scholarly journals Sex determination of the Drosophila germ line: tra and dsx control somatic inductive signals

Development ◽  
1994 ◽  
Vol 120 (3) ◽  
pp. 707-716 ◽  
Author(s):  
M. Steinmann-Zwicky
Keyword(s):  
Germ Cells ◽  
Germ Line ◽  
Somatic Cells ◽  
X Chromosomes ◽  
Specific Product ◽  
Female Host ◽  
Female Specific ◽  
Male Specific ◽  
Inductive Signals

In Drosophila, the sex of germ cells is determined by cell-autonomous and inductive signals. XY germ cells autonomously enter spermatogenesis when developing in a female host. In contrast, XX germ cells non-autonomously become spermatogenic when developing in a male host. In first instar larvae with two X chromosomes, XX germ cells enter the female or the male pathway depending on the presence or absence of transformer (tra) activity in the surrounding soma. In somatic cells, the product of tra regulates the expression of the gene double sex (dsx) which can form a male-specific or a female-specific product. In dsx mutant larvae, XX and XY germ cells develop abnormally, with a seemingly intersexual phenotype. This indicates that female-specific somatic dsx products feminize XX germ cells, and male-specific somatic dsx products masculinize XX and XY germ cells. The results show that tra and dsx control early inductive signals that determine the sex of XX germ cells and that somatic signals also affect the development of XY germ cells. XX germ cells that develop in pseudomales lacking the sex-determining function of Sxl are spermatogenic. If, however, female-specific tra functions are expressed in these animals, XX germ cells become oogenic. Furthermore, transplanted XX germ cells can become oogenic and form eggs in XY animals that express the female-specific function of tra. Therefore, TRA product present in somatic cells of XY animals or in animals lacking the sex-determining function of Sxl, is sufficient to support developing XX germ cells through oogenesis.

scholarly journals Absence of X-chromosome dosage compensation in the primordial germ cells of Drosophila embryos

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryoma Ota ◽  
Makoto Hayashi ◽  
Shumpei Morita ◽  
Hiroki Miura ◽  
Satoru Kobayashi
Keyword(s):  
X Chromosome ◽  
Germ Cells ◽  
Dosage Compensation ◽  
Sex Chromosome ◽  
Primordial Germ Cells ◽  
Histone H4 ◽  
X Chromosomes ◽  
Essential Components ◽  
Msl Complex ◽  
Male Specific

AbstractDosage compensation is a mechanism that equalizes sex chromosome gene expression between the sexes. In Drosophila, individuals with two X chromosomes (XX) become female, whereas males have one X chromosome (XY). In males, dosage compensation of the X chromosome in the soma is achieved by five proteins and two non-coding RNAs, which assemble into the male-specific lethal (MSL) complex to upregulate X-linked genes twofold. By contrast, it remains unclear whether dosage compensation occurs in the germline. To address this issue, we performed transcriptome analysis of male and female primordial germ cells (PGCs). We found that the expression levels of X-linked genes were approximately twofold higher in female PGCs than in male PGCs. Acetylation of lysine residue 16 on histone H4 (H4K16ac), which is catalyzed by the MSL complex, was undetectable in these cells. In male PGCs, hyperactivation of X-linked genes and H4K16ac were induced by overexpression of the essential components of the MSL complex, which were expressed at very low levels in PGCs. Together, these findings indicate that failure of MSL complex formation results in the absence of X-chromosome dosage compensation in male PGCs.

