bluuebunny/crossref_metadata_2025 huggingface dataset:
The Hormonal Control of Diuresis in the Cabbage White Butterfly Pieris Brassicae
Authors: Nicolson Susan W.
Published: April 2021

The diuresis which follows the pupal-adult ecdysis of Pieris brassicae is hormonally controlled. Use of the isolated Malpighian tubules as a bioassay shows the presence of substantial diuretic activity in homogenates of the brain and corpus cardiacum-corpus allatum complex. The hormone is probably produced in the brain and released from a storage site in the corpora cardiaca. The tubules of the butterfly are maximally responsive to the diuretic hormone at the time of eclosion.
Primitive Nervous Systems: Electrophysiology of the Pharynx of the Polyclad Flatworm, Enchiridium Punctatum
Authors: Stone George , Koopowitz Harold
Published: April 2021

Electrical activity accompanying motor activity can be recorded from the excised pharynx of Enchiridium punctatum. Multiple stimuli elicit behaviour which consists of an initial aperture closure followed by extension and then peristalsis. If the stimulus parameters are increased the preparation bends from side to side instead of proceeding through the behavioural sequence. Bending appears to inhibit other movements differentially. The conduction involved with peristalsis is polarized and proceeds in a proximal direction. With stimulus intensities greater than those needed to produce the behavioural response an initial muscle potential (IMP) is evoked. The IMP is frequency sensitive. Maximum facilitation occurs within 100 ms and drops to 50 % of maximum within 250 ms. Conduction velocities of the IMP range from 0·05 m s−1 to 1·9 m s−1. Conduction velocities appear to increase with facilitation.
Evidence for Calcium Inactivation During Hormone Release in the Rat Neurohypophysis
Authors: Nordmann J. J.
Published: April 2021

A study has been made of the relationship between 45Ca uptake into and hormone release from isolated rat neurohypophyses incubated in vitro. Hormone secretion is triggered by high-K (56 mm) but long exposure to the stimulus does not generate a maintained release of hormone. When hormone release began to wane, addition of Ba or La increased hormone output which suggests that the decline in output did not result from depletion of the neurosecretory granules at the nerve terminals. 45Ca uptake is enhanced in the presence of high-K concentration, but the initial high rate declines during long exposure to the potassium stimulus with a time constant similar to that of the decline in hormone release. After a period of incubation in a K-rich, calcium-free medium, addition of calcium to the medium induced hormone release. The magnitude of this release was dependent on the time of exposure to excess potassium. After inactivation of secretion, mobilization of internal calcium by means of a calcium ionophore increased hormone release.
Heart Action of the Freshwater Bivalve Anodonta Anatina During Activity
Authors: Brand A. R.
Published: April 2021

Heart action of Anodonta anatina (L.) was investigated by recording the electrocardiogram (ECG), heart impedance, and ventricular and pericardial cavity pressure during different aspects of the normal behaviour. The contribution of mechanical and nervous mechanisms in controlling changes in heart action is discussed. Pressure recordings were generally more reliable than the other methods and it is suggested that pericardial pressure pulses indicate the stroke volume output of the ventricle. During spontaneous periods of prolonged shell closure there was an initial small increase in heart activity followed by a large reduction in both heart rate and systolic pressure, indicating that total heart output was considerably reduced. When the shell reopened, heart rate increased very rapidly with an initial overshoot of the normal level; systolic pressure increased more slowly with no overshoot. These major changes in heart activity appear to be associated with respiratory changes and are controlled largely by the nervous regulatory system, but some minor rhythmic variations in the amplitude of heart beat are probably caused by mechanical factors. Characteristic patterns of change in heart action were recorded during burrowing. These appear to result from haemodynamic changes associated with the muscular movements of the digging cycle. Control of the heart by the nervous regulatory system is apparently of much greater importance in relation to respiratory control than in relation to the haemodynamic functioning of the fluid-muscle system in locomotion.
Modulation of Hydra Attenuata Rhythmic Activity: Phase Response Curve
Authors: Taddei-Ferretti Cloe , Cordella Luigi
Published: April 2021

We investigated the effect of photic stimulation on the frequency of Hydra attenuata column contractions. We used positive or negative abrupt light transitions, single or repetitive light or darkness pulses, and alternation of light and darkness periods.

The main results are: (a) The frequency of the contraction pulse trains (CPTs) varies transiently in response to an abrupt variation of the light intensity. (b) CPTs in progress can be inhibited by different types of photic stimuli, (c) The response time to a single photic stimulus varies during the inter-CPT interval and depends also on the polarity of the stimulus, (d) The CPTs are entrainable with repetitive light stimulation of various frequencies, (e) Long-lasting variations of the frequency of CPTs occur after the end of a repetitive light stimulation.

We suggest that the mechanism responsible for the rhythm of column contractions is quite similar to that on which other biological rhythmic phenomena are based.
Quantitative studies of the reactions to horizontal angular accelerations in axolotls
Authors: Brändle Kurt
Published: April 2021

Artificially metamorphosed axolotls were exposed to both brief (impulse) and long-lasting horizontal angular accelerations on a turn-table. The animals responded with a head-turning reaction. The general course of the reaction to impulse acceleration was independent of stimulus intensity. The velocity of the head movement first increased to a maximum exponentially and then decreased in a negative exponential manner. Stimulus intensity had a linear relationship to the mean maximum velocity and mean total angle covered by head-turning. The average velocity-time curves at various stimulus intensities differed only by a velocity factor. During long-lasting constant accelerations the velocity of the head-turning increased to a maximum velocity in a sigmoid time-course and then decreased, first to a constant velocity, and then further. Mean values of the maximum velocity were correlated linearly with the stimulus intensity. It was concluded that the head-turning reflexes in axolotls do not agree with the accepted movements of the vertebrate cupula and therefore are not a simple ‘copy’ of the afferent input. It is also suggested that the reaction threshold differs from that for the labyrinthine input.
Quantitative studies of the reactions to horizontal angular accelerations in axolotls : II. head-turning reflexes in animals with a supernumerary pair of labyrinths
Authors: Brändle Kurt
Published: April 2021

In axolotls (Ambystoma mexicanum) the labyrinths and the associated parts of the medulla were doubled artificially. In these so-called tandem-heads the vestibular afferent fibres from both labyrinths on one side united within the medulla to form common bundles.

The head-turning reflexes following impulse acceleration and during long-lasting acceleration were measured quantitatively and compared with those for normal animals. The form and the time-course of the reactions were almost identical in both groups. Tandem-heads showed a linear relationship between stimulus intensity and reaction strength, parallel to that in normal animals but with a greater reaction for a given stimulus. Consequent to this shift in the relationship, there was a significant decrease in the reaction threshold. The removal of one horizontal semicircular canal in tandem-heads proved that both pairs of labyrinths were functionally connected with the brain. It was suggested that during ontogenesis there exists a kind of specificity in the connexion of vestibular fibres. From the parallel shift of the intensity functions it was concluded that the input from both pairs of labyrinths in tandem-heads is not simply accumulated but compared with a reference parameter, which is also double in tandem-heads.
The locust jump. II. Neural circuits of the motor programme
Authors: Heitler W. J. , Burrows M.
Published: April 2021

Neural circuits which co-ordinate the motorneurones of the metathoracic tibiae of the locust in jumping and kicking have been investigated. The fast extensor motorneurone is reflexly excited by the subgenual organ, by a network of cuticle strain receptors, and by Brunner’s organ. The subgenual organ and the cuticle strain receptors are excited by tension in the extensor muscle and mediate a positive feedback which could help to produce the burst of fast extensor spikes which precedes a jump or kick. Brunner’s organ is stimulated by pressure from the flexed tibia, and will be excited by the initial flexion and throughout the co-contraction phase of a kick. A central excitatory, connexion from the fast extensor to the slow extensor ensures that extensor muscle tension is as great as possible early in the co-contraction phase of a kick. A central excitatory connexion from the fast extensor to flexor motorneurones is confirmed. This ensures that flexor muscle tension is great enough to keep the tibia flexed when the extensor muscle tension starts to develop before a jump or kick. Reflex excitation of flexor motorneurones occurs in response to an extensor muscle twitch when the tibia is flexed. This helps to maintain the frequency of flexor spikes after habituation of the central fast extensor to flexor connexion. A receptor, the ‘lump receptor’, which is stimulated by flexor muscle tension only when the tibia is flexed, can inhibit the flexor motorneurones and may activate the trigger system which allows the extension of the tibia in a jump or kick. Receptors in the suspensory ligaments of the joint inhibit the fast extensor when the tibia extends.
Prothoracicotropic hormone in Manduca sexta: localization by a larval assay
Authors: Gibbs Daniel , Riddiford Lynn M.
Published: April 2021

A new method for the assay of insect prothoracicotropic hormone (PTTH) is described, using fourth instar larvae of Manduca sexta. Larvae neck-ligated at a critical time to prevent release of PTTH from the head fail to undergo the next larval moult. Such ligated larvae moult to fifth instar larvae or larval-pupal intermediates after injection of brain homogenates from Manduca larvae, pupae or pharate adults. The degree of response is proportional to the concentration of brain homogenate injected. The source of PTTH in the pupal brain is the dorsal region of the protocerebrum containing the lateral neurosecretory cells. Microhomogen-nates of single pieces of brain showed activity with this method. PTTH activity in partially purified extracts is water soluble, stable to boiling for 10 min, and is destroyed by Pronase or trypsin.
The effect of the spacing of background elements upon optomotor memory responses in the crab: the influence of adding or deleting features during darkness
Authors: Hirsh Richard , Wiersma C. A. G.
Published: April 2021

Study was made of the effect of separation between stripes in the visual field upon responses which indicate memory of those stripes. The amount of separation between white stripes had very little effect, whereas response strength and the amount of separation between black stripes were directly proportional. The presence of extra, non-displaced black stripes prior to or following displacement reduced the size of the memory responses. The effects of the amount of separation in the two cases were comparable. In both situations the separation affected only the responses to displacement of the stripe borders nearest to the extra stripe. The effect of extra stripes present prior to displacement was in turn affected by the duration of the dark period, whilst the effect of those present during the post-displacement period was not. This accounts for the larger effect of extra stripes present during the post-displacement period. By expanding stripe width during darkness it was possible to distinguish between the effects of distance between stripes and the amount of white space separating them. Reducing white space while distance remains constant causes reductions in response strength, whereas reducing the distance between a memory zone and the white space between it and the neighbouring stripe increased the size of the memory response.
The Effect of Salinity on Cadmium Uptake by the Tissues of the Shore Crab Carcinus Maenas
Authors: Wright D. A.
Published: April 2021

Cadmium accumulation by the haemolymph, gills and carapace of the shore crab Carcinus maenas (L.) was significantly higher in dilute sea water. This was reflected in the whole-body cadmium concentrations. There was no salinity effect with the hepatopancreas or muscle cadmium concentration.

