bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of a Quantitative Trait Locus for High-Temperature Adult-Plant Resistance Against Puccinia striiformis f. sp. hordei in ‘Bancroft’ Barley
Authors: Yan Guiping , Chen Xianming
Published: December 2007

Sustainable control of plant diseases can be achieved by developing cultivars with durable resistance. ‘Bancroft’ barley has durable high-temperature, adult-plant (HTAP) resistance to stripe rust caused by Puccinia striiformis f. sp. hordei. The objectives of this study were to determine the inheritance of the HTAP resistance in Bancroft, develop molecular markers for the HTAP resistance using the resistance gene analog polymorphism (RGAP) technique, map the HTAP resistance quantitative trait locus or loci (QTL) on barley chromosomes, and determine the usefulness of the RGAP markers in other barley cultivars for marker-assisted selection. The parents and F4 recombinant inbred lines (RIL) and the parents and F5 RIL were evaluated in 2004 and 2005 in one and three field sites, respectively, in Washington State. Infection type (IT) and disease severity (DS) were recorded three times at each location during each growing season. Area under the disease progress curve (AUDPC) was calculated for each parent and RIL based on the DS data. Genetic analyses of IT data of the parents, F1, and F2 tested in the adult-plant stage under controlled high-temperature cycle in the greenhouse and the parents, F4, and F5 RIL in the field indicated that one dominant gene controlled the HTAP resistance in Bancroft. Using 119 F5:6 RIL and IT data, a linkage map on chromosome arm 3HL was constructed with eight RGAP markers and three simple sequence repeat (SSR) markers. Using the QTL analysis, a QTL for HTAP resistance was mapped with the DS and AUDPC data on the same chromosome location as with the IT data. The QTL explained >70% of the total phenotypic variation for the DS and AUDPC. The heritability of the HTAP resistance based on the AUDPC data was 76%. The two markers most close to the QTL peak detected polymorphisms in 84 and 88% of 25 barley genotypes that do not have the Bancroft HTAP resistance when used individually, and detected polymorphism in 100% of the genotypes when used in combination, indicating that the markers could be used in incorporating the HTAP resistance into these barley genotypes to improve the level and durability of resistance to stripe rust.
The Relationship of Host-Mediated Induced Resistance to Polymorphism in Gene-for-Gene Relationships
Authors: Tellier Aurélien , Brown James K. M.
Published: December 2007

Gene-for-gene relationships are a common feature of plant-parasite interactions. Polymorphism at host resistance and parasite avirulence loci is maintained if there is negative, direct frequency-dependent selection on alleles of either gene. More specifically, selection of this kind is generated when the disease is polycyclic with frequent auto-infection. When an incompatible interaction occurs between a resistant host and an avirulent parasite, systemic defenses are triggered, rendering the plant more resistant to a later attack by another parasite. However, induced resistance (IR) incurs a fitness cost to the plant. Here, the effect of IR on polymorphism in gene-for-gene interactions is investigated. First, in an infinite population model in which parasites have two generations per host generation, increasing the fitness cost of IR increases selection for susceptible plants at low disease severity, while increasing the effectiveness of IR against further parasite attacks enhances selection for resistant plants at high disease severity. This reduces the possibility of polymorphism being maintained in host and parasite populations. In finite population models, the number of plants varies over time as a function of the disease burden of the population. Polymorphism in gene-for-gene relationships is then more stable at high disease prevalence and severity if IR reactions are more costly when there is competition for resources between plants.
Variation in Rates of Spore Deposition of Fusarium circinatum, the Causal Agent of Pine Pitch Canker, Over a 12-Month-Period at Two Locations in Northern California
Authors: Garbelotto M. , Smith T. , Schweigkofler W.
Published: December 2007

Patterns of spore deposition by Fusarium circinatum, the causal agent of pine pitch canker (PPC) of Monterey pine (Pinus radiata) and other conifers, were studied between May 2003 and April 2004 at two sites in Northern California using a novel spore trapping method combined with a real-time polymerase chain reaction (PCR) approach. At each study site, two plots were sampled by placing spore traps at 100 m intervals along transects 600 m in length. The air was sampled continuously by exchanging the spore traps every 2 weeks. The spore deposition rate (DR), ranged from 0 to 1.3 × 105 spores m–2. Spores were detected throughout the year, with higher trapping frequencies (TF) during the rainy season (November to April), than during the dry season (May to October). The detection of spores on traps at distances larger than 200 m from any Monterey pine, suggests at least midrange aerial dispersal. Finally, different inoculum loads were associated with trees displaying different levels of disease symptoms, suggesting infectiousness of the pathogen varies as the disease progresses. This study represents one of the first documenting continuous inoculum pressure values over an entire year for a forest pathogen, and provides important epidemiological information that will be invaluable in the development of disease progression models.
Polyhedral realization of crystal bases for generalized Kac–Moody algebras
Authors: Shin Dong-Uy
Published: December 2007

In this paper, we give a polyhedral realization of the crystal B(∞) of Uq−(𝔤) for the generalized Kac–Moody algebras. As applications, we give explicit descriptions of crystals for the generalized Kac–Moody algebras of rank 2 and 3, and Monster Lie algebras.
Mitochondrial ATP‐sensitive K+ channels regulate NMDAR activity in the cortex of the anoxic western painted turtle
Authors: Pamenter Matthew Edward , Shin Damian Seung‐Ho , Cooray Mohan , Buck Leslie Thomas
Published: December 2007

