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1.
2.
Lily Khadempour Valerie LeMay David Jack J?rg Bohlmann Colette Breuil 《Microbial ecology》2012,64(4):909-917
The mountain pine beetle (MPB) is a native bark beetle of western North America that attacks pine tree species, particularly lodgepole pine. It is closely associated with the ophiostomatoid ascomycetes Grosmannia clavigera, Leptographium longiclavatum, Ophiostoma montium, and Ceratocystiopsis sp.1, with which it is symbiotically associated. To develop a better understanding of interactions between beetles, fungi, and host trees, we used target-specific DNA primers with qPCR to assess the changes in fungal associate abundance over the stages of the MPB life cycle that occur in galleries under the bark of pine trees. Multivariate analysis of covariance identified statistically significant changes in the relative abundance of the fungi over the life cycle of the MPB. Univariate analysis of covariance identified a statistically significant increase in the abundance of Ceratocystiopsis sp.1 through the beetle life cycle, and pair-wise analysis showed that this increase occurs after the larval stage. In contrast, the abundance of O. montium and Leptographium species (G. clavigera, L. longiclavatum) did not change significantly through the MPB life cycle. From these results, the only fungus showing a significant increase in relative abundance has not been formally described and has been largely ignored by other MPB studies. Although our results were from only one site, in previous studies we have shown that the fungi described were all present in at least ten sites in British Columbia. We suggest that the role of Ceratocystiopsis sp.1 in the MPB system should be explored, particularly its potential as a source of nutrients for teneral adults. 相似文献
3.
Kevin J. Beiler Suzanne W. Simard Valerie LeMay Daniel M. Durall 《Molecular ecology》2012,21(24):6163-6174
Understanding ectomycorrhizal fungal (EMF) community structure is limited by a lack of taxonomic resolution and autecological information. Rhizopogon vesiculosus and Rhizopogon vinicolor (Basidiomycota) are morphologically and genetically related species. They are dominant members of interior Douglas‐fir (Pseudotsuga menziesii var. glauca) EMF communities, but mechanisms leading to their coexistence are unknown. We investigated the microsite associations and foraging strategy of individual R. vesiculosus and R. vinicolor genets. Mycelia spatial patterns, pervasiveness and root colonization patterns of fungal genets were compared between Rhizopogon species and between xeric and mesic soil moisture regimes. Rhizopogon spp. mycelia were systematically excavated from the soil and identified using microsatellite DNA markers. Rhizopogon vesiculosus mycelia occurred at greater depth, were more spatially pervasive, and colonized more tree roots than R. vinicolor mycelia. Both species were frequently encountered in organic layers and between the interface of organic and mineral horizons. They were particularly abundant within microsites associated with soil moisture retention. The occurrence of R. vesiculosus shifted in the presence of R. vinicolor towards mineral soil horizons, where R. vinicolor was mostly absent. This suggests that competition and foraging strategy may contribute towards the vertical partitioning observed between these species. Rhizopogon vesiculosus and R. vinicolor mycelia systems occurred at greater mean depths and were more pervasive in mesic plots compared with xeric plots. The spatial continuity and number of trees colonized by genets of each species did not significantly differ between soil moisture regimes. 相似文献
4.
The methods are given which were used to determine the number of stages in the life history of Trichoniscus pusillus pusillus Brandt, 1833 and the stages are described as far as possible. Not all stadia can be separated on morphological grounds and animals extracted from monthly litter samples were measured and the stadia separated by use of probability paper. This method proved quite successful and confirmed the characterization of the three earlier juvenile stadia on morpholigical grounds and the number of the later juvenile stadia determined from laboratory cultures. There are six juvenile and five adult stadia. 相似文献
5.
