Anti-angiogenic VEGFAxxxb transcripts are not expressed in the medio-basal hypothalamus of the seasonal sheep

Source at https://doi.org/10.1371/journal.pone.0197123.This study investigated Vegfa expression in the pars tuberalis (PT) of the pituitary and medio-basal hypothalamus (MBH) of sheep, across seasons and reproductive states. It has recently been proposed that season impacts alternative splicing of Vegfa mRNA in the PT, which shifts the balance between angiogenic VEGFAxxx and anti-angiogenic VEGFAxxxb isoforms (with xxx the number of amino acids of the mature VEGFA proteins) to modulate seasonal breeding. Here, we used various RT-PCR methodologies and analysis of RNAseq datasets to investigate seasonal variation in expression and splicing of the ovine Vegfa gene. Collectively, we identify 5 different transcripts for Vegfa within the ewe PT/MBH, which correspond to splicing events previously described in mouse and human. All identified transcripts encode angiogenic VEGFAxxx isoforms, with no evidence for alternative splicing within exon 8. These findings led us to investigate in detail how “Vegfaxxxb-like” PCR products could be generated by RT-PCR and misidentified as endogenous transcripts, in sheep and human HEK293 cells. In conclusion, our findings do not support the existence of anti-angiogenic VEGFAxxxb isoforms in the ovine PT/MBH and shed new light on the interpretation of prior studies, which claimed to identify Vegfaxxxb isoforms by RT-PCR

Whole genome surveys of rice, maize and sorghum reveal multiple horizontal transfers of the LTR-retrotransposon Route66 in Poaceae

<p>Abstract</p> <p>Background</p> <p>Horizontal transfers (HTs) refer to the transmission of genetic material between phylogenetically distant species. Although most of the cases of HTs described so far concern genes, there is increasing evidence that some involve transposable elements (TEs) in Eukaryotes. The availability of the full genome sequence of two cereal species, (<it>i.e</it>. rice and <it>Sorghum</it>), as well as the partial genome sequence of maize, provides the opportunity to carry out genome-wide searches for TE-HTs in <it>Poaceae</it>.</p> <p>Results</p> <p>We have identified an LTR-retrotransposon, that we named <it>Route66</it>, with more than 95% sequence identity between rice and <it>Sorghum</it>. Using a combination of <it>in silico </it>and molecular approaches, we are able to present a substantial phylogenetic evidence that <it>Route66 </it>has been transferred horizontally between Panicoideae and several species of the genus <it>Oryza</it>. In addition, we show that it has remained active after these transfers.</p> <p>Conclusion</p> <p>This study constitutes a new case of HTs for an LTR-retrotransposon and we strongly believe that this mechanism could play a major role in the life cycle of transposable elements. We therefore propose to integrate classe I elements into the previous model of transposable element evolution through horizontal transfers.</p

First landscape of binding to chromosomes for a domesticated mariner transposase in the human genome: diversity of genomic targets of SETMAR isoforms in two colorectal cell lines

Setmar is a 3-exons gene coding a SET domain fused to a Hsmar1 transposase. Its different transcripts theoretically encode 8 isoforms with SET moieties differently spliced. In vitro, the largest isoform binds specifically to Hsmar1 DNA ends and with no specificity to DNA when it is associated with hPso4. In colon cell lines, we found they bind specifically to two chromosomal targets depending probably on the isoform, Hsmar1 ends and sites with no conserved motifs. We also discovered that the isoforms profile was different between cell lines and patient tissues, suggesting the isoforms encoded by this gene in healthy cells and their functions are currently not investigated

Paleogenomic Analysis of the Short Arm of Chromosome 3 Reveals the History of the African and Asian Progenitors of Cultivated Rices

Rice is one of the most important crops, feeding more than half of the world population. There are two cultivated species, the African rice Oryza glaberrima and the Asian rice O. sativa. Although the African species is gradually replaced by O. sativa in most of African rice agrosystems, this species represents an important reservoir of genes of agronomical interest. Their exploitation for the development of modern African rice varieties requires a good understanding of the genetic relationships between the two cultivated species. We took advantage of the recent availability of the sequence of the chromosome 3 short arm of O. glaberrima to estimate the date of radiation between O. glaberrima and O. sativa lineages, using all the long terminal repeat (LTR)-retrotransposons as paleogenomic markers. We first demonstrated that in two distinct lineages, LTR-retrotransposons mutate at the same rate. Based on LTR-retrotransposons shared by both species in orthologous position, we then estimated that O. glaberrima and O. sativa progenitors diverged 1.2 Ma. This constitutes one of the first studies using such a large sample of transposable elements to reconstruct the phylogeny of species. Given the number of genome sequencing projects, there is no doubt that such approach will allow to resolve phylogenetic incongruities. The application of this method to other plant genomes will also facilitate further understanding of evolution of LTR-retrotransposons and eventually of the whole genome in divergent plant lineages

