Controlling the life cycle of the green macroalga Ulva (Chlorophyta) is essential to maintain its efficient aquaculture. A fundamental shift in cultivation occurs by transforming the thallus cells into gametangia and sporangia (sporulation), with the subsequent release of gametes and zoids. Sporulation occurrence depends on algal age and abiotic stimuli and is controlled by sporulation inhibitors. Thus, quantification of sporulation intensity is critical for identifying the biotic and abiotic factors that influence the transition to reproductive growth. Here, we propose to determine the sporulation index by measuring the number of released gametes using flow cytometry, in proportion to the total number of thallus cells present before the occurrence of the sporulation event. The flow cytometric measurements were validated by manually counting the number of released gametes. We observed a variation in the autofluorescence levels of the gametes which were released from the gametangia. High autofluorescence level correlated to phototactically active behaviour of the gametes. As autofluorescence levels varied between different groups of gametes related to their mobility, flow cytometry can also determine the physiological status of the gametes used as feedstock in seaweed cultivation.

中文翻译：

---

流式细胞仪测量作为培养的大藻Ulva（Chlorophyta）孢子形成强度的替代指标

控制绿色大型藻类（绿藻）的生命周期对于维持其有效的水产养殖至关重要。培养过程的根本转变是将丘疹细胞转化为配子和孢子囊（孢子形成），随后释放配子和类固醇。孢子形成的发生取决于藻龄和非生物刺激，并受孢子形成抑制剂的控制。因此，孢子形成强度的定量对于鉴定影响向生殖生长过渡的生物和非生物因素至关重要。在这里，我们建议通过使用流式细胞仪测量释放的配子的数量来确定孢子形成指数，该数量与发生孢子事件之前存在的thallus细胞的总数成比例。通过手动计数释放的配子的数量来验证流式细胞仪的测量结果。我们观察到了从配子体释放的配子的自发荧光水平的变化。高自发荧光水平与配子的光战术活性行为相关。由于不同组配子之间的自体荧光水平随其活动性而变化，流式细胞术还可以确定用作海藻栽培原料的配子的生理状态。