bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the Physiology of Arenicola Marina L.
Authors: Wells G. P. , Ledingham Isabel C. 
Published: April 2021

ABSTRACT
Of the large number of published studies on the ion relations of invertebrate rhythmic muscles, the great majority concern preparations from Crustacea and molluscs—largely because the animals of these groups are provided with vigorous and experimentally convenient hearts. Data on members of other phyla are relatively few and, from the comparative point of view, their multiplication is evidently desirable. Recently, one of us published a description of the so-called “isolated extrovert” of the lugworm, Arenicola marina L., a preparation consisting of the proboscis and part of the oesophagus (Wells, 1937). Suspended in sea water, the isolated extrovert maintains for many hours a very regular and characteristic activity pattern, consisting of a series of outbursts of vigorous rhythmical contraction separated by periods of relative rest. That this is the normal activity pattern was shown in the paper already mentioned. Because of its vigour, its regularity, its long survival after excision and the ease with which that operation is performed, it is an excellent object for experiments on the action of chemical factors. The writers have undertaken a study of ion actions on this preparation. The results obtained by varying the Mg concentration form the subject of the present communication. Experiments with K and Ca have been begun and it is hoped to complete them shortly.
Relationship Between Heart Rate and Oxygen Consumption During Steady-State Swimming in California Sea Lions
Authors: Butler P. J. , Woakes A. J. , Boyd I. L. , Kanatous S. 
Published: April 2021

ABSTRACT
Heart rate (fH) and rate of oxygen uptake were measured in six subadult California sea lions Zalophus californianus while they were at rest and while they were swimming for 15 min at controlled speeds of up to 1.4ms”1 and pulling loads of up to 3 kg.
There was a good linear relationship between fH and in all six sea lions. The slopes of the individual regression lines varied between 2.66 and 4.36 beats ml−lO2kg−1, the intercepts varied between 48.2 and 63.0 beats min”1 and r2 varied between 0.82 and 0.93. The mean relationship for all six sea lions is fh = (57.4 ± 2.0) + (3.58 ± 0.23) , r2=0.89±0.01. The mean of the lowest values was 5.1±0.4ml min−1 kg−1 and the mean of the highest values was 26.9±1.9 ml min−1 kg−1. The means of the lowest and highest values of fH were less extreme, being 72±3 beats min−1 and 155±5 beats min−1, respectively.
It is concluded that, by using data storage devices and grouped data, fH could be used in otariids as an indicator of aerobic metabolism under field conditions, in particular for breeding females during the period of lactation.
Resolution and Sensitivity in the Eye of the WinkleLittorina Littorea
Authors: Seyer Jan-Olof 
Published: April 2021

ABSTRACTThe winkle Littorina littorea (L.) has camera-type (simple) eyes. Light and electron microscopy were used to generate an accurate geometrical model of the eye, and this was used to predict the eye’s visual performance. The lens is spherical with a diameter of 112μm, and examination of images formed by isolated lenses indicates a mean focal length in water of 126μm. These images are crisp and apparently aberration-free. This, in addition to a shorter than expected focal length, implicates the presence of a gradient of refractive index in the lens. The lens has a focal length to lens-radius ratio of 2.3, which is close to the ‘Matthiessen ratio’ of 2.5 found in the aplanatic lenses of many other marine animals. The lens is predicted to focus images within the retina only when the eye is submerged in water: in air, images are focused distal to the retina. In the central retina, the inter-receptor angle is 1.8° and the rhabdom diameter is 4μm (5.5 times larger than the diffraction blur-circle), indicating a retinal array coarser than that necessary to sample all the information contained in the image. In addition, a low F-number (1.2) and the large possible angles of incidence of rays striking the retina (up to 40°) mean that the eye is likely to suffer substantial spreading of light between rhabdoms (which are unshielded) and further degradation of resolution. Possible behavioural roles for the eyes are discussed.
The Inner Ear Is Responsible For Detection Of Infrasound In The Perch (Perca Fluviatilis)
Authors: Karlsen Hans Erik 
Published: April 2021

