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At least 433 records · Page 24Linked to original sources
PubMed2003

Brassinolide improves embryogenic tissue initiation in conifers and rice.

Somatic embryogenesis (SE), the most promising technology for the large-scale production of high-value coniferous trees from advanced breeding and genetic engineering programs, is expected to play an important role in increasing productivity, sustainability, and the uniformity of future U.S. forests. To be successful for commercial use, SE technology must work with a variety of genetically diverse trees. Initiation in loblolly pine ( Pinus taeda L.), our main focus species, is often recalcitrant for desirable genotypes. Initiation percentages of loblolly pine, Douglas-fir [ Pseudotsuga menziesii (Mirb.) Franco], and Norway spruce ( Picea abies L., Karst.) were improved through the use of brassinolide. Brassinosteroids, which include brassinolide, are a relatively new group of natural plant growth regulators that are found in many plant species. They have been shown to have diverse, tissue-specific, and species-specific effects, including the stimulation of cell elongation and ethylene production and increasing resistance to abiotic stress. In our media, brassinolide was effective at concentrations ranging from 0.005-0.25 micro M. Using control medium (no brassinolide) and brassinolide-supplemented (0.1 micro M) medium, we achieved improved initiation percentages in loblolly pine, Douglas-fir, Norway spruce, and rice-15.0% to 30.1%, 16.1% to 36.3%, 34.6% to 47.4%, and 10%, respectively. Brassinolide increased the weight of loblolly pine embryogenic tissue by 66% and stimulated initiation in the more recalcitrant families of loblolly pine and Douglas-fir, thus compensating somewhat for genotypic differences in initiation. Initiation percentages in loblolly pine were improved through the combination of modified 1/2-P6 salts, 50 mg/l activated carbon (AC), adjusted levels of Cu and Zn (to compensate for adsorption by AC), 1.5% maltose, 2% myo-inositol (to raise the osmotic level, partially simulating the megagametophyte environment), 500 mg/l casamino acids, 450 mg/l glutamine, 2 mg/l alpha-naphthaleneacetic acid, 0.63 mg/l 6-benzylaminopurine, 0.61 mg/l kinetin, 3.4 mg/l silver nitrate, 10 micro M cGMP, 0.1 micro M brassinolide, and 2 g/l Gelrite. Across 12 open-pollinated families of loblolly pine, initiation percentages ranged from 2.5% to 50.7%, averaging 22.5%.

Brassinosteroids↗
PubMed2006

Ethylene in induced conifer defense: cDNA cloning, protein expression, and cellular and subcellular localization of 1-aminocyclopropane-1-carboxylate oxidase in resin duct and phenolic parenchyma cells.

Members of the Pinaceae family have complex chemical defense strategies. Conifer defenses associated with specialized cell types of the bark involve constitutive and inducible accumulation of phenolic compounds in polyphenolic phloem parenchyma cells and oleoresin terpenoids in resin ducts. These defenses can protect trees against insect herbivory and fungal colonization. The phytohormone ethylene has been shown to induce the same anatomical and cellular defense responses that occur following insect feeding, mechanical wounding, or fungal inoculation in Douglas fir (Pseudotsuga menziesii) stems (Hudgins and Franceschi in Plant Physiol 135:2134-2149, 2004). However, very little is known about the genes involved in ethylene formation in conifer defense or about the temporal and spatial patterns of their protein expression. The enzyme 1-aminocyclopropane-1-carboxylate oxidase (ACO) catalyzes the final step in ethylene biosynthesis. We cloned full-length and near full-length ACO cDNAs from three conifer species, Sitka spruce (Picea sitchensis), white spruce (P. glauca), and Douglas fir, each with high similarity to Arabidopsis thaliana ACO proteins. Using an Arabidopsis anti-ACO antibody we determined that ACO is constitutively expressed in Douglas fir stem tissues and is up-regulated by mechanical wounding, consistent with the wound-induced increase of ethylene levels. Immunolocalization showed cytosolic ACO is predominantly present in specialized cell types of the wound-induced bark, specifically in epithelial cells of terpenoid-producing cortical resin ducts, in polyphenolic phloem parenchyma cells, and in ray parenchyma cells.

