bluuebunny/crossref_metadata_2025 huggingface dataset:
Utility Perspective of Selecting Air Filter for Simple-Cycle, Heavy-Duty Combustion Turbines
Authors: Lyons J. W. , Morrison A.
Published: April 2008

The combustion turbines evaluated for this study range in size (nominal) from 80 MW to 100 MW and operate at a compression ratio between 10 and 14. Under these conditions the compressor ingests about 500,000 to 725,000 cubic feet of air per minute for its rated output. With this volume of air, even low concentrations of contaminants can result in a significant total amount of contaminants entering the unit, which may cause compressor erosion, fouling, and foreign object damage in the compressor section and cooling air passage blockage, locking of turbine blade roots, and hot corrosion or sulfidation in the turbine section. Adequate protection against the above-mentioned degradation or damage due to poor air quality may be obtained by using properly designed air filters. An inadequate filter system or total lack of one results in a reduction in power and efficiency over the life of the unit and may significantly decrease the intervals between maintenance and thereby increase the cost of maintenance. Consideration should be given to adding an air inlet filter when or after the combustion turbine without air filter is overhauled to reduce future maintenance costs. This study investigates the need for an inlet air filtration system for simple-cycle, heavy-duty combustion turbines from a cost/benefit and operation standpoint. Options for inlet air filters include a self-cleaning pulse type filter, a surface loading cartridge filter without pulse feature, and a three-stage depth loading type media type filter. Benefits are determined by estimates of improvements in performance and effects on the combustion turbine’s longevity and maintenance.
Performance of Gas Turbine Compressor Cleaners
Authors: Kolkman H. J.
Published: April 2008

Deposits are regularly removed from compressor blades and vanes of installed jet engines and gas turbines by compressor washing. A compressor cleaner is sprayed into the compressor while operating at reduced or normal rpm. Recently developed compressor cleaners are claimed to be ecologically sound. In addition, many new compressor cleaners contain a corrosion inhibitor. The cleaning efficiency of eight (old and new) compressor cleaners was determined by means of simulated compressor washing of compressor blades that had become fouled in service. For the situation simulated, the cleaning efficiency of new, ecologically sound cleaners turned out to be poor as compared with old compressor cleaners. The corrosion inhibition offered by those cleaners that contain a corrosion inhibitor was found to be satisfactory.
Prediction Technique for Stress and Vibration of Nonlinear Supported, Rotating Crankshafts
Authors: Priebsch H.-H. , Affenzeller J. , Gran S.
Published: April 2008

Design analyses of crankshafts, including bearings, are necessary for both the layout of new engines and the modification of existing engines (increased power output, etc.). To improve the existing calculation systems for crankshafts and bearings, AVL has developed a new method. This method enables the coupled vibrations in the torsional, bending, and axial directions, including gyroscopic effects, to be analyzed. For simulation of multibearing effects, the bearing models consider both the hydrodynamic oil film and the stiffness of the bearing structure. The calculation of forced vibrations is carried out using the gas and mass forces acting upon the rotating crankshaft. Comparisons of calculated to measured results demonstrate the accuracy of this calculation technique. The method can be used for passenger car, truck, and medium speed engines. In this paper examples of truck and passenger car engine applications confirm the additional possibilities for the estimation of crankshaft dynamics. Also the improvement of the results obtained from the new technique compared with those from classical calculation methods is described.
Development of a High-Output Dual-Fuel Engine
Authors: Danyluk P. R.
Published: April 2008

This paper presents the results of a new dual-fuel engine development program. The engine is the largest commercially available in terms of power output (650 hp/cyl) and features very low emissions (1 g/hp-hr NOx) and excellent fuel consumption (43 percent thermal efficiency). A two-cylinder turbocharged prototype was designed and built for the initial development. Results from testing on 18-cylinder production versions are also reported.
Engine Knock Rating of Natural Gases—Methane Number
Authors: Ryan T. W. , Callahan T. J. , King S. R.
Published: April 2008

A procedure has been developed and documented for determining the methane number of gaseous fuels. The methane number provides an indication of the knock tendency of the fuel. An experimental test matrix was designed for quantifying the effects of ethane, propane, butane, and CO2. A unique gas mixing and control system was developed to supply test gases to the engine and to control the equivalence ratio and engine operation. The results of the experiments agreed well with the limited data published in the literature. Predictive equations were developed for the methane number (MN) of gaseous fuels using the gas composition. The forms of these equations are suitable for incorporation in a computer program or a spreadsheet.
Progress on the Investigation of Coal-Water Slurry Fuel Combustion in a Medium-Speed Diesel Engine: Part 6—In-Cylinder Combustion Photography Studies
Authors: Hsu B. D. , Branyon D. P.
Published: April 2008

In the GE 7FDL single cylinder research diesel engine, in-cylinder high-speed photographic studies were conducted on coal-water slurry (CWS) fuel combustion. Distinct flames of pilot and CWS combustion were noticed. It was proven that the coal fuel burns after piston impingement and secondary atomization. Agglomerated particles will develop when combustion conditions are not favorable. Cylinder pressure data were simultaneously recorded for each film frame. Heat release data can thus be produced for each photo study. Most of the findings of earlier combustion studies on engine performances were confirmed.
Response to Comment on "Eddy/Wind Interactions Stimulate Extraordinary Mid-Ocean Plankton Blooms"
Authors: McGillicuddy Dennis J. , Ledwell James R. , Anderson Laurence A.
Published: April 2008

