bluuebunny/crossref_metadata_2025_split huggingface dataset:
The actions of FMRFamide-like peptides on visceral and somatic muscles of the snail Helix aspersa
Authors: Lehman H. K. , Greenberg M. J. 
Published: April 2021

ABSTRACT
Phe-Met-Arg-Phe-NH2(FMRFamide) and pyroGlu-Asp-Pro-Phe-Leu-Arg-Phe-NH2(pQDPFLRFamide) occur in the ganglia and tissues of the snail, Helix aspersa. This report describes the effects of these two neuropeptides on five visceral organs or somatic muscles isolated from the snail (Table 1).
The epiphallus, as well as the rest of the male reproductive tract, was contracted by both FMRFamide and pQDPFLRFamide, and the threshold was usually below 5 × 10−9mol 1−1(Fig. 1). Both peptides also reduced the resting tone of the crop and decreased the force and frequency of its rhythmic activity; FMRFamide is about 10 times more potent (Fig. 4). In contrast, pQDPFLRFamide was about 100 times more potent than FMRFamide as a cardioexcitatory agent (Fig. 5). The actions of the peptides on the pharyngeal and tentacle retractor muscles were markedly different: FMRFamide primarily contracted these muscles; and pQDPFLRFamide usually had no effect alone, but relaxed or diminished contractions induced by FMRFamide and acetylcholine (ACh) (Figs 6, 8, 9). Other analogues of FMRFamide were tested, but none was as effective a relaxing agent as pQDPFLRFamide. The effects of FMRFamide and pQDPFLRFamide on all of the preparations could be distinguished from those produced by ACh and 5-hydroxytryptamine (5-HT); thus the actions of the neuropeptides were not mediated by cholinergic or serotonergic neurones.
The stimulation of the musculature in the male reproductive tract and the inhibition of motility of the digestive system by FMRFamide and pQDPFLRFamide implicate these peptides in the control of reproductive behaviour. The effectiveness of pQDPFLRFamide in relaxing the retractor muscles and as a cardioexcitatory agent led to the hypothesis that this heptapeptide and FMRFamide, acting at distinct receptors, cooperate to regulate the excitability and contractility of the snail’s musculature between the extremes of aestivation and active locomotion.
Regulation of the Synthesis of Nerve Growth Factor
Authors: Heumann Rolf 
Published: April 2021

ABSTRACTThrough nearly 40 years of research nerve growth factor (NGF) has become a paradigm for neurotrophic factors. NGF is synthesized and released from innervated target tissues in limiting amounts, thereby regulating the cell number and the differentiated properties of responsive neurones. Three distinct cell types are responsive to NGF: peripheral sensory and sympathetic neurones and certain types of central cholinergic ones. The effects of NGF are mediated through interaction with a specific receptor which activates a transmembrane second-messenger system. NGF synthesis is regulated during development and in the adult animal. In the developing whisker pad, NGF synthesis commences with its sensory innervation, but sensory neurones lack NGF receptors at the stage when their fibres are growing to their target. These findings indicate that NGF does not attract sensory nerve fibres chemotactically to their target fields during development, but is involved in target-controlled neuronal cell death and in regulation of the density of innervation of target tissues. In non-neuronal cells of the sciatic nerve, NGF synthesis is up-regulated during development and after nerve lesion. Thus the changes in NGF levels after lesion in the adult animal are consistent with the hypothesis that the nonneuronal cells relapse into an earlier developmental stage. Regenerating fibres penetrating into the distal nerve stump restore the low adult levels of NGF. Recent evidence indicates that macrophages invading the nerve after transection produce signals which increase NGF synthesis.
Strengthening of Synaptic Inputs After Elimination of A Single Neurone Innervating the Same Target
Authors: Parnas I. 
Published: April 2021

