A general method for efficiently hatching sexually produced diapausing embryos of the microcrustacean Daphnia is valuable for establishing Daphnia as a genetic model system. In this study, we examine the effect of ultraviolet light and different amounts of storage time in darkness on the hatching efficiency in two species of the Daphnia pulex species complex, D. pulex and Daphnia pulicaria. We identified a set of lighting conditions that can trigger 80% to ~100% hatching rate for embryos produced through selfing, outcrossing, and obligate parthenogenesis. Furthermore, we found that a storage time of at least 2 weeks in the dark before exposing embryos to ultraviolet light is critical for achieving high hatching rate. The identification of these key factors for hatching diapausing embryos can greatly facilitate future Daphnia research involving complex breeding designs as well as investigating the genetic switch that activates the hatching of diapausing embryos.

中文翻译：

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一种孵化水蚤（Daphnia pulex）种复合体（甲壳纲，Anomopoda）的滞育性胚胎的有效方法。

有效地孵化有性繁殖的微甲壳类水蚤的胚胎的一般方法对于建立水蚤作为遗传模型系统是有价值的。在这项研究中，我们研究了紫外线和黑暗中不同的储存时间量对水蚤（Daphnia pulex）两种复合种D. pulex和水蚤（Daphnia pulicaria）的孵化效率的影响。。我们确定了一组光照条件，这些条件可以触发通过自交，异交和专性孤雌生殖产生的胚胎的80％至〜100％的孵化率。此外，我们发现在黑暗中将胚胎暴露于紫外线之前至少要保存2周，这对于获得高孵化率至关重要。确定孵化滞育胚胎的这些关键因素可以极大地促进将来的水蚤研究，涉及复杂的育种设计以及调查激活滞育胚胎孵化的遗传开关。