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Journal of Molecular Cell Biology 2017年第1期9卷 74-80页

作者： Magdalena Wienken Ute M. Moll Matthias Dobbelstein Institute of Molecular Oncology Gottingen Center for Molecular Biosciences (GZMB) University Medical Center Gottingen Gottingen 37077 Germany Department of Pathology School of Medicine Stony Brook University Stony Brook NY 11794 USA

Mdm2 is the key negative regulator of the tumour suppressor p53, making it an attractive target for anti-cancer drug design. We recently identified a new role of Mdm2 in gene repression through its direct interaction with several proteins of the polycomb group （PcG） family. PcG proteins form polycomb repressive complexes PRC1 and PRC2. PRC2 （via EZH2） mediates histone 3 lysine 27 （H3K27） trimethyiation, and PRC1 （via RING1B） mediates histone 2A tysine 119 （H2AK119） monoubiquitination. Both PRCs mostly support a compact and transcriptionally silent chromatin structure. We found that Mdm2 regulates a gene expression pro- file similar to that of PRC2 independent of p53. Moreover, Mdm2 promotes the sternness of murine induced pluripotent stem cells and human mesenchymal stem cells, and supports the survival of tumour cells. Mdm2 is recruited to target gene promoters by the PRC2 member and histone methyltransferase EZH2, and enhances PRC-dependent repressive chromatin modifications, specif- icaUy H3K27me3 and H2AK119ubl. Mdm2 also cooperates in gene repression with the PRC1 protein RINGIB, a H2AK119 ubiqui- tin ligase. Here we discuss the possible implications of these p53-independent functions of Mdm2 in chromatin dynamics and in the stem cell phenotype. We propose that the p53-independent functions of Mdm2 should be taken into account for cancer drug design. So far, the majority of clinically tested Mdm2 inhibitors target its binding to p53 but do not affect the new functions of Mdm2 described here. However, when targeting the E3 ligase activity of Mdm2, a broader spectrum of its oncogenic activities might become druggable.

关键词： Mdm2 polycomb repressor complex histone methylation histone ubiquitination EZH2

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A Tropical View on Landau-Ginzburg Models

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Acta Mathematica Sinica,English Series 2024年第1期40卷 329-382页

作者： Michael CARL Max PUMPERLA Bernd SIEBERT Alfred-Delp-Str.2 73430 AalenGermany IU Internationale Hochschule Juri-Gagarin-Ring 15299084 ErfurtGermany AnyscaleInc.2080 Addison St Ste 7BerkeleyCA 94704USA Department of Mathematics The Univ.of Texas at Austin2515 SpeedwayAustinTX 78712USA

This paper,largely written in 2009/2010,fits Landau-Ginzburg models into the mirror symmetry program pursued by the last author jointly with Mark Gross since *** point of view transparently brings in tropical disks of Maslov index 2 via the notion of broken lines,previously introduced in two dimensions by Mark Gross in his study of mirror symmetry for P2.A ma jor insight is the equivalence of properness of the Landau-Ginzburg potential with smoothness of the anticanonical divisor on the mirror *** obtain proper superpotentials which agree on an open part with those classically known for toric *** include mirror LG models for non-singular and singular del Pezzo surfaces,Hirzebruch surfaces and some Fano threefolds.

关键词： Landau-Ginzburg model mirror symmetry tropical disk broken line wall structure scattering diagram Gross-Siebert program del Pezzo surface toric degeneration

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GUN4 Is Required for Posttranslational Control of Plant Tetrapyrrole Biosynthesis

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Molecular Plant 2009年第6期2卷 1198-1210页

作者： Enrico Peter Bernhard Grimm Institute of Biology/Plant Physiology Humboldt University Philippstr. 13 Building 12 D 10115 Berlin Germany

In aerobic photosynthetic organisms, GUN4 binds the chlorophyll intermediates protoporphyrin and Mg protoporphyrin, stimulates Mg chelatase activity, and is implicated in plastidic retrograde signaling. GUN4 expression is most abundant in young and greening tissues and parallels the activity of 5-aminolevulinic acid （ALA） ALA and Mg porphyrin biosynthesis during photoperiodic growth. We explored function and mode of action of GUN4 using GUN4- deficient and overexpressing plants. GUN4 overexpression leads to a general activation of the enzymes of chlorophyll biosynthesis. During photoperiodic growth GUN4 deficiency prevents ALA synthesis and chlorophyll accumulation. All these metabolic changes do not correlate with altered gene expression or changes of protein abundance in tetrapyrrole biosynthesis. While ALA feeding fails to compensate GUN4 deficiency during light-dark growth, this approach results in chlorophyll accumulation under continuous dim light. A new model defines the involvement of GUN4 in posttranslational regulation of ALA and Mg porphyrin synthesis, to sustain chlorophyll synthesis, namely under varying environmental conditions.

