bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identified Neurones Involved in the Control of Rhythmic Buccal Motor Activity in the Snail Achatina Fulica
Authors: Yoshida Masayuki , Kobayashi Makoto 
Published: April 2021

ABSTRACT
In the land snail Achatina fulica, it has been suggested that two pairs of cerebral neurones, ventral cerebral distinct neurones (v-CDNs) and Cl neurones, and a pair of buccal motoneurones (B1s) are involved in the control of rhythmic motor activity (RMA) in the buccal ganglia. These neurones, when tonically fired by depolarizing current injection, could individually initiate and maintain RMA in previously quiescent isolated ganglia. The rhythm elicited by v-CDN persisted for several cycles after the firing of v-CDN stopped, while that elicited by Cl or B1 ceased immediately after the firing of these neurones stopped. RMA also occurred spontaneously and could be induced by labial nerve stimulation in a reduced preparation. Nevertheless, such rhythms were not always accompanied by the firing of v-CDN, Cl or BL. Thus, the firing of these neurones appears to be sufficient, but not essential, for rhythm generation in the experimental conditions.
Taste stimulation of the lip in semi-intact preparations often induced RMA in the buccal ganglia. However, v-CDN and B1 were not tonically excited by the stimulation. It seems unlikely that v-CDN and B1 are critical elements in the generation of the feeding rhythm. Cl responded to taste stimuli with excitation after RMA had begun, suggesting that Cl is involved in the taste-induced buccal rhythm.
Intra-Nasal Zinc Sulphate Irrigation in Pigeons: Effects on Olfactory Capabilities And Homing
Authors: Schlund Wolfgang 
Published: April 2021

ABSTRACT
Depriving homing pigeons of olfactory information by applying a local anaesthetic, gingicain, to their olfactory epithelium results in systemic effects. Furthermore, anosmia persists reliably for only an hour. In contrast, intra-nasal irrigation with 18 % zinc sulphate solution results in anosmia that persists for at least 5 days. No systemic effects of zinc sulphate on anosmie pigeons could be detected while monitoring their olfactory capabilities using the orienting response. To compare the orientation and homing of definitely anosmie, zinc-sulphate-treated pigeons with those of controls, I made releases from two different distances (9−24km, 63−70km). At shorter distances, pigeons treated with zinc sulphate showed no directional preference in their vanishing bearings, whereas both groups of control birds (sham-treated controls and untreated super controls) were well oriented. At the longer distances, the situation was more complex: pigeons treated with zinc sulphate were oriented but the chosen direction did not correspond with the home direction. The control groups did not show any directional preference. In all cases, fewer anosmie pigeons homed and they did so more slowly than did the controls.
Climbing Performance of Migrating Birds as A Basis for Estimating Limits for Fuel-Carrying Capacity and Muscle Work
Authors: Hedenström Anders , Alerstam Thomas 
Published: April 2021

ABSTRACTSustained climb rates and airspeeds in flapping flight were measured by radar tracking fifteen species of migrating birds ranging in body mass between 10 g and 10 kg. There was an inverse correlation between body size and climb rate: the lowest mean climb rate, 0.32 m s−1, was observed in the mute swan and the highest mean value, 1.63 m s−1, in the dunlin. Some dunlin flocks achieved sustained climb rates exceeding 2ms−1, up to 2.14ms−1. Assuming that the migrants expend maximum sustained power during their climbs, the climbing power can be used as a conservative estimate of the power margin. Estimates of climbing power for the species tracked by radar were used, in conjunction with aerodynamic theory, to calculate the amount of extra load the migrants should be able to carry if their power margin was used for load transportation rather than for climbing. Calculated ratios of total body mass with maximum load to lean body mass ranged between 1.28 and 2.75, showing an overall negative correlation with body size. There was a broad agreement with maximum fuel loads observed among free-living birds, indicating that the upper limits of fuel-carrying capacities and flight ranges in migrating birds are determined by power margin constraints in sustained flapping flight. Markedly reduced climb rates have been recorded for shorebirds departing with very large fuel reserves from W. Africa and Iceland, supporting the calculated trade-off between climb rate and fuel load. Total power consumption was estimated as the sum of calculated aerodynamic power for forward flight and climbing power. The ratio of total power to the expected minimum aerodynamic power was 1.1–1.3 in the three largest species, increasing to 2–4 in the smallest species. Medium-and small-sized species seem to allocate power in excess of the minimum aerodynamic power not only for climbing but also for maintaining a forward speed faster than the minimum power speed. Given provisional estimates of flight muscle masses and wingbeat frequencies, the mass-specific sustained muscle work for the different climbing bird species was calculated to be in the range 16–41 joules per kilogram muscle mass, showing a significant positive correlation with body mass.
Evidence for a Role of Gaba in Metabolic Depression During Anoxia in Crucian Carp (Carassius Carassius)
Authors: Nilsson Göran E. 
Published: April 2021

