Confocal Fluorescence Ratio Imaging of Ion Activities in Plant Cells

Fluorescent probes allow measurement of dynamic changes of calcium and pH in living cells. Imaging using confocal scanning laser microscopy provides a route to spatially map these dynamics over time in single optical sections or in 3-D images. We have developed a dual-excitation confocal system to allow ratio measurements of pH and calcium, that compensate for changes in dye distribution, leakage and photobleaching. Application of these techniques to plant tissues is complicated by the difficulty in loading the tissues with dye. We describe a new technique to assist dye loading in intact leaves of Lemna using a pre-treatment with cutinase. Once within plant tissues, many dyes compartmentalise into the vacuole. We report the use of chloromethylfluorescein diacetate as an alternative to BCECF [2\u27 ,7\u27-bis-(2-carboxyethyl)-5-(and 6)carboxyfluorescein] as a pH probe with greater cytoplasmic retention times. In addition, the confocal system allowed discrimination of signals from different compartments and permitted simultaneous measurement of vacuolar and cytoplasmic pH ratios in epidermal strips from Hordeum. We have developed a series of software tools to extract quantitative data from multi-dimensional images and illustrate these approaches with reference to pollen tube growth in Lilium and peptide-evoked changes in pH and calcium in stomata! guard cells from Commelina and Vicia

Active diffusion and microtubule-based transport oppose myosin forces to position organelles in cells.

Even distribution of peroxisomes (POs) and lipid droplets (LDs) is critical to their role in lipid and reactive oxygen species homeostasis. How even distribution is achieved remains elusive, but diffusive motion and directed motility may play a role. Here we show that in the fungus Ustilago maydis ∼95% of POs and LDs undergo diffusive motions. These movements require ATP and involve bidirectional early endosome motility, indicating that microtubule-associated membrane trafficking enhances diffusion of organelles. When early endosome transport is abolished, POs and LDs drift slowly towards the growing cell end. This pole-ward drift is facilitated by anterograde delivery of secretory cargo to the cell tip by myosin-5. Modelling reveals that microtubule-based directed transport and active diffusion support distribution, mobility and mixing of POs. In mammalian COS-7 cells, microtubules and F-actin also counteract each other to distribute POs. This highlights the importance of opposing cytoskeletal forces in organelle positioning in eukaryotes.We thank Dr G. Dagdas, Dr S. Kilaru, Mr M. Schlick and Mrs T. Schrader for technical support. We thank Professor N.J. Talbot for helpful comments on the manuscript. This work was supported by the Biotechnology & Biological Sciences Research Council (BB/J009903/1 to G.S.). S.C.G. was supported by a fellowship from the Portuguese Foundation for Science and Technology (FCT) (SFRH/BD/73532/2010). J.M. is supported by a Wellcome Trust Institutional Strategic Support Award (WT097835MF)

Cliophysics: Socio-political Reliability Theory, Polity Duration and African Political (In)stabilities

Quantification of historical sociological processes have recently gained attention among theoreticians in the effort of providing a solid theoretical understanding of the behaviors and regularities present in sociopolitical dynamics. Here we present a reliability theory of polity processes with emphases on individual political dynamics of African countries. We found that the structural properties of polity failure rates successfully capture the risk of political vulnerability and instabilities in which 87.50%, 75%, 71.43%, and 0% of the countries with monotonically increasing, unimodal, U-shaped and monotonically decreasing polity failure rates, respectively, have high level of state fragility indices. The quasi-U-shape relationship between average polity duration and regime types corroborates historical precedents and explains the stability of the autocracies and democracies.Comment: 4 pages, 3 figures, 1 tabl

Emerging media and press freedoms as determinants of nonviolent and violent political conflicts, 1990–2006

© 2016, © The Author(s) 2016. Using aggregate-level data, this study compares instances of intrastate political conflict that occurred in both nonviolent and violent forms. Specifically, analyses presented in this study examine the relationships that exist between diffusion rates of emerging media and enhanced press freedoms in countries that experienced differing types of conflicts from 1990 through 2006. Through a series of analytic models, the results observed here indicate that higher levels of emerging media and press freedoms are better predictors of nonviolent—as opposed to violent—conflict. Findings from this study thus bridge an important gap in the literature between communication and political science research in establishing linkages between emerging media technologies and press freedoms and their interconnections with nonviolent and violent political conflict. Implications for related interdisciplinary fields are discussed

