β-N-Methylamino-L-alanine (BMAA) perturbs alanine, aspartate and glutamate metabolism pathways in human neuroblastoma cells as determined by metabolic profiling

Metabolomic analysis reveals an important role of sphingosine 1-phosphate in the development of HFMD due to EV-A71 infection

Hand, foot, and mouth disease (HFMD) is a serious pediatric infectious disease that causes immeasurable physical and mental health burdens. Currently, there is a lack of information on the mechanisms of HFMD severity and early diagnosis. We performed metabolomic profiling of sera from 84 Enterovirus A71 (EV-A71) infections and 45 control individuals. Targeted metabolomics assays were employed to further validate some of the differential metabolic molecules. We identified significant molecular changes in the sera of HFMD patients compared to healthy controls (HCs). A total of 54, 60, 35, and 62 differential metabolites were screened between mild cases and HCs, severe cases and HCs, severe cases and mild cases, and among the three groups, respectively. These differential metabolites implicated dysregulation of the tricarboxylic acid cycle, alanine, aspartate, and glutamate metabolism, and valine, leucine, and isoleucine biosynthesis. The diagnostic panel based on some overlapped differential metabolites could effectively discriminate severe cases from mild cases with an AUC of 0.912 (95% CI: 0.85-0.97) using the logistic regression model. Next, we found the elevation of serum sphingosine 1-phosphate (S1P) level in EV-A71 infection mice, which was similar to clinical observation. Importantly, after blocking the release of S1P by MK571, the clinical symptoms and survival of mice were significantly improved, involving the reduction of leukocyte infiltration in infected brain tissues. Collectively, our data provided a landscape view of metabolic alterations in EV-A71 infected children and revealed regulating S1P metabolism was an exploitable therapeutic target against EV-A71 infection.

Comprehensive untargeted polar metabolite analysis using solvent switching liquid chromatography tandem mass spectrometry

Metabolomics analyses enable the examination and identification of endogenous biochemical reaction products, revealing information on the metabolic pathways and processes active within a living cell or organism. Determination of metabolic shifts can provide important information on a treatment or disease. Unlike other omics fields that typically have analytes of the same chemical class with common building blocks, those that fall under the nomenclature of metabolites encompass a wide array of different compounds with very diverse physiochemical properties. Development of a comprehensive metabolomic pipeline therefore can be a troublesome and complicated process for the analyst. Often single liquid chromatography-mass spectrometry methods on unfractionated samples are carried out in order to be time-efficient, however this could potentially produce data with a low number of identifiable metabolites. In the present studies, we developed a comprehensive polar metabolomics pipeline for cell-based metabolomics. SH-SY5Y neuroblastoma cells were selected as the sample matrix for method development since they are one of the most widely used cell lines for human neurotoxicity studies. This was accomplished by investigating and optimising different mass spectrometry source and chromatographic conditions to enhance the signal of polar metabolites. Optimised hydrophilic interaction liquid chromatography (HILIC) based metabolomic methods at different pH values were examined in positive, negative, and polarity switching modes to determine which combination yielded the highest number of confidently identified metabolites. Additionally, the use of sequentially running two methods was also compared to determine the degree of overlap and whether there is merit in running two separate methods on one sample. It was determined that solvent switching between two optimised methods, acidic chromatographic conditions in positive mode and basic chromatographic conditions in negative mode, yielded the highest number of unique identifiable metabolites. This could be run in a single analytical batch due to the large pH range of the column. A quick switch method in-between each method allowed both conditioning the column and preparation of the MS source conditions for the sequential method.

Integrated analysis of transcriptome and metabolome reveals chronic low salinity stress responses in the muscle of Exopalaemon carinicauda

Low salinity environment is one of the key factors threatening the survival of aquatic organisms. Due to the strong adaptability of low salinity, Exopalaemon carinicauda is an ideal model to study the low salinity adaptation mechanism of crustaceans. In this study, E. carinicauda from the same family were divided into two groups, which were reared at salinity of 4 ‰ and 30 ‰, respectively. Integrated analysis of transcriptome and metabolome was used to uncover the mechanisms of E. carinicauda adaptation to chronic low salinity environment. Under the chronic low salinity stress, a total of 651 differentially expressed genes (DEGs) and 386 differential metabolites (DMs) were obtained, with the majority showing downregulation. These DEGs mainly involved MAPK signal transduction pathway and structural constituent of cuticle. Besides, chitin binding and chitin metabolism process were inhibited significantly. Among the DMs, lipids and lipid-like molecules, flavor amino acids and nucleotides were detected, which may be related to the adjustment of energy metabolism and flavor of muscle. In addition, ubiquinone and other terpenoid-quinone biosynthesis pathway and alanine, aspartate, and glutamate metabolic pathway were induced. These results will enrich our understanding of the molecular mechanism underlying the chronic low salinity tolerance in E. carinicauda, providing an important theoretical basis and practical guidance for the research and breeding, thereby promoting the sustainable development of aquaculture.

Polysaccharides from Alpinia oxyphylla fruit prevent hyperuricemia by inhibiting uric acid synthesis, modulating intestinal flora and reducing renal inflammation

Hyperuricemia (HUA) is one of the most common chronic diseases today, with a prevalence exceeding 14 % in both the United States and China. Current clinical treatments for HUA focus on promoting uric acid (UA) excretion and inhibiting UA production, but often neglect the strain on the liver and kidneys. The fruit of Alpinia oxyphylla (A. oxyphylla) is known to improve renal function, regulate metabolism, and exhibit anti-inflammatory effects; however, its effectiveness and mechanisms in treating HUA are not well understood. In this study, HUA mice induced by potassium oxonate and adenine were treated with A. oxyphylla polysaccharide (AFP) for 21 days. The levels associated with HUA were quantified using assay kits to evaluate the impact of AFP on HUA. Serum metabolomics and 16S rRNA sequencing were used to investigate the mechanisms by which AFP ameliorates HUA. The results showed that AFP treatment reduced abnormal biochemical levels, including UA, blood urea nitrogen, and creatinine, in HUA mice. AFP inhibited UA synthesis by regulating pyrimidine metabolism and the metabolism of alanine, aspartate and glutamate, reduced kidney inflammation, and promoted UA excretion by regulating intestinal flora. Thus, AFP appears to be an effective agent for alleviating HUA symptoms.

