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T R Bürglin

Publications and source records attributed to T R Bürglin.

16 recordsLinked to original sources
PubMed1992

C. elegans unc-4 gene encodes a homeodomain protein that determines the pattern of synaptic input to specific motor neurons.

The creation of neural circuits depends on the formation of synapses between specific sets of neurons. Little is known, however, of the molecular mechanisms governing synaptic choice. A mutation in the unc-4 gene alters the pattern of synaptic input to one class of motor neurons in the Caenorhabditis elegans ventral nerve cord. In unc-4(e120), the presynaptic partners of VA motor neurons are replaced with interneurons appropriate to motor neurons of the VB class. This change in neural specificity is not accompanied by any detectable effects on neuronal morphology or process extension. We show that the absence of a functional unc-4 gene product accounts for the mutant phenotype. The unc-4 gene encodes a homeodomain protein and thus is likely to function as a transcription factor. The limited effect of the unc-4 null mutation on cell fate may mean that unc-4 regulates the expression of a small number of target genes and that the products of these genes are directly involved in the choice of synaptic partners.

Alleles↗
PubMed1992

Prune function?

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Animals↗
PubMed1992

Alternatively spliced transcripts of the flp-1 gene encode distinct FMRFamide-like peptides in Caenorhabditis elegans.

We have isolated and characterized several cDNAs and the corresponding genomic region of a gene encoding multiple FMRFamide-like neuropeptides from the nematode Caenorhabditis elegans. The gene, named flp-1, consists of six exons of which four encode FMRFamide-like peptides. The cDNA and genomic sequences revealed that two distinct transcripts are generated by the use of an alternative 3' splice acceptor site between exons 3 and 4. This alternative splice results in the substitution of AGSDPNFLRFG for one of the copies of SADPNFLRFG found in the other translation product. Based on PCR analysis of RNA from mixed-stage animals, both transcripts are expressed. This gene is the first example of a distinct FMRFamide-like peptide being derived from alternative splicing, suggesting a unique role for the substituted peptide in the animal.

Amino Acid Sequence↗
PubMed1991

Negative regulatory sequences in the lin-14 3'-untranslated region are necessary to generate a temporal switch during Caenorhabditis elegans development.

The heterchronic gene lin-14 controls the temporal sequence of developmental events in the Caenorhabditis elegans postembryonic cell lineage. It encodes a nuclear protein that normally is present in most somatic cells of late embryos and L1 larvae but is absent at later stages. Two lin-14 gain-of-function mutations delete 3'-untranslated sequences causing an inappropriately high level of the lin-14 nuclear protein late in development. These mutations identify a negative regulatory element that controls the formation of the lin-14 protein temporal gradient. The 21-kb lin-14 gene is differentially spliced to generate three lin-14 transcripts that encode protein products with variable amino-terminal regions and a constant carboxy-terminal region. The sequence of the gene revealed no protein sequence similarity to any proteins in various data bases.

Amino Acid Sequence↗
PubMed1989

Caenorhabditis elegans has scores of homoeobox-containing genes.

Homoeobox-containing genes control cell identities in particular spatial domains, cell lineages, or cell types during the development of Drosophila and Caenorhabditis elegans, and they probably control similar processes in vertebrates. More than 80 genes with homoeoboxes that have sequence similarities ranging from 25 to 100% have been isolated by genetic means or by DNA hybridization to previously isolated genes. We synthesized 500-2,000-fold degenerate oligonucleotides corresponding to a set of well-conserved eight amino acid sequences from the helix-3 region of the homoeodomain. We screened C. elegans genomic libraries with these probes and identified 49 putative homoeobox-containing loci. DNA sequencing confirmed that eight out of ten selected loci had sequences corresponding to the conserved helix-3 region plus additional flanking sequence similarity. One of these genes contained a sequence corresponding to a complete pou-domain and another was closely related to the homoeobox-containing genes caudal/cdx-1. The putative homoeobox loci were mapped to the physical contig map of C. elegans, allowing the identification of potentially corresponding genes from the correlated genetic map. We estimate that the number of homoeobox-containing genes in C. elegans is at least 60, constituting approximately 1% of the estimated total number of genes.

Amino Acid Sequence↗
PubMed1987

A Xenopus laevis gene encodes both homeobox-containing and homeobox-less transcripts.

