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.

Experimental studies on the role of ‘polar granules’ in the segregation of pole cells in Drosophila melanogaster

Development ◽  
1966 ◽  
Vol 16 (3) ◽  
pp. 391-399
Author(s):  
Bożenna Jazdowska-Zagrodzińska
Keyword(s):  
Germ Cells ◽  
Normal Development ◽  
Primordial Germ Cells ◽  
Experimental Studies ◽  
Main Body ◽  
Track Formation ◽  
Polar Granules ◽  
Pole Cells ◽  
Pole Plasm

The early differentiation of germ cells is a common phenomenon in the animal kingdom. Insects are of special interest in this respect, as the differentiation of their primordial germ cells occurs in very early stages of cleavage (Kahle, 1908; Hegner, 1914; Reitberger, 1934; Kraczkiewicz, 1935, 1936) and the structure of the ooplasm enables relatively convenient observation of the phenomenon of germ track formation. The ooplasm is differentiated in that the posterior end of the egg contains the so-called ‘pole plasm’ in which there are easily visible inclusions quite different from yolk, though staining similarly with haematoxylin. Such inclusions are not noted in other parts of the egg. In the course of normal development the region containing granules and pole plasm always detaches, producing the primordial germ cells. During the separation of the primordial germ cells, also called pole cells, all these granules become included in their cytoplasm, and the main body of ooplasm is left devoid of them.

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.

scholarly journals A truncated form of a transcription factor Mamo activates vasa in Drosophila embryos

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Shoichi Nakamura ◽  
Seiji Hira ◽  
Masato Fujiwara ◽  
Nasa Miyagata ◽  
Takuma Tsuji ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Transcriptional Activator ◽  
Transcriptional Regulators ◽  
Truncated Form ◽  
Germline Development ◽  
Finger Protein ◽  
Biochemical Studies ◽  
Drosophila Embryos

AbstractExpression of the vasa gene is associated with germline establishment. Therefore, identification of vasa activator(s) should provide insights into germline development. However, the genes sufficient for vasa activation remain unknown. Previously, we showed that the BTB/POZ-Zn-finger protein Mamo is necessary for vasa expression in Drosophila. Here, we show that the truncated Mamo lacking the BTB/POZ domain (MamoAF) is a potent vasa activator. Overexpression of MamoAF was sufficient to induce vasa expression in both primordial germ cells and brain. Indeed, Mamo mRNA encoding a truncated Mamo isoform, which is similar to MamoAF, was predominantly expressed in primordial germ cells. The results of our genetic and biochemical studies showed that MamoAF, together with CBP, epigenetically activates vasa expression. Furthermore, MamoAF and the germline transcriptional activator OvoB exhibited synergy in activating vasa transcription. We propose that a Mamo-mediated network of epigenetic and transcriptional regulators activates vasa expression.

scholarly journals Maternal Nanos represses hid/skl-dependent apoptosis to maintain the germ line in Drosophila embryos

2007 ◽  
Vol 104 (18) ◽  
pp. 7455-7460 ◽  
Author(s):  
Kimihiro Sato ◽  
Yoshiki Hayashi ◽  
Yuichi Ninomiya ◽  
Shuji Shigenobu ◽  
Kayo Arita ◽  
...  
Keyword(s):  
Germ Line ◽  
Primordial Germ Cells ◽  
Critical Event ◽  
Caspase Activation ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Evolutionarily Conserved ◽  
Regulated Expression ◽  
Pole Cells ◽  
Drosophila Embryos

Nanos (Nos) is an evolutionarily conserved protein essential for the survival of primordial germ cells. In Drosophila, maternal Nos partitions into pole cells and suppresses apoptosis to permit proper germ-line development. However, how this critical event is regulated by Nos has remained elusive. Here, we report that Nos represses apoptosis of pole cells by suppressing translation of head involution defective (hid), a member of the RHG gene family that is required for Caspase activation. In addition, we demonstrate that hid acts in concert with another RHG gene, sickle (skl), to induce apoptosis. Expression of skl is induced in pole cells by maternal tao-1, a ste20-like serine/threonine kinase. Tao-1-dependent skl expression is required to potentiate hid activity. However, skl expression is largely suppressed in normal pole cells. Once the pole cells lack maternal Nos, Tao-1-dependent skl expression is fully activated, suggesting that skl expression is also restricted by Nos. These findings provide the first evidence that the germ line is maintained through the regulated expression of RHG genes.

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.

