Leibniz Association

About: Leibniz Association is a government organization based out in Berlin, Germany. It is known for research contribution in the topics: Population & Gene. The organization has 16586 authors who have published 35691 publications receiving 1095107 citations. The organization is also known as: Leibniz-Gemeinschaft & Wissenschaftsgemeinschaft Gottfried Wilhelm Leibniz.

Flg22 regulates the release of an ethylene response factor substrate from MAP kinase 6 in Arabidopsis thaliana via ethylene signaling

Abstract: Mitogen-activated protein kinase (MAPK)–mediated responses are in part regulated by the repertoire of MAPK substrates, which is still poorly elucidated in plants. Here, the in vivo enzyme–substrate interaction of the Arabidopsis thaliana MAP kinase, MPK6, with an ethylene response factor (ERF104) is shown by fluorescence resonance energy transfer. The interaction was rapidly lost in response to flagellin-derived flg22 peptide. This complex disruption requires not only MPK6 activity, which also affects ERF104 stability via phosphorylation, but also ethylene signaling. The latter points to a novel role of ethylene in substrate release, presumably allowing the liberated ERF104 to access target genes. Microarray data show enrichment of GCC motifs in the promoters of ERF104–up-regulated genes, many of which are stress related. ERF104 is a vital regulator of basal immunity, as altered expression in both erf104 and overexpressors led to more growth inhibition by flg22 and enhanced susceptibility to a non-adapted bacterial pathogen.

Phosphate systemically inhibits development of arbuscular mycorrhiza in Petunia hybrida and represses genes involved in mycorrhizal functioning

Abstract: Most terrestrial plants form arbuscular mycorrhiza (AM), mutualistic associations with soil fungi of the order Glomeromycota. The obligate biotrophic fungi trade mineral nutrients, mainly phosphate (P(i) ), for carbohydrates from the plants. Under conditions of high exogenous phosphate supply, when the plant can meet its own P requirements without the fungus, AM are suppressed, an effect which could be interpreted as an active strategy of the plant to limit carbohydrate consumption of the fungus by inhibiting its proliferation in the roots. However, the mechanisms involved in fungal inhibition are poorly understood. Here, we employ a transcriptomic approach to get insight into potential shifts in metabolic activity and symbiotic signalling, and in the defence status of plants exposed to high P(i) levels. We show that in mycorrhizal roots of petunia, a similar set of symbiosis-related genes is expressed as in mycorrhizal roots of Medicago, Lotus and rice. P(i) acts systemically to repress symbiotic gene expression and AM colonization in the root. In established mycorrhizal roots, P(i) repressed symbiotic gene expression rapidly, whereas the inhibition of colonization followed with a lag of more than a week. Taken together, these results suggest that P(i) acts by repressing essential symbiotic genes, in particular genes encoding enzymes of carotenoid and strigolactone biosynthesis, and symbiosis-associated phosphate transporters. The role of these effects in the suppression of symbiosis under high P(i) conditions is discussed.

Deletion of Complement Factor H–Related Genes CFHR1 and CFHR3 Is Associated with Atypical Hemolytic Uremic Syndrome

Abstract: Atypical hemolytic uremic syndrome (aHUS) is associated with defective complement regulation. Disease-associated mutations have been described in the genes encoding the complement regulators complement factor H, membrane cofactor protein, factor B, and factor I. In this study, we show in two independent cohorts of aHUS patients that deletion of two closely related genes, complement factor H–related 1 (CFHR1) and complement factor H–related 3 (CFHR3), increases the risk of aHUS. Amplification analysis and sequencing of genomic DNA of three affected individuals revealed a chromosomal deletion of ∼84 kb in the RCA gene cluster, resulting in loss of the genes coding for CFHR1 and CFHR3, but leaving the genomic structure of factor H intact. The CFHR1 and CFHR3 genes are flanked by long homologous repeats with long interspersed nuclear elements (retrotransposons) and we suggest that nonallelic homologous recombination between these repeats results in the loss of the two genes. Impaired protection of erythrocytes from complement activation is observed in the serum of aHUS patients deficient in CFHR1 and CFHR3, thus suggesting a regulatory role for CFHR1 and CFHR3 in complement activation. The identification of CFHR1/CFHR3 deficiency in aHUS patients may lead to the design of new diagnostic approaches, such as enhanced testing for these genes.

The Mouse Intestinal Bacterial Collection (miBC) provides host-specific insight into cultured diversity and functional potential of the gut microbiota

Abstract: Intestinal bacteria influence mammalian physiology, but many types of bacteria are still uncharacterized. Moreover, reference strains of mouse gut bacteria are not easily available, although mouse models are extensively used in medical research. These are major limitations for the investigation of intestinal microbiomes and their interactions with diet and host. It is thus important to study in detail the diversity and functions of gut microbiota members, including those colonizing the mouse intestine. To address these issues, we aimed at establishing the Mouse Intestinal Bacterial Collection (miBC), a public repository of bacterial strains and associated genomes from the mouse gut, and studied host-specificity of colonization and sequence-based relevance of the resource. The collection includes several strains representing novel species, genera and even one family. Genomic analyses showed that certain species are specific to the mouse intestine and that a minimal consortium of 18 strains covered 50-75% of the known functional potential of metagenomes. The present work will sustain future research on microbiota-host interactions in health and disease, as it will facilitate targeted colonization and molecular studies. The resource is available at www.dsmz.de/miBC.

Characterisation of interphase nanoscale property variations in glass fibre reinforced polypropylene and epoxy resin composites

Abstract: The local microstructure can be altered significantly by various fibre surface modifications, causing property differences between the interphase region and the bulk matrix. By using tapping mode phase imaging and nanoindentation tests based on the atomic force microscope (AFM), a comparative study of the sized fibre surface topography and modulus as well as the local mechanical property variation in the interphase of E-glass fibre reinforced epoxy resin and E-glass fibre reinforced modified polypropylene (PPm) matrix composites was conducted. The phase imaging AFM was found a highly useful tool for probing the interphase with much detailed information. Nanoindentation experiments indicated the chemical interaction during processing caused by a gradient profile in the modulus across the interphase region of γ-aminopropyltriethoxy silane (γ-APS) and polyurethane (PU)-sized glass fibre reinforced epoxy composite. The interphase with γ-APS/PU sizing is much softer than the PPm matrix, while the interphase with the γ-APS/PP sizing is apparently harder than the matrix, in which the modulus was constant and independent of distance away from the fibre surface. The interphase thickness varied between less than 100 and ≈300 nm depending on the type of sizing and matrix materials. Based on a careful analysis of ‘boundary effect’, nanoindentation with sufficient small indentation force was found to enable measuring of actual interphase properties within 100 nm region close to the fibre surface. Special emphasis is placed on the effects of interphase modulus on mechanical properties and fracture behaviour. The interphase with higher modulus and transcrystalline microstructure provided simultaneous increase in the tensile strength and the impact toughness of the composites.