bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Postentry Resistance to AKV Ecotropic Mouse Gammaretroviruses in the African Pygmy Mouse,
Mus minutoides
Authors: Yan Yuhe , Kozak Christine A.
Published: April 2008

Cells of
Mus minutoides
, an African pygmy mouse of the subgenus
Nannomys
, are susceptible to ecotropic Moloney and Friend mouse leukemia viruses (MLVs) but not to AKV-type MLVs. Transfected MA139 ferret cells expressing the mCAT-1 cell surface receptor, with the minCAT-1 substitutions K222Q and V233L, did not restrict AKV MLV. The resistance of
M. minutoides
cells to AKV MLV was not relieved by inhibitors of glycosylation or by the introduction of NIH 3T3 mCAT-1. Resistance is thus not mediated by receptor sequence variation, expression level, or glycosylation.
M. minutoides
cells are also infectible with LacZ pseudotypes having AKV Env and Moloney MLV (MoMLV) Gag proteins, further indicating that AKV Env sequence variations do not contribute to the observed block. The pattern of virus resistance in
M. minutoides
differs from that of the known variants of the
Fv1
postentry resistance gene;
M. minutoides
is equally resistant to N-, B-, and NR-tropic AKV viruses and is equally susceptible to NR- and NB-tropic Friend MLVs. This novel resistance blocks replication before reverse transcription, whereas
Fv1
generally restricts replication after reverse transcription;
M. minutoides
cells produce 2-long-terminal-repeat viral DNA circles and linear viral DNA after infection with MoMLV but not with AKV MLV. Analysis of MoMLV-AKV MLV chimeras determined that the target of resistance is in the virus capsid gene. Mutagenesis demonstrated that restriction is mediated by two amino acid substitutions, H117L and A110R; substitutions at these sites can also be targeted by the resistance genes
Fv1
and TRIM5α.
M. minutoides
cells thus have a novel postentry resistance to AKV MLVs.
Glycoproteins Required for Entry Are Not Necessary for Egress of Pseudorabies Virus
Authors: Klupp Barbara , Altenschmidt Jan , Granzow Harald , Fuchs Walter , Mettenleiter Thomas C.
Published: April 2008

In the current perception of the herpesvirus replication cycle, two fusion processes are thought to occur during entry and nuclear egress. For penetration, glycoproteins gB and gH/gL have been shown to be essential, whereas a possible role of these glycoproteins in nuclear egress remains unclear. Viral envelope glycoproteins have been detected by immunolabeling in the nuclear membrane as well as in primary enveloped particles in several herpesviruses, indicating that they might be involved in the fusion process. Moreover, a herpes simplex virus type 1 mutant simultaneously lacking gB and gH was described to be deficient in nuclear egress (A. Farnsworth, T. W. Wisner, M. Webb, R. Roller, G. Cohen, R. Eisenberg, and D. C. Johnson, Proc. Natl. Acad. Sci. USA 104:10187-10192, 2007). To analyze the situation in the related alphaherpesvirus pseudorabies virus (PrV), mutants carrying single and double deletions of glycoproteins gB, gD, gH, and gL were constructed and characterized. We show here that the simultaneous deletion of gB and gD, gB and gH, gD and gH, or gH and gL has no detectable effect on PrV egress, implying that none of these glycoproteins either singly or in the tested combinations is required for nuclear egress. In addition, immunolabeling studies using different mono- or polyclonal sera raised against various PrV glycoproteins did not reveal the presence of viral glycoproteins in the inner nuclear membrane or in primary virions. Thus, our data strongly suggest that different fusion mechanisms are active during virus entry and egress.
A Filovirus-Unique Region of Ebola Virus Nucleoprotein Confers Aberrant Migration and Mediates Its Incorporation into Virions
Authors: Shi Wei , Huang Yue , Sutton-Smith Mark , Tissot Berangere , Panico Maria , Morris Howard R. , Dell Anne , Haslam Stuart M. , Boyington Jeffrey , Graham Barney S. , Yang Zhi-Yong , Nabel Gary J.
Published: April 2008

The Ebola virus nucleoprotein (NP) is an essential component of the nucleocapsid, required for filovirus particle formation and replication. Together with virion protein 35 (VP35) and VP24, this gene product gives rise to the filamentous nucleocapsid within transfected cells. Ebola virus NP migrates aberrantly, with an apparent molecular mass of 115 kDa, although it is predicted to encode an ∼85-kDa protein. In this report, we show that two domains of this protein determine this aberrant migration and that this region mediates its incorporation into virions. These regions, amino acids 439 to 492 and amino acids 589 to 739, alter the mobility of Ebola virus NP by sodium dodecyl sulfate-polyacrylamide gel electrophoresis by 5 and 15 kDa, respectively, and confer similar effects on a heterologous protein, LacZ, in a position-independent fashion. Furthermore, when coexpressed with VP40, VP35, and VP24, this region mediated incorporation of NP into released viruslike particles. When fused to chimeric paramyxovirus NPs derived from measles or respiratory syncytial virus, this domain directed these proteins into the viruslike particle. The COOH-terminal NP domain comprises a conserved highly acidic region of NP with predicted disorder, distinguishing Ebola virus NPs from paramyxovirus NPs. The acidic character of this domain is likely responsible for its aberrant biochemical properties. These findings demonstrate that this region is essential for the assembly of the filamentous nucleocapsids that give rise to filoviruses.
Relationships between dissolved organic carbon concentrations, weather, and acidification in small Boreal Shield lakes
Authors: Keller W. (Bill) , Paterson Andrew M , Somers Keith M , Dillon Peter J , Heneberry Jocelyne , Ford Andrea
Published: April 2008

