Microtubule distribution reveals superficial metameric patterns in the early Drosophila embryo

Development ◽  
1989 ◽  
Vol 107 (1) ◽  
pp. 35-41
Author(s):  
G. Callaini
Keyword(s):  
Fluorescence Microscopy ◽  
Drosophila Embryo ◽  
Alpha Tubulin ◽  
Ventral Furrow ◽  
Early Drosophila Embryo ◽  
Blastoderm Stage ◽  
Whole Mounts ◽  
Drosophila Embryos

Microtubule distribution was examined in whole mounts of Drosophila embryos from the cellularization of the syncytial blastoderm (stage 6) to the completion of the gastrulation (stage 7) by fluorescence microscopy. During ventral furrow formation, the fluorescence of tubulin network was not uniform, but disposed in zebra stripes. Antibodies against alpha-tubulin showed 14 alternating pairs of darker and brighter transverse areas. The possible significance of this pattern is discussed.

scholarly journals Morphogenetic forces planar polarize LGN/Pins in the embryonic head during Drosophila gastrulation

2022 ◽  
Author(s):  
Jaclyn M Camuglia ◽  
Soline Chanet ◽  
Adam C Martin
Keyword(s):  
Planar Cell Polarity ◽  
Adherens Junction ◽  
Drosophila Embryo ◽  
Spindle Orientation ◽  
Planar Polarity ◽  
Ventral Furrow ◽  
Adherens Junction Protein ◽  
Early Drosophila Embryo ◽  
Junction Protein

Spindle orientation is often achieved by a complex of Pins/LGN, Mud/NuMa, Gαi, and Dynein, which interacts with astral microtubules to rotate the spindle. Cortical Pins/LGN recruitment serves as a critical step in this process. Here, we identify Pins-mediated planar cell polarized divisions in several of the mitotic domains of the early Drosophila embryo. We found that neither planar cell polarity pathways nor planar polarized myosin localization determined division orientation; instead, our findings strongly suggest that Pins planar polarity and force generated from mesoderm invagination are important. Disrupting Pins polarity via overexpression of a myristoylated version of Pins caused randomized division angles. We found that disrupting forces through chemical inhibitors, laser ablation, and depletion of an adherens junction protein disrupted Pins planar polarity and spindle orientation. Furthermore, snail depletion, which abrogates ventral furrow forces, disrupted Pins polarization and spindle orientation, suggesting that morphogenetic movements and resulting forces transmitted through the tissue can polarize Pins and orient division. Thus, morphogenetic forces associated with mesoderm invagination result in planar polarized Pins to mediate division orientation at a distant region of the embryo during morphogenesis. To our knowledge, this is the first in vivo example where mechanical force has been shown to polarize Pins to mediate division orientation.

Cyclin A and B functions in the early Drosophila embryo

Development ◽  
1999 ◽  
Vol 126 (23) ◽  
pp. 5505-5513 ◽  
Author(s):  
L.A. Stiffler ◽  
J.Y. Ji ◽  
S. Trautmann ◽  
C. Trusty ◽  
G. Schubiger
Keyword(s):  
Cyclin A ◽  
Cyclin B ◽  
Drosophila Embryo ◽  
Late Prophase ◽  
Early Drosophila Embryo ◽  
Nuclear Events ◽  
The Relationship ◽  
Maternal Gene ◽  
Drosophila Embryos

In eukaryotes, mitotic cyclins localize differently in the cell and regulate different aspects of the cell cycle. We investigated the relationship between subcellular localization of cyclins A and B and their functions in syncytial preblastoderm Drosophila embryos. During early embryonic cycles, cyclin A was always concentrated in the nucleus and present at a low level in the cytoplasm. Cyclin B was predominantly cytoplasmic, and localized within nuclei only during late prophase. Also, cyclin B colocalized with metaphase but not anaphase spindle microtubules. We changed maternal gene doses of cyclins A and B to test their functions in preblastoderm embryos. We observed that increasing doses of cyclin B increased cyclin B-Cdk1 activity, which correlated with shorter microtubules and slower microtubule-dependent nuclear movements. This provides in vivo evidence that cyclin B-Cdk1 regulates microtubule dynamics. In addition, the overall duration of the early nuclear cycles was affected by cyclin A but not cyclin B levels. Taken together, our observations support the hypothesis that cyclin B regulates cytoskeletal changes while cyclin A regulates the nuclear cycles. Varying the relative levels of cyclins A and B uncoupled the cytoskeletal and nuclear events, so we speculate that a balance of cyclins is necessary for proper coordination during these embryonic cycles.

