bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endothermy in the Solitary Bee Anthophora Plumipes: Independent Measures of Thermoregulatory Ability, Costs of Warm-Up and the Role of Body Size
Authors: Stone Graham N. 
Published: April 2021

ABSTRACT
This study examines variation in thoracic temperatures, rates of pre-flight warm-up and heat loss in the solitary bee Anthophora plumipes (Hymenoptera; Anthophoridae). Thoracic temperatures were measured both during free flight in the field and during tethered flight in the laboratory, over a range of ambient temperatures. These two techniques give independent measures of thermoregulatory ability. In terms of the gradient of thoracic temperature on ambient temperature, thermoregulation by A. plumipes is more effective before flight than during flight. Warm-up rates and body temperatures correlate positively with body mass, while mass-specific rates of heat loss correlate negatively with body mass. Larger bees are significantly more likely to achieve flight temperatures at low ambient temperatures. Simultaneous measurement of thoracic and abdominal temperatures shows that A. plumipes is capable of regulating heat flow between thorax and abdomen. Accelerated thoracic cooling is only demonstrated at high ambient temperatures. Anthophora plumipes is able to fly at low ambient temperatures by tolerating thoracic temperatures as low as 25°C, reducing the metabolic expense of endothermic activity. Rates of heat generation and loss are used to calculate the thermal power generated by A. plumipes and the total energetic cost of warm-up under different thermal conditions. The power generated increases with thoracic temperature excess and ambient temperature. The total cost of warm-up correlates negatively with ambient temperature.
The Locust Ovipositor Opener Muscle: Properties of the Neuromuscular System
Authors: Belanger Jim H. , Orchard Ian 
Published: April 2021

ABSTRACT
A new preparation for studying properties of neuromuscular transmission and neuromodulation in insects, the ventral opener muscle of the locust ovipositor, is described. It consists of the complete musculoskeletal apparatus of the ventral opener muscle and the associated abdominal ganglia containing the central pattern generator that drives oviposition digging. In this preparation it is possible to record simultaneously motoneurone activity, muscle electromyograms, intracellular muscle fibre activity and behaviourally relevant tension production. The muscle displays ultrastructural and physiological characteristics typical of insect intermediate-type fibres: abundant sarcoplasmic reticulum, active Ca2+-dependent membrane responses, phasic contractions when stimulated by high-potassium saline and a low twitch:tetanus ratio. Superfused glutamate (10−4 mol l−1) and proctolin (10−8 mol l−1) induce contractions of the muscle, while GABA (10−4 mol l−1) reduces potassium-induced depolarizations. HPLC, bioassay and immunological methods show that proctolin is associated with all of the ventral ovipositor muscles, and combined back-filling/immunohistochemistry suggests that at least one of the ventral opener motoneurones is proctolinergic.
The Locust Ovipositor Opener Muscle: Proctolinergic Central and Peripheral Neuromodulation in a Centrally Driven Motor System
Authors: Belanger Jim H. , Orchard Ian 
Published: April 2021

ABSTRACT
The pentapeptide proctolin has multiple effects on the locust oviposition digging system. At the neuromuscular junction of the ventral opener muscle, it has a concentration-dependent range of modulatory effects. At low concentrations (10−10 mol l−1), proctolin causes an increase in the frequency of miniature excitatory junctional potentials, but has no apparent effects on the muscle membrane or contractile properties. In the middle range of concentrations (approximately 10−9 mol l−1) proctolin increases neurally evoked twitch tension three-to fourfold with little change in the basal tension. At high concentrations (&gt;10−8 mol l−1), proctolin causes a large increase in basal tension, upon which is occasionally superimposed a slow (approximately 0.3–0.5Hz) myogenic rhythm. Stimulation of the ventral opener nerve at 30Hz for 5min releases approximately 8% of the proctolin store of the muscle. In vitro ganglion–muscle preparations which are expressing the oviposition digging rhythm produced in the terminal abdominal ganglion release about 25% of the store of endogenous proctolin during 5min of superfusion. This declines to below the level of detectability over about 20min of superfusion. Muscle contractions decline and then cease over the same period, although the patterned neural input and muscle electromyogram responses are still present. Superfusion of 10−9 mol l−1 proctolin restores the muscle contractions to their original magnitude. Superfusion of 10−8 mol l−1 proctolin over preparations in which the oviposition digging pattern has slowed results in the frequency of the rhythm being restored to its original levels. We suggest that, rather than having a facultative modulatory role in this neuromuscular system, proctolin is required for it to function normally. Furthermore, proctolin may maintain the functional integrity of the central systems driving oviposition digging.
Conopressin G Increases Bursting Activity in Command Neurons Mediating Respiratory Pumping in Aplysia Californica
Authors: Martinez-Padron Manuel , Lukowiak Ken 
Published: April 2021

