Practice question

Syncytial specification operates within shared cytoplasm before plasma membranes partition nuclei, allowing transcription factors to diffuse freely and act on all nuclei simultaneously. In Drosophila, maternal gradients of Bicoid anterior and Nanos posterior traverse syncytium without needing transmembrane receptors, directly entering nuclei to regulate gap genes according to concentration thresholds via differential enhancer affinity. Gap proteins then initiate pair-rule stripes through cooperative interactions. Cell-cell contact becomes relevant only after cellularization around cycle fourteen, after which conditional interactions dominate. Early diffusion mechanism accelerates patterning in rapidly developing insect embryos with short life cycles.