bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Protective Antigens Expressed by
Trypanosoma cruzi
Amastigotes Provide Immunity to Mice Highly Susceptible to Chagas' Disease
Authors: Silveira Eduardo L. V. , Claser Carla , Haolla Filipe A. B. , Zanella Luiz G. , Rodrigues Mauricio M.
Published: June 2008

Earlier studies have demonstrated in A/Sn mice highly susceptible to Chagas' disease protective immunity against lethal
Trypanosoma cruzi
infection elicited by vaccination with an open reading frame (ORF) expressed by amastigotes. In our experiments, we used this mouse model to search for other amastigote-expressed ORFs with a similar property. Fourteen ORFs previously determined to be expressed in this developmental stage were individually inserted into a eukaryotic expression vector containing a nucleotide sequence that encoded a mammalian secretory signal peptide. Immunization with 13 of the 14 ORFs induced specific antibodies which recognized the amastigotes. Three of those immune sera also reacted with trypomastigotes and epimastigotes. After a lethal challenge with Y strain trypomastigotes, the vast majority of plasmid-injected mice succumbed to infection. In some cases, a significant delay in mortality was observed. Only two of these ORFs provided protective immunity against the otherwise lethal infection caused by trypomastigotes of the Y or Colombia strain. These ORFs encode members of the
trans
-sialidase family of surface antigens related to the previously described protective antigen amastigote surface protein 2 (ASP-2). Nevertheless, at the level of antibody recognition, no cross-reactivity was observed between the ORFs and the previously described ASP-2 from the Y strain. In immunofluorescence analyses, we observed the presence of epitopes related to both proteins expressed by amastigotes of seven different strains. In conclusion, our approach allowed us to successfully identify two novel protective ORFs which we consider interesting for future studies on the immune response to Chagas' disease.
Quantitative Survival of Aerobic and Anaerobic Microorganisms in Port-A-Cul and Copan Transport Systems
Authors: Stoner Kevin A. , Rabe Lorna K. , Austin Michele N. , Meyn Leslie A. , Hillier Sharon L.
Published: June 2008

Transport media should preserve the viability and stability of microorganisms in clinical specimens. In this study, the Port-A-Cul transport system and the Copan transport system without charcoal, both designed to preserve anaerobes, were evaluated. Dacron swabs were inoculated with two combinations of facultative and anaerobic organisms typically found in vaginal swab samples. Combination I contained
Candida albicans
,
Escherichia coli
,
Enterococcus
spp., group B streptococci,
Lactobacillus crispatus
, and
Staphylococcus aureus
. Combination II contained
Lactobacillus iners
,
Peptoniphilus asaccharolyticus
,
Mycoplasma hominis
,
Prevotella bivia
,
Prevotella corporis
,
Porphyromonas asaccharolytica
,
Mobiluncus curtisii
,
Peptostreptococcus anaerobius
, and
Gardnerella vaginalis
. Duplicate swabs were placed into the two transporters and held for 24, 48, 72, and 96 h at 4 and 24°C. Both transporters maintained the viability of organisms better at 4°C than at 24°C.
Prevotella bivia
and
Prevotella corporis
had a loss of viability in both transporters at both temperatures. However, at 24°C, there was a significantly greater loss of viability for
Mycoplasma hominis
,
Prevotella bivia
,
Prevotella corporis
, and
Peptoniphilus asaccharolyticus
when the organisms were stored in Copan transport medium than when they were stored in Port-A-Cul transport medium for 96 h (
P
< 0.002). Some organisms proliferated in the transport media, but when transporters were held at 24°C for 96 h, a significantly greater increase in the concentrations of group B streptococci and
Candida albicans
,
Escherichia coli
, and
Enterococcus
spp. organisms in Copan medium than in Port-A-Cul medium was observed (
P
< 0.002). At room temperature, the Port-A-Cul system is superior to the Copan system with respect to the preservation of fastidious microorganisms and the prevention of the proliferation of facultative organisms.
Characterization of Small-Colony Variants ofEnterococcus faecalisIsolated from Chickens with Amyloid Arthropathy
Authors: Petersen Andreas , Chadfield Mark S. , Christensen Jens P. , Christensen Henrik , Bisgaard Magne
Published: June 2008

In this study we report the isolation and characterization of normal-sized and small-colony variants ofEnterococcus faecalisfrom outbreaks of amyloid arthropathy in chickens. Postmortem examinations of 59 chickens revealed orange deposits in the knee joints, typical for amyloid arthropathy. Bacterial cultures from 102 joints and 43 spleens exhibited pure (n= 88) and mixed (n= 11) cultures of normal (n= 60) and pinpoint (n= 28) colonies ofE.faecalis. Pulsed-field gel electrophoresis of 62 isolates demonstrated seven different band patterns with at most two band size variations, and multilocus sequence typing demonstrated two different sequence types, sharing six out of seven alleles, suggesting a close evolutionary relationship between isolates obtained from four outbreaks. In addition, all isolates were clonally related to an amyloid arthropathy reference strain from The Netherlands, previously shown to be globally dispersed. Initial investigation of the isolated small-colony variant phenotype revealed no difference in whole-cell protein profiling between normal and pinpoint colonies. However, the pinpoint colony isolates appeared to be more virulent in an in vivo challenge model in chickens than their normal-sized-colony counterparts. In addition, pinpoint morphology and associated slow growth were expressed without reversion after in vitro and in vivo passage, suggesting a genuine altered phenotype, and in some instances normal colonies converted to pinpoint morphology postinfection. In conclusion, small-colony variants ofE. faecalisare described for the first time from veterinary clinical sources and in relation to amyloid arthropathy in chickens.
Anomalies in the Influenza Virus Genome Database: New Biology or Laboratory Errors?
Authors: Krasnitz Michael , Levine Arnold J. , Rabadan Raul
Published: June 2008

A search of the influenza virus genome database reveals anomalies associated with a nonnegligible number of submitted sequences. There are many pairs of viral segments that are very close to each other in nucleotide sequence but relatively far apart in reported time of isolation, resulting in an abnormally low evolutionary rate. Also, some sequences show clear evidence of apparent homologous recombination, a process normally assumed to be extremely rare or nonexistent in this virus. These findings may point to surprising new biology but are perhaps more readily explained by stock contamination or other errors in the sequencing laboratories.
Human Embryonic Stem Cell-Derived Oligodendrocyte Progenitor Cells Express the Serotonin Receptor and Are Susceptible to JC Virus Infection
Authors: Schaumburg C. , O'Hara B. A. , Lane T. E. , Atwood W. J.
Published: June 2008

We studied the susceptibility of human embryonic stem cell-derived oligodendrocyte progenitor cells to infection with JC virus, the causative agent of progressive multifocal leukoencephalopathy (PML). A human embryonic stem cell line, H7, was used to derive an enriched population of cells expressing the oligodendrocyte progenitor cell-specific marker NG2. These cells expressed the 5HT
2a
receptor (5HT
2a
R) for JC virus and were highly susceptible to infection. Infection was reduced by treatment with anti-5HT
2a
R antibodies and by the 5HT
2a
R antagonists ritanserin and ketanserin. This is the first demonstration that human embryonic stem cell-derived oligodendrocyte progenitor cells are susceptible to JC virus infection and indicates that cells poised to replenish mature oligodendrocytes in PML lesions may also be a target of viral infection.
STAT-1- and IRF-3-Dependent Pathways Are Not Essential for Repression of ICP0-Null Mutant Herpes Simplex Virus Type 1 in Human Fibroblasts
Authors: Everett Roger D. , Young Dan F. , Randall Rick E. , Orr Anne
Published: June 2008

Efficient herpes simplex virus type 1 (HSV-1) infection of human fibroblasts (HFs) is highly dependent on the viral immediate-early regulatory protein ICP0 unless the infection is conducted at a high multiplicity. ICP0-null mutant HSV-1 exhibits a plaque-forming defect of up to 3 orders of magnitude in HFs, whereas in many other cell types, this defect varies between 10- and 30-fold. The reasons for the high ICP0 requirement for HSV-1 infection in HFs have not been established definitively. Previous studies using other cell types suggested that ICP0-null mutant HSV-1 is hypersensitive to interferon and that this sensitivity is dependent on the cellular promyelocytic leukemia (PML) protein. To investigate the roles of two important aspects of interferon signaling in the phenotype of ICP0-null mutant HSV-1, we isolated HFs depleted of STAT-1 or interferon regulatory factor 3 (IRF-3). Surprisingly, plaque formation by the mutant virus was not improved in either cell type. We found that the sensitivity to interferon pretreatment of both ICP0-null mutant and wild-type (wt) HSV-1 was highly dependent on the multiplicity of infection. At a low multiplicity in virus yield experiments, both viruses were extremely susceptible to interferon pretreatment of HFs, but the sensitivity of the wild type but not the mutant could be overcome at higher multiplicities. We found that both wt and ICP0-null mutant HSV-1 remained sensitive to interferon in PML-depleted HFs albeit to an apparently lesser extent than in control cells. The data imply that the substantial reduction in ICP0-null HSV-1 infectivity at a low multiplicity in HFs does not occur through the activities of STAT-1- and IRF-3-dependent pathways and cannot be explained solely by enhanced sensitivity to interferon. We suggest that antiviral activities induced by interferon may be separable from and additive to those resulting from PML-related intrinsic resistance mechanisms.
Linker Histones Are Mobilized during Infection with Herpes Simplex Virus Type 1
Authors: Conn Kristen L. , Hendzel Michael J. , Schang Luis M.
Published: June 2008

Histones interact with herpes simplex virus type 1 (HSV-1) genomes and localize to replication compartments early during infections. However, HSV-1 genomes do not interact with histones in virions and are deposited in nuclear domains devoid of histones. Moreover, late viral replication compartments are also devoid of histones. The processes whereby histones come to interact with HSV-1 genomes, to be later displaced, remain unknown. However, they would involve the early movement of histones to the domains containing HSV-1 genomes and the later movement away from them. Histones unbind from chromatin, diffuse through the nucleoplasm, and rebind at different sites. Such mobility is upregulated by, for example, phosphorylation or acetylation. We evaluated whether HSV-1 infection modulates histone mobility, using fluorescence recovery after photobleaching. All somatic H1 variants were mobilized to different degrees. H1.2, the most mobilized, was mobilized at 4 h and further so at 7 h after infection, resulting in increases in its “free” pools. H1.2 was mobilized to a “basal” degree under conditions of little to no HSV-1 protein expression. This basal mobilization required nuclear native HSV-1 genomes but was independent of HSV-1 proteins and most likely due to cellular responses. Mobilization above this basal degree, and increases in H1.2 free pools, however, depended on immediate-early or early HSV-1 proteins, but not on HSV-1 genome replication or late proteins. Linker histone mobilization is a novel consequence of cell-virus interactions, which is consistent with the dynamic interactions between histones and HSV-1 genomes during lytic infection; it may also participate in the regulation of viral gene expression.
CD81 Is a Central Regulator of Cellular Events Required for Hepatitis C Virus Infection of Human Hepatocytes
Authors: Brazzoli Michela , Bianchi Alessia , Filippini Sara , Weiner Amy , Zhu Qing , Pizza Mariagrazia , Crotta Stefania
Published: June 2008

Infection with hepatitis C virus (HCV) is still a major public health problem, and the events leading to hepatocyte infection are not yet fully understood. Combining confocal microscopy with biochemical analysis and studies of infection requirements using pharmacological inhibitors and small interfering RNAs, we show here that engagement of CD81 activates the Rho GTPase family members Rac, Rho, and Cdc42 and that the block of these signaling pathways drastically reduces HCV infectivity. Activation of Rho GTPases mediates actin-dependent relocalization of the HCV E2/CD81 complex to cell-cell contact areas where CD81 comes into contact with the tight-junction proteins occludin, ZO-1, and claudin-1, which was recently described as an HCV coreceptor. Finally, we show that CD81 engagement activates the Raf/MEK/ERK signaling cascade and that this pathway affects postentry events of the virus life cycle. In conclusion, we describe a range of cellular events that are manipulated by HCV to coordinate interactions with its multiple coreceptors and to establish productive infections and find that CD81 is a central regulator of these events.
Activation of Akt through gp130 Receptor Signaling Is Required for Kaposi's Sarcoma-Associated Herpesvirus-Induced Lymphatic Reprogramming of Endothelial Cells
Authors: Morris Valerie A. , Punjabi Almira S. , Lagunoff Michael
Published: June 2008

Kaposi's sarcoma (KS) is the most common tumor of AIDS patients worldwide. KS-associated herpesvirus (KSHV) is the infectious cause of this highly vascularized skin tumor. The main cell type found within a KS lesion, the spindle cell, is latently infected with KSHV and has markers of both blood and lymphatic endothelial cells. During development, lymphatic endothelial cells differentiate from preexisting blood endothelial cells. Interestingly, KSHV infection of blood endothelial cells induces lymphatic endothelial cell differentiation. Here, we show that KSHV gene expression is necessary to maintain the expression of the lymphatic markers vascular endothelial growth factor receptor 3 (VEGFR-3) and podoplanin. KSHV infection activates many cell signaling pathways in endothelial cells and persistently activates STAT3 through the gp130 receptor, the common receptor of the interleukin 6 family of cytokines. We find that KSHV infection also activates the phosphatidylinositol 3-OH-kinase (PI3K)/Akt cell signaling pathway in latently infected endothelial cells and that gp130 receptor signaling is necessary for Akt activation. Using both pharmacological inhibitors and small interfering RNA knockdown, we show that the gp130 receptor-mediated activation of both the JAK2/STAT3 and PI3K/Akt cell signaling pathways is necessary for KSHV-induced lymphatic reprogramming of endothelial cells. The induction of the lymphatic endothelial cell-specific transcription factor Prox1 is also involved in KSHV-induced lymphatic reprogramming. The activation of gp130 receptor signaling is a novel mechanism for the differentiation of blood endothelial cells into lymphatic endothelial cells and may be relevant to the developmental or pathological differentiation of lymphatic endothelial cells as well as to KSHV pathogenesis.
Pathways of Cross-Species Transmission of Synthetically Reconstructed Zoonotic Severe Acute Respiratory Syndrome Coronavirus
Authors: Sheahan Timothy , Rockx Barry , Donaldson Eric , Corti Davide , Baric Ralph
Published: June 2008

Zoonotic severe acute respiratory syndrome coronavirus (SARS-CoV) likely evolved to infect humans by a series of transmission events between humans and animals in markets in China. Virus sequence data suggest that the palm civet served as an amplification host in which civet and human interaction fostered the evolution of the epidemic SARS Urbani strain. The prototypic civet strain of SARS-CoV, SZ16, was isolated from a palm civet but has not been successfully cultured in vitro. To propagate a chimeric recombinant SARS-CoV bearing an SZ16 spike (S) glycoprotein (icSZ16-S), we constructed cell lines expressing the civet ortholog (DBT-cACE2) of the SARS-CoV receptor (hACE2). Zoonotic SARS-CoV was completely dependent on ACE2 for entry. Urbani grew with similar kinetics in both the DBT-cACE2 and the DBT-hACE2 cells, while icSZ16-S only grew in DBT-cACE2 cells. The SZ16-S mutant viruses adapted to human airway epithelial cells and displayed enhanced affinity for hACE2 but exhibited severe growth defects in the DBT-cACE2 cells, suggesting that the evolutionary pathway that promoted efficient hACE2 interactions simultaneously abolished efficient cACE2 interactions. Structural modeling predicted two distinct biochemical interaction networks by which zoonotic receptor binding domain architecture can productively engage hACE2, but only the Urbani mutational repertoire promoted efficient usage of both hACE2 and cACE2 binding interfaces. Since dual species tropism was preserved in Urbani, it is likely that the virus evolved a high affinity for cACE2/hACE2 receptors through adaptation via repeated passages between human and civet hosts. Furthermore, zoonotic SARS-CoV was variably neutralized by antibodies that were effective against the epidemic strain, highlighting their utility for evaluating passive immunization efficacy.
Neurovirulence of Polytropic Murine Retrovirus Is Influenced by Two Separate Regions on Opposite Sides of the Envelope Protein Receptor Binding Domain
Authors: Peterson Karin E. , Pourciau Susan , Du Min , LaCasse Rachel , Pathmajeyan Melissa , Poulsen David , Agbandje-McKenna Mavis , Wehrly Kathy , Chesebro Bruce
Published: June 2008

Changes in the envelope proteins of retroviruses can alter the ability of these viruses to infect the central nervous system (CNS) and induce neurological disease. In the present study, nine envelope residues were found to influence neurovirulence of the Friend murine polytropic retrovirus Fr98. When projected on a three-dimensional model, these residues were clustered in two spatially separated groups, one in variable region B of the receptor binding site and the other on the opposite side of the envelope. Further studies indicated a role for these residues in virus replication in the CNS, although the residues did not affect viral entry.
Capsid Proteins from Human Immunodeficiency Virus Type 1 and Simian Immunodeficiency Virus SIV
mac
Can Coassemble into Mature Cores of Infectious Viruses
Authors: Chen Jianbo , Pathak Vinay K. , Peng Weiqun , Hu Wei-Shau
Published: June 2008

We have recently shown that the Gag polyproteins from human immunodeficiency virus type 1 (HIV-1) and HIV-2 can coassemble and functionally complement each other. During virion maturation, the Gag polyproteins undergo proteolytic cleavage to release mature proteins including capsid (CA), which refolds and forms the outer shell of a cone-shaped mature core. Less than one-half of the CA proteins present within the HIV-1 virion are required to form the mature core. Therefore, it is unclear whether the mature core in virions containing both HIV-1 and HIV-2 Gag consists of CA proteins from a single virus or from both viruses. To determine whether CA proteins from two different viruses can coassemble into mature cores of infectious viruses, we exploited the specificity of the tripartite motif 5α protein from the rhesus monkey (rhTRIM5α) for cores containing HIV-1 CA (hCA) but not the simian immunodeficiency virus SIV
mac
CA protein (sCA). If hCA and sCA cannot coassemble into the same core when equal amounts of sCA and hCA are coexpressed, the infectivities of such virus preparations in cells should be inhibited less than twofold by rhTRIM5α. However, if hCA and sCA can coassemble into the same core structure to form a mixed core, rhTRIM5α would be able to recognize such cores and significantly restrict virus infectivity. We examined the restriction phenotypes of viruses containing both hCA and sCA. Our results indicate that hCA and sCA can coassemble into the same mature core to produce infectious virus. To our knowledge, this is the first demonstration of functional coassembly of heterologous CA protein into the retroviral core.
Diet overlap and prey selection through metamorphosis in Irish Sea cod (Gadus morhua), haddock (Melanogrammus aeglefinus), and whiting (Merlangius merlangus)
Authors: Rowlands William Ll. , Dickey-Collas Mark , Geffen Audrey J. , Nash Richard D.M.
Published: June 2008

Copepods in the genus Calanus are usually considered to be the preferred prey of gadoid larvae in many areas; however, in the Irish Sea, the abundances of these Calanus species are low and highly variable. We use this situation to test whether Calanus species are still actively selected by gadoid larvae in Calanus -poor environments. Diets of Irish Sea cod ( Gadus morhua ), haddock ( Melanogrammus aeglefinus ), and whiting ( Merlangius merlangus ) were studied from the yolk-sac stage to the juvenile stage. Prey from stomach contents were compared with in situ abundance via an index of prey preference. As expected, all larvae selected copepod nauplii at the onset of feeding. As the larvae developed, their prey preferences changed and varied with species. Cod and whiting showed a similar transition of prey species preference, with a clear preference for Calanus species after metamorphosis, even in this area of low abundance of these Calanus species. The diet composition of haddock differed from that of cod and whiting, as nauplii remained in their diet later into development and there was little preference for individual copepod species detected. The differences in prey selectivity suggested between these gadoids may be attributed to their population variability through the known variability of their preferred prey items.
Among- and within-tributary responses of riverine fish assemblages to habitat featuresContribution of the Group for Interuniversity Research in Limnology (GRIL). We dedicate this paper to the memory of our colleague Réjean Fortin.
Authors: Reyjol Yorick , Rodríguez Marco A. , Dubuc Nathalie , Magnan Pierre , Fortin Réjean
Published: June 2008

