bluuebunny/crossref_metadata_2025 huggingface dataset:
Inception of a Devonian subduction zone along the southwestern Gondwana margin: 40Ar–39Ar dating of eclogite–amphibolite assemblages in blueschist boulders from the Coastal Range of Chile (41°S)
Authors: Kato Terence T. , Sharp Warren D. , Godoy Estanislao
Published: May 2008

Coarsely crystalline residual blueschist boulders from the Coastal Range of south-central Chile (41°S) contain relict eclogite–amphibolite assemblages that provide evidence of pre-Carboniferous high pressure relative to temperature (high P/T) metamorphism along the southwestern continental margin of Gondwana. Early assemblages in the exotic boulders include omphacite, garnet, and hornblende that indicate eclogite-facies conditions of T = 553 ± 30 °C and P > 1.32 ± 0.04 GPa during metamorphism, corresponding to a low geothermal gradient of <12.5 °C/km. These phases are replaced to varying degrees by sodic amphibole + epidote assemblages. Relict hornblende from an early garnet amphibolite assemblage within blueschist yields an 40Ar–39Ar plateau age of 361 ± 1.7 Ma, providing a minimum age for early high P/T metamorphism. Coarse white micas that partially replace the hornblende and are in textural equilibrium with glaucophane yield plateau and near-plateau ages of 325 ± 1.1 Ma and ∼320 Ma, respectively. We interpret these data to indicate that late Paleozoic high P/T metamorphism related to subduction of oceanic lithosphere along the southwestern paleo-Pacific margin of Gondwana began prior to 361 Ma (Late Devonian). Subsequent retrograde metamorphism involving fluid infiltration and decreasing thermal gradients resulted in conversion of coarse eclogite–amphibolite to blueschist by ∼325 Ma in the dated samples.
Exploratory data analysis of the interactions among physics, food web structure, and function in two Arctic polynyas
Authors: Berreville Olivier F. , Vézina Alain F. , Thompson Keith R. , Klein Bert
Published: May 2008

Polynyas are areas of open water in ice-covered seas, characterized by high biological productivity. The NEW (Northeast Water) and NOW (North Water) polynyas, located off the east and west coasts of Greenland, were extensively sampled in 1993 and 1998, respectively. We used principal component analysis to explore the seasonal covariations among physical, chemical, and ecological characteristics in these polynyas. In both polynyas, the most explanatory eigenvector revealed the expected seasonal development of the bloom (nutrient consumption and biomass increases) associated with declining ice cover, warming, and mixed-layer shallowing. This seasonal pattern, however, was much weaker in NEW than in NOW. No connections between the structure of the food web and recycling processes were apparent in either polynya. The analysis points to much stronger and richer interactions between the mesoplankton (i.e., diatoms–zooplankton) and microbial food webs in NOW than in NEW. The differences between the polynyas may be explained in part by differences in their longevity, with the longer-lived NOW polynya having more time to develop complex trophic interactions. The results also indicate that the connections between food web structure and ecosystem function (i.e., new production versus recycling), at least at the seasonal scale, are weaker than expected.
Influence of landscape on resident and anadromous life history types of Oncorhynchus mykiss
Authors: Narum Shawn R. , Zendt Joseph S. , Graves David , Sharp William R.
Published: May 2008

Landscape features can significantly influence genetic and life history diversity of rainbow/steelhead trout, Oncorhynchus mykiss . In this study, heterozygosity of 21 populations of O. mykiss from the Pacific Northwest, USA, was significantly negatively correlated with features such as elevation (P = 0.0023), upstream distance (P = 0.0129), and precipitation (P = 0.0331), and positively correlated with temperature (P = 0.0123). Mantel tests of isolation by distance were significant for anadromous populations (P = 0.007) but not for resident collections (P = 0.061), and suggested that fluvial distance was not the only significant physical variable that influenced genetic structure of life history types. Principal components interpolated to the drainage indicated that high-elevation sites were primarily occupied by the resident form, and high gradients and barriers act to limit anadromous distribution to lower elevation sites. These patterns of O. mykiss life history diversity provide insight regarding the interaction, distribution, and limitations of resident and anadromous forms of the species within this region.
Growth analysis and age validation of a deepwater Arctic fish, the Greenland halibut (Reinhardtius hippoglossoides)
Authors: Treble Margaret A. , Campana Steven E. , Wastle Rick J. , Jones Cynthia M. , Boje Jesper
Published: May 2008

The accuracy of age interpretations on a deep-sea, Arctic fish species, the Greenland halibut ( Reinhardtius hippoglossoides ) was tested using several age validation methods. Consistent annual growth increments were either not formed or not visible in either whole or sectioned otoliths from three fish marked with oxytetracyline and recaptured after 2–4 years at liberty. Bomb radiocarbon assays based on a local reference chronology indicated that both whole and sectioned otoliths underestimated age by 1–15 years, with an average of 6 years. Growth rates estimated using the tag recapture model GROTAG were consistent with growth rates based on the radiocarbon assays and were less than half that of previously reported growth rates. The failure of otolith sections to provide an accurate age is unusual, but may be symptomatic of very slow-growing species with unusually shaped otoliths. Greenland halibut living in the deep-sea, Arctic environment are slower growing and longer lived than previously suspected, suggesting that the age-structured basis for current fisheries management warrants careful examination. Our results highlight the importance of using rigorous tests of ageing accuracy for exploited species and confirm that such age validation methods can be applied successfully in challenging environments such as the deep sea or the Arctic.
Evaluating the role of fish behavior in surveys conducted with underwater vehicles
Authors: Stoner Allan W. , Ryer Clifford H. , Parker Steven J. , Auster Peter J. , Wakefield W. Waldo
Published: May 2008

