The role of the ovarian tumor locus in Drosophila melanogaster germ line sex determination

The locus ovarian tumor (otu) is involved in several aspects of oogenesis in Drosophila melanogaster. The possible role of otu in the determination of the sexual identity of germ cells has not been extensively explored. Some otu alleles produce a phenotype known as ovarian tumors: ovarioles are filled with numerous poorly differentiated germ cells. We show that these mutant germ cells have a morphology similar to primary spermatocytes and that they express male germ line-specific reporter genes. This indicates that they are engaged along the male pathway of germ line differentiation. Consistent with this conclusion, we found that the splicing of Sex-lethal (Sxl) pre-mRNAs occurs in the male-specific mode in otu-transformed germ cells. 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. The sexual transformation of the germ cells observed with several combinations of otu alleles can be reversed by constitutive expression of Sxl. This shows that otu acts upstream of Sxl in the process of germ line sex determination. Other phenotypes of otu mutations were not rescued by constitutive expression of Sxl, suggesting that several functions of otu are likely to be independent of sex determination. 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. One dose of otu+ enhances the ovoD ovarian phenotypes, while three doses partially suppress these phenotypes. Synergistic interaction between ovoD1 and otu alleles leads to the occasional transformation of chromosomally female germ cells into early spermatocytes. These interactions are similar to those observed between ovoD and one allele of the sans fille (snf) locus. Altogether, our results imply that the otu locus acts, along with ovo, snf, and Sxl, in a pathway (or parallel pathways) required for proper sex determination of the female germ line.

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Genetic control of sex determination in the germ line and soma of the housefly, Musca domestica

Development ◽

10.1242/dev.120.9.2531 ◽

1994 ◽

Vol 120 (9) ◽

pp. 2531-2538 ◽

Cited By ~ 2

Author(s):

D. Hilfiker-Kleiner ◽

A. Dubendorfer ◽

A. Hilfiker ◽

R. Nothiger

Keyword(s):

Sex Determination ◽

Musca Domestica ◽

Germ Cells ◽

Maternal Effect ◽

Germ Line ◽

M Cells ◽

Female Genotype ◽

Female Germ Line ◽

Pole Cells

In Musca domestica, sex in the soma is cell autonomously determined by the male-determiner M, or by the female-determiner FD. Transplanted pole cells (precursors of the germ line) show that sex determination of germ cells is non-autonomous genotypically male pole cells form functional eggs in female hosts, and genotypically female pole cells form functional sperm in male hosts. When M/+ cells undergo oogenesis, a male-determining maternal effect predetermines offspring without M, i.e. of female genotype, to develop as fertile males. FD is epistatic to M in the female germ line, as it is in the soma, overruling the masculinizing effect of M. The results suggest that maternal F product is needed for activation of the zygotic F gene.

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Genetic evidence that the ovo locus is involved in Drosophila germ line sex determination.

Genetics ◽

10.1093/genetics/125.3.535 ◽

1990 ◽

Vol 125 (3) ◽

pp. 535-550 ◽

Cited By ~ 1

Author(s):

B Oliver ◽

D Pauli ◽

A P Mahowald

Keyword(s):

Drosophila Melanogaster ◽

Sex Determination ◽

Sexual Identity ◽

Gene Product ◽

Germ Cells ◽

Germ Line ◽

Partial Transformation ◽

Loss Of Function ◽

Lethal Allele ◽

Sex Lethal

Abstract Zygotically contributed ovo gene product is required for the survival of female germ cells in Drosophila melanogaster. Trans-allelic combinations of weak and dominant ovo mutations (ovoD) result in viable germ cells that appear to be partially transformed from female to male sexual identity. The ovoD2 mutation is partially suppressed by many Sex-lethal alleles that affect the soma, while those that affect only the germ line fail to interact with ovoD2. One of two loss-of-function ovo alleles is suppressed by a loss-of-function Sex-lethal allele. Because ovo mutations are germ line dependent, it is likely that ovo is suppressed by way of communication between the somatic and germ lines. A loss-of-function allele of ovo is epistatic to germ line dependent mutations in Sex-lethal. The germ line dependent sex determination mutation, sans fille, and ovoD mutations show a dominant synergistic interaction resulting in partial transformation of germ line sexual identity. The ovo locus appears to be involved in germ line sex determination and is linked in some manner to sex determination in the soma.

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Sex-lethal, master and slave: a hierarchy of germ-line sex determination in Drosophila

Development ◽

10.1242/dev.119.3.897 ◽

1993 ◽

Vol 119 (3) ◽

pp. 897-908 ◽

Cited By ~ 14

Author(s):

B. Oliver ◽

Y.J. Kim ◽

B.S. Baker

Keyword(s):

Drosophila Melanogaster ◽

Sex Determination ◽

Ovarian Tumor ◽

Germ Line ◽

Female Sex ◽

Somatic Signal ◽

Female Germ Line ◽

Sex Lethal ◽

Female Specific ◽

Genetic Hierarchy

Female sex determination in the germ line of Drosophila melanogaster is regulated by genes functioning in the soma as well as genes that function within the germ line. Genes known or suspected to be involved in germ-line sex determination in Drosophila melanogaster have been examined to determine if they are required upstream or downstream of Sex-lethal+, a known germ-line sex determination gene. Seven genes required for female-specific splicing of germ-line Sex-lethal+ pre-mRNA are identified. These results together with information about the tissues in which these genes function and whether they control sex determination and viability or just sex determination in the germ line have been used to deduce the genetic hierarchy regulating female germ-line sex determination. This hierarchy includes the somatic sex determination genes transformer+, transformer-2+ and doublesex+ (and by inference Sex-lethal+), which control a somatic signal required for female germ-line sex determination, and the germ-line ovarian tumor genes fused+, ovarian tumor+, ovo+, sans fille+, and Sex-lethal+, which are involved in either the reception or interpretation of this somatic sex determination signal. The fused+, ovarian tumor+, ovo+ and sans fille+ genes function upstream of Sex-lethal+ in the germ line.

