bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations On the Blood of Certain Ascidians, with Special Reference to the Biochemistry of Vanadium
Authors: Webb D. A. 
Published: April 2021

ABSTRACT
The blood of a number of species of Ascidiacea has been examined with reference to the presence of the vanadium chromogen described by Henze, and the results are discussed in connexion with the data available from other authors. The chromogen is always contained, together with sulphuric acid, in a special type of cell described as a vanadocyte. These are found only in the Ascidiidae and Perophoridae, though members of certain other families contain vanadium in some other form. The distribution within the group of sulphuric acid in vesicular cells of the blood and test is also discussed. There is no reason to suppose that the pigments of Ascidians, other than the chromogen itself, are vanadium compounds. A curious type of cell inclusion from the orange pigment cells of Ascidia mentula is described.
Experimental evidence and theoretical considerations are brought forward to show that the vanadium chromogen is not in any sense a respiratory pigment. At present no function can be ascribed to it. It is not a protein or porphyrin compound, but seems to consist of vanadium in association with a straight chain complex of pyrrol rings, comparable perhaps to a bile pigment.
It seems possible that sea water provides a sufficiently rich source of vanadium to account for the amounts absorbed.
The phylogenetic aspects of these facts are considered in relation to Berrill’s recent re-classification of the Ascidiacea. The presence of vanadium is a primitive character which has been lost in the more specialized families.
Size and Power in Mammals
Authors: Heusner Alfred A. 
Published: April 2021

ABSTRACT
The relationship between basal metabolism P and body mass M of 391 mammalian species has been analysed by least-squares regression, robust regression and covariance analyses. This relationship is a power function:
where the mass exponent b is 0.678±0.007 (mean±S.D.) and the mass coefficient a takes different values. Theory of measurement revealed that the 2/3 mass exponent is due to an underlying dimensional relationship between the primary quantity of mass and the secondary quantity of power.
This paper shows that the 2/3 mass exponent is not the physiological problem of interest. It is not the slope of the metabolic regression line, but its location in the mass/power plane, that must be explained. This location is given by the value of the mass coefficient, the explanation of which is, and remains, the central question in comparative physiology.
Locomotor Performance and Energetic Cost of Sidewinding by the Snake Crotalus Cerastes
Authors: Secor Stephen M. , Jayne Bruce C. , Bennett Albert F. 
Published: April 2021

ABSTRACT
We measured the performance (burst speed and endurance) and the energetic cost of sidewinding locomotion for the viperid snake Crotalus cerastes. The linear scaling regressions relating log mass to log burst speed and log endurance have slopes of 0.29 and 1.01, respectively. Maximal burst speed observed for an individual snake (SVL=41.9cm, SVL is snout-vent length) was 3.7 km h1. Adult snakes were able to match a tread speed of 0.5 km h−1 for times ranging from 33 to more than 180 min, and at 0.7 km h−1 endurance times ranged from 9 to 52 min. Rates of oxygen consumption increased linearly over a range of aerobically sustainable speeds (0.28−0.50 km h−1), with a resulting net cost of transport (NCT) of 0.408 ml O2g−1 km−1 for eight snakes with a mean mass of 110g. Sidewinding of C. cerastes involves periodic movements with a frequency that increases linearly with mean forward speed. At 0.50 km h-1, the mean (N=8) mass-specific energetic cost per cycle of movement was 0.28μl O2g−1cycle−1 for sidewinding. The NCT and the cost per cycle of movement of C. cerastes sidewinding are significantly less than those of similar mass snakes (Coluber constrictor) performing either terrestrial lateral undulation or concertina locomotion. The NCT of C. cerastes sidewinding is also significantly less than that predicted for the terrestrial limbed locomotion of lizards of similar mass. Mean C. cerastes (0.405 ml O2g−1h−1) is only about half that reported for C. constrictor; however, the mean endurance at 0.60 km h−1 (73 min) for sidewinding C. cerastes does not differ significantly from that reported for C. constrictor laterally undulating.
The Effects of Temperature on the Oxygen Consumption, Heart Rate and Deep Body Temperature During Diving in the Tufted Duck Aythya Fuligula
Authors: Bevan R. M. , Butler P. J. 
Published: April 2021

ABSTRACT
Six tufted ducks were trained to dive for food at summer temperatures (air, 26°C, water, 23°C) and at winter temperatures (air, 5.8°C, water 7.4°C). The mean resting oxygen consumption at winter temperatures (Twin) was 90% higher than that at summer temperatures (Tsum), but deep body temperatures (Tb) were not significantly different.
Diving behaviour and mean oxygen consumption for dives of mean duration were similar at Twin and at Tsum, although the mean oxygen consumption for surface intervals of mean duration was 50% greater at Twin and Tb was significantly lower (1°C) at the end of a series of dives in winter than it was in summer.
There appears to be an energy saving of 67 J per dive during winter conditions and this may, at least partially, be the result of the metabolic heat produced by the active muscles being used to maintain body temperature. While at rest under winter conditions, this would be achieved by shivering thermogenesis. Thus, the energetic costs of foraging in tufted ducks in winter are not as great as might be expected from the almost doubling of metabolic rate in resting birds.
Proprioceptive Input From two Basal Joint Stretch Receptors to Leg Motoneurones in the Isolated Thoracic Ganglion of the Shore Crab
Authors: Head Stewart I. , Bush Brian M. H. 
Published: April 2021

ABSTRACT
The reflex effects and interactions of two proprioceptors upon motoneurones supplying the four basal leg muscles of the shore crab Carcinus maenas have been studied in a new in vitro preparation consisting of the thoracic-coxal muscle receptor organ (TCMRO) and the coxo-basal chordotonal organ (CBCO) isolated together with the whole thoracic ganglion complex to which they were still connected by their afferent nerves. Each receptor strand was stimulated mechanically, while recording intracellularly from motoneurones in the ganglion, and extracellularly from the cut motor nerves innervating the promotor and remotor muscles of the thoracic-coxal (T–C) joint and the levator and depressor muscles of the coxo-basal (C–B) joint.
Stretch of the TCMRO evoked reflex firing in several units in the promotor motor nerve, confirming previous studies. In addition to this ‘intrajoint’ reflex, however, TCMRO stretch also elicited ‘interjoint’ reflex responses in moto-neurones of both the levator and depressor muscles. Similarly, stretch and release of the CBCO produced intrajoint resistance reflexes in levator and depressor motoneurones, respectively, as well as interjoint reflexes in promotor and remotor motoneurones. In general, the CBCO produced stronger reflex effects in all four motor nerves than did the TCMRO.
Intracellular recordings from individual motoneurones of all four muscles revealed that the majority of them received convergent input from both proprio-ceptors. The importance of such convergent input in vivo is discussed.
Humoral Induction of Pyloric Rhythmic Output in Lobster Stomatogastric Ganglion: In Vivo and In Vitro Studies
Authors: Rezer Elizabeth , Moulins Maurice 
Published: April 2021

ABSTRACT
In the lobster Jasus lalandii, 14 neurones of the stomatogastric ganglion (STG) are organized in a network that produces rhythmic pyloric outputs. In vitro experiments have shown that the STG neurones receive, via the stomatogastric nerve (stn), neuromodulatory inputs that influence the expression of the bursting properties of the neurones and the ability of the network to produce its rhythmic output.
In contrast to these in vitro observations, in vivo transection of the stn does not abolish the pyloric rhythm. Rhythmic output can be recorded by electromyogra-phy immediately after stn transection and for up to 2 years afterwards. We have shown that, under these experimental conditions, the STG appears to be isolated from any neuronal input that might account for the maintenance of the rhythmic output. Experiments carried out in the 2 days after stn transection showed that an in vitro preparation of the isolated STG was unable to produce any rhythmic output, but blood serum added to the system could restore the pyloric output.
These results suggest strongly that the pyloric network receives neural and humoral modulatory influences in parallel and that each type of influence alone is able to maintain the bursting capability of the pyloric neurones.
The Influence of Temperature on Muscle Function in The Fast Swimming Scup: II. The Mechanics of Red Muscle
Authors: Rome Lawrence C. , Sosnicki Andrzej , Choi In-Ho 
Published: April 2021

