Practice question

Dorsal protein, NF-kappa B homolog, provides ventralizing morphogen; its absence eliminates ventral and lateral fates causing entire embryo to adopt dorsal ectoderm identity characterized by amnioserosa and dorsal hairs circumferentially. Embryos lacking dorsal fail to form ventral furrow, mesoderm, or neuroectoderm, cuticle shows dorsalized phenotype with fine hairs everywhere, lethal before hatching. Ventralized phenotype arises from opposite genotype such as cactus loss or Toll gain. Anteriorized or posteriorized phenotypes involve bicoid or torso pathways. Dorsal loss therefore demonstrates necessity of NF-kappa B-like gradient for DV patterning, innate immunity cross-regulation, providing model linking developmental polarity and inflammatory signaling pathway conservation.