bluuebunny/crossref_metadata_2025_split huggingface dataset:
Independent effects of heart–head distance and caudal blood pooling on blood pressure regulation in aquatic and terrestrial snakes
Authors: Seymour Roger S. , Arndt Joachim O. 
Published: March 2004

SUMMARY
Changes in orientation in a gravitational field markedly alter the patterns of blood pressure and flow in animals, especially tall or long ones such as giraffes or snakes. Vertical orientation tends to reduce blood flow and pressure in the head for two major reasons. First, the increased vertical blood column above the heart creates a gravitational hydrostatic pressure against which the heart must work. Second, expansion of dependent vessels in the lower extremities causes blood pooling and reduces return of venous blood to the heart, thereby lowering flow and pressure. For most animals, it is difficult to separate these two effects, but snakes offer the possibility of bending the animal in the region of the heart and manipulating the two ends of the body independently. We studied baroregulatory responses in terrestrial pythons (Liasis fuscus) and aquatic file snakes (Acrochordus arafurae) by tilting only the front or rear parts and then the whole animal. Changes in head blood pressure during partial tilts added up to the change during full tilt. The vertical distance to the head had twice as much influence on head blood pressure than did blood pooling in the pythons and four times as much in file snakes. This accounts for the cephalad location of the heart in terrestrial species compared with aquatic ones.
Nitric oxide control of the dorsal aorta and the intestinal vein of the Australian short-finned eel Anguilla australis
Authors: Jennings Brett L. , Broughton Brad R. S. , Donald John A. 
Published: March 2004

SUMMARY
This study investigated the mechanisms by which nitric oxide (NO) regulates the dorsal aorta and the intestinal vein of the Australian short-finned eel Anguilla australis. NADPH diaphorase histochemistry and immunohistochemistry using a mammalian endothelial nitric oxide synthase (NOS)antibody could not demonstrate NOS in the endothelium of either blood vessel;however, NOS could be readily demonstrated in the endothelium of the rat aorta that was used as a control. Both blood vessels contained NADPH diaphorase positive nerve fibres and nerve bundles, and immunohistochemistry using a neural NOS antibody showed a similar distribution of neural NOS immunoreactivity in the perivascular nerves. In vitro organ bath physiology showed that a NO/soluble guanylyl cyclase (GC) system is present in the dorsal aorta and the intestinal vein, since the soluble GC inhibitor oxadiazole quinoxalin-1 (ODQ; 10–5 mol l–1)completely abolished the vasodilatory effect of the NO donor, sodium nitroprusside (SNP; 10–4 mol l–1). In addition, nicotine (3×10–4 mol l–1)mediated a vasodilation that was not affected by removal of the endothelium. The nicotine-mediated dilation was blocked by the NOS inhibitor, Nω-nitro-l-arginine (l-NNA;10–4 mol l–1), and ODQ(10–5 mol l–1). More specifically, the neural NOS inhibitor, Nω-propyl-l-arginine(10–5 mol l–1), significantly decreased the dilation induced by nicotine (3×10–4 mol l–1). Furthermore, indomethacin (10–5 mol l–1) did not affect the nicotine-mediated dilation,suggesting that prostaglandins are not involved in the response. Finally, the calcium ionophore A23187 (3×10–6 mol l–1) caused an endothelium-dependent dilation that was abolished in the presence of indomethacin. We propose the absence of an endothelial NO system in eel vasculature and suggest that neurally derived NO contributes to the maintenance of vascular tone in this species. In addition,we suggest that prostaglandins may act as endothelially derived relaxing factors in A. australis.
Effect of β-adrenergic stimulation on the relationship between membrane potential, intracellular [Ca2+] and sarcoplasmic reticulum Ca2+ uptake in rainbow trout atrial myocytes
Authors: Llach Anna , Huang Jingbo , Sederat Franklin , Tort Lluis , Tibbits Glen , Hove-Madsen Leif 
Published: March 2004

