Tarsus determination in Drosophila melanogaster

Genome ◽  
2005 ◽  
Vol 48 (4) ◽  
pp. 712-721 ◽  
Author(s):  
Anthony Percival-Smith ◽  
Wendy A Teft ◽  
Jodi Lynn Barta
Keyword(s):  
Drosophila Melanogaster ◽  
Ectopic Expression ◽  
Imaginal Discs ◽  
Sex Combs Reduced ◽  
Appendage Development ◽  
Sex Combs ◽  
Ectopic Overexpression ◽  
A Cell ◽  
Hox Protein ◽  
Rule Out

Arista versus tarsus determination is well investigated in Drosophila, yet it remains unresolved whether Antennapedia (ANTP) cell autonomously or noncell autonomously determines tarsus identity and whether Sex combs reduced (SCR) is the HOX protein required for normal tarsus determination. Three observations rule out a cell autonomous role for ANTP in tarsus determination. (i) Clonal ectopic overexpression of ANTP did not repress the expression of the arista determining protein Homothorax (HTH) in early 3rd stadium antennal imaginal discs. (ii) Clonal ectopic expression of ANTP did not transform the arista to a tarsus. (iii) Ectopic overexpression of ANTP, Labial (LAB), Deformed (DFD), SCR, Ultrabithorax (UBX), Abdominal-A (ABD-A), or Abdominal-B (ABD-B), using the dppGAL4 driver, resulted in arista-to-tarsus transformations, and repressed HTH/Extradenticle (EXD) activity noncell autonomously in early 3rd stadium antennal imaginal discs. SCR may not be the HOX protein required for normal tarsus determination, because co-ectopic expression of Proboscipedia (PB) inhibited the arista-to-tarsus transformations induced by ectopic expression of DFD, SCR, ANTP, UBX, ABD-A, and ABD-B. The proposal that SCR is the HOX protein required for normal tarsus determination is dependent on SCR being the sole target of PB suppression, which is not the case. Therefore, the possibility exists that normal tarsus determination is HOX independent.Key words: appendage development, Antennapedia, proboscipedia, sex combs reduced, homothorax.

scholarly journals Analysis in Drosophila melanogaster of the Interaction Between Sex Combs Reduced and Extradenticle Activity in the Determination of Tarsus and Arista Identity

Genetics ◽  
1998 ◽  
Vol 150 (1) ◽  
pp. 189-198
Author(s):  
Anthony Percival-Smith ◽  
Danielle J Hayden
Keyword(s):  
Drosophila Melanogaster ◽  
Imaginal Disc ◽  
Imaginal Discs ◽  
Nuclear Accumulation ◽  
Sex Combs Reduced ◽  
Sex Combs ◽  
Disc Cells

Abstract Sex Combs Reduced (SCR) activity is proposed to be required cell nonautonomously for determination of tarsus identity, and Extradenticle (EXD) activity is required cell autonomously for determination of arista identity. Using the ability of Proboscipedia to inhibit the SCR activity required for determination of tarsus identity, we found that loss-of-EXD activity is epistatic to loss-of-SCR activity in tarsus vs. arista determination. This suggests that in the sequence leading to arista determination SCR activity is OFF while EXD activity is ON, and in the sequence leading to tarsus determination SCR activity is ON, which turns EXD activity OFF. Immunolocalization of EXD in early third-instar larval imaginal discs reveals that EXD is localized in the nuclei of antennal imaginal disc cells and localized in the cytoplasm of distal imaginal leg disc cells. We propose that EXD localized to the nucleus suppresses tarsus determination and activates arista determination. We further propose that in the mesodermal adepithelial cells of the leg imaginal discs, SCR is required for the synthesis of a tarsus-inducer that when secreted acts on the ectoderm cells inhibiting nuclear accumulation of EXD, such that tarsus determination is no longer suppressed and arista determination is no longer activated.

scholarly journals The homeotic gene Sex combs reduced of Drosophila melanogaster is differentially regulated in the embryonic and imaginal stages of development.

Genetics ◽  
1991 ◽  
Vol 129 (2) ◽  
pp. 443-461 ◽  
Author(s):  
A M Pattatucci ◽  
T C Kaufman
Keyword(s):  
Gene Expression ◽  
Drosophila Melanogaster ◽  
Protein Localization ◽  
Regulatory Region ◽  
Imaginal Discs ◽  
Protein Accumulation ◽  
Adult Males ◽  
Gain Of Function ◽  
Sex Combs Reduced ◽  
Sex Combs

