bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ca2+ Signaling in Fowl Aortic Smooth Muscle Increases During Maturation But is Impaired in Neointimal Plaques
Authors: Qin Ze-Lian , Nishimura Hiroko 
Published: April 2021

ABSTRACT
Many bird species show the spontaneous development of high arterial pressure and vascular lesions in the aorta and other large arteries. In chickens, arterial pressure tends to increase with age/maturation (particularly in males), and subendothelial hyperplasia (neointima) in the abdominal aorta is often seen prior to sexual maturation. The mechanisms involved, however, are not known. Our aim, therefore, was to determine (1) whether cytosolic Ca2+ signaling (CCS) responses to vasoactive substances in fowl aortic smooth muscle differ among chickens at different maturation stages and (2) whether CCS responses to Ca2+ channel agonists in neointimal plaques differ from those in normal aortic smooth muscle.
K+ increased CCS in a dose-dependent manner in isolated and superfused abdominal aortic smooth muscle tissue from chicks (5–9 weeks old), pullets (11–18 weeks old) and adult hens (20 weeks and older); CCS responses increased as chickens matured. The addition of Bay K 8644 (10−6 mol l−1) to Ringer’s solution containing 50 mmol l−1 K+ further increased CCS, and this response was reduced to half by nifedipine (10−6 mol l−1). Norepinephrine did not alter CCS in chicks, whereas marked dose-dependent increases in CCS were noted in pullets. In contrast to the CCS responses to K+, the norepinephrine-induced CCS responses became smaller in adult hens. Isolated neointimal plaques showed only slight increases in CCS in response to 50 mmol l−1 K+ plus Bay K 8644, whereas clear responses were noted in aortic smooth muscle tissue underlying the plaques. These results suggest (1) that CCS responses to Ca2+ channel agonists increased with sexual maturation in fowl, but (2) that CCS responses to norepinephrine were low in mature hens and to K+ plus Bay K 8644 were low in spontaneously developed neointima, suggesting that phenotypic modulation of Ca2+ channel/norepinephrine receptors may have occurred during maturation/aging and in neointima.
Scavenger-Receptor-Mediated Endocytosis in Endocardial Endothelial Cells of Atlantic Cod Gadus Morhua
Authors: Sørensen Karen K. , Melkko Jukka , Smedsrød Bård 
Published: April 2021

ABSTRACT
Scavenger receptors are multifunctional integral membrane proteins that mediate the endocytosis of many different macromolecular polyanions and also participate in host defence reactions and cell adherance. In Atlantic cod (Gadus morhua L.), two intravenously injected scavenger receptor ligands, [125I]tyramine-cellobiose-labelled formaldehyde-treated serum albumin (125I-TC-FSA) and 125I-labelled N-terminal propeptide of type I procollagen (125I-PINP), distributed mainly to the heart. Cellular uptake was visualized by injections of fluorescently labelled FSA (FITC-FSA), which was recovered in discrete vesicles in endocardial endothelial cells of both heart chambers. Studies in vitro showed that radioiodinated FSA and PINP were endocytosed and degraded very efficiently by cultured atrial endocardial endothelial cells. Moreover, uptake of 125I-FSA was Ca2+-independent. Out of a range of unlabelled ligands, only the scavenger receptor ligands FITC-FSA, polyinosinic acid and, to a varying extent, FSA, acetylated low-density lipoprotein (AcLDL) and PINP, were able to compete with radioiodinated FSA, PINP or AcLDL for uptake in isolated endocardial cells. From our findings, we conclude that the endocardial endothelial cells are major carriers of scavenger receptors in cod. In addition, our results strengthen the hypothesis that these cells in cod play the same important function as that established for the scavenger endothelial cells of the mammalian liver.
The Role of the Frontal Ganglion in the Feeding and Eclosion Behavior of the Moth Manduca Sexta
Authors: Miles Carol I. , Booker Ronald 
Published: April 2021

