Autonomous determination of anterior structures in the early Drosophila embryo by the bicoid morphogen

Development ◽  
1990 ◽  
Vol 109 (4) ◽  
pp. 811-820 ◽  
Author(s):  
W. Driever ◽  
V. Siegel ◽  
C. Nusslein-Volhard
Keyword(s):  
Drosophila Embryo ◽  
Beta Globin ◽  
P Transformation ◽  
Early Drosophila Embryo ◽  
Maternal Effect Genes ◽  
Translational Block ◽  
Maternal Gene ◽  
Anterior Posterior

A small number of maternal effect genes determine anterior-posterior pattern in the Drosophila embryo. Embryos from females mutant for the maternal gene bicoid lack head and thorax. bcd mRNA becomes localized to the anterior tip of the egg during oogenesis and is the source for the morphogen gradient of bcd protein. Here we show that in vitro transcribed bicoid mRNA that has its own leader sequences substituted by the Xenopus beta-globin 5′ untranslated sequences is translated more efficiently than bicoid mRNA with the natural 5′ mRNA leader when tested in vitro and in Drosophila Schneider cells. When injected into bicoid mutant embryos, only the bcd mRNA with the beta-globin leader sequence, substituted for the natural leader, is able to induce anterior development. We used P-transformation to show that sequences in the 5′ leader are neither necessary for localization of the transcript nor for the translational block of the bcd mRNA during oogenesis. For our injection experiments, we used only one of the identified splicing forms of bcd mRNA. The bcd protein species derived from this mRNA is able to induce anterior development at any position along the anterior-posterior axis. Thus bicoid protein can induce development of head and thorax independent of any other specifically localized morphogenetic factor. Our findings further support the notion that the concentration gradient of bcd protein, and not the existence of different forms of bcd protein, is responsible for specifying subregions of the embryo.

scholarly journals The GAGA factor is required in the early Drosophila embryo not only for transcriptional regulation but also for nuclear division

Development ◽  
1996 ◽  
Vol 122 (4) ◽  
pp. 1113-1124 ◽  
Author(s):  
K.M. Bhat ◽  
G. Farkas ◽  
F. Karch ◽  
H. Gyurkovics ◽  
J. Gausz ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chromatin Remodeling ◽  
In Vitro Transcription ◽  
Drosophila Embryo ◽  
Gaga Factor ◽  
Early Drosophila Embryo ◽  
Hypersensitive Sites ◽  
And Function ◽  
Stimulatory Factor

The GAGA protein of Drosophila was first identified as a stimulatory factor in in vitro transcription assays using the engrailed and Ultrabithorax promoters. Subsequent studies have suggested that the GAGA factor promotes transcription by blocking the repressive effects of histones; moreover, it has been shown to function in chromatin remodeling, acting together with other factors in the formation of nuclease hypersensitive sites in vitro. The GAGA factor is encoded by the Trithorax-like locus and in the studies reported here we have used the maternal effect allele Trl13C to examine the functions of the protein during embryogenesis. We find that GAGA is required for the proper expression of a variety of developmental loci that contain GAGA binding sites in their upstream regulatory regions. The observed disruptions in gene expression are consistent with those expected for a factor involved in chromatin remodeling. In addition to facilitating gene expression, the GAGA factor appears to have a more global role in chromosome structure and function. This is suggested by the spectrum of nuclear cleavage cycle defects observed in Trl13C embryos. These defects include asynchrony in the cleavage cycles, failure in chromosome condensation, abnormal chromosome segregation and chromosome fragmentation. These defects are likely to be related to the association of the GAGA protein with heterochromatic satellite sequences which is observed throughout the cell cycle.

scholarly journals A translational block to HSPG synthesis permits BMP signaling in the early Drosophila embryo

Development ◽  
2008 ◽  
Vol 135 (6) ◽  
pp. 1039-1047 ◽  
Author(s):  
D. J. Bornemann ◽  
S. Park ◽  
S. Phin ◽  
R. Warrior
Keyword(s):  
Bmp Signaling ◽  
Drosophila Embryo ◽  
Early Drosophila Embryo ◽  
Translational Block

Implementation of a Five Degree of Freedom Automated System to Determine Knee Flexibility In Vitro

1990 ◽  
Vol 112 (4) ◽  
pp. 392-400 ◽  
Author(s):  
G. S. Berns ◽  
M. L. Hull ◽  
H. A. Patterson
Keyword(s):  
Degrees Of Freedom ◽  
Feedback Loop ◽  
Weight Bearing ◽  
Automated System ◽  
External Torque ◽  
Digitally Controlled ◽  
Definition Of ◽  
Anterior Posterior

This article describes an automated system designed to study the complete flexibility functions of the knee in vitro. The system allows five degrees of freedom with flexion angle being fixed, though adjustable from 0 to 45 deg. Loads corresponding to each of the five motions can be applied independently and in any combination. The effect of weight bearing on knee flexibility can also be studied by including axial force as one of the five loads. The relative motions are measured with LVDT’s and RVDT’s, and the loads are measured with strain gage transducers. The system is digitally controlled with a closed feedback loop, allowing for any combination of programmed loads. A control algorithm on an IBM PC/AT monitors the loads on each axis and continuously adjusts stepping motors to correctly follow programmed loads. The machine coordinate system corresponds to clinically accepted definitions of motion yet retains sequence independence for rotations. Results are presented demonstrating the repeatability of using a functional definition of axis placement to align the leg within the machine. Results are also presented demonstrating the utility of the full flexibility functions of the knee, notably in the determination of significant load interactions between anterior/posterior force and internal/external torque, and varus/valgus torque and internal/external torque.

