scholarly journals Experimental Studies on Pole Cells and Midgut Differentiation in Diptera

1960 ◽  
Vol 13 (4) ◽  
pp. 541 ◽  
Author(s):  
DF Poulson ◽  
DF Waterhouse
Keyword(s):  
Drosophila Melanogaster ◽  
Germ Cells ◽  
Polar Region ◽  
Experimental Studies ◽  
Cell Formation ◽  
Lucilia Cuprina ◽  
Pole Cell ◽  
Gonad Size ◽  
The Common ◽  
Pole Cells

Highly localized irradiation with ultraviolet of the posterior polar region of eggs of Drosophila melanogaster and Lucilia cuprina in pre.pole cell and pole cell stages results in reduction in numbers of the cuprophilic cells of the middle midgut as well as in reduction of gonad size and number. Carefully timed eggs were exposed to dosages of ultraviolet (from a source giving about 90 per cent. at wavelength 2536 A) ranging from 1200 to 2400 I-' W sec/cm2 over periods of 2-4 min. Treatments at the time of active pole cell formation were found to be most effective in producing defects of both gut and gonads, thus demon� strating the common origin of the cuprophilic cells of the middle midgut and the germ cells of the gonads.

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.

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.

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

2018 ◽  
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.

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

Development ◽  
1989 ◽  
Vol 107 (4) ◽  
pp. 733-742 ◽  
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.

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.

scholarly journals Three distinct distributions of F-actin occur during the divisions of polar surface caps to produce pole cells in Drosophila embryos.

1985 ◽  
Vol 100 (4) ◽  
pp. 1010-1015 ◽  
Author(s):  
R M Warn ◽  
L Smith ◽  
A Warn
Keyword(s):  
Cell Formation ◽  
Contractile Ring ◽  
Polar Surface ◽  
Ring Type ◽  
Actin Organization ◽  
Polar Caps ◽  
Pole Cell ◽  
Nuclear Cycle ◽  
Pole Cells ◽  
Drosophila Embryos

The F-actin distribution was studied during pole cell formation in Drosophila embryos using the phalloidin derivative rhodaminyl-lysine-phallotoxin. Nuclei were also stained with 4'-6 diamidine-2-phenylindole dihydrochloride to correlate the pattern seen with the nuclear cycle. The precursors of the pole cells, the polar surface caps, were found to have an F-actin-rich cortex distinct from that of the rest of the embryo surface and an interior cytoplasm that was less intensely stained but brighter than the cytoplasm deeper in the embryo. They were found to divide once without forming true cells and then a second time when cells formed as a result of a meridional and a basal cleavage. Three distinct distributions of the cortical F-actin have been identified during these cleavages. It is concluded that the first division, which cleaves the polar caps but does not separate them from the embryo, involves very different processes from those that lead to the formation of the pole cells. A contractile-ring type of F-actin organization may not be present during the first cleavage but is suggested to occur during the second.

scholarly journals Evidence of a dual function in fl(2)d, a gene needed for Sex-lethal expression in Drosophila melanogaster.

Genetics ◽  
1992 ◽  
Vol 130 (3) ◽  
pp. 597-612 ◽  
Author(s):  
B Granadino ◽  
A San Juán ◽  
P Santamaria ◽  
L Sánchez
Keyword(s):  
Drosophila Melanogaster ◽  
Germ Cells ◽  
Sensitive Period ◽  
Dual Function ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Loss Of Function ◽  
Germline Development ◽  
Suppression Effect ◽  
Pole Cells

Abstract In Drosophila melanogaster, the female sexual development of the soma and the germline requires the activity of the gene Sxl. The somatic cells need the function of the gene fl(2)d to follow the female developmental pathway, due to its involvement in the female-specific splicing of Sxl RNA. Here we report the analysis of both fl(2)d1 and fl(2)d2 mutations: (1) fl(2)d1 is a temperature-sensitive mutation lethal in females and semilethal in males; (2) fl(2)d2 is lethal in both sexes; (3) the fl(2)d1/fl(2)d2 constitution is temperature-sensitive and lethal in females, while semilethal in males. The temperature-sensitive period of fl(2)d1 in females expands the whole development. SxlM1 partially suppresses the lethality of fl(2)d1 homozygous females and that of fl(2)d1/fl(2)d2 constitution, whereas it does not suppress the lethality of fl(2)d2 homozygous females. The addition of extra Sxl+ copies does not increase the suppression effect of SxlM1. The fl(2)d1 mutation in homozygosis and the fl(2)d1/fl(2)d2 constitution, but not the fl(2)d2 in homozygosis, partially suppress the lethality of SxlM1 males. This suppression is not prevented by the addition of extra Sxl+ copies. The semilethality of both fl(2)d1 and fl(2)d1/fl(2)d2 males, and the lethality of fl(2)d2 males, is independent of Sxl function. There is no female synergistic lethality between mutations at fl(2)d and neither at sc or da. However, the female synergistic lethality between mutations at Sxl and either sc or da is increased by fl(2)d mutations. We have analyzed the effect of the fl(2)d mutations on the germline development of both females and males. For that purpose, we carried out the clonal analysis of fl(2)d1 in the germline. In addition, pole cells homozygous for fl(2)d2 were transplanted into wild-type host embryos, and we checked whether the mutant pole cells were capable of forming functional gametes. The results indicated that fl(2)d mutant germ cells cannot give rise to functional oocytes, while they can form functional sperm. Moreover, SxlM1 suppresses the sterility of the fl(2)d1 homozygous females developing at the permissive temperature. Thus, with respect to the development of the germline the fl(2)d mutations mimic the behavior of loss-of-function mutations at the gene Sxl. Females double heterozygous for fl(2)d and snf1621 are fully viable and fertile. fl(2)d2 in heterozygosis partially suppresses the phenotype of female germ cells homozygous for snf1621; however, this is not the case with the fl(2)d1 mutation. The fl(2)d mutations partially suppress the phenotype of the female germ cells homozygous for ovoDIrSI.(ABSTRACT TRUNCATED AT 400 WORDS)

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