bluuebunny/crossref_metadata_2025_split huggingface dataset:
Osmotic Regulation in the Brackish-Water Rotifer Brachionus Plicatilis (Muller)
Authors: Epp R. W. , Winston P. W. 
Published: April 2021

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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. &lt; 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

ABSTRACT
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.