Pectin methyl esterases and rhamnogalacturonan hydrolases: weapons for successful Monilinia laxa infection in stone fruit?

The secretion of cell wall‐degrading enzymes is one of the mechanisms used by necrotrophic fungi to colonize host tissues. However, information about virulence factors of Monilinia spp., the causal agents of brown rot in stone fruit, is scarce. Plant cell walls have three main components that are broken down by fungal enzymes: cellulose, hemicellulose and pectin. In order to identify Monilinia laxa candidate proteins involved in pectin hydrolysis, two in vitro approaches were conducted: (i) phenotypic and ecophysiological characterization of growth of the pathogen at different pHs, in glucose‐ and pectin‐containing solid media for 7 days' incubation; and (ii) expression analysis of genes encoding M. laxa pectin methyl esterases (MlPMEs) and rhamnogalacturonan hydrolases (MlRG‐HYDs) after incubation for 0.5, 2, 6, 24 and 48 h in glucose‐ and pectin‐containing liquid media. Phenotypic tests showed the role of carbon source on M. laxa growth rate and aggressiveness, and indicated that pectinases were greatly affected by pH. Gene expression analyses uncovered differences among members of each family of pectinases and between the two families, defining sets of genes expressed at earlier (0.5–6 h) and later (48 h) phases. Notably, the up‐ or down‐regulation of these target genes was carbon source‐dependent. Finally, an in vivo study confirmed the synergistic and complementary role that these genes play in the M. laxa–stone fruit pathosystem. Based on these results, it is hypothesized that MlPME2, MlRG‐HYD1 and MlRG‐HYD2 may be potential virulence factors of M. laxa in the process from infection to colonization.info:eu-repo/semantics/acceptedVersio

From ID-TIMS U-Pb dating of single monazite grain to APT-nanogeochronology: application to the UHT granulites of Andriamena (North-Central Madagascar)

The causes of U-Pb isotopic discordance documented by Paquette et al. (2004) in monazite grains from the ultra-high temperature (UHT) granulite of the Andriamena unit of Madagascar are re-evaluated in the light of nanoscale crystal-chemical characterization utilising Atom Probe Tomography (APT) and state-of-the-art Scanning Transmission Electron Microscopy (STEM). APT provides isotopic (208Pb/232Th) dating and information on the chemical segregation of trace elements (e.g., Pb) in monazite at nanoscale. Latest generation of STEM allows complementary high-resolution chemical and structural characterization at nanoscale. In situ isotopic U–Pb dating with Secondary Ion Mass Spectrometry (SIMS) on 25 monazite grains and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) on zircon have been employed to refine the age spectra. Monazite and zircon grains located in quartz and garnet formed with the peak UHT metamorphic assemblage, which is partially overprinted by retrograde coronitic textures. Zircon grains hosted in garnet and in quartz yield concordant U–Pb ages at 2758 ± 28 Ma and 2609 ± 51 Ma, respectively whereas monazite grains hosted in quartz and garnet show a discordant Pb* loss trend on the Concordia diagram recording disturbance at 1053 ± 246 Ma that is not seen by the zircon, underlining the importance of combining the use of monazite and zircon to understand the history of polymetamorphic rocks. The Pb*-loss trend of monazite is related to petrographic position, with less Pb* lost from monazite hosted in quartz and garnet than monazite hosted in the coronitic reaction texture domains. STEM shows that the garnet- and quartz-hosted monazite grains contain more Pb-bearing nanophases than monazite grains located in the coronitic textures. An inverse correlation between the number of Pb-bearing nanophases and the percentage of Pb*-loss in monazite grains demonstrates that Pb* is retained in the grain in the form of nanophases. The formation of Pb-bearing nanophases limits Pb*-loss at the grain scale and therefore allows the preservation of early events. 208Pb/232Th ratios obtained with APT in monazite located in quartz and garnet and excluding Pb*-bearing nanophases indicate a mean age of 1059 ± 129 Ma corresponding to a disturbance event hitherto undetected in the geochronological record of the Andriamena unit. Thus, geochronology with APT allows access to information and the definition of events that may be blurred or obscured when examined at lower spatial resolution

Pleiotropic functions of the tumor- and metastasis-suppressing Matrix Metalloproteinase-8 in mammary cancer in MMTV-PyMT transgenic mice

Matrix metalloproteinase-8 (MMP-8; neutrophil collagenase) is an important regulator of innate immunity which has onco-suppressive actions in numerous tumor types

Alignment of cellular motility forces with tissue flow as a mechanism for efficient wound healing

