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Long-term climate change and periodic environmental extremes threaten food and fuel security1 and global crop productivity2-4. Although molecular and adaptive breeding strategies can buffer the effects of climatic stress and improve crop resilience5, these approaches require sufficient knowledge of the genes that underlie productivity and adaptation6-knowledge that has been limited to a small number of well-studied model systems. Here we present the assembly and annotation of the large and complex genome of the polyploid bioenergy crop switchgrass (Panicum virgatum). Analysis of biomass and survival among 732 resequenced genotypes, which were grown across 10 common gardens that span 1,800 km of latitude, jointly revealed extensive genomic evidence of climate adaptation. Climate-gene-biomass associations were abundant but varied considerably among deeply diverged gene pools. Furthermore, we found that gene flow accelerated climate adaptation during the postglacial colonization of northern habitats through introgression of alleles from a pre-adapted northern gene pool. The polyploid nature of switchgrass also enhanced adaptive potential through the fractionation of gene function, as there was an increased level of heritable genetic diversity on the nondominant subgenome. In addition to investigating patterns of climate adaptation, the genome resources and gene-trait associations developed here provide breeders with the necessary tools to increase switchgrass yield for the sustainable production of bioenergy.

DNA base damage is a major source of oncogenic mutations1. Such damage can produce strand-phased mutation patterns and multiallelic variation through the process of lesion segregation2. Here we exploited these properties to reveal how strand-asymmetric processes, such as replication and transcription, shape DNA damage and repair. Despite distinct mechanisms of leading and lagging strand replication3,4, we observe identical fidelity and damage tolerance for both strands. For small alkylation adducts of DNA, our results support a model in which the same translesion polymerase is recruited on-the-fly to both replication strands, starkly contrasting the strand asymmetric tolerance of bulky UV-induced adducts5. The accumulation of multiple distinct mutations at the site of persistent lesions provides the means to quantify the relative efficiency of repair processes genome wide and at single-base resolution. At multiple scales, we show DNA damage-induced mutations are largely shaped by the influence of DNA accessibility on repair efficiency, rather than gradients of DNA damage. Finally, we reveal specific genomic conditions that can actively drive oncogenic mutagenesis by corrupting the fidelity of nucleotide excision repair. These results provide insight into how strand-asymmetric mechanisms underlie the formation, tolerance and repair of DNA damage, thereby shaping cancer genome evolution.How strand-asymmetric processes such as replication and transcription interact with DNA damage to drive mechanisms of repair and mutagenesis is explored. [ABSTRACT FROM AUTHOR]

Throughout evolution primate genomes have been modified by waves of retrotransposon insertions. For each wave, the host eventually finds a way to repress retrotransposon transcription and prevent further insertions. In mouse embryonic stem cells, transcriptional silencing of retrotransposons requires KAP1 (also known as TRIM28) and its repressive complex, which can be recruited to target sites by KRAB zinc-finger (KZNF) proteins such as murine-specific ZFP809 which binds to integrated murine leukaemia virus DNA elements and recruits KAP1 to repress them. KZNF genes are one of the fastest growing gene families in primates and this expansion is hypothesized to enable primates to respond to newly emerged retrotransposons. However, the identity of KZNF genes battling retrotransposons currently active in the human genome, such as SINE-VNTR-Alu (SVA) and long interspersed nuclear element 1 (L1), is unknown. Here we show that two primate-specific KZNF genes rapidly evolved to repress these two distinct retrotransposon families shortly after they began to spread in our ancestral genome. ZNF91 underwent a series of structural changes 8-12 million years ago that enabled it to repress SVA elements. ZNF93 evolved earlier to repress the primate L1 lineage until ∼12.5 million years ago when the L1PA3-subfamily of retrotransposons escaped ZNF93's restriction through the removal of the ZNF93-binding site. Our data support a model where KZNF gene expansion limits the activity of newly emerged retrotransposon classes, and this is followed by mutations in these retrotransposons to evade repression, a cycle of events that could explain the rapid expansion of lineage-specific KZNF genes.

The transcriptome is the readout of the genome. Identifying common features in it across distant species can reveal fundamental principles. To this end, the ENCODE and modENCODE consortia have generated large amounts of matched RNA-sequencing data for human, worm and fly. Uniform processing and comprehensive annotation of these data allow comparison across metazoan phyla, extending beyond earlier within-phylum transcriptome comparisons and revealing ancient, conserved features. Specifically, we discover co-expression modules shared across animals, many of which are enriched in developmental genes. Moreover, we use expression patterns to align the stages in worm and fly development and find a novel pairing between worm embryo and fly pupae, in addition to the embryo-to-embryo and larvae-to-larvae pairings. Furthermore, we find that the extent of non-canonical, non-coding transcription is similar in each organism, per base pair. Finally, we find in all three organisms that the gene-expression levels, both coding and non-coding, can be quantitatively predicted from chromatin features at the promoter using a 'universal model' based on a single set of organism-independent parameters.

