Fushi Tarazu Expression Research Articles

Isolation and expression analysis of FTZ-F1 encoding gene of black rock fish (Sebastes schlegelii)

Sex related FTZ-F1 is a transcriptional factor regulating the expression of fushi tarazu (a member of the orphan nuclear receptors) gene. In this study, FTZ-F1 gene (FTZ-F1) was isolated from the testis of black rockfish (Sebastes schlegeli) by homology cloning. The full-length cDNA of S. schlegeli FTZ-F1 (ssFTZ-F1) contained a 232bp 5′ UTR, a 1449bp ORF encoding FTZ-F1 (482 amino acid residules in length) with an estimated molecular weight of 5.4kD and a 105bp 3′ UTR. Sequence, tissue distribution and phylogenic analysis showed that ssFTZ-F1 belonged to FTZ group, holding highly conserved regions including I, II and III FTZ-F1 boxes and an AF-2 hexamer. Relatively high expression was observed at different larva stages. In juveniles (105 days old), the transcript of ssFTZ-F1 can be detected in all tissues and the abuncance of the gene transcript in testis, ovary, spleen and brain was higher than that in other tissues. In mature fish, the abundance of gene transcript was higher in testis, ovary, spleen and brain than that in liver (trace amount), and the gene was not transcribed in other tissues. The highest abundance of gene transcript was always observed in gonads of both juvenile and mature fish. In addition, the abundance of gene transcript in male tissues were higher than that in female tissue counterparts (P<0.05).

Low-level ectopic expression of Fushi tarazu in Drosophila melanogaster results in ftz Ual/Rpl-like phenotypes and rescues ftz phenotypes

The protein encoded by the Drosophila pair-rule gene fushi tarazu (ftz) is required for the formation of the even-numbered parasegments. Here we analyze the phenotypes of ectopic expression of FTZ and FTZ protein deletions from the Tubulin α1 ( Tubα1) promoter. Fusion of ftz to the Tubα1 promoter resulted in low-level ectopic expression of FTZ relative to FTZ expressed from the endogenous ftz gene. The effects of ectopic expression of four FTZ proteins, FTZ 1–413 (full length wild-type FTZ), FTZ Δ257–316 (a complete deletion of the HD), FTZ Δ101–150 (a deletion that includes the major FTZ-F1 binding site) and FTZ Δ151–209 were determined. Ectopic expression of FTZ 1–413, FTZ Δ257–316 and FTZ Δ101–151 did not result in an anti-ftz phenotype; however, ectopic expression of FTZ 1–413, and FTZ Δ257–316 did result in a ftz Ual/Rpl-like phenotype. In addition, low-level ectopic expression of FTZ 1–413 and FTZ Δ257–316 rescued ftz phenotypes. This was an important observation because the even-numbered parasegment pattern of FTZ expression is considered important for normal segmentation. Therefore, the rescue of ftz phenotypes by low-level FTZ expression in all cells of the embryo suggests that the even-numbered parasegment expression pattern of FTZ is not the sole factor restricting FTZ action. Low-level ectopic expression of FTZ Δ151–209 resulted in the anti-ftz phenotype and rescued hypomorphic ftz-f1 phenotypes indicating that FTZ Δ151–209 is a hyperactive FTZ molecule. Therefore, the region encompassing amino acids 151–209 of FTZ is required in some manner for repression of FTZ activity. These results are discussed in relation to the current understanding of the mechanism of FTZ action.

Establishing Parasegments in Drosophila Embryos: Roles of the odd-skipped and naked Genes

During Drosophila embryogenesis, a genetic cascade establishes repeating developmental units, the parasegments, along the anterior-posterior axis. Anterior and posterior boundaries of parasegments are defined by narrow stripes of cells expressing the segment polarity genes engrailed and wingless , respectively. Through single and double mutant analysis, we describe genetic interactions regulating the precise activation of engrailed and wingless in alternate parasegments. The pair-rule gene odd-skipped and the segment polarity gene naked are both required to restrict engrailed expression. odd-skipped represses expression of fushi tarazu, a known activator of engrailed. naked prevents activation of engrailed by fushi tarazu, without affecting fushi tarazu expression. engrailed expression is thus limited to narrow stripes of cells at the anterior boundaries of these parasegments. wingless expression is regulated by both odd-skipped and the pair-rule gene paired. odd-skipped represses wingless expression, while paired restricts the domain of expression of odd-skipped. wingless expression is thus allowed in narrow stripes of cells at the posterior boundaries of these parasegments. Accurate expression of engrailed and wingless is also required for cells within each parasegment to assume their proper positional identity. In odd-skipped mutants, the positional identities of particular cells are changed, creating mirror-image duplications of the body pattern. We present a model describing how the altered expression patterns of fushi tarazu, engrailed, and wingless generate the mutant phenotype.