Abstract The Sex combs reduced (Scr) locus is unique among the genes contained within the Antennapedia complex (ANT-C) of Drosophila melanogaster in that it directs functions that are required for both cephalic and thoracic development in the embryo and the adult. Antibodies raised against protein encoded by Scr were used to follow the distribution of this gene product in embryos and imaginal discs of third instar larvae. Analysis of Scr protein accumulation in embryos hemizygous for breakpoint lesions mapping throughout the locus has allowed us to determine that sequences required for establishment of the Scr embryonic pattern are contained within a region of DNA that overlaps with the identified upstream regulatory region of the segmentation gene fushi tarazu (ftz). Gain-of-function mutations in Scr result in the presence of ectopic sex comb teeth on the first tarsal segment of mesothoracic and metathoracic legs of adult males. Heterozygous combinations of gain-of-function alleles with a wild-type Scr gene exhibit no evidence of ectopic protein localization in the second and third thoracic segments of embryos. However, mesothoracic and metathoracic leg imaginal discs can be shown to accumulate ectopically expressed Scr protein, implying a differential regulation of the Scr gene during these two periods of development. Additionally, we have found that the spatial pattern of Scr gene expression in imaginal tissues involved in the development of the adult thorax is governed in part by synapsis of homologous chromosomes in this region of the ANT-C. However, those imaginal discs that arise anteriorly to the prothorax do not appear to be sensitive to this form of gene regulation. Finally, we have demonstrated that the extent of Scr expression is influenced by mutations at the Polycomb (Pc) locus but not by mutant alleles of the zeste (z) gene. Taken together, our data suggests that Scr gene expression is differentially regulated both temporally and spatially in a manner that is sensitive to the structure of the locus.

Ectopic expression of homeotic genes caused by the elimination of the Polycomb gene in Drosophila imaginal epidermis

Development ◽  
1988 ◽  
Vol 104 (4) ◽  
pp. 713-720 ◽  
Author(s):  
A. Busturia ◽  
G. Morata
Keyword(s):  
Ectopic Expression ◽  
Homeotic Genes ◽  
Sex Combs Reduced ◽  
Hierarchical Order ◽  
Sex Combs ◽  
Morphological Patterns

The morphological patterns in the adult cuticle of Drosophila are determined principally by the homeotic genes of the bithorax and Antennapedia complexes. We find that many of these genes become indiscriminately active in the adult epidermis when the Pc gene is eliminated. By using the Pc3 mutation and various BX-C mutant combinations, we have generated clones of imaginal cells possessing different combinations of active homeotic genes. We find that, in the absence of BX-C genes, Pc- clones develop prothoracic patterns; this is probably due to the activity of Sex combs reduced which overrules Antennapedia. Adding contributions of Ultrabithorax, abdominal-A and Abdominal-B results in thoracic or abdominal patterns. We have established a hierarchical order among these genes: Antp less than Scr less than Ubx less than abd-A less than Abd-B. In addition, we show that the engrailed gene is ectopically active in Pc- imaginal cells.

scholarly journals Needs and Targets for the multi sex combs Gene Product in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1823-1838 ◽  
Author(s):  
Olivier Saget ◽  
Françoise Forquignon ◽  
Pedro Santamaria ◽  
Neel B Randsholt
Keyword(s):  
Drosophila Melanogaster ◽  
Ectopic Expression ◽  
Polycomb Group ◽  
Homeotic Genes ◽  
Maternal Control ◽  
Gap Gene ◽  
Sex Combs ◽  
Normal Expression ◽  
Selector Genes ◽  
Mutant Phenotypes

Abstract We have analyzed the requirements for the multi sex combs (mxc) gene during development to gain further insight into the mechanisms and developmental processes that depend on the important trans-regulators forming the Polycomb group (PcG) in Drosophila melanogaster. mxc is allelic with the tumor suppressor locus lethal (1) malignant blood neoplasm (l(1)mbn). We show that the mxc product is dramatically needed in most tissues because its loss leads to cell death after a few divisions. mxc has also a strong maternal effect. We find that hypomorphic mxc mutations enhance other PcG gene mutant phenotypes and cause ectopic expression of homeotic genes, confirming that PcG products are cooperatively involved in repression of selector genes outside their normal expression domains. We also demonstrate that the mxc product is needed for imaginal head specification, through regulation of the ANT-C gene Deformed. Our analysis reveals that mxc is involved in the maternal control of early zygotic gap gene expression previously reported for some PcG genes and suggests that the mechanism of this early PcG function could be different from the PcG-mediated regulation of homeotic selector genes later in development. We discuss these data in view of the numerous functions of PcG genes during development.

scholarly journals REVERTANTS OF DOMINANT MUTATIONS ASSOCIATED WITH THE ANTENNAPEDIA GENE COMPLEX OF DROSOPHILA MELANOGASTER: CYTOLOGY AND GENETICS

