bluuebunny/crossref_metadata_2025_split huggingface dataset:
Drag and Lift on Running Insects
Authors: Full R. J. , Koehl M. A. R. 
Published: April 2021

ABSTRACT
We examined the effects of aerodynamic forces on the mechanical power output of running insects for which kinematic data were available. Drag and lift on the cockroaches Periplaneta americana (a small, rapidly running species) and Blaberus discoidalis (a larger, more slowly moving species) were measured in a wind tunnel. Although lift would be expected to affect power output by altering functional body weight, the magnitude of the lift on these cockroaches was less than 2% of their weight. Drag, which increases the horizontal force that must be exerted to run at a given speed, accounted for 20–30% of the power output of P. americana running at speeds of 1.0–1.5 ms−1, but had a much smaller effect on B. discoidalis. Aerodynamic drag on the body (parasite drag) can significantly increase the mechanical power output necessary for small, rapidly running insects in contrast to larger running animals and to flying insects.
Water Flows Around the Comb Plates of the Ctenophore Pleurobrachia Plotted by Computer: A Model System for Studying Propulsion by Antiplectic Metachronism
Authors: Barlow David , Sleigh Michael A. , White Richard J. 
Published: April 2021

ABSTRACT
Patterns of water flow around steadily beating comb plates of Pleurobrachia pileus were tracked using suspended plastic beads. The positions of the beads and the comb plates in the plane of the central longitudinal axis of the comb row were digitised from high-speed ciné films covering several beat cycles. All of the data from each sequence were combined using a computer program which integrated them into a standard cycle, and the resulting data were plotted by a second computer program to produce charts for different stages in the beat cycle showing the flow velocity at a grid of points. On these charts, contour maps were drawn to indicate the speed and direction of the water flow.
Water is drawn towards each comb row from ahead and from the sides and accelerates strongly backwards in a fairly narrow stream which joins those from the other seven comb rows at the rear of the animal. At a beat frequency of 10Hz the comb plates move with a tip speed of up to 70mm s−1 in their effective stroke; they have an estimated Reynolds number of 9 in this stroke. Changes in inter-plate volume between adjacent antiplectically coordinated plates are very important in propulsion, particularly near the end of the effective stroke when pairs of adjacent plates close together and cause the high-speed water from around the ciliary tips to be shed into the overlying stream as a series of jets at speeds of 50mms−1 or more. The antiplectic coordination of the comb plates makes a major contribution to the efficiency of propulsion.
Investigations of Lipid Components of Neurone-Enriched Membranes of the Jellyfish Cyanea Capillata
Authors: Schetz John A. , Anderson Peter A. V. 
Published: April 2021

ABSTRACT
The lipid components of nerve-rich tissues from the jellyfish Cyanea capillata were purified by multiple differential extractions of a single tissue pellet and detected with various chemical spray reagents following separation by thin-layer chromatography. The results indicate that gangliosides are completely absent from Cyanea capillata neurones, that the major sterol is not cholesterol, and that the five major phosphorus-containing lipids do not co-migrate with conventional phospholipid standards. The atypical lipid environment of Cyanea capillata neurones may account for some of their unusual physiological and pharmacological properties.
The effect of ambient Ph on electrolyte regulation during the postmoult period in freshwater crayfish Procambarus clarkii
Authors: Zanotto Flavia P. , Wheatly Michele G. 
Published: April 2021

ABSTRACT
The effects of ambient pH on postmoult net fluxes of Ca, acidic/basic equivalents (H+, NH4+/OH−, HCO3−), Na and Cl−, total body Ca, haemolymph pH and electrolyte status were assessed in the freshwater crayfish Procambarus clarkii (Girard). Variables were monitored for 5 days postmoult in acidic (pH5.2; H2SO4) or alkaline (pH9.2; KOH) artificial tap water (ATW) and compared with those in control (pH7.4) tap water. In control ATW there was an initial net influx of Ca (+2700 μmolkg−1 h−1) and titratable basic equivalents (+5000 μmolkg−1 h−1) that declined with time. Calcium uptake accounted for 40% of total body Ca (0.49mmol g−1); haemolymph Ca concentration remained constant. Haemolymph pH was initially relatively alkalotic (7.7) but recovered within 24h. A 20% haemolymph dilution by water uptake at ecdysis necessitated uptake of Cl− and Na for the first 2–3 days postmoult (+1000 μmolkg−1 h−). In acidic ATW, Ca and basic equivalent uptake were both 60% reduced during the first 3–4 days and total body Ca was reduced by 37%. Chloride and Na uptake and haemolymph [Cl−] were decreased. In alkaline ATW, Ca and basic equivalent uptake were elevated by 30% for the first 2 days and haemolymph alkalosis was maintained. Sodium and Cl−balance were unaffected. Thus, ambient pH affects Ca and basic equivalent fluxes associated with postmoult calcification. Regulation of Na and Cl−levels is also impaired in acidic ATW.
Contribution of the Na+/H+ Antiporter to the Regulation of Intracellular pH in a Crayfish Stretch Receptor Neurone
Authors: Mair N. , Moser H. , Fresser F. 
Published: April 2021

