bluuebunny/crossref_metadata_2025 huggingface dataset:
Optokinetic Responses, Visual Adaptation and Multisensory Control of Eye Movements in the Spiny Lobster, Palinurus Vulgaris
Authors: Neil D. M. , Schöne H. , Scapini F. , Miyan J. A.
Published: April 2021

The optokinetic responses of the spiny lobster, Palinurus vulgaris, were measured in the vertical roll plane. The eyes followed the stripes without nystagmus, and demonstrated incomplete bilateral coupling. Closed-loop responses to oscillating stripes (20 ° peak-to-peak) showed marked habituation at frequencies above 0·l Hz, but at lower frequencies continued undiminished, with amplitude-gain values approaching 1·0. Changes in illuminance level demonstrated that the optokinetic response exhibited a threshold below which the eye initially failed to detect and follow the stripes. However, over a period of several minutes, the previous response level could be restored or even exceeded. The optokinetic response could be antagonized by a response to the irradiance gradient, which also had a threshold and showed adaptation. Migration of visual screening pigments may underlie these adaptation processes. Optokinetic stimuli could interact with proprioceptive inputs arising from displacements of the legs on a moving platform. When the proprioceptive inputs were of equal frequency and in antiphase, the optokinetic response was reduced in amplitude; it was in phase with the visual stimulus at low frequencies, and in phase with the platform in the high-frequency range. When the inputs had unequal frequencies, the eyes followed the drum if its frequency was low, but failed to follow either drum or platform if drum frequency was high. We conclude that multisensory control extends the frequency range of operation of compensatory eye movements, and is dominated by the low-frequency optokinetic response.
Mechanical Responses of A Crustacean Slow Muscle
Authors: Chapple William D.
Published: April 2021

Mechanical properties of the abdominal ventral superficial muscle of the hermit crab, Pagurus pollicarus, were examined under isometric and iso-velocity conditions. The muscle was activated by stimulating its motor nerve at different frequencies. Length-isometric tension relations were measured. Peak tension, P0, was 0·16–0·2 MN m−2 and the sarcomere length of the muscle at the optimum length, L0, was 10·8 + 1·0 μm. Passive tension was high at L0. Correlated measurements of the operating length of the muscle and L0 indicate that the operating length is at a point on the ascending limb of the length-tension curve approximately 0·77 L0. The relationship between activation level of the muscle and the length-tension relation indicates that the curve is not substantially displaced along the length axis by increasing activation level; increased force is primarily due to an increase in the slope of the ascending limb of the curve. The force-velocity relation was obtained by measuring the force at a reference length during iso-velocity shortening of an active muscle. Hill constants of a/P0 = 0·11 + 0·02 and b = 1·07 + 0·24 mm s−1 were obtained. The maximum velocity of shortening per half sarcomere was approximately 4·2μms−1, Stretch of an active muscle did not produce an abrupt short range yield but a gradual transition between short range and terminal stiffness. This behaviour is shown to be due not to differences in cross bridge stiffness between VSM and other muscle but to a non cross bridge stiffness with a value that is one-fifth that of vertebrate muscle. Such a low stiffness may provide an intrinsic mechanism for simplifying load compensation in the absence of rapid proprioceptive reflexes for the control of muscle stiffness.
Effects of Ionophore-Mediated Transport On the Cardiac Resting Potential
Authors: Fahim Mohammad , Mangel Allen , Pressman Berton C.
Published: April 2021

The monovalent carboxylic ionophores form lipid-soluble complexes with alkali cations which transport these ions across membranes. In a biological setting, they promote an electrically neutral exchange of intracellular potassium for extracellular sodium (Pressman, 1976). The ionophore monensin, which has a complexation preference for sodium (Pressman, 1968), has very little capability for complexing or transporting calcium or catecholamines (Pressman, Painter & Fahim, 1980). However, monensin produces a strong positive inotropic effect (Pressman, Harris, Jagger & Johnson, 1967; Sutko et al. 1977; Shlafer, Somani, Pressman & Palmer, 1978; Saini, Hester, Somani & Pressman, 1979) which is attenuated, but not abolished, by β-adrenergic blockade (Sutko et al. 1977; Shlafer et al. 1978; Saini et al. 1979). This indicates that the inotropic effect is partially mediated through an indirect release of catecholamines and, also, through a more direct mechanism, presumably by an alteration of transcellular cation gradients. Studies with cardiac Purkinje fibres show that monensin produces a shortening of the action potential, without an accompanying alteration in the resting potential (Sutko et al. 1977; Shlafer et al. 1978). Inasmuch as monensin should decrease the transcellular gradients of both sodium and potassium, one would expect that not only the action potential, dominated by the sodium diffusion potential, but also the resting potential, dominated by the potassium diffusion potential, should decrease. The present investigation was directed toward resolving the paradox of why monensin fails to alter the resting potential of cardiac muscle segments under the same conditions which alter the action potential. Our results show that depolarization of the resting potential, induced by monensin, is normally masked by the activity of the electrogenic sodium pump, and if the pump is inhibited by ouabain, then the expected depolarization is observed.
‘Instant’ Analysis of Movement
Authors: Godden D. H. , Graham D.
Published: April 2021

