bluuebunny/crossref_metadata_2025 huggingface dataset:
α-Glucosidase Inhibitors Reduce Dengue Virus Production by Affecting the Initial Steps of Virion Morphogenesis in the Endoplasmic Reticulum
Authors: Courageot Marie-Pierre , Frenkiel Marie-Pascale , Duarte Dos Santos Claudia , Deubel Vincent , Desprès Philippe
Published: April 2009

We report that endoplasmic reticulum α-glucosidase inhibitors have antiviral effects on dengue (DEN) virus. We found that glucosidase inhibition strongly affects productive folding pathways of the envelope glycoproteins prM (the intracellular glycosylated precursor of M [membrane protein]) and E (envelope protein): the proper folding of prM bearing unprocessed N-linked oligosaccharide is inefficient, and this causes delayed formation of prME heterodimer. The complexes formed between incompletely folded prM and E appear to be unstable, leading to a nonproductive pathway. Inhibition of α-glucosidase-mediated N-linked oligosaccharide trimming may thus prevent the assembly of DEN virus by affecting the early stages of envelope glycoprotein processing.
Identification of a Bovine Coronavirus Packaging Signal
Authors: Cologna Raymond , Hogue Brenda G.
Published: April 2009

A region of the bovine coronavirus (BCV) genome that functions as a packaging signal has been cloned. The 291-nucleotide clone shares 72% homology with the region of mouse hepatitis coronavirus (MHV) gene
1b
that contains the packaging signal. RNA transcripts were packaged into both BCV and MHV virions when the cloned region was appended to a noncoronavirus RNA. This is the first identification of a BCV packaging signal. The data demonstrate that the BCV genome contains a sequence that is conserved at both the sequence and functional levels, thus broadening our insight into coronavirus packaging.
Analysis of HCF, the Cellular Cofactor of VP16, in Herpes Simplex Virus-Infected Cells
Authors: LaBoissière Sylvie , O'Hare Peter
Published: April 2009

Herpes simplex virus (HSV) immediate-early (IE) gene expression is initiated via the recruitment of the structural protein VP16 onto specific sites upstream of each IE gene promoter in a multicomponent complex (TRF.C) that also includes the cellular proteins Oct-1 and HCF. In vitro results have shown that HCF binds directly to VP16 and stabilizes TRF.C. Results from transfection assays have also indicated that HCF is involved in the nuclear import of VP16. However, there have been no reports on the role or the fate of HCF during HSV type 1 (HSV-1) infection. Here we show that the intracellular distribution of HCF is dramatically altered during HSV-1 infection and that the protein interacts with and colocalizes with VP16. Moreover, viral protein synthesis and replication were significantly reduced after infection of a BHK-21-derived temperature-sensitive cell line (
ts
BN67) which contains a mutant HCF unable to associate with VP16 at the nonpermissive temperature. Intracellular distribution of HCF and of newly synthesized VP16 in
ts
BN67-infected cells was similar to that observed in Vero cells, suggesting that late in infection the trafficking of both proteins was not dependent on their association. We constructed a stable cell line (
ts
BN67r) in which the temperature-sensitive phenotype was rescued by using an epitope-tagged wild-type HCF. In HSV-1-infected
ts
BN67r cells at the nonpermissive temperature, direct binding of HCF to VP16 was observed, but virus protein synthesis and replication were not restored to levels observed at the permissive temperature or in wild-type BHK cells. Together these results indicate that the factors involved in compartmentalization of VP16 alter during infection and that late in infection, VP16 and HCF may have additional roles reflected in their colocalization in replication compartments.
Étapes initiales du développement in situ de Claytonia caroliniana var. caroliniana
Authors: Grandtner Miroslav M. , Gervais Camille
Published: April 2009

The early development of Claytonia caroliniana was studied in situ from seeds sown in wirenetting boxes buried in a maple stand near Quebec City. Seed germination begins in late October, more than 4 months after dissemination, reaches a level of about 50% at the end of December, and resumes in springtime. In April–May, one or two secondary roots appear on the most developed seedlings while the single cotyledon (C. caroliniana is a monocotyledonate dicot) shows up above the litter. Concurrently, the corm begins its development at the base of the primary root. A few days later, when the cotyledonary structure disappears, the corm enlarges slightly, new roots begin to form, and an apical bud is activated to initiate the first leaf. The first leaf can reach a length of 4 cm before the winter and will survive under the litter. In April of the following season, 2 years after the beginning of the cycle, the first leaf emerges from the litter, the corm diameter reaching no more than 2–3 mm at this time. The critical stage for the survival of the seedling comes at the beginning of its first summer, as it must produce a corm able to initiate a leaf. This is probably related to the precocity of seed germination. The early phenology of C. caroliniana as a whole resembles that of its adult stages. It differs slightly, however, from the development of C. virginica. Key words: Claytonia caroliniana, seed, germination, seedling, juvenile development.
Relationships of Poaceae, Cyperaceae, and Juncaceae reflected by their fungal parasites
Authors: Savile D. B. O.
Published: April 2009

The rust fungi attacking Poaceae and Cyperaceae suggest that the families may have diverged in about Lower Eocene when the modern grass subfamilies were appearing; however, their smut genera are conspicuously different, suggesting that they were genetically isolated from the start. Both rusts and smuts confirm a close relationship between Cyperaceae and Juncaceae; however, they also indicate that Juncus and Luzula are approximately as modern as Carex. It appears that Juncaceae evolved from lower Cyperaceae through partial reversion to entomophily.
Développement d'axes embryonnaires de pois pourvus ou dépourvus de réserves
Authors: Guerrier G. , Strullu D.G.
Published: April 2009

