bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Apodeme Complex of the Femoral Chordotonal Organ in the Metathoracic Leg of the Locust Schistocerca Gregaria
Authors: Shelton P. M. J. , Stephen R. O. , Scott J. J. A. , Tindall A. R. 
Published: April 2021

ABSTRACT
The mechanical connections of the metathoracic femoral chordotonal organ (mtFCO) with its insertion at the femoro-tibial joint are described. The apodeme complex is shown to consist of a distal cuticular rod that is replaced proximally by dorsal and ventral ligaments. The dorsal ligament is a direct continuation of the distal rod but proximally it is replaced by ligamentous cells. The ventral ligament has no cuticular core and consists of ligamentous cells throughout its length. The ligaments are composed of bundles of connective tissue cells that are each enclosed in an extracellular matrix containing acid-fuchsin-staining fibrils. Internally the cells are packed with microtubules. During extension and flexion of the joint, the two ligaments move differentially. During passive extension of the tibia, the ventral ligament remains taut but the dorsal one buckles to form a slack loop. Direct observation of living preparations shows that the loop is first detectable during extension of the tibia at joint angles greater than about 51 °. During flexion, the loop gradually tightens and disappears. It has completely disappeared at joint angles of less than about 36°. Changes in loop shape were demonstrable using preparations in which the tibia was moved sinusoidally ±10° about a mean femoro-tibial angle of 90° and photographs were taken using phase-locked illumination. Other details of the apodeme complex are described and the significance of the findings is discussed in relation to mtFCO function.
L-Serine Uptake by Trout (Salmo Trutta) Red Blood Cells: the Effect of Isoproterenol
Authors: Gallardo M. A. , Planas J. , Sánchez J. 
Published: April 2021

ABSTRACT
We studied the uptake of L-serine by trout red blood cells and the effect of a -adrenergic agonist (isoproterenol) on this process. The results obtained indicate that L-serine is taken up by these cells by means of a concentrative process. The uptake seems to be mediated both by a sodium-dependent process and by a sodium-independent process. The sodium-dependent uptake is mediated by a transport system that probably belongs to the ASC system family. Isoproterenol exerts an inhibitory effect on L-serine uptake. This effect is dose-dependent. It is proposed that the inhibitory effect of isoproterenol is mediated by a rise in the intracellular sodium concentration and/or changes in cell volume.
Sensory Inputs Mediating two Opposite Behavioural Responses to Light in the Crayfish Procambarus Clarkii
Authors: Fernández-De-Miguel Francisco , Aréchiga Hugo 
Published: April 2021

ABSTRACT
Crustaceans are attracted out of their burrows by dim light whereas they withdraw in response to light of high intensity. We have studied attraction and withdrawal responses in freely walking crayfish (Procambarus clarkii) and in animals tethered above a treadmill device. Electrophysiological recordings have been made of retinal and extraretinal visual units to determine their possible inputs.
Attraction was induced by light of 0.17– 1.4 lx; the crayfish walked forward with the abdomen extended. Withdrawal was observed at intensities above 5.6lx; the crayfish walked backwards with a cyclic pattern of flexion and extension of the tail. A group of sustaining visual neurones of the optic nerve with low thresholds was found to respond to light in the range of intensities that produced attraction. Two groups of neurones responded in the range of intensities that produced withdrawal: sustaining visual neurones with high thresholds and the caudal photoreceptors. In animals in which the visual fields of the high-threshold fibres had been covered with black paint, the attraction response was not affected, while withdrawal was only observed in response to light stronger than 11 lx. When tested on a treadmill, the latency of the responses to light and the direction of walking of crayfish reflected attraction and withdrawal responses. Moreover, under these conditions, illumination of the eye induced forward walking at intensities that produce attraction and backward walking at intensities that produce withdrawal. In contrast, illumination of the tail induced only backward walking.
Osmolality and Electrolyte Composition of Pleon Fluid in Porcellio Scaber (Crustacea, Isopqda, Oniscidea): Implications for Water Vapour Absorption
Authors: Wright Jonathan C. , O’Donnell Michael J. 
Published: April 2021