ABSTRACT
To understand better how scup can swim twice as fast as carp with its red muscle, we measured the mechanical properties of red muscle bundles in scup. The values of the mean maximum velocity of shortening (Vmax) at 10°C (3.32musclelengthss−1) and at 20°C (5.55 muscle lengths s−1 ; Q10=1.69) were nearly the same as those in carp. Isometric force, however, was approximately 50% greater (183 kN m− 2; Q10 =1.08). The maximal power generation was correspondingly about 50% greater in scup than in carp (71 Wkg−1 at 10 °C and 134Wkg−1 at 20°C; Q1O=1.88). The larger power output of its muscle may be important in the faster swimming of the scup. In addition, the fact that scup use a less undulatory style of swimming means that, when they are swimming twice as fast, their red muscle shortens at the same velocity (V) and with the same V/Vmax (0.37, i.e. where maximum power is generated) as that of carp.
The importance of V/Vmax is further shown by the comparison of scup swimming at different temperatures. The 1.69-fold higher Vmax at 20°C than at 10°C enables scup to swim with a 1.67-fold faster V at 20°C. Thus, at both 10°C and 20°C, red muscle is used only over the same narrow range of V/Vmax (0.17-0.37), where experiments on isolated muscle suggest that power and efficiency are maximal. Therefore, V/Vmax appears to be an important design constraint that limits the range of velocities over which muscle is used in vivo, both at different temperatures and in fast-and slow-locomoting species.
Patch-Clamp Analysis of the Effects of the Insecticide Deltamethrin on Insect Neurones
Authors: Amar M. , Pichon Y. , Inoue I. 
Published: April 2021

ABSTRACT
The mode of action of the pyrethroid insecticide deltamethrin on inexcitable embryonic cultured cockroach neurones has been investigated using the patchclamp technique. Whole-cell recordings of the current induced by step depolarizations of the cell membrane showed that concentrations of deltamethrin ranging from 10−8 to 5x10−6moll-− induced a small tetrodotoxin (TTX)-sensitive inward current that peaked at around + 10 mV and reversed at around +60 mV. The activation and inactivation kinetics of this current were much slower than those of the axonal sodium current in this same species and were relatively insensitive to membrane potential. Steady-state inactivation was almost absent. Single-channel activity associated with the action of the insecticide was analyzed using the cell-attached configuration. Three distinct patterns of activity were found: (1) discrete single-channel events of relatively short duration, (2) long events of comparatively small amplitude and (3) complex bursts made up of a succession of openings and closings to several levels. These three patterns were analyzed quantitatively using specially designed programs. The first pattern of activity could be seen in most patches. It consisted of short (1-lOms) rectangular events of comparatively small amplitude (1.5pA at rest) and very low open time probability (around 0.001). The current-voltage relationship of these small events was linear over the voltage range studied and the (extrapolated) reversal potential approximated ENa. The second pattern of activity was observed less frequently. The channels could stay open for very long periods (up to several seconds) and occasionally flickered between two or more levels. The third pattern of activity was observed in many patches. During the burst, which could last from a few milliseconds to a few hundred milliseconds, the singlechannel current jumped almost continuously between several levels (up to 7 or 8). The size of the different (single-channel) current levels was the same for the three patterns of activity. Furthermore, these levels corresponded to multiples of the same minimum level (around 1 pA at the resting potential). These results suggest that deltamethrin activates several states of one or several populations of sodium channels.
Physiological Response of the Atlantic Cod (Gadus Morhua) to Hypoxia at Various Environmental Salinities
Authors: Claireaux Guy , Dutil Jean-Denis 
Published: April 2021

ABSTRACT
Atlantic cod (Gadus morhua L.) acclimated to water salinities ranging from 28 ‰ to 7 ‰ were exposed to mild (8.0 kPa) or severe (4.0 kPa) hypoxic conditions for 6h. In each experiment, respiratory, acid–base, ionic, haematological and metabolic disturbances were analyzed. During mild hypoxia, a strong hyperventi-latory response was observed, resulting in a respiratory alkalosis that persisted throughout the 6-h trial. Plasma Cl− and pyruvate levels were the only other variables to display significant changes: they both increased. In more severe hypoxic conditions, although the ventilatory response was the same, a weak metabolic acidosis was superimposed. The haematological response (increased haematocrit and decreased mean cellular haemoglobin content) suggested that catecholamines were released into the blood. Both Na+ and Cl− concentrations increased significantly. Metabolic perturbations occurred: plasma lactate, pyruvate and glucose concentrations increased markedly. Though lactate concen-trations in liver, heart and white muscle increased, the concentrations of pyruvate, glucose and glycogen did not change significantly. Water salinity affected the amplitude of the ionic responses during hypoxia: the amplitude decreased with decreasing salinity. Irrespective of water salinity, 23 of 29 fish survived the severe hypoxic conditions. This relatively good tolerance of low water oxygenation, as compared with other marine bottom-feeders, suggests that this species may face poorly oxygenated waters in the wild. Together with temperature and salinity, water oxygen content may thus be an important variable to take into account in the study of the distribution and migration patterns of Atlantic cod.
Fish Skin: An Effective Barrier to Ice Crystal Propagation
Authors: Valerio Paul F. , Kao Ming H. , Fletcher Garth L. 
Published: April 2021

