Two morphological markers indicating dikaryosis in Schizophyllum commune

Summary In the wood destroying basidiomycete Schizophyllum commune a method is described to recognize the onset of dikaryosis rapidly in using recessive genetic markers. The gene ai ⁺/ai causes in its mutant recessive allele (ai) the production of dark coloured fruit bodies. This can be made use of to evaluate macroscopically the formation of a dikaryon. Another useful marker is the gene rd ⁺/rd. The recessive allele (rd) causes phenotypically the formation of a round looking mycelium instead of the fringed looking mycelium, the wild type. This genetic marker which is closely linked to the A-incompatibility factor is therefore also qualified to detect the onset of dikaryosis without much effort.     

Two independent gene systems controlling recombination in Schizophyllum commune

Summary Mating competence in the fungusSchizophyllum commune is controlled by two unlinked factors, each of which consists of two closely linked loci. The recombination frequencies between the loci of each factor were determined for a dikaryon and a group of back-crosses, at two meiotic temperatures. The results establish that the frequencies of recombination in the two regions are under genetic control. Although the two regions are similar in structure and function they are under separate recombination control.     

Chlamydospores of Schizophyllum commune

Summary The detection of chlamydospores of Schizophyllum commune in liquid medium is described. The short thick walled cells are formed by intercalary septation which leads also to modification of the septal complex. The chemical composition of the cell walls of chlamydospores is similar to the composition of the vegetative mycelium.     

普通裂褶菌真菌学及实验室研究进展

普通裂褶菌是一种条件致病菌,可侵犯人体多个器官多种组织,导致各种表现形式的疾病,如脑脓肿、脑膜炎、鼻窦炎、肺部真菌球、蜂窝肺、肺结节、甲真菌病等.由于普通裂褶菌感染引起的真菌病病例少见报道,临床医生对其认识不足,再加上某些实验室不具备鉴定条件,所以感染该菌的病例常被漏诊、误诊.现将近年来临床分离的普通裂褶菌株真菌学及实...     

Transformation of the basidiomycete, Schizophyllum commune

Summary Protoplasts of aSchizophyllum commune tryptophan auxotroph (trp1), deficient in indole-3-glycerol phosphate synthetase (IGPS), were transformed to trp⁺ with plasmid DNA containing the SchizophyllumTRP1 sequence. Efficiencies up to 30 transformants per microgram of plasmid DNA were obtained. Southern blots reveal that the transforming DNA is integrated in chromosomal DNA. The trp⁺ phenotype of transformants is stable in meiosis and mitosis. Transformants possess IGPS activity comparable to wild-type cells.     

Studies of the cell walls of Schizophyllum commune

Mechanically isolated cell wall materials of eight strains of Schizophyllum commune were studied by chemical and enzymatic procedures. Isolated wall material of each strain was separated by chemical methods into three fractions: A (cold alkali-soluble, , amorphous), B (warm alkali-soluble, amorphous), and C (alkali-insoluble, retaining appearance of hyphal fragments). Chemical tests indicated the presence of chitin in Fraction C and the absence of cellulose, lignin and pectic substances from all fractions. Analyses of acid hydrolysates indicated the presence of glucose in Fractions A, B and C, of hexosamine in Fraction C and the absence of galactose, mannose, 6-deoxyhexoses, xylose and other pentoses from all fractions. Unfractionated material, Fraction A and Fraction B were slightly attacked by commercial cellulase whereas Fraction C was heavily attacked. Commercial chitinase by itself did not attack Fraction C or unfractionated material to a significant extent. In the presence of cellulase, it was active upon Fraction C. Qualitative differences in cell wall composition between strains were not detected; however, quantitative differences were observed in the proportion of Fraction A and Fraction C as well as in the amount of the various breakdown products in certain strains. It is visualized that the cell wall of this fungus consists of a core of chitin covered by or intermeshed with glucose-containing polymers.     

A bacteriolytic muramidase from the basidiomycete Schizophyllum commune

The basidiomycete Schizophyllum commune produces an extracellular bacteriolytic enzyme when grown on heat-killed cells of Bacillus subtilis as sole C, N and P source. The enzyme catalyses the dissolution of isolated B. subtilis cell walls at an optimum pH of 3.2-3.4, releasing muramyl reducing groups, which indicates that it is a muramidase. Although low levels of enzyme activity are present when the fungus is grown in the absence of bacteria, full enzyme production appears to be induced by bacterial cells and repressed by glucose. Whole bacteria are not lysed by the enzyme at pH 3.3, but are rendered osmotically fragile, and lyse when the pH is raised to 7 or higher. The muramidase is effective against several Gram-positive bacteria but did not lyse any of the Gram-negative species tested.     

