The C2-domain protein QUIRKY and the receptor-like kinase STRUBBELIG localize to plasmodesmata and mediate tissue morphogenesis in Arabidopsis thaliana

Tissue morphogenesis in plants requires communication between cells, a process involving the trafficking of molecules through plasmodesmata (PD). PD conductivity is regulated by endogenous and exogenous signals. However, the underlying signaling mechanisms remain enigmatic. In Arabidopsis, signal transduction mediated by the receptor-like kinase STRUBBELIG (SUB) contributes to inter-cell layer signaling during tissue morphogenesis. Previous analysis has revealed that SUB acts non-cell-autonomously suggesting that SUB controls tissue morphogenesis by participating in the formation or propagation of a downstream mobile signal. A genetic screen identified QUIRKY (QKY), encoding a predicted membrane-anchored C2-domain protein, as a component of SUB signaling. Here, we provide further insight into the role of QKY in this process. We show that like SUB, QKY exhibits non-cell-autonomy when expressed in a tissue-specific manner and that non-autonomy of QKY extends across several cells. In addition, we report on localization studies indicating that QKY and SUB localize to PD but independently of each other. FRET-FLIM analysis suggests that SUB and QKY are in close contact at PD in vivo. We propose a model where SUB and QKY interact at PD to promote tissue morphogenesis, thereby linking RLK-dependent signal transduction and intercellular communication mediated by PD

Cyanobacterial lipopolysaccharides and human health – a review

Cyanobacterial lipopolysaccharide/s (LPS) are frequently cited in the cyanobacteria literature as toxins responsible for a variety of heath effects in humans, from skin rashes to gastrointestinal, respiratory and allergic reactions. The attribution of toxic properties to cyanobacterial LPS dates from the 1970s, when it was thought that lipid A, the toxic moiety of LPS, was structurally and functionally conserved across all Gram-negative bacteria. However, more recent research has shown that this is not the case, and lipid A structures are now known to be very different, expressing properties ranging from LPS agonists, through weak endotoxicity to LPS antagonists. Although cyanobacterial LPS is widely cited as a putative toxin, most of the small number of formal research reports describe cyanobacterial LPS as weakly toxic compared to LPS from the Enterobacteriaceae. We systematically reviewed the literature on cyanobacterial LPS, and also examined the much lager body of literature relating to heterotrophic bacterial LPS and the atypical lipid A structures of some photosynthetic bacteria. While the literature on the biological activity of heterotrophic bacterial LPS is overwhelmingly large and therefore difficult to review for the purposes of exclusion, we were unable to find a convincing body of evidence to suggest that heterotrophic bacterial LPS, in the absence of other virulence factors, is responsible for acute gastrointestinal, dermatological or allergic reactions via natural exposure routes in humans. There is a danger that initial speculation about cyanobacterial LPS may evolve into orthodoxy without basis in research findings. No cyanobacterial lipid A structures have been described and published to date, so a recommendation is made that cyanobacteriologists should not continue to attribute such a diverse range of clinical symptoms to cyanobacterial LPS without research confirmation

Data Descriptor : A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.Peer reviewe

Cylindrospermopsin occurrence in two German lakes and preliminary assessment of toxicity and toxin production of Cylindrospermopsis raciborskii (Cyanobacteria) isolates

Cylindrospermopsis raciborskii, a freshwater cyanobacterium of tropical origin, is not only increasingly found in (sub) tropical water bodies, but also in temperate regions. Since this species may produce potent toxins such as cylindrospermopsin (CYN) and paralytic shellfish poisons, its massive occurrence in water bodies used as drinking water sources or for recreation is of major concern. The proliferation of C. raciborskii in German water bodies has been documented for the past decade. We investigated the occurrence of CYN in field populations and isolates of C. raciborskii from two lakes, and assessed the toxicity of culture isolates using the mouse bioassay, primary rat hepatocytes and human derived cell lines. We show for the first time the occurrence of CYN in German water bodies. None of seven isolates of C. raciborskii contained CYN, however, all isolates were toxic to primary rat hepatocytes, human hepatoblastoma (HEP-G2) and human colon adenocarcinoma (CACO-2) cells. Methanolic extracts were more toxic than aqueous extracts. Three isolates tested in the mouse bioassay were toxic at a concentration of 800 mg kg(-1) showing liver and spleen damage and inflammation of the intestine. These results give strong evidence that the German isolates of C. raciborskii contain currently not identified or unknown toxins

Sex differences of in-hospital outcome and long-term mortality in patients with Takotsubo cardiomyopathy

KJ Weidner,1,* I El-Battrawy,1,2,* M Behnes,1 K Schramm,1 C Fastner,1,2 J Kuschyk,1 U Hoffmann,1,2 U Ansari,1 M Borggrefe,1,2 I Akin1,2 1First Department of Medicine, University Medical Centre Mannheim, Faculty of Medicine Mannheim, University of Heidelberg, 2DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg, Mannheim, Germany *These authors contributed equally to this work Background: Previous studies revealed that patients with Takotsubo cardiomyopathy (TTC) have a higher mortality rate than the general population. It is still unclear whether sex differences may influence long-term prognosis of TTC patients. The purpose of this study was to determine whether sex differences do influence the short- and long-term outcomes of TTC. Methods and results: A total of 114 patients with TTC were admitted to the University Medical Centre Mannheim from January 2003 to September 2015 and entered into the TTC database of the University Medical Centre Mannheim, and retrospectively analyzed. Patients were diagnosed by the Mayo Clinic criteria. All-cause mortality over mean follow-up of 1,529±1,121 days was revealed. Significantly more male patients died within long-term follow-up compared to female TTC patients (log-rank test; P=0.01). Most males died of noncardiac causes. In multivariate Cox regression analysis, the male sex (P=0.02, hazard ratio [HR] 2.8, 95% CI 1.1–7.2), the ejection fraction ≤35% (P=0.01, HR 3.3, 95% CI 1.2–9.2) and glomerular filtration rate <60 mL/min (P<0.01, HR 3.1, 95% CI 1.4–7.0) figured out as independent predictors of the adverse outcome. Conclusion: This study shows that males suffering from TTC reveal a higher long-term all-cause mortality rate than females over a 5 year follow-up period. Keywords: Takotsubo cardiomyopathy, sex differences, outcome, mortality&nbsp

Auxin efflux by PIN-FORMED proteins is activated by two different protein kinases, D6 PROTEIN KINASE and PINOID

International audienceThe development and morphology of vascular plants is critically determined by synthesis and proper distribution of the phytohormone auxin. The directed cell-to-cell distribution of auxin is achieved through a system of auxin influx and efflux transporters. PIN-FORMED (PIN) proteins are proposed auxin efflux transporters, and auxin fluxes can seemingly be predicted based on the—in many cells—asymmetric plasma membrane distribution of PINs. Here, we show in a heterologous Xenopus oocyte system as well as in Arabidopsis thaliana inflorescence stems that PIN-mediated auxin transport is directly activated by D6 PROTEIN KINASE (D6PK) and PINOID (PID)/WAG kinases of the Arabidopsis AGCVIII kinase family. At the same time, we reveal that D6PKs and PID have differential phosphosite preferences. Our study suggests that PIN activation by protein kinases is a crucial component of auxin transport control that must be taken into account to understand auxin distribution within the plant