Hypoxic mammalian neurons undergo excitotoxic cell death, whereas painted turtle neurons survive prolonged anoxia without apparent injury. Anoxic survival is possibly mediated by a decrease in N‐methyl‐d‐aspartate receptor (NMDAR) activity and maintenance of cellular calcium concentrations ([Ca2+]c) within a narrow range during anoxia. In mammalian ischaemic models, activation of mitochondrial ATP‐sensitive K+ (mKATP) channels partially uncouples mitochondria resulting in a moderate increase in [Ca2+]c and neuroprotection. The aim of this study was to determine the role of mKATP channels in anoxic turtle NMDAR regulation and if mitochondrial uncoupling and [Ca2+]c changes underlie this regulation. In isolated mitochondria, the KATP channel activators diazoxide and levcromakalim increased mitochondrial respiration and decreased ATP production rates, indicating mitochondria were ‘mildly’ uncoupled by 10–20%. These changes were blocked by the mKATP antagonist 5‐hydroxydecanoic acid (5HD). During anoxia, [Ca2+]c increased 9.3 ± 0.3% and NMDAR currents decreased 48.9 ± 4.1%. These changes were abolished by KATP channel blockade with 5HD or glibenclamide, Ca2+c chelation with 1,2‐bis(o‐aminophenoxy)ethane‐N,N,N′,N′‐tetraacetic acid (BAPTA) or by activation of the mitochondrial Ca2+ uniporter with spermine. Similar to anoxia, diazoxide or levcromakalim increased [Ca2+]c 8.9 ± 0.7% and 3.8 ± 0.3%, while decreasing normoxic whole‐cell NMDAR currents by 41.1 ± 6.7% and 55.4 ± 10.2%, respectively. These changes were also blocked by 5HD or glibenclamide, BAPTA, or spermine. Blockade of mitochondrial Ca2+‐uptake decreased normoxic NMDAR currents 47.0 ± 3.1% and this change was blocked by BAPTA but not by 5HD. Taken together, these data suggest mKATP channel activation in the anoxic turtle cortex uncouples mitochondria and reduces mitochondrial Ca2+ uptake via the uniporter, subsequently increasing [Ca2+]c and decreasing NMDAR activity.
Anticipatory changes in human motoneuron discharge patterns during motor preparation
Authors: Duclos Yann , Schmied Annie , Burle Boris , Burnet Henri , Rossi‐Durand Christiane
Published: December 2007

The influence of motor preparation on human motoneuron activity was studied by combining single motor unit recording techniques with reaction‐time (RT) methods. The tonic activity of wrist extensor motor units associated with voluntary isometric contractions was analysed during preparation for a ballistic wrist extensor muscle contraction, using a time preparation procedure. Two durations of the preparatory period elapsing between the warning signal and the response signal were used in separate blocks of trials: a short preparatory period (1 s) allowing optimum time preparation, and a longer, non‐optimum one (3 s). Changes in motoneuron tonic discharge patterns not associated with any changes in the force output were observed during the preparatory period, which suggests that these changes were subtle enough to prevent any changes in muscle contraction from occurring before the forthcoming movement. The changes observed were a lengthening of the mean interspike interval (ISI) and a decrease in the ISI variability. These data confirm that inhibitory mechanisms are activated during motor preparation and suggest that spinal inhibitory mechanisms are involved in the preparatory processes. The mechanisms possibly involved, such as presynaptic inhibition, dysfacilitation processes or AHP conductance changes, are discussed. The fact that the preparation‐induced effects on motoneuron activity were particularly prominent during the last part of the 3 s preparatory period suggests that they were probably related to the neural processes underlying temporal estimation. The anticipatory changes in motoneuron activity observed here during preparation for action provide evidence that central influences act on spinal motoneurons well before it is time to act.
Postnatal tuning of cutaneous inhibitory receptive fields in the rat
Authors: Bremner Lindsay R. , Fitzgerald Maria
Published: December 2007

Spinal nociceptive processing undergoes extensive maturation in the postnatal period. The large excitatory cutaneous receptive fields and sensitivity to mechanical stimulation in the first weeks of life suggest a lack of inhibitory control in developing spinal sensory pathways, which cannot be easily explained at the synaptic level. We hypothesized that developmental changes in dorsal horn inhibition occur at the network level, and tested this by mapping the spatial and modality organization of dorsal horn cell inhibitory receptive fields (RFs) in decerebrate spinal adult and neonatal rats. We report two novel results. First, although contralateral inhibition of dorsal horn cells was well established by postnatal day 3 (P3), inhibitory RFs were significantly less spatially restricted at P3 than in the adult and the intensity of inhibition across the RF was more evenly distributed in the neonate. Second, contralateral inhibitory RFs could be activated by both low‐ and high‐intensity stimulation in the neonate, in contrast to the situation in adult where high‐intensity pinch is normally required. These results demonstrate substantial postnatal changes in the organization or ‘tuning’ of inhibition in the developing dorsal horn, which are likely to contribute to the maturation of tactile and nociceptive spinal processing and coordinated sensorimotor and pain behaviour.
The expression of GABAAβ subunit isoforms in synaptic and extrasynaptic receptor populations of mouse dentate gyrus granule cells
Authors: Herd Murray B. , Haythornthwaite Alison R. , Rosahl Thomas W. , Wafford Keith A. , Homanics Gregg E. , Lambert Jeremy J. , Belelli Delia
Published: December 2007

