LOCALIZATION OF SWINE PRE-1 HOMOLOGS IN 13 LOCI OF PHACOCHOERUS-AETHIOPICUS AND TAYASSU-TAJACU GENOMES, AND THEIR SEQUENCE DIVERGENCE

In our previous study, PRE-1 (a swine short interspersed nuclear eleme nt, SINE) was found to be present in the genomes of animal species rel ated to swine (Sus scrofa) i.e. warthog (Phacochoerus aethiopicus) and collared peccary (Tayassu tajacu) at almost the same frequency as in Sus scrofa. In the present study, we investigated whether PRE-1 was pr esent in hippopotamus (Hippopotamus amphibius), which is in the same o rder but in a different family to Sus scrofa. Hippopotamus amphibius w as found to contain no PRE-1. Then, in order to study the localization of PRE-1 sequences at locus level and the sequence divergence of the PRE-1 of individual loci among Sus scrofa, Phacochoerus aethiopicus an d Tayassu tajacu, primer sets, which can amplify PRE-1 sequences at 13 loci of swine genome with the polymerase chain reaction, were prepare d to identify any corresponding sequences in Phacochoerus aethiopicus and Tayassu tajacu. Twelve and nine of the 13 primer sets identified f ragments in Phacochoerus aethiopicus and Tayassu tajacu respectively. Ten of the 12 Phacochoerus aethiopicus fragments and two of the nine T ayassu tajacu fragments contained PRE-1 sequences. Based on the diverg ence between the corresponding PRE-1 sequences at individual loci and on the mutation rate of the pseudogenes (r=4.6x10(-9)), Phacochoerus a ethiopicus and Tayassu tajacu are currently calculated to have been se parated from Sus scrofa later than 1.4 million years before present (M YBP) and 16.8 MYBP, respectively.