We quantified fish abundance and environmental variables at 170 sites distributed among 11 tributaries of the Ottawa River, Quebec, Canada, to assess the relative importance of among- and within-tributary variation in riverine fish assemblages. Additionally, we determined (i) which environmental variables were most strongly associated with each type of variation and (ii) whether ecomorphological traits in fish assemblages were predictably related to environmental gradients. Partitioning of variation by means of partial ordination indicated that assemblages were less variable among (38.7% of the total variation) than within (61.3%) tributaries. Water transparency singly accounted for 33.3% of the variation among tributaries, whereas macrophyte cover and river width jointly accounted for 8.3% of the variation within tributaries. These results suggests that differences in habitat features among tributaries may account for a substantial fraction of the predictable variation in assemblage structure at the watershed scale, an aspect not emphasized in previous studies of riverine fish assemblages. Mixed regression analyses relating ecomorphological traits to environmental variables showed that the environmental variables most strongly associated with assemblage structure were significantly related to traits associated with predator avoidance or foraging efficiency.
Year-class strength and growth rates after metamorphosis of Japanese sardine (Sardinops melanostictus) in the western North Pacific Ocean during 1996–2003
Authors: Takahashi Motomitsu , Nishida Hiroshi , Yatsu Akihiko , Watanabe Yoshiro
Published: June 2008

Growth trajectories during larval to early juvenile stages in Japanese sardine ( Sardinops melanostictus ) were backcalculated based on the widths of otolith daily increments from 1996 to 2003 in the nursery grounds, Kuroshio–Oyashio transitional waters. Planktonic larvae hatched near Kuroshio have been transported northeastward from the Kuroshio waters to the transitional waters. We show that the somatic growth rates sharply increased after metamorphosis to the early juvenile stage, whereas previously, others showed that growth rate decreases during the larval stage. Otolith growth rates were more variable during the juvenile stage than the larval stage. Interannual variations in the otolith growth rate after metamorphosis explained more than 80% of variation in abundances of recruits (ca. 8–10 months old) in the Pacific coastal waters, whereas no correlation was found between the growth rate during the early larval stage and abundance. Our result was consistent with the hypothesis of growth rate-dependent recruitment success in the Kuroshio–Oyashio transitional waters.
Matching catches to quotas in a multispecies trawl fishery: targeting and avoidance behavior under individual transferable quotas
Authors: Branch Trevor A. , Hilborn Ray
Published: June 2008

Optimizing yield in multispecies fisheries is only possible when fishers have a high degree of control over the species mixture in their catches, although incentives to encourage this kind of behavior are rarely in place. One exception is the British Columbia, Canada, groundfish trawl fishery, where individual transferable quotas govern total allowable catches (TACs) for 22 species, combined with 100% observer coverage and the deduction of discard mortality from quota. Despite the number of species covered, when TACs were increased for some species and reduced for others, fishers were able to adjust the species mixture in their catches. The top 34 vessels frequented a wide range (mean 38, range 20–69) of “fishing opportunities” (repeated trawls along the same track line) containing predictable species mixtures. When TACs for rougheye ( Sebastes aleutianus ), shortraker ( Sebastes borealis ), and yelloweye rockfish ( Sebastes ruberrimus ) were sharply cut, fishers avoided fishing opportunities where these species were more abundant. More generally, their choice of fishing opportunities depended on the expected multispecies composition, although other factors were probably also important.
Annual variation in habitat-specific recruitment success: implications from an individual-based model of Lake Michigan alewife (Alosa pseudoharengus)
Authors: Höök Tomas O. , Rutherford Edward S. , Croley Thomas E. , Mason Doran M. , Madenjian Charles P.
Published: June 2008

The identification of important spawning and nursery habitats for fish stocks can aid fisheries management, but is complicated by various factors, including annual variation in recruitment success. The alewife ( Alosa pseudoharengus ) is an ecologically important species in Lake Michigan that utilizes a variety of habitats for spawning and early life growth. While productive, warm tributary mouths (connected to Lake Michigan) may contribute disproportionately more recruits (relative to their habitat volume) to the adult alewife population than cooler, less productive nearshore habitats, the extent of interannual variation in the relative contributions of recruits from these two habitat types remains unknown. We used an individual-based bioenergetics simulation model and input data on daily temperatures to estimate alewife recruitment to the adult population by these different habitat types. Simulations suggest that nearshore lake habitats typically produce the vast majority of young alewife recruits. However, tributary habitats may contribute the majority of alewife recruits during years of low recruitment. We suggest that high interannual variation in the relative importance of habitats for recruitment is a common phenomenon, which should be considered when developing habitat management plans for fish populations.
Transport and growth of larval cisco (Coregonus artedi) in the Keweenaw Current region of Lake Superior
Authors: Oyadomari Jason K. , Auer Nancy A.
Published: June 2008

Larval cisco ( Coregonus artedi ) were sampled from Lake Superior off the western coast of the Keweenaw Peninsula (Michigan, USA) to determine if the Keweenaw Current influences their distribution and growth. Bongo net tows were conducted during April–June 2000 from four transects extending from 0.1 to 17 km offshore. For most sampling dates, cisco tended to be slightly more abundant, larger, and older at inshore locations. Later-hatched larvae appeared at the western-most transects first, during which time earlier-hatched larvae disappeared from the study area. This pattern followed what would be expected if larvae were being transported eastward by the prevailing Keweenaw Current. Estimated growth rates were 84% higher for later-hatched compared with earlier-hatched larvae and 25% lower for offshore larvae from the eastern-most transects compared with elsewhere. Accordingly, surface water temperatures partly explained spatial and temporal variations in growth rate. These results indicate that cisco larvae in Lake Superior may be transported great distances from major spawning sites by longshore currents and that the temperature regime of nursery areas may largely control their growth.
A management framework for preventing the secondary spread of aquatic invasive species
Authors: Vander Zanden M. Jake , Olden Julian D.
Published: June 2008