ABSTRACT
Anoxia-tolerant vertebrates decrease their metabolic rate by 70% or more during anoxia, while the major inhibitory neurotransmitter in the vertebrate brain, GABA, increases in concentration. To test the possibility that GABA could be a mediator of anoxic metabolic depression, crucian carp (Carassius carassius L.) were given an inhibitor of GABA synthesis, isoniazid, and the rate of anoxic ethanol production (ethanol being the main end product of energy metabolism in anoxic crucian carp) as well as the rates of normoxic and hypoxic oxygen consumption were measured. Isoniazid (500 mg kg−1), which significantly inhibited the anoxia-induced rise in brain GABA concentration, caused a nearly threefold increase in anaerobic ethanol production without affecting normoxic oxygen consumption. The GABA synthesis inhibitor 3-mercaptopropionic acid (3-MP, 200 mg kg−1) and the GABA receptor antagonist securinine (20 mg kg−1) caused similar rises in anoxic ethanol production. Nevertheless, crucian carp given 250-500mgkg−1 isoniazid, 200mgkg−1 3-MP or 20mgkg−1 securinine all recovered after anoxia, suggesting that a complete depression of the rate of metabolism may not be essential for survival during short-term anoxia. These results indicate that GABA is a mediator of anoxic metabolic depression in crucian carp.
Steering Reactions as Adaptive Components of the Tail-Flip in the Spiny Lobster Jasus Lalandii
Authors: Newland Philip L. , Cattaert Daniel , Neil Douglas M. , Clarac Francois 
Published: April 2021

ABSTRACT
Steering movements of the abdomen and the terminal appendages, the uropods, of the rock lobster Jasus lalandii have been examined during slow postural responses and during tail-flips using a combination of movement and force measurements and by monitoring muscle activity. Gentle mechanical stimulation on one side of the animal elicits a postural steering response of the uropods. The activities of the individual uropod muscles that underlie these movements have been determined.
Progressively intense mechanical stimuli initiate tail-flips, which may incorporate steering responses dependent upon the position of the stimulus. Symmetrical stimuli cause both uropods to open and close symmetrically and only a longitudinally directed force to be produced. However, stimuli delivered to only one side elicit asymmetrical movements of the uropods and rotation of the abdomen to the stimulated side during the preflexion phase of the tail-flip. The pattern of activity in the uropod muscles during this preflexion phase is the same as that in the postural steering response. During flexion itself, the uropods open to their full extent while the abdomen rotates further to the stimulated side. As a result of these movements, appropriate steering forces are produced to take the animal away from the point of stimulation. During re-extension, the uropods close and the abdomen re-extends.
These results are discussed in terms of the relationship between postural reactions and the preflexion phase of the tail-flip, the relative contribution of the different abdominal motor systems to tail-flip steering and the occurrence of steering in different forms of the tail-flip.
Insect Cardioactive Peptides in Manduca Sexta: A Comparison of the Biochemical And Molecular Characteristics of Cardioactive Peptides in Larvae and Adults
Authors: Tublitz N. J. , Cheung C. C. , Edwards K. K. , Sylwester A. W. , Reynolds S.E. 
Published: April 2021

