Haltere determination and mutations at the bithorax locus

Mutations at the bithorax locus transform anterior haltere tissue into anterior wing. These transformations could in principle be due to the mutations altering either the expression or cell heredity functions of determination. I have studied two alleles of the bithorax locus bx³ and bx^34e using disc culture techniques and found that both produce their transformations by altering the expression of the determined state. I have also found that the expression of the temperature-sensitive allele, bx^34e, can be altered by temperature shifts during the culture period. Evidence has been obtained that suggests that such changes in expression do not require growth or cell division.