We used multiple linear regression analyses to explore empirical relationships between dissolved organic carbon (DOC) concentrations, weather, and acidification in long-term data sets from 12 small Boreal Shield lakes in Ontario, Canada. In two lakes in which pH changes have been very large (4.5 to ~6.0), pH explained most of the temporal variation in DOC concentrations. In the remaining lakes, long-term average previous temperature (on the scale of a decade or more) was usually the best explanatory variable for DOC concentrations. Lake-specific multiple regression models constructed from long-term and short-term attributes of weather (long-term average previous temperature and precipitation, winter–spring precipitation, summer precipitation, summer sunshine) and pH explained between 41% and 96% of the temporal variation in DOC concentrations during the entire monitoring period for these lakes (n = 16–26 years). Multiple regression models considering only the period common to all lakes, 1987 to 2003 (n = 16–17 years), explained 35%–96% of the variation in DOC concentrations. The importance of long-term and short-term attributes of weather in explaining temporal variations in DOC concentrations suggests that changes in climate will have large effects on lake clarity; however, the interactions between weather-related effects may be very complex.
Response of benthic macroinvertebrate communities to El Niño related drought events in six upland streams in south-central Ontario
Authors: Gilbert Beth , Dillon Peter J , Somers Keith M , Reid Ron A , Scott Lem
Published: April 2008

We examined the effects of extreme drought events on benthic macroinvertebrate (BMI) community structure in six forested upland streams in south-central Ontario, Canada, during a 9-year period. Variation in the mean winter El Niño – Southern Oscillation Index was strongly correlated with drought conditions (zero flow days) in the study streams. Drought onset and duration varied among study streams and among years. Below-average precipitation coincided with the occurrence of drought, although it remains unclear if snowfall and rainfall contributed equally to the impact of decreased precipitation. Increased relative abundance of Ephemeroptera, Plecoptera, and Trichoptera (EPT) one year following drought and decreased relative abundance two years after drought indicated high resistance but poor resilience. In contrast, chironomids showed poor resistance and high resilience. Although these patterns were not consistent across all streams, temporal coherence among streams was found in percent EPT, percent chironomids, and percent dipterans, suggesting that drought acts as a disturbance mechanism that simplifies benthos community assemblages. Biocriteria developed from 22 nearby reference streams indicated that abnormal BMI communities occurred only after recurring episodes of drought, indicating that the effects of drought are cumulative. Headwater streams may prove to be sentinel ecosystems for monitoring the impacts of climate change.
Stunting of Wild Coho Salmon (Oncorhynchus kisutch) in Seawater: Patterns of Plasma Thyroid Hormones, Cortisol, and Growth Hormone
Authors: Varnavsky Vladimir S. , Sakamoto Tatsuya , Hirano Tetsuya
Published: April 2008

Under natural conditions, some coho salmon presmolts (Oncorhynchus kisutch) in Kamchatka have been observed to migrate prematurely to the sea and fail to grow in brackish water for prolonged periods (natural stunts). Plasma levels of growth hormone, cortisol, thyroxine, and triiodothyronine were measured in coho salmon parr captured in the river (freshwater), smolts migrating downstream captured at the river mouth (brackish water), smolts in the sea (seawater), and natural stunts in the inlet (brackish water). The physiological conditions of natural stunts seem analogous to those of hatchery-derived stunts observed in hatchery-reared juveniles in sea pens, with normal plasma sodium concentration, low levels of thyroid hormones and cortisol, and high growth hormone levels.
Removal of Total Phosphorus and Phosphate by Peat Soils of the Florida Everglades
Authors: Jones Ronald D. , Amador José A.
Published: April 2008

Traditional estimates of soil and sediment phosphorus retention are based on orthophosphate (PO4) removal from water by soil or sediment columns under saturated water flow. These techniques may not reflect the P uptake of in situ soils accurately because the PO4 concentration of through-flowing water is often below detection limits in nonpolluted wetlands during the growing season. We used peat soils from the Florida Everglades in saturated flow and equilibrium sorption experiments to show that the uptake of PO4 reaches saturation quickly, potentially underestimating soil P binding capacity when compared with total phosphorus (TP) retention. The rate of TP uptake was constant for 2 d, while the rate of PO4 uptake slowed and followed saturation kinetics. The majority of the TP removed was associated with particles within a 1–20 μm size range. Experiments using both NaCl and nonionic detergent (Triton X–100) as well as batch equilibrium sorption studies indicate that the primary mechanism for TP removal by these soils is not straining. Removal of TP by these soils appears to involve abiotic mechanisms that include both hydrophobic and ionic interactions.
Colonization by Lotic Macroinvertebrates: A Review of Processes and Patterns
Authors: Mackay Rosemary J.
Published: April 2008

Ways in which invertebrates colonize lotic habitats are reviewed, tracing patterns in behaviour, trophic ecology, and life history that could lead to predictions concerning resilience of stream communities after disturbance. Patterns are described for small-scale experimental studies using introduced or natural substrates, for large-scale observations of new or rewatered channels, for rivers recovering from pollution, and for unstable rivers with fluctuating discharge. Colonization depends on invertebrate mobility (drift, swimming, crawling, and flight), substrate texture and associated food supplies, competition, and predation. Epilithon-browsers and filter feeders can use the resources of smooth stones; gatherers colonize as fine detritus accumulates; grazers increase as periphyton becomes established; shredders and predators tend to be late arrivals. Propagules for colonization are made more available by asynchronous and aseasonal life cycles, long oviposition periods, and refuges in the streambed or neighbouring waterbodies. Species in frequently disturbed streams benefit from these characteristics. Although disturbance may be due to stochastic factors, recovery is not due to chance. Recurring ecological patterns among early colonizers suggest that knowledge of the hydrologic regime, food resources, and dominant taxa can be used to predict the overall resilience of a stream community.
A core linkage map of the bumblebeeBombus terrestris
Authors: Wilfert Lena , Gadau Jürgen , Schmid-Hempel Paul
Published: April 2008

The bumblebee Bombus terrestris is an economically important pollinator and an emerging model species in quantitative and population genetics. We generated genetic linkage maps for 3 independent mapping populations of B. terrestris. The linkage map with the highest resolution had 21 linkage groups, which adequately represents the haploid chromosome number of B. terrestris (n = 18). This map can be considered saturated, with an average marker distance of 10.3 cM and an estimated genome coverage of 81%. Using flow cytometry, we have estimated the genome size of this species to be 625 Mb. With an estimated total recombination genome length of 2760 cM, this results in a ratio of 226 kb/cM between the physical and genetic genome sizes. A recurring set of microsatellites and amplified fragment length polymorphism (AFLP) markers allowed the alignment of 14 linkage groups between the 3 maps. We propose to adopt this core map as a reference tool for future genetic and molecular work in B. terrestris.
Étude de l’influence des paramètres de combustion sur la formation de SO2, de NO et de CO lors de la dégradation thermique de produits phytosanitaires d’usage courant en Afrique de l’Ouest
Authors: Bouda Médard , Rogaume Thomas , Segda B. Gérard , Sawadogo Paul W. , Koulidiati Jean
Published: April 2008

As we are faced with a constantly increasing quantity of industrial waste (namely, phytosanitary products), incineration is perceived as an interesting method for their disposal. Nevertheless, incineration can generate pollutants such as nitrogen oxides (NOx), sulfur oxides (SOx), carbon monoxide (CO), and other toxic gases. Therefore, it is important to optimize the combustion process to reduce these emissions. Studies performed during incineration of phytosanitary wastes show strong correlations between the generation of these pollutants and combustion parameters such as oxygen concentration, temperature, and residence time in the reactor core. In the present study, we focused more particularly on determining the influence of these parameters on the production of nitrogen monoxide (NO), CO, and sulfur dioxide (SO2) during the incineration of Cyperthion D and Cyperthion O, the two main phytosanitary products currently used in West Africa. The results showed that NO and SO2 emissions decrease with an increase in residence time, but increase with higher local oxygen concentrations and higher combustion temperatures in the reactor core. Inversely, CO emissions increase with an increase in residence time, but decrease with higher temperatures and higher local oxygen concentrations. This small-scale study allows us to derive the experimental conditions to pursue large-scale assays, in a rotatory incinerator, for the thermal processing of expired phytosanitary products.
Effect of media volume on mixing of biological aerated filters
Authors: Fatihah S. , Donnelly T.
Published: April 2008

Effect of reduced media volume on the mixing of biological aerated filters (BAF) was quantitatively determined. The degree of mixing was evaluated based on Reynolds numbers (Re) while the nonideality of the flow was assessed from information of residence time distribution. At HRTs of 1411, 1111, 781 and 581 min and their, respectively, approximate OLRs of 2, 3, 4, and 6 kg COD·m–3·d–1, the Re in the partial-bed were 40300, 36100, 25500, and 40400, respectively, whilst those of the full-bed were 19500, 20500, 11700, and 26400. Porosity of the BAF is a bed characteristic resulting from the balance between the effect of biomass accumulation due to growth and biomass loss due to shear stress, arising from increased organic loadings, gas flow, and increased upflow velocity. The number of tanks, calculated from the residence time distribution data, is either 1 or 2 (rounded up to an integer). This indicates the occurrence of a completely mixed pattern inside both reactors.
Chemical functionalization and modification of surface-bound cystamine–glycine monolayers on gold nanoparticles
Authors: Dasog Mita , Kavianpour Amir , Paige Matthew F , Kraatz Heinz-Bernhard , Scott Robert W.J.
Published: April 2008

Herein, we report the synthesis, characterization, and post-functionalization of Au nanoparticles that have been surface-modified with glycine–cystamine (Gly-CSA) stabilizing groups. We show that Au monolayer protected clusters (MPCs) can be synthesized via the Brust–Schiffrin method using a Boc-Gly–CSA stabilizer, followed by efficient removal of the Boc protecting group with trifluoroacetic acid. The resulting Gly–CSA Au MPCs are characterized via UV–vis, TEM, and 1H NMR, and are stable in solution over long periods of time. Finally, we show that the Gly–CSA Au MPCs can be further functionalized with nearly stoichiometric yields using activated esters of stearic acid and a Bodipy dye derivative. Thus, this work provides an alternative, general approach for the modification of the surface chemistry of MPCs.Key words: gold nanoparticles, peptide stabilizers, dyes.
Feasibility of sigmatropic rearrangement on electron-deficient coumarinyl ketones
Authors: Dutta Lakshmi Narayan , De Banani , Pal Godhuli , Patra Amarendra
Published: April 2008

