1DEVELOPMENTThe egg/cell provides the molecular and architecturalcontext for developmentIMPORTANT ISSUES1. The egg has information pre-stored in it. How do weidentify the genes encoding this information? 2. Not all genes are expressed in each cell/tissue. How do we determine whether a gene is required for a particular developmental event?The Drosophila egg has maternal gene products localized2The Drosophila egg has maternal gene products localizedMATERNAL EFFECT MUTATIONS IDENTIFY DEVELOPMENTALGENES WHOSE PRODUCTS ARE PRE-LOCATED IN THE EGG+ / lethal+ / lethalX3 viable : 1 deadZYGOTIC LETHALMATERNAL EFFECT LETHAL+ / lethal+ / lethalXALL VIABLElethal / lethal+ / +XALL LETHALMATERNAL EFFECT LETHAL+ / lethal + / lethalXALL VIABLElethal / lethal+ / +XALL LETHAL+ / + + / lethal lethal / lethal(Can the mother produce normal eggs)and3HOW CAN WE DETERMINE WHETHER A GENE’S FUNCTIONIS AUTONOMOUS OR NON-AUTONOMOUS?A CELL OR TISSUE MAY RECEIVE INFORMATION:1. FROM THE CELL ITSELF-AUTONOMOUS2. FROM ITS NEIGHBORS-NON-AUTONOMOUS4HOW CAN WE TELL IF A GENE FUNCTION IS REQUIREDIN A SPECIFIC TISSUE?ANSWER:GENERATE MUTANT CLONES WITHIN THE TISSUESn+ysnY+XSn+ySn+ ysnsnY +Sn+ysnY+Sn+ysnSn+ysn Y+Sn+ysn Y+Sn+ysnY+Sn+ysnY+MITOTIC RECOMBINATIONY +Y+Sn+ysnY+Sn+ysnSn+ysn Y+Sn+ysn Y+SINGEDY+Sn+ySn+ysnsnY+Y+YELLOWsnY+Sn+ySn+ysn Y+WILD TYPEWILD TYPE5HOW CAN WE TELL IF A GENE PRODUCT ISREQUIRED IN A PARTICULAR TISSUE?METHOD: USE THE CRE/LOX SYSTEM TO ELIMINATE THE GENE ONLY IN THAT TISSUE.CRE IS A RECOMBINASE CAUSING RECOMBINATIONONLY BETWEEN TANDEMLY REPEATED LOX SITESHOW CAN WE DELETE A GENE IN A PARTICULAR TISSUE?METHOD: PLACE CRE UNDER A TISSUE SPECIFICPROMOTER AND THE GENE IN QUESTIONFLANKED BY TANDEM LOX SITES6A CELL TYPE SPECIFIC PROMOTER DRIVES CRE
View Full Document