Chemical composition and characterization of a galactomannoglucan from Gliocladium viride wall material

The following fractions were obtained from the wall material of Gliocladium viride : F1 (27.5%), a glucan, containing xylose, mannose and galactose, coluble in 1 M NaOH at 20°C; F2 (6.7%), a β-glucan-chitin complex, solubilized with 1 M NaOH at 20°C from the previous residue left overnight at −20°C; F3 (8.1%), a glucan, containing mannose and galactose solubilized with 1 M NaOH at 70°C; and F4, the insoluble residue, a β-glucan-chitin complex similar to F2, amounting to 31.3% of the wall material.
F1 was extracted with distilled water. The soluble material (F1S) was a galactomannoglucan (54.7%) and the inscluble (F1P) a glucan (45.3%). Periodate oxidation revealed the presence of glycerol, erythritol, threitol, ribitol, arabitol, mannose, galactose and glucose in F1S, and glycerol and glucose as the main components in F1P. The fractions obtained when F1S was purified through Sepharose CL6B, were methylated.     

Effects of polyoxin D on germination,morphological development and biosynthesis of the cell wall of Trichoderma viride

When polyoxin D is added to a spore suspension of Trichoderma viride at a concentration from 50–100 g/ml, it inhibits from 40–60% of germination. This percentage increases if dimethylsulfoxide (DMSO) is added.Mycelium growing in the presence of polyoxin D becomes irregular and loses its rigidity, showing several bulges along the hypha. Under the electron microscope the features of the cell wall and cytoplasmic content are apparently normal. Nevertheless, after incubation with different lytic systems or with (¹⁴C)glucose, it can be seen that polyoxin D partially inhibits the biosynthesis of -(1-3)glucan and the biosynthesis of chitin to a greater extent attaining inhibition of 83% at 100 g/ml of the antibiotic concentration.Regenerating protoplasts are less affected by polyoxin D. They do regenerate slower but the percentage of regeneration is more than 80%. Aberrant tubes synthesized by these protoplasts are not affected, they manifest their usual morphology and lack of chitin is confirmed in their composition.List of Abbreviations CECT Colecci Española de Cultivos Tipo - GAE Glucose, Asparagine and yeast Extract - DMSO Dimethylsulfoxide - PPO Diphenyloxazole - POPOP 1,4-bis-(4-methyl-5-phenyloxazol-2-yl)     

Asplenium (sect. Hymenasplenium) basiscopicum, a new species from Bolivia

Asplenium basiscopicum is described, illustrated, and compared to the most similar species,A. purpurascens.     

鸟巢蕨孢子繁殖技术研究

研究了鸟巢蕨孢子无菌播种和常规播种两种繁殖方法。结果表明,鸟巢蕨无菌播种中孢子萌发率最高可达66.7%,原叶体在固体培养基上培养不能诱导出孢子体,而需经过振荡培养后才能诱导出孢子体;常规播种法更容易诱导出孢子体,每盆播0.02 g孢子时,每克孢子可产生孢子体4 000株以上,比无菌播种操作简便,成本低。因此,孢子常规播种法更适合于鸟巢蕨规模化生产。     

Gliotoxin, a fungistatic metabolic product of Trichoderma viride

Gliotoxin is shown to be a metabolic product of Trichoderma viride , and a semi-continuous apparatus for its production is described. Ammonia nitrogen is preferable to nitrate nitrogen, but a wide range of carbon sources, and organic or inorganic sulphur sources, are suitable for gliotoxin production. No organic supplements to a glucose-mineral medium have been found to affect gliotoxin production beneficially.
Data are presented showing gliotoxin to be moderately toxic to a wide range of bacteria, actinomycetes and fungi. T. viride itself is resistant to its toxic effects. It shows fungicidal activity when applied as a dust to cereal seeds bearing various seed-borne diseases, but is inferior to organomercury compounds for this purpose. Its value as a fungicide for control of plant or animal infections is reduced by the instability of aqueous solutions, except at low p H.     

The role of callose in guard-cell wall differentiation and stomatal pore formation in the fern Asplenium nidus

Background and Aims

The pattern of callose deposition was followed in developing stomata of the fern Asplenium nidus to investigate the role of this polysaccharide in guard cell (GC) wall differentiation and stomatal pore formation.

Methods

Callose was localized by aniline blue staining and immunolabelling using an antibody against (1 → 3)-β-d-glucan. The study was carried out in stomata of untreated material as well as of material treated with: (1) 2-deoxy-d-glucose (2-DDG) or tunicamycin, which inhibit callose synthesis; (2) coumarin or 2,6-dichlorobenzonitrile (dichlobenil), which block cellulose synthesis; (3) cyclopiazonic acid (CPA), which disturbs cytoplasmic Ca²⁺ homeostasis; and (d) cytochalasin B or oryzalin, which disintegrate actin filaments and microtubules, respectively.

Results

In post-cytokinetic stomata significant amounts of callose persisted in the nascent ventral wall. Callose then began degrading from the mid-region of the ventral wall towards its periphery, a process which kept pace with the formation of an ‘internal stomatal pore’ by local separation of the partner plasmalemmata. In differentiating GCs, callose was consistently localized in the developing cell-wall thickenings. In 2-DDG-, tunicamycin- and CPA-affected stomata, callose deposition and internal stomatal pore formation were inhibited. The affected ventral walls and GC wall thickenings contained membranous elements. Stomata recovering from the above treatments formed a stomatal pore by a mechanism different from that in untreated stomata. After coumarin or dichlobenil treatment, callose was retained in the nascent ventral wall for longer than in control stomata, while internal stomatal pore formation was blocked. Actin filament disintegration inhibited internal stomatal pore formation, without any effect on callose deposition.

Conclusions

In A. nidus stomata the time and pattern of callose deposition and degradation play an essential role in internal stomatal pore formation, and callose participates in deposition of the local GC wall thickenings.     

Occurrence of a unique fucose-branched chondroitin sulfate in the body wall of a sea cucumber

The sulfated polysaccharides in the body wall of the sea cucumber occur as three fractions that differ markedly in molecular mass and chemical composition. The fraction containing a high molecular mass component has a high proportion of fucose and small amounts of galactose and amino sugars, whereas another fraction contains primarily a sulfated fucan. The third fraction (F-2), which represents the major portion of the sea cucumber-sulfated polysaccharides, contains approximately equimolar quantities of glucuronic acid, N-acetyl galactosamine, and fucose, and has a sulfate content higher than that in the other two fractions. The structure of fraction F-2 was examined in detail. This polysaccharide has an unusual structure composed of a chondroitin sulfate-like core, containing side chain disaccharide units of sulfated fucopyranosyl linked to approximately half of the glucuronic acid moieties through the O-3 position of the acid. These unusual fucose branches obstruct the access of chondroitinases to the chondroitin sulfate core of F-2. However, after partial acid hydrolysis, which removes the sulfated fucose residues from the polymer, fraction F-2 is degraded by chondroitinases into 6-sulfated and nonsulfated disaccharides.