bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical Responses of the Carnivorous Ciliate Didinium Nasutum in Relation to Discharge of the Extrusive Organelles
Authors: Hara Ritsuo , Asai Hiroshi , Naitoh Yutaka 
Published: April 2021

ABSTRACT
The carnivorous ciliate Didinium nasutum discharged its extrusive organelles when a strong inward current was injected into the cell in the presence of external Ca2+ ions. In the absence of external Ca2+ ions, the strong inward current produced fusion of the apex membrane of the proboscis. External application of Ca2+ ions after the fusion of the apex membrane produced discharge of the organelles. An increase in Ca2+ concentration around the organelles seems to cause discharge of the organelles. Ca2+ concentration threshold for the discharge of the pexicysts seems to be lower than that for the toxicysts. External Ca2+ ions were not necessary for discharge of the organelles upon contact with Paramecium. Chemical interaction of the apex membrane with Paramecium membrane may cause intracellular release of Ca2+ ions from hypothetical Ca2+ storage sites around the organelles. A small hyperpolarizing response seen before the discharge upon contact with Paramecium seems to correlate with the chemical interaction, The depolarizing spike response associated with discharge of the organelles is caused by the depolarizing mechanoreceptor potential evoked by mechanical stimulation of the proboscis membrane by the discharging organelles.
Force-Velocity Characteristics and Metabolism of Carp Muscle Fibres Following Temperature Acclimation
Authors: Johnston Ian A. , Sidell Bruce D. , Driedzic William R. 
Published: April 2021

ABSTRACT
Common carp (Cyprinus carpio L.), 1 kg body weight, were acclimated for 1–2 months to water temperatures of either 7–8°C (cold-acclimated group) or 23–24°C (warm-acclimated group). Single fast fibres and small bundles of slow fibres were isolated from the myotomal muscles and chemically skinned. Force-velocity (P-V) characteristics were determined at 7°C and 23°C.
The contractile properties of carp muscle fibres are dependent on acclimation temperature. In the warm-acclimated group maximum isometric tensions (P0, kN m−2) are 47 ± 6 and 64 ± 5 for slow muscle fibres and 76 ± 10 and 209 ±21 for fast muscle fibres at 7°C and 23°C, respectively. Maximum contraction velocities (Vmm, muscle lengths−1), are 0·4 ± 0·05 and 1·5 ± 0·1 at 7°C (slow fibres) and 0·6 ± 0·04 and 1·9 ± 0·4 at 23°C (fast fibres). All values represent mean ± S.E.
P0 and Vmax at 7°C are around 1·5–2·0 times higher for slow and fast muscle fibres isolated from the cold-acclimated group. Fibres from 7°C-acclimated carp fail to relax completely following maximal activations at 23°C. The resulting Ca-insensitive force component (50–70% Po) is associated with the development of abnormal crossbridge linkages and very slow contraction velocities.
Activities of enzymes associated with energy metabolism were determined at a common temperature of 15°C. Marker enzymes of the electron transport system (cytochrome oxidase), citric acid cycle (citrate synthase), fatty acid metabolism (carnitine palmitoyl transferase, β-hydroxyacyl CoA dehydrogenase) and aerobic glucose utilization (hexokinase) have 30–60% higher activities in slow muscle from cold-acclimated than from warm-acclimated fish. Activities of cytochrome oxidase and citrate synthase in fast muscle are also elevated following acclimation to low temperature. It is concluded that thermal compensation of mechanical power output by carp skeletal muscle is matched by a concomitant increase in the potential to supply aerobically-generated ATP at low temperatures.
Mosaic Collodion Membranes as Analogues of the Plasma Membrane
Authors: Brooks S. C. 
Published: April 2021

ABSTRACT
This paper deals with an attempt to demonstrate selective accumulation of ions by the use of a cell bounded by two dense collodion membranes, one of which was impermeable to anions and the other impermeable to cations. Such a cell would, if successful, constitute a system analogous to many living cells (Brooks, 1929).
The Role of Iron and Silica in the Structure of the Radular Teeth of Certain Marine Molluscs
Authors: Jones E. I. , McCANCE R. A. , Shackleton L. R. B. 
Published: April 2021