ABSTRACT
Regulation of intracellular pH (pHi) following acidosis induced by NH4+/NH3 exposures was re-investigated in a crayfish stretch receptor neurone using H+- and Na+-selective microelectrodes. All experiments were performed in nominally HCO3−/CO2 -free salines. From studies in Na+-free saline and from electrochemical calculations, we concluded that pHi regulation was dependent on extracellular Na+ concentration ([Na+]o ). The half-maximal rate of pHi recovery had an apparent Michaelis–Menten constant of 21mmol l− 1 [Na+]o. The use of this experimental approach and an improved technique enabled us to observe pHi regulation even in Cl− -free saline, in contrast to earlier findings. In addition, amiloride (2mmol l− 1) inhibited the maximum rate of pHi recovery by about 80%, SITS (1mmol l− 1) by about 20%.
The results strongly suggest the operation of two separate pHi-regulating mechanisms, a Na+-dependent HCO3− /Cl− antiporter (probably the Na+/H+/HCO3− /Cl− antiporter described earlier) and a Na+/H+ antiporter. Both mechanisms have been described in crayfish ganglion cells and muscle fibres, but the individual contribution to pHi regulation varies considerably in these preparations. Functional aspects of the pHi-regulating mechanisms in relation to ionic changes during the moulting cycle are discussed.
Effect of Amino Acid Deprivation on L-Alanine Uptake Through the Asc System in Freshly Isolated Trout Hepatocytes
Authors: Canals P. , Gallardo M. A. , Sánchez J. 
Published: April 2021

ABSTRACT
Fasting in mammals and other vertebrates induces an increase in the ability of liver to extract from blood gluconeogenic substrates, such as plasma amino acids, which can also be used as an energy source (Cowey et al. 1977; Newsholme and Leech, 1983). In mammalian hepatocytes, food deprivation induces the appearance of a high-affinity component for short-chain amino acid transport, with the properties of system A, while there are no changes in the activities of a low-affinity system (the ASC system), system L (Fehlmann et al. 1979) or glutamine uptake (Hayes and McGivan, 1982). ‘A’ is the abbreviation for a Na+-dependent carrier which has L-alanine and other short-chain neutral amino acids as preferred substrates. Its tolerance to N-methylated analogues differentiates it from the ASC system. ‘L’ is the abbreviation for a Na+-independent carrier which has L-leucine as preferred substrate. ‘asc’ is the abbreviation for a carrier similar to the ‘ASC’ carrier with respect to preferred substrates, but it is Na+-independent. The ASC system is a widely distributed, short-chain neutral amino acid carrier that transports alanine, serine, cysteine and threonine in a Na+-dependent mode, although the scope of its substrates is now thought to be wider than when it was first described in Erlich ascites tumour cells (Christensen et al. 1967). Characteristically, it does not accept N-methylated amino acid derivatives (allowing easy distinction from the A system).
The Mechanism of Flight Preparation in Some Insects
Authors: Krogh August , Zeuthen Erik 
Published: April 2021

