bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variation in morphology and performance of predator-sensing system in wild cricket populations
Authors: Dangles Olivier , Magal Christelle , Pierre Dominique , Olivier Aurélie , Casas Jérôme 
Published: January 2005

SUMMARY
Even though variation in morphology is known to translate into variation in performance, studies looking at structural variability of a sensor to predict its consequences on the performance of animals are exceedingly rare. We investigated the morphological variability of air-flow-sensing receptors in wild populations of wood crickets (Nemobius sylvestris) sampled in a wide variety of habitats differing in latitude, litter structure, vegetation and predator communities. These hair receptors act as predator sensors. The observed levels of hair morphological variation were then incorporated into a biomechanical model of the hair canopy response to air flow to predict their influence on cricket predator perception. Cricket populations differ from each other, often strongly so, in the total number of hairs and in the number of hairs longer than 1 mm, which are the hairs most sensitive for the perception of approaching predators. The hair canopy response, the output of the biomechanical model, sums up over the entire canopy the angles of deflection at which a neurophysiological response is triggered and represents the sensitivity of the cercal system. It is 35% higher in the most sensitive population, compared with the least sensitive population. These large differences in perception sensitivity for a given predator signal translate into larger distances at which predators could be perceived. Thus, differences in morphology at the sensor level seem to be translated both at the perception level and subsequently at the performance level of crickets.
Optimal swim speeds for traversing velocity barriers: an analysis of volitional high-speed swimming behavior of migratory fishes
Authors: Castro-Santos Theodore 
Published: January 2005

SUMMARYMigrating fish traversing velocity barriers are often forced to swim at speeds greater than their maximum sustained speed (Ums). Failure to select an appropriate swim speed under these conditions can prevent fish from successfully negotiating otherwise passable barriers. I propose a new model of a distance-maximizing strategy for fishes traversing velocity barriers, derived from the relationships between swim speed and fatigue time in both prolonged and sprint modes. The model predicts that fish will maximize traversed distance by swimming at a constant groundspeed against a range of flow velocities, and this groundspeed is equal to the negative inverse of the slope of the swim speed–fatigue time relationship for each mode. At a predictable flow velocity, they should switch from the optimal groundspeed for prolonged mode to that for sprint mode. Data from six migratory fish species(anadromous clupeids: American shad Alosa sapidissima, alewife A. pseudoharengus and blueback herring A. aestivalis; amphidromous:striped bass Morone saxatilis; and potomodromous species: walleye(previously known as Stizostedion vitrium) and white sucker Catostomus commersonii) were used to explore the ability of fish to approximate the predicted distance-maximizing behaviors, as well as the consequences of deviating from the optima. Fish volitionally sprinted up an open-channel flume against fixed flow velocities of 1.5–4.5 m s-1, providing data on swim speeds and fatigue times, as well as their groundspeeds. Only anadromous clupeids selected the appropriate distance-maximizing groundspeed at both prolonged and sprint modes. The other three species maintained groundspeeds appropriate to the prolonged mode, even when they should have switched to the sprint optima. Because of this, these species failed to maximize distance of ascent. The observed behavioral variability has important implications both for distributional limits and fishway design.
Factors reducing the expected deflection in initial orientation in clock-shifted homing pigeons
Authors: Gagliardo Anna , Odetti Francesca , Ioalè Paolo 
Published: January 2005

SUMMARYTo orient from familiar sites, homing pigeons can rely on both an olfactory map and visual familiar landmarks. The latter can in principle be used in two different ways: either within a topographical map exploited for piloting or in a so-called mosaic map associated with a compass bearing. One way to investigate the matter is to put the compass and the topographical information in conflict by releasing clock-shifted pigeons from familiar locations. Although the compass orientation is in general dominant over a piloting strategy, a stronger or weaker tendency to correct towards the home direction by clock-shifted pigeons released from very familiar sites has often been observed. To investigate which factors are involved in the reduction of the deviation due to clock-shift, we performed a series of releases with intact and anosmic pigeons from familiar sites in unshifted and clock-shifted conditions and a series of releases from the same sites with naive clock-shifted birds. Our data suggest that the following factors have a role in reducing deviation due to the clock-shift: familiarity with the release site, the lack of olfactory information and some unknown site-dependent features.
Mechanics and energetics of swinging the human leg
Authors: Doke Jiro , Donelan J. Maxwell , Kuo Arthur D. 
Published: January 2005