Random X-chromosome inactivation in female primordial germ cells in the mouse

Development ◽  
1981 ◽  
Vol 64 (1) ◽  
pp. 251-258
Author(s):  
Andy McMahon ◽  
Mandy Fosten ◽  
Marilyn Monk
Keyword(s):  
X Chromosome ◽  
Germ Cells ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Phosphoglycerate Kinase ◽  
X Chromosome Inactivation ◽  
Yolk Sac ◽  
Chromosome Inactivation ◽  
X Chromosomes

The pattern of expression of the two X chromosomes was investigated in pre-meiotic germ cells from 12½-day-old female embryos heterozygous for the variant electrophoretic forms of the X-linked enzyme phosphoglycerate kinase (PGK-1). If such germ cells carry the preferentially active Searle's translocated X chromosome (Lyon, Searle, Ford & Ohno, 1964), then only the Pgk-1 allele on this chromosome is expressed. This confirms Johnston's evidence (1979,1981) that Pgk-1 expression reflects a single active X chromosome at this time. Extracts of 12½-day germ cells from heterozygous females carrying two normal X chromosomes show both the A and the B forms of PGK; since only one X chromosome in each cell is active, different alleles must be expressed in different cells, suggesting that X-chromosome inactivation is normally random in the germ line. This result makes it unlikely that germ cells are derived from the yolk-sac endoderm where the paternally derived X chromosome is preferentially inactivated. In their pattern of X-chromosome inactivation, germ cells evidently resemble other tissues derived from the epiblast.

scholarly journals Periodic production of retinoic acid by meiotic and somatic cells coordinates four transitions in mouse spermatogenesis

2017 ◽  
Vol 114 (47) ◽  
pp. E10132-E10141 ◽  
Author(s):  
Tsutomu Endo ◽  
Elizaveta Freinkman ◽  
Dirk G. de Rooij ◽  
David C. Page
Keyword(s):  
Retinoic Acid ◽  
Germ Cells ◽  
Germ Line ◽  
Expression Patterns ◽  
Somatic Cells ◽  
Differentiation Process ◽  
Adult Males ◽  
Pachytene Spermatocytes ◽  
Meiotic Initiation ◽  
Spatiotemporal Coordination

Mammalian spermatogenesis is an elaborately organized differentiation process, starting with diploid spermatogonia, which include germ-line stem cells, and ending with haploid spermatozoa. The process involves four pivotal transitions occurring in physical proximity: spermatogonial differentiation, meiotic initiation, initiation of spermatid elongation, and release of spermatozoa. We report how the four transitions are coordinated in mice. Two premeiotic transitions, spermatogonial differentiation and meiotic initiation, were known to be coregulated by an extrinsic signal, retinoic acid (RA). Our chemical manipulations of RA levels in mouse testes now reveal that RA also regulates the two postmeiotic transitions: initiation of spermatid elongation and spermatozoa release. We measured RA concentrations and found that they changed periodically, as also reflected in the expression patterns of an RA-responsive gene, STRA8; RA levels were low before the four transitions, increased when the transitions occurred, and remained elevated thereafter. We found that pachytene spermatocytes, which express an RA-synthesizing enzyme, Aldh1a2, contribute directly and significantly to RA production in testes. Indeed, chemical and genetic depletion of pachytene spermatocytes revealed that RA from pachytene spermatocytes was required for the two postmeiotic transitions, but not for the two premeiotic transitions. We conclude that the premeiotic transitions are coordinated by RA from Sertoli (somatic) cells. Once germ cells enter meiosis, pachytene spermatocytes produce RA to coordinate the two postmeiotic transitions. In combination, these elements underpin the spatiotemporal coordination of spermatogenesis and ensure its prodigious output in adult males.

scholarly journals Ruth Lehmann: Germ cells do things differently

2011 ◽  
Vol 194 (5) ◽  
pp. 660-661
Author(s):  
Caitlin Sedwick
Keyword(s):  
Germ Cells ◽  
Germ Line ◽  
Somatic Cells ◽  
Developmental Program

Lehmann studies the developmental program that sets the germ line apart from somatic cells.

scholarly journals Multicellularity makes somatic differentiation evolutionarily stable

2016 ◽  
Vol 113 (30) ◽  
pp. 8362-8367 ◽  
Author(s):  
Mary E. Wahl ◽  
Andrew W. Murray
Keyword(s):  
Germ Cells ◽  
Germ Line ◽  
Somatic Cells ◽  
Potential Benefits ◽  
Fitness Benefits ◽  
Reproductive Division Of Labor ◽  
Multicellular Organisms ◽  
Reproductive Division ◽  
Evolutionarily Stable

