bluuebunny/crossref_metadata_2025_split huggingface dataset:
In-line motion causes high thrust and efficiency in flapping foils that use power downstroke
Authors: Licht S. C. , Wibawa M. S. , Hover F. S. , Triantafyllou M. S. 
Published: December 2009

SUMMARYWe show experimentally that flapping foil kinematics consisting of a power downstroke and a feathering upstroke together with a properly timed in-line motion, similar to those employed in forelimb propulsion of sea turtles, can produce high thrust and be hydrodynamically as efficient as symmetrically flapping foils. The crucial parameter for such asymmetrically flapping foils is a properly sized and timed in-line motion, whose effect is quantified by a new parameter, the advance angle, defined as the angle of the foil trajectory with respect to the horizontal, evaluated at the middle of the power downstroke. We show, in particular, that optimal efficiency in high aspect ratio rigid foils, accompanied by significant thrust production, is obtained for Strouhal numbers in the range 0.2–0.6 for Reynolds number equal to 13,000, and for values of the advance angle around 0.55π (100 deg.). The optimized kinematics consist of the foil moving back axially during the downstroke, in the direction of the oncoming flow, and rotating with a large pitch angle. This causes the force vector to rotate and become nearly parallel to the steady flow, thus providing a large thrust and a smaller transverse force. During the upstroke, the foil is feathering while it moves axially forward, i.e. away from the vorticity shed during the power stroke; as a result, the transverse force remains relatively small and no large drag force is produced. Observations from turtles confirm qualitatively the findings from the foil experiments.
Heart rate as a predictor of energy expenditure in undisturbed fasting and incubating penguins
Authors: Groscolas R. , Viera V. , Guerin N. , Handrich Y. , Côté S. D. 
Published: December 2009

SUMMARYHeart rate (fH) measurement offers the possibility to monitor energy expenditure (EE) in wild animals if the EE/fH relationship for the species, physiological stages and activities of interest is known. This relationship has been extensively studied using oxygen consumption rate () measurement in captive, repeatedly handled king penguins (Aptenodytes patagonicus). Unfortunately, the potential effects of stress on the observed relationships resulting from handling and confinement were not considered. This study is the first involving undisturbed animals, and determines the EE/fH relationship in naturally fasting and freely incubating or captivity-acclimatized male and female king penguins. EE determination was based on (1) the measurement of body mass loss during periods of phase II fasting, and (2) the calculation of its energy equivalent from changes in body composition, i.e. 23.9 kJ g–1. fH levels in freely incubating and captivity-acclimatized birds were found to be 50–70% lower than those previously reported for resting king penguins during measurements. Significant EE/fH relationships were found in freely incubating and captive males and females (R2=0.59 to 0.84), with no difference observed between genders. The best overall relationship was obtained by including fasting duration (t, days) in the model: EE=818+43.7×fH+36.3t–1.4t×fH (R2=0.91). This equation yielded EE estimates approximately 26% higher than the previously reported ‘best’ predictive equation in king penguins, and even more so when fH was low. This result suggests that stress induces a disproportionate increase of fHvs O2 consumption, and that the use of EE/fH relationships obtained in stressed birds could lead to underestimated EE values.
The distinction between retractor and protractor muscles of the freshwater snail's male organ has no physiological basis
Authors: de Boer P. A. C. M. , Jansen R. F. , ter Maat A. , van Straalen N. M. , Koene J. M. 
Published: December 2009

SUMMARYMany animals are equipped with organs that can be everted, a notable example being male copulatory organs. The ability to protrude or evert an organ generally requires protractor and retractor muscles. Male copulatory behaviour of the pond snail Lymnaea stagnalis (L.) involves eversion (protraction) and retraction of the relatively large penis-carrying organ. For this preputium, protractor and retractor muscle bands have been defined, which implies eversion and retraction through the activity of these muscle bands. However, no physiological data are available that confirm that the terms protractor and retractor are appropriate. To test whether eversion and retraction are possible without protractor and/or retractor muscle bands, lesion experiments were performed. The results show that with either one or several muscle bands lesioned, snails were still capable of everting their preputium and using it for copulation. However, the majority of animals that had six or more muscle bands lesioned were unable to retract its preputium. Hence, retractor muscle bands serve their designated function whereas protractor muscle bands do not. We therefore suggest that a different terminology is used in which all muscle bands are retractors and, based on their location, are either called distal or proximal retractors. The findings furthermore indicate that the preputium muscle bands are normally contracted, possibly in a catch state, retaining the organ inside without high-energy expenditure.
Molt cycle regulation of protein synthesis in skeletal muscle of the blackback land crab, Gecarcinus lateralis, and the differential expression of a myostatin-like factor during atrophy induced by molting or unweighting
Authors: Covi J. A. , Bader B. D. , Chang E. S. , Mykles D. L. 
Published: December 2009

