bluuebunny/crossref_metadata_2025 huggingface dataset:
Hyperforin down-regulates effector function of activated T lymphocytes and shows efficacy against Th1-triggered CNS inflammatory-demyelinating disease
Authors: Cabrelle Anna , Dell’Aica Isabella , Melchiori Luca , Carraro Samuela , Brunetta Enrico , Niero Raffaele , Scquizzato Elisa , D’Intino Giulia , Calzà Laura , Garbisa Spiridione , Agostini Carlo
Published: October 2007

Hyperforin (Hyp) is an active compound contained in the extract of Hypericum perforatum, well known for its antidepressant activity. However, Hyp has been found to possess several other biological properties, including inhibitory effects on tumor invasion, angiogenesis, and inflammation. In this paper, we show that treatment with Hyp inhibited IFN-γ production, with down-regulation of T-box (T-bet; marker of Th1 gene expression) and up-regulation of GATA-3 (marker gene of Th2) on IL-2/PHA-activated T cells. In parallel, we showed a strong down-regulation of the chemokine receptor CXCR3 expression on activated T cells. The latter effect and the down-modulation of matrix metalloproteinase 9 expression may eventually lead to the inhibition of migratory capability and matrix traversal toward the chemoattractant CXCL10 by activated lymphocytes that we observed in vitro. The effect of Hyp was thus evaluated on an animal model of experimental allergic encephalomyelitis (EAE), a classic, Th1-mediated autoimmune disease of the CNS, and we observed that Hyp attenuates the severity of the disease symptoms significantly. Together, these properties qualify Hyp as a putative, therapeutic molecule for the treatment of autoimmune inflammatory disease sustained by Th1 cells, including EAE.
Oxytocin-Induced Activation of Eukaryotic Elongation Factor 2 in Myometrial Cells Is Mediated by Protein Kinase C
Authors: Devost Dominic , Carrier Marie-Eve , Zingg Hans H.
Published: October 2007

The nonapeptide oxytocin (OT) mediates a wide spectrum of biological action, many of them related to reproduction. Recently, we have shown that OT exerts a trophic effect on uterine smooth muscle cells and induces dephosphorylation, and thus activation, of the translation elongation factor eukaryotic elongation factor 2 (eEF2). The present study was designed to elucidate the mechanisms underlying this novel action of OT in the well-characterized human myometrial cell line hTERT-C3. Pathways known to induce eEF2 dephosphorylation are mammalian target of rapamycin (mTOR), and the MAPKs ERK1/2 and p38. Using a panel of chemical inhibitors of specific signaling pathways, we determined that none of these pathways played a role in OT-mediated eEF2 dephosphorylation. Because the OT receptor is a G protein-coupled receptor linked to Gαq, we tested the possibility that this OT action was mediated via protein kinase C (PKC). PKC activity was blocked by application of the general PKC chemical inhibitor Go6983 or by incubation with the cell-permeable PKC inhibitor peptide myr-psi PKC. With either approach, the effect of OT on eEF2 dephosphorylation was suppressed, indicating that the PKC pathway is essential for this OT action. Consistent with this idea, we also found that direct stimulation of PKC with the phorbol ester phorbol 12-myristate 13-acetate induced eEF2 dephosphorylation. Moreover, we observed that the stimulatory effect of OT on [35S]methionine incorporation into nascent proteins was blocked by PKC inhibition. Overall, these results define a novel hormonal signaling pathway that leads to eEF2 dephosphorylation and activation of protein synthesis.
Sex Differences in Serotonergic But Not γ-Aminobutyric Acidergic (GABA) Projections to the Rat Ventromedial Nucleus of the Hypothalamus
Authors: Patisaul Heather B. , Fortino Anne E. , Polston Eva K.
Published: October 2007

Hormonal conditions that elicit lordosis in female rats are ineffective in males, suggesting that this behavior is actively suppressed in males. Previous studies theorize that serotonergic and γ-aminobutyric acidergic (GABA) inputs to the ventrolateral division of the ventromedial nucleus of the hypothalamus (VMNvl) may contribute to lordosis inhibition in males. Using triple-label immunofluorescent techniques, the present studies explored potential sex differences in the density of these projections within three hypothalamic sites: the VMNvl, the arcuate nucleus (ARC), and the dorsomedial nucleus of the hypothalamus. Antibodies directed against HuC/D, estrogen receptor (ER)-α and either serotonin (5-HT) or the γ-aminobutyric acid synthetic enzyme glutamic acid decarboxylase-65 were used to compare the densities of glutamic acid decarboxylase (GAD)-65- and 5-HT-containing fibers in each brain area, the percentage of VMNvl HuC/D immunoreactive (ir) neurons that contained ERα, and the percentage of HuC/D and ERα double-labeled cells receiving apparent contacts from 5-HT fibers between adult, gonadectomized male and female rats. The densities of VMNvl and ARC 5-HT immunolabeled fibers were significantly higher in the males, and the percentage of VMNvl HuC/D-ir neurons containing ERα was significantly higher in the females. The percentage of HuC/D-ir cells contacted by 5-HT fibers was significantly higher in the males, compared with the females, but there was no sex difference in the proportion of those cells receiving contacts that were ERα-ir. Neonatal administration of estradiol but not genistein masculinized 5-HT content in the adult female VMNvl, but the percentage of HuC/D-ir cells colabeled with ERα was not significantly affected by treatment. A similar, but not statistically significant, pattern was observed in the ARC. These findings suggest that the development of serotonergic inputs to the male VMNvl is orchestrated by neonatal estradiol exposure. The hormone-dependent organization of these 5-HT projection patterns may be an important developmental mechanism accounting for sex-specific behaviors in adulthood.
Stress-Induced Intracellular Trafficking of Corticotropin-Releasing Factor Receptors in Rat Locus Coeruleus Neurons
Authors: Reyes Beverly A. S. , Valentino Rita J. , Van Bockstaele Elisabeth J.
Published: October 2007

