Segmental patterning of heart precursors in Drosophila

Development ◽  
1995 ◽  
Vol 121 (12) ◽  
pp. 4303-4308 ◽  
Author(s):  
P.A. Lawrence ◽  
R. Bodmer ◽  
J.P. Vincent
Keyword(s):  
Wild Type ◽  
Drosophila Embryos

The mesoderm of Drosophila embryos is segmented; for instance there are segmentally arranged clusters of cells (some of which are heart precursors) that express even-skipped. Expression of even-skipped depends on Wingless, a secreted molecule. In principle, Wingless could act directly in the mesoderm or it could induce the pattern after crossing from ectoderm to mesoderm. Using mosaic embryos, we show that Wingless produced in the mesoderm is sufficient for even-skipped expression. This proves that induction is not essential. However, induction can occur: when patches of wingless mutant mesoderm are overlaid by wild-type ectoderm, they do express even-skipped. We therefore believe that Wingless from both the ectoderm and mesoderm may contribute to patterning the mesoderm. Using the UAS/Gal4 system, we made embryos in which the Wingless protein is uniformly expressed. This is sufficient to rescue the repeated clusters of even-skipped expressing cells, although they are enlarged. We conclude that the mesoderm is segmented in some way not dependent on the distribution of Wingless, suggesting a more permissive and less instructive role for the protein in this instance.

scholarly journals Gene induction following wounding of wild‐type versus macrophage‐deficient Drosophila embryos

EMBO Reports ◽  
2008 ◽  
Vol 9 (5) ◽  
pp. 465-471 ◽  
Author(s):  
Brian Stramer ◽  
Mark Winfield ◽  
Tanya Shaw ◽  
Thomas H Millard ◽  
Sarah Woolner ◽  
...  
Keyword(s):  
Gene Induction ◽  
Type Versus ◽  
Wild Type ◽  
Drosophila Embryos

Segment polarity gene interactions modulate epidermal patterning in Drosophila embryos

Development ◽  
1993 ◽  
Vol 119 (2) ◽  
pp. 501-517 ◽  
Author(s):  
A. Bejsovec ◽  
E. Wieschaus
Keyword(s):  
Cell Types ◽  
Epidermal Cells ◽  
Specific Cell ◽  
Wild Type ◽  
Individual Gene ◽  
Segment Polarity Genes ◽  
Segment Polarity ◽  
Drosophila Larva ◽  
Cuticular Structures ◽  
Drosophila Embryos

Each segment of a Drosophila larva shows a precisely organized pattern of cuticular structures, indicating diverse cellular identities in the underlying epidermis. Mutations in the segment polarity genes alter the cuticle pattern secreted by the epidermal cells; these mutant patterns provide clues about the role that each gene product plays in the development of wild-type epidermal pattern. We have analyzed embryos that are multiply mutant for five key patterning genes: wingless, patched, engrailed, naked and hedgehog. Our results indicate that wild-type activity of these five segment polarity genes can account for most of the ventral pattern elements and that their gene products interact extensively to specify the diverse cellular identities within the epidermis. Two pattern elements can be correlated with individual gene action: wingless is required for formation of naked cuticle and engrailed is required for formation of the first row of denticles in each abdominal denticle belt. The remaining cell types can be produced by different combinations of the five gene activities. wingless activity generates the diversity of cell types within the segment, but each specific cell identity depends on the activity of patched, engrailed, naked and hedgehog. These molecules modulate the distribution and interpretation of wingless signalling activity in the ventral epidermal cells and, in addition, each can contribute to pattern through a pathway independent of the wingless signalling pathway.

Retarded nuclear migration in Drosophila embryos with aberrant F-actin reorganization caused by maternal mutations and by cytochalasin treatment

Development ◽  
1991 ◽  
Vol 111 (4) ◽  
pp. 909-920 ◽  
Author(s):  
K. Hatanaka ◽  
M. Okada
Keyword(s):  
Cytochalasin B ◽  
Anterior Part ◽  
Nuclear Migration ◽  
Yolk Mass ◽  
Wild Type ◽  
Cleavage Stage ◽  
Early Cleavage ◽  
Actin Reorganization ◽  
Actin Organization ◽  
Drosophila Embryos