It is often assumed that visual survey data provide more accurate fish counts than conventional extractive gear. As a result, use of underwater vehicles to assess the abundance and distribution of fishes has increased rapidly over recent years. However, a review of observations reported for 48 demersal marine fish taxa showed that almost all respond in some way to underwater vehicles. Whether or not movements or changes in behavior affect survey bias is more difficult to assess. A simple conceptual model is presented to evaluate relationships between stimulus intensity, distances from the vehicle where reactions occur, and survey bias. Largest bias is caused by attraction or avoidance that occurs outside the field of cameras or observers. While light level and vehicle speed have been explored experimentally in a few cases, much remains to be learned about how bias varies among species, age groups, different vehicles, and operating conditions. Given poor understanding of survey bias, we recommend that surveys be conducted with minimum possible variation in operations and that vehicle time is devoted to experimental evaluation of methods. There is no good substitute for direct observations on fish behavior, distribution, and abundance; and survey design can be improved through experimentation.
Patterns of larval emergence of capelin (Mallotus villosus) and environmental cues at demersal spawning sites on the northeastern coast of Newfoundland
Authors: Penton Paulette M. , Davoren Gail K.
Published: May 2008

At spawning beaches in Newfoundland, Canada, capelin ( Mallotus villosus ) larval emergence is triggered by coastal water mass replacement (CWMR). CWMR causes sharp but short increases in temperature in coastal areas by the transport of warm surface water to the coast during onshore wind events. Warm water temperatures stimulate the active emergence of capelin larvae into predator-poor and prey-rich conditions favourable for larval survival. We investigated whether wind events influenced (i) the thermal properties of the water column and (ii) the larval emergence patterns at five demersal (deep-water) spawning sites on the northeastern coast of Newfoundland during the posthatch periods in 2004–2006. Winds oriented along the shore caused frequent and sharp increases in bottom temperature at all sites but did not appear to stimulate the release of larvae into the water column. Instead, peaks in larval densities corresponded to predicted peaks in hatching. Because of this and the presence of recently hatched larvae (3–5 mm) primarily in good condition, we hypothesize that larvae simply emerged from the sediment upon hatching at these demersal spawning sites. We conclude that patterns of larval emergence at demersal sites in this region are different from those reported for the beach in other regions of Newfoundland.
Bomb radiocarbon age validation of Pacific ocean perch (Sebastes alutus) using new statistical methods
Authors: Kastelle Craig R. , Kimura Daniel K. , Goetz Betty J.
Published: May 2008

We used bomb-produced radiocarbon (14C) to validate ages of Pacific ocean perch ( Sebastes alutus ), which are routinely estimated with the cut-and-burn method at the Alaska Fisheries Science Center (Seattle, Washington, USA). New statistical methods to compare Δ14C in validation samples with a reference chronology are introduced: (i) calculating confidence intervals around the LOESS-smoothed Δ14C reference chronology using simultaneous inference; (ii) purposely adding biases to the validation sample ages and then analyzing the sum of squared residuals of the validation samples’ Δ14C about the LOESS-smoothed reference chronology; and (iii) standardizing the Δ14C measurements from the validation sample to better fit the reference chronology. Standardized Δ14C measurements are particularly useful when researchers suspect that environmental and biological differences between the validation samples and the reference chronology may exist that affect the level, but not the timing, of Δ14C in the samples. These new methods can be applied simultaneously. Two previous bomb radiocarbon studies on canary rockfish ( Sebastes pinniger ) and black drum ( Pogonias cromis ) were reanalyzed, further illustrating the usefulness of these new methods.
Effects of temperature and ultraviolet radiation on diel vertical migration of freshwater crustacean zooplankton
Authors: Cooke Sandra L. , Williamson Craig E. , Leech Dina M. , Boeing Wiebke J. , Torres Lisette
Published: May 2008

In transparent, thermally stratified lakes, ultraviolet radiation (UV) and temperature are among the primary factors influencing diel vertical migration (DVM) of zooplankton. It is not well known how behavioral responses will vary across a wide range of depths with steep gradients in UV, photosynthetically active radiation (PAR), and temperature. Our objective was to determine the relative importance of UV and temperature on DVM of Daphnia catawba and Leptodiaptomus minutus in a high UV, thermally stratified lake. Using UV-transparent (+UV) and UV-opaque (–UV) columns suspended within the mixed layer and metalimnion, we found that both species were generally shallower in the –UV than in the +UV columns. Daphnia catawba responded negatively to UV, even below the 1% depth for 320 nm, whereas L. minutus responded to UV only within the mixed layer and upper metalimnion. Daphnia catawba did not migrate in the –UV in the mixed layer, but migrated upwards in the –UV in the deep part of the metalimnion, indicating a temperature-induced rather than phototactic response. At night, both species migrated upwards in the metalimnion and were evenly distributed in the mixed layer. These results indicate that in transparent lakes, UV may constrain some zooplankton to cooler, suboptimal temperatures, which may compromise fitness.
Biological indications of contaminant exposure in Atlantic cod (Gadus morhua) in the Baltic Sea
Authors: Schnell Sabine , Schiedek Doris , Schneider Rolf , Balk Lennart , Vuorinen Pekka J. , Karvinen Heta , Lang Thomas
Published: May 2008

