The pebble gene is required for cytokinesis in Drosophila

1992 ◽  
Vol 103 (4) ◽  
pp. 1021-1030 ◽  
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.

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.

Gonad formation and development requires the abd-A domain of the bithorax complex in Drosophila melanogaster

Development ◽  
1992 ◽  
Vol 115 (2) ◽  
pp. 395-402 ◽  
Author(s):  
S. Cumberledge ◽  
J. Szabad ◽  
S. Sakonju
Keyword(s):  
Drosophila Melanogaster ◽  
Germ Line ◽  
Somatic Cells ◽  
Gonadal Development ◽  
Somatic Tissue ◽  
Bithorax Complex ◽  
Wild Type ◽  
Pole Cells ◽  
Transplantation Experiments

The abdominal-A (abd-A) gene, a member of the bithorax complex, is required for the correct identity of parasegments (PS) 7 through 13. Mutations in iab-4, one of the cis-regulatory regions of abd-A, transform epidermal structures of PS 9 and also cause loss of gonads in adult flies. Here, we describe a developmental and molecular analysis of the role of iab-4 functions in gonadal development. In flies homozygous for a strong iab-4 allele, gonadogenesis is not initiated in the embryo because the mesodermal cells fail to encapsulate the pole cells. Flies homozygous for weaker iab-4 mutations sometimes form ovaries. The ovary-oviduct junctions are abnormal, however, and egg transfer from the ovary to the uterus is blocked in the adult. To localize the sites that require iab-4 function, we have analyzed animals chimeric for the mutant and wild-type cells. These chimeras were generated by three kinds of transplantation experiments: pole cells, embryonic somatic nuclei or larval ovaries. Our results suggest that iab-4 is required in the somatic cells of the gonadal primordia, but not the germ line. In addition, the formation of functional ovary-oviduct junctions and egg transfer also requires iab-4 functions in the somatic cells of the ovary and in at least one additional somatic tissue.

Sex determination in germ line chimeras of Drosophila melanogaster

Development ◽  
1977 ◽  
Vol 37 (1) ◽  
pp. 173-185 ◽  
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.

Toll-like receptors stimulate human neutrophil function

Blood ◽  
2003 ◽  
Vol 102 (7) ◽  
pp. 2660-2669 ◽  
Author(s):  
Fumitaka Hayashi ◽  
Terry K. Means ◽  
Andrew D. Luster
Keyword(s):  
Immune Cell ◽  
Germ Line ◽  
Quantitative Polymerase Chain Reaction ◽  
Neutrophil Function ◽  
Human Neutrophils ◽  
Toll Like Receptors ◽  
Gm Csf ◽  
Latex Beads ◽  
Macrophage Colony ◽  
And Function

Abstract The first immune cell to arrive at the site of infection is the neutrophil. Upon arrival, neutrophils quickly initiate microbicidal functions, including the production of antimicrobial products and proinflammatory cytokines that serve to contain infection. This allows the acquired immune system enough time to generate sterilizing immunity and memory. Neutrophils detect the presence of a pathogen through germ line-encoded receptors that recognize microbe-associated molecular patterns. In vertebrates, the best characterized of these receptors are Toll-like receptors (TLRs). We have determined the expression and function of TLRs in freshly isolated human neutrophils. Neutrophils expressed TLR1, 2, 4, 5, 6, 7, 8, 9, and 10—all the TLRs except TLR3. Granulocyte-macrophage colony-stimulating factor (GM-CSF) treatment increased TLR2 and TLR9 expression levels. The agonists of all TLRs expressed in neutrophils triggered or primed cytokine release, superoxide generation, and L-selectin shedding, while inhibiting chemotaxis to interleukin-8 (IL-8) and increasing phagocytosis of opsonized latex beads. The response to the TLR9 agonist nonmethylated CpG-motif-containing DNA (CpG DNA) required GM-CSF pretreatment, which also enhanced the response to the other TLR agonists. Finally, using quantitative polymerase chain reaction (QPCR), we demonstrate a chemokine expression profile that suggests that TLR-stimulated neutrophils recruit innate, but not acquired, immune cells to sites of infection. (Blood. 2003;102:2660-2669)

The ethics of genome editing in the clinic: A dose of realism for healthcare leaders

2017 ◽  
Vol 30 (3) ◽  
pp. 159-163
Author(s):  
Tania Bubela ◽  
Yael Mansour ◽  
Dianne Nicol
Keyword(s):  
Genome Editing ◽  
Germ Line ◽  
Genetic Diseases ◽  
Somatic Cells ◽  
Clinical Translation ◽  
Preclinical Research ◽  
Societal Issues ◽  
Realistic Assessment ◽  
Healthcare Leaders

Genome editing technologies promise therapeutic advances for genetic diseases. We discuss the ethical and societal issues raised by these technologies, including their use in preclinical research, their potential to address mutations in somatic cells, and their potential to make germ line alterations that may be passed to subsequent generations. We call for a proportionate response from health leaders based on a realistic assessment of benefits, risks, and timelines for clinical translation.