SUMMARY
Long depolarizations cause a steady tonic contraction and induce sarcoplasmic reticulum (SR) Ca2+-uptake in trout atrial myocytes. Simultaneous measurements of cytosolic [Ca2+]([Ca2+]i) and whole membrane current showed an elevated[Ca2+]i throughout the depolarization. Rapid caffeine(Caf) applications at –80 mV before and after a long depolarization were used to determine SR Ca2+ loading and its dependency on membrane potential and [Ca2+]i during depolarization. Following a 10 s depolarization, the maximal SR Ca2+ load was 597 μmol l–1 and loading was half-maximal at –12 mV. Theβ-adrenergic agonist isoproterenol (ISO) did not affect the maximal SR Ca2+ loading but shifted the potential for half-maximal loading by–26 mV. Following a 3 s depolarization, the maximal SR Ca2+uptake rate (V̇max) was 418μmol l–1 s–1 in control conditions. ISO did not affect V̇max, but significantly lowered the average free Ca2+ transient during the depolarization and shifted the K0.5 for the relationship between SR Ca2+ uptake and [Ca2+]i from 1.27 in control to 0.8 μmol l–1 with ISO. Following repetitive 200 ms depolarizations, ISO increased the l-type Ca2+current (ICa) amplitude by 91±29% and the peak Ca2+ transient by 41±10%, and decreased the half life of the Ca2+ transient from 151±12 to 111±6 ms. Using the relationship between [Ca2+]i and SR Ca2+uptake to calculate the total SR Ca2+ uptake during a Ca2+ transient elicited by a 200 ms depolarization, a significant increase in the SR Ca2+ uptake from 37±6 μmol l–1 in control to 68±4 μmol l–1with ISO was seen. When normalized to the total Ca2+ transport the contribution of the SR was not significantly different in the absence(35±6%) or presence of ISO (41±4%). Exposure of cells to ISO and low extracellular [Ca2+] increased ICa by 67±40%(N=5) but significantly reduced SR Ca2+ uptake at membrane potentials above –30 mV. Together, these results suggest that (i) ISO has a stimulatory effect on the SR Ca2+ pump that may contribute to the faster decay of the Ca2+ transient, and (ii) the relative contribution of the SR to the Ca2+ removal during relaxation is not altered by ISO in trout atrial myocytes.
Contribution of eye retraction to swallowing performance in the northern leopard frog,Rana pipiens
Authors: Levine Robert P. , Monroy Jenna A. , Brainerd Elizabeth L. 
Published: March 2004

SUMMARYMost anurans retract and close their eyes repeatedly during swallowing. Eye retraction may aid swallowing by helping to push food back toward the esophagus, but this hypothesis has never been tested. We used behavioral observations, cineradiography, electromyography and nerve transection experiments to evaluate the contribution of eye retraction to swallowing in the northern leopard frog, Rana pipiens. Behavioral observations of frogs feeding on 1.5 cm long crickets reveal a high degree of variability in eye retraction and swallowing. Eye retraction can occur bilaterally or unilaterally, and both swallowing movements and eye retraction can occur separately as well as together. During swallowing, cineradiography shows that the eyes and associated musculature retract well into the oropharynx and appear to make contact with the prey item. This contact appears to help push the prey toward the esophagus, and it may also serve to anchor the prey for tongue-based transport. Electromyographic recordings confirm strong activity in the retractor bulbi muscles during eye retraction. After bilateral denervation of the retractor bulbi, frogs maintain the ability to swallow but show a 74% increase in the number of swallows required per cricket (from a mean of 2.3 swallows to a mean of 4.0 swallows per cricket). Our results indicate that, in Rana pipiens feeding on medium-sized crickets, eye retraction is an accessory swallowing mechanism that assists the primary tongue-based swallowing mechanism.
Passive tools for enhancing muscle-driven motion and locomotion
Authors: Minetti Alberto E. 
Published: March 2004

SUMMARY
Musculo–skeletal systems and body design in general have evolved to move effectively and travel in specific environments. Humans have always aspired to reach higher power movement and to locomote safely and fast, even through unfamiliar media (air, water, snow, ice). For the last few millennia,human ingenuity has led to the invention of a variety of passive tools that help to compensate for the limitations in their body design. This Commentary discusses many of those tools, ranging from halteres used by athletes in ancient Greece, to bows, skis, fins, skates and bicycles, which are characterised by not supplying any additional mechanical energy, thus retaining the use of muscular force alone. The energy cascade from metabolic fuel to final movement is described, with particular emphasis on the steps where some energy saving and/or power enhancement is viable. Swimming is used to illustrate the efficiency breakdown in complex locomotion, and the advantage of using fins. A novel graphical representation of world records in different types of terrestrial and aquatic locomotion is presented, which together with a suggested method for estimating their metabolic cost (energy per unit distance), will illustrate the success of the tools used.
Stick insect locomotion in a complex environment: climbing over large gaps
Authors: Blaesing Bettina , Cruse Holk 
Published: March 2004