The Baltic Sea is exposed to severe human impacts. Besides eutrophication and overfishing, a variety of chemical contaminants threaten the health of fish. During a cruise in December 2001, Atlantic cod ( Gadus morhua ) were collected in the western and southern Baltic Sea, somatic condition factors were estimated, and different biomarkers of contaminant exposure were analysed. Additionally, various polychlorinated biphenyl congeners and organochlorine pesticides were measured in cod liver as more general indicators of pollution, not necessarily as the causative agents for biomarker signals. In most specimens, hepatic ethoxyresorufin-O-deethylase activity and bile 1-OH pyrene, a common polycyclic aromatic hydrocarbon metabolite, were detectable. Both features indicate an induction of the CYP1A biotransformation system in response to toxic substances. The increased occurrence of DNA adducts in some of the specimens also indicates the presence of genotoxic substances. Acetylcholinesterase was inhibited, an indication of exposure to organophosphates, carbamates, or certain heavy metals, particularly in specimens taken at Wismar Bay and off the Lithuanian coast. In general, spatial differences in the biomarker responses as well as in contaminant loads were found, suggesting differences in physiologically active concentrations and mixtures of organic contaminants in this ecosystem.
Statolith microchemistry as a technique for discriminating among Great Lakes sea lamprey (Petromyzon marinus) spawning tributaries
Authors: Hand Carrol P. , Ludsin Stuart A. , Fryer Brian J. , Marsden J. Ellen
Published: May 2008

Laurentian Great Lakes fishery management agencies are seeking ways to identify natal origins of parasitic- and spawning-phase sea lamprey ( Petromyzon marinus ) so that efforts to control this invasive species can be prioritized. We developed laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as a technique to quantify elemental concentrations in larval sea lamprey statoliths and explored the use of statolith microchemistry as a tool to discriminate among larval sea lamprey production streams. Our analyses demonstrate that (i) traversing across the statolith with the laser is preferable to drilling down through its apex, (ii) preserving specimens in 95% ethanol versus freezing them has minimal effects on elemental concentrations, (iii) a minimum of 15 individuals per stream should accurately depict stream-specific statolith elemental signatures, and (iv) LA-ICP-MS is preferable to particle-induced X-ray emission (PIXE) for statolith analysis, based on higher precision, lower cost, reduced sampling-time requirements, and wider availability. Using LA-ICP-MS, we could discriminate among larvae from 13 streams located in Lakes Michigan, Huron, and Superior with 82% classification accuracy, indicating that this tool holds promise for determining natal origins of sea lamprey in the Great Lakes.
A geostatistical method for assessing biomassof tuna aggregations around moored fish aggregating devices with star acoustic surveys
Authors: Doray Mathieu , Petitgas Pierre , Josse Erwan
Published: May 2008

Universal kriging was used to model the spatio-temporal variability in the acoustic density of tuna aggregations recorded during star echosounding surveys around moored fish aggregating devices (FADs) in Martinique (Lesser Antilles). The large-scale deterministic drift in the tuna spatial distribution was modeled using an advection–diffusion equation applied to animal grouping. Residuals from the drift were modeled as a random component with small-scale spatial correlation. An estimation variance formula was derived from this deterministic–statistical mixed model to assess the mean precision of density estimates of daytime tuna aggregation. The mean relative error obtained with our star design for daytime surveys was 24%. The methodology was applied to estimate daily maxima of tuna biomass around moored FADs during four monthly sea cruises. The daily peak of tuna biomass aggregated around moored FADs was 9 t on average (standard deviation = 4). Estimation variances for different survey designs were compared for optimizing sampling strategy.
Spatial and temporal variation in the natal otolith chemistry of a Hawaiian reef fish: prospects for measuring population connectivity
Authors: Ruttenberg Benjamin I. , Hamilton Scott L. , Warner Robert R.
Published: May 2008

One of the most compelling unanswered questions in marine ecology is the extent to which local populations are connected via larval exchange. Recent work has suggested that variation in the chemistry of otoliths (earstones) of fishes may function as a natural tag, potentially allowing investigators to determine sources of individual larvae and estimate larval connectivity. We analyzed the spatial and temporal variation in natal otolith chemistry of a benthic-spawning reef fish from the Hawaiian Islands. We found no consistent chemical variation at the largest scale (>100 km, among islands), but found significant variation at moderate scales (sites within islands, tens of kilometres) and small scales (clutches within sites), and chemistry of otoliths was not stable between years. These results imply that we may be able to use otolith chemistry to track larval dispersal only if the scales of dispersal match those of variation in natal otolith chemistry, and that separate natal otolith collections may be needed to track different cohorts of larvae. Finally, we found that elemental composition of recruit cores often did not match that of natal otoliths, suggesting that additional methodological development is required before we can effectively apply methods in otolith chemistry to the study of larval dispersal.
Cumulative impacts of hydrology and human activities on water quality in the St. Lawrence River (Lake Saint-Pierre, Quebec, Canada)
Authors: Hudon Christiane , Carignan Richard
Published: May 2008

The cumulative impacts of discharge and human activities on the spatial variations of water quality were assessed from monthly measurements at 80–110 stations in a ~300 km2 widening of the St. Lawrence River (Lake Saint-Pierre, Québec). Water quality was poorest under high discharge conditions and in shallow riparian areas under the influence of small tributaries draining farmlands; spatial variability was amplified by aquatic macrophytes. In 2004, over 40% of the study area exceeded the provincial water quality criterion (total phosphorus = 30 µg P·L–1) to protect aquatic life in rivers. Nutrient retention occurred mostly during summer when macrophytes were abundant and current velocities were low. Erosion of dredged deposits near the navigation channel was observed during summer, when current velocities increased in the deep channel because of flow obstruction by macrophytes growing in shallow areas. Low discharge conditions and high macrophyte abundance sharpened the contrast between the Lake Ontario waters flowing rapidly through the central river channel and the slow-flowing, low-quality tributary waters along the shores. The cumulative effect of high nutrient inflow from urban areas and farmlands, the man-made navigation channel, and seasonal flow obstruction by macrophytes thus induce a marked spatial variability in water quality within Lake Saint-Pierre.
Oxalate production by fungi: its role in pathogenicity and ecology in the soil environment
Authors: Dutton Martin V. , Evans Christine S.
Published: May 2008

Oxalate secretion by fungi provides many advantages for their growth and colonization of substrates. The role of oxalic acid in pathogenesis is through acidification of host tissues and sequestration of calcium from host cell walls. The formation of calcium oxalate crystals weakens the cell walls, thereby allowing polygalacturonase to effect degradation more rapidly in a synergistic response. There is good correlation between pathogenesis, virulence, and oxalic acid secretion. Solubility of soil nutrients is achieved by soil-living species, when cations freed by oxalate diffusing in clay layers increases the effective solubility of Al and Fe. Oxalate retained in hyphal mats of mycorrhizal species increases phosphate and sulphate availability. The formation of calcium oxalate crystals provides a reservoir of calcium in the ecosystem. The ability of oxalate to bind divalent cations permits detoxification of copper, particularly evident in wood preserved with copper salts. Oxalate plays a unique role in lignocellulose degradation by wood-rotting basidiomycetes, acting as a low molecular mass agent initiating decay. In addition, in white-rot fungi oxalate acts as a potential electron donor for lignin-peroxidase catalysed reduction and chelates manganese, allowing the dissolution of Mn3+from the manganese–enzyme complex and thus stimulating extracellular manganese peroxidase activity. The biosynthesis and degradation of oxalate are discussed.Key words: oxalic acid, calcium oxalate, pathogenicity, fungi.
Development of techniques for the genetic manipulation of the gliding bacteriaLysobacter enzymogenesandLysobacter brunescens
Authors: Lin Danli , McBride Mark J.
Published: May 2008

Lysobacter enzymogenes and Lysobacter brunescens are Gram-negative gliding bacteria that belong to the γ subgroup of the proteobacteria. As a first step toward a molecular analysis of Lysobacter gliding motility, we developed techniques to genetically manipulate these bacteria. Cosmid pSUP106 of the broad host range incompatibility group Q (Inc Q) was introduced into L. enzymogenes and L. brunescens by conjugation and electroporation. pSUP106 replicated stably in both organisms and conferred antibiotic resistance. We also identified several other plasmids (pKT210, pH1JI) that functioned in L. enzymogenes and a transposon (mini-Tn5Sp) that functioned in L. brunescens. The identification of these tools allows genetic analysis of Lysobacter gliding motility, exoenzyme production, and production of antibiotics and other secondary metabolites.Key words: Lysobacter, gliding motility, gene transfer.
A 150-megadalton plasmid in Rhizobium etli strain TAL182 contains genes for nodulation competitiveness on Phaseolus vulgaris L.
Authors: Borthakur Dulal , Gao Xuefeng
Published: May 2008

Rhizobium etli TAL182, a competitive strain for the nodulation of Phaseolus beans, occupied more than 99% of the nodules when co-inoculated in various proportions with Rhizobium TAL1145 or Rhizobium tropici CIAT899. Two overlapping cosmid clones, pUHR68 and pUHR69, containing genes for nodulation competitiveness from TAL182, were isolated by functional complementation of strain TAL1145. Using one of these cosmid clones, we constructed two Tn5-insertion mutants of TAL182 defective in nodulation competitiveness. The Tn5 insertions in both mutants were localized in identical positions within a 4.6-kb HindIII fragment. One mutant, RUH120, was complemented for nodulation competitiveness by this HindIII fragment. The cloned DNA in pUHR68 is a part of a plasmid, 150 MDa in size, in TAL182 and does not show homology with TAL1145 genomic DNA. The 4.6-kb HindIII fragment contains a gene(s) required for nodulation competitiveness on beans, which is present only in some R. etli strains and absent in other Rhizobium spp.Key words: nitrogen fixation, competition, nodule, common bean.
Enhancement of marine bacterial growth by mineral surfaces
Authors: Taylor Gordon T. , Gulnick Jeanne D.
Published: May 2008

