Ação do paradiclorobenzeno sôbre os cromossômios somáticos

Cândida H. T. Mendes Conagin About the author

The effects of a prefixation treatment with paradichlorobenzene on the somatic chromosomes of Coffea arabica, Allium cepa, Arachis prostrata and Aloë sp. have been studied. The following schedule was followed for treating root tips : a) prefixation in a solution of paradichlorobenzene ; b) fixation in Carnoy ; c) hydrolisis in 10 per cent HCI for two minutes at 60°C ; d) washing in distilled water ; e) washing in 45 per cent acetic acid ; f) smearing and staining in aceto-orcein. Good smears were obtained with root tips of Coffea arabica, Allium cepa and Aloe sp. The chromosomes of Coffea arabica were well scattered in the cells. The long chromosomes of Allium cepa and Aloe sp. were also well separated from each other. No difference in the chromosomes was noticed in smears made from paradichlorobenzene treated and untreated root tips of Arachis prostrata. This technique can substitute the paraffin method to advantage for counting chromosome number in root tip cells of the above mentioned species.

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