SUMMARYWe measured how much metabolic energy is expended to swing a human leg. A previous dynamical model of walking predicted that increasing metabolic costs for walking with step length and step frequency trade-off against each other to determine the optimum step combination at a given speed. Simple pendulum dynamics indicate that the cost of walking at high step frequencies could be associated with driving the legs back and forth relative to the body, at a rate increasing approximately with the fourth power of frequency, possibly due to the low economy of producing muscle force for short durations. A similar cost would be expected for isolated swinging of a leg at faster than its natural frequency. We constructed an apparatus to measure work performed on the leg, and measured metabolic cost as human subjects (N=12) swung one leg at frequencies 0.5-1.1 Hz and fixed amplitude. Rate of mechanical work ranged from 0.02-0.27 W kg-1 over these frequencies. Net metabolic rate for leg swinging (subtracting that for quiet standing) increased from 0.41-2.10 W kg-1, approximately with the fourth power of frequency(R2=0.92) and in proportion to a hypothesized cost of force production for short durations. The costs of producing force and work could account for the increase. In a crude comparison, moving the legs back and forth at a typical stride frequency of 0.9 Hz, might consume about one-third of the net energy (2.8±0.8 W kg-1) needed for walking at 1.3 m s-1.
Sodium and anion transport across the avian uterine (shell gland)epithelium
Authors: Vetter Alisen E. , O'Grady Scott M. 
Published: January 2005

SUMMARY
The uterine (shell gland) epithelium from the domestic chicken was mounted in Ussing chambers, bathed in symmetric avian saline solution on both apical and basolateral aspects and voltage clamped at 0 mV. The epithelium exhibited a basal short circuit current (Isc) that was partially inhibited by the epithelial Na+ channel (ENaC) blockers, amiloride and benzamil (IC50 values of 0.8 and 0.12 μmol l-1,respectively). Inhibition of basal Na+ absorption by 10 μmol l-1 amiloride was confirmed by measurements of transepithelial Na+ and Cl- fluxes, where inhibition of the apical-to-basolateral and net Na+ flux occurred, but no significant effects on Cl- fluxes were detected. The amiloride-insensitive portion of the basal Isc was both Cl- and HCO3- dependent and was inhibited by the Cl-channel blocker, diphenyl-2-carboxylate (DPC; 100 μmol l-1). Stimulation with 8-(4-chlorophenylthio)-cyclic 3′-5′, adenosine monophosphate (8-cpt cAMP) produced a sustained increase in Isc that was dependent on both Cl- and HCO3-. The magnitude of the amiloride-sensitive Isc was approximately twofold greater in birds where shell formation was complete, but oviposition had not yet occurred. In addition, the amiloride-sensitive Isc was greater in hens over the age of 55 weeks and in molting birds. The anion-dependent component of the basal Isc was reduced in older birds, and electrogenic HCO3- transport was nearly absent in molting birds. These results demonstrated that electrogenic Na+ transport in avian shell gland was similar to the mammalian uterine epithelium and increased with age and during molting. Electrogenic Cl- and HCO3- transport were coupled under basal and cAMP stimulated conditions and basal anion transport decreased with age and during molting.
Behavioural response to the bioavailability of inorganic mercury in the hydrothermal musselBathymodiolus azoricus
Authors: Kádár Enikõ , Costa Valentina , Santos Ricardo S. , Lopes Humberto 
Published: January 2005

