bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Mechanical Properties of Fin Whale Arteries are Explained by Novel Connective Tissue Designs
Authors: Gosline John M. , Shadwick Robert E. 
Published: April 2021

ABSTRACT
The aortic arch and the descending aorta in the fin whale (Balaenoptera physalus) are structurally and mechanically very different from comparable vessels in other mammals. Although the external diameter of the whale’s descending thoracic aorta (approximately 12 cm) is similar to that predicted by scaling relationships for terrestrial mammals, the wall thickness:diameter ratio in the whale (0.015) is much smaller than the characteristic value for other mammals (0.05). In addition, the elastic modulus of the thoracic aorta (12 MPa at 13 kPa blood pressure) is about 30 times higher than in other mammals. In contrast, the whale’s aortic arch has a wall thickness/diameter ratio (0.055) and an elastic modulus (0.4 MPa) that are essentially identical to those for other mammals. However, the aortic arch is unusual in that it can be deformed biaxially to very large strains without entering a region of high stiffness caused by the recruitment of fully extended collagen fibres. Chemical composition studies indicate that the elastin:collagen ratio is high in the aortic arch (approximately 2:1) and that this ratio falls in the thoracic (approximately 1:2) and abdominal (approximately 1:3) aortas, but the magnitude of the change in composition does not account for the dramatic difference in mechanical properties. This suggests that there are differences in the elastin and collagen fibre architecture of these vessels. The descending aorta contains dense bands of tendon-like, wavy collagen fibres that run in the plane of the arterial wall, forming a fibre-lattice that runs in parallel to the elastin lamellae and reinforces the wall, making it very stiff. The aortic arch contains a very different collagen fibre-lattice in which fibres appear to have a component of orientation that runs through the thickness of the artery wall. This suggests that the collagen fibres may be arranged in series with elastin-containing elements, a difference in tissue architecture that could account for both the lower stiffness and the extreme extensibility of the whale’s aortic arch. Thus, both the structure and the mechanical behaviour of the lamellar units in the aortic arch and aorta of the whale have presumably been modified to produce the unusual mechanical and haemodynamic properties of the whale circulation.
Elevation of Plasma Somatolactin Concentrations During Acidosis in Rainbow Trout (Oncorhynchus Mykiss)
Authors: Kakizawa Sho , Kaneko Toyoji , Hirano Tetsuya 
Published: April 2021

ABSTRACT
Somatolactin (SL) is a putative pituitary hormone of the growth hormone (GH)/prolactin (PRL) family in fish; its physiological function has yet to be determined. Acidosis was induced in rainbow trout (Oncorhynchus mykiss) by exposure to acidic water (pH 4.5) or by exhaustive exercise, and plasma concentrations of SL, PRL and GH as well as other plasma parameters were examined. A decrease in blood pH was observed in fish from 1 day after water acidification until the end of the experiment at day 7. Plasma SL levels in the acid-exposed fish increased, reached a peak on day 1 and then returned to the initial level by day 4. No change was seen in plasma concentrations of PRL throughout the experiment. Plasma levels of GH, in contrast, decreased in the acid-exposed fish on days 2 and 4. Plasma cortisol levels in the acid-exposed fish were higher than the control level on days 4 and 7, although plasma cortisol levels did not increase above the initial level in response to water acidification. There was no significant change in the expression of SL-, PRL-and GH-mRNA in the pituitary gland. Levels of plasma Na+ and lactate were reduced 12 h after water acidification and remained low throughout the experiment. Exhaustive exercise in shallow water at neutral pH (7.5) resulted in a transient but pronounced acidosis, associated with increases in plasma SL, cortisol, Cas2+, phosphate and lactate levels. Plasma SL levels returned to the initial level along with the recovery of blood acid–base status. In contrast, plasma cortisol levels stayed elevated even 24 h after exercise. There was no correlation between plasma PRL and GH levels and blood pH. Elevation of plasma SL levels during acidosis suggests the possible involvement of SL in acid–base regulation in rainbow trout.
Locust ION Transport Peptide (ITP): Primary Structure, cDNA and Expression in a Baculovirus System
Authors: Meredith J. , Ring M. , Macins A. , Marschall J. , Cheng N. N. , Theilmann D. , Brock H. W. , Phillips J. E. 
Published: April 2021

