Epstein-Barr Virus Polypeptides: Identification of Early Proteins and Their Synthesis and Glycosylation

We have identified at least six early polypeptides induced by Epstein-Barr virus in cells or under conditions which are nonpermissive for Epstein-Barr virus DNA replication ranging in molecular weight from 140,000 to 26,000.     

Species–area curve and distance–decay relationships indicate habitat thresholds of ectomycorrhizal fungi in an old‐growth Pseudotsuga menziesii landscape

Aim

Ectomycorrhizal fungi (EMF) are a diverse and essential biota of forests that are vulnerable to species loss through reductions in late‐seral habitat. We examined how the spatial ecology of this biota, particularly distance–decay and species–area relationships, could better inform habitat thresholds for EMF conservation planning.

Location

Southeast Vancouver Island near Victoria, British Columbia, Canada.

Methods

Using a stratified sampling design, 11 plots (0.15 ha in size) were established at 0.05–17.5 km apart across 2,800 ha of mesic old‐growth Pseudotsuga menziesii var. menziesii and Tsuga heterophylla forests. EMF communities were compiled through molecular analysis of root tips and sporocarps.

Results

The EMF community was comprised of many Cortinarius, Piloderma, Russula and Tricholoma species typical of mesotrophic habitat. A total of 238 EMF species were observed, of which 86 species were detected only once. The ratio of average species richness per plot (84 taxa) to total richness was low at 0.35, and inherent stochasticity of the EMF community was estimated to be 31% community dissimilarity for species incidence. Distance decay of EMF communities was nonlinear, with an estimated slope break at 2.6 km, followed by a largely unchanging trend in β‐diversity. Accumulated species–area curves were fitted best by the cumulative Weibull sigmoid model, and the asymptote (367 species) at approx. 50 ha was consistent with nonparametric estimates of γ‐diversity (342–362 spp.).

Main conclusions

Old‐growth forests host an impressive amount of EMF diversity, and many of the Ramaria, Inocybe and Russula species are likely to be endemic to the Pacific Northwest. Both niche‐ and neutral‐based processes influenced EMF community composition, resulting in a minimum threshold of 50 ha (1.8% of the sample area) for capturing γ‐diversity. These spatial patterns will help design and evaluate conservation efforts, such as retention forestry, to sustain fully diverse EMF communities over managed landscapes.

     

Organic nitrogen use by salal ericoid mycorrhizal fungi from northern Vancouver Island and impacts on growth in vitro of Gaultheria shallon

 Salal (Gaultheria shallon) recovers quickly from rhizomes after clear-cut timber harvesting and dominates clearcuts of Tsuga heterophylla and Thuja plicata forests. Thus it contributes to considerable problems in regeneration of these sites in coastal British Columbia, Canada. Based on what is known about other ericaceous plants, we speculated that mycorrhizal fungi of salal play a vital role in the growth and dominance of salal by providing access to organic nitrogen. In this study, the ability of four species of fungi isolated from salal to use different forms of organic nitrogen was tested in pure culture and in association with salal. The organic forms of nitrogen applied were glutamine (an amino acid), glutathione (a peptide), and bovine serum albumin (BSA, a protein). The fungi tested were Oidiodendron maius, Acremonium strictum, and two nonsporulating fungi. Inoculated plants always grew better than noninoculated plants regardless of nitrogen source. Glutamine was used as readily as ammonium nitrogen by all four fungi and the mycorrhizal plants of salal colonized by those fungi. There was considerable variation between fungus species or the plants inoculated with those fungi in using glutathione and BSA. Salal inoculated with O. maius grew better on glutathione than BSA, while A. strictum and unknown 1 produced significantly greater yields of salal on BSA. Colonization rates of salal by all four fungi was higher on glutathione or BSA than on ammonium or glutamine. Accepted: 19 June 1999     

The effect of fertilization on the below-ground diversity and community composition of ectomycorrhizal fungi associated with western hemlock (Tsuga heterophylla)