The subunit composition of GABAA receptors influences their biophysical and pharmacological properties, dictates neuronal location and the interaction with associated proteins, and markedly influences the impact of intracellular biochemistry. The focus has been on α and γ subunits, with little attention given to β subunits. Dentate gyrus granule cells (DGGCs) express all three β subunit isoforms and exhibit both synaptic and extrasynaptic receptors that mediate ‘phasic’ and ‘tonic’ transmission, respectively. To investigate the subcellular distribution of the β subunits we have utilized the patch‐clamp technique to compare the properties of ‘tonic’ and miniature inhibitory postsynaptic currents (mIPSCs) recorded from DGGCs of hippocampal slices of P20–26 wild‐type (WT), β2−/−, β2N265S (etomidate‐insensitive), α1−/− and δ−/− mice. Deletion of either the β2 or the δ subunit produced a significant reduction of the tonic current and attenuated the increase of this current induced by the δ subunit‐preferring agonist 4,5,6,7‐tetrahydroisoxazolo[5,4‐c]pyridin‐3‐ol (THIP). By contrast, mIPSCs were not influenced by deletion of these genes. Enhancement of the tonic current by the β2/3 subunit‐selective agent etomidate was significantly reduced for DGGCs derived from β2N265S mice, whereas this manipulation had no effect on the prolongation of mIPSCs produced by this anaesthetic. Collectively, these observations, together with previous studies on α4−/− mice, identify a population of extrasynaptic α4β2δ receptors, whereas synaptic GABAA receptors appear to primarily incorporate the β3 subunit. A component of the tonic current is diazepam sensitive and is mediated by extrasynaptic receptors incorporating α5 and γ2 subunits. Deletion of the β2 subunit had no effect on the diazepam‐induced current and therefore these extrasynaptic receptors do not contain this subunit. The unambiguous identification of these distinct pools of synaptic and extrasynaptic GABAA receptors should aid our understanding of how they act in harmony, to regulate hippocampal signalling in health and disease.
LTP of GABAergic synapses in the ventral tegmental area and beyond
Authors: Nugent Fereshteh S. , Kauer Julie A.
Published: December 2007

One of the mechanisms by which the experience‐dependent reorganization of neural circuitry can occur is through changes in synaptic strength. Almost every excitatory synapse in the mammalian brain exhibits LTP (long‐term potentiation) or LTD (long‐term depression), two cellular mechanisms of synaptic plasticity. However, LTP and LTD have been reported much more rarely at fast inhibitory GABAA receptor synapses. Our recent study suggests that in vivo morphine initiates a long‐lasting alteration of GABAergic synapses in the ventral tegmental area (VTA) by blocking the mechanisms required for LTP of GABAergic synapses. Here we put this work into the context of other examples of synaptic plasticity at GABAergic synapses.
Elementary Structural Motifs in a Random Network of Cytosine Adsorbed on a Gold(111) Surface
Authors: Otero Roberto , Lukas Maya , Kelly Ross E. A. , Xu Wei , Lægsgaard Erik , Stensgaard Ivan , Kantorovich Lev N. , Besenbacher Flemming
Published: December 2007

Nonsymmetrical organic molecules adsorbed on solid surfaces may assemble into random networks, thereby providing model systems for organic glasses that can be directly observed by scanning tunneling microscopy (STM). We investigated the structure of a disordered cytosine network on a gold(111) surface created by thermal quenching, to temperatures below 150 K, of the two-dimensional fluid present on the surface at room temperature. Comparison of STM images to density functional theory calculations allowed us to identify three elementary structural motifs (zigzag filaments and five- and six-membered rings) that underlie the whole supramolecular random network. The identification of elementary structural motifs may provide a new framework for understanding medium-range order in amorphous and glassy systems.
Gnotobiotic Mouse Immune Response Induced byBifidobacteriumsp. Strains Isolated from Infants
Authors: Ménard Odile , Butel Marie-José , Gaboriau-Routhiau Valérie , Waligora-Dupriet Anne-Judith
Published: December 2007

Bifidobacterium, which is a dominant genus in infants’ fecal flora and can be used as a probiotic, has shown beneficial effects in various pathologies, including allergic diseases, but its role in immunity has so far been little known. Numerous studies have shown the crucial role of the initial intestinal colonization in the development of the intestinal immune system, and bifidobacteria could play a major role in this process. For a better understanding of the effect ofBifidobacteriumon the immune system, we aimed at determining the impact ofBifidobacteriumon the T-helper 1 (TH1)/TH2 balance by using gnotobiotic mice. Germfree mice were inoculated withBifidobacterium longumNCC2705, whose genome is sequenced, and with nineBifidobacteriumstrains isolated from infants’ fecal flora. Five days after inoculation, mice were killed. Transforming growth factor β1 (TGF-β1), interleukin-4 (IL-4), IL-10, and gamma interferon (IFN-γ) gene expressions in the ileum and IFN-γ, tumor necrosis factor alpha (TNF-α), IL-10, IL-4, and IL-5 secretions by splenocytes cultivated for 48 h with concanavalin A were quantified. TwoBifidobacteriumspecies had no effect (B. adolescentis) or little effect (B. breve) on the immune system.Bifidobacterium bifidum,Bifidobacterium dentium, and oneB. longumstrain induced TH1 and TH2 cytokines at the systemic and intestinal levels. OneB. longumstrain induced a TH2 orientation with high levels of IL-4 and IL-10, both secreted by splenocytes, and of TGF-β gene expression in the ileum. The other two strains induced TH1 orientations with high levels of IFN-γ and TNF-α splenocyte secretions.Bifidobacterium's capacity to stimulate immunity is species specific, but its influence on the orientation of the immune system is strain specific.
Pentenolide Analogues of Antifungal Butenolides: Strategies Towards 3,6-Disubstituted Pyranones and Unexpected Loss of Biological Effect
Authors: Šnajdr Ivan , Pavlík Jan , Schiller Radan , Kuneš Jiří , Pour Milan
Published: December 2007