Biological invasions continue to accelerate, and there is a need for closer integration between invasive species research and on-the-ground management. In many regions, aquatic invasive species have established isolated populations, but have not yet spread to many sites that provide suitable habitat. In the Laurentian Great Lakes region, several Great Lakes invaders such as zebra mussel ( Dreissena polymorpha ), rainbow smelt ( Osmerus mordax ), and spiny water flea ( Bythotrephes longimanus ) are currently undergoing secondary spread to the smaller inland lakes and streams. This paper describes recent advances in forecasting the secondary spread of aquatic invasive species and presents a framework for assessing vulnerability of inland waters based on explicit assessment of three distinct aspects of biological invasions: colonization, site suitability, and adverse impact. In many cases, only a fraction of lakes on the landscape are vulnerable to specific invasive species, highlighting the potential application of this type of research for improving invasive species management. Effective application to on-the-ground resource management will require that research aimed at assessing site vulnerability be translated into management tools.
Utilizing magnetic resonance imaging (MRI) to assess the effects of angling-induced barotrauma on rockfish (Sebastes)
Authors: Rogers Bonnie L. , Lowe Christopher G. , Fernández-Juricic Esteban , Frank Lawrence R.
Published: June 2008

The physical consequences of barotrauma on the economically important rockfish ( Sebastes ) were evaluated with a novel method using T2-weighted magnetic resonance imaging (MRI) in combination with image segmentation and analysis. For this pilot study, two fishes were captured on hook-and-line from 100 m, euthanized, and scanned in a 3 Tesla human MRI scanner. Analyses were made on each fish, one exhibiting swim bladder overinflation and exophthalmia and the other showing low to moderate swim bladder overinflation. Air space volumes in the body were quantified using image segmentation techniques that allow definition of individual anatomical regions in the three-dimensional MRIs. The individual exhibiting the most severe signs of barotrauma revealed the first observation of a gas-filled orbital space behind the eyes, which was not observable by gross dissection. Severe exophthalmia resulted in extreme stretching of the optic nerves, which was clearly validated with dissections and not seen in the other individual. Expanding gas from swim bladder overinflation must leak from the swim bladder, rupture the peritoneum, and enter the cranium. This MRI method of evaluating rockfish following rapid decompression is useful for quantifying the magnitude of internal barotrauma associated with decompression and complementing studies on the effects of capture and discard mortality of rockfishes.
Geotechnical performance of a tunnel in till
Authors: Eisenstein Z. , Thomson S.
Published: June 2008

Two parallel tunnels were built in 1976 as part of the first phase of the Edmonton Rapid Transit System. The tunnels, approximately 250 m long, 6 m in diameter, and having centres 11 m apart have been driven in downtown Edmonton with an average of 7.5 m overburden above the crown. The tunnels were located entirely within a dense, jointed till sequence of Wisconsin age.The tunnels were advanced using a mole followed by two systems of soil support. The temporary supporting system consisted of steel ribs and timber lagging while the permanent lining was cast-in-place reinforced concrete. To reduce drag friction, the cutting profile of the mole is about 20 mm larger than the diameter of the shield. The steel ribs are expanded into place by hydraulic jacks.Two finite element analyses were performed. One predicted surface settlements and the other predicted lining stresses. The settlements predicted for a single tunnel agreed closely with observed values but the observed amount was considerably more than predicted for both tunnels. The reasons for this are suggested as being due to a cross tunnel connecting the two main tunnels and to a decrease in stiffness of the soil mass brought about by the moling of the first tunnel.in situ assessment of stresses in the ribs was not successful due largely to the fact that the ribs were not expanded entirely against the soil. Thus comparisons with predicted values could not be made and values of the earth pressure at rest could not be established. However, rib deformations were essentially complete within a few days thus confirming the essentially time-independent character of the deformational behavior of the till.
The effect of stress on strain at the onset of tertiary creep of frozen soils
Authors: Rein Jr. R. G. , Hathi V. V.
Published: June 2008

Data from creep tests on frozen sands show that the strain at the onset of tertiary creep, εpr, can depend strongly on the applied stress. This observation is supported by data published previously for a frozen clay and a frozen sandy loam. Thus, the effect of stress on εpr cannot be ignored in either theoretical or applied considerations.
Stochastic description of undrained soil strength
Authors: Harrop-Williams Kingsley , Ejezie Samuel
Published: June 2008

The probabilistic description of the undrained strength of cohesive soils is important in the reliability analysis of short-term slope stability. In this paper the undrained strength is derived to be identically beta-distributed with depth. The approach is through consideration of particle-to-particle effects in the soil and the overall contribution of both cohesion and friction to the undrained strength. The final result confirms experimental investigation in these soils.
Pressure-injected anchors in sand: load and creep behaviour
Authors: Mohamed M. K. , Hanna T. H.
Published: June 2008

This paper presents the results of recent research into the behaviour of pressure-injected anchors in sand. During the injection process, which was simulated by an anchor unit expanding radially as in a pressuremeter test, radial expansion was measured. In general there was a linear relationship between expansion pressure and static pull-out resistance. The creep coefficient was a function of the expansion pressure and the level of the applied load. The application of a small overload caused a significant reduction in creep. The reapplication of the expansion pressure resulted in an increase in pull-out capacity. The significance of these trends with respect to the control of anchor performance is discussed and the justification for some rules of thumb currently used during anchor construction are confirmed. Key words: anchors, sand, creep, testing, radial stress, relaxation, injection pressure, pressuremeter.
Total and partial factors of safety in geotechnical engineering
Authors: Baikie L. D.
Published: June 2008