The study of walking and other dynamic behaviour patterns has challenged the experimental ingenuity of researchers since Muybridge first demonstrated in a series of still pictures that galloping horses raise all four legs from the ground at once. The use of moving film improves the situation but still suffers from a fundamental disadvantage in the time required to process and analyse the changes in the image from frame to frame. A number of suggestions have been made to make film analysis more time effective but the difficulties are an inherent feature of the storage medium.
Aerial Manoeuvring Reflexes in Flightless Grasshoppers
Authors: Arbas Edmund A.
Published: April 2021

Aerial locomotion of many insects involves jumping or dropping from elevated positions. Flight and aerobatic manoeuvring often follow locust jumps, while jumps from elevated positions can carry flightless grasshoppers several metres through the air. Leg postures and orientation movements associated with aerial locomotion have been studied in the flightless grasshopper, Barytettixpsolus (Cohn & Cantrall, 1974).
Regulation Of The Acid-Base Status During Environmental Hypercapnia in the Marine Teleost Fish Conger Conger
Authors: Toews D. P. , Holeton G. F. , Heisler N.
Published: April 2021

Specimens of Conger conger (L.) were exposed to environmental hypercapnia in a closed recirculating seawater system. Arterial plasma pH, Pco2 and bicarbonate concentration, as well as the net transfer of bicarbonate and ammonia between fish and ambient seawater, were monitored for 30 h of hypercapnia. The initial hypercapnia-induced reduction of arterial pH by about 0·4 pH units was restored to near control values within 10 h of hypercapnia by compensatory elevation of plasma bicarbonate concentration. The continuous rise in extracellular bicarbonate from about 5 to 22 mm during this time was the result of two different mechanisms. Initially, there was a net bicarbonate transfer from the intracellular space to the extracellular compartment until the net uptake of bicarbonate from the seawater started. The amount of bicarbonate originally transferred to the extracellular space was then returned to the intracellular compartment and finally the changes in both extracellular and intracellular pH were compensated by bicarbonate taken up from the environmental seawater. Since the ammonia excretion was not increased during hypercapnia and the pattern of plasma electrolyte concentrations does not favour the H+/Na+ ion exchange mechanism, it is concluded that the additional bicarbonate is gained by active HCO3−/Cl− ion exchange against the electrochemical gradient between fish and seawater.
Role of Mosquito Saliva in Blood Vessel Location
Authors: Ribeiro J. M. C. , Rossignol P. A. , Spielman A.
Published: April 2021

In order to ascribe a blood feeding function to the saliva of mosquitoes, we determined whether this secretion may limit the initial probing phase of biting behaviour. The probing of hosts was indeed prolonged when the salivary ducts were severed, but this prolongation was absent when mosquitoes were fed on an artificial meal contained beneath a membrane. In vitro, turbidometric assays demonstrated that saliva inhibits the ADP-and collagen-mediated aggregation of platelets. ATP and ADP were hydrolysed by saliva, and this apyrase activity explains, in part, the observed effect upon platelets. We conclude that the saliva of mosquitoes functions by facilitating location of blood vessels.
Axon Surface Infolding and Axon Size Can be Quantitatively Related in Gastropod Molluscs
Authors: Longley Roger D.
Published: April 2021

A quantitative estimate of infolding and of its effect on electrical characteristics in axons of different sizes is given by expressions based on the allometric equation, y = axβ. These expressions can be used to describe the effect of stretching the axon and the size dependence of the axo-somatic conductance ratio.

The parameters in the allometric equation are determined for a range of axon sizes in three species of opisthobranchs from original and from published data. Analysis of variance for these data suggests that interaxonal variability of infolding is less for axons of an identifiable neurone from different specimens of the same species than for axons of different neurones from the same specimen. With the exception of the Aplysia R2 axon where the infolding size dependence may be less, the ratio of axon volume to surface in these neurones is given approximately by the equivalent axon diameter to the one-half power. For this relation of infolding to size (and if it is assumed that infolding in the soma varies with size in the same way as in the axon), the axo-somatic conductance ratio is inversely proportional to soma diameter to the three-fourths power.

These results suggest that conduction velocity increase with size is small, and because of the penalty in the concomitant increase in axon surface membrane with size, selection for larger axons probably does not occur to satisfy a requirement of decreased response time.
Effects of Varied Culturing and Experimental Temperature on Electrical Membrane Properties in Paramecium
Authors: Martinac Boris , Machemer Hans
Published: April 2021

Effects of temperature on the electrical properties of the Paramecium membrane were investigated under constant current and voltage-clamp stimulation. With cells cultured at 18 °C, the resting potential was largely stable with experimental temperatures varied over the range of 10–25 °C, whereas action potential amplitude and membrane input resistance were inversely related to temperature increases. During voltage clamp, the early calcium current was increased, the time-to-peak decreased, and the early conductance increased with temperature. Similar modifications of the culturing temperature did not affect the resting potential, input resistance and stimulus-response relationship of the action potential, but the early conductance was reduced with increase in temperature. Possible effects of long- and short-term temperature changes upon intraciliary calcium concentration are discussed.
Influence of Hydration of The Environment On the Pattern of Nitrogen Excretion by Embryonic Snapping Turtles (Chelydra Serpentina)
Authors: Packard Gary C. , Packard Mary J. , Boardman Thomas J.
Published: April 2021

