scholarly journals Two types of pole cells are present in the Drosophila embryo, one with and one without splicing activity for the third P-element intron

Development ◽  
1993 ◽  
Vol 117 (3) ◽  
pp. 885-893 ◽  
Author(s):  
S. Kobayashi ◽  
T. Kitamura ◽  
H. Sasaki ◽  
M. Okada
Keyword(s):  
Germ Cells ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Egg Laying ◽  
P Element ◽  
Drosophila Embryo ◽  
The Third ◽  
Pole Cells ◽  
Almost All ◽  
Second Peak

In Drosophila, it has been postulated that the third intron of the P-element is spliced only in germ-line cells. To test whether this postulate is applicable to pole cells, the progenitor cells of germ line, we carried out a histochemical assay to detect the splicing activity in embryos. The splicing activity was detected in pole cells and primordial germ cells. The activity increased to reach a maximum at 5–6 hours AEL (after egg laying), then decreased to an undetectable level by 8–9 hours AEL. The splicing activity showed a small second peak at 12–15 hours AEL. It was rather unexpected that not all pole cells were capable of splicing the third intron. Almost all pole cells that had the splicing activity at 5–6 hours AEL penetrated the embryonic gonads and differentiated into primordial germ cells. Our findings suggest that pole cells are selected to penetrate the gonads while they are migrating from the proctodeal cavity to the gonads. Furthermore, these results suggest that the machinery to splice the P-element is active in some pole cells, and that this activity is used for processing transcripts of genes that play important roles in the differentiation of pole cells into primordial germ cells.

Distribution of tudor protein in the Drosophila embryo suggests separation of functions based on site of localization

Development ◽  
1993 ◽  
Vol 119 (1) ◽  
pp. 207-219 ◽  
Author(s):  
A. Bardsley ◽  
K. McDonald ◽  
R.E. Boswell
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Germ Plasm ◽  
Primordial Germ Cells ◽  
Posterior Pole ◽  
Drosophila Embryo ◽  
Normal Functioning ◽  
Polar Granules ◽  
Pole Cells

Mutations in the tudor locus of Drosophila affect two distinct determinative processes in embryogenesis; segmentation of the abdomen and determination of the primordial germ cells. The distribution of tudor protein during embryogenesis, and the effect of various mutations on its distribution, suggest that tudor protein may carry out these functions separately, based on its location in the embryo. The protein is concentrated in the posterior pole cytoplasm (germ plasm), where it is found in polar granules and mitochondria. Throughout the rest of the embryo, tudor protein is associated with the cleavage nuclei. Mutations in all maternal genes known to be required for the normal functioning of the germ plasm eliminate the posterior localization of tudor protein, whereas mutations in genes required for the functioning of the abdominal determinant disrupt the localization around nuclei. Analysis of embryos of different maternal genotypes indicates that the average number of pole cells formed is correlated with the amount of tudor protein that accumulates in the germ plasm. Our results suggest that tudor protein localized in the germ plasm is instrumental in germ cell determination, whereas nuclear-associated tudor protein is involved in determination of segmental pattern in the abdomen.

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

Development ◽  
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.

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.

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

Development ◽  
1990 ◽  
Vol 109 (4) ◽  
pp. 911-923 ◽  
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.

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

Development ◽  
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.

Autosomal P[ovoD1] dominant female-sterile insertions in Drosophila and their use in generating germ-line chimeras

Development ◽  
1993 ◽  
Vol 119 (4) ◽  
pp. 1359-1369 ◽  
Author(s):  
T.B. Chou ◽  
E. Noll ◽  
N. Perrimon
Keyword(s):  
Tissue Specificity ◽  
Germ Line ◽  
Egg Laying ◽  
P Element ◽  
Follicle Cells ◽  
Gtpase Activating Protein ◽  
Lethal Mutations ◽  
Sterile Technique ◽  
Dominant Female ◽  
Polarity Determination