ABSTRACT
Active water vapour absorption in Porcellio scaber is associated with the endogenous production of strongly hyperosmotic fluid in the pleoventral chamber (pleoventralraum; PV). Pre-desiccated animals show increased pleon fluid secretion within 1–2 min of transfer to suprathreshold humidities (&gt;87 % relative humidity). The conspicuous increase in fluid volume is accompanied by a rise in osmolality from isosmotic (approximately 750mosmolkg−1) up to as much as 8.2osmol kg−1. Vapour absorption is marked by the onset of metachronal pleopodal ventilation and a subsequent decline in fluid osmolality as uptake fluid approaches equilibrium with ambient water activities. The effects of sealing of the PV by the margins of the depressed pleopods, along with the observation that animals ventilate even when PV fluid activities are somewhat below ambient, suggest that resultant pressure increases may elevate humidity within the PV and thereby augment vapour uptake. Ion-selective microelectrode measurements of Na+, K+, Ca2+ and Cl− concentrations in nanolitre samples of isolated pleon fluid identify Na+ and Cl− as the major osmolytes. Possible preadaptions favouring evolution of vapour absorption in the Oniscidea are discussed.
Ventilation and Gas Exchange During Shallow Hypothermia in Pigeons
Authors: Jensen Chris , Bech Claus 
Published: April 2021

ABSTRACT
Ventilatory control of the composition of the gases in the air sacs was studied during entry into fasting-induced, shallow, nocturnal hypothermia in the domestic pigeon (Columba livia). Respiratory frequency (f), tidal volume (VT) and oxygen uptake were recorded simultaneously in six pigeons; partial pressures of CO2 and O2 in the abdominal and interclavicular air sacs were measured in seven pigeons. Ambient temperature was 25°C (thermoneutral) and the body temperature (Tb) was recorded in all experiments.
A reduction in Tb from 40.5 to 37.5°C paralleled decreases in f and VT from 13.3 min-1 and 15.2 ml BTPS kg-1 to 10.7 min-1 and 12.4ml BTPskg-1, respectively. There was a minor, but non-significant, simultaneous decrease in the ventilatory requirement (total ventilation/O2 uptake) from 0.38 to 0.35 ml BTPS mmol-1. However, in both air sacs the partial pressure of CO2 increased when Tb decreased, indicating an effective parabronchial hypoventilation.
The results support the idea of a gradually developing respiratory acidosis during hypothermia.
An Electrophysiological Characterization of Ciliated Olfactory Receptor Cells of the Coho Salmon Oncorhynchus Kisutch
Authors: Nevitt Gabrielle A. , Moody William J. 
Published: April 2021

ABSTRACT
Electrical properties of ciliated olfactory receptor cells isolated from coho salmon (Oncorhynchus kisutch) were studied using the whole-cell mode of the patch-clamp recording technique.
Voltage-dependent currents could be separated into two inward and three outward conductances, including a Na+ current, Ca2+ current and three K+ currents. The components of the outward current varied with the life stage of the salmon from which cells had been isolated. In cells isolated from juvenile fish (parr), a Ca2+-dependent K+ current dominated the outward current, whereas in cells isolated from older fish (i.e. fish that had undergone smoltification), a transient K+ current became prominent. Differences in response characteristics of outward currents to internal dialysis with cyclic GMP (but not cyclic AMP) were also correlated to the life stage of salmon. Under conditions in which the Ca2+-activated current was blocked, relaxation of the outward current was slowed by dialysis with cyclic GMP only in cells isolated from smolts and sea-run fish, but not in those isolated from mature spawners. From these results, we suggest that hormone modulation of olfactory receptor cell development or differentiation may play a role in establishing these differences.
The Effects of Wing Rotation on Unsteady Aerodynamic Performance At Low Reynolds Numbers
Authors: Dickinson Michael H. 
Published: April 2021