The use of partial factors of safety in geotechnical design is introduced in the second edition of the Canadian Foundation Engineering Manual. The partial factors have been obtained from comparisons with conventional methods of analysis. Studies presented herein for simple slopes, cantilevered rigid retaining walls, flexible sheet pile walls, shallow strip foundations, and pile foundations indicate that modifications to some of the suggested partial load and resistance modification factors are necessary if comparable designs are to be obtained. Key words: factor of safety, partial factors, limit states design, slope stability, retaining walls, shallow foundations, deep foundations, bearing capacity.
Design of axially and laterally loaded piles using in situ tests: A case history
Authors: Robertson P. K. , Campanella R. G. , Brown P. T. , Grof I. , Hughes J. M. O.
Published: June 2008

A 915 mm diameter steel pipe pile was driven and tested by the B.C. Ministry of Transportation and Highways as part of their foundation studies for the proposed Annacis channel crossing of the Fraser River. The pile was driven open ended to a maximum depth of 94 m. The pile was tested axially to failure when the pile tip was at depths of 67, 78, and 94 m below ground surface. Following the final axial load test, the pile was loaded laterally to a total deflection at the ground surface of 150 mm. A slope indicator casing was installed in the pile to monitor the deflected shape during lateral loading.Adjacent to the pile, a piezometer-friction cone penetration test (CPT) and a full-displacement pressuremeter profile were made. Results of the axial and lateral load tests are presented along with the data from the CPT and the full-displacement pressuremeter tests. Results of several analyses using the data from the CPT and pressuremeter tests to predict the axial and lateral performance of the pile are presented. A comparison and discussion is presented between the predicted and measured axial and lateral behaviour of the pile, for which excellent agreement was found. Key words: pile load test, cone penetration test, pressuremeter test.
Creep behaviour of a buffer material for nuclear fuel waste vault
Authors: Yong Raymond N. , Boonsinsuk Prapote , Yiotis Demos
Published: June 2008

In the Canadian nuclear fuel waste disposal concept currently under study, one of the prime candidate procedures is the borehole emplacement technique. Each fuel waste container will be placed in a 1.1 m diameter hole in the floor of a disposal vault in deep plutonic rock. The container will be surrounded by buffer material consisting of a mixture of clay and sand. This study examines the creep behaviour of the buffer material in the borehole during interaction with the waste container and the host rock. It simulated the buffer – container – host rock interaction through a small-scale physical model using the loading pressures anticipated in the full-size system. The results from the model tests were compared with those predicted by a finite element analytical model. The creep behaviour of the full-size system was then predicted using the analytical model.From the results, it is evident that the creep behaviour of the buffer material depends significantly on interaction within the container – buffer – host rock system, overburden pressure, and water uptake. At relatively low overburden pressures, the waste container might settle, causing a separation between the buffer material and the container top. However, this could be alleviated by the swelling properties of the buffer material. The secondary creep rates are negligible, and creep in the buffer material is primarily governed by the primary creep stage. Key words: creep, model test, swelling soil, soil deformation, unsaturated soil, finite element analysis.
The convergence meter
Authors: Stacey T. R. , Wrench B. P.
Published: June 2008

A simple, robust, telescopic instrument has been developed into an accurate tool for determining the closure movements in mine stopes. It consists of a central section graduated with a vernier scale, connected to a telescopic section that can be easily adjusted to provide a series of ‘steps’ or ‘ranges’ inside which small rock movements between permanently mounted studs can be measured. The instrument itself is taken away when not in use. The basic unit provides a continuous measuring range from 1.0 to 1.75 m, with a measuring sensitivity of 0.1 mm.
Triaxial stress relaxation tests on Saskatchewan potash
Authors: Chen Rui , Stimpson B.
Published: June 2008

Relative to the study of creep, the stress relaxation phenomenon has been overlooked in research on salt rocks, especially with respect to the behavior of salt in deep underground mining environments. In the laboratory tests described in this paper, deformational properties of potash were first studied by performing reverse-loading tests that approximately simulate in situ loading paths during excavation of underground cavities. Potash relaxation properties were then investigated by multiple-stage, repeated relaxation tests along the reverse-loading path. Results show that potash behavior along a reverse-loading path is highly stress rate dependent and is reflected in the dependence of the initial axial deformation modulus, ductile point, and post-yield behavior on the rate at which the deviatoric stress is applied to the specimen. The inserted relaxation phases did not significantly affect the subsequent behavior of the potash, and therefore inserted relaxation tests are useful for investigating time-dependent behavior at various stages of deformation. A linear relationship exists between normalized stress drop and logarithm of time, which might imply that potash has no creep limit. Finally, an attempt was made to extend a uniaxial strain hardening constitutive law postulated by another researcher to include confining pressure, and the experimental data were found to approximately fit the proposed constitutive model. Key words : potash, stress relaxation, triaxial tests, constitutive model.
Contaminant migration in engineered clay barriers due to heat and moisture redistribution under freezing conditions
Authors: Mohamed Abdel M.O. , Yong Raymond N. , Mazus Miroslawa T.
Published: June 2008

