Inflammatory, Oxidative Stress, and Apoptosis Effects in Zebrafish Larvae after Rapid Exposure to a Commercial Glyphosate Formulation

Glyphosate-based herbicides (GBH) are the most used herbicides in the world, carrying potentially adverse consequences to the environment and non-target species due to their massive and inadequate use. This study aimed to evaluate the effects of acute exposure to a commercial formulation of glyphosate, Roundup® Flex (RF), at environmentally relevant and higher concentrations in zebrafish larvae through the assessment of the inflammatory, oxidative stress and cell death response. Transgenic Tg(mpxGFP)i114 and wild-type (WT) zebrafish larvae (72 h post-fertilisation) were exposed to 1, 5, and 10 µg mL−1 of RF (based on the active ingredient concentration) for 4 h 30 min. A concentration of 2.5 µg mL−1 CuSO4 was used as a positive control. Copper sulphate exposure showed effectiveness in enhancing the inflammatory profile by increasing the number of neutrophils, nitric oxide (NO) levels, reactive oxygen species (ROS), and cell death. None of the RF concentrations tested showed changes in the number of neutrophils and NO. However, the concentration of 10 µg a.i. mL−1 was able to induce an increase in ROS levels and cell death. The activity of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)), the biotransformation activity, the levels of reduced (GSH) and oxidised (GSSG) glutathione, lipid peroxidation (LPO), lactate dehydrogenase (LDH), and acetylcholinesterase (AChE) were similar among groups. Overall, the evidence may suggest toxicological effects are dependent on the concentration of RF, although at concentrations that are not routinely detected in the environment. Additional studies are needed to better understand the underlying molecular mechanisms of this formulation.

Antifungal and Anti-Biofilm Effects of Caffeic Acid Phenethyl Ester on Different Candida Species

This study investigated the effect of CAPE on planktonic growth, biofilm-forming abilities, mature biofilms, and cell death of C. albicans, C. tropicalis, C. glabrata, and C. parapsilosis strains. Our results showed a strain- and dose-dependent effect of CAPE on Candida, and the MIC values were between 12.5 and 100 µg/mL. Similarly, the MBIC values of CAPE ranging between 50 and 100 µg/mL highlighted the inhibition of the biofilm-forming abilities in a dose-dependent manner, as well. However, CAPE showed a weak to moderate biofilm eradication ability (19-49%) on different Candida strains mature biofilms. Both caspase-dependent and caspase-independent apoptosis after CAPE treatment were observed in certain tested Candida strains. Our study has displayed typical apoptotic hallmarks of CAPE-induced chromatin margination, nuclear blebs, nuclear condensation, plasma membrane detachment, enlarged lysosomes, cytoplasm fragmentation, cell wall distortion, whole-cell shrinkage, and necrosis. In conclusion, CAPE has a concentration and strain-dependent inhibitory activity on viability, biofilm formation ability, and cell death response in the different Candida species.

The helper NLR immune protein NRC3 mediates the hypersensitive cell death caused by the cell-surface receptor Cf-4

Cell surface pattern recognition receptors (PRRs) activate immune responses that can include the hypersensitive cell death. However, the pathways that link PRRs to the cell death response are poorly understood. Here, we show that the cell surface receptor-like protein Cf-4 requires the intracellular nucleotide-binding domain leucine-rich repeat containing receptor (NLR) NRC3 to trigger a confluent cell death response upon detection of the fungal effector Avr4 in leaves of Nicotiana benthamiana. This NRC3 activity requires an intact N-terminal MADA motif, a conserved signature of coiled-coil (CC)-type plant NLRs that is required for resistosome-mediated immune responses. A chimeric protein with the N-terminal α1 helix of Arabidopsis ZAR1 swapped into NRC3 retains the capacity to mediate Cf-4 hypersensitive cell death. Pathogen effectors acting as suppressors of NRC3 can suppress Cf-4-triggered hypersensitive cell-death. Our findings link the NLR resistosome model to the hypersensitive cell death caused by a cell surface PRR.

Nuclear Localization of HopA1Pss61 Is Required for Effector-Triggered Immunity

Plant resistance proteins recognize cognate pathogen avirulence proteins (also named effectors) to implement the innate immune responses called effector-triggered immunity. Previously, we reported that hopA1 from Pseudomonas syringae pv. syringae strain 61 was identified as an avr gene for Arabidopsis thaliana. Using a forward genetic screen approach, we cloned a hopA1-specific TIR-NBS-LRR class disease resistance gene, RESISTANCE TO PSEUDOMONAS SYRINGAE6 (RPS6). Many resistance proteins indirectly recognize effectors, and RPS6 is thought to interact with HopA1Pss61 indirectly by surveillance of an effector target. However, the involved target protein is currently unknown. Here, we show RPS6 is the only R protein that recognizes HopA1Pss61 in Arabidopsis wild-type Col-0 accession. Both RPS6 and HopA1Pss61 are co-localized to the nucleus and cytoplasm. HopA1Pss61 is also distributed in plasma membrane and plasmodesmata. Interestingly, nuclear localization of HopA1Pss61 is required to induce cell death as NES-HopA1Pss61 suppresses the level of cell death in Nicotiana benthamiana. In addition, in planta expression of hopA1Pss61 led to defense responses, such as a dwarf morphology, a cell death response, inhibition of bacterial growth, and increased accumulation of defense marker proteins in transgenic Arabidopsis. Functional characterization of HopA1Pss61 and RPS6 will provide an important piece of the ETI puzzle.