scholarly journals Dynamic Hsp83 RNA localization during Drosophila oogenesis and embryogenesis

1993 ◽  
Vol 13 (6) ◽  
pp. 3773-3781
Author(s):  
D Ding ◽  
S M Parkhurst ◽  
S R Halsell ◽  
H D Lipshitz
Keyword(s):  
Polar Granule ◽  
Rna Degradation ◽  
Posterior Pole ◽  
Drosophila Embryo ◽  
Polar Granules ◽  
Local Protection ◽  
Early Drosophila Embryo ◽  
Drosophila Homolog ◽  
Developmental Significance ◽  
Blastoderm Stage

Hsp83 is the Drosophila homolog of the mammalian Hsp90 family of regulatory molecular chaperones. We show that maternally synthesized Hsp83 transcripts are localized to the posterior pole of the early Drosophila embryo by a novel mechanism involving a combination of generalized RNA degradation and local protection at the posterior. This protection of Hsp83 RNA occurs in wild-type embryos and embryos produced by females carrying the maternal effect mutations nanos and pumilio, which eliminate components of the posterior polar plasm without disrupting polar granule integrity. In contrast, Hsp83 RNA is not protected at the posterior pole of embryos produced by females carrying maternal mutations that disrupt the posterior polar plasm and the polar granules--cappuccino, oskar, spire, staufen, tudor, valois, and vasa. Mislocalization of oskar RNA to the anterior pole, which has been shown to result in induction of germ cells at the anterior, leads to anterior protection of maternal Hsp83 RNA. These results suggest that Hsp83 RNA is a component of the posterior polar plasm that might be associated with polar granules. In addition, we show that zygotic expression of Hsp83 commences in the anterior third of the embryo at the syncytial blastoderm stage and is regulated by the anterior morphogen, bicoid. We consider the possible developmental significance of this complex control of Hsp83 transcript distribution.

Pattern formation in the Drosophila embryo: allocation of cells to parasegments by even-skipped and fushi tarazu

Development ◽  
1989 ◽  
Vol 105 (4) ◽  
pp. 761-767 ◽  
Author(s):  
P.A. Lawrence ◽  
P. Johnston
Keyword(s):  
Pattern Formation ◽  
Drosophila Embryo ◽  
Germ Band ◽  
Fushi Tarazu ◽  
Cellular Resolution ◽  
Blastoderm Stage ◽  
Pair Rule ◽  
Drosophila Embryos

The first sign of metamerization in the Drosophila embryo is the striped expression of pair-rule genes such as fushi tarazu (ftz) and even-skipped (eve). Here we describe, at cellular resolution, the development of ftz and eve protein stripes in staged Drosophila embryos. They appear gradually, during the syncytial blastoderm stage and soon become asymmetric, the anterior margins of the stripes being sharply demarcated while the posterior borders are undefined. By the beginning of germ band elongation, the eve and ftz stripes have narrowed and become very intense at their anterior margins. The development of these stripes in hairy-, runt-, eve-, ftz- and engrailed- embryos is illustrated. In eve- embryos, the ftz stripes remain symmetric and lack sharp borders. Our results support the hypothesis (Lawrence et al. Nature 328, 440–442, 1987) that individual cells are allocated to parasegments with respect to the anterior margins of the eve and ftz stripes.

scholarly journals Reassessing the Role and Dynamics of Nonmuscle Myosin II during Furrow Formation in Early Drosophila Embryos

2004 ◽  
Vol 15 (2) ◽  
pp. 838-850 ◽  
Author(s):  
Anne Royou ◽  
Christine Field ◽  
John C. Sisson ◽  
William Sullivan ◽  
Roger Karess
Keyword(s):  
Myosin Ii ◽  
Colchicine Treatment ◽  
Drosophila Embryo ◽  
Dependent Manner ◽  
Membrane Invagination ◽  
Nonmuscle Myosin Ii ◽  
Early Drosophila Embryo ◽  
Cytoskeleton Rearrangements ◽  
Drosophila Embryos