Amino Acid Oxidoreductases↗
PubMed1998

Sequence and expression of embryogenesis-specific cDNAs encoding 2S seed storage proteins in Pseudotsuga menziesii [Mirb.] Franco.

Differential screening of a cDNA library constructed from polyadenylated RNA from developing Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) seeds resulted in the isolation of four full-length cDNA clones (PM2S1, PM2S2, PM2S3 and PM2S4) encoding isoforms of 2S seed storage proteins. The deduced amino acid sequences had low similarity to the angiosperm 2S storage proteins such as 2S albumin, napin and alpha-amylase/trypsin inhibitor yet contained all conserved cysteines in an arrangement suggestive of a structural similarity between the 2S seed storage proteins from gymnosperms and angiosperms. Southern blot analysis of genomic DNA suggested that the Douglas-fir 2S seed protein genes consisted of at least two sub-families, each including several gene members. Northern blot analysis revealed that all four PM2S mRNAs were present specifically in seeds and temporally during seed development. However, the decline in PM2S2 mRNAs in the megagametophytes occurred before that of the other mRNAs, suggesting that their gene expression was regulated differentially. The accumulation of PM2S transcripts in the haploid megagametophytes started during early embryogenesis and reached a peak before that in diploid zygotic embryos. The mRNAs for PM2S were present in Douglas-fir somatic embryos at the same developmental stages as those in the zygotic embryos, and abscisic acid and osmoticum stress were necessary for the expression of PM2S genes in somatic embryos.

Abscisic Acid↗
PubMed1984

Evaluation of the pulmonary effects of wood smoke in guinea pigs by repeated CO2 challenges.

Male, English smooth haired guinea pigs were exposed to thermal decomposition products, i.e., smoke, generated by heating Douglas fir in an open system. Various amounts of Douglas fir were placed in a furnace, at room temperature, and heated at a rate of 11 degrees C/min until completely decomposed. Major decomposition occurred between 160 and 490 degrees C, and the animals were exposed during this time for a period of 30 min. Immediately before exposure and at various times after exposure, each animal was evaluated by whole-body plethysmography to measure tidal volume and respiratory frequency during air breathing as well as during challenge with 10% CO2. Exposure to smoke from Douglas fir resulted in a diminished ventilatory response to 10% CO2. Comparing the effect of wood smoke to the effect of smoke from polyvinylchloride from previous experiments wood smoke was found to be 10 times less potent than smoke from polyvinylchloride and animals recovered much more rapidly than with smoke from polyvinylchloride.

Animals↗
PubMed1990

Analyses of enzyme activities and other metabolic criteria after five years of fumigation.

Enzymatic activity (peroxidase, glutamate dehydrogenase, glutamine synthetase), foliage buffering capacity, soluble protein and nitrogen content were measured in current and previous year needles from young spruce (Picea abies) and fir (Abies alba). The trees were exposed to low levels of SO(2) and/or O(3) and simulated acidic precipitation (pH 4.0) in open-top chambers from 1983 through 1988. Needle samples were taken during March 1988 at the end of the five-year fumigation period. Exposure to SO(2) substantially increased sulphur content in both needle age classes of spruce and fir, and concomitantly reduced the foliage buffering capacity index (BCI), whereas the combined fumigation with SO(2) and O(3) had no effect on BCI. Peroxidase activity was markedly higher in year-old needles compared to current-year needles. However, trees from the SO(2) and SO(2) + O(3) treatments exhibited statistically significant stimulated peroxidase activities. Similarly, changes in the activities of the nitrogen-metabolizing enzymes indicated an altered cellular function of the trees after the long-term pollution stress. Levels of activity of both glutamate dehydrogenase and glutamine synthetase were increased by exposure to SO(2), especially in spruce. Although glutamate dehydrogenase in spruce was affected by all treatments, such changes in activity were found in fir only with the SO(2) treatment. The highest activity of glutamine synthetase, however, occurred in the older needles of trees exposed to SO(2) + O(3). Total nitrogen concentration was either unaffected by the pollutant treatments or decreased in spruce compared to the controls. No statistically significant changes due to the fumigation were found in soluble protein concentrations. Results indicated that chronic exposure to air pollutants lead to alterations in metabolic processes in conifer needles, detectable either by changes in typical stress indicating values or by increases in ammonium assimilation capacity.