ABSTRACT
Although the morphology of the radulae of molluscs have been extensively studied, but little is known of their composition ; it is generally stated to be of a chitinous nature. There are two exceptions to this statement: Troschel (1856) and Sollas (1907). The former reported that calcium, phosphorus and iron were present in the enamel which covered the teeth and that the organ contained both organic and inorganic constituents. Sollas found that the radulae of the Docoglossa contained up to 27 per cent, of ash of which silica was the chief constituent: from microdeterminations of specific gravity she suggested that the silica was in the form of a hydrate or opal ; the marginal teeth were found to contain no silica. She recognised the presence of iron and stated that “the ash contained (in addition to silica) a noticeable quantity of calcium, iron, magnesium and phosphoric acid.” No other groups of molluscs were found to have siliceous teeth in their radulae, but to have chitinous teeth hardened by deposits of iron, calcium and phosphorus. The Chitonidae were somewhat exceptional, for the most important constituent of their teeth was ferric oxide.
A Method for Determining the Amount of Oxygen Dissolved in I C.C. of Water
Authors: Van Dam L. 
Published: April 2021

ABSTRACT
A description is given of a simple micromethod for determining the amount of oxygen dissolved in water. The method is based on the Winkler procedure and requires only 1 c.c. of water for each analysis. It has the further advantage of avoiding all contact between water and air ; consequently, even water of a very low oxygen content may be analysed accurately.
Iodine Compounds and Fertilisation
Authors: Carter G. S. 
Published: April 2021

ABSTRACT
In the earlier papers of this series (1931–2) the action of iodine compounds on the fertilisation reactions of the two common British species of sea-urchin, Echinus esculentus and E. miliaris, has been discussed, and a theory of the changes which occur at fertilisation in this genus has been founded on the results of the discussion. Before this theory can be accepted as true of fertilisation in general, it is clear that gametes of other types must be investigated. Up to the present the only experiments discussed in these papers which have been concerned with animals other than the sea-urchins have been those on the sperm of the rabbit which formed the subject of the preceding paper (1932e).
Metabolic Rates of Ephemerid Nymphs From Swiftly Flowing and From Still Waters
Authors: Fox H. Munro , Simmonds B. G. , Washbourn R. 
Published: April 2021

ABSTRACT
The oxygen consumptions of the small ephemerid nymphs Ephemerella ignita and Coenis sp. are (anaesthetised at 10° C.) 950 and 290 c.mm./gm./hour. Their habitats are respectively a stream and a pond. The oxygen consumptions of the large ephemerid nymphs Ecdyonurus venosus, Ephemera danica and E. vulgata are (anaesthetised at io° C.) 604, 370 and 278 c.mm./gm./hour. They live, respectively, under stones in a swift stream, burrowing in sand in a stream, and burrowing in mud in a pond. Ecdyonurus venosus is less resistant to oxygen deficiency than Ephemera danica and E. vulgate; and Baetis rhodani (swift stream) is less resistant than Chloeon dipterum (pond).
Impulses in the Segmental Nerves of the Earthworm
Authors: Prosser C. Ladd 
Published: April 2021

ABSTRACT
The literature dealing with the peripheral components of the nervous system of the earthworm has been reviewed recently by Stephenson (1930) and Prosser (19346). Hence it is necessary only to mention the principal elements. The sensory endorgans are said to consist of (1) a variety of epidermal cells (“sensory cells”) which have peripheral terminations, are of different shapes, and may be grouped as “sense organs” or may be isolated, (2) free nerve endings, some of which are closely associated with the glandular cells, and (3) intermuscular cells. Certain of the epidermal sensory cells have been shown to be photosensitive; the function of the others is uncertain. Most of them are connected to a subepidermal plexus which appears to be a true network of anastomosing fibres and to contain nerve cells. In each segment three pairs of nerves lead from the central ganglion to nerve rings from which fibres are distributed either by nerve branches or by the peripheral network to the muscles and sensory cells. There is some evidence for and some against conduction of locomotor impulses by the peripheral plexus across segments lacking the nerve cord. Prosser (19346) concluded that the contrary evidence is slightly stronger.
The Respiratory Rate of Gammarus Chevreuxi in Relation to Differences in Salinity
Authors: Löwenstein Otto 
Published: April 2021

