Identification of a component of Drosophila polar granules

Information necessary for the formation of pole cells, precursors of the germ line, is provided maternally and localized to the posterior pole of the Drosophila egg. The maternal origin and posterior localization of polar granules suggest that they may be associated with pole cell determinants. We have generated an antibody (Mab46F11) against polar granules. In oocytes and early embryos, the Mab46F11 antigen is sharply localized to the posterior embryonic pole. In pole cells, it becomes associated with nuclear bodies within, and nuage around, the nucleus. Immunoreactivity remains associated with cells of the germ line throughout the life cycle of both males and females. This antibody recognizes a 72–74 × 10(3) Mr protein and is useful both as a pole lineage marker and in biochemical studies of polar granules.

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Restoration of pole-cell-forming ability to u.v.-irradiated Drosophila embryos by injection of mitochondrial lrRNA

Development ◽

10.1242/dev.107.4.733 ◽

1989 ◽

Vol 107 (4) ◽

pp. 733-742 ◽

Cited By ~ 3

Author(s):

S. Kobayashi ◽

M. Okada

Keyword(s):

Dna Sequences ◽

Nuclear Dna ◽

Mitochondrial Gene ◽

Cell Formation ◽

Nuclear Bodies ◽

Cdna Insert ◽

Pole Cell ◽

Polar Granules ◽

Pole Cells

Screening a cDNA library generated from poly(A) +RNA of Drosophila cleavage embryos, we selected a cDNA clone (pDE20.6). The cDNA hybridized specifically with a poly(A) +RNA that is capable of restoring embryos from u.v.-caused inability of pole cell formation. The RNA hybrid-selected by pDE20.6 was also able to induce pole cells in the anterior region of embryos, if it was coinjected with u.v.-irradiated polar plasm, although the RNA or irradiated polar plasm alone was not effective. Pole cells thus formed in the anterior or in the u.v.-irradiated posterior region were identified by polar granules and nuclear bodies, morphological markers for normal pole cells. Furthermore, the RNA-induced pole cells were able to migrate into gonadal rudiments. The nucleotide sequence of pDE20.6 cDNA insert was highly homologous with the mitochondrial large rRNA (lrRNA) gene, but not with any nuclear DNA sequences. Using pDE20.6 as a primer, a full-length cDNA of mitochondrial lrRNA was generated and cloned. The RNA transcribed in vitro from the cDNA was able to restore pole cell formation. The cDNA hybridized only with a 1.5 kb poly(A) +RNA on a Northern blot. The 1.5 kb RNA sedimented more with the post-mitochondrial (P3) fraction than with the mitochondrial (P2) fraction, while the majority of transcripts from another mitochondrial gene was detected in the P2 fraction.

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Differentiation and positioning of nuclei in eggs of the cecidomyid Heteropeza pygmaea

Journal of Cell Science ◽

10.1242/jcs.22.1.99 ◽

1976 ◽

Vol 22 (1) ◽

pp. 99-113

Author(s):

M. Meats ◽

J.B. Tucker

Keyword(s):

Structural Changes ◽

Early Stage ◽

Cell Formation ◽

Longitudinal Axis ◽

Posterior Pole ◽

Spindle Orientation ◽

Specific Sequence ◽

Pole Cell ◽

Polar Granules ◽

Egg Chamber

During the first three cleavage divisions of the egg nuclei a precise sequence of spindle orientation and elongation parallel to the longitudinal axis of the egg is apparently involved in positioning one nucleus among the polar granules at the posterior pole of the egg. The size of this nucleus, and the position at which the egg cleaves when pole cell formation occurs, appear to constitute part of the mechanism which ensures that only one nucleus is included in the first pole cell. Blastoderm formation occurs without a well-defined migration of nuclei to the egg surface. Nuclei are so large in relation to the size of the egg that uniform spacing and distribution of nuclei ensures that a large proportion are situated near the egg surface. Those nuclei which are near the egg surface divide synchronously to form a layer of blastoderm nuclei, while membranous cleavage furrows invaginate from the egg surface between them. Nuclei in the central region of the egg chamber condense to form yolk nuclei before blastoderm nuclei have been separated from the rest of the egg by the completion of the cleavage membranes. Polar granules provide the only evidence of fine-structural differences in different regions of the egg chamber cytoplasm. They are found near the posterior pole of the egg from an early stage of oogenesis. They undergo a specific sequence of structural changes and increase in size as the egg grows. No microtubular or microfibrillar arrays have been found in the egg chamber which might form a cytoskeletal basis for spindle orientation or for the spatial differences which develop during differentiation of the uncleaved egg cytoplasm.