ABSTRACT
In 1928 Dotterweich published under the title “Beitrâge zur Nervenphysiologie der Insekten” some very interesting and important observations and measurements mainly on Sphingidae, showing that the rapid vibration of the wings regularly observed in large moths before they take flight produces an increase in temperature of the wing muscles which is necessary to enable them to fly at all. The temperature reached was nearly the same in all cases, 32-34° C., and the time taken to reach it varied with the initial temperature deficit, up to 6 min. with a deficit of 23°. Moths kept at 34° or above would fly off at once, without any preparation, when stimulated. It had been assumed by v. Buddenbrock that this preparation was mainly required to attain the high frequency of the wing movements necessary for actual flight, but a number of observations made by Dotterweich on butterflies (Vanessa), in which the normal frequency is much lower, made it very probable that in these also preparatory wing movements were responsible for a rise in temperature necessary for actual flight.
The Melanin Content of the Skin of Rana Temporaria Under Normal Conditions and after Prolonged Light- and Dark-Adaptation. A Photometric Study
Authors: Dawes Ben 
Published: April 2021

ABSTRACT
Melanin has been extracted from dorsal and ventral components of the skin of English frogs by a simple method involving the leaching out of water-soluble pigments, the peptic digestion of washed skin, and the centrifugation of unaffected pigment. The melanin was estimated in NaOH solution with the aid of an indian-ink colour standard and by the use of a Duboscq colorimeter calibrated against suitable neutral density filters at various wave-lengths. Melanin varies greatly in amount in dorsal skins, some of which contain ten times as much of the pigment as others. In extreme duskiness and pallor, the difference may be fiftyfold. In spite of such variability, melanin formation seems generally to follow the usual laws of growth. Ventral pigmentation varies more than dorsal, ranging from an almost pigmentless condition to equality with dorsal pigmentation. The mean amount of melanin in ventral skin is about 27 % of that in dorsal skin. Melanin occurs in the skin of females at spawning time in large amount. Thus, the pale, red colour of the skin is not due to lack of the pigment. Melanin does not differ significantly in amount in the sexes. Melanin can be determined by careful visual judgement of the tone of the skin to within one-third of the total amount present in dark skin. The melanin content of dorsal skin is increased or decreased when frogs are kept for some weeks in equally illuminated light-absorbing (black) or lightscattering (white) surroundings. The skin of the dark-adapted animal contains 60 % more melanin than that of the light-adapted one after 5 weeks of treatment. The melanin content of the skin of a limb is increased under post-mortem conditions following intramuscular injection of post-pituitary extract into the freshly excised living limb. An increase of 27 % was determined. No effect is produced by adrenaline under these conditions. Prolonged adaptation to light-absorbing or light-scattering surroundings produces a more fundamental effect than the mere dispersion or aggregation of pre-existing melanin granules in the melanophores, namely, the production of fresh melanin or the degradation of this pigment. The subtractive process, which is evident microscopically, is due to some agent at present unknown. Frog melanin is shown by its absorption characteristics to be chemically very closely similar to, and possibly absolutely identical with, mammalian melanin and the pigment of melanoma.
The Structure and Conduction Velocity of the Medullated Nerve Fibres of Prawns
Authors: Holmes W. , Pumphrey R. J. , Young J. Z. 
Published: April 2021

ABSTRACT
The structure of the myelinated fibres of prawns is described, and the homologies of the nucleated sheath which lies between the axon and the fatty layer discussed. The relative thickness of the myelin sheath increases with decrease in total diameter of the fibre along à curve similar in shape to that found in vertebrates and earthworms. Nodes of Ranvier are found in the sheaths of most fibres of a diameter greater than about 13µ. The nodes are similar to those in vertebrate nerves in that the myelin sheath is interrupted at the node. The conduction velocity of fibres in the central nervous system of axon diameter 26µ and total diameter 35µis between 18 and 23 m. per sec., a rate faster than is found in the “unmyelinated” fibres of similar size in other crustacea.
The Pigmentation of Cavernicolous Animals
Authors: Baldwin Ernest , Beatty R. A. 
Published: April 2021

ABSTRACT
The widespread reduction of pigmentation found in cavernicolous animals is discussed. The externally visible coloration of Asellus aquaticus Linn., A. meridianas Rac., and A. aquaticus cavernicolas Rac., appears to be of the melanin type. The melanin content of A. aquaticus is not appreciably affected if this animal is kept in the dark for periods of several months. Offspring produced during this period are. normal in colour. Fertile young resulted from a cross between a colourless female A. aquaticus cavernicolus and a normally pigmented male A. aquaticus. This observation is probably of significance for the genetical analysis of the colour types found among the hypogean asellids. The predominant pigments of A. aquaticus, apart from melanin, are β-carotene and cryptoxanthine. Other carotenoid pigments are present only in traces.
The Influence of Various Physical and Biological Factors of the Environment on Honeybee Activity. An Examination of the Relationship Between Activity and Solar Radiation
Authors: Butler C. G. , Finney D. J. 
Published: April 2021

