The Arabidopsis Malectin-Like/LRR-RLK IOS1 is Critical for BAK1-Dependent and BAK1-Independent Pattern-Triggered Immunity

Plasma membrane-localized pattern recognition receptors (PRRs) such as FLAGELLIN SENSING2 (FLS2), EF-TU RECEPTOR (EFR) and CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1) recognize microbe-associated molecular patterns (MAMPs) to activate pattern-triggered immunity (PTI). A reverse genetics approach on genes responsive to the priming agent beta-aminobutyric acid (BABA) revealed IMPAIRED OOMYCETE SUSCEPTIBILITY1 (IOS1) as a critical PTI player. Arabidopsis thaliana ios1 mutants were hyper-susceptible to Pseudomonas syringae bacteria. Accordingly, ios1 mutants showed defective PTI responses, notably delayed up-regulation of the PTI-marker gene FLG22-INDUCED RECEPTOR-LIKE KINASE1 (FRK1), reduced callose deposition and mitogen-activated protein kinase activation upon MAMP treatment. Moreover, Arabidopsis lines over-expressing IOS1 were more resistant to bacteria and showed a primed PTI response. In vitro pull-down, bimolecular fluorescence complementation, co-immunoprecipitation, and mass spectrometry analyses supported the existence of complexes between the membrane-localized IOS1 and BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1 (BAK1)-dependent PRRs FLS2 and EFR, as well as with the BAK1-independent PRR CERK1. IOS1 also associated with BAK1 in a ligand-independent manner, and positively regulated FLS2-BAK1 complex formation upon MAMP treatment. In addition, IOS1 was critical for chitin-mediated PTI. Finally, ios1 mutants were defective in BABA-induced resistance and priming. This work reveals IOS1 as a novel regulatory protein of FLS2-, EFR- and CERK1-mediated signaling pathways that primes PTI activation

Nonlinear absorption applications of CH₃NH₃PbBr₃ perovskite crystals

Researchers have recently revealed that hybrid lead halide perovskites exhibit ferroelectricity, which is often associated with other physical characteristics, such as a large nonlinear optical response. In this work, we study the non-linear optical properties of single crystal inorganic-organic hybrid perovskite CH3NH3PbBr3. By exciting the material with a 1044 nm laser, we were able to observe strong two-photon absorption-induced photoluminescence in the green spectral region. Using the transmission open-aperture Z-scan technique, we estimated the values of the two-photon absorption coefficient to be 8.5 cm GW-1, which is much higher than that of standard two-photon absorbing materials that are industrially used in nonlinear optical applications, such as LiNbO3, LiTaO3, KTiOPO4, and KH2PO4. Such a strong two-photon absorption effect in CH3NH3PbBr3 can be used to modulate the spectral and spatial profiles of laser pulses, as well as reduce noise, and can be used to strongly control the intensity of incident light. In this study, we demonstrate the superior optical limiting, pulse reshaping, and stabilization properties of CH3NH3PbBr3, opening new applications for perovskites in nonlinear optics

Metal contact and carrier transport in single crystalline CH3NH3PbBr3 perovskite

Organic-inorganic perovskites have arrived at the forefront of solar technology due to their impressive carrier lifetimes and superior optoelectronic properties. By having the cm-sized perovskite single crystal and employing device patterning techniques, and the transfer length method (TLM), we are able to get the insight into the metal contact and carrier transport behaviors, which is necessary for maximizing device performance and efficiency. In addition to the metal work function, we found that the image force and interface charge pinning effects also affect the metal contact, and the studied single crystal CH3NH3PbBr3 features Schottky barriers of 0.17 eV, 0.38 eV, and 0.47 eV for Au, Pt, and Ti electrodes, respectively. Furthermore, the surface charges lead to the thermally activated transport from 207 K to 300 K near the perovskite surface. In contrast, from 120 K to 207 K, the material exhibited three-dimensional (3D) variable range hopping (VRH) carrier transport behavior. Understanding these fundamental contact and transport properties of perovskite will enable future electronic and optoelectronic applications

Characterizing approach behavior of Drosophila melanogaster in Buridan's paradigm.

The Buridan's paradigm is a behavioral task designed for testing visuomotor responses or phototaxis in fruit fly Drosophila melanogaster. In the task, a wing-shortened fruit fly freely moves on a round platform surrounded by a 360° white screen with two vertical black stripes placed at 0° and 180°. A normal fly will tend to approach the stripes one at a time and move back and forth between them. A variety of tasks developed based on the Buridan's paradigm were designed to test other cognitive functions such as visual spatial memory. Although the movement patterns and the behavioral preferences of the flies in the Buridan's or similar tasks have been extensively studies a few decades ago, the protocol and experimental settings are markedly different from what are used today. We revisited the Buridan's paradigm and systematically investigated the approach behavior of fruit flies under different stimulus settings. While early studies revealed an edge-fixation behavior for a wide stripe in the initial visuomotor responses, we did not discover such tendency in the Buridan's paradigm when observing a longer-term behavior up to minutes, a memory-task relevant time scale. Instead, we observed robust negative photoaxis in which the flies approached the central part of the dark stripes of all sizes. In addition, we found that stripes of 20°-30° width yielded the best performance of approach. We further varied the luminance of the stripes and the background screen, and discovered that the performance depended on the luminance ratio between the stripes and the screen. Our study provided useful information for designing and optimizing the Buridan's paradigm and other behavioral tasks that utilize the approach behavior

