Sex-lethal is a sequence-specific RNA binding protein that recognizes a specific UGUUUUUUU element in its target RNAs. It has a Β1,2,3 & 4 domains as well as RNA recognition motifs RRM1 and RRM2. The presence or absence of Sxl in an early embryo will determine whether it develops as a male or a female. Early [...]

Maternal effect genes are transcribed, and their mRNA translocated into the egg, during oogenesis. Maternal effect genes acts before any zygotic genes, which are encoded by the embryonic genome itself. The maternal phenotype determines the zygotic phenotype. Thus, a MEG+/- female will have all normal children even if the child’s phenotype is MEG-/- (due to [...]

In Drosophila, a hierarchy of maternal gene activitity genes, as well as zygotic activity of gap, pair-rule and segment polarity genes divides the embryo into 14 repeating metameric domains. These metameric segments will become head, thorax or abdomen segments based on activity of Hom-C genes (which include Antennapedia Complex (Antp-C) and Bithorax Complex (Bx-C) genes). [...]