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Transcriptomic and functional analysis of the oosome, a unique form of germ plasm in the waspNasonia vitripennis

10.1101/384032 ◽

2018 ◽

Cited By ~ 1

Author(s):

Honghu Quan ◽

Jeremy Lynch

Keyword(s):

Molecular Basis ◽

Germ Plasm ◽

Cell Formation ◽

Solid Sphere ◽

The Novel ◽

Developmental Networks ◽

Pole Cell ◽

Polar Granules ◽

Developmental Role ◽

Pole Cells

AbstractBackgroundThe oosome is the germline determinant in the waspNasonia vitripennisand is homologous to the polar granules ofDrosophila. Despite a common evolutionary origin and developmental role, the oosome is morphologically quite distinct from polar granules. It is a solid sphere that migrates within the cytoplasm before budding out and forming pole cells.ResultsTo gain an understanding of both the molecular basis of the novel form of the oosome, and the conserved essential features of germ plasm, we quantified and compared transcript levels between embryo fragments that contained the oosome, and those that did not. The identity of the localized transcripts indicated thatNasoniauses different molecules to carry out conserved germ plasm functions. In addition, functional testing of a sample of localized transcripts revealed potentially novel mechanisms of ribonucleoprotein assembly and pole cell cellularization in the wasp.ConclusionsOur results demonstrate that numerous novel and unexpected molecules have been recruited in order produce the unique characteristics of the oosome and pole cell formation inNasonia. This work will serve as the basis for further investigation into the patterns of germline determinant evolution among insects, the molecular basis of extreme morphology of ribonucleoproteins, and the incorporation of novel components into developmental networks.

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The pebble gene is required for cytokinesis in Drosophila

Journal of Cell Science ◽

10.1242/jcs.103.4.1021 ◽

1992 ◽

Vol 103 (4) ◽

pp. 1021-1030 ◽

Cited By ~ 17

Author(s):

C.F. Lehner

Keyword(s):

Germ Line ◽

Somatic Cells ◽

Nuclear Envelope Breakdown ◽

Cell Divisions ◽

Pole Cell ◽

Maternal Contribution ◽

Zygotic Gene ◽

Pole Cells ◽

And Function ◽

Alpha Amanitin

Cytokinesis is developmentally controlled during Drosophila embryogenesis. It is omitted during the initial nuclear division cycles. The nuclei of the resulting syncytium are then cellularized at a defined stage, and cytokinesis starts in somatic cells with mitosis 14. However, cytokinesis never occurs in somatic cells of embryos homozygous or transheterozygous for mutations in the pebble gene. Interestingly, the process of cellularization, which involves steps mechanistically similar to cytokinesis, is not affected. Moreover, all the nuclear aspects of mitosis (nuclear envelope breakdown, chromosome condensation, spindle assembly and function) proceed normally in pebble mutant embryos, indicating that pebble is specifically required for the coordination of mitotic spindle and contractile ring functions. The pebble phenotype is also observed, but only with very low penetrance, during the early divisions of the germ line progenitors (the pole cells). alpha-Amanitin injection experiments indicate that these early pole cell divisions, the first cell divisions during embryogenesis, do not require zygotic gene expression. These divisions might therefore rely on maternally contributed pebble function. The maternal contribution from heterozygous mothers might be insufficient in rare cases for all the pole cell divisions.

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

Development ◽

10.1242/dev.119.1.207 ◽

1993 ◽

Vol 119 (1) ◽

pp. 207-219 ◽

Cited By ~ 12

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.