The alternative mechanism proposed by Mahadevan
et al
. is an unlikely explanation for our observations because their model predicts a bloom at the periphery of the eddy, whereas the observations show it located at the eddy center, and because the vertical displacements caused by the nonlinear Ekman effect are too small to lead to an extraordinary biological response in this eddy.
Comment on "Eddy/Wind Interactions Stimulate Extraordinary Mid-Ocean Plankton Blooms"
Authors: Mahadevan Amala , Thomas Leif N. , Tandon Amit
Published: April 2008

McGillicuddy
et al
. (Reports, 18 May 2007, p. 1021) proposed that eddy/wind interactions enhance the vertical nutrient flux in mode-water eddies, thus feeding large mid-ocean plankton blooms. We argue that the supply of nutrients to ocean eddies is most likely affected by submesoscale processes that act along the periphery of eddies and can induce vertical velocities several times larger than those due to eddy/wind interactions.
Genomic Plasticity and the Diversity of Polyploid Plants
Authors: Leitch A. R. , Leitch I. J.
Published: April 2008

Polyploidy, a change whereby the entire chromosome set is multiplied, arises through mitotic or meiotic misdivisions and frequently involves unreduced gametes and interspecific hybridization. The success of newly formed angiosperm polyploids is partly attributable to their highly plastic genome structure, as manifested by tolerance to changing chromosome numbers (aneuploidy and polyploidy), genome size, (retro)transposable element mobility, insertions, deletions, and epigenome restructuring. The ability to withstand large-scale changes, frequently within one or a few generations, is associated with a restructuring of the transcriptome, metabolome, and proteome and can result in an altered phenotype and ecology. Thus, polyploid-induced changes can generate individuals that are able to exploit new niches or to outcompete progenitor species. This process has been a major driving force behind the divergence of the angiosperms and their biodiversity.
Selection on Major Components of Angiosperm Genomes
Authors: Gaut Brandon S. , Ross-Ibarra Jeffrey
Published: April 2008

Angiosperms are a relatively recent evolutionary innovation, but their genome sizes have diversified remarkably since their origin, at a rate beyond that of most other taxa. Genome size is often correlated with plant growth and ecology, and extremely large genomes may be limited both ecologically and evolutionarily. Yet the relationship between genome size and natural selection remains poorly understood. The manifold cellular and physiological effects of large genomes may be a function of selection on the major components that contribute to genome size, such as transposable elements and gene duplication. To understand the nature of selection on these genomic components, both population-genetic and comparative approaches are needed.
Genome-Enabled Approaches Shed New Light on Plant Metabolism
Authors: DellaPenna Dean , Last Robert L.
Published: April 2008

Plant metabolism research has experienced a second golden age resulting from synergies between genome-enabled technologies and classical biochemistry. The rapid rate at which genomics data are being accumulated creates increased needs for robust metabolomic technologies and fast and accurate methods for identifying the activities of enzymes.
Synchronizing Rock Clocks of Earth History
Authors: Kuiper K. F. , Deino A. , Hilgen F. J. , Krijgsman W. , Renne P. R. , Wijbrans J. R.
Published: April 2008

Calibration of the geological time scale is achieved by independent radioisotopic and astronomical dating, but these techniques yield discrepancies of ∼1.0% or more, limiting our ability to reconstruct Earth history. To overcome this fundamental setback, we compared astronomical and
40
Ar/
39
Ar ages of tephras in marine deposits in Morocco to calibrate the age of Fish Canyon sanidine, the most widely used standard in
40
Ar/
39
Ar geochronology. This calibration results in a more precise older age of 28.201 ± 0.046 million years ago (Ma) and reduces the
40
Ar/
39
Ar method's absolute uncertainty from ∼2.5 to 0.25%. In addition, this calibration provides tight constraints for the astronomical tuning of pre-Neogene successions, resulting in a mutually consistent age of ∼65.95 Ma for the Cretaceous/Tertiary boundary.
Vaccinia Virus Uses Macropinocytosis and Apoptotic Mimicry to Enter Host Cells
Authors: Mercer Jason , Helenius Ari
Published: April 2008

Viruses employ many different strategies to enter host cells. Vaccinia virus, a prototype poxvirus, enters cells in a pH-dependent fashion. Live cell imaging showed that fluorescent virus particles associated with and moved along filopodia to the cell body, where they were internalized after inducing the extrusion of large transient membrane blebs. p21-activated kinase 1 (PAK1) was activated by the virus, and the endocytic process had the general characteristics of macropinocytosis. The induction of blebs, the endocytic event, and infection were all critically dependent on the presence of exposed phosphatidylserine in the viral membrane, which suggests that vaccinia virus uses apoptotic mimicry to enter cells.
Role of
C. elegans
TAT-1 Protein in Maintaining Plasma Membrane Phosphatidylserine Asymmetry
Authors: Darland-Ransom Monica , Wang Xiaochen , Sun Chun-Ling , Mapes James , Gengyo-Ando Keiko , Mitani Shohei , Xue Ding
Published: April 2008

The asymmetrical distribution of phospholipids on the plasma membrane is critical for maintaining cell integrity and physiology and for regulating intracellular signaling and important cellular events such as clearance of apoptotic cells. How phospholipid asymmetry is established and maintained is not fully understood. We report that the
Caenorhabditis elegans
P-type adenosine triphosphatase homolog, TAT-1, is critical for maintaining cell surface asymmetry of phosphatidylserine (PS). In animals deficient in
tat-1
, PS is abnormally exposed on the cell surface, and normally living cells are randomly lost through a mechanism dependent on PSR-1, a PS-recognizing phagocyte receptor, and CED-1, which contributes to recognition and engulfment of apoptotic cells. Thus,
tat-1
appears to function in preventing appearance of PS in the outer leaflet of plasma membrane, and ectopic exposure of PS on the cell surface may result in removal of living cells by neighboring phagocytes.
Seeing Green on the Silver Screen
Authors: Stokstad Erik , Zahn Laura M. , Riddihough Guy , Jasny Barbara , Stokstad Erik , Riddihough Guy , Jasny Barbara , Zahn Laura M. , Jasny Barbara
Published: April 2008

