Over-expression of miR166a inhibits cotyledon formation in somatic embryos and promotes lateral root development in seedlings of Larix leptolepis

Somatic embryo (SE) regeneration is an ideal experimental system to realize rapid propagation of excellent clones and genetic improvement for perennial gymnosperms. In the present study, genes encoding the miRNA166 precursor were identified and LamiR166a was successfully transformed into the gymnosperm Larix leptolepis (L. leptolepis) and five LamiR166a over-expressed embryonic cell lines were screened out as stable embryo masses. As expected, the targets of miR166a, LaHDZ31-34, were all down-regulated in transgenic lines according to qRT-PCR results. The results showed that the percentage of normal SEs with 4–7 cotyledons was 77.0?% in wild type (WT) lines, but was reduced to 60.3?% in the pSuper::MIR166a lines with “cup-shaped” embryos comprised 7.0?% of WT and 20.7?% of transgenic embryos. Microscopic observation further showed that the intermediate region surrounded by the cotyledons was larger than in the control, with no upward bulge of the shoot apical meristem (SAM). The expression pattern of the two meristem marker genes CLAVATA (CLV) and WUSCHEL-related homeobox (WOX) were investigated. The results showed that the expression levels of WOX were three times higher in transgenic lines than in WT samples, which suggest that miR166a may indirectly regulate SAM development by directly affecting WOX expression. Besides, overexpression of LamiR166a clearly increased the rooting rate and promoted lateral root formation in L. leptolepis seedlings. These results may provide new insights into the regulatory role of miR166 in gymnosperms, and also new applications for forestry production in practice.     

Retraction Note to: Enhancement of the catalytic activity of ferulic acid decarboxylase from Enterobacter sp. Px6-4 through random and site-directed mutagenesis

Applied Microbiology and Biotechnology -     

ATP‐dependent DNA binding,unwinding, and resection by the Mre11/Rad50 complex

ATP‐dependent DNA end recognition and nucleolytic processing are central functions of the Mre11/Rad50 (MR) complex in DNA double‐strand break repair. However, it is still unclear how ATP binding and hydrolysis primes the MR function and regulates repair pathway choice in cells. Here, Methanococcus jannaschii MR‐ATPγS‐DNA structure reveals that the partly deformed DNA runs symmetrically across central groove between two ATPγS‐bound Rad50 nucleotide‐binding domains. Duplex DNA cannot access the Mre11 active site in the ATP‐free full‐length MR complex. ATP hydrolysis drives rotation of the nucleotide‐binding domain and induces the DNA melting so that the substrate DNA can access Mre11. Our findings suggest that the ATP hydrolysis‐driven conformational changes in both DNA and the MR complex coordinate the melting and endonuclease activity.     

The macroecology of infectious diseases: a new perspective on global‐scale drivers of pathogen distributions and impacts

Identifying drivers of infectious disease patterns and impacts at the broadest scales of organisation is one of the most crucial challenges for modern science, yet answers to many fundamental questions remain elusive. These include what factors commonly facilitate transmission of pathogens to novel host species, what drives variation in immune investment among host species, and more generally what drives global patterns of parasite diversity and distribution? Here we consider how the perspectives and tools of macroecology, a field that investigates patterns and processes at broad spatial, temporal and taxonomic scales, are expanding scientific understanding of global infectious disease ecology. In particular, emerging approaches are providing new insights about scaling properties across all living taxa, and new strategies for mapping pathogen biodiversity and infection risk. Ultimately, macroecology is establishing a framework to more accurately predict global patterns of infectious disease distribution and emergence.