bluuebunny/crossref_metadata_2025_split huggingface dataset:
Power Production During Steady Swimming in Largemouth Bass and Rainbow Trout
Authors: Coughlin David J. 
Published: April 2021

ABSTRACT
Steady swimming in fishes is powered by the aerobic or red muscle, but there are conflicting theories on the relative roles of the anterior and posterior red muscle in powering steady swimming. To examine how red muscle is used to power steady swimming in rainbow trout (Oncorhynchus mykiss), electromyographic (EMG) and sonomicrometry recordings were made of muscle activity in vivo. These data were used in in vitro work-loop studies of muscle power production. Data on in vitro power production were also collected for largemouth bass (Micropterus salmoides) red muscle from previously published data on in vivo muscle activity. The in vivo data collected from swimming trout were similar to those for other species. The anterior red muscle of these fish has the longest duty cycle, the smallest phase shift between the onset of EMG activity and maximum muscle length during each tailbeat and undergoes the smallest strain or length change. For both trout and largemouth bass, work-loop experiments indicate that the majority of power for steady swimming is generated by the posterior muscle, as has been observed in other species.
Pinpointing Food Sources: Olfactory and Anemotactic Orientation in Desert Ants, Cataglyphis Fortis
Authors: Wolf Harald , Wehner Rüdiger 
Published: April 2021

ABSTRACT
Desert ants, Cataglyphis fortis, search for a repeatedly visited food source by employing a combined olfactory and anemotactic orientation strategy (in addition to their visually based path-integration scheme). This behaviour was investigated by video-tracking consecutive foraging trips of individually marked ants under a variety of experimental conditions, including manipulations of the olfactory and wind-detecting systems of the ants. If the wind blows from a constant direction, ants familiar with the feeding site follow outbound paths that lead them into an area 0.5–2.5 m downwind of the feeding station. Here, the ants apparently pick up odour plumes emanating from the food source and follow these by steering an upwind course until they reach the feeder. If the food is removed, foragers usually concentrate their search movements within the area downwind of the feeding site. Only when the wind happens to subside or when tail-wind conditions prevail do the ants steer direct courses towards the food.
Elimination of olfactory input by clipping the antennal flagella, or of wind perception by immobilising the bases of the antennae, altered the foraging behaviour of the ants in ways that supported these interpretations. Ants with clipped flagella were never observed to collect food items.
Energy Storage by Passive Elastic Structures in the Mantle of Sepia Officinalis
Authors: Curtin N. A. , Woledge R. C. , Bone Q. 
Published: April 2021

ABSTRACT
The passive elastic properties of the mantle of the cuttlefish Sepia officinalis have been characterized in experiments on intact mantle and on pieces cut from the mantle. The mantle was found to be very compliant over a wide range of circumferential strains, corresponding to a change in mantle circumferential strain of 0.45. Beyond this range of strain, the mantle was much stiffer, in both the circumferential direction, 0.542±0.025 MPa (mean ± S.E.M., N=51) and through the thickness of the mantle wall, 0.152±0.041 MPa (N=11). Almost 80 % of the work done on the tissue during compression in the circumferential direction was recovered during elastic recoil of the tissue; this elastic work could contribute to refilling the mantle after a jet. Our estimates of the work done during a cycle of jetting and refilling show that such elastic work is small (approximately 1 %) compared with the contractile work done by the circular muscle fibres. However, although the elastic work is almost negligible in the overall energy budget, it is probably sufficient to power refilling of the mantle.
Continuous Measurements of Instantaneous Heart Rate and its Fluctuations Before and After Hatching in Chickens
Authors: Moriya K. , Pearson J. T. , Burggren W. W. , Ar A. , Tazawa H. 
Published: April 2021