Journal Article↗
PubMed1990

Visible injury responses.

During a five year experiment on the causes of forest disease, symptoms of visible injury and pest infestations in trees treated with various air pollutants in open-top chambers were observed. Though the long-term experiment was originally not intended to include such investigations, insect infestation and some discoloration of the trees (Beech, Fagus sylvatica; Fir, Abies alba; Spruce, Picea abies) could not be avoided. Abundance and size of some of the insects were measured after two years and at the end of the experiment. Because it was unknown when the first infestation in the chambers occurred, quantitative investigations of the population size provided little information. Visible injury on leaves and needles was infrequent in general. When it occurred, it appeared to be caused by at least three stress factors. However, three different types of symptoms on beech and fir could be attributed mainly to air pollutants. These symptoms consisted of two types of foliar necrosis and browning in beech and needle tip chlorosis in fir. These symptoms have been observed under certain conditions in the German forests. The spruce clone used, however, developed no injuries which could be connected definitely to treatment effects.

Journal Article↗
PubMed1990

Fine root studies in situ and in the laboratory.

The fine roots and myocorrhizae of beech, spruce and fir trees exposed to ozone, sulphur dioxide and simulated acid precipitation in open-top chambers (OTC) were examined both in situ by rhizoscopy and in the laboratory using root samples from soil cores. Prior to measurements the trees were treated for about one year. During the second year of treatment the fine root production of all three tree species was determined rhizoscopically. The OTC experiments were concluded after an additional three years at which time fine root and small root dry matter as well as the absolute and relative frequencies of mycorrhizae of spruce and fir were determined from soil cores. The vitality of spruce mycorrhizae was examined by fluorescein diacetate staining. In addition total contents of essential cations of spruce mycorrhizae were measured. Long-term exposure to SO(2), SO(2) + O(3), and simulated acid precipitation led to an increased mycorrhizal production by fir. On spruce, a decreased number of mycorrhizae was found in the chambers polluted with SO(2), but a high proportion of dead fine roots indicated an increased root production with an intensified turnover or a delayed decomposition of spruce mycorrhizae. The cation analyses showed an accumulation of Ca(2+) and Zn(2+) in the mycorrhizae of spruce exposed to ozone.

Journal Article↗
PubMed1993

The effects of atmospheric nitrogen deposition and soil chemistry on the nutritional status of Pseudotsuga menziesii, Pinus nigra and Pinus sylvestris.

The ammonium content and the base cation content, expressed relative to ammonium, are enhanced in the soil of Dutch forests, due to the extremely high deposition of ammonium to the forest floor. A nation-wide investigation was carried out to establish whether and how these changed nitrogen fluxes in deposition and soil affect the nutritional status of coniferous trees. The chemical composition of needles of Douglas fir, Scots pine and Corsican pine showed a regional trend similar to that of deposition and soil solution. Particularly nutrients, expressed relative to nitrogen, decreased from North to South. Of the macronutrients phosphorus was most often deficient and therefore probably limiting in the Douglas fir stands. Many pine trees suffered from relative magnesium shortages. In all stands, magnesium and, in Douglas stands, also phosphorus contents of the needles were negatively correlated with ammonium and ammonium/cation ratios in deposition. However, in contrast to pine trees, nutrient contents in needles of Douglas fir showed correlation with nitrate rather than with ammonium in the soil solution. Correlation analyses indicate that nitrogen fluxes in the soil, indirectly affect the nutritional status of coniferous trees.

Journal Article↗
PubMed1993

Effects of acidic fog on seedlings of Pinus ponderosa and Abies concolor: foliar injury, physiological and biochemical responses.