Growth of axes attached to, or excised from, cotyledons of pea (Pisum sativum) L. cv. Douce Provence) was measured during 6 days of germination or incubation on aseptic agar nutritive medium (mineral nutrients, sucrose). Growth of attached peas starts from the first hour on germination medium, whereas growth of excised axes starts after a lag period of 4 days. During this lag period, carbohydrate and nitrogen metabolism of the axis is dependent on reserve compounds in the cotyledons: on the one hand, the soluble sugar content of the excised axis decreases as a function of incubation time while no dilution due to water uptake occurs, whereas, on the other hand, the high proportion of mineral nitrogen in excised axes contrasts with their high glutamine synthetase and glutamate synthase activities. These observations emphasize the role of utilisation of sugars as respiratory substrate and of polypeptide synthesis involved in the growth process.
Ectomycorrhizal synthesis with Alaskan Alnus tenuifolia
Authors: Brunner I. L. , Brunner F. , Miller Jr. O. K.
Published: April 2009

The ability of Alnus tenuifolia to form ectomycorrhizae with potential ectomycorrhizal fungi was investigated. Alnus tenuifolia seedlings raised in growth pouches were inoculated with Frankia to induce nodulation and then with a putative ectomycorrhizal fungus. The fungi used were collected in nearly pure A. tenuifolia stands in Alaska or were found in Alnus nepalensis stands in Nepal. Five species of putative ectomycorrhizal symbionts of alders were tested. Alpova diplophloeus and Paxillus filamentosus formed both mantle and Hartig net. Cortinarius cf. saturninus developed a mantle but no Hartig net. Hebeloma cf. crustuliniforme and Gyrodon lividus developed neither mantle nor Hartig net. This is the first report of synthesis of P. filamentosus and C. cf. saturninus with Alnus. The ectomycorrhizal status of the genus Gyrodon is discussed, since in vitro synthesis has not yet been demonstrated. Synthesis with A. diplophloeus and H. crustuliniforme did not result in ectomycorrhizal formations with nonnodulated alder seedlings.
Ion behaviour in plant cell walls. III. Measurement of the mean charge separation distance and the linear charge density parameter in delignified Sphagnum russowii cell walls
Authors: Richter Conrad , Dainty Jack
Published: April 2009

According to the Manning condensation theory, the structure of cation-binding uronates in the cell wall can influence ionic behaviour. Assuming the theory is valid, we measured, in cation-binding experiments, the dimensionless linear charge density parameter and the mean charge separation distance in the fully ionized delignified Sphagnum russowii cell wall. Our charge separation estimate, 1.00 ± 0.02 nm, indicates that approximately 1.3 neutral sugars are interpolated between the uronic acids in the polyuronate chains of the cation exchanger. This compares well with chemical data of isolated wall fractions from another Sphagnum species reported by other workers. The charge density parameter estimate, 0.71 ± 0.02, implies that univalent cations never condense, whereas cations with two or more positive charges condense when the degree of ionization of the fixed (wall) charges is high enough. Key words: ion exchange, cell wall, charge density.
Ion behaviour in plant cell walls. IV. Selective cation binding by Sphagnum russowii cell walls
Authors: Richter Conrad , Dainty Jack
Published: April 2009

Selective cation binding by Sphagnum russowii cell walls was investigated using data from bicationic potentiometric titrations of isolated cell walls. Selectivity measurements were interpreted in the context of Manning condensation. In titrations with cations of different valency, selectivity favoured the higher valency cation, as expected in Manning condensation. This selectivity generally increased with bathing pH until the wall-bound polyuronic acids became fully ionized (pH > 5). The selectivity coefficient order at full ionization was Na+–Ca2+ > Na+–La3+ > Ca2+–La3+, as predicted by the weak acid Donnan–Manning (WADM) model. Other phenomena also appear to influence binding selectivity. A small population of isolated binding sites are more effectively neutralized by univalent (or divalent) than divalent (or trivalent) cations. High selectivity for cations of lower valency at low pH also suggests a site isolation effect. In bicationic titrations involving divalent cations only, Sr24+ and Ca2+ were bound by the cell wall with approximately equal effectiveness, as predicted by the WADM model. However, cation or binding site specificities probably account for the favoured binding of Ca2+ over Mg2+ by the cell wall. Key words: ion exchange, cell wall, selectivity.
A morphological study of interspecific hybrids in the genus Lotus (Fabaceae)
Authors: O'Donoughue Louise S. , Raelson J. V. , Grant W. F.
Published: April 2009

A morphological study of hybrids in an interspecific hybridization program involving the nonshattering Lotus species L. conimbricensis and L. ornithopodioides and species belonging to the Lotus corniculatus group, L. alpinus, L. japonicus, and L. burttii, was undertaken. Two hybrids (L. alpinus × L. conimbricensis and L. burttii × L. ornithopodioides) are newly reported. Electrophoretic phenotypes for the enzymes phosphoglucomutase and triose-phosphate isomerase confirmed their hybridity. These hybrids were both highly sterile and might provide a source of indehiscence for L. corniculatus via amphidiploidy. Preliminary shattering evaluations of the hybrids that did set seed indicated increased indehiscence is being attained to a limited extent within the L. corniculatus group.
Endogone pisiformis : croissance, morphologie et conservation des cultures
Authors: Dalpé Yolande
Published: April 2009