A cDNA clone (p52) that contains all the protein-coding region from the maternally expressed XlHbox 2 locus of the frog Xenopus laevis has been isolated and sequenced. A probe containing the exon preceding the homeobox detected transcripts which arise from a splicing event in which the homeobox-containing exon is replaced by another exon lying 5' to it in the genome. Both the homeobox-containing and homeobox-less splicing event occur in the same tissues, with the homeobox-less RNA representing the minority of mRNA from this gene. There may therefore be a function for two types of transcript, and hence protein, from this locus. This phenomenon may not be exclusive to the XlHbox 2 gene of Xenopus, but might occur more generally in other homeobox-containing genes. The protein deduced from the homeobox-containing cDNA is significantly similar to the yeast mating type factor a1 (MAT-a1) gene product. In addition to the previously described homology of the homeodomains, the amino-terminal domains of XlHbox 2 and MAT-a1 are similar to each other; thus essentially all of the MAT-a1 protein corresponds to some part of the XlHbox 2 protein. In the case of XlHbox 2, the protein coded for by the homeoboxless mRNA would contain all of the non-homeobox homology to yeast MAT-a1.

Amino Acid Sequence↗
PubMed1987

The nuclear migration signal of Xenopus laevis nucleoplasmin.

Nucleoplasmin is the most abundant protein in the nucleus of Xenopus laevis oocytes. Its ability to target to the nucleus when microinjected into the cytoplasm has been the subject of many studies central to our understanding of how proteins segregate into nuclei. Using a cDNA clone we constructed beta-galactosidase-nucleoplasmin hybrids in modified bacterial expression vectors. The fusion proteins were expressed in Escherichia coli, purified and injected into the cytoplasm of X. laevis oocytes. The distribution of the fusion proteins between the cytoplasmic and nuclear compartments were analysed after incubation of various lengths of time. The results show that the signal sequence for nuclear transport is located close to the carboxy terminus of the protein. The signal sequence has been mapped to a small stretch of amino acids, containing a stretch of four lysines analogous to the SV40 large-T antigen signal.

Amino Acid Sequence↗
PubMed1987

Cloning of nucleoplasmin from Xenopus laevis oocytes and analysis of its developmental expression.

Nucleoplasmin is the most abundant protein in the nucleus of Xenopus laevis oocytes. We cloned a cDNA coding for nucleoplasmin from an expression library of immature Xenopus laevis oocytes. The deduced amino acid sequence shows that the carboxyl terminus is very hydrophilic and contains an unusual stretch of 12 glutamic acid residues, which is consistent with one of the proposed functions of nucleoplasmin--that of promoting chromatin assembly. The last 50 amino acids are lysine- and alanine-rich and contain short stretches of homology to histone H1. These regions could be involved in interactions with nucleosomes. The levels of nucleoplasmin mRNA and protein during oogenesis and embryogenesis were investigated using Northern blots, Western blots, and in situ hybridization to oocyte sections. The mRNA is detected during oogenesis but not during embryogenesis, suggesting that nucleoplasmin may be an exclusively maternally expressed gene. However, the protein is present throughout embryogenesis and undergoes pronounced changes in its level of phosphorylation during maturation of the oocyte and just after midblastula transition. These results support the notion that nucleoplasmin is not only important in oocytes but also plays a major role during the rapid cleavages of early embryogenesis.

Amino Acid Sequence↗
PubMed1986

Assembly in vitro of nuclei active in nuclear protein transport: ATP is required for nucleoplasmin accumulation.

DNA (from bacteriophage lambda or Xenopus) is assembled into nucleus-like structures when mixed with an extract from Xenopus eggs. Electron microscopy shows that these in vitro-reconstituted nuclei possess complete double membranes; some, but not all, nuclei have pore complexes. Extracts depleted of their endogenous ATP (by addition of ATPases) cannot assemble nuclear envelopes visible by phase-contrast microscopy. Once synthetic nuclei are assembled, however, they are stable when ATP is subsequently depleted, although their chromatin becomes condensed. About one-fourth of the nuclei assembled in vitro from lambda DNA accumulate nuclear proteins such as nucleoplasmin. ATP depletion blocks nucleoplasmin accumulation both in vitro, in pre-assembled synthetic nuclei, and in vivo, in the nucleus of microinjected oocytes. However, nucleoplasmin previously accumulated by reconstituted nuclei or by the germinal vesicle in microinjected oocytes is retained after ATP depletion.

Adenosine Triphosphate↗
PubMed1986

SEQGEL: a versatile and comfortable DNA editor which supports a special keyboard and a speech synthesizer.

A DNA editor for an Apple II is described which contains many additional functions apart from just editing sequences. The data files are normal ASCII text or binary files and can thus be used easily by other programs. The program supports a special keyboard which greatly facilitates typing of DNA sequences. Furthermore a speech synthesizer is supported by the editor. The speech feedback, together with the special keyboard, reduces typing errors to a minimum.

Base Sequence↗