bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative Study on Neural Oscillation in the Procerebrum of the Terrestrial Slugs Incilaria Bilineata and Limax Marginatus
Authors: Kawahara Shigenori , Toda Shoichi , Suzuki Yasuyoshi , Watanabe Satoshi , Kirino Yutaka 
Published: April 2021

ABSTRACT
Coherent oscillatory activities in procerebral neurones have been described in Limax maximus; however, the electrical properties of the procerebrum of other terrestrial molluscs are less well understood. We have examined oscillatory activity in the procerebrum of Incilaria bilineata and Limax marginatus. The local field potential measured in the procerebrum of I. bilineata showed repetitive peaks which had the opposite polarity from those measured in L. marginatus. Optical measurement of membrane potential using a potential-sensitive dye, di-4-ANEPPS, showed that the oscillations in I. bilineata occurred mainly in the internal mass while those in L. marginatus were located in the cell mass. An analysis of the waveform revealed that the depolarizing phase of the oscillations consists of both a slow and a rapid component in both species. The rapid component was most pronounced in the internal mass of I. bilineata but was prominent in the cell mass of L. marginatus. The superior tentacle nerve, which projects to the terminal mass, also showed oscillations in synchrony with those of the procerebrum. These results suggest that oscillations in procerebral interneurones are commonly generated in a region adjacent to the terminal mass and that these oscillations may affect the membrane potential of the neurones constituting the superior tentacle nerve.
Mg2+ Transport in Plasma Membrane Vesicles of Renal Epithelium of the Mozambique Tilapia (Oreochromis Mossambicus)
Authors: Bijvelds Marcel J. C. , Kolar Zvonimir , Wendelaar Bonga Sjoerd E. , Flik Gert 
Published: April 2021

ABSTRACT
To elucidate the mechanisms involved in Mg2+ transport at the apical and basolateral poles of the renal tubular epithelium, apical and basolateral plasma membrane vesicle preparations were derived from kidney tissue of freshwater- and seawater-adapted Mozambique tilapia Oreochromis mossambicus. Brush-border preparations were enriched 15.8-fold in alkaline phosphatase activity and consisted almost exclusively of right-side-out membrane vesicles. Basolateral membrane preparations were enriched 7.5-fold in Na+/K+-ATPase activity and contained resealed vesicles and leaky membrane fragments. Mg2+ association with brush-border and basolateral plasma membranes, traced using radioactive 27Mg, occurred in an osmotically active space. In all instances, Mg2+ binding to the vesicular membrane was low compared with the vesicular uptake. Mg2+ equilibration across the vesicular membrane of brush-border preparations was rapid and sensitive to the presence of extravesicular Ca2+, suggesting that the apical membrane of the renal epithelium contains a transport pathway for divalent cations. Application of various ionic gradients did not affect vesicular Mg2+ transport in apical and basolateral membrane preparations, suggesting the presence of an ion-coupled transport mechanism. ATP or ATP-γ-S did not stimulate Mg2+ fluxes, indicating that Mg2+ transport does not proceed via an ATP-driven or activated transporter. In these aspects, vesicular Mg2+ transport was similar in seawater and freshwater preparations. These results suggest that the apical membrane of renal epithelial cells lacks an active secretory Mg2+ transport mechanism. We propose that the Mg2+ conductivity of the apical membrane reflects a route for downhill Mg2+ entry and is involved in renal Mg2+ reabsorption.
Ontogeny of Central Chemoreception During Fictive Gill and Lung Ventilation in an In Vitro Brainstem Preparation of Rana Catesbeiana
Authors: Torgerson C. S. , Gdovin M. J. , Remmers J. E. 
Published: April 2021