SUMMARY
In decapod crustaceans, claw muscle undergoes atrophy in response to elevated ecdysteroids while thoracic muscle undergoes atrophy in response to unweighting. The signaling pathways that regulate muscle atrophy in crustaceans are largely unknown. Myostatin is a negative regulator of muscle growth in mammals, and a myostatin-like cDNA is preferentially expressed in muscle of the land crab, Gecarcinus lateralis (Gl-Mstn). Contrary to prediction, levels of Gl-Mstn mRNA decreased dramatically in both the claw closer and weighted thoracic muscles when molting was induced by either eyestalk ablation (ESA) or multiple limb autotomy (MLA). However, the effect of molt induction was greater in the claw muscle. By late premolt, Gl-Mstn mRNA in the claw muscle decreased 81% and 94% in ESA and MLA animals, respectively, and was negatively correlated with ecdysteroids. Gl-Mstn mRNA in thoracic muscle decreased 68% and 82% in ESA and MLA animals, respectively, but was only weakly correlated with ecdysteroid. Claw and thoracic muscles also differed to varying extents in the expression of ecdysteroid receptor (Gl-EcR and Gl-RXR), elongation factor-2 (Gl-EF-2), and calpain T (Gl-CalpT) in response to molt induction, but levels of the four transcripts were not correlated with ecdysteroid. The downregulation of Gl-Mstn expression in premolt claw muscle coincided with 11- and 13-fold increases in protein synthesis in the myofibrillar and soluble protein fractions, respectively. Furthermore, the rate of the increase in the synthesis of soluble proteins was greater than that of myofibrillar proteins during early premolt (1.4:1, soluble:myofibrillar), but the two were equivalent during late premolt. By contrast, Gl-Mstn mRNA increased 3-fold and Gl-CalpT mRNA decreased 40% in unweighted thoracic muscle; there was little or no effect on Gl-EF-2, Gl-EcR, and Gl-RXR mRNA levels. These data indicate that Gl-Mstn expression is negatively regulated by both ecdysteroids and load-bearing contractile activity. The downregulation of Gl-Mstn in claw muscle may induce the elevated protein turnover associated with remodeling of the contractile apparatus during molt-induced atrophy. The upregulation of Gl-Mstn in unweighted thoracic muscle suggests that this factor is also involved in disuse atrophy when hemolymph ecdysteroid levels are low.
Ecophysiological response of Adélie penguins facing an experimental increase in breeding constraints
Authors: Beaulieu M. , Spée M. , Lazin D. , Ropert-Coudert Y. , le Maho Y. , Ancel A. , Raclot T. 
Published: December 2009

SUMMARY
Foraging strategies play a key role in breeding effort. Little is known, however, about their connection with hormonal and nutritional states, especially when breeding constraints vary. Here, we experimentally increased foraging costs and thus breeding constraints by handicapping Adélie penguins (Pygoscelis adeliae) with dummy devices representing 3–4% of the penguins' cross-sectional area. We examined food-related stress (via plasma corticosterone concentration) and nutritional state (via metabolite levels). Concurrently, we investigated the use of ecological niches via the isotopic signature of red blood cells indicating the trophic position (δ15N) and the spatial distribution (δ13C) of penguins. Handicapped birds performed ∼70% longer foraging trips and lost ∼60% more body mass than controls and their partners. However, corticosterone levels and the nutritional state were unchanged. The isotopic signature revealed that males and females differed in their foraging behaviour: upper trophic levels contributed more in the males' diet, who foraged in more pelagic areas. Handicapped and partner birds adopted the same strategy at sea: a shift towards higher δ13C values suggested that they foraged in more coastal areas than controls. This change in foraging decisions may optimize feeding time by decreasing travelling time. This may partly compensate for the presumed lower foraging efficiency of handicapped birds and for the energetic debt of their partners who had to fast ∼70% longer on the nest. We propose that this flexible use of ecological niches may allow birds facing increased breeding constraints to avoid chronic stress and to minimize the impact on their body condition.
Regulation of sarcoendoplasmic reticulum Ca2+-ATPase (SERCA) in turtle muscle and liver during acute exposure to anoxia
Authors: Ramnanan C. J. , McMullen D. C. , Bielecki A. , Storey K. B. 
Published: December 2009

