Methods for selection of Daphnia resting eggs: the influence of manual decapsulation and sodium hypoclorite solution on hatching rates.
Methods for selection of Daphnia resting eggs: the influence of manual decapsulation and sodium hypoclorite solution on hatching rates.
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水蚤休眠卵的选择方法：人工破壳和次氯酸钠溶液对孵化率的影响。
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发表时间：
2016
期刊：
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通讯作者：
P. Maia
中科院分区：
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作者：
T. A. Paes;A. C. Rietzler;P. Maia
枝海动物能够在一个保护性的抗药囊——表皮中产生休眠的卵，由于深色的色素沉淀，休眠的卵很难被观察到。因此，在孵化实验之前，必须考虑验证棘鱼休眠卵存活的方法。本研究旨在评价两个热带水生生态系统水蚤（Daphnia）的卵数，以及几种剥卵方法的效率。为了评估不同方法对孵化率的影响，我们测试了三种不同的条件：浸泡在次氯酸钠中，手动脱囊休眠卵和完整的epihippia。次氯酸盐溶液浸泡可以评估所研究生态系统中每个鳞茎休眠卵的数量差异。次氯酸钠浓度为2%，暴露20分钟是最有效的目视评价和分离静卵的方法。未分离棘球蚴静息卵的孵化率被低估（11.1±5.0%），表明需要量化和分离活卵的方法。次氯酸盐溶液处理的卵孵化率（47.2±7.34%）与人工脱囊的卵孵化率（53.7±13.24%）无显著差异。然而，在次氯酸盐中浸泡是一种更有效、更快、不需要人工操作的技术。
Cladocerans are able to produce resting eggs inside a protective resistant capsule, the ephippium, that difficults the visualization of the resting eggs, because of the dark pigmentation. Therefore, before hatching experiments, methods to verify viable resting eggs in ephippia must be considered. This study aimed to evaluate the number of eggs per ephippium of Daphnia from two tropical aquatic ecosystems and the efficiency of some methods for decapsulating resting eggs. To evaluate the influence of methods on hatching rates, three different conditions were tested: immersion in sodium hypochlorite, manually decapsulated resting eggs and intact ephippia. The immersion in hypochlorite solution could evaluate differences in numbers of resting eggs per ephippium between the ecosystems studied. The exposure to sodium hypochlorite at a concentration of 2% for 20 minutes was the most efficient method for visual evaluation and isolation of the resting eggs. Hatching rate experiments with resting eggs not isolated from ephippia were underestimated (11.1 ± 5.0%), showing the need of methods to quantify and isolate viable eggs. There were no differences between the hatching rate of resting eggs submitted to hypochlorite solution (47.2 ± 7.34%) and manually decapsulated (53.7 ± 13.24%). However, the immersion in hypochlorite was a more efficient technique, faster and not requiring manual ability.