Liu Yang, Xu Yao, Xiao Peng, Pan Qianqian, Yu Gongliang, Li Renhui
Key Lab of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Lab of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, China.
Harmful Algae. 2014 Jan;31:76-81. doi: 10.1016/j.hal.2013.09.012. Epub 2013 Oct 29.
Lake Taihu has been severely eutrophied during the last few decades and dense cyanobacterial blooms have led to a decrease in phytoplankton diversity. The cyanobacterial blooms in Lake Taihu were mainly composed of unicellular colony-forming Microcystis and filamentous heterocystous Dolichospermum (formerly known as planktonic species of Anabaena). In contrast to that of Microcystis spp., the fundamental knowledge about diversity, abundance and dynamics of Dolichospermum populations in Lake Taihu is lacking. The present study was conducted to understand genotypic distribution, dynamics and succession of Dolichospermum populations in Lake Taihu. By sequencing 688 internal transcribed spacer (ITS) regions between the 16S and 23S rRNA genes of Dolichospermum, we were able to confirm that all the sequences were Dolichospermum rather than Aphanizomenon. 118 different genotypes were identified from the obtained sequences, and two genotypes (W-type and L-type) were found to dominate in the lake, representing 36.6% and 26.2% of the total sequences, respectively. These two dominant genotypes of Dolichospermum displayed the significant seasonal pattern. Stepwise regressions analysis revealed that water temperature was associated with the two dominant genotypes. The combined results implied the possible existence of ecotypes in bloom-forming cyanobacteria, probably triggered by water temperature in the lake.
在过去几十年中，太湖已严重富营养化，密集的蓝藻水华导致浮游植物多样性下降。太湖的蓝藻水华主要由单细胞群体形成的微囊藻和丝状有异形胞的Dolichospermum（以前称为鱼腥藻的浮游物种）组成。与微囊藻属相比，关于太湖中Dolichospermum种群的多样性、丰度和动态的基础知识尚缺乏。本研究旨在了解太湖中Dolichospermum种群的基因型分布、动态和演替。通过对Dolichospermum的16S和23S rRNA基因之间的688个内部转录间隔区（ITS）进行测序，我们能够确认所有序列均为Dolichospermum而非束丝藻。从获得的序列中鉴定出118种不同的基因型，发现两种基因型（W型和L型）在湖中占主导地位，分别占总序列的36.6%和26.2%。Dolichospermum的这两种优势基因型呈现出明显的季节模式。逐步回归分析表明，水温与这两种优势基因型有关。综合结果表明，形成水华的蓝藻中可能存在生态型，这可能是由湖泊水温引发的。
