria of both sexes, flight variables, including flight speed, ascent angle and body angle, were investigated under closed-loop conditions (i.e. during free flight) as a function of adult maturation. Motor patterns were examined by telemetric electromyography in juvenile and adult mature animals of both sexes. Functional relationships between particular flight variables were investigated by additional loading of the animals and by reductions in wing area. The results indicate that an increase in flight speed as the flight system matures enables it to match the aerodynamic demands resulting from increases in body mass. Furthermore, the data suggest that this postmoult increase in flight speed is not simply a consequence of the increase in wingbeat frequency observed during maturation. The instantaneous body angle during flight is controlled mainly by aerodynamic output from the wings. In addition, the mean body angle decreases during maturation in both sexes, and this may play an important part in the directional control of the resultant flight force vector.
In Vivo Demonstration of Load-Induced Fluid Flow in the Rat Tibia and Its Potential Implications For Processes Associated With Functional Adaptation
Authors: Tate M.L. Knothe , Steck R. , Forwood M. R. , Niederer P. 
Published: April 2021

ABSTRACT
Load-induced extravascular fluid flow has been postulated to play a role in mechanotransduction of physiological loads at the cellular level. Furthermore, the displaced fluid serves as a carrier for metabolites, nutrients, mineral precursors and osteotropic agents important for cellular activity. We hypothesise that load-induced fluid flow enhances the transport of these key substances, thus helping to regulate cellular activity associated with processes of functional adaptation and remodelling. To test this hypothesis, molecular tracer methods developed previously by our group were applied in vivo to observe and quantify the effects of load-induced fluid flow under four-point-bending loads. Preterminal tracer transport studies were carried out on 24 skeletally mature Sprague Dawley rats. Mechanical loading enhanced the transport of both small-and larger-molecular-mass tracers within the bony tissue of the tibial mid-diaphysis. Mechanical loading showed a highly significant effect on the number of periosteocytic spaces exhibiting tracer within the cross section of each bone. For all loading rates studied, the concentration of Procion Red tracer was consistently higher in the tibia subjected to pure bending loads than in the unloaded, contralateral tibia. Furthermore, the enhancement of transport was highly site-specific. In bones subjected to pure bending loads, a greater number of periosteocytic spaces exhibited the presence of tracer in the tension band of the cross section than in the compression band; this may reflect the higher strains induced in the tension band compared with the compression band within the mid-diaphysis of the rat tibia. Regardless of loading mode, the mean difference between the loaded side and the unloaded contralateral control side decreased with increasing loading frequency. Whether this reflects the length of exposure to the tracer or specific frequency effects cannot be determined by this set of experiments. These in vivo experimental results corroborate those of previous ex vivo and in vitro studies. Strain-related differences in tracer distribution provide support for the hypothesis that load-induced fluid flow plays a regulatory role in processes associated with functional adaptation.
Ontogenetic Scaling of Burrowing Forces in the Earthworm Lumbricus Terrestris
Authors: Quillin Kim J. 
Published: April 2021

ABSTRACT
In hydrostatic skeletons, it is the internal fluid under pressure surrounded by a body wall in tension (rather than a rigid lever) that enables the stiffening of the organism, the antagonism of muscles and the transmission of force from the muscles to the environment. This study examined the ontogenetic effects of body size on force production by an organism supported with a hydrostatic skeleton. The earthworm Lumbricus terrestris burrows by forcefully enlarging crevices in the soil. I built a force-measuring apparatus that measured the radial forces as earthworms of different sizes crawled through and enlarged pre-formed soil burrows. I also built an apparatus that measured the radial and axial forces as earthworms of different sizes attempted to elongate a dead-end burrow. Earthworms ranging in body mass mb from hatchlings (0.012 g) to adults (8.9 g) exerted maximum forces (F, in N) during active radial expansion of their burrows (F=0.32mb0.43) and comparable forces during axial elongation of the burrow (F=0.26mb0.47). Both these forces were almost an order of magnitude greater than the radial anchoring forces during normal peristalsis within burrows (F=0.04mb0.45). All radial and axial forces scaled as body mass raised to the 2/5 power rather than to the 2/3 power expected by geometric similarity, indicating that large worms exert greater forces than small worms on an absolute scale, but the difference was less than predicted by scaling considerations. When forces were normalized by body weight, hatchlings could push 500 times their own body weight, while large adults could push only 10 times their own body weight.
Durophagy in Sharks: Feeding Mechanics of the Hammerhead Sphyrna Tiburo
Authors: Wilga Cheryl D. , Motta Philip J. 
Published: April 2021