Dax, a locust Hox gene related to fushi-tarazu but showing no pair-rule expression.

We describe an unusual Antennapedia class homeobox gene from the grasshopper Schistocerca gregaria (Orthoptera, African Plague Locust). Its sequence is not sufficiently similar to that of any other insect Hom-Hox gene to identify it unambiguously, but short conserved elements suggest a relationship to the segmentation gene fushi-tarazu, (ftz). We term it Sg Dax (divergent Antennapedia class homeobox gene). Antibodies raised against the protein encoded by this gene reveal two phases of expression during embryogenesis. In the early embryo, it is a marker for the posterior part of the forming embryonic primordium, and subsequently for the posterior part of the growing germ band. In older embryos, it labels a subset of neural precursor cells in each trunk segment, very similar to that defined by the expression of fushi tarazu (ftz) in Drosophila. We suggest that Schistocerca Dax and Drosophila ftz are homologous members of a gene family whose members are diverging relatively rapidly, both in terms of sequence and role in early development.

Distribution and function of the lethal of scute gene product during early neurogenesis in Drosophila

Genes of the achaete-scute complex (ASC) participate in the formation of the central nervous system in the Drosophila embryo. Previous genetic analyses have indicated that lethal of scute (l'sc) is the most important gene of the complex in that process. We have obtained antibodies against the l'sc protein to study the expression of the gene during early neurogenesis. The protein is found in groups of embryonic neuroectodermal cells, analogous to the proneural clusters that precede the appearance of precursors of peripheral sensory organs in imaginal epithelia. The groups appear in different regions of the neuroectoderm, accompanying the three successive waves of neuroblast segregation. Most neuroblasts delaminate from these clusters and express position-specific levels of l'sc protein. No significant differences have been found between the distribution of l'sc RNA and protein. Phenotypic analysis of a l'sc deficiency has shown that the gene is required for neuroblast commitment, although this requirement is less widespread than the domain of l'sc expression, suggesting a high degree of redundancy in the function of genes that participate in the process of neuroblast segregation. The ASC genes have been postulated to play a role in the control of NB identity, revealed by the generation of a defined lineage of identifiable neurons. However, our study in l'sc mutants of the expression of fushi tarazu, engrailed, and even-skipped, used as markers of neuronal identity, has not provided evidence to support this hypothesis.

Control of the initiation of homeotic gene expression by the gap genes giant and tailless in Drosophila

The process of segmentation in Drosophila is controlled by both maternal and zygotic genes. Members of the gap class of segmentation genes play a key role in this process by interpreting maternal information and controlling the expression of pair-rule and homeotic genes. We have analyzed the pattern of expression of a variety of homeotic, pair-rule, and gap genes in tailless and giant gap mutants. tailless acts in two domains, one anterodorsal and one posterior. In its anterior domain tailless exerts a repressive effect on the expression of fushi tarazu, hunchback, and Deformed. In its posterior domain of action, tailless is responsible for the establishment of Abdominal-B expression and demarcating the posterior boundary of the initial domain of expression of Ultrabithorax. giant is an early zygotic regulator of the gap gene hunchback: in giant- embryos, alterations in the anterior domain of hunchback expression are visible by the beginning of cycle 14. giant also regulates the establishment of the expression patterns of Antennapedia and Abdominal-B. In particular, giant is the factor that controls the anterior limit of early Antennapedia expression.

Reciprocal effects of hyper- and hypoactivity mutations in the Drosophila pattern gene torso.

In Drosophila, five "terminal" polarity genes must be active in females in order for them to produce embryos with normal anterior and posterior ends. Hypoactivity mutations in one such gene, torso, result in the loss of the most posterior domain of fushi tarazu expression and the terminal cuticular structures. In contrast, a torso hyperactivity mutation causes the loss of central fushi tarazu expression and central cuticular structures. Cytoplasmic leakage, transplantation, and temperature-shift experiments suggest that the latter effect is caused by abnormal persistence of the torso product in the central region of the embryo during early development. Thus, the amount and timing of torso activity is key to distinguishing the central and terminal regions of the embryo. Mutations in the tailless terminal gene act as dominant maternal suppressors of the hyperactive torso allele, indicating that the torso product acts through, or in concert with, the tailless product.