ABSTRACTIt has been well established that antifreeze peptides are responsible for the ability of many marine teleosts to survive in icy sea water at temperatures below the colligative freezing points of their blood. However, the in vivo site of antifreeze action has yet to be determined. One current hypothesis, the ‘iceexclusion hypothesis’, suggests that antifreeze proteins act within epithelial membranes (skin, gills, gut) and block the entry of external ice crystals. This hypothesis was examined by measuring ice propagation temperatures across isolated skin samples from the winter flounder (Pseudopleuronectes americanus). The results obtained were consistent with the hypothesis, indicating that fish skin is an effective barrier to ice propagation and that the effectiveness of this barrier improves with the addition of antifreeze proteins. The results also demonstrated that the skin ice propagation temperatures were substantially lower than the lethal freezing temperatures of the fish. Therefore, some other epithelial tissue (possible gill) must be less effective than the skin in blocking ice crystal penetration into the fish.&gt;
The Quality of Vision in the Ctenid Spider Cupiennius Salei
Authors: Land M. F. , Barth F. G. 
Published: April 2021

ABSTRACT
Much is known about the mechanosensory behaviour of the spider Cupiennius salei Keyserling, but much less about its visual capabilities. In this study the quality of the optical image, the retinal resolution and the fields of view were assessed for each of the four pairs of eyes. The image is of good quality in all eyes. The principal (antero-median) eyes lack a tapetum and have an inter-receptor angle of 2.9°. The three secondary eyes (antero-lateral, postero-median and posterolateral) all have ‘gridiron’ tapeta with receptors arranged in rows. The angular separations (along rows × between rows) are 3.6° × 9.3°, 0.9° × 2.3° and 1.0° × 3.0°, respectively. Although the disposition of eyes on the head is similar to that of pisaurid spiders, all other features of the eyes, including the sizes and shapes of the fields of view, resemble those of lycosid spiders. The peripheral visual system of Cupiennius can thus, in principle, support a similar range of visual behaviour to that of lycosids, which includes prey capture, predator avoidance and courtship.
Some Properties of the Mammalian Locomotory and Respiratory Systems in Relation to Body Mass
Authors: Young Iain S. , Warren Ruth D. , Altringham John D. 
Published: April 2021

ABSTRACT
Video and ciné films of mammals running at the trot-gallop transition were analysed to measure breathing frequencies. Breathing frequency at the trotgallop transition (fb, in Hz) was shown to decrease with increasing body mass (M, in kg) and was described by the equation fb=5.08M-0 14. The stiffness of the thorax and diaphragm of mice, rats, rabbits and wallabies was calculated and this, together with the mass of the viscera, was used to calculate the natural frequency of the system (nft, in Hz). The relationship between nft and body mass can be described by the equation nft=5.02Mf-0.18. The significance of these results is discussed in relation to models of mechanical linkage between respiratory and locomotory movements.
Pitching Equilibrium, Wing Span and Tail Span in a Gliding Harris’ Hawk, Parabuteo Unicinctus
Authors: Tucker Vance A. 
Published: April 2021

