TOWARDS THE PHYSICAL MAP OF THE TRYPANOSOMA-CRUZI NUCLEAR GENOME - CONSTRUCTION OF YAC AND BAC LIBRARIES OF THE REFERENCE CLONE TRYPANOSOMA-CRUZI CL-BRENER

Strategies to construct the physical map of the Trypanosoma cruzi nucl ear genome have tn capitalize on three main advantages of the parasite genome, namely (a) its small size, (b) the fact that all chromosomes can be defined and many of them can be isolated by pulse field gel ele ctrophoresis, and (c) the fact that simple Southern blots of electroph oretic karyotypes can be used to map sequence tagged sites and express ed sequence tags to chromosomal bands. A major drawback to cope with i s the complexity of T. cruzi genetics, that hinders the construction o f a comprehensive genetic map. As a first step towards physical mappin g, we report the construction and partial characterization of a T. cru zi CL-Brener genomic library in yeast artificial chromosomes (YACs) th at consists of 2,770 individual YACs with a mean insert size of 365 kb encompassing around 10 genomic equivalents. Two libraries ill bacteri al artificial chromosomes (BACs) have been constructed BACI and BACII. Both libraries represent about three genome equivalents. A third BAC library (BAC III) is being constructed. YACs and BACs are invaluable t ools for physical mapping. More generally, they have to be considered as a common resource for research in Chagas disease.