Cytoarchitecture and the patterning of fushi tarazu expression in the Drosophila blastoderm.

In the Drosophila embryo at the blastoderm stage, the segmentation gene fushi tarazu (ftz) is expressed in a seven-banded pattern. The generation of this pattern, like many other segmentation gene expression patterns, coincides with the formation of cell membranes around the blastoderm nuclei. To test the role of cellularization in resolving the banded ftz pattern, we used cytoskeletal inhibitors (colcemid and cytochalasin B) to block cellularization. We found that banded ftz RNA and protein patterns can form without cellular structure. We also tested the importance of rapid degradation of the ftz RNA, using cycloheximide to block degradation. RNA degradation is essential to maintain the banded ftz pattern in a syncytium, but is not required to maintain the pattern in a cellularized embryo. A latticework of cytoskeletal microtubules that forms during cellularization appears to be a key component in localizing the ftz mRNA. We conclude that RNA degradation and cellular structure normally work together to localize ftz RNA to its sites of synthesis.

Pattern abnormalities induced by ectopic expression of the Drosophila gene hairy are associated with repression of ftz transcription

The pair-rule segmentation gene hairy (h) is expressed and required in alternate metameres in the early Drosophila embryo. We show that h expression outside these domains, driven by an hsp70 promoter, suppresses the expression of fushi tarazu (ftz). The kinetics of action favor h acting directly as a transcriptional repressor. The resulting pattern defects, and the patterns of en and Ubx activity, can be explained if h acts via ftz and other pair-rule genes in the establishment of stable en domains. We present evidence that ftz is required for the initiation of Ubx transcription, but not for its maintenance.

Complementary patterns of even-skipped and fushi tarazu expression involve their differential regulation by a common set of segmentation genes in Drosophila.

We have examined the position-dependent expression of two segmentation genes that contain a homeo box, even-skipped (eve) and fushi tarazu (ftz). Products encoded by both genes accumulate in a series of seven transverse stripes along the anterior-posterior body axis of developing embryos. Double-staining experiments show that eve and ftz proteins accumulate in complementary sets of embryonic cells. A total of eight zygotically active segmentation genes are required for the establishment and refinement of the eve and ftz expression patterns during development. Mutations that affect one of the genes were always found to produce a reciprocal alteration in the other. These results suggest that the eve and ftz promoters independently "interpret" the same positional cues to give differential patterns of expression. We propose that a combination of segmentation gene products that activates the expression of eve represses the expression of ftz, and vice versa. This proposal is discussed in the context of a hierarchy of interactions among segmentation genes, whereby the gap genes establish asymmetric patterns of eve and ftz expression in blastoderm-stage embryos, and interactions with other pair-rule genes serve to refine further the complementarity of eve and ftz expression during gastrulation and germ band elongation.

Independence of fushi tarazu expression with respect to cellular density in Drosophila embryos.

Regularly spaced repeated morphological structures are a common developmental theme among higher eukaryotes. In Drosophila, this is evident in the repeated segments of the larval and the adult cuticle. It has been demonstrated through cell transplantation and more recently through molecular techniques that these repeated segmental units are established as early as nuclear cycle 14 in the blastoderm embryo. A number of genes have been shown to express their transcripts, and in two instances their protein products, in a spatially restricted manner at this early stage. Immunofluorescence probes against the protein product of one such gene, fushi tarazu (ftz), reveal that it is distributed in seven evenly spaced stripes across the cellularized cycle-14 blastoderm embryo. The mechanisms that determine such spatial patterns of gene expression are of fundamental importance for the development of multicellular organisms, but in no case are they well understood. Here we examine the ftz pattern on blastoderm embryos derived from maternal-haploid 1182 (mh 1182) and daughterless-abo-like (dal) females which possess cell densities and sizes both above and below the wild-type levels. The number, spacing and width of the ftz protein positive bands are not altered in these abnormal embryos relative to the wild-type pattern, suggesting that the mechanism by which distance is measured with respect to the ftz protein is independent of cell size and density.