ABSTRACT
We have examined the musculature and motor patterns of the foregut and the role of the frontal ganglion in the adult moth Manduca sexta. During adult development, the structure of the foregut changes from a simple straight tube to a pump consisting of a flexible-roofed chamber or cibarium, with dilator muscles that raise the roof to draw in fluids and a compressor to push it down and force the fluid down the thin-walled esophagus. The frontal ganglion drives the activity of this cibarial pump during feeding, which is triggered by the application of sucrose solution or water to the proboscis. The feeding motor pattern consists of coupled bursts of the pump dilators and shorter-duration, high-frequency bursts of spikes from the pump compressor.
The pump is also activated at the adult molt. At this time, it is used both before the moth emerges from the pupal case for swallowing molting fluid and again after emergence for swallowing air. These behaviors are important for eclosion and are necessary for the expansion of the wings after eclosion. Their motor patterns are similar to the feeding program. Up to 24 h before adult ecdysis, this motor pattern can be triggered by the peptide eclosion hormone. The other eclosion-related peptide, Manduca sexta eclosion-triggering hormone, does not appear to trigger activity of the cibarial pump.
The Energetic Cost of Copulation in a Polygynandrous Millipede
Authors: Telford Steven R. , Webb Peter I. 
Published: April 2021

ABSTRACT
We determined the energetic cost of copulation in both sexes of Alloporus uncinatus, a polygynandrous millipede in which copulation can last for several hours and involves physical restraint of the female by the male. We found an elevation in the rate of oxygen consumption by males and a depression in the rate of oxygen consumption by females during copulation. The rate of oxygen consumption of females, but not of males, was elevated immediately after copulation, indicating that females had built up and were repaying an oxygen debt. On this basis, we estimated energy expenditure during copulation to be 30 % above resting levels in males and 14 % above resting levels in females. As matings are frequent in this species in the wild throughout the 4 month breeding season, we suggest that the energetic demands of copulation are a previously overlooked potentially significant cost of reproduction in this species and in other invertebrate species with similar mating patterns.
A Role of 5-HT2 Receptors in the Gill Vasculature of the Antarctic Fish Pagothenia Borchgrevinki
Authors: Sundin Lena , Davison William , Forster Malcolm , Axelsson Michael 
Published: April 2021

ABSTRACT
This study was conducted to describe the cardiovascular responses to intra-arterial injections of serotonin in the Antarctic fish Pagothenia borchgrevinki and to elucidate the underlying mechanisms. Immunohistochemistry was used to localise serotonin-containing cells within the gills. Simultaneous and continuous recordings of ventral and dorsal aortic blood pressure, heart rate and ventral aortic blood flow (cardiac output) were made using standard cannulation procedures in combination with Doppler flow measurement. An extracorporeal loop with an in-line oxygen electrode allowed continuous measurements of arterial oxygen pressure Pre-branchial injection of serotonin (5-hydroxytryptamine, 5-HT) or the 5-HT2 receptor agonist α-methylserotonin increased the branchial vascular resistance and ventral aortic pressure, while the 5-HT1 receptor agonist piperazine was without effect. The branchial vasoconstriction produced by serotonin injection was completely blocked by the 5-HT1/5-HT2 receptor antagonist methysergide and the branchial vasoconstriction produced by α-methylserotonin injection was completely blocked by the specific 5-HT2 receptor antagonist LY53857. The results suggest that the 5-HT2 receptor alone mediates the branchial vasoconstriction. Serotonin also mediated a methysergide-sensitive reduction in , the reduction being greatest when the pre-injection value was high. 5-HT-immunoreactive cells and nerve fibres were present within the gill tissues. All the 5-HT-immunoreactive cells were located on the efferent side of the filaments, but 5-HT-immunoreactive nerve fibres were found lining both of the branchial arteries. Our findings demonstrate a potential serotonergic control system for the gills in Pagothenia borchgrevinki. In contrast to its effects on the branchial vasculature, serotonin produced a methysergide-insensitive decrease in the systemic vascular resistance. However, neither the specific 5-HT1 nor 5-HT2 receptor agonists produced a decrease in the resistance of the systemic vasculature. The nature of the serotonergic receptor(s) inducing vasodilation in teleost fish is uncertain.
Prolonged Swimming, Recovery and Repeat Swimming Performance of Mature Sockeye Salmon Oncorhynchus Nerka Exposed to Moderate Hypoxia and Pentachlorophenol
Authors: Farrell A. P. , Gamperl A. K. , Birtwell I. K. 
Published: April 2021

