ELECTRON MICROSCOPY OF MITOSIS IN A RADIOSENSITIVE GIANT AMOEBA
Pelomyxa illinoisensis amoebae, the large radiosensitive species, were fixed in OsO/sub 4/ and embedded in either Epon 812 or methacrylate. Ultrastructural morphology is demonstrated in subnuclear structures at interphase and during specific times in mitosis. Evidence of nuclear envelope breakdown and reconstruction is presented. Fragments of nuclear envelope membranes are traced throughout metaphase and anaphase to telophase. Annuli in the nuclear envelope and its fragments are demonstrated. P. illinoisensis is unique in mitochondrial arrangement during metaphase and anaphase-- mitochondria are aligned at the ends of fibrils distal to the chromosomes at the positions occupied by centrioles in other types of cells; there they remain until the end of anaphase. The radioresistant amoebae, Pelomyxa carolinensis and Amoeba proteus do not have polar mitochondria. P. illinoisensis also differs from the two radioresistant species in nucleolar morphology during interphase, and in the manner of nucleolar dissolution during prophase. On the other hand, helical coils are shown in the interphase nucleoplasm which appear similar to those in the radioresistant amoebae, P. carolinensis and A. groteus. A blister stage in the telophase of P. illinoisensis is described which is interpreted to be the result of a rapid nuclear expansion leading to interphase. This has not been observed in the radioresistant amoebae. (auth)
- Research Organization:
- Argonne National Lab., Ill.; Ames Lab., Ames, Iowa
- DOE Contract Number:
- W-31-109-ENG-38
- NSA Number:
- NSA-17-035335
- OSTI ID:
- 4661252
- Report Number(s):
- TID-17851; UAC-7075
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- United States
- Language:
- English
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