Over a 68-day period, cadmium was steadily accumulated by the carapace, with the salinity effect becoming increasingly apparent. In 50 % sea water the gill cadmium concentration apparently reached a maximum level after about 2 weeks of uptake. This was eventually overtaken by the tissue cadmium concentration in the gills of 100 % s.w. animals. After about 48 days the salinity effect had disappeared and the gill cadmium concentration of both 50% and 100% s.w. animals (in 20 μ-mol Cd l− 1 = 2· 3 mg I− 1) remained at approximately 0·3 μ-mol Cd g− 1 ( = 33·7 mg kg− 1) wet weight of tissue. The hepatopancreas cadmium also levelled off at about this concentration although no salinity effect was apparent.

When animals loaded with cadmium for a 37-day period were returned to clean sea water, their whole body cadmium concentration fell by about 50 % after 11 days. Losses from carapace and gills were important components of this reduction in cadmium concentration.
Asymmetrical Permeability of the Integument of Tree Frogs (Hylidae)
Authors: Yorio T. , Bentley P. J.
Published: April 2021

The skin from four species of North American tree frogs (Hylidae) was found in vitro, to be remarkably permeable to water in the presence or absence of the neurohypophysial hormone vasotocin. This property was, however, only seen in preparations from the ventral integument; osmotic water movement across the dorsal skin was negligible. The ionic permeability, reflected by the electrical resistance, was also much greater in the ventral skin. Unidirectional fluxes of 22Na, 36C1, 14C-urea and tritiated water were measured in vitro in a single species, Agalychnis dacnicolor Cope. The ventral skin was 10−20 times more permeable to these molecules than the dorsal skin. The short-circuit current (usually reflecting active transmural Na transport) across the ventral skin was increased by aldosterone and vasotocin but these responses were absent on the dorsal side. The lipid content of the dorsal skin was four times greater than that on the ventral surface.
Ionic Basis of Axonal Excitability in An Extreme Euryhaline Osmoconformer, The Serpulid Worm Mercierella Enigmatica (Fauvel)
Authors: Carlson A. D. , Treherne J. E.
Published: April 2021

Despite the extreme fluctuations in blood concentration experienced by this marine osmoconformer, essentially ‘conventional’ ionic mechanisms are involved in conduction by the giant axons in isosmotic conditions. The resting axonal membrane approximates to an ideal potassium electrode, with a 58·8 mV slope for decade change in [K+]0 above 10 mm. The action potential overshoot shows a 55·8 mV decline with decade reduction in [Na+]0 and the action potentials are blocked by tetrodotoxin at around 10−7 M.

The rising phase and overshoot of the action potential remain constant at potassium concentrations up to the relatively high level of 30 mm found in the blood, indicating an unusual absence of sodium inactivation over a wide range of resting potentials. Relatively rapid, symmetrical movement of potassium ions between the bathing medium and the axon surface is deduced from the potential changes induced by alterations in [K+]0. Outward movement of sodium ions (t0·5 = 33·5s) occurs at a similar rate to that of potassium, but inward movement of Na+ is relatively slow and complex. It is concluded that the ability of axons to function in dilute media must involve specific adaptations to osmotic and ionic stress.
Osmotic Regulation in the Brackish-Water Rotifer Brachionus Plicatilis (Muller)
Authors: Epp R. W. , Winston P. W.
Published: April 2021

The body fluid osmolarity of individual rotifers was measured at 12 external concentrations ranging from 32 to 957 m-osmol/l. Brachionus plicatilis is essentially an osmoconformer, since a change in the concentration of the medium results in a corresponding change in the concentration of the body fluids. Most animals were, however, slightly hyperosmotic throughout the range tested.

The lowest body fluid osmolarity was 59 m-osmol/l at an external concentration of 32 m-osmol/l. It appears that B. plicatilis is unable to tolerate the low concentrations that are frequently associated with acid water environments and this is responsible for the restriction of this species to alkaline and brackish waters.
The Neuronal Basis of A Sensory Analyser, The Acridid Movement Detector System
Authors: Rowell C. H. Fraser , O’shea Michael , Williams J. L. D.
Published: April 2021