Experiments on chromosome elimination in the gall midge, Mayetiola destructor

Development ◽  
1970 ◽  
Vol 24 (2) ◽  
pp. 257-286
Author(s):  
C. R. Bantock
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Germ Line ◽  
Gall Midge ◽  
Primordial Germ Cells ◽  
Chromosome Complement ◽  
Chromosome Elimination ◽  
Mayetiola Destructor ◽  
Cell Nuclei ◽  
Polar Granules

Cleavage in Cecidomyidae (Diptera) is characterized by the elimination of chromosomes from presumptive somatic nuclei. The full chromosome complement is kept by the germ-line nuclei. The course of cleavage in Mayetiola destructor (Say) is described. After the fourth division two nuclei lie in the posterior polar-plasm and become associated with polar granules, and fourteen nuclei lie in the rest of the cytoplasm. All the nuclei possess about forty chromosomes. During the fifth division the posterior nuclei do not divide and the polar-plasm becomes constricted to form primordial germ cells (pole cells). The remaining fourteen nuclei divide and lose about thirty-two chromosomes so that twenty-eight nuclei are formed containing only eight chromosomes. These are the presumptive somatic nuclei. During subsequent divisions the pole cell nuclei retain the full chromosome number; these divisions occur less frequently than those of the somatic nuclei. Experiments were performed on early embryonic stages to elucidate the properties of the posterior end during the time that chromosome elimination was taking place from the presumptive somatic nuclei. Ultraviolet irradiation, constriction, and centrifugation techniques were used. The polar granules are concerned with the non-division of the germ-cell nuclei during the fifth division, since if the granules are dispersed by centrifugation, or if nuclei are prevented by constriction from coming into contact with them before the fifth division, all the nuclei divide with chromosome elimination at this division. With each technique it is possible to obtain embryos possessing germ cells with only eight chromosomes in their nuclei. Individuals possessing germ-line nuclei with only eight chromosomes were allowed to develop to maturity. Abnormalities were confined to the germ cells only and were the same regardless of which technique had been used to produce the deficient germ line. An ovary containing germ-cell nuclei with only eight chromosomes is unable to form both oocytes and nurse cells. A testis containing germ-cell nuclei with only eight chromosomes is unable to form spermatocytes but cells which come to resemble gametes are formed. Experimental males and females are both sterile. The results are discussed in relation to other experimental work on Cecidomyidae and the following main conclusions are reached: (a) the polar granules are responsible for preventing an irreversible loss of chromosomes from the germ-cell nuclei by preventing the mitosis of these nuclei during the fifth division; (b) the chromosomes normally retained in the germ line are required for gametogenesis, particularly for oogenesis. The significance of chromosome elimination is discussed.

A SEM and Light Microscope Study of the Epidermal Leaf Structures of the Carnivorous Plant, Sarracenia purpurea, L.

1971 ◽  
Vol 29 ◽  
pp. 358-359
Author(s):  
B. J. Panessa ◽  
J. F. Gennaro
Keyword(s):  
Methylene Blue ◽  
Toluidine Blue ◽  
Outer Surface ◽  
Microscope Study ◽  
Light Microscope ◽  
Carnivorous Plant ◽  
Sarracenia Purpurea ◽  
Inner Surface

Tissue from the hood and sarcophagus regions were fixed in 6% glutaraldehyde in 1 M.cacodylate buffer and washed in buffer. Tissue for SEM was partially dried, attached to aluminium targets with silver conducting paint, carbon-gold coated(100-500Å), and examined in a Kent Cambridge Stereoscan S4. Tissue for the light microscope was post fixed in 1% aqueous OsO4, dehydrated in acetone (4°C), embedded in Epon 812 and sectioned at ½u on a Sorvall MT 2 ultramicrotome. Cross and longitudinal sections were cut and stained with PAS, 0.5% toluidine blue and 1% azure II-methylene blue. Measurements were made from both SEM and Light micrographs.The tissue had two structurally distinct surfaces, an outer surface with small (225-500 µ) pubescent hairs (12/mm2), numerous stoma (77/mm2), and nectar glands(8/mm2); and an inner surface with large (784-1000 µ)stiff hairs(4/mm2), fewer stoma (46/mm2) and larger, more complex glands(16/mm2), presumably of a digestive nature.

Hexachlorobenzene toxicity in the rat ovary: II. Ultrastructure induced by medium (10 mg/kg) dose exposure

1992 ◽  
Vol 50 (1) ◽  
pp. 668-669
Author(s):  
Amreek Singh ◽  
Warren G. Foster ◽  
Anna Dykeman ◽  
David C. Villeneuve
Keyword(s):  
Germ Cells ◽  
Primordial Germ Cells ◽  
Surface Epithelium ◽  
Morphological Parameters ◽  
Comprehensive Investigation ◽  
Ovary Surface Epithelium ◽  
Rat Ovary ◽  
High Doses

Hexachlorobenzene (HCB) is a known toxicant that is found in the environment as a by-product during manufacture of certain pesticides. This chlorinated chemical has been isolated from many tissues including ovary. When administered in high doses, HCB causes degeneration of primordial germ cells and ovary surface epithelium in sub-human primates. A purpose of this experiment was to determine a no-effect dose of the chemical on the rat ovary. The study is part of a comprehensive investigation on the effects of the compound on the biochemical, hematological, and morphological parameters in the monkey and rat.

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