ABSTRACT
This study investigates the motor pattern and head movements during feeding of a durophagus shark, the bonnethead Sphyrna tiburo, using electromyography and simultaneous high-speed video. Sphyrna tiburo feeds almost exclusively on hard-shelled crabs, with shrimp and fish taken occasionally. It captures crabs by ram feeding, then processes or reduces the prey by crushing it between molariform teeth, finally transporting the prey by suction for swallowing. The prey-crushing mechanism is distinct from that of ram or bite capture and suction transport. This crushing mechanism is accomplished by altering the duration of jaw adductor muscle activity and modifying jaw kinematics by the addition of a second jaw-closing phase. In crushing events, motor activity of the jaw adductor muscles continues (biting of the prey occurs as the jaws close and continues after the jaws have closed) throughout a second jaw-closing phase, unlike capture and transport events during which motor activity (biting) ceases at jaw closure. Sphyrna tiburo is able to take advantage of a resource (hard prey) that is not readily available to most sharks by utilizing a suite of durophagous characteristics: molariform teeth, a modified jaw protrusor muscle, altered jaw adductor activity and modified jaw kinematics. Sphyrna tiburo is a specialist feeder on crab prey as demonstrated by the lack of differences in kinematic or motor patterns when offered prey of differing hardness and its apparent lack of ability to modulate its behavior when feeding on other prey. Functional patterns are altered and coupled with modifications in dental and jaw morphology to produce diverse crushing behaviors in elasmobranchs.
Two orcokinins and the novel octapeptide orcomyotropin in the hindgut of the crayfish Orconectes Limosus: Identified myostimulatory neuropeptides originating together in neurones of the terminal abdominal ganglion
Authors: Dircksen Heinrich , Burdzik Siegward , Sauter Arnold , Keller Rainer 
Published: April 2021

ABSTRACT
The tridecapeptides Asn13-orcokinin and Val13- orcokinin, two known members of the orcokinin neuropeptide family native to crustaceans, and a novel octapeptide, orcomyotropin, FDAFTTGFamide, have been identified from extracts of hindguts of the crayfish Orconectes limosus using an isolated hindgut contractility bioassay, high-performance liquid chromatography, microsequencing and mass spectrometry. All three peptides display strong inotropic actions on crayfish hindguts. Orcomyotropin showed higher potency than the two orcokinins. Threshold concentration was approximately 5×10−12 moll−1versus 10−10 moll−1 for the two orcokinins. An approximately fivefold increase in contraction amplitude was observed with 10−9 moll−1 orcomyotropin and 10−7 moll−1 of the orcokinins. Asn13- and Val13-orcokinin did not differ significantly with regard to their biological effects. Semi-isolated crayfish hearts and locust oviducts did not respond to the three peptides. Immunocytochemistry using antisera against Asn13- orcokinin and orcomyotropin showed that these neuropeptides are co-localized in approximately 80–90 neurones of the terminal abdominal ganglion that have been shown to innervate the entire hindgut muscularis via the intestinal nerve. The neurones form elaborate terminal branches preferentially on longitudinal hindgut muscles. Orcomyotropin is a novel crustacean member of the GF-amide family of myotropic and/or allatotropic neuropeptides from annelids, molluscs and insects.
Inspiratory aerodynamic valving in the avian lung: Functional morphology of the extrapulmonary primary bronchus
Authors: Maina John N. , Africa Miranda 
Published: April 2021