Adrenocorticotrophic hormone-stimulated cortisol release by the head kidney inter-renal tissue from sea bream (Sparus aurata) fed with linseed oil and soyabean oil

The mode of action of highly unsaturated fatty acids (HUFA) in regulating gilthead sea bream (Sparus aurata) head kidney (HK) cortisol production was studied through in vitro trials using a dynamic superfusion system. Fish were previously fed with different diets containing several inclusion levels of linseed oil (LO) or soyabean oil (SO) for 26 weeks. Five diets were tested; anchovy oil was the only lipid source for the control diet (fish oil, FO) and two different substitution levels (70 and 100 %) were tested using either LO or SO (70LO, 70SO, 100LO and 100SO). Fatty acid compositions of the HK reflected the dietary input, thus EPA, DHA, arachidonic acid and n-3 HUFA were significantly (P,0·05) reduced in fish fed vegetable oils compared with fish fed the FO diet. Feeding 70 or 100% LO increased significantly (P,0·05) cortisol release in HK after stimulation with adrenocorticotrophic hormone (ACTH), while feeding SO had no effect on this response. Cortisol stimulation factor (SF) was increased in fish fed the 70LO and 100LO diets compared with fish fed the control diet. Moreover, eicosanoid inhibition by incubating the HK tissue with indomethacin (INDO) as a cyclo-oxygenase (COX) inhibitor, or nordihydroguaiaretic acid (NDGA) as a lipoxygenase (LOX) inhibitor, significantly reduced (P,0·05) the cortisol release after ACTH stimulation in the 70LO and 100LO diets. Cortisol SF was reduced in the FO, 70LO and 100LO diets when incubating the HK with INDO or NDGA, while it was increased in the 70SO diet. The present results indicate that changing the fatty acid profile of gilthead sea bream HK by including LO and/or SO in the fish diet affected the in vitro cortisol release, and this effect is partly mediated by COX and/or LOX metabolites

Sharks of the order Carcharhiniformes from the British Coniacian, Santonian and Campanian (Upper Cretaceous).

Bulk sampling of phosphate-rich horizons within the British Coniacian to Campanian (Upper Cretaceous) yielded very large samples of shark and ray teeth. All of these samples yielded teeth of diverse members of the Carcharhiniformes, which commonly dominate the fauna. The following species are recorded and described: Pseudoscyliorhinus reussi (Herman, 1977) comb. nov., Crassescyliorhinus germanicus (Herman, 1982) gen. nov., Scyliorhinus elongatus (Davis, 1887), Scyliorhinus brumarivulensis sp. nov., ? Palaeoscyllium sp., Prohaploblepharus riegrafi (Müller, 1989) gen. nov., ? Cretascyliorhinus sp., Scyliorhinidae inc. sedis 1, Scyliorhinidae inc. sedis 2, Pteroscyllium hermani sp. nov., Protoscyliorhinus sp., Leptocharias cretaceus sp. nov., Palaeogaleus havreensis Herman, 1977, Paratriakis subserratus sp. nov., Paratriakis tenuis sp. nov., Paratriakis sp. indet. and ? Loxodon sp. Taxa belonging to the families ?Proscylliidae, Leptochariidae, and Carcharhinidae are described from the Cretaceous for the first time. The evolutionary and palaeoecological implications of these newly recognised faunas are discussed

Genome-wide characterization and expression profiling of immune genes in the diamondback moth, Plutella xylostella (L.)

The diamondback moth, Plutella xylostella (L.), is a destructive pest that attacks cruciferous crops worldwide. Immune responses are important for interactions between insects and pathogens and information on these underpins the development of strategies for biocontrol-based pest management. Little, however, is known about immune genes and their regulation patterns in P. xylostella. A total of 149 immune-related genes in 20 gene families were identified through comparison of P. xylostella genome with the genomes of other insects. Complete and conserved Toll, IMD and JAK-STAT signaling pathways were found in P. xylostella. Genes involved in pathogen recognition were expanded and more diversified than genes associated with intracellular signal transduction. Gene expression profiles showed that the IMD pathway may regulate expression of antimicrobial peptide (AMP) genes in the midgut, and be related to an observed down-regulation of AMPs in experimental lines of insecticide-resistant P. xylostella. A bacterial feeding study demonstrated that P. xylostella could activate different AMPs in response to bacterial infection. This study has established a framework of comprehensive expression profiles that highlight cues for immune regulation in a major pest. Our work provides a foundation for further studies on the functions of P. xylostella immune genes and mechanisms of innate immunity.Xiaofeng Xia, Liying Yu, Minqian Xue, Xiaoqiang Yu, Liette Vasseur, Geoff M. Gurr, Simon W. Baxter, Hailan Lin, Junhan Lin, Minsheng Yo

