三角褐指藻(Phaeodactylum tricornutum)形态及其变异现象的研究

Studies on the Morphotype and Morphological Variation of Phaeodactylum tricornutum

分别对青岛、浙江、上海和厦门四地的三角褐指藻藻种及单个细胞克隆后多个藻株的形态及其变异现象进行了比较研究。青岛、上海藻种短期培养后 ,培养液细胞基本由梭形细胞组成 ;浙江和厦门藻种则基本由三出放射形细胞组成。正常培养液中卵形细胞比例均在 0 .1%以下。特定条件下 ,梭形和三出放射形细胞均能产生卵形细胞 ,卵形细胞也能发育成梭形或三出放射形细胞 ;三出放射形细胞可能经“突变”或“定向变异”转变成梭形细胞 ,而梭形细胞培养液中没有出现三出放射形细胞。培养液比重、温度及光照条件的改变短期内对细胞形态类型的转变没有明显影响 ;淡水和低温 ( 4℃～ 8℃ )的长期胁迫能使梭形和三出放射形藻株发生高比例的卵形细胞。

The morphotypes and morphological variations of Phaeodactylum tricornutum , collected from cultures of Qingdao, Zhejiang, Shanghai and Xiamen were studied. The normal cultures of Qingdao and Shanhai had a high proportion of over 95% fusiforms, while over 90% of the cultures of Zhejiang and Xiamen consisted of triradiates. Only very small proportions of ovals(<0.1%) were found in the normal cultures. 2 clones of fusiform cells and 6 clones of triradiate cells were established. It was shown that both triadiates and fusiforms could produce ovals by division, and the ovals so produced could multiply to form further ovals, or grow either two or three arms, generally two, to form fusiform or triradiate cells. A proportion of the triadiate cells could shorten one arm and gradually pass, during successive divisions into the fusiform cells, however there was little to suggest that fusiform cells ever became triradiate by growing out a third arm. The effect of short period changes in water salinity, temperature and light intensity on the conversion of morphotype was not notable. A high proportion of ovals was produced both in fusiform clones and triadiate clones under long term stress of freshwater and lower temperature(4～8℃).