ABSTRACT
The downstroke-to-upstroke transition of many insects is characterized by rapid wing rotation. The aerodynamic consequences of these rapid changes in angle of attack have been investigated using a mechanical model dynamically scaled to the Reynolds number appropriate for the flight of small insects such as Drosophila. Several kinematic parameters of the wing flip were examined, including the speed and axis of rotation, as well as the duration and angle of attack during the wing stroke preceding rotation. Alteration of these kinematic parameters altered force generation during the subsequent stroke in a variety of ways.
When the rotational axis was close to the trailing edge, the model wing could capture vorticity generated during rotation and greatly increase aerodynamic performance. This vortex capture was most clearly manifested by the generation of lift at an angle of attack of 0°. Lift at a 0° angle of attack was also generated following rotation about the leading edge, but only if the downstroke angle was large enough to generate a von Karman street. The lift may be due to an alteration in the effective angle of attack caused by the inter-vortex stream in the downstroke wake. The maximum lift attained (over all angles of attack) was substantially elevated if the wing translated backwards through a wake generated by the previous stroke. Transient lift coefficient values of nearly 4 were obtained when the wing translated back through a von Karman street generated at a 76.5° angle of attack. This effect might also be explained by the influence of the inter-vortex stream, which contributes a small component to fluid velocity in the direction of translation. The growth of lift with angle of attack was significantly elevated following a 7.5 chord stroke with a 76.5° angle of attack, although it was relatively constant under all other kinematic conditions. The results also indicate the discrepancies between transient and time-averaged measures of performance that arise when unsteady mechanisms are responsible for force generation. Although the influence of wing rotation was strong during the first few chords of translation, averaging the performance over as little as 6.5 chords of motion greatly attenuated the effects of rotation. Together, these modeling results suggest that the unsteady mechanisms generated by simple wing flips could provide an important source for the production of aerodynamic forces in insect flight. Furthermore, the extreme sensitivity to small variations in almost all kinematic parameters could provide a foundation for understanding the aerodynamic mechanisms underlying active flight control.
A Locust Octopamine-Immunoreactive Dorsal Unpaired Median Neurone Forming Terminal Networks On Sympathetic Nerves
Authors: Bräunig Peter , Stevenson Paul A. , Evans Peter D. 
Published: April 2021

ABSTRACT
In insects, octopamine is present in neurohaemal regions of the thoracic sympathetic nervous system, but its cellular source is unknown. We describe a dorsal unpaired median neurone (DUM1b) in the locust metathoracic ganglion that forms a meshwork of varicose, presumably neurohaemal, endings on the surfaces of sympathetic nerves. Other targets include several ventral longitudinal muscles, the spiracle closer muscle, tissue remnants of degenerated nymphal muscles and the salivary glands. Using an established antiserum, DUM1b is shown to be octopamine-immunoreactive, and its target muscles to be covered with octopamine-immunoreactive varicosities. Octopamine influences one of these muscles in essentially the same way that another well-described octopaminergic neurone, DUMEti, modulates the extensor tibiae muscle of the hind leg. We propose that DUM1b is an octopaminergic modulator of muscle contractions and may also influence numerous other body functions by releasing octopamine as a hormone from sympathetic neurohaemal areas.
Are Mitochondria Subject to Evolutionary Temperature Adaptation?
Authors: Johnston Ian A. , Guderley Helga , Franklin Craig E. , Crockford Tony , Kamunde Collins 
Published: April 2021

ABSTRACT
Thermal tolerance and the respiratory properties of isolated red muscle mitochondria were investigated in Oreochromis alcalicus grahami from the alkaline hot-springs, Lake Magadi, Kenya. Populations of O. a. grahami were resident in pools at 42.8°C and migrated into water reaching temperatures of 44.8°C for short periods. The maximum respiration rates of mitochondria with pyruvate as substrate were 217 and 284 natom O mg−1 mitochondrial protein min−1 at 37°C and 42°C, respectively (Q10=1.71). Fatty acyl carnitines (chain lengths C8, C12 and C16), malate and glutamate were oxidised at 70–80% of the rate for pyruvate. In order to assess evolutionary temperature adaptation of maximum mitochondrial oxidative capacities, the rates of pyruvate and palmitoyl carnitine utilisation in red muscle mitochondria were measured from species living at other temperatures: Notothenia coriiceps from Antarctica (-1.5 to +1°C); summer-caught Myoxocephalus scorpius from the North Sea (10–15°C); and Oreochromis andersoni from African lakes and rivers (22–30°C). State 3 respiration rates had Q10 values in the range 1.8–2.7. At the lower lethal temperature of O. andersoni (12.5°C), isolated mitochondria utilised pyruvate at a similar rate to mitochondria from N. coriiceps at 2.5°C (30 natom O mg−1 mitochondrial protein min−1). Rates of pyruvate oxidation by mitochondria from M. scorpius and N. coriiceps were similar and were higher at a given temperature than for O. andersoni. At their normal body temperature (-1.2°C), mitochondria from the Antarctic fish oxidised pyruvate at 5.5% and palmitoyl-DL-carnitine at 8.8% of the rates of mitochondria from the hot-spring species at 42°C. The results indicate only modest evolutionary adjustments in the maximal rates of mitochondrial respiration in fish living at different temperatures.
The Lung–Eardrum Pathway in Three Treefrog and Four Dendrobatid Frog Species: Some Properties of Sound Transmission
Authors: Ehret Günter , Keilwerth Elke , Kamada Tsutomu 
Published: April 2021

