bluuebunny/crossref_metadata_2025_split huggingface dataset:
Excretion of Alkaloids by Malpighian Tubules of Insects
Authors: Maddrell S. H. , Gardiner B. O. 
Published: April 2021

ABSTRACT
Nicotine is transported at high rates by Malpighian tubules of larvae of Manduca sexto, Pieris brassicae and Rhodnius prolixus and the transport persists in the absence of alkaloid from the diet. In the fluid-secreting portion of Rhodnius tubules this transport is not coupled to ion transport, nor is it dependent on the physiological state of the animal. The transport, which can occur against a steep electrochemical gradient, shows saturation kinetics with a maximal rate of 700 pmol. min−1 per tubule and is half saturated at 2–3 mm. Nicotine transport independent of ion movements also occurs in the lower resorptive parts of Rhodnius tubules. Both portions of Rhodnius tubules can transport morphine and atropine. These alkaloids and nicotine compete with one another and are presumed to be carried by the same transport system. Nicotine transport in Rhodnius was unaffected by organic anions, such as amaranth and benzyl penicillin, or by the organic anion transport inhibitor, probenecid. Fluid secretion in 5-HT-stimulated tubules was reduced by atropine and nicotine, probably by blocking the 5-HT receptors. The Malpighian tubules of adult Calliphora erythrocephala and Musca domestica remove nicotine from bathing solutions, an unknown metabolite accumulating in the tubules. Adult P. brassicae and M. sexta do not exhibit transport of nicotine by their Malpighian tubules.
Active transport of sodium by the malpighian tubules of the tsetse fly Glossina morsitans
Authors: Gee J. D. 
Published: April 2021

ABSTRACT
Isolated Malpighian tubules of Glossina morsitans are able to transport sodium against its concentration gradient. Their rate of secretion is dependent on the sodium concentration of the bathing medium. Potassium must be present in the bathing solution for rapid secretion to be maintained, but it does not play an active role in fluid secretion. Lithium and ammonium ions are able to substitute partially for sodium, other monovalent cations cannot. Ouabain does not affect rapid secretion by Glossina tubules in vitro. Conclusions drawn from the results are incorporated into a model of Malpighian tubule cell function in this insect.
The unreliability of mammalian glomerular markers in teleostean renal studies
Authors: Beyenbach K. W. , Kirschner L. B. 
Published: April 2021

ABSTRACT
The assumption that [3H]methoxy inulin, [14C]polyethylene glycol (PEG) and [128]iothalamate (glofil) are reliable volume and glomerular markers in teleosts was tested. PEG occupied smaller volumes than inulin and glofil in sea-water-adapted Salmo gairdneri. Ureteral clearances of PEG were about 22 % higher than those of inulin and glofil, and urine-to-plasma ratios were significantly greater for PEG than for the other two markers. After introduction into the urinary bladder the three macro-molecules appeared in the plasma, PEG at the lowest rates. These observations indicate that mammalian glomerular markers can penetrate the bladder and possibly the ureters and renal tubules. Therefore, their clearances may not give a true measure of glomerular filtration rates in teleosts.
Two slow conduction systems co-ordinate shell-climbing behaviour in the sea anemone Calliactis parasitica
Authors: McFarlane I. D. 
Published: April 2021

ABSTRACT
Pulses in two slow conducting systems, the ectodermal SS 1 and the endodermal SS 2, were recorded during shell-climbing behaviour. The mean pulse interval of SS 1 pulses was 7·4 s and that of SS 2 pulses was 6·4 s. Activity in both systems may arise as a sensory response of tentacles to shell contact, but the SS 1 and SS 2 may not share the same receptors. Electrical stimulation of the SS 1 and SS 2 together, at a frequency of 1 shock every 5 s, elicits shell-climbing behaviour in the absence of a shell. Low-frequency nerve-net activity (about 1 pulse every 15 s) accompanies column bending during both normal and electrically elicited responses. This activity probably arises as a result of column bending and is not due to a sensory response to the shell.
The effects of transecting the IXth and Xth cranial nerves on hydromineral balance in the eel Anguilla anguilla
Authors: Mayer-Gostan N. , Hirano T. 
Published: April 2021

