bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature dependence of cardiac performance in the lobsterHomarus americanus
Authors: Worden Mary Kate , Clark Christine M. , Conaway Mark , Qadri Syed Aman 
Published: March 2006

SUMMARYThe lobster Homarus americanus inhabits ocean waters that vary in temperature over a 25°C range, depending on the season and water depth. To investigate whether the lobster heart functions effectively over a wide range of temperatures we examine the temperature dependence of cardiac performance of isolated lobster hearts in vitro. In addition, we examined whether modulation of the heart by serotonin depends on temperature. The strength of the heartbeat strongly depends on temperature, as isolated hearts are warmed from 2 to 22°C the contraction amplitude decreases by greater than 60%. The rates of contraction and relaxation of the heart are most strongly temperature dependent in the range from 2 to 4°C but become temperature independent at warmer temperatures. Heart rates increase as a function of temperature both in isolated hearts and in intact animals, however hearts in intact animals beat faster in the temperature range of 12–20°C. Interestingly, acute Q10 values for heart rate are similar in vivo and in vitro over most of the temperature range, suggesting that temperature dependence of heart rate arises mainly from the temperature effects on the cardiac ganglion. In contrast to earlier reports suggesting that the strength and the frequency of the lobster heartbeat are positively correlated, we observe no consistent relationship between these parameters as they change as a function of temperature. Stroke volume decreases as a function of temperature. However, the opposing temperature-dependent increase in heart rate partially compensates to produce a relationship between cardiac output and temperature in which cardiac output is maximal at 10°C and significantly decreases above 20°C. Serotonin potentiates contraction amplitude and heart rate in a temperature-independent manner. Overall, our results show that although the parameters underlying cardiac performance show different patterns of temperature dependence, cardiac output remains relatively constant over most of the wide range of environmental temperatures the lobster inhabits in the wild.
Glycerol production in rainbow smelt (Osmerus mordax) may be triggered by low temperature alone and is associated with the activation of glycerol-3-phosphate dehydrogenase and glycerol-3-phosphatase
Authors: Driedzic William R. , Clow Kathy A. , Short Connie E. , Ewart K. Vanya 
Published: March 2006

SUMMARYRainbow smelt (Osmerus mordax) accumulate high levels of glycerol in winter that serves as an antifreeze. Fish were subjected to controlled decreases in water temperature and levels of plasma glycerol, liver metabolites and liver enzymes were determined in order to identify control mechanisms for the initiation of glycerol synthesis. In two separate experiments, decreases in temperature from 8°C to 0°C over a period of 10–11 days resulted in increases in plasma glycerol from levels of less than 4 mmol l–1 to approximate mean levels of 40 (first experiment) and 150 mmol l–1 (second experiment). In a third experiment, decreases in temperature to –1°C resulted in plasma glycerol levels approaching 500 mmol l–1. The accumulation of glycerol could be driven in either December or March, thus eliminating decreasing photoperiod as a necessary cue for glycerol accumulation. Glycerol accumulation in plasma was associated with changes in metabolites in liver leading to increases in the mass action ratio across the reactions catalyzed by glycerol-3-phosphate dehydrogenase (GPDH) and glycerol-3-phosphatase(G3Pase). The maximal, in vitro activity of GPDH, increased twofold in association with a sharp increase in plasma glycerol level. The metabolite levels and enzyme activities provide complementary evidence that GPDH is a regulatory site in the low temperature triggered synthesis of glycerol. Indirect evidence, based on calculated rates of in vivo glycerol production by liver, suggests that G3Pase is a potential rate-limiting step. As well, transient increases in glyceraldehyde-3-phosphate dehydrogenase and alanine aminotransferase suggest that these sites are components of a suite of responses, in rainbow smelt liver, induced by low temperature.
Carotenoid availability in diet and phenotype of blue and great tit nestlings
Authors: Biard Clotilde , Surai Peter F. , Møller Anders P. 
Published: March 2006