Seedlings of Pinus ponderosa (ponderosa pine) and Abies concolor (white fir) were exposed to acidic fog (pH 2.0, 3.0 or 4.0) in open-field plots for six weeks. The two species exhibited dissimilar injury responses; neither current year nor previous year needles of ponderosa pine were injured by pH 2.0 fog, but current year needles exhibited higher membrane permeability responses (i.e. needle extract conductivity, K+ concentration). In comparison, both needle age classes in white fir were significantly injured by pH 2.0 fog, but no significant effects on membrane permeability were observed. For both species, whole-study average rates of net photosynthesis in previous year needles were lower in plants exposed to pH 2.0 fog than in plants treated with pH 4.0 fog. While decreased process rates coincided with leaf necrosis in white fir, stomatal closure appeared to be the mechanism of inhibition in ponderosa pine with pH 2.0 fog (i.e. no visible injury). The findings of the present study provide evidence that frequent applications of highly acidic fog (i.e. pH 2.0-3.0) can cause temporal alterations in membrane permeability and gas exchange rates in western conifer seedlings, in the presence or absence of visible injury. However, because incipient effects on other measures of foliage health were species-specific (i.e. concentrations of starch, photosynthetic pigments, inorganic nutrients), a general mechanism of phytotoxicity could not be identified.

Journal Article↗
PubMed1996

Synthesis of an anaesthetic agent administration system using fuzzy inductive reasoning.

Control of the depth of anaesthesia is a difficult undertaking. Progress has been made during recent years by use of different methodologies and monitoring systems that suggest the safe amount of an anaesthetic drug, considering the condition of an individual patient. Despite these improvements, anaesthetists still rely heavily on personal experience when suggesting the anaesthetic dosage during surgical operations. The purposes of this paper are twofold. One is a description of the design of an anaesthetic agent control system using a qualitative modelling and simulation methodology called Fuzzy Inductive Reasoning (FIR). A comparison with a system developed for the same application using a neural network approach is also presented. The second purpose is a discussion of the problem of separating system-generic from patient-specific behaviour in the context of inductive modeling using the FIR methodology. In order to be useful, the model generated by FIR should reflect upon system-generic behavioural characteristics exclusively, while suppressing patient-specific behavioural patterns. A technique based on combining knowledge obtained from different patients is designed that makes it possible to derive a single model characterizing a specific class of similar patients undergoing similar operations, preserving the common characteristics of all these patients while filtering out the specific behavioural patterns of any one of the individual patients from whom the data were obtained.

Anesthetics↗
PubMed2004

Chemical and morphological characteristics of key tree species of the Carpathian Mountains.

Concentrations of Al, B, Ca, Cu, Fe, K, Mg, Mn, N, Na, P, S and Zn in the foliage of white fir (Abies alba), Norway spruce (Picea abies) and common beech (Fagus sylvatica) from 25 sites of the Carpathian Mts. forests (Czech Republic, Poland, Romania, Slovakia and Ukraine) are discussed in a context of their limit values. S/N ratio was different from optimum in 90% of localities when compared with the European limit values. Likewise we found increase of Fe and Cu concentrations compared with their background levels in 100% of locations. Mn concentrations were increased in 76% of localities. Mn mobilization values indicate the disturbance of physiological balance leading to the change of the ratio with Fe. SEM-investigation of foliage waxes from 25 sites in the Carpathian Mts. showed, that there is a statistically significant difference in mean wax quality. Epistomatal waxes were damaged as indicated by increased development of net and amorphous waxes. The most damaged stomata in spruce needles were from Yablunitsa, Synevir and Brenna; in fir needles from Stoliky, and in beech leaves from Malá Fatra, Morské Oko and Beregomet. Spruce needles in the Carpathian Mts. had more damaged stomata than fir needles and beech leaves. Spruce seems to be the most sensitive tree species to environmental stresses including air pollution in forests of the Carpathian Mountains. Foliage surfaces of three forest tree species contained Al, Si, Ca, Fe, Mg, K, Cl, Mn, Na, Ni and Ti in all studied localities. Presence of nutrition elements (Ca, Fe, Mg, K and Mn) on foliage surface hinders opening and closing stomata and it is not physiologically usable for tree species.

Abies↗
PubMed2004

Genetic effects of air pollution on forest tree species of the Carpathian Mountains.

