ORCID Profile
0000-0003-3548-3594
Current Organisations
Universität Zürich
,
University of Zurich
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Publisher: Wiley
Date: 17-03-2017
Abstract: Improving host health through microbial manipulation requires untangling factors that shape the microbiome. There is currently little understanding of how initial community structure may drive the microbiota trajectory across host development or influence bacterial therapy outcomes. Probiotic baths of surface symbionts, Pseudomonas fluorescens and Flavobacterium johnsoniae were administered to 240 tadpoles of the midwife toad, Alytes obstetricans in semi-natural outdoor mesocosms originating from geographically and genetically distinct populations in Switzerland. Host bacterial and fungal assemblages were compared in tadpoles from the pond of origin, across metamorphosis, and in toadlets via microbial fingerprinting. Bacterial and fungal community structures differed significantly among populations and a microbial population signature persisted from the tadpole stage, through metamorphosis, and following probiotic treatment. A minimal core surface microbiota is described by persistence through development and by shared membership across populations. The impact of F. johnsoniae on the tadpole surface microbiome was assessed with shotgun metagenomics. Bacterial therapy reduced abundance, ersity, and functional repertoire compared to untreated controls. A correlation between host skin peptides and microbiota suggests a mechanism of host-directed symbiosis throughout development. Early developmental stages are ideal targets for hibian bacterial therapy that can govern a microbiome trajectory at critical timepoints and may impact susceptibility to disease.
Publisher: Oxford University Press (OUP)
Date: 2016
Publisher: MDPI AG
Date: 29-07-2023
Abstract: Toxic breakdown products of young Camelina sativa (L.) Crantz, glucosinolates can eliminate microorganisms in the soil. Since microorganisms are essential for phosphate cycling, only insensitive microorganisms with phosphate-solubilizing activity can improve C. sativa’s phosphate supply. In this study, 33P-labeled phosphate, inductively coupled plasma mass spectrometry and pot experiments unveiled that not only Trichoderma viride and Pseudomonas laurentiana used as phosphate-solubilizing inoculants, but also intrinsic soil microorganisms, including Penicillium aurantiogriseum, and the assemblies of root-colonizing microorganisms solubilized as well phosphate from apatite, trigger off competitive behavior between the organisms. Driving factors in the competitiveness are plant and microbial secondary metabolites, while glucosinolates of Camelina and their breakdown products are regarded as key compounds that inhibit the pathogen P. aurantiogriseum, but also seem to impede root colonization of T. viride. On the other hand, fungal diketopiperazine combined with glucosinolates is fatal to Camelina. The results may contribute to explain the contradictory effects of phosphate-solubilizing microorganisms when used as biofertilizers. Further studies will elucidate impacts of released secondary metabolites on coexisting microorganisms and plants under different environmental conditions.
Publisher: Wiley
Date: 24-10-2016
DOI: 10.1111/PCE.12828
Abstract: As a first line of defense against insect herbivores many plants store high concentrations of toxic and deterrent secondary metabolites in glandular trichomes. Plant Pleiotropic Drug Resistance (PDR)-type ABC transporters are known secondary metabolite transporters, and several have been implicated in pathogen or herbivore defense. Here, we report on Petunia hybrida PhPDR2 as a major contributor to trichome-related chemical defense. PhPDR2 was found to localize to the plasma membrane and be predominantly expressed in multicellular glandular trichomes of leaves and stems. Down-regulation of PhPDR2 via RNA interference (pdr2) resulted in a markedly higher susceptibility of the transgenic plants to the generalist foliage feeder Spodoptera littoralis. Untargeted screening of pdr2 trichome metabolite contents showed a significant decrease in petuniasterone and petuniolide content, compounds, which had previously been shown to act as potent toxins against various insects. Our findings suggest that PhPDR2 plays a leading role in controlling petuniasterone levels in leaves and trichomes of petunia, thus contributing to herbivory resistance.
Publisher: Wiley
Date: 27-11-2006
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.MEEGID.2012.07.024
Abstract: Heterogeneity in immune defense effectors can benefit hosts encountering a variety of parasites and pathogens. Antimicrobial peptides (AMPs) are a erse set of immune defense effectors in many hibians, and are secreted from dermal granular glands to protect the skin from infection. Over 50 different skin peptides have been reported from the European water frog hybridogenic complex (Pelophylax esculentus complex), consisting of the hybrid P. esculentus, and the parent species Pelophylax lessonae and Pelophylax ridibundus. In central Europe the hybrid is sympatric with only P. lessonae, while in other areas all three species can co-occur. Amphibian immune defenses are likely under selective pressure from emerging pathogens such as the chytrid fungus Batrachochytrium dendrobatidis (Bd). To assess if hybridization affects immune defenses against Bd, we compared skin peptides of the three species in terms of (i) quantity, (ii) activity against Bd, (iii) repertoire, and (iv) stability. Hybrids secreted AMPs at higher quantities and with greater fungicidal activity compared to cohabiting P. lessonae. Compared to P. ridibundus, AMPs from hybrids were of similar quantity but slightly greater antifungal activity. Mass spectrometric analyses (MALDI-TOF) revealed that of all three species P. esculentus has the greatest peptide ersity, a repertoire inclusive of peptides occurring in either one or the other parent species. Measurements of degradation dynamics indicate that peptides remain relatively stable on the skin of all species for over an hour after induction of skin gland secretions. Our data demonstrate that the hybrid has more effective peptide defenses against Bd and a richer peptide repertoire than either parent species. Hybrid advantage in environments hosting virulent pathogens may contribute to disassortative mating preferences, and we suggest that AMP ersity may be analogous to major histocompatibility complex (MHC) heterozygosity by benefiting hosts encountering multiple parasites.
Publisher: Public Library of Science (PLoS)
Date: 29-01-2014
Publisher: Springer Science and Business Media LLC
Date: 04-02-2016
DOI: 10.1038/NCOMMS10622
Abstract: Inositol pyrophosphates, such as diphospho-myo-inositol pentakisphosphates (InsP 7 ), are an important family of signalling molecules, implicated in many cellular processes and therapeutic indications including insulin secretion, glucose homeostasis and weight gain. To understand their cellular functions, chemical tools such as photocaged analogues for their real-time modulation in cells are required. Here we describe a concise, modular synthesis of InsP 7 and caged InsP 7 . The caged molecule is stable and releases InsP 7 only on irradiation. While photocaged InsP 7 does not enter cells, its cellular uptake is achieved using nanoparticles formed by association with a guanidinium-rich molecular transporter. This novel synthesis and unprecedented polyphosphate delivery strategy enable the first studies required to understand InsP 7 signalling in cells with controlled spatiotemporal resolution. It is shown herein that cytoplasmic photouncaging of InsP 7 leads to translocation of the PH-domain of Akt, an important signalling-node kinase involved in glucose homeostasis, from the membrane into the cytoplasm.
No related grants have been discovered for Laurent Bigler.