scholarly journals The Drosophila sex determination gene snf is utilized for the establishment of the female-specific splicing pattern of Sex-lethal.

Genetics ◽  
1993 ◽  
Vol 134 (3) ◽  
pp. 801-807
Author(s):  
E B Albrecht ◽  
H K Salz
Keyword(s):  
Sex Determination ◽  
Rna Splicing ◽  
Null Allele ◽  
Early Embryogenesis ◽  
Wild Type ◽  
Female Progeny ◽  
Splicing Pattern ◽  
Late Embryogenesis ◽  
Sex Lethal ◽  
Female Specific

Abstract The Drosophila snf gene is a positive regulator of the sex determination gene Sex-lethal in both the germline and the soma. Its role in the soma is only evident when the probability of Sex-lethal activation has been reduced. For instance, in an otherwise wild-type background, females homozygous for a weak snf mutation produce both male and female progeny; however, when mated to males hemizygous for a null allele of Sex-lethal, they produce only male progeny. We demonstrate that the lack of female progeny is due to aberrant Sex-lethal regulation in late embryogenesis. In these mutant embryos, there is little accumulation of the late female-specific spliced RNAs and proteins. In contrast, in early embryogenesis, Sex-lethal regulation is not affected. The accumulation of both the early Sex-lethal transcripts and proteins is normal. These results suggest that the wild-type product of snf plays an important role in establishing the female-specific RNA splicing pattern of Sex-lethal. Whether snf influences the female-specific splice site choice directly or indirectly remains to be determined.

Induction of female Sex-lethal RNA splicing in male germ cells: implications for Drosophila germline sex determination

Development ◽  
1997 ◽  
Vol 124 (24) ◽  
pp. 5033-5048 ◽  
Author(s):  
J.H. Hager ◽  
T.W. Cline
Keyword(s):  
Sex Determination ◽  
Germ Cells ◽  
Rna Splicing ◽  
Feedback Loop ◽  
Dose Effect ◽  
Male Germ Cells ◽  
Control Female ◽  
Sex Lethal ◽  
Specific Regulation ◽  
Female Specific

With a focus on Sex-lethal (Sxl), the master regulator of Drosophila somatic sex determination, we compare the sex determination mechanism that operates in the germline with that in the soma. In both cell types, Sxl is functional in females (2X2A) and nonfunctional in males (1X2A). Somatic cell sex is determined initially by a dose effect of X:A numerator genes on Sxl transcription. Once initiated, the active state of SXL is maintained by a positive autoregulatory feedback loop in which Sxl protein insures its continued synthesis by binding to Sxl pre-mRNA and thereby imposing the productive (female) splicing mode. The gene splicing-necessary factor (snf), which encodes a component of U1 and U2 snRNPs, participates in this RNA splicing control. Here we show that an increase in the dose of snf+ can trigger the female Sxl RNA splicing mode in male germ cells and can feminize triploid intersex (2X3A) germ cells. These snf+ dose effects are as dramatic as those of X:A numerator genes on Sxl in the soma and qualify snf as a numerator element of the X:A signal for Sxl in the germline. We also show that female-specific regulation of Sxl in the germline involves a positive autoregulatory feedback loop on RNA splicing, as it does in the soma. Neither a phenotypically female gonadal soma nor a female dose of X chromosomes in the germline is essential for the operation of this feedback loop, although a female X-chromosome dose in the germline may facilitate it. Engagement of the Sxl splicing feedback loop in somatic cells invariably imposes female development. In contrast, engagement of the Sxl feedback loop in male germ cells does not invariably disrupt spermatogenesis; nevertheless, it is premature to conclude that Sxl is not a switch gene in germ cells for at least some sex-specific aspects of their differentiation. Ironically, the testis may be an excellent organ in which to study the interactions among regulatory genes such as Sxl, snf, ovo and otu which control female-specific processes in the ovary.

scholarly journals Both Loss-of-Function and Gain-of-Function Mutations in snf Define a Role for snRNP Proteins in Regulating Sex-lethal Pre-mRNA Splicing in Drosophila Development

