bluuebunny/crossref_metadata_2025 huggingface dataset:
Silencing Onion Lachrymatory Factor Synthase Causes a Significant Change in the Sulfur Secondary Metabolite Profile
Authors: Eady Colin C. , Kamoi Takahiro , Kato Masahiro , Porter Noel G. , Davis Sheree , Shaw Martin , Kamoi Akiko , Imai Shinsuke
Published: June 2008

Through a single genetic transformation in onion (Allium cepa), a crop recalcitrant to genetic transformation, we suppressed the lachrymatory factor synthase gene using RNA interference silencing in six plants. This reduced lachrymatory synthase activity by up to 1,544-fold, so that when wounded the onions produced significantly reduced levels of tear-inducing lachrymatory factor. We then confirmed, through a novel colorimetric assay, that this silencing had shifted the trans-S-1-propenyl-l-cysteine sulfoxide breakdown pathway so that more 1-propenyl sulfenic acid was converted into di-1-propenyl thiosulfinate. A consequence of this raised thiosulfinate level was a marked increase in the downstream production of a nonenzymatically produced zwiebelane isomer and other volatile sulfur compounds, di-1-propenyl disulfide and 2-mercapto-3,4-dimethyl-2,3-dihydrothiophene, which had previously been reported in trace amounts or had not been detected in onion. The consequences of this dramatic simultaneous down- and up-regulation of secondary sulfur products on the health and flavor attributes of the onion are discussed.
Imaging of the Yellow Cameleon 3.6 Indicator Reveals That Elevations in Cytosolic Ca2+ Follow Oscillating Increases in Growth in Root Hairs of Arabidopsis
Authors: Monshausen Gabriele B. , Messerli Mark A. , Gilroy Simon
Published: June 2008

In tip-growing cells, the tip-high Ca2+ gradient is thought to regulate the activity of components of the growth machinery, including the cytoskeleton, Ca2+-dependent regulatory proteins, and the secretory apparatus. In pollen tubes, both the Ca2+ gradient and cell elongation show oscillatory behavior, reinforcing the link between the two. We report that in growing root hairs of Arabidopsis (Arabidopsis thaliana), an oscillating tip-focused Ca2+ gradient can be resolved through imaging of a cytosolically expressed Yellow Cameleon 3.6 fluorescence resonance energy transfer-based Ca2+ sensor. Both elongation of the root hairs and the associated tip-focused Ca2+ gradient show a similar dynamic character, oscillating with a frequency of 2 to 4 min−1. Cross-correlation analysis indicates that the Ca2+ oscillations lag the growth oscillations by 5.3 ± 0.3 s. However, growth never completely stops, even during the slow cycle of an oscillation, and the concomitant tip Ca2+ level is always slightly elevated compared with the resting Ca2+ concentration along the distal shaft, behind the growing tip. Artificially increasing Ca2+ using the Ca2+ ionophore A23187 leads to immediate cessation of elongation and thickening of the apical cell wall. In contrast, dissipating the Ca2+ gradient using either the Ca2+ channel blocker La3+ or the Ca2+ chelator EGTA is accompanied by an increase in the rate of cell expansion and eventual bursting of the root hair tip. These observations are consistent with a model in which the maximal oscillatory increase in cytosolic Ca2+ is triggered by cell expansion associated with tip growth and plays a role in the subsequent restriction of growth.
Bridging the Gap between Plant and Mammalian Polyamine Catabolism: A Novel Peroxisomal Polyamine Oxidase Responsible for a Full Back-Conversion Pathway in Arabidopsis
Authors: Moschou Panagiotis N. , Sanmartin Maite , Andriopoulou Athina H. , Rojo Enrique , Sanchez-Serrano Jose J. , Roubelakis-Angelakis Kalliopi A.
Published: June 2008

In contrast to animals, where polyamine (PA) catabolism efficiently converts spermine (Spm) to putrescine (Put), plants have been considered to possess a PA catabolic pathway producing 1,3-diaminopropane, Δ  1-pyrroline, the corresponding aldehyde, and hydrogen peroxide but unable to back-convert Spm to Put. Arabidopsis (Arabidopsis thaliana) genome contains at least five putative PA oxidase (PAO) members with yet-unknown localization and physiological role(s). AtPAO1 was recently identified as an enzyme similar to the mammalian Spm oxidase, which converts Spm to spermidine (Spd). In this work, we have performed in silico analysis of the five Arabidopsis genes and have identified PAO3 (AtPAO3) as a nontypical PAO, in terms of homology, compared to other known PAOs. We have expressed the gene AtPAO3 and have purified a protein corresponding to it using the inducible heterologous expression system of Escherichia coli. AtPAO3 catalyzed the sequential conversion/oxidation of Spm to Spd, and of Spd to Put, thus exhibiting functional homology to the mammalian PAOs. The best substrate for this pathway was Spd, whereas the N  1-acetyl-derivatives of Spm and Spd were oxidized less efficiently. On the other hand, no activity was detected when diamines (agmatine, cadaverine, and Put) were used as substrates. Moreover, although AtPAO3 does not exhibit significant similarity to the other known PAOs, it is efficiently inhibited by guazatine, a potent PAO inhibitor. AtPAO3 contains a peroxisomal targeting motif at the C terminus, and it targets green fluorescence protein to peroxisomes when fused at the N terminus but not at the C terminus. These results reveal that AtPAO3 is a peroxisomal protein and that the C terminus of the protein contains the sorting information. The overall data reinforce the view that plants and mammals possess a similar PA oxidation system, concerning both the subcellular localization and the mode of its action.
The polybasic region of Rho GTPases defines the cleavage by Yersinia enterocolitica outer protein T (YopT)
Authors: Fueller Florian , Schmidt Gudula
Published: June 2008