Three X-linked mutations of Drosophila melanogaster, gs(1)N26, gs(1)N441 and paralog, had a common maternal-effect phenotype. Mutant embryos show reduced egg contraction that normally occurs at an early cleavage stage in wild-type embryos. In addition, the mutants exhibited retarded nuclear migration while synchronous nuclear divisions were unaffected. The retarded migration causes nuclei to remain in the anterior part of the embryo retaining their spherical distribution even in a late cleavage stage. This consequently results in an extreme delay in nuclear arrival in the posterior periplasm. A mutant phenocopy was induced in wild-type embryos that were treated with cytochalasin B or D at a very early cleavage stage. Remarkable differences were noticed in the organization of cortical F-actin between the mutants and the wild type throughout the cleavage stage: obvious F-actin aggregates were dispersed in the cortex of mutant embryos, in contrast to the wild type where the cortical F-actin layer was smooth and underlying F-actin aggregates were smaller than those in the mutants; the transition of the distribution pattern of F-actin in the yolk mass, from the centralized to the fragmented type, occurred later in the mutants than in wild type. The results suggest that these mutations affect the mechanism underlying establishment and transition of F-actin organization required for normal egg contraction and nuclear migration in the cleavage embryos.

scholarly journals The dynamic transmission of positional information in stau- mutants during Drosophila embryogenesis

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Zhe Yang ◽  
Hongcun Zhu ◽  
Kakit Kong ◽  
Xiaoxuan Wu ◽  
Jiayi Chen ◽  
...  
Keyword(s):  
Measurement Errors ◽  
Time Windows ◽  
Positional Information ◽  
Intensity Noise ◽  
Wild Type ◽  
Drosophila Embryogenesis ◽  
Self Organized ◽  
Short Time ◽  
Embryo Length ◽  
Drosophila Embryos

It has been suggested that Staufen (Stau) is key in controlling the variability of the posterior boundary of the Hb anterior domain (xHb). However, the mechanism that underlies this control is elusive. Here, we quantified the dynamic 3D expression of segmentation genes in Drosophila embryos. With improved control of measurement errors, we show that the xHb of stau– mutants reproducibly moves posteriorly by 10% of the embryo length (EL) to the wild type (WT) position in the nuclear cycle (nc) 14, and that its variability over short time windows is comparable to that of the WT. Moreover, for stau– mutants, the upstream Bicoid (Bcd) gradients show equivalent relative intensity noise to that of the WT in nc12–nc14, and the downstream Even-skipped (Eve) and cephalic furrow (CF) show the same positional errors as these factors in WT. Our results indicate that threshold-dependent activation and self-organized filtering are not mutually exclusive and could both be implemented in early Drosophila embryogenesis.

scholarly journals Wingless can bring about a mesoderm-to-ectoderm induction in Drosophila embryos

Development ◽  
1994 ◽  
Vol 120 (12) ◽  
pp. 3355-3359 ◽  
Author(s):  
P.A. Lawrence ◽  
P. Johnston ◽  
J.P. Vincent
Keyword(s):  
Germ Layer ◽  
Wild Type ◽  
Germ Layers ◽  
Genetic Mosaics ◽  
Standard Assay ◽  
In The Wild ◽  
Drosophila Embryos ◽  
Made In

By means of nuclear transplantations, we make mosaics in which largely wingless- embryos contain patches of wingless+ cells. In these genetic mosaics, using a standard assay for wingless function (the maintenance of engrailed expression), we uncover an induction across germ layers: Wingless made in the mesoderm can sustain engrailed expression in the ectoderm. This result makes clear that Wingless is expressed in the mesoderm until at least one hour after gastrulation and may function in this germ layer in the wild type.

Patterned epidermal cell death in wild-type and segment polarity mutant Drosophila embryos

Development ◽  
1998 ◽  
Vol 125 (17) ◽  
pp. 3427-3436 ◽  
Author(s):  
T.M. Pazdera ◽  
P. Janardhan ◽  
J.S. Minden
Keyword(s):  
Cell Death ◽  
Embryonic Development ◽  
Epidermal Cell ◽  
Time Lapse ◽  
Wild Type ◽  
Segment Polarity ◽  
Genetic Perturbations ◽  
Mutant Phenotypes ◽  
Cell Death Pattern ◽  
Drosophila Embryos