ABSTRACT
The problem of ‘competition’ between neurones innervating the same target can be studied in simple neural systems such as the central nervous system of the leech and the lobster neuromuscular junction. Intracellular injection of pronase to kill selectively a single neurone shows that, in the leech, removal of one neurone is a sufficient signal to produce compensatory changes. After removal of a given neurone, only neurones of the same function respond to innervate the ‘vacant territory’. This was shown both for a motor neurone (annulus erector) and sensory neurones (T or N). Thus the response is very specific.
The lobster neuromuscular junction, with its multiple excitatory and inhibitory innervation, has advantages for the study of changes in synaptic efficacy of the remaining neurones after removal of a defined neurone releasing the same or a different transmitter. Killing the inhibitory neurone produced prolongation of the excitatory’ synaptic current because of a prolonged channel open time. When an excitatory axon is killed the remaining excitatory axon releases more transmitter. Over a period of 10 days, there is first a strengthening of existing synapses, then the appearance of new release sites and sprouting. Only those terminals of a neurone that innervate a territory with reduced innervation become stronger, while other terminals of the same axon remain normal. Cutting of axons produces different responses from those seen after killing single neurones.
The Use of Peripheral Nerve Grafts To Enhance Neuronal Survival, Promote Growth and Permit Terminal Reconnections in the Central Nervous System of Adult Rats
Authors: Bray Garth M. , Villegas-Pérez Maria Paz , Vidal-Sanz Manuel , Aguayo Albert J. 
Published: April 2021

ABSTRACT
During both development and regeneration, the survival of neurones and the growth of axons are controlled by inherent neuronal properties, conditions in the axonal environment, and the establishment of appropriately timed and specific functional contacts. To study the effects of extrinsic influences on the survival, growth and connectivity of axotomized neurones in the mature mammalian CNS, we replaced the optic nerve in adult rats with segments of autologous peripheral nerve (PN) and used morphometric techniques, neuroanatomical tracer substances and immunological cell markers to examine retinal ganglion cells (RGCs), their axons in the PN grafts and their terminals in the superior colliculi (SC) of these animals. We observed that: (1) the survival of axotomized RGCs was enhanced by the PN grafts; (2) in the PN-grafted eyes, approximately 20% of the surviving RGCs regrew their axons into the grafts and (3) some of the RGC axons that regenerated along the PN grafts bridging the eye and the tectum re-entered the SC, arborized and made synaptic contacts with tectal neurones. It is not known if the terminal connections established between RGCs and cells in the SC are appropriate, functional or capable of influencing the long-term survival of their cells of origin.
Net Uptake of CO2 Driven by Sulphide and Thiosulphate Oxidation in the Bacterial Symbiont-Containing Clam Solemya Reidi
Authors: Anderson A. E. , Childress J. J. , Favuzzi J. A. 
Published: April 2021

ABSTRACT
Solemya reidi Bernard is a gutless clam that lives in burrows in reducing sediments, and harbours intracellular sulphur-oxidizing bacteria in its gills. Clams were incubated in various concentrations of sulphide and thiosulphate for up to 65 h in a flow-through respirometer. Fluxes were determined by continuous sampling of the respiratory medium with analysis of CO2, O2 and sulphide by gas chromatography and analysis of thiosulphate, sulphite (and sulphide) by HPLC using mono-bromobimane-derivatized discrete samples. Net CO2 uptake was shown to occur with exposure to 50–100 μmol l−1 sulphide and greater than 225 μmoll−1 thiosulphate; sulphide oxidation and thiosulphate uptake were also demonstrated. 45CaCO3 deposition in the shells of S. reidi was found to be insignificant compared to the net CO2 flux measured in the presence of low levels of sulphide.
In experiments conducted under various O2 conditions, O2 limitation, produced by a combination of low [O2] and low water flow, was shown to inhibit sulphide oxidation and to prevent CO2 uptake. However, if O2 supply was not limited by low flow rates, in the presence of low [O2] (25–40 μmol l−1) S. reidi showed rates of O2 and sulphide consumption and CO2 uptake near the maximum levels determined under high [O2] conditions, indicating the potential for net CO2 uptake in the low [O2] conditions presumed to exist in the animal’s burrows.
Thiosulphate levels in the blood of S. reidi were analysed and shown to increase rapidly during incubation in sulphide. These levels reached an apparent steady state (approx. 300 μmoll−1) in recently captured clams after 1 h of incubation. However, both O2 limitation and time in captivity (&gt;43 days after capture) caused a marked increase in the blood thiosulphate levels, which exceeded 2·5 mmol l−1 after 16 h of exposure to sulphide. These results indicate that blood thiosulphate is transported to the bacteria and further oxidized, and that sulphide and thiosulphate oxidation are oxygen-dependent. In analyses of gill tissues for elemental sulphur, we found a wide range in the levels of sulphur stores. Calculations indicated these to be a small fraction of the total flux of sulphur maintained during continuous sulphide oxidation.
Estimates of CO2:O2:sulphide ratios suggest CO2 fixation efficiencies similar to those of chemolithoautotrophic bacteria. Assuming translocation and oxidation of symbiont-fixed organic compounds, the net uptake of CO2 by S. reidi in the presence of reduced sulphur compounds suggests that this intact symbiosis may be able to meet its organic carbon needs through autotrophy.
Carbohydrate Use in the Flight Muscles of Manduca Sexta During Pre-Flight Warm-Up
Authors: Joos Barbara 
Published: April 2021

