ON THE MOLECULAR TAXONOMY OF TRYPANOSOMA-CRUZI USING RIBOPRINTING

In order to investigate the molecular taxonomy within Trypanosoma cruz i, the ribosomal small subunit (18S) gene was amplified by polymerase chain reaction (PCR) from a selection of 21 stocks and 3 outgroup taxa . Amplification products were digested with 10 restriction enzymes; re striction fragments were separated by polyacrylamide gel electrophores is and profiles were visualized by silver staining. Upon analysis of s uch riboprint profiles, an estimate of pairwise phenetic distance betw een stocks of T. cruzi was calculated. Upon principal coordinate analy sis of this data matrix, a tendency towards a bi-polar grouping of sto cks was observed. These 2 groups were predominantly either zymodeme 1 stocks or zymodeme 2 stocks. The position of zymodeme 3 stocks remaine d intermediate between the 2 groups but did not form a coherent group by themselves. It would therefore appear premature to warrant division of T. cruzi into 2 discrete taxa or subspecies until the relationship s of further zymodeme 3 stocks are elucidated.