The effects of sorptive inert surfaces on growth of marine bacteria and metabolism, as well as partitioning of organic substrates, were examined in microcosms inoculated with bacterioplankton from a local salt marsh. Introduction of organic-free glass beads to a dilute seawater medium (tryptic soy broth) increased yields of ATP, a surrogate for bacterial biomass, by 187% within the entire microcosm (attached + free-living). Growth efficiencies (bacterial C/media C) were 30% for bacteria grown in microcosms with beads compared with 16% without beads. Surface enrichment increased rates of proteolytic enzyme activity and cell-specific [3H]leucine incorporation into protein by factors of 6.8 and 2.2, respectively. Scanning electron microscopy revealed obvious organic coatings on all beads after 2 h of exposure, but few strongly attached bacteria were evident, even after 40 h of exposure. Results support the hypothesis that mineral surfaces facilitate bacterial utilization of complex organic matter through physical–chemical processes that increase conversion efficiencies of labile substrate despite possible kinetic limitations. Furthermore, firm attachment by bacteria to these surfaces is apparently not a requirement to produce surface-enhanced activity.Key words: epibacteria, sorption, interfaces, hydrolytic enzymes, growth efficiency.
Cloning and characterization of transcriptional promoters fromBacillus subtilisphage 2C
Authors: Daxhelet Guy , Gilot Philippe , Hoet Philippe
Published: May 2008

Phage 2C is a Bacillus subtilis lytic phage, whose genome contains hydroxymethyluracil in place of thymine. To isolate promoters of early phage genes involved in the take-over of cellular metabolism, 2C DNA libraries were constructed in promoter-probe plasmids replicating in Escherichia coli and B. subtilis. Four different 2C DNA fragments strongly expressed reporter genes in E. coli but not in B. subtilis. All fragments originated from unique sequences of the genome and not from its terminal redundancies. One fragment was sequenced. Despite the presence of an σA-RNA polymerase binding site upstream of the transcriptional initiation site of a 2C early gene, this fragment did not promote transcription in B. subtilis.Key words: hydroxymethyluracil, lytic phage, promoter-probe plasmid, Bacillus subtilis, gene expression.
Effects of a strain of Saccharomyces cerevisiae (Levucell® SC), a microbial additive for ruminants, on lactate metabolism in vitro
Authors: Chaucheyras Frédérique , Fonty Gérard , Gouet Philippe , Bertin Gérard , Salmon Jean-Michel
Published: May 2008

The effect of Levucell® SC, a strain of Saccharomyces cerevisiae marked as a feed additive for ruminants, was investigated in vitro on lactate metabolism by the ruminal bacteria Streptococcus bovis and Megasphaera elsdenii. The coculture between 107 live cells∙mL−1 of SC and a Streptococcus bovis strain in the presence of glucose reduced lactate production by the bacterial strain. Live yeast cells were able to compete with Streptococcus bovis for glucose utilization in strictly anaerobic conditions, so less glucose was available for the bacterium. SC also stimulated L-lactate utilization by a strain of M. elsdenii. The effect depended on the concentration of yeast cells added. Bacterial growth and fermentation end-product concentrations were also increased in the presence of SC. Some amino acids and vitamins, but not dicarboxylic acids, stimulated the bacterial specific activity of L-lactate uptake. SC was able to provide amino acids to M. elsdenii. In a coculture of Streptococcus bovis and M. elsdenii on glucose, the reduction of lactate concentration was improved by SC, the same trend being observed when maltose or soluble starch were used as carbon and energy source. These results indicate that SC can be a very useful tool to reduce lactate accumulation in vitro during fermentation of soluble sugars.Key words: rumen, Saccharomyces cerevisiae, lactate metabolism, Streptococcus bovis, Megasphaera elsdenii.
Endoglucanase G from Fibrobacter succinogenes S85 belongs to a class of enzymes characterized by a basic C-terminal domain
Authors: Iyo Abiye H. , Forsberg Cecil W.
Published: May 2008

A 3.6-kb fragment of the Fibrobacter succinogenes S85 DNA was sequenced and found to contain two open reading frames (ORFs) on the same strand separated by 242 nucleotide bases. The translated protein from ORF1 had a predicted mass of 52.3 kDa. In a region of 320 amino acid overlap, it shares a 35% identity with the b-chain of the glutamate synthase of Escherichia coli. The ORF2 protein encodes a 519 residue protein designated CelG. It consists of an ORF of 1557 bp, encoding a polypeptide of 54.5 kDa. The N-terminal region, which contains the catalytic domain, is linked to a C-terminal basic domain, which has a predicted isoelectric point of 10.8. The catalytic domain in endoglucanase G (CelG) is homologous to the family 5 (A) cellulases. The enzyme has an apparent mass of 55 kDa, a pH optimum of 5.5, and temperature optimum of 25 °C. It had a specific activity of 16.5 mmol∙min−1∙mg−1 on barley b-glucan and produced a mixture of cellooligosaccharides from the hydrolysis of acid swollen cellulose and cellooligosaccharides. Antiserum raised against the purified form of CelG in E. coli failed to react with proteins from the native organism when grown on either glucose or crystalline cellulose, but reverse transcription and polymerase chain reaction techniques using RNA from the native organism demonstrated that the celG gene was expressed constitutively. Its distribution amongst subspecies of Fibrobacter was restricted to F. succinogenes S85.Key words: basic terminal domain, Fibrobacter succinogenes, endoglucanase, nucleotide sequence.
Leishmania(V.)guyanensis: isolation and characterization of glucantime-resistant cell lines
Authors: Ferreira-Pinto K. C. , Miranda-Vilela A. L. , Anacleto C. , Fernandes A. P. S. M. , Abdo M. C. B. , Petrillo-Peixoto M. L. , Moreira E. S. A.
Published: May 2008

