bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colour vision of domestic chicks
Authors: Osorio D. , Vorobyev M. , Jones C. D. 
Published: April 2021

ABSTRACT
The colour vision of domestic chicks (Gallus gallus) was investigated by training them to small food containers decorated with tilings of grey and coloured rectangles. Chicks learn to recognise the colour quickly and accurately. Chicks have four types of single-cone photoreceptor sensitive to ultraviolet, short-, medium- or long-wavelength light. To establish how these receptors are used for colour vision, stimuli were designed to be distinguished only by specific combinations of receptors. We infer (1) that all four single cones are used, and (2) that their outputs are encoded by at least three opponency mechanisms: one comparing the outputs of ultraviolet- and short-wavelength-sensitive receptors, one comparing the outputs of medium- and long-wavelength receptors and a third comparing of the outputs of short- and long- and/or medium-wavelength receptors. Thus, the chicks have tetrachromatic colour vision. These experiments do not exclude a role for the fifth cone type, double cones, but other evidence suggests that these cones serve luminance-based tasks, such as motion detection, and not colour recognition.
Processing of proprioceptive signals by ascending interneurones in the terminal abdominal ganglion of the crayfish
Authors: Aonuma Hitoshi , Newland Philip L. , Nagayama Toshiki 
Published: April 2021

ABSTRACT
Intersegmental interneurones are crucial for the appropriate coordination of the activity of local circuits located in different body segments. We have analysed the synaptic inputs to ascending intersegmental interneurones from a proprioceptor in the tailfan of the crayfish. Twenty identified interneurones responded during stimulation of the exopodite–endopodite chordotonal organ. Of these 20 interneurones, three were excited phaso-tonically, nine were excited phasically and eight were inhibited. All received convergent exteroceptive inputs from water-motion- or touch-sensitive hairs on the uropods. The effects of simultaneous exteroceptive and proprioceptive stimulation depended upon the identity of an interneurone. For interneurones that were inhibited by proprioceptive stimulation, suprathreshold exteroceptive responses were reduced to a subthreshold level by simultaneous proprioceptive stimulation. In contrast, for interneurones that were excited by proprioceptive stimulation, the simultaneous application of subthreshold proprioceptive and exteroceptive stimulation elicited action potentials.
Two of the interneurones that receive proprioceptive input (NE-1 and RC-8) are known to be presynaptic to giant interneurones that mediate and coordinate the tail-flip. Many of the other interneurones that receive proprioceptive inputs in the tailfan are known to excite abdominal extensor motor neurones. Thus, proprioceptive input to these intersegmental interneurones could serve two roles: first, to extend the abdomen during postural movements or prior to escape and, second, to drive the tail-flip escape response.
Placental nutrition in the viviparous lizard Niveoscincus metallicus: the influence of placental type
Authors: Thompson Michael B. , Speake Brian K. , Stewart James R. , Russell Kylie J. , McCartney Ruth J. , Surai Peter F. 
Published: April 2021