Corticotropin-releasing factor (CRF) activates locus coeruleus (LC)-norepinephrine neurons during stress. Previous stress or CRF administration attenuates the magnitude of this response by decreasing postsynaptic sensitivity to CRF. Here we describe the fate of CRF receptors (CRFr) in LC neurons after stress. Rats were exposed to swim stress or handling and perfused 1 or 24 h later. Sections through the LC were processed for immunogold-silver labeling of CRFr. CRFr in LC dendrites was present on the plasma membrane and within the cytoplasm. In control rats, the ratio of cytoplasmic to total dendritic labeling was 0.55 ± 0.01. Swim stress increased this ratio to 0.77 ± 0.01 and 0.80 ± 0.02 at 1 and 24 h after stress, respectively. Internalized CRFr was associated with different organelles at different times after stress. At 1 h after stress, CRFr was often associated with early endosomes in dendrites and perikarya. By 24 h, more CRFr was associated with multivesicular bodies, suggesting that some of the internalized receptor is targeted for degradation. In perikarya, more internalized CRFr was associated with Golgi apparatus 24 vs. 1 h after stress. This is suggestive of changes in CRFr synthesis. Alternatively, this may indicate communication between multivesicular bodies and Golgi apparatus in the process of recycling. Administration of the selective CRF1 antagonist, antalarmin, before swim stress attenuated CRFr internalization. The present demonstration of stress-induced internalization of CRFr in LC neurons provides evidence that CRF is released in the LC during swim stress to activate this system and initiate cellular trafficking of the receptor that determines subsequent sensitivity of LC neurons to CRF.
Dexamethasone Sensitizes the Neonatal Intestine to Fructose Induction of Intestinal Fructose Transporter (Slc2A5) Function
Authors: Douard Veronique , Cui Xue-Lin , Soteropoulos Patricia , Ferraris Ronaldo P.
Published: October 2007

The recent dramatic increase in fructose consumption is tightly correlated with an equally dramatic surge in the incidence of type 2 diabetes and obesity in children, but little is known about dietary fructose metabolism and absorption in neonates. The expression of the rat intestinal fructose transporter GLUT5 [Slc2A5, a member of the glucose transporter family (GLUT)] can be specifically induced by its substrate fructose, but only after weaning begins at 14 d of age. In suckling rats younger than 14 d old, dietary fructose cannot enhance GLUT5 expression. The aim of this study was to identify the mechanisms allowing fructose to stimulate GLUT5 during weaning. After intestines were perfused with fructose or glucose (control), using microarray hybridization we showed that of 5K genes analyzed in 10-d-old pups, only 13 were fructose responsive. Previous work found approximately 50 fructose-responsive genes in 20-d-old pups. To identify fructose-responsive genes whose expression also changed with age, intestines of 10- and 20-d-old littermate pups perfused with fructose were compared by microarray. Intestines of 10- and 20-d-old pups perfused with glucose were used to segregate age- but not fructose-responsive genes. About 28 genes were up- and 22 down-regulated in 20- relative to 10-d-old pups, under conditions of fructose perfusion, and many were found, by cluster analysis, to be regulated by corticosterone. When dexamethasone was injected into suckling pups before fructose perfusion, the expression of GLUT5 but not that of the sodium glucose cotransporter (SGLT) 1 and of GLUT2, as well as the uptake of fructose but not of glucose increased dramatically. Thus, dexamethasone, which allows dietary fructose to precociously stimulate intestinal fructose absorption, can mimic the effect of age and modify developmental timing mechanisms regulating GLUT5.
Pituitary Gonadotroph Estrogen Receptor-α Is Necessary for Fertility in Females
Authors: Gieske Mary C. , Kim Hyun Joon , Legan Sandra J. , Koo Yongbum , Krust Andree , Chambon Pierre , Ko CheMyong
Published: October 2007

Estrogens play a central role in regulating female reproduction throughout the reproductive axis, and the pituitary is one of the major targets of estrogen action. We hypothesized that estrogen receptor α (ERα) mediates estrogen action in the pituitary gonadotroph. To test this hypothesis, we generated a mouse line with a selective ERα deletion in the gonadotropin α-subunit (αGSU)-expressing pituitary cells (pituitary-specific ERα knockout; ERαflox/flox αGSUcre). Although the ERαflox/flox αGSUcre female mice maintain a basal level of serum LH and FSH and their ovulatory capacity is comparable to that in controls, they do not display regular estrous cycles and are infertile, indicating a potential disorder in regulating LH and/or FSH secretion. The ERαflox/flox αGSUcre female mice express equivalent levels of LHβ and αGSU mRNA compared with wild-type mice as determined by microarray analysis. Taken together, these findings indicate that pituitary gonadotroph ERα carries out the effects of estrogens with regard to estrous cyclicity and ultimately fertility.
Functional Development of the Ovarian Noradrenergic Innervation
Authors: Ricu Manuel , Paredes Alfonso , Greiner Monika , Ojeda Sergio R. , Lara Hernan E.
Published: October 2007