ABSTRACT
Frequency–response curves of the tympanum and lateral body wall (lung area) were measured by laser Doppler vibrometry in three treefrog (Smilisca baudini, Hyla cinerea, Osteopilus septentrionalis) and four dendrobatid frog (Dendrobates tinctorius, D. histrionicus, Epipedobates tricolor, E. azureiventris) species. The high-frequency cut-off of the body wall response was always lower than that of the tympanum. The best response frequencies of the lateral body wall were lower than those of the tympanum in some species (S. baudini, O. septentrionalis, D. tinctorius), while in the others they were rather similar. Best tympanic frequencies and best body wall response frequencies tended to differ more with increasing body size.
Stimulation of the tympanum by sound transfer through 3.14 mm2 areas of the lateral body wall showed that the lung–eardrum pathway can be in two states, depending on breathing activity within the lungs: 44% (in Smilisca), 39% (in Hyla) and 31% (in Osteopilus) of the eardrum vibrations were 2.5–8 times (8–18 dB) larger when the frogs were breathing with the lungs compared with non-breathing conditions.
The vibration amplitudes of the tympanum and lateral body wall of the treefrogs followed the same dependence on sound intensity, only absolute amplitudes differed between species.
Our results suggest that the lung–eardrum pathway attenuates high-frequency components of species-specific calls and enhances low-frequency components. In addition, an amplitude modulation is imposed on the low frequencies during the rhythm of breathing.
The Olfactory Memory of the Honeybee Apis Mellifera:II. Blocking Between Odorants in Binary Mixtures
Authors: Smith Brian H. , Cobey Susan 
Published: April 2021

ABSTRACT
Proboscis extension conditioning of honeybee workers was used to study the processing of odorants when bees were conditioned to binary mixtures. Responses to a set of pure floral odors and pheromones after conditioning have already been described. When bees are conditioned to certain mixtures of odorants, the response to both components is equal to that when they are tested alone. However, mixtures of an aliphatic aldehyde and an alcohol elicit asymmetric response patterns; that is, the response to the aldehyde is much stronger than that to the alcohol. A bee’s response to the alcohol after it had been trained in an aldehyde background is significantly lower than when the bee is trained to respond to the same alcohol in the background of another odorant. Such response patterns are not necessarily caused by a behavioral decrement resulting from a compound-unique perceptual effect produced by the mixture. Furthermore, studies of blocking show that behavioral acquisition in response to one component can be hindered or blocked by pretraining with the other component. These results suggest that honeybees can perceive the individual components of some binary mixtures. The similarities in neural processing in olfactory systems of vertebrates and invertebrates mean that such studies could elucidate behavioral mechanisms of olfaction in a wide phylogenetic spectrum of animals.
Porters and Neurotransmitter Transporters
Authors: Nelson Nathan , Lill Holger 
Published: April 2021

ABSTRACT
Uptake of neurotransmitters involves multiple transporters acting in different brain locations under different physiological conditions. The vesicular transporters are driven by a proton-motive force generated by a V-ATPase and their substrates are taken up via proton/substrate exchange. The plasma membrane transporters are driven by an electrochemical gradient of sodium generated by a Na+/K+-ATPase. Two distinct families of transporters were identified in this group. One cotransports sodium with glutamate and other amino acids and requires additionally an outwardly directed potassium gradient. The second cotransports sodium, chloride and a variety of neurotransmitters, including γ-aminobutyric acid (GABA), glycine and monoamines. Genes and cDNA encoding several members of the latter family have been cloned and studied in detail. The structure and function as well as the evolutionary relationships among these neurotransmitter transporters are discussed.
Swimming Kinematics of Fast Starts are Altered by Temperature Acclimation in the Marine Fish Myoxocephalus Scorpius
Authors: Beddow Toni A. , Leeuwen Johan L. Van , Johnston Ian A. 
Published: April 2021

