bluuebunny/crossref_metadata_2025 huggingface dataset:
The Digestive Enzymes of Some Wood-Boring Beetle Larvae
Authors: Parkin E. A.
Published: April 2021

Qualitative tests for the presence of amylase, invertase, maltase, lactase, cellulase, hemicellulases A and B, and proteinase in the digestive juices of wood-boring coleopterous larvae are described.

Fourteen species representing the families Scolytidae, Cerambycidae, Lyctidae, Bostrychidae and Anobiidae, have been investigated and their nutrition is discussed in terms of the enzymes found and present knowledge of the composition of wood.

It is concluded that three types of wood feeding may be distinguished, (i) larvae able to utilize only the cell contents and perhaps part of the polysaccharides which are intermediate in composition between starch and the hemicelluloses—Lyctidae and Bostrychidae, (ii) larvae able to utilize cell contents and the carbohydrates of the cell wall up to hemicelluloses, but excluding cellulose—Scolytidae (bark beetles), and (iii) larvae able to utilize cell contents and the carbohydrates of the cell wall including cellulose—Anobiidae and most Cerambycidae.

A proteinase is of general occurrence in the larval guts of wood-boring beetles.

Digestive enzymes were absent from the gut of hibernating larvae of Scolytus destructor.
The Oxygen Consumption of Flies During Flight
Authors: Davis R. A. , Fraenkel G.
Published: April 2021

A method is described by which the oxygen uptake of the blow-fly, Lucilia sericata Mg., was measured during flight manometrically in a Warburg and in a Barcroft type of apparatus.

The average oxygen consumption in air for all the flies used was 95·5800.0. per g. wet weight per hour. When flying in pure oxygen the rate of oxygen consumption showed no significant difference ; in oxygen-nitrogen mixtures, containing 10 and 5% oxygen, the rate was considerably less than in air.
Contribution of the Secondary Circulatory System to Acid–Base Regulation During Hypercapnia in Rainbow Trout (Oncorhynchus Mykiss)
Authors: Ishimatsu Atsushi , Iwama George K. , Bentley Timothy B. , Heisler Norbert
Published: April 2021

The contribution of the secondary circulatory system to acid–base regulation and epithelial ion transport was evaluated qualitatively in freshwater-acclimated rainbow trout. The dorsal aorta (DA) and the lateral cutaneous vessel (LCV) (which is considered to be the venous drainage of the secondary system) were chronically cannulated and the fish were exposed to environmental hypercapnia (2% CO2) after establishment of normocapnic control values. Fluid sampled from the LCV contained much less haemoglobin (0.14 g 100 ml−1 ) and fewer blood cells (packed cell volume, PCV, 1.2-1.7%) than DA blood ([Hb] 8.2-8.9g100ml−1, PCV 27.2-32.5%) regardless of ambient CO2 levels, indicating highly limited access of red blood cells to the secondary circulatory system through anastomoses connecting it to the primary system. There was no significant difference between the two sampling sites for any of the acid–base variables (pH, , [HCO3−]) and most plasma ion concentrations ([Na+], [Ca2+], [Mg2+] and [Cl−]) during normocapnia, although plasma [K+] and osmolarity were significantly lower in LCV fluid. Upon exposure to hypercapnia, the pH of LCV fluid became significantly higher than that of DA plasma because of the higher [HCO3∼] in the LCV plasma than in the DA plasma. The LCV plasma concentration of Cl− was significantly lower than that of DA plasma during hypercapnia. These data suggest that the secondary circulatory system draining the body surface is involved in ionic acid–base regulation in fish, probably via CE/HCO3− exchange processes across the extrabranchial epithelium of the body surface.
Orientation to Oceanic Waves by Green Turtle Hatchlings
Authors: Lohmann Kenneth J. , Fittinghoff Lohmann Catherine M.
Published: April 2021

Minutes after emerging from underground nests, hatchling green turtles (Chelonia mydas L.) enter the sea and begin a migration towards the open ocean. To test the hypothesis that migrating hatchlings use wave cues to maintain their seaward headings, we released turtles offshore during unusual weather conditions when waves moved in atypical directions. Hatchlings swam into approaching waves in all experiments, even when doing so resulted in orientation back towards land. These data suggest that green turtle hatchlings normally maintain seaward headings early in the offshore migration by using wave propagation direction as an orientation cue. Because waves and swells reliably move towards shore in shallow coastal areas, swimming into waves usually results in movement towards the open sea.

The physiological mechanisms that underlie wave detection by sea turtle hatchlings are not known. Calculations indicate that, at the depth at which hatchlings swim, accelerations produced beneath typical waves and swells along the Florida coast are sufficient to be detected by the vertebrate inner ear. We therefore hypothesize that hatchlings determine wave direction while under water by monitoring the sequence of horizontal and vertical accelerations that occur as waves pass above.
Sexual Maturity Can Double Heart Mass and Cardiac Power Output in Male Rainbow Trout
Authors: Franklin Craig E. , Davie Peter S.
Published: April 2021

Mature male rainbow trout have significantly higher relative ventricle masses (RVM, ventricle mass as a percentage of body mass) than do immature males or females. Hatchery-reared maturing male trout had a mean RVM of 0.139%, whereas females had an RVM of only 0.074%. Moreover, as males matured and their testes grew from 0.07 to 3.92% of body mass, RVM more than doubled. In female trout no such heart growth occurred; RVM remained unchanged during the period of ovary growth.

