Piriformospora indica released factors and its role in the molecular interaction with Arabidopsis thaliana

The interaction between P. indica and A. thaliana results in growth promotion and enhanced seed production. I studied the role of various P. indica-released factors in the interaction and the signalling pathways they activate. We describe the isolation of a growth-promoting factor from the cell wall of P. indica. The cell wall extract (CWE) induces a transient cytosolic Ca2+ elevation in the roots of Arabidopsis and tobacco plants expressing the Ca2+ bioluminescent indicator aequorin. The CWE and the fungus induce a similar set of genes in Arabidopsis roots, among them are genes with Ca2+ signalling-related functions. The CWE does not promote growth of P. indica insensitive lines and the growth promotion is abolished if the Ca2+ inhibitor BAPTA is added. The cellular Ca2+ elevations and are thus crucial for growth promotion, and Ca2+ signalling pathways are activated by incoming fungus. The CWE does not stimulate H2O2 production and the activation of defence gene expression, although it led to phosphorylation of mitogen-activated protein kinases (MAPKs) in a Ca2+-dependent manner. Thus, Ca2+ is likely to be an early signalling component in the mutualistic interaction between P. indica and A. thaliana similar to other interactions like AM symbiosis. P. indica releases isopentenyl-adenine (iP) and cis-Zeatin (cZ)-type cytokinins into axenic cultures, but elevated levels of cis Zeatin (cZ) isomers accumulate in colonized roots. However, our data clearly demonstrate that trans-zeatin (tZ) biosynthesis in Arabidopsis is required for the beneficial interaction as knocking out atipt1 atipt3 atipt5 atipt7 genes required for (tZ) biosynthesis results in no response to the fungus. The double mutant cre1ahk2 shows no growth response to P. indica. The CRE1 AHK2 receptor combination is thus crucial for the response to P. indica

Reaction pathways of water dimer following single ionization

Water dimer $\mathrm{(H_2O)_2}$ - a vital component of the earth's atmosphere - is an important prototypical hydrogen-bonded system. It provides direct insight into fundamental chemical and biochemical processes, e.g., proton transfer and ionic supramolecular dynamics occurring in astro- and atmospheric chemistry. Exploiting a purified molecular beam of water dimer and multi-mass ion imaging, we report the simultaneous detection of all generated ion products of $\mathrm{(H_2O)_2^+}$-fragmentation following single ionization. Detailed information about ion yields and reaction energetics of 13 ion-radical pathways, 6 of which are new, of $\mathrm{(H_2O)_2^+}$ are presented, including strong $\mathrm{{}^{18}O}$-isotope effects.Comment: 7 pages, 4 figures, (SI: 4 pages, 6 figures

Measuring childhood socioeconomic position in health research:Development and validation of childhood socioeconomic position questionnaire using mixed method approach

Background: There is no single best indicator to assess the childhood socioeconomic position (CSEP) in public health research. The aim of the study is to develop and validate a new questionnaire, with adequate psychometric properties, to measure the childhood SEP of the young adults. Methods: The first phase consisted of a qualitative phase to identify the variables to measure childhood SEP through the in-depth interviews among 15 young adults (18-45 years) of rural Kerala. The second phase was a quantitative phase to validate the questionnaire through a cross sectional survey among 200 young adults of Kerala. We did content validity, reliability tests and construct validity by using exploratory factor analysis of the questionnaire to demonstrate its psychometric properties. Results: The qualitative analysis reported 26 variables spread across 5 domains to measure the CSEP. Finally, the questionnaire has 11 questions with 3 domains named as value added through paternity, maternal occupation-related factors and parental education. The questionnaire has good reliability (Cronbach's α=0.88) also. Conclusion: We have developed a reliable and valid questionnaire to measure the childhood SEP of younger adults and can be used in various public health research

The zinc finger protein PtaZFP2 negatively controls stem growth and gene expression responsiveness to external mechanical loads in poplar

Mechanical cues are essential signals regulating plant growth and development. In response to wind, trees develop a thigmomorphogenetic response characterized by a reduction in longitudinal growth, an increase in diameter growth, and changes in mechanical properties. The molecular mechanisms behind these processes are poorly understood. In poplar, PtaZFP2, a C2H2 transcription factor, is rapidly up-regulated after stem bending. To investigate the function of PtaZFP2, we analyzed PtaZFP2-overexpressing poplars (Populus tremula 9 Populus alba). To unravel the genes downstream PtaZFP2, a transcriptomic analysis was performed. PtaZFP2-overexpressing poplars showed longitudinal and cambial growth reductions together with an increase in the tangent and hardening plastic moduli. The regulation level of mechanoresponsive genes was much weaker after stem bending in PtaZFP2-overexpressing poplars than in wild-type plants, showing that PtaZFP2 negatively modulates plant responsiveness to mechanical stimulation. Microarray analysis revealed a high proportion of down-regulated genes in PtaZFP2-overexpressing poplars. Among these genes, several were also shown to be regulated by mechanical stimulation. Our results confirmed the important role of PtaZFP2 during plant acclimation to mechanical load, in particular through a negative control of plant molecular responsiveness. This desensitization process could modulate the amplitude and duration of the plant response during recurrent stimuli