Dieng Hamady, Boots Michael, Tamori Naoki, Higashihara Junko, Okada Takashi, Kato Kotaro, Eshita Yuki
Department of Infectious Disease Control, Faculty of Medicine, Oita University, Hasamamachi, Japan.
J Am Mosq Control Assoc. 2006 Sep;22(3):382-9. doi: 10.2987/8756-971X(2006)22[382:STAEDO]2.0.CO;2.
Fertility is a physiological process of great importance underlying the dynamics of mosquito populations. In transgenesis, it is a prerequisite for the production of subsequent generations and a crucial parameter for evaluating efficiency. Yet, ongoing success in mosquito vector transformation is being severely affected by low embryo survivability. In the prospect of overcoming this impediment, we investigated the darkening/hardening process of the chorion, the effects of some parameters required for transgenesis on hatch success, and erratic hatching in Aedes albopictus, a species that has not yet been targeted for transformation. The eggs from this species, when placed in a moistened environment while whitish, become dark and yet still remain soft approximately 2 h 10 min postoviposition. Those reared in a high moisture environment hatched at a high rate compared with their counterparts submitted to a drier environment. Submission of eggs to p-nitrophenyl-p'-guanidino-benzoate, a substance known to delay the darkening/delay process, resulted in a hatch rate lower than that from eggs soaked in distilled water, which suggests a negative impact on viability. Heat-shock treatment did not taint embryo viability. Overall, eggs displayed a tolerance to an hour of heat shock at 39 degrees C but still hatched at a considerable rate after a 1 hr exposure to 42 degrees C. Hatching was erratic, with a high rate of hatching on the initial flooding and lower rates of hatching on subsequent floodings, all of which resulted cumulatively in considerable hatch success. Our results should serve as a useful reference for the production of both transgenic and laboratory strains of floodwater Aedes mosquitoes.
繁殖力是蚊子种群动态背后极为重要的生理过程。在转基因过程中，它是产生后代的前提条件，也是评估效率的关键参数。然而，目前蚊子载体转化的成功正受到胚胎存活率低的严重影响。为克服这一障碍，我们研究了白纹伊蚊（一种尚未进行转化研究的物种）卵壳的黑化/硬化过程、转基因所需的一些参数对孵化成功率的影响以及不规则孵化情况。该物种的卵在产出时呈白色，放置在潮湿环境中后，大约在产卵后2小时10分钟会变黑，但仍保持柔软。与处于较干燥环境中的卵相比，在高湿度环境中饲养的卵孵化率较高。将卵置于对硝基苯基-对'-胍基苯甲酸酯（一种已知会延迟黑化/硬化过程的物质）中处理后，其孵化率低于浸泡在蒸馏水中的卵，这表明该物质对卵的活力有负面影响。热休克处理并未损害胚胎活力。总体而言，卵在39摄氏度下耐受1小时热休克，但在暴露于42摄氏度1小时后仍有相当比例的卵孵化。孵化情况不稳定，初次浸水时孵化率高，后续浸水时孵化率较低，但总体孵化成功率较高。我们的研究结果应为转基因和实验室品系的洪水伊蚊的生产提供有用参考。
