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D MAZIA

Publications and source records attributed to D MAZIA.

At least 19 recordsLinked to original sources
PubMed1961

How cells divide.

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Cell Division↗
PubMed1961

The direct isolation of the mitotic apparatus.

A method for isolating the mitotic apparatus from dividing sea urchin eggs without the use of ethyl alcohol or of detergents is described. In the present method, the eggs are dispersed directly in a medium containing 1 M (to 1.15 M) sucrose, 0.15 M dithiodiglycol, and 0.001 M Versene at pH 6, releasing the visibly intact mitotic apparatus. The method is designed for studies of enzyme activities, lipid components, and the variables affecting the stability of the apparatus.

Animals↗
PubMed1960

Deoxyribonucleic acid synthesis in relation to duplication of centers in dividing eggs of the sea urchin, Strongylocentrotus purpouratus.

The earliest known event in the sequence leading to mitosis is the duplication of cell centers. The present investigation shows that the synthesis of DNA, although closely following it in time, is initiated entirely independently of this prior event. Fertilized eggs of the sea urchin, S. purpuratus, were exposed to beta-mercaptoethanol at intervals during development. This substance, when introduced at appropriate times, blocks mitosis and also prevents duplication of centers. Whether or not duplication of centers had already occurred before introduction of the blocking agent was determined by observing the division patterns of eggs after the mercaptoethanol was removed: division of one cell into two, or of two into four indicated that duplication had not occurred; division of one into four or of two into eight, that it had. Incorporation of H(3)-labeled thymidine into DNA, as demonstrated by autoradiography, showed that DNA synthesis took place during the mercaptoethanol block regardless of whether or not the centers had already duplicated. Thus the two major reproductive events of the mitotic sequence, although normally coordinated in time, can be dissociated experimentally and shown to function independently.

Animals↗
PubMed1956

The distribution of newly synthesized DNA in mitotic division.

The chromosomes of Crepis capillaris were labelled with thymidine-2-C(14) in their DNA fraction. Quantitative analysis of the distribution of newly synthesized DNA in postmetaphase stages of the division following the period of label incorporation led to the conclusion that the new DNA is not necessarily equally distributed by the mitotic process and that, therefore, chromosome duplication does not involve the equal partition of parental DNA. The implications of these findings with respect to DNA duplication are discussed. An attempt is made to translate the pattern of new DNA distribution into a probable number of units of synthesis per chromosome.

Cell Division↗