Pathogenic Yersinia strains evade the innate immune responses of the host by producing effector proteins (Yersinia outer proteins [Yops]), which are directly injected into mammalian cells by a type III secretion system (TTSS). One of these effector proteins (YopT) disrupts the actin cytoskeleton of the host cell resulting in cell rounding. YopT is a cysteine protease that cleaves Rho proteins directly upstream of the post‐translationally modified cysteine. Thereby, it releases the GTPases from the membrane leading to inactivation. Small GTPases are modified by isoprenylation of the cysteine of the CAAX box, cleavage of the –AAX tripeptide, and methylation of the cysteine. We have shown that isoprenylation and the endoproteolytic cleavage of the tripeptide of Rho GTPases are essential for YopT‐induced cleavage, whereas carboxyl methylation is not required. In the present study, we post‐translationally modified RhoA, Rac, Cdc42, and several mutants in vitro and characterized the YopT‐induced cleavage with recombinant YopT. We show that farnesylated RhoA is a preferred substrate of YopT compared with the geranylgeranylated GTPase. Geranylgeranylated RhoA, however, is the preferred substrate for YopT‐catalyzed cleavage with a threefold faster turnover rate over Rac and Cdc42. Moreover, our data indicate that the composition of the polybasic region of the GTPases defines the specificity and efficiency of the YopT‐induced cleavage, and that a space between the polybasic stretch of amino acids at the C terminus and the CAAX box enhances the turnover rate of YopT‐catalyzed cleavage.
Novel protein folds and their nonsequential structural analogs
Authors: Guerler Aysam , Knapp Ernst‐Walter
Published: June 2008

Newly determined protein structures are classified to belong to a new fold, if the structures are sufficiently dissimilar from all other so far known protein structures. To analyze structural similarities of proteins, structure alignment tools are used. We demonstrate that the usage of nonsequential structure alignment tools, which neglect the polypeptide chain connectivity, can yield structure alignments with significant similarities between proteins of known three‐dimensional structure and newly determined protein structures that possess a new fold. The recently introduced protein structure alignment tool, GANGSTA, is specialized to perform nonsequential alignments with proper assignment of the secondary structure types by focusing on helices and strands only. In the new version, GANGSTA+, the underlying algorithms were completely redesigned, yielding enhanced quality of structure alignments, offering alignment against a larger database of protein structures, and being more efficient. We applied DaliLite, TM‐align, and GANGSTA+ on three protein crystal structures considered to be novel folds. Applying GANGSTA+ to these novel folds, we find proteins in the ASTRAL40 database, which possess significant structural similarities, albeit the alignments are nonsequential and in some cases involve secondary structure elements aligned in reverse orientation. A web server is available at http://agknapp.chemie.fu‐berlin.de/gplus for pairwise alignment, visualization, and database comparison.
Local calcium release activation by DHPR calcium channel openings in rat cardiac myocytes
Authors: Poláková Eva , Zahradníková Jr Alexandra , Pavelková Jana , Zahradník Ivan , Zahradníková Alexandra
Published: June 2008

The principal role of calcium current in the triggering of calcium release in cardiac myocytes is well recognized. The mechanism of how calcium current (ICa) controls the intensity of calcium release is not clear because of the stochastic nature of voltage‐dependent gating of calcium channels (DHPRs) and of calcium‐dependent gating of ryanodine receptors (RyRs). To disclose the relation between DHPR openings and the probability of calcium release, local calcium release activation by ICa was investigated in rat ventricular myocytes using patch‐clamp and confocal microscopy. Calcium spikes were activated by temporally synchronized DHPR calcium current triggers, generated by instantaneous ‘tail’ICa and modulated by prepulse duration, by tail potential, and by the DHPR agonist BayK 8644. The DHPR–RyR coupling fidelity was determined from the temporal distribution of calcium spike latencies using a model based on exponentially distributed DHPR open times. The analysis provided a DHPR mean open time of ∼0.5 ms, RyR activation time constant of ∼0.6 ms, and RyR activation kinetics of the 4th order. The coupling fidelity was low due to the inherent prevalence of very short DHPR openings but was increased when DHPR openings were prolonged by BayK 8644. The probability of calcium release activation was high, despite low coupling fidelity, due to the activation of many DHPRs at individual release sites. We conclude that the control of calcium release intensity by physiological stimuli can be achieved by modulating the number and duration of DHPR openings at low coupling fidelity, thus avoiding the danger of inadvertently triggering calcium release events.
Regulation of quantal shape by Rab3A: evidence for a fusion pore‐dependent mechanism
Authors: Wang Xueyong , Thiagarajan Ramachandran , Wang Qingbo , Tewolde Teclemichael , Rich Mark M. , Engisch Kathrin L.
Published: June 2008