SUMMARYCarotenoids are biologically active pigments of crucial importance for the development of avian embryos and nestlings. Thus parental ability to provide nestlings with a carotenoid-rich diet may enhance offspring fitness. However,very little is known about the possible effects of carotenoid availability in the diet on growing nestlings in natural populations. We experimentally manipulated dietary intake of carotenoids by nestlings of two closely related passerine species, the great tit Parus major and the blue tit Parus caeruleus, and measured nestling antioxidants, body condition,immunity and plumage colour. There was no detectable increase in plasma carotenoids after treatment in carotenoid-fed nestlings of either species despite regular supply of dietary carotenoids. However, in carotenoid-fed blue tit nestlings, plasma vitamin E concentration increased with plasma carotenoid concentration, while that was not the case for control nestlings. In both species, there was no significant effect of carotenoid supply on immune function. Carotenoid supplementation enhanced yellow feather colour in great tit nestlings only. In both species a strong effect of carotenoid supply was found on body condition with an increase in body mass for small carotenoid-fed nestlings compared to similarly sized control nestlings. Dietary availability of carotenoids may thus have important fitness consequences for tits. We hypothesise that the difference in effect of dietary carotenoids on the two species is due to relatively larger clutch size and higher growth rates of blue tits compared to great tits, leading to blue tit nestlings being more in need of carotenoids for antioxidant function than great tit nestlings.
Hydration of rainbow trout oocyte during meiotic maturation andin vitroregulation by 17,20β-dihydroxy-4-pregnen-3-one and cortisol
Authors: Milla Sylvain , Jalabert Bernard , Rime Helene , Prunet Patrick , Bobe Julien 
Published: March 2006

SUMMARYAlthough oocytes of many teleost fish, especially marine species, are subjected to a hydration process during meiotic maturation, which leads to an important volume increase, no noticeable hydration of the preovulatory oocyte has ever been reported in rainbow trout (Oncorhynchus mykiss). In the present study, oocyte water content and dry mass were monitored using consecutive samples taken in vivo from the same female rainbow trout,from 4–5 days prior to ovulation to up to 7 days post-ovulation. In addition, yolk protein electrophoretic patterns were compared between oocytes sampled prior to germinal vesicle breakdown (GVBD) and unfertilized eggs. Furthermore, the effect of the maturation-inducing steroid(17,20β-dihydroxy-4-pregnen-3-one, 17,20β-P), cortisol and 11-deoxycorticosterone (DOC) on oocyte dry and wet masses, as well as GVBD occurrence was assessed in vitro. Finally, mRNA expression profiles of glucocorticoid and mineralocorticoid receptors as well as 11β-hydroxysteroid dehydrogenase (11β-HSD) were monitored in the periovulatory ovary by real-time PCR. Both in vivo and in vitro data showed, for the first time in rainbow trout, that a significant oocyte hydration occurs during oocyte maturation. In addition, an intra-oocyte dry matter increase was reported in vivo during the periovulatory period. However, yolk protein migration patterns were similar in preGVBD oocytes and unfertilized eggs, suggesting that no or little yolk proteolysis occurs during oocyte maturation. We also showed that oocyte hydration can be induced in vitro by 17,20β-P and cortisol but not by DOC. In contrast, GVBD was only observed after 17,20β-P stimulation. Finally, real-time PCR analysis showed an up-regulation of 11β-HSD and glucocorticoid receptor 2 transcripts in the ovary at the time of oocyte maturation. Together, these results suggest that cortisol could participate in the control of oocyte hydration and possibly in other periovulatory ovarian functions.
Seismic signal production in a wolf spider: parallelversusserial multi-component signals
Authors: Elias Damian O. , Lee Norman , Hebets Eileen A. , Mason Andrew C. 
Published: March 2006