A substantial fraction of the noradrenergic innervation targeting the mammalian ovary is provided by neurons of the celiac ganglion. Although studies in the rat have shown that noradrenergic nerves reach the ovary near the time of birth, it is unknown how the functional capacity of this innervation unfolds during postnatal ovarian development. To address this issue, we assessed the ability of the developing ovary to incorporate and release 3H-norepinephrine. Incorporation of 3H-norepinephrine was low during the first 3 wk of postnatal life, but pharmacological inhibition of norepinephrine (NE) neuronal uptake with cocaine showed that an intact transport mechanism for NE into nerve terminals is already in place by the first week after birth. Consistent with this functional assessment, the mRNA encoding the NE transporter was also expressed in the celiac ganglion at this time. During neonatal-infantile development [postnatal (PN) d 5–20], the spontaneous, vesicle-independent outflow of recently taken up NE was high, but the NE output in response to K+-induced depolarization was low. After PN d 20, spontaneous outflow decreased and the response to K+ increased markedly, reaching maximal values by the time of puberty. Tyramine-mediated displacement of NE stored in vesicles, which displace vesicular NE, showed that vesicle-dependent NE storage becomes functional by PN d 12 and that vesicular release increases during the juvenile-peripubertal phases of sexual development. These results indicate that vesicular release of NE from ovarian noradrenergic nerves begins to operate by the third week of postnatal life, becoming fully functional near the time of puberty.
Increased P2X7 Receptor Expression and Function in Thyroid Papillary Cancer: A New Potential Marker of the Disease?
Authors: Solini Anna , Cuccato Sabina , Ferrari Davide , Santini Eleonora , Gulinelli Sara , Callegari Maria Giulia , Dardano Angela , Faviana Pinuccia , Madec Stephanie , Di Virgilio Francesco , Monzani Fabio
Published: October 2007

Nucleotides are increasingly recognized as nonredundant extracellular signals for chemotaxis, cell growth, and cytokine release. Effects of extracellular nucleotides are mediated by P2 receptors, among which the P2X7 subtype is attracting increasing attention for its involvement in apoptosis, cell growth, and cytokine release. Recent studies showed that P2X7 is overexpressed in chronic lymphocytic leukemia and breast and prostate cancer. The aim of the present study was to better understand the clinical significance of P2X7 receptor expression in normal and cancer human thyroid tissues. P2X7 receptor message and protein expression and functional activity were tested in two cell lines (FB1 and FB2) established from either anaplastic or papillary primary thyroid cancer and in several histological samples of human papillary cancer. We show here that human thyroid papillary carcinoma, whether of the classical or follicular variant, expresses the P2X7 receptor (P2X7R) to a much higher level than normal thyroid tissue. The P2X7R was similarly up-regulated in FB1 and FB2 cell lines. In contrast to normal thyroid cells, both cell lines responded to extracellular nucleotide stimulation with a large increase in intracellular Ca2+ and secretion of IL-6. Ca2+ increase was attenuated and release of IL-6 was fully blocked by P2X7R inhibitors. Finally, the thyroid carcinoma cell lines had at least a 3-fold higher intracellular ATP concentration and maintained at least a 3-fold higher extracellular ATP level, compared with control cells. These data suggest that an enhanced P2X7R function might be a feature of human thyroid cancer.
Magnetic maps in animals: nature's GPS
Authors: Lohmann Kenneth J. , Lohmann Catherine M. F. , Putman Nathan F.
Published: October 2007

Diverse animals detect the Earth's magnetic field and use it as a cue in orientation and navigation. Most research on magnetoreception has focused on the directional or `compass' information that can be extracted from the Earth's field. Because the field varies predictably across the surface of the globe, however, it also provides a potential source of positional or `map'information, which some animals use to steer themselves along migratory pathways or to navigate toward specific target areas. The use of magnetic positional information has been demonstrated in several diverse animals including sea turtles, spiny lobsters, newts and birds, suggesting that such systems are phylogenetically widespread and can function over a wide range of spatial scales. These `magnetic maps' have not yet been fully characterized. They may be organized in several fundamentally different ways, some of which bear little resemblance to human maps, and they may also be used in conjunction with unconventional navigational strategies.
Light scattering by selected zooplankton from the Gulf of Aqaba
Authors: Gagnon Y. L. , Shashar N. , Warrant E. J. , Johnsen S. J.
Published: October 2007

