bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scaling the Feeding Mechanism of Largemouth Bass (Micropterus Salmoides): Kinematics of Prey Capture
Authors: Richard Barton A. , Wainwright Peter C. 
Published: April 2021

ABSTRACT
We present the first analysis of scaling effects on prey capture kinematics of a feeding vertebrate. The scaling of feeding kinematics of largemouth bass (Micropterus salmoides) was investigated using high-speed video (200 fields s 1) to determine what functional changes occur in the feeding mechanism as a consequence of body size. A size series of ten bass ranging from 32 to 210mm standard length was used for the study and ten feeding sequences from each individual were analyzed to quantify movements of the feeding apparatus during prey capture. Maximal linear and angular displacements of the strike scaled isometrically. The time course of the strike was longer in larger fish. Maximal velocities of displacement were more rapid in larger fish, but their scaling exponents indicated that the intrinsic rate of muscle shortening decreased with fish size. Morphological measurements of the lever arms of the lower jaw and of the two major muscles that drive the feeding mechanism were made to relate possible biomechanical changes in the feeding mechanism to the observed kinematic relationships. The lever arms of the lower jaw and the muscles scaled isometrically; hence, the relative slowing of movements with increasing body size cannot be attributed to changes in mechanical advantage with change in body size. The scaling of feeding kinematics in the largemouth bass is in accord with the scaling of rates of muscle contraction found in other lower vertebrates. These findings demonstrate that body size can have major effects on feeding kinematics and that future comparative studies of feeding kinematics should use empirical data on size effects in kinematic comparisons between taxa.
Thermal Adaptation of Cytoplasmic Malate Dehydrogenases of Eastern Pacific Barracuda (Sphyraena spp): The Role of Differential Isoenzyme Expression
Authors: Lin Jen-Jen , Somero George N. 
Published: April 2021

ABSTRACT
Kinetic properties, electrophoretic patterns and thermal stabilities of cytoplasmic malate dehydrogenases (cMDHs) were compared in Eastern Pacific barracuda (Sphyraena spp) from different latitudes. All tissues of the tropical species S. ensis contained only a single, thermostable form of cMDH. Subtropical (S. lucasana) as well as north (S. argentea) and south (S. idiastes) temperate barracuda contained both thermostable and thermolabile cMDHs, the pattern characteristic of most teleosts. Kinetic studies using unfractioned cMDHs showed that the apparent Michaelis–Menten constant (Km) of cofactor (NADH) increased with temperature, but at the physiological temperatures of the four species, Km of NADH was conserved within a narrow range (20–23 μmol l−1). Thermostable and thermolabile cMDHs were chromatographically separated and compared. Thermolabile cMDHs had higher Km values for NADH at all measurement temperatures than did thermostable cMDHs. Thermolabile cMDHs isolated from congeneric barracuda exhibited similar kinetic properties (Kmversus temperature, optimal pH, optimal substrate and cofactor concentrations). Thermostable cMDHs, likewise, were similar among the barracuda. Conservation of Km in the differently thermally adapted barracudas is, therefore, apparently due to adjustments in the ratio of expression of the thermostable and thermolabile isoforms, rather than to temperature-adaptive differences among orthologous homologues, as is commonly found for enzymes encoded by a single gene locus. The effects of temperature on the Km of NADH for isolated thermostable and thermolabile cMDHs of a eurythermal goby, Gillichthys mirabilis, however, were consistent with adaptive change in orthologous homologues of cMDH. The selective basis for the absence of thermolabile cMDH in warm-adapted ectotherms, mammals and birds is discussed.
Daily Variations in the Response of Wood Mice Apodemus Sylvaticus to Noradrenaline
Authors: Haim A. , McDevitt R. M. , Speakman J. R. 
Published: April 2021

