Prorocentrum minimum is a potentially toxic marine dinoflagellate that often forms massive blooms in estuarine and coastal sea waters. In this study, the life cycle of P. minimum was investigated and sexual reproduction in culture was described for the first time. Morphology of the mitotic stages was revised and several distinguishing features from sexual steps were described. The sexual reproductive stages were observed in the stationary culture and compared with a well‐studied closely related species, Prorocentrum micans. Prorocentrum minimum has a haplontic life cycle and homothallic sexual process. The gametes were isogamous and morphologically indistinguishable from the vegetative cells. Unlike P. micans, P. minimum isogametes fused, but did not conjugate, partially reorganizing their cell coverings. Newly formed planozygotes were distinguished by their irregular shape and a large asymmetrically located nucleus. No long‐term resting cyst stages (hypnozygotes) were documented. The late planozygotes underwent meiosis and formed tetrads of cells. The second meiotic division could be delayed or arrested in one of the daughter nuclei leading to formation of trinucleate cells with three pairs of flagella. So, similar to P. micans, P. minimum may have two possible scenarios of sexual division: (a) formation of a four‐cell stage through two successive divisions or (b) asynchronous divisions of the zygote. Changes in the DNA content were confirmed by quantitative image cytometry.

中文翻译：

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海洋最低鞭毛原中心（Dinophyceae，Prorocentrales）的生命周期阶段和有性生殖的证据。

最低原肠是有潜在毒性的海洋鞭毛藻，经常在河口和沿海海水中形成大量的水华。在这项研究中，研究了最小体育杆菌的生命周期，并首次描述了文化中的有性生殖。修订了有丝分裂阶段的形态，并描述了有性步阶的几个区别特征。在固定培养中观察到有性生殖阶段，并将其与经过充分研究的密切相关的物种Prorocentrum micans进行比较。最低原肠具有生命周期和同型性过程。配子是同性的，在形态上与营养细胞没有区别。与米克假单胞菌不同，体育最小亚种配子融合，但不缀合，部分重组其细胞覆盖。新形成的平合子以其不规则形状和大的不对称定位的核而著称。没有长期静止的囊肿分期（hyponozygotes）的记录。晚期的扁桃体进行了减数分裂并形成了细胞四联体。减数分裂的第二分裂可能会延迟或停在子核之一中，从而导致三对鞭毛形成三核细胞。这样，类似于P.藻，最小P.可以具有性别分工的两种可能的情况：（1）通过两个连续分裂或（b）的合子异步区划四细胞期的形成。通过定量图像细胞术确认DNA含量的变化。