DensityMap: a genome viewer for illustrating the densities of features

Several tools are available for visualizing genomic data. Some, such as Gbrowse and Jbrowse, are very efficient for small genomic regions, but they are not suitable for entire genomes. Others, like Phenogram and CViT, can be used to visualise whole genomes, but are not designed to display very dense genomic features (eg: interspersed repeats). We have therefore developed DensityMap, a lightweight Perl program that can display the densities of several features (genes, ncRNA, cpg, etc.) along chromosomes on the scale of the whole genome. A critical advantage of DensityMap is that it uses GFF annotation files directly to compute the densities of features without needing additional information from the user. The resulting picture is readily configurable, and the colour scales used can be customized for a best fit to the data plotted.DensityMap runs on Linux architecture with few requirements so that users can easily and quickly visualize the distributions and densities of genomic features for an entire genome. The input is GFF3-formated data representing chromosomes (linkage groups or pseudomolecules) and sets of features which are used to calculate representations in density maps. In practise, DensityMap uses a tilling window to compute the density of one or more features and the number of bases covered by these features along chromosomes. The densities are represented by colour scales that can be customized to highlight critical points. DensityMap can compare the distributions of features; it calculates several chromosomal density maps in a single image, each of which describes a different genomic feature. It can also use the genome nucleotide sequence to compute and plot a density map of the GC content along chromosomes.DensityMap is a compact, easily-used tool for displaying the distribution and density of all types of genomic features within a genome. It is flexible enough to visualize the densities of several types of features in a single representation. The images produced are readily configurable and their SVG format ensures that they can be edited

The future of transposable element annotation and their classification in the light of functional genomics - what we can learn from the fables of Jean de la Fontaine?

International audienceTransposable element (TE) science has been significantly influenced by the pioneering ideas of David Finnegan near the end of the last century, as well as by the classification systems that were subsequently developed. Today, whole genome TE annotation is mostly done using tools that were developed to aid gene annotation rather than to specifically study TEs. We argue that further progress in the TE field is impeded both by current TE classification schemes and by a failure to recognize that TE biology is fundamentally different from that of multicellular organisms. Novel genome wide TE annotation methods are helping to redefine our understanding of TE sequence origins and evolution. We briefly discuss some of these new methods as well as ideas for possible alternative classification schemes. Our hope is to encourage the formation of a society to organize a larger debate on these questions and to promote the adoption of standards for annotation and an improved TE classification

Genes Encoding Teleost Fish Ligands and Associated Receptors Remained in Duplicate More Frequently than the Rest of the Genome

International audienceSignaling through ligand/receptor interactions is a widespread mechanism across all living taxa. During evolution, however, there has been a diversification in multigene families and changes in their interaction patterns. Among the events that led to the creation of new genes is the whole-genome duplication, which made possible some major innovations. Teleost fishes descended from a common ancestor which underwent one such whole-genome duplication. In our study, we investigated the effect of complete genome duplication on the evolution of ligand-receptor pairs in teleosts. We selected ten teleost species and used bioinformatics programs and phylogenetic tools in order to study the evolution of the human ligands and receptors that have orthologous genes in fishes, as well as the rest of the fish genomes. We established that since the complete duplication of the fish genomes, the conservation in duplicate copy of ligand and receptor genes is higher than expected. However, the ligand/receptor pair partners did not necessarily evolve in the same way, and a lot of situations occurred in which one of the partners returned in singleton copy when the other one was maintained in duplicate. This suggests that changes in interaction partners may have taken place during the evolution of teleosts. Moreover, the fate of the ligands and receptor coding genes is partly congruent with the phylogeny of teleosts. However, some incongruences can be observed. We suggest that these incongruences are correlated to the environment

The chicken repeated sequences

National audienc

But where did the centromeres go in the chicken genome models?

International audienceThe chicken genome was the third vertebrate to be sequenced. To date, its sequence and feature annotations are used as the reference for avian models in genome sequencing projects developed on birds and other Sauropsida species, and in genetic studies of domesticated birds of economic and evolutionary biology interest. Therefore, an accurate description of this genome model is important to a wide number of scientists. Here, we review the location and features of a very basic element, the centromeres of chromosomes in the galGal5 genome model. Centromeres are elements that are not determined by their DNA sequence but by their epigenetic status, in particular by the accumulation of the histone-like protein CENP-A. Comparison of data from several public sources (primarily marker probes flanking centromeres using fluorescent in situ hybridization done on giant lampbrush chromosomes and CENP-A ChIP-seq datasets) with galGal5 annotations revealed that centromeres are likely inappropriately mapped in 9 of the 16 galGal5 chromosome models in which they are described. Analysis of karyology data confirmed that the location of the main CENP-A peaks in chromosomes is the best means of locating the centromeres in 25 galGal5 chromosome models, the majority of which (16) are fully sequenced and assembled. This data re-analysis reaffirms that several sources of information should be examined to produce accurate genome annotations, particularly for basic structures such as centromeres that are epigenetically determined