Krebs and Stuart A. To test our hypothesis we transiently expressed the fem gene in males by injecting fem encoding mRNAs that we synthesized in vitro. No sex-transformed effects occurred in fem -repressed males.
The testes of fem -repressed females were smaller and contained fewer and shorter testioles in all cases, irrespective of whether we compared larvae of the same given the sex determination system in bees in Brampton or the same stage with the controls, suggesting that this difference is not just a slowdown of development caused by the effect of RNAi.
In addition, the individual in Figure 3P lacks the female-specific lobe on the first tarsus but displays the pollen comb on the tibia. The identity of the female fragments was confirmed by nucleotide sequence analysis.
The male bees' genetic makeup is therefore entirely derived from the mother, while the genetic makeup of the female worker bees is half derived from the mother, and half from the father.
Sex determination and dosage compensation in Drosophila melanogaster : production of male given the sex determination system in bees in Brampton in XX females. However, hundreds of thousands of insects, such as ants, wasps and bees, have a fundamentally different sex determination system called haplodiploidy.
Individuals that were derived from inbred crosses were sexed according to the genotype at the csd locus . The exclusion of other sex-determining factors at SDL suggests that complementary sex determination entirely relies on heterozygous combination of the csd gene.
The fragments obtained from untreated females and males are shown in the 1 st and 2 nd lane, respectively. From the presence of male mRNAs under conditions of resumed fem mRNA production, we conclude that the csd gene has lost its ability to direct the processing of fem into the female mode.
A similar mechanism has been proposed for the medfly Ceratitis capitata at the level of the sex-determining tra Cc-tra gene  ,  , a gene which has a common ancestry with the fem gene . We propose that the positive feedback loop would 1 generate stably determined states implemented by the commitment given by the primary signal csd and 2 maintain the determined state throughout development.