ABSTRACT
The centre of area of the wings of a Harris’ hawk gliding freely in a wind tunnel moved forward 0.09 wing chord lengths when the hawk increased its wing span from 0.68 to 1.07 m. The movement of the centre of area probably produces a positive pitching moment that, if unopposed, would cause the bird’s head to rise. The tail remained folded until wing span reached 87 % of maximum and then began to spread. This behaviour is also typical of gliding birds in nature, which spread their tails when the wings are near maximum span. Tail spreading probably produces a negative pitching moment that compensates for the forward movement of the wings at maximum span. As the tail spread, its centre of area moved backwards. This movement, together with the increase in tail area, can keep the centre of area of the combined wings and tail from moving forward, even at maximum wing span. The tail can generate an estimated 10% of the hawk’s total lift at maximum wing span and 5 % or less at shorter wing spans. I moved the centre of area of the hawk’s wings forward experimentally by clipping 76 mm from primary feathers 6–10 and 38 mm from primary feather 5. The effect of this operation on the hawk’s behaviour indicated that the forward movement of the centre of area of the wings caused a positive pitching moment. The hawk pitched up more in flight. It held its wings at shorter than normal spans, which partially compensated for the effects of clipping by moving the centre of area of the wings backwards. It also spread its tail at shorter than normal spans, which would compensate for an increase in the pitching moment of the wings.
The Effect of Stress and Starvation on Brain Serotonin Utilization in Arctic Charr (Salvelinus Alpinus)
Authors: Winberg Svante , Nilsson Göran E. , Olsén K. Håkan 
Published: April 2021

ABSTRACT
The effects of stress and starvation on brain levels of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were studied in Arctic charr (Salvelinus alpinus). Three experimental protocols were used to elucidate (1) the effect of stress in fish given food, (2) the effect of starvation, and (3) the effect of stress in fish deprived of food. In the stress experiments, fish were stressed three times a day over a four-week period, and in the starvation experiment the fish were starved for a four-week period. Stressed fish, whether given food or not, showed significantly higher concentrations of 5-HIAA, the main 5-HT metabolite, in both the telencephalon and the brain stem. The 5-HIAA/5-HT ratio (an index of serotonergic activity) was also significantly increased in the brain of stressed fish. In the telencephalon of starved fish, the 5-HT concentration was significantly decreased. However, starvation had no effect on 5-HIAA concentrations or 5-HIAA/5-HT ratios in either the telencephalon or the brain stem. These results suggest that stress increases brain serotonergic activity in Arctic charr, while starvation has no effect on the utilization of this transmitter system. It is suggested that stress could be a mediator of the increased 5-HIAA levels and 5-HIAA/5-HT ratios recently observed in low-ranking Arctic charr in a dominance hierarchy.
Recovery From Acute Haemolymph Acidosis in Unfed Locusts II. Role of Ammonium and Titratable Acid Excretion
Authors: Harrison Jon F. , Phillips John E. 
Published: April 2021

ABSTRACTIn this study we characterized acid, ammonium and total urate excretion in the faecal pellets of unfed locusts (Schistocerca gregaria) and examined the effect of haemolymph acidosis (HCl injections into the haemocoel) on net acid and nitrogen excretion. In unfed, uninjected locusts, the pH of the urinary pellets was less than 5, and ammonium was excreted at three times the rate of total urate. Ammonium was present primarily as a precipitate, indicating that ammonium excretion is compatible with water conservation in this desert locust. Ammonium excretion was increased by HO injections, theoretically accounting for 15 % of the acid equivalents removed from the haemolymph during recovery from acute acid loads. Luminal pH in the hindgut was affected by feeding state but not by haemolymph acidosis. HC1 injections did not affect faecal pellet pH or the excretion rates of bicarbonate, titratable acid, pellet buffer compounds (urate, inorganic phosphate), Na+, K+, Ca2+, Mg2+ or Cl-. In unfed locusts, the low rate of excretion and low pH of faecal pellets may limit the capacity to increase titratable acid excretion after acid-loading.
Brain Neurones Involved in the Control of Walking in the Cricket Gryllus Bimaculatus
Authors: Böhm Hartmut , Schildberger Klaus 
Published: April 2021

ABSTRACT
The responses of single brain neurones to artificial calling song, to moving striped patterns and to air puffs were recorded while tethered crickets were walking on a sphere in such a way that their intended orientation to the stimuli could be measured.
Local and descending brain neurones responsive to only one of the stimuli tested often encoded the directional information contained in the stimulus (e.g. the direction of the sound source or the direction of stripe movement). Brain neurones with little directional sensitivity responded with marked habituation to all stimuli, so that their responses primarily signalled changes in the overall stimulus situation.
The responses of some neurones were stronger during walking than when the cricket was standing still. In the case of one descending neurone, which increased its level of activity shortly before and during the walking phases, the mean spike rate was correlated with the forward velocity. By altering the discharge rate of another descending neurone, it was possible to elicit walking in the manner typical of crickets. Maintenance and control of walking by such ‘command neurones’ is discussed.