Our reviewers discuss five films that appeared in the recent Environmental Film Festival in Washington, DC.
Pseudallescheria fusoidea
, a New Cause of Osteomyelitis
Authors: Lindsley Mark D. , Guarro Josep , Khairy Raed N. , Williams JoAnna , Iqbal Naureen , Pancholi Preeti
Published: April 2008

Osteomyelitis resulting from a mold infection often presents as a chronic and indolent disease process. Described here for the first time is a case of osteomyelitis of the foot caused by the mold
Pseudallescheria fusoidea
, which resulted from traumatic implantation after an injury sustained 3 years earlier.
Bovine Mastitis Associated with
Prototheca blaschkeae
Authors: Marques Sara , Silva Eliane , Kraft Christine , Carvalheira Júlio , Videira Arnaldo , Huss Volker A. R. , Thompson Gertrude
Published: April 2008

Bovine mastitis is an important and complex disease responsible for economic losses in the dairy industry. Biotype II strains of the green alga
Prototheca zopfii
can be involved, most often resulting in chronic mastitis of difficult treatment associated with reduced milk production. This type of infection is rare, but the number of reported cases is increasing worldwide. In order to determine the kind of species involved in mastitis by
Prototheca
in northwest Portugal, 41
Prototheca
isolates were genetically characterized. The algae are part of
Prototheca
isolates that were collected during a 6-year period, isolated from the milk of 41 dairy cows in a total of 22 herds with a history of increasing somatic cell counts, mild clinical signs of udder infection, and unsuccessful response to the usual therapy. PCR amplification of the 18S ribosomal DNA (rDNA), amplified rDNA restriction analysis, and phylogenetic analyses of the 18S rDNA sequences were performed. Thirty-seven isolates were identified as
P. zopfii
var.
hydrocarbonea
and four as
Prototheca blaschkeae
. These data suggest a high incidence of
P. zopfii
var.
hydrocarbonea
mastitis in the region and demonstrate for the first time the involvement of
P. blaschkeae
with bovine mammary gland infections.
Unusually High Prevalence of Panton-Valentine Leukocidin Genes among Methicillin-Sensitive
Staphylococcus aureus
Strains Carried in the Indonesian Population
Authors: Severin Juliëtte A. , Lestari Endang Sri , Kuntaman Kuntaman , Melles Damian C. , Pastink Martijn , Peeters Justine K. , Snijders Susan V. , Hadi Usman , Duerink D. Offra , van Belkum Alex , Verbrugh Henri A.
Published: April 2008

Few data on the molecular characteristics and epidemiology of
Staphylococcus aureus
from Indonesia are available. The purpose of the present study was to define
S. aureus
reservoirs in both the Indonesian community and hospital using a collection of 329 nasal carriage isolates obtained during a survey of 3,995 healthy individuals and patients from Java, Indonesia. Only one strain (0.3%) was identified as methicillin-resistant
S. aureus
by
mecA
gene PCR. The Panton-Valentine leukocidin (PVL) genes were detected in 35 methicillin-sensitive
S. aureus
strains (10.6%). Molecular typing by pulsed-field gel electrophoresis of the 329 isolates showed extensive genetic diversity among both PVL-positive and PVL-negative strains. In Surabaya, Indonesia, however, a cluster was identified that was strongly associated with the presence of the PVL locus (
P
< 0.0001). As determined by high-throughput amplified fragment length polymorphism, PVL-positive strains occurred throughout all major AFLP clusters (I to IV). Multilocus sequence typing of a subset of isolates showed that most PVL-positive strains belonged to sequence type (ST) 188, while most PVL-negative isolates belonged to ST45. The high prevalence of PVL-positive
S. aureus
strains in certain regions of Indonesia is of concern since these strains may cause severe infections in the community and in hospitals.
Diverse and Novel Oral Bacterial Species in Blood following Dental Procedures
Authors: Bahrani-Mougeot Farah K. , Paster Bruce J. , Coleman Shirley , Ashar Jignya , Barbuto Sara , Lockhart Peter B.
Published: April 2008

We identified oral bacterial species in blood cultures following single-tooth extraction and tooth brushing. Sequence analysis of 16S rRNA genes identified 98 different bacterial species recovered from 151 bacteremic subjects. Of interest, 48 of the isolates represented 19 novel species of
Prevotella, Fusobacterium, Streptococcus, Actinomyces, Capnocytophaga, Selenomonas
, and
Veillonella
.
Performance of Vitek 2 in Antimicrobial Susceptibility Testing of
Pseudomonas aeruginosa
Isolates with Different Mechanisms of β-Lactam Resistance
Authors: Mazzariol Annarita , Aldegheri Marco , Ligozzi Marco , Lo Cascio Giuliana , Koncan Raffaella , Fontana Roberta
Published: April 2008