Programmed cell death plays an essential role in the normal embryonic development of Drosophila melanogaster. One region of the embryo where cell death occurs, but has not been studied in detail, is the abdominal epidermis. Because cell death is a fleeting process, we have used time-lapse, fluorescence microscopy to map epidermal apoptosis throughout embryonic development. Cell death occurs in a stereotypically striped pattern near both sides of the segment border and to a lesser extent in the middle of the segment. This map of wild-type cell death was used to determine how cell death patterns change in response to genetic perturbations that affect epidermal patterning. Previous studies have suggested that segment polarity mutant phenotypes are partially the result of increased cell death. Mutations in wingless, armadillo, and gooseberry led to dramatic increases in apoptosis in the anterior of the segment while a naked mutation resulted in a dramatic increase in the death of engrailed cells in the posterior of the segment. These results show that segment polarity gene expression is necessary for the survival of specific rows of epidermal cells and may provide insight into the establishment of the wild-type epidermal cell death pattern.

Cell culture of individual Drosophila embryos

Development ◽  
1978 ◽  
Vol 45 (1) ◽  
pp. 161-172
Author(s):  
David P. Cross ◽  
James H. Sang
Keyword(s):  
Fat Body ◽  
Individual Cell ◽  
Cell Types ◽  
Wild Type ◽  
Initial Appearance ◽  
Developmental Capacity ◽  
In Vitro Cell Cultures ◽  
Nerve Muscle ◽  
Drosophila Embryos

A new procedure is described for the preparation of in vitro cell cultures from individual early gastrulae of Drosophila melanogaster. In these cultures several identifiable cell types differentiate within 24 h (nerve, muscle, fat-body, haemocyte and chitin-secreting): their initial appearance and continuing development over a period of weeks is described. It is proposed that this technique may be used to analyse abnormalities of cellular development in embryonic lethal mutants. Culture in vitro of cells from lethal embryos is seen to have two broad roles: (1) to test the developmental capacity of individual cell types in a situation where they are relatively free from possible deleterious interactions with other cell types and are liberated from the system of the dying embryo, and (2) through the preparation of mixed cultures from normal and mutant embryos, to determine the influence of the presence of wild-type cells on observed abnormalities of a particular cell type.

Mechanisms of dorsal-ventral axis determination in Drosophila embryos revealed by cytoplasmic transplantations

Development ◽  
1993 ◽  
Vol 117 (4) ◽  
pp. 1385-1396 ◽  
Author(s):  
S. Roth
Keyword(s):  
Pattern Formation ◽  
Spatial Information ◽  
Vitelline Membrane ◽  
Perivitelline Space ◽  
Protein Distribution ◽  
Wild Type ◽  
Toll Receptor ◽  
Anterior Posterior ◽  
Drosophila Embryos ◽  
Anterior Posterior Axis

The establishment of the dorsal-ventral pattern in Drosophila embryos depends on a signal transduction process: a putative extracellular ligand released into the perivitelline space surrounding the embryo binds to the Toll receptor. Toll activation triggers the formation of the nuclear gradient of dorsal protein, the morphogen of the dorsal-ventral axis. Here, I analyse the dorsal protein distribution and the expression of zygotic dorsal-ventral genes in Toll- embryos that have been injected with wild-type cytoplasm under a variety of different injection conditions. Injections into two positions within a single embryo lead to the formation of two dorsal-ventral patterns in one embryo, allowing the analysis of interactions between pattern-forming processes. The results of single and double injections suggest that the spatial information for the embryonic dorsal-ventral axis is largely derived from spatial cues present in the extraembryonic compartment, which restrict the release of the putative Toll ligand. They argue against a Toll-dependent pattern-formation process employing local self-enhancement and lateral inhibition to enhance a weak initial asymmetry. The putative Toll ligand appears to originate from a ventrally restricted zone which extends along the entire anterior-posterior axis. Ligand diffusion or its graded release are required to determine the slope of the nuclear dorsal protein gradient. Both the Toll receptor and the putative ligand of Toll are in excess in wild-type embryos. Since spatial information for the embryonic dorsal-ventral axis is already present in the vitelline membrane or the perivitelline space, it is most likely generated during oogenesis. Oogenic pattern formation is also responsible for the perpendicular orientation the dorsal-ventral axis maintains with respect to the anterior-posterior axis.

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