Brownell P F, Nicholas D J
Department of Agricultural Biochemistry, Waite Agricultural Research Institute, University of Adelaide, South Australia.
Plant Physiol. 1967 Jul;42(7):915-21. doi: 10.1104/pp.42.7.915.
Anabaena cylindrica grown with nitrate required higher levels of sodium (0.4 meq/l NaCl) to prevent chlorosis than when grown without combined nitrogen (0.004 meq/l NaCl). Nitrite accumulated in sodium-deficient cultures containing nitrate. Amounts of nitrite similar to those found in deficient cultures when added to normal cultures resulted in a chlorosis of the cells. Thus loss of chlorophyll was caused by nitrite toxicity.A deficiency of sodium resulted in an increased incorporation of (15)NO(3), (15)NO(2), (15)NH(3) or (14)C glutamate into protein compared with normal cells. The enzyme nitrate reductase was markedly increased in cells grown without sodium.Evidence from chloramphenicol treatment of the cells suggests that sodium may exert its control of nitrate reductase through a protein factor(s).By contrast, N(2) fixation was reduced in sodium deficient cells. Since the incorporation of ammonia or glutamate into protein was increased under these conditions, it is likely that the element is required for the conversion of N(2) gas into ammonia. Various nitrogenous compounds including ammonium chloride, amides and amino acids at low concentrations (0.1 mm) greatly reduced the nitrite accumulation in sodium-deficient cultures.
与在无化合态氮条件下生长（0.004 毫当量/升氯化钠）相比，以硝酸盐为氮源生长的柱状鱼腥藻需要更高水平的钠（0.4 毫当量/升氯化钠）来防止黄化。在含硝酸盐的缺钠培养物中亚硝酸盐会积累。当向正常培养物中添加与缺钠培养物中含量相似的亚硝酸盐时，细胞会出现黄化现象。因此，叶绿素的损失是由亚硝酸盐毒性引起的。与正常细胞相比，钠缺乏会导致（15）NO₃、（15）NO₂、（15）NH₃ 或（14）C 谷氨酸掺入蛋白质的量增加。在无钠条件下生长的细胞中，硝酸还原酶显著增加。氯霉素处理细胞的证据表明，钠可能通过一种蛋白质因子来控制硝酸还原酶。相比之下，缺钠细胞中的固氮作用会降低。由于在这些条件下氨或谷氨酸掺入蛋白质的量增加，很可能该元素是将氮气转化为氨所必需的。低浓度（0.1 毫米）的各种含氮化合物，包括氯化铵、酰胺和氨基酸，能大大减少缺钠培养物中亚硝酸盐的积累。