A total of 78 isolates of
Pseudomonas aeruginosa
grouped according to the phenotype for ceftazidime and imipenem susceptibility/resistance were used to assess the accuracy of the Vitek 2 system in antimicrobial susceptibility testing. Comparisons were made with a MIC gradient test for piperacillin-tazobactam, ceftazidime, aztreonam, imipenem, meropenem, gentamicin, and ciprofloxacin. For the total of 546 isolate-antimicrobial combinations tested, the category agreement was 83.6%, with 2.0, 1.6, and 12.8% very major, major, and minor errors, respectively. Vitek 2 accuracy was influenced differently by the mechanism responsible for resistance, and interpretation of the results in relation to phenotype could improve the performance of the system.
A Glycoconjugate Antigen Based on the Recognition Motif of a Broadly Neutralizing Human Immunodeficiency Virus Antibody, 2G12, Is Immunogenic but Elicits Antibodies Unable To Bind to the Self Glycans of gp120
Authors: Astronomo Rena D. , Lee Hing-Ken , Scanlan Christopher N. , Pantophlet Ralph , Huang Cheng-Yuan , Wilson Ian A. , Blixt Ola , Dwek Raymond A. , Wong Chi-Huey , Burton Dennis R.
Published: April 2008

The glycan shield of human immunodeficiency virus type 1 (HIV-1) gp120 contributes to viral evasion from humoral immune responses. However, the shield is recognized by the HIV-1 broadly neutralizing antibody (Ab), 2G12, at a relatively conserved cluster of oligomannose glycans. The discovery of 2G12 raises the possibility that a carbohydrate immunogen may be developed that could elicit 2G12-like neutralizing Abs and contribute to an AIDS vaccine. We have previously dissected the fine specificity of 2G12 and reported that the synthetic tetramannoside (Man
4
) that corresponds to the D1 arm of Man
9
GlcNAc
2
inhibits 2G12 binding to gp120 as efficiently as Man
9
GlcNAc
2
itself, indicating the potential use of Man
4
as a building block for creating immunogens. Here, we describe the development of neoglycoconjugates displaying variable copy numbers of Man
4
on bovine serum albumin (BSA) molecules by conjugation to Lys residues. The increased valency enhances the apparent affinity of 2G12 for Man
4
up to a limit which is achieved at ∼10 copies per BSA molecule, beyond which no further enhancement is observed. Immunization of rabbits with BSA-(Man
4
)
14
elicits significant serum Ab titers to Man
4
. However, these Abs are unable to bind gp120. Further analysis reveals that the elicited Abs bind a variety of unbranched and, to a lesser extent, branched Man
9
derivatives but not natural
N
-linked oligomannose containing the chitobiose core. These results suggest that Abs can be readily elicited against the D1 arm; however, potential differences in the presentation of Man
4
on neoglycoconjugates, compared to glycoproteins, poses challenges for eliciting anti-mannose Abs capable of cross-reacting with gp120 and HIV-1.
An Engineered
Saccharomyces cerevisiae
Strain Binds the Broadly Neutralizing Human Immunodeficiency Virus Type 1 Antibody 2G12 and Elicits Mannose-Specific gp120-Binding Antibodies
Authors: Luallen Robert J. , Lin Jianqiao , Fu Hu , Cai Karen K. , Agrawal Caroline , Mboudjeka Innocent , Lee Fang-Hua , Montefiori David , Smith David F. , Doms Robert W. , Geng Yu
Published: April 2008

The glycan shield of the human immunodeficiency virus type 1 (HIV-1) envelope (Env) protein serves as a barrier to antibody-mediated neutralization and plays a critical role in transmission and infection. One of the few broadly neutralizing HIV-1 antibodies, 2G12, binds to a carbohydrate epitope consisting of an array of high-mannose glycans exposed on the surface of the gp120 subunit of the Env protein. To produce proteins with exclusively high-mannose carbohydrates, we generated a mutant strain of
Saccharomyces cerevisiae
by deleting three genes in the N-glycosylation pathway,
Och1, Mnn1
, and
Mnn4
. Glycan profiling revealed that N-glycans produced by this mutant were almost exclusively Man
8
GlcNAc
2
, and four endogenous glycoproteins that were efficiently recognized by the 2G12 antibody were identified. These yeast proteins, like HIV-1 gp120, contain a large number and high density of N-linked glycans, with glycosidase digestion abrogating 2G12 cross-reactivity. Immunization of rabbits with whole Δ
och1
Δ
mnn1
Δ
mnn4
yeast cells produced sera that recognized a broad range of HIV-1 and simian immunodeficiency virus (SIV) Env glycoproteins, despite no HIV/SIV-related proteins being used in the immunization procedure. Analyses of one of these sera on a glycan array showed strong binding to glycans with terminal Manα1,2Man residues, and binding to gp120 was abrogated by glycosidase removal of high-mannose glycans and terminal Manα1,2Man residues, similar to 2G12. Since
S. cerevisiae
is genetically pliable and can be grown easily and inexpensively, it will be possible to produce new immunogens that recapitulate the 2G12 epitope and may make the glycan shield of HIV Env a practical target for vaccine development.
Transcriptional Changes Induced by Bovine Papillomavirus Type 1 in Equine Fibroblasts
Authors: Yuan Z. Q. , Nicolson L. , Marchetti B. , Gault E. A. , Campo M. S. , Nasir L.
Published: April 2008