A glucantime sensitive Leishmania (V.) guyanensis strain was used to obtain in vitro resistant cell lines, by increments in glucantime concentrations employing both one step and stepwise protocols. Whereas the effective concentration of drug that inhibited the growth of wild type cells by 50% (EC50value) was 0.20 mg Sbv/mL, the resistant cells were able to grow in glucantime concentrations greater than 8.0 mg/mL. The resistant cell lines were partially characterized by their in vitro response to glucantime, the stability of resistance phenotype, cross resistance to a range of drugs, and also by the analysis of total DNA fragments generated by restriction endonucleases and blot hybridization. Amplified DNA sequence similar to a P-glycoprotein analog from Leishmania tarentolae (ltpgpA gene) was observed in all the resistant cell lines obtained through the one-step protocol. These cell lines showed cross resistance to heavy metals but were sensitive to puromycin, vinblastine, and pentostam.Key words: Leishmania, glucantime resistance, pentavalent antimony, gene amplification.
Influence de la monensine sur la croissance et la sécrétion des exopolysaccharides chez le Botrytis cinerea Pers. et le Sclerotium rolfsii Sacc.
Authors: Koulali Yahya , Talouizte Ahmed , Fonvieille Jean-Louis , Dargent Robert
Published: May 2008

The addition of various concentrations of monensin (1, 5, and 10 μg/mL) to the culture medium inhibits the fungal growth and perturbs exopolysaccharides secretion, provoking a decrease of production in Botrytis cinerea and an increase in Sclerotium rolfsii. The ionophore induces also modifications in both polymer composition and structure. New monomers were observed in the two species and a decreased branching rate for Sclerotium rolfsii. These modifications show that monensin affects the enzymes responsible for normal wall synthesis and therefore vesicular traffic.Key words: monensin, growth, exopolysaccharides, Botrytis cinerea, Sclerotium rolfsii.
Detection of plasmid-like DNA and double-stranded RNA elements in some Canadian isolates of the oilseed rape pathogen Leptosphaeria maculans
Authors: Patterson N. A. , Kapoor M.
Published: May 2008

Nine Canadian isolates of Leptosphaeria maculans were examined for the presence of plasmid-like elements. A single extrachromosomal DNA element, with an estimated size of 9 kb, was detected in undigested genomic DNA of a virulent isolate, Fairview 1. This element was susceptible to hydrolysis by DNAse I and exonuclease III, and it was shown to hybridize to DNA of all virulent isolates. In addition, another virulent strain, Saskatoon 8, was observed to contain four double-stranded RNA (dsRNA) segments, ranging from approximately 500 bp to 2.4 kb. The latter segments (dsRNA) were resistant to DNAse I and exonuclease III treatment, and to RNAse A in high-ionic-strength buffer, but were susceptible to RNAse A in the presence of low-ionic-strength buffer.Key words: Leptosphaeria maculans, Canola, double-stranded RNA, plasmids.
Analytical Solutions of Special Queuing Situations in Logging
Authors: Meng C. H.
Published: May 2008

Three cases in logging can be considered as queuing situations: the operation of (1) the felling and processing devices of a tree harvester, (2) the pick-up and processing devices of a processor, and (3) manual felling machine skidding. These cases can be represented by a queuing model with a special characteristic — queue length equals zero or one. Analytical solutions of this model that involve deriving the means, variances, and probability density functions of waiting times and idle times are developed.
Rates and Times at Which Needles are Initiated in Buds on Differing Provenances of Pinuscontorta and Piceasitchensis in Scotland
Authors: Cannell M. G. R. , Willett S. C.
Published: May 2008

During 1973, bud formation was monitored by sampling terminal buds from the topmost branches on four provenances plus one interprovenance hybrid of 10-year-old Pinuscontorta, and five provenances of 8-year-old Piceasitchensis, all growing in forest trials in Scotland. On both species, extension growth occurred between late May and mid-July. On pine, buds began forming in April; about a third of next year's needles (axillary bud primordia) were formed before mid-July and all were formed by mid-September. On spruce, bud formation occurred from May to October.Northerly and inland montane provenances began producing primordia earlier in spring than southerly provenances, suggesting differences in temperature sensitivity. The dates when bud development ceased were more closely related to latitude of seed origin, suggesting differences in photoperiod sensitivity. Differences among pine provenances in total numbers of primordia formed were related to differences in maximum rates of initiation during the summer, whereas in spruce they were due to differences in seasonal duration. In all cases, rates of initiation were closely correlated with apical dome diameters. Implications are noted regarding conifer breeding and environment–genotype interactions.
Pruning Northern Red Oak Nursery Seedlings: Effects on Root Regeneration and Early Growth
Authors: Larson M. M.
Published: May 2008

Northern red oak seedlings were top-pruned in the seedbed each month from August until the next March. In late March, all trees were lifted, planted in the greenhouse, and harvested 30 days later. Any top-pruning treatment that directly or indirectly removed the leaves in late summer or early fall markedly reduced root regeneration and initial shoot growth after planting in March. Removal of all the visible buds at any date resulted in increased numbers of new shoots after planting, while pruning stems at the groundline reduced new shoot growth.In additional studies, shoots and roots of trees lifted in March were pruned to various levels before planting. Results indicated that root pruning influenced seedling growth much more than shoot pruning. The amount of new shoot growth was significantly correlated with root weight of seedlings when planted, whether differences in root weight were natural or obtained by pruning. The effects of shoot pruning and root pruning on seedling growth were largely independent of each other.
Insect Attack and Value Loss in Wind-damaged Spruce and Jack Pine Stands in Northern Ontario
Authors: Gardiner Lorne M.
Published: May 2008