Many multicellular organisms produce two cell lineages: germ cells, whose descendants produce the next generation, and somatic cells, which support, protect, and disperse the germ cells. This germ-soma demarcation has evolved independently in dozens of multicellular taxa but is absent in unicellular species. A common explanation holds that in these organisms, inefficient intercellular nutrient exchange compels the fitness cost of producing nonreproductive somatic cells to outweigh any potential benefits. We propose instead that the absence of unicellular, soma-producing populations reflects their susceptibility to invasion by nondifferentiating mutants that ultimately eradicate the soma-producing lineage. We argue that multicellularity can prevent the victory of such mutants by giving germ cells preferential access to the benefits conferred by somatic cells. The absence of natural unicellular, soma-producing species previously prevented these hypotheses from being directly tested in vivo: to overcome this obstacle, we engineered strains of the budding yeast Saccharomyces cerevisiae that differ only in the presence or absence of multicellularity and somatic differentiation, permitting direct comparisons between organisms with different lifestyles. Our strains implement the essential features of irreversible conversion from germ line to soma, reproductive division of labor, and clonal multicellularity while maintaining sufficient generality to permit broad extension of our conclusions. Our somatic cells can provide fitness benefits that exceed the reproductive costs of their production, even in unicellular strains. We find that nondifferentiating mutants overtake unicellular populations but are outcompeted by multicellular, soma-producing strains, suggesting that multicellularity confers evolutionary stability to somatic differentiation.

scholarly journals Transgenic and knockout analyses of Masculinizer and doublesex illuminated the unique functions of doublesex in germ cell sexual development of the silkworm, Bombyx mori

2020 ◽  
Author(s):  
Tomohisa Yuzawa ◽  
Misato Matsuoka ◽  
Megumi Sumitani ◽  
Fugaku Aoki ◽  
Hideki Sezutsu ◽  
...  
Keyword(s):  
Germ Cell ◽  
Bombyx Mori ◽  
Germ Cells ◽  
Sexual Development ◽  
Somatic Cells ◽  
Specific Factor ◽  
Physical Interaction ◽  
Homozygous Mutation ◽  
Male Specific ◽  
Silkworm Bombyx Mori

Abstract Background: Masculinizer (Masc) plays a pivotal role in male sex determination in the silkworm, Bombyx mori. Masc is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. The male isoform of Bmdsx (BmdsxM) induces male differentiation in somatic cells, while females express the female isoform of Bmdsx (BmdsxF), which promotes female differentiation in somatic cells. Our previous findings suggest that Masc could direct the differentiation of genetically female (ZW) germ cells into sperms. However, it remains unclear whether Masc directly induces spermatogenesis of if it promotes male differentiation in germ cells indirectly by inducing the expression of BmdsxM. Results: In this study, we performed genetic analyses using a transgenic line that expressed Masc, as well as various Bmdsx knockout lines. Masc-expressing females express both BmdsxF and BmdsxM and have degenerated ovaries combined with testis-like tissues, which produce sperm. We found that Masc-expressing females with a homozygous mutation in BmdsxM showed normal development in ovaries. The formation of testis-like tissues was abolished in these females. In comparison, Masc-expressing females carrying a homozygous mutation in BmdsxF exhibited almost complete male-specific development in gonads and germ cells. These results suggest that BmdsxM can induce male development in germ cells and internal genital organs, while BmdsxF inhibits BmdsxM activity and represses male differentiation. To investigate whether MASC directly controls male-specific splicing of Bmdsx and identify RNAs that form complexes with MASC in testes, we performed RNA immunoprecipitation (RIP) using an anti-MASC antibody. We found that MASC formed a complex with AS1 lncRNA , which is a testis-specific factor involved in the male-specific splicing of Bmdsx pre-mRNA . Conclusions: Taken together, our findings suggest that Masc induces male differentiation in gonads and germ cells by enhancing the production of BmdsxM. Physical interaction between MASC and AS1 lncRNA may be important for the BmdsxM expression in the testis. Unlike Drosophila dsx, BmdsxM was able to induce spermatogenesis in genetically female (ZW) germ cells. To the best of our knowledge, this is the first report that the role of dsx in germ cell sexual development is different between insect species.

