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E. hecabe Ostrinia

Figure 13.14 Hypothetical molecular mechanisms for sex determination in E. hecabe and Ostrinia. (a): In uninfected matrilines, morphological sexual dimorphism is generated by proper expression of sex-determining and sex-differentiation genes according to their genetic sexes (b): In feminized matrilines, the expression of one of the sex-determining or sex-differentiation genes is switched from the male-type to the female-type at a particular point In the downstream of this point, the gene expressions are consistently of the female type Consequently, phenotypically female adults are generated under the male genotype in E. hecabe, whereas genetic males die during larval development in Ostrinia (c): Intersexual individuals generated in E. hecabe and Ostrinia are purely genetic males, but are comprised of mosaics of phenotypically female and male tissues complex: DCC), which is necessary for dosage compensation, was found to be required for the expression of Spiroplasma-induced male killing (Veneti et al ., 2005) .

The death of Ostrinia genetic males is considered to be due to their intolerance of the feminizing effect of Wolbachia (Kageyama and Traut, 2004). This may imply that genetic males (ZZ individuals) cannot survive as phenotypic females due to the adverse effects of the excessive expression of Z-linked genes Therefore, why do feminized genetic males of E. hecabe survive and function normally? To answer or validate this question, we need to examine the Z-linked gene expression levels among normal females, normal males, and feminized individuals of E. hecabe and Ostrinia.

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