Metabolic responses of the diatom Achnanthes brevipes (bacillariophyceae) to nutrient limitation
Metabolic responses of the diatom Achnanthes brevipes (bacillariophyceae) to nutrient limitation
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DOI：
10.1046/j.1529-8817.2000.99070.x
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发表时间：
2000-10-01
影响因子：
2.9
通讯作者：
Pistocchi, R
中科院分区：
文献类型：
--
作者：
Guerrini, F;Cangini, M;Pistocchi, R
硅藻曲壳藻Achnanthes brevipes C.A. AG.在限制浓度的氮（N）或无机磷酸盐（Pi）存在下培养。就最终产量而言，氮限制比磷限制对生长的影响更大;氮限制对蛋白质和叶绿素含量的影响也更大。两种营养饥饿处理下，碳水化合物浓度均增加，但氮或磷限制的影响不同。当细胞暴露于两种类型的营养限制时，总（细胞内加细胞外）糖含量增加，但胞外多糖组分仅在P-1饥饿的存在下增加。进行分析以确定暴露于低磷酸盐的细胞中发生的代谢变化，因为这是影响碳水化合物挤出的主要条件。参与碳水化合物代谢的几种酶的活性表明，在P-i限制下，在某些高等植物和绿色新月藻中，没有发现导致P-i释放而不是消耗的替代反应的激活。柯林斯。结果表明，与对照细胞相比，在P-i限制条件下，丙酮酸激酶、磷酸化NAD依赖性3-磷酸甘油醛脱氢酶和3-磷酸甘油酸激酶的活性受到抑制，表明葡萄糖催化作用有限。尿苷二磷酸葡萄糖焦磷酸化酶的活性，一个关键酶的生物合成的存储化合物crysolaminarin，也部分抑制在P-1-应激细胞。我们的研究结果表明，A.短足类在P-i缺乏下受到限制，而胞外碳水化合物的挤出是有利的。
The diatom Achnanthes brevipes C.A. Ag. was cultured in the presence of limiting concentrations of nitrogen (N) or inorganic phosphate (P-i). Growth, in terms of final yield, was more affected by N limitation than P-i limitation; N limitation had a greater effect also on protein and chlorophyll content. Carbohydrate concentrations increased under both nutrient starvation treatments, but N or P-i limitation had different effects. Total (intracellular plus extracellular) sugar content increased when cells were exposed to both types of nutrient limitation, but the extracellular polysaccharide fraction increased only in the presence of P-i starvation. Analyses were performed to identify the metabolic changes occurring in cells exposed to low phosphate because this was the main condition that affected carbohydrate extrusion. Activities of several enzymes involved in carbohydrate metabolism showed that under P-i limitation there was no activation of alternative reactions that were found to result in P-i liberation, instead of its consumption, in some higher plants and in the green alga Selenastrum minutum Naeg. Collins. Results showed that activities of pyruvate kinase, phosphorylating NAD-dependent 3-phosphate-glyceraldehyde dehydrogenase, and 3-phospho-glycerate kinase were inhibited under P-i-limited conditions compared with control cells, indicating limited glucose catabolism. Activity of uridine diphosphate glucose pyrophosphorylase, a key enzyme for the biosynthesis of the storage compound crysolaminarin, was also partly inhibited in P-i-stressed cells. Our findings suggest that carbohydrate catabolism in A. brevipes is limited under P-i deficiency, whereas extracellular extrusion of carbohydrate is favored.