▁is ▁possible ▁to ▁assume ▁that ▁ex ogen ous ▁dam aging ▁agents ▁( ion izing ▁radiation ▁and ▁chemical ▁gen ot ox ic ▁agents ) ▁increase ▁the ▁rate ▁of ▁m t D NA ▁escape ▁into ▁the ▁cy top las m . ▁ ▁Th ors ness ▁and ▁Fox ▁continued ▁their ▁research ▁to ▁find ▁the ▁end ogen ous ▁factors ▁affect ing ▁m t D NA ▁escape ▁into ▁the ▁nucle us . ▁They ▁isolated ▁and ▁studied ▁ 2 1 ▁nuclear ▁mut ants ▁with ▁different ▁combinations ▁of ▁mut ations ▁in ▁at ▁least ▁ 1 2 ▁nuclear ▁lo ci ▁called ▁the ▁y me ▁( ye ast ▁mit och ond rial ▁escape ) ▁mut ations , ▁in ▁different ▁environmental ▁conditions ▁since ▁some ▁of ▁these ▁mut ations ▁cause ▁temperature ▁sens itivity . ▁They ▁found ▁out ▁these ▁mut ations ▁which ▁perturb ▁mit och ond rial ▁functions , ▁due ▁to ▁the ▁alter ation ▁of ▁gene ▁products , ▁affect ▁mit och ond rial ▁integrity ▁and ▁led ▁to ▁m t D NA ▁escape ▁to ▁the ▁cy top las m . ▁Additionally , ▁defect s ▁in ▁the ▁prote ins ▁change ▁the ▁rate ▁of ▁m t D NA ▁transfer ▁into ▁the ▁nucle us . ▁For ▁instance , ▁in ▁the ▁case ▁of ▁y me 1 ▁mut ant , ▁ab normal ▁mit och ond ria ▁are ▁target ed ▁for ▁de grad ation ▁by ▁the ▁vac u ole , ▁with ▁the ▁help ▁of ▁p ep 4 ▁, ▁a ▁major ▁protein ase , ▁and ▁de grad ation ▁increases ▁m t D NA ▁escape ▁to ▁the ▁nucle us ▁through ▁the ▁process ▁of ▁mit