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Transcriptomic and functional analysis of the oosome, a unique form of germ plasm in the wasp Nasonia vitripennis

BMC Biology ◽

10.1186/s12915-019-0696-7 ◽

2019 ◽

Vol 17 (1) ◽

Author(s):

Honghu Quan ◽

Deanna Arsala ◽

Jeremy A. Lynch

Keyword(s):

Molecular Basis ◽

Germ Plasm ◽

Solid Sphere ◽

Nasonia Vitripennis ◽

Unique Form ◽

Developmental Networks ◽

Pole Cell ◽

Polar Granules ◽

Developmental Role ◽

Pole Cells

Abstract Background The oosome is the germline determinant in the wasp Nasonia vitripennis and is homologous to the polar granules of Drosophila. Despite a common evolutionary origin and developmental role, the oosome is morphologically quite distinct from polar granules. It is a solid sphere that migrates within the cytoplasm before budding out and forming pole cells. Results To gain an understanding of both the molecular basis of oosome development and the conserved essential features of germ plasm, we quantified and compared transcript levels between embryo fragments that contained the oosome and those that did not. The identity of the differentially localized transcripts indicated that Nasonia uses a distinct set of molecules to carry out conserved germ plasm functions. In addition, functional testing of a sample of localized transcripts revealed potentially novel mechanisms of ribonucleoprotein assembly and pole cell cellularization in the wasp. Conclusions Our results demonstrate that the composition of germ plasm varies significantly within Holometabola, as very few mRNAs share localization to the oosome and polar granules. Some of this variability appears to be related to the unique properties of the oosome relative to the polar granules in Drosophila, and some may be related to differences in pole formation between species. This work will serve as the basis for further investigation into the patterns of germline determinant evolution among insects, the molecular basis of the unique properties of the oosome, and the incorporation of novel components into developmental networks.

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Sex determination in germ line chimeras of Drosophila melanogaster

Development ◽

10.1242/dev.37.1.173 ◽

1977 ◽

Vol 37 (1) ◽

pp. 173-185 ◽

Cited By ~ 1

Author(s):

E. B. van Deusen

Keyword(s):

Germ Cells ◽

Germ Line ◽

Sex Reversal ◽

Progeny Testing ◽

Pole Cell ◽

Cell Transplants ◽

Opposite Sex ◽

Female Donor ◽

Pole Cells ◽

Pole Cell Transplantation

Of 55 flies developing from blastoderms which had received male or female pole cell transplants, 15 (7 females and 8 males) were shown by progeny testing to be germ line chimeras. Since donor and host pole cells were genetically marked with contrasting X- or Y-linked alleles, the progeny testing scheme enabled the genotypic sex of the donor component undergoing gametogenesis to be identified as either the same as (‘homosexual’ chimeras) or opposite (‘heterosexual’ chimeras) that of the host. All seven of the female chimeras were identified as ‘homosexual’ chimeras carrying only chromosomally female donor and XX host germ cells. Similarly, all eight males were shown to be ‘homosexual’ chimeras with chromosomally male XY donor and XY host germ cells. The chromosomal sex of the donor component undergoing gametogenesis was in every case the same as the phenotypic sex of the host. Since there is an equal probability of constructing either a ‘homosexual’ or a ‘heterosexual’ chimera during pole cell transplantation, the ability of pole cells to differentiate functional gametes in hosts of the opposite sex was tested 50 % of the time even if sex reversal of these donor pole cells could not be demonstrated. Thus the absence of ‘heterosexual’ chimerism strongly supports the interpretation that the phenotypic sex of a germ cell in Drosophila is determined entirely by its own chromosome constitution, not by that of the gonadal mesoderm.

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Polar granules and pole cells in the embryo of Calliphora erythrocephala: ultrastructure and [3H]leucine labelling

Development ◽

10.1242/dev.57.1.79 ◽

1980 ◽

Vol 57 (1) ◽

pp. 79-93

Author(s):

Anders Lundquist ◽

Hadar Emanuelsson

Keyword(s):

Cell Formation ◽

Electron Microscopic ◽

Electron Microscopic Autoradiography ◽

Calliphora Erythrocephala ◽

Pole Cell ◽

Polar Granules ◽

Pole Cells ◽

Autoradiographic Analysis ◽

Pole Plasm ◽

Blastoderm Stage

The polar granules in Calliphora undergo a gradual fragmentation during early cleavage, but reaggregate after pole-cell formation. Autoradiographic analysis showed that the pole cells in Calliphora acquire a higher ‘3H’leucine label than the rest of the embryo during the blastoderm stage. Such an increased label was not seen in the pole plasm before pole-cell formation or in the pole cells during gastrulation. Electron microscopic autoradiography revealed that the polar granules are substantially labelled during the blastoderm stage. At the same time, characteristic nuclear blebs appear in the pole cells. The observations are consistent with the hypothesis that polar granules contain maternalmessenger RNA, which is released and translated into proteins.