Bovine papillomavirus type 1 (BPV-1) and, less commonly, BPV-2 are associated with the pathogenesis of common equine skin tumors termed sarcoids. In an attempt to understand the mechanisms by which BPV-1 induces sarcoids, we used gene expression profiling as a screening tool to identify candidate genes implicated in disease pathogenesis. Gene expression profiles of equine fibroblasts transformed by BPV-1 experimentally or from explanted tumors were compared with those of control equine fibroblasts to identify genes associated with expression of BPV-1. Analysis of the microarray data identified 81 probe sets that were significantly (
P
< 0.01) differentially expressed between the BPV-1-transformed and control cell lines. Expression of several deregulated genes, including
MMP-1, CXCL5, FRA-1, NKG7, TLR4
, and the gene encoding the major histocompatibility complex class I (MHC-I) protein, was confirmed using other BPV-1-transformed cell lines. Furthermore, expression of these genes was examined using a panel of 10 sarcoids. Increased expression of
MMP-1, CXCL5, FRA-1
, and
NKG7
was detected in a subset of tumors, and
TLR4
and
MHC I
showed robust down-regulation in all tumors. Deregulated expression was confirmed at the protein level for MMP-1 and MHC-I. The present report identifies genes modulated by BPV-1 transformation and will help identify the molecular mechanisms involved in disease pathogenesis.
Nuclear Marginalization of Host Cell Chromatin Associated with Expansion of Two Discrete Virus-Induced Subnuclear Compartments during Baculovirus Infection
Authors: Nagamine Toshihiro , Kawasaki Yu , Abe Atsushi , Matsumoto Shogo
Published: April 2008

Chromatin structure is strictly regulated during the cell cycle. DNA viruses occasionally disturb the spatial organization of the host cell chromatin due to formation of the viral DNA replication compartment. To examine chromatin behavior in baculovirus-infected cells, we constructed recombinant plasmids expressing fluorescent protein-tagged histone H4 molecules and visualized the intracellular localization of chromatin by their transient expression in live infected cells. Similar to other DNA viruses, the baculovirus
Bombyx mori
nucleopolyhedrovirus induced marginal relocation of chromatin within the nuclei of BmN cells, simultaneously with expansion of the viral DNA replication compartment, the virogenic stroma (VS). In the late stage of infection, however, the peristromal region (PR), another virus-induced subnuclear compartment, was also excluded from the chromatin-localizing area. Provided that late-gene products such as PR proteins (e.g., envelope proteins of the occlusion-derived virus) were expressed, blockage of viral DNA synthesis failed to inhibit chromatin relocation, despite abrogation of VS expansion. Instead, chromatin became marginalized concomitantly with PR expansion, suggesting that the PR contributes directly to chromatin replacement. In addition, chromatin was excluded from relatively large subnuclear structures that were induced in uninfected cells by cotransfection with four baculovirus genes,
ie1
,
lef3
,
p143
, and
hr
. Omission of any of the four genes, however, failed to result in formation of the large structures or chromatin exclusion. This correlation between compartmentalization and chromatin exclusion suggests the possibility that a chromatin-exclusive property of viral molecules, at least in part, supports nuclear compartmentalization of virus-infected cells.
Generation of Recombinant Rotavirus with an Antigenic Mosaic of Cross-Reactive Neutralization Epitopes on VP4
Authors: Komoto Satoshi , Kugita Masanori , Sasaki Jun , Taniguchi Koki
Published: April 2008

Recombinant rotavirus (RV) with cDNA-derived chimeric VP4 was generated using recently developed reverse genetics for RV. The rescued virus, KU//rVP4(SA11)-II(DS-1), contains SA11 (simian RV strain, G3P[2])-based VP4, in which a cross-reactive neutralization epitope (amino acids 381 to 401) on VP5* is replaced by the corresponding sequence of a different P-type DS-1 (human RV strain, G2P[4]). Serological analyses with a panel of anti-VP4- and -VP7-neutralizing monoclonal antibodies revealed that the rescued virus carries a novel antigenic mosaic of cross-reactive neutralization epitopes on its VP4 surface. This is the first report of the generation of a recombinant RV with artificial amino acid substitutions.
Autocrine and Paracrine Promotion of Cell Survival and Virus Replication by Human Herpesvirus 8 Chemokines
Authors: Choi Young Bong , Nicholas John
Published: April 2008

Human herpesvirus 8 (HHV-8), which is associated with the endothelial tumor Kaposi's sarcoma, encodes three CC/β-chemokines. These are expressed early during productive (lytic) infection and are believed to be involved in immune evasion, in addition to viral pathogenesis via induction of angiogenic cytokines. Here we report that two of the HHV-8 chemokines, CCR8 agonists vCCL-1 and vCCL-2, have direct effects on endothelial survival and virus replication. The v-chemokines stimulated virus replication when added to infected cultures exogenously, and CCR8 knockdown absent v-chemokine supplementation inhibited virus production, indicative of autocrine effects of endogenously produced vCCLs. This was verified and proreplication functions of each chemokine were demonstrated via shRNA-mediated vCCL depletion. The v-chemokines inhibited expression of lytic cycle-induced proapoptotic protein Bim, RNA interference-mediated suppression of which mimicked v-chemokine proreplication functions. Our data show for the first time that the v-chemokines have direct effects on virus biology, independently of their postulated immune evasion functions, and suggest that in vivo the v-chemokines might play direct roles in Kaposi's sarcomagenesis via paracrine prosurvival signaling.
Habitat Switch and Niche Overlap in Coregonid Fishes: Effects of Zooplankton Abundance
Authors: Næsje T. F. , Jonsson B. , Sandlund O. T. , Kjellberg G.
Published: April 2008