The forests of northern Ontario are damaged frequently by strong winds that develop along cold fronts. Deterioration of spruce (Picea spp.) and jack pine (Pinusbanksiana Lamb.) saw timber because of wood-boring insects was studied in an extensive area of blowdown between 1969 and 1972. Sawyer beetles (Monochamus spp.) were the most important agents of degrade, but a surprising amount of damage was caused in spruce by Tetropium spp. Broken trees fared worst, but all uprooted trees were heavily attacked by 2 years after the storm. Milling studies showed about a 10% loss in all material combined 1 year after the storm, with the loss in general more than doubling in the 2nd year. The greatest loss occurred in white spruce (Piceaglauca (Moench) Voss), which was of greater original value than jack pine. Trees left standing were not attacked by emerging beetles but were subject to windthrow by relatively light winds. Salvage operations, when desirable, should begin as soon as possible after a blowdown and all stems, including those left standing, should be harvested at once.
Kraft Pulping and Specific Gravity in the Uppermost Stem of Fertilized Balsam Fir
Authors: Gagnon J. D. , Hunt K.
Published: May 2008

Samples of five pairs of fertilized and non-fertilized 60-year-old natural balsam fir (Abiesbalsamea (L.) Mill.) growing in the Quebec boreal forest region were pulped by the kraft process and the specific gravity was measured. Analyses carried out 7 years after treatment on the last seven terminal internodes revealed the mean pulp yield of trees fertilized exceeded that of non-fertilized by 7%, while the mean specific gravity was about 6% lower.
Biomass and Productivity of an Alder Swamp in Northern Michigan
Authors: Parker George R. , Schneider G.
Published: May 2008

Total aboveground dry weight biomass and annual production were determined for two sites of different soil texture in an alder swamp of Michigan's upper peninsula. The more poorly drained site A averaged 5300 g/m2 and 640 g/m2 per year while site B averaged 3100 g/m2 and 570 g/m2 per year. The smaller standing-crop biomass on the better-drained site B is due to greater abundance of Alnusrugosa. The tree stratum constitutes 97 and 93% of the total biomass and 84 and 80% of the total production on site A and B, respectively. The understory strata constituted the remaining 3 and 16% of the biomass and production on site A and 7 and 20% on site B.
Effects of Thinning and Fertilization on Foliar Nutrient Concentrations of Sugar Maple
Authors: Stone D. M. , Christenson D. R.
Published: May 2008

Effects of thinning and fertilization on growth and foliar nutrients were studied in pole-size sugar maple (Acersaccharum Marsh.). Thinning plus fertilization resulted in significantly lower concentrations of foliar N, P, K, Mg, Cu, Zn, B, and Al in the first growing season, and of Mg, Cu, Zn, and Al in the 2nd year. Foliar nutrients in released, but nonfertilized, trees exhibited similar trends. The decreased foliar nutrient concentrations are attributed to dilution effects as a result of increased growth.Fertilization with N, P, and K significantly increased foliar concentrations of those nutrients but did not stimulate radial growth. Thinning resulted in highly significant increase in diameter growth both years.
Chromatographic Analysis of an Open-pollinated Rosendahl Spruce Progeny
Authors: Riemenschneider Don , Mohn Carl A.
Published: May 2008

Chromatographic evaluation of foliage extracts from 25 white spruce, 25 black spruce, Rosendahl spruce, and 61 open-pollinated progeny of Rosendahl spruce provided additional evidence of the hybrid origin of Rosendahl spruce. Individual trees were scored on the basis of the presence or absence of spots indicating flavanoid compounds. The score for the Rosendahl spruce and the mean score of its 61 progeny were intermediate to the mean scores for white and black spruce. Chromatographic scores for the progeny group were more variable than those obtained from either the white or black spruce samples.
The Effect of High Concentrations of Ethylene on Seed Germination of Douglas Fir (Pseudotsugamenziesii (Mirb.) Franco)
Authors: Borno Carey , Taylor Iain E. P.
Published: May 2008

Stratified, imbibed Douglas fir (Pseudotsugamenziesii (Mirb.) Franco) seeds were exposed to 100% ethylene for times between 0 and 366 h. Germination rate and germination percentage were increased by treatments up to 48 h. The 12-h treatment gave largest stimulation; 30% enhancement of final germination percentage over control. Treatment for 96 h caused increased germination rate for the first 5 days but reduced the germination percentage. Germinants were subject to continuous exposure to atmospheres containing 0.1 – 200 000 ppm ethylene in air, but it did not stimulate growth, and the gas was inhibitory above 100 ppm. Although some effects of high concentrations of ethylene may have been due to the lowering of oxygen supplies, this alone was insufficient to account for the full inhibitory effect. The mechanism of stimulation by short-term exposure to ethylene is discussed.
Some Tree Growth – Wood Property Relationships of Eucalypts
Authors: Nicholson J. E. , Hillis W. E. , Ditchburne N.
Published: May 2008