The function of Rab3A, a small GTPase located on synaptic vesicles, is not well understood. Studies in the Rab3A−/− mouse support a role in activity‐dependent plasticity, but have not reported any effects on spontaneously occurring miniature synaptic currents, except that there is a decrease in resting frequency at the neuromuscular junction. Therefore we were surprised to find an increase in the occurrence of mEPCs with abnormally long half‐widths at the neuromuscular junctions of Rab3A−/− mice. The abnormal miniature endplate currents (mEPCs), which have significantly greater charge than the average mEPCs for the same fibres, could arise from larger vesicles. However, the type of mEPC most increased in Rab3A−/− mice has a slow rise, which suggests it is not the result of full collapse fusion. To test if the slow mEPCs increased after loss of Rab3A could be due to malfunctioning fusion pores, we used carbon fibre amperometry to record pre‐spike feet, which have been shown to correspond to the initial opening of a narrow fusion pore, in adrenal chromaffin cells of wild‐type and Rab3A−/− mice. We found that small amplitude pre‐spike feet with abnormally long durations were increased in Rab3A−/− cells. The correspondence between mEPC and amperometric data supports our interpretation that slow rising, long half‐width mEPCs are caused by reduced diameter fusion pores that remain open longer. These data could be explained by a direct action of Rab3A on the fusion pore, or by Rab3A‐dependent control of vesicles with unusual fusion pore characteristics.
Stimulation of peroxynitrite catalysis improves insulin sensitivity in high fat diet‐fed mice
Authors: Duplain Hervé , Sartori Claudio , Dessen Pierre , Jayet Pierre‐Yves , Schwab Marcos , Bloch Jonathan , Nicod Pascal , Scherrer Urs
Published: June 2008

Peroxynitrite synthesis is increased in insulin resistant animals and humans. Peroxynitirite‐induced nitration of insulin signalling proteins impairs insulin action in vitro, but the role of peroxynitrite in the pathogenesis of insulin resistance in vivo is not known. We therefore assessed the effects of a 1‐week treatment with the peroxynitrite decomposition catalyst FeTPPS on insulin sensitivity in insulin resistant high fat diet‐fed (HFD) and control mice. FeTPPS normalized the fasting plasma glucose and insulin levels (P < 0.01), attenuated the hyperglycaemic response to an intraperitoneal glucose challenge by roughly 50% (P < 0.05), and more than doubled the insulin‐induced decrease in plasma glucose levels in HFD‐fed mice (P < 0.001). Moreover, FeTPPS restored insulin‐stimulated Akt phosphorylation and insulin‐stimulated glucose uptake in isolated skeletal muscle in vitro. Stimulation of peroxynitrite catalysis attenuates HFD‐induced insulin resistance in mice by restoring insulin signalling and insulin‐stimulated glucose uptake in skeletal muscle tissue.
Repeated bouts of aerobic exercise lead to reductions in skeletal muscle free radical generation and nuclear factor κB activation
Authors: Brooks Susan V. , Vasilaki Aphrodite , Larkin Lisa M. , McArdle Anne , Jackson Malcolm J.
Published: June 2008

Chronic exercise improves endurance and skeletal muscle oxidative capacity. Despite the potential importance of reactive oxygen species (ROS) generated during exercise as regulators of these adaptations, the effect of repeated bouts of aerobic exercise on ROS generation by skeletal muscles during contractions has not been examined. Our aim was to establish the impact of repeated treadmill running exercise on muscle ROS generation and activation of redox‐sensitive transcription factors. Following 8 weeks of treadmill running, mice displayed an improvement in running speed that was associated with an enhanced ability of gastrocnemius (GTN) muscles to maintain force during a protocol of isometric contractions. In contrast to GTN muscles of cage‐sedentary (Sed) mice, muscles from exercised (Exer) mice did not release superoxide or nitric oxide during the isometric contractions. For male mice, basal levels of nuclear factor κB (NFκB) and activator protein‐1 (AP‐1) DNA binding were increased by treadmill running, and the contraction‐induced activation of NFκB and AP‐1 observed in muscles of Sed mice was absent in Exer muscles. Also in contrast to Sed muscles, Exer muscles displayed no reductions in glutathione or protein thiol levels in response to contraction. Our observations of decreases for Exer compared with Sed muscles in contraction‐induced (i) ROS generation, (ii) activation of redox‐sensitive signalling pathways, and (iii) ROS stress suggest that exercise conditioning enhances the ability of skeletal muscle to readily and rapidly detoxify ROS and/or reduces ROS generation, providing protection from ROS‐induced damage and reducing signals that might act to mediate further unnecessary adaptations.
Do multiple ionic interactions contribute to skeletal muscle fatigue?
Authors: Cairns S. P. , Lindinger M. I.
Published: June 2008

During intense exercise or electrical stimulation of skeletal muscle the concentrations of several ions change simultaneously in interstitial, transverse tubular and intracellular compartments. Consequently the functional effects of multiple ionic changes need to be considered together. A diminished transsarcolemmal K+ gradient per se can reduce maximal force in non‐fatigued muscle suggesting that K+ causes fatigue. However, this effect requires extremely large, although physiological, K+ shifts. In contrast, moderate elevations of extracellular [K+] ([K+]o) potentiate submaximal contractions, enhance local blood flow and influence afferent feedback to assist exercise performance. Changed transsarcolemmal Na+, Ca2+, Cl− and H+ gradients are insufficient by themselves to cause much fatigue but each ion can interact with K+ effects. Lowered Na+, Ca2+ and Cl− gradients further impair force by modulating the peak tetanic force–[K+]o and peak tetanic force–resting membrane potential relationships. In contrast, raised [Ca2+]o, acidosis and reduced Cl− conductance during late fatigue provide resistance against K+‐induced force depression. The detrimental effects of K+ are exacerbated by metabolic changes such as lowered [ATP]i, depleted carbohydrate, and possibly reactive oxygen species. We hypothesize that during high‐intensity exercise a rundown of the transsarcolemmal K+ gradient is the dominant cellular process around which interactions with other ions and metabolites occur, thereby contributing to fatigue.
Differential dendritic Ca2+ signalling in young and mature hippocampal granule cells
Authors: Stocca Gabriella , Schmidt‐Hieber Christoph , Bischofberger Josef
Published: June 2008

Neuronal activity is critically important for development and plasticity of dendrites, axons and synaptic connections. Although Ca2+ is an important signal molecule for these processes, not much is known about the regulation of the dendritic Ca2+ concentration in developing neurons. Here we used confocal Ca2+ imaging to investigate dendritic Ca2+ signalling in young and mature hippocampal granule cells, identified by the expression of the immature neuronal marker polysialated neural cell adhesion molecule (PSA‐NCAM). Using the Ca2+‐sensitive fluorescent dye OGB‐5N, we found that both young and mature granule cells showed large action‐potential evoked dendritic Ca2+ transients with similar amplitude of ∼200 nm, indicating active backpropagation of action potentials. However, the decay of the dendritic Ca2+ concentration back to baseline values was substantially different with a decay time constant of 550 ms in young versus 130 ms in mature cells, leading to a more efficient temporal summation of Ca2+ signals during theta‐frequency stimulation in the young neurons. Comparison of the peak Ca2+ concentration and the decay measured with different Ca2+ indicators (OGB‐5N, OGB‐1) in the two populations of neurons revealed that the young cells had an ∼3 times smaller endogenous Ca2+‐binding ratio (∼75 versus∼220) and an ∼10 times slower Ca2+ extrusion rate (∼170 s−1versus∼1800 s−1). These data suggest that the large dendritic Ca2+ signals due to low buffer capacity and slow extrusion rates in young granule cells may contribute to the activity‐dependent growth and plasticity of dendrites and new synaptic connections. This will finally support differentiation and integration of young neurons into the hippocampal network.
In vivo inhibition of focal adhesion kinase causes insulin resistance
Authors: Bisht Bharti , Srinivasan K. , Dey Chinmoy S.
Published: June 2008

Focal adhesion kinase (FAK), a non‐receptor tyrosine kinase, has recently been implicated in the regulation of insulin resistance in vitro. However, its in vivo validation has not been attempted due to lethality of FAK knockout. Hence, to ascertain the role of FAK in the development of insulin resistance in vivo, we have down‐regulated FAK expression by delivering FAK‐specific small interfering RNA (siRNA) in mice using hydrodynamic tail vein injection. Here, we show for the first time that FAK silencing (57 ± 0.05% in muscle and 80 ± 0.08% in liver) exacerbates insulin signalling and causes hyperglycaemia (251.68 ± 8.1 mg dl−1) and hyperinsulinaemia (3.48 ± 0.06 ng ml−1) in vivo. FAK‐silenced animals are less glucose tolerant and have physiological and biochemical parameters similar to that of high fat diet (HFD)‐fed insulin‐resistant animals. Phosphorylation and expression of insulin receptor substrate 1 (IRS‐1) was attenuated by 40.2 ± 0.03% and 35.2 ± 0.6% in muscle and 52.3 ± 0.04% and 40.2 ± 0.03% in liver in FAK‐silenced mice. Akt‐Ser473‐phosphorylation decreased in muscle and liver (50.3 ± 0.03% and 70.2 ± 0.02%, respectively) in FAK‐silenced mice. This, in part, explains the mechanism of development of insulin resistance in FAK‐silenced mice. The present study provides direct evidence that FAK is a crucial mediator of insulin resistance in vivo. Considering the lethality of FAK gene knockout the approach of this study will provide a new strategy for in vivo inhibition of FAK. Furthermore, the study should certainly motivate chemists to synthesize new chemical entities for FAK activation. This may shed light on new drug development against insulin resistance.
Autopsy pathology of cocaine users from the Eastern district of London: a retrospective cohort study
Authors: Rajab R , Stearns E , Baithun S
Published: June 2008

Aim:

To establish the most frequent pathological findings encountered at postmortem examination during the investigation of a fatality with a history of cocaine abuse.

Methods:

Autopsied deaths investigated by the coroner for the Eastern district of London, between 2004 and 2007, in which the decedent had positive toxicology for cocaine were identified (n = 28). The autopsy records and histology of tissue taken at autopsy were retrieved and reviewed. Pathological findings (gross and microscopic, including cardiac, pulmonary, gastrointestinal, hepatobiliary, renal and neurological) were collated.

Results:

The main pathological findings at autopsy occurring in this cohort (comprising predominantly men, mean age 31 years), were cardiovascular: left ventricular hypertrophy (46%), multifocal myocardial fibrosis (21%), coronary artery disease (29%), cerebrovascular disease (36%) and pulmonary oedema (71%). Hepatic steatosis (29%) and gastrointestinal haemorrhage (18%), due mostly to gastric erosions/ulceration, were also frequent findings.

Conclusions:

During a coroner’s autopsy of a cocaine user, a thorough cardiac examination combined with cardiac tissue sampling for histology, are valuable investigations, which are most likely to help show pathology relevant to the cause of death.
High levels of expression of cytokeratin 5 are strongly correlated with poor survival in higher grades of mucoepidermoid carcinoma
Authors: Lueck N E , Robinson R A
Published: June 2008

Aims:

Mucoepidermoid carcinoma (MEC) is the most common malignant primary salivary gland tumour. Little is known about cytokeratin expression in MEC or how it may relate to survival. In this study, the aim was to determine the extent of cytokeratin 5 (CK5) expression in intermediate- and high-grade MEC and correlate expression with survival.