Pentenolide analogues of antifungal 3,5-disubstituted butenolides were prepared by oxidative cyclization of 2-(substituted aryl)hex-5-enoic acids as the key step. Given the limitations of the methodology, another approach to the title compounds based on the Pd-catalyzed carbonylative lactonization of 4-iodo-3-en-1-ols was developed, and the carbonylation conditions were optimized. While the former sequence allows only the introduction of a substituted methyl at C6, pyranones bearing a range of various C-substituents at C6 can be prepared by the latter. Somewhat surprisingly, unlike the corresponding butenolides with the same substitution pattern, the title pentenolides possess no antifungal or cytostatic activity.
Synthesis of Novel Carbocyclic Nucleoside Analogues Derived from 2-(Hydroxymethyl)bicyclo[2.2.1]heptane
Authors: Dejmek Milan , Hřebabecký Hubert , Dračínský Martin , Holý Antonín
Published: December 2007

The key intermediates, [(1R*,2R*,4R*,6R*)-6- (12a) and [(1R*,2R*,4R*,5S*)-5-(hydroxymethyl)- bicyclo[2.2.1]heptan-2-yl]methyl benzoates (12b), were prepared from (1R*,2S*,4R*)- bicyclo[2.2.1]hept-5-en-2-ylmethyl benzoate by hydroboration, oxidation with pyridinium dichromate and subsequent reduction of the thus obtained ketones. The Mitsunobu reaction of12aand12bwith 6-chloropurine afforded 6-chloropurine derivatives, which were converted into others purine analogues. Thymine analogues were prepared from [(1R*,2R*,4S*,6S*)-6- (25a) and [(1R*,2S*,4R*,5S*)-5-aminobicyclo[2.2.1]heptan-2-yl]methanols (25b), which were prepared from alcohols12aand12bin several easy steps.
Bile Acids as Building Blocks of Amphiphilic Polymers. Applications and Comparison with Other Systems
Authors: Durand Alain
Published: December 2007

This review deals with the use of bile acids as building blocks of amphiphilic polymers. These natural polyfunctional organic molecules have been employed in the synthesis of macromolecules combining hydrophilic and hydrophobic sequences. The two main synthetic strategies are radical (co)polymerization after attachment of a vinyl group onto the bile acid and molecule grafting of bile acid onto a hydrophilic polymer. The physicochemical properties of the resulting polymers both as bulk materials and in aqueous solution are reviewed and compared with polymers of other structures. Whenever possible, semiquantitative correlations are established and discussed.
The burden of cancer at work: estimation as the first step to prevention
Authors: Rushton L , Hutchings S , Brown T
Published: December 2007

Objectives:

Work-related cancers are largely preventable. The overall aim of this project is to estimate the current burden of cancer in Great Britain attributable to occupational factors, and identify carcinogenic agents, industries and occupations for targeting risk prevention.

Methods:

Attributable fractions and numbers were estimated for mortality and incidence for bladder, lung, non-melanoma skin, and sinonasal cancers, leukaemia and mesothelioma for agents and occupations classified as International Agency for Research on Cancer (IARC) Group 1 and 2A carcinogens with “strong” or “suggestive” evidence for carcinogenicity at the specific cancer site in humans. Risk estimates were obtained from published literature and national data sources used for estimating proportions exposed.

Results:

In 2004, 78 237 men and 71 666 women died from cancer in Great Britain. Of these, 7317 (4.9%) deaths (men: 6259 (8%); women: 1058 (1.5%)) were estimated to be attributable to work-related carcinogens for the six cancers assessed. Incidence estimates were 13 338 (4.0%) registrations (men: 11 284 (6.7%); women 2054 (1.2%)). Asbestos contributed over half the occupational attributable deaths, followed by silica, diesel engine exhaust, radon, work as a painter, mineral oils in metal workers and in the printing industry, environmental tobacco smoke (non-smokers), work as a welder and dioxins. Occupational exposure to solar radiation, mineral oils and coal tars/pitches contributed 2557, 1867 and 550 skin cancer registrations, respectively. Industries/occupations with large numbers of deaths and/or registrations include construction, metal working, personal and household services, mining (not metals), land transport and services allied to transport, roofing, road repair/construction, printing, farming, the Armed Forces, some other service industry sectors and manufacture of transport equipment, fabricated metal products, machinery, non-ferrous metals and metal products, and chemicals.

