Break lies in the iab-4 transcription unit.
Mutation maps outside the 5' end of the transcription unit.
Lesion mapped to: 83-86.5 kb.
Germ cells are present in homozygous embryos. Some gonadal cells are present in 56% of female homozygous embryos. Gonadal cells are always associated with a cluster of germ cells in these embryos.
Gonadal precursors do not coalesce into a gonad. Pole cells are released from the stalled gonadal precursors and are scattered throughout the embryo.
Defective in gonad assembly.
Gonadogenesis is not initiated in the embryo because the mesodermal cells fail to encapsulate the pole cells in a mesodermal gonadal sheath. Formation and/or the development of male and female gonads is affected. Pole cell transplantation shows that ovary and testis formation does not require abd-A in the germ cells. Somatic chimeras demonstrated that abd-A is required in somatic cells to produce competent gonad-duct connections and in somatic cells at another site to form functional ovaries.
Hemizygotes display a transformation of segment A4 into A3 and A2 into A3.
Partial transformation of the fifth and second adult abdominal segment to the fourth or third.
R.H. Baker.
R. Baker.
Induced with: abd-Aiab4-302.
Mutations in iab-4 have effects on the abd-A transcription unit, so such mutations are considered to be simultaneously mutant for iab-4 and abd-A.