ABSTRACT
An isolated brainstem preparation of the bullfrog tadpole, Rana catesbeiana, displays coordinated rhythmic bursting activities in cranial nerves V, VII and X in vitro. In decerebrate, spontaneously breathing tadpoles, we have previously shown that these bursts correspond to fluctuations in buccal and lung pressures and to bursts of activity in the buccal levator muscle H3a. This demonstrates that the rhythmic bursting activities recorded in vitro represent fictive gill and lung ventilation. To investigate the ontogeny of central respiratory chemoreception during the transition from gill to lung ventilation, we superfused the isolated brainstems of four larval stage groups with oxygenated artificial cerebrospinal fluid at various levels of . We measured shifts in the pattern of fictive respiratory output and the response to central hypercapnic stimulation throughout development. At normal (2.3 kPa), stage 3–9 tadpoles displayed rhythmic neural bursts associated with gill ventilation, while stages 10–14 and 15–19 tadpoles produced oscillating bursting activity associated with both gill and lung respiration, and tadpoles at stages 20–25 displayed neural activity predominantly associated with lung ventilation. In stage 3–9 tadpoles, variations in of the superfusate (0.5–6.0 kPa) caused almost no change in fictive gill or lung ventilation. By contrast, stage 10–14 tadpoles showed a significant hypercapnic response (P&lt;0.05) in the amplitude and frequency of fictive gill ventilation, which was accompanied by a significant increase (P&lt;0.05) in the burst amplitude and respiratory output of cranial nerve X over that occurring at all other stages. The amplitude and frequency of fictive gill ventilation in stages 15–19 increased significantly (P&lt;0.05) in response to pH reduction, but became insensitive to hypercapnia at stages 20–25. The frequency of fictive lung ventilation was unresponsive to hypercapnia in stage 10–14, increased significantly by stage 15–19 (P&lt;0.05) and became maximal (P&lt;0.05) in stages 20–25. Overall, we describe the ontological development of central respiratory chemoreceptors driving respiratory output in the larval amphibian, demonstrating transfer in central chemoreceptive influence from gill to lung regulation during metamorphic stages. In addition, we provide novel evidence for the stimulatory influence of central chemoreceptors on fictive gill ventilation in response to CO2.
In Situ Biomechanics of the Syrinx and Sound Generation in Pigeons
Authors: Goller Franz , Larsen Ole Næsbye 
Published: April 2021

ABSTRACT
The in situ biomechanics of the vocal organ, the syrinx, was studied in anesthetized pigeons using fiberoptic instruments. The role of syringeal muscles was determined by electrical stimulation, and phonation was induced by injecting gas into the subsyringeal air sacs. This study presents the first direct observations of the biomechanical processes that occur in an intact syrinx.
Contraction of one of the syringeal muscles, the m. tracheolateralis (TL), withdraws the lateral tympaniform membranes (LTM) from the syringeal lumen, causing opening of the syringeal airways. Shortening of a second muscle, the sternotrachealis (ST), draws the syringeal cartilages closer to each other, causing the LTM to fold into the syringeal lumen. Maximal ST contraction does not lead to complete closure of the syrinx.
As air-sac pressure is increased by the injection of gas, the LTM are drawn into the syringeal lumen and balloon in a rostral direction until they touch, thus forming a fold-like valve. Air-induced phonation is always associated with vibrations of the membrane folds, suggesting that pulsatile release of air into the trachea by vibratory motion of the LTM generates sound. During air-induced phonation, strong stimulation of the TL terminates sound generation by abducting the LTM, whereas weak stimulation changes the geometry of the membrane folds, which is accompanied by changes in the acoustic structure of the sound. Stimulation of the ST has little effect on air-induced sounds.
The LTM appear to be the main sound generators, since disabling the medial tympaniform membranes (MTM) with tissue adhesive does not prevent phonation or change the frequency and amplitude structure of display coos in spontaneously vocalizing pigeons. Moreover, the activity of the syringeal muscles appears to have a mainly modulatory function, suggesting that the basic sound-generating mechanism is similar in both air-induced and natural phonation.
Mechanics of Locomotion in Lizards
Authors: Farley Claire T. , Ko T. Christine 
Published: April 2021

ABSTRACT
Lizards bend their trunks laterally with each step of locomotion and, as a result, their locomotion appears to be fundamentally different from mammalian locomotion. The goal of the present study was to determine whether lizards use the same two basic gaits as other legged animals or whether they use a mechanically unique gait due to lateral trunk bending. Force platform and kinematic measurements revealed that two species of lizards, Coleonyx variegatus and Eumeces skiltonianus, used two basic gaits similar to mammalian walking and trotting gaits. In both gaits, the kinetic energy fluctuations due to lateral movements of the center of mass were less than 5 % of the total external mechanical energy fluctuations. In the walking gait, both species vaulted over their stance limbs like inverted pendulums. The fluctuations in kinetic energy and gravitational potential energy of the center of mass were approximately 180 ° out of phase. The lizards conserved as much as 51 % of the external mechanical energy required for locomotion by the inverted pendulum mechanism. Both species also used a bouncing gait, similar to mammalian trotting, in which the fluctuations in kinetic energy and gravitational potential energy of the center of mass were nearly exactly in phase. The mass-specific external mechanical work required to travel 1 m (1.5 J kg-1) was similar to that for other legged animals. Thus, in spite of marked lateral bending of the trunk, the mechanics of lizard locomotion is similar to the mechanics of locomotion in other legged animals.
Maximum Speed and Mechanical Power Output in Lizards
Authors: Farley Claire T. 
Published: April 2021

