Disease relevance of otu

• Severe alleles of the ovarian tumor (otu) and ovo genes result in female sterility in Drosophila melanogaster, producing adult ovaries that completely lack egg chambers [1].

High impact information on otu

• It has been proposed that otu phenotypes result from abnormal germ cell division and differentiation [2].
• To understand better what role otu performs in oogenesis we have undertaken an analysis of protein expression from the otu locus [2].
• Immunostaining of otu proteins is restricted to the cytoplasm of germ cells, and a rapid loss of oocyte immunostaining during stage 11 suggests that there is a rapid and selective degradation of otu proteins within the oocyte but not within its 15 interconnected nurse cells [2].
• Sequence analysis of otu cDNAs suggests that these proteins are translated from two mRNAs generated by alternative splicing of a 126-bp exon between the sixth and seventh exon of the smaller transcript [2].
• An apparent null mutation causes abnormal cysts to form containing an excess number of cells that cannot differentiate into gametes. bam function resides within a simple 2.2-kb transcription unit encoding a single 442-amino-acid protein that shows similarity to the product of the ovarian tumor gene [3].

Biological context of otu

• The locus ovarian tumor (otu) is involved in several aspects of oogenesis in Drosophila melanogaster [4].
• Some otu alleles produce a phenotype known as ovarian tumors: ovarioles are filled with numerous poorly differentiated germ cells [4].
• Finally, we show that the gene dosage of otu modifies the phenotype of ovaries heterozygous for the dominant alleles of ovo, another gene involved in germ line sex determination [4].
• Hrb27C, Sqd and Otu cooperatively regulate gurken RNA localization and mediate nurse cell chromosome dispersion in Drosophila oogenesis [5].
• Loss-of-function, gain-of-function and promoter swapping constructs demonstrate that OVO binding near the transcription start site is required for OVO-dependent otu transcription in vivo [6].

Anatomical context of otu

• The possible role of otu in the determination of the sexual identity of germ cells has not been extensively explored [4].
• Synergistic interaction between ovoD1 and otu alleles leads to the occasional transformation of chromosomally female germ cells into early spermatocytes [4].
• We show that the transport is ineffective in the qui and otu mutants apparently due to the lack of a properly differentiated oocyte [7].
• In salivary glands of SuUR and in the nurse cells of otu mutants, under-replication is partly suppressed and a banded structure appears within the centric heterochromatin of chromosome 3 [8].
• Immunolocalization experiments demonstrated that otu protein is present in the cytoplasm of oogonial stem cells that populate third instar larvae and in all germ-line-derived cells until late in oogenesis [9].

Associations of otu with chemical compounds

• The proline-rich, hydrophilic otu protein is novel [10].

Physical interactions of otu

• Interestingly, the strongest OVO-binding site is very near the otu transcription start, where basal transcriptional complexes must function [6].
• The Drosophila gene fs(2)cup interacts with otu to define a cytoplasmic pathway required for the structure and function of germ-line chromosomes [11].

Regulatory relationships of otu

• The position of the otu locus in the regulatory cascade of germ line sex determination has been studied by using mutations that constitutively express the feminizing activity of the Sxl gene [4].
• Drosophila OVO regulates ovarian tumor transcription by binding unusually near the transcription start site [6].
• In particular, hfp mutants display striking defects in the developmentally regulated splicing of ovarian tumor (otu) [12].
• Even more extreme shortening of life spans were observed when the sex peptide gene (Acp70A) was expressed in homozygous otu females, though they were virgin, indicating that the shortening in life span is due to seminal factors [13].

Other interactions of otu

• Our analyses support dual cooperative roles for Sqd, Hrb27C and Otu during Drosophila oogenesis [5].
• This shows that otu acts upstream of Sxl in the process of germ line sex determination [4].
• Furthermore, transgenic expression of the missing otu splice form can rescue the ovarian phenotypes of hfp [12].
• By testing for expression of male germline traits, we determined that partial germline sex transformation occurs in otu, snf, Sxlfs, and bam ovarian tumors [14].
• Mutations in otu and ovo cause a range of ovarian defects, including agametic ovaries and tumorous egg cysts, but do not affect spermatogenesis [15].

Analytical, diagnostic and therapeutic context of otu

• Reciprocal cross and developmental Northern blot studies suggest a maternal requirement for otu in the development of the female germline [16].

References