ABSTRACT
The rate of oxygen uptake was studied in the brackish water amphipod Gammarus chevreuxi in water of different salinities (25 per cent, sea water and sea water). The respiratory rate was found to be approximately 20 per cent, lower in sea water than in 25 per cent, sea water which is a concentration occurring in the natural habitat. Anaesthetised animals showed the same percentage decrease as unanaesthetised animals. The change in oxygen consumption takes place immediately after the transfer and remains constant thereafter. It is completely reversible. A comparison with the unanaesthetised respiratory rates of the related freshwater species G. pulex and marine G. marinus shows that the rate of oxygen consumption of the brackish water form G. chevreuxi in 25 per cent, sea water lies between the two others.
Serum Relationships Within the Family Cercopithecidae
Authors: Zuckerman S. , Sudermann Ann E. 
Published: April 2021

ABSTRACT
Quantitative tests show that an antiserum for an individual of one species of the Old World monkey family Cercopithecidae may react no more strongly with the blood of another individual of the same species than it does with the blood of monkeys belonging to other species or genera of the same family. They also show that in this family of Primates interspecific precipitin responses may be no stronger than intergeneric ones. Furthermore, the specific and generic serum interrelationships of these monkeys may be no closer than their interfamilial serum relationships to the chimpanzee. The latter relationship appears, however, to be closer than the monkeys’ interfamilial serum relationship to man. Human serum nevertheless does give a group reaction to anti-Old World monkey serum, whereas such a response is not given either by the brown capuchin, a New World monkey, or by the lemur, Perodicticus potto.
These findings support the view, developed both by Erhardt (1929) and Manwaring (1934), that the serum-precipitin test is of limited value in tracing phylogenetic relationships.
Termination of Pregnancy in the Rabbit by Intravenous Injection of Anterior Lobe Pituitary Extract
Authors: Bellerby C. W. 
Published: April 2021

ABSTRACT
Ovulation can be induced in the pregnant rabbit at different stages of gestation by a single intravenous injection of extract prepared from the anterior lobe of the pituitary. It is almost invariably associated with either resorption or abortion of the embryos. In most cases, atrophy of all the existing corpora lutea of pregnancy is produced, but in the early stages both atrophic and non-atrophic structures can be found together. Ovulation does not occur exclusively; haemorrhagic follicles being also produced as a result of the action of the extract. The proportions in which ruptured and haemorrhagic follicles are formed varies according to the stage of pregnancy at which injection is made.
Methods of Measuring the Evaporation of Water from Animals
Authors: Ramsay J. A. 
Published: April 2021

ABSTRACT
The physical theory of evaporation in still air and in moving air is outlined. An apparatus is described in which controlled conditions of temperature, humidity and wind velocity are obtained. The effects of these three factors upon the rate of evaporation from simple physical systems have been investigated. Sources of error attaching to experiments carried out in still air are enumerated. The law of saturation deficiency is shown to be theoretically untrue.
The Evaporation of Water from the Cockroach
Authors: Ramsay J. A. 
Published: April 2021

ABSTRACT
The effects of temperature, humidity and wind velocity upon the rate of evaporation of water from the cockroach Periplaneta americana have been studied. The effects of these factors upon the rate of evaporation from the tracheal system are shown to be similar to their effects upon purely physical systems. The effects of these factors upon the rate of evaporation from the body surface are shown to be complicated by the presence of a film of fatty substance which undergoes a change of state at about 30° C.
The Fused Thoracic-Abdominal Ganglion of the Hermit Crab (Pagurus Pollicaris): Neuromuscular Relationships in the Thoracic and Abdominal Flexor Muscles
Authors: Stephens Philip J. 
Published: April 2021

ABSTRACT
The physiological and morphological properties of the thoracic flexor neuromuscular systems are described for the hermit crab Pagurus pollicaris. There are two pairs of flexor muscles in thoracic segments 3 to 5 : the dorsal flexors and the ventral flexors. The dorsal flexors are composed of fast fibres and are asymmetrical. On the left side the muscle branches laterally so that it has two points of insertion on the thoracic-abdominal sternite, compared with only one for the right side. The ventral flexors are composed of slow fibres. The dorsal flexors are supplied by two excitatory motor axons that run in the thin nerve of the first abdominal root. The ventral flexors are innervated by at least seven excitors: two from the thin nerve of the first abdominal root, three from the thick nerve of the first abdominal root, and two from the thin nerve of the fifth thoracic root. Cobalt backfilling of the first abdominal root revealed that most cells are located on the dorsal and ventral surfaces in the centre of the thoracic-abdominal (TA) ganglion. Although most of the efferent cell bodies from the thin nerve of the fifth thoracic root are located rostrally in the midline of the TA ganglion, two or three somata can be found in the same region as cell bodies from the first abdominal root. Stimulation of the giant interneurone elicits a spike in the giant flexor motor neurone and a contraction of the dorsal flexor muscles, and a spike in one of the axons in the thin nerve of the fifth thoracic root and a contraction of the ventral flexors. Axons in the third abdominal root innervate the flexor muscles in the first abdominal segment. Motor axons in this root, which includes a giant flexor motor neurone, have cell bodies in the TA ganglion - not in the first abdominal ganglion. Most of the motor axons in the fourth and fifth thoracic roots have cell bodies located in the fused TA ganglion. This suggests that the TA ganglion consists of a fusion of the first abdominal ganglion and the fourth and fifth thoracic ganglia.
Metabolic Responses of Trout (Salmo Gairdneri) To Acute Environmental Hypoxia
Authors: Dunn J. F. , Hochachka P. W. 
Published: April 2021