The species Endogone pisiformis can now be maintained in pure culture collection in its vegetative form. In vitro, morphological observations of the mycelium revealed the presence of ramified, coenocytic hyphae, which bore both thin- and thick-walled swellings analogous to the vesicles and chlamydospores of vesicular-arbuscular mycorrhizal fungi of the genera Glomus and Sclerocystis. Similar mycelial structures also have been observed, in vivo, on Sphagnum plants along vegetative hyphae still attached to sporocarps. Natural, semisynthetic, and synthetic culture media supported the growth of E. pisiformis for a few successive transfers, but the strains then rapidly lost their vitality. With the addition of thiamine to the culture media, strains completely recovered their vitality. Using thiamine, long-term storage by lyophilisation or under mineral oil is possible. Key words: Endogone pisiformis, fungal morphology, fungal pure culture, thiamine.
Changes in resistance to powdery mildew in a barley composite cross
Authors: Reinhold M. , Bjarko M. E. , Sands D. C. , Bockelman H. E.
Published: April 2009

The response of barley composite cross XLII to selection for resistance to powdery mildew was evaluated. Representative samples from eight cycles of recurrent selection were inoculated with two isolates of Erysiphe graminis f.sp. hordei. Frequencies of resistant plants were determined for each cycle. The resistance in composite cross XLII increased with selection. Increased selection pressure in 1986 resulted in a more rapid increase in resistance than in previous years. Multiple alleles occurring in the Ml-a locus did not seem to have a negative effect on the accumulation of resistance in composite cross XLII. Key words: Hordeum vulgare, barley, Erysiphe graminis f.sp. hordei, powdery mildew, response to selection, recurrent selection.
Ecological Studies of Arctic Cod (Boreogadus saida) in Beaufort Sea Coastal Waters, Alaska
Authors: Craig P. C. , Griffiths W. B. , Haldorson L. , McElderry H.
Published: April 2009

Fish use of Beaufort Sea coastal waters was examined during summer and winter periods 1977–80. Arctic cod (Boreogadus saida) were abundant but their occurrence was highly variable. They accounted for 8–78% of all fish caught in Simpson Lagoon during two summers, and 0.4–100% of catches at various coastal sites in winter. Arctic cod increased in abundance in the lagoon during late summer and some association was noted between their numbers and higher salinities but not temperature or turbidity. Some cod remained in shallow waters in early winter but deeper areas were used through the winter, and the highest catch rate was recorded 175 km offshore. Principal foods of the cod in nearshore waters were mysids (Mysis litoralis, M. relicta), amphipods (Onisimus glacialis), and copepods. The cod caught were generally small (60–170 mm) and young (ages 1–3). Most males matured at ages 2–3 and females at age 3. These size, age, and maturity characteristics indicate a life history strategy (r-selection) unlike that typified by many other arctic fish populations, particularly the freshwater and anadromous species which tend to be slow growing, late maturing and long-lived (K-selection).Key words: Arctic cod, Boreogadus saida; Beaufort Sea, distribution, life history strategy
Growth Patterns in a Newfoundland Atlantic Herring (Clupea harengus harengus) Stock
Authors: Moores J. A. , Winters G. H.
Published: April 2009

Growth patterns in a discrete Atlantic herring (Clupea harengus harengus) stock were examined using back-calculated lengths derived from otolith measurements and empirical data. The influence of abiotic and biotic factors on growth was examined and evaluated for possible density-dependent or density-independent effects. The results give little evidence to support density-dependent herring growth in the 1st year, but suggest density-independent growth regulated by temperature. A growth compensation mechanism appears to occur in subsequent years resulting in a stable maturation pattern within the stock.Key words: herring, growth, density-dependent, density-independent, growth compensation, maturation
Planktivorous Feeding Ecology of Arctic Grayling (Thymallus arcticus)
Authors: Schmidt David , O'Brien W. John
Published: April 2009

A component analysis approach was applied to studies of the zooplankton feeding of Arctic grayling (Thymallus arcticus) of 3–20 cm standard length using all arctic zooplankton species common in the area. Unlike other fish species, larger grayling have greater reactive distance. As expected, the ability of grayling to locate prey was found to increase with size of prey and with light intensity. Grayling vision was found to increase dramatically at light intensities higher than 100 lx. Generally, grayling located and attacked any species within the visual field, locating all by core body size. One exception was the copepod Diaptomus pribilofensis, which was of appropriate size and pigmented a bright red, but was never attacked and eaten by any grayling. The large copepod Heterocope septentrionalis was able to evade grayling feeding attack, but Heterocope evasion was dependent on grayling size and water temperature. Analysis of inter-gill-raker spacing showed that spacing increases linearly with fish length up to 13 cm, at which length no further increase was observed. Such change in inter-gill-raker spacing suggests the feeding niche of grayling may be broader than that of similar sized, temperate centrarchid planktivores.Key words: Arctic grayling, Thymallus arcticus; planktivorous fish, predator–prey interaction, prey evasion, zooplankton
Structure–toxicity Relationship of Tin Compounds on Algae
Authors: Wong P. T. S. , Chau Y. K. , Kramar O. , Bengert G. A.
Published: April 2009