Developmentally regulated proteases from the basidiomycete Schizophyllum commune

The basidiomycete Schizophyllum commune produces three chromatographically distinguishable proteases which are capable of attack on a variety of other enzymes from S. commune and other sources. These proteases, which are produced during a specific phase of the development cycle, exhibit typical enzyme kinetic patterns, are active in the neutral to weakly alkaline pH range and are inhibited by phenylmethylsulfonyl fluoride, soybean trypsin inhibitor, and ovomucoid. No pattern of specificity toward the test enzymes could be discerned. The proteases co-purify with the activity which causes the increase in cold lability of S. commune phosphoglucomutase reported previously. In addition, one of the protease enzymes could be purified to the point where it had no significant ability to release trichloroacetic acid products from denatured substrates at pH 3 or pH 7. When undenatured hemoglobin was used as a substrate, the purified protease releases a relatively large molecular weight nonheme peptide. Relatively large peptides are also formed after proteolysis of rabbit muscle phosphoglucomutase. These results suggest that the protease carries out only limited proteolysis.     

Chimeric pheromone receptors in the basidiomycete Schizophyllum commune

The pheromone receptor system of the basidiomycete Schizophyllum commune is capable of ligand discrimination to confer mating specificity. The pheromone receptors of the B alpha locus were investigated for ligand discrimination in a strategy of domain swapping experiments. Several altered phenotypes of chimeric receptors have been found. These include constitutive pheromone receptors which need no ligand for activation of the downstream cascade of events. In addition, receptors still dependent on ligand were identified that had altered pheromone activation profiles, including promiscuous receptors that are activated by pheromones of all nine specificities, including the former self. In addition, highly discriminative receptors were created which are activated by only two of the eight non-self-specificities. The chimeric receptors identify the last third of the receptor as the determinant for B alpha 1 specificity, whereas B alpha 2 specificity resides in noncontiguous domains covering the first and middle parts of the receptor molecule.     

裂褶菌营养菌丝蛋白质成分的分析

对裂褶菌菌丝中蛋白质的氨基酸组成及含量进行了测定。结果表明 ,裂褶菌中所含粗蛋白的质量分数为 2 8.76 % ,所测定的 17种氨基酸总质量分数为 12 0 .13g·kg- 1 。其中 7种必需氨基酸的质量分数为 4 5 .36g·kg- 1 ,占氨基酸总量的 37.76 % ;10种非必需氨基酸的质量分数为 79.5 0g·kg- 1 ,占氨基酸总量的 6 2 .2 4 %。     

Control of erythritol dehydrogenase in Schizophyllum commune

Summary An NAD-dependent erythritol dehydrogenase was detected in cell-extracts of basidiospore germinants of Schizophyllum commune following culture on either meso-erythritol or glycerol as sole carbon sources. Induction of erythritol dehydrogenase was also observed in purely vegetative mycelium (str. 845 or str. 699). Erythritol dehydrogenase was not observed in ungerminated basidiospores or germinants which arose on d-glucose, d-mannitol, sorbitol, ribitol, xylitol, d-arabitol or l-arabitol. NAD-coupled polyol dehydrogenases for all the latter sugar alcohols were observed in ungerminated basidiospores, germinants, and vegetative mycelium of S. commune cultured on d-glucose. Basidiospore germination on d-glucose plus meso-erythritol led to a 90% decrease in erythritol dehydrogenase and the specific activity of ribitol dehydrogenase was directly comparable to that seen in d-glucose germinants. Storage experiments of crude extracts of meso-erythritol germinants indicated differential enzyme decay of dehydrogenases for d-mannitol, sorbitol and erythritol while the respective enzymes could be further distinguished by heat-stability as well as preferential utilization of analogues of NAD. DEAE-cellulose column chromatography led to separation of sorbitol dehydrogenase which was also active with xylitol, erythritol dehydrogenase, and mannitol dehydrogenase which was also active with d-arabitol.     