Vitamin B Mitigates Thoracic Aortic Dilation in Marfan Syndrome Mice by Restoring the Canonical TGF-β Pathway

Thoracic aortic aneurysm (TAA) formation is a multifactorial process that results in diverse clinical manifestations and drug responses. Identifying the critical factors and their functions in Marfan syndrome (MFS) pathogenesis is important for exploring personalized medicine for MFS. Methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and methionine synthase reductase (MTRR) polymorphisms have been correlated with TAA severity in MFS patients. However, the detailed relationship between the folate-methionine cycle and MFS pathogenesis remains unclear. Fbn1C1039G/+ mice were reported to be a disease model of MFS. To study the role of the folate-methionine cycle in MFS, Fbn1C1039G/+ mice were treated orally with methionine or vitamin B mixture (VITB), including vitamins B6, B9, and B12, for 20 weeks. VITB reduced the heart rate and circumference of the ascending aorta in Fbn1C1039G/+ mice. Our data showed that the Mtr and Smad4 genes were suppressed in Fbn1C1039G/+ mice, while VITB treatment restored the expression of these genes to normal levels. Additionally, VITB restored canonical transforming-growth factor β (TGF-β) signaling and promoted Loxl1-mediated collagen maturation in aortic media. This study provides a potential method to attenuate the pathogenesis of MFS that may have a synergistic effect with drug treatments for MFS patients

Effects of Multi-Strain Probiotics on Immune Responses and Metabolic Balance in Helicobacter pylori-Infected Mice

Chronic inflammation caused by Helicobacter pylori infection increases the risk of developing gastric cancer. Even though the prevalence of H. pylori infection has been decreased in many regions, the development of antibiotic resistance strains has increased the difficulty of eradicating H. pylori. Therefore, exploring alternative approaches to combat H. pylori infection is required. It is well-known that probiotic therapy can improve H. pylori clearance. In this study, H. pylori-infected mice were treated with Lactobacillus fermentum P2 (P2), L. casei L21 (L21), L. rhamnosus JB3 (JB3), or a mixture including the aforementioned three (multi-LAB) for three days. All the lactic acid producing bacteria (LAB) treatments decreased H. pylori loads in the stomach and vacA gene expression, H. pylori specific immunoglobulin (Ig) A, and IgM levels in stomach homogenates, as well as serum levels of interferon-gamma and interleukin-1 beta. The multi-LAB and JB3 treatments further restored the superoxide dismutase and catalase activities suppressed by H. pylori infection. Furthermore, H. pylori infection decreased serum concentrations of 15 kinds of amino acids as well as palmitic acid. The multi-LAB treatment was able to recover the serum levels of alanine, arginine, aspartate, glycine, and tryptophan, which are all important in modulating immune functions. In addition, butyric acid, valeric acid, palmitic acid, palmitoleic acid, stearic acid, and oleic acid levels were increased. In this study, multi-LAB revealed its ability to adjust the composition of metabolites to improve health. To date, the mechanisms underlying how LAB strains crosstalk with the host are not fully understood. Identifying the mechanisms which are regulated by LABs will facilitate the development of effective therapies for infection in the future

Peptide‐functionalized double network hydrogel with compressible shape memory effect for intervertebral disc regeneration

Abstract As a prominent approach to treat intervertebral disc (IVD) degeneration, disc transplantation still falls short to fully reconstruct and restore the function of native IVD. Here, we introduce an IVD scaffold consists of a cellulose‐alginate double network hydrogel‐based annulus fibrosus (AF) and a cellulose hydrogel‐based nucleus pulposus (NP). This scaffold mimics native IVD structure and controls the delivery of Growth Differentiation Factor‐5 (GDF‐5), which induces differentiation of endogenous mesenchymal stem cells (MSCs). In addition, this IVD scaffold has modifications on MSC homing peptide and RGD peptide which facilitate the recruitment of MSCs to injured area and enhances their cell adhesion property. The benefits of this double network hydrogel are high compressibility, shape memory effect, and mechanical strength comparable to native IVD. In vivo animal study demonstrates successful reconstruction of injured IVD including both AF and NP. These findings suggest that this double network hydrogel can serve as a promising approach to IVD regeneration with other potential biomedical applications