Positioning adjacent pair-rule stripes in the posterior Drosophila embryo

Development ◽  
1994 ◽  
Vol 120 (10) ◽  
pp. 2945-2955 ◽  
Author(s):  
J.A. Langeland ◽  
S.F. Attai ◽  
K. Vorwerk ◽  
S.B. Carroll
Keyword(s):  
Binding Sites ◽  
Drosophila Embryo ◽  
Regulatory Sequences ◽  
Posterior Border ◽  
Adjacent Pair ◽  
Gap Gene ◽  
Competitive Mechanism ◽  
Pair Rule ◽  
Drosophila Embryos ◽  
Do So

We present a genetic and molecular analysis of two hairy (h) pair-rule stripes in order to determine how gradients of gap proteins position adjacent stripes of gene expression in the posterior of Drosophila embryos. We have delimited regulatory sequences critical for the expression of h stripes 5 and 6 to 302 bp and 526 bp fragments, respectively, and assayed the expression of stripe-specific reporter constructs in several gap mutant backgrounds. We demonstrate that posterior stripe boundaries are established by gap protein repressors unique to each stripe: h stripe 5 is repressed by the giant (gt) protein on its posterior border and h stripe 6 is repressed by the hunchback (hb) protein on its posterior border. Interestingly, Kruppel (Kr) limits the anterior expression limits of both stripes and is the only gap gene to do so, indicating that stripes 5 and 6 may be coordinately positioned by the Kr repressor. In contrast to these very similar cases of spatial repression, stripes 5 and 6 appear to be activated by different mechanisms. Stripe 6 is critically dependent upon knirps (kni) for activation, while stripe 5 likely requires a combination of activating proteins (gap and non-gap). To begin a mechanistic understanding of stripe formation, we locate binding sites for the Kr protein in both stripe enhancers. The stripe 6 enhancer contains higher affinity Kr-binding sites than the stripe 5 enhancer, which may allow for the two stripes to be repressed at different Kr protein concentration thresholds. We also demonstrate that the kni activator binds to the stripe 6 enhancer and present evidence for a competitive mechanism of Kr repression of stripe 6.

Concentration-dependent patterning by an ectopic expression domain of the Drosophila gap gene knirps

Development ◽  
1997 ◽  
Vol 124 (7) ◽  
pp. 1343-1354 ◽  
Author(s):  
D. Kosman ◽  
S. Small
Keyword(s):  
Target Genes ◽  
Ectopic Expression ◽  
Drosophila Embryo ◽  
Asymmetric Distribution ◽  
Protein Diffusion ◽  
Expression Domain ◽  
Gap Gene ◽  
Pair Rule Gene ◽  
Transgenic Lines ◽  
Pair Rule

The asymmetric distribution of the gap gene knirps (kni) in discrete expression domains is critical for striped patterns of pair-rule gene expression in the Drosophila embryo. To test whether these domains function as sources of morphogenetic activity, the stripe 2 enhancer of the pair-rule gene even-skipped (eve) was used to express kni in an ectopic position. Manipulating the stripe 2-kni expression constructs and examining transgenic lines with different insertion sites led to the establishment of a series of independent lines that displayed consistently different levels and developmental profiles of expression. Individual lines showed specific disruptions in pair-rule patterning that were correlated with the level and timing of ectopic expression. These results suggest that the ectopic domain acts as a source for morphogenetic activity that specifies regions in the embryo where pair-rule genes can be activated or repressed. Evidence is presented that the level and timing of expression, as well as protein diffusion, are important for determining the specific responses of target genes.

