G. Primpke et al., Absence of complementation in non-allelic mutants of Dictyostelium discoideum with defects in the transition from growth to development, MOL GENET G, 266(3), 2001, pp. 396-405
In Dictyostelium discoideum, growth and development are mutually exclusive
and the transition between the two phases of the life cycle is regulated by
the environment. This regulation is disturbed in HBW3, a chemically induce
d mutant with an unknown molecular defect. The mutant develops rapidly and
expresses developmental markers during growth. Here we show that HBW3 fails
to complement another mutant which has a similar phenotype: a targeted kno
ck-out of the gdt1 gene. We further show that both mutations are recessive
and that both are located on chromosome III, suggesting that the two mutati
ons might be allelic. Molecular analysis, however, demonstrates that the gd
t1 gene is not mutated in HBW3. Thus, although a wild-type copy of each gen
e is present in diploid cell lines, the defects due to the recessive mutati
ons synergize to produce a detectable phenotype. The phenotypic similaritie
s and differences between the two mutants are discussed.