Conclusions:

Estimates for all but leukaemia are greater than those currently used in UK health and safety strategy planning and contrast with small numbers (200–240 annually) from occupational accidents. Sources of uncertainty in the estimates arise principally from approximate data and methodological issues. On balance, the estimates are likely to be a conservative estimate of the true risk. Long latency means that past high exposures will continue to give substantial numbers in the near future. Although levels of many exposures have reduced, recent measurements of others, such as wood dust and respirable quartz, show continuing high levels.
Effect of day length on reaction of sunflowers to Verticillium wilt
Authors: Sackston W. E. , Sheppard J. W.
Published: December 2007

Symptoms of Verticillium wilt on inoculated plants of the sunflower cultivar Sunrise appeared sooner and were more severe under long days (16 h light, 8 h dark), or short days with interrupted dark period (10 h light, [Formula: see text] dark, [Formula: see text] light, [Formula: see text] dark), than under short days (10 h light, 14 h dark). Uninoculated control plants flowered in 45 to 47 days under short-day conditions, but reached only the yellow bud stage in 50 to 55 days under long days or short days with interrupted dark period. Development of Verticillium wilt of sunflower is not dependent on the initiation of flowering as it is in some other hosts.
Arctic and alpine agarics from Alaska and Canada
Authors: Miller Jr. Orson K. , Laursen Gary A. , Murray Barbara M.
Published: December 2007

Eight species of agarics in the Basidiomycetes from arctic and alpine tundra in Alaska and adjacent Canada are included. Four taxa are reported from North America for the first time including one new species. One taxon is reported for the first time from arctic tundra in North America. New ecological information, host ranges, and fruiting periods are presented for all taxa. Camera lucida drawings are included for five taxa.
Vegetational heterogeneity during a secondary (postfire) succession
Authors: Shafi M. I. , Yarranton G. A.
Published: December 2007

Areas of boreal forest in the Clay Belt of northern Ontario, burned at a range of times from 0 to 57 years before the present, were examined. The range of vegetation present was sampled by means of a number of plots in each area. A simple test of heterogeneity, based on the number of significant correlations between species, was applied to the data from each area. Vegetation samples and species were each classified into nonexclusive groups, and the properties of the groups explored. Maturity weightings, based on the age of the site at which each species was first detected, were calculated for each sample.The results of analyses indicated the presence of four stages in the succession: (a) initial heterogeneity; (b) early phase; (c) heterogeneous phase; and (d) late phase. Initial heterogeneity, attributable to burning intensity, persists for a year, but is succeeded by a more homogeneous phase dominated by species which survive the fire in various ways. The heterogeneous phase is dominated by environmentally differentiated mosaic elements; it is succeeded by the late phase as a canopy develops and as ephemeral species, which colonized the disturbed area, disappear. The late phase is dominated by jack pine in sandy areas and by black spruce in peaty areas.There is evidence that the changes from one phase to the next are spatially heterogeneous because some sites mature more rapidly than others. The paths of succession at different sites within an area may differ, but there is convergence to one of the two main vegetation types in the late phase. The late phase types are differentiated at a much larger scale than the seral mosaic elements.
The effect of cycloheximide on amide formation in maize roots
Authors: Oaks Ann , Johnson F. J.
Published: December 2007

Cycloheximide inhibits the incorporation of acetate-2-14C into protein and into asparagine in corn root tips. It also causes an accumulation of glutamine and, over a concentration range of 0.4 to 5.0 μg/ml, a transient accumulation of the neutral and basic amino acids. In mature sections, cycloheximide inhibits protein synthesis but causes an increase in the incorporation of radioactivity into both glutamine and asparagine. Azaserine, a glutamine analogue, also inhibits the formation of asparagine in root-tip sections but has only a minor effect on protein synthesis. In mature root sections, there is an accumulation of glutamine but no effect on asparagine formation when azaserine is used. Glutamine additions to root tips or mature root sections affect neither asparagine formation nor protein synthesis. We conclude that cycloheximide is behaving as a glutamine analogue in its effect on asparagine biosynthesis, and that its effect as a glutamine analogue is lost as cells mature.
Foliar nutrition and wood growth in red pine: effects of darkening and defoliation on the distribution of 14C-photosynthate in young trees
Authors: Rangnekar P. V. , Forward D. F.
Published: December 2007

Young red pine trees were supplied with 14CO2 through a branch in the third whorl. Darkening or removal of all other needles caused a major diversion of 14C to the expanding terminal shoot. Defoliation had a much greater effect than darkening. The diversion can be only partially explained on the basis of removal of competing sources of carbohydrate. Use as well as distribution of labeled photosynthate was affected by the treatments.
The conidial state of Xylaria johorensis
Authors: Morgan-Jones G. , Hashmi M. H.
Published: December 2007

The conidial state of Xylaria johorensis is described from pure culture. Because of a close morphological similarity between both the perfect and conidial state of the fungus and species of Poronia, it is transferred to that genus.
Growth of the flax rust Melampsora lini on chemically defined media
Authors: Turel Franziska L. M.
Published: December 2007

Good saprobic growth of primary and established cultures of Melampsora lini (Ehrenb.) Lév., race 3, was obtained on chemically defined media containing modified Knop's minerals, various trace elements, 5% sucrose, and aspartic acid. Cysteine, cystine, and glutathione had to be added to the base medium singly or in combination. Alanine and methionine, added to minerals and sucrose, supported only sporadic and slow growth of primary flax rust cultures; and established cultures started on media containing more complex amino acid mixtures did not survive on the alanine–methionine medium. Types and concentrations of essential amino acids determined the rate of mycelial growth.
Cryofixation reveals uniqueness of reddish-purple sequent periderm and equivalence between brown first and brown sequent periderms of three conifers
Authors: Mullick D. B. , Jensen G. D.
Published: December 2007