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Dual role of Ovol2 on the germ cell lineage segregation during gastrulation in mouse embryogenesis

Development ◽

10.1242/dev.200319 ◽

2022 ◽

Author(s):

Yuki Naitou ◽

Go Nagamatsu ◽

Nobuhiko Hamazaki ◽

Kenjiro Shirane ◽

Masafumi Hayashi ◽

...

Keyword(s):

Germ Cells ◽

Splice Variant ◽

Epithelial To Mesenchymal Transition ◽

Functional Relationship ◽

Germ Line ◽

Primordial Germ Cells ◽

Cell Lineage ◽

Animal Kingdom ◽

Mesenchymal Transition

In mammals, primordial germ cells (PGCs), the origin of the germ line, are specified from the epiblast at the posterior region where gastrulation simultaneously occurs, yet the functional relationship between PGC specification and gastrulation remains unclear. Here, we show that Ovol2, a transcription factor conserved across the animal kingdom, balances these major developmental processes by repressing the epithelial-to-mesenchymal transition (EMT) driving gastrulation and the upregulation of genes associated with PGC specification. Ovol2a, a splice variant encoding a repressor domain, directly regulates EMT-related genes and consequently induces re-acquisition of potential pluripotency during PGC specification, whereas Ovol2b, another splice variant missing the repressor domain, directly upregulates genes associated with PGC specification. Taken together, these results elucidate the molecular mechanism underlying allocation of the germ line among epiblast cells differentiating into somatic cells through gastrulation.

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Sex determination in the germ line of Drosophila melanogaster: activation of the gene Sex-lethal

Development ◽

10.1242/dev.118.3.813 ◽

1993 ◽

Vol 118 (3) ◽

pp. 813-816 ◽

Cited By ~ 9

Author(s):

B. Granadino ◽

P. Santamaria ◽

L. Sanchez

Keyword(s):

Drosophila Melanogaster ◽

Germ Cells ◽

Germ Line ◽

Wild Type ◽

Female Development ◽

Pole Cell ◽

Somatic Tissues ◽

Wild Type Female ◽

Sex Lethal ◽

Pole Cell Transplantation

The germ line exhibits sexual dimorphism as do the somatic tissues. Cells with the 2X;2A chromosome constitution will follow the oogenic pathway and X;2A cells will develop into sperm. In both somatic and germ-line tissues, the sexual pathway chosen by the cells depends on the gene Sex-lethal (Sxl), whose function is continuously needed for female development. In the soma, the sex of the cells is autonomously determined by the X:A signal while, in the germ line, the sex is determined by cell autonomous (the X:A signal) and somatic inductive signals. Three X-linked genes have been identified, scute (sc), sisterless-a (sis-a) and runt (run), that determine the initial functional state of Sxl in the soma. Using pole cell transplantation, we have tested whether these genes are also needed to activate Sxl in the germ line. We found that germ cells simultaneously heterozygous for sc, sis-a, run and a deficiency for Sxl transplanted into wild-type female hosts develop into functional oocytes. We conclude that the genes sc, sis-a and run needed to activate Sxl in the soma seem not to be required to activate this gene in the germ line; therefore, the X:A signal would be made up by different genes in somatic and germ-line tissues. The Sxlf7M1/Sxlfc females do not have developed ovaries. We have shown that germ cells of this genotype transplanted into wild-type female hosts produce functional oocytes. We conclude that the somatic component of the gonads in Sxlf7M1/Sxlfc females is affected, and consequently germ cells do not develop.(ABSTRACT TRUNCATED AT 250 WORDS)

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Germ-line sex determination in Drosophila melanogaster

Trends in Genetics ◽

10.1016/0168-9525(90)90208-n ◽

1990 ◽

Vol 6 ◽

pp. 259-263 ◽

Cited By ~ 29

Author(s):

Daniel Pauli ◽

Anthony P. Mahowald

Keyword(s):

Drosophila Melanogaster ◽

Sex Determination ◽

Germ Line

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Sex determination in Drosophila: sis-b, a major numerator element of the X:A ratio in the soma, does not contribute to the X:A ratio in the germ line

Development ◽

10.1242/dev.117.2.763 ◽

1993 ◽

Vol 117 (2) ◽

pp. 763-767 ◽

Cited By ~ 15

Author(s):

M. Steinmann-Zwicky

Keyword(s):

Sex Determination ◽

Germ Cells ◽

Germ Line ◽

Somatic Cells ◽

Present Evidence ◽

Primary Signal ◽

Sex Lethal

In soma and germ cells of Drosophila, the X:A ratio builds a primary signal for sex determination, and in both tissues Sex-lethal (Sxl) function is required for cells to enter the female pathway. In somatic cells of XX animals, the products of X-chromosomal elements of the X:A ratio activate Sxl. Here I show that sisterless-b (sis-b), which is the X-chromosomal element of the somatic X:A ratio that has best been analysed, is not required for oogenesis. I also present evidence that Sxl function might not be sufficient to direct germ cells into the female pathway. These results show that the elements forming the X:A ratio in the germ line are different from the elements forming the X:A ratio in the soma and they suggest that, in the germ line, Sxl might not be regulated by the X:A ratio.

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

Genetics ◽

10.1093/genetics/120.1.159 ◽

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.

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