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

Genetics ◽  
1990 ◽  
Vol 125 (3) ◽  
pp. 535-550 ◽  
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.

Sex determination in the germ line of Drosophila depends on genetic signals and inductive somatic factors

Development ◽  
1989 ◽  
Vol 107 (3) ◽  
pp. 505-518 ◽  
Author(s):  
R. Nothiger ◽  
M. Jonglez ◽  
M. Leuthold ◽  
P. Meier-Gerschwiler ◽  
T. Weber
Keyword(s):  
Sex Determination ◽  
Germ Cells ◽  
Germ Line ◽  
The State ◽  
Loss Of Function ◽  
X Chromosomes ◽  
Constitutive Mutation ◽  
Sex Lethal ◽  
Double Sex ◽  
State Of Activity

We have analyzed the mechanism of sex determination in the germ line of Drosophila by manipulating three parameters: (1) the ratio of X-chromosomes to sets of autosomes (X:A); (2) the state of activity of the gene Sex-lethal (Sxl), and (3) the sex of the gonadal soma. To this end, animals with a ratio of 2X:2A and 2X:3A were sexually transformed into pseudomales by mutations at the sex-determining genes Sxl (Sex-lethal), tra (transformer), tra-2 (transformer-2), or dsx (double-sex). Animals with the karyotype 2X;3A were also transformed into pseudofemales by the constitutive mutation SxlM1. The sexual phenotype of the gonads and of the germ cells was assessed by phase-contrast microscopy. Confirming the conclusions of Steinmann-Zwicky et al. (Cell 57, 157, 1989), we found that all three parameters affect sex determination in germ cells. In contrast to the soma in which sex determination is completely cell-autonomous, sex determination in the germ line has a non-autonomous component inasmuch as the sex of the soma can influence the sexual pathway of the germ cells. Somatic induction has a clear effect on 2X;2A germ cells that carry a Sxl+ allele. These cells, which form eggs in an ovary, can enter spermatogenesis in testes. Mutations that cause partial loss of function or gain of function of Sxl thwart somatic induction and, independently of the sex of the soma, dictate spermatogenesis or oogenesis, respectively. Somatic induction has a much weaker effect on 2X;3A germ cells. This ratio is essentially a male signal for germ cells which consistently enter spermatogenesis in testes, even when they carry SxlM1. In a female soma, however, SxlM1 enables the 2X;3A germ cells to form almost normal eggs. Our results show that sex determination in the germ line is more complex than in the soma. They provide further evidence that the state of Sxl, the key gene for sex determination and dosage compensation in the soma, also determines the sex of the germ cells, and that, in the germ line, the state of activity of Sxl is regulated not only by the X:A ratio, but also by somatic inductive stimuli.

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

Development ◽  
1993 ◽  
Vol 118 (3) ◽  
pp. 813-816 ◽  
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)

scholarly journals 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 ◽  
1993 ◽  
Vol 117 (2) ◽  
pp. 763-767 ◽  
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.

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 The mog-1 gene is required for the switch from spermatogenesis to oogenesis in Caenorhabditis elegans.

Genetics ◽  
1993 ◽  
Vol 133 (4) ◽  
pp. 919-931 ◽  
Author(s):  
P L Graham ◽  
J Kimble
Keyword(s):  
Caenorhabditis Elegans ◽  
Sex Determination ◽  
Germ Cells ◽  
Germ Line ◽  
Loss Of Function ◽  
Wild Type ◽  
Per Se ◽  
Post Transcriptional Regulation ◽  
Germline Sex Determination ◽  
Embryonic Death

Abstract Caenorhabditis elegans hermaphrodites make first sperm, then oocytes. By contrast, animals homozygous for any of six loss-of-function mutations in the gene mog-1 (for masculinization of the germ line) make sperm continuously and do not switch into oogenesis. Therefore, in mog-1 mutants, germ cells that normally would become oocytes are transformed into sperm. By contrast, somatic sexual fates are normal, suggesting that mog-1 plays a germ line-specific role in sex determination. Analyses of double mutants suggest that mog-1 negatively regulates the fem genes and/or fog-1: mog-1; fem and mog-1; fog-1 double mutants all make oocytes rather than sperm. Therefore, we propose that wild-type mog-1 is required in the hermaphrodite germ line for regulation of the switch from spermatogenesis to oogenesis rather than for specification of oogenesis per se. In addition to its role in germline sex determination, maternal mog-1 is required for embryogenesis: most progeny of a mog-1; fem or mog-1; fog-1 mother die as embryos. How might the roles of mog-1 in the sperm/oocyte switch and embryogenesis be linked? Previous work showed that fem-3 is regulated post-transcriptionally to achieve the sperm/oocyte switch. We speculate that mog-1 may function in the post-transcriptional regulation of numerous germ-line RNAs, including fem-3. A loss of mog-1 might inappropriately activate fem-3 and thereby abolish the sperm/oocyte switch; its loss might also lead to misregulation of maternal RNAs and thus embryonic death.