SUMMARYThe hydrothermal vent bivalve Bathymodiolus azoricus is naturally exposed to putatively elevated levels of mercury (Hg), exposure that dates back to the geological occurrence of vent ecosystems, and thus may have evolved evolutionary detoxification mechanisms. Therefore, it was used as a model organism in the present investigation to study the Hg–animal interaction. Mussels were exposed to inorganic Hg by daily administration of 20 μg l-1 Hg for 21 days (cumulative added concentration was 420μg l-1, i.e. ∼2 mmol l-1) under controlled laboratory conditions, and consequent bioaccumulation and detoxification patterns were investigated, while shell gaping behaviour indicative of filtering activity was monitored.As a result of Hg exposure, significant increase in duration, as well as decline in frequency of shell gaping occurred, which did not recover to pre-exposure levels following 21 days of Hg-free treatment. An increase in the duration of open-shelled status may indicate the absence of an avoidance reaction in the vent mussel coming in contact with Hg, unlike other bivalves that normally close their shells in response to stress compounds. Alternatively, it may suggest that Hg had an inhibitory effect on the adductor muscle function that is responsible for closing the shells. As a result,elevated Hg levels were measured in the soft tissues (270±71 μg g-1 in gills, 245±52 μg g-1 in digestive glands, 93±25 μg g-1 in the mantle and 46±9 μg g-1 in the foot), in byssus threads (peak levels of 442±89μg g-1) and in pseudofaeces (reaching levels as high as 1000μg g-1). Overall, gills contributed 75% to the total Hg body burden followed by mantle (13%), digestive gland (7%), byssus (3%) and foot(2%). Tissue Hg levels remained elevated in mussels transferred to Hg-free seawater even after 21 days, despite the high concentrations persistently eliminated with pseudofaeces both, during and after, exposure.This potential for bioaccumulation of inorganic Hg (concentration factors reached the order of magnitude of 104) by the vent mussel, which does not seem to prevent uptake by shell closure, suggests that the main Hg-handling strategy is elimination via mucus.
Foraging in a complex naturalistic environment: capacity of spatial working memory in flower bats
Authors: Winter York , Stich Kai Petra 
Published: January 2005

SUMMARY
Memory systems have evolved under selection pressures, such as the need to remember the locations of resources or past events within spatiotemporally dynamic natural environments. The full repertoire of complex behaviours exhibited by animals in dynamic surroundings are, however, difficult to elicit within simply structured laboratory environments. We have developed a computer-controlled naturalistic environment with 64 feeders for simulating dynamic patterns of water or food resource availability (depletion and replenishment) within the laboratory. The combination of feeder and cage remote control permits the automated transfer of animals between cage and test arena and, therefore, high experimental throughput and minimal disturbance to the animals (bats and mice). In the present study, we investigated spatial working memory in nectar-feeding bats (Glossophaga soricina,Phyllostomidae) collecting food from a 64-feeder array. Feeders gave only single rewards within trials so that efficient foraging required bats to avoid depleted locations. Initially, bats tended to revisit feeders (win-stay), but within three trials changed towards a win-shift strategy. The significant avoidance of revisits could not be explained by algorithmic search guiding movement through the array nor by scent cues left by the bats themselves and,thus, the data suggest that bats remembered spatial locations depleted of food. An examination of the recency effect on spatial working memory after bats shifted to a win-shift strategy indicated that bats held more than 40 behaviour actions (feeder visits) in working memory without indication of decay. This result surpasses previous findings for other taxa.
Muscle remodeling in relation to blood supply: implications for seasonal changes in mitochondrial enzymes
Authors: McClelland G. B. , Dalziel A. C. , Fragoso N. M. , Moyes C. D. 
Published: January 2005

SUMMARYWe investigated if seasonal changes in rainbow trout muscle energetics arise in response to seasonal changes in erythrocyte properties. We assessed if skeletal muscle mitochondrial enzymes changed (1) acutely in response to changes in erythrocyte abundance, or (2) seasonally when we altered the age profile of erythrocytes. Rainbow trout were treated with pheynylhydrazine,causing a 75% reduction in hematocrit within 4 days. After erythropoiesis had returned hematocrit to normal, treated and control fish were subjected to a seasonal cold acclimation regime to assess the impact of erythrocyte age on skeletal muscle remodeling. Anemia (i.e. phenylhydrazine treatment) did not alter the specific activities (U g-1 tissue) of mitochondrial enzymes in white or red muscle. Anemic pretreatment did not alter the normal pattern of cold-induced mitochondrial proliferation in skeletal muscle,suggesting erythrocyte age was not an important influence on seasonal remodeling of muscle. Anemia and cold acclimation both induced a 25–30%increase in relative ventricular mass. The increase in relative ventricular mass with phenylhydrazine treatment was accompanied by a 35% increase in DNA content (mg DNA per ventricle), suggesting an increase in number of cells. In contrast, the increase in ventricular mass with cold temperature acclimation occurred without a change in DNA content (mg DNA per ventricle), suggesting an increase in cell size. Despite the major increases in relative ventricular mass, neither anemia nor seasonal acclimation had a major influence on the specific activities of a suite of mitochondrial enzymes in heart. Collectively, these studies argue against a role for erythrocyte dynamics in seasonal adaptive remodeling of skeletal muscle energetics.
Flight muscle properties and aerodynamic performance ofDrosophilaexpressing aflightintransgene
Authors: Barton Byron , Ayer Gretchen , Heymann Nicole , Maughan David W. , Lehmann Fritz-Olaf , Vigoreaux Jim O. 
Published: January 2005