Cardiac performance was assessed using an in situ perfused heart preparation. Mature male trout have larger ventricles and could generate significantly greater maximum cardiac power output per kilogram body mass than could immature males or females. This enhanced cardiac performance by the mature males was attributable to delivery of greater cardiac outputs (through larger stroke volumes) and an increased ability of the heart to work against higher output pressures. Power output per gram ventricle mass was similar in both sexes.
Regional Specialization for Control of Ocular Movements in the Compound Eyes of a Stomatopod Crustacean
Authors: Cronin Thomas W. , Yan Hong Y. , Bidle Kay D.
Published: April 2021

Regional specialization within the triple compound eyes of the gonodactyloid stomatopod Gonodactylus oerstedii (Hansen) was studied by examining how ocular tracking of a small target was affected after occluding vision in particular ommatidial regions with black enamel paint. Complete occlusion of one eye did not prevent the other eye from tracking, indicating that the two eyes act somewhat independently. However, following such treatment, the angular extent over which the seeing eye moved while tracking was reduced. An eye was able to continue tracking a moving target even after occlusion of the anterior tip or after painting over all of its posterior surface except the anterior tip (restricting the visual field to a patch about 40° in diameter). Similarly, occlusion of only the midband, the medial half or the lateral half of an eye did not prevent tracking. Tracking was also possible, although with decreased amplitude, when either the dorsal or the ventral hemisphere was occluded. However, when both the dorsal and ventral hemispheres were occluded, leaving only the midband for vision, the ability of an eye to track was abolished. A computer model was used to investigate whether the midband alone had the potential to direct tracking in our experiments. The model’s output predicts that, in spite of its restricted field of view, if the midband is oriented within 20° of the horizontal, an eye could track using the midband alone. Conditions favoring such potential tracking occurred in our experiments, but neither tracking nor targetting movements were observed. We conclude that ommatidia of the dorsal and ventral hemispheres of each compound eye are essential for ocular tracking in G. oerstedii. The midband appears to play no major role in this activity.
The Effect of Brain Homogenates on Directly Measured Water Fluxes Through the Pronotum of Periplaneta Americana
Authors: Machin J. , Kestler P. , Lampert G. J.
Published: April 2021

Measurements of tritiated water (THO) efflux using a cup, ventilated with dry air, attached to the pronotum of Periplaneta, have been used to obtain unambiguous measurements of the permeability of this structure. Permeability values were 53% of those determined gravimetrically. Our results support the proposal that cockroach cuticle permeability is hormonally controlled, to the extent that compounds extracted from the brain have been shown to be capable of inducing permeability change over relatively short periods. Fresh brain homogenate injections from hydrated donors produced a 28% increase in pronotal permeability in 5 h, rising to 46% the day after. Injections of saline or of fresh brain extracts from dehydrated and normally hydrated cockroaches had no effect. However, previously frozen brain homogenates, from donors at all hydration levels, significantly increased pronotal permeability the day following injection.

The capacity of the pronotum to undergo increases in permeability over relatively short periods was also evident in other experiments. THO permeabilities of excised pronotal discs (5.16×10−10±0.31×10−ll) m s−1) were an order of magnitude higher than those of intact pronota (0.49× 10−10 ±0.06×10−10 ms−1). In vivo permeability of pronota of accidentally injured cockroaches was significantly higher than that of uninjured animals, even though the pronota themselves were not damaged.

We argue that the observed changes in cuticle permeability are too small primarily to serve osmoregulatory functions. We suggest, instead, that the changes might be associated with the control of secondary processes in which the cuticle is involved and which unavoidably promote water loss.
Evidence for a conserved 95–120 KDA subunit associated with and essential for activity of V-ATPases
Authors: Manolson Morris F. , Proteau Denys , Jones Elizabeth W.
Published: April 2021

Vacuoles purified from Saccharomyces cerevisiae bearing the vphl-1 mutation had no detectable bafilomycin-sensitive ATPase activity or ATP-dependent proton pumping. Furthermore, the vacuolar H+-ATPase (V-ATPase) nucleotide binding subunits were no longer associated with vacuolar membranes yet were present at wild-type levels in yeast whole-cell extracts. The VPH1 gene was cloned by screening a λgtl 1 expression library with antibodies directed against a 95 kDa vacuolar integral membrane protein and independently cloned by complementation of the vphl-1 mutation. Deletion disruption of the VPH1 gene revealed that the VPH1 gene is required for vacuolar H+-ATPase assembly and vacuolar acidification but is not essential for cell viability or for targeting and maturation of vacuolar proteases. VPH1 encodes a predicted polypeptide of 840 amino acid residues (95.6 kDa) with putative membrane-spanning regions. Cell fractionation and immunodetection demonstrate that Vphlp is a vacuolar integral membrane protein that co-purifies with V-ATPase activity. Vphlp has 42% identity to the 116 kDa polypeptide of the rat clathrin-coated vesicles/synaptic vesicle proton pump, 42% identity to the TJ6 mouse immune suppressor factor, 42% identity to the Caenorhabditis elegans proton pump homologue and 54% identity to the predicted polypeptide encoded by the yeast gene STV1 (Similar To Y.PH1, identified as an open reading frame next to the BUB2 gene).
Structure, function and regulation of the coated vesicle V-ATPase
Authors: Forgac Michael
Published: April 2021