In this study, the effect of temperature distribution and its influence on contaminant migration in a silty clay soil were examined. Three series of freezing-column tests were performed with three different fluids: distilled water, municipal waste leachate, and heavy metal – leachate solution. It was found that temperature distribution as a function of space and time was similar in all tests, most likely as a result of the limited amount of fluid intake. Moisture redistributions were varied as a function of experiment duration and the type of fluid used. The amount of fluid intake was directly related to the freezing time and the temperature gradient in the freezing column. The amount of unfrozen water content, ion concentration and temperature gradient were the controlling parameters that contributed to the contaminant transport in the frozen illitic silty clay soil. Na+-concentration profiles were mostly dependent on water movement in the soil column. The behaviour of Ca2+ and Mg2+ cations was similar to Na+; their concentrations in the soil solution decreased with freezing time due to ion exchange. The large accumulations of Pb2+, Zn2+, Cu2+, and Cd2+ in the lower 10 mm of the soil column occurred as a result of cation exchange and precipitation mechanisms. Key words : unsaturated, osmotic, diffusion, buffer, exchange, transport.
Field performance of the port of Sepetiba test fills
Authors: Garga Vinod K. , Medeiros Luciano V.
Published: June 2008

The design of the industrial port of Sepetiba, 50 km south of Rio de Janeiro, Brazil, required a detailed evaluation of the underlying soft soil deposits. Initially, on the basis of laboratory tests, it was proposed to remove approximately 3.7 × 106 m3 of the very soft deposits in the stockpile area by dredging and substitute with hydraulic sand fill. Subsequently, in view of the cost of such a measure, a large program of field investigations was initiated to study the in situ characteristics of the soft clay to evaluate whether replacement of this material and (or) ground improvement was necessary. As part of this investigation, two large identically instrumented test fills (test fills B and D), each 65 m2 in plan and 5 m high, with 3:1 slopes were constructed. Test fill B was constructed over natural ground, whereas the subsoil beneath test fill D was treated with stone columns. The instrumentation for each test fill consisted of piezometers, deep settlement plates, surface settlement plates, and inclinometers. This paper provides a description of the field investigations, observations on installation of stone columns, analysis of instrumentation, a comparison of the behaviour of the two test fills, and a discussion on load tests on individual stone columns. Key words : case history, embankment, ground improvement, instrumentation, soft clay, stone columns.
Analyse de la liquéfaction et du comportement non drainé des sables du delta de Kenamu (Projet ADFEX)
Authors: Couture Réjean , Locat Jacques , Konrad Jean-Marie
Published: June 2008

Jointly sponsored by France, Norway, and Canada, the ADFEX project (Artic Delta Failure Experiment) aims at triggering a full-scale submarine slide. For that purpose, a delta is destabilized by blasting to induce instantaneous liquefaction of the delta front. The selected site is the delta of Kenamu River at Melville Lake (Labrador), located approximately 40 km northeast of Goose Bay. The delta sediments are angular fine silty sands constituted mainly of quartz. A series of consolidated isotropically and undrained triaxial tests was performed on specimens of reconstituted loose sands to establish the boundaries between the contracting and dilating behaviours (steady state line or F line) and the upper and lower limits of the boundaries within the bidimensional diagram void ratio – mean effective stress. A soil state above this boundary region constitutes a necessary condition to liquefaction. The results of the triaxial tests are used to evaluate the liquefaction potential of Kenamu delta. Key words : liquefaction, sand, steady state, triaxial test, undrained, delta.
GROWTH AND SPECTROSCOPIC CHARACTERIZATION OF Mg:Ce:Cu:LiNbO3 CRYSTALS
Authors: FAN YEXIA , LI HONGTAO , ZHAO LIANCHENG
Published: June 2008

Congruent Ce (0.1 wt %): Cu (0.05 wt %): LiNbO 3 single crystals doped with 0, 1, 3, 4, 5, 6 mol% MgO respectively were grown by the Czochrolski method in air along the C direction. The inductively coupled plasma optical emission/mass spectrometry (ICP-OE/MS), the X-ray powder diffraction (XRD), the differential thermal analysis (DTA), the ultraviolet-visible (UV-Vis) absorption spectra and the infrared (IR) absorption spectrum were measured and discussed in terms of the spectroscopic characterization and the defect structure of the Mg:Ce:Cu:LiNbO 3 crystals. The results indicated that the Mg:Ce:Cu:LiNbO 3 crystal grown from the congruent composition melt showed large [ Li ]/[ Nb ] ratios, which was closer to stoichiometry, an increase in the Curie temperature and a non-linear shift in the absorption edge with MgO concentration increasing. The threshold concentration of MgO in Mg:Ce:Cu:LiNbO 3 of nearly 5.52 mol% was estimated.
VARIOUS MEASURING PROPERTIES FOR THE BIPARTITE CONTINUOUS ENTANGLED STATE
Authors: LIU TANG-KUN , FAN HONG-YI
Published: June 2008

We have calculated different kinds of measurement results for the bipartite continuous entangled state |η〉. It is found that the second particle 2 simultaneously collapses to the similar type state to the measurement basis performed on the particle 1, which manifestly exhibits quantum entanglement. The calculation is greatly simplified by virtue of the the Schmidt decomposition of |η〉 and the properties of |η〉.