ABSTRACT
The ion, energy, lipid, nitrogen and fat-soluble vitamin contents of freshly ovulated eggs and neonates of the viviparous lizard Niveoscincus metallicus were measured to quantify uptake of nutrients across the placenta. This species is particularly interesting because it has a chorio–allantoic placenta that is intermediate in complexity compared to viviparous species that have been the focus of other studies. Newly ovulated eggs have a wet mass of 79.6±4.6 mg and a dry mass of 41.8±2.8 mg, compared to the neonates that have a wet mass of 224.2±8.2 mg and dry mass of 37.9±1.2 mg. Thus, there is no significant net uptake of dry matter across the placenta. Neonates have significantly less lipid (6.2±0.4 mg) than eggs (12.7±0.5 mg), but no significant difference in nitrogen (4.1±0.3 mg) compared to eggs (4.5±0.2 mg). Energy densities reflect the protein and lipid composition and the relative dry masses of the eggs and neonates. There is significantly more energy (1029.1±80.0 J) in the egg than in the neonate (858.2±38.6 J). The increase in the ash content of the neonates (2.9±0.2 mg) compared to fresh eggs (2.1±0.3 mg) was not significant, even though there was an approximately threefold increase in the amount of sodium (0.11±0.01 mg in neonates, 0.34±0.01 mg in eggs) and potassium (0.12±0.017 in neonates, 0.40±0.01 mg in eggs) in neonates compared to eggs. There was no significant uptake of calcium and magnesium during development. The egg lipids consisted of triacylglycerol (66.7±2.3 %), phospholipid (18.9±0.7 %), cholesteryl ester (4.9±1.6 %) and free cholesterol (5.6±1.5 %). The egg phospholipid contained comparatively high proportions of arachidonic and eicosapentanoic acids but low levels of docosahexaenoic acid (DHA), whereas the phospholipid of the neonate was greatly enriched in DHA. In the egg, the predominant vitamin E was α-tocopherol (62.6±3.4 mg g−1), although there was some γ-tocotrienol (3.5±0.3 mg g −1), and vitamin A was present (1.5±0.2 mg g−1). The ratio of neonate dry mass to egg dry mass of N. metallicus (0.91) lies between that of species with type I (0.78) and type III (1.70) chorio–allantoic placentae, confirming our conclusion that the placenta of N. metallicus is functionally intermediate, as well as intermediate in complexity, between these other two types.
Effects of zinc on L-[3H]proline uptake by lobster (Homarus americanus) hepatopancreatic brush-border membrane vesicles
Authors: Monteilh-Zoller Mahealani K. , Zonno Vincenzo , Storelli Carlo , Ahearn Gregory A. 
Published: April 2021

ABSTRACT
Epithelial brush-border membrane vesicles (BBMVs) from the hepatopancreas of the lobster Homarus americanus were prepared using a magnesium precipitation technique and employed in transport experiments designed to demonstrate the effects of external and internal divalent cationic heavy metals on the uptake of L-[3H]proline. When BBMVs were exposed to a high external concentration (2.5 mmol l−1) of Cd2+, Cu2+, Fe2+, Mn2+ or Zn2+, L-[3H]proline (0.5 mmol l−1) uptake was significantly (P&lt;0.05) decreased by each metal. However, if a 30 min pre-incubation period with each metal was used before incubation of the vesicles with amino acid and metal, a significant (P&lt;0.05) enhancement of L-[3H]proline transport occurred. Zinc was the most stimulatory metal of those tested. Proline influxes (1.0 and 2.5 mmol l−1) were hyperbolic functions of bilateral [Zn2+], with a lower apparent zinc half-saturation constant (Km) at the higher amino acid concentration. L-[3H]proline influx was a hyperbolic function of external [L-proline] (Km=2.10±0.26 mmol l−1; Jmax=2290±600 pmol mg−1 protein 10 s−1) (means ± S.E.M., N=3), and bilateral exposure to zinc significantly (P&lt;0.05) increased the maximal rate of influx, Jmax, of proline (Jmax=4890±250 pmol mg−1 protein 10 s−1), but had no effect (P&gt;0.05) on apparent L-[3H]proline binding to the membranes (Km=1.66±0.23 mmol l−1) (means ± S.E.M., N=3). In the presence of 0.5 mmol l−1 l-pipecolate, bilateral zinc-stimulated, carrier-mediated, L-[3H]proline influx was abolished. At low external concentrations of zinc alone (e.g. below 1.0 mmol l−1), L-[3H]proline influx was enhanced by the metal. Enhanced amino acid uptake in the presence of external zinc alone was abolished by L-pipecolate. A model accounting for external and internal zinc enhancements of L-[3H]proline influx by the Na+-dependent L-pipecolate-sensitive IMINO transport system in these membranes is proposed.
The supramolecular organisation of fibrillin-rich microfibrils determines the mechanical properties of bovine zonular filaments
Authors: Wright D. M. , Duance V. C. , Wess T. J. , Kielty C. M. , Purslow P. P. 
Published: April 2021

