Asexual and sexual life cycle events were studied in cultures of the toxic marine dinoflagellate Protoceratium reticulatum. Asexual division by desmoschisis was characterized morphologically and changes in DNA content were analyzed by flow cytometry. The results indicated that haploid cells with a C DNA content occurred only during the light period whereas a shift from a C to a 2C DNA content (indicative of S phase) took place only during darkness. The sexual life cycle was documented by examining the mating type as well as the morphology of the sexual stages and nuclei. Gamete fusion resulted in a planozygote with two longitudinal flagella, but longitudinally biflagellated cells arising from planozygote division were also observed, so one of the daughter cells retained two longitudinal flagella while the other daughter cell lacked them. Presumed planozygotes (identified by their longitudinally biflagellated form) followed two life-cycle routes: division and encystment (resting cyst formation). Both the division of longitudinally biflagellated cells and resting cyst formation are morphologically described herein. Resting cyst formation through sexual reproduction was observed in 6.1% of crosses and followed a complex heterothallic pattern. Clonal strains underwent sexuality (homothallism for planozygote formation and division) but without the production of resting cysts. Ornamental processes of resting cysts formed from the cyst wall under an outer balloon-shaped membrane and were fully developed in <1 h. Obligatory dormancy period was of ∼4 months. Excystment resulted in a large, rounded, pigmented, longitudinally biflagellated but motionless, thecate germling that divided by desmoschisis. Like the planozygote, the first division of the germling yielded one longitudinally biflagellated daughter cell and another without longitudinal flagella. The longitudinal biflagellation state of both sexual stages and of the first division products of these cells is discussed.

在有毒的海洋鞭毛藻网状原藻的培养物中研究了无性和性生活周期事件。通过去粘虫作用进行无性分裂的形态学表征，并通过流式细胞仪分析DNA含量的变化。结果表明，具有C DNA含量的单倍体细胞仅在光亮时期发生，而从C到2C DNA含量（指示S期）的转变仅在黑暗期间发生。通过检查交配类型以及性阶段和细胞核的形态来记录性生活周期。配子融合产生具有两个纵向鞭毛的扁平虫，但是也观察到了由扁平虫分裂产生的纵向双鞭毛细胞，因此一个子细胞保留了两个纵向鞭毛，而另一个子代细胞缺少它们。推定的扁桃体（通过其纵向双鞭毛形式识别）遵循两条生命周期路线：分裂和包囊（静止的囊肿形成）。本文在形态学上描述了纵​​向双鞭毛细胞的分裂和静止的囊肿形成。在6.1％的杂交中观察到通过有性生殖而形成的静止性囊肿，并遵循复杂的异硫杂草模式。克隆菌株经历了性行为（扁桃体形成和分裂的同态性），但没有产生静止的囊肿。静止的囊肿的装饰过程由囊壁形成，位于外球囊状膜下，并在不到1小时内完全发育。强制性休眠期约为4个月。囊肿导致大的，圆形的，有色的，纵向双鞭毛的但静止不动的类幼芽，由去潮分裂分开。像扁平虫一样，幼芽的第一部分产生一个纵向双鞭毛子细胞，另一个没有纵向鞭毛。讨论了这些细胞的有性阶段和第一分裂产物的纵向双鞭毛状态。