bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Humidity Behaviour of the Mealworm Beetle, Tenebrio Molitor L
Authors: Pielou D. P. 
Published: April 2021

ABSTRACT
The existence of sensillae sensitive to humidity has frequently been surmised, but there is no experimental evidence on their form or position in insects. Necheles (1925) suggested that the antennal hairs of the mosquito might be sensitive to humidity; Thomson (1938) made an attempt to locate the receptors in the mosquito, Culex fatigans, but found the experimental difficulties too great. Kennedy (1937) attempted unsuccessfully to locate the receptors in the locust, Locusta migratoria. Gunn & Cosway (1938) found that humidity behaviour in the cockroach, Blatta orientalis, became irregular when the antennae were infected with a fungus, and they suggested on these grounds that the receptors are located on the antennae. Thus there is no satisfactory evidence on the site of humidity receptors in insects. The problem has also been examined in other terrestrial arthropods. Blumenthal (1935), working on the olfactory sense of spiders, decided that certain organs on the tarsi of the legs are olfactory receptors. As he used water as one of his “odours” and found a reaction to it, he concluded that these organs were also humidity receptors. Gunn (1937) could not locate the humidity receptors in the wood-louse, Porcellio scaber.
The Digestive Enzymes of Some Wood-Boring Beetle Larvae
Authors: Parkin E. A. 
Published: April 2021

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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.