Differential Expression of Conserved Germ Line Markers and Delayed Segregation of Male and Female Primordial Germ Cells in a Hermaphrodite, the Leech Helobdella

In mice, epiblast cells found both the germ-line and somatic lineages in the developing embryo. These epiblast cells carry epigenetic information from both parents that is required for development and cell function in the fetus and during post-natal life. However, germ cells must establish an epigenetic program that supports totipotency and the configuration of parent-specific epigenetic states in the gametes. To achieve this, the epigenetic information inherited by the primordial germ cells at specification is erased and new epigenetic states are established during development of the male and female germ-lines. Errors in this process can lead to transmission of epimutations through the germ-line, which have the potential to affect development and disease in the parent's progeny. This review discusses epigenetic reprogramming in the germ-line and the transmission of epigenetic information to the following generation.

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Faculty Opinions recommendation of The ontogeny of cKIT+ human primordial germ cells proves to be a resource for human germ line reprogramming, imprint erasure and in vitro differentiation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717970350.793468938 ◽

2013 ◽

Author(s):

Kate Loveland

Keyword(s):

Germ Cells ◽

Germ Line ◽

Primordial Germ Cells ◽

In Vitro Differentiation

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Reproductive Isolation and Morphogenetic Evolution in Drosophila Analyzed by Breakage of Ethological Barriers

Genetics ◽

10.1093/genetics/147.1.231 ◽

1997 ◽

Vol 147 (1) ◽

pp. 231-242 ◽

Cited By ~ 1

Author(s):

Lucas Sánchez ◽

Pedro Santamaria

Keyword(s):

Reproductive Isolation ◽

Germ Cells ◽

Morphological Analysis ◽

Seminal Fluid ◽

Germ Line ◽

Regulatory Gene ◽

Motile Sperm ◽

Male And Female ◽

Drosophila Yakuba

Abstract This article reports the breaking of ethological barriers through the constitution of soma-germ line chimeras between species of the melanogaster subgroup of Drosophila, which are ethologically isolated. Female Drosophila yakuba and D. teissieri germ cells in a D. melanogaster ovary produced functional oocytes that, when fertilized by D. melanogaster sperm, gave rise to sterile yakuba-melanogaster andteissieri-melanogaster male and female hybrids. However, the erecta-melanogaster and orena-melanogaster hybrids were lethal, since female D. erecta and D. orena germ cells in a D. melanogaster ovary failed to form oocytes with the capacity to develop normally. This failure appears to be caused by an altered interaction between the melanogaster soma and the erecta and orena germ lines. Germ cells of D. teissieri and D. orena in a D. melanogaster testis produced motile sperm that was not stored in D. melanogaster females. This might be due to incompatibility between the teissieri and orena sperm and the melanogaster seminal fluid. A morphological analysis of the terminalia of yakuba-melanogaster and teissieri-melanogaster hybrids was performed. The effect on the terminalia of teissieri-melanogaster hybrids of a mutation in doublesex, a regulatory gene that controls the development of the terminalia, was also investigated.

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

Development ◽

10.1242/dev.64.1.251 ◽

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.

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Developmental expression of c-kit, a proto-oncogene encoded by the W locus

Development ◽

10.1242/dev.109.4.911 ◽

1990 ◽

Vol 109 (4) ◽

pp. 911-923 ◽

Cited By ~ 16

Author(s):

A. Orr-Urtreger ◽

A. Avivi ◽

Y. Zimmer ◽

D. Givol ◽

Y. Yarden ◽

...

Keyword(s):

Germ Cells ◽

Receptor Tyrosine Kinase ◽

Germ Line ◽

Primordial Germ Cells ◽

Mouse Embryos ◽

Developmental Expression ◽

Male Germ Line ◽

Polypeptide Growth Factors ◽

Adult Ovary

Developmental expression of the c-kit proto-oncogene, a receptor tyrosine kinase encoded by the W locus, was investigated by in situ hybridization in normal mouse embryos. Early after implantation transcripts were detectable only in the maternal placenta (6 1/2-7 1/2 days p.c.). Subsequently (8 1/2 days p.c.) numerous ectodermal (neural tube, sensory placodes) and endodermal (embryonic gut) derivatives expressed c-kit. Later transcripts were detected also in the blood islands of the yolk sac and in the embryonic liver, the main sites of embryonic hemopoiesis. Around midgestation, transcripts accumulated in the branchial pouches and also in primordial germ cells of the genital ridges. This complex pattern of expression remained characteristic also later in gestation, when c-kit was expressed in highly differentiated structures of the craniofacial area, in presumptive melanoblasts and in the CNS. In the adult ovary, maternal c-kit transcripts were detected. They were present in the oocytes of both immature and mature ovarian follicles, but not in the male germ line, where c-kit expression may be down regulated. Thus, c-kit activity is complex and appears in multiple tissues including those that also display defects in mutations at the W locus where c-kit is encoded. Correlation between W phenotypes and c-kit expression, as well as the regulation of the complex and multiple expression of polypeptide growth factors and receptors, is discussed.

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The positional effect of presumptive primordial germ cells (pPGCs) on their differentiation into PGCs in Xenopus

Development ◽

10.1242/dev.102.3.527 ◽

1988 ◽

Vol 102 (3) ◽

pp. 527-535

Author(s):

K. Ikenishi ◽

Y. Tsuzaki

Keyword(s):

Germ Cells ◽

Germ Plasm ◽

Germ Line ◽

Anterior Part ◽

Primordial Germ Cells ◽

Positional Effect ◽

In Series

To determine whether the location of ‘germ plasm’-bearing cells [presumptive primordial germ cells (pPGCs)] is crucial for their differentiation into PGCs in Xenopus, [3H]thymidine-labelled pPGCs were implanted into the anterior or posterior halves of the endoderm in unlabelled host neurulae. Labelled PGCs in the genital ridges of experimental tadpoles were investigated by autoradiography. When the labelled pPGCs were implanted into posterior halves of the endoderm where host pPGCs are situated, 65 and 77% of the experimental tadpoles (designated as p-tadpoles) had the labelled PGCs in series I and II, respectively. When implanted into the anterior halves, 20 and 27% of the experimental tadpoles (a- tadpoles) had the labelled PGCs in series I and II, respectively. In p-tadpoles, the average numbers of labelled PGCs per tadpole were 8á7 in series I and 10 in series II, whereas they were 2á0 in a-tadpoles of both series. Both the proportion and the average number in p-tadpoles of both series were significantly different from those in a-tadpoles. In both series, labelled PGCs in p-tadpoles were found to be distributed throughout the genital ridges while those in a-tadpoles were localized only in the anterior part of the ridges. These facts indicate that the location of pPGCs in the endoderm affects their successful migration into the genital ridges, and that not only the presence of the germ plasm but also the proper location in endoderm are prerequisites to PGC differentiation of the germ line cells.

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