ABSTRACT
Periodic spontaneous gill movements (SGMs) are one of the most obvious of the 21 general action patterns described in the ethogram of Aplysia californica (Leonard and Lukowiak, 1986). SGMs are thought to be a prime component of Aplysia’s respiratory cycle (Koester et al. 1974; Byrne and Koester, 1978) and in the intact animal the frequency of SGMs can be modified by changes in the partial pressures of CO2 and O2 of the sea water (Croll, 1985; Levy et al. 1989).
Energetic Cost of Locomotion as a Function of Ambient Temperature and During Growth in the Marsupial Potorous Tridactylus
Authors: Baudinette R. V. , Halpern E. Annette , Hinds David S. 
Published: April 2021

ABSTRACT
In the marsupial, the potoroo, multiple regression analysis shows that ambient temperature makes a minor (2%) contribution towards variation in oxygen consumption with speed. This suggests that the heat generated during running is substituted for heat which would otherwise have to be generated for temperature regulation. Maximum levels of oxygen consumption are also temperature-independent over the range 5–25°C, but plasma lactate concentrations at the conclusion of exercise significantly increase with ambient temperature. Adult potoroos show a linear increase in oxygen consumption with speed, and multiple regression indicates that the most significant factor affecting energy use during running is stride length. Juvenile potoroos have an incremental cost of locomotion about 40% lower than that predicted on the basis of body mass. The smaller animals meet the demands of increasing speed by increasing stride length rather than stride frequency, as would be expected in a smaller species. Our results show that juvenile potoroos diverge significantly from models based only on adult animals in incremental changes in stride frequency, length and the cost of transport, suggesting that they are not simply scaled-down adults.
Primary Cultures Of Epithelial Cells From Rainbow Trout Gills
Authors: Pärt P. , Norrgren L. , Bergström E. , Sjöberg P. 
Published: April 2021

ABSTRACT
A method for obtaining primary cultures of epithelial cells from rainbow trout gills is described. The yield of cells from approximately 1.5g wet mass of tissue was 218×106±12×106 cells with a viability defined by eosin exclusion of 80±6%. Cells were seeded in culture dishes and grown in Leibowitz L-15 medium supplemented with 5 % foetal bovine serum. Attachment efficiency after 24h was 35±6%. The cells appeared confluent 10–12 days after seeding and exhibited surface structures similar to those seen on respiratory epithelial cells of trout gills in vivo. Growth rate, [3H]thymidine incorporation and attachment efficiency were used to evaluate culture conditions. Epidermal growth factor, insulin, transferrin, hydrocortisone, laminin and collagen did not improve growth and attachment. Similarly, coating the culture dishes with rat tail collagen, trout skin extract, laminin or a mixture of human basement membrane proteins (Matrigel) failed to improve attachment. It is concluded that the cells in culture are respiratory epithelial cells and that this culture system could provide a valuable new approach for studying the physiology of these cells.
Coordination of Wing Beat and Respiration in Canada Geese During Free Flight
Authors: Funk Gregory D. , Sholomenko Gerald N. , Valenzuela Ignacio J. , Steeves John D. , Milsom William K. 
Published: April 2021

ABSTRACT
It remains unclear whether coordination of wing and respiratory movements is universal among birds during flight (Tomlinson, 1963). However, it is certain that many species demonstrate some form of coordination between wing and respiratory movements (Marey, 1890; Groebbels, 1932; Zimmer, 1935; all cited in Hart and Roy, 1966; Tomlinson, 1957, 1963; Lord et al. 1962; Hart and Roy, 1966; Berger et al. 1970b; Butler et al. 1977; Butler and Woakes, 1980). Ratios of wing beat frequency to respiratory frequency (fW/fV) ranging from 1:1 to 5:1 have been described, some species showing variation in fW/fV (Lord et al. 1962; Berger et al. 1970b; Butler and Woakes, 1980).
An Annular Respirometer for Measuring Aerobic Metabolic Rates of Large, Schooling Fishes
Authors: Lucas M. C. , Johnstone A. D. F. , Tang J. 
Published: April 2021

