Dataset Information

Maintenance of transposon-free regions throughout vertebrate evolution.

ABSTRACT:

Background

We recently reported the existence of large numbers of regions up to 80 kb long that lack transposon insertions in the human, mouse and opossum genomes. These regions are significantly associated with loci involved in developmental and transcriptional regulation.

Results

Here we report that transposon-free regions (TFRs) are prominent genomic features of amphibian and fish lineages, and that many have been maintained throughout vertebrate evolution, although most transposon-derived sequences have entered these lineages after their divergence. The zebrafish genome contains 470 TFRs over 10 kb and a further 3,951 TFRs over 5 kb, which is comparable to the number identified in mammals. Two thirds of zebrafish TFRs over 10 kb are orthologous to TFRs in at least one mammal, and many have orthologous TFRs in all three mammalian genomes as well as in the genome of Xenopus tropicalis. This indicates that the mechanism responsible for the maintenance of TFRs has been active at these loci for over 450 million years. However, the majority of TFR bases cannot be aligned between distantly related species, demonstrating that TFRs are not the by-product of strong primary sequence conservation. Syntenically conserved TFRs are also more enriched for regulatory genes compared to lineage-specific TFRs.

Conclusion

We suggest that TFRs contain extended regulatory sequences that contribute to the precise expression of genes central to early vertebrate development, and can be used as predictors of important regulatory regions.

SUBMITTER: Simons C

PROVIDER: S-EPMC2241635 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Maintenance of transposon-free regions throughout vertebrate evolution.

Simons Cas C Makunin Igor V IV Pheasant Michael M Mattick John S JS

BMC genomics 20071220

<h4>Background</h4>We recently reported the existence of large numbers of regions up to 80 kb long that lack transposon insertions in the human, mouse and opossum genomes. These regions are significantly associated with loci involved in developmental and transcriptional regulation.<h4>Results</h4>Here we report that transposon-free regions (TFRs) are prominent genomic features of amphibian and fish lineages, and that many have been maintained throughout vertebrate evolution, although most transp ...[more]

PMID: 18093339

Similar Datasets

Project description:This study presents statistical analyses of gene expression during all 40 developmental stages in the teleost Fundulus heteroclitus using four biological replicates per stage. Patterns of gene expression for 7,000 genes appear to be important as they recapitulate developmental timing. Among the 45% of genes with significant expression differences between pairs of temporally adjacent stages, significant differences in gene expression vary from as few as five to more than 660. Five adjacent stages have disproportionately more significant changes in gene expression (>200 genes) relative to other stages: four to eight and eight to sixteen cell stages, onset of circulation, pre- and post-hatch, and during complete yolk absorption. The fewest differences among adjacent stages occur during gastrulation. Yet, at stage 16 (pre-mid-gastrulation), the largest number of genes has peak expression. This stage has an over-representation of genes in oxidative respiration and protein expression (ribosomes, translational genes and proteases). Unexpectedly, among all ribosomal genes, both strong positive and negative correlations occur. Similar correlated patterns of expression occur among all significant genes. These data provide statistical support for the temporal dynamics of developmental gene expression during all stages of vertebrate development. A double-loop design was used for the microarray hybridizations, where each sample is hybridized to 2 arrays using both Cy3- and Cy5-labelled fluorophores (Kerr and Churchill 2001a; Kerr and Churchill 2001b). The loop consisted of Cy3- and Cy5-labelled embryo aRNAs from 4 biological pools for each of 40 stages (S). In total, 160 biological pools were hybridized to 80 microarrays. Each array had different combinations of biological pools (Altman and Hua 2006). The double loop formed was S1M-bM-^FM-^R S2 M-bM-^FM-^R S3M-bM-^FM-^R M-bM-^@M-& S40M-bM-^FM-^R S1 and S40M-bM-^FM-^R S39M-bM-^FM-^R S38M-bM-^FM-^R M-bM-^@M-& S2M-bM-^FM-^R S1 M-bM-^FM-^R S40, where each arrow represents a separate hybridization (array) with the biological pool at the base of the arrow labeled with Cy3 and the biological pool at the head of the arrow labelled with Cy5.

Project description:BackgroundOne of the many gene families that expanded in early vertebrate evolution is the neuropeptide (NPY) receptor family of G-protein coupled receptors. Earlier work by our lab suggested that several of the NPY receptor genes found in extant vertebrates resulted from two genome duplications before the origin of jawed vertebrates (gnathostomes) and one additional genome duplication in the actinopterygian lineage, based on their location on chromosomes sharing several gene families. In this study we have investigated, in five vertebrate genomes, 45 gene families with members close to the NPY receptor genes in the compact genomes of the teleost fishes Tetraodon nigroviridis and Takifugu rubripes. These correspond to Homo sapiens chromosomes 4, 5, 8 and 10.ResultsChromosome regions with conserved synteny were identified and confirmed by phylogenetic analyses in H. sapiens, M. musculus, D. rerio, T. rubripes and T. nigroviridis. 26 gene families, including the NPY receptor genes, (plus 3 described recently by other labs) showed a tree topology consistent with duplications in early vertebrate evolution and in the actinopterygian lineage, thereby supporting expansion through block duplications. Eight gene families had complications that precluded analysis (such as short sequence length or variable number of repeated domains) and another eight families did not support block duplications (because the paralogs in these families seem to have originated in another time window than the proposed genome duplication events). RT-PCR carried out with several tissues in T. rubripes revealed that all five NPY receptors were expressed in the brain and subtypes Y2, Y4 and Y8 were also expressed in peripheral organs.ConclusionWe conclude that the phylogenetic analyses and chromosomal locations of these gene families support duplications of large blocks of genes or even entire chromosomes. Thus, these results are consistent with two early vertebrate tetraploidizations forming a paralogon comprising human chromosomes 4, 5, 8 and 10 and one teleost tetraploidization. The combination of positional and phylogenetic data further strengthens the identification of orthologs and paralogs in the NPY receptor family.

Dataset Information

Maintenance of transposon-free regions throughout vertebrate evolution.

Background

Results

Conclusion

Publications

Maintenance of transposon-free regions throughout vertebrate evolution.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets