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W J Gehring

Publications and source records attributed to W J Gehring.

At least 145 records · Page 8Linked to original sources
PubMed1985

Control elements of the Drosophila segmentation gene fushi tarazu.

Fushi tarazu (ftz) is one of the Drosophila homeo-box-containing genes required to establish the segmental pattern. Ftz+ transcripts accumulate in cells that form seven equally spaced bands at the blastoderm stage. We have analyzed cis-acting controlling sequences of the ftz gene by germ line transformation. The functional ftz gene includes a transcription unit of 1.9 kb and approximately 6.1 kb of the 5'-flanking sequences. Fusion of the 5'-flanking sequences to the E. coli lacZ gene directs expression of beta-galactosidase in a "zebra" pattern in transformed embryos. The fusion gene is also expressed in certain neuroblasts that contribute to ganglion cells of all segments. Various morphogenetic controlling elements have been identified within the 5'-flanking sequences.

Animals↗
PubMed1984

Functional analysis of the white gene of Drosophila by P-factor-mediated transformation.

A 12-kb DNA segment spanning the white (w) locus of Drosophila has been inserted into a P-transposon vector and used for P-factor-mediated germ-line transformation. Several red-eyed transformants were recovered which complement the white mutant phenotype. Analysis of the eye pigments and the interaction with the zeste mutation indicates that the w gene inserted at several new chromosomal sites is expressed normally. The tissue-specific accumulation of w transcripts, as studied by in situ hybridization to tissue sections, is the same in transformant and wild-type larvae. This indicates that all the genetic information specified by the w locus is contained within this 12-kb segment of DNA. By secondary mobilization it was shown that the w sequences have been inserted as a functional P(w) transposon which is capable of further transposition.

Journal Article↗
PubMed1984

Developmental expression of the white locus of Drosophila melanogaster.

We have isolated several cDNA clones of the white locus which are derived from embryonic and pupal transcripts of Drosophila melanogaster. The cDNA sequences map within 7.5 kb (coordinates -3.0 to +4.6) of the genomic DNA and correspond mainly to sequences within the distal region of the gene (coordinates -0.2 to -3.0). A major RNA species of 2.6 kb was detected on Northerns of poly(A) RNA isolated from all developmental stages. The total accumulation of this transcript peaks in the mature third instar larva to a level of 0.003% which is about ten times higher than that observed in embryos. The spatial distribution of white locus transcripts was determined by in situ hybridization to tissue sections. In embryos, hybridization signals are restricted to the cells of the developing Malpighian tubules and the signal strength corresponds with 50 transcripts per cell. Before the termination of the third instar stage, hybridization signals are also detected at a comparable level in the eye antennal disks. At the same stage, a third site of labeling is observed over a small cluster of cells which seems to be associated with the larval photoreceptor organs. Thus, white locus expression is largely restricted to tissues which are known to be involved in the biosynthesis of eye pigments and these different cell types act in a temporally autonomous manner with respect to the induction of the white gene during development.

Journal Article↗
PubMed1984

Molecular cloning and chromosome mapping of a mouse DNA sequence homologous to homeotic genes of Drosophila.

Some of the homeotic genes of Drosophila, involved in the control of segmental development, form a diverged multigene family. A conserved DNA sequence common to these genes has been used to isolate a clone (Mo-10) from the mouse genome which contains a sequence coding for a protein domain that is homologous to the domain conserved in the Drosophila homeotic genes. By structural analogy, this sequence may be involved in the control of metameric pattern formation in the mouse. Mo-10 has been mapped to the proximal portion of mouse chromosome 6, and its position in relationship to genes known to influence mouse morphogenesis is discussed.

Amino Acid Sequence↗
PubMed1984

A homologous protein-coding sequence in Drosophila homeotic genes and its conservation in other metazoans.

The homeotic genes of the bithorax complex (BX-C) and the Antennapedia complex (ANT-C) of Drosophila appear to specify the developmental fate of segments or parts of segments of the fly. We have previously reported weak DNA sequence homology between 3' portions of the Antennapedia and fushi tarazu genes of the ANT-C and the Ultrabithorax gene of the BX-C. Here we show that this DNA homology (the homeo box) is due to a conserved protein-coding sequence present in these three pattern-formation genes. Thus the functional homology between these developmental controlling genes is reflected in a structural homology in their gene products. The homeo box sequence is also present in a few copies in the genomes of some other invertebrates, and is even conserved in vertebrate genomes, including the human genome. Apparently at least a part of these developmental switch genes from Drosophila is highly conserved during evolution, and might perform an analogous function in many metazoans .

Amino Acid Sequence↗
PubMed1984

Cloning of an X. laevis gene expressed during early embryogenesis coding for a peptide region homologous to Drosophila homeotic genes.

A Xenopus laevis gene was cloned on the basis of cross-homology to a region conserved between several Drosophila homeotic genes. It was shown to be expressed during early development, starting at late gastrulation and producing three transcripts under specific temporal control. The frog gene contains a region coding for 60 amino acids, which is extremely conserved when compared to Drosophila homeotic genes in the region of the homeo domain. Southern blot analysis indicates that there are at least five such sequences in the Xenopus genome. The conserved region is very rich in arginine. This gene could perhaps represent the first development-controlling gene identified in vertebrates.

Animals↗
PubMed1984

Cloning and transcriptional analysis of the segmentation gene fushi tarazu of Drosophila.

In the course of studying the Antennapedia (Antp) locus, we found that one of the 3' Antp exons has weak cross-homology to another gene affecting segmentation, fushi tarazu (ftz; meaning "not enough segments"), which is 30 kb to the left of Antp. Homozygous ftz- embryos die before hatching and lack alternate body segments. The reduced number of segments results from the fusion of the anterior portion of one segment with the posterior portion of the next segment. The ftz gene encodes a single 1.9 kb poly(A)+ RNA expressed exclusively from the early blastoderm to gastrula stages of embryonic development. The structure of the ftz gene has been analyzed by S1 nuclease mapping and by restriction mapping of a cDNA clone. The ftz gene consists of two exons, and it is the 3' exon that cross-hybridizes with the 3' exon of Antp. The role of ftz in cell determination is discussed.

Animals↗
PubMed1984

Spatial distribution of transcripts from the segmentation gene fushi tarazu during Drosophila embryonic development.

The locus fushi tarazu appears to be involved in the establishment of the segmentation pattern of the Drosophila embryo. The cuticle of ftz mutant embryos is missing structures in alternating segments such that only half the normal number of segments are present. We have localized ftz+ transcripts in tissue sections of wild-type Drosophila embryos by in situ hybridization. Transcripts from the ftz+ gene were first detected during nuclear cleavage prior to cell formation. During the last two nuclear divisions ftz+ transcription becomes gradually restricted such that at the cellular blastoderm stage the ftz+ transcripts are localized in seven evenly spaced bands of cells. The size of each band is similar to the size of the segment primordia at the blastoderm. By the time segmentation becomes morphologically distinct ftz+ transcripts are no longer detected. These results suggest that the ftz+ gene plays a key role in the determination of the segmentation pattern in the embryo.

Animals↗
PubMed1984

Differentiation markers in the Drosophila ovary.

A library of monoclonal antibodies, raised against imaginal discs of Drosophila melanogaster, was screened for binding to differentiation antigens in the adult ovary by immunofluorescence. Several lectins were similarly assayed. Two antibodies, DOV 1 and DOV 2, and wheat germ agglutinin exhibited binding which was restricted to particular stages of ovarian cell differentiation. DOV 2 also showed a marked preferential binding to the cell surface of germ line cells in the ovary. A differentiation of the portion of the tunica propria covering the anterior part of the germarium was revealed by the monoclonal antibody DOV 3. Another monoclonal antibody, DOV 4, identified a molecular specialization of the chorion at the tip of the micropyle. These markers should provide tools for the molecular analysis of oogenesis.

Animals↗
PubMed1983

An improved in situ hybridization method for the detection of cellular RNAs in Drosophila tissue sections and its application for localizing transcripts of the homeotic Antennapedia gene complex.

An improved method for the detection of cellular RNAs in tissue sections has been developed. It involves in situ hybridization of tritium-labeled cloned DNA probes to tissue sections and autoradiography. The method was calibrated by using a cloned DNA probe complementary to transcripts abundant in the midgut cells of Drosophila larvae. The improved method also permitted the detection of these transcripts in sectioned embryos where they are much less abundant. The sensitivity of the method can be approximated by quantifying the signal intensities over the hybridizing embryonic midgut cells relative to the larval midgut cells for which the number of transcripts has been estimated. Based on these calculations we estimate that the method is sensitive enough to detect 100 complementary RNA molecules per cell after 3 days of autoradiographic exposure with a signal-to-noise ratio of 10. The method has been successfully applied to detect transcripts of the homeotic gene Antennapedia. Serial sections allow us to study the spatial pattern of gene expression in the course of development.