ABSTRACT
The goal of the present study was to test the hypothesis that maximum running speed is limited by how much mechanical power the muscular system can produce. To test this hypothesis, two species of lizards, Coleonyx variegatus and Eumeces skiltonianus, sprinted on hills of different slopes. According to the hypothesis, maximum speed should decrease on steeper uphill slopes but mechanical power output at maximum speed should be independent of slope. For level sprinting, the external mechanical power output was determined from force platform data. For uphill sprinting, the mechanical power output was approximated as the power required to lift the center of mass vertically. When the slope increased from level to 40 ° uphill, maximum speed decreased by 28 % in C. variegatus and by 16 % in E. skiltonianus. At maximum speed on a 40 ° uphill slope in both species, the mechanical power required to lift the body vertically was approximately 3.9 times greater than the external mechanical power output at maximum speed on the level. Because total limb mass is small in both species (6–16 % of body mass) and stride frequency is similar at maximum speed on all slopes, the internal mechanical power output is likely to be small and similar in magnitude on all slopes. I conclude that the muscular system is capable of producing substantially more power during locomotion than it actually produces during level sprinting. Thus, the capacity of the muscular system to produce power does not limit maximum running speed.
Two novel tachykinin-related peptides from the nervous system of the crab Cancer borealis
Authors: Christie Andrew E. , Lundquist C. Tomas , Nässel Dick R. , Nusbaum Michael P. 
Published: April 2021

ABSTRACT
Immunocytochemical and biochemical studies have indicated the presence of many neuroactive substances in the stomatogastric nervous system (STNS) of the crab Cancer borealis. In electrophysiological studies, many of these substances modulate the motor output of neural networks contained within this system. Previous work in the STNS suggested the presence of neuropeptides related to the invertebrate tachykinin-related peptide (TRP) family. Here we isolate and characterize two novel peptides from the C. borealis nervous system that show strong amino acid sequence identity to the invertebrate TRPs. The central nervous systems of 160 crabs were extracted in an acidified solvent, after which four reversed-phase HPLC column systems were used to obtain pure peptides. A cockroach hindgut muscle contraction bioassay and a radioimmunoassay (RIA) employing an antiserum to locustatachykinin I (LomTK I) were used to monitor all collected fractions. The amino acid sequences of the isolated peptides were determined by Edman degradation. Mass spectrometry and chemical synthesis confirmed the sequences to be APSGFLGMR-NH2 and SGFLGMR-NH2. APSGFLGMR-NH2 is approximately 20-fold more abundant in the crab central nervous system than is SGFLGMR-NH2. We have named these peptides Cancer borealis tachykinin-related peptide Ia and Ib (CabTRP Ia and Ib), respectively. Both peptides are myoactive in the cockroach hindgut muscle contraction bioassay, with CabTRP Ia being approximately 500 times more potent than CabTRP Ib. RIA performed on HPLC-separated C. borealis stomatogastric ganglion (STG) extract revealed that CabTRP Ia is the only detectable TRP-like moiety in this ganglion. Incubation of synthetic CabTRP Ia with the isolated STG excited the pyloric motor pattern. These effects were suppressed by the broad-spectrum tachykinin receptor antagonist Spantide I. Spantide I had no effect on the actions of the unrelated endogenous peptide proctolin in the STG. There was no consistent influence of CabTRP Ib on the pyloric rhythm. Given its amino acid sequence and minimal biological activity in the crab, CabTRP Ib may be a breakdown product of CabTRP Ia.
Experience-dependent changes in the number of chemosensory sensilla on the mouthparts and antennae of Locusta Migratoria
Authors: Rogers S. M. , Simpson S. J. 
Published: April 2021