The effects of a number of inorganic and organic tin compounds on pure cultures of green and blue-green algae and natural phytoplankton in lake water were tested. Organic tin compounds were generally more inhibitory to primary production and reproduction of the algae than inorganic tin compounds. The toxicity of organotin compounds varied considerably with the number and nature of the organic groups attached to tin, with trialkyl tin compounds being the most toxic forms. Within a given alkyl tin compound series, the longer the carbon chain, the higher the toxicity. A direct relationship between toxicity and partition coefficients of trialkyl tin compounds was observed. Other tin compounds had no such direct relationship.Key words: algae, tin, toxicity, partition coefficients
Spawning and Feeding Behavior of Captive Pacific Herring, Clupea harengus pallasi
Authors: Stacey N. E. , Hourston A. S.
Published: April 2009

Laboratory observations indicate that spawning of Pacific herring (Clupea harengus pallasi) involves very similar if not identical behavior in males and females, and no identifiable behavioral interactions between the sexes. The presence of a sexual pheromone in herring milt is indicated because spawning behavior is rapidly initiated in ripe (ovulated and spermiated) herring of either sex following exposure either to herring milt or to a filtrate of ripe herring testes. Exposure to herring eggs or to filtrates of hake (Merluccius productus) or Pacific cod (Gadus macrocephalus) testes did not elicit such responses. Four components of spawning behavior induced by herring testis filtrate are identified and described: rising and milling, papilla extension, substrate testing, and substrate spawning. Testis filtrates also elicited rising and milling in spent, developing, and mature (unovulated and unspermiated) fish but rising was not followed by papilla extension, substrate testing, or substrate spawning in fish at these earlier stages of gonadal development. Herring at all stages of maturity also displayed rising and milling in response to an olfactory stimulus (filtrate of crushed euphausiids). This feeding response was weakest in the mature and ripe stages, when fish under natural conditions are reported not to feed, and was strongest in the spent stage, when wild fish resume feeding. In terms of the common components of the response to testis and euphausid filtrates (increased swimming speed, rising, and milling), differential responses to these two stimuli were seen only in ripe fish, suggesting herring at other stages of gonadal development may simply perceive milt as a food stimulus.Key words: Clupea harengus pallasi, spawning behavior, pheromone, feeding
Decreased Seawater Adaptability of Chum Salmon (Oncorhynchus keta) Fry Following Prolonged Rearing in Freshwater
Authors: Iwata Munehico , Hasegawa Sanae , Hirano Tetsuya
Published: April 2009

Chum salmon (Oncorhynchus keta) fry weighing about 1 g maintained plasma Na+ concentrations at 134–140 mmol/L during seaward migration in the Otsuchi River. The plasma Na+ level increased slightly in the estuary, and reached 150–160 mmol/L in the fry caught in the bay. On direct transfer from freshwater to seawater, the plasma Na+ concentrations of the fry weighing 0.4–2.3 g increased markedly after 1 h and reached a maximum after 3–12 h. The fry of < 1.4 g attained sea water-acclimated plasma Na+ level of 156 mmol/L within 24 h after transfer, whereas fry of 1.8–2.3 g failed to adapt to seawater within 24 h. When seawater adaptability of fry of different lots was examined simultaneously in late April, 83–109 d after hatch, the smaller fry adjusted their plasma Na+ levels more easily than the larger fry: the smallest fry attained seawater level after 12 h without showing any peak. Changes in seawater adaptability of the same lots of fry were also followed until 5 mo after hatching, and the osmoregulatory ability of the fry in seawater decreased gradually with an increase in body weight or in the time spent in freshwater.Key words: chum salmon fry, seaward migration, plasma Na+ concentration, seawater adaptability, Oncorhynchus keta
Application of Time–Series Intervention Analysis to Fish Ventilatory Response Data
Authors: Thompson Kenneth W. , Deaton Michael L. , Foutz Robert V. , Cairns Jr. John , Hendricks Albert C.
Published: April 2009

The development of environmental monitors based on ventilation behavior of fishes has produced large masses of data for which no standard analytical procedures exist. This report demonstrates the application of time–series models to this type of data. It also demonstrates the use of intervention analysis to determine the reaction to changes in water quality. Intervention analysis is a powerful statistical tool that allows for great flexibility in the type of response that can be investigated. In this report it is used to determine the ventilatory reaction of the bluegill (Lepomis macrochirus) to sublethal concentrations of zinc sulfate applied in fluctuating intermittent exposures.Key words: intervention analysis, time–series models, Lepomis, ventilatory behavior, biomonitoring
STOCHASTIC MODELS OF THERMODIFFUSION
Authors: CHEVALIER C. , DEBBASCH F. , RIVET J. P.
Published: April 2009

New stochastic models of thermodiffusion are constructed and their hydrodynamical limits are studied through a first-order Chapman–Enskog expansion. These models differ from earlier ones by taking into account all first-order contributions proportional to the temperature gradient and, thus, allow for both positive and negative Soret coefficients, in accordance with observations.
LASER CLADDING OF MAGNESIUM ALLOY AZ91D WITH SILICON CARBIDE
Authors: CAI L. F. , MARK C. K. , ZHOU WEI
Published: April 2009

