Denial in the Decisive Decade: Towards Intervention and Common Action

[abstract not provided]https://fount.aucegypt.edu/faculty_book_chapters/1921/thumbnail.jp

Water in a Changing World

Life on earth depends on the continuous flow of materials through the air, water, soil, and food webs of the biosphere. The movement of water through the hydrological cycle comprises the largest of these flows, delivering an estimated I 10,000 cubic kilometers (km^\u3e of water to the land each year as snow and rainfall. Solar energy drives the hydrological cycle, vaporizing water from the surface of oceans, lakes, and rivers as well as from soils and plants (evapotranspiration). Water vapor rises into the atmosphere where it cools, condenses, and eventually rains down anew. This renewable freshwater supply sustains life on the land, in estuaries, and in the freshwater ecosystems of the earth

The Arabidopsis leucine-rich repeat receptor kinase BIR3 negatively regulates BAK1 receptor complex formation and stabilizes BAK1

BAK1 is a co-receptor and positive regulator of multiple ligand-binding leucine-rich-repeat receptor kinases (LRR-RKs) and is involved in brassinosteroid (BR)-dependent growth and development, innate immunity and cell death control. The BAK1-interacting LRR-RKs BIR2 and BIR3 were previously identified by proteomics analyses of in vivo BAK1 complexes. Here we show that BAK1-related pathways such as innate immunity and cell death control are affected by BIR3 in Arabidopsis thaliana. BIR3 also has a strong negative impact on BR signaling. BIR3 directly interacts with the BR receptor BRI1 and other ligand-binding receptors and negatively regulates BR signaling by competitive inhibition of BRI1. BIR3 is released from BAK1 and BRI1 after ligand exposure and directly affects the formation of BAK1 complexes with BRI1 or FLAGELLIN SENSING2. Double mutants of bak1 and bir3 show spontaneous cell death and constitutive activation of defense responses. BAK1 and its closest homolog BKK1 interact with and are stabilized by BIR3, suggesting that bak1 bir3 double mutants mimic the spontaneous cell death phenotype observed in bak1 bkk1 mutants via destabilization of BIR3 target proteins. Our results provide evidence for a negative regulatory mechanism for BAK1 receptor complexes in which BIR3 interacts with BAK1 and inhibits ligand-binding receptors to prevent BAK1 receptor complex formation

Transcriptome Profiling of Citrus Fruit Response to Huanglongbing Disease

Huanglongbing (HLB) or “citrus greening” is the most destructive citrus disease worldwide. In this work, we studied host responses of citrus to infection with Candidatus Liberibacter asiaticus (CaLas) using next-generation sequencing technologies. A deep mRNA profile was obtained from peel of healthy and HLB-affected fruit. It was followed by pathway and protein-protein network analysis and quantitative real time PCR analysis of highly regulated genes. We identified differentially regulated pathways and constructed networks that provide a deep insight into the metabolism of affected fruit. Data mining revealed that HLB enhanced transcription of genes involved in the light reactions of photosynthesis and in ATP synthesis. Activation of protein degradation and misfolding processes were observed at the transcriptomic level. Transcripts for heat shock proteins were down-regulated at all disease stages, resulting in further protein misfolding. HLB strongly affected pathways involved in source-sink communication, including sucrose and starch metabolism and hormone synthesis and signaling. Transcription of several genes involved in the synthesis and signal transduction of cytokinins and gibberellins was repressed while that of genes involved in ethylene pathways was induced. CaLas infection triggered a response via both the salicylic acid and jasmonic acid pathways and increased the transcript abundance of several members of the WRKY family of transcription factors. Findings focused on the fruit provide valuable insight to understanding the mechanisms of the HLB-induced fruit disorder and eventually developing methods based on small molecule applications to mitigate its devastating effects on fruit production

Chemosensitivity profiling of osteosarcoma tumour cell lines identifies a model of BRCAness