关键词： Tetrapyrrole biosynthesis chlorophyll Mg porphyrin branch photo-oxidation chloroplasts

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A simple human cell model for TAU trafficking and tauopathy-related TAU pathology

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Neural Regeneration Research 2022年第4期17卷 770-772页

作者： Michael Bell Hans Zempel Institute of Human Genetics Faculty of Medicine and University Hospital CologneUniversity of CologneCenter for Molecular Medicine Cologne(CMMC)University of CologneCologneGermany

The microtubule(MT)-associated protein TAU is highly abundant in the axon of human brain neurons,where it binds to and stabilizes MT ***,TAU regulates the dynamic(dis)assembly of MT strands and is involved in a wide range of neuronal *** Alzheimer's disease(AD)and other tauopathies,TAU is missorted into the somatodendritic *** missorting is accompanied by(or leads to)abnormal TAU phosphorylation,MT destabilization,and loss of dendritic spines and mitochondria,eventually resulting in TAU aggregation,neuronal dysfunction and cell death(Arendt et al.,2016).Strikingly,the mechanisms of TAU sorting,and the detrimental cascade upon its failure,are still not fully understood.

关键词： tau sorting eventually

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Implications of tree species–environment relationships for the responsiveness of Himalayan krummholz treelines to climate change

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Journal of Mountain Science 2017年第3期14卷 453-473页

作者： Niels SCHWAB Udo SCHICKHOFF Birgit BURZLE Michael MULLER Jurgen BOHNER Ram Prasad CHAUDHARY Thomas SCHOLTEN Jens OLDELAND CEN Center for Earth System Research and Sustainability Institute of GeographyUniversity of HamburgBundesstrafle 5520146 HamburgGermany Department of Geosciences Chair of Soil Science and CeomorphologyUniversity of TübingenGermany Research Centre for Applied Science and Technology&Central Department of Botany Tribhuvan UniversityNepal Biocentre Klein Flottbek University of HamburgOhnhorststr.1822609 HamburgGermany

Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. In this context, we aim at investigating the sensitivity and responsiveness of the near-natural treeline ecotone in Rolwaling Himal, Nepal, to climate warming. We analysed population densities of tree species along the treeline ecotone from closed forest stands via the krummholz belt to alpine dwarf shrub heaths （3700-4200 m） at 50 plots in 2013 and 2014. We quantified species - environment relationships, i.e. the change of environmental conditions （e.g., nutrient and thermal deficits, plant interactions） across the ecotone by means of redundancy analyses, variation partitioning and distance-based Moran＇s eigenvector maps. In particular, we focus on explaining the high competitiveness of Rhododendron campanulatum forming a dense krummholz belt and on the implications for the responsiveness of Himalayan krummholz treelines to climate change. Results indicate that treeline trees in the ecotone show species-specific responses to the influence of environmental parameters, and that juvenile and adult tree responses are modulated by environmental constraints in differing intensity. Moreover, the species - environment relationships suggest that the investigated krummholz belt will largely prevent the upward migration of other tree constrain the future response species and thus of Himalayan krummholz treelines to climate warming.