Fertilization typically reduces ectomycorrhizal diversity shortly after its application but less is known about its longer-term influence on fungal species. Long-term effects are important in forests where fertilizer is rarely applied. We compared fungal species composition in western hemlock control plots with plots last fertilized 7 years ago with nitrogen (N) or nitrogen plus phosphorus (N + P). The N + P fertilization had a significant lingering effect, increasing the tree size and foliar P content of the western hemlocks. From ectomycorrhizal roots of 24-year-old trees from northern Vancouver Island, Canada, we identified fungi from 12 samples per treatment, by amplifying, cloning, and sequencing fungal ribosomal DNA fragments, placing sequences with 97% or more identity in the same operational taxonomic unit (OTU). Diversity was high across treatments; we detected 77 fungal OTUs, 52 from ectomycorrhizal genera, among 922 clone sequences. The five most frequent OTUs were similar in abundance across treatments. Only 19 OTUs matched any of the 197 previously reported ectomycorrhizal species of western hemlock. Species composition but not diversity in nitrogen plus phosphorus plots differed significantly from control or nitrogen plots. Two Cortinarius OTUs were indicator species for nitrogen plus phosphorus plots and presence of Cortinarius cinnamomeus was correlated with control or nitrogen plots. After 7 years, fertilization history had made no detectable difference in ectomycorrhizal fungal diversity, but long-lasting changes in environment resulting from fertilization had a lingering effect on fungal ectomycorrhizal species composition. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Cultivation of Mediterranean species of Tuber (Tuberaceae) in British Columbia,Canada

Based on an assessment of soil and climatic conditions in British Columbia (BC), the Truffle Association of British Columbia (TABC) determined that the cultivation of Mediterranean Tuber melanosporum and Tuber aestivum might be possible in the warmer parts of the province. With the cooperation of independent truffle growers, TABC assessed the colonization of host tree roots collected from eight truffle orchards planted 2–7 years earlier using morphological and molecular criteria. Both Tuber species persisted on the roots of inoculated trees in six of the eight truffle orchards studied. The identity of Tuber ectomycorrhizas that had been characterized morphologically as differing from those of T. melanosporum and T. aestivum were determined using DNA sequence analysis to belong to three species of truffles native to the Pacific Northwest. One of those species, Tuber anniae, had been previously reported from BC, but the other two, Tuber menseri nom. prov. and Tuber beyerlei, are reported here from BC for the first time. Recently, production of three Périgord black truffles in one truffle orchard and one Burgundy truffle in another orchard demonstrates that these truffles are able to fruit in BC.     

Effects of growth medium, nutrients, water, and aeration on mycorrhization and biomass allocation of greenhouse-grown interior Douglas-fir seedlings

Commercial nursery practices usually fail to promote mycorrhization of interior Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco] seedlings in British Columbia, which may account for their poor performance following planting in the field. We tested the effects of four nursery cultivation factors (nitrogen fertilization, phosphorus fertilization, watering, and soil aeration) and field soil addition on mycorrhization, survival, growth, and biomass allocation of interior Douglas-fir seedlings in a series of greenhouse experiments. Where field soil was added to the growing medium, mycorrhization and root/shoot ratios were maximized at lower levels of mineral nutrient application and aeration. Where field soil was not added, mycorrhization was negligible across all fertilization and aeration treatments, but root/shoot ratio was maximized at lower levels of mineral nutrients and the highest level of aeration. Regardless of whether field soil was added, intermediate levels of soil water resulted in the best mycorrhizal colonization and root/shoot ratios. However, field soil addition reduced seedling mortality at the two lowest water levels. A cluster analysis placed ectomycorrhizal morphotypes into three groups (Mycelium radicis-atrovirens Melin, Wilcoxina, and mixed) based on their treatment response, with all but two morphotypes in the mixed group whose abundance was maximized under conditions common to advanced seedling establishment. For maximal mycorrhization and root development of interior Douglas-fir seedlings, nurseries should minimize addition of nitrogen and phosphorus nutrients, maximize aeration, provide water at moderate rates, and, where possible, add small amounts of field soil to the growing medium.     

Molecular detection,community structure and phylogeny of ericoid mycorrhizal fungi

Through traditional culturing and molecular characterization, we have determined that five putative species and 2 polyphyletic assemblages of fungi produce ericoid mycorrhizae in Gaultheria shallon, other Ericaceae and Epacridaceae. Using phylogenetic analysis of ITS2 sequences in GenBank, we have confirmed that most of these fungi occur in North America, Europe, and Australia. The low recovery rate of culturable ericoid mycorrhizal fungi from Gaultheria shallon may partly be explained by the fact that most mycorrhizal root segments contain an unculturable basidiomycete, revealed by direct amplification, cloning, and sequencing of LSU fungal DNA from root. Molecular characterization and phylogenetic analysis are powerful tools in revealing the geographic distribution and identity of ericoid mycorrhizal fungi.