▁at ▁U tre cht ▁University ▁in ▁September ▁ 1 9 5 3 . ▁He ▁did ▁his ▁first ▁DNA - res earch ▁under ▁professor ▁W ink ler . ▁In ▁ 1 9 6 5 ▁he ▁obtained ▁his ▁Ph D ▁from ▁Le iden ▁University . ▁In ▁the ▁late ▁ 1 9 6 0 s ▁Bo ots ma ▁performed ▁his ▁comp uls ory ▁military ▁service ▁at ▁the ▁Medical - Bi ological ▁Labor atory ▁of ▁the ▁Netherlands ▁Organisation ▁for ▁App lied ▁Scient ific ▁Research ▁( T NO ). ▁There , ▁he ▁research ed ▁the ▁influence ▁of ▁X - rad iation ▁on ▁chrom os om es ▁in ▁living ▁cells . ▁ ▁After ▁obtain ing ▁his ▁Ph D , ▁Bo ots ma ▁joined ▁the ▁newly ▁found ▁department ▁of ▁cell ▁bi ology ▁and ▁gen et ics ▁at ▁the ▁Er as mus ▁University ▁Rot ter dam . ▁In ▁ 1 9 6 9 , ▁he ▁became ▁a ▁professor ▁of ▁gen et ics . ▁After ▁recom bin ant ▁DNA ▁became ▁available , ▁Bo ots ma ▁and ▁his ▁department ▁made ▁use ▁of ▁this ▁technology . ▁In ▁ 1 9 7 4 ▁he ▁organized ▁the ▁second ▁Human ▁Gene ▁M apping ▁Conference ▁in ▁No ord wij ker h out . ▁Bo ots ma ▁later ▁lost ▁his ▁interest ▁in ▁gene ▁mapping . ▁He ▁then ▁turned ▁to ▁cancer ▁research , ▁re lying ▁on ▁his ▁earlier ▁experiences ▁at ▁T NO . ▁He ▁focused ▁on ▁mechan isms ▁that ▁rep a ired ▁DNA , ▁especially ▁in ▁rare ▁forms ▁of ▁skin ▁cancer , ▁and ▁discovered ▁several ▁prote ins ▁in ▁this ▁field