Cytoplasmic streaming in giant algal cells: A historical survey of experimental approaches |
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Authors: | Noburô Kamiya |
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Institution: | (1) National Institute for Basic Biology, Myodaijicho, 444 Okazaki |
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Abstract: | Various methods have been used to study cytoplasmic streaming in giant algal cells during the past three decades. Simple techniques
can be used with characean internodal cells to modify the cell constitution in various ways to gain insight into the mechanism
of cytoplasmic streaming. Another method involves isolatingin vitro a huge drop of uninjured endoplasm, to examine its physical and dynamic properties. The motive force responsible for streaming
has been measured by three different techniques with similar results. Subcortical fibrils consisting of bundles of F-actin
with the same polarity are indispensable for streaming. Differential treatment of the endoplasm and ectoplasm has shown that
putative characean myosin is localized in the endoplasm. Studies of the roles of ATP, Mg2+, Ca2+, H+ etc. in the streaming have been conducted by cellular perfusion, which allows removal of the tonoplast, or by techniques
permeabilizing the protoplasmic membrane. A slow version of the movement can even be artificially reproduced by combining
characean actinin situ and exogenous myosin in the presence of Mg-ATP. The findings thus far obtained support the hypothesis that cytoplasmic streaming
in characean cells is caused by an active shearing force produced by interaction of the actin filament bundles on the cortex
with myosin in the endoplasm. |
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Keywords: | Cell model Cell surgery Cellular perfusion Chara Cytoplasmic streaming Nitella |
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