Mg alloys are ultralight but their structural applications are often limited by their poor wear and corrosion resistance. The research aimed to address the problem by laser-cladding. Cladding with SiC powder onto surface of AZ91D was carried out using Nd :YAG laser. The laser-clad surface was analyzed using the optical microscope, SEM equipped with EDS, and XRD and found to contain SiC and other Si compounds such as Mg 2 Si and Al 3.21 Si 0.47 as well as much refined α- Mg grains and β- Mg 17 Al 12 intermetallics. The laser-clad surface possesses considerably higher hardness but its corrosion resistance is not improved, indicating that the laser-cladding technique can only be adopted for applications in noncorrosive environments where wear is the predominant problem.
BINDING ENERGIES FOR OXYGEN ON TRANSITION METAL SURFACES
Authors: PETROVA N. V. , YAKOVKIN I. N.
Published: April 2009

The binding energies and related energies of associative desorption for oxygen on close-packed ( W (110), Mo (110), and Ru (0001)) and furrowed ( W (112), Mo (112), and [Formula: see text]) surfaces have been calculated by DFT method with generalized gradient approximation for exchange-correlation potential in the revised-Perdew–Burke–Ernzerhof form. The unified approach allows one for a direct comparison of calculated binding energies for different transition metals and different surface geometries, thus revealing the trends that are essential for catalytic properties of surfaces with adsorbed oxygen layers.
OXIDATION RESISTANT (Mo,W)Si2 COATING FOR SiC-COATED CARBON/CARBON COMPOSITES BY IN SITU FORMATION METHOD
Authors: FU QIAN-GANG , LI HE-JUN , LI KE-ZHI , TONG KE , YAO XI-YUAN
Published: April 2009

In order to protect carbon/carbon ( C / C ) composites against oxidation, a ( Mo , W ) Si 2 coating was prepared on the surface of SiC -coated C / C composites by a simple in situ information method using Si , Mo and W as starting materials. The microstructures and oxidation protective ability of the as-received coating were investigated. The results show that the ( Mo , W ) Si 2 outer layer coating containing free Si has a good bonding with SiC inner layer. The as-prepared SiC /( Mo , W ) Si 2 coating can protect C / C composites from oxidation in air at 1773 K for 252 h with a weight gain of 1.56 wt.%. The excellent oxidation resistant property of the double-layer coating is attributed to its dense microstructure and the formation of the stable glassy SiO 2 film on the ( Mo , W ) Si 2 coating surface during its exposure to air at high temperatures.
Expression regulation of Na+-K+-ATPase α1-subunit subtypes in zebrafish gill ionocytes
Authors: Liao Bo-Kai , Chen Ruo-Dong , Hwang Pung-Pung
Published: April 2009

In zebrafish ( Danio rerio), six distinct Na+-K+-ATPase (NKA) α1-subunit genes have been identified, and four of them, zatp1a1a.1, zatp1a1a.2, zatp1a1a.4, and zatp1a1a.5, are expressed in embryonic skin where different types of ionocytes appear. The present study attempted to test a hypothesis of whether these NKA α1 paralogues are specifically expressed and function in respective ionocytes. Double fluorescence in situ hybridization analysis demonstrated the specific expression of zatp1a1a.1, zatp1a1a.2, and zatp1a1a. 5 in NKA-rich (NaR) cells, Na+-Cl−cotransporter (NCC)-expressing cells, and H+-ATPase-rich (HR) cells, respectively, based on the colocalization of the three NKA α1 genes with marker genes of the respective ionocytes (epithelial Ca2+channel in NaR cells; NCC in NCC cells; and H+-ATPase and Na+/H+exchanger 3b in HR cells). The mRNA expression (by real-time PCR) of zatp1a1a.1, zatp1a1a.2, and zatp1a1a.5 were, respectively, upregulated by low-Ca2+, low-Cl−, and low-Na+freshwater, which had previously been reported to stimulate uptake functions of Ca2+, Cl−, and Na+. However, zatp1a1a.4 was not colocalized with any of the three types of ionocytes, nor did its mRNA respond to the ambient ions examined. Taken together, zATP1a1a.1, zATP1a1a.2, and zATP1a1a.5 may provide driving force for Na+-coupled cotransporter activity specifically in NaR, NCC, and HR cells, respectively.
Cortisol and corticosterone in immune organs and brain of European starlings: developmental changes, effects of restraint stress, comparison with zebra finches
Authors: Schmidt Kim L. , Chin Eunice H. , Shah Amit H. , Soma Kiran K.
Published: April 2009

Glucocorticoids (GCs) are produced in the adrenal glands and also in extra-adrenal sites, including immune organs and brain. Here, we examined regulation of systemic GC levels in plasma and local GC levels in immune organs and brain during development. We conducted two studies and examined a total of 462 samples from 70 subjects. In study 1, we determined corticosterone and cortisol levels in the plasma, immune organs, and brain of wild European starlings on posthatch day 0 (P0) and P10 (at baseline and after 45 min of restraint). Baseline corticosterone and cortisol levels were low in the immune organs and brain at P0 and P10, providing little evidence for local GC synthesis in starlings. At P0, restraint had no significant effects on corticosterone or cortisol levels in the plasma or tissues; however, there was a trend for restraint to increase both corticosterone and cortisol in the immune organs. At P10, restraint increased corticosterone levels in the plasma and all tissues, but restraint increased cortisol levels in the plasma, thymus, and diencephalon only. In study 2, we directly compared GC levels in European starlings and zebra finches at P4. In zebra finches but not starlings, cortisol levels were higher in the immune organs than in plasma. This difference in immune GC levels might be due to evolutionary lineage, life history strategy, or experiential factors, such as parasite exposure. This is the first study to measure immune GC levels in wild animals and one of the first studies to measure local GC levels after restraint stress.
Expression and modulation of translocator protein and its partners by hypoxia reoxygenation or ischemia and reperfusion in porcine renal models
Authors: Favreau Frederic , Rossard Ludivine , Zhang Keqiang , Desurmont Thibault , Manguy Emilie , Belliard Aude , Fabre Stéphane , Liu Jun , Han Zeqiu , Thuillier Raphael , Papadopoulos Vassilios , Hauet Thierry
Published: April 2009