Genetics ◽  
1996 ◽  
Vol 144 (1) ◽  
pp. 95-108
Author(s):  
Helen K Salz ◽  
Thomas W Flickinger
Keyword(s):  
Sex Determination ◽  
Rna Splicing ◽  
Loss Of Function ◽  
Functional Homology ◽  
Snrnp Protein ◽  
A Cell ◽  
Sex Lethal ◽  
Mutant Phenotypes ◽  
Female Specific ◽  
Male Specific

Abstract The Drosophila snf gene encodes a protein with functional homology to the mammalian UlA and U2B″ snRNP proteins. Studies, based on the analysis of three viable alleles, have suggested a role for snf in establishing the female-specific splicing pattern of the sex determination switch gene, Sex-lethal. Here, we show that the non-sex-specific lethal null allele is required for female sex determination, arguing against the formal possibility that the viable alleles disrupt a function unrelated to snf's wild-type function. Moreover, we find snf is required for normal cell growth and/or survival, as expected for a protein involved in a cell-vital process such as RNA splicing. We also show that of the three viable alleles only one, snfJA2, is a partial loss-of-function mutation. The other two viable alleles, snf1621 and snfe8H, encode antimorphic proteins. We find the antimorphic proteins are mislocalized and correlate their mislocalization with their molecular lesions and mutant phenotypes. Finally, we provide genetic evidence that the antimorphic alleles interfere with the autoregulatory splicing function of the Sex-lethal protein. Based on these studies we suggest a model in which the snRNP protein, Snf, functions with Sex-lethal to block recognition of the regulated male-specific exon.

scholarly journals A conserved role of the duplicated Masculinizer gene in sex determination of the Mediterranean flour moth, Ephestia kuehniella

2021 ◽  
Author(s):  
Sander Visser ◽  
Anna Voleníková ◽  
Petr Nguyen ◽  
Eveline C. Verhulst ◽  
František Marec
Keyword(s):  
Sex Determination ◽  
Early Embryogenesis ◽  
Ephestia Kuehniella ◽  
Z Chromosome ◽  
Female Development ◽  
Biased Sex Ratio ◽  
The Mediterranean ◽  
Female Specific ◽  
Mediterranean Flour Moth

AbstractSex determination in the silkworm, Bombyx mori, is based on Feminizer (Fem), a W-linked Fem piRNA that triggers female development in WZ individuals, and the Z-linked Masculinizer (Masc), which initiates male development and dosage compensation in ZZ individuals. While Fem piRNA is missing in a close relative of B. mori, Masc determines sex in several representatives of distant lepidopteran lineages. We studied the molecular mechanisms of sex determination in the Mediterranean flour moth, Ephestia kuehniella (Pyralidae). We identified an E. kuehniella Masc ortholog, EkMasc, and its paralog resulting from a recent duplication, EkMascB. Both genes are located on the Z chromosome and encode a similar Masc protein that contains two conserved domains but has lost the conserved double zinc finger domain. We developed PCR-based genetic sexing and demonstrated a peak in the expression of EkMasc and EkMascB genes only in early male embryos. Simultaneous knock-down experiments of both EkMasc and EkMascB using RNAi during early embryogenesis led to a shift from male- to female-specific splicing of the E. kuehniella doublesex gene (Ekdsx), their downstream effector, in ZZ embryos and resulted in a strong female-biased sex-ratio. Our results thus confirmed the conserved role of both EkMasc and EkMascB genes in masculinization. We suggest that the C-terminal proline-rich domain, we have identified in all functionally confirmed Masc proteins, in conjunction with the masculinizing domain, is important for transcriptional regulation of sex determination in Lepidoptera. The function of the Masc double zinc finger domain is still unknown, but appears to have been lost in E. kuehniella.Author summaryThe sex-determining cascade in the silkworm, Bombyx mori, differs greatly from those of other insects. In B. mori, female development is initiated by Fem piRNA expressed from the W chromosome during early embryogenesis. Fem piRNA silences Masculinizer (Masc) thereby blocking the male pathway resulting in female development. It is currently unknown whether this cascade is conserved across Lepidoptera. In the Mediterranean flour moth, Ephestia kuehniella, we identified an ortholog of Masc and discovered its functional duplication on the Z chromosome, which has not yet been found in any other lepidopteran species. We provide two lines of evidence that both the EkMasc and EkMascB genes play an essential role in masculinization: (i) they show a peak of expression during early embryogenesis in ZZ but not in WZ embryos and (ii) their silencing by RNAi results in female-specific splicing of the E. kuehniella doublesex gene (Ekdsx) in ZZ embryos and in a female-biased sex ratio. Our results suggest a conserved role of the duplicated Masc gene in sex determination of E. kuehniella.

