bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lactate metabolism and glucose turnover in the subterranean crustacean Niphargus virei during post-hypoxic recovery
Authors: Hervant F. , Garin D. , Mathieu J. , Freminet A. 
Published: April 2021

ABSTRACT
Glucose and lactate metabolism were studied in a hypoxia-resistant subterranean crustacean, Niphargus virei, using an injection of L-[U-14C]lactate and tracer D-[6-3H]glucose either in normoxic conditions or after a 24 h exposure to severe hypoxic. Post-hypoxic animals (H animals) were compared with two treatment groups of normoxic animals. In the first normoxic group (NLL animals), animals were simultaneously injected with labelled and unlabelled lactate to obtain a lactate load similar to that of H animals. In the second normoxic group (N, control animals), animals were only injected with labelled lactate. During a 24 h recovery period, the incorporation of 14C and 3H into glycogen, lactate, glucose, amino acids, lipids and CO2 was measured.
During recovery, glucose turnover rate was enhanced in H and depressed in NLL compared with N animals. However, when energy expenditure was taken into account, the changes were due only to a reduction of glucose turnover rate by lactate load. It was concluded that gluconeogenesis was not the main source of glyconeogenesis.
Equivalent lactate loading in NLL and H animals resulted in an equivalent enhancement (fivefold) of lactate utilization in both groups when energy expenditure was taken into account. Lactate label incorporation appeared later in glycogen than in glucose, but remained high 24 h after the injection. Since glucose is mainly an extracellular metabolite, this observation may be consistent with the hypothesis of two distinct sites for glycogen restoration in hypogean crustaceans: a gluconeogenic organ (a liver equivalent) and a glyconeogenic organ (a muscle equivalent).
The oxidative pathways of glucose and lactate were depressed in post-hypoxic N. virei and to a lesser extent in the NLL group. Since there is no evidence of marked protein utilization, it is postulated that, during recovery, repayment of the O2 debt relies on an increase in lipid utilization.
During recovery from severe hypoxia or after a lactate load, the subterranean N. virei appeared to implement a strategy of lactate removal quite different from that observed in epigean crustaceans, favouring lactate-supported gluco- and glyconeogenesis and rapid glycogen replenishment instead of rapid lactate removal via oxidative pathways.
High-frequency steering maneuvers mediated by tactile cues: antennal wall-following in the cockroach
Authors: Camhi J. M. , Johnson E. N. 
Published: April 2021

ABSTRACT
Cockroaches (Periplaneta americana) use their antennae to detect a wall and to maintain a constant distance from it as they walk or run along it. The faster they run, the closer they position themselves to the wall. They also use their antennae to detect and follow multiple accordion-like projections in the wall. They can make up to 25 body turns s−1 for short periods during rapid running to follow such wall projections. Each turn apparently involves a change in stepping direction. These turns help to avoid collisions with the outward projections, while keeping the body close to the wall.
Sensory inputs from the flagellum of the antenna, and not from its base, appear to evoke the turns in response to wall projections. These flagellar inputs appear to report the position along the antenna of its contact with the wall and/or the position of the consequent antennal bend. This flagellar information constitutes a one-dimensional sensory map, with location along the map indicating the distance to the wall.
Structure and mechanics of the squid mantle
Authors: MacGillivray Patrick S. , Anderson Erik J. , Wright Glenda M. , Demont M. Edwin 
Published: April 2021

ABSTRACT
The goal of this study was to obtain a complete description of the elastic modulus and hysteresis of the mantle tissue of the squid Loligo pealei over the entire functional region of the mantle. In addition, in vivo strains were measured to allow calculations of the amount of energy stored and returned in each region of the mantle studied, and microscopic analysis of the tissue was carried out with the aim of correlating macroscopic properties with microscopic structure. The results of dynamic tissue tests indicate that mean elastic moduli for each of the 35 mantle positions tested ranged from 5.0×105 to 1.2×106 N m−2. The elastic modulus varied within a narrow range, in no predictable manner. Mean hysteresis values for each position varied from 19.7 % to 27.3 % with no discernible patterns found either around or along the mantle. In vivo mantle strains peaked in the middle (lengthwise) of the mantle and declined towards both ends, and the absolute strains increased with increasing swimming velocity. Energy storage calculations showed that most energy was stored in the middle of the mantle, with an increase in storage with increased swimming velocity. Microscopic tissue analysis found direct correlations between macroscopic properties and microscopic characteristics, and electron microscopical analysis of all three types of intramuscular fibre revealed that all three types are collagenous in nature.
Excretion of thiosulphate, the main detoxification product of sulphide, by the lugworm Arenicola marina L.
Authors: Hauschild Kerstin , Weber Wolf-Michael , Clauss Wolfgang , Grieshaber Manfred K. 
Published: April 2021

