Project description:Mimivirus 1.2Mb genome is organized into a 30 nm nucleocapsid-like structure made of two closely related GMC-oxidoreductases, also composing the fibrils decorating its virions. In this work, we used MS-proteomics to characterize the protein content of virions and fibrils from different members of the Mimiviridae family (clade A: Mimivirus reunion -Mr- and Mimivirus M4 -M4, clade B: Moumouvirus australiensis -Ma- and Moumouvirus maliensis -Mm, clade C: Megavirus chilensis -Mc- and Megavirus vitis -Mv). Furthermore, we analyzed fractions purified from Mr mutants devoid of one of the two GMC-oxidoreductases (Mr_KOqu_143 and Mr_KOqu_946), or of both GMC-oxidoreductases (Mr_2KO) with or without expression of the GFP fused to the N-terminus of one GMC-oxidoreductase (Mr_2KO-GFP). Our results show the versatility of the protein content of the fibrils, with fibrils composed of different proteins inter- and even intra-clade, clades B and C viruses presenting fibrils with a protein composition closer to each other than that of clade A viruses.
Project description:In animals, microRNAs frequently form families with related sequences. The functional relevance of miRNA families and the relative contribution of family members to target repression have remained, however, largely unexplored. Here, we used the C. elegans miR-58 miRNA family, comprised primarily of four highly abundant members: miR-58.1, miR-80, miR-81 and miR-82, as a model to investigate the redundancy of miRNA family members and their impact on target expression in an in vivo setting.
Project description:<p><strong>BACKGROUND:</strong> Plants exhibit wide chemical diversity due to the production of specialized metabolites that function as pollinator attractants, defensive compounds, and signaling molecules. Lamiaceae (mints) are known for their chemodiversity and have been cultivated for use as culinary herbs, as well as sources of insect repellents, health-promoting compounds, and fragrance.</p><p><strong>FINDINGS:</strong> We report the chromosome-scale genome assembly of Callicarpa americana L. (American beautyberry), a species within the early-diverging Callicarpoideae clade of Lamiaceae, known for its metallic purple fruits and use as an insect repellent due to its production of terpenoids. Using long-read sequencing and Hi-C scaffolding, we generated a 506.1-Mb assembly spanning 17 pseudomolecules with N50 contig and N50 scaffold sizes of 7.5 and 29.0 Mb, respectively. In all, 32,164 genes were annotated, including 53 candidate terpene synthases and 47 putative clusters of specialized metabolite biosynthetic pathways. Our analyses revealed 3 putative whole-genome duplication events, which, together with local tandem duplications, contributed to gene family expansion of terpene synthases. Kolavenyl diphosphate is a gateway to many of the bioactive terpenoids in C. americana; experimental validation confirmed that CamTPS2 encodes kolavenyl diphosphate synthase. Syntenic analyses with Tectona grandis L. f. (teak), a member of the Tectonoideae clade of Lamiaceae known for exceptionally strong wood resistant to insects, revealed 963 collinear blocks and 21,297 C. americana syntelogs.</p><p><strong>CONCLUSIONS:</strong> Access to the C. americana genome provides a road map for rapid discovery of genes encoding plant-derived agrichemicals and a key resource for understanding the evolution of chemical diversity in Lamiaceae.</p>
Project description:A central question in transcription factor biology is how a specific member of a transcription factor family occupies a promoter in vivo, when all family members bind the same consensus site in vitro. To uncover the mechanisms regulating DNA binding specificity within transcription factor families, we have used the techniques of chromatin immunoprecipitation coupled with genome-wide microarray analysis to query the occupancy of three members of the ETS transcription factor family in a human T-cell line. Unexpectedly, redundant occupancy was frequently detected while specific occupancy was less likely. An unbiased bioinformatics approach correlated redundant binding with consensus ETS binding sequences near transcription start sites, whereas specific binding sites diverged dramatically from the consensus, were coupled with a site for a cooperative binding partner, and were found further from transcription start sites. The specific and redundant DNA binding modes illustrate the regulation of transcription factor specificity in vivo and suggest two distinct roles for members of the ETS transcription factor family. Keywords: ChIP-chip
Project description:In animals, microRNAs frequently form families with related sequences. The functional relevance of miRNA families and the relative contribution of family members to target repression have remained, however, largely unexplored. Here, we used the C. elegans miR-58 miRNA family, comprised primarily of four highly abundant members: miR-58.1, miR-80, miR-81 and miR-82, as a model to investigate the redundancy of miRNA family members and their impact on target expression in an in vivo setting.