Genetics ◽  
1983 ◽  
Vol 105 (3) ◽  
pp. 581-600
Author(s):  
T Hazelrigg ◽  
T C Kaufman
Keyword(s):  
Drosophila Melanogaster ◽  
Gene Complex ◽  
Dominant Mutation ◽  
Sex Combs Reduced ◽  
X Ray ◽  
Lethal Mutations ◽  
Sex Combs ◽  
Chromosomal Loci ◽  
Chromosome Bands

ABSTRACT Using X-ray mutagenesis we have induced and recovered phenotypic revertants of four dominant mutations thought to be associated with the Antennapedia complex of Drosophila melanogaster. These include seven revertants of Antennapedia-73b (Antp73b), six of Extra Sex Combs of Wakimoto (Scxw), three of Deformed (Dfd) and one of Humeral (Hu). Fifteen of the 17 revertants are associated with chromosomal aberrations and localize Antp73b, Scxw and Hu to polytene chromosome bands 84B1,2. The Dfd lesion is apparently located in or adjacent to bands 84A4,5. Since all of the dominants are reverted by events that delete their respective chromosomal loci, we conclude that all four are the result of a gain-of-function lesions. Complementation analysis of the various revertant chromosomes has shown that Scxw and Hu are dominant allelic variants of the Antp locus. The Dfd lesion represents a dominant mutation at a locus just proximal to Antp and previously only occupied by recessive lethal mutations. Characterization of the revertants of Scxw and a comparison with the properties of the original mutation has revealed that the original lesion has effects on both the Antp and Sex Combs Reduced (Scr) loci and that these defects are in some cases separable by the reverting event.

scholarly journals A functional and structural analysis of the Sex combs reduced locus of Drosophila melanogaster.

Genetics ◽  
1991 ◽  
Vol 129 (2) ◽  
pp. 423-441 ◽  
Author(s):  
A M Pattatucci ◽  
D C Otteson ◽  
T C Kaufman
Keyword(s):  
Drosophila Melanogaster ◽  
Gene Function ◽  
Molecular Mapping ◽  
Genetic Locus ◽  
Regulatory Region ◽  
Genomic Rearrangements ◽  
Fushi Tarazu ◽  
Sex Combs Reduced ◽  
Sex Combs ◽  
Normal Head

Abstract We have undertaken a developmental genetic analysis of the homeotic gene Sex combs reduced (Scr) of Drosophila melanogaster by examining embryonic and adult phenotypes of mutations affecting Scr gene function. Molecular mapping of Scr breakpoint lesions has defined a segment of greater than 70 kb of DNA necessary for proper Scr gene function. This region is split by the fushi tarazu (ftz) gene, with lesions affecting embryonic Scr function molecularly mapping to the region proximal (5') to ftz and those exhibiting polyphasic semilethality predominantly mapping distal (3') to ftz. Gain-of-function mutations are associated with genomic rearrangements and map throughout the Scr locus. Our analysis has revealed that the Scr locus encompasses genetic elements that are responsible for functions in both the embryonic and larval to adult periods of development. From these studies, we conclude that Scr is a complex genetic locus with an extensive regulatory region that directs functions required for normal head and thoracic development in both the embryo and the adult and that the regulation of Scr during these two periods is distinct.

Ectopic expression and function of the Antp and Scr homeotic genes: the N terminus of the homeodomain is critical to functional specificity

Development ◽  
1993 ◽  
Vol 118 (2) ◽  
pp. 339-352 ◽  
Author(s):  
W. Zeng ◽  
D.J. Andrew ◽  
L.D. Mathies ◽  
M.A. Horner ◽  
M.P. Scott
Keyword(s):  
Dna Binding ◽  
Target Genes ◽  
Ectopic Expression ◽  
Homeotic Genes ◽  
Cell Fates ◽  
Nmr Studies ◽  
Sex Combs Reduced ◽  
Sex Combs ◽  
N Terminus

The transcription factors encoded by homeotic genes determine cell fates during development. Each homeotic protein causes cells to follow a distinct pathway, presumably by differentially regulating downstream ‘target’ genes. The homeodomain, the DNA-binding part of homeotic proteins, is necessary for conferring the specificity of each homeotic protein's action. The two Drosophila homeotic proteins encoded by Antennapedia and Sex combs reduced determine cell fates in the epidermis and internal tissues of the posterior head and thorax. Genes encoding chimeric Antp/Scr proteins were introduced into flies and their effects on morphology and target gene regulation observed. We find that the N terminus of the homeodomain is critical for determining the specific effects of these homeotic proteins in vivo, but other parts of the proteins have some influence as well. The N-terminal part of the homeodomain has been observed, in crystal structures and in NMR studies in solution, to contact the minor groove of the DNA. The different effects of Antennapedia and Sex combs reduced proteins in vivo may depend on differences in DNA binding, protein-protein interactions, or both.

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