ABSTRACT
Although fat is the principal fuel for flight in moths and butterflies, some use of carbohydrate fuels during activity would be predicted on energetic and biochemical grounds, particularly in nectivores. The present study evaluates the use of carbohydrate fuels during pre-flight warm-up in the endothermic sphinx moth Manduca sexta (L.). Carbohydrate content of moths was measured at intermediate points during the pre-flight warm-up cycle and at take-off. Muscle glycogen content declined during the initial phases of warm-up, whereas glucose and trehalose concentrations were unchanged. Abdominal carbohydrates were not mobilized during warm-up. Energy budget analysis suggests that glycogen oxidation supplies about 39% of the energy needed for the initial phase of warm-up and about 6% of the total cost of warm-up. Glycogen use during warm-up may be correlated with the capacity for endothermic warm-up at low ambient temperatures. Carbohydrates appear to be more important as fuels for activity in some lepidopterans than has been previously reported for other members of this diverse Order.
Acid-Base and Ionic Regulation in the American Eel (Anguilla Rostrata) During and After Prolonged Aerial Exposure: Branchial and Renal Adjustments
Authors: Hyde D. A. , Perry S. F. 
Published: April 2021

ABSTRACT
The involvement of the gill and kidney in acid-base regulation was examined in the American eel, Anguilla rostrata, during 36h of continuous air-exposure and subsequent return to water. While in air, eels developed a severe mixed respiratory/-metabolic acidosis. Renal acid excretion increased only slightly during the latter stages of air-exposure. A pronounced reduction in urine flow rate was important to minimize dehydration but essentially eliminated the kidney as a route for excess acid excretion. Upon return to the water, eels had accrued an extracellular metabolic acid load of 9·53 mmol 1−1. The metabolic acid was cleared from the extracellular compartment at an exceptionally low rate (approximately 70μmol kg−1 h−1) and about 50 % of the acid load remained after 18 h of recovery in water. The clearance of metabolic acid was accounted for by enhanced branchial acid excretion which was related primarily to adjustments of unidirectional Na+ fluxes. Unidirectional Cl− fluxes were undetectable using radiotracer methods. We speculate that the inefficiency of acid-base regulation in the eel compared to other teleosts is, in part, related to the absence of significant branchial C1−/HCO3− exchange.
A Functional Analysis Of The Primary Upstroke And Downstroke Muscles In The Domestic Pigeon (Columba Lima) During Flight
Authors: Dial K. P. , Kaplan S. R. , Goslow G. E. , Jenkins F. A. 
Published: April 2021

ABSTRACT
In domestic pigeons (Columba livia), the electrical activity of the major depressor muscle of the wing, the pectoralis (pars thoracicus), begins in late upstroke well before the wing begins its downstroke excursion. The two architecturally distinct heads of the pectoralis, the sternobrachialis and the thoracobrachialis, are differentially recruited during take-off, level flight and landing. In addition to wing depression, the sternobrachialis protracts the humerus and the thoracobrachialis retracts the humerus. At the point of transition from wing upstroke to downstroke, the pectoralis EMG signal typically exhibits a reduction in amplitude. The supracoracoideus, in addition to an expected EMG associated with wing elevation, is co-activated with the pectoralis about 50% of the time.
Acid-Base Regulation Following Acute Acidosis in Seawater-Adapted Rainbow Trout, Salmo Gairdneri: A Possible Role for Catecholamines
Authors: Tang Yong , Nolan Steven , Boutilier Robert G. 
Published: April 2021