Analysis of maternal effect mutant combinations elucidates regulation and function of the overlap of hunchback and Kruppel gene expression in the Drosophila blastoderm embryo

Development ◽  
1989 ◽  
Vol 107 (3) ◽  
pp. 651-662 ◽  
Author(s):  
U. Gaul ◽  
H. Jackle
Keyword(s):  
Maternal Effect ◽  
Drosophila Embryo ◽  
Homeotic Genes ◽  
Protein Distribution ◽  
Wild Type ◽  
Gap Gene ◽  
Gap Genes ◽  
Underlying Mechanisms ◽  
And Function ◽  
Pair Rule

The metameric organisation of the Drosophila embryo is generated early during development, due to the action of maternal effect and zygotic segmentation and homeotic genes. The gap genes participate in the complex process of pattern formation by providing a link between the maternal and the zygotic gene activities. Under the influence of maternal gene products they become expressed in distinct domains along the anteroposterior axis of the embryo; negative interactions between neighboring gap genes are thought to be involved in establishing the expression domains. The gap gene activities in turn are required for the correct patterning of the pair-rule genes; little is known, however, about the underlying mechanisms. We have monitored the distribution of gap and pair-rule genes in wild-type embryos and in embryos in which the anteroposterior body pattern is greatly simplified due to combinations of maternal effect mutations (staufen exuperantia, vasa exuperantia, vasa exuperantia, bicoid oskar, bicoid oskar torsolike, vasa torso exuperantia). We show that the domains of protein distribution of the gap genes hunchback and Kruppel overlap in wild-type embryos. Based on the analysis of the maternal mutant combinations, we suggest an explanation of how this overlap is generated. Furthermore, our data show that different constellations of gap gene activities provide different input for the pair-rule genes, and thus strongly suggest that the overlap of hunchback and Kruppel in wild-type is functional in the formation of the patterns of pair-rule genes.

scholarly journals Integration of the head and trunk segmentation systems controls cephalic furrow formation in Drosophila

Development ◽  
1997 ◽  
Vol 124 (19) ◽  
pp. 3747-3754 ◽  
Author(s):  
A. Vincent ◽  
J.T. Blankenship ◽  
E. Wieschaus
Keyword(s):  
Initial Step ◽  
Drosophila Embryo ◽  
Germ Band ◽  
Molecular Analyses ◽  
Single Row ◽  
Gap Gene ◽  
Pair Rule Gene ◽  
Integrated Regulation ◽  
Morphogenetic Fields ◽  
Pair Rule

Genetic and molecular analyses of patterning of the Drosophila embryo have shown that the process of segmentation of the head is fundamentally different from the process of segmentation of the trunk. The cephalic furrow (CF), one of the first morphological manifestations of the patterning process, forms at the juxtaposition of these two patterning systems. We report here that the initial step in CF formation is a change in shape and apical positioning of a single row of cells. The anteroposterior position of these initiator cells may be defined by the overlapping expression of the head gap gene buttonhead (btd) and the primary pair-rule gene even-skipped (eve). Re-examination of the btd and eve phenotypes in live embryos indicated that both genes are required for CF formation. Further, Eve expression in initiator cells was found to be dependent upon btd activity. The control of eve expression by btd in these cells is the first indication of a new level of integrated regulation that interfaces the head and trunk segmentation systems. In conjunction with previous data on the btd and eve embryonic phenotypes, our results suggest that interaction between these two genes both controls initiation of a specific morphogenetic movement that separates two morphogenetic fields and contributes to patterning the hinge region that demarcates the procephalon from the segmented germ band.

scholarly journals Gap gene properties of the pair-rule gene runt during Drosophila segmentation

Development ◽  
1994 ◽  
Vol 120 (6) ◽  
pp. 1671-1683 ◽  
Author(s):  
C. Tsai ◽  
J.P. Gergen
Keyword(s):  
Transcriptional Activation ◽  
Expression Patterns ◽  
Normal Component ◽  
Ectopic Expression ◽  
Antagonistic Effect ◽  
Drosophila Embryo ◽  
Gap Gene ◽  
New Family ◽  
Pair Rule Gene ◽  
Pair Rule