Light scattering by zooplankton was investigated as a major factor undermining transparency camouflage in these pelagic animals. Zooplankton of differing transparencies – including the hyperiid amphipod Anchylomera blossevillei, an unknown gammarid amphipod species, the brine shrimp Artemia salina, the euphausiid shrimp Euphausia diomedeae, the isopod Gnathia sp., the copepods Pontella karachiensis, Rhincalanus sp. and Sapphirina sp., the chaetognath Sagitta elegans and an enteropneust tornaria larva– were illuminated dorsally with white light (400–700 nm). Spectral measurements of direct transmittance as well as relative scattered radiances at angles of 30°, 90°, 150° and 180° from the light source were taken. The animals sampled had transparencies between 1.5% and 75%. For all species, the highest recorded relative scattered radiance was at 30°, with radiances reaching 38% of the incident radiance for the amphipod A. blossevillei. Scattering patterns were also found to be species-specific for most animals. Relative scattered radiances were used to estimate sighting distances at different depths. These calculations predict that all of the examined zooplankton are brighter than the background radiance when viewed horizontally, or from diagonally above or below at shallow depths. Thus, in contrast to greater depths, the best strategy for detecting transparent zooplankton in the epipelagic environment may be to search for them from above while looking diagonally downwards, looking horizontally or looking from below diagonally upwards. Looking directly upwards proved to be more beneficial than the other viewing angles only when the viewed animal was at depths greater than 40 m.
Assessment of sperm chemokinesis with exposure to jelly coats of sea urchin eggs and resact: a microfluidic experiment and numerical study
Authors: Inamdar Munish V. , Kim Taeyong , Chung Yao-Kuang , Was Alex M. , Xiang Xinran , Wang Chia-Wei , Takayama Shuichi , Lastoskie Christian M. , Thomas Florence I. M. , Sastry Ann Marie
Published: October 2007

Specific peptides contained within the extracellular layer, or jelly coat,of a sea urchin egg have been hypothesized to play an important role in fertilization, though separate accounting of the effects of chemoattraction,chemokinesis, sperm agglomeration and the other possible roles of the jelly coat have not been reported. In the present study, we used a microfluidic device that allowed determination of the differences in the diffusion coefficients of sperm of the purple sea urchin Arbacia punctulatasubjected to two chemoattractants, namely the jelly coat and resact. Our objectives were twofold: (1) to experimentally determine and compare the diffusion coefficients of Arbacia punctulata spermatozoa in seawater,jelly coat solution and resact solution; and (2) to determine the effect of sea urchin sperm diffusion coefficient and egg size on the sperm–egg collision frequency using stochastic simulations. Numerical values of the diffusion coefficients obtained by diffusing the spermatozoa in seawater,resact solution and jelly coat solution were used to quantify the chemotactic effect. This allowed direct incorporation of known enlargements of the egg,and altered sperm diffusion coefficients in the presence of chemoattractant,in the stochastic simulations. Simulation results showed that increase in diffusion coefficient values and egg diameter values increased the collision frequency. From the simulation results, we concluded that type of sperm, egg diameter and diffusion coefficient are significant factors in egg fertilization. Increasing the motility of sperm appears to be the prominent role of the jelly coat.
Modulation of flight muscle power output in budgerigarsMelopsittacus undulatusand zebra finchesTaeniopygia guttata:in vitromuscle performance
Authors: Ellerby David J. , Askew Graham N.
Published: October 2007

The pectoralis muscles are the main source of mechanical power for avian flight. The power output of these muscles must be modulated to meet the changing power requirements of flight across a range of speeds. This can be achieved at the muscle level by manipulation of strain trajectory and recruitment patterns, and/or by intermittent flight strategies. We have measured the in vitro power outputs of pectoralis muscle fascicles from budgerigars Melopsittacus undulatus and zebra finches Taeniopygia guttata under conditions replicating those previously measured in vivo during flight. This has allowed us to quantify the extent to which different power modulation mechanisms control flight muscle power output. Intermittent flight behaviour is a more important determinant of flight power in zebra finches than budgerigars. This behaviour accounts for 25–62% of power modulation relative to the maximum available mechanical power output in zebra finch, compared to 0–38% in budgerigars. Muscle level changes in fascicle strain trajectory and motor unit recruitment, rather than intermittent flight behaviours, are the main determinants of pectoralis muscle power output in budgerigars at all speeds, and in zebra finch at speeds below 14 m s–1.
Modulation of pectoralis muscle function in budgerigarsMelopsitaccus undulatusand zebra finchesTaeniopygia guttatain response to changing flight speed
Authors: Ellerby David J. , Askew Graham N.
Published: October 2007