Three types of periderms, brown first periderm (bfp), reddish-purple sequent periderm (rsp), and brown sequent periderm (bsp) were distinguished in Abies amabilis, Abies grandis, and Tsuga heterophylla. The distinctions are based on 15 characteristics revealed largely by extension of a new cryofixation technique with various modes of illumination. On the bases of bright-yellow and pale-blue fluorescent substances in phellem cells, bright-yellow fluorescent substances in phellem walls, distinctive chemical nature of the pigments, presence of phellogen activity marker cells, and specificity of the site of occurrence next to rhytidome and several other cryofixation characteristics, rsp is established not only as distinctly different from bfp and bsp, but also as unique. Both bfp and bsp were found to be similar in all 15 characteristics, revealed by cryofixation and other techniques and thus may have similar physiological roles. This similarity implicates the incompleteness of the term first periderm.
Ultrastructure of sterigma growth and basidiospore formation in Coprinus and Boletus
Authors: McLaughlin David J.
Published: December 2007

In basidia of Coprinus cinereus and Boletus rubinellus at early interphase II of meiosis numerous microtubules are oriented longitudinally in the sterigmata. Their orientation in the rest of the cell is predominantly parallel to the long axis. In Coprinus cinereus cytoplasmic vesicles, apparently derived from Golgi cisternae, are involved in tip growth of the sterigmata and basidiospore growth. Additional information is provided on the Golgi apparatus in the basidium, and the role of microtubules and microbodies is discussed.
Morphology of Nicotiana tabacum cells grown in contact with lunar material
Authors: Baur P. S. , Walkinshaw C. H. , Halliwell R. S. , Scholes V. E.
Published: December 2007

Suspension and stationary habituated tobacco tissue cultures were examined histologically and cytologically after treatment with 0.22 g of lunar material. The treated and untreated tissues differed in chloroplast structure and distribution, degree of cell association, cytoplasmic vacuolation and vesiculation, and living to nonliving ratios.
Possible mechanism of gibberellin-induced chlorosis in lettuce seedlings
Authors: Das Gaurangakumar
Published: December 2007

Effects of gibberellin A3 (GA) on growth, pigments, protein, and nucleic acid content of the cotyledons of lettuce seedlings (Lactuca sativa L. cv. Grand Rapids) are reported. GA treatment increased both the total shoot and cotyledon fresh weights, and decreased chlorophyll content per cotyledon and on a dry weight basis. GA also decreased the protein content of the cotyledon, but increased the level of RNA and DNA measured on a dry weight basis. The hormone had no effect on the pheophytin: chlorophyll ratio, but increased the ratios of chlorophyll a: chlorophyll b, phytol: chlorophyll, and carotene: chlorophyll. GA also increased the sugar content of the cotyledons. Treatment of excised cotyledons with glucose had an effect similar to that of GA on chlorophyll and protein content. The data are discussed in relation to the mechanism of GA-induced chlorosis.
Desiccation and protein synthesis in the moss Tortilla ruralis
Authors: Bewley J. Derek
Published: December 2007

Toriula ruralis, when subjected to various drying conditions, loses water until it maintains around 20% of its original fresh weight. On reintroduction to water, uptake is completed within 90 s. Prolonged desiccation of the moss for 10 months resulted in no adverse effects on its capacity to resume protein synthesis rapidly on rehydration.
Sporulation mutants in Cochliobolus carbonum
Authors: Leonard K. J.
Published: December 2007

Three types of mutants were induced in cultures of Cochliobolus carbonum by ultraviolet irradiation. The mutant C1 abc formed abnormally shaped conidia which proliferated in chains rather than being arranged in a spiral on the conidiophore as in wild-type isolates; a second mutant, C2 pcg, produced conidia which germinated precociously while still attached to the conidiophore and which formed secondary conidia at the ends of short germ tubes; and the third, C1 nc1, formed no conidia. A fourth mutant, C1 nc2, which also failed to form conidia was isolated from a culture grown on a medium containing acriflavin. A 1: 1 segregation ratio was obtained in crosses of C1 abc × wild type, but in crossesC2 pcg × wild type and C1 nc1 × wild type nearly all of the progeny were wild type. The mutants C2 pcg and C1 nc1 failed to form perithecia but could serve as male parents; C1 nc2 was completely infertile. Preliminary attempts to determine whether the pcg and nc mutants were controlled cytoplasmically were inconclusive.
Nematophagous fungi: Meristacrum
Authors: Davidson J. G. N. , Barron G. L.
Published: December 2007

Conidia of Meristacrum asterospermum were found to be forcibly ejected, supporting the position of this fungus in the Entomophthoraceae. Conidia adhering to the integument of a live nematode either penetrate directly by a germ tube or germinate externally and produce secondary conidia. Resting spores germinate and produce a single erect conidiophore similar to those produced by thallodic segments.
Coniophora: study of 22 type specimens
Authors: Ginns James H.
Published: December 2007

