bluuebunny/crossref_metadata_2025 huggingface dataset:
Mutant analysis ofPrevotellasp.plaA-lacZfusion protein expression inEscherichia coli: support for an essential role of the stem-loop
Authors: Manch-Citron Jean N , Dey Anjana , Ewell John B , Nguyen Nga Y
Published: April 2011

This study investigated the involvement of RNA folding in the synthesis of a fusion protein with beta-galactosidase activity. The coding gap region of the Prevotella loescheii adhesin gene plaA was fused in-frame with the Escherichia coli lacZ gene on plasmid pSK105. N-Terminal sequencing of the expressed plaA-lacZ protein indicated that it resulted from translational initiation at a fortuitous ribosomal-binding site within the plaA sequence at nt 570. Specific mutations were introduced in the stem-loop region that precedes the gap sequence. Analysis of stem-loop mutants, together with the introduction of compensatory mutations that restored activity, supports a requirement for stem-loop formation within the plaA sequence preceding the translational initiation site. A mutation reducing the predicted size of the loop, but preserving the stem structure, inactivated fusion protein synthesis. A suppressor mutation predicted to restore the size of the loop restored efficient fusion protein synthesis. In addition, the sequence preceding the translational start site of the plaA-lacZ fusion has several similarities to sequences that function as translational enhancers in prokaryotes. These include a stem-loop structure, an A-U rich region preceding the initiation codon, and a region of homology to 16S rRNA.Key words: site-directed mutagenesis, stem-loop formation, fusion protein, translational initiation, translational enhancer.
Detection ofLawsonia intracellularisin faeces of swine from the main producing regions in Brazil
Authors: Chiriboga Adriana E.C. Nascimento , Guimarães Walter V , Vanetti Maria Cristina D. , Araújo Elza F
Published: April 2011

Swine proliferative enteropathy is an enteric disease caused by Lawsonia intracellularis which affects animals between 6 and 20 weeks of age, causing diarrhea, anorexia, and poor growth. The presence of L. intracellularis was evaluated in the faecal samples of 636 swine from 75 randomly chosen herds in the main swine-producing regions of Brazil. The pathogen was detected by the polymerase chain reaction method (PCR) using L. intracellularis specific primers. A 319-bp DNA fragment specific for L. intracellularis was produced on amplification of DNA from the faeces of pigs with proliferative enteropathy. Equal amounts of DNA extracted from the faeces of animals from the same herd were pooled together and, once L. intracellularis was detected, the faecal material of each animal was analyzed separately. The incidence of L. intracellularis was 33.4% in the state of Santa Catarina, 29.4% in Paraná, 26.3% in Minas Gerais, 16.7% in Mato Grosso, and 7.1% in São Paulo. The presence of the pathogenic agent was detected in samples from 15 farms, representing a total incidence of 20%. Although 46 animals (7.2%) were shown to be infected, 11% did not present any symptoms of swine proliferative enteropathy. The use of PCR allowed the detection of L. intracellularis in swine farms and the evaluation of the incidence of proliferative enteropathy in different regions of Brazil.Key words: proliferative enteropathy, diagnosis, Lawsonia intracellularis, PCR, incidence.
Temperature and water potential effects on growth and pathogenicity of Rhizoctonia solani AG-11 to lupin
Authors: Kumar S , Sivasithamparam K , Gill J S , Sweetingham M W
Published: April 2011

Rhizoctonia solani anastomosis group (AG) 11 causes serious damping-off and hypocotyl rot of lupins (Lupinus angustifolius L.) and is wide-spread in the northern grain-belt of Western Australia. We compared growth of AG-11 to AG-8, which causes bare-patch of grain crops including lupin. AG-11 grew significantly faster than AG-8 on potato dextrose agar (PDA) at several temperatures (10, 15, 20, 25, or 30°C) and also grew best within the pH range of 4-7. Growth of AG-8 was best at pH 7. There was no difference in the linear growth in soil of both AGs at 10°C, but AG-11 grew at a significantly faster rate at 20°C. Reduction in growth of AG-11 on osmotically adjusted PDA at temperatures between 10 and 30°C was more pronounced than that of AG-8. AG-11 caused very little lupin pre-emergence damping-off and hypocotyl rot at 10°C, and most severe hypocotyl rot was recorded at 20 and 25°C. Severity of hypocotyl rot caused by AG-11 at soil water potentials of -0.1, -0.07, and -0.05 MPa was higher than at -0.03 MPa. It appears that AG-11 is well suited to the environmental conditions of the relatively small area in Western Australia from which it is readily isolated.Key words: Rhizoctonia solani, anastomosis groups, osmotic potential, lupin.
Stability of mutations in aSphingomonasstrain
Authors: Bünz Patricia V , Buck Miriam , Hebenbrock Svantje , Fortnagel Peter
Published: April 2011

Sphingomonas sp. strain RW1 is able to mineralise dibenzofuran and dibenzo-p-dioxin. Three mutants were constructed that could not use dibenzofuran or dibenzo-p-dioxin as a carbon source but were able to grow with the succeeding metabolites of the pathway. Two different mutagenic agents were applied, a chemical treatment with 1-methyl-3-nitro-1-nitrosoguanidine, resulting in mutants RW1-N6 and RW1-N7, and a biological insertion mutagenesis with the mini-Tn5 transposon pBSL118, resulting in mutant RW1-M3. Southern blot analysis and PCR experiments confirmed a single insertion of the mini-Tn5 into one of the genes coding for the oxygenase component of the dibenzofuran 4,4a-dioxygenase system. The genetic stability of these mutants was examined after growth with complex medium under nonselective conditions. All three mutants failed to revert to wild-type metabolic functions.Key words: Sphingomonas, mutation, stability, mini-Tn5, 1-methyl-3-nitro-1-nitrosoguanidine.
Metal binding by Pseudomonas aeruginosa PAO1 is influenced by growth of the cells as a biofilm
Authors: Langley S , Beveridge T J
Published: April 2011

The metal-binding properties of Pseudomonas aeruginosa PAO1 biofilms were investigated using four metals (Cu, Fe, Au, and La). All but one of the metals (i.e., Cu) were bound by the biofilms in amounts that were significantly greater than those bound by planktonically grown cells of the same strain. Lanthanum precipitation appeared to be limited to the base of the biofilms and was not promoted by a shift in lipopolysaccharide production by the cells.Key words: metal binding, biofilms, Gram-negative bacteria, bioremediation.
Characterization and overproduction of theEscherichia coliappAencoded bifunctional enzyme that exhibits both phytase and acid phosphatase activities
Authors: Golovan Serguei , Wang Guirong , Zhang Jun , Forsberg Cecil W
Published: April 2011

The appA gene that was previously shown to code for an acid phosphatase instead codes for a bifunctional enzyme exhibiting both acid phosphatase and phytase activities. The purified enzyme with a molecular mass of 44 708 Da was further separated by chromatofocusing into two isoforms of identical size with isoelectric points of 6.5 and 6.3. The isoforms had identical pH optima of 4.5 and were stable at pH values from 2 to 10. The temperature optimum for both phytase isoforms was 60°C. When heated at different pH values the enzyme showed the greatest thermal resistance at pH 3. The pH 6.5 isoform exhibited Kmand Vmaxvalues of 0.79 mM and 3165 U·mg-1of protein for phytase activity and 5.5 mM and 712 U·mg-1of protein for acid phosphatase, respectively. The pH 6.3 isoform exhibited slightly lower Kmand Vmaxvalues. The enzyme exhibited similar properties to the phytase purified by Greiner et al. (1993), except the specific activity of the enzyme was at least 3.5-fold less than that previously reported, and the N-terminal amino acid sequence was different. The Bradford assay, which was used by Greiner et al. (1993) for determination of enzyme concentration was, in our hands, underestimating protein concentration by a factor of 14. Phytase production using the T7 polymerase expression system was enhanced by selection of a mutant able to grow in a chemically defined medium with lactose as the carbon source and inducer. Using this strain in fed-batch fermentation, phytase production was increased to over 600 U·mL-1. The properties of the phytase including the low pH optimum, protease resistance, and high activity, demonstrates that the enzyme is a good candidate for industrial production as a feed enzyme.
Activation and fragmentation ofBacillus thuringiensisδ-endotoxin by high concentrations of proteolytic enzymes
Authors: Pang Anthony SD , Gringorten J Lawrence , Bai Cheng
Published: April 2011

Commercial enzymes and insect gut juice at various concentrations were used to digest Bacillus thuringiensis subsp. sotto Cry1Aa protoxin and examine the fragmentation pattern and effect on insecticidal activity. Trypsin at both high (5 mg/mL) and low (0.05 mg/mL) concentrations converted protoxin to toxin with no difference in insecticidal activity against Bombyx mori larvae. In both cases, the toxin protein had an apparent Mrof 58.4 kDa (SDS-PAGE). Active toxin of identical Mrwas also produced with low concentrations of Pronase and subtilisin, but at high concentration, it was degraded into two protease-resistant fragments of apparent Mr31.8 and 29.6 kDa, and exhibited no insecticidal activity. Sequencing data established the primary cleavage site to be in domain II, the receptor-binding region of the toxin, in an exposed loop between two beta-sheet strands. Fragmentation was not observed, however, when the digests were analyzed by native protein techniques, but rather the toxin molecule appeared to be intact. The amount of activated toxin produced by Choristoneura fumiferana gut juice was markedly reduced when the gut-juice concentration was increased from 1 to 50% and correlated with a loss in insecticidal activity. However, no lower Mrprotease-resistant fragments were evident in the SDS-PAGE of these digests.Key words: Bacillus thuringiensis endotoxin, Lepidoptera, proteolytic enzymes, insect gut juice, activation, digestion.
Sequencing as a tool in yeast molecular taxonomy
Authors: Valente P , Ramos J P , Leoncini O
Published: April 2011

The literature on sequencing as a tool for yeast molecular taxonomy is reviewed. Ribosomal DNA has been preferred for sequencing over other molecules such as mitochondrial DNA, and a large database is now available. rDNA consists of regions that evolve at different rates, allowing comparison of different levels of relationship among yeasts. Sequences of the 18S rDNA and the 25S rDNA have been largely used for yeast systematics and phylogeny, but the search for regions with increased resolving power has led to the study of the spacer regions of the rDNA. Few studies are concerned with signature sequences.Key words: yeast, molecular taxonomy, rDNA, sequencing.
Role of hsfA gene on host-specificity by Bradyrhizobium japonicum in a broad range of tropical legumes
Authors: Oh Hye-Sook , Chun Jong-Yoon , Lee Myung-Sok , Min Kyung-Hee , Lee Suk-Ha , Cheon Choong-Ill
Published: April 2011

Bradyrhizobium japonicum mutant strain NAD163, containing a 30-kb deletion mutant encompassing the hsfA gene, was inoculated onto a broad range of legume species to test host-specificity. Most legume species formed ineffective nodules except Vigna angularis var. Chibopat and Glycine max var. Pureunkong. A hsfA insertion mutant, BjjC211, gave similar results to strain NAD163, implying that many legume species require HsfA for host-specific nitrogen fixation. To determine whether other genes in the deleted region of NAD163 are also necessary, the hsfA gene was conjugally transferred into the NAD163 mutant. The transconjugant formed effective nodules on the host legume plants, which earlier had formed ineffective nodules with mutant NAD163. Thus, we conclude that the hsfA gene in the 30-kb region is the only factor responsible for host-specific nitrogen fixation in legume plants.Key words: host-specific nitrogen fixation, legume-Rhizobium symbiosis, hsfA gene, host-specificity.
Serogroups of the beer spoilage bacterium Megasphaera cerevisiae correlate with the molecular weight of the major EDTA-extractable surface protein
Authors: Ziola Barry , Gee Lori , Berg Nancy N , Lee Sun Y
Published: April 2011

Megasphaera cerevisiae is a Gram-negative obligate anaerobe that causes turbidity and off-flavour and aroma in beer. Seven isolates of M. cerevisiae were obtained worldwide, and their extractable surface antigens were focused upon to determine if there is more than one serogroup of this bacterium. Sodium dodecyl sulphate polyacrylamide gel electrophoresis of ethylenediaminetetraacetic acid (EDTA) bacterial extracts revealed a predominant protein with apparent molecular weights of 46 000, 45 000, and 43 000 for three, two, and two isolates, respectively. When mouse antiserum generated against any of the EDTA extracts was reacted with denatured bacterial proteins in immunoblots, all bacterial isolates exhibited extensive cross-reactivity involving three antigens, one being the major EDTA-extractable protein. In contrast, when the sera were tested for surface reactivity with intact bacteria, three cross-reactivity groups were observed, with the groups individually comprised of bacteria having the same size major EDTA-extractable surface protein. When BALB/c mice immunized with a bacterium from each of the three serogroups were used for monoclonal antibody (Mab) hybridoma production, bacterial surface-reactive Mabs were obtained whose reactivities parallel the three polyclonal antibody-defined serogroups. Through combining these surface-reactive Mabs, it will be possible to rapidly detect and identify beer contamination by M. cerevisiae belonging to any serogroup. Key words: beer spoilage bacteria, Megasphaera cerevisiae, monoclonal antibodies, surface proteins, serogroups.
Origin ofp-cresol in the anaerobic degradation of trinitrotoluene
Authors: Shen C F , Hawari J A , Ampleman G , Thiboutot S , Guiot S R
Published: April 2011

p-Cresol was repeatedly detected as a trace metabolite in anaerobic slurry reactors treating 2,4,6-trinitrotoluene (TNT)-contaminated soils. This study shows that p-cresol was not a metabolite of the anaerobic degradation of TNT, by using a combination of analytical techniques and13C-labelled TNT. Instead, p-cresol, an intermediate in the degradation pathway of some amino acids, was shown to be inhibited by TNT and its metabolites. The range and persistence of inhibition to p-cresol microbial degradation decreased with the level of amino-substitution of the derivatives. This explains why p-cresol accumulated within the TNT-treating anaerobic bioslurry, as it could not be further biodegraded in the presence of TNT. Key words: p-cresol, bioremediation, trinitrotoluene, inhibition, metabolites.
Inactivation of MS-2 phage and poliovirus in groundwater
Authors: Alvarez Maria E , Aguilar Miguel , Fountain Alexis , Gonzalez Neyda , Rascon Osvaldo , Saenz David
Published: April 2011

Since temperature affects the inactivation rate of viruses in natural water systems, the aim of this study was to determine if a temperature shift could influence the structural integrity of model viruses. When crude lysates of MS-2 phage were seeded into groundwater microcosms and incubated at 27°C, complete virus inactivation took place in eight days. The temperature was then shifted to 4°C. Three days after the temperature shift, a two-log increase in virus titer (reactivation) occurred. However, when purified MS-2 lysates were added to groundwater microcosms, no reactivation was obtained. No reactivation of poliovirus took place when similar microcosm experiments were done. The sedimentation coefficients of MS-2 shifted from 80S to 58S, 48S, 37S, 32S, and 18S as inactivation proceeded in groundwater and distilled water controls. Similarly, the sedimentation coefficients of polioviruses changed from 156S to 142S, 135S, 117S, 105S, 95S, and 80 S as inactivation took place. There was no correlation between % virus inactivation and % decrease in virions with intact sedimentation coefficients, as reported earlier for poliovirus inactivated by chlorine. The results presented support our hypothesis that virus inactivation proceeds gradually, involving the rearrangement and (or) loss of capsomere components that may eventually lead to the ejection of nucleic acids. The intermediate particles generated as inactivation proceeds may be in a reversibly inactivated state, and may revert back to a fully infectious state when chemical components stabilize the virus particle.Key words: poliovirus, MS-2, groundwater, virus inactivation, virus reactivation.
Molecular analysis and development of 16S rRNA oligonucleotide probes to characterize a diclofop-methyl-degrading biofilm consortium
Authors: Laramée Louise , Lawrence John R , Greer Charles W
Published: April 2011

Genomic DNA from nine individual bacteria, isolated from a diclofop-methyl-degrading biofilm consortium, was extracted for genetic characterization. The degradation of diclofop-methyl produces metabolites that are known intermediates or substrates for bacteria that degrade a variety of chlorinated aromatic compounds. Accordingly, oligonucleotide primers were designed from specific catabolic genes for chlorinated organic degradation pathways, and tested by PCR to determine if these genes are involved in diclofop-methyl degradation. DNA homology between the PCR products and the known catabolic genes investigated by Southern hybridization analysis and by sequencing, suggested that novel catabolic genes are functioning in the isolates. Specific fluorescent oligonucleotides were designed for two of the isolates, following 16S rDNA sequencing and identification of each of the isolates. These probes were successfully used for fluorescent in situ hybridization (FISH) studies of the two isolates in the biofilm consortium. Key words: consortium, catabolic gene, diclofop-methyl, 16S rDNA, FISH, SCLM.
Purification, partial characterization, and reactivity with aromatic compounds of two laccases fromMarasmius quercophilusstrain 17
Authors: Farnet A M , Criquet S , Tagger S , Gil G , Petit J Le
Published: April 2011

Two isozymes of laccase were obtained from an induced liquid culture of Marasmius quercophilus with p-hydroxybenzoic acid as the inducer. Both the constitutive and the induced isozyme have a molecular mass of 60 kDa as determined by polyacrylamide gel electrophoresis. Using isoelectric focusing, we found three isozymes with the constitutive enzyme (pI 4, 4.2, 4.4) and four of the induced form (pI 4.75, 4.85, 4.95, 5.1). We observed certain differences between these two isozymes; the specific activity of the induced isozyme was twice as high, and two optimum pH levels (5 and 6) were observed with the induced isozyme (only one, pH 5, for the constitutive isozyme). However, both of these enzymes have the same thermal stability and the same temperature for their highest activity (80°C). Furthermore, the reactivity of both these enzymes with aromatic compounds was similar. The use of mediators extended the oxidized substrate range of the laccases studied. Various products of degradation were observed, depending on the mediator used. When laccase was used alone, the decrease of the signal corresponding to the aromatic cycle, without any formations of other peaks at different wavelengths, suggested polymerisation of aromatic compounds.Key words: laccase, Marasmius quercophilus, mediator, phenol degradation.
Net primary productivity following forest fire for Canadian ecoregions
Authors: Amiro B D , Chen J M , Liu Jinjun
Published: April 2011

Recent modelling results indicate that forest fires and other disturbances determine the magnitude of the Canadian forest carbon balance. The regeneration of post-fire vegetation is key to the recovery of net primary productivity (NPP) following fire. We geographically co-registered pixels classed using the Boreal Ecosystem Productivity Simulator, a process-based model with AVHRR (advanced very-high resolution radiometer) satellite estimates of leaf-area index and land cover type, with polygons from a recent database of large Canadian fires. NPP development with time since fire was derived for the first 15 years following the disturbance in the boreal and taiga ecozones. About 7 × 106 ha were analysed for over 500 fires occurring between 1980 and 1994. NPP increases linearly through this period, at rates that depend on ecoregion. A longer data set for the Boreal Plains ecozone of Alberta shows that NPP levels off at about 20-30 years and remains constant for 60 years. The NPP trajectories can be used as spatial averages to support models of forest carbon balance and succession through the most fire-prone regions of Canada.
Stability and density management in Douglas-fir plantations
Authors: Wilson J S , Oliver C D
Published: April 2011

Limited tree size variation in coastal Oregon, Washington, and British Columbia Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantations makes them susceptible to developing high height to diameter ratios (H/D same units) in the dominant trees. The H/D of a tree is a relative measure of stability under wind and snow loads. Experimental plot data from three large studies was used to evaluate the impact of initial planting densities and thinning on plantation H/D values. The H/D predictions from the experimental plot data match spacing trial results closely but are substantially different than distance-independent growth model predictions. The results suggest that plantation H/D values can be lowered and stability promoted through reduced planting densities or early thinning; however, later thinnings may not be effective in promoting stability, since they do not appear to lower H/D values. Higher initial planting densities shorten the time period during which thinning can be expected to effectively lower future H/D values. Time-sensitive thinning requirements in dense plantations make their management inflexible. The flexibility with which a stand can be managed describes the rigidity of intervention requirements and (or) potential range of stand development pathways.
The mating system and genic diversity in Martínez spruce, an extremely rare endemic of México's Sierra Madre Oriental: an example of facultative selfing and survival in interglacial refugia
Authors: Ledig F Thomas , Bermejo-Velázquez Basilio , Hodgskiss Paul D , Johnson David R , Flores-López Celestino , Jacob-Cervantes Virginia
Published: April 2011

Martínez spruce (Picea martínezii T.F. Patterson) is a conifer currently passing through a bottleneck, reduced to a few relict populations totaling less than 800 trees. We used isozyme markers to analyze the mating system and survey the level of genic diversity in two populations. The mating system was characterized by a high frequency of selfing. The multilocus outcrossing rates (tm) and 95% confidence intervals were only 0.399 (0.197 < tm< 0.601) for the smallest population and 0.589 (0.475 < tm< 0.703) or 0.685 (0.465 < tm< 0.905), depending on year, for the largest. These are among the lowest rates of outcrossing observed in conifers. The fixation indices for the two populations were -0.058 and 0.121, less than expected for such high levels of selfing. Expected heterozygosity, unbiased He, based on 22 loci in 13 enzyme systems, was 0.121 and 0.101 in the two populations. The proportion of the total genic diversity between populations, FST, was 2.4%. Nm, the number of migrants per generation, was about 1.00 or 10.17, depending on the method of estimation. The time since the two populations were isolated was estimated from Nei's genetic distance as only 150 to 15 000 years, which is consistent with a hypothesis of population collapse during late Pleistocene or Holocene warming. We discuss the implications for conservation.
Factors associated with the decline disease of sugar maple on the Allegheny Plateau
Authors: Horsley Stephen B , Long Robert P , Bailey Scott W , Hallett Richard A , Hall Thomas J
Published: April 2011

Mortality of sugar maple (Acer saccharum Marsh.) has reached unusually high levels across northern Pennsylvania since the early to mid-1980s. We evaluated the influence of glaciation, topographic position, foliage chemistry, defoliation history, and stand characteristics (species composition, structure, density) on the health of sugar maple in 43 stands at 19 sites on the northern Allegheny Plateau. Using percent dead sugar maple basal area as the measure of health, we found that all moderately to severely declining stands were on unglaciated summits, shoulders, or upper backslopes. Stands on glaciated sites and unglaciated lower topographic positions were not declining. The most important factors associated with sugar maple health were foliar levels of Mg and Mn and defoliation history. The lowest foliar Mg, highest foliar Mn, and highest number and severity of insect defoliations were associated with unglaciated summits, shoulders, and upper backslopes. Declining stands had less than ~700 mg·kg-1 Mg and two or more moderate to severe defoliations in the past 10 years; both conditions were associated with moderately to severely declining stands. The decline disease of sugar maple seems to result from an interaction between Mg (and perhaps Mn) nutrition and stress caused by defoliation.
Nutrient concentrations and nitrogen mineralization in forest floors of single species conifer plantations in coastal British Columbia
Authors: Prescott C E , Vesterdal L , Pratt J , Venner K H , Montigny L M de , Trofymow J A
Published: April 2011

We examined the extent to which nutrient concentrations and C and N mineralization rates in forests floors under different tree species are predictable from the chemistry of foliar litter and its rate of decomposition. We studied replicated single species plantations of western redcedar (Thuja plicata Donn ex D. Don), western hemlock (Tsuga heterophylla (Raf.) Sarg.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and Sitka spruce (Picea sitchensis (Bong.) Carr.) at four locations. Nutrient concentrations in forest floors correlated poorly with litter nutrient concentrations; the only significant relationships were for Ca and K. Nitrogen mineralization correlated weakly with forest floor C/N ratio, and differed more among sites than among species. None of the litter chemistry parameters were related to net N mineralization rates. Decomposition was fastest in hemlock litter, intermediate in Douglas-fir litter and lowest in cedar litter. Litter also decomposed more rapidly on hemlock forest floors than on cedar forest floors. Rates of N mineralization in the forest floors were not related to rates of decomposition of foliar litter. Differences among sites in N mineralization rates were related to the understory vegetation composition, particularly the amount of the ericaceous shrub salal, which in turn was related to slope position. These site factors appeared to override the effect of tree species on rates of N mineralization.
Detection of quantitative trait loci for wood strength inCryptomeria japonica
Authors: Kuramoto Noritsugu , Kondo Teiji , Fujisawa Yoshitake , Nakata Ryogo , Hayashi Eiji , Goto Yoko
Published: April 2011

Cryptomeria japonica D. Don (sugi) is one of the most important forest tree species in Japan. The progeny of a cross between the cultivars Iwao-sugi and Boka-sugi were analyzed using RAPD markers, with the pseudo-test-cross strategy, to construct linkage maps of the parental cultivars. A total of 355 segregating loci were detected among 72 offspring: 200 and 155 markers being distributed in Iwao-sugi and Boka-sugi, respectively. In Iwao-sugi, 119 markers with confirmed map positions were assigned to 21 linkage groups covering 1756.4 cM. In Boka-sugi, 84 markers with confirmed map positions were assigned to 14 linkage groups covering 1111.9 cM. The framework map distance in Iwao-sugi and Boka-sugi provides about 62 and 40% coverage, respectively, of the total genome, estimated to be approximately 2800 cM in length. Using genetic linkage maps constructed in this study, 15 QTLs were detected that are associated with the modulus of elasticity (MOE), an important indicator of wood strength. The QTLs for MOE explained about 45% of its total phenotypic variance. Some QTLs associated with different phenotypic traits were located on the same linkage groups. Some of the QTLs for MOE measured by two different methods (the hanging method and the tapping method) were located independently on the different linkage groups.
Dendroecological detection of spruce bark beetle outbreaks in northwestern Colorado
Authors: Eisenhart Karen S , Veblen Thomas T
Published: April 2011

Episodic outbreaks of Dendroctonus rufipennis (Kirby), the spruce bark beetle, have greatly influenced the structure of subalpine forests in northern Colorado. During the 1940s, much of the subalpine zone of northwestern Colorado was severely affected by beetle outbreak; also, tree-ring and photographic evidence suggest that large-scale outbreaks occurred in the 19th century. The present study focused on tree-ring methods to examine the regional extent and synchrony of pre-20th-century beetle outbreaks in northwestern Colorado. Results from examination of both live and dead Engelmann spruce (Picea engelmannii Parry ex Engelm.) tree rings in nine stands were compared with results of previous tree-ring studies in the same region. Evidence of past canopy disturbance included episodes of tree mortality in conjunction with sustained increases in radial growth rates. We identified regional outbreaks of spruce beetle by synchronous and sustained growth release in trees from disjunct stands. These new tree-ring records, along with previously published records, indicate that severe and widespread canopy disturbances, probably spruce beetle outbreaks, affected northwestern Colorado in 1716-1750, 1827-1845, 1860-1870, and 1940-1960. These results support earlier findings that large-scale outbreaks of spruce beetle have long been an important component of the dynamics of subalpine forests in Colorado.
Artificial inoculation with Armillaria ostoyae in established conifers stressed by defoliation, planting, and thinning in Newfoundland
Authors: Piercey-Normore M D , Bérubé J A
Published: April 2011

Armillaria ostoyae (Romagnesi) Herink causes root disease in conifers of the northern hemisphere. Pathogenicity tests of established conifer trees with A. ostoyae, has never been done in the boreal forest. Seven forest plots were selected in Newfoundland; a black spruce (Picea mariana (Mill.) BSP) plantation, a naturally regenerated black spruce stand, a balsam fir (Abies balsamea (L.) Mill.) stand with hemlock looper (Lambdina fiscellaria (Guen.)) defoliation, two balsam woolly adelgid (Adelges piceae (Ratz.)) infested balsam fir stands (thinned and unthinned sites), a balsam fir sawfly (Neodiprion abietis Harris) defoliated balsam fir stand, and an artificially defoliated black spruce stand. Roots of fir and spruce trees were inoculated with two isolates of A. ostoyae and re-examined after 2 years. The purpose of this study was to compare differences in root infection within plots for different types of host stress to examine the response of trees to controlled inoculations of A. ostoyae. There was a statistically significant difference in number of infected roots between the two isolates used as inoculum. There was significantly more root response with severity of infection within all sites except both adelgid plots. A marginally significant relationship between tree health and root infection was present in the balsam fir sawfly plot. There was a significantly larger number of infected roots associated with rhizomorphs in the naturally regenerated black spruce stand and the artificially defoliated balsam fir stand. These results suggest that stress prediposes the host tree to root infection by A. ostoyae.
Comparative fate of glyphosate and triclopyr herbicides in the forest floor and mineral soil of an Acadian forest regeneration site
Authors: Thompson Dean G , Pitt Douglas G , Buscarini Teresa M , Staznik Bozena , Thomas David R
Published: April 2011

Following applications of three different salt formulations of glyphosate (Vision®, Touchdown®, and Mon14420) and an ester formulation of triclopyr (Release®) to an Acadian forest regeneration site in New Brunswick, Canada, the fate and persistence of herbicide residues in the forest floor and underlying mineral soil were investigated. Within 14 days of treatment, maximal residue levels (average 8.3 µg·g dry mass1) were observed in the forest floor matrix following application of the glyphosate formulations, with higher values (45.7 µg·g dry mass1) observed for triclopyr. Residue maxima in the underlying mineral soil were, on average, 5.7-fold lower than those in the forest floor. In both matrices, glyphosate residues declined exponentially with time, irrespective of the formulation applied. Among the glyphosate treatments no significant differences (p = 0.16, p = 0.97, for forest floor and mineral soil respectively) were observed in the estimated times to 50% dissipation (DT50). Overall, average DT50 values for glyphosate were estimated as 12 ± 2 and 10 ± 3 days for the forest floor matrix and mineral soil, respectively. Triclopyr residues, particularly in the forest floor, were characterized by a series of transient increases, possibly reflecting temporally varying inputs from dew, rainwash, or litter fall from surrounding treated vegetation. Triclopyr residues also dissipated with time, with approximate DT50 values ranging from 39 to 69 days in the forest floor and mineral soil, respectively.
Leaf area index of an old-growth Douglas-fir forest estimated from direct structural measurements in the canopy
Authors: Thomas Sean C , Winner William E
Published: April 2011

Leaf area index (LAI) in old-growth Douglas-fir (Pseudotsuga menziesii var menziesii (Mirb.) Franco) forests exceeds that of any other forest ecosystem by some estimates; however, LAI determinations in coniferous forests have generally been indirect, involving extrapolations of patterns observed in younger stands. Aided by a 75-m construction crane for canopy access, we used a vertical line-intercept method to estimate LAI for a [Formula: see text]450-year-old Douglas-fir - western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest in southwestern Washington state. LAI was calculated as the product of foliage contact frequency and an "extinction coefficient" accounting for foliage angular distribution, geometry, and the ratio of "interceptable" to total leaf area. LAI estimates were 9.3 ± 2.1 (estimate ± 95% confidence interval), 8.5 ± 2.2, and 8.2 ± 1.8 in 1997, 1998, and 1999, respectively, or 8.6 ± 1.1 pooled across years. Understory vegetation, including foliage of woody stems <5 cm diameter, represented 20% of this total. Sample points in which Douglas-fir was dominant had a higher total LAI than points dominated by western hemlock, including a higher LAI of understory vegetation. Our results do not support the contention that old-growth Douglas-fir - western hemlock forests maintain an appreciably higher LAI than do other forest ecosystems. Moreover, LAI in very old stands may decline as western hemlock replaces Douglas-fir through the course of succession.
Ecological interpretation of tree-ring width and intraannual density fluctuations inPinus sylvestrison dry sites in the central Alps and Siberia
Authors: Rigling Andreas , Waldner Philipp O , Forster Theodor , Bräker Otto U , Pouttu Antti
Published: April 2011