Genetic evidence that the sans fille locus is involved in Drosophila sex determination.

Genetics ◽  
1988 ◽  
Vol 120 (1) ◽  
pp. 159-171
Author(s):  
B Oliver ◽  
N Perrimon ◽  
A P Mahowald
Keyword(s):  
Sex Determination ◽  
Dosage Compensation ◽  
Germ Line ◽  
Ovarian Tumors ◽  
Lethal Gene ◽  
Nurse Cells ◽  
Loss Of Function ◽  
Wild Type ◽  
Sex Lethal

Abstract Females homozygous for sans fille1621 (= fs(1)1621) have an abnormal germ line. Instead of producing eggs, the germ-line cells proliferate forming ovarian tumors or excessive numbers of nurse cells. The Sex-lethal gene product(s) regulate the branch point of the dosage compensation and sex determination pathways in the soma. The role of Sex-lethal in the germ line is not clear but the germ line of females homozygous for female sterile Sex-lethal alleles or germ-line clones of loss-of-function alleles are characterized by ovarian tumors. Females heterozygous for sans fille1621 or Sex-lethal are phenotypically wild type with respect to viability and fertility but females trans-heterozygous for sans fille1621 and Sex-lethal show ovarian tumors, somatic sexual transformations, and greatly reduced viability.

scholarly journals Analysis of the Doublesex Female Protein in Drosophila melanogaster: Role in Sexual Differentiation and Behavior and Dependence on Intersex

Genetics ◽  
1999 ◽  
Vol 152 (4) ◽  
pp. 1653-1667 ◽  
Author(s):  
Julie A Waterbury ◽  
Larry L Jackson ◽  
Paul Schedl
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Determination ◽  
Target Genes ◽  
Negative Regulator ◽  
Wild Type ◽  
Binding Properties ◽  
Behavioral Abnormalities ◽  
Female Specific ◽  
And Behavior ◽  
Dna Binding Properties

Abstract doublesex (dsx) is unusual among the known sex-determination genes of Drosophila melanogaster in that functional homologs are found in distantly related species. In flies, dsx occupies a position near the bottom of the sex determination hierarchy. It is expressed in male- and female-specific forms and these proteins function as sex-specific transcription factors. In the studies reported here, we have ectopically expressed the female Dsx protein (DsxF) from a constitutive promoter and examined its regulatory activities independent of other upstream factors involved in female sex determination. We show that it functions as a positive regulator of female differentiation and a negative regulator of male differentiation. As predicted by the DNA-binding properties of the Dsx protein, DsxF and DsxM compete with each other for the regulation of target genes. In addition to directing sex-specific differentiation, DsxF plays an important role in sexual behavior. Wild-type males ectopically expressing DsxF are actively courted by other males. This acquisition of feminine sex appeal is likely due to the induction of female pheromones by DsxF. More extreme behavioral abnormalities are observed when DsxF is ectopically expressed in dsx- XY animals; these animals are not only courted by, but also copulate with, wild-type males. Finally, we provide evidence that intersex is required for the feminizing activities of DsxF and that it is not regulated by the sex-specific splicing cascade.

scholarly journals Transposon insertions causing constitutive Sex-lethal activity in Drosophila melanogaster affect Sxl sex-specific transcript splicing.

Genetics ◽  
1995 ◽  
Vol 139 (2) ◽  
pp. 631-648
Author(s):  
M Bernstein ◽  
R A Lersch ◽  
L Subrahmanyan ◽  
T W Cline
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Rna Splicing ◽  
Wild Type ◽  
Gain Of Function ◽  
Positive Regulators ◽  
Sex Lethal ◽  
Male Specific ◽  
Transposon Insertions

Abstract Sex-lethal (Sxl) gene products induce female development in Drosophila melanogaster and suppress the transcriptional hyperactivation of X-linked genes responsible for male X-chromosome dosage compensation. Control of Sxl functioning by the dose of X-chromosomes normally ensures that the female-specific functions of this developmental switch gene are only expressed in diplo-X individuals. Although the immediate effect of X-chromosome dose is on Sxl transcription, during most of the life cycle "on" vs. "off" reflects alternative Sxl RNA splicing, with the female (productive) splicing mode maintained by a positive feedback activity of SXL protein on Sxl pre-mRNA splicing. "Male-lethal" (SxlM) gain-of-function alleles subvert Sxl control by X-chromosome dose, allowing female Sxl functions to be expressed independent of the positive regulators upstream of Sxl. As a consequence, SxlM haplo-X animals (chromosomal males) die because of improper dosage compensation, and SxlM chromosomal females survive the otherwise lethal effects of mutations in upstream positive regulators. Five independent spontaneous SxlM alleles were shown previously to be transposon insertions into what was subsequently found to be the region of regulated sex-specific Sxl RNA splicing. We show that these five alleles represent three different mutant types: SxlM1, SxlM3, and SxlM4. SxlM1 is an insertion of a roo element 674 bp downstream of the translation-terminating male-specific exon. SxlM3 is an insertion of a hobo transposon (not 297 as previously reported) into the 3' splice site of the male exon, and SxlM4 is an insertion of a novel transposon into the male-specific exon itself. We show that these three gain-of-function mutants differ considerably in their ability to bypass the sex determination signal, with SxlM4 being the strongest and SxlM1 the weakest. This difference is also reflected in effects of these mutations on sex-specific RNA splicing and on the rate of appearance of SXL protein in male embryos. Transcript analysis of double-mutant male-viable SxlM derivatives in which the SxlM insertion is cis to loss-of-function mutations, combined with other results reported here, indicates that the constitutive character of these SxlM alleles is a consequence of an alteration of the structure of the pre-mRNA that allows some level of female splicing to occur even in the absence of functional SXL protein. Surprisingly, however, most of the constitutive character of SxlM alleles appears to depend on the mutant alleles' responsiveness, perhaps greater than wild-type, to the autoregulatory splicing activity of the wild-type SXL proteins they produce.

scholarly journals Regulation of behavioral and pheromonal aspects of sex determination in Drosophila melanogaster by the Sex-lethal gene.

Genetics ◽  
1989 ◽  
Vol 123 (3) ◽  
pp. 535-541 ◽  
Author(s):  
L Tompkins ◽  
S P McRobert
Keyword(s):  
Drosophila Melanogaster ◽  
Sexual Behavior ◽  
Sex Determination ◽  
Ectopic Expression ◽  
Lethal Gene ◽  
Gene Products ◽  
Morphological Aspects ◽  
Sex Lethal ◽  
Normal Males ◽  
Female Specific

Abstract We have shown that the Sex-lethal (Sxl) gene, which controls morphological aspects of sex determination in Drosophila melanogaster, also regulates sexual behavior. Chromosomal males that are hemizygous for a deletion of the entire Sxl locus perform normal courtship and synthesize the two courtship-inhibiting pheromones that normal males make. However, ectopic expression of female-specific Sex-lethal gene products drastically alters chromosomal males' ability to perform and elicit courtship and increases the probability that they will synthesize a courtship-stimulating pheromone or fail to synthesize one of the inhibitory pheromones. These observations suggest that male sexual behavior is a consequence of the Sxl gene's being functionally inactive in haplo-X flies.

scholarly journals sisterless A is required for the activation of Sex lethal in the germline