Flexible-shelled eggs of common snapping turtles were incubated on wet and dry substrates. More than 70 % of the waste nitrogen accumulating in eggs on both substrates was in the form of urea, and less than 25 % was in the form of ammonia. Low levels of soluble urate were detected in eggs late in incubation, but insoluble urate was never present. Accumulation of ammonia and soluble urate was unaffected by the hydration of the environment, but more urea accumulated late in incubation in eggs on the wet substrate than in those on the dry substrate. Thus, embryos are ureotelic throughout development, and the pattern of accumulation of the primary nitrogenous waste is influenced by hydration of the environment.
Movements and Active Moments of Bull Sperm Flagella as a Function of Temperature and Viscosity
Authors: Rikmenspoel Robert
Published: April 2021

Detailed measurements were made of the movements and waveforms of bull sperm flagella over a temperature range of 5 to 37 °C and over a range of external viscosities of 1–3600 × 10−3Pas−1*. The data obtained were used for an evaluation of the internal active moments in the flagella, using exact, large amplitude, algebra. The results of the calculations show that the axoneme in bull sperm flagella can produce the forces necessary to power the flagellar motion over the entire range of conditions. The calculations further suggest that no other structure in the bull sperm flagella has a forceproducing function.
Aerial Versus Aquatic Oxygen Consumption in Larvae of the Clawed Frog, Xenopus Laevis
Authors: Feder Martin E. , Wassersug Richard J.
Published: April 2021

Tadpoles of Xenopus laevis Daudin can extract oxygen from both air and water. When these larvae have access to air, aerial oxygen uptake averages 16·6 % of total oxygen consumption in normoxic water, and increases to 100% of net oxygen consumption in hypoxic water. Neither anaerobiosis nor increased buccopharyngeal ventilation occur in response to hypoxia. If tadpoles are prevented from surfacing to breathe air, they can maintain normal oxygen consumption through aquatic respiration alone in normoxic water, but not in hypoxic water. Unlike air-breathing larvae, exclusively water-breathing larvae respond to aquatic hypoxia by increasing their buccal pumping rate and by accumulating lactate. Even though Xenopus larvae can survive without air for many days, aerial respiration is necessary for other functions: tolerance of hypoxia, normal feeding, locomotion and buoyancy regulation.
Active Potassium Ion Transport Across the Caterpillar Midgut: I. Tissue Electrical Properties and Potassium Ion Transport Inhibition
Authors: Thomas M. V. , May T. E.
Published: April 2021

Active potassium ion transport by isolated midguts of Spodoptera littoralis andManduca sexta caterpillars has been studied by electrical means. In contrast to previous studies, the electrical properties of the midguts remained essentially constant for several hours; this improvement probably results from use of an experimental saline that more closely resembles caterpillar haemolymph. The active transport could be abolished by anoxia and by a number of chemical agents, of which trimethyl tin chloride (effective at 10−9M) was the most potent. Some of these substances, including trimethyl tin chloride, may have been acting directly on the potassium ion transport system. The results of varying the ionic composition of the saline suggest that potassium is the only cation that can be transported at a significant rate. However, the rate of potassium ion transport is increased by the simultaneous presence of other inorganic cations.

Experiments to determine the ‘reversal potential’ for the active transport pathway, by varying the potassium ion concentration, suggested that this parameter was not a constant, and thus the active transport system could not be modelled by a simple equivalent electrical circuit, although the midgut epithelium is not unique in this respect. Therefore, the tissue electrical properties could not readily be correlated with the energetics of the potassium transport process, but the results are nevertheless consistent with a potassium ion: ATP ratio of greater than one, if ATP is indeed the primary energy source.
Active Potassium Ion Transport Across the Caterpillar Midgut: II. Intracellular Microelectrode Studies
Authors: Thomas M. V. , May T. E.
Published: April 2021

Intracellular microelectrodes were used to record from individual cells in midguts isolated from Spodoptera littoralis caterpillars. Recorded potentials, referenced to the basal (haemolymph) surface, showed a bimodal distribution, with maxima in the ranges 0 to –10 and –30 to –40 mV. In experiments where the fluorescent dye Lucifer Yellow CH was iono-phoresed from the recording microelectrode, fluorescence was associated with single cells only for membrane potentials more negative than –25 mV. Examination of tissue sections showed these cells to be of both columnar and goblet types, in an approximate 2:1 ratio. This conclusion conflicts with that of a previous study on other caterpillar species, in which it was concluded that the goblet cells had basal membrane potentials of only a few mV. Attempts to discriminate between the two cell types by resistance measurements were unsuccessful. The resistance values obtained were substantially higher than those in the previous study, although they are consistent with those predicted from the overall tissue resistance. The major electrical effect of potassium ion transport inhibition by 1 m-KCN was on the apical membrane, supporting the view that the potassium pump is located there. The major initial effect of potassium ion removal was on the basal membrane, which is as expected if this membrane is permeable primarily to potassium. Our inability to discriminate between goblet and columnar cells by any electrical criterion suggests that both cell types may be able to transport potassium.
The Specific Power Output Of Aerobic Muscle, Related To The Power Density Of Mitochondria
Authors: Pennycuick C. J. , Rezende Marcio A.
Published: April 2021

A simple theory is proposed to account for the quantity of mitochondria present in aerobic muscles. Attention is restricted to muscles adapted to operate aerobically at a well-defined ‘operating frequency’. For this special case, it is shown that the volume ratio of mitochondria to myofibrils should depend on the power density of mitochondria, and the operating frequency, but not on the mechanical properties of the myofibrils. If the underlying assumptions are valid, this would mean that the specific power output of such muscles could be determined by examination of electron micrographs.