Different alkyl/aryl 7-hydroxy-8-coumarinyl ketones were converted to 7-O-allyl and 7-O-cyclohexenyl ethers and the study of hitherto unreported sigmatropic rearrangement on 7-O-allyl and 7-O-cyclohex-2'-ene-1'-ylcoumarinyl ketones prepared is accounted herein. The rearrangement yielded alkyl/aryl 6-allyl-7-hydroxy-8-coumarinyl ketones 3 and alkyl/aryl 6-cyclohex-2'-en-1'-yl-7-hydroxy-8-coumarinyl ketones 7 as the major products. Interestingly, unusual selectivity was observed in the case of alkyl 7-O-allylcoumarinyl ketones. Thus alkyl 3-allyl-7-hydroxy-8-coumarinyl ketones 4 and alkyl 8-allyl-7-hydroxy-6-coumarinyl ketones 5 were the outcome from alkyl 7-O-allyl-8-coumarinyl ketones and alkyl 4-methyl-7-O-allyl-8-coumarinyl ketones, respectively, albeit in minor yields.Key words: allyloxycoumarinyl ketones, 7-O-cyclohex-2'-en-1'-ylcoumarinyl ketones, sigmatropic rearrangement, 3-allylcoumarinyl ketones, 8-allylcoumarinyl ketones.
Rooting depths and successional development of selected boreal forest communities
Authors: Strong W. L , Roi G. H. La
Published: April 2008

The root density and depth patterns of four boreal forest age sequences were analyzed for successional trends. Rooting depths increased with age on sandy substrates which supported aspen (Populustremuloides Michx.) and jack pine (Pinusbanksiana Lamb.) communities. Rooting depth did not change in an aspen series on fine-textured substrates or in a black spruce (Piceamariana (Mill.) BSP) series growing on organic substrates. Plant communities growing on mineral soils showed a decrease in near-surface root densities and understory vascular plant cover with increasing age. Maximum rooting was deepest on sandy substrates and shallowest on organic deposits. Roots in all stands were concentrated near the ground surface. In most cases 50% of all roots were located within 15 cm of the forest floor. Root densities in this zone ranged from 11 000 to 30 000 roots m−2 of vertical surface. Densities were approximately 4300 roots m−2 for the overall rooting zone.
Effects of different vesicular–arbuscular mycorrhizal fungi on growth of Fraxinusamericana
Authors: Furlan Valentin , Fortin J. André , Plenchette Christian
Published: April 2008

White ash seedlings (Fraxinusamericana L.) were inoculated with five species of endomycorrhizal fungi. On the 2nd week after transplantation, growth of inoculated plants differed from control plants. Growth also differed between each fungal species used, but the difference decreased after 82 days of culture. Only dry mass remained higher in plants inoculated with Glomusepigaeum Daniels & Trappe, Glomus sp. No. 3, and Glomusmonosporum Gerd. & Trappe. A significant growth enhancement was obtained even with a low level of root colonization.
Ecological adaptations in Douglas-fir (Pseudotsugamenziesii var. glauca) populations. III. Central Idaho
Authors: Rehfeldt Gerald E.
Published: April 2008

Growth, phenology, and cold hardiness of seedlings from 74 populations of Douglas-fir (Pseudotsugamenziesii var. glauca (Beissn.) Franco) from central Idaho were compared in four contrasting environments. Analyses of 3-year-old seedlings revealed population differentiation for eight variables: bud burst, bud set, multiple flushing, height, deviation from regression of 3-year height on 2-year height, spring frost damage, fall frost damage, and winter injury. These analyses, as well as high intercorrelations among population means, suggested that adaptations result from a balance between selection for a high growth potential in mild environments and selection for cold hardiness in severe environments. Consequently, genetic variation among populations was closely related to the elevation, geography, and climate of the seed source.
Analyses of mineral elements in vegetative buds and needles from young and old trees of Piceaabies
Authors: Arnold Sara Von , Roomans Godfried M.
Published: April 2008

The mineral contents of vegetative buds and needles collected from young plants and old trees of Piceaabies (L.) Karst. were determined. It was found that the contents of Cl, K, and Na were significantly higher in buds from old trees than in buds from young plants. Since the Na concentration increased more with age than the K concentration, the K:Na ratio decreased with age. In addition, dry weight was significantly higher in buds from old trees than in buds from young plants. Similar age-dependent differences could not be observed in the needle tissue.
Frost hardiness as acquired by Douglas-fir seedlings in three Pacific Northwest nurseries
Authors: Schuch Ursula K. , Duryea Mary L. , Fuchigami L. H.
Published: April 2008

Two-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings from two seed sources raised in three nurseries in Oregon and Washington were tested for differences in frost hardiness between September 1985 and January 1986. The objective was to determine whether nursery location significantly influenced hardiness. Seedlings were tested by whole-plant freezing to various temperatures, followed by six evaluations of frost hardiness of needle, bud, and stem tissues. Seedlings at the highest nursery had the hardiest needles and those at the coastal nursery the least hardy needles. Bud hardiness, calculated over time, differed between seed sources but not among nurseries. Stem acclimation followed the pattern of needle hardening from November to January. A regression equation calculated to predict frost hardiness from climatic data and elevation of the nurseries showed that elevation, photoperiod, and number of days of frost were the most important independent factors (R2 = 0.29).
Competitive interactions of whiteleaf manzanita, herbs, Douglas-fir, and ponderosa pine in southwest Oregon
Authors: White Diane E. , Newton Michael
Published: April 2008