ABSTRACT
In a previous study of infrasound detection in the cod, the inner ear was suggested to be the sensory organ responsible for the responses. However, a possible involvement of the lateral-line system in the observed low-frequency detection could not be ruled out. The infrasound sensitivity was therefore studied in perch (Perca fluviatilis) with normal and blocked lateral-line organs. The experiments were performed using a standing wave acoustic tube and the cardiac conditioning technique. All perch readily responded to infrasound frequencies down to 0.3Hz with threshold values of approximately 2×10−4ms−2. These thresholds were not affected by complete blocking of the lateral-line system with Co2+, which suggests that the inner ear is responsible for the observed infrasound detection by the perch.
Wind-Evoked Escape Running of the Cricket Gryllus Bimaculatus:I. Behavioural Analysis
Authors: Gras Heribert , Hörner Michael 
Published: April 2021

ABSTRACT
Spontaneous walking and escape running in response to wind puffs directed to the abdominal cerci were quantitatively studied in tethered walking crickets.
An apparatus for optically recording rotations of an air-supported sphere was developed to measure the intended locomotion of insects with high linear and temporal resolution but without mechanically imposed bias. During spontaneous locomotion without sensory cues for orientation, alternate pauses of 0.35–2.2 s and walking phases of 0.5–6 s resulted in a highly variable pattern of locomotion on a meandering path. A single air puff to one or both of the wind-sensitive cerci evoked a short run, whereas a continuous sequence of puffs caused sustained escape running with a tendency to turn away from the stimulus source. Escape running was characterized by a series of stereotyped running bouts and pauses, both significantly shorter than those recorded during spontaneous locomotion. Forward speed and angular speed of escape running correlated linearly with the wind puff frequency between 5 and 10Hz. This was caused by a shortening of the standing phases, while the durations of the running bouts were constant. The reflex-like running bouts and the pattern of escape running were largely independent of the duty cycle of the wind puff series and the wind speed. Neither individual steps nor running bouts were synchronized with the stimulus pattern. The behavioural modes of spontaneous walking and escape running were maintained with a minor reduction in general activity in partly dissected specimens during intracellular recording in the prothoracic ganglion. Each impaled local interneurone with locomotion-related activity generated action potentials in the actual step rhythm of walking and running bouts, but did not show specific activity during escape running. Some of these local neurones, however, showed modulations of spike frequency before or during intended turns and may participate in the coordination of the prothoracic legs.
Control of Impulse Discharge of Visual Interneurones by the Receptive Field Surround in Butterfly Larvae
Authors: Ichikawa Toshio 
Published: April 2021

ABSTRACT
The influence of interactions between the antagonistic centre and surround areas of receptive fields on the electrical activities of medulla neurones was examined in the larval swallowtail butterfly Papilio xuthus. Weak signals from the surround had a significant depressive effect on the maintained discharge, which increased for on-centre cells or decreased for off-centre cells in response to illumination of the centre. Moderation of the maintained discharge suppressed saturation of the response and extended the graded response range of the neurones. Surround illumination also reduced irregular fluctuations in the membrane potentials and variability in the discharge rate of impulses. The results indicate that the spatial inhibitory mechanism is important for the larval visual system in order to increase the efficiency of signal processing.
The role of V-ATPase in neuronal and endocrine systems
Authors: Moriyama Yoshinori , Maeda Masatomo , Futai Masamitsu 
Published: April 2021

ABSTRACT
Synaptic vesicles have important roles in the neural transmission at nerve terminals: the storage and the controlled exocytosis of neurotransmitters. At least two different factors are responsible for the concentration process: the vacuolar-type H+-ATPase (V-ATPase), establishing an electrochemical gradient of protons, and specific transport systems for transmitters. We will discuss our recent progress on the energy-transducing systems in synaptic vesicles: (1) structural aspects of V-ATPase; (2) energy coupling of transport of transmitters; (3) reconstitution of transporters; (4) effects of neurotoxins and neuron blocking agents; (5) function of synaptic-vesicle-like microvesicles from endocrine tissues.
The osteoclast proton pump differs in its pharmacology and catalytic subunits from other vacuolar H+-ATPases
Authors: Chatterjee D. , Chakraborty M. , Leit M. , Neff L. , Jamsa-Kellokumpu S. , Fuchs R. , Bartkiewicz M. , Hernando N. , Baron R. 
Published: April 2021

