Toward a molecular paleontology of primate genomes.  II.  The KpnI families of alphoid DNAs. 
KpnI restriction of anthropoid primate DNAs, from a New World monkey to man, releases a series of segments that are remarkable among all of the alphoid DNAs in the constancy of their relative amounts in the various primate genomes, in their long-range organization, and in their internal sequence structure.  These segments are labeled the KpnI A, B, C and D segments.  Cross-hybridization analysis by Southern filter-transfer hybridization indicates that the KpnI segments represent separate and distinct families of alphoid DNAs.  These families are termed the KpnI A, B, C and D families of alphoid sequences, of which only the KpnI A and B families were studied in detail here. -  Evidence is presented suggesting that the KpnI segments do not exist as long, tandemly repeated sequences in the primate genome: rather, they may occur interspersed among other, perhaps nonalphoid sequences.  From the stained gel patterns and from Southern filter-transfer hybridization experiments, the KpnI families appear to be absent from the genomes of the two prosimians studied - the galago and the black lemur.  The KpnI A and B families are found among all of the anthropoid primates, including the New World capuchin monkey.  The KpnI C family was detected in the genomes of the Old World anthropoid primates whereas the KpnI D family was detected only among the great apes and man. -  The results are in accord with the observation (Musich et al.,  1980) that with the continued evolutionary development of the primate Order, there has been a parallel trend toward an increased number and variety of alphoid DNA sequences.  The properties of the KpnI families suggest that these sequences, unique among the alphoid DNAs, have been conservatively maintained throughout primate phylogeny and that they are among the most ancient of all primate DNAs.