A small region on the X chromosome of Drosophila regulates a key gene that controls sex determination and dosage compensation

Steinmann‐Zwicky, Monica; Nöthiger, Rolf

doi:10.1016/0092-8674(85)90284-3

Cited by 23 publications

(4 citation statements)

References 26 publications

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“…Steinmann-Zwicky and Nothiger have reported sequences localized in the distal region of the X chromosome with a strong feminizing effect (31) that challenges this traditional view of multiple female-determining factors distributed throughout the entire chromosome. However, unlike these localized sequences that appear to be necessary for proper Sxl activation, we suggest that our XDm sequences might be involved in assessing the X/A ratio.…”

Section: Resultsmentioning

confidence: 94%

Cloning and characterization of a dispersed, multicopy, X chromosome sequence in Drosophila melanogaster.

Waring¹,

Pollack²

1987

Proc. Natl. Acad. Sci. U.S.A.

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We have isolated and characterized a dispersed middle repetitive DNA sequence from Drosophila melanogaster that is concentrated on the euchromatic portion of the X chromosome. In situ hybridization of the repeat unit to salivary gland chromosomes shows the sequence is distributed among approximately 10 major and 20 minor X chromosomal sites. Based on DNA sequence analysis of homologous sequences from three different cytogenetic regions, the 372-base-pair repeat unit appears to be (A+T)-rich and noncoding and shows strong sequence conservation among units from different chromosomal regions. The nature and distribution of this sequence are suggestive of the hypothetical X chromosome DNA sequences thought to be involved in the primary establishment of sex determination and dosage compensation in Drosophila.The Drosophila genome consists of three kinetic components, highly repetitive, middle repetitive, and unique DNA (1). The middle repetitive fraction constitutes -417% of the total genomic DNA and includes the tandemly repeated rRNA, 5S RNA, and histone genes. Most of the middle repetitive DNA in Drosophila melanogaster, however, is not tandemly repeated but rather is dispersed over the entire genome (2). It is composed of at least 50-100 different sequence families, each of which generally consists of 10-100 closely related sequences (2). The number of sequences within a family seems to be conserved in different strains of the species, but their chromosomal positions are highly variable. In marked contrast, in this paper we describe a dispersed middle repetitive family with repeats at chromosomal positions that are conserved between strains. More importantly, the repeat units are concentrated in the euchromatic portion of the X chromosome. A functional link between family members is suggested by the extensive sequence homology found between repeats from different chromosomal regions. The intriguing possibility that these sequences may play a role in the primary establishment of sex determination and dosage compensation in Drosophila is considered. MATERIALS AND METHODSPreparation of Nucleic Acids. The Maniatis X bacteriophage library of D. melanogaster genomic DNA (3) was screened by in situ plaque hybridization (4) under low stringency hybridization [4x SET (0.6 M NaCl/8 mM EDTA/0.12 M Tris HCl, pH 8), 43% formamide, 37°C] and wash conditions (0.3 M NaCl/30 mM sodium citrate, pH 7, 37°C) with the 32P-labeled single-stranded RNA probe described in the text.Phage from single plaques were purified from liquid cultures by centrifugation in CsCl block gradients (5); phage DNA was purified with NaDodSO4, proteinase K, and phenol. For smaller quantities, DNA was prepared from phage lysates with RNase, NaDodSO4, and phenol.Subclones were generated by inserting gel-purified restriction fragments into the appropriate sites of the pGem-1 and pGem-2 transcription vectors (Promega Biotec, Madison, WI). Recombinant plasmids were used to transfect Escherichia coli HB101. To confirm their identity, alkaline minipreparat...

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Section: Resultsmentioning

confidence: 94%

Cloning and characterization of a dispersed, multicopy, X chromosome sequence in Drosophila melanogaster.

Waring¹,

Pollack²

1987

Proc. Natl. Acad. Sci. U.S.A.

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“…Discovery of the involvement of snf in Sxl regulation began with the observation that females heterozygous for both Sxl Ϫ and X chromosome deficiencies removing snf were partially sex transformed and͞or inviable (2). Attention was drawn to snf 1621 , a female sterile mutation that interacted with Sxl Ϫ just like the deficiencies and was suppressed by gain-of-function (g.o.f.)…”

mentioning

confidence: 99%

Functioning of the Drosophila integral U1/U2 protein Snf independent of U1 and U2 small nuclear ribonucleoprotein particles is revealed by snf ⁺ gene dose effects

Cline

Rudner

Barbash

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

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Snf, encoded by sans fille, is the Drosophila homolog of mammalian U1A and U2B and is an integral component of U1 and U2 small nuclear ribonucleoprotein particles (snRNPs). Surprisingly, changes in the level of this housekeeping protein can specifically affect autoregulatory activity of the RNA-binding protein Sex-lethal (Sxl) in an action that we infer must be physically separate from Snf's functioning within snRNPs. Sxl is a master switch gene that controls its own pre-mRNA splicing as well as splicing for subordinate switch genes that regulate sex determination and dosage compensation. Exploiting an unusual new set of mutant Sxl alleles in an in vivo assay, we show that Snf is rate-limiting for Sxl autoregulation when Sxl levels are low. In such situations, increasing either maternal or zygotic snf ؉ dose enhances the positive autoregulatory activity of Sxl for Sxl somatic pre-mRNA splicing without affecting Sxl activities toward its other RNA targets. In contrast, increasing the dose of genes encoding either the integral U1 snRNP protein U1-70k, or the integral U2 snRNP protein SF3a 60 , has no effect. Increased snf ؉ enhances Sxl autoregulation even when U1-70k and SF3a 60 are reduced by mutation to levels that, in the case of SF3a 60 , demonstrably interfere with Sxl autoregulation. The observation that increased snf ؉ does not suppress other phenotypes associated with mutations that reduce U1-70k or SF3a 60 is additional evidence that snf ؉ dose effects are not caused by increased snRNP levels. Mammalian U1A protein, like Snf, has a snRNP-independent function.

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“…Such a phenomenon was recently established in Drosophila, a species in which only a small region of the X directs ovarian development. 8 In humans, proximal Xql3 is clearly of greatest importance. However, other regions could play secondary roles.…”

Section: Isochromosome For the X Long Arm [I(xq]mentioning

confidence: 99%

Genetic Control of Sex Determination

Simpson¹

1987

Semin Reprod Med

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A small region on the X chromosome of Drosophila regulates a key gene that controls sex determination and dosage compensation

Cited by 23 publications

References 26 publications

Cloning and characterization of a dispersed, multicopy, X chromosome sequence in Drosophila melanogaster.

Cloning and characterization of a dispersed, multicopy, X chromosome sequence in Drosophila melanogaster.

Functioning of the Drosophila integral U1/U2 protein Snf independent of U1 and U2 small nuclear ribonucleoprotein particles is revealed by snf ⁺ gene dose effects

Genetic Control of Sex Determination

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A small region on the X chromosome of Drosophila regulates a key gene that controls sex determination and dosage compensation

Cited by 23 publications

References 26 publications

Cloning and characterization of a dispersed, multicopy, X chromosome sequence in Drosophila melanogaster.

Cloning and characterization of a dispersed, multicopy, X chromosome sequence in Drosophila melanogaster.

Functioning of the Drosophila integral U1/U2 protein Snf independent of U1 and U2 small nuclear ribonucleoprotein particles is revealed by snf + gene dose effects

Genetic Control of Sex Determination

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Product

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Functioning of the Drosophila integral U1/U2 protein Snf independent of U1 and U2 small nuclear ribonucleoprotein particles is revealed by snf ⁺ gene dose effects