The lobula giant movement detector neurone (LGMD) and its post-synaptic cell, the descending contralateral movement detector neurone (DCMD), show a preference for small-rather than large-area stimuli within their 180° receptive field. Intracellular recordings from LGMD show that two different neural mechanisms are responsible. Large-field moving stripes cause little decrement in the labile afferent synapses to LGMD. The response to a small moving target is progressively inhibited by large-field moving stripes when these are closer than ca. 20° and moving stripes produce progressively more excitatory response when their area is limited to 40° or less. These observations indicate a phasic lateral inhibitory network between the afferent excitatory pathways to subfield A of LGMD. The responsible units have not been identified, but are probably in the proximal medulla or distal lobula. This network reduces input to LGMD during sustained large-field stimulation and, in addition, protects the decrement-prone small-field neurones from the potentially fatiguing effects of whole-field movements. Large-field stimuli also produce long-lasting compound IPSPs in LGMD, which limit or prevent spiking. Separate and different IPSPs are generated by ON and OFF stimuli. The neurones mediating OFF IPSPS have been identified anatomically and their function confirmed by selective lesion. Their input dendrites cover approximately 8° × 12°of the proximal face of the medulla. The axons form a dorsal uncrossed bundle (DUB) above the second chiasma, and terminate on the dorsal lobe of the lobula, apparently synapsing on dendritic subfield C of LGMD. The ON and OFF inhibitory inputs form ‘feed-forward’ inhibitory loops around the ON/OFF excitatory afferents. ‘Feed-forward’ inhibition is necessary in addition to lateral inhibition to prevent a large excitatory response to whole-field transients. Lateral inhibition is necessary in addition to feedforward inhibition to protect the small-field excitatory afferents from depression. This combination may be widespread in sensory systems and could provide a basis for saccadic suppression. The response of LGMD to a variety of visual stimuli is analysed and shown to be adequately explained as the resultant of small-field excitatory and lateral-and feed-forward inhibitory inputs.
Calcium Movements During Contraction in Molluscan Smooth Muscle, and the Loci of Calcium Binding and Release
Authors: Huddart H. , Hunt S. , Oates K.
Published: April 2021

Conventional 45Ca efflux studies of Buccinum and Neptunia pharangeal retractor and columella muscles revealed the presence of a fast and a slow calcium compartment. KCl-induced depolarization caused a stimulation of the 45Ca efflux from the slow compartment, suggesting that this compartment may be related to calcium diffusion from intracellular sources. Fine structural studies showed a lack of organized sarcoplasmic reticulum in both muscles, and that submembrane vesicles and mitochondria were prominent. Muscle sections examined by energy-dispersive X-ray microprobe analysis showed the presence of significant calcium accumulation in the submembrane vesicles and mitochondria. Isolated submembrane vesicles and mitochondria of columella muscle showed strong powers of ATP-promoted calcium binding, while pre-loaded preparations could be induced to release 45Ca under in vitro conditions. Synthetic detergent dispersal of columella muscle submembrane vesicles and mitochondria, followed by polyacrylamide gel electrophoresis revealed, in both fractions, a striking similarity of protein profile with those from skeletal muscle sarcoplasmic reticulum. Two dominant protein bands were present, at 110000-112000 daltons and at 51000-53000 daltons, in a position similar to the Ca2+/Mg2+ ATPase and calsequestrin or high affinity proteins of skeletal muscle. It is suggested that, in the absence of an organized sarcoplasmic reticulum, the submembrane vesicles and mitochondria may act as the major calcium pools for contraction in these molluscan smooth muscles.
Oxygen Consumption of the Terrestrial Mite Alaskozetes Antarcticus (Acari: Cryptostigmata)
Authors: Block William
Published: April 2021

Analysis of 148 measurements of individual respiration rate showed that although respiration was linearly related to live weight on a double log10 scale, there were significant differences between rates at 0°, + 5° and +10 ° C. Proto-and deutonymphal metabolic rates were higher than other stages, especially at +10 ° C. Q10 values ranged from 2·07 to 3·83 over 0° to +10 ° C. Equations relating individual respiratory rate to live weight and temperature for A. antarcticus, and metabolic rate to temperature for 10 species of Antarctic terrestrial invertebrates were developed. Comparison with temperate data indicated considerable cold adaptation in the Antarctic species with 3–5 times increased metabolism. It was calculated that 78– 82 % of the energy assimilated may be used in respiration by A. antarcticus.
Mechanical Diversity of Connective Tissue of the Body Wall of Sea Anemones
Authors: Koehl M. A. R.
Published: April 2021

Techniques for analysing polymer mechanics were used to describe quantitatively the time-dependent mechanical properties of the body-wall connective tissue (mesogloea) and to indicate macromolecular mechanisms responsible for the mechanical behaviour of two species of sea anemones, Me tridium senile and Anthopleura xanthogrammica.

The mesogloea of M. senile is more extensible and less resilient than that of A. xanthogrammica when stressed for periods comparable to the duration of flow forces the anemones encounter and the postural changes they perform. Polarized light microscopy and SEM reveal that the reinforcing collagen fibres in the mesogloea are aligned parallel with the major stress axes in the body wall. Mechanical tests and observations of composition and microstructure indicate that the mesogloea of A. xanthogrammica is less extensible than that of M. senile because molecular entanglements (due to more closely packed parallel collagen fibres and to a higher concentration of polymers in the interfibrillar matrix) retard the extension of A. xanthogrammica mesogloea.

