Publications by authors named "Andreas Bachmann"

Polyploids, which arise from whole-genome duplication events, have contributed to genome evolution throughout eukaryotes. Among plants, novel features of neopolyploids include traits that can be evolutionarily or agriculturally beneficial, such as increased abiotic stress tolerance. Thus, in addition to being interesting from an evolutionary perspective, genome duplication is also increasingly recognized as a promising crop improvement tool.

View Article and Find Full Text PDF

Current diagnostic methods for evaluating the functionality of the lymphatic vascular system usually do not provide quantitative data and suffer from many limitations including high costs, complexity, and the need to perform them in hospital settings. In this work, we present a quantitative, simple outpatient technology named LymphMonitor to quantitatively assess lymphatic function. This method is based on the painless injection of the lymphatic-specific near-infrared fluorescent tracer indocyanine green complexed with human serum albumin, using MicronJet600 microneedles, and monitoring the disappearance of the fluorescence signal at the injection site over time using a portable detection device named LymphMeter.

View Article and Find Full Text PDF

Epigenetic regulation of cell and tissue function requires the coordinated action of transcription factors. However, their combinatorial activities during regeneration remain largely unexplored. Here, we discover an unexpected interaction between the cytoprotective transcription factor NRF2 and p63- a key player in epithelial morphogenesis.

View Article and Find Full Text PDF

In nature, individual histones in the same nucleosome can carry identical (symmetric) or different (asymmetric) post-translational modification (PTM) patterns, increasing the combinatorial complexity. Embryonic stem cells exhibit "bivalent" nucleosomes, some of which are marked by an asymmetric arrangement of H3K36me3 (an activating PTM) and H3K27me3 (a repressive PTM). Here we describe a modular synthetic method to access such asymmetrically modified nucleosomes and show that H3K36me3 inhibits the activity of the methyltransferase PRC2 locally while still prolonging its chromatin binding time.

View Article and Find Full Text PDF

The regulation of fundamental processes such as gene expression or cell differentiation involves chromatin states, demarcated by combinatorial histone post-translational modification (PTM) patterns. The subnuclear organization and dynamics of chromatin states is not well understood, as tools for their detection and modulation in live cells are lacking. Here, we report the development of genetically encoded chromatin-sensing multivalent probes, cMAPs, selective for bivalent chromatin, a PTM pattern associated with pluripotency in embryonic stem cells (ESCs).

View Article and Find Full Text PDF

Polycomb repressive complex 2 (PRC2) trimethylates histone H3 at lysine 27 to mark genes for repression. We measured the dynamics of PRC2 binding on recombinant chromatin and free DNA at the single-molecule level using total internal reflection fluorescence (TIRF) microscopy. PRC2 preferentially binds free DNA with multisecond residence time and midnanomolar affinity.

View Article and Find Full Text PDF

Chromatin recruitment of effector proteins involved in gene regulation depends on multivalent interaction with histone post-translational modifications (PTMs) and structural features of the chromatin fiber. Due to the complex interactions involved, it is currently not understood how effectors dynamically sample the chromatin landscape. Here, we dissect the dynamic chromatin interactions of a family of multivalent effectors, heterochromatin protein 1 (HP1) proteins, using single-molecule fluorescence imaging and computational modeling.

View Article and Find Full Text PDF

Many site-selective palladium-catalyzed C-H functionalization methods require directing groups. We report here β-carboline amides as intrinsic directing groups for C(sp)-H functionalization. Various substrates including the natural product alangiobussinine and the marinacarboline core structure were functionalized using carboline-directed δ-C(sp)-H alkynylations.

View Article and Find Full Text PDF

Multivalent interactions between effector proteins and histone post-translational modifications are an elementary mechanism of dynamic chromatin signalling. Here we elucidate the mechanism how heterochromatin protein 1α (HP1α), a multivalent effector, is efficiently recruited to the silent chromatin state (marked by trimethylated H3 at Lys9, H3K9me3) while remaining highly dynamic. Employing chemically defined nucleosome arrays together with single-molecule total internal reflection fluorescence microscopy (smTIRFM), we demonstrate that the HP1α residence time on chromatin depends on the density of H3K9me3, as dissociated factors can rapidly rebind at neighbouring sites.

View Article and Find Full Text PDF

The Nrf2 transcription factor controls the expression of genes involved in the antioxidant defense system. Here, we identified Nrf2 as a novel regulator of desmosomes in the epidermis through the regulation of microRNAs. On Nrf2 activation, expression of miR-29a and miR-29b increases in cultured human keratinocytes and in mouse epidermis.

View Article and Find Full Text PDF