Fluoride-Induced Expression of Neuroinflammatory Markers and Neurophysiological Regulation in the Brain of Wistar Rat Model.

Excess fluoride intake has been linked with various pathological conditions. The objective of the present study was to understand the role of fluoride in neurotoxic, neuroinflammatory, and neurodegenerative changes in the brain tissue of Wistar rats. Wistar rats were fed with water containing 20-100 ppm (ppm) sodium fluoride (NaF). An array of neurotransmitters (acetylcholine, dopamine, epinephrine, norepinephrine, serotonin, histamine, and glutamate) expression levels were estimated with respect to different fluoride concentrations. Additionally, its effect on the expression levels of specific neuroinflammatory markers (iNOS, COX-2, TNF-α, PKC, VEGF, and HSP-70) in brain tissues of Wister rats was assessed. An increase in NaF concentration resulted in increased fluoride deposition in the brain which in turn caused increase levels of epinephrine, histamine, serotonin, and glutamate and decreased levels of norepinephrine, acetylcholine, and dopamine in a dose-dependent manner. Tissue fluoride levels of the hippocampus, neocortex, cerebellum, spinal cord, and sciatic nerve increased significantly in fluoride fed rats. Transmission electron microscopy in the experimental animals revealed axon deterioration, myelin sheath degeneration, and dark cells with scanty cytoplasm in the spinal cord and sciatic nerve. Additionally, vacuolated swollen mitochondria were observed in the neocortex, hippocampus, and cerebellum. Results suggest excess fluoride intake modulates a set of biological marker and promote neuroinflammatory and neurodegenerative condition in Wister rats. Therefore, we conclude that the accumulation of NaF alters the neurological function which leads to neurodegenerative disorders.

Author Correction: Methane utilization in Methylomicrobium alcaliphilum 20ZR: a systems approach.

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Methane utilization in Methylomicrobium alcaliphilum 20ZR: a systems approach.

Biological methane utilization, one of the main sinks of the greenhouse gas in nature, represents an attractive platform for production of fuels and value-added chemicals. Despite the progress made in our understanding of the individual parts of methane utilization, our knowledge of how the whole-cell metabolic network is organized and coordinated is limited. Attractive growth and methane-conversion rates, a complete and expert-annotated genome sequence, as well as large enzymatic, 13C-labeling, and transcriptomic datasets make Methylomicrobium alcaliphilum 20ZR an exceptional model system for investigating methane utilization networks. Here we present a comprehensive metabolic framework of methane and methanol utilization in M. alcaliphilum 20ZR. A set of novel metabolic reactions governing carbon distribution across central pathways in methanotrophic bacteria was predicted by in-silico simulations and confirmed by global non-targeted metabolomics and enzymatic evidences. Our data highlight the importance of substitution of ATP-linked steps with PPi-dependent reactions and support the presence of a carbon shunt from acetyl-CoA to the pentose-phosphate pathway and highly branched TCA cycle. The diverged TCA reactions promote balance between anabolic reactions and redox demands. The computational framework of C1-metabolism in methanotrophic bacteria can represent an efficient tool for metabolic engineering or ecosystem modeling.

Discovery of a novel insecticidal protein from Chromobacterium piscinae, with activity against Western Corn Rootworm, Diabrotica virgifera virgifera.

Western corn rootworm (WCR), Diabrotica virgifera virgifera, is one of the most significant pests of corn in the United States. Although transgenic solutions exist, increasing resistance concerns make the discovery of novel solutions essential. In order to find a novel protein with high activity and a new mode of action, a large microbial collection was surveyed for toxicity to WCR using in vitro bioassays. Cultures of strain ATX2024, identified as Chromobacterium piscinae, had very high activity against WCR larvae. The biological activity from the strain was purified using chromatographic techniques and fractions were tested against WCR larvae. Proteins in the final active fraction were identified by mass spectrometry and N-terminal sequencing and matched to the genome of ATX2024. A novel 58.9kDa protein, identified by this approach, was expressed in a recombinant expression system and found to have specific activity against WCR. Transgenic corn events containing this gene showed good protection against root damage by WCR, with average scores ranging between 0.01 and 0.04 on the Iowa State node injury scale. Sequence analysis did not reveal homology to any known insecticidal toxin, suggesting that this protein may act in a novel way to control WCR. The new WCR active protein is named GNIP1Aa, for Gram Negative Insecticidal Protein.

Organ-specific metabolic responses to drought in Pinus pinaster Ait.