Flight power varies in a U-shaped relationship with flight speed, requiring the modulation of flight muscle power in order to meet these changing power demands. The power output of the pectoralis muscle can potentially be modulated by changing strain trajectory and the relative timing and intensity of muscle activity. Pectoralis muscle length change and activity patterns were recorded in budgerigars Melopsitaccus undulatus and zebra finches Taeniopygia guttata at a range of flight speeds using sonomicrometry and electromyography (EMG). The pectoralis muscles in these species contain a single muscle fibre type. Therefore, the power output is entirely determined by muscle activity and strain trajectory, rather than recruitment of motor units with different contractile properties as in many other vertebrate muscle systems. Relative EMG intensity, wingbeat frequency and muscle strain varied in an approximately U-shaped relationship with flight speed. The shape of the length trajectory varied with flight speed in budgerigars, with the proportion of the cycle spent shortening being lowest at intermediate flight speeds. In zebra finch pectoralis muscle the shape of the length trajectory did not vary significantly with flight speed. In both species the observed changes in muscle recruitment and length trajectory are consistent with meeting flight power requirements that vary in a U-shaped pattern with speed. Both species utilised intermittent flight, tending to spend relatively less time flapping at intermediate flight speeds. This supports the idea that intermittent flight is used as a simple power modulation strategy. However, the idea that intermittent flight serves to maintain a `fixed gear' is over-simplistic and fails to recognise the plasticity in performance at the level of the muscle. Intermittent flight is only one component of a complex power modulation strategy.
Immunohistochemical characterization of a parapinopsin-containing photoreceptor cell involved in the ultraviolet/green discrimination in the pineal organ of the river lamprey Lethenteron japonicum
Authors: Kawano-Yamashita Emi , Terakita Akihisa , Koyanagi Mitsumasa , Shichida Yoshinori , Oishi Tadashi , Tamotsu Satoshi
Published: October 2007

In the pineal organ, two types of ganglion cell exhibit antagonistic chromatic responses to UV and green light, and achromatic responses to visible light. In this study, we histologically characterized UV-sensitive photoreceptor cells that contain a unique non-visual UV pigment, lamprey parapinopsin, in order to elucidate the neural network that is associated with antagonistic chromatic responses. These characteristics were compared with those of lamprey rhodopsin-containing cells, most of which are involved in achromatic responses. RT-PCR analysis revealed that lamprey parapinopsin was expressed in the pineal organ but not in the retina, unlike lamprey rhodopsin,which was expressed in both. Lamprey parapinopsin and lamprey rhodopsin were immunohistochemically localized in the dorsal and ventral regions of the pineal organ, respectively. The two pigments were localized in distinct photoreceptor cells throughout the pineal organ, namely the dorsal and ventral regions as well as the peripheral region, which corresponds to the dorso-ventral border region. The ratio of the number of lamprey parapinopsin-containing cells to lamprey rhodopsin-containing cells around the peripheral region was higher than in the central region. Electron-microscopic analysis revealed that lamprey parapinopsin-containing dorsal cells have outer segments and synaptic ribbons similar to those of ventral photoreceptor cells. However, unlike lamprey rhodopsin-containing cells, lamprey parapinopsin-containing cells connected with each other in a wide area of dorsal and peripheral portions and made direct contact with ganglion cells,mainly in the peripheral portion. These results suggest that UV light information captured by lamprey parapinopsin-containing photoreceptor cells is converged and directly transmitted to chromatic-type ganglion cells in the peripheral region to generate antagonistic chromatic responses.
Diurnal and nocturnal prey luring of a colorful predator
Authors: Chuang Chih-Yen , Yang En-Cheng , Tso I-Min
Published: October 2007

While animal color signaling has been studied for decades, we have little knowledge of the role conspicuous body coloration plays in the nocturnal context. In this study we explored animal color signaling in both diurnal and nocturnal contexts to arrive at a more comprehensive understanding of its function. We quantified how the brightly colored giant wood spiders Nephila pilipes are viewed by nocturnal insects, and performed field manipulations to assess the function of a spider's coloration in both diurnal and nocturnal conditions. Seen through the eyes of moths, the conspicuous body parts of spiders are quite distinctive from the vegetation background. The presence of N. pilipes significantly increased the diurnal as well as the nocturnal prey interception rates of their webs, but these rates were significantly reduced when the conspicuous color signals of N. pilipes were altered by black paint. A comparison of the diurnal and nocturnal hunting performances of spiders showed that their conspicuous coloration had a higher luring effect under dim light conditions. These results demonstrate that the conspicuous body coloration of N. pilipes functions as a visual lure to attract both diurnal and nocturnal prey. It seems that nocturnal insects are the major target of this colorful sit-and-wait predator. We suggest that the selection pressure to effectively exploit the color vision of nocturnal prey could be one of the major forces driving the evolution of spider coloration.
The use of distal rhynchokinesis by birds feeding in water
Authors: Estrella Sora M. , Masero José A.
Published: October 2007

The use of distal rhynchokinesis, which consists of the movement of the distal part of the upper jaw with respect to the cranium, is well documented in long-billed shorebirds (Scolopacidae), commonly being associated with the deep probing feeding method. However, the functional and evolutionary significance of distal rhynchokinesis and other cranial kinesis is unclear. We report for the first time the use and occurrence of distal rhynchokinesis in wild long-billed shorebirds feeding on small prey items suspended in water. We tested whether prey size in captive dunlins Calidris alpinainfluences the occurrence of distal rhynchokinesis during feeding and also whether its use affects foraging efficiency. We found that wild dunlin, curlew sandpiper Calidris ferruginea, sanderling Calidris alba and little stint Calidris minuta commonly use distal rhynchokinesis to strike, capture and transport small prey items. Prey size influenced the occurrence of distal rhynchokinesis during the transport phase, with this type of cranial kinesis being more frequently used with larger prey. The rhynchokinesis protraction angle (a measure of bill tip elevation) during prey strike and transport was affected by prey size, and bill gape was modulated through the use of distal rhynchokinesis in relation to prey size. Finally,the use of distal rhynchokinesis throughout intra-oral prey transport was related to shorter transport times, which improved foraging efficiency. We conclude that distal rhynchokinesis is a mechanism that could contribute to the flexible feeding behaviour of long-distance migratory shorebirds,enhancing small prey profitability and so improving foraging efficiency, and may have played a role in the evolutionary radiation of Scolopacidae(Charadrii).
Molecular cloning, phylogeny and localization of AgNHA1: the first Na+/H+ antiporter (NHA) from a metazoan,Anopheles gambiae
Authors: Rheault Mark R. , Okech Bernard A. , Keen Stephen B. W. , Miller Melissa M. , Meleshkevitch Ella A. , Linser Paul J. , Boudko Dmitri Y. , Harvey William R.
Published: October 2007

