Microtubules, disorganization

Himmelspach R., Williamson R.E., and Wasteneys G.O. 2003. Cellulose microfibril alignment recovers from DCB-induced disruption despite microtubule disorganization. Plant J 36 565-575. 

Lau 0-L, John WW, Yang SF (1977 b) Inactivity of oxidation products of lAA to stimulate ethylene production in mungbean hypocotyls. Plant Physiol 59 Suppl, p 11 Lawson VR, Weintraub RL (1975) Interactions of microtubule disorganizers, plant hormones, and red light in wheat coleoptile segment growth. Plant Physiol 55 1062-1066 Lee BO(1961) Effect of Line tin on the fertility of some strains of Neurospora crassa. Nature 192 288... 

The answer is c. (Hardman, pp 1260—1262.) Paclitaxel is a large structural molecule that contains a 15 membered taxane ring system. This anti cancer agent is an alkaloid derived from the bark of the Pacific yew tree. Its chemotherapeutic action is related to the microtubules in the cell. Paclitaxel promotes microtubule assembly from dimers and causes microtubule stabilization by preventing depolymerization. As a consequence of these actions, the microtubules form disorganized bundles, which decreases... 

It was found that 1 acted as an antimitotic agent, not binding to tubulin, but by disorganizing the microtubule network in some fashion. In addition, it is a DNA minor groove guanine-specific alkylating agent [1]. The Et s showed potent inhibition of DNA and RNA synthesis and of RNA polymerase activity, but its inhibition of DNA polymerase activity is much less marked [75]. The potent activity of Et s was attributed, at least in part, to the unit C since the related saframycin A lacks this unit and has lower efficacy than Et 729 in comparable tumor models [74, 75]. More recent structural information on Et 743-DNA adduct was obtained by NMR spectroscopy [78]. An enantioselective total synthesis of Et 743 has been achieved by Corey et al. [79]. 

Jasmonic acid-induced tuberization appears to be due to its being capable of inducing expansion of potato cells rather than the division of cells in vitro. The expansion-inducing activity seems to be specific to jasmonic acid and related compounds since none of the other plant hormones tested have appreciable activity [57]. Further studies [58] showed that jasmonic acid can increase the levels of sucrose and cell wall polysaccharides in potato cells in vitro. The cellulose synthesis inhibitor 2,6-dichlorobenzonitrile inhibited the jasmonic-acid-induced expansion of potato cells. These results support the finding that cell wall polysaccharide and the accumulation of sucrose are involved in jasmonic-acid-induced expansion of cells. Disorganizers of microtubules such as colchicine and isopropyl N-phenyl-carbamate and inhibitors of microfilaments, such as cytochalasin, strongly inhibited the jasmonic-acid-induced expansion of potato cells, suggesting the involvement of a cytoskeletal structure in the expansion of cells by this compound. 

Baskin T.I., Beemster G.T.S., Judy-March J.E., and Marga F. 2004. Disorganization of cortical microtubules stimulates tangential expansion and reduces the uniformity of cellulose microfibril alignment among cells in the root of Arabidopsis. Plant Physiol 135 2279-2290. 

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