ABSTRACT
The role of neurally derived peptides affecting insect visceral muscle has been explored by many investigators over the past thirty years (e.g. Raabe, 1982; Miller, 1985; Huddart, 1985). One set of myoactive neuropeptides that have been well characterized physiologically is the cardioacceleratory peptides (CAPs) found in the tobacco hawkmoth Manduca sexta. The CAPs act as cardioregulatory neurohormones in the adult moth, increasing heart rate during wing inflation (Tublitz and Truman, 1985a,b; Tublitz and Evans, 1986) and flight (Tublitz, 1989). In addition to their involvement in adult behaviour, one of the CAPs, CAP2, has been implicated in the modulation of the embryonic hindgut in Manduca sexta. Broadie et al. (1990) demonstrated that CAP2 is released in the latter half of embryonic development to aid in the digestion of extra-embryonic yolk by stimulating frequency of gut contractures. This interpretation was supported by quantitative immunocytochemical studies using an anti-CAP monoclonal antibody to identify a group of central nervous system (CNS) neurones that were CAP-immunoreactive (Broadie et al. 1990).
Characterization of a Vasodilator from the Salivary Glands of the Yellow Fever Mosquito Aedes Aegypti
Authors: Ribeiro José M. C. 
Published: April 2021

ABSTRACT
Salivary gland homogenates and oil-induced saliva of the mosquito Aedes aegypti dilate the rabbit aortic ring and contract the guinea pig ileum. The vasodilatory activity is endothelium-dependent, heat-stable, sensitive to both trypsin and chymotrypsin treatments, and both smooth muscle activities cross-desensitize to the tachykinin peptide substance P. Both bioactivities co-elute when salivary gland homogenates are fractionated by reversed-phase HPLC. Molecular sieving chromatography indicates a relative molecular mass of 1400. A monoclonal antibody specific to the carboxy terminal region of tachykinins reacts with material in the posterior part of the central lobe of paraformaldehyde-fixed salivary glands. The presence of a vasodilatory peptide of the tachykinin family in the salivary glands of A. aegypti is proposed and its role in blood feeding is discussed.
Orientation-Disturbing Magnetic Treatment Affects The Pigeon Opioid System
Authors: Papi Floriano , Luschi Paolo , Limonta Patrizia 
Published: April 2021

ABSTRACT
Keeping homing pigeons in an oscillating magnetic field of low intensity is known to increase the scattering of initial bearings and/or their deflection towards a specific direction. To determine whether these effects on orientation are the outcome of direct interference with the birds’ navigational mechanism or are the side-effect of problems in another biological system, experiments were performed to test whether the same effects could be induced by non-magnetic treatments. The initial orientation of pigeons treated with the prototypic opiate antagonist naloxone (1 mg kg-1) displayed similar disturbances to those observed in magnetically treated birds. In both cases, the orientation was significantly different from that of control birds.
The concentration and affinity of the brain’s μ-opiate receptors were then assessed in magnetically treated birds by using [3H]dihydromorphine as a ligand. The concentration of μ-opiate receptors fell significantly in these birds, whereas the affinity of the receptors was unaffected.
We conclude that it appears improbable that the navigational mechanism of pigeons is directly influenced by magnetic treatments. What these do seem to produce is a lack of compensation for the stress experienced by pigeons subjected to a test release.
Conditional Inhibition of Screening-Pigment Aggregation by Lidocaine in Crayfish Photoreceptors and Frog Retinal Pigment Epithelium
Authors: Mondragón Ricardo , Frixione Eugenio 
Published: April 2021

