Mutations causing defects in pattern formation in Drosophila

Mutations causing defects in pattern formation in Drosophila. A fifth class of mutations, homeotic gene mutations.Mutations causing defects in pattern formation in Drosophila. A fifth class of mutations, homeotic gene mutations.

(3) Coordinate gene (b) Gap gene (c) Pair-rule gene (d) Segment polarity gene Highest concentration of bicoid knirps hunchback odd-skipped Expression patterns Anterior Posterior even-skipped Wingless engrailed . . Defines broad region Defines segments Defines axrs of embryo of the embryo of the embryo Mutations Mutation results in the loss of Mutation results in the loss of Mutation results in the loss of Mutation results in defects in pattern segments and mirror-image contiguous sets of segments alternate parasegments within anterior or posterior formation duplications of other (9 genes). (8 genes). regions of each segment segments. (>15 genes). Wild type (side view) Wild type (do rsal view) Wild type Wild type ,---—n~~~-_~,) -I—l-i 4>>>>>>>> —l -+ > > > dNUJ d N W & U1 0‘ \lm -i W b 0‘ oo /' A1 A3 A5 A7 @giiifligs’ks is“; “"3“ " , .. .. - fig: 21 )1 * fillililg Mutant . - 7": ~ , a; phenotypes .z . y t 9 , . , \ Ktfing/qm gill i if: is ”(3 {K}; ‘ ooseberr o blCOid o even-skipped o g y 55%? _, ”I” ehedgehog T = thoracic segment A = abdominal segment e odd-skipped