ABSTRACT
Non-shivering thermogenesis (NST) is an important mechanism for heat production in many small rodent species. Daily rhythms of body (rectal) temperature (Tb) reflect the relationship between heat production and heat dissipation. The roles of photoperiod and the time of day at which NST is measured were studied in wood mice Apodemus sylvaticus.
Mice of both sexes (N=18) were acclimated to two different photoperiod regimes (16 h:8 h L:D and 8 h:16 h L:D) at a constant ambient temperature (Ta) of 24 °C. Non-shivering thermogenesis was measured as the maximal response of oxygen consumption and body temperature (TbNA) to a noradrenaline (NA) injection (1.5 mgkg−1 subcutaneously) in unanaesthetized mice at three different times in the daily rhythm of Tb (N=6 in each group).
Mice acclimated to 8 h:16 h L:D had a greater response to noradrenaline at the three different times of the day compared with those acclimated to 16 h:8 h L:D. The extent of the response to noradrenaline within each group varied with time of day; the smallest response was recorded at 18:00±1.5 h, and the greatest was at 01:00 h. These results suggest that photoperiod is an important cue for seasonal acclimatization in this species and that the response to noradrenaline follows a daily rhythm.
Extracellular and Intracellular Acid–Base Status in the Freshwater Crayfish Austropotamobius Pallipes Between 1 and 12 °C
Authors: Whiteley N. M. , Naylor J. K. , Taylor E. W. 
Published: April 2021

ABSTRACT
Freshwater crayfish, Austropotamobius pallipes, caught in the winter when water temperature was 5 °C, were acclimated in the laboratory to 5 °C for 1 week and to 1 and 12 °C for 1 month before haemolymph and tissue samples were taken for acid–base analysis. In vivo, haemolymph (extracellular) pH increased by 0.14 units between 5 and 1 °C but remained unchanged between 5 and 12 °C, giving an overall ΔpHe/Δt value of −0.009 pH units °C−1 and an [H+] value of +3.3 nmol l−1. Haemolymph withdrawn from crayfish acclimated to 1 °C and warmed anaerobically in vitro to 12 °C had a ΔpHe/Δt value of −0.010 pH units °C−1. This was depressed compared with the values of −0.015 and −0.016 pH units °C−1 obtained from haemolymph withdrawn from crayfish held at 5 and 12 °C, respectively, but changes in H+ concentration were similar in all three groups. There was little change in intracellular pH with rise in temperature in either claw muscle (ΔpHi/Δt= −0.003 pH units °C−1) or hepatopancreas (ΔpHi/Δt= −0.006 pH units °C−1). In the heart, ΔpHi/Δt paralleled that in the haemolymph (−0.010 pH units °C−1), but the largest change was found in the abdominal muscle (−0.025 pH units °C−1). In all tissues apart from claw muscle, there was a metabolic acidosis, with an increase in metabolic acid load as temperature rose from 1 to 12 °C. The depressed in vivo ΔpHe/Δt value and the differences in ΔpHi/Δt between the tissues were attributed to active regulation of pHi, possibly to control enzyme function in the intracellular compartments. Tissues that are functionally important in the winter months, such as abdominal muscle, followed alphastat regulation, whereas tissues that are less active in the winter, such as claw muscle and hepatopancreas, maintained pHi irrespective of temperature, resulting in a relatively acidotic pHi, which may serve to depress the activity of metabolic enzymes.
Evidence for the Involvement of Cyclic Amp in the Pheromonal Modulation of Barnacle Settlement
Authors: Clare Anthony S. , Thomas Ronald F. , Rittschof Daniel 
Published: April 2021

ABSTRACT
The involvement of cyclic AMP in the settlement of the cypris larva of Balanus amphitrite amphitrite Darwin has been examined through the use of compounds that affect intracellular cyclic AMP levels. The activation of adenylate cyclase with forskolin, and the inhibition of phosphodiesterase with 3-isobutyl-1-methylxanthine, caffeine and theophylline, significantly increased the settlement of cyprids. Although the analogue dibutyryl cyclic AMP appeared to increase settlement, the effect was not significant. No marked increase in settlement resulted from the incubation of cyprids with dibutyryl cyclic GMP, 8-(4-chlorophenylthio) (CPT) cyclic AMP or papaverine (a phosphodiesterase inhibitor). Miconazole nitrate, an adenylate cyclase inhibitor, prevented settlement, but this effect appeared to be physico-chemical rather than pharmacological. Radioimmunoassay did not clearly show whether cyclic AMP levels changed following exposure of cyprids to a pulse of crude barnacle extract. However, exposure to forskolin significantly increased the cyclic AMP titre of cyprids. We conclude that compounds that alter intracellular cyclic AMP levels alter normal patterns of cyprid settlement. Whether this is because of an alteration in signal transduction is unclear.
Spatial Orientation in the Lamprey : I. Control of Pitch and Roll
Authors: Ullén F. , Deliagina T. G. , Orlovsky G. N. , Grillner S. 
Published: April 2021