ABSTRACT
Aerobic metabolic rates of fish at controlled levels of activity are usually measured with individual fish isolated in a flume-type respirometer, in which the fish must swim against a known water velocity (Brett, 1964; Beamish, 1978; Gehrke etal. 1990). Their use for large and fast-swimming fish is difficult owing to engineering problems and water turbulence and because swimming in the confined test section of the respirometer affects the performance of the fish. Some of these problems have been partially dealt with by applying corrections to compensate for the altered water flow around the body of the fish (Webb, 1971) and by developing highly sophisticated flume respirometers (Gehrke et al. 1990).
Generation of Monoclonal Antibodies Detecting Specific Epitopes in Locust Antennae
Authors: Strotmann J. , Boekhoff I. , Göggerle S. , Breer H. 
Published: April 2021

ABSTRACT
Following a tissue-specific screening paradigm, monoclonal antibodies have been generated that interact with distinct subpopulations of cells in locust antennae. Antigens were identified as high molecular weight components. Immunoreactivity was not detectable during embryonic development, but rapidly appeared within a few hours of hatching. The time course of antigen expression in antennal cells could be followed in situ as well as invitro. Expression of monoclonal antibody B14/6D2-like immunoreactivity was prevented by blocking protein synthesis with cycloheximide.
Quantitative Analysis of Chemoaccumulation in Specimens of Paramecium Caudatum in Relation to Their Motile Activities
Authors: Nakazato Hiroyuki , Naitoh Yutaka 
Published: April 2021

ABSTRACT
The quantitative relationship between chemoaccumulation and locomotor activity in specimens of Paramecium caudatum was examined by employing a novel chemoaccumulation assay system. Distribution of the specimens in two adjoining solutions with different chemical compositions was dependent on both the rate of arrival of the specimens at the border between two solutions (the arrival rate) and the ratio of the number of specimens crossing the border to that arriving at the border in unit time (the pass ratio). The arrival rate was higher when the forward swimming velocity was higher and when the frequency of spontaneous avoiding responses was lower. The pass ratio was higher when the degree of the avoiding response at the border was lower. The translocation rate was defined as the number of specimens crossing from one solution to another in unit time, corresponding to the product of the arrival rate and the pass ratio. In the steady-state condition, the distribution ratio, which is defined as the ratio of the number of specimens in the test solution to that in the reference solution, was proportional to the ratio of the translocation rate towards the test solution from the reference solution to that towards the reference solution from the test solution. When specimens showed a higher arrival rate in one solution than the other the pass ratio was lower, so that the arrival rate and the pass ratio acted antagonistically in establishing chemoaccumulation. The involvement of membrane-potential-mediated changes in the motile activity of specimens in establishing chemoaccumulation is discussed.
Guanine Nucleotides Modulate Calcium Currents in a Marine Paramecium
Authors: Bernal Juan , Ehrlich Barbara E. 
Published: April 2021