Homology of Saccharomyces cerevisiae ADH4 to an iron-activated alcohol dehydrogenase from Zymomonas mobilis 总被引:8,自引:0,他引:8
Summary Insertion of the transposable element Ty at the ADH4 locus results in increased levels of a new alcohol dehydrogenase (ADH) activity in Saccharomyces cerevisiae. The DNA sequence of this locus has been determined. It contains a long open reading frame which is not homologous to the other ADH isozymes that have been characterized in S. cerevisiae nor does it show obvious homology to Drosophila ADH. The hypothetical ADH does, however, show strong homology to the sequence of an iron-activated ADH from the bacterium Zymomonas mobilis. Thus ADH4 appears to encode an ADH structural gene which, along with the Zymomonas enzyme, may define a new family of alcohol dehydrogenases.Now The Plant Cell Research Institute, Inc., 6560 Trinity Court, Dublin, CA 94568, USA 相似文献
6.
Survey of the Anaerobic Biodegradation Potential of Organic Chemicals in Digesting Sludge 总被引:4,自引:1,他引:3 下载免费PDF全文
The degradation potential of 77 organic chemicals under methanogenic conditions was examined with an anaerobic digesting sludge from the United Kingdom. Degradation was assessed in terms of net total gas (CH4 plus CO2) produced, expressed as a percentage of the theoretical production (ThGP). The compounds tested were selected from various chemical groups and included substituted phenols and benzoates, pesticides, phthalic acid esters, homocyclic and heterocyclic ring compounds, glycols, and monosubstituted benzenes. The results obtained were in good agreement with published surveys of biodegradability in U.S. digesting sludges and other methanogenic environments. In general, the presence of chloro or nitro groups inhibited anaerobic gas production, while carboxyl and hydroxyl groups facilitated biodegradation. The relationship between substituent position and susceptibility to methanogenic degradation was compound dependent. The following chemicals were completely degraded (≥80% ThGP) at a concentration of 50 mg of carbon per liter: phenol, 2-aminophenol, 4-cresol, catechol, sodium benzoate, 4-aminobenzoic acid, 3-chlorobenzoic acid, phthalic acid, ethylene glycol, diethylene glycol, triethylene glycol, sodium stearate, and quinoline. 3-Cresol, 4-chlorobenzoic acid, dimethyl phthalate, and pyridine were partially degraded. Although the remaining chemicals tested were either persistent or toxic, their behavior may differ at more environmentally realistic chemical-to-biomass ratios. Our findings suggest that biodegradability assessments made with sludge from one source can be extrapolated to sludge from another source with a reasonable degree of confidence and should help in predicting the fate of an organic chemical during the anaerobic digestion of sewage sludge. 相似文献
7.
The organotypic culture of human skin keratinocytes and fibroblasts to achieve form and function 总被引:6,自引:0,他引:6
Dr. Nancy L. Parenteau Patrick Bilbo Cynthia J. M. Nolte Valerie S. Mason Mireille Rosenberg 《Cytotechnology》1992,9(1-3):163-171
We describe an organotypic model of human skin comprised of a stratified layer of human epidermal keratinocytes and dermal
fibroblasts within a contracted collagen lattice. Feasible and reproducible production of the skin construct has required
the use of traditional as well as specialized culture techniques. The configuration of the construct has been engineered to
maintain polarity and permit extended culture at the air-liquid interface. Morphological, biochemical and kinetic parameters
were assessed and functional assays were performed to determine the degree of similarity to human skin. Light and ultrastructural
morphology of the epidermis closely resembled human skin. The immunocytochemical localization of a number of differentiation
markers and extracellular matrix proteins was also similar to human skin. Kinetic data showed a transition of the epidermal
layer to a morein vivo-like growth rate during the development of the construct at the air-liquid interface. The barrier properties of the construct
also increased with time reaching a permeability to water of less than 2%·h after approximately 2 weeks at the air-liquid
interface which is still on average 30-fold more water-permeable than normal human skin. The construct is currently used forin vitro research and testing and is also being tested in clinical applications. 相似文献
8.