SUMMARYFlightin is a multiply phosphorylated, myosin-binding protein found specifically in indirect flight muscles (IFM) of Drosophila. A null mutation in the flightin gene (fln0) compromises thick filament assembly and muscle integrity resulting in muscle degeneration and lost of flight ability. Using P-element-mediated transformation with the full-length flightin gene driven by the Actin88F promoter,we have achieved rescue of all fln0-related ultrastructural and functional defects of the IFM. Transgenic P{fln+}fln0 `rescued' flies have fewer thick filaments per myofbril than wild-type flies (782±13 vs945±9) but have otherwise normal IFM. Transgenic P{fln+}fln+ `tetraploid' flies have a normal number of thick filaments. The flightin protein levels in both transgenic strains are similar to wild type. By contrast, flightin levels are reduced in a myosin heavy chain tetraploid strain that produces excess myosin and excess thick filaments. These results suggest that regulation of flightin protein level is independent of gene copy number and that the number of thick filaments assembled per myofibril is influenced independently by myosin and flightin expression. We measured mechanical properties of IFM skinned fibers by sinusoidal analysis and found no significant differences in active viscoelastic properties of flightin-rescued and tetraploid transgenic flies vs wild type. The ability of the fln+transgene to overcome deficits in dynamic stiffness and power output in fln0 suggest that the flightin protein contributes directly to fiber stiffness and stretch activation. However, flight parameters at maximum locomotor capacity, measured in a virtual reality flight simulator,are slightly compromised for both transgenic strains. P{fln+}fln0 and P{fln+}fln+ flies generated enough flight force to sustain hovering flight but showed reduced capability to produce forces in excess of hovering flight force. Both strains showed reductions in stroke frequency but only P{fln+}fln+ showed reductions in stroke amplitude. Muscle and aerodynamic efficiency are similar among the two transgenic strains and wild type. These results illustrate the importance of flightin in flight muscle development and function.
Effect of photoperiod on body mass, food intake and body composition in the field vole,Microtus agrestis
Authors: Król E. , Redman P. , Thomson P. J. , Williams R. , Mayer C. , Mercer J. G. , Speakman J. R. 
Published: January 2005

SUMMARYMany small mammals respond to seasonal changes in photoperiod by altering body mass and adiposity. These animals may provide valuable models for understanding the regulation of energy balance. Here, we present data on the field vole (Microtus agrestis) – a previously uncharacterised example of photoperiod-induced changes in body mass. We examined the effect of increased day length on body mass, food intake, apparent digestive efficiency,body composition, de novo lipogenesis and fatty acid composition of adipose tissue in cold-acclimated (8°C) male field voles by transferring them from a short (SD, 8 h:16 h L:D) to long day photoperiod (LD, 16 h:8 h L:D). During the first 4 weeks of exposure to LD, voles underwent a substantial increase in body mass, after which the average difference between body masses of LD and SD voles stabilized at 7.5 g. This 24.8% increase in body mass reflected significant increases in absolute amounts of all body components, including dry fat mass, dry lean mass and body water mass. After correcting body composition and organ morphology data for the differences in body mass, only gonads (testes and seminal vesicles) were enlarged due to photoperiod treatment. To meet energetic demands of deposition and maintenance of extra tissue, voles adjusted their food intake to an increasing body mass and improved their apparent digestive efficiency. Consequently, although mass-corrected food intake did not differ between the photoperiod groups, the LD voles undergoing body mass increase assimilated on average 8.4 kJ day-1 more than animals maintained in SD. The majority(73–77%) of the fat accumulated as adipose tissue had dietary origin. The rate of de novo lipogenesis and fatty acid composition of adipose tissue were not affected by photoperiod. The most important characteristics of the photoperiodic regulation of energy balance in the field vole are the clear delineation between phases where animals regulate body mass at two different levels and the rate at which animals are able to switch between different levels of energy homeostasis. Our data indicate that the field vole may provide an attractive novel animal model for investigation of the regulation of body mass and energy homeostasis at both organism and molecular levels.
Human Umbilical Cord Perivascular (HUCPV) Cells: A Source of Mesenchymal Progenitors
Authors: Sarugaser Rahul , Lickorish David , Baksh Dolores , Hosseini M. Morris , Davies John E. 
Published: January 2005