ABSTRACT
Mature, wild sockeye salmon (Oncorhynchus nerka) demonstrated their remarkable stamina and recovery abilities by performing three consecutive critical swimming speed tests with only a 45 min interval for recovery between subsequent tests. Although the repeated swimming challenges were performed without a full recovery, normoxic fish swam just as well on the second swim, and the majority of fish swam only marginally more poorly on the third swim. In addition, metabolic loading in these fish, as measured by the rate of oxygen consumption, ventilation rate and plasma lactate levels during recovery, did not appear to be cumulative with successive swims. Fish, however, did not recover as well after a similar level of initial swimming performance under moderately hypoxic conditions (water mmHg; 1 mmHg=0.1333 kPa). Four out of the five fish did not swim again and their high plasma lactate levels indicated a greater anaerobic effort.
In another group of fish, metabolic loading (elevated control rates of oxygen consumption) was induced with an overnight sublethal exposure to pentachlorophenol, but these fish swam as well as normoxic fish on the first swim, and five of the six fish swam for a third time at a marginally lower critical swimming speed. In contrast to expectations, pentachlorophenol pretreatment and moderate hypoxia were not additive in their effects. Instead, the effects resembled those of pentachlorophenol pretreatment alone. The results are discussed in terms of what aspects of fatigue might impair the repeat swimming performance of sockeye salmon.
Visual Modulation of Olfactory Learning in Honeybees
Authors: Gerber Bertram , Smith Brian H. 
Published: April 2021

ABSTRACT
We use classical conditioning of the honeybee (Apis mellifera) proboscis extension reflex with a visual (A) and an olfactory (X) conditioned stimulus in a blocking paradigm. Typically, learning about one element (X) of a compound (AX) is decreased (blocked) if the other component (A) has previously been rewarded alone. Our results show that visual pretraining did not produce blocking in honeybees: instead, forward pairings of A with a reward increased subsequent learning about X relative to a backward pairing control. This finding violates the independence assumption, which holds that elements of inter-modal compound stimuli change associative strength independently of each other. Furthermore, it is at odds with common theories of conditioning that predict blocking and assume that the elements of a compound stimulus rely on one common internal reinforcing signal. Taking the functional anatomy of the honeybee brain into account, we suggest that vision and olfaction may not rely on the same internal reinforcing signal; compound interactions might thus reflect the wiring of the honeybee nervous system and the biological significance of different sensory modalities during natural behaviour.
Why Do Mayflies Lay Their Eggs En Masse on Dry Asphalt Roads? Water-Imitating Polarized Light Reflected From Asphalt Attracts Ephemeroptera
Authors: Kriska György , Horváth Gábor , Andrikovics Sándor 
Published: April 2021

ABSTRACT
We report on dry asphalt roads acting as ‘mayfly traps’; that is, they lure swarming, mating and egg-laying mayflies in large numbers. To explain this surprising behaviour, we performed multiple-choice experiments with Ephemeroptera in the field, and measured and compared the reflection–polarization characteristics of an asphalt road and a mountain creek from which mayflies emerge. We show here that Ephemeroptera can be deceived by and attracted to dry asphalt roads because of the strongly horizontally polarized light reflected from the surface. Asphalt surfaces can mimic a highly polarized water surface to Ephemeroptera. The darker and smoother the asphalt surface, the higher is the degree of polarization of reflected light and the more attractive is the road to mayflies. We show that mayflies detect water by means of polarotaxis; that is, on the basis of the partially and horizontally polarized reflected light. Asphalt roads are excellent markers for swarming Ephemeroptera because of their conspicuous elongated form; the sky above them is usually open, which is the prerequisite of mayfly mating, and the higher temperature of the asphalt prolongs the reproductive activity of mayflies. These additional factors enhance the attractiveness of asphalt roads to swarming mayflies. Thus, asphalt roads near ephemeropteran emergence sites (lakes, rivers and creeks) are a great danger for mayflies, because eggs laid on the asphalt inevitably perish. Asphalt roads can deceive and attract mayflies en masse like the ancient tar pits and asphalt seeps or the recent crude or waste oil lakes deceive, lure and trap polarization-sensitive water-seeking insects in large numbers.
Adhesion and Reattachment of Compound Ascidians to Various Substrata: Weak Glue can Prevent Tissue Damage
Authors: Edlund Anna F. , Koehl M. A. R. 
Published: April 2021