Recent experiments have shown that spreading epithelial sheets exhibit a long-range coordination of motility forces that leads to a buildup of tension in the tissue, which may enhance cell division and the speed of wound healing. Furthermore, the edges of these epithelial sheets commonly show finger-like protrusions whereas the bulk often displays spontaneous swirls of motile cells. To explain these experimental observations, we propose a simple flocking-type mechanism, in which cells tend to align their motility forceswith their velocity. Implementing this idea in amechanical tissue simulation, the proposed model gives rise to efficient spreading and can explain the experimentally observed long-range alignment of motility forces in highly disordered patterns, as well as the buildup of tensile stress throughout the tissue. Our model also qualitatively reproduces the dependence of swirl size and swirl velocity on cell density reported in experiments and exhibits an undulation instability at the edge of the spreading tissue commonly observed in vivo. Finally, we study the dependence of colony spreading speed on important physical and biological parameters and derive simple scaling relations that show that coordination of motility forces leads to an improvement of the wound healing process for realistic tissue parameters

Whole systems approaches to obesity and other complex public health challenges: a systematic review

Background: Increasing awareness of the complexity of public health problems, including obesity, has led to growing interest in whole systems approaches (WSAs), defined as those that consider the multifactorial drivers of overweight and obesity, involve transformative co-ordinated action across a broad range of disciplines and stakeholders, operate across all levels of governance and throughout the life course. This paper reports a systematic review of WSAs targeting obesity and other complex public health and societal issues, such as healthy lifestyles for prevention of non-communicable disease. Methods: Seven electronic databases were searched from 1995 to 2018. Studies were included if there had been an effort to implement a WSA. Study selection was conducted by one reviewer with a random 20% double checked. Data extraction and validity assessment were undertaken by one reviewer and checked by a second reviewer. Narrative synthesis was undertaken. Results: 65 articles were included; 33 about obesity. Most examined multicomponent community approaches, and there was substantial clinical and methodological heterogeneity. Nevertheless, a range of positive health outcomes were reported, with some evidence of whole systems thinking. Positive effects were seen on health behaviours, body mass index (BMI), parental and community awareness, community capacity building, nutrition and physical activity environments, underage drinking behaviour and health, safety and wellbeing of community members, self-efficacy, smoking and tobacco-related disease outcomes. Features of successful approaches reported in process evaluations included: full engagement of relevant partners and community; time to build relationships, trust and capacity; good governance; embedding within a broader policy context; local evaluation; finance. Conclusions: Systems approaches to tackle obesity can have some benefit, but evidence of how to operationalise a WSA to address public health problems is still in its infancy. Future research should: (a) develop an agreed definition of a WSA in relation to obesity, (b) look across multiple sectors to ensure consistency of language and definition, (c) include detailed descriptions of the approaches, and (d) include process and economic evaluations

The repulsive lattice gas, the independent-set polynomial, and the Lov\'asz local lemma

We elucidate the close connection between the repulsive lattice gas in equilibrium statistical mechanics and the Lovasz local lemma in probabilistic combinatorics. We show that the conclusion of the Lovasz local lemma holds for dependency graph G and probabilities {p_x} if and only if the independent-set polynomial for G is nonvanishing in the polydisc of radii {p_x}. Furthermore, we show that the usual proof of the Lovasz local lemma -- which provides a sufficient condition for this to occur -- corresponds to a simple inductive argument for the nonvanishing of the independent-set polynomial in a polydisc, which was discovered implicitly by Shearer and explicitly by Dobrushin. We also present some refinements and extensions of both arguments, including a generalization of the Lovasz local lemma that allows for "soft" dependencies. In addition, we prove some general properties of the partition function of a repulsive lattice gas, most of which are consequences of the alternating-sign property for the Mayer coefficients. We conclude with a brief discussion of the repulsive lattice gas on countably infinite graphs.Comment: LaTex2e, 97 pages. Version 2 makes slight changes to improve clarity. To be published in J. Stat. Phy

Colloquium: Mechanical formalisms for tissue dynamics

The understanding of morphogenesis in living organisms has been renewed by tremendous progressin experimental techniques that provide access to cell-scale, quantitative information both on theshapes of cells within tissues and on the genes being expressed. This information suggests that ourunderstanding of the respective contributions of gene expression and mechanics, and of their crucialentanglement, will soon leap forward. Biomechanics increasingly benefits from models, which assistthe design and interpretation of experiments, point out the main ingredients and assumptions, andultimately lead to predictions. The newly accessible local information thus calls for a reflectionon how to select suitable classes of mechanical models. We review both mechanical ingredientssuggested by the current knowledge of tissue behaviour, and modelling methods that can helpgenerate a rheological diagram or a constitutive equation. We distinguish cell scale ("intra-cell")and tissue scale ("inter-cell") contributions. We recall the mathematical framework developpedfor continuum materials and explain how to transform a constitutive equation into a set of partialdifferential equations amenable to numerical resolution. We show that when plastic behaviour isrelevant, the dissipation function formalism appears appropriate to generate constitutive equations;its variational nature facilitates numerical implementation, and we discuss adaptations needed in thecase of large deformations. The present article gathers theoretical methods that can readily enhancethe significance of the data to be extracted from recent or future high throughput biomechanicalexperiments.Comment: 33 pages, 20 figures. This version (26 Sept. 2015) contains a few corrections to the published version, all in Appendix D.2 devoted to large deformation