Analysis apaptosis phenomena of nuclei in zygospores of Phycomyces

植菌是多核的，当两种交配类型交配时，数千个核从亲本配子体转移到合子孢子中。然而，只有一个或两个二倍体核能够存活到大约6个月的休眠期结束。其余的核随着合子孢子年龄的增加而失去功能并逐渐消失。为了探讨这种细胞核凋亡现象的机制，我们观察了合子孢子的特征随年龄的变化。交配第10天后，合子孢子的物理硬度增加，约为交配第10天前的5倍。硬度恢复到合子萌发前的正常水平。出现一个大的中央油滴是10天后合子孢子的另一个特征。油滴也在发芽前消失。对不同年龄的裂裂合子孢子的孢子囊和再生的菌丝上发育的孢子核的遗传分析表明，减数分裂在交配后第10天之前没有完成。第10天后，合子未发生任何结构再生。选择具有不同遗传标记的异核亲本之间形成的合子孢子，将其包括细胞核的原生质转移到一个营养不足突变体的孢子囊片段中。孢子分析表明，合子孢子在交配后30天左右发生减数分裂。显微镜和电镜观察表明，在交配后7 ~ 8天，核的体积增加，但在交配后第10天至第20天，核的体积急剧减少。30天后，衰老的合子孢子中出现了一些退化核的聚集。细胞核膜破裂。这些发现表明，除了存活的二倍体核（ei）外，所有的细胞核在交配后10天都失去了功能。少

Phycomyces is multinucleate and thousands of nuclei transfer from parental gametangia into zygospores when two mating types were mated. Only one or two diploid nuclei, however, are able to survive until the end of the dormancy period of about 6 months. The other remained nuclei lose their functions and gradually disappear with an increase in the age of zygospores. To explore the mechanisms of this apaptosis phenomenon of nuclei, the zygospores were inspected for the age-dependent changes of their characteristics.1. The zygospores increased in their physical hardness after the 10th day of the mating, about 5 times harder than the zygospores before 10 days after mating. The hardness recovered to the normal just before the zygospore germination. Emergence of a large central oil-drop is another characteristic of the post-10th-day zygospores. The oil drop also disappeared before the germination.2. Genetic analyses of nuclei in the spores developed on sporangiophores and hyphae which regener … More ated from the incised zygospores with different ages revealed that meiosis has not completed before 10th day after mating. No regeneration of any structures occurred on the post-10th day zygospores.3. The zygospores formed between the heterokaryotic parents with several different genetic markers were selected and their protoplasm including nuclei were transferred into the sporangiophore segments of an auxotropic mutant. The spore analysis for recombination of genetic markers of the regenerants on the sporangiophore segments implied that meiosis occurred in the zygospores around 30th day after the mating.4. Microscopic and electromicroscopic observations revealed that the nuclei increased in their volumes at the 7-8th days after mating but sharply decreased after the 10th day till the 20th day.5. Aggregation of some degenerated nuclei was found in the aged zygospores after the 30th day. Nuclei with broken membrane were also found. These findings imply that all the nuclei except for the survive diploid nucleus(ei) lose their functions 10 days after mating. Less