We provisionally estimate that the inverse power density of mitochondria, in flight muscles running at a high temperature, is in the range 1·010−6 to 1·310−6 m3 W–1, that is, that a little over 1 ml of mitochondria is required to sustain 1 W of mechanical power output. On this basis, a muscle with equal volumes of mitochondria and myofibrils should be able to deliver a specific power of about 430 W kg–1, at an operating frequency around 40 Hz for non-fibrillar, or 230 Hz for fibrillar muscle. The limiting specific power should be twice this level in either case, i.e. about 860Wkg–1.

It is predicted that a survey of flight muscles should yield a straight-line relationship between wing-beat frequency and the volume ratio of mitochondria to myofibrils, in a set of muscles of the same general type. It is not known whether lack of exercise, either on a long-term or short-term basis is likely to affect this. As a preliminary to such a survey, we have examined the pectoralis muscles of domesticated quail, and a wild house sparrow. Both showed a high level of variability in the mitochondria: myofibril ratio, but this may be due, at least in part, to sampling artifacts caused by the shape of mitochondrial arrays. The quail showed distinct populations of aerobic and non-aerobic fibres, apparently identical to those described in wild birds with similar flight requirements by George & Berger (1966), but the quantity of mitochondria in the aerobic fibres was less than half that expected, by comparison with other species.
Jumping Performance of Frogs (Rana Pipiens) as a Function of Muscle Temperature
Authors: Hirano Michio , Rome Lawrence C.
Published: April 2021

This study was performed to determine whether or not the power generated by frog muscles during maximal jumps increases two- to three-fold with a 10 °C increase in temperature as it does in isolated preparations. We found that peak power increased 2·7-fold between 14 and 25 °C, and then remained constant to 30 °C. During jumps at 14 and 25 °C, the extensor muscles of the legs appeared to generate the same power as the maximum power output found in isolated frog muscle preparations, thus suggesting that the total cross section of the extensors is active during maximal jumps. We also found that jump distance was linearly related to peak power generation.
Foetal and Adult Blood Oxygen Affinities of the Viviparous Seaperch, Embiotoca Lateralis
Authors: Ingermann Rolf L. , Terwilliger Robert C. , Roberts Michael S.
Published: April 2021

The high oxygen affinity of foetal versus adult blood is an almost universal characteristic of viviparous vertebrates; a notable exception is the cat (Novy & Parer, 1969). There is also likely to be a difference in the oxygen affinities of foetal and adult blood in the teleostean fish, the seaperch Embiotoca lateralis Agassiz. Our studies of E. lateralis foetal and adult haemoglobins and erythrocytes have shown several mechanisms which are likely to facilitate oxygen transfer to the foetal fish by increasing foetal blood oxygen affinity with respect to that of adult blood. Proposed mechanisms include structurally distinct foetal and adult haemoglobins with foetal haemoglobin having the higher oxygen affinity, lower foetal erythrocyte nucleoside triphosphate (NTP, primarily ATP) concentrations, and possibly, lower mean corpuscular haemoglobin concentrations (MCHC) in foetal cells (Ingermann & Terwilliger, 1981a, b, 1982a). It is necessary, however, to see if the oxygen affinity of foetal whole blood is greater than that of adult blood as predicted from purified haemoglobin oxygen binding and erythrocyte characteristics. Consequently, we have measured the oxygen affinities of foetal and adult whole bloods under comparable conditions.
Use of A Ventilated Capsule and Tritiated Water to Measure Evaporative Water Losses in A Tenebrionid Beetle
Authors: Nicolson S. W. , Louw G. N. , Edney E. B.
Published: April 2021

Evaporative water losses (EWL) in arthropods have traditionally been measured by gravimetric methods (Loveridge, 1980), although electronic sensing of water has recently been employed (Hadley, Stuart & Quinlan, 1982; Hadley & Quinlan, 1982). Difficulties are encountered in separating the cuticular and respiratory components of total transpiration. Cuticular water loss has frequently been measured in freshly killed specimens with blocked spiracles, and the results subtracted from the total EWL of living animals to obtain values for respiratory transpiration. Unfortunately, however, cuticular transpiration is higher in dead than in living arthropods (e.g. Hadley, 1970) and is further augmented by the appreciable damage to the cuticular waterproofing caused by blocking the spiracles (Beament, 1959). An additional problem arises when surface areas are estimated from standard equations, in order to express cuticular EWL in units independent of body weight. Loveridge (1980) has suggested that such estimates of surface area may be as much as an order of magnitude too low. We describe here an alternative technique using tritiated water (THO) and ventilated capsules to determine transpiration rates across small, known areas of cuticle in living insects. Tenebrionid beetles were selected as experimental animals and, because of the anatomy of their respiratory system, our method has also proved suitable for direct measurement of water losses from the subelytral cavity.
In Vitro Studies on the Role of the Brain and Prothoracic Glands in the Pupal Diapause of Manduca Sexta
Authors: Bowen M. F. , Bollenbacher W. E. , Gilbert L. I.
Published: April 2021

