Deletion of genomic sequences 2192-2210, only the first 406 amino acids are present followed by 3 new amino acids.
Mutation in the putative regulatory domain. Class II fu allele, affects the carboxy domain of the protein by changing the open reading frame in the 5' region.
in fu50/fu50, fu50/fu52 or fu50/Df(1)fu-Z4 females at 4 or 10 days old, over 70% of egg chambers are tumorous. Tumorous egg chambers consist of tens to hundreds of germ-line cells with small non-polyploid nuclei enveloped by a regular follicular epithelium. Marker expression studies and analysis of spectrosome morphology in tumorous cysts from fu50/Df(1)fu-Z4 and fu50/fu52 animals suggest that these tumorous germ-line cells remain very immature and do not progress beyond the early cystoblast stage and perhaps include germline stem cells (GSCs). Tumorous egg chambers develop from germaria where encapsulation of germ-line cysts fails in region 3. These germaria are mis-shapen and swollen and accumulate germline stem cells or cystolasts (as judged by the presence of an unbranched spectrosome and by marker expression) throughout the germarium. Germaria from fu50/fu50 adult females exhibiting relatively normal encapsulation germline cysts in region 3 (and so not producing tumorous follicles), have an excess of germline stem cells or cystoblasts in region 1. In both cases, marker analysis indicates that the size of germline stem cell niches appears to be unnaffected - suggesting that these phenotypes are due to inceases in GSC or cystoblast-like cells outside of the niche. This increase is not due to increased cell division of germline stem cells in the niche - as assayed by scoring the percentage of GSCs in the niche undergoing mitosis in fu50/fu50 fu52/fu50 and fu50/Df(1)fu-Z4 adult females.
Relatively large somatic clones that include the anterior region of the follicular epithelium of an egg chamber are associated with the production of egg chambers with abnormal numbers of germline cells. Mosaic ovarioles containing homozygous follicle cell clones sometimes show mislocalisation of the oocyte. In these egg chambers the mislocalised oocytes orient themselves towards fu+ cells, independently of where the fu+ cells are localised.
strong wing phenotype - veins L3 and L4 fused all along length; weak viability phenotype - ratio of the number of fused flies to wild type in fu/+ X fu/Y is 0.75-1.0; strong fecundity phenotype - ratio of eggs laid by fu/fu versus fu/+ sisters is 0-0.1; strong maternal effect on segmentation - percent of embryos with all segments entirely duplicated is 70-100%.
Su(fu)LP, fu50 has wing blade anterior compartment phenotype
Su(fu)LP, fu50 has leg anterior compartment phenotype
Su(fu)LP, fu50 has haltere anterior compartment phenotype
When in combination with Su(fu)LP heterozygotes individuals die as pupae. Adult escapers display wings, halteres and legs that have duplication of structures in the anterior compartment and shortening along the proximal-distal axis. Embryos derived from heterozygotes with Su(fu) mutants display a segment polarity phenotype: thoracic denticle belts are absent, last two rows of abdominal denticle belts are absent and a mirror image duplication of anterior rows of abdominal denticle belts.
Class II mutation based on interaction with Su(fu)LP, suppression of embryonic and adult phenotype but display an additional phenotype.