ABSTRACT
The IXth and the Xth cranial nerves in Anguilla anguilla were transected, and the effects upon ion and water balance were studied in fresh water and sea water, and during transfer from fresh water to sea water and vice versa. In fresh water there is a slow demineralization due to an excess loss of Na and Cl ions. During freshwater to seawater transfer the eel survives only for 4–5 days. The fish do not drink and Na efflux does not increase enough to extrude excess ions. In sea water the glossopharyngeal and vagus nerves are necessary for the maintenance of the hydromineral balance. Denervation is followed by an increase in plasma ion concentrations. Na fluxes are not modified and increased water loss is not compensated by drinking.
The rapid reduction of Na efflux during transfer from sea water to fresh water is not modified by denervation.
The series elastic component and the force-velocity relation in the anterior byssal retractor muscle of Mytilus edulis during active and catch contractions
Authors: Tameyasu T. , Sugi H. 
Published: April 2021

ABSTRACT
The length changes of the anterior byssal retractor muscle (ABRM) of Mytilus edulis, following step changes in load, were studied at various phases of active and catch contractions produced by acetylcholine. The load-extension curves of the series elastic component (SEC) were found to be scaled down in proportion to the isometric tension immediately before step changes in load, but remain unchanged irrespective of whether the ABRM was in active or in catch contraction. In hypertonic solutions the compliance of the SEC was reduced in the same manner as that of the SEC in frog skeletal muscle. These results seem to favour the linkage hypothesis for the catch mechanism, though the SEC in the ABRM is suggested to be composed not only of the cross-linkages, but also of the compliance of the myofilaments.
Flight energetics of sphinx moths: power input during hovering flight
Authors: Casey T. M. 
Published: April 2021

ABSTRACT
The energetic cost of hovering flight was measured in sphinx moths from five species. Mean power input per unit mass (Pi/M) varied from 237·2 W kg−1 in Manduca sexta (Subfamily: Sphinginae), mean body mass 1·2 × 10−3 kg, to 327·9 W kg−1 in Deilephila elpenor (Subfamily: Macroglossinae) mean body mass 7×3 × 10−4 kg. Mean Pi/M for the five species was inversely proportional to mean body mass and directly proportional to mean wing loading. For any given body mass, Pi/M was greater in Hyles lineata than in M. sexta. This difference is correlated with higher wing loading at any given mass in H. lineata. Energy expenditure per unit mass of thorax was 1018 W kg−1 in H. lineata and 694 W kg−1 in M. sexta. Within each of these species, Pi per unit mass of thorax does not vary with body mass. Power input data are compared with calculated power requirements based on momentum theory and blade-element theory of helicopter aerodynamics. Absolute efficiency, the ratio between calculated power requirements and measured energy expenditure, appears to vary directly with body mass. These data provide an energetic basis for observed correlates between thoracic temperature and flight effort in flying sphinx moths.
Heat exchange in relation to blood flow between thorax and abdomen in bumblebees
Authors: Heinrich B. 
Published: April 2021

ABSTRACT
The narrow passage within the petiole between thorax and abdomen is anatomically constructed so that counter-current exchange should retain heat in the thorax despite blood flow to and from the cool abdomen. However, the counter-current heat exchanger can be physiologically circumvented. Exogenously heated bumblebees prevented overheating of the thorax by shunting heat into the abdomen. They also regurgitated fluid, which helped to reduce head temperature but had little effect on thoracic temperature. Temperature increases in the ventrum of the abdomen occurred in steps exactly coinciding with the beats of the ventral diaphragm, and with the abdominal ‘ventilatory’ pumping movements when these were present. The ability to prevent overheating of the thorax by transport of heat to the abdomen was abolished when the heart was made inoperative. At low thoracic temperatures the ventral diaphragm beat at a wide range of rates and with varying interbeat intervals, while the heart beat at a high frequency relative to the ventral diaphragm, but at a very low amplitude. However, when thoracic temperature exceeded 43 °C the amplitudes of both were high, and the interbeat intervals as well as the beating frequencies of the two pulsatile organs became identical in any one bee. Furthermore, heated bees engaged in vigorous abdominal pumping at the same frequency as that of their heart and ventral diaphragm pulsations. The results indicate that the anatomical counter-current heat exchanger is reduced or eliminated during heat stress by ‘chopping’ the blood flow into pulses, and the blood pulses are shunted through the petiole alternately by way of a switch mechanism.
The Effect of Partial Pressures of Inert Gases on the Behaviour and Survival of the Heterotrich Ciliate Spirostomum Ambiguum
Authors: MacDonald S. , Kitching J. A. 
Published: April 2021