scholarly journals Spatially uniform establishment of chromatin accessibility in the early Drosophila embryo

2017 ◽  
Author(s):  
Jenna E. Haines ◽  
Michael B. Eisen
Keyword(s):  
Chromatin Accessibility ◽  
Drosophila Embryo ◽  
Direct Result ◽  
Open Chromatin ◽  
Relative Contribution ◽  
Genome Wide ◽  
Zygotic Transcription ◽  
Early Drosophila Embryo ◽  
Nucleosome Density ◽  
Anterior Posterior

AbstractAs the Drosophila embryo transitions from the use of maternal RNAs to zygotic transcription, domains of open chromatin, with relatively low nucleosome density and specific histone marks, are established at promoters and enhancers involved in patterned embryonic transcription. However, it remains unclear whether open chromatin is a product of activity - transcription at promoters and patterning transcription factor binding at enhancers - or whether it is established by independent mechanisms. Recent work has implicated the ubiquitously expressed, maternal factor Zelda in this process. To assess the relative contribution of activity in the establishment of chromatin accessibility, we have probed chromatin accessibility across the anterior-posterior axis of early Drosophila melanogaster embryos by applying a transposon based assay for chromatin accessibility (ATAC-seq) to anterior and posterior halves of hand-dissected, cellular blastoderm embryos. We find that genome-wide chromatin accessibility is remarkably similar between the two halves. Promoters and enhancers that are active in exclusively one half of the embryo have open chromatin in the other half, demonstrating that chromatin accessibility is not a direct result of activity. However, there is a small skew at enhancers that drive transcription exclusively in either the anterior or posterior half of the embryo, with greater accessibility in the region of activity. Taken together these data support a model in which regions of chromatin accessibility are defined and established by ubiquitous factors, and fine-tuned subsequently by activity.

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 THE GENETICS OF THE DORSAL-BICAUDAL-D REGION OF DROSOPHILA MELANOGASTER

Genetics ◽  
1986 ◽  
Vol 113 (3) ◽  
pp. 665-678
Author(s):  
Ruth Steward ◽  
Christiane Nüsslein-Volhard
Keyword(s):  
Maternal Effect ◽  
Complementation Group ◽  
Drosophila Embryo ◽  
Temperature Sensitive ◽  
X Ray ◽  
Dominant Phenotype ◽  
Maternal Effect Genes ◽  
D Region ◽  
Complementation Groups ◽  
Anterior Posterior

ABSTRACT The chromosomal region 36C on 2L contains two maternal-effect loci, dorsal (dl) and Bicaudal-D (Bic-D), which are involved in establishing polarity of the Drosophila embryo along the dorsal-ventral and anterior-posterior axes, respectively. To analyze the region genetically, we isolated X-ray-induced dorsal alleles, which we recognized by virtue of the haplo-insufficient temperature-sensitive dorsal-dominant phenotype in progeny of single females heterozygous for a mutagenized chromosome. From the 20,000 chromosomes tested, we isolated three deficiencies, two inversions with breakpoint in dl and one apparent dl point mutant. One of the deficiencies, Df(2L)H20 (36A6,7; 36F1,2) was used to screen for EMS-induced lethal- and maternal-effect mutants mapping in the vicinity of dl and Bic-D. We isolated 44 lethal mutations defining 11 complementation groups. We also recovered as maternal-effect mutations four dl alleles, as well as six alleles of quail and one allele of kelch, two previously identified maternal-effect genes. Through complementation tests with various viable mutants and deficiencies in the region, a total of 18 loci were identified in an interval of about 30 cytologically visible bands. The region was subdivided into seven subregions by deficiency breakpoints. One lethal complementation group as well as the two maternal loci, Bic-D and quail, are located in the same deficiency interval as is dl.

Primary culture of single ectodermal precursors of Drosophila reveals a dorsoventral prepattern of intrinsic neurogenic and epidermogenic capabilities at the early gastrula stage

Development ◽  
1992 ◽  
Vol 116 (2) ◽  
pp. 377-385 ◽  
Author(s):  
K. Luer ◽  
G.M. Technau
Keyword(s):  
Cell Fate ◽  
Precursor Cells ◽  
Drosophila Embryo ◽  
Original Position ◽  
Division Pattern ◽  
Dorsal Ectoderm ◽  
Development In Vitro ◽  
Almost All

We have analyzed the development in vitro of individual precursor cells from the presumptive truncal segmental ectoderm of the Drosophila embryo to study the intrinsic component in the determination of cell fate. For each cultured cell, the original position within as well as the developmental stage of the donor embryo were known. Cells removed from the ventral neurogenic region develop neural clones. Cells from the dorsal ectoderm and from the dorsalmost part of the ventral neurogenic ectoderm develop epidermal clones. These two classes of clones differ with respect to their division pattern, adhesiveness, cell morphologies and the expression of cell-specific markers. Mixed neural/epidermal clones were obtained from a fraction of precursors at almost all dorsoventral sites. We conclude that, at the onset of gastrulation, precursor cells of the truncal segmental ectoderm already have the capability to develop as either neuroblasts or epidermoblasts in the absence of further cell interactions. At the same time, positional cues distributed along the dorsoventral axis equip precursors with intrinsic preferences towards the neural or epidermal fate, thus defining a prepattern of high neurogenic preferences ventrally, and high epidermogenic preferences dorsally. It is likely that this prepattern is involved in defining the extent of the ventral neurogenic and dorsal epidermogenic regions of the ectoderm. The roles of intrinsic capabilities versus extrinsic influences in the regulation of the characteristic pattern of segregation of the two lineages are discussed.

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