Ricerche sulla fisiologia della mitosi. Azione del malonato e dello iodoace-tato sulla crescita per divisione e per distensione delle cellule delle radici di plantule di frumento (Triticum sativum)

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Abstract
RESEARCHES ON THE PHYSIOLOGY OF MITOSIS: ACTION OF MALONATE AND IODACETATE ON DIVISION AND DISTENSION GROWRH OF CELLS OF WHEAT SEEDLINGS ROOTS. — The effect of malonate and iodacetate was studied on cell distension and on the mitosis of etiolated, intact or deprived of caryopsis wheat seedlings. At the same time the variation in the exigen uptake of such plants or root segments placed in the above inhibitors was studied by the Warburg apparatus. The oxigen uptake indicated that the response of the roots to the two inhibitors used is greatest in the first hours and then decreases more or less rapidly. An early almost total and irreversible inhibition of cell distension corresponds to the early decrease in the oxigen uptake. Such inhibition seems to be due to a comtemporaneous decrease of the energy available in the cell. It is at least peculiar that such temporary reduction in the available energy causes a permanent change in the growth capability of the cells. As regards the action of the inhibitors on cell division and on the mitosis behaviour, the greatest concentrations cause a more or less severe and extended blocking of the mitosis, without any remarkable interference on the regular development of the already started mitosis. Then malonate and iodacetate seem to act as preprophasic inhibitors. The experiments with etiolated and deprived of caryopsis seedlings, placed in thermostat at various temperatures or in the two respiratory inhibitors seem to indicate that mitosis stops in the meristematic apex as soon as the energy available in the cells becomes too scanty, that is under a « threshold value ». A comparison of the effect of the two inhibitors indicated that, although the effect is like under certain aspects, it shows a remarkable difference for others. In fact, only in the roots placed in iodacetate there is in the meristematic cells a more or less evident unmixing of chromatin, a more precocious differentiation of the cells near the apex and the presence of aberrant root hair, sometimes branched and even pluricellular.