Plasma flow
The plasma flow (also cytoplasmic flow, cyclosis ) is a flowing movement of the cytoplasm including the organelles located therein , which can be observed in plants , algae , fungi and slime molds . In plant cells and in many cases also in algae cells, only the endoplasm moves , which surrounds the central vacuole and often also runs through it in the form of fine strands, while in multinucleated ( coenocytic ) algae and fungi that are not subdivided into cells, the flow runs through the entire organism and also theCell nuclei captured. In the multinucleated plasmodia of many slime molds, the direction of flow is reversed periodically (pendulum flow).
In biochemical terms, both the plasma flow and the muscle movement in animals and humans are based on an interaction of the cytoskeletal protein actin with the motor protein myosin . In plant cells and in algae, the myosin sits on the organelles, and these move along actin filaments , taking the cytosol , the liquid part of the cytoplasm, with them. The situation is completely different with the slime mold Physarum polycephalum : Its plasmodia look like amoebas , move amoeboid and feed like amoeba through phagocytosis . They can become very large and often branched and cover an area of up to one square meter. Their cytoplasm is differentiated (as in plants) into a gel-like , external ectoplasm and a solar -like , i.e. viscous endoplasm. The ectoplasm, like the actomyosin bundles known as stress fibers, can contract and relax again in animal cells (or, on a larger scale, muscle fibers and whole muscles), thereby causing the characteristic pendulum flow of the endoplasm.
literature
- T. Shimmen, E. Yokota: Cytoplasmic streaming in plants. In: Current Opinion in Cell Biology. 16 (2004), pp. 68-72, ISSN 0955-0674 , doi : 10.1016 / j.ceb.2003.11.009 , PMID 15037307 .
Web links
- Lexicon of Biology : Plasma Flow . Spectrum, Heidelberg 1999.
- Video of the plasma flow at Physarum polycephalum for download (AVI)
Individual evidence
- ^ FG Woodhouse, RE Goldstein: Cytoplasmic streaming in plant cells emerges naturally by microfilament self-organization. In: Proceedings of the National Academy of Sciences . 110 (2013), pp. 14132-14137, ISSN 1091-6490 . doi : 10.1073 / pnas.1302736110 , PMID 23940314 , PMC 3761564 (free full text).
- ↑ Shinji Yoshiyama, Mitsuo Ishigami, Akio Nakamura and Kazuhiro Kohama: Calcium Wave for Cytoplasmic Streaming of Physarum Polycephalum . In: Cell Biology International. 34 (2010), pp. 35-50. doi : 10.1042 / CBI20090158 .