Abstract Nile tilapia can achieve sexual maturity before reaching market size, which can be a great problem for production farms. To circumvent this problem the standard solution is to use androgen treatment to produce only male fish. However, the use of hormones has undesirable environmental issues due to residues in the water. One alternative would be by producing sterile triploid fish, which is conceptually possible by mating tetraploid x diploid. Therefore, our objective was to develop a tetraploid Nile tilapia broodstock. We performed three experiments, where females were hormonally induced spawning, oocytes were collected, fertilized with a semen pool, and eggs were incubated at 27 °C. In experiment I (E-I), we determined the first cleavage interval (FCI) to establish a suitable moment for heat shock. Using the obtained FCI of 90 min, we designed the Experiment II (E-II) with nine treatments: control (no shock); one shock (40 °C) at 60 min post-fertilization of 1, 2, 3 or 4 min duration; and two shocks (40 °C) at 50 and 70 min post-fertilization of 1, 2, 3 or 4 min. The ploidy status of juveniles was evaluated by flow cytometry, however, no tetraploid was found, thus, using the results from E-II, a third experiment was devised. In Experiment III (E-III), we applied nine treatments: control (no shock); one shock (40 °C) at 75, 80, 85 or 90 min post-fertilization; or two shocks (40 °C) at 75 and 85 min, 80 and 90 min, 85 and 95 min or 90 and 100 min post-fertilization, all shocks were of 4 min. Triploid, mosaic, and aneuploid tilapias were identified in the treated groups. Even though we analyzed a large number of animals (>2800) that were submitted to different heat shocks applied at suitable windows of tetraploid induction, no 100% 4 N juvenile was found, indicating that the generation of tetraploid Nile tilapia broodstock using the protocols described is impractical.

中文翻译：

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尝试通过热激诱导生产尼罗罗非鱼四倍体系

摘要 尼罗罗非鱼在达到市场规模之前就已经达到性成熟，这对养殖场来说是一个很大的问题。为了规避这个问题，标准的解决方案是使用雄激素处理来只生产雄鱼。然而，由于水中的残留物，激素的使用具有不希望的环境问题。一种替代方法是生产不育的三倍体鱼，这在概念上可以通过四倍体 x 二倍体的交配来实现。因此，我们的目标是开发四倍体尼罗罗非鱼亲鱼。我们进行了三个实验，其中雌性被激素诱导产卵，收集卵母细胞，用精液池受精，并在 27°C 下孵化卵。在实验 I (EI) 中，我们确定了第一个裂解间隔 (FCI) 以建立合适的热休克时刻。使用获得的 90 分钟 FCI，我们设计的实验 II (E-II) 有九个处理：对照（​​无休克）；在 1、2、3 或 4 分钟的受精后 60 分钟进行一次电击 (40 °C)；受精后 1、2、3 或 4 分钟，分别在 50 和 70 分钟进行两次冲击 (40 °C)。通过流式细胞术评估幼鱼的倍性状态，但是没有发现四倍体，因此，使用 E-II 的结果，设计了第三个实验。在实验三（E-III）中，我们采用了九种处理方法：对照（无休克）；在受精后 75、80、85 或 90 分钟进行一次电击 (40 °C)；或在受精后 75 和 85 分钟、80 和 90 分钟、85 和 95 分钟或 90 和 100 分钟进行两次冲击 (40 °C)，所有冲击均为 4 分钟。在处理组中鉴定出三倍体、镶嵌体和非整倍体罗非鱼。尽管我们分析了大量动物 (>