ABSTRACT
Two major tasks must be fulfilled during locomotion: propulsion and spatial orientation. In the lamprey, the propulsive force is generated by laterally directed body undulations propagated from the rostral to the caudal end of the body. The neuronal networks underlying this basic locomotor pattern have been described in considerable detail. The present study was undertaken to provide the necessary behavioural background for parallel studies of the vestibular neuronal networks responsible for spatial orientation during locomotion. The following results were obtained.
The lamprey actively stabilized its pitch angle during swimming and usually kept a linear trajectory in the sagittal plane, despite large changes in the speed of swimming. During repeated tests, a certain preferred pitch angle could be maintained over a period of several minutes, even if the initial starting angle of the animal was changed considerably. Two different strategies were observed for active turning in the downward direction: a smooth turn accomplished by weak ventral flexion of the whole body, and a sharp turn accomplished by localized ventral flexion of a region of the body just posterior to the gills. The lampreys were oriented with the dorsal side up while swimming at any pitch angle. The control systems for pitch and roll can thus operate independently. When swimming, lampreys kept the tail region flexed somewhat ventrally. This body configuration will cause lateral movements of the tail to generate a torque that rotates the body around its longitudinal axis. This mechanism is presumably used to correct deviations from the dorsal-side-up orientation. After amputation of the dorsal and tail fins, lampreys maintained a proper spatial orientation during swimming. After a unilateral labyrinthectomy, swimming lampreys continuously rolled towards the lesioned side. Unilaterally labyrinthectomized animals displayed a tonic twisting of the body into a helical shape. This presumably represents an additional strategy for performing roll turns. Bilaterally labyrinthectomized animals never maintained a linear trajectory in any plane, but turned continuously in all directions.
Spatial Orientation in the Lamprey : II. Visual Influence on Orientation During Locomotion and In The Attached State
Authors: Ullén F. , Deliagina T. G. , Orlovsky G. N. , Grillner S. 
Published: April 2021

ABSTRACT
The responses of attached lampreys to homogeneous visual stimulation and the role of visual stimuli in orientation during locomotion were investigated. Experiments were performed by video recording the responses of intact and lesioned animals to illumination. The following results were obtained.
In lampreys attached with their sucker mouth to the bottom of the aquarium, illumination of one eye evoked several possible motor responses (ordered after mean latency): (a) movement of the illuminated eye downwards, and the contralateral eye upwards; (b) rotation of the body around the longitudinal axis, with the illuminated side tilting downwards; (c) deviation of the caudal part of the anterior dorsal fin in the contralateral direction (away from the light); and (d) flexion of the neck and body towards the side of illumination. Illumination of one eye in attached lampreys often resulted in detachment and subsequent movement in a direction away from the light source (negative phototaxis). This response was not related to the degree of roll tilt before detachment, so the negative phototaxis does not appear to be a consequence of the vestibular stimulation. Negative phototaxis was also seen during locomotion: lampreys turned through 180 ˚ when they approached a brightly illuminated area. Photostimulation also affected their orientation in the transverse plane during swimming. Illumination of one eye from the side induced a roll movement, so that the illuminated side tilted downwards and the dorsum of the lamprey became turned towards the light. This is similar to the ‘dorsal light response’ of fish and shows that vision also plays a role in postural control in lampreys. The behaviour of blinded animals differed strikingly from that of intact ones. Whereas intact animals preferentially swam close to the bottom, along horizontal trajectories, blinded animals showed episodes of continuous swimming upwards, near the water surface. During horizontal swimming, their orientation in the transverse plane remained normal, with the dorsal side up.
Locomotor Patterns in Freely Moving Crayfish (Procambarus Clarkii)
Authors: Jamon Marc , Clarac François 
Published: April 2021