Cytoplasmic and nuclear Sw-5b synergistically induce plant immune responses to inhibit different viral infection steps

Plant intracellular nucleotide binding-leucine-rich repeat (NLR) receptors play critical roles in mediating host immunity to pathogen attack. Successful virus infection in plant involves several essential steps including viral replication, intercellular and long-distance movement. How plant NLRs induce resistances against virus infection remains largely unknown. We demonstrated here that tomato NLR Sw-5b locates to cytoplasm and nucleus, respectively, to play different roles in inducing host resistances against tospovirus infection. The cytoplasmic Sw-5b functions to induce a strong cell death response to inhibit TSWV replication. This host response is, however, insufficient to block viral intercellular and long-distance movement. The nucleus-localized Sw-5b triggers a host defense that weakly inhibit viral replication but strongly impede virus intercellular and systemic movement. Furthermore, the cytoplasmic and nuclear Sw-5b act synergistically to confer a strong immunity to TSWV infection. Our finding adds a new knowledge to our current understanding on the plant NLRs-triggered immunity against virus infection.

Coiled-coil and RPW8-type immune receptors function at the plasma membrane in a phospholipid dependent manner

Activation of intracellular nucleotide-binding leucine-rich repeat receptors (NLRs) results in immunity and a localized cell death response of infected cells. Cell death activity of many NLRs requires oligomerization and in some cases plasma membrane (PM) localization. However, the exact mechanisms underlying PM localization of NLRs lacking recognizable N- or C-terminal lipidation motifs or predicted transmembrane domains remains elusive. Here we show that the PM localization and stability of members of the RPW8-like coiled-coil (CCR) domain NLRs (RNLs) and a CC-type NLR (CNL) depend on the interaction with PM phospholipids. Depletion of phosphatidylinositol-4-phosphate (PI4P) from the PM led to a mislocalization of the analyzed NLRs and consequently inhibited their cell death activity. We further demonstrate activation-dependent self-association of cell death inducing RNLs. Our results provide new insights into the molecular mechanism of NLR PM localization and defines an important role of phospholipids for CNL and RNL activity during immunity.

Endocrine disruption and female reproductive health: Implications on cross-talk between endocrine and autocrine/paracrine axes in the ovary

Female reproduction is a blend of neuroendocrine, endocrine, and autocrine/paracrine factors that maintain the appropriate ovarian micro-environment. The growing urbanization prompted exposure to a myriad of environmental toxins carrying the ability to interfere with reproductive processes governed by endogenous hormones, making reproductive health a major global concern. These environmental anthropogenic contaminants, popularly termed as endocrine-disrupting chemicals (EDCs), can disrupt the ovarian homeostasis leading to serious perturbations, namely, anovulation, infertility, estrogen deficiency, and premature ovarian failure. Although gonadotropin action, biosynthesis of gonadal steroids vis-à-vis growth factors comprise the essential modulators within the ovary, the redox balance along with inflammatory and cell death response can dramatically influence the framework of ovarian dynamics; however, details of which remain relatively less understood. The present overview provides an update on candidates (endocrines and autocrine/paracrine) of oogenesis, and the potential impact of EDCs on diverse intra-ovarian entities including but not limited to gonadotropin action, steroidogenic potential, expression of growth factors, and modulation of maturational competence. Moreover, the relative importance of free radical-induced stress, inflammation, and elevated cell death (follicular atresia), in the regulation of ovarian functions and how these intricate yet conjoined mechanisms may alter the reproductive performance of a female will be an issue of discussion.

Analysis of common glucocorticoid response genes in childhood acute lymphoblastic leukemia in vivo identifies cell cycle but not apoptosis genes

Glucocorticoids (GCs) are an essential component of acute lymphoblastic leukemia (ALL) therapy. To identify genes mediating the anti-leukemic GC effects in vivo, we performed gene expression profiling of lymphoblasts from 46 children during the first 6-24h of systemic GC mono-therapy. Differential gene expression analysis across all patients revealed a considerable number of GC-regulated genes (190 induced, 179 repressed at 24h). However, when 4 leukemia subtypes (T-ALL, ETV6-RUNX1+, hyperdiploid, other preB-ALLs) were analyzed individually only 17 genes were regulated in all of them showing subtype-specificity of the transcriptional response. Cell cycle-related genes were down-regulated in the majority of patients, while no common changes in apoptosis genes could be identified. Surprisingly, none of the cell cycle or apoptosis genes correlated well with the reduction of peripheral blasts used as parameter for treatment response. These data suggest that (a) GC effects on cell cycle are independent of the cell death response and (b) GC-induced cell death cannot be explained by a single transcriptional pathway conserved in all subtypes. To unravel more complex, potentially novel pathways, we employed machine learning algorithms using an iterative elastic net approach, which identified gene expression signatures that correlated with the clinical response.