CONSERVED SEQUENCE AND FUNCTIONAL DOMAINS IN SATELLITE-2 FROM 3 FAMILIES OF SALAMANDERS

Thirteen satellite 2 elements from Ambystoma talpoideum and 16 from Am phiuma tridactylum were cloned, sequenced, and compared with the satel lite 2 consensus from Notophthalmus viridescens. These elements have m aintained a high degree of similarity during the 65-200 Myr that the s alamander families, represented by the three species, have been separa ted. The DNA sequences of the consensus elements from A. talpoideum an d A. tridactylum are 81% similar, and both are approximately 65% simil ar to the N. viridescens consensus. In addition to its DNA sequence, t he functional properties of satellite 2 have also been conserved. By s electing and analyzing clones that closely mimicked the consensus of e ach species, we were able to demonstrate that satellite 2 from each sp ecies was capable of promoting transcription after injection into Xeno pus laevis oocytes and that synthetic transcripts of satellite 2 from each species were capable of catalyzing their own site-specific cleava ge. These properties may be related to the process of retroposition, w hich was previously proposed to be responsible for the genomic prolife ration of satellite 2. Each of these functional properties also has ge neral biological interest.