ABSTRACT
Freely walking crayfish, Procambarus clarkii, were studied using a video analysis procedure adapted especially for use with crayfish. The animals were placed in a tank and their homing behaviour was filmed as they returned in a straight line to their shelter. Various sequences were studied at the two following levels. First, the trajectory of each pair of legs (from leg 2 to leg 5) during the step cycle (power stroke and return stroke) was studied to measure stride length and to analyse in detail changes in acceleration. Each leg was found to contribute in a specific manner to locomotion. Second, ipsi-and contralateral leg coordination was investigated. Ipsilateral coordination was found to involve a metachronal organization from front to back in all the walking sequences recorded, whereas contralateral coordination involved, in addition to the weak alternate coupling commonly observed in treadmill walking, another coordination pattern where the legs on each side (legs 3 and 4) are in phase. The results obtained in these free-walking sequences are discussed and compared with those obtained previously, in particular in treadmill situations.
Electrosensory Thresholds in Larvae of the Weakly Electric Fish Pollimyrus Isidori (Mormyridae, Teleostei) During Ontogeny
Authors: Postner Martin , Kramer Bernd 
Published: April 2021

ABSTRACT
Electrosensory thresholds and tuning were determined from behavioural studies in larvae of Pollimyrus isidori using the stop response of their electric organ discharge to weak electrical stimuli. Two age groups were studied: (1) 10-to 15-day-old larvae in which the electric organ discharge (EOD), produced by a distinct larval electric organ, had just stabilized; (2) 54-to 60-day-old larvae, just before the advent of the adult EOD (an adult electric organ functionally replaces that of the larva between about 60 and 80 days). Three stimulus pulse waveforms were used: (1) single-cycle, bipolar sine-wave pulses; (2) single-cycle, monopolar sine-wave pulses and (3) monopolar square-wave pulses.
The younger larvae were exceedingly sensitive to weak electrical stimuli, down to the 10 µVp–p cm−1 range. Stimulus pulse duration had a significant effect on threshold for all three pulse waveforms, but the shapes of the tuning curves were quite different. Thresholds at the ‘best’ pulse duration were lower and the tuning sharper (with a V-shaped curve) with monopolar sine-wave pulses than with bipolar sine-wave pulses. The ‘best’ pulse duration was 1 ms for both sine-wave pulses, corresponding well to the spectral peak amplitude of larval EODs (964±22 Hz). The threshold curve for monopolar sine-wave pulses appeared to be perfectly adapted for sensing larval rather than adult EODs. With square-pulse stimuli, thresholds increased monotonically with duration and there was no evidence of tuning for this kind of stimulus. These results suggest that both conventional spectral tuning and ‘tuning’ to a particular pulse waveform (with a monopolar sine-wave pulse best approximating the waveform of a larval discharge) are found in young larvae. In the older age group, larvae were more sensitive to all three kinds of stimuli than those of the younger age group. The sensitivity increase varied from 10 dB to 29 dB; at stimuli of 2.4 µVp–p cm−1, larvae just 18 mm long displayed adult sensitivity. No tuning was seen for square-wave pulses and, as in younger larvae, their effectiveness increased monotonically with duration, so that for neither age group are square-wave pulses a good model for larval EODs. The threshold curves for both types of sine-wave pulse were similar and resembled the broadband tuning curves of Knollenorgan electroreceptors. Tuning was present but weak, with sensitivity for the high-frequency range much greater than for younger larvae. This change is adaptive for sensing both larval and adult EODs and occurred before the larvae developed an adult EOD.
The mechanism for a change in tuning that has been established for electroreceptors in adult mormyrids and gymnotiforms, where the spectral properties of the EOD of a fish entrain its electroreceptors, is not found in the larvae of Pollimyrus isidori, which ‘anticipate’ the tuning necessary for the reception of their own, future adult EOD.
Effects of Anoxia on Energy Metabolism in Crucian Carp Brain Slices Studied With Microcalorimetry
Authors: Johansson Dan , Nilsson Göran E. , Törnblom Erik 
Published: April 2021