The type specimens of 24 epithets of Coniophora were studied and most are redescribed. Eleven names are excluded from Coniophora. Seven are Hymenomycetes of uncertain generic position: C. albo-olivacea Rick, C. harperi Burt, C. indica Massee, C. janthinospora (Pat.) Sacc. & Trav., C. lichenoides Massee, C. stratalis Massee, and C. viridis (Berk.) Cooke ex Sacc. In addition, C. broomeiana Massee is not a basidiomycete; C. lateritia Speg. is a nomen dubium; C. murina is Septobasidium murina (Berk. & Br.) Petch; and C. stereoidea Rick is a Gloeocystidiellum. Thirteen epithets are placed in synonymy with other Coniophora names: Coniophora berkeleyi Massee, C. betulae P. Karst., C. macra (P. Karst.) P. Karst., C. arida subsp. macra P. Karst., and C. subdealbata (Berk. & Br.) Massee all as C. suffocata (Peck) Massee; C. cookei Massee and C. subcinnamomea P. Karst. both as C. arida (Fr.) P. Karst.; C. kalmiae (Peck) Burt, C. luteocincta (Berk.) Cooke ex Sacc, C. lurida P. Karst., and C. arida var. lurida (P. Karst.) P. Karst. all as C. puteana (Fr.) P. Karst.; C. inflata Burt as C. submembranacea (Berk. & Br.) Cooke ex Sacc.; and C. betulae var. eucalypti Bres. & Torrend as C. hanoiensis Pat.
The origin and extent of discolouration and decay in stems of young regrowth eucalypts in southern Tasmania
Authors: Wardlaw Timothy J.
Published: December 2007

Two hundred thirteen potential sawlog trees from 22- to 34-year-old Eucalyptusregnans F. Muell. and Eucalyptusdelegatensis R.T. Baker regrowth forests from four sites in southern Tasmania were felled, dissected, and assessed for discolouration and decay. Of the aboveground origins, branches accounted for more than half of the discolouration and decay both in terms of incidence and volume. Stem-boring insects and branch crotches were the source of most of the remaining aboveground decay. Butt rots accounted for only 7% of the columns of discolouration and decay, but their incidence showed considerable local variation such that on some plots they accounted for more than 20% of the total volume of discolouration and decay in the bottom 6 m of the stem. Decay in individual trees was 0 to 17.5% of total volume, with a mean of 1.3%. Only 12% of the trees were completely free of discolouration and decay, while 25% of the trees had discolouration and decay in more than 1.5% of the total stem volume. Whilst both the incidence and percent volume of decay showed considerable, and often statistically significant, variation both among sites and locally, among plots within sites, the greatest proportion of the variation was tree to tree. Our ability to limit future timber losses resulting from decay will require that those site, stand, and most importantly, tree factors that influence the prevalence of, and susceptibility to, decay in eucalypts are identified.
Recovering time trends in dominant height from stem analysis
Authors: Magnussen S. , Penner M.
Published: December 2007

Site-index curves derived from stem analysis of trees with dominant height at the time of selection will underestimate dominant height of young trees and thus overestimate the performance and yield expectations of young stands. A simple model-based adjustment procedure is presented and tested on two artificial populations and two data sets from repeatedly measured plots. To recover a less biased height–age curve of dominant trees, estimates are needed of age–age correlations and the sampling intensity (standardized height difference) applied to the selection of site trees for stem analysis. Adaptation to different definitions of dominant height is possible. Results confirmed that the recovery procedure is very effective in reducing the relative bias. Bias reduction in excess of 40% can be expected during the first half of a rotation. Small but insignificant increases in bias were encountered during the second half of a rotation.
Effects of basal area or density as sampling metrics on oak woodland cluster analyses
Authors: Mehlert Svenje , McPherson Guy R.
Published: December 2007

This study compared the effects of sampling metrics (basal area and density of trees) on cluster analyses of oak woodland vegetation. Minimum-variance clustering was used to define communities within oak woodlands. Communities derived from basal area data were more distinct and more homogeneous than communities derived from density data. Consistent with previous research, minimum-variance clustering of basal area data produced groups of approximately equal size. In contrast, minimum-variance clustering of density data did not result in similar-sized groups. Formation of similar-sized groups, which is generally reported to be an advantage of minimum-variance clustering, apparently is dependent on the sampling metric employed.
Generalizing forest regeneration models: the dependence of propagule availability on disturbance history and stand size
Authors: Peterson Chris J. , Carson Walter P.
Published: December 2007

We summarize three existing conceptual frameworks for forest regeneration in northeastern North America and suggest that none consider both a range of disturbance characteristics and a range of forest conditions at the time of disturbance. We offer a more general conceptual model, within which the existing models can be seen as special cases. We propose that the abundance of characteristic seed–bank, pioneer species, such as Prunuspensylvanica L.f. and Rubus spp. (often Rubusallegheniensis T.C. Porter, Rubushispidus L., or Rubusodoratus L.), is dependent on propagule availability, which in turn is determined by forest age and size. Specifically, following disturbance, large tracts of forest and older forests (ca. >125 years) are predicted to have very low densities of the above pioneers. As a result, population, community, and ecosystem parameters may be substantially different in the regenerating forest than in the familiar cases of regeneration in secondary forests. Indeed, the presettlement forest of much of northeastern North America may have experienced a notable scarcity of pioneers after disturbances, in areas far enough inland for hurricanes to be unimportant. Our hypothesis makes predictions of seed-bank abundance that are well supported in a variety of forest types; we also provide support for our hypothesis with data on regeneration following catastrophic windthrow in Allegheny National Forest, Pennsylvania, and elsewhere. Finally, our hypothesis also predicts that the potential regeneration in much of the secondary forest of northeastern North America should profoundly shift as stands age from roughly 100 to 130 years.
The effects of drainage on substrate water content at several forested Alberta peatlands
Authors: Rothwell R.L. , Silins U. , Hillman G.R.
Published: December 2007