Genotoksičnost metalnih nanočestica: osvrt na podatke istraživanja In vivo

With increasing production and application of a variety of nanomaterials (NMs), research on their cytotoxic and genotoxic potential grows, as the exposure to these nano-sized materials may potentially result in adverse health effects. In large part, indications for potential DNA damaging effects of nanoparticles (NPs) originate from inconsistent in vitro studies. To clarify these effects, the implementation of in vivo studies has been emphasised. This paper summarises study results of genotoxic effects of NPs, which are available in the recent literature. They provide indications that some NP types cause both DNA strand breaks and chromosomal damages in experimental animals. Their genotoxic effects, however, do not depend only on particle size, surface modifi cation (particle coating), and exposure route, but also on exposure duration. Currently available animal studies may suggest differing mechanisms (depending on the duration of exposure) by which living organisms react to NP contact. Nevertheless, due to considerable inconsistencies in the recent literature and the lack of standardised test methods - a reliable hazard assessment of NMs is still limited. Therefore, international organisations (e.g. NIOSH) suggest utmost caution when potential exposure of humans to NMs occurs, as long as evidence of their toxicological and genotoxic effect(s) is limited.S povećanjem proizvodnje i primjene niza različitih nanomaterijala (NM) raste i potreba istraživanja njihovih mogućih citotoksičnih i genotoksičnih učinaka kao i drugih štetnih učinaka na zdravlje u uvjetima profesionalne ili opće izloženost ljudi. Indikacije potencijanog oštećenja DNA kojeg uzrokuju nanočestice u velikoj mjeri proizlaze iz nedosljednih in vitro ispitivanja. Kako bi se razjasnili ti učinci, naglašena je potreba provedbe in vivo ispitivanja. Ovaj pregledni rad sažima rezultate procjene genotoksičnih učinaka nanočestica koji su objavljeni u novijoj stručnoj i znanstvenoj literaturi. Navedeni rezultati pokazuju da određene nanočestice uzrokuju lomove u molekuli DNA i oštećuju kromosome u eksperimentalnim životinjama. Njihovi genotoksični učinci ne ovise samo o veličini čestice, modifi kaciji površine (oblaganje čestice) i načinu izlaganja, već i o trajanju izloženosti nanočesticama. Postojeća istraživanja provedena na životinjama upućuju na različite mehanizme koji ovise o trajanju izlaganja i pomoću kojih živi organizmi reagiraju na doticaj s nanočesticama. Međutim postoje brojne nedosljednosti u novijoj literaturi, a standardne testne metode nisu dostupne pa je stoga pouzdanija procjena opasnosti od izlaganja nanomaterijalima u ljudi još uvijek veoma ograničena. Stoga se u međunarodnim dokumentima savjetuje oprez prilikom svakog izlaganja ljudi nanomaterijalima kako bi se spriječili mogući opći toksični genotoksični učinci

Threats posed by the fungal kingdom to humans, wildlife, and agriculture

The fungal kingdom includes at least 6 million eukaryotic species and is remarkable with respect to its profound impact on global health, biodiversity, ecology, agriculture, manufacturing, and biomedical research. Approximately 625 fungal species have been reported to infect vertebrates, 200 of which can be human associated, either as commensals and members of our microbiome or as pathogens that cause infectious diseases. These organisms pose a growing threat to human health with the global increase in the incidence of invasive fungal infections, prevalence of fungal allergy, and the evolution of fungal pathogens resistant to some or all current classes of antifungals. More broadly, there has been an unprecedented and worldwide emergence of fungal pathogens affecting animal and plant biodiversity. Approximately 8,000 species of fungi and Oomycetes are associated with plant disease. Indeed, across agriculture, such fungal diseases of plants include new devastating epidemics of trees and jeopardize food security worldwide by causing epidemics in staple and commodity crops that feed billions. Further, ingestion of mycotoxins contributes to ill health and causes cancer. Coordinated international research efforts, enhanced technology translation, and greater policy outreach by scientists are needed to more fully understand the biology and drivers that underlie the emergence of fungal diseases and to mitigate against their impacts. Here, we focus on poignant examples of emerging fungal threats in each of three areas: human health, wildlife biodiversity, and food security