Consists of a deletion that starts 23bp upstream of eyg and extends 11.8kb downstream of the gene. Contains an almost complete P{lacW} element at +72bp relative to the proximal end of the deficiency, in the opposite transcriptional orientation to the original P{lacW} in eygM3-12. At the distal end, there is a 3' end of an incomplete P element in the opposite transcriptional orientation.
eygP20MD1 mutants suffer head loss, making this mutation lethal. eygP20MD1 mutant third-instar larvae completely lack eye discs and have only a rudimentary antennal disc. eygP20MD1/Df(3L)iro-2 hemizygotes also completely lack eye tissue. Clones of eygP20MD1 cells at the dorsal-ventral boundary of late third larval instar eye discs are always smaller than wild-type cells. The presence of eygP20MD1 clones can often lead to an overall reduction in eye size due to the presence of multiple clones in the dorsal-ventral region, nonautonomous outgrowths, or nonautonomous repatterning defects. There is a reduction of cell divisions within eygP20MD1 mutant clones compared to wild-type clones. Eye discs comprised almost entirely of eygP20MD1 mutant clone tissue (induced using the Minute technique) are much smaller than wild-type discs and do not differentiate a retina. Mosaic eye discs with wild-type cells along the dorsal-ventral region have normal eye-growth and differentiation, resulting in adults with eyes of an almost normal size, despite the presence of the eygP20MD1 clones. New boundaries that juxtapose wild-type and eygP20MD1 cells in mosaic eye discs induce a local increase in cell proliferation and pattern duplications in the antennal disc.