Pupal diapause in the tobacco hornworm, Manduca sexta (Johannson), is characterized by the absence of an increased ecdysteroid titre in the haemolymph during the first week of pupal life as measured by radioimmunoassay. This virtual absence of the steroid moulting hormone is thought to be responsible for the diapause state and it is apparently a consequence of the failure of the diapausing pupal prothoracic glands (PG) to synthesize ecdysone at an increased rate. In Manduca, this apparent failure of PG activation during diapause may be in response to two endocrinological circumstances: the curtailment of PTTH release as opposed to its synthesis and transport, and the development of refractoriness of the gland to stimulation by PTTH. The former was examined by measuring PTTH activity present in brains and brain-retrocerebral complexes of diapausing and non-diapausing pupae and the latter by assessing PG biosynthetic activity in vitro in the presence and absence of PTTH.
Hypoxic Acclimation in the Lamprey, Lampetra Fluviatilis: Organismic and Erythrocytic Responses
Authors: Nikinmaa Mikko , Weber Roy E.
Published: April 2021

Acute exposure of Lampetra fluviatilis to hypoxia ( = 40–50 mmHg) resulted in a large increase in ventilation frequency and a significant increase in O2 consumption (from 40 to 60 mg kg−1h−1 at 8 °C). After 1 week’s hypoxia, the O2 consumption decreased (from 60 to 50 mg kg−1 h−1), indicating the existence of slow, acclimatory changes that remove some of the strain from the ventilatory response. The hypoxic animals had a higher blood O2 affinity than the normoxic controls. This acclimatory response is not the result of a decreased allosteric interaction between the haemoglobin and erythrocytic organic phosphates, as in teleost fish, but is attributable partly to dilution of haemoglobin within the red cells and partly to an increase in the intracellular pH. The intraerythrocytic pH of hypoxic animals, measured with a freeze-thaw method, was higher than the plasma pH, suggesting that protons are not passively distributed.
Localization of tones and noise in the horizontal plane by unrestrained house mice (Mus musculus)
Authors: Ehret Günter , Dreyer Angelika
Published: April 2021

House mice (Mus musculus, outbred strain NMRI) were trained to locate loudspeakers at the margin of a wire-mesh covered circular platform. Sound signals were tone bursts of 1, 15, 50 and 80 kHz and noise bursts (bandwidth 15–80 kHz). Localization acuity as represented by orientation angles (α) toward the speaker was determined at 5 radial distances from the centre of the platform. If the animals could localize under closed-loop conditions (with repetitive stimulation), the distributions of (α) showed a significant peak at the speaker position (0°) and mean orientation angles for the different stimuli all varied around 0°. Distributions of (α) from open-loop tests were not peaked, i.e. mice did not localize the sound source. We calculated the median angle (β) of the distributions of orientated runs and used (β) as a measure for the accuracy of localization. Smallest values of α were 12° for 1 kHz, 15 ° for 15 kHz, 9·5 ° for 50 kHz, 8·5 ° for 80 kHz tone bursts and 7 ° for the noise bursts. The results are discussed in relation to possible localization mechanisms in mice.
Contractility and 45Ca fluxes in heart muscle of flounder at a lowered extracellular NaCl concentration
Authors: Gesser H. , Mangor-Jensen A.
Published: April 2021

The twitch force of isolated electrically paced ventricular strips of flounder, Platichthys flesus L., increased after lowering the extracellular sodium chloride concentration by 50 mmol l−1. This response was markedly reduced by replacing the sodium chloride with either Tris-HCl or sucrose, so that osmolarity was unchanged.

The 45Ca efflux decreased and the 45Ca influx increased when the extracellular sodium concentration was lowered. In contrast, changing only the osmolarity had no observable effect on these fluxes.

An increased resting tension appeared in strips exposed to a Na+-, Ca2+-free solution. This was transient at an unchanged osmolarity but became permanent at an osmolarity lowered by 100 mosmol l−1.

These results suggest that both a lowered Na0 and a lowered osmolarity have a positive inotropic effect, due respectively to an increased cellular uptake of Ca2+ and a redistribution of cellular Ca2+.
Antarctic Fish Blood: Respiratory Properties and the Effects Of Thermal Acclimation
Authors: Tetens Vilhelm , Wells Rufus M. G. , DeVries Arthur L.
Published: April 2021

The effects of thermal acclimation on whole blood oxygen affinity were examined in the antarctic fish Pagothenia borchgrevinki. 4·5 °C-acclimated fish had a P50 value of 26·7 mmHg at pH 8·4, compared to 20·7 mmHg for −1·5 °C-acclimated fish. The apparent heat of oxygenation, ΔH = −26·7 kJ mol−1, is comparable to values for temperate species. Warm-acclimation was followed by an increased ATP:Hb4 molar ratio, resulting in an augmentation of the thermal effect on oxy-haemoglobin affinity. This may be considered adaptive in a constantly well oxygenated environment, where oxygen loading at the gills is secured. Unloading to the tissues is thereby enhanced, supporting an elevated rate of aerobic metabolism at higher temperatures. In vivo blood pH was high, between 8·10 and 8·25 at − 1·5 °C. Astrup titration revealed arterial CO2 tensions of less than 0·8 mmHg, indicating relative hyperventilation and low oxygen extraction efficiency in antarctic fish. Blood oxygen affinities of four antarctic nototheniid species were low (P50 between 11·9 and 20·7 mmHg at pH 8·1 and -1·5 °C) in comparison with the temperate speciesNotothenia angustata (P50 = 10·8 mmHg). The zoarcid Rhigophila dearbomi had a high blood oxygen affinity (P50 = 4·3 mmHg). Blood oxygen-binding properties are discussed in relation to the polar environment, mode of life, and the concept of cold adaptation.
Neural Involvement in the Control of Salivary Gland Degeneration in the Ixodid Tick Amblyomma Hebraeum
Authors: Harris Robert A. , Kaufman William R.
Published: April 2021