Drought is an important driver of plant survival, growth, and distribution. Water deficit affects different pathways of metabolism, depending on plant organ. While previous studies have mainly focused on the metabolic drought response of a single organ, analysis of metabolic differences between organs is essential to achieve an integrated understanding of the whole plant response. In this work, untargeted metabolic profiling was used to examine the response of roots, stems, adult and juvenile needles from Pinus pinaster Ait. full-sib individuals, subjected to a moderate and long lasting drought period. Cyclitols content showed a significant alteration, in response to drought in all organs examined, but other metabolites increased or decreased differentially depending on the analyzed organ. While a high number of flavonoids were only detected in aerial organs, an induction of the glutathione pathway was mainly detected in roots. This result may reflect different antioxidant mechanisms activated in aerial organs and roots. Metabolic changes were more remarkable in roots than in the other organs, highlighting its prominent role in the response to water stress. Significant changes in flavonoids and ascorbate metabolism were also observed between adult and juvenile needles, consistent with previously proven differential functional responses between the two developmental stages. Genetic polymorphisms in candidate genes coding for a Myb1 transcription factor and a malate dehydrogenase (EC 1.1.1.37) were associated with different concentration of phenylalanine, phenylpropanoids and malate, respectively. The results obtained will support further research on metabolites and genes potentially involved in functional mechanisms related to drought tolerance in trees.

The plant immunity inducer pipecolic acid accumulates in the xylem sap and leaves of soybean seedlings following Fusarium virguliforme infection.

The causal agent of the soybean sudden death syndrome (SDS), Fusarium virguliforme, remains in infected roots and secretes toxins to cause foliar SDS. In this study we investigated the xylem sap, roots, and leaves of F. virguliforme-infected and -uninfected soybean seedlings for any changes in a set of over 3,000 metabolites following pathogen infection by conducting GC/MS and LC/MS/MS, and detected 273 biochemicals. Levels of many intermediates of the TCA cycle were reduced suggesting suppression of this metabolic pathway by the pathogen. There was an increased accumulation of peroxidated lipids in leaves of F. virguliforme-infected plants suggesting possible involvement of free radicals and lipoxygenases in foliar SDS development. Levels of both isoflavone conjugates and isoflavonoid phytoalexins were decreased in infected roots suggesting degradation of these metabolites by the pathogen to promote root necrosis. The levels of the plant immunity inducer pipecolic acid (Pip) and the plant hormone salicylic acid (SA) were significantly increased in xylem sap (in case of Pip) and leaves (in case of both Pip and SA) of F. virguliforme-infected soybean plants compared to the control plants. This suggests a major signaling role of Pip in inducing host defense responses in above ground parts of the F. virguliforme-infected soybean. Increased accumulation of pipecolic acid in foliar tissues was associated with the induction of GmALD1, the soybean homolog of Arabidopsis ALD1. This metabolomics study generated several novel hypotheses for studying the mechanisms of SDS development in soybean.

Transcriptome and metabolite profiling of the infection cycle of Zymoseptoria tritici on wheat reveals a biphasic interaction with plant immunity involving differential pathogen chromosomal contributions and a variation on the hemibiotrophic lifestyle definition.

The hemibiotrophic fungus Zymoseptoria tritici causes Septoria tritici blotch disease of wheat (Triticum aestivum). Pathogen reproduction on wheat occurs without cell penetration, suggesting that dynamic and intimate intercellular communication occurs between fungus and plant throughout the disease cycle. We used deep RNA sequencing and metabolomics to investigate the physiology of plant and pathogen throughout an asexual reproductive cycle of Z. tritici on wheat leaves. Over 3,000 pathogen genes, more than 7,000 wheat genes, and more than 300 metabolites were differentially regulated. Intriguingly, individual fungal chromosomes contributed unequally to the overall gene expression changes. Early transcriptional down-regulation of putative host defense genes was detected in inoculated leaves. There was little evidence for fungal nutrient acquisition from the plant throughout symptomless colonization by Z. tritici, which may instead be utilizing lipid and fatty acid stores for growth. However, the fungus then subsequently manipulated specific plant carbohydrates, including fructan metabolites, during the switch to necrotrophic growth and reproduction. This switch coincided with increased expression of jasmonic acid biosynthesis genes and large-scale activation of other plant defense responses. Fungal genes encoding putative secondary metabolite clusters and secreted effector proteins were identified with distinct infection phase-specific expression patterns, although functional analysis suggested that many have overlapping/redundant functions in virulence. The pathogenic lifestyle of Z. tritici on wheat revealed through this study, involving initial defense suppression by a slow-growing extracellular and nutritionally limited pathogen followed by defense (hyper) activation during reproduction, reveals a subtle modification of the conceptual definition of hemibiotrophic plant infection.