Botanisches Institut der Universität Köln, Gyrhofstr. 15, D-5, Köln 41, Germany.
Planta. 1975 Jan;125(2):161-70. doi: 10.1007/BF00388702.
Discs punched out of different zones of the found of Laminaria hyperborea (Gunn.) Fossl. were exposed to H(14)CO3 (-) in the light and in the dark for various lengths of time. Photosynthetic rates in young and old parts were in the same range, 12-39 μmol CO2 dm(-2) h(-1) at 4°C, whereas dark fixation was remarkably higher in the growing zone than in the old frond: 13-28% of the corresponding light fixation in the young phylloid and only 2-6% in the old one. In all parts of the frond the reductive pentose phosphate cycle is the main system of carboxylation, and is accompanied by a notable primary synthesis of amino acids. In the growing zone heavy and primary labelling of malate and aspartate parallel to 3-PGA is due to the undiminshed activity of the dark fixation system (PEP-carboxykinase) in the light. Mannitol synthesis seems to be enhanced with increasing age of the phylloid, but rapid and primary (14)C-incorporation into amino acids was found in all parts of the frond.The data presented here suggest a possible significance of the high dark fixation rates for the growth of the sublittoral Laminaria hyperborea. Translocation of mobilized storage material from the old phylloid might supply the young tissue with reduced material during the growth season when the light intensity is low in the habitat of this alga.
从海带（Gunn.）Fossl 的根状茎的不同区域打孔出来的圆盘，在光照和黑暗条件下暴露于 H(14)CO3 (-) 中，时间长短不一。年轻和年老部分的光合速率相同，在 4°C 时为 12-39 μmol CO2 dm(-2) h(-1)，而在生长区的暗固定率明显高于老叶片：年轻的叶状部中相应的光固定率的 13-28%，而在老叶片中只有 2-6%。在叶片的所有部分，还原戊糖磷酸循环是羧化的主要系统，并且伴随着显著的氨基酸的初级合成。在生长区，与 3-PGA 平行的苹果酸和天冬氨酸的强烈和初级标记归因于暗固定系统（PEP-羧激酶）在光照下的活性未降低。甘露醇的合成似乎随着叶状部年龄的增加而增强，但在叶片的所有部分都发现了快速和初级（14)C 掺入到氨基酸中。这里提出的数据表明，高暗固定率对于亚潮带海带的生长可能具有重要意义。在这种藻类的栖息地光照强度较低的生长季节，从老叶片中动员储存物质可能会为年轻组织提供还原物质。