We have developed a simple, quantitative assay to monitor salivary gland function in ixodid ticks. Salivary glands of engorged (l·0–3·0 g), or partially engorged (0·40–1·0 g), Amblyomma hebraeum Koch lose virtually all secretory function within 4 days after engorgement. Salivary glands from partially-fed ticks (0·20–0·30 g) lose 75 % of their secretory ability by 4 days post-removal, but retain this level of function for at least another 11 days. Partially-fed ticks (0·20–0·30 g) removed from the host for 4 days and then allowed to re-attach and resume feeding for a further 2 days, recover much of their lost function. Cutting the opisthosomal nerves of partially-fed ticks (0·40–1·0 g) inhibits salivary gland degeneration. Excising the seminal receptacle from partially-fed ticks (0·40–1·0 g) inhibits salivary gland degeneration. Replacement of the seminal receptacle permits salivary gland degeneration to proceed normally. The factor from the seminal receptacle appears to be distinct from tick salivary gland degeneration factor (TSGDF; Harris & Kaufman, 1981). Injecting a crude extract of male genital tracts into large, partially-fed ticks (0·40–1·0 g), which had had their seminal receptacles removed, caused virtually complete salivary gland degeneration. Such ticks, when injected with an extract of male salivary glands, showed no such degeneration. This suggests that the factor associated with mating originates in the male and is transferred to the female during copulation.
Serotonergic innervation and modulation of the stomatogastric ganglion of three decapod crustaceans (Panulirus interruptus, Homarus americanus and Cancer irroratus)
Authors: Beltz Barbara , Eisen Judith S. , Flamm Robert , Harris-Warrick Ronald M. , Hooper Scott L. , Marder Eve
Published: April 2021

The serotonergic innervation of the stomatogastric ganglion (STG) of three decapod crustacean species, Panulirus interruptus, Homarus americanus and Cancer irroratus, was studied. Immunohistochemical techniques were used to study the distribution of serotonin-like staining in regions of the stomatogastric system in the three species. In C. irroratus and H. americanus, but not in P. interruptus, serotonin-like staining was found in fibres in the stomatogastric nerve and in neuropil regions of the STG. High performance liquid chromatography confirmed the presence of serotonin in STG of C. irroratus and H, americanus, but serotonin was not found in STG of P. interruptus. Electrophysiological experiments showed that the pyloric motor output of the STG of all three species was influenced by bath applications of serotonin. The STG of P. interruptus responded to serotonin concentrations as low as 10−9M; however the STG of the other two species did not respond until serotonin concentrations in excess of 10−6 M were applied. We conclude that serotonin may play a hormonal role in the control of the STG of P. interruptus, but is likely to be a neurotransmitter released by inputs to the STG of H. americanus and C. irroratus.
Unusual Phase Relationships Between The Forewings And Hindwings In Flying Dragonflies
Authors: Alexander David E.
Published: April 2021

Flying insects can generally be divided into two groups: ‘primitive’ orders with forewings and hindwings that move independently (for example, Odonata, Orthoptera, Isoptera) and more ‘advanced’ orders with wings that are functionally one pair, with the fore- and hindwings in contact so as to function as one wing (for example, Hymenoptera, Lepidoptera, Homoptera), or with only one pair of wings that functions primarily as a lifting surface (for example, Diptera, Strepsiptera).
Dietary maintenance of bioluminescence in a deep-sea mysid
Authors: Frank Tamara M. , Widder Edith A. , Latz Michael I. , Case James F.
Published: April 2021

Dietary acquisition of the specific constituents of bioluminescent systems, frequently suggested for various midwater organisms (Haneda, Johnson & Shimomura, 1966; Shimomura, Inoue, Johnson & Haneda, 1980; McCapra & Hart, 1980), has been demonstrated experimentally only in the batrachoidid fish, Porichthys notatus. The luciferins and luciferases of Porichthys and the ostracod Vargula (= Cypridina) hilgendorfii cross-react, suggesting structural similarity (Cormier, Crane & Nakano, 1967; Tsuji, Haneda, Lynch & Sugiyama, 1971). Normally, non-luminescent Porichthys from Puget Sound luminesce after injection of V. hilgendorfii luciferin or feeding with dried V. hilgendorfii (Tsuji, Barnes & Case, 1972; Barnes, Case & Tsuji, 1973) or V. tsujii (Warner & Case, 1980). Specific dietary maintenance of bioluminescence has also been suggested for bioluminescent crustaceans. Shimomura et al. (1980) found large amounts of luciferin in the digestive tracts of various shrimps, and suggested that their luminescence had dietary origins.
The Contribution of the Alkaline Pericardial Fluid of Freshwater Turtles to Acid Buffering During Prolonged Anoxia
Authors: Jackson Donald C. , Heisler Norbert
Published: April 2021