SUMMARYAnimal signals can consist of multiple parts within or across sensory modalities (multi-component signals or multimodal signals). While recent work has focused on multimodal signals, the production, processing and evolution of multi-component signals has received considerably less attention. Here, using synchronous high-speed video and laser vibrometer recordings followed by experimental manipulations of putative sound-producing structures, we explored the mechanisms of seismic signal production in the courtship display of Schizocosa stridulans Stratton. Two types of seismic courtship signals were observed: `rev' and `idle' signals. Revs consist of a high-frequency component produced by flexions of the male pedipalp(stridulation) simultaneous with a low-frequency component produced by movements of the abdomen (tremulation). This multi-component signal is produced by independent structures and represents a parallel multi-component display. By contrast, idle displays consist of a high-intensity component produced by drumming of the forelegs on the substrate (percussion) followed by a high-frequency component produced by flexions of the male pedipalp(stridulation). While the components of the idle display are also produced by independent structures, the leg drumming and palp flexions occur serially and do not overlap in time. We discuss the selective pressures that may drive the evolution of multiple sound-producing structures as well as the selective pressures that drive the evolution of parallel versus serial multi-component signals.
Chronic hypercapnia modulates respiratory-related central pH/CO2 chemoreception in an amphibian,Bufo marinus
Authors: Gheshmy Afshan , Vukelich Robert , Noronha Angelo , Reid Stephen G. 
Published: March 2006

SUMMARYAnuran amphibians have multiple populations of pH/CO2-sensitive respiratory-related chemoreceptors. This study examined in cane toads(Bufo marinus) whether chronic hypercapnia (CHC) altered the pH/CO2 sensitivity of central respiratory-related chemoreceptors in vitro and whether CHC altered the acute hypercapnic ventilatory response (HCVR; 5% CO2) in vivo. Toads were exposed to CHC(3.5% CO2) for 9 days. In vitro brainstem–spinal cord preparations were used to examine central respiratory-related pH/CO2 chemosensitivity. CHC augmented in vitro fictive breathing as the pH of the superfusate was lowered from 8.2 to 7.4. Midbrain transection in vitro (at a level known to reduce the clustering of breaths) did not alter this augmentation. In vivo, CHC did not alter the acute HCVR but midbrain transection changed the breathing pattern and increased the overall level of ventilation. CHC did not alter the effect of olfactory CO2 chemoreceptor denervation on the acute HCVR in vivo but did alter the response when returned to normal air. The results indicate that CHC increases the response of central pH/CO2chemoreceptors to changes in cerebrospinal fluid pH in vitro yet this increase is not manifest as an increase in the HCVR in vivo.
How much stress do researchers inflict on their study animals? A case study using a scincid lizard, Eulamprus heatwolei
Authors: Langkilde Tracy , Shine Richard 
Published: March 2006

SUMMARY
Research on live vertebrates is regulated by ethics committees, who prohibit `excessively stressful' procedures. That judgment is based on intuition – a notoriously unreliable criterion when dealing with animals phylogenetically distant from humans. To objectively evaluate the stress imposed by research practices, we measured plasma corticosterone levels in lizards (Eulamprus heatwolei Wells & Wellington, Scincidae). Some procedures (handling and measuring, toe-clipping for identification, exposure to predator scent) did not induce significant increases in corticosterone levels, suggesting that these stimuli generated relatively little stress. However, other stimuli (testing locomotor speed, microchip implantation, blood sampling, an unfamiliar enclosure, tail autotomy, exposure to a heterospecific lizard) were more stressful, with corticosterone levels increasing only transiently in some treatments (&lt;2 h for tail autotomy), but persisting much longer in others (14 days for microchip implantation). Overall, our data suggest that the levels of stress induced by routine laboratory procedures are no greater than those often experienced by lizards in nature; but that intuition provides a poor basis for evaluating the levels of stress induced by research. For example, toe-clipping is often criticized and sometimes banned;but our data suggest that this method is actually less stressful than the technique frequently recommended to replace it on ethical grounds (microchip implantation). Toe-clipping also was less stressful than superficially trivial manipulations such as housing the animal in an unfamiliar enclosure. More generally, we urge researchers to seek objective information on the effects of their activities on research subjects, rather than relying upon subjectivity and anthropomorphism in making these evaluations.
Differential parental nutrient allocation in two congeneric pipefish species (Syngnathidae:Syngnathusspp.)
Authors: Ripley Jennifer L. , Foran Christy M. 
Published: March 2006