ABSTRACT
The swimming kinematics of prey capture was studied in short-horned sculpin (Myoxocephalus scorpius L.) acclimated for 6–8 weeks to either 5 °C or 15 °C (12h:12h light:dark) using 15 °C-acclimated shrimps as prey. Fish acclimated to 5 °C remained interested in feeding following an acute rise in temperature to 15 °C over 12 h. Prey capture was a stereotyped behaviour consisting of stalking and stationary phases, followed by an S-shaped fast-start (stage 1), a propulsive stroke (stage 2) and a glide of variable duration during which the mouth was expanded and protruded to suck in the prey (stage 3). The duration of the preparatory stroke (half tail-beat, stage 1) was significantly shorter at 15 °C (48.8 ms) than at 5 °C (108.3 ms) in the 5 °C-acclimated sculpin (Q10=2.2). For 5 °C-acclimated fish, at 5 °C, the maximum values for acceleration and velocity along the path travelled by the fish were 16.2ms − and 0.8 ms−1 respectively. Both variables were relatively independent of acute temperature change (Q10=1.1-1.2; P&gt;0.1). At 15 °C, the maximum velocity was 33 % higher and the tail-beat duration of the propulsive stroke was 37% shorter in 15 °C-acclimated than in 5 °C-acclimated fish. Both stride length and tail beat amplitude were significantly higher (28 and 23 % respectively) in 15 °C-compared with 5 °C-acclimated sculpin at 15 °C. The results demonstrate plasticity in the major kinematic variables of fast-starts following warm acclimation sufficient to increase the percentage of successful attacks during prey capture from 23.2 to 73.4 %.
Longitudinal Variation in Mechanical Competence of Bone Along the Avian Humerus
Authors: Bonser Richard H. C. 
Published: April 2021

ABSTRACT
Vickers microhardness tests were used to gauge the mechanical ‘competence’ (ability to resist bending and failure) of cortical and trabecular bone along the humeri of three bird species. Hardness was greatest at the mid-length portion of the shaft. The mean hardness of trabeculae, where present, was between 78.7 and 90.9 % of that of the adjacent cortical bone. The possible causes of this are briefly discussed. Microhardness tests offer the opportunity to gauge differences in mechanical properties over small distances and might usefully be applied to test the homogeneity of mechanical properties within specimens for tensile or compressive tests.
Water and Carbon Dioxide Loss From the Cockroach Periplaneta Americana (L.) Measured Using Radioactive Isotopes
Authors: Noble-Nesbitt J. , Appel A. G. , Croghan P. C. 
Published: April 2021

ABSTRACT
Tritiated water (THO) loss from Periplaneta americana is used to measure cuticular permeability (Pd). In dry air, following various periods of predesiccation, the values of Pd lie around 0.5×10−9 m s-1, with the lowest values below 0.3×10−9 m s-1, close to the lowest permeabilities previously reported. There is no obvious relationship between permeability and initial mass of the insect. A significant lowering of Pd was found after 72 h of predesiccation. A marked sudden decrease in permeability occurred when the airstream flowing over an insect was changed from humid air to dry air. Labelling the bicarbonate pool using 14CO32- enabled the output of CO2 to be estimated. An average output of about 390 μl g-1 h-1 was found. Simultaneous measurement of THO and 14CO2 loss showed that tracheal water loss is only a small component of total water loss, with an average value of 3.8 %. The total water loss can therefore be used to make close estimates of cuticular permeability in Periplaneta americana. 2 min sampling periods clearly show the pulsatile nature of 14CO2 release but, even when the effect is most discernible, the periodic release of CO2 has only a small effect on water loss.
Pupil Adjustments in the Eye of the Common Backswimmer
Authors: Ro Alf-Inge , Nilsson Dan-E. 
Published: April 2021

ABSTRACT
The pupil mechanism in the acone apposition eye of the semi-aquatic common backswimmer Notonecta glauca (Hemiptera) was investigated with infrared reflectometry of the pseudopupil. This method allows non-invasive continuous measurements of pupil responses in the living animal. The dynamic range of the pupil sensitivity is about 7 log units during daytime and 6 log units at night. During the day, the sensitivity range of the pupil covers the normal daylight intensities in the animal’s habitat, just under the water surface (I50=1019.2 photons m−2 sr−1 s−1). At night, the sensitivity is 1 log unit lower (I50=1020.2 photons m−2 sr−1 s−1), ensuring that the pupil is maximally open when light intensities are low. During daytime, light adaptation is completed in slightly less than 40 min, and dark adaptation takes approximately 50 min. The pupil response is only slightly slower at night. The speed of the response as well as the pupil sensitivity are dependent on the preceding adaptation history. An endogenous circadian rhythm determines the control range of the pupil aperture. However, the rhythm is easily disturbed, especially within a 3 h period before dusk and dawn. The results are compared with corresponding results from other insects with the same type of pupil mechanism.