This study illustrates how structural features on the macromolecular and microscopic levels of organization of an organism can equip that organism for the particular mechanical activities it performs and the environmental forces it encounters.
Oxygen Consumption During the Metamorphosis of the Parasitic Lamprey, Lampetra Fluviatilis (L.) and Its Non-Parasitic Derivative, Lampetra Planeri (Bloch)
Authors: Lewis S. V. , Potter I. C.
Published: April 2021

Standard oxygen consumption has been measured during the six stages of metamorphosis in both the anadromous parasitic lamprey, Lam-petra fluviatilis, and in its non-parasitic derivative, Lampetra planeri. At 10 °C, the standard rates in larval L. planeri and L. fluviatilis of metamorphosing size were 20·3 and 29·3 μl g−1 h−1 respectively. After a slow rise in oxygen consumption during the initial stages of metamorphosis, the rates reached 50·5 and 60·4 μl g−1 h−1 at stage of 6 of L. planeri and L. fluviatilis respectively. Following the completion of metamorphosis in L. planeri and the development of secondary sexual characters, the mean rate in males rose to 73·3 μ g−1 h−1, compared with a decline in females to 44·1 μ g−1 h−1. Although no circadian rhythm was detectable in the oxygen consumption of larvae, an elevation in the metabolic rate was present during darkness in L. fluviatilis at the end of metamorphosis. Standard oxygen consumption and ventilatory frequency were influenced greatly by temperature, e.g. values for stage 6 of L. fluviatilis rose from 24·3 μl g−1 h−1 and 33·0 beats min−1 at 5 °C to 103·8 μl g−1 h−1 and 98·2 beats min−1 at 15 °C. The results are discussed in the context of the radical changes taking place during metamorphosis and in terms of the differences between larvae and adult and between the life cycles of parasitic and non-parasitic lampreys.
The Oxygen Transport System in Trout (Salmo Gairdneri) During Sustained Exercise
Authors: Kiceniuk Joe W. , Jones David R.
Published: April 2021

The capabilities of the oxygen transport system of rainbow trout in supplying the increased oxygen demands in exercise, in a water tunnel at 9–10·5 °C, have been investigated by increasing the velocity of water flow, with a i h period between increments, up to the maximum swimming speed (critical velocity, Ucrit). At Ucrit, was elevated above the resting level by 7·5 times. The logarithm of was linearly related to the swimming speed expressed as a proportion of Ucrit. increased in almost direct proportion to the increase in . Heart rate rose slightly at half Ucrit and reached a maximum, 1·6 times the resting rate, as Ucrit was approached. Ventral and dorsal aortic mean blood pressures rose by 60% and 20% respectively at Ucrit while their pulse pressures doubled. Central venous pressure was virtually unchanged. fell slightly during exercise but was unaffected. On the other hand halved and fell from 3·17 (S.E. = 0·3) to 0·6 (S.E. = 0·7) mmol/1. Cardiac output increased by about 3 times resting values. The results are discussed and an attempt is made to estimate the maximum capabilities of the components of the oxygen transport system in sustained exercise.
Relationship of Intracellular Potassium to Asexual Reproduction in Hydra
Authors: Epp Leonard G. , Koblick Daniel C.
Published: April 2021

Removal of potassium from Hydra culture medium produces a decrease in intracellular potassium and a parallel decrease in asexual growth rate. Rubidium and caesium are ineffective as substitutes for potassium in the maintenance of growth rate. Increases in intracellular potassium parallel increases in growth rate up to a level somewhat below the normal steady-state level of intracellular potassium. The full potassium requirement for maximum effect on budding can be acquired from food or external medium. High levels of external potassium suppress budding but do not alter intracellular potassium levels.
The Control of the Diuresis Following A Blood Meal in Females of the Yellow Fever Mosquito Aëdes Aegypti (L.)
Authors: Stobbart R. H.
Published: April 2021

Control of post-feeding diuresis in females of the mosquito Aëdes aegypti has been studied by means of a weighing technique and simple surgical procedures. The primary controlling factor is (as in the larva) a nervous feedback mechanism and not an increased production of diuretic hormone. As the mosquito ingests blood, sensory information from the distending abdomen reaches the mid gut via the nerve cord, brain and stomatogastric system. This information probably inhibits retroperistaltic movements of the mid gut allowing fluid from the Malpighian tubules (which seems to be produced continually) to be moved back to the rectum for subsequent excretion, instead of being re-cycled to the haemolymph via the mid gut. Such a control does not preclude a role for the diuretic hormone, continual secretion of which may cause the continual production of fluid from the Malpighian tubules.
Tyrosinase In Crustacean Blood
Authors: Pinhey Kathleen Godwin
Published: April 2021

When the blood of certain Crustaceans clots at a wound, the clot ultimately becomes black. This same blackening sometimes becomes troublesome in solutions of haemocyanin (in its natural serum) which are kept for any length of time in the laboratory. This will be shown to be the result of the action of a tyrosinase system in the blood, producing a black pigment, to which the general name melanin can be applied. Heim, in 1892, noticed black granules in the blood of Crustacea; these granules were soluble in mineral acids, producing a brown colour. He suggested that they were formed through the action of a tryptic ferment on some protein substrate in the blood. Furth (1903) first showed that the enzyme concerned in the reaction was a tyrosinase.
Thyroxine and the Oxygen Consumption of the Spermatozoa of Echinus Miliaris
Authors: Carter G. S.
Published: April 2021