SUMMARYMale seahorses and pipefishes of the family Syngnathidae are heralded for their unique brood pouch structures for incubating embryos. There are three general types of brood pouch with increasing complexity: simple ventral gluing, two pouch flaps and a completely sealed sac. The diversity of functional roles within a type in providing nutrition, aeration and protection to offspring is unknown. Here we reveal significant differences in parental nutrient allocation to embryos for two closely related, sympatric pipefishes with similar brood pouch structure. We document differences in embryo attachment, depletion of pouch fluid nutrients over development and egg nutrient partitioning between Syngnathus floridae and Syngnathus fuscus. In S. fuscus, females produce nutritionally poor eggs and the males implant developing embryos in the brood pouch adjacent to blood vessels. A female-biased breeding population was observed, supporting the hypothesis that the cost of male parental care is high in this species. The loose connection between eggs and brood pouch tissues and the appearance of undeveloped eggs and lipid droplets in the pouch of S. floridae males suggest this species utilizes nutrient-rich eggs produced by females as nurse eggs to supplement embryonic development. A balanced sex-ratio for S. floridae further supports more equal parental contribution. This comparison provides evidence of a decline in female gametic investment and reveals the rapid diversification of syngnathid brood pouch function. Our results indicate gross classification of brooding structures into one of the three general pouch types does not predict the energetic investment of males in parental care. But rather, physiological characterization of the relative investment by each sex to offspring is essential to understanding the functional significance of the brood pouch.
Metabolic and blood gas dependence on digestive state in the Savannah monitor lizardVaranus exanthematicus: an assessment of the alkaline tide
Authors: Hartzler L. K. , Munns S. L. , Bennett A. F. , Hicks J. W. 
Published: March 2006

SUMMARYA large alkaline tide (up to 20 mmol l–1 increase in bicarbonate concentration [HCO3–] with an accompanied increase in blood pH) has previously been reported for some carnivorous reptiles within 24 h after ingesting a large meal. This phenomenon has been attributed to the secretion of large amounts of H+ ions into the stomach, which is required for digestion of large prey items. To test the generality of this phenomenon in carnivorous reptiles, this study quantified the metabolic and acid–base status of the Savannah monitor lizard, Varanus exanthematicus, during digestion at 35°C. Following a meal of approximately 10% of body mass, V̇O2 and V̇CO2 were measured continuously and arterial pH, blood gases and strong ions were measured every 8 h for 5 days. During peak digestion (24 h post feeding), V̇O2 and V̇CO2 increased to approximately threefold fasting values(V̇O2, 0.95–2.57 ml min–1 kg–1; V̇CO2 0.53–1.63 ml min–1 kg–1) while respiratory exchange ratio(R) remained constant (0.62–0.73). During digestion, arterial PCO2 increased (from 4.6 kPa to 5.8 kPa), and[HCO3–] also increased (from 24.1 mmol l–1 to 40.3 mmol l–1). In contrast to early studies on crocodilians, arterial pH in V. exanthematicus remained relatively stable during digestion (7.43–7.56). Strong ions contributed little to the acid–base compensation during the alkalosis. Collectively the data indicate that the metabolic alkalosis associated with H+secretion (as indicated by increased plasma bicarbonate) is partially compensated by a respiratory acidosis.
Developmentally determined attenuation in circadian rhythms links chronobiology to social organization in bees
Authors: Yerushalmi Shai , Bodenhaimer Shalev , Bloch Guy 
Published: March 2006