Vendace (Coregortus albula) in Lake Mjøsa lived in the pelagic zone and gillnet catches were correlated with water temperature (r2 = 0.457, p < 0.005). Whitefish (Coregonus lavaretus) exploited both epibenthic and pelagic areas. Whitefish with body lengths between 25 and 35 cm moved from the epibenthic to pelagic zone during summer; other length groups remained in epibenthic habitats. The pelagic fish returned to epibenthic areas in the autumn. Cladocerans were important food items for both fish species in the pelagic zone. The large copepod Limnocalanus macrurus was eaten only by vendace whereas surface insects were more important prey for whitefish. This suggests that vendace is the more specialized zooplanktivore. The pelagic gillnet catch of whitefish and the pelagic habitat overlap between whitefish and vendace increased with increasing zooplankton densities at depths between 0 and 50 m (r2 = 0.609 and 0.494, respectively, p < 0.01). During spring and autumn we observed a time lag between the change in zooplankton abundance and habitat switches of whitefish. The fish moved to the more profitable habitat several days after food availability had changed, indicating an element of learning in choice of habitat.
Hydrocarbon and Metal Contents in a Sediment Core from Halifax Harbour: A Chronology of Contamination
Authors: Gearing Juanita N. , Buckley Dale E. , Smith John N.
Published: April 2008

In a dated core from the Northwest Arm of Halifax Harbour, pollutant hydrocarbon concentrations have increase 100-fold since about 1900 (15–20 cm depth). Aliphatic contaminants characteristic of sewage and urban runoff have had a steady, exponential growth overtime, while aromatic hydrocarbon combustion products are currently declining slightly from a subsurface maximum around 1950 (5–10 cm depth). Present levels of these compounds are among the highest reported in the literature. Similarly, contamination of sediments by the metals Cu, Zn, Pb, and Hg has also increased from 1890 to 1970, with maximum levels among the highest reported from other urban and industrialized coastal marine areas in the world. In contrast, the concentrations of natural product hydrocarbons such as squalene and perylene have not changed significantly in this century.
Size Scaling of Whole-Body Maximal Enzyme Activities in Aquatic Crustaceans
Authors: Berges Jonn A. , Ballantyne James S.
Published: April 2008

The relationships between body size and maximal activities of eight enzymes were measured in whole-body homogenates of the crustaceans Macrobrachium rosenbergii, Artemia franciscana, and Daphnia magna. Interspecifically and intraspecificaily, enzyme activities per animal (Y) scale with protein weight (W) according to the allometric relationship Y = aWb. Scaling exponents (b) varied with the enzyme examined and were usually different from 0.75. For enzymes such as citrate synthase, intraspecific and interspecific exponents were similar, but for enzymes associated with pathways other than aerobic metabolism, significant differences were found between species. For anaerobic enzymes such as lactate dehydrogenase, these differences may relate to interspecific differences in life history and ecology. For anabolic enzymes such as glucose-6-phosphate dehydrogenase and nucleoside diphosphate kinase, differences may relate to differences in growth rates between species.
Evidence for Attacks by the Bathypelagic Fish Anotopterus pharao (Myctophiformes) on Pacific Salmon (Oncorhynchus spp.)
Authors: Welch D. W. , Margolis L. , Henderson M. A. , McKinnell S.
Published: April 2008

Adult Pacific salmon (Oncorhynchus spp.) returning from offshore waters to spawn frequently bear a wide range of wounds and scars. One of the most common wounds is a single slash mark on the posterior third of one side of the body, running posteroventrally from near the dorsal fin at a roughly 45° angle. The evidence is reviewed for the occurrence of slash-marked salmon around the Pacific Rim over the past 30 yr. A jaw fragment removed from the wound of a slash-marked sockeye salmon (O. nerka) and identified as belonging to a daggertooth (Anotopterus pharao: order Myctophiformes), a highly modified bathypelagic fish, provides the first direct evidence for the cause of these wounds. Given the frequency of slash-marked adult salmon in coastal fisheries, A. pharao may be a significant cause of mortality in Pacific salmon that has previously gone unrecognized.
Potential Rates of Increase of a Harbour Porpoise (Phocoena phocoena) Population Subjected to Incidental Mortality in Commercial Fisheries
Authors: Woodley Thomas H. , Read Andrew J.
Published: April 2008

We estimated the potential intrinsic rate of increase (r) of the harbour porpoise (Phocoena phocoena) population in the Bay of Fundy and Gulf of Maine using empirical data on reproductive rates (mx) and several hypothetical survival (Ix) schedules. Schedules of Ix, to maximum ages of 12 and 15 yr, were calculated from two potential natural mortality (nx) schedules combined with several schedules of incidental mortality (hx) estimates. The most realistic results were obtained when nx of non-calves were calculated from Caugley's (1966. Ecology 47: 906–918) smoothed age-frequency equation for Himalayan thar (Hemitragus jemlahicus) and applied in conjunction with a range of calf natural mortality estimates, this model indicates that harbour porpoises have a limited capacity for population increase, and populations are unlikely to sustain even moderate levels of incidental mortality (4% of the population per year). Extending the maximum age used in the models from 12 to 15 yr does little to increase estimates of r for the harbour porpoise population, and hence their susceptibility to incidental mortality.
Changes in Plasma T4 and T3 Levels during Reconditioning and Rematuration in Male and Female Wild Atlantic Salmon (Salmo salar) Kelts Held in Freshwater under Two Photoperiod Regimes
Authors: Eales J. G. , Cyr D. G. , Finnson K. , Johnston C. E.
Published: April 2008

The plasma level of L-thyroxine (T4) of wild reconditioned Atlantic salmon (Salmo salar) kelts held in freshwater at seasonal temperatures on a natural simulated photoperiod showed a robust seasonal profile with a marked peak in early spring followed by low levels throughout the summer. Plasma T4 was low in kelts that did not recondition and was uninfluenced by gender, eventual reproductive state, or imposition of a 6-mo compressed photocycle. The plasma 3,5,3′-triiodo-L-thyronine (T3) level also rose in spring in both males and females. In males and nonreproducing females, plasma T3 remained high during the growth phase in summer and decreased in fall and winter. Plasma T3 was very low in nonfeeding fish and showed some influence by the 6-mo compressed photocycle. Plasma T3 was particularly low in females at the time of vitellogenesis when 17β-estradiol was high. It is concluded that in reconditioned Atlantic salmon kelts, levels of plasma T4 and T3 appear to be controlled independently and that plasma T3 is more susceptible than T4 to vitellogenic state and other factors relating to metabolic demands.
Biological and Environmental Control of Mercury Accumulation by Fish in Lakes and Reservoirs of Northern Manitoba, Canada
Authors: Jackson Togwell A.
Published: April 2008

Enlargement of northern Manitoba lakes to form hydroelectric reservoirs caused a rise in the Hg content of walleye (Stizostedion vitreum), northern pike (Esox lucius), lake whitefish (Coregonus clupeaformis), yellow perch (Perca flavescens), and spottail shiner (Notropis hudsonius) owing to stimulation of Hg methylating microbes by submerged terrestrial organic matter. However, an increase in the supply of organic substrates beyond a critical amount mitigated this effect, apparently by promoting Hg demethylation and production of Hg-binding agents such as sulfides. Fish species, even at the same trophic level, differed markedly in their Hg content, Hg – fork length relationships, and regional and temporal variations in Hg content; this is ascribed to differences in habitat preference, metabolic rate, age, growth rate, size, biomass, diet, and excretory pathways, and hence different responses and degrees of exposure to spatially varying conditions influencing Hg speciation and availability. Whitefish had an anomalously weak tendency to accumulate CH3Hg+ and a high ratio of liver CH3Hg+ to muscle CH3Hg+, suggesting a special mechanism of excretion. Only walleye Hg correlated significantly with CH3Hg+ production in offshore mud, indicating the value of walleye for whole-lake Hg bioassays and the validity and utility of the methods used to quantify CH3Hg+ production.
Characteristics and Function of Large Woody Debris in Streams Draining Old-Growth, Clear-Cut, and Second-Growth Forests in Southwestern Washington
Authors: Bilby Robert E. , Ward James W.
Published: April 2008

Amount of large woody debris (LWD) surveyed in 70 stream reaches flowing through old-growth, clear-cut, and second-growth forests decreased with increasing stream size for all stand types but was greatest at old-growth sites. Average piece volume was larger at old-growth sites than at other stand types in streams >10 m wide, but no differences were seen in smaller streams. Scour pools accounted for 90% of the wood-associated pools at second-growth and clear-cut sites but only 50% at old-growth sites, which contained more pools than other stand types, particularly for larger streams. Pool size was similar for all stand types in smaller streams, but averaged 10 m2 in streams >10 m wide at old-growth sites and 4 m2 for other stand types. Pool size was similar for all stand types in smaller streams. Sediment and fine organic matter retained by woody debris decreased with increasing stream size for ail stand types, but old-growth sites contained greater amounts of both materials than other stand types. The frequency of pool formation, the type of pool formed, and sediment accumulation were influenced by the amount of fine debris associated with LWD. Changes in LWD amount, characteristics, and function occurred very rapidly following removal of streamside vegetation.
Fire history and age structure in red fir forests of Sequoia National Park, California
Authors: Pitcher Donald C.
Published: April 2008

The relationship between historical fires and age structure was examined on three plots in red fir (Abiesmagnifica var. shastensis Lemm.) forests within Sequoia National Park, California, U.S.A. All trees greater than 0.1 m in height were mapped and aged. Fire history was determined from 16 fire-scar sections. Red fir trees are more shade tolerant, longer lived, larger, and slower growing than western white pine (Pinusmonticola Dougl.) on the plots. No fires have occurred since 1886, but prior to that time the average fire-free interval was 65 years. Most of the trees on two of the plots originated after fires, but on the third plot red fir regeneration was delayed for at least 60 years following the last fire. Structural differences between the plots were linked to variations in fire behavior. The decrease in fire frequencies in this century may have led to a decrease in red fir establishment. Excluding the most recent period, the forest age structure is in something of a steady state that approximates a negative exponential age-class distribution.
Analyse qualitative des équations différentielles d'un modèle de croissance pour l'érablière à sucre
Authors: Ung Chun-Huor , Bertrand François
Published: April 2008

This paper describes a growth model based on the Weibull function. An estimation of the model parameters is made from data of 89 permanent sample plots provided by the Quebec Department of Energy and Resources. Sugar maple represents more than 75% of the total basal area in each sample plot. Qualitative analyses is used to study completely the mathematical behavior of the model.
Variation in damage among Pinuscontorta provenances caused by the needle cast fungus Lophodermellaconcolor
Authors: Hunt R. S. , Ying C. C. , Ashbee D.
Published: April 2008

Fifty-three family-structured provenances of lodgepole pine (Pinuscontorta var. latifolia) growing at a single test site near Prince George, British Columbia, were rated visually by two different methods for needle casting caused by Lophodermellaconcolor in 1982 and 1984. Analysis of variance indicated little variation due to families and much due to provenance. There were consistent year-to-year trends among the provenances and the two rating methods correlated by 0.9. This variation was significantly correlated with longitude and elevation but only slightly with latitude. Damage among the 41 provenances that are adapted to the continental climate of interior British Columbia increased with elevation.
Impact of red squirrel feeding damage on spaced stands of lodgepole pine in the Cariboo Region of British Columbia
Authors: Sullivan Thomas P. , Vyse Alan
Published: April 2008

