| 球形棕囊藻的负趋光性和硝酸盐饥饿诱导鞭毛脱落试验 |
| Negative Phototaxis and Low-nitrate Induced Flagellum Abscission in Phaeocystis globosa |
| 投稿时间：2015-05-19 修订日期：2015-12-08 |
| DOI：10.15928/j.1674-3075.2015.05.009 |
| 中文关键词:球形棕囊藻 负趋光性 硝酸盐 饥饿诱导 鞭毛脱落 |
| 英文关键词:Phaeocystis globosa negative phototaxis nitrate nitrate starvation flagellum abscission |
| 基金项目:汕头市科技项目（2013年99号，2014年14号）；中国科学院热带海洋生物资源与生态重点实验室开放课题（LMB131004) |
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| 中文摘要: |
| 为了解释自然界中球形棕囊藻（Phaeocystis globosa）赤潮的生消现象，对其负趋光性和硝酸盐饥饿诱导鞭毛脱落进行试验。通过制作简易的实验装置，对球形棕囊藻生活史中的游动单细胞、不动单细胞和群体3种形态进行趋光性试验。结果显示，具有鞭毛的游动单细胞形态的球形棕囊藻负趋光性明显，其他2种形态则无负趋光性；当培养基中硝酸盐完全缺失时，或者用等量氮素的亚硝酸盐或尿素代替，球形棕囊藻细胞均不能正常生长，在硝酸盐饥饿状态下诱导游动单细胞鞭毛脱落成为不动单细胞，并逐渐聚集形成群体，不动单细胞和群体培养液添加硝酸盐继续培养后又出现大量游动单细胞。试验表明，球形棕囊藻具有负趋光性，硝酸盐饥饿能够诱导游动单细胞鞭毛脱落并逐渐形成群体，当硝酸盐营养得到补充时，游动单细胞即可再生，与其在自然界中的赤潮生消现象相吻合。 |
| 英文摘要: |
| Phaeocystis globosa red tides frequently occur in the southeast coastal waters of China and adversely affect the local economy and marine environment. Phaeocystis globosa is a eurythermal, euryhaline marine microalgae with a complex life cycle alternating between free-living cells and colonies. The unicellular stage involves different forms including static single cell, motile single cell and microzoospore. Based on the occurrence and disappearance characteristics of Phaeocystis globosa red tides and the importance of nitrate to the development of red tides, we conducted experiments to explore the negative phototaxis of Phaeocystis globosa and the flagellum abscission of motile single cells that occurs with nitrate starvation. The study provides a theoretical basis for understanding the occurrence and disappearance of Phaeocystis globosa red tides. A simple experimental device was designed and assembled to conduct the phototaxis experiment for the three morphological forms of Phaeocystis globosa; motile single cells, static single cells and colonies. The nitrate starvation experiment for inducing flagellum abscission of motile single cells was divided into five parallel treatments, all beginning with f/2 growth media, prepared with nitrate: No.1, f/2 growth media; No.2, f/2 growth media without nitrogen element; No.3, f/2 growth media with an equal amount urea nitrogen substituting for nitrate; No.4, f/2 growth media with the same amount nitrite nitrogen substituting for nitrate; No.5, f/2 growth media with an extra equal amount of urea nitrogen . Results show that motile cells with flagellum display negative phototaxis, while static single cells and colonies do not. Nitrate is an important limiting factor in the growth of Phaeocystis globosa. Phaeocystis globosa did not grow normally when the f/2 medium contained no nitrate, or when substituting nitrite or urea for nitrate. It was found that nitrate starvation induced flagellum abscission of Phaeocystis globosa, resulting in the aggregation of cells to form colonies. Furthermore, the addition of nitrate induced flagellum growth in static cells of Phaeocystis globosa. In conclusion, the motile cells of Phaeocystis globosa display negative phototaxis, explaining why Phaeocystis globosa initially blooms in the turbid and turbulent waters of early spring under low light conditions. The experiment on nitrate starvation showed that a lack of nitrate induces flagellum abscission and the formation of static cells and colonies in the life history of Phaeocystis globosa. Nitrate starvation induces flagellum abscission of Phaeocystis globosa and colony formation but motile capacity is recovered when nitrate levels increase. This is consistent with the fluctuations of Phaeocystis globosa biomass observed in the marine environment. |
| 陈加雄,李伟滨,廖小珊,林传旭.2015.球形棕囊藻的负趋光性和硝酸盐饥饿诱导鞭毛脱落试验[J].水生态学杂志,36(5):58-62. |
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