Genome-wide binding of posterior HOXA/D transcription factors reveals subgrouping and association with CTCF

Homeotic genes code for key transcription factors (HOX-TFs) that pattern the animal body plan. During embryonic development, Hox genes are expressed in overlapping patterns and function in a partially redundant manner. In vitro biochemical screens probing the HOX-TF sequence specificity revealed largely overlapping sequence preferences, indicating that co-factors might modulate the biological function of HOX-TFs. However, due to their overlapping expression pattern, high protein homology, and insufficiently specific antibodies, little is known about their genome-wide binding preferences. In order to overcome this problem, we virally expressed tagged versions of limb-expressed posterior HOX genes (HOXA9-13, and HOXD9-13) in primary chicken mesenchymal limb progenitor cells (micromass). We determined the effect of each HOX-TF on cellular differentiation (chondrogenesis) and gene expression and found that groups of HOX-TFs induce distinct regulatory programs. We used ChIP-seq to determine their individual genome-wide binding profiles and identified between 12,721 and 28,572 binding sites for each of the nine HOX-TFs. Principal Component Analysis (PCA) of binding profiles revealed that the HOX-TFs are clustered in two subgroups (Group 1: HOXA/D9, HOXA/D10, HOXD12, and HOXA13 and Group 2: HOXA/D11 and HOXD13), which are characterized by differences in their sequence specificity and by the presence of cofactor motifs. Specifically, we identified CTCF binding sites in Group 1, indicating that this subgroup of HOX-proteins cooperates with CTCF. We confirmed this interaction by an independent biological assay (Proximity Ligation Assay) and demonstrated that CTCF is a novel HOX cofactor that specifically associates with Group 1 HOX-TFs, pointing towards a possible interplay between HOX-TFs and chromatin architecture

Genome and transcriptome analysis of the Mesoamerican common bean and the role of gene duplications in establishing tissue and temporal specialization of genes

Background: Legumes are the third largest family of angiosperms and the second most important crop class. Legume genomes have been shaped by extensive large-scale gene duplications, including an approximately 58 million year old whole genome duplication shared by most crop legumes. Results: We report the genome and the transcription atlas of coding and non-coding genes of a Mesoamerican genotype of common bean (Phaseolus vulgaris L., BAT93). Using a comprehensive phylogenomics analysis, we assessed the past and recent evolution of common bean, and traced the diversification of patterns of gene expression following duplication. We find that successive rounds of gene duplications in legumes have shaped tissue and developmental expression, leading to increased levels of specialization in larger gene families. We also find that many long non-coding RNAs are preferentially expressed in germ-line-related tissues (pods and seeds), suggesting that they play a significant role in fruit development. Our results also suggest that most bean-specific gene family expansions, including resistance gene clusters, predate the split of the Mesoamerican and Andean gene pools. Conclusions: The genome and transcriptome data herein generated for a Mesoamerican genotype represent a counterpart to the genomic resources already available for the Andean gene pool. Altogether, this information will allow the genetic dissection of the characters involved in the domestication and adaptation of the crop, and their further implementation in breeding strategies for this important crop.This work was supported by Ibero-American Programme for Science, Technology and Development - CYTED (PhasIbeAm project); Spanish Government - Ministry of Economy and Competitiveness (EUI2009-04052, BIO2011-26205); Brazilian Government — National Council for Scientific and Technological Development - CNPq/Prosul (490725/2010-4) and Brazilian Agricultural Research Corporation - Embrapa (MP2-0212000050000); Ministerio de Ciencia, Tecnología e Innovación Productiva de la República Argentina; the European Molecular Biology Laboratory; Consejo Nacional de Ciencia y Tecnología - Conacyt, Mexico (J010-214-2009) for financial support to undertake parts of research presented in this study. We acknowledge support of the Spanish Ministry of Economy and Competitiveness, ‘Centro de Excelencia Severo Ochoa 2013-2017’, SEV-2012-0208 and Instituto Nacional de Bioinformatica (INB, Project PT13/0001/0021, ISCIII — Subdirección General de Evaluación y Fomento de la Investigación/FEDER “Una Manera de hacer Europa”)

Genomic analysis of the blood attributed to Louis XVI (1754–1793), king of France

A pyrographically decorated gourd, dated to the French Revolution period, has been alleged to contain a handkerchief dipped into the blood of the French king Louis XVI (1754–1793) after his beheading but recent analyses of living males from two Bourbon branches cast doubts on its authenticity. We sequenced the complete genome of the DNA contained in the gourd at low coverage (2.5×) with coding sequences enriched at a higher 7.3× coverage. We found that the ancestry of the gourd's genome does not seem compatible with Louis XVI's known ancestry. From a functional perspective, we did not find an excess of alleles contributing to height despite being described as the tallest person in Court. In addition, the eye colour prediction supported brown eyes, while Louis XVI had blue eyes. This is the first draft genome generated from a person who lived in a recent historical period; however, our results suggest that this sample may not correspond to the alleged king.This work is supported by FEDER and Spanish Government grants BFU2012-38236 and the Spanish Multiple Sclerosis Netowrk (REEM) of the Instituto de Salud Carlos III (RD12/0032/0011) to A.N., BFU2011-28549 and ERC Starting Grant (260372) to T.M.-B. and BFU2012-34157 to C.L.-F. and S.C., and a predoctoral fellowship from the Basque Government (DEUI) to I.

Genomic analysis of the blood attributed to Louis XVI (1754–1793), king of France

A pyrographically decorated gourd, dated to the French Revolution period, has been alleged to contain a handkerchief dipped into the blood of the French king Louis XVI (1754–1793) after his beheading but recent analyses of living males from two Bourbon branches cast doubts on its authenticity. We sequenced the complete genome of the DNA contained in the gourd at low coverage (2.5×) with coding sequences enriched at a higher 7.3× coverage. We found that the ancestry of the gourd's genome does not seem compatible with Louis XVI's known ancestry. From a functional perspective, we did not find an excess of alleles contributing to height despite being described as the tallest person in Court. In addition, the eye colour prediction supported brown eyes, while Louis XVI had blue eyes. This is the first draft genome generated from a person who lived in a recent historical period; however, our results suggest that this sample may not correspond to the alleged king.This work is supported by FEDER and Spanish Government grants BFU2012-38236 and the Spanish Multiple Sclerosis Netowrk (REEM) of the Instituto de Salud Carlos III (RD12/0032/0011) to A.N., BFU2011-28549 and ERC Starting Grant (260372) to T.M.-B. and BFU2012-34157 to C.L.-F. and S.C., and a predoctoral fellowship from the Basque Government (DEUI) to I.