The effects of air pollution on the genetic structure of Norway spruce, European silver fir and European beech were studied at four polluted sites in Slovakia, Romania and Czech Republic. In order to reduce potential effects of site heterogeneity on the health condition, pair-wise sampling of pollution-tolerant and sensitive trees was applied. Genotypes of sampled trees were determined at 21 isozyme gene loci of spruce, 18 loci of fir and 15 loci of beech. In comparison with Norway spruce, fewer genetic differences were revealed in beech and almost no differentiation between pollution-tolerant and sensitive trees was observed in fir. In adult stands of Norway spruce, sensitive trees exhibited higher genetic multiplicity and diversity. The decline of pollution-sensitive trees may result thus in a gradual genetic depletion of pollution-exposed populations of Norway spruce through the loss of less frequent alleles with potential adaptive significance to altered stressing regimes in the future. Comparison of the subsets of sensitive and tolerant Norway spruce individuals as determined by presence or absence of discolorations ("spruce yellowing") revealed different heterozygosity at 3 out of 11 polymorphic loci.

Abies↗
PubMed2004

Vegetation of the selected forest stands and land use in the Carpathian Mountains.

Within the framework of the project "Effects of forest health on biodiversity with emphasis on air pollution in the Carpathian Mountains" 26 permanent study sites were established in the vicinity of the ozone monitoring sites. The study sites were located on the NW-SE transect through the Western (12 sites), Eastern (11 sites) and Southern (3 sites) Carpathians in forest ecosystems typical of each area. Some of the forest monitoring sites were located in national parks, biosphere reserves and areas of protected landscape. Each permanent site of 0.7 ha area consisted of 5 small 500m(2) circular plots, arranged in the form of a cross, i.e. four placed on the cardinal points (N, E, S, W) and one in the center. Phytosociological records were done twice during the 1998 growing season using the Braun-Blanquet's method. The study sites represented various types of forest: Picea abies stands (8), beech (Fagus sylvatica) stands (10), fir (Abies alba) stands (2) and mixed beech-fir, spruce-fir and beech-spruce stands (6). Age of most stands was 80-100 years. Degree of crown damage varied greatly between sites, a percentage of damaged trees decrease in Carpathians from West to East. It corresponds well with the O(3) level in these areas. Typical damage by O(3) in herb layer species in several Carpathian sites were found. Land-use map for the entire Carpathian Mountains and two detailed land use maps for Tatras (Western Carpathians) and Retezat (Southern Carpathians) are presented. A little more than half of the Carpathian territory is forested. The most densely forested are Eastern Carpathians, while the most sparsely Western Carpathians. Arable lands occupy 22.6% of the Carpathians, pastures and meadows 6.2%, water bodies 1.9%, and build up areas several percent. In the highest elevation of the Carpathians alpine meadows (11.3%) and rocks (3.5%) are distributed.

Agriculture↗
PubMed2006

Diterpene resin acid biosynthesis in loblolly pine (Pinus taeda): functional characterization of abietadiene/levopimaradiene synthase (PtTPS-LAS) cDNA and subcellular targeting of PtTPS-LAS and abietadienol/abietadienal oxidase (PtAO, CYP720B1).

Diterpene resin acids are prominent defense compounds against insect pests and pathogens in conifers. Biochemical and molecular analyses in grand fir (Abies grandis), Norway spruce (Picea abies), and loblolly pine (Pinus taeda) have identified two classes of genes and enzymes that generate much of the structural diversity of terpenoid defense compounds: The terpenoid synthases (TPS) and cytochrome P450 monooxgenases (P450). Using a single substrate, geranylgeranyl diphosphate, families of single-product and multi-product diterpene synthases generate an array of cyclic diterpene olefins. These diterpenes are converted to diterpene resin acids by activity of one or more P450 enzymes. A few conifer diterpene synthases have previously been cloned and characterized in grand fir and in Norway spruce. We have also previously shown that the loblolly pine P450 abietadienol/abietadienal oxidase (PtAO) catalyzes multiple oxidations of several diterpene alcohols and aldehydes. Conifer diterpene synthases are thought to function in plastids while P450s can also be localized to plastids or to the endoplasmic reticulum (ER). Here, we show that a loblolly pine cDNA (PtTPS-LAS) encodes a typical multi-product conifer diterpene synthase that forms levopimaradiene, abietadiene, palustradiene, and neoabietadiene similar to the grand fir abietadiene synthase and Norway spruce levopimaradiene/abietadiene synthase. Subcellular targeting of PtTPS-LAS and PtAO to plastids and ER, respectively, was shown with green fluorescent fusion protein expression in tobacco cells. These data suggest that enzymes for conifer diterpene resin acid biosynthesis are localized to at least two different subcellular compartments, plastids and ER, requiring efficient transport of intermediates and secretion of diterpene resin acids into the extracelluar space.