The coated vesicle V-ATPase plays an important role in both receptor-mediated endocytosis and intracellular membrane traffic by providing the acidic environment required for ligand-receptor dissociation and receptor recycling. The coated vesicle V-ATPase is a macromolecular complex of relative molecular mass 750000 composed of nine subunits arranged in two structural domains. The peripheral V1 domain, which has a relative molecular mass of 500000, has the subunit structure 733583401341331 and possesses all the nucleotide binding sites of the V-ATPase. The integral Vo domain of relative molecular mass 250000 has a subunit composition of 1001381191176 and possesses the pathway for proton conduction across the membrane. Reassembly studies have allowed us to probe the role of specific subunits in the V-ATPase complex while chemical labeling studies have allowed us to identify specific residues which play a critical role in catalysis. From both structural analysis and sequence homology, the vacuolar-type H+-ATPases resemble the F-type H+-ATPases. Unlike the F1 and F0 domains of the F-type ATPases, however, the V1 and Vo domains do not appear to function independently. The possible relevance of these observations to the regulation of vacuolar acidification is discussed.
V-ATPases in phagocytic cells
Authors: Grinstein S. , Nanda A. , Lukacs G. , Rotstein O.
Published: April 2021

V-ATPases in phagocytic cells are known to mediate the acidification of most intracellular organelles. Proton-pump-mediated acidification of these organellar compartments is vital to numerous cell processes, including receptor recycling, protein processing and sorting and microbial degradation. Recent studies have suggested a role for V-ATPases in cytoplasmic pH homeostasis. The present discussion will review the current knowledge regarding the presence of V-ATPases in both the plasmalemmal and organellar membranes of phagocytic cells, the regulation of proton pump activity in these locations and the functional significance of pump-mediated proton translocation.
Polarized targeting of V-ATPase in kidney epithelial cells
Authors: Brown Dennis , Sabolic Ivan , Gluck Stephen
Published: April 2021

The membrane-associated V-ATPase that plays an important role in the regulation of acid-base balance by the kidney is a multisubunit enzyme that is densely packed into specialized membrane domains in intercalated cells. Intercalated cells can be separated into at least two subtypes, A-cells and B-cells, based on their morphological features, the distribution of V-ATPase, and the presence or absence of a basolateral chloride/bicarbonate anion exchanger (AE1) exclusively in B-cells. A-cells secrete protons into the tubule lumen, whereas B-cells secrete bicarbonate. The relative amounts of V-ATPase and AE1 in the plasma membranes of A-and B-cells are modulated under different acid-base conditions and provide a sensitive means by which urinary acidification can be controlled. The mechanisms governing the movement of acid-base transporting proteins between intracellular vesicles and the plasma membrane are under investigation. The microtubular apparatus of the cell is involved in maintaining both apical and basolateral polarity of the enzyme, and different isoforms of V-ATPase subunits may also be involved in the selective targeting of V-ATPase to different membrane domains.
The insect V-ATPase, a plasma membrane proton pump energizing secondary active transport: molecular analysis of electrogenic potassium transport in the tobacco hornworm midgut
Authors: Wieczorek Helmut
Published: April 2021

Goblet cell apical membranes in the larval midgut of Manduca sexta are the site of active and electrogenic K+ secretion. They possess a vacuolar-type ATPase which, in its immunopurified form, consists of at least nine polypeptides. cDNAs for the A and B subunits screened by monoclonal antibodies to the A subunit of the Manduca V-ATPase or by hybridisation with a cDNA probe for a plant V-ATPase B subunit have been cloned and sequenced. There is a high degree of identity to the sequences of the respective subunits of other V-ATPases.

The M. sexta plasma membrane V-ATPase is an electrogenic proton pump which energizes, by the electrical component of the proton-motive force, electrogenic K+/nH+ antiport, resulting in net electrogenic K+ secretion. Since the midgut lacks a Na+/K+-ATPase, all solute fluxes in this epithelium seem to be energized by the V-ATPase. Thus, the midgut provides an alternative to the classical concept of animal plasma membrane energization by the Na+-motive force generated by the Na+/K+-ATPase.
The insect V-ATPase, a plasma membrane proton pump energizing secondary active transport: immunological evidence for the occurrence of a V-ATPase in insect ion-transporting epithelia
Authors: Klein Ulla
Published: April 2021

Active electrogenic K+ transport in insects serves as the energy source for secretion or absorption in gastrointestinal epithelia or for the receptor current in sensory epithelia. In the larval midgut of the tobacco hornworm Manduca sexta, a vacuolar-type proton pump (V-ATPase) and a K+/nH+ antiport represent the functional elements of the potassium pump. Several immunological findings support the hypothesis that active K+ transport in other insect epithelia may also be energized by a V-ATPase. In immunoblots, crude homogenates of sensilla-rich antennae and Malpighian tubules of M. sexta cross reacted with an immune serum directed to the purified plasma membrane V-ATPase from the midgut; the M. sexta midgut V-ATPase cross reacted with polyclonal antibodies to endomembrane V-ATPases from xenic origin. In immunocytochemical investigations of larvae of M. sexta and adults of Antheraea pernyi, monoclonal antibodies to defined subunits of the purified midgut V-ATPase or polyclonal antibodies to xenic endomembrane V-ATPase labelled the sites of active K+ transport: the goblet cell apical membrane in the midgut, the brush border of Malpighian tubules and the apical projections of the auxiliary cells in antennal sensilla. The functional mechanism of a primary H+-pumping V-ATPase and a secondary H+-dependent K+ transport postulated for K+-transporting insect epithelia may be further applicable to active Na+ or Cl− transport and would provide a unifying concept for all ouabain-insensitive electrogenic ion transport in insects. The findings from the midgut investigations, however, are the first instance in which a V-ATPase provides an alternative to the Na+/K+-ATPase in energizing secondary active transport in animal plasma membranes.
pH gradients in lepidopteran midgut
Authors: Dow Julian A. T.
Published: April 2021