ABSTRACT
A study has been made of the effects of helium, nitrogen and argon at partial pressures of 10–120 atm on the swimming speed, behaviour and survival of the heterotrich ciliate Spirostomum ambiguum. Experiments have also been carried out with hydrostatic pressure alone. Hydrostatic, helium and nitrogen pressures reduced the swimming speed approximately equally but pressure of argon reduced it to an even greater extent. Hydrostatic, helium, nitrogen and argon pressures caused a reduction in the number of reversals in a given time but the number of reversals/distance travelled did not change significantly. All the treatments increased the durations of individual forward movements. Pressures of helium, nitrogen and argon also increased the durations of reversals but at high hydrostatic pressures the durations of reversals were reduced.
Argon caused cytolysis at 30–40 atm and nitrogen at 80 atm; helium did not cause any visible cell damage over periods of 1 h at 120 atm. Addition of substantial partial pressures of helium protected Spirostomum against partial pressures of argon which would otherwise have caused cytolysis. The increase of hydrostatic pressure may have been responsible.
A study of the unidirectional fluxes of Na and Cl across the gills of the dogfish Scyliorhinus canicula (Chondrichthyes)
Authors: Bentley P. J. , Maetz J. , Payan P. 
Published: April 2021

ABSTRACT
The gills of the dogfish Scyliorhinus canicula are more permeable to Cl than to Na. In sea water, influx of Na and Cl exceeded the efflux of these ions. Under these conditions the fish were slightly electronegative, by about 2 mV, to the external solution. The net accumulation of Cl could be accounted for by diffusion along the observed electrochemical gradient but the movement of Na into the fish was more consistent with an electrically neutral active Na transport mechanism (using the Ussing flux ratio criterion). When the external pH was changed from 7·8 to 6·9, influxes of Na and Cl were depressed, while the effluxes were unaffected, and the fish became slightly less electronegative. In artificial solutions, in which the concentrations of Na and Cl were lowered and replaced with urea to maintain the total osmotic concentration, Na influx displayed saturation kinetics, while Na efflux increased with decreasing Na concentrations. Cl influx decreased linearly, while Cl efflux remained constant. The efflux of Cl could not be reconciled with a process of passive diffusion along any of the observed electrochemical gradients and thus could reflect the presence of an active transport mechanism.
The actions of some putative neurotransmitters on the cockroach salivary gland
Authors: Bowser-Riley F. , House C. R. 
Published: April 2021

ABSTRACT
Certain putative transmitters were applied to the innervated cockroach salivary gland and their effects on the resting potential and the neurally evoked secretory potential of the acinar cells were observed. γ-Aminobutyric acid, glutamate, glycine, aspartate and alanine had no significant effect on the resting potential. However, γ-aminobutyric acid and glutamate reduced the neurally evoked secretory potential but only at concentrations above 10−3 M. Acetylcholine and carbachol appeared to act by modifying transmitter output from the salivary nerves. These substances failed to have any effect on the resting potential. The biogenic amines, adrenaline, dopamine, noradrenaline, 5-hydroxy-tryptamine and octopamine, produced hyperpolarizing responses, graded according to concentration, It is suggested that dopamine, the most potent of the biogenic amines tested, is the transmitter at this junction.
Electrical activity of the proventriculus of the polychaete worm Syllis spongiphila
Authors: Anderson M. , del Castillo J. 
Published: April 2021