ABSTRACT
Osteoclasts are multinucleated cells derived from the mononuclear phagocyte system in the hematopoietic bone marrow. Their function is to resorb bone during skeletal growth and remodeling. They perform this function by acidifying an enclosed extracellular space, the bone resorbing compartment. Analysis of proton transport by inside-out vesicles derived from highly purified chicken osteoclast membranes has revealed the presence of a novel type of multisubunit vacuolar-like H+-ATPase. Unlike H+-ATPases derived from any other cell type or organelle, proton transport and ATPase activity in osteoclast vesicles are sensitive to two classes of inhibitors, namely V-ATPase inhibitors [N-ethyl-maleimide (NEM) and bafilomycin Ai] and vanadate (IC50 100 μmol l−1), an inhibitor previously found to affect only P-ATPases. The osteoclast V-ATPase morphologically resembles vacuolar proton pumps and contains several vacuolar-like subunits (115×103, 39×103 and l6×103Mr), demonstrated by Western blot analysis. Subunits A and B of the catalytic domain of the enzyme, however, differ from that of other V-ATPases. In osteoclasts, subunit A has an Mrof 63×103 instead of 67×103–70×I03; in contrast, monocytes, macrophages and kidney microsomes, which contain a vanadate-insensitive H+-ATPase, express the classical subunit A (70×103Mr). Moreover, two types of 57×103–60×103MrB subunits are also found: they are differentially recognized by antibodies and one is expressed predominantly in osteoclasts and the other in bone marrow cells and in kidney microsomes. Preliminary cloning data have indicated that the B subunit expressed in osteoclasts may be similar to the brain isoform. The osteoclast proton pump may, therefore, constitute a novel class of V-ATPase, with a unique pharmacology and specific isoforms of two subunits in the catalytic portion of the enzyme.
Biochemistry of the renal V-ATPase
Authors: Gluck Stephen L. , Nelson Raoul D. , Lee Beth S. , Wang Zhi-Qiang , Guo Xiao-Li , Fu Ji-Yi , Zhang Kun 
Published: April 2021

ABSTRACT
In most eukaryotic cells, vacuolar H+-ATPases (V-ATPases) are present primarily or exclusively in intracellular membrane compartments, functioning in the acidification of the endocytic and secretory vacuolar apparatus necessary for constitutive cell function. V-ATPases also participate in renal hydrogen ion secretion in both the proximal and distal nephron, residing at high concentrations on the plasma membrane, where they are regulated physiologically to maintain the acid-base balance of the organism. Recent experiments have begun to reveal how the kidney controls transcellular proton transport while still maintaining acidification of intracellular compartments. Control may occur by recruitment of proton pumps to or away from the plasma membrane. The protontransporting plasma membrane of intercalated cells is a specialized apparatus that translocates the enzyme between an intracellular membrane pool and the plasma membrane in response to physiological stimuli. Regulation may also occur by changes in the kinetics of the V-ATPase. V-ATPases are a family of structurally similar enzymes which differ in the composition of specific subunits. Cytosolic regulatory enzymes present in renal cells may preferentially affect V-ATPases in selective membrane compartments.
Complex modulation of cation channels in the tonoplast and plasma membrane of Saccharomyces cerevisiae: single-channel studies
Authors: Bertl A. , Slayman C. L. 
Published: April 2021

ABSTRACT
Detailed patch-clamp studies have been made of ion channels in the plasma membrane and tonoplast of the yeast Saccharomyces cerevisiae. The predominant tonoplast channel is a high-conductance cation-selective inward rectifier (passing ions easily into the cytoplasm from the vacuole), with its open probability (Po) peaking at about −80mV (cytoplasm negative) and falling to near zero at +80mV. It has a maximal slope conductance of approximately 150pS in 100mmoll−1 KCl, and conducts Na+, K+ and Ca2+. Elevated cytoplasmic Ca2+ concentration, alkaline pH and reducing agents can activate the channel, its likely physiological function being to adjust cytoplasmic Ca2+ concentration from the vacuolar reservoir. The predominant plasma-membrane channel is a strongly outward rectifying K+ channel (passing K+ easily out of the cytoplasm to the extracellular medium), which is activated by positive-going membrane voltages as well as by elevated cytoplasmic Ca2+ concentration and alkaline pH. Interaction between membrane voltage and [Ca2+]cyt is complex and defines three parallel closed states for the channel: a Ca2+-independent brief closure (I), a calcium-inhibited long closure (G) and, at large positive voltages, a calcium-induced brief blockade (B). This channel is likely to function in steady-state turgor regulation and in charge balancing during proton-coupled substrate uptake.
Energization of sodium absorption by the H+-ATPase pump in mitochondria-rich cells of frog skin
Authors: Harvey Brian J. 
Published: April 2021

