Effect of nitrogen starvation on optical properties, pigments, and arachidonic acid content of the unicellular green alga Parietochloris incisa (Trebouxiophyceae, Chlorophyta)
Effect of nitrogen starvation on optical properties, pigments, and arachidonic acid content of the unicellular green alga Parietochloris incisa (Trebouxiophyceae, Chlorophyta)
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DOI：
10.1111/j.1529-8817.2007.00375.x
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发表时间：
2007-08-01
影响因子：
2.9
通讯作者：
Cohen, Zvi
中科院分区：
文献类型：
--
作者：
Merzlyak, Mark N.;Chivkunova, Olga B.;Cohen, Zvi
单细胞绿色绿隔球藻Parietochloris incisa（Reisigl）Shin Watan的细胞悬浮液、单个细胞和提取物的光谱特性。研究了弱光下的生长。长期缺氮导致叶绿体体积减少，大量的细胞质油体出现，并沉积了含有高比例花生四烯酸的三酰甘油。叶绿素a和B同步下降，而类胡萝卜素（Car）表现出相对增加。同时，观察到切缘单胞菌、细胞提取物和细胞悬液的光谱特性发生了显著的质的变化。在很大程度上，在细胞悬浮液中观察到的光谱变化可以归因于整体色素含量的减少，导致所谓的包装效应逐渐减弱，并且最有可能在油体中积累额外量的Car超过Chl。细胞悬浮液的一些光学特性可以作为缺氮的敏感指标。此外，吸收比A（476）/A（676）和A（650）/A（676）分别与Car-chl比值和相对花生四烯酸（AA）含量密切相关。后者使它有可能表明，AA的百分比增加，在切割P. incisa的收益与细胞叶绿素含量的下降，解释了包装效应减弱平行。氮补充导致细胞光学性质的完全恢复。细胞超微结构，色素，脂质和光学性质的变化可能具有的意义进行了讨论，特别提到藻类的适应能力和生存条件下的长期营养缺乏。
Spectral properties of cell suspensions, individual cells, and extracts of the unicellular green alga Parietochloris incisa (Reisigl) Shin Watan. grown under low light were studied. Long-terrn nitrogen (N) deprivation resulted in a decrease of chloroplast volume, appearance of numerous large cytoplasmic oil bodies, and the deposition of triacylglycerols with a high proportion of arachidonic acid. Chlorophylls a and b underwent a synchronous decline, whereas carotenoids (Car) showed a relative increase. Simultaneously, significant qualitative changes in the spectral properties of P. incisa individual cells, cell extracts, and cell suspensions were observed. To a large extent, the spectral changes observed in cell suspension could be attributed to a decrease in overall pigment content, leading to a gradual weakening of the so-called package effect and accumulation of additional amounts of Car over chl, most probably, in oil bodies. Several optical characteristics of cell suspensions could serve as sensitive indicators of N-deficiency in P. incisa. Furthermore, the absorption ratios, A(476)/A(676) and A(650)/A(676), showed close correlations with the Car-to-chl ratio and relative arachidonic acid (AA) content, respectively. The latter makes it possible to suggest that the increase in AA percentage in P. incisa proceeds in parallel with a decrease in cell chl content, accounting for the weakening of the package effect. N-replenishment resulted in complete recovery of cell optical properties. The possible significance of the changes in cell ultrastructure, pigments, lipids, and optical properties is discussed with special reference to the ability of algae to adapt to and survive under conditions of long-term nutrient deficiency.