ABSTRACT
Ion transport peptide (ITP) purified from locust nervous corpus cardiacum (CC) has previously been shown to stimulate salt and water reabsorption and inhibit acid secretion in the ileum of Schistocerca gregaria. We used the partial amino acid sequence of purified ITP to derive degenerate primers. These were used to amplify a cDNA from brain RNA using reverse transcription and the polymerase chain reaction (RtPCR). This sequence was extended using anchored PCR to yield a partial, 517 bp cDNA clone. This cDNA encodes a putative ITP prohormone which could be cleaved at two dibasic amino acid sites to yield a 72 residue active amidated peptide. The deduced amino acid sequence from the cDNA agrees completely with the amino acid sequence and molecular mass (8564 Da) derived from analysis of purified ITP. Relative to a family of crustacean hyperglycaemic hormones (CHH), all six cysteine residues and many other amino acid residues are conserved in ITP, establishing that ITP is a homologue. However, CHH, crab eyestalk and CC extracts from distantly related insects have no action, whereas CC extracts from closely related insects are active on the locust ITP assay, showing that the bioassay is selective. Insect Sf9 cells transfected with a baculovirus containing our partial cDNA secreted a potent stimulant of locust ileal transport, confirming that the peptide encoded by our ITP clone has biological activity. The mRNA for ITP is restricted to the brain and CC. Interestingly, a related mRNA is observed in other tissues which are not active on the ITP bioassay.
The Advantages of an Unsteady Panel Method in Modelling the Aerodynamic Forces on Rigid Flapping Wings
Authors: Smith Michael J. C. , Wilkin Peter J. , Williams Marc H. 
Published: April 2021

ABSTRACT
This paper responds to research into the aerodynamics of flapping wings and to the problem of the lack of an adequate method which accommodates large-scale trailing vortices. A comparative review is provided of prevailing aerodynamic methods, highlighting their respective limitations as well as strengths. The main advantages of an unsteady aerodynamic panel method are then introduced and illustrated by modelling the flapping wings of a tethered sphingid moth and comparing the results with those generated using a quasi-steady method. The improved correlations of the aerodynamic forces and the resultant graphics clearly demonstrate the advantages of the unsteady panel method (namely, its ability to detail the trailing wake and to include dynamic effects in a distributed manner).
Water Loss And Morphological Changes During Desiccation Of The Anhydrobiotic Nematode Ditylenchus Dipsaci
Authors: Wharton David A. 
Published: April 2021

ABSTRACT
Ditylenchus dipsaci is an anhydrobiotic nematode which can withstand direct exposure to extreme desiccation. Water loss has been determined gravimetrically and morphological changes quantified by light microscopy. Water loss occurs in two distinct phases, with a permeability slump 2 min after the onset of desiccation. The permeability slump remains after treatment with sodium azide or carbon dioxide but disappears after heat treatment. There is a marked decrease in body length during the first 2 min of desiccation but diameter decreases throughout the desiccation period, mainly as a result of a decrease in the thickness of the hyaline layer. These observations suggest that one mechanism by which the nematode controls water loss during desiccation is by narrowing the groove between annulations. They also provide measurements on living nematodes which can be compared with more detailed observations using electron microscope techniques.
Characterization of two Myotropic Neuropeptides in the Fmrfamide family from Segmental Ganglia of the moth Manduca Sexta: Candidate Neurohormones and Neuromodulators
Authors: Kingan Timothy G. , Shabanowitz Jeffrey , Hunt Donald F. , Witten Jane L. 
Published: April 2021