ABSTRACT
Crucian carp (Carassius carassius L.) is an exceptionally anoxia-tolerant vertebrate. To determine whether isolated crucian carp brain tissue survives anoxia and whether it displays anoxic metabolic depression, heat production (using microcalorimetry), lactate production, ethanol production and the maintenance of ATP, ADP and AMP levels and energy charge were measured in telencephalic brain slices during anoxia. In response to anoxia, heat output decreased by 37 %, corresponding to a 31 % fall in ATP turnover rate. Adenylate phosphates and energy charge were well maintained and no ethanol was produced during anoxia. It is concluded that crucian carp brain tissue has an intrinsic capacity to tolerate anoxia and that it responds to anoxia by depressing metabolic rate and elevating the glycolytic rate, thereby maintaining ATP levels.
Ingestive Sensory Inputs Excite Serotonin Effector Neurones and Promote Serotonin Depletion From the Leech Central Nervous System and Periphery
Authors: Groome James R. , Vaughan Dana K. , Lent Charles M. 
Published: April 2021

ABSTRACT
Thermal and chemical stimuli known to promote ingestive behaviours in the medicinal leech Hirudo medicinalis were tested for their physiological effects on Retzius neurones and for their biochemical effects on serotonin levels in the central nervous system, pharynx and body wall. Retzius neurones throughout the leech nerve cord receive excitatory synaptic input during thermal or chemical stimulation of the prostomial lip. These neurones respond to the rate of change of temperature as well as to absolute temperature at the lip. Exposure of the lip to sodium chloride excites Retzius neurones, whereas exposure to arginine has little effect. Thermal stimulation of the lip elicits a more rapid but less prolonged excitation of Retzius neurones than does chemical stimulation.
Stimulation of the prostomial lip is associated with afferent activities in the cephalic nerves D1, D2 and V1–2. Thermal stimulation of the prostomial lip results in depletion of serotonin from midbody ganglia, whereas chemical stimulation has no effect. Conversely, chemical stimulation of the lip results in depletion of serotonin from the body wall, whereas thermal stimulation does not. Pharyngeal serotonin content is decreased with either modality. These data distinguish two important feeding-related sensory input pathways to central serotonergic effector neurones in Hirudo medicinalis.
A Neurotransmitter Role for Red-Pigment-Concentrating Hormone in Ovarian Maturation in the Red Swamp Crayfish Procambarus Clarkii
Authors: Sarojini Rachakonda , Nagabhushanam Rachakonda , Fingerman Milton 
Published: April 2021

ABSTRACT
The influence of red-pigment-concentrating hormone (RPCH) on ovarian maturation in the red swamp crayfish Procambarus clarkii was studied using both in vivo and in vitro techniques. In vivo, RPCH stimulated ovarian maturation. However, RPCH did not affect the ovary in vitro when only RPCH, muscle and ovarian explants were used. But when RPCH, thoracic ganglia, which are known to contain gonad-stimulating hormone-like (GSH-like) activity, and ovarian explants were incubated together, significant ovarian maturation ensued. The calcium ionophore A23187 mimicked RPCH both in vivo and in vitro. These results provide evidence to support the hypothesis that RPCH has a role as a neurotransmitter in Procambarus clarkii to stimulate GSH release, with calcium acting as a second messenger for RPCH.
The Motor Program for Defensive Kicking in Crickets: Performance and Neural Control
Authors: Hustert Reinhold , Gnatzy Werner 
Published: April 2021

ABSTRACT
Crickets can repulse sources of mechanical touch to their wings, legs or to the posterior body by kicking backwards ipsilaterally with one hindleg. The main component of a kick is the rapid extension of the femoro-tibial (knee) joint. A kick as a defence against predators must occur instantly after the moment of touch. The cricket kick is completed within 60–100 ms, whereas in locusts 500–2000 ms elapses between the stimulus and the end of the kick. The rapid movement of the cricket hindleg was recorded with a high-resolution video technique. Cricket kicking is based on a dynamic co-contraction of the extensor and flexor tibiae muscles during the pre-kick knee flexion period, thus differing from the static co-contraction period seen in locusts. Biomechanically, the knee joint is specialized for kicking and jumping by the specific leverage of tendons inserting at the knee, by a femoral ridge that modifies the angle of attack for flexor muscular forces and by a cushion-like swelling on the flexor tibiae tendon. Because of these structural specialisations for rapid kicking, the neural control of the motor pattern of the muscles participating in the tibial movement can vary considerably, but still produce efficient kicks. Kicking is also an element of other complex behaviours.