ABSTRACT
Thiosulphate, the main sulphide detoxification product, is accumulated in the body fluids of the lugworm Arenicola marina. The aim of this study was to elucidate the fate of thiosulphate. Electrophysiological measurements revealed that the transepithelial resistance of body wall sections was 76±34 Ω cm2 (mean ± S.D., N=14), indicating that the body wall of the lugworm is a leaky tissue in which mainly paracellular transport along cell junctions takes place. The body wall was equally permeable from both sides to thiosulphate, the permeability coefficient of which was 1.31×10−3±0.37×10−3 cm h−1 (mean ± S.D., N=30). No evidence was found for a significant contribution of the gills or the nephridia to thiosulphate permeation. Thiosulphate flux followed the concentration gradient, showing a linear correlation (r=0.997) between permeated and supplied (10–100 mmol l−1) thiosulphate. The permeability of thiosulphate was not sensitive to the presence of various metabolic inhibitors, implicating a permeation process independent of membrane proteins and showing that the lugworm does not need to use energy to dispose of the sulphide detoxification product. The present data suggest a passive permeation of thiosulphate across the body wall of A. marina. In live lugworms, thiosulphate levels in the coelomic fluid and body wall tissue decreased slowly and at similar rates during recovery from sulphide exposure. The decline in thiosulphate levels followed a decreasing double-exponential function. Thiosulphate was not further oxidized to sulphite or sulphate but was excreted into the sea water.
The sarcoplasmic reticulum plays a major role in isometric contraction in atrial muscle of yellowfin tuna
Authors: Shiels H. A. , Freund E. V. , Farrell A. P. , Block B. A. 
Published: April 2021

ABSTRACT
We used an isometric muscle preparation to test the hypothesis that yellowfin tuna Thunnus albacares utilize the intracellular Ca2+ storage sites of the sarcoplasmic reticulum (SR) during routine contractions. Ryanodine (a blocker of SR Ca2+ release) reduced the force of contraction by approximately 50 % and the rates of contraction and relaxation by 60 % in yellowfin tuna atrium. High levels of adrenaline were unable to ameliorate the effects of ryanodine. We conclude that the SR is active in contributing Ca2+ to force development at physiological contraction frequencies. Further, we suggest that, by using intracellular Ca2+ cycling, the yellowfin tuna is able to increase the maximum contraction frequency of its cardiac muscle beyond that of most other fishes.
Structure, fluorescent properties and proposed function in phototaxis of the stigma apparatus in the ciliate Chlamydodon mnemosyne
Authors: Selbach Matthias , Kuhlmann Hans-Werner 
Published: April 2021

ABSTRACT
Chlamydodon mnemosyne, a brackish-water ciliate which feeds on cyanobacteria, is capable of sensing the direction of light. Cells are negatively phototactic in the well-fed state and tend to swim towards the light source when mildly starved. Severely starved cells normally fail to show phototactic responses. An autofluorescent substance, which is present in all life cycle stages, occurs in, or immediately beneath, the plasma membrane of this ciliate. It is located in the anterior left side of a cell, in the same region where mildly starved cells accumulate small orange globules that form a structure known as the stigma. The diameter of the whole area where the autofluorescent substance is located appears to be smaller than the stigma; typically, it consists of two rows of blue-green fluorescence, each row subdivided into 5–10 squares. Since the blue-green autofluorescence is excited by both blue (450–490 nm) and near-ultraviolet (340–380 nm) light, it possibly originates from flavin- and/or pterin-like molecules. We suggest that the autofluorescent substance located in or beneath the plasma membrane of Chlamydodon mnemosyne acts as a photoreceptor pigment in phototaxis and that photo-orientation of this ciliate is triggered by a combined mechanism involving the photoreceptor and either the stigma or a number of light-absorbing food vacuoles as a shading device.
Differential expression of mitochondrial genes between queens and workers during caste determination in the honeybee Apis mellifera
Authors: Corona Miguel , Estrada Enrique , Zurita Mario 
Published: April 2021