ABSTRACT
We have characterized two new members of the FMRFamide family of neuropeptides from the segmental ganglia of the tobacco hornworm Manduca sexta. Levels of peptides in ganglia used for purification were enhanced by manipulating their exposure to the steroid molting hormones. Explants of ganglia were cultured in the low-level ecdysteroid environment of diapausing pupae shown previously to evoke accumulation of FMRFamide-like immunoreactivity (FLI). Sufficient material for sequencing was obtained from 180 explanted ganglia. Extracts of ganglia were fractionated using two reverse-phase liquid chromatography procedures, and the immunoreactive fractions were subjected to sequence analysis using electrospray mass spectrometry. The sequences of the two peptides were determined to be GNSFLRFamide and DPSFLRFamide. These peptides have been named MasFLRFamide II and MasFLRFamide III, respectively; the previously characterized M. sexta FLRFamide (pEDVVHSFLRFamide) has been renamed MasFLRFamide I. The three peptides show distinctive tissue and developmental distributions as determined from fractionated extracts of larval and adult central nervous system structures and neurohemal organs. In the retrocerebral corpora cardiaca/corpora allata, MasFLRFamide I was the predominant form, while in the segmental ganglia MasFLRFamides II and III predominated. Higher levels of MasFLRFamide I and II were found in the adult, whereas there was little apparent change in the level of MasFLRFamide III upon metamorphosis. Determinations of peptide levels in fractionated hemolymph of newly emerged moths revealed that levels of MasFLRFamide I and III could exceed 10 nmol l-1. The actions of the three peptides were tested on the moth ileum. MasFLRFamides II and III were found to be stimulatory. At 1 nmol l-1, these peptides induced robust increases in the rate of rhythmic longitudinal and peristaltic waves of contractions. In contrast, MasFLRFamide I was ineffective even at 20 nmol l-1. Thus, while all three peptides have the characteristics of neurohormones in M. sexta, the physiological findings show that the heptapeptide FLRFamides have properties distinct from those of the decapeptide.
Voltage- and Ca2+-Gated Currents in Zebrafish Olfactory Receptor Neurons
Authors: Corotto Frank S. , Piper David R. , Chen Nansheng , Michel William C. 
Published: April 2021

ABSTRACT
Voltage-and Ca2+-gated currents were recorded from isolated olfactory receptor neurons (ORNs) of the zebrafish Danio rerio using the whole-cell voltage-clamp technique. Zebrafish ORNs had an average capacitance of 0.66 pF and an average apparent input resistance of 8.0 GΩ. Depolarizing steps elicited transient inward currents followed by outward currents with transient and sustained components. The transient inward current (INa) was sensitive to 1 μmol l-1 tetrodotoxin, activated between -74 mV and-64 mV, and reached half-maximal conductance at -28 mV. Its peak amplitude averaged-101 pA. Steady-state inactivation of INa was half-maximal at an average test potential of -78 mV and recovery from inactivation proceeded with two time constants averaging 23 ms and 532 ms. A sustained, Co2+-sensitive current (ICa) activated between -44 mV and -34 mV and reached a peak amplitude averaging -9 pA at -14 mV. Outward currents were carried by K+, based on the reversal potentials of tail currents, and consisted of a Ca2+-dependent K+ current, a delayed rectifier current (IDR) and a transient K+ current (IA). The Ca2+-dependent K+ current (IK(Ca)) activated between -44 mV and -34 mV, whereas IDR and IA activated between -34 mV and -24 mV. In summary, zebrafish ORNs possess a complement of gated currents similar but not identical to that of ORNs from other vertebrates and which appears well suited for encoding a graded receptor potential into a train of action potentials.
Colour Learning in the Hawkmoth Macroglossum Stellatarum
Authors: Kelber Almut 
Published: April 2021

ABSTRACT
Newly eclosed specimens of the day-active hawkmoth Macroglossum stellatarum were trained to artificial flowers in dual-colour choice situations. Learning curves were obtained from learning and reversed-learning experiments. Initially, learning behaviour was influenced by innate colour preferences. In comparison with other lepidopterans, Macroglossum stellatarum learns well. When trained in a dual-choice situation, the moths learned not only to visit the rewarded colour but also to avoid the unrewarded colour. These good learning abilities are discussed in the context of the biology of the species.
A Novel Subunit of Vacuolar H+-ATPase Related to The b Subunit of F-ATPases
Authors: Supekova Lubica , Sbia Mohammed , Supek Frantisek , Ma Yuemei , Nelson Nathan 
Published: April 2021

ABSTRACT
The subunit structure of the vacuolar H+-ATPase (V-ATPase) membrane sector is not entirely known. The proteolipid is the only subunit that has been implicated in the mechanism of energy transfer in the enzyme. We have identified a protein (M16) that co-purifies with the V-ATPase complex from bovine chromaffin granules. Information obtained from the amino acid sequence of a proteolytic fragment of M16 was used to clone a bovine adrenal cDNA encoding this protein. The cDNA encodes a hydrophilic protein of 118 amino acid residues with a calculated molecular mass of 13 682 Da. Amino acid sequence analysis revealed that M16 exhibits a significant homology to subunit b of F-ATPases. M16 is smaller than subunit b and contains no apparent transmembrane segment in its N terminus. The remainder of subunit b is related to M16 not only by its amino acid sequence but also in its predicted structure of helix–turn–helix. The structural and evolutionary implications of these findings are discussed.
Peptidergic Regulation of Chromatophore Function in the European Cuttlefish Sepia Officinalis
Authors: Loi Poh Kheng , Saunders Robin G. , Young Doug C. , Tublitz Nathan J. 
Published: April 2021