ABSTRACT
The zonular filaments from the eyes of cows are rich in microfibrils containing fibrillin. Tensile tests, stress-relaxation tests and X-ray diffraction studies were used to study the relationship between the mechanical behaviour of zonular filaments and the molecular packing and structure of the fibrillin-rich microfibrils. Zonular filaments show a non-linear (J-shaped) stress–strain curve and appreciable stress-relaxation. It is proposed that the non-linear properties are due to local variations in waviness in the microfibrils or assemblies of microfibrils, which straighten out and become more regularly aligned with strain. Previous and current X-ray diffraction results consistently show a partial ordering of microfibrils in zonular filaments into staggered aggregates which become more ordered and laterally aligned on stretching. Although the removal and re-addition of Ca2+ is known to change the molecular structure of fibrillin, no effect was observed on the tensile properties of the zonular filaments. It is hypothesised that strain-induced deformation in the supramolecular aggregate packing may not be Ca2+-sensitive but could dominate the mechanical behaviour of microfibrillar arrays in zonular filaments.
The hormonal coordination of behavior and physiology at adult ecdysis in Drosophila melanogaster
Authors: Baker James D. , McNabb Susan L. , Truman James W. 
Published: April 2021

ABSTRACT
In insects, ecdysis is thought to be controlled by the interaction between peptide hormones; in particular between ecdysis-triggering hormone (ETH) from the periphery and eclosion hormone (EH) and crustacean cardioactive peptide (CCAP) from the central nervous system. We examined the behavioral and physiological functions of the first two of these peptides in Drosophila melanogaster using wild-type flies and knockout flies that lacked EH neurons. We used ETH from Manduca sexta (MasETH) to induce premature ecdysis and compared the responses of the two types of flies.
The final release of EH normally occurs approximately 40 min before ecdysis. It is correlated with cyclic guanosine monophosphate (cGMP) production in selected neurons and tracheae, by an elevation in the heart rate and by the filling of the new tracheae with air. Injection of developing flies with MasETH causes all these events to occur prematurely. In EH cell knockouts, none of these changes occurs in response to MasETH, and these flies show a permanent failure in tracheal filling. This failure can be overcome in the knockouts by injecting them with membrane-permeant analogs of cGMP, the second messenger for EH.
The basis for the 40 min delay between EH release and the onset of ecdysis was examined by decapitating flies at various times relative to EH release. In flies that had already released EH, decapitation was always followed within 1 min by the start of ecdysis. Immediate ecdysis was never observed when the EH cell knockout flies were decapitated. We propose that EH activates both ventral central nervous system elements necessary for ecdysis (possibly the CCAP cells) and descending inhibitory neurons from the head. This descending inhibition establishes a delay in the onset of ecdysis that allows the completion of EH-activated physiological processes such as tracheal filling. A waning in the inhibition eventually allows ecdysis to begin 30–40 min later.
Primitive organization of cytosolic Ca2+ signals in hepatocytes from the little skate Raja erinacea
Authors: Nathanson Michael H. , O’Neill Allison Fa. , Burgstahler Angela D. 
Published: April 2021

ABSTRACT
Cytosolic Ca2+ (Cai2+) signals begin as polarized, inositol 1,4,5-trisphosphate (InsP3)-mediated Cai2+ waves in mammalian epithelia, and this signaling pattern directs secretion together with other cell functions. To investigate whether Cai2+ signaling is similarly organized in elasmobranch epithelia, we examined Cai2+ signaling patterns and InsP3 receptor (InsP3R) expression in hepatocytes isolated from the little skate, Raja erinacea. Cai2+ signaling was examined by confocal microscopy, InsP3R expression by immunoblot, and the subcellular distribution of InsP3Rs by immunochemistry. ATP induced a rapid increase in Cai2+ in skate hepatocytes, as it does in mammalian hepatocytes. Unlike in mammalian hepatocytes, however, the Cai2+ increase in skate hepatocytes began randomly throughout the cell rather than in the apical region. In cells loaded with heparin ATP-induced Cai2+ signals were inhibited, but de-N-sulfated heparin was not inhibitory, suggesting that the increases in Cai2+ were mediated by InsP3. Immunoblot analysis showed that the type I but not the types II or III InsP3R was expressed in skate liver. Confocal immunofluorescence revealed that the InsP3R was distributed throughout the hepatocyte, rather than concentrated apically as in mammalian epithelia. These findings demonstrate that ATP-induced Cai2+ signals are mediated by InsP3 in skate hepatocytes, as they are in mammalian hepatocytes. However, in skate hepatocytes Cai2+ signals begin at loci throughout the cell rather than as an organized apical-to-basal Cai2+ wave, which is probably because the InsP3R is distributed throughout these cells. This primitive organization of Cai2+ signaling may in part explain the observation that Ca2+-mediated events such as secretion occur much less efficiently in elasmobranchs than in mammals.
The effects of intensity on the energetics of brief locomotor activity
Authors: Baker Emily J. , Gleeson Todd T. 
Published: April 2021