ABSTRACT
Voltage-dependent calcium channels play a critical role in many cell functions and in many cell types ranging from protozoa to vertebrates. We have shown previously that guanine nucleotides modulate the calcium action potential and the duration of backward swimming in Paramecium, both indirect measurements of calcium channel function. To determine whether guanine nucleotides do indeed alter calcium currents, the inward calcium current (ICa) in Paramecium calkinsi was studied. First, the calcium current was characterized. The magnitude of ICa increased as the extracellular calcium concentration was increased from 0.5 to 50mmol l−1, unlike the situation in freshwater species of Paramecium where the inward calcium current magnitude is maximal when extracellular calcium levels reach 1mmoll−1. Inorganic compounds (NiCl2 at 10 μmoll−1 and CdCl2 at 1mmol l−1) and organic compounds (naphthalene sulfonamides, W-7 and W-12-Br at 100 and 2 μmol l−1, respectively) reduced ICa. Regardless of the holding membrane potential (from −80 to −20mV), the threshold activation for ICa was at −10mV and the maximum value of ICa was reached at +20mV, suggesting that there is only one type of calcium channel in P. calkinsi. Second, we injected GTPγS, GTP and GDPβS into voltage-clamped cells while monitoring calcium and/or potassium currents. GTPγS increased the magnitude of ICa by 42±6% (mean ± S.D., N=5) and the effect was irreversible, GTP increased the magnitude of ICa by 37±4% (N=4) in a reversible manner, and GDPβS decreased ICa by 57±8% (N=3) irreversibly. The outward potassium currents did not change when GTPγS was injected into the cells. These results support the hypothesis that injection of guanine nucleotides modulates the voltage-dependent calcium channel in P. calkinsi, presumably by activating G-protein-dependent processes.
Transcellular Intestinal Calcium Transport in Freshwater and Seawater Fish and its Dependence on Sodium/Calcium Exchange
Authors: Schoenmakers TH. J. M. , Verbost P. M. , Flik G. , Bonga S. E. Wendelaar 
Published: April 2021

ABSTRACT
Transepithelial calcium uptake and transcellular calcium uptake mechanisms were compared in the proximal intestine of freshwater- and seawater-adapted tilapia, Oreochromis mossambicus. Stripped intestinal epithelium of seawater fish showed a higher paracellular permeability to calcium in vitro. Net transepithelial calcium uptake was 71% lower, reflecting a physiological response to the increased inward calcium gradient. Na+/K+-ATPase activity was significantly enhanced in enterocytes of seawater- adapted fish, in line with the water transport function of the intestine in seawater fish. The Vmax and the Km values for Ca2+of the ATP-dependent Ca2+ pump in seawater fish enterocytes were 28% and 27%, respectively, lower than in freshwater fish. The Km for Ca2+ of the Na+/Ca2+ exchanger was 22% lower, and a 57% decrease in the Vmax for Ca2+ of the exchanger was observed. Apparently, the density of exchanger molecules in the basolateral plasma membrane is reduced in seawater fish. From the correlation between the differences in net intestinal calcium uptake and Na+/Ca2+ exchange activity we conclude that Na+/Ca2+ exchange is the main basolateral effector of transcellular calcium uptake.
Separating the Effects of Temperature and Viscosity on Swimming and Water Movement by Sand Dollar Larvae (Dendraster Excentricus)
Authors: Podolsky R. D. , Emlet R. B. 
Published: April 2021

ABSTRACT
The small size and slow movement of aquatic, microscopic organisms means that the viscosity of water has a predominant influence on their motion. Temperature, through its effects on physiological processes, also influences motion. Because water viscosity is physically coupled to temperature, changes in temperature can influence the activity of microscopic organisms through both physiological and physical means. To partition these effects, we artificially altered seawater viscosity and, at two temperatures, we measured swimming speed and water movement by larvae of the sand dollar Dendraster excentricus. Over an environmentally relevant, 10-degree drop in water temperature (22 to 12°C), swimming speed was reduced by approximately 40% and water movement was reduced by 35%. 40% of the decrease in swimming speed and 55% of the decrease in water movement were accounted for by increases in viscosity alone. The physical effects of viscosity can therefore make up a large component of the effect of temperature on activity of microscopic organisms. If uncorrected for effects of viscosity, temperature coefficients such as Q10 values can overestimate the influence of temperature on the physiological processes that underlie the generation of motion at small spatial scales. These changes in viscosity may cause substantial reductions or increases in swimming and feeding rates that are biologically relevant. Environmental variation in viscosity due to temperature fluctuations could lead to temperature responses or adaptations that are nonphysiological.
Acetate, Butyrate and Proline Uptake in the Caecum and Colon of Prairie Voles (Microtus Ochrogaster)
Authors: Hume I. D. , Karasov W. H. , Darken B. W. 
Published: April 2021

ABSTRACT
We have measured unidirectional uptake (not transmural flux) of acetate, butyrate and proline by everted sleeves of intact tissue from the jejunum, caecum, proximal colon and distal colon of prairie voles (Microtus ochrogaster).
There was active (i.e. Na+-dependent) transport of L-proline in the jejunum, but we found no evidence for it in any region of the hindgut (i.e. the caecum, proximal colon and distal colon). Uptake of acetate was carrier-mediated in all three regions of the hindgut, but the Jmax and apparent Km (⩽1.5mmol l−1) were low, and uptake was primarily passive over the concentration range 10–50mmol l−1, which spanned measured acetate levels in the caecum and proximal colon. At 100mmol l−1, acetate uptake (nmolmin−1 cm−2) was higher (P&lt;0.001) in distal colon (359±33) than in the proximal colon (225±17) and caecum (150±5) (mean ± S.E., N=8). Uptakes summed over the length of each region were also higher (P&lt;0.001) in the distal colon at 100mmol l−1, but not at low concentrations (0.1mmol l−1).
Uptakes normalized to diffusion coefficents were higher for butyrate than acetate and were lowest for L-glucose (which is absorbed passively via an aqueous pathway) in all regions, indicating that uptake of the short-chain fatty acids involves solubilization in the lipid bilayer of the apical membrane. The short-chain fatty acids absorbed from the hindgut of the vole were equivalent to 22% of standard metabolic rate or 15% of resting (but fed) metabolic rate.
Lateral Line Stimuli Can Override Vision to Determine Sunfish Strike Trajectory
Authors: Janssen John , Corcoran Jim 
Published: April 2021

ABSTRACT
Although all fishes have a mechanosensory lateral line system – a system of water flow detectors (neuromasts) in canals or free on the skin’s surface – particular behavioral functions are documented for only a few species. Work on lateral line use for feeding has focused on either cavefishes or night-active species (Montgomery, 1989). While surface-feeding fishes with well-developed eyes do use the lateral line to locate prey (Müller and Schwartz, 1982), it is generally assumed that diurnal/crepuscular fishes are visual predators. We show that a hydromechanical stimulus detected by the cephalic lateral line system in two sunfishes (Centrarchidae) can be the sole determinant of a strike trajectory. The response occurs without reinforcement and appears to be an unconditioned response. Green sunfish (Lepomis cyanellus Rafinesque) and largemouth bass (Micropterus salmoides Lacépède) are North American sunfishes that inhabit ponds, lakes and slow streams. Both species have diverse diets, including invertebrates and fishes (Carlander, 1977). These species and their congeners are active during the day; at night in field and laboratory they lie near or on the bottom and are lethargic (Neill and Magnuson, 1974; Helfman, 1981). Both species have cones and rods in the retina; the green sunfish visual pigments are characteristic of crepuscular mid-water fishes (Dearry and Barlow, 1987;
Development of Connections by Axons Growing Through Injured Spinal Cord of Neonatal Opossum in Culture
Authors: Woodward S. K. A. , Treherne J. M. , Knott G. W. , Fernandez J. , Varga Z. M. , Nicholls J. G. 
Published: April 2021

ABSTRACT
The ability of neurites to grow through a lesion and form synaptic connections has been analyzed in a developing mammalian spinal cord in vitro. After isolation of the entire central nervous system (CNS) of the newly born South American opossum (Monodelphis domestica) the spinal cord was crushed. Outgrowth through and beyond the lesion was observed in living preparations for 2–5 days by staining axons with carbocyanine dyes. The structure of the acute crush and the growing neurites was examined by light and electron microscopy in tissue fixed immediately after the crush had been made. All axons had been severed and the site was filled with debris and amorphous vesicular structures. By 3 days after injury, numerous labelled neurites had grown into the lesion; by 4 days, many had extended several millimetres beyond it. At this time normal axonal profiles were apparent in electron micrographs of the crush site. Although fewer axons grew across the lesion than had been severed by the crush, the amplitudes of compound action potential volleys conducted across the crush in injured preparations were comparable with those recorded from uninjured spinal cords. Physiological experiments made with raised concentrations of extracellular magnesium in the culture fluid indicated that growing axons had formed synaptic connections. Thus, delayed major peaks of the response were abolished while the small component corresponding to through conduction remained unaffected by magnesium. These experiments demonstrate the development of synaptic interactions by the growing neurites and confirm the far greater powers of repair in neonatal mammals compared to adults. They set the stage for comparing molecular mechanisms involved in development and regeneration of the mammalian CNS.