Lepidopteran larvae demonstrate several remarkable specialisations of the alimentary canal: the most active epithelial transport known; a unique cell type, called a goblet cell; and the highest pH values known to be generated by a biological system. The electrogenic K+ pump in midgut is now known to be energised by a H+-pumping V-ATPase, and net alkali metal transport is achieved by linking it to a nH+/alkali metal exchanger, which recycles H+ into the cytoplasm.

Generation of high luminal pH is modelled as a passive (Nernstian) distribution of protons in the electrical field generated by the V-type ATPase. Electrode impalements show that the potential difference across the goblet cavity membrane is extremely high. Measurements of pH gradients generated in vitro confirm that the midgut itself generates such a gradient, that this process relies on metabolic energy, and that the differential ability of midgut subregions to perform acid-base transport maps to their differing morphologies and to the pH profiles observed along the gut in vivo.

During larval/larval moults, K+ transport is suppressed. The transepithelial potential difference (PD) across the gut collapses and recovers in phase with the loss and recovery of the gut pH gradient, and with tissue V-ATPase activity, confirming that these processes are intimately linked.

Acridine Orange partitions into acidic compartments and might be expected to be concentrated in goblet cavities, as these are the compartments toward which the V-ATPase pumps protons. However, under normal conditions, Acridine Orange is excluded from the cavities. Red metachromasia of the cavities (implying low pH) is only observed when the ion transport status of the tissue is compromised. It thus seems likely that, under physiological conditions, K+/H+ exchange is tight enough to produce a neutral or alkaline, rather than acidic, cavity.

Molecular analysis of the 16000 Mr subunit from Manduca midgut reveals it to be closely similar to other known 16000Mr sequences, particularly that from Drosophila brain. It is thus likely to be a true H+ channel, rather than one modified for K+ transport.

The cavity can be modelled in two ways: (i) to isolate the site of proton equilibration electrically from the main gut lumen, and thus allow larger pH gradients to develop, or (ii) to buffer the V-ATPase from the alkaline pH in the gut lumen, which would otherwise destroy the gradient driving the exchange of H+ for alkali metal cations. The first model would predict a high cavity pH, whereas the second would predict a near neutral pH and would imply a non-cavity route for transport of base equivalents. Work with both pH-sensitive dyes and pH-sensitive electrodes so far tends to support the second model.
A plant biochemist’s view of H+-ATPases and ATP synthases
Authors: Mccarty Richard E.
Published: April 2021

My twenty-five year fascination with membrane ATPases grew out of my experiences in the laboratories of André Jagendorf and Efraim Racker. André introduced me to photosynthetic phosphorylation and Ef, to whose memory this article is dedicated, convinced me that ATPases had much to do with ATP synthesis.
Vacuolar ATpase of Neurospora Crassa: Electron Microscopy, Gene Characterization and Gene Inactivation/Mutation
Authors: Bowman Barry J. , Dschida William J. , Bowman Emma Jean
Published: April 2021

We are using three approaches to investigate the vacuolar ATPase, V-ATPase, from Neurospora crassa. (1) Examination in the electron microscope shows the enzyme has a ‘ball and stalk’ structure like the F-type ATPases. However, the vacuolar ATPase is significantly larger, has a prominent cleft in the head sector, and has extra components associated with the stalk and membrane sectors. (2) Genes encoding three of the major subunits of the vacuolar ATPase and the homologous subunits of the mitochondrial F-ATPase have been isolated. The exon/intron structures of the genes have been analyzed and the chromosomal locations have been determined. Two of the vacuolar ATPase genes map very close to each other, suggesting the possibility of a cluster of ATPase genes. (3) The function of the ATPase is being investigated by isolating strains with altered or inactivated ATPase. We are characterizing strains that are resistant to bafilomycin A1, a potent and specific inhibitor of the vacuolar ATPase. Initial attempts to inactivate a vacuolar ATPase gene indicate that the enzyme may be essential for growth.
Identification, Characterisation and In Vitro Reconstruction of an Interneuronal Network of the Snail Helisoma Trivolvis
Authors: Syed N. I. , Roger I. , Ridgway R. L. , Bauce L. G. , Lukowiak K. , Bulloch A. G. M.
Published: April 2021