We have cloned a cDNA encoding a new ion transporter from the alimentary canal of larval African malaria mosquito, Anopheles gambiae Giles sensu stricto. Phylogenetic analysis revealed that the corresponding gene is in a group that has been designated NHA, and which includes(Na+ or K+)/H+ antiporters; so the novel transporter is called AgNHA1. The annotation of current insect genomes shows that both AgNHA1 and a close relative, AgNHA2, belong to the cation proton antiporter 2 (CPA2) subfamily and cluster in an exclusive clade of genes with high identity from Aedes aegypti, Drosophila melanogaster, D. pseudoobscura, Apis mellifera and Tribolium castaneum. Although NHA genes have been identified in all phyla for which genomes are available, no NHA other than AgNHA1 has previously been cloned,nor have the encoded proteins been localized or characterized.

The AgNHA1 transcript was localized in An. gambiae larvae by quantitative real-time PCR (qPCR) and in situ hybridization. AgNHA1 message was detected in gastric caeca and rectum, with much weaker transcription in other parts of the alimentary canal. Immunolabeling of whole mounts and longitudinal sections of isolated alimentary canal showed that AgNHA1 is expressed in the cardia, gastric caeca, anterior midgut, posterior midgut, proximal Malpighian tubules and rectum, as well as in the subesophageal and abdominal ganglia.

A phylogenetic analysis of NHAs and KHAs indicates that they are ubiquitous. A comparative molecular analysis of these antiporters suggests that they catalyze electrophoretic alkali metal ion/hydrogen ion exchanges that are driven by the voltage from electrogenic H+ V-ATPases. The tissue localization of AgNHA1 suggests that it plays a key role in maintaining the characteristic longitudinal pH gradient in the lumen of the alimentary canal of An. gambiae larvae.
G protein activation by uncaging of GTP-γ-S in the leech giant glial cell
Authors: Hirth Ingo C. , Britz Frank C. , Deitmer Joachim W.
Published: October 2007

Glial cells can be activated by neurotransmitters viametabotropic, G protein-coupled receptors. We have studied the effects of`global' G protein activation by GTP-γ-S on the membrane potential,membrane conductance, intracellular Ca2+ and Na+ of the giant glial cell in isolated ganglia of the leech Hirudo medicinalis. Uncaging GTP-γ-S (injected into a giant glial cell as caged compound) by moderate UV illumination hyperpolarized the membrane due to an increase in K+ conductance. Uncaging GTP-γ-S also evoked rises in cytosolic Ca2+ and Na+, both of which were suppressed after depleting the intracellular Ca2+ stores with cyclopiazonic acid (20 μmol l–1). Uncaging inositol-trisphosphate evoked a transient rise in cytosolic Ca2+ and Na+ but no change in membrane potential. Injection of the fast Ca2+ chelator BAPTA or depletion of intracellular Ca2+ stores did not suppress the membrane hyperpolarization induced by uncaging GTP-γ-S. Our results suggest that global activation of G proteins in the leech giant glial cell results in a rise of Ca2+-independent membrane K+conductance, a rise of cytosolic Ca2+, due to release from intracellular stores, and a rise of cytosolic Na+, presumably due to increased Na+/Ca2+ exchange.
Effects of perch diameter and incline on the kinematics, performance and modes of arboreal locomotion of corn snakes (Elaphe guttata)
Authors: Astley Henry C. , Jayne Bruce C.
Published: October 2007

Animals moving through arboreal habitats face several functional challenges, including fitting onto and moving on cylindrical branches with variable diameters and inclines. In contrast to lizards and primates, the arboreal locomotion of snakes is poorly understood, despite numerous snake species being arboreal. We quantified the kinematics and performance of corn snakes (Elaphe guttata) moving on seven cylinders (diameters 1.6–21 cm) with five inclines (horizontal, ±45° and±90°) and through horizontal tunnels of corresponding widths. When perches were inclined at either 45° or 90°, snakes were unable to move uphill or downhill on the larger diameters. None of the locomotion on perches conformed to any previously described mode of limbless locomotion. On horizontal and uphill perches snakes performed a variant of concertina locomotion with periodic stopping and gripping. When moving downhill, snakes often slid continuously while grasping the perch to reduce their speed. Mean forward velocity decreased both with increased incline and with increased perch diameter, contrary to the beneficial effect of increased diameter on the speeds of lizards. Both tunnel width and perch diameter had widespread and similar effects on kinematics. When perches and tunnels were narrower, the snakes had more lateral bends at shallower angles. The numerous effects of perch diameter on kinematics and the similarity to tunnel concertina locomotion emphasize the importance of fit as a limitation in arboreal locomotion of snakes. However, the slower speeds on horizontal perches compared to tunnels also suggest that balance and grip may further limit locomotor performance.
Honeybees perform optimal scale-free searching flights when attempting to locate a food source
Authors: Reynolds Andrew M. , Smith Alan D. , Reynolds Don R. , Carreck Norman L. , Osborne Juliet L.
Published: October 2007