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.

scholarly journals Transgenic and knockout analyses of Masculinizer and doublesex illuminated the unique functions of doublesex in germ cell sexual development of the silkworm, Bombyx mori

2020 ◽  
Author(s):  
Tomohisa Yuzawa ◽  
Misato Matsuoka ◽  
Megumi Sumitani ◽  
Fugaku Aoki ◽  
Hideki Sezutsu ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Sexual Development ◽  
Somatic Cells ◽  
Specific Factor ◽  
Physical Interaction ◽  
Homozygous Mutation ◽  
Rna Immunoprecipitation ◽  
Male Specific

Abstract Background: Masculinizer (Masc) plays a pivotal role in male sex determination in the silkworm, Bombyx mori. Masc is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. The male isoform of Bmdsx (BmdsxM) induces male differentiation in somatic cells, while females express the female isoform of Bmdsx (BmdsxF), which promotes female differentiation in somatic cells. Our previous findings suggest that Masc could direct the differentiation of genetically female (ZW) germ cells into sperms. However, it remains unclear whether Masc directly induces spermatogenesis or if it promotes male differentiation in germ cells indirectly by inducing the expression of BmdsxM. Results: In this study, we performed genetic analyses using the transgenic line that expressed Masc, as well as various Bmdsx knockout lines. We found that Masc-expressing females with a homozygous mutation in BmdsxM showed normal development in ovaries. The formation of testis-like tissues was abolished in these females. On the other hand, Masc-expressing females carrying a homozygous mutation in BmdsxF exhibited almost complete male-specific development in gonads and germ cells. These results suggest that BmdsxM has an ability to induce male development in germ cells as well as internal genital organs, while BmdsxF inhibits BmdsxM activity and represses male differentiation. To investigate whether MASC directly controls male-specific splicing of Bmdsx and identify RNAs that form complexes with MASC in testes, we performed RNA immunoprecipitation (RIP) using an anti-MASC antibody. We found that MASC formed a complex with AS1 lncRNA, which is a testis-specific factor involved in the male-specific splicing of Bmdsx pre-mRNA. Conclusions: Taken together, our findings suggest that Masc induces male differentiation in germ cells by enhancing the production of BmdsxM. Physical interaction between MASC and AS1 lncRNA may be important for the BmdsxM expression in the testis. Unlike in the Drosophila dsx, BmdsxM was able to induce spermatogenesis in genetically female (ZW) germ cells. To the best of our knowledge, this is the first report that the role of dsx in germ cell sexual development is different between insect species.

Genetic activity of sex chromosomes in somatic cells of mammals

1970 ◽  
Vol 259 (828) ◽  
pp. 41-52 ◽  
Keyword(s):  
X Chromosome ◽  
Germ Cells ◽  
Chromosome Region ◽  
Somatic Cells ◽  
X Inactivation ◽  
X Chromosomes ◽  
Animal Group ◽  
Inactive X Chromosome ◽  
Genetic Activity ◽  
Partial Inactivation

Mammals are thought to have a type of dosage compensation not so far known in any other animal group: however many X chromosomes are present, only one remains genetically active in somatic cells. Considerable evidence for this idea exists, in spite of criticism; the greatest difficulty is presented by the abnormalities in human individuals with X chromosome aberrations. Possible explanations for these abnormalities include: wrong X chromosome dosage in early development before X inactivation, reversal of inactivation, partial inactivation of both X chromosomes, activity of the X while in the condensed inactive state, and the presence of a homologous non-inactivated region of the human X and Y. In female germ cells X inactivation apparently does not occur, but the situation in male germ cells is less clear. The Y chromosome is probably also inactive in somatic cells of adults, but again its function in germ cells is not yet clear. Some species have a presumed doubly inactive X chromosome region, as well as the singly active one. The origins and functions of this region are unknown; it may have a role in female germ cells.

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.

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