The Drosophila Runt protein is a member of a new family of transcriptional regulators that have important roles in processes extending from pattern formation in insect embryos to leukemogenesis in humans. We used ectopic expression to investigate runt's function in the pathway of Drosophila segmentation. Transient over-expression of runt under the control of a Drosophila heat-shock promoter caused stripe-specific defects in the expression patterns of the pair-rule genes hairy and even-skipped but had a more uniform effect on the secondary pair-rule gene fushi tarazu. Surprisingly, the expression of the gap segmentation genes, which are upstream of runt in the segmentation hierarchy was also altered in hs/runt embryos. A subset of these effects were interpreted as due to an antagonistic effect of runt on transcriptional activation by the maternal morphogen bicoid. In support of this, expression of synthetic reporter gene constructs containing oligomerized binding sites for the Bicoid protein was reduced in hs/runt embryos. Finally, genetic experiments demonstrated that regulation of gap gene expression by runt is a normal component of the regulatory program that generates the segmented body pattern of the Drosophila embryo.

Anterior repression of a Drosophila stripe enhancer requires three position-specific mechanisms

Development ◽  
2002 ◽  
Vol 129 (21) ◽  
pp. 4931-4940 ◽  
Author(s):  
Luiz Paulo Moura Andrioli ◽  
Vikram Vasisht ◽  
Ekaterina Theodosopoulou ◽  
Adam Oberstein ◽  
Stephen Small
Keyword(s):  
Binding Sites ◽  
Positional Information ◽  
Common Mechanism ◽  
Sequence Repeat ◽  
Conserved Sequence ◽  
Gap Gene ◽  
Embryo Formation ◽  
Pair Rule Gene ◽  
Specific Position ◽  
Pair Rule

The striped expression pattern of the pair-rule gene even skipped(eve) is established by five stripe-specific enhancers, each of which responds in a unique way to gradients of positional information in the earlyDrosophila embryo. The enhancer for eve stripe 2(eve 2) is directly activated by the morphogens Bicoid (Bcd) and Hunchback (Hb). As these proteins are distributed throughout the anterior half of the embryo, formation of a single stripe requires that enhancer activation is prevented in all nuclei anterior to the stripe 2 position. The gap genegiant (gt) is involved in a repression mechanism that sets the anterior stripe border, but genetic removal of gt (or deletion of Gt-binding sites) causes stripe expansion only in the anterior subregion that lies adjacent to the stripe border. We identify a well-conserved sequence repeat, (GTTT)4, which is required for repression in a more anterior subregion. This site is bound specifically by Sloppy-paired 1 (Slp1),which is expressed in a gap gene-like anterior domain. Ectopic Slp1 activity is sufficient for repression of stripe 2 of the endogenous eve gene,but is not required, suggesting that it is redundant with other anterior factors. Further genetic analysis suggests that the(GTTT)4-mediated mechanism is independent of the Gt-mediated mechanism that sets the anterior stripe border, and suggests that a third mechanism, downregulation of Bcd activity by Torso, prevents activation near the anterior tip. Thus, three distinct mechanisms are required for anterior repression of a single eve enhancer, each in a specific position. Ectopic Slp1 also represses eve stripes 1 and 3 to varying degrees,and the eve 1 and eve 3+7 enhancers each contain GTTT repeats similar to the site in the eve 2 enhancer. These results suggest a common mechanism for preventing anterior activation of three different eve enhancers.