Methods:

Data on clinicopathological features including stage and survival outcome were collected on 29 patients with intermediate- or high-grade MEC that had follow-up for at least 4 years or until death. Staining with antibody to CK5 protein was carried out and tumour staining was stratified as 0–3 (0, no tumour cells staining; 1, 1–25% of tumour cells staining; 2, 26–75% of tumour cells staining; 3, >75% of tumour cells staining). Six patients had intermediate-grade tumours and 23 had high-grade tumours. The median patient follow-up was 33 months, and 11 patients were alive at the end of the study.

Results:

At the end of the study, 12/13 patients with the highest (>75%) CK5 expression were dead, while 6 of 18 patients with less than 75% expression were dead (p = 0.006, Fisher exact test). When compared with those patients whose tumours had less than 75% expression, patients whose tumours had greater than 75% CK5 expression had much poorer survival times (log-rank test; p ⩽ 0.001).

Conclusions:

The findings suggest that very high levels of CK5 expression may be a potential marker for worse outcome in intermediate- and high-grade MEC.
Kimberlite-sourced bentonite, its paleoenvironment and implications for the Late Cretaceous K14 kimberlite cluster, northern AlbertaThis article is one of a selection of papers published in this Special Issue on the themeGeology of northeastern British Columbia and northwestern Alberta: diamonds, shallow gas, gravel, and glaciers.
Authors: Eccles D. Roy , Heaman Larry M. , Sweet Arthur R.
Published: June 2008

Kimberlite-sourced bentonite layers have been discovered in Late Cretaceous sedimentary drill cores located within the Buffalo Head Hills kimberlite field, north-central Alberta. Two bentonites are unambiguously differentiated from “common” intermediate to felsic volcanic-derived Alberta bentonite by having similar whole-rock geochemical composition to ultramafic rocks from the Buffalo Head Hills kimberlite field and worldwide crater-facies kimberlite. The results demonstrate that the geochemical analysis of bentonite can provide a quick, cost-effective means of testing for low-volume kimberlite volcanism. The kimberlite-sourced bentonite is associated with a cluster of Buffalo Head Hills kimberlites known as the K14 complex. The K14A kimberlite occurrence has a previously reported206Pb/238U perovskite emplacement age of 86.8 ± 2.1 Ma. This age is compatible with early or mid-Cenomanian (∼99–96 Ma) and mid-Coniacian to Santonian (∼88–84 Ma) palynological results for mudstone underlying and bracketing the K14A and K14B kimberlites, respectively. Conversely, biostratigraphically significant palynomorphs in host rock cores bracketing the K14C kimberlite indicate emplacement during the Cenomanian or Turonian (∼96–92 Ma). U–Pb detrital zircon ages from syndepositional kimberlite-sourced bentonite directly adjacent to the K14C kimberlite contains a high frequency of young (∼99–92 Ma) zircon with a best maximum206Pb/238U depositional age of 91.7 ± 2.9 Ma. Thus, this innovative approach may provide evidence of multiple episodes of kimberlite emplacement within or near the K14 complex.
Olenid-dominated trilobite fauna from the Shallow Bay Formation (Cow Head Group), Cambrian–Ordovician boundary interval, western Newfoundland
Authors: Karim Talia S.
Published: June 2008

A single boulder (PH 8.14), recovered from unit 8 on the Point of Head, Cow Head Peninsula, Shallow Bay Formation (Cow Head Group), contains a unique olenid-dominated trilobite fauna composed of the following taxa: Boeckaspis geordii n. sp., Leiobienvillia terranovica (Rasetti, 1954), hystricurid n. gen. n. sp., Tulepyge sp. A, Tulepyge sp. B, Tulepyge? sp. C, and Symphysurina sp. The pelturine trilobite  B. geordii dominates the assemblage. Boulder PH 8.14 consists of light grey-brown packstone to grainstone. This is atypical for olenid-dominated faunas, which usually occur in dark laminated limestones and shales. The fauna is likely earliest Ordovician in age, but a latest Cambrian age cannot be entirely ruled out. Regardless, this assemblage is unique in that it is the only known olenid-dominated fauna from Cambrian–Ordovician boundary sediments in Laurentia. A phylogenetic analysis of Boeckaspis and other putatively closely related taxa ( Westergaardia Raymond, 1924 and Jujuyaspis Kobayashi, 1936) was conducted. The results of the analysis indicate that Westergaardia is not monophyletic and as such it is considered a junior synonym of Boeckaspis herein.
Mountain permafrost probability mapping using the BTS method in two climatically dissimilar locations, northwest Canada
Authors: Bonnaventure Philip P. , Lewkowicz Antoni G.
Published: June 2008

The Basal Temperature of Snow (BTS) method was used to predict permafrost distribution in two climatologically dissimilar mountain environments in northwest Canada. Permafrost probability maps with 30 m × 30 m grid cells were generated for part of the Ruby Range, Yukon Territory (425 km2), and for the Haines Summit area, northern British Columbia (536 km2), using winter BTS measurements in conjunction with late-summer ground truthing by probing and digging pits to physically verify the presence of permafrost. BTS values, and hence permafrost distribution, were modeled using elevation and potential incoming solar radiation (PISR) for the Ruby Range. PISR was not significant at Haines Summit, probably because persistent cloudiness associated with its more maritime climatic regime reduced aspect-induced variability in insolation. Probability maps indicate that ∼66% of the Ruby Range area and ∼43% of the Haines Summit area are underlain by permafrost. Therefore, the Ruby Range should be classified as extensive discontinuous permafrost, while Haines Summit is part of the sporadic discontinuous permafrost zone and not the isolated patches zone as portrayed on recent maps. Extensive ground truthing proved to be an essential part of the procedure because traditional BTS “rules-of-thumb” did not remain valid across the differing mountain climate zones.
An evaluation of steel fibre reinforced shotcrete for underground support
Authors: Little T. E.
Published: June 2008

Exploratory work at a proposed hydroelectric site on the Peace River in British Columbia included excavation of several adits and a test chamber about 11 m wide, 7.5 m high, and 45 m in length. Most of these excavations, in a Cretaceous slaking shale, were lined with steel fibre reinforced shotcrete. Laboratory tests indicate that the properties of the steel fibre shotcrete compare favourably with those of plain shotcrete. Field tests suggest that the steel fibre shotcrete is equal to wire fabric reinforced shotcrete in load-carrying capacity and for support of underground excavations. Some of the adits were excavated more than 5 years ago and the shotcrete continues to perform well. It is suggested that steel fibre shotcrete is also suitable for underground support in most other rock types and offers cost savings over the use of wire fabric reinforced shotcrete. Key words: slaking shale, shotcrete, steel fibre reinforced shotcrete, laboratory tests, field tests, underground excavation, test chamber.
Evaluating height structure in Scots pine forests using marked point processes
Authors: Montes Fernando , Barbeito Ignacio , Rubio Agustín , Cañellas Isabel
Published: June 2008

In this study, the second-moment analysis of marked spatial point processes is applied to the characterization of the tree height distribution in two Scots pine ( Pinus sylvestris L.) forests in the Central Mountain Range of Spain. The cumulative function Lm(d) weighted by the normalized mark variance is proposed to analyse the second-order properties of marked point patterns. The empirical Lm(d) was compared with two null models to assess the relationship between the spatial distribution of the trees and the tree height correlations: the first null model was used to characterize the spatial clustering of the trees and was derived from the complete spatial randomness model used with Ripley’s K(d) function. The second null model, which is derived from the random labelling model used with the intertype second-moment measure K12(d) (type 1 intensity conditioned to the type 2 intensity and vice versa), allows us to identify the mark correlations. The performance of the technique was assessed through simulated marked point patterns. The second-moment analysis showed that most of the analysed Scots pine stands have a uniform height distribution at small scale and greater heterogeneity at large scales, with the exception of an upper altitudinal stand, which exhibited heterogeneity at short distances. These results demonstrate the utility of second-moment analysis of marked point processes for characterizing height structure in forest stands and the interaction between the height and the spatial pattern of the trees.
Simultaneous unbiased estimates of multiple downed wood attributes in perpendicular distance sampling
Authors: Ducey Mark J. , Williams Michael S. , Gove Jeffrey H. , Valentine Harry T.
Published: June 2008

Perpendicular distance sampling (PDS) is a fast probability-proportional-to-size method for inventory of downed wood. However, previous development of PDS had limited the method to estimating only one variable (such as volume per hectare, or surface area per hectare) at a time. Here, we develop a general design-unbiased estimator for PDS. We then show how that estimator can be used to develop simple measurement protocols that allow simultaneous, unbiased estimation of multiple downed wood variables, including logs per hectare, length of logs per hectare, surface area or area coverage per hectare, and volume per hectare.
Linking environmental gradients, species composition, and vegetation indicators of sugar maple health in the northeastern United States
Authors: Horsley Stephen B. , Bailey Scott W. , Ristau Todd E. , Long Robert P. , Hallett Richard A.
Published: June 2008

Sugar maple ( Acer saccharum Marsh.) decline has occurred throughout its range over the past 50 years, although decline symptoms are minimal where nutritional thresholds of Ca, Mg, and Mn are met. Here, we show that availability of these elements also controls vascular plant species composition in northern hardwood stands and we identify indicator species of these nutrient thresholds. Presence and abundance of vascular plant species and data on 35 environmental variables were collected from 86 stands in New Hampshire and Vermont (NHVT) and Pennsylvania and New York (PANY). Nonmetric multidimensional scaling ordination was used to determine which variables affected presence and abundance of species; both measures gave similar results. A base cation – acid cation nutrient gradient on axis one accounted for 71.9% (NHVT) and 63.0% (PANY) of the variation in the nonmetric multidimensional scaling ordination. Measures of Ca, Mg, and pH formed the base end and Al, Mn, K, soil acidity, and organic matter the acid end in both subregions. In both subregions, sugar maple foliar Mg and Ca had the strongest association with the base end of axis 1; exchangeable Al in NHVT and foliar Mn in PANY were strongly associated with the acid end. McNemar’s exact test and indicator species analysis were used to determine which species were present in stands that met the nutritional thresholds for Ca, Mg, and Mn foliar chemistry. McNemar’s exact test identified 16 species in NHVT and PANY, 16 additional species in NHVT only, and 12 additional species in PANY only. Indicator species analysis identified a subset of these species with the highest frequency of occurrence. Indicator species could provide land managers with a diagnostic tool for determining where on the landscape sugar maple is “at risk” or likely to remain healthy in the face of stresses.
Natural regeneration in a beech-dominated forest managed by close-to-nature principles — a gap cutting based experiment
Authors: Madsen Palle , Hahn Katrine
Published: June 2008