Whiteleaf manzanita (Arctostaphylosviscida Parry) was established on three sites at densities ranging from 0 to 27 000 seedlings/ha in 2-year-old mixed stands of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and ponderosa pine (Pinusponderosa Dougl. ex Laws.). Invading herbs were controlled by spraying all plots, except one at each site at the 13 500 manzanita/ha density level. Intraspecific manzanita competition reduced individual shrub basal diameter, leaf area, biomass, and canopy volume by the 3rd year of our study. In contrast, these variables increased at the highest density in the manzanita stand. Stem volume of 5-year-old conifers was reduced in relation to manzanita density, biomass, leaf area index, and canopy cover. The presence of herbaceous vegetation reduced both manzanita and conifer growth by the 3rd year.
LOOP QUANTUM GRAVITY
Authors: THIEMANN THOMAS
Published: April 2008

We describe the canonical approach to quantum gravity and report on the status of its most advanced implementation, Loop Quantum Gravity (LQG).
COMPARING LQG WITH THE LINEARIZED THEORY
Authors: MAGLIARO ELENA , PERINI CLAUDIO
Published: April 2008

We illustrate the conceptual scenario of the general boundary formulation for field theories and present a brief description of the calculus of graviton propagator in the context of LQG. Then we analyze the possibility of comparing this result with the graviton propagator in perturbative quantum gravity. For this purpose we demonstrate the compatibility of harmonic and radial gauge; it allows to simultaneously impose both gauges and to obtain an expression for the propagator comparable with the one provided by LQG.
EQUILIBRIUM CONFIGURATIONS IN THE DOUBLE REISSNER-NORDSTROM EXACT SOLUTION
Authors: PIZZI MARCO , PAOLINO ARMANDO
Published: April 2008

The double Reissner-Nordstrom (RN) solution without strings nor struts, recently found by Alekseev and Belinski, shows that classically-forbidden equilibria are allowed for a naked singularity near a black hole.

In the following we shows the plots of the electric force lines in three qualitatively different situations: equal-signed charges, opposite charges and the case of a naked singularity near a neutral black hole.
MIXMASTER DYNAMICS IN THE WHEELER-DEWITT FRAMEWORK
Authors: BENINI RICCARDO , MONTANI GIOVANNI
Published: April 2008

In this work we present an analysis of the Mixmaster model in the Wheeler-DeWitt framework. After a brief review of the classical evolution, several aspects of the semi-classical and of the quantum dynamics are discussed: the most important results we will present are a possible operator ordering obtained from the semi-classical analysis and the full characterization of the quantum dynamics in Misner-Chitré like variables.
NONCOMMUTATIVE GEOMETRIES: AN OVERVIEW
Authors: PERINI CLAUDIO
Published: April 2008

I make a very introductory overview of noncommutative geometries, focusing on the DFR model for Minkowski space; in this model the noncommutativity, or “fuzziness”, of spacetime events emerges at semiclassical level putting together the Heisenberg principle with general relativity.
LORENTZ GAUGE THEORY AND SPINOR INTERACTION
Authors: CARLEVARO NAKIA , LECIAN ORCHIDEA MARIA , MONTANI GIOVANNI
Published: April 2008

A gauge theory of the Lorentz group, based on the different behavior of spinors and vectors under local transformations, is formulated in a flat space-time and the role of the torsion field within the generalization to curved space-time is briefly discussed.

The spinor interaction with the new gauge field is then analyzed assuming the time gauge and stationary solutions, in the non-relativistic limit, are treated to generalize the Pauli equation.
EXPONENTIAL LAGRANGIAN FOR THE GRAVITATIONAL FIELD AND THE PROBLEM OF VACUUM ENERGY
Authors: LECIAN ORCHIDEA MARIA , MONTANI GIOVANNI
Published: April 2008

We will analyze two particular features of an exponential gravitational Lagrangian. On the one hand, while this choice of the Lagrangian density allows for two free parameters, only one scale, the cosmological constant, arises as fundamental when the proper Einsteinian limit is to be recovered. On the other hand, the vacuum energy arising from f(R) theories such that f(0) ≠ 0 needs a cancellation mechanism, by which the present value of the cosmological constant can be recast.
Attenuation of retinal endothelial cell migration and capillary morphogenesis in the absence of bcl-2
Authors: Kondo Shuji , Tang Yixin , Scheef Elizabeth A. , Sheibani Nader , Sorenson Christine M.
Published: April 2008

Apoptosis plays a critical role during development and in the maintenance of the vascular system. B-cell leukemia lymphoma 2 (bcl-2) protects endothelial cells (EC) from apoptosis in response to a variety of stimuli. Previous work from this laboratory demonstrated attenuation of postnatal retinal vascular development and retinal neovascularization during oxygen-induced ischemic retinopathy in bcl-2-deficient (bcl-2−/−) mice. To gain further insight into the function of bcl-2 in the endothelium, we isolated retinal EC from bcl-2+/+ and bcl-2−/− mice. Retinal EC lacking bcl-2 demonstrated reduced cell migration, tenascin-C expression, and adhesion to vitronectin and fibronectin. The bcl-2−/− retinal EC also failed to undergo capillary morphogenesis in Matrigel. In addition, using an ex vivo angiogenesis assay, we observed reduced sprouting from aortic rings grown in culture from bcl-2−/− mice compared with bcl-2+/+ mice. Furthermore, reexpression of bcl-2 was sufficient to restore migration and capillary morphogenesis defects observed in bcl-2−/− retinal EC. Mechanistically, bcl-2−/− cells expressed significantly less endothelial nitric oxide synthase, an important downstream effecter of proangiogenic signaling. This may be attributed to increased oxidative stress in the absence of bcl-2. In fact, incubation of retinal EC or aortic rings from bcl-2−/− mice with the antioxidant N-acetylcysteine rescued their capillary morphogenesis and sprouting defects. Thus, bcl-2-mediated cellular functions play important roles not only in survival but also in proangiogenic phenotype of EC with a significant impact on vascular development and angiogenesis.
Leptin extends the anorectic effects of chronic PYY(3-36) administration in ad libitum-fed rats
Authors: Unniappan Suraj , Kieffer Timothy J.
Published: April 2008