Two distinct mechanisms for differential positioning of gene expression borders involving the Drosophila gap protein giant

Development ◽  
1998 ◽  
Vol 125 (19) ◽  
pp. 3765-3774 ◽  
Author(s):  
X. Wu ◽  
R. Vakani ◽  
S. Small
Keyword(s):  
Target Genes ◽  
Early Embryo ◽  
Drosophila Embryo ◽  
Anterior Border ◽  
Gap Gene ◽  
Gap Genes ◽  
Pair Rule Gene ◽  
Differential Positioning ◽  
Pair Rule

We have combined genetic experiments and a targeted misexpression approach to examine the role of the gap gene giant (gt) in patterning anterior regions of the Drosophila embryo. Our results suggest that gt functions in the repression of three target genes, the gap genes Kruppel (Kr) and hunchback (hb), and the pair-rule gene even-skipped (eve). The anterior border of Kr, which lies 4–5 nucleus diameters posterior to nuclei that express gt mRNA, is set by a threshold repression mechanism involving very low levels of gt protein. In contrast, gt activity is required, but not sufficient for formation of the anterior border of eve stripe 2, which lies adjacent to nuclei that express gt mRNA. We propose that gt's role in forming this border is to potentiate repressive interaction(s) mediated by other factor(s) that are also localized to anterior regions of the early embryo. Finally, gt is required for repression of zygotic hb expression in more anterior regions of the embryo. The differential responses of these target genes to gt repression are critical for the correct positioning and maintenance of segmentation stripes, and normal anterior development.

Ftz-F1 is a cofactor in Ftz activation of the Drosophila engrailed gene

Development ◽  
1997 ◽  
Vol 124 (4) ◽  
pp. 839-847 ◽  
Author(s):  
B. Florence ◽  
A. Guichet ◽  
A. Ephrussi ◽  
A. Laughon
Keyword(s):  
Transcriptional Activation ◽  
Binding Sites ◽  
Direct Contact ◽  
Regulatory Element ◽  
Drosophila Embryo ◽  
Homeodomain Protein ◽  
Reporter Expression ◽  
Fushi Tarazu ◽  
Pair Rule Gene ◽  
Pair Rule

The fushi tarazu pair-rule gene is required for the formation of alternating parasegmental boundaries in the Drosophila embryo. fushi tarazu encodes a homeodomain protein necessary for transcription of the engrailed gene in even-numbered parasegments. Here we report that, within an engrailed enhancer, adjacent and conserved binding sites for the Fushi tarazu protein and a cofactor are each necessary, and together sufficient, for transcriptional activation. Footprinting shows that the cofactor site can be bound specifically by Ftz-F1, a member of the nuclear receptor superfamily. Ftz-F1 and the Fushi tarazu homeodomain bind the sites with 4- to 8-fold cooperativity, suggesting that direct contact between the two proteins may contribute to target recognition. Even parasegmental reporter expression is dependent on Fushi tarazu and maternal Ftz-F1, suggesting that these two proteins are indeed the factors that act upon the two sites in embryos. The two adjacent binding sites are also required for continued activity of the engrailed enhancer after Fushi tarazu protein is no longer detectable, including the period when engrailed, and the enhancer, become dependent upon wingless. We also report the existence of a separate negative regulatory element that apparently responds to odd-skipped.

Ultrabithorax and engrailed expression in Drosophila embryos mutant for segmentation genes of the pair-rule class

Development ◽  
1988 ◽  
Vol 102 (2) ◽  
pp. 325-338 ◽  
Author(s):  
A. Martinez-Arias ◽  
R.A.H. White
Keyword(s):  
Cell Death ◽  
Molecular Probes ◽  
The Body ◽  
Drosophila Embryo ◽  
Segmentation Genes ◽  
Gene Functions ◽  
Pair Rule Gene ◽  
Molecular Phenotypes ◽  
Pair Rule ◽  
Drosophila Embryos

Mutations in the pair-rule class of segmentation genes cause pattern deletions with a double segment periodicity in the Drosophila embryo. This phenotype is, in part, due to cell death. Using molecular probes for engrailed (en) and Ultrabithorax (Ubx) expression as markers for the body plan, we have studied the phenotype of pair-rule mutants prior to cell death. All these mutants alter the expression of en and Ubx; their molecular phenotypes suggest a pathway whereby pair-rule gene functions construct metameric units.

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.

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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