ABSTRACT
The striated myoepithelial cells of the proventriculus of Syllis spongiphila are composed of only one or two sarcomeres that may reach 40 µm in length. Experiments were performed to study some of their electrophysiological properties and their synaptic control. The mean resting potentials recorded in two different bathing media were 59·1 ± 5·5 mV (S.D., n = 91) and 62·5 ± 6·3 mV (S.D., n = 98). At rest the membrane potential is determined largely by permeability of the membrane to K + ions, but the membrane is also permeable to other ions. On a semilogarithmic plot of membrane potential v. [K]o the mean slope of the data points from 9 to 90 mm-[K]o was 48 ± 3 mV for a 10-fold change in [K]o. The anterior end of the animal was stimulated with a suction electrode to elicit activity of nerve fibres that innervate the proventriculus. Single indirect stimuli usually evoked hyperpolarizing or biphasic responses, and occasionally depolarizing responses, from the myoepithelial cells. The depolarizing synaptic potentials exhibited a faster time course than the hyperpolarizing ones. The rise time to peak ranged from 20 to 35 ms for simple depolarizations (n = 32) and 25−75 ms for simple hyperpolarizations (n = 103). Time to decay to half amplitude ranged from 20 to 55 ms for depolarizations (n = 29) and 62−135 ms for hyperpolarizations (n = 87). Low frequency (⩽ 4 Hz) trains of indirectly applied stimuli elicited mainly hyperpolarizing responses; higher frequency (5−40 Hz) trains elicited complex responses composed of hyperpolarizations and depolarizations. Hyperpolarizations were selectively and reversibly abolished in chloride-free solutions. The reversal potential of the hyperpolarizing synaptic potential was —104 ± 3 mV (S.D., n = 8, 2 preparations). In calcium-free solution both hyperpolarizations and depolarizations were almost completely abolished. 4 mm-Mn2+ added to the bath almost completely abolished the depolarization but not the hyperpolarization. It was not clear whether Mn2+ acted at the presynaptic membrane, the postsynaptic membrane or both. The myoepithelial cells are electrically coupled. The mean space constant of five preparations was 0·52 mm (range 0·40−0·66 mm).
Pressure Difference in Adjacent Segments and Movement of Septa in Earthworm Locomotion
Authors: Seymour Malcolm K. 
Published: April 2021

ABSTRACT
The nature and timing of septal movements during gentle crawling have been examined in relation to the coelomic pressure (Pc) in and between adjacent segments. Between neighbouring anterior segments the phase lag was 0·05−0·1 s and the maximum Pc difference 3·3 cm water. The mean Po in a leading segment exceeded that in a trailing segment by 0·9 ± 0·06 cm water. In forward crawling, the septa bulged maximally backward and forward when segments were half elongated and half shortened respectively, and were flat when segments were longest and shortest: the area of a septum in an elongated segment was one quarter that in a shortened one and thus a septum is strongest (small and thick) when the Pc to be longitudinally confined is highest. Bulging of septa is closely related to the intersegmental Pc difference. Bulging forces acting on a septum range from o to about 1 g wt. The pressure drop along a worm is not linear and the ventral foramina may act as ‘septal valves’ to equalize coelomic volume and pressure when required. The influence of gut, septum and body wall movements on each other is discussed.
The cardiac responses to shell opening and closure in the bivalve Arctica islandica (L.)
Authors: Taylor A. C. 
Published: April 2021

ABSTRACT
Shell closure in Arctica islandica is followed by an exponential decrease in the oxygen tension of the mantle cavity water and is accompanied by an initial increase in heart rate which is followed at lower oxygen tensions by a bradycardia. Prior to shell opening there is a slight increase in heart rate before any movement of the shell valves can be detected. However, once the shell opens and pumping activity recommences there is a rapid increase in heart rate, often to levels above normal.
Perfusion of the mantle cavity with water of high and low oxygen tension resulted in the cardiac responses normally associated with shell opening and closure. Recordings of the of the blood in the ventricle, made simultaneously with cardiac recordings, showed that the changes in heart rate were recorded only after the of the blood had changed. These experiments suggest that changes in the of the mantle cavity water may be primarily responsible for the cardiac responses to shell closure in Arctica.
Acoustical Properties of the Flight Activities of the Caribbean Fruit Fly
Authors: Webb J. C. , Sharp J. L. , Chambers D. L. , Benner J. C. 
Published: April 2021

ABSTRACT
The waveforms generated by the flight sounds of the Caribbean fruit fly Anastrepha suspensa (Loew) were recorded and analysed. These analyses included measurements of wingbeat frequency (WBF), sound pressure level (SPL) and harmonic content. The WBF and SPL were similar for both sexes but varied with fly maturity. A power spectral density (PSD) plot was made of the waveforms produced by each fly. These PSD plots showed waveform differences between young 1- to 4-day-old) flies and older flies, but these differences decreased with age. In flies more than 4-6 days old the waveforms remained relatively constant throughout the test period and were similar, for both sexes in that each contained discrete, narrow-band spectral lines in both the fundamental frequency and the harmonics.
The effect of caffeine on excitation-contraction coupling in skeletal and smooth muscle
Authors: Syson A. J. , Huddart H. 
Published: April 2021