Alkyl and Aryl Transferases↗
PubMed2006

Linking patterns and processes of species diversification in the cone flies Strobilomyia (Diptera: Anthomyiidae).

Phytophagous insects provide useful models for the study of ecological speciation. Much attention has been paid to host shifts, whereas situations where closely related lineages of insects use the same plant during different time periods have been relatively neglected in previous studies of insect diversification. Flies of the genus Strobilomyia are major pests of conifers in Eurasia and North America. They are specialized feeders in cones and seeds of Abies (fir), Larix (larch) ,and Picea (spruce). This close association is accompanied by a large number of sympatric Strobilomyia species coexisting within each tree genus. We constructed a molecular phylogeny with a 1320 base-pair fragment of mitochondrial DNA that demonstrated contrasting patterns of speciation in larch cone flies, as opposed to spruce and fir cone flies; this despite their comparable geographic distributions and similar resource quality of the host. Species diversity is the highest on larch, and speciation is primarily driven by within-host phenological shifts, followed by allopatric speciation during geographical expansion. By contrast, fewer species exploit spruce and fir, and within-host phenological shifts did not occur. This study illustrates within-host adaptive radiation through phenological shifts, a neglected mode of sympatric speciation.

Animals↗
PubMed2001

Defective interplay of activators and repressors with TFIH in xeroderma pigmentosum.

Inherited mutations of the TFIIH helicase subunits xeroderma pigmentosum (XP) B or XPD yield overlapping DNA repair and transcription syndromes. The high risk of cancer in these patients is not fully explained by the repair defect. The transcription defect is subtle and has proven more difficult to evaluate. Here, XPB and XPD mutations are shown to block transcription activation by the FUSE Binding Protein (FBP), a regulator of c-myc expression, and repression by the FBP Interacting Repressor (FIR). Through TFIIH, FBP facilitates transcription until promoter escape, whereas after initiation, FIR uses TFIIH to delay promoter escape. Mutations in TFIIH that impair regulation by FBP and FIR affect proper regulation of c-myc expression and have implications in the development of malignancy.

Blotting, Western↗
PubMed2003

Expression of FERM domain including guanine nucleotide exchange factor mRNA in adult rat brain.

FERM domain including Rho GEF (FIR) belongs to Dbl family of guanine nucleotide exchange factors and specifically activates biochemical pathways specific for Rac1. FIR was shown to regulate neurite remodeling of the embryonic neurons. Here we report a distribution of FIR mRNA in adult rat brain using in situ hybridization. The expression was found all throughout the brain with the most intensive signals in hippocampus, piriform cortex, red nucleus and nuclei of cranial nerves. The signal was predominantly localized in the neuronal cells.

Aging↗
PubMed1996

Effects of formaldehyde-enriched mists on Pseudotsuga menziesii (Mirbel) Franco and Lobaria pulmonaria (L.) Hoffm.

The atmosphere in some areas is polluted with formaldehyde (HCHO); however, little is known about effects of HCHO on plants at concentrations resembling those in polluted areas. The effects of simulated fogwater enriched with HCHO on seedlings of Pseudotsuga menziesii (Mirbel) Franco (Douglas fir) and pendants of Lobaria pulmonaria (L.) Hoffm. were assessed. Plants were treated with HCHO-enriched fog (target concentrations of 100, 500, and 1000 microm) during five 4-night mist sessions. Growth and nitrogenase activity (acetylene reduction rate) for lichens and growth and timing of bud-break for Douglas fir were monitored. Nitrogenase activity was lowest in lichens treated at the highest HCHO concentration after all but the first mist session, and it declined significantly with increasing HCHO concentration after the final mist session (R(2) = 0.60, p = 0.02). However, differences in nitrogenase activity among treatments were generally not statistically significant (most p values from ANOVAs were >/= 0.20). Formaldehyde did not affect growth of the lichens. Budbreak of Douglas firs was slightly delayed and height growth was slightly depressed with increasing HCHO concentration, although effects were not statistically significant.

Journal Article↗