ABSTRACT
Sessile, soft-bodied, compound ascidians are successful competitors for substrata in crowded benthic and epibiotic marine communities and can be effective colonists of new sites, through adult rafting and reattachment. Adhesion to the substratum is essential for these ecologically important functions; we therefore studied the material properties of colony attachment to various substrata in the rafting ascidians Botrylloides sp. We found that, compared with the strength of the colony tissues, the glue attaching Botrylloides sp. to the substratum is very weak. This relative weakness may protect the soft-bodied colonies from damage if they are ripped from their host. For sessile animals, such a weak-glue ‘strategy’ is only effective if the animals can later reattach to a substratum. By detaching Botrylloides sp. colonies from host eelgrass blades and allowing them to reattach, before measuring peel strengths, we learned that the initial reattachment of a colony depends upon rapid new growth of the colony rather than on fresh secretion of glue beneath old zooids. We also found that the propagation peel force necessary to remove Botrylloides sp. from different substrata (e.g. mussel shells, barnacle basal plates or eelgrass blades) depends upon the surface texture of the host. Thus, the overall tenacity of a colony is affected by the types of substrata that it overgrows.
Flight of the Vampire: Ontogenetic Gait-Transition in Vampyroteuthis Infernalis (Cephalopoda: Vampyromorpha)
Authors: Seibel Brad A. , Thuesen Erik V. , Childress James J. 
Published: April 2021

ABSTRACT
Vampyroteuthis infernalis is a cosmopolitan cephalopod that lives in the oxygen minimum layer between 600 and 800 m depth. Morphometric and physiological studies have indicated that V. infernalis has little capacity for jet propulsion and has the lowest metabolic rate ever measured for a cephalopod. Because fin swimming is inherently more efficient than jet propulsion, some of the reduction in energy usage relative to other cephalopods may result from the use of fins as the primary means of propulsion. V. infernalis undergoes a rapid metamorphosis which consists of changes in the position, size and shape of the fins. This suggests that there are changes in the selective factors affecting locomotion through ontogeny. The present study describes these changes in relation to models for underwater ‘flight’. Citrate synthase (CS) and octopine dehydrogenase (ODH) activities, indicative of aerobic and anaerobic metabolism, respectively, were measured in fin, mantle and arm tissue across a range of body size of four orders of magnitude. The low enzymatic activities in both posterior and anterior fin tissue and the relatively high activity in mantle muscle prior to metamorphosis indicate that jet propulsion using mantle contraction is the primary means of propulsion in juvenile V. infernalis. The increase in CS activity with size after metamorphosis suggests an increased use of the fins for lift-based propulsion. Fin swimming appears to be the primary means of propulsion at all adult sizes. The negative allometry of CS activity in mantle and arm muscle is consistent with the scaling of oxygen consumption previously measured for V. infernalis and with the scaling of aerobic metabolism observed in most animals. The unusual positive allometry of fin muscle CS activity suggests that the use of fins is either relatively more important or more costly in larger animals. Positive scaling of ODH activity in all tissues suggests that fin propulsion, jet propulsion and medusoid ‘bell-swimming’ are all important for burst escape responses. Enzyme activities in Cirrothauma murrayi are consistent with fin-swimming observed from submersibles, while those in Opisthoteuthis californiana suggest a strong reliance on medusoid swimming using the arms. The transition from jet propulsion to paired-fin ‘flight’ with increasing body size in Vampyroteuthis infernalis appears functionally to be an ontogenetic ‘gait-transition’.
Hydrodynamic effect of a satellite transmitter on a juvenile green turtle (Chelonia mydas)
Authors: Watson Kennard P. , Granger Robert A. 
Published: April 2021

ABSTRACT
Wind tunnel tests were performed to measure the effect of a satellite transmitter on a juvenile green turtle (Chelonia mydas). A full-scale turtle model was constructed from an 11.5 kg specimen with a 48 cm carapace length, and a transmitter model was constructed from a Telonics ST-6. The turtle model was tested in a wind tunnel with and without the transmitter, which was mounted on the forward, topmost part of the carapace. Drag, lift and pitch moment were measured for several speeds and flow angles, and the data were scaled for application to the marine environment. At small flow angles representative of straight-line swimming, the transmitter increased drag by 27–30 %, reduced lift by less than 10 % and increased the pitch moment by 11–42 %. On the basis of the drag data at zero angle of attack, it is estimated that the backpack will reduce swimming speed by 11 %, assuming that the turtle produces the same thrust with the unit attached. The drag data are also used to estimate the effect of a transmitter on the swimming energetics of an adult green turtle. Design guidelines are included to minimize the adverse forces and moments caused by the transmitter.
Voltage-activated currents in identified giant interneurons isolated from adult crickets Gryllus bimaculatus
Authors: Kloppenburg Peter , Hörner Michael 
Published: April 2021

