Tobacco (Nicotiana tabacum L. cv. BY-2) cell lines tolerant to 700 M Ni in which unselected cells can not grow, were selected. The Ni-tolerant cells were also more tolerant to Co, but not to Cd than unselected cells. Ni concentrations in Ni-tolerant cells were always higher than those in medium. Since buthionine sulfoximine did not affect their Ni-tolerance, it is suggested that phytochelatins are not involved in Ni-tolerance of Ni-tolerant cells. On the other hand, histidine contents in Ni-tolerant and unselected cells, which were treated with Ni, were higher that those treated without Ni, and the degree of the elevation of histidine contents by Ni-treatment was higher in Ni-tolerant cells than in unselected cells. Additionally, exogenous histidine reduced the inhibitory effect of Ni on the growth of unselected cells. In addition, the cells that were tolerant to histidine-analogue, had higher contents of histidine and Ni-tolerance. These results suggest that histidine is involved in Ni-tolerance and the detoxification of Ni in symplast in Ni-tolerant cells.

Calcium chloride (0.3 or 10 mM) was applied to the growth medium before, together with, or after sodium chloride application, and the effect of the timing of Ca application on the alleviation of salt stress was investigated. Seedlings of maize, tall fescue, and reed canarygrass were grown in medium with 0 and 200 mM NaCl for 5 d. Regardless of the plant species the maximum alleviation of NaCl stress was achieved when CaCl 2 and NaCl coexisted in the growth medium. The effects of Ca application were connected with the decrease in the Na content in the plant roots and shoots and increased ATPase activity in the roots.

The solubilization of cattle achilles tendon with actinidin was investigated under neutral and acidic conditions. 1.43 to 1.92 and 0.97 to 3.19% of collagen were solubilized by treating the cattle achilles tendon with actinidin at 20˚C at pH 6.0 and 3.3, respectively. Furthermore, SDS-polyacrylamide gel electrophoresis of reaction mixtures with actinidin demonstrated that actinidin degraded the tendon into collagen subunit chain, ␤-and ␣-chain and peptide fragments of various sizes at 20˚C at pH 6.0 and 3.3. These results indicated that actinidin could solubilize the insoluble collagen in unheated cattle achilles tendon at 20˚C at pH 6.0 and 3.3 and that a large proportion of the resulting peptide fragments by actinidin seemed to be actinidin digests against elastin with a small contribution of hydroxyproline.

We have previously reported the ability of porous glass material (PGM) to adsorb phosphate and that calcium contributed to this process. In the present investigation, the possible use of PGM to improve water quality (wastewater in particular) and the subsequent use of phosphate‐adsorbed PGM as fertilizer were examined. We confirmed the phyto‐availability of phosphate adsorbed onto PGM using tomato cultivation and an assay of truog‐phosphate levels. Adsorption and release of phosphate in PGM was controlled by particle size. The findings suggest the possibility of using PGM of different particle sizes for efficient phosphate recycling in soil‐water/plant systems.

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