摘要
为了探讨光照对微囊藻形态的影响,研究了6株不同种的群体微囊藻在不同光强下群体形态的变化及其响应机制。研究发现,随着光强的增加,6株群体微囊藻的群体尺寸变大。当光强为80—200μmol/(m2·s)时,群体微囊藻DH-M1和DC-M2的比生长速率显著增大,而另4株在高光强下比生长速率无显著性差异;对多糖含量分析发现,高光强对群体微囊藻TH-M2、DC-M1、FACHB1174和FACHB1027胞外及胶被多糖的分泌与释放有显著的促进效果,而DH-M1和DC-M2多糖含量增加不明显。对于不同的微囊藻株,高光强促进群体形态变化的作用机理不同:光饱和点低的微囊藻是通过分泌大量的胞外及胶被多糖使群体尺寸变大,而光饱和点高的微囊藻是通过生长来促进群体尺寸的增大。此外,对产毒藻株在不同光强下的毒素基因表达及胞内毒素测定发现,高光强组的群体微囊藻mcyB和mcyD表达量升高,且胞内微囊藻毒素含量增加显著,推测微囊藻毒素也可能是影响微囊藻群体形态及大小的作用因子之一。
Microcystis has been recognized as the dominant bloom-forming organism in eutrophic lakes world-widely. Its dominance in natural circumstances results from a variety of adaptive strategies developed byMicrocystis of which the essence is to exist in the form of colonies. The existence and size ofMicrocystis colonies change in response to the cyclical rhythms of key factors such as temperature and light. For example, summer is a preferable season forMicrocy-stis to form colonies in large sizes, while in winter and early spring the organism are more readily to maintain a form of either single cells or small colonies. To understand how light regulates the morphology of colonialMicrocystis, we se-lected six different species/strains （TH-M2, DC-M1, FACHB1174, FACHB1027, DH-M1 and DC-M2） of colonialMi-crocystis and compared their responses to varied irradiance, in terms of colony size, growth, content of EPS and micro-cystins. It showed that the colony sizes of allMicrocystis were dramatically enhanced by the increased light intensity. When the light intensity was in the range of 80-200μmol/（m2？s）, the enlargement was caused by the significant in-crease in EPS production in high light saturation point strains TH-M2, DC-M1, FACHB1174 and FACHB1027. However, the enlargement was caused by the increased growth rate in low light saturation point strains DH-M1 and DC-M2. This implied that the mechanisms inducing the enlargement of colony size at high light intensities were diverse among dif-ferent species/strains ofMicrocystis. In high light saturation point strains the enhanced production of EPS played an important role in forming larger colonies, probably via the strengthened adhesion of single cells; whereas in high light saturation point strains the increase in colony size is most likely due to a faster growth rate. We also examined the tran-scriptional levels ofmcy genes and concentrations of intracellular microcystins. It was observed that at high light inten-sity the expression ofmcyBandmcyDwere enhanced in
出处
《水生生物学报》
CAS
CSCD
北大核心
2014年第1期35-42,共8页
Acta Hydrobiologica Sinica
基金
云南省–国家自然科学基金联合项目(U0833604)
国家自然科学基金(31070355)资助
关键词
群体微囊藻
群体尺寸
光强
生理机制
ColonialMicrocystis
Colony size
Light
Physiological mechanism