Direct studies of dikaryotization in Schizophyllum commune

Compatible matings of Schizophyllum commune were performed on glucose-peptone-yeast extract medium appended with gelatin (18%) and studied by phase contrast microscopy during nuclear migration. Three categories of nuclear migration were observed. Type I involved a pulsatile jerking of the entire cytoplasmic contents of the hypha, changed direction periodically, and, during periods of cytoplasmic tranquility, the nucleus continued to migrate. Type II A migration of nuclei occurred in the absence of visible cytoplasmic flow. Both Type I and Type II A nuclear movements exceeded the hyphal growth rate by 10--20-fold. Type II B nuclear migration also occurred in the absence of visible cytoplasmic flow and the velocity was within the range of the hyphal growth rate. No specific organelles that were detected either directed or facilitated Type II A or Type II B nuclear movements. The nucleolus could either lead or trail relative to the direction of nuclear movement. Nuclear migration can be attributed to both cytoplasmic flow and self motility, depending upon the particular regions of the migration hypha in which it occurs.     

Production of schizophyllan using Schizophyllum commune NRCM

In the present work, four strains were screened for schizophyllan production, of which Schizophyllum commune NRCM was selected for further work. The fermentation was carried out for 168 h at 28+/-2 degrees C on an orbital shaker at 180 rpm. In the first step, one factor-at-a-time method was used to investigate the effect of media constituents such as carbon and nitrogen sources on schizophyllan production. Subsequently in the second step, concentration of the medium components was optimized using Response Surface Method (RSM). The yield increased from 3.25+/-0.72 g/l in the unoptimized media to 8.03+/-1.12 g/l in the medium optimized by RSM.     

Characterization of the genome of the basidiomycete Schizophyllum commune

DNA of Schizophyllum commune was isolated both from mycelial cells and from protoplasts. Nuclear DNA was isolated after solubilization of the mitochondria with the detergent Nonidet. The G + C content of the nuclear DNA was 57%, calculated from its buoyant density (1.7165 g/ml) and from the Tm (77.4 degrees C in 15 mM NaCl/1.5 mM trisodium citrate). The buoyant density of the ribosomal cistrons was 1.707 g/ml. DNA isolated from purified mitochondria had a very low G + C content: 22% (rho = 1.6845 g/ml, Tm = 61.8 degrees C in 15 mM NaCl/1.5 mM trisodium citrate). Analysis of CsCl profiles and melting patterns suggested that mitochondrial DNA contains interspersed (A + T)-rich sequences. From reassociation analysis of sheared nuclear DNA the genome size of S. commune was determined to be 22.8 . 10(9) daltons. A small amount of DNA (0.5 . 10(9) daltons) bound to hydroxyapatite at zero time Cot. 7% of the genome (1.6 . 10(9) daltons) represented repetitive DNA.     

Sequence organization of the nuclear DNA of Schizophyllum commune

Several methods were used to characterize the organization of repetitive DNA in the fungus Schizophyllum commune. They all failed to show interspersion of repetitive sequences among single copy sequences. Saturation hybridization showed that 2.2% of the double-stranded nuclear DNA coded for rRNA. The size of the ribosomal cistron (11.9.10(6) daltons) was determined by restriction enzyme analysis. From these values it was calculated that about 6% of the nuclear DNA consisted of ribosomal cistrons, which approx. equals the amount of repetitive DNA present. Thus, this simple sequence organization in Schizophyllum commune is fundamentally different from organization patterns in higher eukaryotes.     

Direct studies of dikaryotization in Schizophyllum commune

The growth, duplication and fate of multikaryotic hyphae bearing true clamp connections, as derived from compatible matings of Schizophyllum commune, were studied by phase contrast microscopy. The nuclei (N) of multikaryotic apices maintained a near central position during hyphal growth. True clamp connection formation occurred with near synchronous mitosis followed by septal synthesis across the clamp neck and main hyphal axis. Nuclear progeny after mitosis in a hexakaryon included 6 N in the apex, 1 N in the clamp and 5 N in the penultimate cell; the solitary nucleus in the clamp later entered the penultimate cell. Similar events occurred for clamp connection formation and mitosis in the trikaryon, quadrikaryon or pentakaryon, whether in the apex or primary branches. Nuclear content of the multikaryotic apex (2 N through 10 N) had no apparent effect on the rate of individual hyphal growth. Reduction of the nuclear number in a trikaryon occurred by long-term entrappment of a solitary nucleus in the clamp and subsequent outgrowth of the dikaryotic penultimate cell. Occasionally, more than one nucleus became entrapped in the clamp cell. The ephemeral nature of the multikaryon was indicated by the fact that older cultures appeared to be exclusively dikaryotic hyphae at the colony periphery.