Summary The germination response of Sinapis arvensis to the presence of established plants was investigated in a greenhouse experiment. Established conspecific and heterospecific plants were found to inhibit germination and reduce the probability of recruitment of those seeds that germinate. Established plants have no effect on seed mortality in the soil. Using a simple recruitment model, it is demonstrated that the combination of variance in germination time coupled with the interaction between buried seeds and established plants can generate density dependence. The implications of these results for community processes, such as succession, are discussed. 相似文献
9.
Jeong-Yau Ho Rob Weide Helen M. Ma Monique F. van Wordragen Kris N. Lambert Maarten Koornneef Pim Zabel Valerie M. Williamson 《The Plant journal : for cell and molecular biology》1992,2(6):971-982
A dominant allele at the Mi locus on chromosome 6 of tomato (Lycopersicon esculentum Mill) confers resistance to three species of root-knot nematodes (Meloidogyne). The resistance, which is associated with a localized necrotic response, was originally introduced into tomato from the wild species Lycopersicon peruvianum. As a step towards the molecular cloning of Mi, we have identified closely linked DNA markers from both cDNA and genomic DNA libraries as restriction fragment length polymorphisms (RFLPs). DNA from tomato populations segregating for nematode resistance was analyzed to generate a high-resolution genetic map of this region. Additional information on gene order was obtained by comparing the size of the introgressed L. peruvianum chromosomal segment within a collection of nematode-resistant tomato lines. Among the four cDNA markers that are tightly linked to Mi, three are dominant, i.e. L. peruvianum-specific. One cDNA marker corresponds to a gene family comprising 20-30 members, one of which is diagnostic for all nematode-resistant genotypes tested. The presence of non-homologous sequences around the Mi gene may contribute to the suppression of recombination in this region of the genome in crosses heterozygous for Mi. The potential of 'walking' from closely linked markers to Mi is discussed. 相似文献
10.
Valerie J. Horn Paul A. Sheehy Miriam B. Goodman Indu S. Ambudkar 《Molecular and cellular biochemistry》1991,101(1):43-49
Intracellular Ca2+ mobilization events were assessed in mouse L cells, which contain native prostaglandin E1 receptors and transfected human 2 adrenergic receptors. Both Fura2 (single cell measurements) and Quin 2, (cuvette assays) were used to determine [Ca2+]i levels. Our results demonstrate that in the transfected cells there is a dose-dependent increase in [Ca2+]i in response to isoproterenol (0.1 nM–100 nM), which is inhibited by the -adrenergic antagonist, propranolol, and is a result of intracellular Ca2+ release. [Ca2+]1 in these cells was also increased by prostaglandin E1, 8 bromo cyclic AMP, and aluminum fluoride. Both 8 bromo cAMP and isoproterenol induced a rapid increase in the levels of IP1, IP2, and IP3. The data presented demonstrate that the elevation of intracellular cyclic AMP induces an increase in IP3 production which leads to an elevation in [Ca2+];. We propose that this cyclic AMP dependent activation of the IP3 generating system occurs at a post-receptor site.Abbreviations cAMP
Adenosine Cyclic 3-5-Monophosphate
- [Ca2+]i
intracellular [Ca2+]i
- 8 Br cAMP
8 Bromo Adenosine Cyclic 3-5-Monophosphate
- DAG
Diacylglycerol
- EGTA]
[Ethylene Bis (oxyethylenenitrilo)] Tetracetic acid
- BSA
Bovine Serum Albumin
- HBSS-H
Hanks' Balanced Salt Solution buffered with HEPES to pH 7.4
- HEPES
4-(2-Hydroxyethyl)-1-piperazineethanesulfonic acid
- PIP2
Phosphatidylinositol 4,5-bisphosphate
- IP2
Inositol 4 Phosphate
- IP2
Inositol 4,5 Bisphosphate
- IP3
Inositol Trisphosphate
- PGE1
Prostaglandin E1
- PBS
Phosphate Buffered Saline Solution 相似文献