In 1917 Miss Woodward and Miss Hague (5) published an account of experiments in which a solution of iodine in sea-water was found to be effective in producing artificial parthenogenesis in the eggs of Arbacia. The results were remarkable in that the percentages of the eggs which developed were not noticeably increased by treatment with hypertonic sea-water after activation by the parthenogenetic agent. In this respect iodine differs from all the better known means of producing artificial parthenogenesis in the echinoderm egg, and resembles only fertilisation by the spermatozoon, and the activation of the frog’s egg by pricking its surface.
The Distribution of Biological Activity in the Anterior Pituitary of the Ox
Authors: Spaul E. A. , Howes N. H.
Published: April 2021

There is a graded distribution of metamorphic activity from the inside of the anterior pituitary to the periphery. This is similar to the distribution of the phosphate content of the iodine precipitate obtained with extracts of different regions of the gland. A new technique based upon iodine absorption and the reaction between the absorbed iodine and the leuco-base of malachite green is described. The distribution of the staining intensity with this technique corresponds to the oxyphil affinity and the biological activity. The oxyphil cells appear to be mainly concerned with the metamorphic activity.
The Production of Non-Disjunction By γ-Radiation From Radium
Authors: Mottram J. C.
Published: April 2021

The occurrence of non-disjunction like that of gynandromorphism, of intersexes, and of sex-linked mosaics, is closely related to mutations due to chromosome change. It is probable that agents which effect non-disjunction will also give rise to mutations. For instance, in the case of X-rays, Mavor (1924) has shown that these radiations produce non-disjunction and Muller (1927) that the occurrence of mutations is greatly increased in Drosophila by subjecting the flies to the same radiations.
A Histological Study of the Ox Pituitary Gland After Freezing and Exposure
Authors: Howes N. H.
Published: April 2021

A histological method is described for a study of post-mortem cytoplasmic changes ; the method depends upon observed variations in staining capacity. By the application of this method, a series of cytoplasmic changes were found in ox pituitary glands which had been exposed, after the death of the animal, for varying times to different temperatures. These changes correspond to alterations in the biological activity and chemical content previously investigated. These methods showed that freezing apparently causes no alteration in the distribution of biological activity. It is possible that the histological appearance can be used to determine the suitability of ox pituitary glands for the preparation of active extracts of the anterior lobe.
A Re-Investigation of Metabolic Gradients
Authors: Shearer C.
Published: April 2021

I Published (17) in 1924 certain observations on the rate of oxygen consumption of parts (head and tail portions) of chick embryos and of earthworms. The manometer method was employed. I concluded that these results apparently supported the previous work of Hyman (7), and Hyman and Galigher (8) on Annelids and Planarians, which were based on Winkler’s method of titration. The head portions of the embryos and earthworms, for equal quantities of living tissue, had always a relatively greater uptake of oxygen than the corresponding tail portions.
Studies on Growth Acceleration in Protozoa and Yeast
Authors: Darby Hugh H.
Published: April 2021

In 1923 Robertson revitalised the old theory that reproducing unicellular organisms discharge into the medium a substance which accelerates growth. This theory has of necessity the corollary that the larger the amount of culture medium, the greater the dilution of this substance, and therefore the less acceleration. Robertson maintained that some organisms would not reproduce at all if placed in too large an amount of culture medium. Thereby he confused two separate concepts—one, of a substance necessary for growth, the other, of a substance which accelerates growth. The history of the former concept will be taken up later in connection with the growth of yeast. For the present, discussion will be confined to the production of an auto-catalyst by protozoa.
Voltage Sensitive Ca-Channels and the Transient Inward Current in Paramecium Tetraurelia
Authors: Satow Youko , Kung Ching
Published: April 2021

Transient inward currents across the membrane of P. tetraurelia are recorded upon step depolarizations with a voltage clamp in solutions where Ca2+ is the only added inorganic cation. It is shown that the current is normally carried by Ca2+ through the Ca-channels which activate and inactivate in time.

The transient inward current is dependent on both the size of the depolarizing step and the holding level before the step. Maximum inward current (Imax) occurs when the membrane is first held at the resting level (– 30 mV), then stepped to o mV in a solution containing 0·91 mm-Ca2+. The Imax is smaller when the membrane is first held at depolarized level. This is due to the depolarization-sensitive inactivation of the Ca-channels. The is also smaller when the membrane is first held at a hyperpolarized level. This may be explained by the activation of hyperpolarization-sensitive K-channels known to exist in the Paramecium membrane.

I max increases with concentration of Ca2+ up to 0·9 mm. Further increase in the Ca2+ concentration does not affect /max-This apparent saturation at 0·9 mm-Ca2+ may reflect a rate-limiting step of Ca2+ permeation. The increase in Ca2+ concentration shifts the V−Ipeak curve in the direction of less sensitivity. This result is best explained as the effect of bound Ca2+ on the surface potential of the Paramecium membrane.

