水生态学杂志Issue(5)：58-62,5.DOI:10.15928/j.1674-3075.2015.05.009
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
摘要
Abstract
Phaeocystis globosa red tides frequently occur in the southeast coastal waters of China and adversely af-fect 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 mo-tile single cells that occurs with nitrate starvation.The study provides a theoretical basis for understanding the oc-currence and disappearance of Phaeocystis globosa red tides.A simple experimental device was designed and as-sembled 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 e-qual 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 mo-tile cells with flagellum display negative phototaxis,while static single cells and colonies do not.Nitrate is an im-portant 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 in-duced flagellum abscission of Phaeocystis globosa,resulting in the aggregation of cells to form colonies.Further-more,the addition of nitrate induced flagellum growth in static cells of Phaeocystis globosa.In conclusion,the mo-tile 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 for-mation but motile capacity is recovered when nitrate levels increase.This is consistent with the fluctuations of Phae-ocystis globosa biomass observed in the marine environment.关键词
球形棕囊藻/负趋光性/硝酸盐/饥饿诱导/鞭毛脱落Key words
Phaeocystis globosa/negative phototaxis/nitrate/nitrate starvation/flagellum abscission分类
生物科学引用本文复制引用
陈加雄,李伟滨,廖小珊,林传旭..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,2015,(5):58-62,5.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）。 （）