SUMMARY
We investigated labor-related plasticity in the circadian clock of the bumblebee Bombus terrestris. Bumblebee workers vary enormously in body size, and we found that size, division of labor, and diurnal rhythms in activity are correlated in B. terrestris colonies. Large workers typically perform foraging activities with strong diurnal rhythms and low activity at night, whereas small bees typically care for (nurse) brood around the clock with weak or no diurnal rhythms. Under constant laboratory conditions, circadian rhythms in locomotor activity were weaker, less stable,and developed at a later age in small (nurse-size) bees compared to their larger (forager-size) sisters. Under a light:dark illumination regime, many small bees, particularly at a young age, were active during the dark phase,fewer small bees developed rhythms, and they did so later compared to large bees. Taken together these findings reveal naturally occurring attenuation or suppression in the circadian clock of small bees that is determined during pre-adult development. This deficiency in clock function, however, does not result in pathology but rather appears to be functionally significant, because it is associated with around-the-clock brood care activity and therefore apparently improves divisions of labor and colony efficiency. This in turn suggests that variation in social biology influences traits of the circadian clock.
α-Fluorination of Sulfoxides Bearing α-Hydrogens by Molecular Fluorine. A Novel Method for the Synthesis of α-Fluorosulfones
Authors: Chiba Jun , Sugihara Takumichi , Kaneko Chikara 
Published: March 2006

Abstract
Direct formation of α-fluorosulfones from sulfoxides bearing α-hydrogens merely by reacting molecular fluorine (5% F2/N2) is reported and a possible mechanism for this novel α-fluorination reaction is proposed.
Stereoselective Ring Opening of Geometrically Constrained Oxaziridines by Photosensitized Electron Transfer
Authors: Iwano Yasunori , Kawamura Yasuhiko , Horie Tokunaru 
Published: March 2006

Abstract
Stereoselective isomerizations of geometrically constrained oxaziridines 1 to the corresponding nitrones 2 could be induced by 9,10-dicyanoanthracene-photosensitized electron transfer.
Preparation and Properties of π-Conjugated Poly(1,10-phenanthroline-3,8-diyl)
Authors: Saitoh Yutaka , Yamamoto Takakazu 
Published: March 2006

Abstract
Poly(1,10-phenanthroline-3,8-diyl) has been synthesized by dehalogenation polycondensation of 3,8-dibromo-1,10-phenanthroline with a zerovalent nickel complex. The polymer has molecular weight of 6800 and is electrochemically reduced at Epa = 2.24 V vs Ag/Ag+.
Setting Quality Expectations When Entering a Market: What Should the Promise Be?
Authors: Kopalle Praveen K. , Lehmann Donald R. 
Published: March 2006

This paper examines optimal advertised quality, actual quality, and price for a firm entering a market. It develops a two-period model where advertised quality influences expectations, and hence trial and the gap between actual quality and expectations determines satisfaction, which in turn impacts second-period sales. In such situations a company makes a choice between advertising high quality and getting trial, but little repeat; and advertising low quality and getting low trial, but high repeat. Results are derived by numerical methods, as well as analytically for a special case of the model. The model suggests it is optimal to overstate quality when (i) customers rely relatively less on advertising to form quality expectations, and (ii) customers’ intrinsic satisfaction with a product is high. These results are consistent with deceptive advertising cases at the FTC, which showed more deception for unknown firms and for firms whose customers were more satisfied. They are also consistent with the decisions made by future managers (MBAs), except that the respondents would advertise higher (versus lower) quality when advertising was effective.
Are National Guidelines for Total Hip Replacement in the UK Reflected in Practice?
Authors: Abraham A , Hajipour L , Innes AR , Phillips H , McCaskie AW 
Published: March 2006

INTRODUCTION A cross-sectional study was performed to compare the practice of total hip replacement (THR) in the UK against national guidelines. MATERIALS AND METHODS A postal questionnaire was sent to all fellows of the British Orthopaedic Association. RESULTS Of the 1587 questionnaires sent out, 966 (60.9%) were returned. Of these, 706 (73.1%) were available for data collection and analysis. CONCLUSIONS Consensus was observed in several areas including the use of pre-admission clinics and modern cementing techniques. Facilities deemed necessary for THR surgery such as HDU/ITU back-up, ultra-clean air and dedicated orthopaedic wards are almost universally available. However, a lack of consensus is evident in many areas including the process of obtaining written consent, thrombo-embolic prophylaxis, duration of antibiotic prophylaxis, supervision of trainee surgeons and follow-up arrangements. The proliferation in the range of implants, particularly aimed at ‘younger’ patients, available to surgeons has once again been highlighted.