2019 ◽  
Author(s):  
Raghav Goyal ◽  
Ellen Baxter ◽  
Mark Van Doren
Keyword(s):  
Sex Determination ◽  
X Chromosome ◽  
Germ Cells ◽  
Specific Expression ◽  
Male Germ Cells ◽  
X Chromosomes ◽  
Dna Elements ◽  
Sex Lethal ◽  
Female Specific ◽  
Necessary And Sufficient

ABSTRACTIn Drosophila, sex determination in somatic cells has been well-studied and is under the control of the switch gene Sex lethal (Sxl), which is activated in females by the presence of two X chromosomes. Though sex determination is regulated differently in the germline versus the soma, Sxl is also necessary and sufficient for the female identity in germ cells. Loss of Sxl function in the germline results in ovarian germline tumors, a characteristic of male germ cells developing in a female soma. Further, XY (male) germ cells expressing Sxl are able to produce eggs when transplanted into XX (female) somatic gonads, demonstrating that Sxl is also sufficient for female sexual identity in the germline. As in the soma, the presence of two X chromosomes is sufficient to activate Sxl in the germline, but the mechanism for “counting” X chromosomes in the germline is thought to be different from the soma. Here we have explored this mechanism at both cis- and trans-levels. Our data support the model that the Sxl “establishment” promoter (SxlPE) is activated in a female-specific manner in the germline, as in the soma, but that the timing of SxlPE activation, and the DNA elements that regulate SxlPE are different from those in the soma. Nevertheless, we find that the X chromosome-encoded gene sisterless A (sisA), which helps activate Sxl in the soma, is also essential for Sxl activation in the germline. Loss of sisA function leads to loss of Sxl expression in the germline, and to ovarian tumors and germline loss. These defects can be rescued by the expression of Sxl, demonstrating that sisA lies upstream of Sxl in germline sex determination. We conclude that sisA acts as an X chromosome counting element in both the soma and the germline, but that additional factors that ensure robust, female-specific expression of Sxl in the germline remain to be discovered.

scholarly journals The Drosophila melanogaster Sex Determination Gene sisA Is Required in Yolk Nuclei for Midgut Formation

Genetics ◽  
2000 ◽  
Vol 155 (1) ◽  
pp. 191-202 ◽  
Author(s):  
Jeffrey J Walker ◽  
Karin K Lee ◽  
Rushin N Desai ◽  
James W Erickson
Keyword(s):  
Sex Determination ◽  
Null Allele ◽  
Gut Development ◽  
Direct Role ◽  
Yolk Cell ◽  
Gene Functions ◽  
Essential Function ◽  
Sex Lethal ◽  
Key Aspects

Abstract During sex determination, the sisterlessA (sisA) gene functions as one of four X:A numerator elements that set the alternative male or female regulatory states of the switch gene Sex-lethal. In somatic cells, sisA functions specifically in sex determination, but its expression pattern also hints at a role in the yolk cell, a syncytial structure believed to provide energy and nutrients to the developing embryo. Previous studies of sisA have been limited by the lack of a null allele, leaving open the possibility that sisA has additional functions. Here we report the isolation and molecular characterization of four new sisA alleles including two null mutations. Our findings highlight key aspects of sisA structure-function and reveal important qualitative differences between the effects of sisA and the other strong X:A numerator element, sisterlessB, on Sex-lethal expression. We use genetic, expression, clonal, and phenotypic analyses to demonstrate that sisA has an essential function in the yolk nuclei of both sexes. In the absence of sisA, endoderm migration and midgut formation are blocked, suggesting that the yolk cell may have a direct role in larval gut development. To our knowledge, this is the first report of a requirement for the yolk nuclei in Drosophila development.

Sex-lethal, a Drosophila sex determination switch gene, exhibits sex-specific RNA splicing and sequence similarity to RNA binding proteins

Cell ◽  
1988 ◽  
Vol 55 (6) ◽  
pp. 1037-1046 ◽  
Author(s):  
Leslie R. Bell ◽  
Eleanor M. Maine ◽  
Paul Schedl ◽  
Thomas W. Cline
Keyword(s):  
Sex Determination ◽  
Rna Splicing ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Sequence Similarity ◽  
Sex Lethal
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