We describe three interneurones and their follower cells in the central ganglionic ring of Helisoma trivolvis. The largest neurone on the dorsal surface of the left pedal ganglion is shown to be an interneurone that contains dopamine and makes monosynaptic connections with a large number of follower cells in the visceral and left parietal ganglia. This neurone is designated as left pedal dorsal 1 (LPeD1). Another giant neurone is located on the dorsal surface of the right pedal ganglion. Although the position and morphology of this cell, designated right pedal dorsal 1 (RPeD1), are similar to those of LPeD1, it contains serotonin rather than dopamine. This neurone was found to synapse only on LPeD1, no other follower cells have so far been discovered. The connections between LPeD1 and RPeD1 are mutually inhibitory. A small FMRFamide-immunoreactive neurone, identified here as visceral dorsal 4 (VD4), is located on the dorsal surface of the visceral ganglion. This neurone has a large number of follower cells throughout the central ganglionic ring. Among these follower cells are LPeD1 and RPeD1. The transmitter utilized by VD4 at these synapses is probably FMRFamide. In addition, VD4 receives excitatory inputs from LPeD1 that appear to be chemical and monosynaptic. To test further the monosynaptic and specific nature of the connections within the network, the three interneurones were isolated and cultured in vitro. In these circumstances, the three neurones extended neurites and formed synapses which, with one exception (occasional electrical coupling between LPeD1 and RPeD1), were of similar type to those observed invivo. The identification and characterization of these three interneurones and their follower cells should greatly facilitate future studies of the Helisoma trivolvis nervous system. Furthermore, the possibility that this three-cell network can be reconstructed in vitro should aid our understanding of the mechanisms underlying synapse formation and neuronal plasticity.
Electrophysiological Evidence for the Modulation of Acetylcholine Release by Endogenous Acetylcholine in the Cockroach Central Nervous System
Authors: Corronc H. Le , Hue B.
Published: April 2021

Biochemical studies of the central nervous system (CNS) of locusts (Breer and Knipper, 1984; Knipper and Breer, 1988) have provided evidence for a muscarinic negative feedback mechanism in which muscarinic antagonists and agonists, respectively, enhance and decrease the acetylcholine (ACh) output. More recently, this inhibitory action of presynaptic muscarinic acetylcholine receptors (mAChrs) has been demonstrated in cockroach (Hue et al. 1989; Le Corronc et al. 1991) and in tobacco hornworm (Trimmer and Weeks, 1989) using electrophysiological methods. However, in insects, most experiments have not been performed under physiological conditions but in the presence of acetylcholinesterase inhibitors or exogenous agonists. The aim of this study was to determine whether the release of ACh at a central synapse in the cockroach, Periplaneta americana, could be modulated by endogenous ACh acting on presynaptic muscarinic receptors.
Indications for Two Bioactive Principles in the Corpuscles of Stannius
Authors: Verbost P. M. , Butkus A. , Willems P. , Bonga S. E. Wendelaar
Published: April 2021

For a long time it was thought that the corpuscles of Stannius (CS) of holostean and teleostean fishes produce a single hormone reducing Ca2+ influx from the water via the gills. We here present data showing that two separate bioactive principles are present in the CS: stanniocalcin (STC), a 56kDa glycoprotein, and teleocalcin (TC), a 3kDa glycopeptide. STC indeed inhibits Ca2+ influx (as reported many times before) but does not affect the Ca2+-and Mg2+-dependent phosphatase activity located in the gill plasma membrane. TC does not affect Ca2+ influx but inhibits the Ca2+-and Mg2+-dependent phosphatase activity. Thus, the Ca2+-and Mg2+-dependent phosphatase activity appears not to be involved in transbranchial Ca2+ transport. We conclude that STC is the pivotal calcium-regulating hormone in fish and that TC has an as yet unidentified role in gill physiology through its phosphatase-reducing activity.
Effect of Adenosine on Glucose Metabolism of Rana Ridibunda Erythrocytes
Authors: Kaloyianni Martha , Michaelidis Basile , Moutou Katerina
Published: April 2021

The effects of adenosine and inosine on Rana ridibunda erythrocyte metabolism were studied. Adenosine can be metabolized by Rana ridibunda erythrocytes as a carbon source for glycolysis to maintain ATP levels, whereas neither inosine nor glucose could maintain ATP levels. The rate of lactate production was maximal (2.89 μmolml-1 redcell h-1) in the presence of adenosine together with glucose compared with that in the presence of glucose or adenosine alone. Inosine sustained a similar rate of lactate production as did glucose. The concentrations of phosphorylated hexoses increased during 4h of incubation in the presence of adenosine either with or without glucose. The presence of sodium iodoacetate accelerated the loss of ATP; furthermore, levels of lactate and pyruvate were significantly reduced in the presence of either adenosine or inosine. Ouabain strongly inhibited ATP and lactate formation in the presence of adenosine, whereas the levels of ATP and lactate were almost unchanged in the presence of inosine. An inhibitor of adenosine transport, dipyridamole, impeded the increases in erythrocyte lactate and ATP concentration in the presence of adenosine but did not modify the effects of inosine.
The Gleaning Attacks of the Northern Long-Eared Bat, Myotis Septentrionalis, Are Relatively Inaudible to Moths
Authors: Faure Paul A. , Fullard James H. , Dawson Jeff W.
Published: April 2021

