家蚕胚胎发育初期受精核的分裂与移动观察及数值化分析

Division and Movement Observation and Digitalization Analysis of Bombyx mori Fertilized Nuclei in Early Embryonic Development

研究家蚕胚盘形成期受精核的分裂及移动速度,有助于了解家蚕胚胎最初的发育过程及对环境的感受性等。以家蚕卵着色非滞育性(pnd)品系和滞育卵品系C108为材料,经时观察产卵初期受精核的分裂,并估算受精核的移动速度及分裂频率。pnd品系卵在25℃±1℃保护条件下,于产卵后2 h受精,之后受精核开始分裂,分裂核的数量逐渐增加并同时向卵内四周移动,分裂核到达卵前极和后极的时间分别是9 h 30 min、10 h 30 min,到达卵腹侧和背侧的时间分别是9 h 40 min、9 h30 min。不同滞育性家蚕品系受精核的分裂周期不同,pnd品系为40 min,C108品系为60 min。由分裂核的位置推断:家蚕受精核的第1次分裂表现为左右核裂,第2次分裂表现为前后核裂,第3次核分裂表现为左右分裂和前后分裂同时进行,且至少前5次的核分裂表现为同步分裂。研究结果丰富了家蚕乃至昆虫早期胚胎发育特别是受精核的分裂周期及移动特点等生物学内容。

To study the division and movement of fertilized nuclei in the biastoderm formation stage of silkworm （Bombyx mori） will help understand the early developmental process and environmental perceptibility of silkworm embryos. In this study, silkworm strains with non-diapause （pnd） of egg coloration and with diapause （C108） of egg coloration were used as material for observation of nuclear division at early stage after oviposition and for estimation of movement speed and division frequency of the fertilized nuclei. The results showed that pnd eggs were fertilized at 2 h post oviposition un- der ℃±1℃. Then, the fertilized nuclei began to divide. Consequently, more and more divided nuclei emerged and moved towards edge of the egg. Time of the divided nucleus arriving at anterior and posterior poles of the egg was 9 h 30 min and 10 h 30 min respectively. Time of the divided nucleus arriving at ventral line and dorsal line of the egg was 9 h 40 min and 9 h 30 min respectively. The division cycle of fertilized eggs varied among silkworm strains with different diapause properties, being 40 min in pnd strain and 60 min in C108 strain. According to locations of the divided nuclei, it is sugges- ted that the first division of silkworm fertilized nucleus was in latitudinal direction, the second one was in meridinal direction, and the third one was in both latitudinal and meridinal directions. Moreover, at least the first 5 nuclear divisions were of syn-chronized division. These results enrich the knowledge on early embryonic development of silkworm and other insect, especially on division cycle and movement of fertilized nuclei.