Use of specific phospholipid fatty acids for identifying and quantifying the external hyphae of the arbuscular mycorrhizal fungus Gigaspora rosea

The external hypha of arbuscular mycorrhizal (AM) fungi, extending from roots out into soil, is an important structure in the uptake of phosphate from the depletion zone around each root. In this paper, we analysed some phospholipid fatty acids (PLFAs) derived from external hyphae of four AM fungi (Glomus etunicatum, Glomus clarum, Gigaspora margarita and Gigaspora rosea) to find fatty acids which may be useful as specific markers for identifying and quantify the external hyphae of Gigaspora species. Leek (Allium porrum L.) seedlings inoculated with each AM fungus were grown in river sand. Sand samples were collected and four PLFAs (16:1ω5, 18:1ω9, 20:1ω9 and 20:4) in the sand were analysed. In addition, the hyphal biomass in the sand was determined by the direct microscopic method. PLFAs 18:1ω9 and 20:4 were found in all the AM-inoculated and non-inoculated sand samples. PLFA 16:1ω5 was detected in the sand inoculated with G. etunicatum, G. clarum and Gi. rosea. PLFA 20:1ω9 was detected only in the sand inoculated with Gi. rosea. PLFAs 16:1ω5 and 20:1ω9 were not found in the sand inoculated with Gi. margarita. The amount of PLFA 20:1ω9 was closely correlated with the amount of biomass of external hyphae of Gi. rosea (r=0.937, P<0.001), whereas no correlation was observed for PLFA 16:1ω5. The 20:1ω9 content of Gi. rosea was approximately 6.56 nmol mg⁻¹ hyphal biomass. We suggest that PLFA 20:1ω9 can be used as a specific marker for identifying and quantifying the external hyphae of Gi. rosea, at least in controlled experimental systems.     

Use of epichlorohydrin-treated chitosan resin as an adsorbent to isolate kappa-casein glycomacropeptide from sweet whey

This study was undertaken to develop a method to isolate glycomacropeptide (GMP), a bioactive compound, from sweet whey by using chitosan resins as anion exchangers. Shrimp shells were used to prepare two chitosan (polyglucosamine) resins, one with the primary amine (-NH(2)) (resin A) and the other with the secondary amine (-NH-) (resin B) as the major functional group. These resins were tested as adsorbents for the isolation of GMP from sweet whey, and the results obtained were compared with those obtained with commercial anion exchangers. The most important finding in this experiment was that the GMP binding capacity of resin A was much higher than that of resin B. Resin A may be the anion exchanger to be tested for industrial scale production of GMP. Amino acid analysis of the GMP-depleted whey fraction suggests that this product can replace sweet whey as an ingredient in various food products including infant formulas, bakery products, and beverages.     

Water-assisted highly efficient synthesis of impurity-free single-walled carbon nanotubes

We demonstrate the efficient chemical vapor deposition synthesis of single-walled carbon nanotubes where the activity and lifetime of the catalysts are enhanced by water. Water-stimulated enhanced catalytic activity results in massive growth of superdense and vertically aligned nanotube forests with heights up to 2.5 millimeters that can be easily separated from the catalysts, providing nanotube material with carbon purity above 99.98%. Moreover, patterned, highly organized intrinsic nanotube structures were successfully fabricated. The water-assisted synthesis method addresses many critical problems that currently plague carbon nanotube synthesis.     

Regeneration of protoplasts from hyphal strands ofVolvariella volvacea

A series of experiments on the preparation and regeneration of protoplasts from hyphal strands ofVolvariella volvacea (Bull. ex. Fr.) Singer were conducted with the aim of optimizing the conditions for its efficient regeneration. One commercial (Vvcl) and two wild (EAAC-0001 and EAAC-0002) strains ofV. volvacea from the Philippines were used and subjected to varying conditions to determine the most efficient means for regeneration of their protoplasts. The effects of age and type of strain, pH, type and concentration of osmotic stabilizer, enzymatic composition, treatment time, temperature, reciprocal frequency during enzymatic lysis of the cell wall, and centrifugation conditions were investigated. Results showed that the three strains ofV. volvacea had varying responses in terms of yield, size, and ability of their protoplasts to regenerate into the protoplast regeneration medium. Among the three strains, EAAC-0002 had the highest rate of regeneration. The 5-day-old culture ofV. volvacea, when subjected to a combination of 2% Novozyme 234 and 0.2% chitinase in 0.6M mannitol (pH 6.0) for 3 h at 30°C, 90 strokes/min and centrifuged at 1100 g for 10 min; produced an efficient yield of protoplasts with a relatively high regeneration rate.Part of this paper was presented at the 47th annual meeting of the Japan Wood Research Society, Kochi, Japan, April 2–5, 1997