The role of buffering of the high pericardial fluid [HCO3−] of the turtle, Chrysemy spicta bellii Gray, was evaluated during prolonged anoxia at 3 and 10°C. At 3°C, pericardial fluid samples were collected from groups of animals after 0, 1, 2, 4 and 8 weeks of anoxia, and the ionic composition of these samples was compared to plasma values from the same animals. At 10 °C, pericardial and plasma samples were taken from normoxic turtles and from turtles after 11 days of anoxia. The samples were analysed for total CO2, [Cl−] and [lactate-]. At 3°C, the fall in pericardial [HCO3−] and the rise in [lactate−] lagged behind the same changes in the plasma, until after about 8 weeks of anoxia the composition of pericardial fluid became identical with that of plasma. At 10 °C, pericardial [HCO3−] fell significantly after 11 days of anoxia but was still above plasma [HCO3−], while [lactate-] was essentially the same in both fluids. We conclude that the pericardial fluid does participate in the buffering of lactic acid during prolonged anoxia. However, its involvement is delayed, possibly until the energy supply for the active carrier-mediated transfer processes responsible for the high [HCO3−] gradient breaks down as a consequence of the prolonged anoxia. Analysis of the overall buffering in the body reveals that the contribution of the pericardial fluid is minor.
The Influence of Starvation on the Thermal Death-Point on Insects
Authors: Mellanby Kenneth
Published: April 2021

Previous work (Mellanby, 1932) has shown that insects may be killed at temperatures above the normal by various factors. There is no definite “thermal death-point” above which they are killed instantly, and below which they survive in a normal manner. Various factors contribute to the death of insects, and in different circumstances different factors are limiting. If the temperature is above 40° C. the heat is sufficient to kill many species. The actual lethal temperature depends on the length of the exposure, and may also be influenced by atmospheric humidity. Below 40° C., in moist air, the heat is usually the limiting factor, but in dry air insects which cannot conserve the water in their bodies die from desiccation.

Further experiments have shown that starvation is a factor which may influence the thermal death-point. Experiments made with the human body-louse, Pediculus humanus corporis de G., and with the mosquito, Culex fatigans, illustrate this point, and are here described.
Diffraction Patterns Produced by Bacteria
Authors: Ponder Eric
Published: April 2021

By treating the diffraction patterns produced by cultures of bacilli as the result of diffraction through a grating, Pijper has been led to the conclusion that the bacilli are oriented at right angles to the surface of the culture medium. It is shown in this paper that his results are better accounted for by supposing the organisms to be lying at random, under which circumstances only those patterns resulting from the diffraction of light by their breadths are perceptible to the eye.
The Liberation and Utilisation of Oxygen By the Population of Rock-Pools
Authors: Stephenson T. A. , Zoond A. , Eyre Joyce
Published: April 2021

A. P. Orr (1933), in the course of a study of the physical and chemical conditions prevailing in the sea near coral reefs, and in shallow pools on their surface, found that the oxygen content of the water in pools containing coral may rise to a very high figure (sometimes as high as a supersaturation of 278 per cent.) by the end of the period of low water during the daytime, falling to a low figure (e.g. 18 per cent, saturation) by the end of low water at night. Respiration by plants and animals uses up oxygen in both light and darkness; photosynthesis produces an excess of oxygen during daylight. The photosynthesis is due not only to free-living algae, but also (and in some places predominantly) to the symbiotic algae known as zooxanthellae which abound in the tissues of nearly all reef-corals. The effect can be detected in open water over coral, but is naturally much less marked there than in pools. C. M. Yonge, M. J. Yonge and A. G. Nicholls (1932) and S. M. Marshall (1932) studied the oxygen production of corals and their larvae experimentally. Oxygen determinations on coral reefs, and experiments on corals, have also been made by other authors—for references see Yonge, Yonge and Nicholls (1932) and Verwey (1931).
Regression of Anterior Pituitary Reactions II and III In the Mouse Ovary
Authors: Kennedy Walter P.
Published: April 2021

A number of tests were carried out to find the duration of the changes induced in the mouse ovary by prolan, and whether they were completely evanescent or productive of more or less permanent alterations. The question is of some interest in view of Mandelstamm and Tschaikowsky’s results (1931) in the production of temporary sterility in mice with prolan, and their experiment was repeated in a modified form with a few animals. Katzman has also reported that the B hormone from pregnancy urine produces profound ovarian luteinisation and complete inhibition of oestrus in rats, but that the impairment of the reproductive mechanism is not permanent.
Retardation of Growth in Axolotls Resulting From Parathyroid Extract Administration
Authors: Thompson J. H. , Huxley Julian S.
Published: April 2021

Axolotls have been used in a series of experiments designed to test the growth-retarding properties of the parathyroid glands of mammals, prepared so as to include the anti-growth hormone. Such retardation of growth has been obtained, and is proportional to dosage. This extends the growth-retarding effect of this hormone to the Anamnia, and to forms which presumably have no parathyroid themselves.