The ‘dominant female-sterile’ technique used to generate germ-line mosaics in Drosophila is a powerful tool to determine the tissue specificity (germ line versus somatic) of recessive female-sterile mutations as well as to analyze the maternal effect of recessive zygotic lethal mutations. This technique requires the availability of germ-line-dependent, dominant female-sterile (DFS) mutations that block egg laying but do not affect viability. To date only one X-linked mutation, ovoD1 has been isolated that completely fulfills these criteria. Thus the ‘DFS technique’ has been largely limited to the X-chromosome. To extend this technique to the autosomes, we have cloned the ovoD1 mutation into a P-element vector and recovered fully expressed P[ovoD1] insertions on each autosomal arm. We describe the generation of these P[ovoD1] strains as well as demonstrate their use in generating germ-line chimeras. Specifically, we show that the Gap1 gene, which encodes a Drosophila homologue of mammalian GTPase-activating protein, is required in somatic follicle cells for embryonic dorsoventral polarity determination.

The use of ‘normal’ and ‘transformed’ gynandromorphs in mapping the primordial germ cells and the gonadal mesoderm in Drosophila

Development ◽  
1976 ◽  
Vol 35 (3) ◽  
pp. 607-616
Author(s):  
W. J. Gehring ◽  
E. Wieschaus ◽  
M. Holliger
Keyword(s):  
Germ Cells ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Ventral Side ◽  
Drosophila Embryo ◽  
The Real ◽  
Genital Disc ◽  
Stage Of Development ◽  
Data Support ◽  
Blastoderm Stage

The primordial germ cells and the gonadal mesoderm were mapped in the Drosophila embryo by analyzing the patterns of mosaicism in ‘normal’ and ‘transformed’ gynandromorphs. Relative to the adult cuticular markers the germ cells map as the posterior moststructure, which coincides with their known location in the blastoderm embryo. These data support the hypothesis that the gynandromorph map reflects the real position of the pri-mordia in the embryo. Since after the blastoderm stage the primordial germ cells migrateanteriorly these data also indicate that the map in fact corresponds to the blastoderm stageand not to a later stage of development. The genital disc maps as a single median primordium anterior and ventral to the germ cells, the gonadal mesoderm is located anterior to the genital disc and also forms a single median primordium on the ventral side of the embryo. The primordia for the genital disc and the gonadal mesoderm are unusually large in size, which presumably reflects some indeterminacy of the cell lineage leading to an ‘expansion’ of the map.

Epsilon granules in Drosophila pole cells and oöcytes

Development ◽  
1965 ◽  
Vol 13 (1) ◽  
pp. 73-81
Author(s):  
Suzanne L. Ullmann
Keyword(s):  
Germ Cells ◽  
Microscope Study ◽  
Light Microscope ◽  
Primordial Germ Cells ◽  
Structural Level ◽  
Developmental Morphology ◽  
Insect Eggs ◽  
Polar Granules ◽  
Pole Cells ◽  
Drosophila Embryos

In many insect eggs, including those of the Diptera, deeply staining granules, rich in RNA, occur in the posterior polar plasm and during ontogeny become enclosed within the pole cells. The structure and fate of these cells, which generally give rise to the primordial germ cells, and their inclusions have excited interest for over half a century (Hegner, 1908; Huettner, 1923; Rabinowitz, 1941; Poulson, 1947; Counce, 1963; Mahowald, 1962), yet numerous questions concerning them remain unsettled or controversial to this day. For instance, the dual fate of the pole cells in Drosophila, the genus which has been most extensively studied, is still debated (Poulson & Waterhouse, 1960; Hathaway & Selman, 1961). Recently, Counce (1963), in a light-microscope study, has described the developmental morphology of the polar granules in several species of Drosophila embryos; while Mahowald (1962) has succeeded in identifying them in D. melanogaster at the ultra-structural level.

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