Homozygotes are viable at 22^oC and lethal at 29^oC. Hemizygous patches of cells show a greater proliferation than heterozygous cells in gynandromorphs at 22^oC. This increased proliferation is eliminated at 29^oC. Mutant germ cells often differentiate into morphologically abnormal oocytes.

Temperature sensitive mutation. Hemizygous males and homozygous females are viable and fertile at 22^oC, but all females and some males become sterile if maintained at 29^oC. RpII215^ts in transheterozygous combination with RpII215^Ubl, RpII215¹⁰, RpII215^NC or RpII215⁷ is lethal, or viability is greatly reduced even at low temperatures. Homozygous or hemizygous embryos maintained at 29^oC die during late embryogenesis or as first instar larvae, and appear superficially normal. Temperature shift experiments show that as the temperature is increased from 22^oC the percentage lethality of homozygous and hemizygous embryos increases and the lethal phase shifts from larval stages towards the embryonic stage. The temperature-sensitive phenotype lasts from the end of gastrulation until the end of the third instar larval stage. Homozygous clones appear to be either cell lethal or have greatly reduced viability even when induced at the pupal stage, indicating that the RpII215⁺ product is required at all stages of development.

Encodes a heat labile RNA polymerase subunit, as measured in vitro (Coulter and Greenleaf, 1982) and by sterilizing effects on females and lethal effects on embryos. Females shifted from 22^oC to 29^oC become sterile, although their eggs laid during the first 24 hr appear normal morphologically; after 24 hr, embryonic development is visibly abnormal. Embryonic abnormalities include holes in the ventral cuticle and abnormal pharyngeal structures. Partial rescue of the sterility can be achieved by shifting newly laid eggs to 22^oC or by fertilization of eggs of RpII215^ts females with wild-type sperm; the degree of rescue decreases as the time that the females have been held at 29^oC increases. Abnormalities of embryos dying despite rescue attempts mimic the phenotypes of pair-rule and segment-polarity mutants; surviving adults resemble Hab in lacking one or both halteres and metathoracic legs. In RpII215^ts/+//RpII215^ts/0 gynandromorphs, the RpII215^ts/0 tissue appears to occupy more territory than expected, as though it had a proliferative advantage over the RpII215^ts/+ tissue (Mortin, Perrimon and Bonner, 1985).

Polr2A^ts has lethal phenotype, non-suppressible by Polr2B^S1

Polr2A^ts has lethal phenotype, non-suppressible by Polr2B^S2

Polr2A^ts has lethal phenotype, non-suppressible by Polr2B^S5

Polr2A^ts has lethal phenotype, non-suppressible by Polr2B^S6

Polr2A^ts has lethal phenotype, non-suppressible by Polr2B^S8

Polr2A^ts has lethal phenotype, non-suppressible by Polr2B^S7

Polr2A^ts has lethal phenotype, non-suppressible by Polr2B^S11

Polr2A^ts has lethal phenotype, non-suppressible by Polr2B^S12