The foraging strategies used by animals are key to their success in spatially and temporally heterogeneous environments. We hypothesise that when a food source at a known location ceases to be available, flying insects will exhibit search patterns that optimise the rediscovery of such resources. In order to study these searching patterns, foraging honeybees were trained to an artificial feeder that was then removed, and the subsequent flight patterns of the bees were recorded using harmonic radar. We show that the flight patterns have a scale-free (Lévy-flight) characteristic that constitutes an optimal searching strategy for the location of the feeder. It is shown that this searching strategy would remain optimal even if the implementation of the Lévy-flights was imprecise due, for example, to errors in the bees'path integration system or difficulties in responding to variable wind conditions. The implications of these findings for animal foraging in general are discussed.
Effects of photoperiod history on body mass and energy metabolism in Brandt's voles (Lasiopodomys brandtii)
Authors: Lu Qin , Zhong Wen-Qin , Wang De-Hua
Published: October 2007

Many small mammals respond to seasonal changes in photoperiod via alterations in morphology, physiology and behaviour. In the present study, we tested the hypothesis that the preweaning (from embryo to weaning) photoperiod experience can affect subsequent development in terms of body mass and thermogenesis. Brandt's voles (Lasiopodomys brandtii) were gestated and reared to weaning under either a short (SD, 8 h:16 h L:D) or a long photoperiod (LD, 16 h:8 h L:D) at a constant ambient temperature (23°C). At weaning, male juveniles were either maintained in their initial photoperiod or transferred to the alternative photoperiod for 8 weeks. Postweaning SD voles had a lower body mass but higher thermogenic capacity compared with LD voles. At the same time, preweaning photoperiod conditions had long-lasting effects on thermogenic capacity later in life. Serum leptin concentration was positively correlated with body mass and body fat mass, whereas it was negatively correlated with energy intake and uncoupling protein 1 content in brown adipose tissue. Our results suggest that postweaning development in terms of body mass and thermogenesis is predominantly influenced by the postweaning photoperiod, while the preweaning photoperiod experience could chronically modify thermogenesis but not body mass. Furthermore, serum leptin,acting as a potential adipostatic signal, may be involved in the regulation of both energy intake and energy expenditure.
Displacement potential solution of a deep stiffened cantilever beam of orthotropic composite material
Authors: Deb Nath S. K , Afsar A M , Reaz Ahmed S
Published: October 2007

An analytical solution of the elastic field of a deep stiffened cantilever beam of orthotropic composite material is presented in the paper. The cantilever beam is subjected to a parabolic shear loading at its free lateral end and the two opposing longitudinal edges are stiffened. Unidirectional fibre-reinforced composite is considered for the present analysis where the fibres are assumed to be directed along the beam length. Following a new development, the present mixed-boundary-value elastic problem is formulated in terms of a single potential function defined in terms of the associated displacement components. This formulation reduces the problem to the solution of a single fourth-order partial differential equation of equilibrium and is capable of dealing with mixed modes of boundary conditions appropriately. The solution is obtained in the form of an infinite series. Results of different stress and displacement components at different sections of the composite beam are presented numerically in the form of graphs. Finally, in an attempt to check the reliability as well as the accuracy of the present solution, the problem is solved by using two standard numerical methods of solution. A comparison of the results shows that the analytical and numerical solutions of the present problem are in good agreement and thus establishes the soundness as well as the reliability of the present displacement potential approach to solution of the elastic field of orthotropic composite structures.
Validation and application of a screw method for strain measurement in bulk metal forming
Authors: Yuan S J , Zhang J , He Z. B
Published: October 2007

A new method for measurement of plastic strain inside a deforming body is advanced and validated through a simple cylinder upsetting experiment. It is also applied to a ring for demonstrating this method in a ring compression test. The experimental results and numerical simulation show good agreement. In contrast with other physical modelling methods, this method utilizes the real metal for a sensor and workpiece, rather than using substitute materials, and can observe and measure material flow and plastic strain inside the specimen without splitting it before deformation. It can be used to study material flow and to predict strain distribution in general bulk metal-forming processes such as upsetting, extrusion, and die forging. It is also useful for verification of the numerical simulation methods when the material model and the processing parameters were uncertain and/or not easily verified.
Multi-scan laser forming: Synchrotron strain scanning and microstructure evolution
Authors: Topić M N , McGrath P , Vorster W. J J , Zhang S Y , Bucher R , Venter A , Korsunsky A. M
Published: October 2007

