cytochalasin

(biochemistry) One of a series of structurally related fungal metabolic products which, among other effects on biological systems, selectively and reversibly block cytokinesis while not affecting karyokinesis; the molecule with minor variations consists of a benzyl-substituted hydroaromatic isoindolone system, which in turn is fused to a small macrolide-like cyclic ring.

A class of lipophilic antibiotics produced by fungi. The cytochalasins elicit in animal and plant cells a puzzling diversity of membrane phenomena. There is evidence that numerous chemicals, including cytochalasins, interact directly with plasma membrane components, modulate activity of membrane-bound enzymes, and often produce changes in membrane structure.

In animals, cytochalasins inhibit cytokinesis, cell movement, and embryonic morphogenesis, as well as intracellular movement such as the transport of melanin granules. In addition, nuclear extrusion is induced; lymphocyte-mediated destruction of target cells is inhibited; and there is selective “pulverization” of certain chromosomes, which are converted to the unraveled, interphase form, while the other chromosomes in the cell remain in the condensed, metaphase form.

In plants, intracellular movements such as cytoplasmic streaming and chloroplast movements are inhibited. Cytochalasins also inhibit root growth and water uptake in onion seedlings; cells become more spherical in shape.

The great value of the cytochalasins as research tools is that they appear to achieve their reversible impact on cell behavior with a minimum of undesirable side effects such as inhibition of respiration or protein synthesis. Cytochalasin is extensively applied as a chemical “scalpel” to enucleate mammalian cells rapidly, precisely, and efficiently in studies of nuclear-cytoplasmic relations and in cell hybridization and nuclear transplant work. Another major application is in examining the consequences of arrested cytoplasmic movement.

Any of a group of substances derived from molds that interfere with the division of cytoplasm, inhibit cell movement, and cause extrusion of the nucleus.