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Chromosome elimination in germ line – soma differentiation of Acricotopus lucidus (Diptera, Chironomidae)

Genome ◽

10.1139/g05-103 ◽

2006 ◽

Vol 49 (3) ◽

pp. 269-274 ◽

Cited By ~ 12

Author(s):

Wolfgang Staiber

Keyword(s):

Dna Sequences ◽

Germ Line ◽

Chromosome Elimination ◽

Fish Analysis ◽

Sister Chromatids ◽

Early Embryos ◽

One Step ◽

Pole Cells ◽

Acricotopus Lucidus

During germ line – soma differentiation in early syncytial embryonic development of the chironomid Acricotopus lucidus, a complement of supernumerary chromosomes, the so-called germ line limited chromosomes (Ks), is excluded from the future somatic nuclei in the course of elimination mitoses. The Ks lag behind in the equatorial plane, while the somatic chromosomes (Ss) segregate equally. After elimination mitoses, the Ks are only present in the pole cells, the primary germ cells. In the divisions before their elimination, the Ks frequently showed delayed separation of sister chromatids with high-frequency formation of anaphasic bridges and lagging in pole movement as detected in 4′,6-diamidino-2-phenylindole (DAPI)-stained squash preparations of early embryos. To determine if all of the Ks are eliminated in one step during a single mitosis, a fluorescence in situ hybridization (FISH) analysis of early embryonic divisions was performed using probes of germ line specific repetitive DNA sequences, which specifically label the Ks in their centromeric regions. In most cases, all of the Ks are lost in one mitosis; however, occasionally one or several of the Ks can escape their elimination by segregating and moving poleward together with the Ss. The escaping Ks will then be eliminated in one of the following mitoses. This clearly indicates that the specific conditions to eliminate Ks are not restricted to only one division. Possible mechanisms of elimination of Ks are discussed.Key words: germ line limited chromosomes, elimination mitosis, germ line – soma differentiation, FISH.

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Spatial and developmental changes in the respiratory activity of mitochondria in early Drosophila embryos

Development ◽

10.1242/dev.115.4.1175 ◽

1992 ◽

Vol 115 (4) ◽

pp. 1175-1182 ◽

Cited By ~ 1

Author(s):

T. Akiyama ◽

M. Okada

Keyword(s):

Respiratory Activity ◽

Cell Formation ◽

Rhodamine 123 ◽

Mitochondrial Activity ◽

Early Cleavage ◽

Pole Cell ◽

Posterior Group ◽

Cleavage Stages ◽

Pole Cells ◽

Drosophila Embryos

Mitochondria of early Drosophila embryos were observed with a transmission electron microscope and a fluorescent microscope after vital staining with rhodamine 123, which accumulates only in active mitochondria. Rhodamine 123 accumulated particularly in the posterior pole region in early cleavage embryos, whereas the spatial distribution of mitochondria in an embryo was uniform throughout cleavage stages. In late cleavage stages, the dye showed very weak and uniform accumulation in all regions of periplasm. Polar plasm, sequestered in pole cells, restored the ability to accumulate the dye. Therefore, it is concluded that the respiratory activity of mitochondria is higher in the polar plasm than in the other regions of periplasm in early embryos, and this changes during development. The temporal changes in rhodamine 123-staining of polar plasm were not affected by u.v. irradiation at the posterior of early cleavage embryos at a sufficient dosage to prevent pole cell formation. This suggests that the inhibition of pole cell formation by u.v. irradiation is not due to the inactivation of the respiratory activities of mitochondria. In addition, we found that the anterior of Bicaudal-D mutant embryos at cleavage stage was stained with rhodamine 123 with the same intensity as the posterior of wild-type embryos. No pole cells form in the anterior of Bic-D embryos, where no restoration of mitochondrial activity occurs in the blastoderm stage. The posterior group mutations that we tested (staufen, oskar, tudor, nanos) and the terminal mutation (torso) did not alter staining pattern of the posterior with rhodamine 123.

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