ABSTRACT
There has been considerable interest in heart rate (fH) fluctuations in relation to cardiovascular control systems and foetal conditions during pregnancy in mammals. Prominent fluctuations in fH also occur in avian embryos, which are an important experimental model for studying developmental physiology. The present study determined the instantaneous fH of seven chick embryos continuously from the last stage of prenatal development (day 18), throughout the pipping (perinatal) period (days 19–21) until hatching and, subsequently, of newly hatched chicks (up to day 2).
The distinctive patterns of instantaneous fH fluctuations took the form of specific changes within a broad mean fH baseline. Cyclic oscillations (ultradian rhythm) occurred until an early stage of the perinatal period, when the fH baseline started rising. Subsequently, the baseline dropped and respiratory arrhythmia began to appear concomitant with external pipping. During the final stage of external pipping, when the fH baseline rose again prior to hatching, three unique patterns of instantaneous fH fluctuations were evident: relatively long-lasting cyclic small accelerations, irregular intermittent large accelerations and short-term repeated large accelerations. Furthermore, repeated alternate occurrences of the latter two types of acceleration formed an additional oscillating pattern with a period of 10–15 min.
During the early period after hatching, when the fH baseline reached its maximum, instantaneous fH changed relatively slowly accompanied by transient rapid decelerations, probably due to augmented vagal tone. Subsequently, the mean fH baseline dropped to its minimum, and a circadian rhythm and three types of previously reported fH fluctuations (types I–III) appeared.
Developmental patterns of mean fH and the appearance of distinctive patterns of instantaneous fluctuations in fH and circadian rhythms were not influenced by an ultimate failure of hatching after a normal development.
The demonstration of complex, repeatable patterns of fH fluctuation that change during development suggests that the avian embryo model should be useful in studying the phenomenon of fH fluctuation and its underlying causes.
Mitochondrial Function in Flying Honeybees (Apis Mellifera): Respiratory Chain Enzymes and Electron Flow from Complex III to Oxygen
Authors: Suarez R. K. , Staples J. F. , Lighton J. R. B. , Mathieu-Costello O. 
Published: April 2021

ABSTRACT
The biochemical bases for the high mass-specific metabolic rates of flying insects remain poorly understood. To gain insights into mitochondrial function during flight, metabolic rates of individual flying honeybees were measured using respirometry, and their thoracic muscles were fixed for electron microscopy. Mitochondrial volume densities and cristae surface densities, combined with biochemical data concerning cytochrome content per unit mass, were used to estimate respiratory chain enzyme densities per unit cristae surface area. Despite the high content of respiratory enzymes per unit muscle mass, these are accommodated by abundant mitochondria and high cristae surface densities such that enzyme densities per unit cristae surface area are similar to those found in mammalian muscle and liver. These results support the idea that a unit area of mitochondrial inner membrane constitutes an invariant structural unit. Rates of O2 consumption per unit cristae surface area are much higher than those estimated in mammals as a consequence of higher enzyme turnover rates (electron transfer rates per enzyme molecule) during flight. Cytochrome c oxidase, in particular, operates close to its maximum catalytic capacity (kcat). Thus, high flux rates are achieved via (i) high respiratory enzyme content per unit muscle mass and (ii) the operation of these enzymes at high fractional velocities.
Sustained Swimming at Low Velocity Following a Bout of Exhaustive Exercise Enhances Metabolic Recovery in Rainbow Trout
Authors: Milligan C. Louise , Hooke G. Brian , Johnson Crystal 
Published: April 2021

ABSTRACT
Sustained swimming at 0.9 BL s−1, where BL is fork body length, following a bout of exhaustive exercise enhanced recovery of metabolite and acid–base status in rainbow trout compared with fish held in still water. The most striking effect of an active recovery was a total absence of the elevation cortisol concentration typically associated with exhaustive exercise. In fish swimming at 0.9 BL s−1, plasma cortisol levels averaged 20–25 ng ml−1 throughout the 6 h recovery period. In contrast, plasma cortisol increased to a peak level of 128.4±11.2 ng ml−1 (mean ± S.E.M., N=6) in fish recovering in still water. Muscle glycogen was completely resynthesized and lactate cleared within 2 h of exercise in swimming fish compared with more than 6 h required in the fish held in still water. Similarly, blood lactate level and acid–base status were restored more quickly in the swimming fish. These observations suggest that the prolonged recovery usually associated with exhaustive exercise in rainbow trout is due to elevations in plasma cortisol concentration and that the stimulus for cortisol release is not exercise per se, but rather post-exercise inactivity.
Oxygen-Dependent Energetics of Anoxia-Tolerant and Anoxia-Intolerant Hepatocytes
Authors: Krumschnabel Gerhard , Schwarzbaum Pablo J. , Lisch Johannes , Biasi Christina , Wieser Wolfgang 
Published: April 2021