ABSTRACT
Rainbow trout were subjected to 1 and 3h of environmental hypoxia (20 Torr, 4°C), after which samples of blood, heart, brain, liver, and red and white muscle were removed for metabolite determination. The heart, brain and white muscle all showed signs of glycolytic activation. High-energy phosphate stores in the liver were greatly depleted, although there was no measurable decline in liver glycogen content. Glycolytic activation in the white muscle is argued to have a major impact on the hypoxia tolerance of trout, as this tissue produces the bulk of the lactate. These responses of the trout are contrasted with those of the African lungfish, a fish which is relatively tolerant of hypoxia.
Glucose Transport by the in Vitro Perfused Midgut of the Blue Crab, Callinectes Sapidus
Authors: Chu Ka Hou 
Published: April 2021

ABSTRACT
The midgut of Callinectes sapidus is capable of net transmural glucose absorption. The mucosal glucose influx by the midgut has a sodium-dependent, saturable component and a sodium-independent, non-saturable counterpart. The unidirectional mucosal to serosal flux and the mucosal influx of glucose are depressed by metabolic inhibitors, the presence of mucosal phlorizin or serosal ouabain. The low rate of net transmural glucose flux and the kinetic characteristics of mucosal influx suggest that the midgut does not play an important role in total nutrient absorption. Thin layer chromatographic analysis shows that most of the glucose appears as phosphorylated forms upon entering the midgut, suggesting that the efflux of free glucose across the serosal border requires an active mechanism.
Role of the Lower Intestine in the Adaptation of Gulls (Larus Glaucescens) to Sea Water
Authors: Goldstein David L. , Hughes Maryanne R. , Braun Eldon J. 
Published: April 2021

ABSTRACT
We used in vivo perfusion of the lower intestine (colon plus coprodeum) to examine the osmoregulatory role of that organ in glaucous-winged gulls (Larus glaucescens Naum.) drinking sea water and fresh water. The area of the lower intestine was small, 0·59 cm2 100g-1 body mass. Its electrolyte and water transport rates were unaffected by salt water acclimation. Sodium and chloride were always reabsorbed from the intestinal lumen to the plasma. The maximum sodium transport rate we measured was 37μlequivcm-2h-1, from a sodium concentration of 200 mequiv l-1. Potassium transport from the different perfusion fluids differed, and was generally negatively correlated with sodium transport, suggesting some form of sodium-potassium exchange. Solute-linked water was reabsorbed at a rate of 3·5 μlμequiv-1 Na+, permitting the lower intestinal epithelium to maintain a luminal fluid up to 130mosmolkg-1 hyperosmotic to plasma. The serosal-to-mucosal osmotic permeability coefficient of the lower intestinal epithelium was 0·21 μlcm-2h-1 (mosmolkg-1)-1. Ureteral urine from birds in both groups was usually strongly (up to 250mosmolkg-1) hypertonic to plasma, but sodium, potassium and chloride concentrations were low and constituted less than 25 % of total osmolytes. We suggest that the lower intestine of L. glaucescens does not play a major role in reclaiming urinary water and electrolytes for recycling to the salt glands.
Influence of Oxygen on the Heartbeat Rhythm of the Leech
Authors: Davis Robin L. 
Published: April 2021