Translocator protein (TSPO), formerly known as the peripheral-type benzodiazepine receptor, is an 18-kDa drug- and cholesterol-binding protein localized to the outer mitochondrial membrane and implicated in a variety of cell and mitochondrial functions. To determine the role of TSPO in ischemia-reperfusion injury (IRI), we used both in vivo and in vitro porcine models: an in vivo renal ischemia model where different conservation modalities were tested and an in vitro model where TSPO-transfected porcine proximal tubule LLC-PK1cells were exposed to hypoxia and oxidative stress. The expression of TSPO and its partners in steroidogenic cells, steroidogenic acute regulatory protein (StAR) and cytochrome P-450 side chain cleavage CYP11A1, as well as the impact of TSPO overexpression and exposure to TSPO ligands in vitro in hypoxia-ischemia conditions were investigated. Hypoxia induced caspase activation, reduction of ATP content, and LLC-PK1cell death. Transfection and overexpression of TSPO rescued the cells from the detrimental effects of hypoxia and reoxygenation. Moreover, TSPO overexpression was accompanied by a reduction of H2O2-induced necrosis. TSPO drug ligands did not affect TSPO-mediated functions. In vivo, TSPO expression was modulated by IRI and during regeneration particularly in proximal tubule cells, which do not express this protein at the basal level. Under the same conditions, StAR and CYP11A1 protein and gene expression was reduced without apparent relation to TSPO changes. Pregnenolone was identified and measured in the pig kidney. Pregnenolone synthesis was not affected by the experimental conditions used. Taken together, these results indicate that changes in TSPO expression in kidney regenerating tissue could be important for renal protection and maintenance of kidney function.
Reverse Optical Trawling for Synaptic Connections In Situ
Authors: Sasaki Takuya , Minamisawa Genki , Takahashi Naoya , Matsuki Norio , Ikegaya Yuji
Published: April 2009

We introduce a new method to unveil the network connectivity among dozens of neurons in brain slice preparations. While synaptic inputs were whole cell recorded from given postsynaptic neurons, the spatiotemporal firing patterns of presynaptic neuron candidates were monitored en masse with functional multineuron calcium imaging, an optical technique that records action potential–evoked somatic calcium transients with single-cell resolution. By statistically screening the neurons that exhibited calcium transients immediately before the postsynaptic inputs, we identified the presynaptic cells that made synaptic connections onto the patch-clamped neurons. To enhance the detection power, we devised the following points: 1) [K+]e was lowered and [Ca2+]e and [Mg2+]e were elevated, to reduce background synaptic activity and minimize the failure rate of synaptic transmission; and 2) a small fraction of presynaptic neurons was specifically activated by glutamate applied iontophoretically through a glass pipette that was moved to survey the presynaptic network of interest (“trawling”). Then we could theoretically detect 96% of presynaptic neurons activated in the imaged regions with a 1% false-positive error rate. This on-line probing technique would be a promising tool in the study of the wiring topography of neuronal circuits.
Brain Polarization Enhances the Formation and Retention of Motor Memories
Authors: Galea Joseph M. , Celnik Pablo
Published: April 2009

One of the first steps in the acquisition of a new motor skill is the formation of motor memories. Here we tested the capacity of transcranial DC stimulation (tDCS) applied over the motor cortex during motor practice to increase motor memory formation and retention. Nine healthy individuals underwent a crossover transcranial magnetic stimulation (TMS) study designed to test motor memory formation resulting from training. Anodal tDCS elicited an increase in the magnitude and duration of motor memories in a polarity-specific manner, as reflected by changes in the kinematic characteristics of TMS-evoked movements after anodal, but not cathodal or sham stimulation. This effect was present only when training and stimulation were associated and mediated by a differential modulation of corticomotor excitability of the involved muscles. These results indicate that anodal brain polarization can enhance the initial formation and retention of a new motor memory resulting from training. These processes may be the underlying mechanisms by which tDCS enhances motor learning.
Whole Cell Recordings From Visualized Neurons in the Inner Laminae of the Functionally Intact Spinal Cord
Authors: Dyck Jason , Gosgnach Simon
Published: April 2009

The in vitro whole spinal cord preparation has been an invaluable tool for the study of the neural network that underlies walking because it provides a means of recording fictive locomotor activity following surgical and/or pharmacological manipulation. The recent use of molecular genetic techniques to identify discrete neuronal populations in the spinal cord and subsequent studies showing some of these populations to be involved in locomotor activity have been exciting developments that may lead to a better understanding of the structure and mechanism of function of this neural network. It would be of great benefit if the in vitro whole spinal cord preparation could be updated to allow for the direct targeting of genetically defined neuronal populations, allowing each to be characterized physiologically and anatomically. This report describes a new technique that enables the visualization of, and targeted whole cell patch-clamp recordings from, genetically defined populations of neurons while leaving connectivity largely intact. The key feature of this technique is a small notch cut in the lumbar spinal cord that reveals cells located in the intermediate laminae while leaving the ventral portion of the spinal cord—the region containing the locomotor neural network—untouched. Whole cell patch-clamp recordings demonstrate that these neurons are healthy and display large rhythmic depolarizations that are related to electroneurogram bursts recorded from ventral roots during fictive locomotion. Intracellular labeling demonstrates that this technique can also be used to map axonal projection patterns of neurons. We expect that this procedure will greatly facilitate electrophysiological and anatomical study of important neuronal populations that constitute neural networks throughout the CNS.
Developmental Changes in Dendritic Shape and Synapse Location Tune Single-Neuron Computations to Changing Behavioral Functions
Authors: Meseke Maurice , Evers Jan Felix , Duch Carsten
Published: April 2009