ABSTRACT
The electrophysiological properties of cultured giant interneurons isolated from the terminal ganglion of adult crickets (Gryllus bimaculatus) were investigated using whole-cell patch-clamp techniques. To allow for unequivocal identification of these interneurons in cell culture, a protocol for fast and selective labeling of their cell bodies was established. Prior to cell dissociation, the giant interneurons were backfilled through their axons in situ with a fluorescent dye (dextran tetramethylrhodamine). In primary cell cultures, the cell bodies of giant interneurons were identified among a population of co-cultured neurons by their red fluorescence.
Action potentials were recorded from the cell bodies of the cultured interneurons suggesting that several types of voltage-activated ion channels exist in these cells. Using voltage-clamp recording techniques, four voltage-activated currents were isolated and characterized.
The giant interneurons express at least two distinct K+ currents: a transient current that is blocked by 4-aminopyridine (4×10−3 mol l−1) and a sustained current that is partially blocked by tetraethylammonium (3×10−2 mol l−1) and quinidine (2×10−4 mol l−1). In addition, a transient Na+ current sensitive to 10−7 mol l−1 tetrodotoxin and a Ca2+ current blocked by 5×10−4 mol l−1 CdCl2 have been characterized. This study represents the first step in an attempt to analyze the cellular and ionic mechanisms underlying plasticity in the well-characterized and behaviorally important giant interneuron pathway in insects.
Effects of heat shock and hypoxia on protein synthesis in rainbow trout (Oncorhynchus mykiss) cells
Authors: Airaksinen Susanna , Råbergh Christina M. I. , Sistonen Lea , Nikinmaa Mikko 
Published: April 2021

ABSTRACT
We examined the effects of heat stress (from 18 °C to 26 °C) and low oxygen tension (1 % O2=1 kPa) on protein synthesis in primary cultures of hepatocytes, gill epithelial cells and fibroblast-like RTG-2 cells of rainbow trout Oncorhynchus mykiss. All these cell types displayed elevated levels of 67, 69 and 92 kDa proteins, whereas a 104 kDa protein was induced only in RTG-2 cells. Hypoxia induced a cell-type-specific response, increasing the synthesis of 36, 39 and 51 kDa proteins in the gill epithelial cells. The regulation of the heat-shock response in fish hepatocytes showed that an HSF1-like factor is involved in the transcriptional induction of the hsp70 gene. Consequently, there was a pronounced accumulation of hsp70 mRNA. Furthermore, the kinetics of activation of DNA binding and the increase in hsp70 gene expression showed a remarkable correlation, indicating that hsp70 expression is regulated at the transcriptional level in these trout cells.
Purification and cloning of the salivary nitrophorin from the hemipteran Cimex lectularius
Authors: Valenzuela Jesus G. , Ribeiro José M. C. 
Published: April 2021

ABSTRACT
Cimex lectularius and Rhodnius prolixus contain salivary nitric oxide (NO) that may help them to feed on their vertebrate hosts by promoting vasodilation and inhibiting platelet aggregation. Salivary NO is associated with heme proteins (nitrophorins) that store and transport NO from the insect salivary glands to the skin of the host. In this study, the salivary nitrophorin of Cimex lectularius was purified by DEAE chromatography and reverse-phase high-performance liquid chromatography. The purified nitrophorin had a molecular mass of 32.9 kDa. The DEAE-purified hemoprotein was able to bind NO, and this binding shifted the absorption maximum from 388 nm to 438 nm. The ratio of heme to apoprotein was estimated to be of 1:1. A cDNA clone of 1079 base pairs was sequenced and was found to code for a protein with a molecular mass of 31.7 kDa. The clone sequence was in agreement with the internal peptide sequences obtained from the purified protein. Sequencing of the isolated clone indicates high similarity to several inositol phosphatases; however, no significant similarities emerged when the sequence of C. lectularius nitrophorin was compared with that of R. prolixus nitrophorin, the only other nitrophorin known in insect saliva. Because C. lectularius and R. prolixus belong to two different families of Hemiptera that evolved independently to blood feeding, a case is made for the convergent evolution of these two insect nitrophorins.