ABSTRACT
A review of the literature shows that those who have studied the influence of solar radiation on honeybee activity are agreed that it is an important limiting factor. This is in general agreement with observations made by beekeepers.
Brittain et al. (1933) give a detailed account of the effects of solar radiation on honeybee activity, and claim that, as might be expected from the work of Bertholf (1931, 1931 a), a higher correlation between activity and the intensity of ultra-violet radiation exists than between activity and rádiation of clear light. However, fresh analysis of their data throws considerable doubt on their conclusions.
New data were collected which clearly show an association between variations in honeybee activity and the radiation of clear light.
What Ears Do For Bats: A Comparative Study Of Pinna Sound Pressure Transformation In Chiroptera
Authors: Obrist Martin K. , Fenton M. Brock , Eger Judith L. , Schlegel Peter A. 
Published: April 2021

ABSTRACT
Using a moveable loudspeaker and an implanted microphone, we studied the sound pressure transformation of the external ears of 47 species of bats from 13 families. We compared pinna gain, directionality of hearing and interaural intensity differences (IID) in echolocating and non-echolocating bats, in species using different echolocation strategies and in species that depend upon prey-generated sounds to locate their targets. In the Pteropodidae, two echolocating species had slightly higher directionality than a non-echolocating species. The ears of phyllostomid and vespertilionid species showed moderate directionality. In the Mormoopidae, the ear directionality of Pteronotus parnellii clearly matched the dominant spectral component of its echolocation calls, unlike the situation in three other species. Species in the Emballonuridae, Molossidae, Rhinopomatidae and two vespertilionids that use narrow-band search-phase echolocation calls showed increasingly sharp tuning of the pinna to the main frequency of their signals. Similar tuning was most evident in Hipposideridae and Rhinolophidae, species specialized for flutter detection via Doppler-shifted echoes of high-duty-cycle narrow-band signals. The large pinnae of bats that use prey-generated sounds to find their targets supply high sound pressure gain at lower frequencies. Increasing domination of a narrow spectral band in echolocation is reflected in the passive acoustic properties of the external ears (sharper directionality). The importance of IIDs for lateralization and horizontal localization is discussed by comparing the behavioural directional performance of bats with their bioacoustical features.
The Effect of Serotonin (5-Hydroxytryptamine) on Glycolysis in the Perfused Ventricle of the Freshwater Bivalve Anodonta Cygnea: Evidence for Phosphorylation/Dephosphorylation Control of Phosphofructokinase
Authors: Michaelidis Basile , Rofalikou Evagelia , Beis Isidoros 
Published: April 2021

ABSTRACT
The ventricles of the freshwater mollusc Anodonta cygnea were isolated and perfused with serotonin in order to examine its effect on glycolysis. Serotonin induces an increase in the concentration of glycolytic intermediates. Phosphofructokinase (PFK) preparations from ventricles perfused with serotonin exhibited an increased sensitivity to activation by the substrate fructose 6-phosphate (F6P) and to the activators AMP and fructose 2,6-bisphosphate (F2,6P2) and a reduced sensitivity to inhibition by ATP. In vitro phosphorylation/dephosphorylation experiments revealed that incubation of PFK preparations from ventricles perfused with normal saline in the presence of ATP, cyclic AMP and MgCl2 alters the degree of activation by F6P. In contrast, when enzyme preparations from ventricles treated with serotonin were incubated in the presence of alkaline phosphatase and MgCl2, PFK showed a reduced sensitivity to activation by F6P. Serotonin had no significant effect on the kinetic properties of PK, while it increased the proportion of the active a form of glycogen phosphorylase. These results indicate that serotonin induces an increase in the concentration of glycolytic intermediates in the ventricle of A. cygnea and that this is at least partly due to the activation of PFK, possibly via phosphorylation by an endogenous cyclic-AMP-dependent protein kinase.
Action of the Hypaxial Muscles During Walking and Swimming in the Salamander Dicamptodon Ensatus
Authors: Carrier David R. 
Published: April 2021

