J Integr Plant Biol. ›› 1997, Vol. 39 ›› Issue (7): -.

• Research Articles •    

Morphological Studies on the Process of Chromosome Construction in Physarum polycephalum

Zeng Xian-lu, Jiao Ming-da, Wang Xiao-guang and Hao Shui   

Abstract: The process of morphological construction of chromosomes in Physarura polycephalum was studied with transmission electron microscopy. The synchronous plasmodinm materials were sampled in 5 to 10 min time intervals during the mitotic cycle. In mitotic prophase, the compact lumped chromatin of Ga-phase gradually decondensed into loose structure. Meanwhile, the loose chromatin gradually reorganized into the chromatin thread structure that was about 80 to 150 nm in diameter. This process was completed in about 30 min. In the loose chromatin threads many condensed regions appeared which increased and expanded, as the prophase proceeded, and the chromatin thread became shorter and thicker. Finally, the metaphase chromosomes of 300 to 350 nm in diameter were formed. This process also took about 30 min. At the same time, nucleoli gradually moved from the center to the edge of the nucleus and disintegrated in about 50 min in the prophase. The results revealed that the whole process of morphological construction of chromosomes in this species was completed in about one hour. The process could be divided into two consecutive steps, that is, the reorganization and condensation of chromatin. The 25 to 30 nm chromatin fibers were the fmest morphological unit that could be identified.

Key words: Physarum polycephalum, Mitotic prophase, Chromosome, Morphological constructing process

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