ABSTRACT
A fall in blood pH was induced by intra-arterial infusion of HC1 in seawater-adapted rainbow trout (Salmo gairdneri). The acute acidosis resulting from HC1 infusion caused a short-lived decrease in plasma bicarbonate concentration ([HCO3−]) and an increase in arterial CO2 tension . Erythrocyte pH and bicarbonate concentrations were not significantly altered by the infusion of acid. Injection of acid did, however, stimulate a branchial net H+ efflux which could be primarily accounted for by a net uptake of bicarbonate equivalent ions from the environmental water.
Acid infusion of animals pre-treated with the β-adrenergic blocking agent, propranolol, induced a similar pattern of change in plasma acid-base status. However, the recovery of plasma pH and restoration of plasma [HCO3−] were slower than in animals infused with acid alone. Red cell pH fell significantly in the face of plasma acidosis in the β-blocked animals. Erythrocyte [HCO3−] showed a similar pattern of change to that of erythrocyte pH. Branchial net H+ efflux increased to a lesser extent following acid infusion in animals treated with propranolol.
We conclude that catecholamines released into the bloodstream during periods of acute acidosis may play an important role in facilitating branchial H+ efflux in seawater-adapted rainbow trout.
Discontinuous CO2 Emission in a Small Insect, the Formicine Ant Camponotus Vicixus
Authors: Lighton John R. B. 
Published: April 2021

ABSTRACT
Standard rates of oxygen consumption and CO2 production were measured by constant-volume respirometry in the formicine ant, Camponotus vicinus Mayr, at temperatures ranging from 10 to 40°C. Over this range, the Q10 with regard to was 1·79, and with regard to , 1·84. Multiple regression equations relating and of inactive ants to mass (0·016–0·088 g) and temperature were calculated. Periodic CO2 emissions (‘bursts’) were monitored with flow-through respirometry. Burst frequency increased exponentially with temperature (Q10 = 3·05), from 8·14h−1 at 15°C to 81·4h−1 at 35°C, and was not significantly correlated with body mass over the mass range (0·041–0·086g) investigated. Burst volume, which could be accurately measured in one ant, decreased with temperature (Q10= 0·61), thus yielding the observed Q10 of 1·84.
Analysis of Haemolymph and Muscle Acid-Base Status During Aerial Exposure in the Crayfish Austropotamobius Pallipes
Authors: Tyler-Jones R. , Taylor E. W. 
Published: April 2021

ABSTRACT
Exposure of the crayfish Auslropotamobius palhpes to air resulted in an acidosis in the postbranchial haemolymph (pHa) and the abdominal muscle. The haemolymph acidosis was subsequently compensated and, after 24 h in air, pHa had returned to the settled, submerged value. The intracellular acidosis remained uncompensated throughout the period of aerial exposure. When crayfish were first removed into air, lactate concentrations in the haemolymph and abdominal muscle increased substantially. After 24 h in air lactate concentrations in both compartments had returned towards submerged levels. Possibilities for the fate of lactate are discussed. Re-analysis of haemolymph acid-base data for crayfish exposed to air (Taylor & Wheatly, 1981) revealed discrepancies between observed and expected base excess. Initially these may arise from exchanges of H+ or HCO3− with other compartments. During long-term air exposure, the removal of lactate from the haemolymph and an independent accumulation of base, probably from the mobilization of an internal source of bicarbonate buffer, result in the observed pH compensation. Determination of base excess for the changes in abdominal muscle acid-base status after 3 h of exposure to air corroborated the results of the haemolymph analysis, suggesting a retention of H+ despite the efflux of lactate.
Functional Morphology of the Lungs of the Nile Crocodile, Crocodylus Niloticus: Non-Respiratory Parameters
Authors: Perry Steven F. 
Published: April 2021

ABSTRACT
The complex, multicameral lungs of the Nile crocodile are characterized by rows of tubular chambers, which in cranial and ventral lung regions are broad and sac-like. The inner surface of the chambers is enhanced by cubicles (ediculae), the capillary-bearing walls of which are often perforated. Extrabronchial communication among chambers is infrequent. The ediculae end in a network of myoelastic trabeculae, which face the central lumen of the chambers. The trabecular epithelium is similar to that of mammalian bronchi and contains isolated endocrine-hke cells basally, whereas the edicular epithelium is similar to that of other reptiles and of mammals. The distribution of non-vascular smooth muscle, 64% in trabeculae and 36% in interedicular walls, is consistent with the hypothesis that these two antagonistically oriented muscle groups interact to effect lung patency. The volume-specific lung compliance is similar to that of much simpler, unicameral gekko lungs, implying that lung compliance is a function of parenchymal structure and not of primary structural type.
The Effects of Temperature on Flight Muscle Potentials in Honeybees and Cuculiinid Winter Moths
Authors: Esch Harald 
Published: April 2021

