Konno Haruyoshi, Nakato Takako, Nakashima Susumu, Katoh Kenji
Research Institute for Bioresources, Okayama University, Kurashiki, Okayama 710-0046, Japan.
J Exp Bot. 2005 Jul;56(417):1923-31. doi: 10.1093/jxb/eri187. Epub 2005 May 31.
The present work reports the results of a study on the growth kinetics and characterization of matrix polysaccharides in the cell walls of Lygodium japonicum prothallium grown in the presence of copper (Cu). When the prothallium was cultured in the media containing 0.2 mM or 0.4 mM CuSO(4), it showed a rapid accumulation of Cu with a maximum uptake of Cu measured in the cells up to 20 d of culture. The maximum rate of Cu uptake into the prothallium was greater for 0.4 mM Cu-treated cells (17.2 micromol g(-1) DW) than for 0.2 mM Cu-treated cells (3.2 micromol g(-1) DW). Cell walls were isolated from both untreated control and Cu-treated cells and then extracted sequentially with cyclohexane-trans-1,2-diaminetetra-acetate (CDTA), Na(2)CO(3), 1 M KOH, and 4 M KOH. The amount of pectin solubilized from 0.4 mM Cu-treated cell walls decreased to 53% of its level in the control, whereas the amount of hemicellulose solubilized from the Cu-treated cell walls represented 82% of that from control cell walls. When the polysaccharides were fractionated by anion-exchange chromatography into four carbohydrate components, considerable increases in fractions PI-3 and PII-3 eluted with 0.5 M NaCl were observed in CDTA-soluble (PI) and Na(2)CO(3)-soluble (PII) pectic polymers from Cu-treated cell walls. Fractions PI-3 and PII-3 were composed predominantly of uronic acid (more than 71% of total sugars). Approximately 66% of Cu within the cell walls was released from the 0.4 mM Cu-treated cells with the endo-pectate-lyase treatment, suggesting that most of the Cu that accumulated into the Lygodium prothallium is tightly bound to the homogalacturonan of the cell wall pectin.
本研究报告了在铜（Cu）存在的情况下生长的日本海金沙原叶体细胞壁中基质多糖的生长动力学和特性研究结果。当原叶体在含有0.2 mM或0.4 mM硫酸铜的培养基中培养时，它显示出铜的快速积累，在培养至20天时细胞中测得的铜最大吸收量。0.4 mM铜处理的细胞对原叶体的最大铜吸收速率（17.2微摩尔克-1干重）高于0.2 mM铜处理的细胞（3.2微摩尔克-1干重）。从未处理的对照细胞和铜处理的细胞中分离出细胞壁，然后依次用环己烷-反式-1,2-二氨基四乙酸（CDTA）、碳酸钠、1 M氢氧化钾和4 M氢氧化钾提取。从0.4 mM铜处理的细胞壁中溶解的果胶量降至对照水平的53%，而从铜处理的细胞壁中溶解的半纤维素量占对照细胞壁的82%。当多糖通过阴离子交换色谱法分离成四种碳水化合物成分时，在来自铜处理细胞壁的CDTA可溶性（PI）和碳酸钠可溶性（PII）果胶聚合物中，观察到用0.5 M氯化钠洗脱时PI-3和PII-3组分有相当大的增加。PI-3和PII-3组分主要由糖醛酸组成（占总糖的71%以上）。用内切果胶裂解酶处理后，细胞壁中约66%的铜从0.4 mM铜处理的细胞中释放出来，这表明积累到日本海金沙原叶体中的大部分铜与细胞壁果胶的同型半乳糖醛酸紧密结合。