European beech ( Fagus sylvatica L.) is increasingly managed by close-to-nature principles, mimicking the gap dynamics of seminatural forests. The prime aim of this study was to analyse natural regeneration reliability under favourable conditions in newly formed gaps. A total of 12 gaps were created by felling three canopy trees for each gap: six gaps in each of the two winters 1996–1997 and 1997–1998. One-half of the gaps were fenced against deer. We recorded advance regeneration density (1997), regeneration density and height (1997–2002), relative light intensity (1997–2002), and volumetric soil moisture content (1997–2002). We also studied the effect of year of establishment, fenced versus unfenced, and position within gap on regeneration. Three or 4 years after gap formation, most gaps had nearly closed. Response of European beech, European ash ( Fraxinus excelsior L. ), and sycamore maple ( Acer pseudoplatanus L.) regeneration to gap formation was limited, and few seedlings were added to the advance regeneration pool during the study period. Other factors, such as relative light intensity, soil moisture, fencing, year of establishment, and position within gaps, all had rather low effects. Thus, the presence of advance regeneration appeared to be a key factor in explaining regeneration patterns in artificially created gaps.
Work climate, innovativeness, and firm performance in the US forest sector: in search of a conceptual framework
Authors: Crespell Pablo , Hansen Eric
Published: June 2008

Innovativeness can help companies differentiate themselves, with the ultimate goal of securing survival and improving performance. Modern theories in organizational behavior look at innovation as something that starts with individual creativity but that is also affected by the work environment. Using one broad industry sector, the US forest products industry, this study attempts to integrate into a unifying model the concepts of work climate, innovativeness, and firm performance using structural equation modeling. Results support the proposed theoretical model, with some modifications, finding a positive and significant relationship among all factors. Having innovation as a core part of a company’s strategy and fostering a climate for innovation positively affects the degree of innovativeness and performance of a company. This is especially true for secondary or value-added wood products manufacturers. A climate for innovation is characterized by high levels of autonomy and encouragement, team cohesion, openness to change and risk taking, and sufficient resources available to people. Lack of a validation sample suggests treating the model as tentative until further testing.
Quantifying the interrelationship between tree stand growth rate and water table level in drained peatland sites within Central Finland
Authors: Hökkä Hannu , Repola Jaakko , Laine Jukka
Published: June 2008

The quantitative relationship between stand growth rate and water table level in peatland forest sites has not been fully ascertained in the literature. In this study, we investigated this relationship by means of a bivariate regression model. Tree and stand attributes, including volume and past 5-year volume growth as well as median water table depth (WTM) during the 1984 growing season, were observed in 69 Scots pine ( Pinus sylvestris L.) sample stands with three subplots established in each stand. All stands were located in deep-peated, moderately rich to poor organic soil sites in Central Finland (61°45′–62°26′N, 22°40′–28°29′E) that had been ditched for forestry about 25 years earlier (1959–1961). Prediction models for the fixed mean functions for 5-year volume growth and WTM as well as estimates for variances and the correlation of random effects at plot and subplot levels were estimated simultaneously using bivariate regression methods. The correlation of model residuals at the plot level was highly significant. The model was applied to simulate stand volume development for a period of 20 years. Simulations illustrated the dynamic interaction of stand volume, volume growth, and soil water levels: deep initial WTM resulted in stand growth and volume-development increases and subsequently further deepened the WTM in the stand. The model can be applied to southern boreal drained Scots pine peatlands to estimate the WTM in different stand volume conditions and to assess the effect of stand management on WTM.
The effect of mechanical site preparation on ectomycorrhizae of planted white spruce seedlings in conifer-dominated boreal mixedwood forest
Authors: Lazaruk Lance W. , Macdonald S. Ellen , Kernaghan Gavin
Published: June 2008

We characterized the ectomycorrhizae (ECM) of planted white spruce ( Picea glauca (Moench) Voss) seedlings as affected by mechanical site preparation (MSP) of clear-cut conifer-dominated boreal mixedwood forest. Relative abundance, richness, and composition of the ECM community were compared among untreated control, mixed, mounded, and scalped site preparation treatments. On >11 000 root tips, we observed 16 ECM morphotypes. Those common to the nursery in which the seedlings were raised were most abundant ( Thelephora americana , Wilcoxina -like (E-strain), Amphinema byssoides , Phialocephala -like (MRA)). Seedlings in the untreated controls had lower abundances of these, but higher abundances of other ECM, which were not present in the nursery of origin but were indigenous to these forest stands. In terms of ECM composition, the “mixed” treatment was most similar to the untreated control, while the “scalped” and “mound” treatments showed significantly different ECM communities than the controls. Our results suggest that MSP may facilitate continued dominance by ECM that establish on seedlings in the nursery while slowing the natural succession towards the natural forest ECM. MSP treatments that leave some surface organic matter relatively intact may impact ECM less than those that remove or bury the organic layer.
Influence of microhabitat on bryophyte diversity in Ontario mixedwood boreal forest
Authors: Cole Heather A. , Newmaster Steven G. , Bell F. Wayne , Pitt Doug , Stinson Al
Published: June 2008