ABSTRACT
The form, geometry and epithelial morphology of the extrapulmonary primary bronchi (EPPB) of the domestic fowl (Gallus gallus var. domesticus) and the rock dove (Columba livia) were studied microscopically and by three­dimensional computer reconstruction to determine the structural features that may be involved in the rectification of the inspired air past the openings of the medioventral secondary bronchi (MVSB), i.e. the inspiratory aerodynamic valving (IAV). In both species, the EPPB were intercalated between the clavicular and the cranial thoracic air-sacs. A notable difference between the morphology of the EPPB in G. g. domesticus and C. livia was that, in the former, the EPPB were constricted at the origin of the MVSB, while a dilatation occurred at the same site in the latter. In both species, a highly vascularized, dorsally located hemispherical epithelial swelling was observed cranial to the origin of the MVSB. The MVSB were narrow at their origin and variably angled relative to the longitudinal axis of the EPPB. Conspicuous epithelial tracts and folds were observed on the luminal aspect of the EPPB in both C. livia and G. g. domesticus. From their marked development and their orientation relative to the angled MVSB, these properties may influence the flow of the air in the EPPB. It was concluded that features such as syringeal constriction, an intimate topographic relationship between the EPPB and the cranial air-sacs, prominent epithelial tracts and folds, an epithelial swelling ahead of the origin of the first MVSB (corresponding to the ‘segmentun accelerans’), and narrowing and angulation of the MVSB at their origin, may together contribute to IAV to a variable extent. In as much as the mechanism of pulmonary ventilation and mode of airflow in the parabronchial lung are basically similar in all birds, the morphological differences observed between G. g. domesticus and C. livia suggest that either the mechanism of production of IAV or its functional efficiency may be different, at least in these two species of birds.
Integumentary L-Histidine Transport in a Euryhaline Polychaete Worm: Regulatory Roles of Calcium and Cadmium in the Transport Event
Authors: Hammers Ahearn Heather Rae , Ahearn Gregory A. , Gomme Jørgen 
Published: April 2021

ABSTRACT
Integumentary uptake of L-[3H]histidine by polychaete worms (Nereis succinea) from estuarine waters of Oahu, Hawaii was measured in the presence and absence of calcium and cadmium using a physiological saline that approximated the ion composition of 60 % sea water. In this medium 1 µmol l−1cadmium significantly increased (P&lt;0.01) the uptake of 10 µmol l−1 L-[3H]histidine, while 1 µmol l−1 cadmium plus 25 µmol l−1 L-leucine significantly decreased (P&lt;0.01) amino acid uptake. L-[3H]histidine influx was a sigmoidal function (n=2.21±0.16, mean ± S.E.M.) of [L-histidine] (1–50 µmol l−1) in the absence of cadmium, but became a hyperbolic function with the addition of 1 µmol l−1cadmium. A decrease of calcium concentration from 6 to 0 mmol l−1(lithium substitution) significantly increased (P&lt;0.01) amino acid influx in the presence and absence of cadmium. Calcium significantly reduced (P&lt;0.01), and cadmium significantly increased (P&lt;0.01), L-[3H]histidine influx Jmax, without either divalent cation affecting amino acid influx Kt. Variation in external sodium concentration (0–250 mmol l−1) had no effect on 10 µmol l−1 L-[3H]histidine influx, but amino acid entry was a sigmoidal function of both [cadmium] (n=2.34±0.44) and [lithium] (n=1.91±0.39) in the absence of calcium. A model is proposed for transapical L-[3H]histidine influx by a transporter that resembles the classical sodium-independent L-system carrier protein that is regulated by the external divalent cations calcium and cadmium.
Image Analysis of Olfactory Responses in the Procerebrum of the Terrestrial Slug Limax Marginatus
Authors: Toda Sho’ichi , Kawahara Shigenori , Kirino Yutaka 
Published: April 2021

ABSTRACT
Neural oscillations have been found to occur in the olfactory centers of some vertebrates and invertebrates, including the procerebrum of the terrestrial slug Limax marginatus. Using optical recording with the potential-sensitive dye di-4-ANEPPS, we analyzed the spatiotemporal pattern of procerebral neural activities in response to odorants applied to an in vitro brain-superior tentacle preparation. The odor of rat chow, on which the slugs were normally fed, increased the frequency of the oscillation. Garlic odor, which induced aversive behavior in the slug, caused a transient increase in oscillation frequency during stimulation, followed by a second increase in oscillation frequency when the stimulus was terminated. Wave propagation from the distal to the proximal region of the procerebrum was accelerated in parallel with modulation of the frequency. The cycle-by-cycle average of the optical signals showed that a large area of the cerebral ganglia, including the procerebrum, was depolarized during the initial increase in frequency. During the second increase, however, the net depolarization was most prominent in the terminal mass of the procerebrum. These results suggest that the level of depolarization generated by interactions among the neurites projecting to the terminal mass, such as the neurites of the nonbursting neurons, may control neural oscillations in the procerebrum.
Nitrogen Metabolites and Related Enzymatic Activities in the Body Fluids and Tissues of the Hydrothermal Vent Tubeworm Riftia Pachyptila
Authors: De Cian Marie-Cécile , Regnault Michèle , Lallier François H. 
Published: April 2021