Oncogenic activation of BRAF fuels cancer growth by constitutively promoting RAS-independent mitogen-activated protein kinase (MAPK) pathway signalling (1). Accordingly, RAF inhibitors have brought substantially improved personalized treatment of metastatic melanoma (2-5). However, these targeted agents have also revealed an unexpected consequence: stimulated growth of certain cancers (6-9). Structurally diverse ATP-competitive RAF inhibitors can either inhibit or paradoxically activate the MAPK pathway, depending whether activation is by BRAF mutation or by an upstream event, such as RAS mutation or receptor tyrosine kinase activation (10-12). Here we have identified next-generation RAF inhibitors (dubbed 'paradox breakers') that suppress mutant BRAF cells without activating the MAPK pathway in cells bearing upstream activation. In cells that express the same HRAS mutation prevalent in squamous tumours from patients treated with RAF inhibitors, the first-generation RAF inhibitor vemurafenib stimulated in vitro and in vivo growth and induced expression of MAPK pathway response genes; by contrast the paradox breakers PLX7904 and PLX8394 had no effect. Paradox breakers also overcame several known mechanisms of resistance to first-generation RAF inhibitors. Dissociating MAPK pathway inhibition from paradoxical activation might yield both improved safety and more durable efficacy than first-generation RAF inhibitors, a concept currently undergoing human clinical evaluation with PLX8394., Selective RAF inhibitors including vemurafenib (13) and dabrafenib (14) have demonstrated both objective tumour response and, in the case of vemurafenib, overall survival benefit in mutant BRAFV600-driven melanoma. The clinical [...]

Author(s): Gernot Wolf [1]; Rita Rebollo [2, 3]; Mohammad M. Karimi [2]; Adam D. Ewing [4]; Rui Kamada [1]; Warren Wu [1]; Brenda Wu [1]; Mahesh Bachu [1]; Keiko Ozato [...]

Proposals to bury plutonium from nuclear weapons must address chemical interactions and intrusion risks, say Cameron L. Tracy, Megan K. Dustin and Rodney C. Ewing., Author(s): Cameron L. Tracy [sup.1] , Megan K. Dustin [sup.2] , Rodney C. Ewing [sup.3] Author Affiliations: (1) Cameron L. Tracy is a MacArthur postdoctoral fellow at the Center for [...]

Author(s): The Honeybee Genome Sequencing Consortium; Overall project leadership: ; George M. Weinstock [1, 2]; Gene E. Robinson [7, 9, 13, 14]; Principal investigators: ; Richard A. Gibbs [1, 2]; [...]

Author(s): Helen Davies [1, 2]; Graham R. Bignell [1, 2]; Charles Cox [1, 2]; Philip Stephens [1, 2]; Sarah Edkins [1]; Sheila Clegg [1]; Jon Teague [1]; Hayley Woffendin [1]; [...]

Cancers arise through the acquisition of oncogenic mutations and grow by clonal expansion1,2. Here we reveal that most mutagenic DNA lesions are not resolved into a mutated DNA base pair within a single cell cycle. Instead, DNA lesions segregate, unrepaired, into daughter cells for multiple cell generations, resulting in the chromosome-scale phasing of subsequent mutations. We characterize this process in mutagen-induced mouse liver tumours and show that DNA replication across persisting lesions can produce multiple alternative alleles in successive cell divisions, thereby generating both multiallelic and combinatorial genetic diversity. The phasing of lesions enables accurate measurement of strand-biased repair processes, quantification of oncogenic selection and fine mapping of sister-chromatid-exchange events. Finally, we demonstrate that lesion segregation is a unifying property of exogenous mutagens, including UV light and chemotherapy agents in human cells and tumours, which has profound implications for the evolution and adaptation of cancer genomes. Mutagenic lesions such as those that give rise to cancer frequently segregate—unrepaired—during cell division, resulting in phasing of multiple alleles across generations of daughter cells and consequent tumour heterogeneity. [ABSTRACT FROM AUTHOR]

Author(s): Theodore J. Bornhorst (corresponding author) [1]; Christopher J. Poulsen [2]; Rodney C. Ewing [3] You recommend uniting universities' natural-history collections at regional hubs to protect them from financial constraints [...]

The world today has a stock of about 500 tonnes of separated plutonium --enough to make 100,000 nuclear weapons (1). As observed in a report (2) by the US National [...]