Residual elastic strain and microstructural transformations resulting from high thermal gradients introduced by industrial-strength laser forming of mild steel are reported in this article. An 8 mm thick steel plate was bent to a total bending angle of 1.2° by running a laser three successive times across the length of the plate. Thin through-thickness slices of the plate were prepared for synchrotron energy-dispersive X-ray diffraction experiments from which lattice strains were calculated by measuring peak shifts in the diffraction patterns. The diffraction patterns were analysed by means of Rietveld refinement using the general structure analysis system allowing the spatially resolved mapping of relevant strain components needed for full-field eigenstrain determination in the plate. Comparison of the measured residual elastic strain fields and metallographic analyses of the steel plate suggests that a correlation exists between the residual elastic strains and metallurgical processes. The present study serves the purpose of developing a better understanding of the laser forming process and its implications on structural integrity and in-service reliability of components. It also provides a foundation for further in-depth studies into the interaction between lasers and structural materials
Orthotropy and geometry effects on stress concentration factors for short rectangular plates with a centred circular opening
Authors: Bakhshandeh K , Rajabi I
Published: October 2007

In this study, the effects of orthotropy ratio and plate length on the stress concentration factor for orthotropic plates with a centred circular opening under the action of uniaxial tension loads are investigated by use of the finite element method. This work demonstrates that the stress concentration factor depends on the length of the member in addition to other established geometric parameters. The value of the transition length between long and short plates is computed and reported as well. This study has shown that Tan's equation for a finite width orthotropic plate is accurate for a ratio of the opening radius to plate semiwidth of less than 0.35 for orthotropy ratios less than 50. A new concept is introduced, namely the transition ratio.
Measurement of semi-volatiles in used natural gas engine oil using thermogravimetric analysis
Authors: Mullins G , Truhan J
Published: October 2007

Semi-volatile in internal combustion engine lubricating oil may be responsible for limiting service life and can lead to in-cylinder deposit formation. In order to measure semivolatile content, a new thermogravimetric analysis (TGA) procedure has been adapted from existing soot procedures to determine the levels of semi-volatile compounds in progressively aged lubricating oil samples from a natural gas engine dynamometer test cell run. The per cent weight remaining at 550 °C, while heated at a constant rate in an inert atmosphere, varied linearly with running time, viscosity, and oxidation and nitration. The method yielded reproducible run-to-run results and showed good agreement between helium and argon atmospheres. Mass spectroscopy data confirmed increased levels of high molecular weight species during engine operation. This method may be applicable to diesel engine oil samples.
Emissions suppression mechanism of premixed diesel combustion with variable valve timing
Authors: Murata Y , Kusaka J , Odaka M , Daisho Y , Kawano D , Suzuki H , Ishii H , Goto Y
Published: October 2007

A variable valve timing (VVT) mechanism is applied to achieve premixed diesel combustion at higher load for low emissions and high thermal efficiency in a light-duty diesel engine. By means of late intake valve closing (LIVC), compressed gas temperatures near the top dead centre are lowered, thereby preventing too early ignition and increasing ignition delay to enhance fuel-air mixing. The variability of an effective compression ratio has significant potential for ignition timing control of conventional diesel fuel mixtures. At the same time, the expansion ratio is kept constant to ensure thermal efficiency. Combining the control of LIVC, exhaust gas recirculation (EGR), supercharging systems, and high-pressure fuel injection equipment can simultaneously reduce NO x and smoke. The NO x and smoke suppression mechanism in the premixed diesel combustion is analysed using a three-dimensional computational fluid dynamics (3D-CFD) code combined with detailed chemistry. LIVC can achieve a significant NO x and smoke reduction due to lowering combustion temperatures and avoiding local overrich regions in the mixtures respectively.
The Effects of Three Levels of Contextual Interference on Performance Outcomes and Movement Patterns in Golf Skills
Authors: Porter Jared M. , Landin Dennis , Hebert Edward P. , Baum Brian
Published: October 2007

The motor learning literature is replete with studies investigating the contextual interference (CI) effect. However, CI research has focused on performance outcome measures, largely ignoring the influence varying levels of CI may have on performance production measures, particularly with tasks involving inter-limb coordination. It was the purpose of this study to explore the effects of three levels of CI on both categories of performance measures in adults who were naïve to a sport skill Participants were taught the basic movement pattern of two golf strokes the putt and pitch. Following an instructional period, subsequent practice involved 160 trials performed under low, moderate, or high CI. No significant group differences emerged from practice data. Analysis of post-test data indicated that the high CI group was generally superior on both production measures. These results add to a limited body of research that suggests CI can benefit the development of coordinated movements.
Time Management and the Full-Time Sportsperson: Increasing Individual Perceptions of Time Control
Authors: Forsyth Darryl K. , Catley Bevan
Published: October 2007

For the full-time athlete, effective time management can contribute to sporting success as well as helping them to avoid harmful effects to their psychological well-being. One important source of tension and potential stress lies in the difficulty sportspeople and their families have in recognising and establishing the boundaries between work time and ‘non-work’ time Utilising a process model of time management, this paper maintains that the goal of any time management initiative should be to enhance the individual's perception of time control. Building on this insight and drawing on applied research in the fields of psychology and organisation studies, strategies for effective time management are discussed. However, in contrast to many ‘self-help’ books in this area, this paper does not simply advocate one ‘correct’ way to manage time but contends that any potential strategy should be used in conjunction with the individual's preference for organisation