culturing a host transformed by a vector comprising {HEAD ~ a DNA segment} having {TAIL ~ the following nucleotide sequence}: 
having
culturing a host transformed by a vector comprising { HEAD ~ a DNA segment } having { TAIL ~ the following nucleotide sequence } :
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH