Release of dissolved organic nitrogen from Scenedesmus quadricauda (Chlorophyta) and Microcystis novacekii (Cyanobacteria)
Release of dissolved organic nitrogen from Scenedesmus quadricauda (Chlorophyta) and Microcystis novacekii (Cyanobacteria)
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四尾栅藻（绿藻门）和新生微囊藻（蓝藻门）释放溶解的有机氮
DOI：
10.3354/ame027275
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发表时间：
2002
影响因子：
1.4
通讯作者：
T. Miyazaki
中科院分区：
文献类型：
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作者：
Fumitaka Nagao;T. Miyazaki
研究了淡水浮游植物四尾栅藻（Scenedesmus quadricauda（Turp.）Brebission和Microcystis novacekii（Kom.）用15 N示踪法进行了比较。在氮限制或氮充足的条件下培养藻类。分别以氯化铵和硝酸钠为氮源，测定了DON释放总量、近期同化氮释放量（RANR）和净同化氮（NNA）。在15 N示踪培养中，S.在1h前，M.在硝基限制条件下，novacekii在3-6 h之前观察到总DON的最低释放。该结果表明，氮限制型细胞有效地利用了掺入的氮。在15 N培养条件下，富氮S. quadricauda和M. novacekii。在氮限制和氮充足的藻类RANR小于，并滞后于总DON的释放，表明新同化的氮不容易释放。NNA由氮限制S.从示踪剂孵育开始，四尾细胞的数量增加，表明从孵育开始，氮限制的细胞就需要环境氮。富氮S. quadricauda在示踪剂孵育的前1小时内没有显示NNA，表明在从氮充足的条件转移后，该线虫不立即需要外部氮。本研究表明，氮的释放和同化显着影响藻类的营养状态。
We measured the time-course of dissolved organic nitrogen (DON) release and inor- ganic nitrogen assimilation in the freshwater phytoplankton Scenedesmus quadricauda (Turp.) Brebission and Microcystis novacekii (Kom.) Comp. by the 15 N tracer method. The algae were culti- vated under nitrogen-limited or -replete conditions. We estimated the total DON release, release of recently assimilated nitrogen (RANR) and net nitrogen assimilation (NNA), using ammonium chlo- ride or sodium nitrate as the nitrogen source. In the 15 N tracer incubation of S. quadricauda prior to 1h and in M. novacekii prior to 3-6 h, minimal release of total DON was observed under the nitro- gen-limited conditions. This result suggests that nitrogen-limited cells efficiently use incorporated nitrogen. Appreciable release of total DON was observed in the 15 N incubation of nitrogen-replete S. quadricauda and M. novacekii. RANR in both nitrogen-limited and -replete algae was smaller than, and lagged behind, release of total DON, indicating that newly assimilated nitrogen was less easily released. NNA by nitrogen-limited S. quadricauda increased from the onset of the tracer incu- bation, showing that ambient nitrogen was needed for nitrogen-limited cells from the beginning of the incubation. Nitrogen-replete S. quadricauda showed no NNA during the first 1 h of the tracer incubation, suggesting that the alga did not require external nitrogen immediately after being trans- ferred from nitrogen-replete conditions. This study shows that nitrogen release and assimilation are markedly affected by the nutritional states of the algae.