The karyosome is fragmented into two fuzzy spots in mutant embryos, instead of forming a single compact dot as occurs in wild-type nuclei.
Homozygous vls1 embryos derived from homozygous females have no polar granules, fail to form pole cells and have deletions of abdominal structures. vas and CycB transcripts are localized at the posterior.
Eggs derived from homozygous females form a syncytial blastoderm but 80-90% of the embryos fail to cellularise. Those that do cellularise show variable cellularisation defects. The embryos show a "grandchildless-knirps" phenotype; they lack polar granules and pole cells and show typical maternal kni-like abdominal segment deletions.
maternal-effect lethal Embryos from homozygous mothers exhibit a so-called "grandchildless-knirps" phenotype: all eggs lack polar granules and no pole cells are formed; most of the embryos show variable deletions of abdominal segments; whereby segment A4 is deleted most frequently, larger deletions may remove segments A2 through A7; in extreme cases anterior parts of segment A1 become fused to posterior parts of segment A8, but telson elements are always present and relatively normal. In addition, 80-90% of the embryos fail to cellularize normally at the blastoderm stage and die without forming cuticle, or only fragmented pieces of cuticle. Analysis of germ-line clones indicates that the mutation is germ-line autonomous (Schupbach and Wieschaus, 1986).