Hydrologic drainage criteria that describe the position of the water table between adjacent ditches are commonly used to assess the initial effectiveness of peatland drainage projects for tree growth improvement. However, these criteria do not reflect the soil conditions that regulate tree growth and performance after drainage. The effect of three drainage ditch spacings (30, 40, and 50 m) on the spatial variability of soil water conditions at three drained boreal Alberta peatlands was studied. Soil water content (0–30 cm depth) was found to be insensitive (p = 0.686) to drainage ditch spacing several years after drainage. Greater variation was observed between different sampling locations (p = 0.024) relative to the position of the ditch edge within similar ditch spacings. Spatial distribution of soil water in the unsaturated zone was found to be inversely related to the degree of water table lowering. Spatial patterns of soil water content were strongly associated with changes to substrate bulk density resulting from post-drainage peatland subsidence.
Spatial autocorrelation of allozyme traits in a Norway spruce (Piceaabies) population
Authors: Leonardi Stefano , Raddi Sabrina , Borghetti Marco
Published: December 2007

Using isoenzymes as gene markers and spatial autocorrelation analysis as a tool to detect spatial patterns, we studied the spatial distribution of genotypes in a naturally regenerated uneven-aged Norway spruce (Piceaabies (L.) Karst.) stand on the eastern Italian Alps. In most cases we found a random distribution of genotypes in space; in the whole data set less than 11% of genotype pairs showed positive associations for the first (10 m) distance class. Extensive gene flow, due to long distance dispersal of pollen and seeds in P. abies, may account for the observed spatial patterns. A few genotypes (GotB-22, LapB-23, LapB-24, SkdB-12, and MnrB-12) showed a significant clumped distribution over a small spatial scale. We suggested that selection processes driven by environmental variability might have produced significant clumping of these genotypes. However, the role of factors linked to the breeding system, and of chance events, in determining the population spatial structure cannot be excluded in our study.
Operationalization of biological diversity as a decision objective in tactical forest planning
Authors: Kangas Jyrki , Pukkala Timo
Published: December 2007

An approach for including biological diversity in calculations of multiobjective forest planning is described. This makes it possible to consider biodiversity as a decision objective among multiple objectives in tactical forest planning. Biodiversity is operationalized by decomposing it into measurable environmental components that describe its dimensions. The relative importance of the components is assessed via pairwise comparisons. The relationship between the value of the component and the overall biodiversity is estimated and described for each component as a subpriority function. The relationship can be nonlinear. A biodiversity index is calculated for each alternative forest plan based on the components and their weighting, the subpriority functions, and the predicted qualities of the forest area when implementing the plans. The approach is illustrated by a case study. Using this approach, the relationship between biodiversity and the other objective variables, as well as the effects of the components of biodiversity, can be analyzed numerically.
Influence of forest herbicide on snowshoe hare population dynamics: reproduction, growth, and survival
Authors: Sullivan Thomas P.
Published: December 2007

This study was designed to assess the influence of forest applications of glyphosate herbicide on reproduction, growth, and survival in snowshoe hare (Lepusamericanus Erxleben) populations in control (reference) and treatment habitats near Prince George, B.C. Proportion of adult hares in breeding condition and number of successful pregnancies showed no consistent differences between control and treatment populations. Recruitment of hares was generally similar except for significantly more juvenile females entering the control than treatment population at one study area. At a second study area, total recruitment was significantly higher in the treatment than control population for both sexes in 1990 and for adult females in 1991, the 2 post-treatment years. There was little difference in survival of hares between control and treatment populations. Lack of significant differences in mean body mass and growth rates suggested that this herbicide treatment had little or no effect on metabolic or general physiological processes in the development of young hares. Similar profiles of body mass distribution between control and treatment populations indicated that comparable levels of biomass of hares were available as prey for predators. Use of this forest herbicide did not measurably affect demographic parameters of snowshoe hare populations.
Crown structure in western hemlock, Douglas-fir, and grand fir in western Washington: horizontal distribution of foliage within branches
Authors: Kershaw Jr. John A. , Maguire Douglas A.
Published: December 2007

Horizontal distribution of foliage within individual branches was explored for three major tree species (western hemlock (Tsugaheterophylla (Raf.) Sarg.), Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), and grand fir (Abiesgrandis (Dougl. ex D. Don) Lindl.)) in the Pacific Northwest. Weibull, β, normal, and Johnson's SB distributions were assessed for their ability to conform to the empirical foliage distributions. Moment-based parameter recovery and parameter prediction methodologies were applied. On the basis of the rank of individual branch χ2-values, the β distribution performed best under parameter recovery, while Johnson's SB distribution was best in terms of total sum of χ2-values. Overall, few differences between the four distributions were observed. A system of moment-based parameter prediction equations was developed from branch dimensional and positional measures. The prediction equations showed that the ratio of relative distance from the stem to mean foliage density increased with increasing branch size. This relative increase was enhanced with increasing depth into crown for western hemlock, but not for Douglas-fir or grand fir. Again, the β distribution, based on predicted moments, followed most closely the empirical distributions on the basis of the ranks of χ2-values. The normal distribution was the best in terms of total sum of χ2-values. As expected, moment-based parameter recovery produced smoothed distributions that followed more closely the observed empirical distributions; however, parameter prediction provides a methodology for predicting distributions when empirical moments are not available. No significant (p > 0.05) differences in horizontal foliage distribution were found between sites or fertilization treatments.