During nervous system development, different classes of neurons obtain different dendritic architectures, each of which receives a large number of input synapses. However, it is not clear whether synaptic inputs are targeted to specific regions within a dendritic tree and whether dendritic tree geometry and subdendritic synapse distributions might be optimized to support proper neuronal input-output computations. This study uses an insect model where structure and function of an individually identifiable neuron, motoneuron 5 (MN5), are changed while it develops from a slow larval crawling into a fast adult flight motoneuron during metamorphosis. This allows for relating postembryonic dendritic remodeling of an individual motoneuron to developmental changes in behavioral function. Dendritic architecture of MN5 is analyzed by three-dimensional geometric reconstructions and quantitative co-localization analysis to address the distribution of synaptic terminals. Postembryonic development of MN5 comprises distinct changes in dendritic shape and in the subdendritic distribution of GABAergic input synapses onto MN5. Subdendritic synapse targeting is not a consequence of neuropil structure but must rely on specific subdendritic recognition mechanisms. Passive multicompartment simulations indicate that postembryonic changes in dendritic architecture and in subdendritic input synapse distributions may tune the passive computational properties of MN5 toward stage-specific behavioral requirements.
Synergistic Roles of GABAA Receptors and SK Channels in Regulating Thalamocortical Oscillations
Authors: Kleiman-Weiner Max , Beenhakker Mark P. , Segal William A. , Huguenard John R.
Published: April 2009

Rhythmic oscillations throughout the cortex are observed during physiological and pathological states of the brain. The thalamus generates sleep spindle oscillations and spike-wave discharges characteristic of absence epilepsy. Much has been learned regarding the mechanisms underlying these oscillations from in vitro brain slice preparations. One widely used model to understand the epileptiform oscillations underlying absence epilepsy involves application of bicuculline methiodide (BMI) to brain slices containing the thalamus. BMI is a well-known GABAA receptor blocker that has previously been discovered to also block small-conductance, calcium-activated potassium (SK) channels. Here we report that the robust epileptiform oscillations observed during BMI application rely synergistically on both GABAA receptor and SK channel antagonism. Neither application of picrotoxin, a selective GABAA receptor antagonist, nor application of apamin, a selective SK channel antagonist, alone yielded the highly synchronized, long-lasting oscillations comparable to those observed during BMI application. However, partial blockade of SK channels by subnanomolar concentrations of apamin combined with picrotoxin sufficiently replicated BMI oscillations. We found that, at the cellular level, apamin enhanced the intrinsic excitability of reticular nucleus (RT) neurons but had no effect on relay neurons. This work suggests that regulation of RT excitability by SK channels can influence the excitability of thalamocortical networks and may illuminate possible pharmacological treatments for absence epilepsy. Finally, our results suggest that changes in the intrinsic properties of individual neurons and changes at the circuit level can robustly modulate these oscillations.
Immunohistochemical Localization of the Bradykinin B1 and B2 Receptors in Human Nasal Mucosa
Authors: Shirasaki Hideaki , Kanaizumi Etsuko , Himi Tetsuo
Published: April 2009

Bradykinin (BK) has been tobe thought a potent mediator involved in allergic rhinitis because BK was recovered from the nasal lavage fluid of allergic rhinitis patients after allergen provocation and BK receptor antagonists relief nasal allergic symptoms. Two mammalian BK receptor subtypes, B1 and B2, have been defined based on their pharmacological properties. We investigated the localization of these receptors by immunohistochemistry. Human turbinates were obtained after turbinectomy from 12 patients with nasal obstruction refractory to medical therapy. The immunohistochemical study revealed that epithelial cells, submucosal glands, fibroblast, vascular smooth muscle, vascular endothelial cells, and macrophages showed immunoreactivity for both B1 and B2 receptors. The B2 receptor expression was found in peripheral nerve fibers, whereas the B1 expression was not observed in nerves. The results may have an important clinical implication for understanding the differential roles of BK receptor subtypes on upper airway diseases such as allergic rhinitis and nonallergic rhinitis.
Topological and Kinematic Singularities for a Class of Parallel Mechanisms
Authors: Shvalb Nir , Shoham Moshe , Bamberger Hagay , Blanc David
Published: April 2009

We study singularities for a parallel mechanism with a planar moving platform inℝd  (d= 2, 3), with joints which are universal, spherical (spatial case), or rotational (planar case). For such mechanisms, we give a necessary condition for a topological singularity to occur, and describe the corresponding kinematic singularity. An example is provided.
Cylindrical Dielectric Resonator Antennas with Harmonic Control as an Active Antenna Radiator
Authors: Lucci L. , Manara G. , Nepa P. , Pelosi G. , Selleri S.
Published: April 2009

