DNA FROM DROSOPHILA-MELANOGASTER BETA-HETEROCHROMATIN BINDS SPECIFICALLY TO NUCLEAR LAMINS IN-VITRO AND THE NUCLEAR-ENVELOPE IN-SITU

A DNA fragment designated lambda 20p1.4 binds in vitro to polymerized Drosophila melanogaster lamin. In situ hybridization of lambda 20p1.4 to isolated polytene chromosomes revealed localization at the chromoce nter and to the 49 CD region on the right arm of chromosome 2. About 1 20 copies of sequences homologous to lambda 20p1.4 were detected per h aploid genome. Nucleotide (nt) sequence analysis demonstrates that lam bda 20p1.4 is an A+T-rich, 1327-bp fragment containing four repeated u nits between nt 595 and 919. Results suggest that lamin interacts with a region of lambda 20p1.4 between nt 300 and 1000. Confocal immunoflu orescence co-localization demonstrates that in situ, the major locus o f lambda 20p1.4 hybridization, the chromocenter, is found juxtaposed t o the nuclear envelope (lamina). This is the first demonstration that a DNA sequence that binds specifically to nuclear lamins in vitro, is located at or near the nuclear envelope in situ and, presumably, in vi vo.