ABSTRACT
Color patterning in cephalopod molluscs involves activation of a peripheral chromatophore system that is under neuromuscular control. The complex behavior of individual chromatophores is mediated by a specific set of muscles, the chromatophore muscles, that receive direct innervation from the central nervous system. To date, glutamate is the only excitatory transmitter that has been proposed to act at the chromatophore neuromuscular junction of cephalopods. We present data demonstrating that the chromatophore muscles in the European cuttlefish Sepia officinalis are also regulated by the FMRFamide family of neuropeptides. Using an in vitro chromatophore bioassay, it has been determined that several FMRFamide-related peptides (FaRPs) are potent excitors of the chromatophore muscles, causing chromatophore expansion. Immunocytochemical analyses of the central nervous system using an FMRFamide antibody revealed the presence of FMRFamide-like immunoreactive cell bodies in the posterior chromatophore lobes, the region of the brain containing the chromatophore motoneurons of the fin and mantle. FMRFamide-like immunoreactivity was also seen in the periphery, in the nerves around the chromatophores and in close apposition to the muscles in the chromatophore layer of the fin. HPLC analysis of the fin dermis isolated four bioactive peaks that were FMRFamide-immunoreactive when tested on an immunoblot assay. Two of these peaks co-eluted with known FaRPs, FMRFamide and ALSGDAFLRFamide, a decapeptide isolated from squid. Taken together, these data suggest that the FaRPs are likely to be endogenous excitors of the chromatophore muscles in cephalopods.
Ca2+ Transport Processes of Lobster Hepatopancreatic Brush-Border Membrane Vesicles
Authors: Zhuang Zhenpeng , Ahearn Gregory A. 
Published: April 2021

ABSTRACT
45Ca2+uptake by hepatopancreatic brush-border membrane vesicles of Atlantic lobster (Homarus americanus) occurred by a combination of three independent processes: (1) an amiloride-sensitive carrier-mediated transport system; (2) an amiloride-insensitive carrier-mediated transport system; and (3) a verapamil-inhibited channel process responsive to transmembrane potential. Both carrier-mediated processes were antiporters and capable of exchanging external Ca2+ with intravesicular Na+ or H+. The kinetic parameters of both carrier-mediated processes have been reported previously. External amiloride and Zn2+ were both competitive inhibitors of 45Ca2+ influx, reducing entry of the divalent cation at a single binding site with Ki values of 370 μmol l−1 for amiloride and 940 μmol l−1 for Zn2+. It is concluded that the mechanisms controlling Ca2+ entry into hepatopancreatic epithelial cells include a previously reported electrogenic 2Na+/1H+ antiporter, an electroneutral 2Na+/1Ca2+ antiporter and a verapamil-sensitive Ca2+ channel, which might also be used for the entry of Zn2+ and possibly other heavy metals. Evidence from an equilibrium-shift experiment, based on the thermodynamics of a coupled transport process, suggested that both monovalent (Na+) and divalent (Ca2+ and Zn2+) cations may enter hepatopancreatic epithelial cells through a common carrier-mediated transport protein. This suite of hepatopancreatic brush-border Ca2+ transport processes qualitatively resembles that previously reported for the luminal membrane of lobster antennal glands and suggests that crustacean epithelial cells from different organs may handle this divalent cation by similar means.
A Computational Fluid Dynamics Study of Tadpole Swimming
Authors: Liu Hao , Wassersug Richard J. , Kawachi Keiji 
Published: April 2021

ABSTRACT
The hydrodynamics and undulating propulsion of tadpoles were studied using a newly developed two-dimensional computational fluid dynamics (CFD) modeling method. The mechanism of thrust generation associated with the flow patterns during swimming is discussed. Our CFD analysis shows that the kinematics of tadpoles is specifically matched to their special shape and produces a jet-stream propulsion with high propulsive efficiency, as high as that achieved by teleost fishes. Investigation of the effect of Reynolds number indicates that the Froude efficiency increases with increasing Reynolds number with no ceiling in generating the jet-stream propulsion. Further studies using tadpole- and fish-shaped models with hindlimbs added to their body profiles reveal that the tadpole shape – a globose head with a tapered tail and hindlimbs at the base of the tail – allows tadpoles, but not fish, to develop hindlimbs with very little handicap on propulsion. The shapes and kinematics of tadpoles appear to be specially adapted to the requirement of these organisms to transform into frogs.
The Effect of Formaldehyde Exposure on the Transmembrane Distribution of Free Amino Acids in Muscles of Mytilus Edulis
Authors: Zachariassen Karl Erik , Olsen Anders Johny , Aunaas Tore 
Published: April 2021