ABSTRACT
The nourishment received by female honeybee larvae determines their differentiation into queens or workers. In this study, we report the first molecular analysis of differences that occur between queens and workers during the caste-determination process. RNA-differential display experiments identified a clone that encodes for a gene that is homologous to the nuclear-encoded mitochondrial translation initiation factor (AmIF-2mt). Semi-quantitative analysis by reverse transcriptase/polymerase chain reaction (RT-PCR) throughout honeybee development detected a higher level of expression of this gene in queen larvae than in worker larvae. Analysis of two other genes encoding mitochondrial proteins, cytochrome oxidase subunit 1 (COX-1; mitochondrial-encoded) and cytochrome c (cyt c; nuclear-encoded) also showed differential expression of these two genes between queens and workers. In particular, the cyt c transcript is more abundant in queen larvae and throughout the metamorphosis of the queen. These results indicate that the higher respiratory rate previously documented in queen larvae is accomplished through a higher level of expression of both nuclear- and mitochondrial-encoded genes for mitochondrial proteins.
Evidence for orientation using the e-vector direction of polarised light in the sleepy lizard Tiliqua rugosa
Authors: Freake Michael J. 
Published: April 2021

ABSTRACT
Adult sleepy lizards (Tiliqua rugosa) were trained to orient in a predictable direction under natural sky light in outdoor pens. When tested under clear skies in the late afternoon, without a view of the sun, the lizards exhibited a symmetrical bimodal pattern of orientation with respect to the trained axis. Since the e-vector of polarised light provides an axial rather than a polar cue, the bimodal orientation exhibited by the lizards is consistent with the use of a celestial compass based on sky polarisation patterns. To confirm that the lizards could orient with respect to a polarisation pattern, lizards were trained in indoor pens to orient in a predictable direction under a linearly polarised light source. When tested in a circular arena illuminated by another polarised light source, the lizards used the e-vector direction of the polarised light source to orient along the trained axis. There was no evidence that the lizards were using any room-specific cues or brightness patterns to orient in the training direction. These results support the hypothesis that the lizards can use the e-vector direction of polarised light in the form of a sky polarisation compass.
PELVIC ASPIRATION IN THE AMERICAN ALLIGATOR (ALLIGATOR MISSISSIPPIENSIS)
Authors: Farmer Colleen G. , Carrier David R. 
Published: April 2021

ABSTRACT
The pelvis of crocodilians is highly derived in that the pubic bones are isolated from the acetabulum and are attached to the ischia via moveable joints. We examined the possible role of this unusual morphology in lung ventilation by measuring ventilation, abdominal pressure and the electrical activity of several abdominal and pelvic muscles in the American alligator (Alligator mississippiensis). We found that the activity of two pelvic muscles, the ischiopubis and ischiotruncus muscles, was correlated with inspiration; these muscles rotate the pubes ventrally and thereby increase abdominal volume. During expiration, contraction of the rectus abdominis and transversus abdominis rotates the pubes dorsally. We suggest that this mechanism facilitates diaphragmatic breathing by creating space for caudal displacement of the viscera during inspiration. Because birds also use a dorso-ventral movement of the pelvis to effect ventilation, some form of pelvic aspiration may be plesiomorphic for archosaurs.
Permeation Through the Cftr Chloride Channel
Authors: Mccarty Nael A. 
Published: April 2021

ABSTRACT
The cystic fibrosis transmembrane conductance regulator (CFTR) protein forms a Cl− channel found in the plasma membranes of many epithelial cells, including those of the kidney, gut and conducting airways. Mutation of the gene encoding CFTR is the primary defect in cystic fibrosis, a disease that affects approximately 30 000 individuals in the United States alone. Alteration of CFTR function also plays an important role in the pathophysiology of secretory diarrhea and polycystic kidney disease. The basic mechanisms of permeation in this channel are not well understood. It is not known which portions of the protein contribute to forming the pore or which amino acid residues in those domains are involved in the biophysical processes of ion permeation. In this review, I will discuss (i) the present understanding of ion transport processes in the wild-type CFTR channel, (ii) the experimental approaches currently being applied to investigate the pore, and (iii) a proposed structure that takes into account the present data on mechanisms of ion selectivity in the CFTR channel and on blockade of the pore by open-channel blockers.
Sensory Habituation of Auditory Receptor Neurons: Implications for Sound Localization
Authors: Givois V. , Pollack G. S. 
Published: April 2021