These results provide the first detailed description of the properties of the action current through the Ca-channel in Paramecium. They also define the conditions under which future voltage-clamp studies of wild-type and mutant membranes of P. tetraurelia should be performed, i.e. to maximize the resolution of the Ca-channel activity, the membrane should be held at or near the resting potential and there should be over 0·9 mm-Ca2+ in the test solutions. The behaviour of the Paramecium Ca-channel and small Imax in the presence of K+ are discussed.
Power Capabilities of the Avian Sound-producing System
Authors: Brackenbury J. H.
Published: April 2021

The vocal performance of different species of songbird was compared by measuring the maximum total sound power produced during normal song. This varied from 10 mW/Kg body weight in the linnet Acanthus cannabina and the whitethroat Sylvia communis to 870 mW/Kg in the song-thrush Turdus philomelos. In comparison, the performance of the chicken Gallus domesticus during crowing was approximately 60 mW /Kg. There was some evidence that performance was related to size in the songbirds as a group, the smaller bird being less effective than the larger. Differences in performance are discussed in relation to the presence or absence of intrinsic muscles in the syrinx and to possible effects of scale on the efficiency of the fundamental sound-producing process.
Thermal Acclimation of A Central Neurone in Helix Aspersa
Authors: Langley C. K.
Published: April 2021

Thermal acclimation of the F1 neurone does not appear to result from changes in the chemical composition of the haemolymph. This is deduced from the lack of effect on the electrical characteristics of control neurones of either pooled haemolymph from acclimated individuals, or variations in the experimental salines made in accordance with haemolymph analyses. Changes in [Ca]0 tended to act cooperatively with temperature shifts to induce alterations in the electrical properties of the neurone, notably to increase excitability and lower membrane resistance. Warm acclimation was associated with increased resting conductance of the neuronal membrane to sodium and potassium, whereas chloride conductance appeared little affected.
Bathing Solution Tonicity and Potassium Transport by the Midgut of the Tobacco Hornworm Manduca Sexta
Authors: Moffett David F.
Published: April 2021

Potassium transport by the isolated midgut of Manduca larvae, as measured by the short circuit current, is inhibited by substitution of small organic solutes (M.W. < 340) for the sucrose normally included in bathing solution formulated for this tissue. Other solutes of molecular weight equal to or greater than sucrose are essentially as effective as sucrose in promoting the short circuit current. Equilibration of midgut in solutions containing the small solute mannitol results in a decrease in the dry weight/wet weight ratio of the tissue, suggesting that the small solutes can penetrate into areas of the tissue which are not accessible to sucrose. Histological studies suggest that sites of swelling in the presence of mannitol include both cytoplasm and goblet cell lumen. The inhibition of the short circuit current is rapidly reversible on return to bathing solution containing sucrose or another large solute. The effect of small solutes probably does not involve compromise of the energy source for potassium transport since oxygen uptake is unchanged in the presence of a small solute.
Interlimb Coordination During Slow Walking in the Cockroach
Authors: Greene Sharon I. , Spirito Carl P.
Published: April 2021

This paper examines changes in interlimb coordination resulting from lesions in the CNS during tethered, ball-walking in the cockroach. After a single connective was cut, between either the first and second or second and third thoracic ganglia, there were shifts in the mean interlimb coordination between legs as a function of time after surgery. During the first day, the mean coordination between legs bordering the cut was altered and contralateral phase changed greatly posterior to the lesion. From 1 to 10 days post-op, the relationship between all leg pairs changed unpredictably, and phase became variable. In general, the gait stabilized between 20 and 36 days after an operation. The new pattern of walking was significantly different from both that of normal individuals and that seen one day after surgery. At 36 days the legs adjacent to the cut remained relatively uncoordinated, and there were distinct changes in the mean coordination of other leg pairs. These results suggest that a neural reorganization of the locomotor system takes place after surgery.
Temperature-Related Changes in the Erythrocytic Carbonic Anhydrase (Acetazolamide-Sensitive Esterase) Activity of Goldfish, Carassius Auratus*
Authors: Houston Arthur H. , Mearow Karen M.
Published: April 2021

Carbonic anhydrase activity in ‘membrane ‘and’ cytosol ‘fractions of goldfish erythrocytes was assayed by the p-nitrophenyl acetate procedure following thermal acclimation. The thermal sensitivity of ‘membrane’-associated activity was apparently unaltered by acclimation. ‘Cytosol’ activity in warm-accfimated specimens was somewhat more thermosensitive than that of animals maintained at low temperature. Significant increases in specific activity, and activity per unit volume of packed cells and blood were observed at higher temperatures when assays were conducted at the temperatures at which the system actually functions in the fish. By contrast, when determinations were carried out at a standard temperature (41°C) corresponding to the upper incipient lethal for this species, activity was either unaffected, or declined as acclimation temperatures increased. Changes in carbonic anhydrase activity following acclimation are consistent with the hypothesis that this system is implicated in the maintenance of stable plasma chloride levels, and the suggestion that alterations in red cell chloride levels with temperature are, in part at least, attributable to concomitant variations in enzyme activity.
The Effects of Acclimation Temperature on A Neuromuscular System of the Crayfish, Astacus Leptodactylus
Authors: Harri Mikko , Florey Ernst
Published: April 2021