A cylindrical dielectric resonator antenna is proposed as a radiator for an active integrated antenna. Harmonic tuning, which is the key step in designing active antenna radiators, is achieved via a combination of shape factor control over the resonator and insertion of reactive elements in the feed system. Numerical simulations are carried out in a finite elements framework and a layout for the complete antenna is proposed, aimed at compactness for subsequent utilization of the radiator as an element in an active array for satellite communications.
Solutions for m‐Point BVP with Sign Changing Nonlinearity
Authors: Su Hua
Published: April 2009

We study the existence of positive solutions for the following nonlinear m‐point boundary value
problem for an increasing homeomorphism and homomorphism with sign changing nonlinearity:
, 0 < t < 1,
, , where ϕ : R → R is an increasing homeomorphism and homomorphism and ϕ(0) = 0. The nonlinear term f may
change sign. As an application, an example to demonstrate our results is given. The conclusions in this paper essentially extend and improve the known results.
Baboon Palm Nut Harvesters in Ancient Egypt: New (Ancient) Evidence, New Questions
Authors: Deputte B.L. , Anderson J.R.
Published: April 2009

It is well documented that hamadryas baboons were used by the ancient Egyptians to pick fruits, but it is not well known that these baboons were also used to collect palm nuts. We describe this practice as it is depicted on a painting on a rarely exhibited ancient Egyptian artefact. Striking similarities with the modern use of pig-tailed macaques as coconut harvesters are described, raising new questions about the demise of the practice in Africa and its continuation in South-East Asia.
Spectrophotometric Method for the Assay of Human Blood Coagulation Factor VIII
Authors: van Dieijen G. , van Dieijen-Visser M.P. , Franssen J. , Hemker H.C.
Published: April 2009

A spectrophotometric method for the assay of human blood coagulation factor VIII in plasma is presented. The chromogenic assay for factor VIIL·C in plasma is performed in 3 steps: (1) activation of factor VIII by thrombin; (2) activation of factor X in a mixture of factor X, factor IXa, phospholipids/Ca2+ and plasma containing activated factor VIII, and (3) determination of the rate of factor Xa formation with the chromogenic substrate S2337. Within-assay variation was between 5 and 6.9% for factor VIIL·C activities between 20 and 150%. Clotting and chromogenic factor VIIL·C activities were compared in plasma of 50 normal healthy donors (coefficient of correlation r = 0.83).
The Capillary Thrombometer Revisited
Authors: Kadota R.P. , Bowie E.J.W. , Emslander H.C. , Fass D.N. , Ilstrup D.M.
Published: April 2009

A modified capillary thrombometer was constructed to study the rate of thrombus formation using heparinized whole blood (2 U/ml) obtained from normal adults (n = 22) and children (n = 20) and patients with hemophilia A (n = 10) or von Willebrand’s disease (n = 8). The median thrombosis times were as follows: normal adults =12.8 min (range = 4.5–26.0), normal children = 13.3 min (range = 5.7–29.0), patients with hemophilia A = 37.2 min (range = 20.0–60.0 min), and patients with von Willebrand’s disease = 60.0 min (range = 37.2–60.0). Significant differences were demonstrated between all groups of subjects, except between normal adults and children. The capillary thrombometer appears to measure thrombus formation dependent on adequate Willebrand factor and platelets.
Influence of Heparin, Aspirin, Streptokinase and Factor VIII (AHF) on Amorphous Electron-Dense Substance, a Mediator of Platelet and Thrombus Adhesion in vivo
Authors: Herrmann K.S. , Voigt W.-H. , Kreuzer H.
Published: April 2009

Platelet adherence and aggregation on vessel walls are the first crucial steps in thrombogenesis and atherosclerosis. Whether platelets can be activated on damaged endothelial cells or their activation is achieved only when subendothelial structures are exposed was controversially discussed in the past. Recently, an electron-microscopic study has revealed an amorphous electron-dense substance (AEDS) after endothelial cell damage and has discussed its role as a possible trigger of thrombogenesis. The aim of the present study is to elucidate the role and origin of this substance and to investigate the influence which inhibitors of platelet function (acetylsalicylic acid), coagulation (heparin), stimulation of fibrinolysis (streptokinase) and addition of factor VIII (AHF) have on AEDS.
Lack of Effect of Aspirin on Cigarette Smoke-Induced Increase in Circulating Endothelial Cells
Authors: Davis James W. , Shelton Loretta , Eigenberg David A. , Hignite Charles E.
Published: April 2009

A random-order, double-blind crossover study was done to compare the effects of placebo and two different doses of aspirin on the endothelial cell count of venous blood before and after smoking. Each of 17 male habitual smokers with coronary artery disease smoked two cigarettes during each of three 20-min periods separated by 2 weeks. Each patient was asked to take a tablet containing 150 mg of aspirin, 300 mg of aspirin or a placebo 12 h before each experimental smoking period and to abstain from smoking in the interim. Endothelial cell counts were determined by means of differential centrifugation and phase-contrast microscopy and nicotine by gas chromatography. After ingestion of placebo, the mean endothelial cell counts ( ± SD) were 2.7 ± 0.8 and 4.5 ± 0.9 per counting chamber before and after smoking respectively (p < 0.001). Endothelial cell counts and plasma nicotine concentrations were not significantly correlated. Neither the mean presmoking values nor smoking-induced changes in either variable were affected either dose of aspirin. The data suggest that smoking caused acute endothelial cell desquamation which was not prevented by aspirin.