ABSTRACT
The frog skin in vivo is capable of active transepithelial H+ secretion (JH) which is matched by Na+ absorption (JNA). Studies in vitro demonstrate that JH is generated by an H+-ATPase pump localized in apical membranes of mitochondria-rich (MR) cells, whereas JNa occurs through an amiloride-sensitive pathway in principal (P) cells. The H+ pump is sensitive to inhibitors of carbonic anhydrase (e.g. acetazolamide) and to specific inhibitors of mitochondrial F1F0 H+-ATPase (oligomycin) and vacuolar (V)-type H+-ATPase (N-ethylmaleimide) and to inhibitors of both these types of H+-ATPases (dicyclohexylcarbodiimide, DCCD). JH is independent of external K+, which differentiates it from gastric H+/K+-ATPase and is strictly dependent on aerobic metabolism. The proton pump is primarily implicated in whole-body acid–base regulation. Acute stimulation of JH in response (seconds–minutes) to an acid load involves insertion of H+ pumps (exocytosis) from a cytosolic pool into the apical membrane. The chronic response (days) to metabolic acid load involves morphological changes (increased apical membrane surface area and number of MR cells). Whole-cell patch-clamp recordings of membrane capacitance and current fluctuations from MR cells demonstrate that a respiratory acid load and aldosterone produce rapid exocytotic insertion of DCCD-sensitive conductive membrane.
A secondary role of the H+ pump is to energize sodium absorption (JNa ) via principal cells from dilute solutions in the absence of a permeant anion under open-circuit conditions. The apparent 1:1 stoichiometry between JH and JNa is a result of transepithelial electrical coupling between these electrogenic fluxes. The H+ pump in MR cells generates a transepithelial current (serosa to apical) which acts as a physiological voltage-clamp to hyperpolarize the apical membrane of P cells. This hyperpolarization can facilitate passive Na+ entry across the apical membrane against a threefold chemical gradient. Since both JH and JNa are sensitive to membrane potential, inhibition or activation of one will produce similar effects on the transport of the other ion. For example, inhibition of JH by ethoxzolamide will reduce JNa. Conversely, blocking JNa with amiloride also inhibits JH. These effects can be avoided or reversed if variations in membrane potential are prevented by voltage-clamping the epithelium. A paradoxical activation of JNa is observed when JH is stimulated by an acid load (CO2), despite inhibition of Na+ channel activity by H+ in P cells. Patch-clamp studies reveal the presence of Na+ channels in MR cells which may provide a route for Na+ absorption energized by the H+ pump when Na+ channels in P cells are closed by an acid load.
Ion transport in parasitic protozoa
Authors: Bakker-Grunwald Tilly 
Published: April 2021

ABSTRACT
Many parasitic protozoa go through complex life cycles in the course of which they adapt to widely different environments; ion transport processes are expected to play a role both in pathogenicity and in adaptation. So far, studies on ion transport have been virtually limited to Leishmania, Plasmodium and Entamoeba. The distribution of ion pumps in the former two organisms generally appears to conform to the picture established for other protozoa, i.e. a proton-motive P-ATPase in the plasma membrane provides the driving force for H+-coupled secondary-active transport, a proton-motive V-ATPase in the digestive vacuoles is responsible for vacuolar acidification, and an F-ATPase (ATP synthase) is found in the mitochondria. The situation in Entamoeba, an archaic organism that lacks mitochondria, could be different from that in the two other parasites in that a V-ATPase may be present and active both in the plasma membrane and in the membranes of the endocytic vesicles.
V-ATPase-energized epithelia and biological insect control
Authors: Wolfersberger Michael G. 
Published: April 2021