SUMMARYIn a complex environment, animals are challenged by various types of obstacles. This requires the controller of their walking system to be highly flexible. In this study, stick insects were presented with large gaps to cross in order to observe how locomotion can be adapted to challenging environmental situations. Different approaches were used to investigate the sequence of gap-crossing behaviour. A detailed video analysis revealed that gap-crossing behaviour resembles modified walking behaviour with additional step types. The walking sequence is interrupted by an interval of exploration, in which the insect probes the gap space with its antennae and front legs. When reaching the gap, loss of contact of an antenna with the ground does not elicit any observable reactions. In contrast, an initial front leg step into the gap that often follows antennal `non-contact' evokes slowing down of stance velocity. An ablation experiment showed that the far edge of the gap is detected by tactile antennal stimulation rather than by vision. Initial contact of an antenna or front leg with the far edge of the gap represents a `point of no return', after which gap crossing is always successfully completed. Finally,flow chart diagrams of the gap-crossing sequence were constructed based on an ethogram of single elements of behaviour. Comparing flow charts for two gap sizes revealed differences in the frequency and succession of these elements,especially during the first part of the sequence.
Take-off mechanics in hummingbirds (Trochilidae)
Authors: Tobalske Bret W. , Altshuler Douglas L. , Powers Donald R. 
Published: March 2004

SUMMARYInitiating flight is challenging, and considerable effort has focused on understanding the energetics and aerodynamics of take-off for both machines and animals. For animal flight, the available evidence suggests that birds maximize their initial flight velocity using leg thrust rather than wing flapping. The smallest birds, hummingbirds (Order Apodiformes), are unique in their ability to perform sustained hovering but have proportionally small hindlimbs that could hinder generation of high leg thrust. Understanding the take-off flight of hummingbirds can provide novel insight into the take-off mechanics that will be required for micro-air vehicles. During take-off by hummingbirds, we measured hindlimb forces on a perch mounted with strain gauges and filmed wingbeat kinematics with high-speed video. Whereas other birds obtain 80–90% of their initial flight velocity using leg thrust,the leg contribution in hummingbirds was 59% during autonomous take-off. Unlike other species, hummingbirds beat their wings several times as they thrust using their hindlimbs. In a phylogenetic context, our results show that reduced body and hindlimb size in hummingbirds limits their peak acceleration during leg thrust and, ultimately, their take-off velocity. Previously, the influence of motivational state on take-off flight performance has not been investigated for any one organism. We studied the full range of motivational states by testing performance as the birds took off: (1) to initiate flight autonomously, (2) to escape a startling stimulus or (3) to aggressively chase a conspecific away from a feeder. Motivation affected performance. Escape and aggressive take-off featured decreased hindlimb contribution (46% and 47%,respectively) and increased flight velocity. When escaping, hummingbirds foreshortened their body movement prior to onset of leg thrust and began beating their wings earlier and at higher frequency. Thus, hummingbirds are capable of modulating their leg and wingbeat kinetics to increase take-off velocity.
Physiological, biochemical and morphological indicators of osmoregulatory stress in `California' Mozambique tilapia (Oreochromis mossambicus×O. urolepis hornorum) exposed to hypersaline water
Authors: Sardella Brian A. , Matey Victoria , Cooper Jill , Gonzalez Richard J. , Brauner Colin J. 
Published: March 2004

SUMMARYThe salinity tolerance of the `California' Mozambique tilapia(Oreochromis mossambicus × O. urolepis hornorum), a current inhabitant of the hypersaline Salton Sea in California, USA, was investigated to identify osmoregulatory stress indicators for possible use in developing a model of salinity tolerance. Seawater-acclimated (35 g l–1) tilapia hybrids were exposed to salinities from 35–95 g l–1, using gradual and direct transfer protocols, and physiological (plasma osmolality, [Na+],[Cl–], oxygen consumption, drinking rate, hematocrit, mean cell hemoglobin concentration, and muscle water content), biochemical(Na+, K+-ATPase) and morphological (number of mature,accessory, immature and apoptotic chloride cells) indicators of osmoregulatory stress were measured. Tilapia tolerated salinities ranging from 35 g l–1 to 65 g l–1 with little or no change in osmoregulatory status; however, in fish exposed to 75–95 g l–1 salinity, plasma osmolality, [Na+],[Cl–], Na+, K+-ATPase, and the number of apoptotic chloride cells, all showed increases. The increase in apoptotic chloride cells at salinities greater than 55 g l–1, prior to changes in physiological and biochemical parameters, indicates that it may be the most sensitive indicator of osmoregulatory stress. Oxygen consumption decreased with salinity, indicating a reduction in activity level at high salinity. Finally, `California' Mozambique tilapia have a salinity tolerance similar to that of pure Mozambique tilapia; however, cellular necrosis at 95 g l–1 indicates they may be unable to withstand extreme salinities for extended periods of time.
Ventilatory compensation of the alkaline tide during digestion in the snakeBoa constrictor
Authors: Andrade Denis V. , De Toledo Luis Felipe , Abe Augusto S. , Wang Tobias 
Published: March 2004