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

Development ◽  
1993 ◽  
Vol 119 (3) ◽  
pp. 897-908 ◽  
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.

Sex Determination Signals Control ovo-B Transcription in Drosophila melanogaster Germ Cells

Genetics ◽  
2002 ◽  
Vol 160 (2) ◽  
pp. 537-545
Author(s):  
Justen Andrews ◽  
Brian Oliver
Keyword(s):  
Transcription Factor ◽  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Sex Determination ◽  
Sexual Identity ◽  
Germ Cells ◽  
Female Germline ◽  
Chromosome Karyotype ◽  
Inductive Signals

Abstract Nonautonomous inductive signals from the soma and autonomous signals due to a 2X karyotype determine the sex of Drosophila melanogaster germ cells. These two signals have partially overlapping influences on downstream sex determination genes. The upstream OVO-B transcription factor is required for the viability of 2X germ cells, regardless of sexual identity, and for female germline sexual identity. The influence of inductive and autonomous signals on ovo expression has been controversial. We show that ovo-B is strongly expressed in the 2X germ cells in either a male or a female soma. This indicates that a 2X karyotype controls ovo-B expression in the absence of inductive signals from the female soma. However, we also show that female inductive signals positively regulate ovo-B transcription in the 1X germ cells that do not require ovo-B function. Genetic analysis clearly indicates that inductive signals from the soma are not required for ovo-B function in 2X germ cells. Thus, while somatic inductive signals and chromosome karyotype have overlapping regulatory influences, a 2X karyotype is a critical germline autonomous determinant of ovo-B function in the germline.

Identification of regions interacting with ovoD mutations: potential new genes involved in germline sex determination or differentiation in Drosophila melanogaster.

Genetics ◽  
1995 ◽  
Vol 139 (2) ◽  
pp. 713-732 ◽  
Author(s):  
D Pauli ◽  
B Oliver ◽  
A P Mahowald
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Determination ◽  
Sexual Identity ◽  
Ovarian Tumor ◽  
Biological Process ◽  
Genetic Interactions ◽  
New Genes ◽  
Sex Lethal ◽  
Germline Sex Determination

Abstract Only a few Drosophila melanogaster germline sex determination genes are known, and there have been no systematic screens to identify new genes involved in this important biological process. The ovarian phenotypes produced by females mutant for dominant alleles of the ovo gene are modified in flies with altered doses of other loci involved in germline sex determination in Drosophila (Sex-lethal+, sans fille+ and ovarian tumor+). This observation constitutes the basis for a screen to identify additional genes required for proper establishment of germline sexual identity. We tested 300 deletions, which together cover approximately 58% of the euchromatic portion of the genome, for genetic interactions with ovoD. Hemizygosity for more than a dozen small regions show interactions that either partially suppress or enhance the ovarian phenotypes of females mutant for one or more of the three dominant ovo mutations. These regions probably contain genes whose products act in developmental hierarchies that include ovo+ protein.

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

Development ◽  
1993 ◽  
Vol 119 (1) ◽  
pp. 123-134 ◽  
Author(s):  
D. Pauli ◽  
B. Oliver ◽  
A.P. Mahowald
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Determination ◽  
Germ Cells ◽  
Ovarian Tumor ◽  
Germ Line ◽  
Gene Dosage ◽  
Constitutive Expression ◽  
Regulatory Cascade

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.

scholarly journals glp-3 Is Required for Mitosis and Meiosis in the Caenorhabditis elegans Germ Line

Genetics ◽  
1997 ◽  
Vol 145 (1) ◽  
pp. 111-121 ◽  
Author(s):  
Lisa C Kadyk ◽  
Eric J Lambie ◽  
Judith Kimble
Keyword(s):  
Caenorhabditis Elegans ◽  
Germ Cells ◽  
Germ Line ◽  
Stem Cell Population ◽  
Phenotypic Characterization ◽  
Loss Of Function ◽  
Dapi Staining ◽  
Cell Cycles ◽  
C Elegans ◽  
Mitosis And Meiosis

The germ line is the only tissue in Caenorhabditis elegans in which a stem cell population continues to divide mitotically throughout life; hence the cell cycles of the germ line and the soma are regulated differently. Here we report the genetic and phenotypic characterization of the glp-3 gene. In animals homozygous for each of five recessive loss-of-function alleles, germ cells in both hermaphrodites and males fail to progress through mitosis and meiosis, but somatic cells appear to divide normally. Germ cells in animals grown at 15° appear by DAPI staining to be uniformly arrested at the G2/M transition with <20 germ cells per gonad on average, suggesting a checkpoint-mediated arrest. In contrast, germ cells in mutant animals grown at 25° frequently proliferate slowly during adulthood, eventually forming small germ lines with several hundred germ cells. Nevertheless, cells in these small germ lines never undergo meiosis. Double mutant analysis with mutations in other genes affecting germ cell proliferation supports the idea that glp-3 may encode a gene product that is required for the mitotic and meiotic cell cycles in the C. elegans germ line.

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