Journal Article↗
PubMed1983

Molecular analysis of large transposable elements carrying the white locus of Drosophila melanogaster.

A large transposable element (TE) comprising the white-apricot and roughest genes has been found to transpose to well over a hundred sites scattered over the Drosophila genome. We report the cloning of the essential parts of several TEs. TE98 and TE28 sequences were cloned by ;walking' along the chromosome from the previously cloned heatshock genes. The ends of the TEs are characterized by dispersed repetitive elements belonging to the foldback (FB) family. FB elements are also associated with two independently isolated transposable elements originating from the white locus, Tp w-1 and Tp w. The strong correlation between FB elements and large composite transposons suggests that a pair of these elements can mobilize large intermediary DNA segments. One particular FB family member, FB-NOF, is associated with TE28, the white-crimson (w) mutant, the w-derived Tp w-1 and probably also with Tp w. A unique sequence located close to the white end of TE28 was used to clone the borders of TE77 and the surrounding sequences in the bithorax region, indicating that the TE can be used as a probe for gene isolation. Some evolutionary implications of the large composite transposons are discussed.

Journal Article↗
PubMed1983

Genomic and cDNA clones of the homeotic locus Antennapedia in Drosophila.

Homeotic genes are involved in the control of developmental pathways: dominant mutations at the Antennapedia locus of Drosophila, for example, lead to replacement of the antennae on the head of the fly by mesothoracic legs. Using a combination of chromosome walking and jumping, we have cloned a DNA region from Drosophila containing Antennapedia. Five DNA inversion rearrangements which are associated with the Antennapedia mutant phenotype were localized within a 25-kb region. Genomic DNA sequences from this area were used as hybridization probes to screen cDNA libraries prepared from Drosophila embryonic and pupal poly(A)+ RNA. A 2.2-kb cDNA sequence (903) was isolated which appears to derive from at least four non-contiguous chromosomal regions that span 100 kb. It includes the positions of the inversion breakpoints. A second cDNA of 2.9 kb (909) is composed of sequences from at least three chromosomal regions, two of which are similar or identical to sequences contained in the 903 clone but the third is derived from genomic DNA within a putative 903 intron. The unusual size and complexity of this locus are discussed.

Animals↗
PubMed1983

Spatial distribution of Antennapedia transcripts during Drosophila development.

We have localized transcripts specified by the homeotic Antennapedia (Antp) locus within serial tissue sections of Drosophila embryos and larvae by in situ hybridization. As a hybridization probe we used a 2.2-kb cDNA sequence (903) which is complementary to at least four non-contiguous chromosomal DNA regions within a span of 100 kb derived from the Antp+ locus. The tritiated probe was directly hybridized to frozen tissue sections of wild-type embryos and larvae. Hybridization was first detected to the progenitors of the thoracic segments during the cellularization of the syncytial blastoderm, when embryonic cells first become determined to form particular adult segments. At later embryonic stages the ventral nervous system also becomes labeled in a spatially-restricted manner. Initially, accumulation of transcripts is detected in all thoracic and abdominal ganglia of the ventral cord. Subsequently, the highest concentration of transcripts is detected in the ganglion cells of the mesothorax. Proper development of this segment is known to be affected in individuals homozygous for putative Antp null alleles. In third-instar larvae, hybridization to the different imaginal disks of all three thoracic segments is observed, localized mainly to those regions that will form proximal, cuticular portions of the respective segments. These results are discussed with respect to the role of homeotic genes in the specification of particular anatomical segments.

Animals↗
PubMed1983

Unequal crossing-over associated with asymmetrical synapsis between nomadic elements in the Drosophila melanogaster genome.

The molecular structure of reciprocal duplications and deficiencies produced by unequal crossing-over at the white (w) locus of Drosophila melanogaster females heterozygous for the alleles w(a) and w(a4) has been examined. A transposable, copia-like element is found at the rearrangement breakpoints. Further characterization indicates that asymmetrical pairing between two copies of this element, which are at least 60 kilobases apart in the parental chromosomes, followed by a crossover within the paired elements, is responsible for the duplication and deficiencies observed. The frequency of these events is high compared with normal homologous exchange, implying that synaptic pairing during meiosis must be sufficiently flexible as to allow efficient recognition of sequences located in nonidentical positions on homologous chromosomes. These results suggest a possible mechanism for the generation of tandem duplications in eukaryotic organisms.

Journal Article↗