This study empirically tests the prediction that the echolocation calls of gleaning insectivorous bats (short duration, high frequency, low intensity) are acoustically mismatched to the ears of noctuid moths and are less detectable than those of aerially hawking bats. We recorded auditory receptor cell action potentials elicited in underwing moths (Catocala spp.) by echolocation calls emitted during gleaning attacks by Myotis septentrionalis (the northern long-eared bat) and during flights by the aerial hawker Myotis lucifugus (the little brown bat). The moth ear responds inconsistently and with fewer action potentials to the echolocation calls emitted by the gleaner, a situation that worsened when the moth’s ear was covered by its wing (mimicking a moth resting on a surface). Calls emitted by the aerial-hawking bat elicited a significantly stronger spiking response from the moth ear. Moths with their ears covered by their wings maintained their relative hearing sensitivity at their best frequency range, the range used by most aerial insectivorous bats, but showed a pronounced deafness in the frequency range typically employed by gleaning bats. Our results (1) support the prediction that the echolocation calls of gleaners are acoustically inconspicuous to the ears of moths (and presumably other nocturnal tympanate insects), leaving the moths particularly vulnerable to predation, and (2) suggest that gleaners gain a foraging advantage against eared prey.
Cardiac regulation by endogenous small cardioactive peptides and FMRFamide-related peptides in the snail Helix aspersa
Authors: Lesser W. , Greenberg M. J.
Published: April 2021

The putative heptapeptide pQDPFLRIamide, previously known only from its appearance in a cDNA clone from Helix aspersa, was isolated from circumoesophageal ganglia extracts and sequenced.

Extracts of several tissues were fractionated by high performance liquid chromatography and the fractions analysed by radioimmunoassay (RIA). The results indicate that ten cardioactive peptides, FMRFamide, FLRFamide, six FMRFamide-related heptapeptides and two nonapeptide analogues of the small cardioactive peptides (SCPs), are present in the circumoesophageal ganglia (brain), the visceral nerve trunk (from which the cardiac nerve branches) and the aorta. The heart contains the two tetrapeptides, FMRFamide and FLRFamide, and the SCPs, but the heptapeptides were completely undetectable in this organ. The levels of tetrapeptide were high enough to allow their calcium-dependent release from the heart to be demonstrated. Immunohistochemistry revealed a diffuse SCP and FMRFamidergic innervation distributed throughout the heart. These data support the idea that, although the ten peptides are probably acting as neurotransmitters throughout most of the cardiovascular system, the heptapeptides probably also have a neurohormonal rôle on the Helix aspersa heart itself. The binding affinities of the various antisera used in these studies were examined in competitive RIAs, in non-competitive dot-blot assays or in both.
Muscle Performance in Hovering Hummingbirds
Authors: Wells Dominic J.
Published: April 2021

The flight energetics of hovering hummingbirds was examined by simultaneous collection of metabolic and kinematic data followed by a morphometric analysis of wing characteristics. These data were then used for an aerodynamic analysis of the power output required to generate sufficient lift; this, together with the metabolic power input, allowed an estimate of the flight efficiency. The use of two closely related species demonstrated common design features despite a marked difference in wing loading. Considerations of the inertial power costs strongly suggest that hummingbirds are able to store kinetic energy elastically during deceleration of the wing stroke. This analysis predicts that hummingbirds hover with a muscle power output close to 100–120 W kg−1 at 9–11% mechanochemical efficiency.
The Effect of Ionic Copper on the Oxygen Consumption of Gammarus Pulex and Polycelis Nigra
Authors: Erichsen Jones J. R.
Published: April 2021

The suggestion has been put forward that the oligodynamic action of certain heavy metals is the result of the destruction or inactivation of substances essential for cellular respiration. In a study of the effect of copper sulphate solutions on the oxygen consumption of Polycelis nigra it is found that solutions of concentration 0·001–0·001 N, fatal in 2 hr. or less, induce a marked preliminary rise in the respiration rate ; this appears to be due to the inhibition of ciliary locomotion and increased muscular activity. A similar increase is produced by increasing the activity of the animals by mechanical means, or by a muscle stimulant (barium chloride). Over the latter part of the survival time the respiration rate drops rapidly and disintegration of the animals begins when it falls to about 60 % of the normal value. A 0·0004 N copper sulphate solution does not inhibit ciliary locomotion, does not stimulate muscular activity, and the oxygen consumption undergoes a steady decline. A 0·0002 N NaCN solution rapidly depresses the respiration rate to less than 20 % of the normal value, but is not fatal, the animals surviving over 4 days. Hydrogen ions, at the concentrations resulting from the hydrolysis of the salt, have no appreciable effect on the oxygen consumption, but at lethal concentrations (pH 2·6, 2·8) effect a speedy depression. The results suggest that the depression of respiration rate observed is insufficient to account for the death of the animals, and is no more than a symptom of the toxic process.

A similar general result was obtained in experiments with silver nitrate and mercuric chloride, and also in experiments on the comparative effect of copper sulphate and sodium cyanide solutions on the oxygen consumption of Gammarus pulex.
The Role of the Pituitary and the Thyroid in the Development of Teleosts
Authors: Landgrebe F. W.
Published: April 2021

There is no satisfactory evidence for regarding the organ of Syrski as the male gonad of Anguilla. Silvering of the eel, salmon and trout is independent of gonad development and cannot therefore be regarded as a ‘breeding dress ‘ Injection of either pregnancy urine, ox anterior lobe extracts, pig anterior lobe extracts and thyroid extracts, as also pituitary homeo-implantation. were all without effect on the gonads of eels treated in this way. Ox anterior lobe extracts produced premature smoltification in Salmo salar, had no visible effect on S. trutta or on Anguilla vulgaris, and did not affect the gonads in either species. Injection of thyroid extracts produced silvering in salmon and brown trout but had no effect on the eel. After two months’ treatment with thyroid extract brown trout are externally indistinguishable from sea trout.
The Action of Potassium on Echinoderm, Molluscan and Crustacean Muscle
Authors: Wells G. P.
Published: April 2021

