Amino acid replacement: G113R.
G14328668A
G113R | spn-B-PA
site of nucleic acid difference inferred by FlyBase curator based on reported amino acid change
spn-B1 mutants have a similar frequency of single-strand annealing repair (SSA) compared to controls in a P{wIw.FRT} hemizygous assay to study DNA double-stranded break repair when assayed at 38oC.
Mutants are weakly sensitive to X ray irradiation when irradiated at either 24-48 or 48-72 hours after egg laying (AEL). Little difference in viability is seen in irradiated at 0-24 hours AEL.
In contrast to wild-type ovaries, where the synaptonemal complex (SC) is always restricted to the oocyte by region 2b, spn-B1 mutant females show a significant delay in the process, with cysts with more than 1 cell in synapsis in region 3 of the germarium.
Hemizygotes are viable. Eggs derived from fs(1)K10unspecified; spn-B2/spn-B1 females show a broad spectrum of phenotypes ranging from completely dorsalised to completely ventralised. spn-B1/spn-B2 larvae show normal sensitivity to methyl methanesulfonate.
Hemizygous eggs exhibit either a strong or weak ventralised phenotype: eggs are longer than wild type and are completely symmetric along the DV axis or the eggs display fused dorsal appendages. Egg chambers of females exhibit a partially penetrant disruption in the positioning of the oocyte which can be located anywhere in the egg chamber. Almost all oocytes lack a karyosome and the oocyte chromosomes are arranged instead in thread-like figures with irregular shape. Germline clones in egg chambers are composed of wild type follicle cells, mutant nurse cells, oocytes that give rise to ventralised eggs and oocytes that lack a karyosome.
maternal-effect lethal. Similar to spn-A but normal eggs also recovered; eggs always unfertilized and abnormal eggs often long.
spn-B1 has radiation sensitive phenotype, non-enhanceable by spn-A093A
spn-B1 has radiation sensitive phenotype, non-suppressible by spn-A093A
spn-B1 is a non-enhancer of radiation sensitive phenotype of spn-A093A
spn-B1 is a non-suppressor of radiation sensitive phenotype of spn-A093A
Has no effect on the frequency of X-Y chromosome nondisjunction seen in Df(1)X-1-53B males.
Double mutants with spn-D2 increases the oocyte mispositioning frequency. Double mutant stage 5-6 egg chambers with mus301094 exhibit a two-oocyte phenotype: the second pro-oocyte develops as an oocyte rather than a nurse cell. The double mutants delay but do not block the decision between the two pro-oocytes as one of the two cells always becomes a nurse cell eventually. Double mutant mothers with fs(1)K101 lay dorsalised eggs, the dorsal appendages form a collar around the entire circumference of the egg. This phenotype is indistinguishable from that of fs(1)K101 single mutants.