ABSTRACT
Background is provided for the experimentally detailed contributions concerning the structure, distribution and function of V-ATPase-based ion pumps in insect epithelia. The mode of action of an insecticidal bacterial protein, which is dependent upon the V-ATPase-energized state in larval lepidopteran midgut for activity, is discussed.
Circuit analysis of transmembrane voltage relationships in V-ATPase-coupled ion movements
Authors: Martin Francis G. 
Published: April 2021

ABSTRACT
The concept of electrical circuit analysis is extended to include components found in membrane ionic transport systems. As in classical electrical equivalent circuits, resistors and capacitors are used to represent ion channels and the membrane capacitances, respectively; batteries represent energy sources driven by chemical reactions. In the extensions proposed, energy stored in various ionic concentrations is treated as charges on compartmental capacitors; symporters and antiporters are treated as energy-coupling devices analogous to transformers in alternating current electrical circuits. Pumps are shown to be special cases of porters in which the input circuit derives its energy from a chemical reaction. Using these components, circuit diagrams are drawn for several examples of membrane ion transport systems. By applying appropriate circuit analysis techniques, these diagrams facilitate the quantitative description of the energy distributions throughout the system.
The importance of being acid: the role of acidification in intracellular membrane traffic
Authors: Mellman Ira 
Published: April 2021

ABSTRACT
Ever since the early work of Elie Metchnikoff at the turn of the century, it has been clear that the ability of vacuolar organelles to generate and maintain pH plays a crucial role in a variety of critical cellular functions. Using a variety of crude pH indicators such as neutral red or litmus particles, Metchnikoff observed that bacteria ingested by phagocytic cells of the immune system were transferred to acidic structures in the cytoplasm, killed and then digested. Without any understanding or knowledge of membranes, organelles or proton pumps, Metchnikoff drew accurate conclusions concerning the necessity of an acidic milieu for intracellular digestion, the role of cellular energy in maintaining the acidic pH, and the likelihood that the acidity was due to diffusible protons as opposed to the infusion of acidic substances such as DNA (which had, in fact, been offered as an explanation by some of Metchnikoff s contemporaries).
Insect malpighian tubules: V-ATPase action in ion and fluid transport
Authors: Maddrell S. H. P. , O’Donnell M. J. 
Published: April 2021

ABSTRACT
Insect Malpighian tubules secrete fluid into the lumen as part of their function as excretory organs. The underlying ion transport is, when stimulated, faster than in any other known tissue. It is driven by the activity of an H+-transporting V-ATPase situated on the luminal cell membranes. This ATPase, together with cation/H+ antiporter(s), constitutes a common cation pump which can transport sodium ions, potassium ions or both. Treatments that selectively slow cation transport across the epithelium cause the secreted fluid to become alkaline, whereas those that selectively reduce the rate of anion passage lead to secretion of acid fluid.
Escherichia coli ATP synthase (F-ATPase): catalytic site and regulation of H+ translocation
Authors: Futai Masamitsu , Iwamoto Atsuko , Omote Hiroshi , orita Yuji , Shin Kouichirou , Nakamoto Robert K. , Maeda Masatomo 
Published: April 2021

ABSTRACT
We discuss our recent results on the Escherichia coli F-ATPase, in particular its catalytic site in the β subunit and regulation of H+ transport by the γ subunit. Affinity labelling experiments suggest that βLys-155 in the glycine-rich sequence is near the γ-phosphate moiety of ATP bound at the catalytic site. The enzyme loses activity upon introduction of missense mutations in βLys-155 or βThr-156 and changes catalytic properties upon introduction of other mutations. By analysis of mutations and their pseudo revertants, residues β Ser-174, β Glu-192 and β Val-198 were found to be located near the glycine-rich sequence. The combined approaches of chemical labelling and genetics have been fruitful in visualizing the structure of the catalytic site. Analysis of mutations in the y subunit suggests that this subunit has an essential role in coupling catalysis with proton translocation.