双角多甲藻有性生殖及厚垣合子形成条件的研究

SEXUAL REPRODUCTION AND HYPNOZYGOTE FORMATION IN THE FRESHWATER DINOFLAGELLATE PERIDINIUM BIPES STEIN

双角多甲藻在MCV合成培养基中的最短加倍时间约6天,其有性生殖可用缺氮培养基进行诱导。批量培养的迟滞期和指数生长期末细胞的诱导效率最高,合子产率可达70％。厚垣合子形成的最适温度为19℃、pH7.4、光强5200lx。在鉴定的70个克隆藻株中,有2株为同宗配合;48株为异宗配合,其中“+”株23个,“-”株25个;其余20株未能诱导出有性生殖。合子开始萌发时,在中层壁和内层壁之间的空间出现1至多个“管状结构”,协助原生质体将合子壁顶破,外包一层薄壁的原生质体放出。

The optimum growth condition for Peridinium bipes in synthetic MCV medium was at 18℃, pH 7.4 and 5000 lx. Under this condition, the doubling time was about 6 days. Sexual reproduction was induced by transferring vegetative cells into nitrogen-free MCV medium. The maximum frequency of gamete induction was achieved at late lag stage and late exponential growth stage of batch culture, and the rate of hypuozygote formation was as high as 70％. The optimum condition for zygote formation was almost the same as that for growth. Mating types of 70 clones were identified. Two of them were homothallic. Forty eight clones were heterothallic; among these, 23 were 'plus' and 25 'minus'. In the remaining 20 clones, sexual reproduction was not observed. During the process of hypnozygote germination, one to several 'tubular structure' appeared in the space between mesospore wall and endospore wall. Obviously, this structure could help the pre-meiocyte rupturing the thick mesospore wall by offerring mechanical force.