Acute administration of peptide YY(3-36) [PYY(3-36)] results in a reduction in food intake in several different vertebrates. However, long-term continuous administration of PYY(3-36) causes only a transient reduction in food intake, thus potentially limiting its therapeutic efficacy. We hypothesized that a fall in leptin levels associated with reduced food intake could contribute to the transient anorectic effects of continuous PYY(3-36) infusion and thus that leptin replacement might prolong the anorectic effects of PYY(3-36). Seven-day administration of 100 μg·kg body wt−1·day−1 PYY(3-36) using osmotic minipumps caused a significant reduction in food intake of ad libitum-fed rats, but only for the first 2 days postimplantation. Circulating levels of leptin were reduced 1 day following continuous infusion of PYY(3-36), and combined leptin infusion at a dose of leptin that had no anorectic effects on its own (100 μg·kg body wt−1·day−1) prolonged the anorectic actions of PYY(3-36) in ad libitum-fed rats for up to 6 days postimplantation and yielded reduced weight gain compared with either peptide alone. The inhibitory effects of 100 μg·kg body wt−1·day−1 PYY(3-36) on food intake were absent in rats refed after a 24-h fast and substantially reduced at a dose of 1,000 μg·kg body wt−1·day−1 PYY(3-36). Leptin replacement was unable to recover the anorectic effects of PYY(3-36) in fasted rats. Our results suggest that an acute fall in leptin levels is not solely responsible for limiting duration of action of chronic PYY(3-36) infusion, yet chronic coadministration of a subanorectic dose of leptin can extend the anorectic effects of PYY(3-36).
Effect of interval versus continuous training on cardiorespiratory and mitochondrial functions: relationship to aerobic performance improvements in sedentary subjects
Authors: Daussin Frédéric N. , Zoll Joffrey , Dufour Stéphane P. , Ponsot Elodie , Lonsdorfer-Wolf Evelyne , Doutreleau Stéphane , Mettauer Bertrand , Piquard François , Geny Bernard , Richard Ruddy
Published: April 2008

The goal of the study was to determine the effects of continuous (CT) vs. intermittent (IT) training yielding identical mechanical work and training duration on skeletal muscle and cardiorespiratory adaptations in sedentary subjects. Eleven subjects (6 men and 5 women, 45 ± 3 years) were randomly assigned to either of the two 8-wk training programs in a cross-over design, separated by 12 wk of detraining. Maximal oxygen uptake (V̇o2max) increased after both trainings (9% with CT vs. 15% with IT), whereas only IT was associated with faster V̇o2kinetics (τ: 68.0 ± 1.6 vs. 54.9 ± 0.7 s, P < 0.05) measured during a test to exhaustion (TTE) and with improvements in maximal cardiac output (Qmax, from 18.1 ± 1.1 to 20.1 ± 1.2 l/min; P < 0.01). Skeletal muscle mitochondrial oxidative capacities ( Vmax) were only increased after IT (3.3 ± 0.4 before and 4.5 ± 0.6 μmol O2·min−1·g dw−1after training; P < 0.05), whereas capillary density increased after both trainings, with a two-fold higher enhancement after CT (+21 ± 1% for IT and +40 ± 3% after CT, P < 0.05). The gain of Vmaxwas correlated with the gain of TTE and the gain of V̇o2maxwith IT. The gain of Qmaxwas also correlated with the gain of VO2max. These results suggest that fluctuations of workload and oxygen uptake during training sessions, rather than exercise duration or global energy expenditure, are key factors in improving muscle oxidative capacities. In an integrative view, IT seems optimal in maximizing both peripheral muscle and central cardiorespiratory adaptations, permitting significant functional improvement. These data support the symmorphosis concept in sedentary subjects.
Effect of renal lipid accumulation on proximal tubule Na+/H+exchange and ammonium secretion
Authors: Bobulescu I. Alexandru , Dubree Michele , Zhang Jianning , McLeroy Paul , Moe Orson W.
Published: April 2008

Patients with metabolic syndrome have increased risk of uric acid nephrolithiasis due to lower urinary pH and impaired ammonium excretion. The pathophysiology underlying these urinary changes is unknown. We used two animal models and a cell culture model to study whether the alteration in renal acidification is associated with renal fat infiltration (steatosis). Compared with pair-fed lean control rats, Zucker diabetic fatty rats have higher renal triglyceride content, decreased urinary ammonium and pH, and lower levels of brush border membrane Na+/H+exchanger-3 (NHE3), a major mediator of ammonium excretion. High-fat feeding in Sprague-Dawley rats results in transient lowering of urinary ammonium and pH, with all parameters returning to normal when the animals resumed eating normal chow. This is consistent with an absence of diet-induced renal steatosis in these animals. To examine the direct effect of fat accumulation, we incubated opossum kidney (OKP) cells with a mixture of long-chain fatty acids and found accumulation of intracellular lipids with concomitant dose-dependent decrease in NHE3 activity, surface biotin-accessible NHE3 protein, and ammonium secretion. A lower dose of fatty acids that leads to intracellular lipid accumulation but does not change baseline NHE3 is sufficient to abolish the stimulation of NHE3 by insulin and to partially block the stimulation of NHE3 by glucocorticoid hormones; acid regulation of NHE3 in lipid-loaded OKP cells is not affected. These findings suggest that renal steatosis decreases ammonium secretion in the proximal tubule, in part by reducing NHE3 activity and by impairing the regulation of NHE3 by specific agonists.
Roll Tilt Psychophysics in Rhesus Monkeys During Vestibular and Visual Stimulation
Authors: Lewis Richard F. , Haburcakova Csilla , Merfeld Daniel M.
Published: April 2008

