tharris's Chung:MA [16 articles]

Abstract

We have isolated a C. elegans homolog of the Drosophila forkhead and rodent HNF-3 genes. In the DNA-binding domain, the amino acid matches between the C. elegans gene (called Cefkh-1) and forkhead/HNF-3 genes are in the range of 75-80%. Northern analysis shows that Cefkh-1 message can be detected in all stages of development but is at least 5 - 10 fold higher in embryos. A combination of cDNA cloning, primer extension and RT-PCR has defined three distinct transcripts, two of which ...

Abstract

The C. elegans ges-1 gene codes for a gut- specific esterase first expressed at the 4-8E cell stage of development and is a convenient marker to study intestine development.. We are interested in the factors that bind to the control region of the ges-1 gene to bring about its regulation. Promoter mutagenesis experiments has shown two "WGATAR" motifs to be crucial for the correct spatial expression pattern of the ges-1 gene. Expression screening using GATA-binding motifs yielded a positive cDNA clone ...

Abstract

The ges-1 gene codes for a non-specific carboxylesterase that is expressed only in cells of the gut lineage. We are taking several approaches to investigate the control of ges-1 expression: deletion analysis, in VIVO competition, and cross-species transformation. Deletion analysis: Transformation of ges-1(0J mutants with a 5'deletion series of the ges-1 gene reveals two unexpected behaviours: (1) the pattern of ges-1 expression switches from the gut into muscle cells of the (sister) MS-lineage or into muscle and hypodermis cells of the ...

Abstract

C. elegans fkh-1 is a homolog of the Drosophila forkhead and rodent HNF-3 genes with greater than 75% identity within the DNA binding domains. We are interested in determining whether fkh-1 has an important developmental role in endoderm formation, like the Drosophila and rodent genes. Northerns show that fkh-1 transcripts are expressed at highest levels in embryos. In situ hybridization shows that these transcripts are present both in the gut and pharynx of pre-morphogenic embryos. By the comma stage, transcripts are ...

Abstract

The C. elegans GATA transcription factor elt-2 was cloned by expression screening using GATA binding motifs from the promoter of the gut specific ges-1 gene (1). Previous promoter analysis has shown that these GATA motifs are crucial for the correct gut specific expression of ges-1 (2, 3). Furthermore ELT-2 protein has been demonstrated to bind specifically to these motifs by gel mobility shift assays. Using anti-ELT-2 antibody as well as elt-2::lacZ (or GFP) reporter constructs, we have now shown that elt-2 ...

Abstract

How do gene regulation pathways evolve? Comparison of a homologous gene in related species, such as C. elegans and C. briggsae, provides a starting point for addressing this problem. The gene ges-1 (gut esterase) has been previously cloned from both C. elegans and C. briggsae, and found to be 75% identical within the coding region at the DNA level (83% at the protein level); however, surrounding DNA sequences show little overall sequence conservation (Kennedy et al., 1993). Promoter analysis of the ...

Abstract

We had previously reported (Aamodt et al., Science 252, 579-582, 1991) that a number of 5'-deletions of the normally gut-specific ges-1 gene, when transformed into the ges-1 (0)strain, caused esterase expression, not in the gut, but in the posterior part of the pharynx (along with a cell in the tail that we tentatively identified as mu Int R). These patterns were seen with both "transient" transformation and with heritable transformation (the latter, using either the unc-22 antisense or the rol-6 phenotypic ...

Abstract

To identify the control regions of the C. elegans gut-specific esterase gene (ges-1), we are using a variety of approaches including a comparison of the upstream control regions of ges-1 and the homologous esterase gene from C. briggsae (cloned and sequenced from the Baillie library by Brian Kennedy and Fran Allen). For this approach to be valid, we needed to show that the esterase gene from one species is properly expressed in the other species. It was easy to show that ...

Abstract

We have cloned a member of the fork head/HNF-3 family of transcription factors from the nematode Caenorhabditis elegans. Within the predicted DNA binding domain, this gene, called Ce-fkh-1, is 75-78% identical to the Drosophila fork head and rat liver HNF-3 alpha, beta, and gamma genes. Ce-fkh-1 mRNA is highly enriched in embryos. The Ce-fkh-1 gene produces three major transcripts: the longest mRNA retains its original 5'-end but two shorter mRNAs are trans-spliced at the beginning of exons 2 and 3, respectively. ...

Abstract

The Caenorhabditis elegans ges-1 gene (gut esterase No. 1) is expressed only in the intestinal lineage, beginning when the developing gut has only four to eight cells. We analyze the sequence requirements for this tissue-specific gene regulation by injecting deleted/mutated constructs of the ges-1 gene into a viable ges-1 (null) strain of worms and assaying heritably transformed embryos by esterase histochemistry. Many deletion constructs accurately reconstitute the wildtype gut-specific ges-1 expression. However, deletions in the neighborhood of 1100 bp upstream of ...

Abstract

The ges-1 gene codes for a non-specific carboxylesterase that is normally expressed only in the intestine of the nematode Caenorhabditis elegans. In the current paper, we describe the cloning and characterization of the ges-1 gene from C. elegans, as well as the homologous gene from the nematode Caenorhabditis briggsae. The ges-1 esterases from the two nematodes are 83% identical at the amino acid level and contain regions of significant similarity to insect and mammalian esterases; these conserved regions can be identified ...

Abstract

We describe an acid phosphatase enzyme (EC 3.1.3.2) that is localized to the intestine of the nematode Caenorhabditis elegans and that should serve as a convenient biochemical marker for gut differentiation. In adult worms, acid phosphatase activity is located along the edge of the gut lumen in the vicinity of the intestinal brush border. All but the anterior six cells of the intestine stain for phosphatase activity; the nonstaining cells all descend from the Ea(l/r)(a/p)a cells. Acid phosphatase activity is low ...

Abstract

The nematode Caenorhabditis elegans was transformed with constructs containing upstream deletions of the gut-specific ges-1 carboxylesterase gene. With particular deletions, ges-1 was expressed, not as normally in the gut, but rather in muscle cells of the pharynx (which belong to a sister lineage of the gut) or in body wall muscle and hypodermal cells (which belong to a cousin lineage of the gut). These observations suggest that gut-specific gene expression in C. elegans involves not only gut-specific activators but also multiple ...

Abstract

The ges-1 gene of the nematode Caenorhabditis elegans codes for a nonspecific carboxylesterase that is expressed only in the intestinal lineage. This esterase has turned out to be a convenient biochemical marker for lineage-specific differentiation. In the present paper, we describe the production of several C. elegans strains that lack detectable activity of the ges-1 esterase. To isolate these ges-1 null strains, we first produced a strain of hermaphrodites in which the wild-type copy of the ges-1 gene was stably balanced ...