SUMMARY
The freshwater turtle Trachemys scripta elegans naturally tolerates extended periods of anoxia during winter hibernation at the bottom of ice-locked ponds. Survival in this anoxic state is facilitated by a profound depression of metabolic rate. As calcium levels are known to be elevated in anoxic turtles, and ion pumping is an ATP-expensive process, we proposed that activity of the sarcoendoplasmic reticulum Ca2+-ATPase (SERCA) would be reduced in muscle and liver of T. s. elegans during acute (up to 20 h) exposure to anoxia. SERCA activity decreased ∼30% in liver and ∼40% in muscle after 1 h anoxia exposure and was ∼50% lower after 20 h of anoxia exposure in both tissues, even though SERCA protein levels did not change. SERCA kinetic parameters (increased substrate Km values, increased Arrhenius activation energy) were indicative of a less active enzyme form under anoxic conditions. Interestingly, the less active SERCA in anoxic turtles featured greater stability than the enzyme from normoxic animals as determined by both kinetic analysis (effect of low pH and low temperatures on Km MgATP) and conformational resistance to urea denaturation. The quick time course of deactivation and the stable changes in kinetic parameters that resulted suggested that SERCA was regulated by a post-translational mechanism. In vitro experiments indicated that SERCA activity could be blunted by protein phosphorylation and enhanced by dephosphorylation in a tissue-specific manner.
Identification of a calcitonin-like diuretic hormone that functions as an intrinsic modulator of the American lobster,Homarus americanus, cardiac neuromuscular system
Authors: Christie A. E. , Stevens J. S. , Bowers M. R. , Chapline M. C. , Jensen D. A. , Schegg K. M. , Goldwaser J. , Kwiatkowski M. A. , Pleasant T. K. , Shoenfeld L. , Tempest L. K. , Williams C. R. , Wiwatpanit T. , Smith C. M. , Beale K. M. , Towle D. W. , Schooley D. A. , Dickinson P. S. 
Published: December 2009

SUMMARYIn insects, a family of peptides with sequence homology to the vertebrate calcitonins has been implicated in the control of diuresis, a process that includes mixing of the hemolymph. Here, we show that a member of the insect calcitonin-like diuretic hormone (CLDH) family is present in the American lobster, Homarus americanus, serving, at least in part, as a powerful modulator of cardiac output. Specifically, during an ongoing EST project, a transcript encoding a putative H. americanus CLDH precursor was identified; a full-length cDNA was subsequently cloned. In silico analyses of the deduced prepro-hormone predicted the mature structure of the encoded CLDH to be GLDLGLGRGFSGSQAAKHLMGLAAANFAGGPamide (Homam-CLDH), which is identical to a known Tribolium castaneum peptide. RT-PCR tissue profiling suggests that Homam-CLDH is broadly distributed within the lobster nervous system, including the cardiac ganglion (CG), which controls the movement of the neurogenic heart. RT-PCR analysis conducted on pacemaker neuron- and motor neuron-specific cDNAs suggests that the motor neurons are the source of the CLDH message in the CG. Perfusion of Homam-CLDH through the isolated lobster heart produced dose-dependent increases in both contraction frequency and amplitude and a dose-dependent decrease in contraction duration, with threshold concentrations for all parameters in the range 10–11 to 10–10 mol l–1 or less, among the lowest for any peptide on this system. This report is the first documentation of a decapod CLDH, the first demonstration of CLDH bioactivity outside the Insecta, and the first detection of an intrinsic neuropeptide transcript in the crustacean CG.
First evidence of fine colour discrimination ability in ants (Hymenoptera, Formicidae)
Authors: Camlitepe Y. , Aksoy V. 
Published: December 2009

