Mosulén Silvia, Domínguez M José, Vigara Javier, Vílchez Carlos, Guiraum Alfonso, Vega José M
Departmento Bioquímica Vegetal y Biología Molecular, Facultad de Química, Universidad de Sevilla, Apartado 553, 41080 Sevilla, Spain.
Biomol Eng. 2003 Jul;20(4-6):199-203. doi: 10.1016/s1389-0344(03)00053-4.
Cadmium (Cd(2+)) or copper (Cu(2+)) ions are toxic for Chlamydomonas reinhardtii growth, at 300 microM, and the alga may accumulate about 0.90+/-0.02 and 0.64+/-0.02% of its dry weight, respectively. Metal contamination changes the elemental composition of dried alga biomass, which indicates the possibility to use C. reinhardtii as biosensor and bioremediator of the aquatic contamination by heavy metals. Either, Cd(2+) or Cu(2+), inhibits about 20% of the nitrate consumption rate by the cells, while only Cd(2+) increases about 40% the sulfate consumption rate. The presence of 1 mM calcium (Ca(2+)) in the culture medium increases the C. reinhardtii productivity (about 50%), the nitrate uptake rate (about 20%) and the sulfate uptake rate (about 30%). In addition, Ca(2+) overcomes the Cd(2+) (300 microM) toxicity by decreasing (about 35%) the intracellular accumulation of metal. Sulfur-starvation induces in C. reinhardtii the expression of serine acetyltransferase and O-acetylserine(thiol)lyase activities, but decreases 50% the consumption rate of nitrate by the cells. Sulfate is also required for the full expression of the nitrate reductase (NR), nitrite reductase (NiR) and glutamate synthase activities.
镉（Cd(2+)）或铜（Cu(2+)）离子对莱茵衣藻的生长具有毒性，浓度为300微摩尔时，该藻类可能分别积累其干重的约0.90±0.02%和0.64±0.02%。金属污染会改变干燥藻类生物质的元素组成，这表明有可能将莱茵衣藻用作重金属水污染的生物传感器和生物修复剂。Cd(2+)或Cu(2+)都会抑制细胞约20%的硝酸盐消耗率，而只有Cd(2+)会使硫酸盐消耗率提高约40%。培养基中存在1毫摩尔钙（Ca(2+)）会提高莱茵衣藻的生产力（约50%）、硝酸盐摄取率（约20%）和硫酸盐摄取率（约30%）。此外，Ca(2+)通过降低（约35%）细胞内金属积累来克服Cd(2+)（300微摩尔）的毒性。硫饥饿会诱导莱茵衣藻中丝氨酸乙酰转移酶和O-乙酰丝氨酸（硫醇）裂合酶活性的表达，但会使细胞的硝酸盐消耗率降低50%。硫酸盐也是硝酸盐还原酶（NR）、亚硝酸还原酶（NiR）和谷氨酸合酶活性充分表达所必需的。