关键词： Himalaya Nepal Population structure Rhododendron campanulatum Spatial patterns Species-environment relationships Stand density Variation partitioning

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Surface area-volume ratios in insects

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Insect Science 2017年第5期24卷 829-841页

作者： Sara Kuhsel Adrian Bruckner Sebastian Schmelzle Michael Heethoff Nico Bluthgen Department of Biology Technische Universitat Darmstadt Schnittspahnstrasse 3 D-64287 Darmstadt Germany

Body mass, volume and surface area are important for many aspects of the physiology and performance of species. Whereas body mass scaling received a lot of attention in the literature, surface areas of animals have not been measured explicitly in this context. We quantified surface area-volume （SA/V） ratios for the first time using 3D surface models based on a structured light scanning method for 126 species of pollinating insects from 4 orders （Diptera, Hymenoptera, Lepidoptera, and Coleoptera）. Water loss of 67 species was measured gravimetrically at very dry conditions for 2 h at 15 and 30 ℃ to demonstrate the applicability of the new 3D surface measurements and relevance for predicting the performance of insects. Quantified SA/V ratios significantly explained the variation in water loss across species, both directly or after accounting for isometric scaling （residuals of the SA/V - mass2/3 relationship）. Small insects with a proportionally larger surface area had the highest water loss rates. Surface scans of insects to quantify allometric SA/Vratios thus provide a promising method to predict physiological responses, improving the potential of body mass isometry alone that assume geometric similarity.

关键词： body size body shape 3D surface imaging sphericity structured light water loss

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Plastid Signals and the Bundle Sheath： Mesophyll Development in Reticulate Mutants

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Molecular Plant 2014年第1期7卷 14-29页

作者： Peter K. Lundquist Christian Rosar Andrea Brautigam Andreas P.M. Weber Institute for Plant Biochemistry and Cluster of Excellence on Plant Sciences (CEPLAS) Heinrich-Neine-Universitat Universitatsstrasse 1 40225 Dusseldorf Germany Alte StraBe 2 34225 Baunatal Germany

The development of a plant leaf is a meticulously orchestrated sequence of events producing a complex organ comprising diverse cell types. The reticulate class of leaf variegation mutants displays contrasting pigmentation between veins and interveinal regions due to specific aberrations in the development of mesophyll cells. Thus, the reticulate mutants offer a potent tool to investigate cell-type-specific developmental processes. The discovery that most mutants are affected in plastid-localized, metabolic pathways that are strongly expressed in vasculature-associated tis- sues implicates a crucial role for the bundle sheath and their chloroplasts in proper development of the mesophyll cells. Here, we review the reticulate mutants and their phenotypic characteristics, with a focus on those in Arabidopsis thali- ana. Two alternative models have been put forward to explain the relationship between plastid metabolism and meso- phyll cell development, which we call here the supply and the signaling hypotheses. We critically assess these proposed models and discuss their implications for leaf development and bundle sheath function in C3 species. The characteriza- tion of the reticulate mutants supports the significance of plastid retrograde signaling in cell development and highlights the significance of the bundle sheath in C3 photosynthesis.

关键词： reticulate mesophyll bundle sheath development intercellular signaling leaf variegation plastid.

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Biodiversity and belowground interactions mediate community invasion resistance against a tall herb invader

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Journal of Plant Ecology 2010年第2期3卷 99-108页

作者： Christoph Scherber Peter NMwangi Martin Schmitz Michael Scherer-Lorenzen Holger Beßler Christof Engels Nico Eisenhauer Varvara DMigunova Stefan Scheu Wolfgang WWeisser Ernst-Detlef Schulze Bernhard Schmid Agroecology Department of Crop ScienceUniversity of GottingenWaldweg 26D-37073 GottingenGermany Institute of Evolutionary Biology and Environmental Studies University of ZurichWinterthurerstraße 92CH-8057 ZurichSwitzerland Max Planck Institute for Biogeochemistry Hans-Knoll Straße 10D-07745 JenaGermany Institute of Ecology Jena UniversityDornburger Straße 159D-07743 JenaGermany Institut fur Biologie II/Geobotanik Schanzlestr.1D-79104 FreiburgGermany Humboldt Universitat zu Berlin Fachgebiet PflanzenernahrungAlbrecht-Thaer-Weg 4D-14195 BerlinGermany J.F.Blumenbach Institute of Zoology and Anthropology University of GottingenBerliner Str.28D-37073 GottingenGermany K.I.Skryabin All-Russian Institute of Helminthology Bolschaya Tcheryomuschkinskaya str.28117218 MoscowRussia