Insertion and excision of Caenorhabditis elegans transposable element Tc1

1988 ◽  
Vol 8 (2) ◽  
pp. 737-746
Author(s):  
D Eide ◽  
P Anderson
Keyword(s):  
Amino Acid ◽  
Caenorhabditis Elegans ◽  
Transposable Element ◽  
Dna Sequences ◽  
Germ Line ◽  
Consensus Sequence ◽  
Somatic Cells ◽  
Chain Gene ◽  
Imprecise Excision ◽  
Insertion Sites

The transposable element Tc1 is responsible for most spontaneous mutations that occur in Caenorhabditis elegans variety Bergerac. We investigated the genetic and molecular properties of Tc1 transposition and excision. We show that Tc1 insertion into the unc-54 myosin heavy-chain gene was strongly site specific. The DNA sequences of independent Tc1 insertion sites were similar to each other, and we present a consensus sequence for Tc1 insertion that describes these similarities. We show that Tc1 excision was usually imprecise. Tc1 excision was imprecise in both germ line and somatic cells. Imprecise excision generated novel unc-54 alleles that had amino acid substitutions, amino acid insertions, and, in certain cases, probably altered mRNA splicing. The DNA sequences remaining after Tc1 somatic excision were the same as those remaining after germ line excision, but the frequency of somatic excision was at least 1,000-fold higher than that of germ line excision. The genetic properties of Tc1 excision, combined with the DNA sequences of the resulting unc-54 alleles, demonstrated that excision was dependent on Tc1 transposition functions in both germ line and somatic cells. Somatic excision was not regulated in the same strain-specific manner as germ-line excision was. In a genetic background where Tc1 transposition and excision in the germ line was not detectable, Tc1 excision in the soma still occurred at high frequency.

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.

Unequal cleavage in leech embryos: zygotic transcription is required for correct spindle orientation in subset of early blastomeres

Development ◽  
1996 ◽  
Vol 122 (2) ◽  
pp. 599-606
Author(s):  
S.T. Bissen ◽  
C.M. Smith
Keyword(s):  
Cell Division ◽  
Early Period ◽  
Spindle Orientation ◽  
Mitotic Spindles ◽  
Maternal Control ◽  
Transcription Analysis ◽  
Cell Divisions ◽  
Zygotic Transcription ◽  
Different Types ◽  
Alpha Amanitin

Leech embryos undergo invariant sequences of equal and unequal cell divisions to give rise to identifiable progeny cells. While many of the early cleavages are under maternal control, the divisions of a subset of early blastomeres (the large cells of the D' lineage) are perturbed after the inhibition of zygotic transcription. Analysis of the different types of cells produced in embryos injected with the transcriptional inhibitor, alpha-amanitin, revealed that the symmetry of cell division is perturbed in these large D'-derived cells during this early period of development. These cells, which would normally undergo a series of equal and unequal cleavages, always undergo equal cleavages after the inhibition of zygotic transcription. It appears that zygotically transcribed gene product(s) are required in the large cells of the D' lineage to orient the mitotic spindles properly for these unequal cell cleavages.

Multiple products from the shavenbaby-ovo gene region of Drosophila melanogaster: relationship to genetic complexity

1994 ◽  
Vol 14 (10) ◽  
pp. 6809-6818
Author(s):  
M D Garfinkel ◽  
J Wang ◽  
Y Liang ◽  
A P Mahowald
Keyword(s):  
Drosophila Melanogaster ◽  
Germ Line ◽  
Gene Region ◽  
Multiple Products ◽  
Zinc Finger Motifs ◽  
Genetic Complexity ◽  
Complex Locus ◽  
Female Germ Line ◽  
Sensory Structures ◽  
Pole Cells

The Drosophila melanogaster shavenbaby (svb)-ovo gene region is a complex locus, containing two distinct but comutable genetic functions. ovo is required for survival and differentiation of female germ line cells and plays a role in germ line sex determination. In contrast, svb is required in both male and female embryos for the production of epidermal locomotor and sensory structures. Sequences required for the two genetic functions are partially overlapping. ovo corresponds to a previously described germ line-dependent 5.0-kb poly(A)+ mRNA that first appears in the germarium and accumulates in nurse cells during oogenesis. The 5.0-kb mRNA is stored in the egg, but it is rapidly lost in the embryos except for its continued presence in the germ line precursor pole cells. The ovo mRNA predicts a 1,028-amino-acid 110.6-kDa protein homologous with transcription factors. We have identified an embryonic mRNA, 7.1 kb in length, that contains exons partially overlapping those of the 5.0-kb poly(A)+ mRNA. The spatial distribution of this newly discovered transcript during midembryogenesis suggests that it corresponds to the svb function. The arrangement of exons common to the 5.0- and 7.1-kb mRNAs suggests that the Ovo and Svb proteins share DNA-binding specificity conferred by four Cys2-His2 zinc finger motifs but differ functionally in their capacity to interact with other components of the transcription machinery.

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