SUMMARYThe increased metabolic rate during digestion is associated with changes in arterial acid–base parameters that are caused by gastric acid secretion(the `alkaline tide'). Net transfer of HCl to the stomach lumen causes an increase in plasma HCO3– levels, but arterial pH does not change because of a ventilatory compensation that counters the metabolic alkalosis. It seems, therefore, that ventilation is controlled to preserve pH and not PCO2 during the postprandial period. To investigate this possibility, we determined arterial acid–base parameters and the metabolic response to digestion in the snake Boa constrictor, where gastric acid secretion was inhibited pharmacologically by oral administration of omeprazole.The increase in oxygen consumption of omeprazole-treated snakes after ingestion of 30% of their own body mass was quantitatively similar to the response in untreated snakes, although the peak of the metabolic response occurred later (36 h versus 24 h). Untreated control animals exhibited a large increase in arterial plasma HCO3– concentration of approximately 12 mmol l–1, but arterial pH only increased by 0.12 pH units because of a simultaneous increase in arterial PCO2 by about 10 mmHg. Omeprazole virtually abolished the changes in arterial pH and plasma HCO3– concentration during digestion and there was no increase in arterial PCO2. The increased arterial PCO2 during digestion is not caused, therefore, by the increased metabolism during digestion or a lower ventilatory responsiveness to ventilatory stimuli during a presumably relaxed state in digestion. Furthermore, the constant arterial PCO2, in the absence of an alkaline tide, of omeprazole-treated snakes strongly suggests that pH rather than PCO2 normally affects chemoreceptor activity and ventilatory drive.
The occurrence of two types of hemopexin-like protein in medaka and differences in their affinity to heme
Authors: Hirayama Makoto , Kobiyama Atsushi , Kinoshita Shigeharu , Watabe Shugo 
Published: March 2004

SUMMARY
Full-length cDNA clones encoding two types of hemopexin-like protein,mWap65-1 and mWap65-2, were isolated from the HNI inbred line of medaka Oryzias latipes. The deduced amino acid sequence of mWap65-2 resembled mammalian hemopexins more closely than that of mWap65-1. Histidine residues required for the high affinity of hemopexins for hemes were conserved in mWap65-2, but not in mWap65-1. Surprisingly, mWap65-1, but not mWap65-2,showed heme-binding ability as revealed by hemin–agarose affinity chromatography, even though mWap65-1 lacked the essential histidine residues. Furthermore, RT-PCR analysis of different tissues demonstrated that the transcripts of mWap65-2 were restricted to liver, whereas those of mWap65-1 were found in various tissues including liver, eye, heart and brain. Quantitative RT-PCR revealed that transcripts of mWap65-2were expressed earlier than those of mWap65-1 during ontogeny. However, the accumulated mRNA levels of both mWap65-1 and mWap65-2 did not differ significantly in fish acclimated to either 10°C or 30°C for 5 weeks. These characteristics suggest that the two proteins have different physiological functions and that mWap65-2 is not a hemopexin.
Structure–function analysis of the cysteine string protein inDrosophila: cysteine string, linker and C terminus
Authors: Arnold Christine , Reisch Natascha , Leibold Christian , Becker Sonja , Prüfert Kristina , Sautter Kerstin , Palm Dieter , Jatzke Susanne , Buchner Sigrid , Buchner Erich 
Published: March 2004