Crayfish, Astacus leptodactylus, were acclimated to 12°C and to 25°C. Nerve muscle preparations (closer muscle of walking legs) were subjected to temperatures ranging from 6 to 32°C. The resting membrane potential of muscle fibres was found to increase with temperature in a linear manner, but with a change in slope at around 17° in cold-acclimated preparations, and around 24°C in warm-acclimated ones. Temperature acclimation shifted the temperature range of maximal amplitudes of fast and slow e.j.p.s toward the acclimation temperature. Optimal facilitation of slow e.j.p.s also occurred near the respective acclimation temperature. E.j.p. decay time is nearly independent of temperature in the upper temperature range but increases steeply when the temperature falls below a critical range around 17°C in preparations from cold-acclimated animals, and around 22°C after acclimation to 25°C. Peak depolarizations reached by summating facilitated e.j.p.s are conspicuously independent of temperature over a wide range (slow and fast e.j.p.s of cold-acclimated preparations, fast e.j.p.s of warm-acclimated ones) which extends to higher temperatures after warm acclimation in the case of fast e.j.p.s. In warm-acclimated preparations the peak depolarization of slow e.j.p.s first falls then rises and falls again as the temperature increases from 8 to 32°C. Tension development elicited by stimulation of the slow axon at a given frequency reaches maximal values at the lower end of the temperature range in cold-acclimated preparations. The maximum is shifted towards 20°C after warm acclimation. Fast contractions decline with temperature; possible acclimation effects are masked by the great lability of fast contractions in warm-acclimated preparations. It is suggested that changes in the composition of membrane lipids may be responsible for the effects of acclimation on the electrical parameters and their characteristic temperature dependence.
Block Intensification of Neurones Stained with Cobalt Sulphide: A Method for Destaining and Enhanced Contrast
Authors: Pitman Robert M.
Published: April 2021

In characterizing neurones it is important to have both physiological and morphological information. This was first realized in a practical sense by Stretton & Kravitz (1968), who explored the use of the Procion series of dyes and used them to study the morphology of identified lobster neurones. Initially, Procion dyes were injected into single neurones using microelectrodes. However, it was later found that Procion Yellow could be introduced into the cut end of axons (Iles & Mulloney, 1971). This made it possible both to stain small neurones which would be hard to impale with microelectrodes, and also to determine rapidly the position of the cell bodies of neurones with axons in a given nerve trunk. Subsequently, it was found that neurones could be stained by introduction of cobalt ions followed by the formation of a black precipitate of cobalt sulphide (Pitman, Tweedle & Cohen, 1972). This method had the advantage that intact neurones could be observed in whole-mount preparations. A great improvement on the resolution of the cobalt sulphide method was obtained using a modification of the Timm ‘s sulphide-silver intensification procedure (Tyrer & Bell, 1974). This made it possible to visualize fine branches of neurones which were too lightly stained to be seen using the original cobalt sulphide method. It is also relatively permanent, whereas unintensified preparations often fade. However, a disadvantage of this modification was that it required sectioning of the tissue before intensification. More recently, block intensification methods have been described (Strausfeld & Obermayer, 1976; Bacon & Altman, 1977). These permit whole-mount viewing of entire neurones with intensely stained fine processes.
Size-Dependent Variation in the Evasive Behaviour of the Bivalve Mollusc Spisula Solidissima
Authors: Prior David J. , Schneiderman Anne M. , Greene Sharon I.
Published: April 2021

The evasive jump response of Spisula can be elicited by contact of the siphons with the tube feet of a starfish (Asterias forbesi). The level of responsiveness varies with the size of the individual clam; small clams (2·0–5·0 cm) being very responsive, large clams (12·0–18·0 cm) being totally unresponsive. The cell bodies of touch-sensitive neurones subserving the siphons are located in the visceral ganglion. The mean area of the receptive fields of these neurones in small clams is 33·8 mm2 and in large clams is 9·7 mm2. In small clams the large proportion of the total siphon surface innervated by single touch-sensitive neurones results in considerable overlap of receptive fields. As a result of this overlap, numerous touch-sensitive neurones are activated by a point stimulus. The variation in jump responsiveness of large and small clams is correlated with the size of the receptive fields of touch-sensitive neurones.
Crayfish Escape Behaviour: Commands for Fast Movement Inhibit Postural Tone and Reflexes, and Prevent Habituation of Slow Reflexes
Authors: Kuwada John Y. , Wine Jeffrey J.
Published: April 2021

Organized behaviour requires central neural mechanisms to prevent the simultaneous occurrence of incompatible movements. We investigated neural pathways in crayfish that suppress slow flexion of the abdomen during rapid flexions (‘tailflips’) produced by a separate set of muscles. The slow flexors are innervated in each half segment of the abdomen by five motor neurones and one peripheral inhibitor. In isolated preparations of the abdominal nervous system, stimulation of identified command neurones, which trigger tailflips in intact animals, inhibited spontaneous activity in the motor neurones to the slow flexors and excited the peripheral inhibitor. These effects are mediated by a population of interganglionic interneurones interposed between the command cells and the slow flexor efferents.

Slow flexor reflexes also were inhibited by escape commands. This inhibition includes pathways that act upon early stages of sensory input. As a result, habituation of reflexes, which normally is produced by repeated stimulation, is abolished if each sensory stimulus is preceded by a burst of impulses in the command neurone.