SUMMARY
In the present study, we report the first evidence that ants discriminate and learn perceptually close colour stimuli. Foragers of the ant species Cataglyphis aenescens and Formica cunicularia were trained in a Y-maze choice apparatus to monochromatic light stimuli of a constant intensity associated with a food reward. Two stimuli, with a mean wavelength of 40 nm perceptual distance, were chosen from the UV (340 nm vs 380 nm) and the green (510 nm vs 550 nm) range because these species are UV–green dichromats. Foragers were trained with two conditioning paradigms [absolute conditioning (AC) and differential conditioning (DC)]. In the UV range, C. aenescens foragers failed to discriminate when presented with a small colour difference in both training procedures. Foragers also failed in the green range when trained with AC but showed significant bias towards the rewarded stimulus when trained with DC. Formica cunicularia foragers achieved the task in the UV range when trained with DC only. In the green range, F. cunicularia foragers showed clear preference for the rewarded stimulus in both training conditioning procedures. Foragers never failed in choosing the rewarded stimulus in DC even when the intensity of the rewarded stimulus was reduced by one log unit. This clearly indicates that DC is of paramount importance to discriminate perceptually close colour stimuli.
The effect of boat propeller scarring intensity on genetic variation in a subtropical seagrass species
Authors: Larkin Patrick D. , Heideman Krista L. , Burfeind Dana D. , Stunz Gregory W. 
Published: December 2009

Abstract
We report here the effect of one form of disturbance, boat propeller scarring, on genetic variation in the subtropical seagrass Halodule wrightii. We developed an amplified fragment length polymorphism assay to measure genetic variation in plots representing four levels of scarring intensity: reference (0% scarring), low (1–5%), moderate (5–15%) and severe (>15%). Although we found severely scarred plots to have the lowest, and moderately scarred plots to have the highest, mean genetic diversity estimates (H
e, P), differences among scarring levels were found to be non-significant (α=0.05). Analysis of molecular variance also showed no significant effect of scarring intensity. While propeller scarring can cause significant habitat loss, scarring intensities of up to 20% may not yet have seriously affected those factors (population size, flowering density, recruitment, gene flow) that strongly influence population genetic variation. The relatively recent occurrence of this type of disturbance, however, could mean that any long-term effects have yet to be detected.
Detection and quantitation of Epstein-Barr virus (EBV) DNA in EDTA whole blood samples using automated sample preparation and real time PCR
Authors: Raggam Reinhard B. , Wagner Jasmin , Bozic Michael , Michelin Birgit D.A. , Hammerschmidt Sandra , Homberg Cordula , Kessler Harald H. 
Published: December 2009

Abstract

Background: Detection and quantitation of Epstein-Barr virus (EBV) DNA in EDTA whole blood samples has gained significance in the routine diagnostic laboratory.

Methods: In this study, the analytical and clinical performance of the artus

®
EBV RG PCR kit in conjunction with automated sample preparation on the QIAsymphony
®
SP instrument was evaluated.

Results: When the accuracy of the new test system was tested, all results were found to be within ±0.5 log10 unit of the expected panel results. Determination of linearity showed a quasilinear curve over 4 log units. The lower limit of detection was determined to be 391 EBV DNA copies/mL in EDTA whole blood. The between day imprecision ranged from 18% to 66%, and the within run imprecision ranged from 11% to 50%. When clinical samples were tested and the results compared with those obtained with the routinely used easyMAG™ sample preparation and EBV R-gene™ test system, 60 samples tested positive and 31 samples tested negative by both assays. Nineteen samples were found to be positive using the QIAsymphony
®
sample preparation and artus

®
EBV RG PCR test system only, and no samples tested positive with the routinely used test system only.