ABSTRACT
The energetic costs associated with locomotion are often estimated only from the energy expended during activity and do not include the costs incurred during recovery. For some types of locomotion, this method overlooks important aspects of the metabolic costs incurred as a result of the activity. These estimates for energetic cost have also been predicted from long-duration, low-intensity activities that do not necessarily reflect all the behavior patterns utilized by animals in nature. We have investigated the effects of different activity intensities on the metabolic expenditure (per unit distance traveled) associated with brief exercise, and offer a more inclusive analysis of how the energetics of short-duration activities might be analyzed to estimate the costs to the animal. Mice ran on a treadmill for 15 or 60 s at 25 %, 50 % or 100 % of maximum aerobic speed (MAS) while enclosed in an open-flow respirometry system. Following the run, each mouse was allowed to recover while remaining enclosed in the respirometry chamber. Excess exercise oxygen consumption (EEOC), the excess volume of oxygen consumed during the exercise period, increased with the duration and increased linearly with the intensity of exercise. In contrast, the volume of oxygen consumed during the recovery period, or excess post-exercise oxygen consumption (EPOC), was independent of exercise intensity and duration and accounted for more than 90 % of the total metabolic cost. The net cost of activity (Cact), calculated by summing EEOC and EPOC and then dividing by the distance run, increased as both activity duration and intensity decreased. The values for Cact ranged from 553 ml O2 g−1 km−1 for a 15 s run at 25 % MAS to 43 ml O2 g−1 km−1 for a 60 s run at 100 % MAS. Combining these data with data from a companion paper, we conclude (1) that EPOC is independent of both the duration and intensity of activity when exercise duration is brief in mice, (2) that EPOC accounts for a majority of the oxygen consumed as a result of the activity when exercise durations are short, and (3) that animals can minimize their energy expenditure per unit distance by running faster for a longer period.
Precise monitoring of porpoising behaviour of Adelie penguins determined using acceleration data loggers
Authors: Yoda K. , Sato K. , Niizuma Y. , Kurita M. , Bost C.-A. , Maho Y. LE , Naito Y. 
Published: April 2021

ABSTRACT
A new method using acceleration data loggers enabled us to measure the porpoising behaviour of Adélie penguins (Pygoscelis adeliae), defined as a continuous rapid swimming with rhythmic serial leaps. Previous hydrodynamic models suggested that leaping would be energetically cheaper when an animal swims continuously at depths of less than three maximum body diameters below the water surface. In the present study, free-ranging Adélie penguins leapt at a mean speed of 2.8 m s−1 above the predicted threshold speed (0.18–1.88 m s−1). Wild penguins reduced drag by swimming deeper (0.91 m) and did not swim continuously within the high-drag layer while submerged. This indicates that previous calculations may be incomplete. Moreover, leaps represented an average of only 3.8 % of the total distance travelled during the porpoising cycle, which would make energy savings marginal. Among the six penguins used in our study, two did not porpoise and three porpoised for less than 7 min, also indicating that this behaviour was not important during travel to and from foraging sites, as has been previously suggested. Birds mainly porpoised at the start and end of a trip. One explanation of porpoising might be an escape behaviour from predators.
Accommodation in the cuttlefish (Sepia officinalis)
Authors: Schaeffel Frank , Murphy Christopher J. , Howland Howard C. 
Published: April 2021

ABSTRACT
We have studied natural accommodation in the eye of six specimens of cuttlefish (Sepia officinalis) as they were fed with fish and shrimp. Using infrared photoretinoscopy, we observed (1) that the resting refractive state of the cuttlefish was emmetropic or slightly hyperopic, (2) that accommodation took place only a fraction of a second before a strike and (3) that accommodation focused selectively only in the frontal visual field while no change in refraction could be measured in the lateral field of view. Accommodation was bilateral and amounted to approximately 5 diopters (the reciprocal of the focal length expressed in meters). Simultaneously, the eyes converged. It appears that, as in most teleost fishes, accommodation in the cuttlefish involves a movement of the crystalline lens perpendicular to the axis of the eye. In histological sections, we observed the position and arrangement of the ciliary muscles, confirming earlier anatomical descriptions, and developed a model of how accommodation could be achieved.
Flight-muscle adenylate pool responses to flight demands and thermal constraints in individual Colias eurytheme (Lepidoptera, pieridae)
Authors: Kohane Michael J. , Watt Ward B. 
Published: April 2021