ABSTRACT
The effect of diet on the number of gustatory and olfactory sensilla was investigated in locusts. Insects fed for the final two stadia on nutritionally adequate synthetic foods have fewer sensilla on the maxillary palps and antennae than insects fed on the usual rearing diet of seedling wheat. This effect was seen irrespective of the nutritional balance of the foods and was independent of the concentration of nutrients present or the size of the insect. Supplying wheat odour to locusts fed synthetic foods had no effect on the number of sensilla present on the palps, but completely reversed the decrease in the number of olfactory sensilla of the antennae and partially reversed the decrease in the number of antennal uniporous trichoid sensilla. Locusts that were allowed to select between two nutritionally unbalanced but complementary synthetic foods had a higher number of sensilla on the maxillary palps than those fed individual synthetic foods, providing the two foods differed substantially in their protein:carbohydrate ratios. Insects also developed more sensilla if they were fed on two foods of identical nutritional composition but with different added flavours (1 % tannic acid or amygdalin). Exposing locusts to synthetic foods for a single stadium did not cause any significant decrease in sensilla number. The results suggest that the number of sensilla that develop in a given sensory field is influenced by the variety of chemical stimuli experienced and the chemical complexity of the environment as provided by the presence of distinct individual sources of stimulation.
The First Peptide-Gated Ion Channel
Authors: Cottrell Glen A. 
Published: April 2021

ABSTRACT
Patch-clamp experiments on the C2 neurone of Helix aspersa have shown that the neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide) directly gates a Na+ channel. The channel is amiloride-sensitive. Activation of this channel is responsible for the fast excitatory action of the peptide. Using primers based on amiloride-sensitive epithelial Na+ channels, a complete cDNA sequence (FaNaCh) was cloned and sequenced from a Helix library. The sequence is predicted to have just two membrane-spanning regions and a large extracellular loop. When expressed in Xenopus laevis oocytes, the channel responded to FMRFamide. Taken together, these data provide the first evidence for a peptide-gated ion channel. Comparison of the properties of the expressed FaNaCh with the native neuronal channel show small differences in the sensitivities to some drugs and in channel conductance. It is not yet clear whether the native channel is a homo-oligomer or comprises other subunits. The peptide FKRFamide is an effective antagonist of FMRFamide on the expressed and neuronal channels. Nucleotide sequences encoding similar channel proteins occur in neurones of species as dissimilar as man and Caenorhabditis elegans. Some channels are thought to be associated with mechano-sensation, at least one is a proton-gated channel and others may also be ligand-gated channels.
A Stereological Comparison of Villous and Microvillous Surfaces in Small Intestines of Frugivorous and Entomophagous Bats: Species, Inter-Individual and Craniocaudal Differences
Authors: Makanya A. N. , Maina J. N. , Mayhew T. M. , Tschanz S. A. , Burri P. H. 
Published: April 2021

ABSTRACT
The extents of functional surfaces (villi, microvilli) have been estimated at different longitudinal sites, and in the entire small intestine, for three species of bats belonging to two feeding groups: insect- and fruit-eaters. In all species, surface areas and other structural quantities tended to be greatest at more cranial sites and to decline caudally. The entomophagous bat (Miniopterus inflatus) had a mean body mass (coefficient of variation) of 8.9 g (5 %) and a mean intestinal length of 20 cm (6 %). The surface area of the basic intestinal tube (primary mucosa) was 9.1 cm2 (10 %) but this was amplified to 48 cm2 (13 %) by villi and to 0.13 m2 (20 %) by microvilli. The total number of microvilli per intestine was 4×1011 (20 %). The average microvillus had a diameter of 89 nm (10 %), a length of 1.1 μm (22 %) and a membrane surface area of 0.32 μm2 (31 %). In two species of fruit bats (Epomophorus wahlbergi and Lisonycteris angolensis), body masses were greater and intestines longer, the values being 76.0 g (18 %) and 76.9 g (4 %), and 73 cm (16 %) and 72 cm (7 %), respectively. Surface areas were also greater, amounting to 76 cm2 (26 %) and 45 cm2 (8 %) for the primary mucosa, 547 cm2 (29 %) and 314 cm2 (16 %) for villi and 2.7 m2 (23 %) and 1.5 m2 (18 %) for microvilli. An increase in the number of microvilli, 33×1011 (19 %) and 15×1011 (24 %) per intestine, contributed to the more extensive surface area but there were concomitant changes in the dimensions of microvilli. Mean diameters were 94 nm (8 %) and 111 nm (4 %), and mean lengths were 2.8 μm (12 %) and 2.9 μm (10 %), respectively. Thus, an increase in the surface area of the average microvillus to 0.83 μm2 (12 %) and 1.02 μm2 (11 %) also contributed to the greater total surface area of microvilli. The lifestyle-related differences in total microvillous surface areas persisted when structural quantities were normalised for the differences in body masses. The values for total microvillous surface area were 148 cm2 g−1 (20 %) in the entomophagous bat, 355 cm2 g−1 (20 %) in E. wahlbergi and 192 cm2 g−1 (17 %) in L. angolensis. This was true despite the fact that the insect-eater possessed a greater length of intestine per unit of body mass: 22 mm g−1 (8 %) versus 9–10 mm g−1 (9–10 %) for the fruit-eaters.
Contractile Properties of Obliquely Striated Muscle from the Mantle of Squid (Alloteuthis Subulata) and Cuttlefish (Sepia Officinalis)
Authors: Milligan Brian J. , Curtin N. A. , Bone Quentin 
Published: April 2021

