Homologous recombination (HR) is a molecular process that plays multiple important roles in DNA metabolism, both for DNA repair and genetic variation in all forms of life1. Generally, HR involves exchange of genetic information between two identical or nearly identical DNA molecules1; however, HR can also occur between RNA molecules, as shown for RNA viruses2. Previous research showed that synthetic RNA oligonucleotides (oligos) can template DNA double-strand break (DSB) repair in yeast and human cells3,4, and artificial long RNA templates injected in ciliate cells can guide genomic rearrangements5. Here we report that endogenous transcript RNA mediates HR with chromosomal DNA in yeast Saccharomyces cerevisiae. We developed a system to detect events of HR initiated by transcript RNA following repair of a chromosomal DSB occurring either in a homologous but remote locus (in trans), or in the same transcript-generating locus (in cis) in reverse transcription defective yeast strains. We found that RNA-DNA recombination is blocked by ribonucleases (RNases) H1 and H2. In the presence of RNases H, DSB repair proceeds through a cDNA intermediate, whereas in their absence, it proceeds directly through RNA. The proximity of the transcript to its chromosomal DNA partner in cis facilitates Rad52-driven HR during DSB repair. In accord, we demonstrate that yeast and human Rad52 proteins efficiently catalyze annealing of RNA to a DSB-like DNA end in vitro. Our results reveal a novel mechanism of HR and DNA repair templated by transcript RNA. Thus, considering the abundance of RNA transcripts in cells, the impact of RNA on genomic stability and plasticity could be vast.

Sexual reproduction may be cryptic or facultative in fungi and therefore difficult to detect. Magnaporthe oryzae, which causes blast, the most damaging fungal disease of rice, is thought to originate from southeast Asia. It reproduces asexually in all rice-growing regions. Sexual reproduction has been suspected in limited areas of southeast Asia, but has never been demonstrated in contemporary populations. We characterized several M. oryzae populations worldwide both biologically and genetically, to identify candidate populations for sexual reproduction. The sexual cycle of M. oryzae requires two strains of opposite mating types, at least one of which is female-fertile, to come into contact. In one Chinese population, the two mating types were found to be present at similar frequencies and almost all strains were female-fertile. Compatible strains from this population completed the sexual cycle in vitro and produced viable progenies. Genotypic richness and linkage disequilibrium data also supported the existence of sexual reproduction in this population. We resampled this population the following year, and the data obtained confirmed the presence of all the biological and genetic characteristics of sexual reproduction. In particular, a considerable genetic reshuffling of alleles was observed between the 2 years. Computer simulations confirmed that the observed genetic characteristics were unlikely to have arisen in the absence of recombination. We therefore concluded that a contemporary population of M. oryzae, pathogenic on rice, reproduces sexually in natura in southeast Asia. Our findings provide evidence for the loss of sexual reproduction by a fungal plant pathogen outside its centre of origin.

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Abstract. We provide a new topological obstruction for complete stable minimal hypersurfaces in IR n+1 . For n ≥ 3, we prove that a complete orientable stable minimal hypersurface in IR n+1 cannot have more than one end by showing the existence of a bounded harmonic function based on the Sobolev inequality for minimal submanifolds [MS] and by applying the Liouville theorem for harmonic functions due to Schoen-Yau [SY].

The identification and utilization of broad-spectrum resistance genes have been proven the most effective and economical approach to control rice blast disease. To understand the molecular mechanism of broad-spectrum resistance to rice blast, we conducted genetic and fine mapping analysis of the blast resistance gene in a Chinese rice variety: Gumei 4 (GM4) identified with broad-spectrum resistance and used in rice breeding for blast resistance for more than 20 years. Genetic and mapping analysis indicated that blast resistance to nine isolates of different Chinese races in GM4 was controlled by the same dominant locus designated as Pigm(t) that was finely mapped to an approximately 70-kb interval between markers C5483 and C0428 on chromosome 6, which contains five candidate NBS--LRR disease resistance genes. The allelism test showed that Pigm(t) was either tightly linked or allelic to Pi2 and Pi9, two known blast resistance genes. Mapping information also indicated that another blast resistance gene Pi26(t) might also be located at the same region. Candidate genes were identified by sequence analysis of the Nipponbare and Pi9 locus and the corresponding region in GM4. Sequence divergence of candidate genes was observed between GM4 and model varieties Nipponbare and 9311, and Pi9. Our current study provides essential information and new genetic resource for the cloning of functional resistance gene(s) and for marker-assisted selection in rice breeding for broad-spectrum blast resistance.

The present study aimed to investigate whether olive leaf extract (OLE) prevents high-fat diet (HFD)-induced obesity in mice and to explore the underlying mechanisms. Mice were randomly divided into groups that received a chow diet (CD), HFD, or 0.15% OLE-supplemented diet (OLD) for 8 weeks. OLD-fed mice showed significantly reduced body weight gain, visceral fat-pad weights, and plasma lipid levels as compared with HFD-fed mice. OLE significantly reversed the HFD-induced upregulation of WNT10b- and galanin-mediated signaling molecules and key adipogenic genes (PPARγ, C/EBPα, CD36, FAS, and leptin) in the epididymal adipose tissue of HFD-fed mice. Furthermore, the HFD-induced downregulation of thermogenic genes involved in uncoupled respiration (SIRT1, PGC1α, and UCP1) and mitochondrial biogenesis (TFAM, NRF-1, and COX2) was also significantly reversed by OLE. These results suggest that OLE exerts beneficial effects against obesity by regulating the expression of genes involved in adipogenesis and thermogenesis in the visceral adipose tissue of HFD-fed mice.

In this paper, we applied Hamilton's Ricci flow to study the metric deformation on Riemannian manifolds with boundary. We proved a short time existence theorem for manifold with umbilical boundary. We also derived the Simons' identity for the boundary under the Ricci flow. And as a corollary, we show that any three-manifold with totally geodesic boundary which admits positive Ricci curvature can be deformed to a space form with totally geodesic boundary.

Abstract. In this paper, we borrowed some ideas from general relativity and find a Robinson-type identity for the overdetermined system of partial differential equations in the Fischer-Marsden conjecture. We proved that if there is a nontrivial solution for such an overdetermined system on a 3-dimensional, closed manifold with positive scalar curvature, then the manifold contains a totally geodesic 2-sphere.Let M denote the set of smooth Riemannian metrics on an n-dimensional closed manifold M whose derivatives are L 2 -integrable. Then for any g ∈ M, its scalar curvature R g is an element in the space W of C ∞ functions. From the formula for R g in local coordinates, we see that the scalar curvature map from M to W defines a quasi-linear differential operator of second order. The derivative R g at g ∈ M is given bywhere δ is the divergence operator on the symmetric p-tensor on M , Ric g is the Ricci curvature tensor of g, ∆ is the Laplacian, and δ * is the formal adjoint of δ. In the Riemannian case, if {e i } n i=1 is a local orthonormal basis of vector fields, thenIn particular, for any one-form α, we havewhere Lα is the Lie derivative of the vector fieldα andα is the dual of α.It is easy to compute that the L 2 -adjoint operator of R g isSince we can regard R g as a linear map from the space of symmetric tensors to the space of functions, so it is known that the following decompositions are true [Be-Eb]: