Kumar M, Lakhotia S C
Chromosoma. 1977 Feb 23;59(4):301-5. doi: 10.1007/BF00327971.
A simple fluorescence technique is decribed to localise in situ the non-replicating alpha heterochromatin in the chromocentre region of Drosophila nasuta polytene nuclei. After incorporating 5-bromodeoxyuridine in larval salivary gland cells for one or two cycles of replication, the polytene nuclei are examined for Hoechst 33258 flourescence at pH 7.0. The non-replicating alpha heterochromatin remains brightly fluorescing as it does not incorporate any 5-bromodeoxyuridine while the rest of the replicating chromatin shows dull fluorescence due to the quenching of Hoechst 33258 fluorescence by the bromodeoxyuridine substituted DNA.