Some years ago, the writer published an account of the action of potassium on the crops of Aplysia and Helix, and the hearts of Maia and Homarus (Wells, 1928). It was pointed out that the preparations used show a general resemblance in their responses to changes in potassium concentration, although they include plain and striped muscle, and are taken from molluscs and crustaceans. Since that time he has made similar experiments on other preparations. The results are now described and discussed from a comparative standpoint. It appears that potassium—in contrast to calcium, which has the most diverse effects—-produces essentially similar responses in muscles from animals of various different phyla, and of quite different histological and functional nature. The suggestion is made that all types of rhythmic muscle are essentially alike in their responses to comparable changes in the potassium concentration of the environment.
Chromatic Behaviour of Scyllium Canicula
Authors: Waring H. , Landgrebe F. W. , Bruce J. R.
Published: April 2021

Dermal melanophores of intact Scyllium equilibrate at μ = 4·9 and μ — 1·4 respectively on black and white background with overhead illumination. They equilibrate at μ = 2·9 in complete darkness. Normal responses are of the ‘slow’ type. Expanded melanophores in skin strips immersed in saline contract in 30 min. In pituitary extract they expand in 60 min. So we may interpret the slow responses of intact fish as indices of the slow rise and fall of co-ordinating hormones in circulation. The time relations of normal responses are not consistent with a one-hormone hypothesis. Thyroids removed from animals hypophysectomized a month previously afford no evidence for pituitary control of thyroid activity.
Coupled Versus Uncoupled Functional Systems: Motor Plasticity In The Queen Triggerfish Balistes Vetula
Authors: Wainwright Peter C. , Turingan Ralph G.
Published: April 2021

Teleost fishes typically capture prey with the oral jaws and perform most types of prey-processing behavior with the pharyngeal jaw apparatus. In these fishes, the motor patterns associated with the different stages of feeding are quite distinct, and fish can modify muscle activity patterns when feeding on different prey. We examined motor pattern variation in the queen triggerfish, Balistes vetula, a versatile predator that both captures and processes prey with its oral jaws. During feeding on three prey that differed in hardness and elusiveness, three distinct patterns of behavior could be identified on the basis of patterns of muscle activity: prey capture, buccal manipulation and blowing. During prey capture by suction feeding, the retractor arcus palatini muscle (RAP) commenced activity before the levator operculi muscle (LOP). In both buccal manipulation and blowing, the RAP began activity well after the onset of activity in the LOP. Both prey capture and buccal manipulation motor patterns varied when fish fed on different prey. When capturing hard-shelled and non-elusive prey, B. vetula did not employ suction feeding but, instead, the fish directly bit parts of its prey. The motor pattern exhibited during direct biting to capture prey was different from that during suction feeding, but was indistinguishable from the pattern seen during the repeated cycles of buccal manipulation. Harder prey elicited significantly longer bursts of activity in the jaw adductor muscles than did soft prey. In spite of the involvement of the oral jaws in virtually all stages of feeding, B. vetula shows levels of variation between patterns of behavior and types of prey characteristic of previously studied teleost fishes. Thus, the coupling of capture and processing behavior patterns in the repertoire of the oral jaws does not appear to constrain the behavioral versatility of this species.
Behaviour of Dogs During Olfactory Tracking
Authors: Thesen Aud , Steen Johan B. , Døving Kjell B.
Published: April 2021

The ability to detect the direction of a track is of vital importance to animals of prey and is retained in many modern breeds of dogs. To study this ability, four trained German shepherd tracking dogs, equipped with head microphones to transmit sniffing activity, were video-monitored after being brought at right angles to a track where the position of each footprint was known. Three phases could be recognized in the dogs’ behaviour: (1) an initial searching phase, during which the dog tried to find the track, (2) a deciding phase, during which it tried to determine the direction of the track and (3) a tracking phase, in which it followed the track. During ten tests on 20-min-old tracks on grass, and ten tests on 3-min-old tracks on concrete, the dogs always followed the track in the correct direction (i.e. in the direction the track was leading). During the deciding phase the dogs moved at half the speed and their periods of sniffing lasted three times as long as during the other two phases.

The deciding phase lasted 3–5s, while the dogs sniffed at 2–5 footprints. The dogs’ ability to determine track direction in this time must rely on accurate methods of sampling air and a remarkable sensitivity for certain substances.
Effects of Ammonia on Survival, Swimming and Activities of Enzymes of Nitrogen Metabolism in the Lake Magadi Tilapia Oreochromis Alcalicus Grahami
Authors: Walsh Patrick J. , Bergman Harold L. , Narahara Annie , Wood Chris M. , Wright Patricia A. , Randall David J. , Maina J. N. , Laurent Pierre
Published: April 2021