This study measured the impact of red squirrel (Tamiasciurushudsonicus Erxleben) feeding damage on spaced stands of lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) in the Cariboo Forest Region of British Columbia. A limited regional assessment of animal damage in spaced stands indicated that squirrels were the most important small mammal damage agents and that lodgepole pine was the only tree species susceptible to squirrel feeding (bark and vascular tissues) injuries. Intensive assessment of damage in two stands showed that squirrel attack was significantly greater among large- (>60 mm dbh) than small-diameter stems. Significantly more spaced than control (unspaced) crop trees were attacked. There was a general decline in the proportion of trees wounded from 1980 to 1985. Some damaged trees grew faster in diameter than undamaged trees of the same size. However, at one study area, damaged trees showed faster radial growth than undamaged trees before and after squirrel attack. Squirrels appear to prefer feeding on vigorous stems and the lost growth of these trees may be substantial. Height growth of damaged trees was significantly reduced in one stand in the years following squirrel damage. Some limit to a tree's capacity to sustain damage, beyond which mortality is inevitable, seems likely. Impact of damage to spaced stands may be minimized by delaying spacing in susceptible areas or by increasing the prescribed number of stems remaining after spacing to compensate for expected mortality and severe damage.
Tree-ring studies on conifers along ecological gradients and the potential of single-year analyses
Authors: Kienast Felix , Schweingruber Fritz Hans , Bräker Otto Ulrich , Schär Ernst
Published: April 2008

Cores from conifers growing in four different climatic regions were analyzed using radiodensitometric methods. All the sites are located along altitudinal gradients between the subalpine timberline and low elevations, in some regions the arid tree line. At each of the elevation levels considered, the soil conditions range from as shallow and dry as possible to deep and moist. Various dendroecological methods were applied to determine the relationships between tree-ring growth, climatic conditions, site elevation, and site characteristics. The dominant mode of linear response between ring growth and the monthly temperature and precipitation variables was identified using response functions. A new graphical method permitted a year for year description of the complex and often nonlinear responses of tree-ring growth to the limiting factors. This is a departure from different statistical approaches that measure the most dominant relationships for a population of many years. The described single-year method is suited to analyze time-dependent growth phenomena. Typical cases of single-year responses are illustrated and the dynamics of the overlapping environmental influences are discussed. The broad spectrum of sites was used to identify ring parameters and site types most suitable for reconstructions of temperature or precipitation records.
Site and seed source influence jack pine yields in the Lake States
Authors: Strong Terry F. , Grigal David F.
Published: April 2008

Total aboveground biomass (TAB) at age 30 years was estimated for six seed sources of jack pine (Pinusbanksiana Lamb.) at eight sites in the Lake States. Initial tree spacing was 1.5 × 1.5 m. Mean TAB ranged from 70 to 122 Mg/ha among seed sources and from 56 to 130 Mg/ha among sites. A significant interaction was found between seed source and site. Environmental characteristics of each site were related to TAB. For four seed sources, TAB was positively related to total available soil water summed to 2 m. The TABs of the two better-producing seed sources were not as strongly related to available water, suggesting more efficient water use by these sources. Total aboveground biomass was negatively related to drought and evapotranspiration. Foliar micronutrient and macronutrient concentrations differed among sites and macronutrient concentrations differed among seed sources. No strong relations were found between foliar nutrient concentrations and TAB, indicating that nutrients are less limiting than water to jack pine growth. Sets of site variables that explained the variation in TAB by multiple regression were dissimilar among seed sources, suggesting that each seed source adapts to the environment differently. Selecting seed sources that are better adapted to water use can increase yields, especially on dry sites.
Decomposition of woody debris in a regenerating, clear-cut forest in the Southern Appalachians
Authors: Mattson Kim G. , Swank Wayne T. , Waide Jack B.
Published: April 2008

Mass losses were estimated for coarse (>5 cm) and fine (≤5 cm) woody debris (CWD and FWD, respectively) during the first 7 years following clear-cutting of a mixed hardwood forest at the Coweeta Hydrologie Laboratory in the Southern Appalachians of North Carolina. Estimates were based on (i) precut forest biomass, (ii) volume and density of CWD and mass of FWD at year 1, and (iii) wood density changes of CWD by year 6 and mass changes of FWD by year 7. Mass estimates of CWD at years 0, 1, and 6 were 91.2, 74.8, and 53.0 Mg/ha, respectively. Mass estimates of FWD at years 0, 1, and 7 were 30.3, 21.3, and 7.8 Mg/ha, respectively. Decay constants (k) for mass losses were relatively high compared with other studies of wood decomposition, 0.083 and 0.185 year−1 for CWD and FWD, respectively, and 0.108 year−1 for total (CWD + FWD) debris. Mass loss of CWD occurred largely through wood density decreases and bark fragmentation. CO2−efflux estimates accounted for over 90% of the CWD density loss and for two-thirds (40.4 Mg/ha) of the total debris mass loss. The remaining mass loss of total debris (20.3 Mg/ha) is a source of large, organic matter inputs to the forest floor via solution fluxes and fragmentation of CWD bark and FWD. The large variation in wood-density loss among logs was examined statistically as a function of various decay factors. Density loss varied by more than 10-fold among tree species. Density loss rates were 40% higher in logs on the ground versus those off the ground, 100% higher in logs with observable fungi versus those without fungi, and 40% higher in logs that occurred in plots with south and east aspects versus those in plots with west aspects.