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Repetitive DNA sequences located in the terminal portion of the Caenorhabditis elegans chromosomes.

ABSTRACT: We describe the distribution along the chromosomes of Caenorhabditis elegans of two repetitive DNA families, RcS5 and Cerep3 and interstitial telomeric sequences. Both families show, among other interesting features, a preferential location in the terminal 30% of the chromosomes. It is known that in these regions of the genome the frequency of recombination is much higher than in the central portion, genes are rarer and sequences important for chromosome disjunction may lie.

SUBMITTER: Cangiano G

PROVIDER: S-EPMC309273 | biostudies-other | 1993 Mar

REPOSITORIES: biostudies-other

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Repetitive DNA sequences located in the terminal portion of the Caenorhabditis elegans chromosomes.

Cangiano G G La Volpe A A

Nucleic acids research 19930301 5

We describe the distribution along the chromosomes of Caenorhabditis elegans of two repetitive DNA families, RcS5 and Cerep3 and interstitial telomeric sequences. Both families show, among other interesting features, a preferential location in the terminal 30% of the chromosomes. It is known that in these regions of the genome the frequency of recombination is much higher than in the central portion, genes are rarer and sequences important for chromosome disjunction may lie. ...[more]

PMID: 8096635

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Project description:BackgroundThe identity of each neuron is determined by the expression of a distinct group of genes comprising its terminal gene battery. The regulatory sequences that control the expression of such terminal gene batteries in individual neurons is largely unknown. The existence of a complete genome sequence for C. elegans and draft genomes of other nematodes let us use comparative genomics to identify regulatory sequences directing expression in the DVA interneuron.Methodology/principal findingsUsing phylogenetic comparisons of multiple Caenorhabditis species, we identified conserved non-coding sequences in 3 of 10 genes (fax-1, nmr-1, and twk-16) that direct expression of reporter transgenes in DVA and other neurons. The conserved region and flanking sequences in an 85-bp intronic region of the twk-16 gene directs highly restricted expression in DVA. Mutagenesis of this 85 bp region shows that it has at least four regions. The central 53 bp region contains a 29 bp region that represses expression and a 24 bp region that drives broad neuronal expression. Two short flanking regions restrict expression of the twk-16 gene to DVA. A shared GA-rich motif was identified in three of these genes but had opposite effects on expression when mutated in the nmr-1 and twk-16 DVA regulatory elements.Conclusions/significanceWe identified by multi-species conservation regulatory regions within three genes that direct expression in the DVA neuron. We identified four contiguous regions of sequence of the twk-16 gene enhancer with positive and negative effects on expression, which combined to restrict expression to the DVA neuron. For this neuron a single binding site may thus not achieve sufficient specificity for cell specific expression. One of the positive elements, an 8-bp sequence required for expression was identified in silico by sequence comparisons of seven nematode species, demonstrating the potential resolution of expanded multi-species phylogenetic comparisons.

Dataset Information

Repetitive DNA sequences located in the terminal portion of the Caenorhabditis elegans chromosomes.

Publications

Repetitive DNA sequences located in the terminal portion of the Caenorhabditis elegans chromosomes.

Similar Datasets

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