ABSTRACT
Lidocaine, at concentrations equal to or lower than those that inhibit fast axoplasmic transport, was found to interfere with the dark-adapting migration of the screening pigments along crayfish photoreceptors and within the cells of the frog retinal pigment epithelium (RPE). The effects of the anesthetic on pigment movements were studied in isolated eyes incubated under light or dark conditions in media of different ionic compositions. Treatment of crayfish eyes with 25 mmol l−1 lidocaine in normal Van Harreveld’s saline arrested pigment migration to the dark-adapted position or caused migration towards the light-adapted position in the dark. Similar results were obtained with frog eyecups exposed to 5 mmol l−1 lidocaine in Ringer’s solution. In each case, the inhibition of dark adaptation was reversible and dependent on the levels of Na+ and Ca2+ in the incubation medium. A dark-adapted position of both pigments was compatible with lidocaine treatment provided that low-Na+, or high-Ca2+ or CO2+ containing solutions were used. These results indicate that light-adapted and dark-adapted pigment positions in both types of retinal cells can occur in the absence of local nervous input. Further, the data suggest a direct effect of lidocaine upon the photoreceptors or RPE cells. The inhibition of pigment aggregation is interpreted to be a consequence of an anesthetic-induced increase in the permeability of the plasma membrane, which in turn affects the intracellular ionic balance that controls pigment position.
Hypoxic Boundary Layers Surrounding Skin-Breathing Aquatic Amphibians: Occurrence, Consequences and Organismal Responses
Authors: Feder Martin E. , Booth David T. 
Published: April 2021

ABSTRACT
We have used oxygen microelectrodes to characterize the relationship between the partial pressure of oxygen and the distance from the skin in a variety of amphibians immersed in unstirred normoxic water. A substantial hypoxic boundary layer surrounded the skin in nearly every case, with the at the skin-medium interface typically varying between 2 and 4 kPa at both 10 and 20°C. The degree of hypoxia varied little among the anatomical sites examined.
We hypothesized that the formation of hypoxic boundary layers should abbreviate voluntary diving in amphibians that use cutaneous oxygen uptake from water to supplement oxygen stores in the body during dives. To test this, we compared voluntary submergence times of amphibians diving in stirred and unstirred normoxic water. The dives of frogs (Xenopus laevis) and salamanders (Siren lacertina) in stirred water averaged 2·3–2·5 times longer than dives in unstirred water. Diving Xenopus also underwent more voluntary movements (other than swimming to the surface to breathe air) in unstirred water than in moving water. A closed extracorporeal loop containing an oxygen electrode was used to record the of lung gas during forced dives in Xenopus to determine the time required to deplete pulmonary oxygen stores to a level normally associated with the end of voluntary dives . In normoxic water flowing at 0·54 cm s−1 or faster, the decline in pulmonary to this level required on average 18.7 min; in unstirred normoxic water, the average time was 13·8 min. This difference is tantamount to a 36 % extension of submergence time in flowing water.
These findings and those of companion studies suggest that hypoxic boundary layers have a major and pervasive influence on the respiratory status of skinbreathing amphibians in water.
Coupling Between The Heart and Sucking Stomach During Ingestion in a Tarantula
Authors: Dunlop Jason A. , Altringham John D. , Mill Peter J. 
Published: April 2021

ABSTRACT
Electrocardiograms (ECGs) and electromyograms (EMGs) from the dorsal musculature of the sucking stomach of tarantulas (Grammastola cala) were recorded simultaneously from unrestrained animals during ingestion. Resting heart rates averaged 33.6±1.9 beats min−1, which increased significantly to an average of 51.6±3.8 beats min−1 during ingestion. This is not significantly different from the average sucking stomach rate of 53.6±3.9 cycles min−1. Activity of the sucking stomach constrictor muscles started with a phase shift of 0.64±0.007 cycles relative to dilator activity. In some cases the stomach dilators were active almost in synchrony with heart systole (phase shift of 0.10±0.009 relative to ECG), and the constrictors were active later in the cycle, during diastole, with a phase shift of 0.71±0.007 relative to the ECG. These data suggest that, during ingestion, fluid flows in the anterior aorta and midgut are negatively coupled as the fluids traverse the pedicel. Although such coupling was observed in about half the traces, other results were obtained that showed no evidence of coupling. Possible mechanisms for coupling and the sequence of events in the pedicel during ingestion are discussed.
Constrained and Flexible Features of Rhythmical Hindlimb Movements in Chicks: Kinematic Profiles of Walking, Swimming and Airstepping
Authors: Johnston Rebecca M. , Bekoff Anne 
Published: April 2021