The relationship between level of longitudinal growth strain and stress, modulus of elasticity, basic density, volumetric shrinkage, fiber classification, and stem form was investigated with 10 Eucalyptusregnans regrowth trees. Close relationships were observed. It is suggested that variations in these properties within trees are closely controlled, possibly to enable optimum positioning of the tree crown in relation to its immediate environment. The concept of fiber structure varying as a response to environment is supported by the observed variation in wood properties within and between trees of this species. The often-reported association between eccentric radial growth and reaction wood was not substantiated in this study.The data indicate that if economically justifiable, it would be possible to segregate trees that are likely to contain material that is hard to season.
Biology, Damage, and Chemical Control of the Poplar Borer (Saperdacalcarata) in the Junction of the Root and Stem of Balsam Poplar in Western Canada
Authors: Drouin J. A. , Wong H. R.
Published: May 2008

The life history of Saperdacalcarata Say in the junction of root and stem of balsam poplar follows closely that reported by Peterson (1947) in the stem of trembling aspen. The insect requires at least 3 years to complete its life cycle; damage is restricted to the segment of the stem above and adjoining root below ground level.Larvae reared from the junction of root and stem substantiated the varietal status of S. adspersa by developing into females with mainly bluish elytra (S. calcarata) and males with mostly brownish elytra (S. calcarata var. adspersa). Eight species of parasites, two species of predators, and five species of insects associated with S. calcarata are listed. Ten systemic insecticides were tested against this insect. Best results were obtained with dimethoate (Cygon 4E®) applied as a soil drench.
The Influences of Rooting Volume – Seedling Espacement and Substratum Density on Greenhouse Growth of Lodgepole Pine, White Spruce, and Douglas Fir Grown in Extruded Peat Cylinders
Authors: Hocking D. , Mitchell D. L.
Published: May 2008

Seedlings of white spruce (Piceaglauca (Moench) Voss var. albertiana (S. Brown) Sarg.), lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.), and Douglas fir (Pseudotsugamenziesii (Mirb.) Franco) were grown in closely packed, extruded peat cylinders (sausages) of different lengths, diameters, and densities within a range practical for operational use. The highest density (0.23 g/cm3) was limiting to all growth parameters for all species in all rooting volumes – espacements. In lower densities, all growth parameters were linearly correlated to rooting volume. In the smaller rooting volumes – seedling espacements, growth restrictions were partially relieved by compression of the peat up to density 0.20 g/cm3.
Rôle protecteur du Suillusgranulatus contre le Myceliumradicisatrovirens sur des semis de Pinusresinosa
Authors: Richard Claude , Fortin J.-André
Published: May 2008

Suillusgranulatus prevented the stunting effect of root pathogen Myceliumradicisatrovirens on Pinusresinosa (red pine) seedlings grown in gnotobiotic conditions. In these conditions, the presence of carbon dioxide also seems to have stimulated a better growth of the seedlings inoculated with Suillusgranulatus as compared with the controls. In the light of these findings, the authors suggest caution in the interpretation of results from experiments in closed containers.Suillusgranulatus has an antagonistic effect against many pathogenic fungi probably as a result of the production of an antibiotic.
Effects of Drought and Defoliation on Some Metabolites in Roots of Black Oak Seedlings
Authors: Parker Johnson , Patton Roy L.
Published: May 2008

Starch levels in roots were lower in defoliated, watered black oak seedlings than in non-defoliated, watered seedlings in two separate experiments. Starch levels in unwatered, non-defoliated seedlings were lower only when drought was severe. Drought and defoliation together resulted in lower starch levels than either one alone. Reducing sugars and several amino acids were higher in unwatered seedlings than in nondefoliated and watered ones, but not in those subjected to less severe droughts. Some increase in averages of reducing sugars and certain amino acids occurred in once- and twice-defoliated, watered plants. Levels of catechin and quercitrin were usually lower in defoliated than in nondefoliated seedlings, regardless of watering, and higher in unwatered seedlings than in watered ones, regardless of defoliation. Addition of fertilizer to the soil had no effect on growth, but in some combinations of drought and defoliation it resulted in lower carbohydrate levels.
Environmental Control of Cold Acclimation in Douglas Fir During Germination, Active Growth, and Rest
Authors: Timmis R. , Worrall J.
Published: May 2008

Controlled-environment experiments were conducted on Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings during their 1st year. Hardiness of foliage was assessed by visually estimating injury after freezing tests.Germinants (1 week) were unable to attain any freezing tolerance under 8-h days at 2 °C even after 9 weeks but were killed whenever ice formed. Their ability to supercool increased by 5 °C during this treatment. However, seedlings older than 3 weeks (1 to 2 cm of epicotyl) could develop true hardiness under the influence of either short days (less effective) or low positive temperatures, independently of lignification, bud setting, or entry into rest. Ability to acclimate increased gradually with age and was inversely related to growth and maturation, apparently because the latter processes had higher temperature optima. Photoperiod affected growth and bud formation only above about 15 °C but influenced hardiness at 1 °C. The optimum photoperiod for inducing hardiness was longer at low light intensities than at high ones, presumably because of a minimum requirement for photosynthesis.Interruption of the long inductive dark period with 15 min of red light (650 nm) caused a small decrease in hardiness and bud set and an increase in growth. This effect was not reversed, but was enhanced by an isoenergetic burst of far-red (FR) light immediately after. FR interruptions alone had no effect. Night frosts (−7 °C) caused significant dehydration and rapidly increased hardiness only if both the warm, short day and chilling "stages" had been supplied first and the daily supply of light continued.