How does the brain calculate the spatial orientation of the head relative to gravity? Psychophysical measurements are critical to investigate this question, but such measurements have been limited to humans. In non-human primates, behavioral measures have focused on vestibular-mediated eye movements, which do not reflect percepts of head orientation. We have therefore developed a method to measure tilt perception in monkeys, derived from the subjective visual vertical (SVV) task. Two rhesus monkeys were trained to align a light bar parallel to gravity and performed this task during roll tilts, centrifugation, and roll optokinetic stimulation. The monkeys accurately aligned the light bar with gravity during static roll tilts but also demonstrated small orientation-dependent misperceptions of the tilt angle analogous to those measured in humans. When the gravito-inertial force (GIF) rotated dynamically in the roll plane, SVV responses remained closely aligned with the GIF during roll tilt of the head (coplanar canal rotational cues present), lagged slightly behind the GIF during variable-radius centrifugation (no canal cues present), and shifted gradually during fixed-radius centrifugation (orthogonal yaw canal cues present). SVV responses also deviated away from the earth-vertical during roll optokinetic stimulation. These results demonstrate that rotational cues derived from the semicircular canals and visual system have prominent effects on psychophysical measurements of roll tilt in rhesus monkeys and therefore suggest that a central synthesis of graviceptive and rotational cues contributes to percepts of head orientation relative to gravity in non-human primates.
Inhibitory Interactions Among Olfactory Glomeruli Do Not Necessarily Reflect Spatial Proximity
Authors: Reisenman Carolina E. , Heinbockel Thomas , Hildebrand John G.
Published: April 2008

Inhibitory interactions shape the activity of output neurons in primary olfactory centers and promote contrast enhancement of odor representations. Patterns of interglomerular connectivity, however, are largely unknown. To test whether the proximity of glomeruli to one another is correlated with interglomerular inhibitory interactions, we used intracellular recording and staining methods to record the responses of projection (output) neurons (PNs) associated with glomeruli of known olfactory tuning in the primary olfactory center of the moth Manduca sexta. We focused on Toroid I, a glomerulus in the male-specific macroglomerular complex (MGC) specialized to one of the two key components of the conspecific females' sex pheromone, and the adjacent, sexually isomorphic glomerulus 35, which is highly sensitive to Z-3-hexenyl acetate (Z3-6:OAc). We used the two odorants to activate these reference glomeruli and tested the effects of olfactory activation in other glomeruli. We found that Toroid-I PNs were not inhibited by input to G35, whereas G35 PNs were inhibited by input to Toroid-I PNs. We also recorded the responses of PNs arborizing in other sexually isomorphic glomeruli to stimulation with the sex pheromone and Z3-6:OAc. We found that inhibitory responses were not related to proximity to the MGC and G35: both distant and adjacent PNs were inhibited by stimulation with the sex pheromone, some others were affected by only one odorant, and yet others by neither. Similar results were obtained in female PNs recorded in proximity to female-specific glomeruli. Our findings indicate that inhibitory interactions among glomeruli are widespread and independent of their spatial proximity.
Synopsis of Panurgidæ (Hymenoptera)
Authors: Robertson Charles
Published: April 2008

Verbenapis - A Correctiondx.doi.org/10.1155/1923/65625
The Fiber Tracts of the Fused Thoracic Ganglia of the Adult Ephestia Kuehniella Zeller (Lepidoptera: Pyralidæ)
Authors: Pyle Robert W.
Published: April 2008

Correctiondx.doi.org/10.1155/1942/68541
The Taxonomic Value of the Ovipositor in the New England Species of the Genus Corythucha Stål (Hemiptera: Tingidae)
Authors: Feldman Albert Edward , Bailey Norman S.
Published: April 2008

The purpose of this paper is to present evidence that the ovipositor of the New England species in the genus Corythucha Stål is of taxonomic value in the separation of the species. This work is based upon a study of thirteen species, of which over 450 whole mounts have been prepared and examined.
Tylothrips Bruesi, A New Thysanopteron From Florida
Authors: Hood J. Douglas
Published: April 2008

The following species was taken within a few miles of
Professor Charles T. Brues′ home on the St. Johns River,
in Florida, shortly after we had collected together and
renewed an acquaintance which apparently began very
nearly fifty years ago, long before he became Professor
of Entomology at Harvard University and Editor of
Psyche.
A New Species of Ant Belonging to thePheidole Pilifera Complex (Hymenoptera: Formicidae)
Authors: Gregg Robert E.
Published: April 2008

A small collection of ants representing the genus Pheidole
from several localities in Western United States was given
to me recently by Dr. W. S. Creighton. Among these
specimens are samples of several colonies from Oregon
which prove to be a new species. The description of this
ant follows herewith
The Collembola of Lebanon and Western Syria. Part I. General Considerations and the Family Onychiuridae
Authors: Christiansen K.
Published: April 2008

The Collembolan fauna of the eastern end of the Mediterranean
is still very poorly known. Brown (1926)
made the first major contribution by describing twelve
species taken by Buxton and Evans in the region of
Amara and Baghdad in Iraq. Handschin (1942) recorded
all but one of these species from Palestine, and added 26
additional forms. In his recent paper upon the Collembola
taken during a speleological expedition in Lebanon, Cassagnau
(1951) added 25 new forms to this list. In
addition to these major works a number of smaller papers
have been published upon new material or further records.