ABSTRACT
Although studies of walking have generated many of the principles for motor control, walking is but one of the many behaviors that an animal produces. This study investigates the relationships among the kinematic profiles of three behaviors in chicks: walking, swimming and airstepping. In addition to describing features of the hindlimb movements, such as retraction and protraction, we also examined the intra-and interjoint coordination patterns at the hip, knee and ankle. By using multiple levels of analysis, we identified some features that are common to all three behaviors, and therefore appear to be constrained, as well as some dissimilar or flexible features. Specifically, we show that resistance differentially affects the hip, knee and ankle joints. Our results also show that each joint plays a distinctive role in these behaviors. For example, we suggest that the hip stabilizes the hindlimb and regulates the rhythmicity of its movements. We also show that movement at the knee consistently precedes movement at the other joints in each behavior. Finally, differences in ankle movements are the key features that discriminate one behavior from another. Continuity among prenatal, perinatal and postnatal behaviors in chicks is discussed.
Undulatory Swimming: How Traveling Waves are Produced and Modulated in Sunfish (Lepomis Gibbosus)
Authors: Long John H. , McHenry Matthew J. , Boetticher Nicholas C. 
Published: April 2021

ABSTRACT
We have developed an experimental procedure in which the in situ locomotor muscles of dead fishes can be electrically stimulated to generate swimming motions. This procedure gives the experimenter control of muscle activation and the mechanical properties of the body. Using pumpkinseed sunfish, Lepomis gibbosus, we investigated the mechanics of undulatory swimming by comparing the swimming kinematics of live sunfish with the kinematics of dead sunfish made to swim using electrical stimulation. In electrically stimulated sunfish, undulatory waves can be produced by alternating left–right contractions of either all the axial muscle or just the precaudal axial muscle. As judged by changes in swimming speed, most of the locomotor power is generated precaudally and transmitted to the caudal fin by way of the skin and axial skeleton. The form of the traveling undulatory wave – as measured by tail-beat amplitude, propulsive wavelength and maximal caudal curvature – can be modulated by experimental control of the body’s passive stiffness, which is a property of the skin, connective tissue and axial skeleton.
Note on the Calculation of Propeller Efficiency Using Elongated Body Theory
Authors: Cheng Jian-Yu , Blickhan Reinhard 
Published: April 2021

ABSTRACTThe elongated body theory has been widely used for calculations of the hydrodynamic propulsive performance of swimming fish. In the biological literature, terms containing the slope of the amplitude function at the tail end have been neglected in the calculations of thrust and efficiency, and a slope of zero has been assumed. However, some fishes, such as saithe and trout, have non-zero values of the slope near the tail end and, when this term is taken into account, the efficiency may be reduced by as much as 20% and approaches the result given by the three-dimensional waving plate theory. The inclusion of the slope in the efficiency considerations results in an optimum ratio of the swimming speed to the wave speed that is clearly less than 1. It is suggested that the slope terms should be included in the estimation of propulsive performance for fish swimming with variable amplitude.
Modulation of Negative Work Output from a Steering Muscle of the Blowfly Calliphora Vicina
Authors: Tu Michael S. , Dickinson Michael H. 
Published: April 2021

ABSTRACT
Of the 17 muscles responsible for flight control in flies, only the first basalar muscle (b1) is known to fire an action potential each and every wing beat at a precise phase of the wing-beat period. The phase of action potentials in the b1 is shifted during turns, implicating the b1 in the control of aerodynamic yaw torque. We used the work loop technique to quantify the effects of phase modulation on the mechanical output of the b1 of the blowfly Calliphora vicina. During cyclic length oscillations at 10 and 50 Hz, the magnitude of positive work output by the b1 was similar to that measured previously from other insect muscles. However, when tested at wing-beat frequency (150 Hz), the net work performed in each cycle was negative. The twitch kinetics of the b1 suggest that negative work output reflects intrinsic specializations of the b1 muscle. Our results suggest that, in addition to a possible role as a passive elastic element, the phase-sensitivity of its mechanical properties may endow the b1 with the capacity to modulate wing-beat kinematics during turning maneuvers.