As forest management intensifies, the conservation of forest biodiversity is a growing concern. Bryophytes are known to represent a considerable portion of plant diversity within northern forests. This is because bryophyte diversity is closely associated with microhabitat diversity. In this study, the influence of microhabitats on bryophyte diversity was investigated by comparing eight different boreal mixedwood microhabitats. The results indicate that bryophyte diversity (species richness, abundance, and evenness) is quite variable among microhabitats. The accumulation of species richness with microhabitat quantity within a forest stand also varies among microhabitats. β-diversity analyses indicate that the variety of microhabitats has considerable influence on community structure. Frequency analysis identified bryophytes that are restricted to or prefer particular microhabitats. Although all microhabitats are important to bryophyte diversity, decayed logs and rocks supported the greatest number of microhabitat-specific species, and rock microhabitats supported the largest total number of species. Recommendations for forest management, one of which emphasizes the need to recognize and manage the natural variety of microhabitats, such as downed woody material, found within the forests to conserve or restore bryophyte diversity are provided.
Estimation of species-specific diameter distributions using airborne laser scanning and aerial photographs
Authors: Packalén Petteri , Maltamo Matti
Published: June 2008

The use of diameter distributions originates from a need for tree-level description of forest stands, which is required, for example, in growth simulators and bucking. Diameter distribution models are usually applied, since measuring empirical diameter distributions in practical forest inventories is too laborious. This study investigated the ability of remote sensing information to predict species-specific diameter distributions. The study was carried out in Finland in a typical managed boreal forest area. The tree species considered were Scots pine ( Pinus sylvestris L.), Norway spruce ( Picea abies (L.) Karst.), and deciduous trees as a group. Growing stock was estimated using the k-MSN method using airborne laser scanning data and aerial photographs. Two approaches were compared: first, the nearest neighbour approach based on field measured trees was used as such to predict diameter distribution, and second, a theoretical diameter distribution approach in which the parameters of the Weibull distribution are predicted using the k-MSN estimates was applied. Basically, all test criteria indicated that the diameter distribution based on nearest neighbour imputed trees outperforms the Weibull distribution, but care must be taken to ensure that the modelling data are comprehensive enough.
Predicting selected wood properties of jack pine following commercial thinning
Authors: Schneider Robert , Zhang S. Y. , Swift D. Edwin , Bégin Jean , Lussier Jean-Martin
Published: June 2008

This paper examined the impact of commercial thinning on selected wood properties of jack pine ( Pinus banksiana Lamb.). Wood properties evaluated include wood density (ring density, earlywood ring density, and latewood ring density), percentage of latewood in the ring, and wood bending properties. Nonlinear, mixed-effect models have been developed using data from three commercially thinned sites in eastern Canada. Ring density followed the same pattern as percentage of latewood, in which cambial age, relative height, and ring width were found to have important effects. Earlywood and latewood ring densities changed within the juvenile wood zone until a plateau was reached. Ring width affected earlywood and latewood ring densities mainly in narrow rings. Wood bending stiffness (measured by modulus of elasticity) and strength (measured by modulus of rupture) increased with cambial age and wood density; whereas, wood strength was also affected by ring width. Commercial thinning did not influence the developed models, but it had an indirect effect through increased ring width.
Clone by isolate interaction in the hybrid poplar – Septoria musiva pathosystem
Authors: LeBoldus Jared M. , Blenis Peter V. , Thomas Barb R.
Published: June 2008

Fourteen clones of hybrid poplar were inoculated with 19 isolates of Septoria musiva Peck under greenhouse conditions to determine the magnitude of the clone, isolate, and clone × isolate interaction effects. Septoria musiva isolates were collected from five geographic areas, two symptoms (canker and leaf spot), and two host types (native species and hybrid poplar). The hybrid poplar clones were classified by parent type ( Populus deltoides Bartr. ex Marsh., Populus laurifolia Lebed. × Populus nigra L., and P. deltoides × (P. laurifolia × P. nigra)). There were no significant differences among geographic areas (p = 0.443), symptoms (p = 0.842), or hosts (p = 0.304) of origin for the 19 isolates nor significant differences among the three parent types (p = 0.089). Clone, isolate, and clone × isolate interaction effects were all significant, accounting for 65%, 15%, and 18%, respectively, of the explained variation. These results indicate that clones rather than parent types should be the focus of resistance screening programs and that the pathosystem should be stable given the relatively small clone × isolate interaction. These results also indicate that a single isolate should be sufficient for preliminary screening of disease resistance in hybrid poplars.
Impact of a pine lappet (Dendrolimus pini) mass outbreak on C and N fluxes to the forest floor and soil microbial properties in a Scots pine forest in Germany
Authors: le Mellec Anne , Michalzik Beate
Published: June 2008

Herbivorous insect infestations significantly alter element and nutrient cycling in forests, thus directly and indirectly affecting ecosystem functioning. In this paper, we report on the herbivore-mediated transfer of carbon (C) and nitrogen (N) from the canopy to the forest floor and its influence on soil microbial activity during a pine lappet ( Dendrolimus pini L.) infestation. Over the course of 6 months, we followed C and N fluxes in bulk deposition, throughfall, and green fall (green needle debris dropped during herbivory) together with solid frass (insect faeces) in an 80-year-old Scots pine ( Pinus silvestris L.) forest. Compared with the control, herbivore defoliation significantly doubled throughfall inputs of total and dissolved organic C and N over the study period. Frass plus green-fall C and N fluxes peaked in June–July at 110 kg C·ha–1and 2.3 kg N·ha–1, respectively. Randomized intervention analysis revealed no significant effects of herbivory on soil microbial properties, except for adenylate energy charge, which showed slightly higher values under herbivory. This study demonstrates the importance of canopy herbivory on overall C and N inputs to forest ecosystems, particularly in altering the timing and quality of the organic material reaching the forest floor and potentially affecting belowground processes.