ABSTRACT
Raising and lowering the oxygen content in the fluid bathing the skin of the leech modified the frequency of the heartbeat. In raised concentrations of oxygen, the period between bursts of impulses in the heart excitor motoneurones (HE cells) was reduced. Conversely, with lowered oxygen concentrations bathing the skin, the heart rate was slowed, with longer periods between bursts of firing in the HE motoneurones. Changes in oxygen concentration did not affect HE motoneurone firing patterns in preparations in which the CNS was dissected from the skin and surrounding body tissues. Various other stimuli were tried, including stroking, pinching, stretching the skin, blood vessels and gut, as well as changing the temperature. None of these stimuli mimicked the specific effects of oxygen on rhythmicity. It is concluded that peripheral receptors sensitive to changes in oxygen tension are able to influence the central neuronal circuits responsible for generating the rhythm of the heartbeat.
Octopamine Sensitivity of the Blood-Brain Barrier of an Insect
Authors: Schofield P. K. , Treherne J. E. 
Published: April 2021

ABSTRACT
Octopaminergic sensitivity of the glia that form the blood-brain barrier of the cockroach was examined using microelectrode recordings of the potential developed across this barrier layer, the perineurium. Exposure to 10−4moll−1 DL-octopamine had no significant effect upon the changes in potential induced by substitution of Tris for external sodium. Treatment with concentrations ranging from 10−4moll−1 down to 5 × 10−7 mol 1”1 enhanced the resting level of the potential after 5 min, with an accompanying depression of the magnitude of potassium-induced steps. At 10−7moll−1, there was no significant effect upon the resting level, but there was a reduction in potassium sensitivity. In a study of the effect of other neurohormonal factors, it was found that DL-synephrine could depress the response to potassium but was less effective than octopamine. In contrast, carbamylcholine, histamine and some compounds related to octopamine enhanced the potassium sensitivity. The effect of octopamine was completely blocked by phentolamine, and partially blocked by propranolol. It is concluded that the perineurium possesses an octopamine receptor that could respond to octopamine circulating in the haemolymph, and which appears to mediate a reduction in the potassium sensitivity of the basolateral membrane of these glia.
A Triphasic Ventilator for Reptiles
Authors: Hasan Z. 
Published: April 2021

ABSTRACT
In connection with studies of the spinal motor-control system (Hasan & Sasaki, 1986), the need arose to maintain freshwater turtles (Pseudemys scripta elegans) in a decapitated state for several days. Although a commercially available ventilator has been used in a similar situation (Rosenberg, 1972), such ventilators, apart from being expensive, are not designed to suit the reptilian respiratory pattern. In particular, they do not usually accommodate low frequencies of respiration, nor do they allow the apnoeic pauses (during which the lungs remain inflated while the glottis is constricted) that are observed in normal reptilian breathing (Wood & Lenfant, 1976; Jackson, 1979; Randall, Burggren, Farrell & Haswell, 1981). A simple, inexpensive ventilator was therefore constructed, which mimics the reptilian pattern. Its design is described here for possible use by others who may have similar requirements.
Transcellular and Paracellular Flow of Water During Secretion in the Upper Segment of the Malpighian Tubule of Rhodnius Prolixus: Solvent Drag of Molecules of Graded Size
Authors: Whittembury Guillermo , Biondi Angela C. , Paz-Aliaga Azael , Linares Henry , Parthe Valentín , Linares Nancy 
Published: April 2021

ABSTRACT
The following molecules graded in size were added to the fluid bathing the blind end of the upper segment of the Malpighian tubules of Rhodnius: urea (U), erythritol (E), mannitol (M), L-glucose (G), sucrose (S), polyethyleneglycol 800 (PEG), raffinose (R), inulin (I) and dextran 15 000–18 000 (D). U, E, M and G distribute themselves within the cell and the extracellular space, while S, PEG, R, I and D are exclusively extracellular. In addition, the net secretory flow of these probes was studied as a function of the net secretory volume flow (Jv). , is made up of a diffusive component , mainly due to unstirred layer effects, and of a convective component , due to the drag (entrainment) of the probes by the water flow. The relative contribution of and of for each probe was studied as a function of Jv. It was found that for U, E, M, G, S and PEG. Therefore these probes are dragged by water. On the other hand for R, I and D, which are not entrained. It is concluded that water flows via extracellular pathways since S and PEG, which are true extracellular probes, are entrained by solvent. In addition to extracellular pathways, it is suggested that the transcellular structures described by Wessing (1965) and Bergeron et al. (1985) could also be the sites of solute-solvent coupling.