ABSTRACT
The mechanical properties of obliquely striated muscle fibres were investigated using thin slices of mantle from squid Alloteuthis subulata and cuttlefish Sepia officinalis. Brief tetani or twitch stimuli were used as this pattern is likely to occur during jetting of the intact animal. The length–active force relationship for twitches and tetani (0.1 s, 50 Hz) was similar to that of vertebrate cross-striated fibres. Passive force at the length giving maximum tetanic force was 0.13±0.05P0 (mean ± S.E.M., N=6, where P0 is maximum isometric tetanus force) and increased steeply at longer lengths. Peak force in a brief isometric tetanus (0.2 s, 100–150 Hz) was 262±16 mN mm−2 cross-sectional area of wet tissue (N=6) for squid, and 226±19 mN mm−2 (N=7) for cuttlefish. The force–velocity relationship for isotonic shortening during twitches of squid mantle slices was a ‘double hyperbolic’ relationship as described for cross-striated fibres by Edman. Fitting Edman’s equation to the results gave: P*=1.18±0.07, Vmax=2.43±0.11Ltw s−1 and 1/G=0.69±0.13 (N=8), where P* is the intercept on the force axis expressed relative to Ptw, peak isometric twitch force, Vmax is the intercept on the velocity axis, Ltw is the length at which Ptw is produced and G is the constant expressing curvature. The large values of 1/G indicate that the force–velocity relationship is not very curved. Maximum power was produced during shortening at 0.45±0.03Ptw (N=8). Maximum power during twitch contraction was 18.3±1.7 mW g−1 wet mass or, expressed in relative units, (V/Vmax)(P/Ptw), where V is the velocity during shortening and P is the force during shortening, was 0.16±0.01 (N=8), which is higher than that of many cross-striated locomotor muscles.
Three Opsin-Encoding cDNAS from the Compound Eye of Manduca Sexta
Authors: Chase Michael R. , Bennett Ruth R. , White Richard H. 
Published: April 2021

ABSTRACT
Three distinct opsin-encoding cDNAs, designated MANOP1, MANOP2 and MANOP3, were isolated from the retina of the sphingid moth Manduca sexta. MANOP1 codes for a protein with 377 amino acid residues. It is similar in sequence to members of a phylogenetic group of long-wavelength-sensitive arthropod photopigments, most closely resembling the opsins of ants, a praying mantis, a locust and the honeybee. MANOP2 and MANOP3 opsins have 377 and 384 residues respectively. They belong to a related group of insect visual pigments that include the ultraviolet-sensitive rhodopsins of flies as well as other insect rhodopsins that are also thought to absorb at short wavelengths. The retina of Manduca sexta contains three rhodopsins, P520, P450 and P357, with absorbance peaks, respectively, at green, blue and ultraviolet wavelengths. There is evidence that MANOP1 encodes the opsin of P520. We suggest that MANOP2 encodes P357 and that MANOP3, representing a class of blue-sensitive insect photopigments, encodes P450.
Defensive Production Of Quinoline By A Phasmid Insect (Oreophoetes Peruana)
Authors: Eisner Thomas , Morgan Randy C. , Attygalle Athula B. , Smedley Scott R. , Herath Kithsiri B. , Meinwald Jerrold 
Published: April 2021

ABSTRACT
Adults and nymphs of the Peruvian stick insect Oreophoetes peruana (order Phasmatodea) have a pair of thoracic glands from which they discharge a malodorous fluid when disturbed. The secretion contains a single volatile component, quinoline. Quinoline has not been reported previously from an animal source. The compound proved repellent or topically irritant in assays with ants, spiders, cockroaches and frogs. O. peruana nymphs, at molting, do not extricate the shed cuticular lining of the glands, thereby managing not to lose their secretory supply when they cast their skin. They are able, as a consequence, to discharge secretion even while still teneral after molting.