Experimental Mycology最新文献

Bailey, A. M., Burden, R. S., James, C. S., Keon, J. P. R., Croxen, R., Bard, M., and Hargreaves, J. A. 1993. Isolation of the ERG2 gene, encoding Δ⁸ → Δ⁷ sterol isomerase, from the maise smut pathogen Ustilago maydis. Experimental Mycology 18, 87-92. The ERG2 gene encoding Δ⁸ → Δ⁷ sterol isomerase has been isolated from the fungal plant pathogen Ustilago maydis. This was accomplished by screening an U. maydis genomic library with a fragment of the Saccharomyces cerevisiae ERG2 gene. The identity of the U. maydis ERG2 gene was confirmed by complementation of an U. maydis Erg2 mutant and by comparing the deduced amino acid sequence encoded by the U. maydis ERG2 gene with that of the S. cerevisiae ERG2 gene product.

Monzer J., Haindl, E., Kern V., and Dressel, K. 1994. Gravitropism of the basidiomycete Flammulina velutipes: Morphological and physiological aspects of the graviresponse. Experimental Mycology, 18, 7-19. The fruiting body of the basidiomycete Flammulina velutipes shows a distinct negative gravitropic response. Maturing fruiting bodies in the rapid elongation phase become graviresponsive with basidiospore differentiation. Lateral gravistimulation by horizontal arrangement of the fruiting body results in unilateral growth regulation. Elongation in the upper stipe side decreases to 40% during gravitropic reorientation of the fruiting body. Overshooting of the gravitropic response during reorientation is precisely regulated. The graviresponsiveness is concentrated to the apical area of the stipe, the transition zone between pileus and stipe, which features a prominent elongation capability. The small size and low vacuolization of the transition zone hyphae compared with differentiated basal stipe hyphae correspond with this physiological function on the light and electron microscopical levels. Curvature experiments using intact and explanted fruiting bodies demonstrated the graviperceptive role of the transition zone. The excision of various amounts of pilear tissue, even the disruption of the whole pileus, had no severe effect on gravitropic curvature, until the transition zone was damaged. Removal of the transition zone resulted in a dramatic loss of graviresponse, whereas the decrease of elongation was less drastic.

Edelmann, S. E., and Staben, C. 1994. A statistical analysis of features within genes from Neurospora crassa. Experimental Mycology 18, 70-81. We analyzed gene sequences from Neurospora crassa deposited in GenBank or EMBL for GC content, codon usage, intron prevalence, intron length, exon length, translation initiation sites, and mRNA splice sites. Protein coding regions were 59% GC, and noncoding regions were 49% GC. Codon usage was biased, primarily due to a strong preference for C in the final position of the codons. Over 80% of N. crassa protein coding genes had introns, which are typically 60 nucleotides long. Exons varied greatly in length, but were typically much longer than introns. The distribution of nucleotides surrounding translation initiation and intron splice sites was clearly nonrandom. We derived a consensus translation initiation site of CAMMATGGCT, a 5′-intron donor site of G^GTAAGTnnYCnYY, an internal branchpoint of WRCTRACMnnnnnnYY, and a 3′-acceptor site of WACAG^.

Freeman, S., Pham, M., and Rodriguez, R. J. 1993. Molecular genotyping of Colletotrichum species based on arbitrarily primed PCR, A + T-rich DNA, and nuclear DNA analyses. Experimental Mycology 17, 309-322. Isolates of Colletotrichum were grouped into 10 separate species based on arbitrarily primed PCR (ap-PCR), A + T-rich DNA (AT-DNA) and nuclear DNA banding patterns. In general, the grouping of Colletotrichum isolates by these molecular approaches corresponded to that done by classical taxonomic identification, however, some exceptions were observed. PCR amplification of genomic DNA using four different primers allowed for reliable differentiation between isolates of the 10 species. HaeIII digestion patterns of AT-DNA also distinguished between species of Colletotrichum by generating species-specific band patterns. In addition, hybridization of the repetitive DNA element (GcpR1) to genomic DNA identified a unique set of Pst 1-digested nuclear DNA fragments in each of the 10 species of Colletotrichum tested. Multiple isolates of C. acutatum, C. coccodes, C. fragariae, C. lindemuthianum, C. magna, C. orbiculare, C. graminicola from maize, and C. graminicola from sorghum showed 86-100% intraspecies similarity based on ap-PCR and AT-DNA analyses. Interspecies similarity determined by ap-PCR and AT-DNA analyses varied between 0 and 33%. Three distinct banding patterns were detected in isolates of C. gloeosporioides from strawberry. Similarly, three different banding patterns were observed among isolates of C. musae from diseased banana.

Barbosa, I. P., and Kemmelmeier, C. 1993. Chemical composition of the hyphal wall from Fusarium graminearum. Experimental Mycology 17, 274-283. Hyphal cell walls of Fusarium graminearum (zearalenone producer strain) were isolated, purified, and subjected to chemical analysis, enzymatic degradation, and electron microscopy. Chemical analysis revealed that the cell wall contained 74.5% carbohydrate, 4.5% protein, 3.0% lipid, 4.5% ash, and 0.3% phosphorus. The major cell wall component, N-acetylglucosamine (31%), is in the form of chitin, as shown by infrared spectroscopy. Glucose constituted 21.5% of the cell wall while mannose, galactose, arabinose, and glucuronic acid accounted for 22% of the cell wall. Glucuronic acid seems to be predominantly linked to galactose in the intact wall. Electron microscopy studies showed that the isolated cell wall consisted of two distinct layers, an outer electron-dense layer and a broader electron-transparent inner layer. Furthermore, intact cells showed an additional outer mucilaginous layer. The cell wall was shown to be susceptible to enzymatic degradation with the gastric juice from the snail Megalobulimus paranaguensis.

Friman, E. 1993. Isolation of trap cells from the nematode-trapping fungus Dactylaria candida. Experimental Mycology 17, 368-370. Dactylaria candida (CBS 220.54) captures nematodes with the aid of adhesive knobs. An easy and quick method to isolate high numbers of these trap cells was developed. During growth in liquid culture with heavy aeration from the bottom, the connections between the knobs and the mycelia were broken. The mycelia were separated from free knobs and substrate by filtration through a 5-μm nylon net. The knobs were then collected on a 1.2-μm millipore filter. The isolated trap cells were able both to "capture" and complete the infection of nematodes and to germinate and colonize an agar substrate. Isolated trap cells will be useful for the isolation of trap-specific microbodies and for identification and further study of molecules involved in the nematode infection process.

Fracella, F., Mohsenzadeh, S., and Rensing, L. 1993. Purification and partial amino acid sequence of the major 70,000-Dalton heat shock protein in Neurospora crassa. Experimental Mycology , 17, 362-367. The major heat shock protein of 70 kDa (hsp70) from heat-shocked mycelial extracts of Neurospora crassa was purified to near homogeneity employing DEAE anion-exchange chromatography followed by affinity chromatography on ATP-agarose. The isolated hsp70 migrates as a single band on one-dimensional sodium dodecyl sulfate polyacrylamide gels (SDS-PAGE), with a molecular mass of ∼69 kDa. On two-dimensional gels it is resolved into two polypeptides with isoelectric points in the acidic range of ∼pH 5.2. The first 53 amino terminal amino acids of the major protein were sequenced and compared with hsp70 of other species. The amino acids aspartic acid, arginine, and phenylalanine occur at positions 27, 28, and 44 (from the methionine terminus) in contrast to the main consensus sequence. These three differing amino acids are shared by yeast, and, in addition, the first two by Arabidopsis, petunia, and maize.