The series of papers, of which this is the first, will
constitute a description of over 80 species collected from
Lebanon and Western Syria. More than 35 are new to
science or new records for the Near East. Collections
upon which this study was based were made from over
I00 localities including most of the major habitats of the
region. Caves were poorly represented, but these have
already been extensively investigated by Cassagnau (op. cit.).
Mexiterpes Sabinus, New Genus and New Species, a Mexican Troglobite (Diplopoda: Trichopetalidae)
Authors: Causey Nell B.
Published: April 2008

This troglobitic milliped is of unusual interest because it is the
type of a new genus and the first Mexican record of the family Trichopetalidae,
which previously has been known from Nova Scotia to
Louisiana, Oklahoma, and Colorado. If the genus has undergone
speciation as related genera have, then additional species and subspecies
will be found in other Mexican caves. Other millipeds from
Mexican caves have been described by R. V. Chamberlin (1942).

I am indebted to the members of the Texas Speleological Survey
for the specimen from which this species was described.
A New Genus and Species of Neotropical Horsefly (Diptera: Tabanidae)
Authors: Fairchild G. B.
Published: April 2008

The Neotropical Tabanidae are remarkable for the number of
bizarre forms which have developed, especiaIly in the Tribe Diachlorini.
Of the 146 generic names proposed at one time or another
to include Neotropical Tabanidae, 65 were proposed for Diachlorini.
The mortality rate among these names has been high, and conservative
students of the family will probably recognize hardly half of
these as useful. The proposal of another new genus in this fauna
may thus appear somewhat foolhardy; nevertheless, the subject of
this note presents a so far unique combination of characters which
disturbs current ideas as to relationships within the Tribe.
A New Species of Ligyrocoris Stal With a Key to the Northeastern Species (Hemiptera:Lygaeidae)
Authors: Sweet Merrill H.
Published: April 2008

In the course of current work upon the biology and ecology of the
Rhyparochrominae of New England, a new species of Ligyrocoris
was discovered. The species runs in Barber′s (1921) key to the
couplet separating diffusus (Uhler) from sylvestris (L.), but is distinct
from either species. While the new species is closely related to
these species, it is also quite close to L. depictus which is separated
out in a different part of Barber′s key.

These four closely related species are sympatric in New England,
although they are markedly different in their overall distribution. The
habitat preferences and life cycles of the species are quite different
(Sweet, unpublished). The habitat of the new species described
below is most unusual for the genus. The greater part of the type
series was collected along the margin of a small pond where sedge
clumps were standing in the water among occasional exposed rocks
rather than in relatively dry fields or slope habitats where the other
species occur. The species feeds upon the seeds of the sedge, Carex
stricta Lam, and its life cycle is apparently adapted to that of
the sedge, which fruits in late May and June. The insect becomes
adult in mid‐June and lays eggs until mid‐July. The eggs remain in
diapause over the summer and winter and hatch in May.
Studies on North American Carboniferous Insects. 2. The Genus Brodioptera, From the Maritime Provinces, Canada
Authors: Carpenter F. M.
Published: April 2008

Although few in number, the insects which have been found in the
Upper Carboniferous strata of the Maritime Provinces of Canada are
of exceptional interest. They occur in rocks which are well down in the
Westphallan stage (Zone A) and are therefore only a little younger
than the oldest insects known (Namurian). In 1957, Dr. M. J.
Copeland of the Canada Department of Mines and Technical Surveys
published an account of the arthropod fauna of the Upper Carboniferous
rocks of these provinces and included descriptions of two species
of the genus Brodioptera, which he placed in the Order Megasecoptera.
Since Dr. Copeland′s descriptions and illustrations are inadequate
for our present needs of interpreting the relationships of these
insects, I have found it necessary to make a study of this material. I
am indebted to Dr. Copeland for arranging to have the type specimens
loaned to me for this purpose.

One of the species which Copeland placed in Brodioptera is a member
of the Order Megascoptera, as thought by him, although its
affinities within the group are different from those which he assumed;
the other species described in Brodiorptera is not a megasecopteron at
all but very clearly a member of the Order Palaeodictyoptera.
A New Family of Wasps
Authors: Evans Howard E.
Published: April 2008

The classification of the aculeate Hymenoptera is considerably complicated
by the existence of a number of small families of doubtful
relationships, families such as the Plumariidae, Rhopalosomatidae,
Sierolomorphidae, Sclerogibbidae, and Loboscelidiidae. To add still
another family to this list is a dubious distinction, and to base such a
family on twelve specimens may be considered a dubious procedure.
Nevertheless these twelve specirnens present such an unusual array of
structural features that they can scarcely be ignored. Although some
of these features are clearly specializations, others are so very generalized,
for Aculeata, that there can be little question that this family
is a relict of a very ancient stock of wasps. These wasps have the
habitus of certain Scolioidea, and probably the family should be
placed in that superfamily. However, because of the 13‐segmented
antennae in the female and the lack of closed cells in the hind wings,
the family will fall in the Bethyloidea in most classifications. The
name of the type genus, Scolebythus, is meant to imply a sharing of
certain characteristics of both these superfamilies of primitive Aculeata
(scolbeing a prefix derived from Scolia, lebythus an anagram of
Bethylus). Further discussion of the relationships of the family is
deferred until after the descriptive material. In the description of the
family, I have numbered the more significant characters so that these
can be referred to more readily later on.