Poly (A) § RNA from the D. melanogaster culture ceils labeled with [~ 2p] orthophosphate for
15 hr was obtained as described by Tchurikov et al.(1978). For hybridization of mdg-1, only
the heavy fraction (> 20S) was used. The Southern filters contained the following, mdg-
1:(ad) p58 DNA;(e) EcoRI fragment B; 00 EcoRI fragment C. mdg-3:(gm) p38 DNA. In c,
fragment D is located above A since it is linked to a pBR322 DNA.