ABSTRACT
For cockroach skeletal muscle, 2 mm caffeine considerably lowered the mechanical threshold without affecting the membrane potential. Contractures were induced by 8−10 mm caffeine. In rat ileal smooth muscle, 1−10 mm caffeine inhibited spontaneous contractile behaviour, abolished spike activity and reduced KCl-induced contracture tension. Enhanced spike activity associated with the KCl-induced phasic contraction was abolished by caffeine, the degree of caffeine-induced relaxation being proportional to the concentration employed. These relaxations were not accompanied by membrane hyperpolarization. The present results accord with previous work which has shown that caffeine increases myoplasmic free calcium in the skeletal muscle and lowers it in the smooth muscle. It is suggested that caffeine releases bound calcium in the former muscle and promotes binding in the latter. It is further suggested that in the smooth muscle caffeine may reduce the membrane permeability to calcium.
Receptor Units Responding to Movement in the Octopus Mantle
Authors: Boyle P. R. 
Published: April 2021

ABSTRACT
A preparation of the mantle of Octopus which is inverted over a solid support and which exposes the stellate ganglion and associated nerves is described. Afferent activity can be recorded from stellar nerves following electrical stimulation of the pallial nerve. The latency and frequency of the phasic sensory response is correlated with the contraction of the mantle musculature. It is proposed that receptor cells located in the muscle, and their activity following mantle contraction, form part of a sensory feedback system in the mantle. Large, multipolar nerve cells that were found between the two main layers of circular muscle in the mantle could be such receptors.
Neural Excitation of the Larval Firefly Photocyte: Slow Depolarization Possibly Mediated by A Cyclic Nucleotide
Authors: Oertel Donata , Case James F. 
Published: April 2021

ABSTRACT
In firefly larvae, extracellular recordings from the light organ nerve show that a volley of action potentials elicits a glow similar to the glow of an intact animal. Intracellular recordings from the photocytes show that they respond to nerve stimulation with a slow, graded depolarization which precedes light emission. The depolarization begins about 0·5 s after the nerve is stimulated ; it peaks about 1 s after stimulation; and subsides about 2·5 s after the stimulus. The glow increases fastest when the photocyte depolarization is at its peak and lasts 5–15 s. Photocyte depolarization is associated with a decrease in the input resistance of the cell. Adrenergic receptors in the light organ are pharmacologically similar to vertebrate α-receptors. Phosphodiesterase inhibitors, aminophylline and theophylline, cause the light organ to glow, suggesting that cyclic nucleotides may mediate the effect of the adrenergic nerve transmitter.
Adult Motor Patterns Produced by Moth Pupae During Development
Authors: Kammer Ann E. , Rheuben Mary B. 
Published: April 2021

ABSTRACT
Muscle potentials were recorded extracellularly from developing pupae and adults of the saturniid moths Antheraea polyphemus and A. pernyi and the sphingid moth Manduca sexta. During the week prior to the terminal ecdysis, developing moths still enclosed within the pupal cuticle produced motor patterns similar to those recorded from adults during flight and shivering. The pupal patterns had a longer cycle time and were more variable than the adult motor patterns. Characteristic inter-family differences in adult motor patterns were apparent in pupal motor patterns.
Development of motor patterns was followed over several days by observing individuals with chronically implanted leads. Early in the pupal period potentials were small and infrequent. The amount of activity gradually increased and became more patterned. As development proceeded adult patterns were produced for increasing lengths of time, although the patterns changed quickly and spontaneously.
Restricting the wing movements of A. polyphemus adults increased the cycle time, increased the number of spikes per burst in muscles opposing the restraint, and did not alter the interspike interval within a burst. The flight patterns produced by pharate moths, in which the wings are also immobile, also have a longer cycle time than that of adult flight, but the number of spikes per burst is the same and the interspike interval is longer than in adult flight. These observations suggest that the differences between pupal and adult patterns are not necessarily due to the confinement of the wings by the pupal cuticle.