ABSTRACT
The distribution of nitrogen metabolism end-products and the associated enzyme activities, free amino acids and purine base catabolites were investigated in all the body compartments (circulating fluids and tissues) of the hydrothermal vent tubeworm Riftia pachyptila to acquire a general overview of nitrogen metabolism in this symbiotic organism. There were striking differences between the symbiont-containing trophosome tissue and other host tissues. High concentrations of ammonia, creatinine and, in particular, urate were found in all tissues, but they were present at consistently higher concentrations in the trophosome, which also contained large amounts of urea. Uric acid crystals were present at the periphery of trophosome lobules. The urea cycle appears to be fully functional in this tissue, which also uses creatine phosphate for phosphagen storage, while arginine phosphate or a combination of both phosphagens occurs in other tissues. The amino acid patterns are dominated by sulphated compounds in all tissues except the trophosome, which has high levels of aspartate and glutamate. Although no definitive conclusions could be drawn regarding the nitrogen regime of Riftia pachyptila, this in vitro study gives several indications for future research in this area.
The Hind Wing of the Desert Locust (Schistocerca Gregaria Forskål): I. Functional Morphology and Mode of Operation
Authors: Wootton R. J. , Evans K. E. , Herbert R. , Smith C. W. 
Published: April 2021

ABSTRACT
Detailed morphological investigation, mechanical testing and high-speed cinematography and stroboscopic examination of desert locusts, Schistocerca gregaria, in flight show that their hind wings are adapted to deform cyclically and automatically through the wing stroke and that the deformations are subtly dependent on the wings’ structure: their shape, venation and vein design and the local properties of the membrane. The insects predominantly fly fast forwards, generating most force on the downstroke, and the hind wings generate extra lift by peeling apart at the beginning of the downstroke and by developing a cambered section during the stroke’s translation phase through the ‘umbrella effect’ – an automatic consequence of the active extension of the wings’ expanded posterior fan. Bending experiments indicate that most of the hind wing is more rigid to forces from below than from above and demonstrate that the membrane acts as a stressed skin to stiffen the structure.
Effects of Environmental Salinity on Na+/K+-ATPase in the Gills and Rectal Gland of a Euryhaline Elasmobranch (Dasyatis Sabina)
Authors: Piermarini Peter M. , Evans David H. 
Published: April 2021

ABSTRACT
Changes in Na+/K+-ATPase activity and abundance associated with environmental salinity were investigated in the gills and rectal gland of the Atlantic stingray Dasyatis sabina. Using a ouabain-specific ATPase assay and western blotting, we found that stingrays from fresh water had the highest activity and highest relative abundance of Na+/K+-ATPase in the gills. Using immunohistochemistry, we also found that gills from freshwater stingrays had the greatest number of Na+/K+-ATPase-rich cells. When freshwater stingrays were acclimated to sea water for 1 week, the activity and abundance of Na+/K+-ATPase and the number of Na+/K+-ATPase-rich cells decreased in the gills. In seawater stingrays, the branchial activity and abundance of Na+/K+-ATPase and the number of Na+/K+-ATPase-rich cells were further reduced. In rectal glands, the activity and abundance of Na+/K+-ATPase were lower in freshwater animals than in seawater-acclimated and seawater stingrays, both of which had equivalent levels. These findings suggest that salinity-associated changes in gill and rectal gland Na+/K+-ATPase activity are due to changes in the abundance of Na+/K+-ATPase. We conclude that the gills may be important for active ion uptake in fresh water, while the rectal gland is important for active NaCl excretion in sea water. The results from this study are the first to demonstrate an effect of environmental salinity on Na+/K+-ATPase expression in the gills and rectal gland of an elasmobranch.