ABSTRACT
Activity of the hypaxial muscles during walking and swimming was measured in the salamander Dicamptodon ensatus. During walking, there was activity on both sides of the trunk simultaneously. The obliquus externus superficialis and profundus muscles were active on the side towards which the trunk was bending (flexing), while the obliquus internus and transversalis muscles were active on the opposite side. In contrast, during swimming, all four of these muscles were active on the side of the trunk that was bending to become concave. These observations are consistent with the hypothesis that during terrestrial ambulation the obliquely oriented hypaxial muscles do not contribute to lateral bending of the trunk or to horizontal propulsion, but to stabilization of the trunk against long-axis torsion.
The Effects of SDRNFLRFamide and TNRNFLRFamide on the Motor Patterns of the Stomatogastric Ganglion of the Crab Cancer Borealis
Authors: Weimann James M. , Marder Eve , Evans Bruce , Calabrese Ronald L. 
Published: April 2021

ABSTRACT
TNRNFLRFamide was isolated and sequenced from the stomatogastric nervous system of the crab Cancer borealis by reverse-phase high performance liquid chromatography followed by automated Edman degradation. An SDRNFLRFamide-like peptide that exactly co-migrated with SDRNFLRFamide was also observed. The effects of TNRNFLRFamide and SDRNFLRFamide on the gastric and pyloric rhythms of the stomatogastric nervous system of the crab Cancer borealis were studied. Both peptides activated pyloric rhythms in quiescent preparations in a dose-dependent manner with a threshold between 10 −11 and 10−10 mol l−1. Both peptides increased the pyloric rhythm frequency of preparations showing moderate activity levels and had relatively little effect on preparations that showed strong pyloric rhythms prior to peptide application. Both peptides evoked gastric mill activity in preparations without existing gastric rhythms. The activation of the gastric rhythm is associated with activation of oscillatory properties in the dorsal gastric neurone. The induction of gastric rhythms by these peptides was accompanied by switches from pyloric-timed activity to gastric-timed activity by several stomatogastric ganglion neurones. Application of these peptides provides direct experimental control of circuit modification in the stomatogastric nervous system.
Neuromuscular Organization in the Swimming System of the Pteropod Mollusc Clione Limacina
Authors: Satterlie Richard A. 
Published: April 2021

ABSTRACT
Swim motor neurons of the pteropod mollusc Clione limacina were identified by a combination of electrophysiological and morphological characteristics. Two types of motor neurons were found, including small motor neurons which are active during both slow and fast swimming and which innervated restricted fields of the ipsilateral wing. General excitor motor neurons have large cell bodies, innervate widespread fields and are recruited into activity for fast swimming. Small motor neurons monosynaptically innervate slow-twitch muscle cells, whereas general excitors monosynaptically innervate both slow-twitch and fast-twitch muscle cells. Activity in general excitors can centrally enhance that in small motor neurons because the neurons are electrically coupled. Neuromuscular recordings and lesion experiments indicate that a peripheral nerve network does not appear to play an important role in the spread of excitation throughout the muscle fields.
Metabolic Control of Luminescence in Isolated Photophores of Porichthys: Effects of Glucose on Oxygen Consumption and Luminescence
Authors: Mallefet J. , Baguet F. 
Published: April 2021

ABSTRACT
Basal oxygen consumption of isolated photophores from Porichthys sp. at rest, i.e. without light emission, increased significantly from 0.101±0.021nmolmin−1 to 0.173±0.016nmolmin−1 in response to the addition of 5.5mmol l−1 glucose. 5.5mmol l−1 glucose pretreatment modified the time course of the two phases of adrenaline-induced luminescence; an increase in oxygen consumption was observed during the fast phase of light production but a decrease occurred during the slow phase of luminescence. Pretreatment of isolated photophores with 5.5mmol l−1 glucose totally inhibited the light emission induced by 1mmol l-1 potassium cyanide. With this treatment, the respiration rate decreased progressively and after 40min reached a value not significantly different from zero. Even after blockage of cellular respiration by cyanide, an increase in the rate of oxygen consumption was observed during the fast adrenaline-induced luminescence. Glucose utilisation by glycolysis or by oxidative metabolism may provide energy to an inhibitory mechanism that maintains the photophores in a non-luminescent state. We suggest that the oxygen consumed during the fast phase of adrenaline luminescence could represent the activity of an extramitochondrial oxidative pathway involved in the light reaction.