| Autor: |
MARUYAMA, Keizo, KUME, Nahoaki, OKUDA, Mitsuro |
| Zdroj: |
Journal of Electron Microscopy; Jul1985, Vol. 34 Issue 3, p162-168, 7p |
| Abstrakt: |
The method of direct freeze-fracture and thaw-fixation for scanning electron microscopy has been developed further for the study of chromosomes; the fixation of freeze-fractured cells was postponed until after treatment with varied solutions. This method opened the possibility for experimental studies on chromosome morphology. In this paper, effects of divalent cations on chromosome morphology were reported. Roots of were freeze-fractured in liquid nitrogen and then thawed in a DMSO solution containing 2 mM Ca and 5 mM Mg. They were washed and incubated in a buffer solution containing various concentrations of Ca and Mg, and then were fixed with glutaraldehyde. At a concentration of Ca over 1 mM or Mg over 5 mM, chromosomes were compact with knobs or protuberances on the surface. As the concentration of divalent cations was reduced, the chromosomes expanded successively and twisted fibers became evident. When divalent cations were depleted with EDTA, fibers 30–40 nm in diameter were seen extending along the long axis of the chromatid arm. It appeared that a certain number of the longitudinally oriented fibers twisted and coiled to form a chromatid. [ABSTRACT FROM PUBLISHER] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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