Expression of the Sex-lethal gene is controlled at multiple levels during Drosophila oogenesis

Abstract

In addition to controlling somatic sexual development in Drosophila melanogaster, the Sex-lethal (Sxl) gene is required for proper differentiation of female germ cells. To investigate its role in germ-line development, we have examined the expression of Sxl in wild-type ovaries and ovaries that are defective in early steps of germ cell differentiation. As in the soma, the basic mechanism for on/off regulation of Sxl relies on sex-specific processing of its transcripts in germ cells. One class of female-sterile mutations, which includes fs(1)1621 and the tumorous-ovary-producing allele of the ovarian tumor gene, otu1, is defective in the splicing process. These mutants have germ lines with high amounts of Sxl RNA spliced in the male mode and a severe reduction of protein levels in the germ cells. Another class of female-sterile mutations produces a phenotype similar to that seen in fs(1)1621 and otu1 but appears to express normal levels of Sxl protein in the germ cells. However, this second class does not show the changes in protein distribution normally observed in wild-type germ cells. In the wild-type germarium, the non-differentiated germ cells show a strong cytoplasmic accumulation of Sxl protein followed, as the germ cells differentiate, by a dramatic reduction and redistribution of the protein into nuclear foci. Interestingly, two female-sterile alleles of Sxl, Sxlf4 and Sxlf5 belong to the second class, which shows persistent cytoplasmic accumulation of Sxl protein. These Sxl female-sterile mutants encode an altered protein indicating that Sxl regulates processes that eventually lead to the changes in Sxl protein distribution. Lastly, we demonstrate that during the final stages of oogenesis several mechanisms must operate to prevent the progeny from inheriting Sxl protein. Conceivably, this regulation safeguards the inadvertent activation of the Sxl autoregulatory feedback loop in the male zygote.

Tudor domain containing protein 5-like(Tdrd5l) identifies a novel germline body and regulates maternal RNAs during oogenesis

“…Unlike in the male GSCs (Fig 1B brackets), Tdrd5l granules were absent from the germline stem cells (GSCs) in females (Fig 1D, brackets). Since Sxl represses Tdrd5l expression (25), this likely accounts for the lack of Tdrd5l expressing in female GSCs where Sxl is at highest levels (28). At later stages in the female germline, we observed Tdrd5l localizing to granules in the early differentiating germline of the germarium (Fig 1C), as well as in the nurse cells (Fig 1E and 1F, white arrow) and oocyte (Fig 1E, yellow arrow) until mid-oogenesis.…”

Checkpoint activation drives global gene expression changes in Drosophila nuclear lamina mutants

“…GLKD of BAF was achieved crossing the w 1118 , nanos (nos)>gal4VP16 driver line (Bloomington # 4937) and the y 1 , sc*, v 1 , sev 21 ; P[Trip.HMS00195]attP2 (Bloomington # 36108) short hairpin RNA responder. Other mutants used include tud 1 that carries a K1036term mutation, tud A36-38 (a kind gift of the R. Lehmann laboratory), and bag-of-marbles ( bam Δ86 ; BL # 5427) that carries a 1.7-kb deletion in the coding region ( Bopp et al 1993 ).…”

The sex determination master switch, Sex-lethal, responds to Hedgehog signaling in theDrosophilagermline

“…As these cells mature, there is a marked drop in the level of cytoplasmic Sxl. After this downregulation, Sxl is detected in mid-region 1 of the germarium as bright nuclear foci (Bopp et al, 1993). The intensity of Sxl in the nucleus and cytoplasm increases as the germ cells progress down the germarium (Figs 1B,2A).…”

“…Ovaries were fixed and stained (Bopp et al, 1993). Fifty or more ovarioles from a minimum of two separate stainings were counted from at least six different pairs of ovaries.…”

“…RNA extraction, RT, PCR and Southern blot analysis were performed (Bopp et al, 1993) but a mixture of Pfu DNA polymerase (Stratagene) and Klentaq1 (Ab Peptides) was used (Barnes, 1994).…”