The radial growth of Pinus sylvestris L. from nine sites at the semiarid lower forest border of the central Alps (Switzerland) and central Siberia (Russia) has been investigated using dendroecological methods. Tree growth differed according to soil substrate, with trees on dune sites showing lower mean ring widths, lower mean sensitivities, and higher autocorrelation. The relationships between climate and tree-ring width were studied using response function analysis. Independent of the climatic zone and the soil substrate, precipitation just before and at the beginning of the growing season is positively correlated with radial growth. The climatic response of dune sites is low, possibly because of the poor water-holding capacity and the high permeability of the sandy soils. Intraannual density fluctuations (IADFs) were observed at all the sites. Most IADFs were found in latewood. On dunes, fewer cores contain IADFs, and their frequency is lower. All stands showed significant relationships between IADF frequency and tree-ring width (positive) and ring age (negative). For Swiss sites, moist-cool conditions in the middle of the growing season are demonstrated as the triggering factor for IADFs. For the Russian sites, inadequate climatic data made it impossible to demonstrate any climate dependence of IADFs.
A quantitative framework for breeding and conservation of forest tree genetic resources in British Columbia
Authors: Yanchuk Alvin D
Published: April 2011

Over the last decade, forest tree breeders have become aware of the need for gene conservation, but have struggled with methods that would meaningfully integrate breeding and conservation populations. Gene Namkoong has provided the most guidance in this area by defining the role of in- and ex-situ populations in forest tree gene resource management and, particularly, the need for this to be dynamic in time and space. However, once conservation plans for individual species in British Columbia were considered, it became clear that more quantitative structure was needed to provide a framework for attaining practical management objectives. This paper attempts to provide such a framework and show how breeding and conservation populations can be integrated into a continuum of genetic resources. First, capturing only one copy of an allele is likely not satisfactory to meet conservation objectives, and sampling targets should be set higher (e.g., 20) so as to avoid potential problems of inbreeding at later stages in the program. Second, there seems to be a large problem with conserving very low frequency alleles that are recessive, but this occurs in nature as well. Third, in situ populations should be large enough and in a state to persist on their own over several generations, so the more recent effective population size numbers proposed by Lynch (1996) (i.e., ~1000) need to be considered. Fourth, while breeding populations of moderate size (~80) will contain adequate amounts of quantitative genetic variation, they will also contain 20 copies of dominant alleles at frequencies of ~0.20 or higher. Fifth, maintaining and rejuvenating strategic ex-situ test populations now seems to be the only way to conserve low- to mid-frequency alleles that will (i) be reduced in progressive breeding populations by drift and, (ii) over time, not be in desirable genetic backgrounds in in situ populations. Sixth, any reliance on locating mutants in production populations seems generally remote and cannot be relied upon except in a very few situations, although mutation will be important in breeding and in reserves in situ.
An evaluation of alternate remote sensing products for forest inventory, monitoring, and mapping of Douglas-fir forests in western Oregon
Authors: Lefsky M A , Cohen W B , Spies T A
Published: April 2011

This research evaluates the utility of several remote sensing data types for the purpose of mapping forest structure and related attributes at a regional scale. Several sensors were evaluated, including (i) single date Landsat Thematic Mapper (TM); (ii) multitemporal Landsat TM; (iii) Airborne Data Acquisition and Registration (ADAR), a sensor with high spatial resolution; (iv) Airborne Visible-Infrared Imaging Spectrometer (AVIRIS), a sensor with high spectral resolution; and (v) Scanning Lidar Imager Of Canopies By Echo Recovery (SLICER), a lidar sensor that directly measures the height and canopy structure of forest vegetation. To evaluate the ability of each of the sensors to predict stand structure attributes, we assembled a data set consisting of 92 field plots within the Willamette National Forest in the vicinity of the H.J. Andrews Experimental Forest. Stand structure attributes included age, basal area, aboveground biomass, mean diameter at breast height (DBH) of dominant and codominant stems, mean and standard deviation of the DBH of all stems, maximum height, and the density of stems with DBH greater than 100 cm. SLICER performed better than any other remote sensing system in its predictions of forest structural attributes. The performance of the imaging sensors (TM, multitemporal TM, ADAR, and AVIRIS) varied with respect to which forest structural variables were being examined. For one group of variables there was little difference in the ability of the these sensors to predict forest structural attributes. For the remaining variables, we found that multitemporal TM was as or more effective than either ADAR or AVIRIS. These results indicate that multitemporal TM should be investigated as an alternative to either hyperspectral or hyperspatial sensors, which are more expensive and more difficult to process than multitemporal Landsat TM.
History of a pine false webworm (Hymenoptera: Pamphiliidae) outbreak in northern New York
Authors: Asaro Christopher , Allen Douglas C
Published: April 2011

A sustained outbreak of pine false webworm, Acantholyda erythrocephala (L.) (Hymenoptera: Pamphiliidae), in northern New York is unprecedented in its extent and duration. White pine, Pinus strobus L., is the preferred host in this region. What began as a 30-ha infestation of this introduced sawfly in 1981 affected 5440 ha of white pine distributed throughout 231 000 ha in St. Lawrence and Franklin counties by 1995. Occurrence of A. erythrocephala in the United States has been documented in eight northeastern and one north-central state (Connecticutt, Massachusetts, Maine, New Hampshire, New Jersey, New York, Pennsylvania, Vermont, and Wisconsin) and three Canadian provinces (Alberta, Newfoundland, and Ontario). Possible explanations for the occurrence and tenure of the current outbreak in New York are discussed.
Effects of pine shelterwoods on microclimate and frost damage to Norway spruce seedlings
Authors: Langvall O , Örlander G
Published: April 2011

Cuttings of Norway spruce, Picea abies (L.) Karst., were planted under two Scots pine, Pinus sylvestris L., shelterwoods with a density gradient varying from fully stocked forest to clearcuts. This provided a range of near-ground temperature and radiation regimes. The microclimate was monitored near each cutting, using an automated mobile system. The factors monitored were air temperature, global radiation, and net radiation. Frost damage to the spruce cuttings was assessed by two methods. First, the percentage of actively growing shoots with visible damage was determined. Second, the maximum photochemical efficiency of photosystem II (Fv/Fm) in 1-year-old and current-year needles was estimated from measurements of chlorophyll a fluorescence. A frost event in May 1990 was analysed using the partial least squares in latent variables (PLS) method of multivariate statistical analysis. Different microclimatic variables were used as predictors. Visible damage to actively growing shoots and the Fv/Fmratio in 1-year-old needles were used as response variables. The predictors were used to produce a separate PLS model for each response variable. Nocturnal net radiation during the frost event, and both the net and global radiation the day after, were found to be important for explaining the visible damage and the Fv/Fmratios. In both the PLS analyses, the modelling power of these three variables was ranked among the highest of all microclimatic factors tested. The accumulated air temperature below 0°C, the duration of the frost, and the minimum air temperature near the ground (at 0.4 m) also had high predictive power. Thus, both higher nocturnal air temperature near the ground and shading the day after the frost event were important factors explaining the reduction of visible damage and low-temperature induced photoinhibition. Leaving a dense shelterwood moderates both the nocturnal air temperature and the radiation regime and, therefore, is recommended on sites where early summer frosts are expected.
The influence of clear-cut logging and residual leave material on small mammal populations in aspen-dominated boreal mixedwoods
Authors: Moses Richard A , Boutin Stan
Published: April 2011

We investigated responses of populations of common small mammals to variation in the amount of standing trees and residual woody material retained during logging in aspen-dominated, boreal mixedwood forest in north-central Alberta. Experimentally manipulated levels of residual material, with two replicates per level, were (i) "zero residual": clear-cut and no woody debris (tree tops and limbs); (ii) "low residual": clear-cut and woody debris; (iii) "moderate residual": 10% basal area standing live tree retention, and woody debris; and (iv) "uncut": 100% uncut. Patterns of small mammal abundance were similar throughout the study on uncut and moderate-residual grids, where southern red-backed voles (Clethrionomys gapperi Vigors) and deer mice (Peromyscus maniculatus Wagner) were numerically dominant. In contrast, C. gapperi were virtually absent from the low- and zero-residual grids during the breeding season following logging and occurred at low numbers in the following 2 years. Peromyscus maniculatus were common on low- and zero-residual grids in all years. We found no evidence that rates of reproductive activity and (or) survival in C. gapperi and P. maniculatus were affected by logging treatments. Meadow voles (Microtus pennsylvanicus Ord) were uncommon on uncut and moderate-residual grids throughout the study but were abundant on both low-residual grids and one zero-residual grid, particularly in the second year following logging, when they exhibited irruptive dynamics in midsummer. In sum, relative abundances of common small mammals were most affected by intensive (clear-cut) logging, and our results suggest that the experimental retention of at least 10% basal area on cutovers may reduce some of these effects.
Breeding objectives for three silvicultural regimes of radiata pine
Authors: Apiolaza Luis A , Garrick Dorian J
Published: April 2011

A generic vertically integrated firm, comprising a production forest, a sawmill, and a pulp mill was modelled under three silvicultural regimes: direct to pulp, intermediate (includes production thinning), and intensive (includes production thinnings and pruning). The harvest age traits included in the breeding objective were total volume (m3/ha) and average wood density (kg/m3). Economic values for each trait were calculated as the difference in discounted profit for a unit marginal increase of volume or density, and expressed as relative weights to facilitate comparisons between the objectives. The methodology was applied to a Chilean case study using representative economic and production circumstances. The breeding objectives so derived were 1vol + 2.4den for pulp, 1vol + 1.1den for intermediate, and 1vol + 1.2den for the intensive regime, where vol and den are the breeding values for volume and density, respectively. The firm was profitable under all regimes. Genetic correlations between the objectives for each regime were higher than 0.9, indicating that a single breeding strategy with objective 1vol + 1.5den could be adopted, with almost no loss of genetic gain relative to selecting for a particular silvicultural regime.