Abstract
We describe the isolation of a nonhematopoietic (CD45−, CD34−, SH2+, SH3+, Thy-1+, CD44+) human umbilical cord perivascular (HUCPV) cell population. Each HUCPV cell harvest (2–5 × 106, depending on the length of cord available) gave rise to a morphologically homogeneous fibroblastic cell population, which expressed α-actin, desmin, vimentin, and 3G5 (a pericyte marker) in culture. We determined the colony-forming unit-fibro-blast (CFU-F) frequency of primary HUCPV cells to be 1:333 and the doubling time, which was 60 hours at passage 0 (P0), decreased to 20 hours at P2. This resulted in a significant cell expansion, producing over 1010 HUCPV cells within 30 days of culture. Furthermore, HUCPV cells cultured in nonosteogenic conditions contained a subpopulation that exhibited a functional osteogenic phenotype and elaborated bone nodules. The frequency of this CFU-osteogenic subpopulation at P1 was 2.6/105 CFU-F, which increased to 7.5/105 CFU-F at P2. Addition of osteogenic supplements to the culture medium resulted in these frequencies increasing to 1.2/104 and 1.3/104 CFU-F, respectively, for P1 and P2. CFU-O were not seen at P0 in either osteogenic or non-osteogenic culture conditions, but P0 HUCPV cells did contain a 20% subpopulation that presented neither class I nor class II cell-surface major histocompatibility complexes (MHC−/−). This population increased to 95% following passage and cryopreservation (P5). We conclude that, due to their rapid doubling time, high frequencies of CFU-F and CFU-O, and high MHC−/− phenotype, HUCPV cells represent a significant source of cells for allogeneic mesenchymal cell-based therapies.
Health Expenditures for Privately Insured Adults Enrolled in Managed Care Gatekeeping vs Indemnity Plans
Authors: Pati Susmita , Shea Steven , Rabinowitz Daniel , Carrasquillo Olveen 
Published: January 2005

Objectives. We assessed the ability of managed care gatekeeping strategies (i.e., requiring a designated primary care provider to authorize referrals) to control health care costs in the mid-1990s. Methods. We analyzed expenditure data from 8195 privately insured adults sampled in the nationally representative 1996 Medical Expenditure Panel Survey. Managed care gatekeeping plan enrollees included those in health maintenance organizations and other plans requiring a primary care gatekeeper. All others were considered indemnity plan enrollees. Results. In 1996, total per capita annual health expenditures for adult gatekeeping enrollees were about $50 less than those of indemnity enrollees, primarily owing to lower out-of-pocket expenditures. After multivariate adjustment, mean per capita expenditures were approximately 6% lower for gatekeeping enrollees than for indemnity enrollees. Conclusions. In the private sector, gatekeeping strategies resulted in modest cost savings over indemnity plans.
Comparative Geographic Concentrations of 4 Sexually Transmitted Infections
Authors: Kerani Roxanne P. , Handcock Mark S. , Handsfield H. Hunter , Holmes King K. 
Published: January 2005

Objectives. We measured and compared the concentration of primary and secondary syphilis, gonorrhea, chlamydial infection, and genital herpes in a large county with urban, suburban, and rural settings. Methods. We geocoded sexually transmitted infections reported to King County, Washington health department in 2000–2001 to census tract of residence. We used a model-based approach to measure concentration with Lorenz curves and Gini coefficients. Results. Syphilis exhibited the highest level of concentration (estimated Gini coefficient = 0.68, 95% confidence interval [CI] = 0.64, 0.78), followed by gonorrhea (estimated Gini coefficient=0.57; 95% CI=0.54, 0.60), chlamydial infection (estimated Gini coefficient = 0.45; 95% CI = 0.40, 0.43), and herpes (estimated Gini coefficient=0.26; 95% CI=0.22, 0.29). Conclusions. Geographically targeted interventions may be most appropriate for syphilis and gonorrhea. For less-concentrated infections, control strategies must reach a wider portion of the population.