在人工培养条件下，海带配子体能够进行有丝分裂以形成无性繁殖系(克隆)。为分析海带配子体克隆有丝分裂的细胞学特征。本实验首先制备海带配子体石蜡切片，利用免疫荧光技术，结合DAPI染色，获得其核分裂各期的细胞结构变化图像。结果显示，通过DAPI染色，清晰展示出不同分裂期核大小及形态的变化；通过免疫荧光技术，成功观察到由中心体发射出的纺锤丝及“钟罩”状纺锤体。随后，制备海带配子体的超薄切片，透射电镜下，于细胞板的形成位置观察到由质膜内陷产生的向内生长的分裂沟。分裂沟的最前端呈现封闭的弯曲状，其中无或仅少量细胞壁成分，以促成向心式生长，直至最后接触、融合和形成新的细胞壁，完成胞质分裂。最后通过压片法制备染色体，苏木素染色后利用DAPI进行复染，获得配子体完整细胞的染色体图像，从而进一步明确海带配子体具有31条染色体。研究表明，本实验首次获得海带配子体有丝分裂完整过程(核分裂和胞质分裂)的图像和结构特征，同时完成海带配子体完整细胞的核型分析。实验结果为海带细胞遗传学研究提供了更多准确数据，也为褐藻胞质分裂方式及机制的探讨提供了新的材料和证据。

Gametophyte clones of Saccharina japonica can be established through the induction of mitosis in gametophytes under artificial culture conditions. However, there have been few reports on the cytological characteristics of mitosis in these clones. This study presents the first observation of the cellular structure during the mitosis phases of kelp gametophytes using paraffin sections, immunofluorescence technique coupled with DAPI staining. Changes in the size and morphology of the gametophyte nucleus during the phases of mitosis were clearly illustrated by DAPI staining. The spindle fibers, originating from the centrosome, and cage-shaped spindle were successfully visualized. Ultrathin sections revealed cleavage furrows at the positions of cell plates under a transmission electron microscope. These furrows, with closed curved front ends formed by invagination of the plasmalemma, grew centripetally until they contacted and fused, leading to the construction of a new cell wall and completion of cytokinesis. The chromosomes of the gametophyte cell were prepared by pressing method, stained with hematoxylin and counterstained with DAPI. It was confirmed that there were 31 chromosomes in the gametophyte of S. japonica. The characterizations of mitosis of S. japonica gametophytes including karyokinesis and cytokinesis were firstly observed in the study, and chromosomes in the intact cell of gametophyte were also illustrated. It provided accurate data for the cytogenetic study of S. japonica, and provided new evidence for the study of cytoplasmic division of brown algae.

S 917.3

国家自然科学基金(32172963，41376136)；国家“双一流”水产学科