Immunocytological and FISH analysis of pole cell formation and soma elimination of germ line-limited chromosomes in the chironomid Acricotopus lucidus

2000 ◽  
Vol 302 (2) ◽  
pp. 189-197 ◽  
Author(s):  
Wolfgang Staiber
Keyword(s):  
Germ Line ◽  
Cell Formation ◽  
Fish Analysis ◽  
Pole Cell ◽  
Acricotopus Lucidus

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

Genome ◽  
2006 ◽  
Vol 49 (3) ◽  
pp. 269-274 ◽  
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.

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

Development ◽  
1992 ◽  
Vol 115 (4) ◽  
pp. 1175-1182 ◽  
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.

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

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.

Centrosomes, and not nuclei, initiate pole cell formation in Drosophila embryos

Cell ◽  
1989 ◽  
Vol 57 (4) ◽  
pp. 611-619 ◽  
Author(s):  
Jordan W. Raff ◽  
David M. Glover
Keyword(s):  
Cell Formation ◽  
Pole Cell ◽  
Drosophila Embryos

scholarly journals Identification of a component of Drosophila polar granules

Development ◽  
1988 ◽  
Vol 103 (4) ◽  
pp. 625-640 ◽  
Author(s):  
B. Hay ◽  
L. Ackerman ◽  
S. Barbel ◽  
L.Y. Jan ◽  
Y.N. Jan
Keyword(s):  
Germ Line ◽  
Posterior Pole ◽  
Nuclear Bodies ◽  
Maternal Origin ◽  
Pole Cell ◽  
Polar Granules ◽  
Early Embryos ◽  
Biochemical Studies ◽  
Males And Females ◽  
Pole Cells

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.

Sex determination in the germ line of Drosophila melanogaster: activation of the gene Sex-lethal

Development ◽  
1993 ◽  
Vol 118 (3) ◽  
pp. 813-816 ◽  
Author(s):  
B. Granadino ◽  
P. Santamaria ◽  
L. Sanchez
Keyword(s):  
Drosophila Melanogaster ◽  
Germ Cells ◽  
Germ Line ◽  
Wild Type ◽  
Female Development ◽  
Pole Cell ◽  
Somatic Tissues ◽  
Wild Type Female ◽  
Sex Lethal ◽  
Pole Cell Transplantation

The germ line exhibits sexual dimorphism as do the somatic tissues. Cells with the 2X;2A chromosome constitution will follow the oogenic pathway and X;2A cells will develop into sperm. In both somatic and germ-line tissues, the sexual pathway chosen by the cells depends on the gene Sex-lethal (Sxl), whose function is continuously needed for female development. In the soma, the sex of the cells is autonomously determined by the X:A signal while, in the germ line, the sex is determined by cell autonomous (the X:A signal) and somatic inductive signals. Three X-linked genes have been identified, scute (sc), sisterless-a (sis-a) and runt (run), that determine the initial functional state of Sxl in the soma. Using pole cell transplantation, we have tested whether these genes are also needed to activate Sxl in the germ line. We found that germ cells simultaneously heterozygous for sc, sis-a, run and a deficiency for Sxl transplanted into wild-type female hosts develop into functional oocytes. We conclude that the genes sc, sis-a and run needed to activate Sxl in the soma seem not to be required to activate this gene in the germ line; therefore, the X:A signal would be made up by different genes in somatic and germ-line tissues. The Sxlf7M1/Sxlfc females do not have developed ovaries. We have shown that germ cells of this genotype transplanted into wild-type female hosts produce functional oocytes. We conclude that the somatic component of the gonads in Sxlf7M1/Sxlfc females is affected, and consequently germ cells do not develop.(ABSTRACT TRUNCATED AT 250 WORDS)

Oskar anchoring restricts pole plasm formation to the posterior of the Drosophila oocyte

Development ◽  
2002 ◽  
Vol 129 (15) ◽  
pp. 3705-3714 ◽  
Author(s):  
Nathalie F. Vanzo ◽  
Anne Ephrussi
Keyword(s):  
Drosophila Melanogaster ◽  
Translational Control ◽  
Cell Formation ◽  
Positional Information ◽  
Mrna Localization ◽  
Posterior Pole ◽  
Tight Coupling ◽  
Anteroposterior Patterning ◽  
Pole Cell ◽  
Pole Plasm

Localization of the maternal determinant Oskar at the posterior pole of Drosophila melanogaster oocyte provides the positional information for pole plasm formation. Spatial control of Oskar expression is achieved through the tight coupling of mRNA localization to translational control, such that only posterior-localized oskar mRNA is translated, producing the two Oskar isoforms Long Osk and Short Osk. We present evidence that this coupling is not sufficient to restrict Oskar to the posterior pole of the oocyte. We show that Long Osk anchors both oskar mRNA and Short Osk, the isoform active in pole plasm assembly, at the posterior pole. In the absence of anchoring by Long Osk, Short Osk disperses into the bulk cytoplasm during late oogenesis, impairing pole cell formation in the embryo. In addition, the pool of untethered Short Osk causes anteroposterior patterning defects, owing to the dispersion of pole plasm and its abdomen-inducing activity throughout the oocyte. We show that the N-terminal extension of Long Osk is necessary but not sufficient for posterior anchoring, arguing for multiple docking elements in Oskar. This study reveals cortical anchoring of the posterior determinant Oskar as a crucial step in pole plasm assembly and restriction, required for proper development of Drosophila melanogaster.

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