A lightening of colour in normally dark pigmented individuals was noted after a considerable period (about eight weeks) of treatment.
Pregnancy During the Anoestrous Season in the Ferret
Authors: Hammond J. , Walton A.
Published: April 2021

It is generally believed that pregnancy in most species requires critical amounts of ovarian secretions for its maintenance. Since these secretions, as judged by the appearance of the uterus and accessory organs, are considerably diminished during the anoestrum (in those species which have a limited breeding season) we have investigated the behaviour of animals which become pregnant at the end of the breeding season so that pregnancy extends into the time normally occupied by anoestrum.
The Water Relations of Snails and Slugs
Authors: Howes N. H. , Wells G. P.
Published: April 2021

The weight of active specimens of Helix pomatia L. undergoes continual fluctuation, the changes from day to day being often of very great magnitude and presenting the appearance of an irregular rhythm. The animals tend to aestivate at the times when their weight is low. The weight fluctuations are not responses to varying environmental conditions. The weight fluctuations are seen in animals given water but no food, and are not seen in those given food but no water. They are therefore due primarily to variations in the water content of the animals. The amplitude of the fluctuations is greater in fed than in fasting animals. Similar fluctuations, but of somewhat smaller amplitude, occur in snails kept in air saturated with water vapour.
On the Chemical Changes Associated with Metamorphosis in A Beetle (Tenebrio Molitor L.)
Authors: Evans A. C.
Published: April 2021

The changes in carbohydrate, fatty acids, unsaponifiable matter and nitrogen distribution are described in detail during the metamorphosis from larva to adult in the common mealworm, Tenebrio molitor L., and compared with those occurring in Lucilia sericata M.
The Effect of Unilateral Castration on the Remaining Testis of the Mouse
Authors: Rowlands I. W.
Published: April 2021

Unilateral castration was performed on a group of ninety-two adult male mice, and on another group of twenty immature males at the age of 14 days. No hypertrophy nor any microscopic changes could be detected in the remaining testes in either the adult or the immature groups.
The Electrical Properties of Isolated Frog’s Skin
Authors: Pumphrey R. J.
Published: April 2021

In two previous papers in this Journal (Francis and Pumphrey, 1933 ; Francis, 1934) the relation between the potential across pieces of isolated frog’s skin and various environmental factors has been described and discussed. In the work there described the potential was measured by means which were virtually electrostatic and no appreciable work was done by the skin. In this paper is described a method by which the potential can be measured during and after the performance of electrical work on or by the skin. Certain features are common to all the electrical phenomena manifested by cells and tissues and it seems likely that in all cases the basic mechanism is the same. It is probable therefore that the results here described will eventually be of service in the interpretation of the electrical behaviour of nerve and other excitable tissues, where on account of the structure of the tissue such experiments are difficult or impossible of performance.
The Location of Circa-Tidal Pacemakers in the Estuarine Amphipod Corophium Volutator Using A Selective Chilling Technique
Authors: Harris Gerard J. , Morgan Elfed
Published: April 2021

The anatomical location of the control centre(s) for the endogenous tidal rhythm of swimming activity shown by Corophium volutator (Pallas) has been investigated using a selective chilling technique. Rephasing occurred on chilling the whole animal to −3 °C or on chilling either the supra- or sub-oesophageal ganglion alone, whereas cold pulses applied to the telson or mid-body regions were without effect. Ablating the eyes had no effect on the endogenous rhythm. The results are interpreted in terms of two autonomous control centres.
Stick Insect Locomotion on a Wheel: Patterns of Stopping and Starting
Authors: Dean Jeffrey , Wendler Gernot
Published: April 2021

The relationship between standing and steady walking was investigated for stick insects walking on a wheel. Normal hexapod coordination patterns ensure that each point in the gait cycle has static stability. Nevertheless, stick insects show preferred stopping sequences: the final protraction in ipsilateral metachronal sequences is most often by a front leg and least often by a rear leg (Fig. 1, Table 1). The associated preferred stance is one in which front, middle, and rear legs are spread apart (Fig. 2). This preferred stance does not conform precisely to those of steady walking, necessitating small adjustments to the walk in the final steps. First, the final leg protraction often occurs in the absence of strong retraction by the supporting legs. Second, the insect often takes advantage of the left/right asymmetry, letting rear and middle legs on the leading side retract beyond their normal endpoints while completing the metachronal sequence on the trailing side. Walking typically resumes with an initial retraction by all legs. Stances are close enough to leg configurations of steady walking that metachronal rhythms are often continuous across pauses, a feature which suggests that leg coordination is affected by peripheral parameters, such as leg position.
Studies on the Mode of Action of Octopamine, 5-Hydroxytryptamine And Proctolin on A Myogenic Rhythm in the Locust
Authors: Evans Peter D.
Published: April 2021

The modes of action of the modulatory compounds octopamine, 5-hydroxytryptamine (5-HT) and proctolin on the frequency of the myogenic rhythm of the extensor-tibiae muscle of the hindleg of the locust, Schisto-cerca americana gregaria, have been investigated. 5-HT and proctolin increase the frequency of the myogenic rhythm and the results of the present study suggest that they may mediate their effects by increasing the levels of cyclic AMP in the pacemaker of the myogenic bundle. In contrast, octopamine reduces the frequency of the myogenic rhythm and appears to mediate its effects by a mechanism that does not involve an elevation of cyclic AMP. A number of other possible mechanisms for the action of octopamine are discussed.