The Lake Magadi tilapia, Oreochromis alcalicus grahami, is remarkable among teleosts in that it flourishes under extremely well-buffered alkaline water conditions (pH10, 180mmol l−1) at temperatures of 30–40°C (Wood et al. 1989). As expected from current models in teleosts, ammonia excretion into such water would be difficult at best (Wood, 1993). Part of the survival strategy of the Lake Magadi tilapia is that it has a complete ornithine–urea cycle (O–UC) in the liver and excretes virtually all of its waste nitrogen as urea (Randall et al. 1989). Ammonia toxicity in ammoniotelic teleosts has been studied extensively, and typical values for unionized ammonia (NH3) 96h LC 50 (the concentration at which half of test subjects die after 96h) are well below 100 μmol l−1 (Haywood, 1983; Thurston et al. 1983a,b; Campbell, 1991). Surprisingly, no ammonia LC50 values are available for ureogenic teleost fish, and one would predict that fish synthesizing and excreting urea for whatever purpose would have higher LC50 values than their ammoniotelic counterparts. Additionally, since ammonia exposure has been implicated in the functional response of urea excretion in the Lake Magadi tilapia (Wood et al. 1989) and another ureogenic teleost (the gulf toadfish Opsanus beta) (Walsh et al. 1990), we reasoned that ammonia exposure in the Lake Magadi tilapia might reveal insights into the biochemical regulation of the O–UC in this species; in particular that it might induce enzyme activity. We report here that the Lake Magadi tilapia has a rather high ammonia LC50 compared to values for other teleosts, but that short-term ammonia exposure has very limited effects on the activities of the enzymes of nitrogen metabolism and on swimming performance.
Control of Body Height in a Stick Insect Walking on a Treadwheel
Authors: Cruse H. , Schmitz J. , Braun U. , Schweins A.
Published: April 2021

The properties of the system that controls the distance between body and ground was investigated in the stick insect Carausius morosus. The insect walked on a lightweight double treadwheel under open-loop or closed-loop conditions. The open-loop investigations show that the dynamic behaviour of the height-control system in the walking animal can be described in terms of a simple proportional system with negligible dynamic properties, and it is therefore much simpler than the height-control system in the standing animal. Under open-loop conditions, we found no coupling between contralateral or ipsilateral legs. This agrees with the findings on standing animals. The force–height characteristic shows two ranges, in each of which the system exhibits a linear relationship but a different slope. Under closed-loop conditions, the force–height characteristic shows the same two linear ranges, but the slopes are greater than under open-loop conditions. Because the height controller of each leg can be considered to act like a spring, this result means that under closed-loop conditions the controller is stiffer than it is under open-loop conditions.
Hormonal Control of Transmitter Plasticity in Insect Peptidergic Neurons: II. Steroid Control of the Up-Regulation of Bursicon Expression
Authors: Tublitz N. J. , Loi P. K.
Published: April 2021

Each abdominal ganglion of the central nervous system of the tobacco hawkmoth, Manduca sexta, contains four individually identified lateral neurosecretory cells (LNCs) that undergo a postembryonic transmitter switch in vivo. In the embryonic and caterpillar stages, the primary LNC transmitter is cardioacceleratory peptide 2 (CAP2), a myoregulatory peptide. During metamorphosis, these cells stop expressing CAP2 and instead produce bursicon, a classic insect peptide hormone responsible for cuticular tanning. We have previously reported that this transmitter plasticity is under the control of the insect steroid hormone 20-hydroxyecdysone (20-HE), which surges twice during the last larval instar. In that report we showed that the CAP2 decline is indirectly regulated by the first 20-HE rise, the commitment pulse (CP). Here we provide evidence that the rise in bursicon levels in the LNCs is directly triggered by the second 20-HE surge, the prepupal peak (PP). We performed several experimental manipulations that exposed LNCs to the PP without the CP; cells treated in this manner exhibited a significant rise in bursicon content. In contrast, bursicon levels remained unchanged in those LNCs exposed only to the CP. Exposure to the PP triggered a precocious increase in bursicon expression in LNCs from the penultimate larval stage. Increased bursicon levels in the LNCs were also induced by direct infusion of 20-HE. Taken together, the results of these experiments suggest that the rise in bursicon in the LNCs during metamorphosis is due to the direct action of the PP on the LNCs. Thus, the two 20-HE surges combine to regulate the CAP2-to-bursicon switch in the LNCs, the first acting indirectly to cause a decline in CAP2 levels and the second triggering a rise in bursicon expression, possibly by a direct action on the LNCs.
Clock-Shift Experiments with Migratory Yellow-Faced Honeyeaters, Lichenostomus Chrysops (Meliphagidae), an Australian Day-Migrating Bird
Authors: Munro Ursula , Wiltschko Roswitha
Published: April 2021

The behaviour of an Australian day migrant, the yellow-faced honeyeater Lichenostomus chrysops, was studied in order to assess the role of the sun in migratory orientation. During autumn migration, all tests took place under a sunny sky; birds were tested while living in the natural photoperiod (control) and with their internal clock shifted 4h fast and 4h slow. In spring, all birds were shifted 3h fast; tests in overcast conditions, with the birds relying on their magnetic compass, served as controls. In control tests in both seasons, the birds preferred directions corresponding to those observed in the wild. When tested under sunny conditions with their internal clock shifted, the birds changed their directional tendencies. However, their preferred directions were different from those expected if a time-compensating sun compass was being used. After about 6 days, the shifted birds’ directions were no longer different from the control direction. This behaviour argues against a major role of the sun compass in the orientation of day migrants. The dramatic changes of the sun’s arc with geographic latitute might cause day-migrating birds to prefer a more constant orientation cue, such as the geomagnetic field. The initial response to the clock-shift might have occurred because the birds were confused by the conflicting information from solar and magnetic cues. This suggests that the sun is usually used as a secondary cue in combination with the magnetic field.