Aims Species-rich plant communities are hypothesized to be more resistant against plant invasions because they use resources in a more efficient ***,the relative contributions of aboveground competition and belowground interactions for invasion resistance are still poorly *** We compared the performance of Knautia arvensis transplants growing in plots differing in plant diversity both under full competition and with shoots of neighbors tied back to determine the relative strength of aboveground competition in suppressing this test invader without the confounding effect of *** addition,we assessed the effects of belowground competition and soil-borne pathogens on transplant *** Findings Both aboveground competition and plant species richness strongly and independently affected invader *** biomass,height,leaf mass per area and flowering of transplanted individuals of *** decreased with increasing species richness of the host ***-rich and species-poor communities both imposed equally strong aboveground competition on ***,belowground interactions(especially belowground root competition)had strong negative effects on transplant *** addition,the presence of grasses in a plant community further reduced the performance of *** results suggest that belowground competition can render species-rich host communities more suppressive to newly arriving species,thus enhancing community invasion resistance.

关键词： aboveground competition competitive suppression belowground interactions root competition shoot exclusion species richness

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Parameterized Algorithmics for Computational Social Choice:Nine Research Challenges

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Tsinghua Science and Technology 2014年第4期19卷 358-373页

作者： Robert Bredereck Jiehua Chen Piotr Faliszewski Jiong Guo Rolf Niedermeier Gerhard J.Woeginger the Institut fr Softwaretechnik und Theoretische Informatik TU Berlin Berlin Germany AGH University of Science and Technology Kraków Poland the Cluster of Excellence Multimodal Computing and Interaction Universitt des SaarlandesSaarbrcken Germany the Department of Mathematics and Computer Science TU Eindhoven Eindhoven The Netherlands

Computational Social Choice is an interdisciplinary research area involving Economics, Political Science,and Social Science on the one side, and Mathematics and Computer Science（including Artificial Intelligence and Multiagent Systems） on the other side. Typical computational problems studied in this field include the vulnerability of voting procedures against attacks, or preference aggregation in multi-agent systems. Parameterized Algorithmics is a subfield of Theoretical Computer Science seeking to exploit meaningful problem-specific parameters in order to identify tractable special cases of in general computationally hard problems. In this paper, we propose nine of our favorite research challenges concerning the parameterized complexity of problems appearing in this context. This work is dedicated to Jianer Chen, one of the strongest problem solvers in the history of parameterized algorithmics,on the occasion of his 60 th birthday.

关键词： NP-hard problems parameterized complexity fixed-parameter tractability kernelization exact algorithms voting decision making cake cutting

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Occurrence of an endangered grassland butterfly is mainly driven by habitat heterogeneity,food availability,and microclimate

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Insect Science 2022年第4期29卷 1211-1225页

作者： Gwydion Scherer Thomas Fartmann Department of Biodiversity and Landscape Ecology University of OsnabrückOsnabrückGermany Institute of Biodiversity and Landscape Ecology(IBL) MünsterGermany

The Marsh Fritillary(Euphydryas aurinia)was once widespread in large parts of Central ***,in the course of the last century,populations of the butterfly largely ***,we surveyed patch and microhabitat occupancy and its drivers in one of the last vital populations in calcareous *** study revealed that environmental conditions at the landscape and habitat level determined the occurrence of *** in a montane agricultural landscape with low land-use *** occupancy increased with the cover of Devil's-bit Scabious(Succisa pratensis)grasslands in the surroundings of the patches,habitat heterogeneity and host-plant *** occupancy was driven by a warm microclimate and high availability of host *** the well-connected landscape of nutrient-poor grasslands,patch occupancy of *** was driven by parameters defining a high habitat *** heterogeneity very likely buffers *** populations against environmental stochasticity and,hence,enhances long-term *** the gregariously feeding caterpillars of ***,host-plant biomass is *** to their more luxuriant growth,*** plants were clearly preferred,although the Glossy Scabious(Scabiosa lucida)was also ***,the growth of large Succisa plants was favored by soil humidity and grassland *** cope with the adverse macro-and mesoclimatic conditions of the study area,females of the butterfly selected host plants growing in extraordinarily warm microhabitats for *** secure long-term viability of *** populations,we recommend creating mosaics of traditionally managed grasslands and early stages of abandonment within the patches.

关键词： agricultural landscape calcarcous grassland hay meadow host-plant abundance land-use change traditional management

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