ABSTRACT
Auditory receptor neurons exhibit sensory habituation; their responses decline with repeated stimulation. We studied the effects of sensory habituation on the neural encoding of sound localization cues using crickets as a model system. In crickets, Teleogryllus oceanicus, sound localization is based on binaural comparison of stimulus intensity. There are two potential codes at the receptor-neuron level for interaural intensity difference: interaural difference in response strength, i.e. spike rate and/or count, and interaural difference in response latency. These are affected differently by sensory habituation. When crickets are stimulated with cricket-song-like trains of sound pulses, response strength declines for successive pulses in the train, and the decrease becomes more pronounced as the stimulus intensity increases. Response decrement is thus greater for receptors serving the ear ipsilateral to the sound source, where intensity is higher, resulting in a decrease in the interaural difference in response strength. Sensory habituation also affects response latency, which increases for responses to successive sound pulses in the stimulus train. The change in latency is independent of intensity, and thus is similar for receptors serving both ears. As a result, interaural latency difference is unaffected by sensory habituation and may be a more reliable cue for sound localization.
Phenotypic Plasticity of Early Myogenesis and Satellite Cell Numbers in Atlantic Salmon Spawning in Upland and Lowland Tributaries of a River System
Authors: Johnston Ian A. , Mclay H. Anne , Abercromby Marguerite , Robins Duncan 
Published: April 2021

ABSTRACT
Early myogenesis was studied in the offspring of Atlantic salmon (Salmo salar L.) spawning in a lowland (Sheeoch) and an upland (Baddoch) tributary of the River Dee System, Aberdeenshire, Scotland. Eggs from each population were incubated at the simulated natural thermal regimes of each stream, which was on average 2.8 °C cooler for the Baddoch than for the Sheeoch. Relationships between muscle cellularity variables, the density of myonuclei and responses to temperature were investigated using multivariate statistical techniques. These revealed highly significant temperature effects (P&lt;0.001) at hatch (H) and first feeding (FF) and significant interactions between population and temperature (P&lt;0.001), indicating that Baddoch and Sheeoch salmon responded differently to the two temperature regimes. The total cross-sectional area of white muscle (WF.ta) at the adipose fin was relatively independent of temperature at hatch and first feeding in the Sheeoch population. In contrast, for alevins of Baddoch origin, WF.ta was 18.9 % (H) and 30.5 % (FF) higher in fish incubated at Baddoch than at Sheeoch temperatures. At hatch, there were 15.6 % more white muscle fibres (WF.no) at the cooler incubation temperature in fish of Sheeoch origin and 6.0 % more in fish of Baddoch origin. However, by first feeding, the difference in WF.no between temperatures had narrowed to 7.2 % in the Sheeoch fish and increased to 17.4 % in the Baddoch population. In contrast, at hatch, the density of myonuclei was 59.8 % higher at the warmer incubation temperature in the Sheeoch population and 23.5 % higher in the Baddoch population, but differences were less evident at first feeding. In Baddoch fish, 22.5 % of the total muscle nuclei were actively dividing at first feeding, as assessed by staining for proliferating cell nuclear antigen (PCNA). Of the PCNA-positive nuclei, 78 % were present in cells that stained for the c-met tyrosine kinase receptor, a marker of satellite cells and their division products. The proportion of c-met-positive cells staining for individual myogenic regulatory factors was 72.4 % for the myogenic transcription factor MyoD, 76.3 % for the myogenic transcription factor Myf-5, 62.1 % for myogenin and 48.7 % for the myogenic transcription factor Myf-6. For the Sheeoch population, there were 26.5 % more c-met-expressing (P&lt;0.01) and 23.2 % more myogenic-regulatory-factor-expressing (P&lt;0.05) cells at Sheeoch than at Baddoch temperatures. In contrast, incubation temperature had no significant effects on satellite cell density in the Baddoch population.
Colour Constancy of the Swallowtail Butterfly Papilio Xuthus
Authors: Kinoshita Michiyo , Arikawa Kentaro 
Published: April 2021

ABSTRACT
We have recently shown that the Japanese yellow swallowtail butterfly Papilio xuthus uses colour vision when searching for food. In the field, these butterflies feed on nectar provided by flowers of various colours not only in direct sunlight but also in shaded places and on cloudy days, suggesting that they have colour constancy. Here, we tested this hypothesis. We trained newly emerged Papilio xuthus to feed on sucrose solution on a paper patch of a certain colour under white illumination. The butterflies were then tested under both white and coloured illumination. Under white illumination, yellow- and red-trained butterflies selected the correctly coloured patch from a four-colour pattern and from a colour Mondrian collage. Under four different colours of illumination, we obtained results that were fundamentally similar to those under white illumination. Moreover, we performed critical tests using sets of two similar colours, which were also correctly discriminated by trained butterflies under coloured illumination. Taken together, we conclude that the butterfly Papilio xuthus exhibits some degree of colour constancy when searching for food.
Mass Spectrometric Survey of Peptides in Cephalopods With an Emphasis on the Fmrfamide-Related Peptides
Authors: Sweedler Jonathan V. , Li Lingjun , Floyd Philip , Gilly William 
Published: April 2021

ABSTRACT
A matrix-assisted laser desorption/ionization (MALDI) mass spectrometric (MS) survey of the major peptides in the stellar, fin and pallial nerves and the posterior chromatophore lobe of the cephalopods Sepia officinalis, Loligo opalescens and Dosidicus gigas has been performed. Although a large number of putative peptides are distinct among the three species, several molecular masses are conserved. In addition to peptides, characterization of the lipid content of the nerves is reported, and these lipid peaks account for many of the lower molecular masses observed. One conserved set of peaks corresponds to the FMRFamide-related peptides (FRPs). The Loligo opalescens FMRFa gene has been sequenced. It encodes a 331 amino acid residue prohormone that is processed into 14 FRPs, which are both predicted by the nucleotide sequence and confirmed by MALDI MS. The FRPs predicted by this gene (FMRFa, FLRFa/FIRFa and ALSGDAFLRFa) are observed in all three species, indicating that members of this peptide family are highly conserved across cephalopods.
Processes Contributing To Metabolic Depression In Hepatopancreas Cells From The SnailHelix Aspersa
Authors: Bishop T. , Brand M. D. 
Published: April 2021

ABSTRACTCells isolated from the hepatopancreas of the land snail Helix aspersa strongly depress respiration both immediately in response to lowered (oxygen conformation) and, in the longer term, during aestivation. These phenomena were analysed by dividing cellular respiration into non-mitochondrial and mitochondrial respiration using the mitochondrial poisons myxothiazol, antimycin and azide. Non-mitochondrial respiration accounted for a surprisingly large proportion, 65±5 %, of cellular respiration in control cells at 70 % air saturation. Non-mitochondrial respiration decreased substantially as oxygen tension was lowered, but mitochondrial respiration did not, and the oxygen-conforming behaviour of the cells was due entirely to the oxygen-dependence of non-mitochondrial oxygen consumption. Non-mitochondrial respiration was still responsible for 45±2 % of cellular respiration at physiological oxygen tension. Mitochondrial respiration was further subdivided into respiration used to drive ATP turnover and respiration used to drive futile proton cycling across the mitochondrial inner membrane using the ATP synthase inhibitor oligomycin. At physiological oxygen tensions, 34±5 % of cellular respiration was used to drive ATP turnover and 22±4 % was used to drive proton cycling, echoing the metabolic inefficiency previously observed in liver cells from mammals, reptiles and amphibians. The respiration rate of hepatopancreas cells from aestivating snails was only 37 % of the control value. This was caused by proportional decreases in non-mitochondrial and mitochondrial respiration and in respiration to drive ATP turnover and to drive proton cycling. Thus, the fraction of cellular respiration devoted to different processes remained constant and the cellular energy balance was preserved in the hypometabolic state.