The early Drosophila embryo undergoes two distinct membrane invagination events believed to be mechanistically related to cytokinesis: metaphase furrow formation and cellularization. Both involve actin cytoskeleton rearrangements, and both have myosin II at or near the forming furrow. Actin and myosin are thought to provide the force driving membrane invagination; however, membrane addition is also important. We have examined the role of myosin during these events in living embryos, with a fully functional myosin regulatory light-chain-GFP chimera. We find that furrow invagination during metaphase and cellularization occurs even when myosin activity has been experimentally perturbed. In contrast, the basal closure of the cellularization furrows and the first cytokinesis after cellularization are highly dependent on myosin. Strikingly, when ingression of the cellularization furrow is experimentally inhibited by colchicine treatment, basal closure still occurs at the appropriate time, suggesting that it is regulated independently of earlier cellularization events. We have also identified a previously unrecognized reservoir of particulate myosin that is recruited basally into the invaginating furrow in a microfilament-independent and microtubule-dependent manner. We suggest that cellularization can be divided into two distinct processes: furrow ingression, driven by microtubule mediated vesicle delivery, and basal closure, which is mediated by actin/myosin based constriction.

scholarly journals Dynamic Hsp83 RNA localization during Drosophila oogenesis and embryogenesis.

1993 ◽  
Vol 13 (6) ◽  
pp. 3773-3781 ◽  
Author(s):  
D Ding ◽  
S M Parkhurst ◽  
S R Halsell ◽  
H D Lipshitz
Keyword(s):  
Polar Granule ◽  
Rna Degradation ◽  
Posterior Pole ◽  
Drosophila Embryo ◽  
Polar Granules ◽  
Local Protection ◽  
Early Drosophila Embryo ◽  
Drosophila Homolog ◽  
Developmental Significance ◽  
Blastoderm Stage

Hsp83 is the Drosophila homolog of the mammalian Hsp90 family of regulatory molecular chaperones. We show that maternally synthesized Hsp83 transcripts are localized to the posterior pole of the early Drosophila embryo by a novel mechanism involving a combination of generalized RNA degradation and local protection at the posterior. This protection of Hsp83 RNA occurs in wild-type embryos and embryos produced by females carrying the maternal effect mutations nanos and pumilio, which eliminate components of the posterior polar plasm without disrupting polar granule integrity. In contrast, Hsp83 RNA is not protected at the posterior pole of embryos produced by females carrying maternal mutations that disrupt the posterior polar plasm and the polar granules--cappuccino, oskar, spire, staufen, tudor, valois, and vasa. Mislocalization of oskar RNA to the anterior pole, which has been shown to result in induction of germ cells at the anterior, leads to anterior protection of maternal Hsp83 RNA. These results suggest that Hsp83 RNA is a component of the posterior polar plasm that might be associated with polar granules. In addition, we show that zygotic expression of Hsp83 commences in the anterior third of the embryo at the syncytial blastoderm stage and is regulated by the anterior morphogen, bicoid. We consider the possible developmental significance of this complex control of Hsp83 transcript distribution.

Laser scanning confocal microscopic analysis of cytoskeletal and nuclear reorganization in live Drosophila embryos

1993 ◽  
Vol 51 ◽  
pp. 174-175
Author(s):  
William Theurkauf
Keyword(s):  
Laser Scanning ◽  
Microscopic Analysis ◽  
Large Cell ◽  
Early Embryo ◽  
Drosophila Embryo ◽  
Cortical Actin ◽  
Nuclear Reorganization ◽  
Cytoskeletal Elements ◽  
Microtubule Structure ◽  
Drosophila Embryos

Cell division in eucaryotes depends on coordinated changes in nuclear and cytoskeletal components. In Drosophila melanogaster embryos, the first 13 nuclear divisions occur without cytokinesis. During the final four divisions, nuclei divide in a uniform monolayer at the surface of the embryo. These surface divisions are accompanied by dramatic changes in cortical actin and microtubule structure (Karr and Alberts, 1986), and inhibitor studies indicate that these changes are essential to orderly mitosis (Zalokar and Erk, 1976). Because the early embryo is syncytial, fluorescent probes introduced by microinjection are incorporated in structures associated with all of the nuclei in the blastoderm. In addition, the nuclei divide synchronously every 10 to 20 min. These characteristics make the syncytial blastoderm embryo an excellent system for the analysis of mitotic reorganization of both nuclear and cytoskeletal elements. However, the Drosophila embryo is a large cell, and resolution of cytoskeletal filaments and nuclear structure is hampered by out-of focus signal.

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