Conclusions: The QIAsymphony
®
sample preparation and artus

®
EBV RG PCR test system is suitable for the detection and quantitation of EBV DNA in EDTA whole blood in the routine diagnostic laboratory.
Clin Chem Lab Med 2010;48:413–8.
The Chromatin-Remodeling Protein Osa Interacts With CyclinE in Drosophila Eye Imaginal Discs
Authors: Baig Jawaid , Chanut Francoise , Kornberg Thomas B , Klebes Ansgar 
Published: December 2009

Abstract
Coordinating cell proliferation and differentiation is essential during organogenesis. In Drosophila, the photoreceptor, pigment, and support cells of the eye are specified in an orchestrated wave as the morphogenetic furrow passes across the eye imaginal disc. Cells anterior of the furrow are not yet differentiated and remain mitotically active, while most cells in the furrow arrest at G1 and adopt specific ommatidial fates. We used microarray expression analysis to monitor changes in transcription at the furrow and identified genes whose expression correlates with either proliferation or fate specification. Some of these are members of the Polycomb and Trithorax families that encode epigenetic regulators. Osa is one; it associates with components of the Drosophila SWI/SNF chromatin-remodeling complex. Our studies of this Trithorax factor in eye development implicate Osa as a regulator of the cell cycle: Osa overexpression caused a small-eye phenotype, a reduced number of M- and S-phase cells in eye imaginal discs, and a delay in morphogenetic furrow progression. In addition, we present evidence that Osa interacts genetically and biochemically with CyclinE. Our results suggest a dual mechanism of Osa function in transcriptional regulation and cell cycle control.
Genetic Control of Photoperiod Sensitivity in Maize Revealed by Joint Multiple Population Analysis
Authors: Coles Nathan D , McMullen Michael D , Balint-Kurti Peter J , Pratt Richard C , Holland James B 
Published: December 2009

AbstractVariation in maize for response to photoperiod is related to geographical adaptation in the species. Maize possesses homologs of many genes identified as regulators of flowering time in other species, but their relation to the natural variation for photoperiod response in maize is unknown. Candidate gene sequences were mapped in four populations created by crossing two temperate inbred lines to two photoperiod-sensitive tropical inbreds. Whole-genome scans were conducted by high-density genotyping of the populations, which were phenotyped over 3 years in both short- and long-day environments. Joint multiple population analysis identified genomic regions controlling photoperiod responses in flowering time, plant height, and total leaf number. Four key genome regions controlling photoperiod response across populations were identified, referred to as ZmPR1–4. Functional allelic differences within these regions among phenotypically similar founders suggest distinct evolutionary trajectories for photoperiod adaptation in maize. These regions encompass candidate genes CCA/LHY, CONZ1, CRY2, ELF4, GHD7, VGT1, HY1/SE5, TOC1/PRR7/PPD-1, PIF3, ZCN8, and ZCN19.
A Single Unpaired and Transcriptionally Silenced X Chromosome Locally Precludes Checkpoint Signaling in theCaenorhabditis elegansGerm Line
Authors: Jaramillo-Lambert Aimee , Engebrecht JoAnne 
Published: December 2009

AbstractIn many organisms, female and male meiosis display extensive sexual dimorphism in the temporal meiotic program, the number and location of recombination events, sex chromosome segregation, and checkpoint function. We show here that both meiotic prophase timing and germ-line apoptosis, one output of checkpoint signaling, are dictated by the sex of the germ line (oogenesis vs. spermatogenesis) in Caenorhabditis elegans. During oogenesis in feminized animals (fem-3), a single pair of asynapsed autosomes elicits a checkpoint response, yet an unpaired X chromosome fails to induce checkpoint activation. The single X in males and fem-3 worms is a substrate for the meiotic recombination machinery and repair of the resulting double strand breaks appears to be delayed compared with worms carrying paired X chromosomes. Synaptonemal complex axial HORMA domain proteins, implicated in repair of meiotic double strand breaks (DSBs) and checkpoint function, are assembled and disassembled on the single X similarly to paired chromosomes, but the central region component, SYP-1, is not loaded on the X chromosome in males. In fem-3 worms some X chromosomes achieve nonhomologous self-synapsis; however, germ cells with SYP-1-positive X chromosomes are not preferentially protected from apoptosis. Analyses of chromatin and X-linked gene expression indicate that a single X, unlike asynapsed X chromosomes or autosomes, maintains repressive chromatin marks and remains transcriptionally silenced and suggests that this state locally precludes checkpoint signaling.