The pyrithiamine or pPTR vectors are E. coli-Aspergillus shuttle vectors andcontain an ampicillin resistance gene (Amp^R) as the selection marker for E. coli and a pyrithiamine-resistance gene (ptrA) as the selection marker for Aspergillus. Pyrithiamine isa pyridine analog and inhibitor of thiamine. Because the pPTR vector multiple cloning site (MCS) islocated within the lacZ region, the presence or absence of target DNA insert can easily beverifiedusing blue/white screeningviabacterial plates containing IPTG and X-Gal.