ABSTRACT
We study here the connections among body temperature variation, flight performance and flight ‘fuel’ metabolism in Colias eurytheme butterflies, to begin re-examining the metabolic reasons for animal thermoregulation. Methods are presented for (a) stable extraction of adenylates (and other metabolites) from the flight muscles of individual Colias eurytheme, (b) automated separation and quantitative analysis of individual adenylate samples by high-pressure liquid chromatography and (c) reliable, low-variance assay of inorganic phosphate levels in the same extracts. Correlations among metabolite concentrations and two indices of muscle cytosol ATP maintenance occur as expected on general metabolic principles. [ATP] and [ATP]/[ADP] decline from resting levels to reach a plateau in the first minute of free, interrupted flight, while [AMP] increases at the same time; these concentrations do not vary further for up to 6 min total flight time. In an initial test of the alternative metabolic bases of the thermoregulation of Colias eurytheme, we find that [ATP]/[ADP] rises between a body temperature, Tb, of 31 and 35 °C, at the base of the behavioral thermal optimum for flight, but then decreases again at Tb=39 °C, at the top of the behavioral thermal optimum and well short of damaging temperatures. This is not consistent with the view that metabolic effectiveness increases monotonically up to the lower limits of thermal damage to enzymes, but supports an alternative hypothesis that the narrowness of thermoregulation results from a system-based constraint on the breadth of temperature over which maximal energy processing is possible.
‘Data on the biochemistry of insect thermoregulation are extremely scanty.’
G. A. Bartholomew (1987)
Temperature-dependence of neuronal performance in the motion pathway of the blowfly calliphora erythrocephala
Authors: Warzecha Anne-Kathrin , Horstmann Wolfram , Egelhaaf Martin 
Published: April 2021

ABSTRACT
Raising the head temperature within a behaviourally relevant range has strong effects on the performance of an identified neuron, the H1 neuron, in the visual motion pathway of blowflies. The effect is seen as an increase in the mean amplitude of the responses to motion under both transient and steady-state conditions, a considerable decrease in the response latency and an improvement in the reliability of the responses to motion. These temperature-dependent effects are independent of whether the animal is exposed to transient temperature changes or is maintained continuously at the same temperature for its entire life. The changes in the neuronal response properties with temperature may be of immediate functional significance for the animal under its normal operating conditions. In particular, the decrease in latency and the improvement in the reliability with increasing temperature may be relevant for the fly when executing its extremely virtuosic flight manoeuvres.
Phenotypic flexibility of the avian gizzard: rapid, reversible and repeated changes of organ size in response to changes in dietary fibre content
Authors: Starck J. Matthias 
Published: April 2021

ABSTRACT
Evolutionary biology presumes that organ capacities match their natural loads. Therefore, in fluctuating conditions, organ systems are expected to show a reversible, repeatable and rapid phenotypic response that is directional and scaled. In this study, phenotypic responses of the gizzard of adult Japanese quail (Coturnix japonica) to experimental mismatches of load and capacity were tested by a series of diet-switching experiments, involving an increased content of non-digestable fibre (NDF) in the diet. The results of all experiments were in accordance with the predictions of the hypothesis that there is matching between loads and capacities. (1) The observed phenotypic responses are directional and scaled to the demands, i.e. increasing NDF elicits an increase in gizzard size. When the proportion of NDF in the diet was raised from 1 % to 45 %, the gizzard was more than twice as large as in the control group. (2) Size responses were reversible, and reduced NDF was followed by a decrease of gizzard size. (3) Phenotypic responses could be elicited repeatedly in three successive trials. (4) Excess capacities were downregulated and insufficient capacities were upregulated. (5) The responses followed changes of loads with almost no time lag, with size changes measurable within 24 h.