ABSTRACT
Free amino acids in the posterior adductor muscle of mussels (Mytilus edulis) occur in a high-energy gradient group, with energy gradients of 15–18 kJ mol−1 (aspartate, beta-alanine, glycine, taurine and threonine), and a low-energy gradient group, with energy gradients around 12 kJ mol−1 (the rest of the amino acids). Two of the amino acids, glycine and taurine, are present at intracellular concentrations of 100–150 mmol kg−1, while the other amino acids occur at concentrations below 50 mmol kg−1.
Exposure of mussels to formaldehyde causes a marked influx of Na+ into the muscle cells and an increase in cellular water content. The Na+ gradient, which provides the energy for the cellular accumulation of free amino acids, is reduced. The drop in the Na+ gradient is accompanied by a nearly proportional reduction in the energy gradients of all amino acids in the high-energy gradient group and a 150 mmol kg−1 reduction in the total intracellular concentration of free amino acids. Most of this reduction is made up by the Na+-dependent amino acids aspartate, glycine and threonine, the concentrations of which are reduced by about 120 mmol kg−1.
The transmembrane distribution of the low-energy gradient amino acids seems to be independent of the Na+ gradient, and these amino acids display only moderate reductions in their intracellular concentrations when the Na+ gradient is reduced.
The reduction in the concentrations of the free amino acids appears to be a volume-regulatory response, serving to bring the cell volume back to its optimal level after the formaldehyde-induced Na+ influx has caused a cellular swelling. The basis of these differences in Na+-dependence is discussed.
Taurine, which is the quantitatively dominating organic solute and an important volume-regulatory osmolyte in mussels, does not take part in the volume-regulatory response. This may be due the role of taurine in the protection against potentially toxic Ca2+, which enters the cells in large quantities when mussels are exposed to formaldehyde.
Magnetic Compass Cues and Visual Pattern Learning in Honeybees
Authors: Frier Helen J. , Edwards Emma , Smith Claire , Neale Susi , Collett Thomas S. 
Published: April 2021

ABSTRACT
We show that honeybees can learn to distinguish between two 360 ° panoramic patterns that are identical except for their compass orientation; in this case, the difference was a 90 ° rotation about the vertical axis. To solve this task, bees must learn the patterns with respect to a directional framework. The most powerful cue to direction comes from the sky, but discrimination between patterns is possible in the absence of celestial information. Under some conditions, when other potential directional cues have been disrupted, we show that bees can use a magnetic direction to discriminate between the patterns.
An Increase in Activity of Serotonergic Retzius Neurones May not be Necessary for the Consummatory Phase of Feeding in the Leech Hirudo Medicinalis
Authors: Wilson R. J. A. , Kristan W. B. , Kleinhaus A. L. 
Published: April 2021

ABSTRACT
During the consummatory phase of feeding, in which blood is ingested, medicinal leeches display a characteristic set of behaviours: they extend their jaws, are less responsive to sensory input, produce mucus, relax the body wall and exhibit waves of peristalsis that can run the length of the body. Earlier reports suggested that this pattern of behaviour is orchestrated by serotonin released from Retzius cells in response to the appropriate sensory stimulation of the lip.
We have developed a semi-intact preparation in which only the nervous system in the posterior half of the leech was exposed. The front half of the leech was free to explore, bite through and feed until satiated from a blood-filled sausage casing while continuous intracellular and extracellular recordings were made from identified cells and the nerve roots of the exposed segments.
Prior to attachment of the animal to the feeding device, the firing frequency of the Retzius cell increased transiently during spontaneous movements or tactile stimuli to its front or posterior end. In contrast, Retzius cell activity decreased after the anterior sucker attached to the membrane of the feeding device at about the time when ingestion was initiated.
Increased activity of Leydig cells, which are known to modulate several circuits in the leech, was also associated with exploration. However, unlike that of Retzius cells, the activity of Leydig cells increased significantly following the onset of consumption.
These results suggest that increased activity of Retzius cells in midbody ganglia is not a prerequisite for the consummatory phase of feeding and raises questions regarding the role of serotonin in regulating this behaviour.