SUMMARYCysteine string proteins (CSPs) are conserved secretory vesicle proteins involved in regulating neurotransmitter and peptide release. While the function of the J-domain has been studied in detail, little is known about other conserved regions. We have constructed mutant genes coding for proteins with modified cysteine string, linker region or C terminus and transformed them into Csp null-mutant Drosophila. In the living animal,mutated CSP lacking all cysteines fails to associate with membranes, does not concentrate in synaptic terminals, and cannot rescue adult temperature-sensitive paralysis and short life span, both prominent null mutant phenotypes. A mutant protein with 5 instead of 11 string cysteines appears to be normally targeted but cannot rescue paralysis at 37°C. We propose that the cysteine string, in addition to its role in targeting, may be essential for a function of CSP that is dependent on the number of cysteines in the string. A deletion in the linker region or the C terminus does not affect CSP targeting, and function in adults is only marginally impaired.
Effect of serotonin on ciliary beating and intracellular calcium concentration in identified populations of embryonic ciliary cells
Authors: Doran Shandra A. , Koss Ron , Tran Cam Ha , Christopher Kimberly J. , Gallin Warren J. , Goldberg Jeffrey I. 
Published: March 2004

SUMMARYEmbryos of the pond snail Helisoma trivolvis express three known subtypes of ciliary cells on the surface of the embryo early in development:pedal, dorsolateral and scattered single ciliary cells (SSCCs). The pedal and dorsolateral ciliary cells are innervated by a pair of serotonergic sensory-motor neurons and are responsible for generating the earliest whole-animal behavior, rotation within the egg capsule. Previous cell culture studies on unidentified ciliary cells revealed that serotonin(5-hydroxytryptamine; 5-HT) produces a significant increase in the ciliary beat frequency (CBF) in a large proportion of ciliary cells. Both Ca2+ influx and a unique isoform of protein kinase C (PKC) were implicated in the signal transduction pathway underlying the cilio-excitatory response to 5-HT. The goal of the present study was to characterize the anatomical and physiological differences between the three known populations of superficial ciliary cells. The pedal and dorsolateral ciliary cells shared common structural characteristics, including flat morphology, dense cilia and lateral accessory ciliary rootlets. By contrast, the SSCCs had a cuboidal morphology, reduced number of cilia, increased ciliary length and absence of lateral accessory rootlets. In cultures containing unidentified ciliary cells,the calcium/calmodulin-dependent enzyme inhibitor calmidazolium (2 μmol l–1) blocked the stimulatory effect of 5-HT (100 μmol l–1) on CBF. In addition, 50% of unidentified cultured cells responded to 5-HT (100 μmol l–1) with an increase in[Ca2+]i. To facilitate the functional analyses of the individual populations, we developed a method to culture identified ciliary subtypes and characterized their ciliary and calcium responses to 5-HT. In cultures containing either pedal or dorsolateral ciliary cells, 5-HT (100μmol l–1) produced a rapid increase in CBF and a slower increase in [Ca2+]i in all cells examined. By contrast,the CBF and [Ca2+]i of SSCCs were not affected by 100μmol l–1 5-HT. Immunohistochemistry for two putative 5-HT receptors recently cloned from Helisoma revealed that pedal and dorsolateral ciliary cells consistently express the 5-HT1Helprotein. Intense 5-HT7Hel immunoreactivity was observed in only a subset of pedal and dorsolateral ciliary cells. Cells neighboring the SSCCs,but not the ciliary cells themselves, expressed 5-HT1Hel and 5-HT7Hel immunoreactivity. These data suggest that the pedal and dorsolateral ciliary cells, but not the SSCCs are a homogeneous physiological subtype that will be useful for elucidating the signal transduction mechanisms underlying 5-HT induced cilio-excitation.
Renal stone analysis: why and how?
Authors: Kasidas G P , Samuell C T , Weir T B 
Published: March 2004

Upper urinary tract stone disease is widespread in the developed world. On both clinical and economic grounds it is now accepted that evidence-based medical intervention is the only approach likely to make a significant impact on the incidence, and more importantly, the recurrence rates of this disease. Targeted medical prophylaxis requires reliable information on stone type which, when combined with relevant blood and urine analyses, allows identification of treatable risk factors. Data from an external quality assurance scheme indicate that stone analysis is poorly performed in many laboratories, and it is probable that this results in ill-informed patterns of investigation, inappropriate therapy, missed diagnoses of rarer causative disorders and wasteful further investigation of 'non-renal' stone artefacts. Renal stone analysis is a specialist investigation requiring appropriate analytical and interpretative expertise if the information is to be used to enhance patient care. For those laboratories not able to offer this, for whatever reason, referral is the only defensible approach to service provision. The methods currently employed in many departments have no place in modern clinical biochemistry practice.