ABSTRACT
Amplitudes of extracellular action potentials in indirect flight muscles of honey-bees and cuculiinid winter moths decline with decreasing muscle temperatures and fall suddenly to zero. Action potential durations increase with amplitude decline. Amplitudes at 11 °C are only 20% of values near 30°C in workers of Apis mellifera mellifera. They fall to zero at approx. 10°C. In the cuculiinid winter moth Eupsilia devia, amplitudes at 1°C are approx. 12% of values at 27°C. They fall to zero between 0 and 1°C. The duration of action potentials in bees and cuculiinid winter moths is about 7 ms at 27 °C and increases to 52 ms at 11 °C in bees and to 66 ms at 1°C in moths. The ratios of action potential rise time to fall time are about 1 at 27°C for bees and moths. They decrease to 0·45 at 11 °C in bees and to 0·56 at 1°C in moths. Results suggest that bees can heat flight muscles only if muscle temperatures are above 10°C, whereas cuculiinid winter moths can shiver with muscle temperatures near 0°C.
Ionic Currents in Neurones Cultured From Embryonic Cockroach (Periplaneta Americana) Brains
Authors: Christensen Burgess N. , Larmet Yves , Shimahara Takeshi , Beadle David , Pichon Yves 
Published: April 2021

ABSTRACT
Neurones isolated from embryonic cockroach brains were maintained in culture for up to 8 weeks. A single patch electrode was used to record voltage changes in response to injected current, membrane ionic currents under whole-cell voltageclamp conditions or single-channel currents from isolated membrane patches. The voltage changes in response to injected current that depolarized the cell indicated increases in membrane permeability to calcium and potassium. These observations were confirmed using a voltage clamp. The potassium current observed in the youngest cultures turned on with a delay and was blocked by tetraethylammonium (TEA) and 4-aminopyridine (4-AP). Two kinds of decrease in the outward potassium current were observed. One may be associated with extracellular potassium accumulation, inactivation of the potassium channel or inactivation of a calcium channel. The other appears to be a voltage-dependent inactivation. The magnitude of the calcium permeability appeared to increase as the cultures developed, being most prominent in cultures more than 2 weeks old. Single-channel conductance measured from an analysis of records from six isolated membrane patches ranged from 15 to 110pS. Except for one channel, the probability of the channels being open did not change appreciably with membrane potential. Our results suggest that much of the increase in potassium permeability may be due an increase in intracellular calcium level.
Solubility of Nitrogen and Argon in Eel Whole Blood and its Relationship to pH
Authors: Pelster B. , Kobayashi H. , Scheid P. 
Published: April 2021

ABSTRACT
The solubility coefficients (α) for the inert gases, nitrogen (N2) and argon (Ar), were measured by mass spectrometry in whole blood of the freshwater-adapted European eel, Anguilla anguilla, at varied pH and at two temperatures, 5 and 15°C. The pH was altered either by varying (0·75–75 mmHg; 1 mmHg = 133·3 Pa) or by adding fixed acid (HC1 or lactic acid).
No dependence of α on pH (range 5·5–8·4) or on lactate concentration (range 0·2–25 mmol l−1) was detectable. Average values (±S.D.) for α (μmol l−1 mmHg−1) were: at 5°C and at 15°C. These data yield values for Q10 of 0·87 for nitrogen and 0·82 for argon, and for activation energy, Ea (kJ mol−1 K−1), of –9· 2 for nitrogen and –13·4 for argon. The results do not support earlier reports on significant pH dependence of α in eel blood and suggest, in contrast, that no fundamental differences exist in respect of inert gas solubility between whole blood of the eel and of other vertebrates.
Empirical Estimates of Body Drag of Large Waterfowl and Raptors
Authors: Pennycuick C. J. , Obrecht Holliday H. , Fuller Mark R. 
Published: April 2021

ABSTRACT
Measurements of the body frontal area of some large living waterfowl (Anatidae) and raptors (Falconiformes) were found to vary with the two-thirds power of the body mass, with no distinction between the two groups. Wind tunnel measurements on frozen bodies gave drag coefficients ranging from 0·25 to 0·39, in the Reynolds number range 145 000 to 462000. Combining these observations with those of Prior (1984), which extended to lower Reynolds numbers, a practical rule is proposed for choosing a value of the body drag coefficient for use in performance estimates.