Osteosarcoma (OS) is an aggressive sarcoma, where novel treatment approaches are required. Genomic studies suggest that a subset of OS, including OS tumour cell lines (TCLs), exhibit genomic loss of heterozygosity (LOH) patterns reminiscent of BRCA1 or BRCA2 mutant tumours. This raises the possibility that PARP inhibitors (PARPi), used to treat BRCA1/2 mutant cancers, could be used to target OS. Using high-throughput drug sensitivity screening we generated chemosensitivity profiles for 79 small molecule inhibitors, including three clinical PARPi. Drug screening was performed in 88 tumour cell lines, including 18 OS TCLs. This identified known sensitivity effects in OS TCLs, such as sensitivity to FGFR inhibitors. When compared to BRCA1/2 mutant TCLs, OS TCLs, with the exception of LM7, were PARPi resistant, including those with previously determined BRCAness LoH profiles. Post-screen validation experiments confirmed PARPi sensitivity in LM7 cells as well as a defect in the ability to form nuclear RAD51 foci in response to DNA damage. LM7 provides one OS model for the study of PARPi sensitivity through a potential defect in RAD51-mediated DNA repair. The drug sensitivity dataset we generated in 88 TCLs could also serve as a resource for the study of drug sensitivity effects in OS

Liquid Assets: The Critical Need to Safeguard Freshwater Ecosystems

By taking advantage of the work that healthy watersheds and freshwater ecosystems perform naturally, cities and rural areas can purify drinking water, alleviate hunger, mitigate flood damages, and meet other societal goals at a fraction of the cost of conventional technological alternatives. But because commercial markets rarely put a price on these "ecosystem services," and because governments around the world are failing to protect them, they are being lost at a rapid rate. Global warming is the wild card that could further exacerbate the impacts of human activities on the natural systems that safeguard our water supply -- impacts that include falling water tables, shrinking wetlands, vanishing species, and a decrease in both the quality and quantity of available freshwater

Molecular and functional analysis of the pathogen induced receptor-like kinase DRK3 from Arabidopsis thaliana

Pflanzen besitzen ein Immunsystem und sind dem Angriff von Pathogenen nicht wehrlos ausgesetzt, sondern zeigen Resistenz gegen eine Vielzahl möglicher Pathogene. Es wurde gezeigt, dass einige rezeptorähnliche Kinasen (RLKs) eine wichtige Rolle bei der Erkennung von pathogenspezifischen Strukturen und bei der Aktivierung von Abwehrreaktionen spielen. Ein gut untersuchtes Beispiel ist der Flagellinrezeptor FLS2. Dieser Rezeptor weist strukturelle Ähnlichkeiten zu TOLL-ähnlichen Rezeptoren aus Säugern auf, die in immunabwehr- und entwicklungspezifische Reaktionen involviert sind. In Microarray-Experimenten wurde gezeigt, dass die Expression von 49 RLKs durch bakterielle Pathogene oder Elizitoren induziert wird. Da hierzu auch FLS2 zählt, wurde angenommen, dass möglicherweise auch andere RLKs eine Funktion in Reaktionen der Immunabwehr besitzen. Eine dieser RLKs wurde in dieser Arbeit eingehend untersucht und als defence-related receptor kinase 3 (DRK3) bezeichnet. Ein knockout dieses Genes führt in Arabidopsis Pflanzen zu einer erhöhten Resistenz gegenüber dem virulenten Bakterium Pto DC3000. Dies geht mit einer verstärkten Produktion an reaktiven Sauerstoffspezies und einem vermehrten Auftreten von Zelltod einher. Unter Verwendung des Hefe-Dihybrid-Systems wurde nach mit dem DRK3-Protein interagierenden Proteinen gesucht. Hierbei konnte als potentieller Interaktionspartner ein Resistenzprotein, RLM3, identifiziert werden.Plants possess a powerful innate immune system to defend themselves against invading pathogens. The elucidation of the responsible mechanisms is an important research topic. It has already been shown that some receptor-like kinases (RLKs) are involved in the recognition of certain pathogen-specific structures and in the activation of immune response reactions in plants. One example is the flagellin receptor FLS2. This receptor resembles the modular structure of TOLL-like receptor (TLR) complexes that are known to be involved in innate immune reactions in animals. In microarray experiments it was shown that the transcript level of 49 RLKs is induced by infection with bacterial pathogens or elicitors. One of these RLKs is FLS2. Therefore it was assumed that other RLKs that are also upregulated upon pathogen and/or elicitor treatment might have a function in plant defence processes as well. One example is the defence-related receptor kinase (DRK3). The knockout of this gene leads to enhanced resistance of Arabidopsis plants to the virulent bacterial pathogen Pst DC3000. An increased production of reactive oxygen species (ROS) and enhanced cell-death reaction occur upon pathogen infection in knockout-plants. To elucidate the mechanisms underlying these phenomena a pathogen-induced cDNA-library was constructed and screened for interacting proteins that could explain the molecular function of this regulator of defence-reactions. The resistance protein RLM3 was identified as one interesting potential interaction partner of the DRK3