▁method ▁for ▁single - cell ▁CR IS PR ▁screen ing ▁was ▁presented ▁in ▁a ▁pre print ▁on ▁bio R xiv ▁and ▁later ▁published ▁in ▁the ▁Nature ▁Method s ▁journal . ▁While ▁each ▁paper ▁shared ▁the ▁core ▁principles ▁of ▁combining ▁CR IS PR ▁medi ated ▁perturb ation ▁with ▁sc R NA - seq , ▁their ▁experimental , ▁techn ological ▁and ▁analyt ical ▁approaches ▁differ ed ▁in ▁several ▁aspects , ▁to ▁explore ▁distinct ▁bi ological ▁questions , ▁demonstr ating ▁the ▁broad ▁utility ▁of ▁this ▁method ology . ▁For ▁example , ▁the ▁CR IS PR - seq ▁paper ▁demonstrated ▁the ▁feas ibility ▁of ▁in ▁v ivo ▁studies ▁using ▁this ▁technology , ▁and ▁the ▁C ROP - seq ▁protocol ▁facil it ates ▁large ▁screens ▁by ▁providing ▁a ▁vector ▁that ▁makes ▁the ▁guide ▁R NA ▁itself ▁readable ▁( r ather ▁than ▁re lying ▁on ▁expressed ▁bar codes ), ▁which ▁allows ▁for ▁single - step ▁guide ▁R NA ▁cl oning . ▁ ▁Ex perimental ▁workflow ▁ ▁CR IS PR ▁Single ▁Guide ▁R NA ▁Library ▁design ▁and ▁selection ▁▁ ▁P oo led ▁CR IS PR ▁libraries ▁that ▁enable ▁gene ▁in activ ation ▁can ▁come ▁in ▁the ▁form ▁of ▁either ▁knock out ▁or ▁inter ference . ▁Kno ck out ▁libraries ▁perturb ▁gen es ▁through ▁double ▁str and ed ▁breaks ▁that ▁prompt ▁the ▁error ▁pr one ▁non - hom olog ous ▁end ▁joining ▁repair ▁path way ▁to ▁introduce ▁dis rupt ive ▁insert ions ▁or ▁delet ions . ▁CR IS PR ▁inter ference ▁( CR IS PR i ) ▁on ▁the ▁other ▁hand