ABSTRACT
The oxygen-dependence of cellular energetics was investigated in hepatocytes from goldfish Carassius auratus (anoxia-tolerant) and rainbow trout Oncorhynchus mykiss (anoxia-intolerant). In goldfish hepatocytes, an approximately 50 % reduction in the rate of oxygen consumption was observed in response to both acute and prolonged hypoxia, the latter treatment shifting the threshold for this reduction to a higher oxygen level. A concomitant increase in the rate of lactate production did not compensate for the decreased aerobic ATP supply, resulting in an overall metabolic depression of 26 % during acute hypoxia and of 42 % during prolonged hypoxia. Trout hepatocytes showed a similar suppression of cellular respiration after prolonged hypoxia but were unresponsive to acute hypoxia. Similarly, the rate of lactate production was unaltered during acute hypoxia but was increased during prolonged hypoxia, metabolic depression amounting to 7 % during acute hypoxia and 30 % during prolonged hypoxia. In both species, the affinity of hepatocytes for oxygen decreased during hypoxia, but this alteration was not sufficient in absolute terms to account for the observed decrease in aerobic ATP supply. Protein synthesis was suppressed in both cell types under hypoxia, whereas Na+/K+-ATPase activity decreased in trout but not in goldfish hepatocytes, emphasising the importance of membrane function in these cells during conditions of limited energy supply.
The Ontogeny of Metabolic Rate and Thermoregulatory Capabilities of Northern Fur Seal, Callorhinus Ursinus, Pups in Air and Water
Authors: Donohue M. J. , Costa D. P. , Goebel M. E. , Baker J. D. 
Published: April 2021

ABSTRACT
Young pinnipeds, born on land, must eventually enter the water to feed independently. The aim of this study was to examine developmental factors that might influence this transition. The ontogeny of metabolic rate and thermoregulation in northern fur seal, Callorhinus ursinus, pups was investigated at two developmental stages in air and water using open-circuit respirometry. Mean in-air resting metabolic rate (RMR) increased significantly from 113±5 ml O2 min−1 (N=18) pre-molt to 160±4 ml O2 min−1 (N=16; means ± S.E.M.) post-molt. In-water, whole-body metabolic rates did not differ pre- and post-molt and were 2.6 and 1.6 times in-air RMRs respectively. Mass-specific metabolic rates of pre-molt pups in water were 2.8 times in-air rates. Mean mass-specific metabolic rates of post-molt pups at 20 °C in water and air did not differ (16.1±1.7 ml O2 min−1 kg−1; N=10). In-air mass-specific metabolic rates of post-molt pups were significantly lower than in-water rates at 5 °C (18.2±1.1 ml O2 min−1 kg−1; N=10) and 10 °C (19.4±1.7 ml O2 min−1 kg−1; N=10; means ± S.E.M.). Northern fur seal pups have metabolic rates comparable with those of terrestrial mammalian young of similar body size. Thermal conductance was independent of air temperature, but increased with water temperature. In-water thermal conductance of pre-molt pups was approximately twice that of post-molt pups. In-water pre-molt pups matched the energy expenditure of larger post-molt pups while still failing to maintain body temperature. Pre-molt pups experience greater relative costs when entering the water regardless of temperature than do larger post-molt pups. This study demonstrates that the development of thermoregulatory capabilities plays a significant role in determining when northern fur seal pups enter the water.
Sulphaemoglobin Formation in Fish: A Comparison Between the Haemoglobin Of the Sulphide-Sensitive Rainbow Trout (Oncorhynchus Mykiss) and of the Sulphide-Tolerant Common Carp (Cyprinus Carpio)
Authors: Völkel Susanne , Berenbrink Michael 
Published: April 2021

ABSTRACT
A method for the quantitative determination of sulphaemoglobin (SHb) in a mixture of haemoglobin derivatives by spectral deconvolution is described. SHb formation was studied in haemolysates and in red blood cells of the sulphide-sensitive rainbow trout (Oncorhynchus mykiss) and of the sulphide-tolerant common carp (Cyprinus carpio). Addition of sulphide caused the formation of SHb in haemolysates of both animals. However, haemoglobin from common carp was much less sensitive to sulphide than was trout haemoglobin. The maximal obtainable SHb fraction was approximately 30 % in trout and 10 % in carp haemolysates. In both animals, the SHb fraction increased with increasing Hb and sulphide concentrations up to 100 μmol l−1 and 1 mmol l−1, respectively, and was favoured by a low pH. An increase of temperature between 5 and 25 °C strongly increased SHb formation in trout haemolysate. In contrast, temperature changes had almost no effect on SHb production in carp. Within trout red blood cells, approximately 7 % of total haemoglobin was converted to SHb during 60 min of incubation (with 2.5 mmol l−1 sulphide), inducing a 20 % loss of haemoglobin oxygen-saturation. In carp red blood cells incubated under identical conditions, SHb formation was minimal and haemoglobin oxygen-saturation was not affected.
Physical and Physiological Components Of The Graviresponses Of Wild-Type and Mutant Paramecium Tetraurelia
Authors: Nagel Ute , Machemer Hans 
Published: April 2021

ABSTRACT
Wild-type and the morphological mutant kin 241 of Paramecium tetraurelia showed improved orientation away from the centre of gravity (negative gravitaxis) when accelerations were increased from 1 to 7 g. Gravitaxis was more pronounced in the mutant. A correlation between the efficiency of orientation and the applied g value suggests a physical basis for gravitaxis. Transiently enhanced rates of reversal of the swimming direction coincided with transiently enhanced gravitaxis because reversals occurred more often in downward swimmers than in upward swimmers. The results provide evidence of a physiological modulation of gravitaxis by means of the randomizing effect of depolarization-dependent swimming reversals. Gravity bimodally altered propulsion rates of wild-type P. tetraurelia so that sedimentation was partly antagonized in upward and downward swimmers (negative gravikinesis). In the mutant, only increases in propulsion were observed, although the orientation-dependent sensitivity of the gravikinetic response was the same as in the wild-type population. Observed swimming speed and sedimentation rates in the wild-type and mutant cells were linearly related to acceleration, allowing the determination of gravikinesis as a linear (and so far non-saturating) function of gravity.
The Electrical Properties of the Anterior Stomach of the Larval Mosquito (Aedes Aegypti)
Authors: Clark Thomas M. , Koch Alan , Moffett David F. 
Published: April 2021

ABSTRACT
The electrical properties of the anterior stomach of the larval mosquito (Aedes aegypti) were determined. At late times after cannulation, the intraluminal space constant was 936 μm, which is almost as long as the isolated tissue itself. At this time, the resistance of the apical cell membranes dominates the transcellular resistance; it is approximately 14 times the resistance of the basal cell membrane. Two physiologically distinct epithelial cell types were identified. One type has a stable basal potential of approximately 65 mV and responds to 5-hydroxytryptamine with hyperpolarization. The second cell type initially shows a basal potential of 100 mV. However, this basal potential decays in the first few minutes in parallel with the decay of the transintestinal potential. This latter cell type does not respond to 5-hydroxytryptamine.
Directional Hearing of a Grasshopper in the Field
Authors: Gilbert Friederike , Elsner Norbert 
Published: April 2021

ABSTRACT
An electrophysiological method for making long-term recordings from the tympanal nerve was developed in Chorthippus biguttulus (Gomphocerinae) to gain insight into the ecophysiological constraints of sound localization in acridid grasshoppers. Using this ‘biological microphone’, the directional dependence of auditory nerve activity was monitored both in the laboratory and in various natural habitats of this species. On gravel and in sparse vegetation, the overall patterns of directionality were found to be very similar to those in the free sound field in the laboratory, regardless of whether the animal was positioned horizontally or vertically. However, the differences between the ipsi- and contralateral sides were smaller in these habitats than in the laboratory. In dense vegetation, the directional patterns were greatly affected by the environment. Moreover, a minimum in nerve activity was not always reached on the contralateral side, as is typical for the free sound field situation. On the basis of these data, predictions can be made about the ability of the animals to determine the correct side of a sound source. In the free sound field of the laboratory, correct lateralizations are expected at all angles of sound incidence between 20 and 160 °, a prediction corresponding to the results of behavioural studies. In sparse vegetation, a similar accuracy can be anticipated, whereas on gravel and in dense vegetation directional hearing is expected to be severely degraded, especially if the animal is oriented horizontally. The predictions from our present electrophysiological investigations must now be confirmed by behavioural studies in the field.
Depression of Nuclear Transcription and Extension of mRNA Half-Life Under Anoxia in Artemia Franciscana Embryos
Authors: Breukelen Frank Van , Maier Ryan , Hand Steven C. 
Published: April 2021

