al ▁particles . ▁ ▁History ▁P 1 ▁was ▁discovered ▁in ▁ 1 9 5 1 ▁by ▁Giuseppe ▁Bert ani ▁in ▁Salvador ▁L uria ' s ▁labor atory , ▁but ▁the ▁ph age ▁was ▁little ▁studied ▁until ▁Ed ▁Len no x , ▁also ▁in ▁L uria ' s ▁group , ▁showed ▁in ▁ 1 9 5 4 – 5 ▁that ▁it ▁could ▁trans du ce ▁gen etic ▁material ▁between ▁host ▁b acter ia . ▁This ▁discovery ▁led ▁to ▁the ▁ph age ▁being ▁used ▁for ▁gen etic ▁exchange ▁and ▁gen ome ▁mapping ▁in ▁E . ▁col i , ▁and ▁stim ulated ▁its ▁further ▁study ▁as ▁a ▁model ▁organ ism . ▁In ▁the ▁ 1 9 6 0 s , ▁H ideo ▁I k eda ▁and ▁Jun - ichi ▁Tom iz awa ▁showed ▁the ▁ph age ' s ▁DNA ▁gen ome ▁to ▁be ▁linear ▁and ▁double - str and ed , ▁with ▁redund ancy ▁at ▁the ▁ends . ▁In ▁the ▁ 1 9 7 0 s , ▁Nat ▁Stern berg ▁character ised ▁the ▁Cre – lo x ▁site - specific ▁recom bin ation ▁system , ▁which ▁allows ▁the ▁linear ▁gen ome ▁to ▁circular ise ▁to ▁form ▁a ▁pl as mid ▁after ▁in fection . ▁During ▁the ▁ 1 9 8 0 s , ▁Stern berg ▁developed ▁P 1 ▁as ▁a ▁vector ▁for ▁cl oning ▁large ▁pieces ▁of ▁e uk ary otic ▁DNA . ▁A ▁P 1 ▁gene ▁map ▁based ▁on ▁a ▁partial ▁DNA ▁sequence ▁was ▁published ▁in ▁ 1 9 9 3 ▁by ▁Michael ▁Y arm