小硅藻光合作用脂^(13)C稳定同位素定量标记分析

^(13)C Stable Isotope Labeled Quantitative Analysis of Photosynthesis Lipid in Diatom

以小硅藻(Nitzschia closterium f.minutissima)作为研究对象,利用超高压液相色谱联用四极杆-静电场轨道阱高分辨质谱技术,研究了处于平台期的小硅藻中的光合作用脂被^(13)C标记的程度和速度。结果显示:在平台期^(13)C人工标记的10天内,所有4类光合作用脂均被^(13)C明显标记,其中二酰甘油双半乳糖脂(DGDG)、磷脂酰甘油(PG)、二酰甘油硫代糖脂(SQDG)被^(13)C标记的总量,从刚进入平台期到平台期第8天逐渐增加,此后出现下降趋势,在第8天分别达到最大值(173±24)ng/mg,(473±41)ng/mg及(1224±21)ng/mg,标记率分别达到56.3%,38.4%和62.6%;而二酰甘油单半乳糖脂(MGDG)被^(13)C标记的总量在整个平台期呈现持续上升趋势,并在第10天达到(956±51)ng/mg,标记率为87.3%。可见,不同脂质在藻体内合成的先后时间有差别,为了清晰地了解生物摄食过程中对微藻中特定脂类的同化机理,需要藻体内被^(13)C标记的每类脂质含量的最大化,针对DGDG、PG、SQDG,应选取标记了8天的微藻来投喂生物,而针对MGDG,则应选取标记了10天的微藻投喂生物。

The diatom Nitzschia closterium f. minutissima was selected as the object to study the^13C labeled extent and speed of photosynthesis lipids by ultra high pressure liquid chromatography coupled with quadrupole orbitrap high resolution mass spectrometry. The results showed that all four types of lipid were labeled clearly by^13C within 10 days in the stationary phase. The total labeled amount by^13C of digalactosyl diacylglycerol（DGDG）,phosphatidylglycerol（PG）and sulfoquinovosyl diacylglycerol（SQDG）increased from entering the stationary phase to the eighth day,but declined later. And the total labeled amount of DGDG,PG and SQDG reached the maximum of（173 ±24）ng / mg,（473 ±41）ng / mg and（1224 ±21）ng / mg on the eighth day with the labeled rate of 56. 3%,38. 4% and 62. 6%, respectively. The total labeled amount by^13C of monogalactosyl diacylglycerol（MGDG）showed a continued upward trend during the 10 days,and reached（956±51）ng / mg on the tenth day,with marked rate of 87. 3%. It was suggested that the synthesized time of different lipid was different. Therefore,for studying assimilation mechanism of microalgae lipids by marine organisms,the lipid content that labeled by^13C should reach the maximum. So if for DGDG,PG and SQDG,we should choose the diatom labeled 8 days by^13C to feed the marine organisms. Meanwhile if for MGDG,we should choose the diatom labeled 10 days by^13C to feed the marine organisms.