ABSTRACT
Transcriptional activity, as assessed by nuclear run-on assays, was constant during 10 h of normoxic development for embryos of the brine shrimp Artemia franciscana. Exposure of embryos to only 4 h of anoxia resulted in a 79.3±1 % decrease in levels of in-vivo-initiated transcripts, and transcription was depressed by 88.2±0.7 % compared with normoxic controls after 24 h of anoxia (means ± S.E.M., N=3). Initiation of transcription was fully restored after 1 h of normoxic recovery. Artificially lowering the intracellular pH of aerobic embryos to the value reflective of anoxia (pH 6.7) showed that acidification alone explained over half the transcriptional arrest. Initiation of transcription was not rescued by application of 80 % carbon monoxide under anoxia, which suggests that heme-based oxygen sensing is not involved in this global arrest.
When these transcriptional data are combined with the finding that mRNA levels are unchanged for at least 6 h of anoxia, it is clear that the half-life of mRNA is extended at least 8.5-fold compared with that in aerobic embryos. In contrast to the activation of compensatory mechanisms to cope with anoxia that occurs in mammalian cells, A. franciscana embryos enter a metabolically depressed state in which gene expression and mRNA turnover are cellular costs apparently not compatible with survival and in which extended tolerance supercedes the requirement for continued metabolic function.
The Ontogeny of Ultraviolet Sensitivity, Cone Disappearance and Regeneration in the Sockeye Salmon Oncorhynchus Nerka
Authors: Flamarique Iñigo Novales 
Published: April 2021

ABSTRACT
This study examines the spectral sensitivity and cone topography of the sockeye salmon Oncorhynchus nerka throughout its life history with special emphasis on ultraviolet sensitivity. Electrophysiological recordings from the optic nerve show that ultraviolet sensitivity is greatly diminished at the smolt stage but reappears in adult fish weighing about 201 g. Concomitantly, light microscopy observations of the retina show that ultraviolet cones disappear from the dorsal and temporal retina at the smolt stage but reappear at the adult stage. These changes occur for sockeye salmon raised in fresh water or salt water after smoltification. In contrast to this ultraviolet cycle, the other cone mechanisms (short-, middle- and long-wavelength-sensitive) and the rod mechanism remain present throughout ontogeny. The natural appearance and disappearance of ultraviolet cones in salmonid retinas follows surges in blood thyroxine at critical developmental periods. Their presence coincides with times of prominent feeding on zooplankton and/or small fish that may be more visible under ultraviolet light. It is proposed that the primary function of ultraviolet cones in salmonids is to improve prey contrast.
The Ageing of the Low-Frequency Water Disturbances Caused by Swimming Goldfish and Its Possible Relevance to Prey Detection
Authors: Hanke Wolf , Brücker Christoph , Bleckmann Horst 
Published: April 2021

ABSTRACT
Wakes caused by swimming goldfish (Carassius auratus) were measured with a particle image velocimetry system and analyzed using a cross-correlation technique. Particle velocities in a horizontal plane (size of measuring plane 24 cm×32 cm or 20 cm×27 cm) were determined, and the vorticity in the plane was derived from these data. The wake behind a swimming goldfish can show a clear vortex structure for at least 30 s. Particle velocities significantly higher than background noise could still be detected 3 min after a fish (body length 10 cm) had passed through the measuring plane. Within this time span, the lateral spread of fish-generated wakes could exceed 30 cm for a 10 cm fish and 20 cm for a 6 cm fish. Measurements in a man-made open-air pond showed that water velocities in a quasi-natural still water environment can be as small as 1 mm s−1. Background velocities did not exceed 3 mm s−1 as long as no moving animal was present in the measuring plane. The possible advantage for piscivorous predators of being able to detect and analyze fish-generated wakes is discussed.