Insights into the synergistic toxicity mechanisms caused by nano- and microplastics with triclosan using a dose-dependent functional genomics approach in Saccharomyces cerevisiae

The emergence of polystyrene (PS) nano- and microplastics (NMPs) and triclosan (TCS) as environmental contaminants has raised concerns about their combined toxicities to organisms, but the complex toxicity arising from their interactions and the underlying molecular mechanisms remain obscure to us. In this study, we comprehensively detected the combined toxicity of PS-NMPs and TCS via the dose-dependent yeast functional genomics profiling. Firstly, our findings demonstrated that the combined exposure to PS-NMPs and TCS elicited a synergistic toxic effect in which the toxicity depended on the size of the PS-NMPs. Secondly, we found that TCS exposure, either alone or in combination with PS-NMPs, influenced lipid biosynthetic processes and ATP export pathways, while the unique responsive genes triggered by combined exposure to TCS and PS-NMPs are significantly enriched in mitochondrial translation, ribosomal small subunit assembly, and tRNA wobble uridine modification. Thirdly, our results demonstrated that point of departure (POD) at the pathway level was positively correlated with IC50, and POD was a more sensitive predictor of toxicity than the apical toxicity endpoints. More importantly, our findings suggested that the combined exposure of PS-NMPs in a size-dependent manner not only alleviated the harmful effects of TCS on glycerophospholipid metabolism, but also exacerbated its negative impact on oxidative phosphorylation. Collectively, our study not only provides new insights into the intricate molecular mechanisms that control the combined toxicity of PS-NMPs and TCS, but also confirms the effectiveness of the dose-dependent functional genomics approach in elucidating the molecular mechanisms of the combined toxicity of pollutants.

Comparative 1H NMR-Based Metabolomics of Traditional Landrace and Disease-Resistant Chili Peppers (Capsicum annuum L.)

Chili peppers (Capsicum annuum L.) are economically valuable crops belonging to the Solanaceae family and are popular worldwide because of their unique spiciness and flavor. In this study, differences in the metabolomes of landrace (Subicho) and disease-resistant pepper cultivars (Bulkala and Kaltanbaksa) widely grown in Korea are investigated using a 1H NMR-based metabolomics approach. Specific metabolites were abundant in the pericarp (GABA, fructose, and glutamine) and placenta (glucose, asparagine, arginine, and capsaicin), highlighting the distinct physiological and functional roles of these components. Both the pericarp and placenta of disease-resistant pepper cultivars contained higher levels of sucrose and hexoses and lower levels of alanine, proline, and threonine than the traditional landrace cultivar. These metabolic differences are linked to enhanced stress tolerance and the activation of defense pathways, imbuing these cultivars with improved resistance characteristics. The present study provides fundamental insights into the metabolic basis of disease resistance in chili peppers, emphasizing the importance of multi-resistant varieties to ensure sustainable agriculture and food security. These resistant varieties ensure a stable supply of high-quality peppers, contributing to safer and more sustainable food production systems.

Codonopsis pilosula water extract delays D-galactose-induced aging of the brain in mice by activating autophagy and regulating metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Codonopsis pilosula (C. pilosula), also called "Dangshen" in Chinese, is derived from the roots of Codonopsis pilosula (Franch.) Nannf. (C. pilosula), Codonopsis pilosula var. Modesta (Nannf.) L.D.Shen (C. pilosula var. modesta) or Codonopsis pilosula subsp. Tangshen (Oliv.) D.Y.Hong (C. pilosula subsp. tangshen), is a well-known traditional Chinese medicine. It has been regularly used for anti-aging, strengthening the spleen and tonifying the lungs, regulating blood sugar, lowering blood pressure, strengthening the body's immune system, etc. However, the mechanism, by which, C. pilosula exerts its therapeutic effects on brain aging remains unclear.

AIM OF THE STUDY

This study aimed to investigate the underlying mechanisms of the protective effects of C. pilosula water extract (CPWE) on the hippocampal tissue of D-galactose-induced aging mice.

MATERIALS AND METHODS

In this research, plant taxonomy has been confirmed in the "The Plant List" database (www.theplantlist.org). First, an aging mouse model was established through the intraperitoneal injections of D-galactose solution, and low-, medium-, and high-dose CPWE were administered to mice by gavage for 42 days. Then, the learning and memory abilities of the mice were examined using the Morris water maze tests and step-down test. Hematoxylin and eosin staining was performed to visualize histopathological damage in the hippocampus. A transmission electron microscope was used to observe the ultrastructure of hippocampal neurons. Immunohistochemical staining was performed to examine the expression of glial fibrillary acidic protein (GFAP), the marker protein of astrocyte activation, and autophagy-related proteins, including microtubule-associated protein light chain 3 (LC3) and sequestosome 1 (SQSTM1)/p62, in the hippocampal tissues of mice. Moreover, targeted metabolomic analysis was performed to assess the changes in polar metabolites and short-chain fatty acids in the hippocampus.

RESULTS

First, CPWE alleviated cognitive impairment and ameliorated hippocampal tissue damage in aging mice. Furthermore, CPWE markedly alleviated mitochondrial damage, restored the number of autophagosomes, and activated autophagy in the hippocampal tissue of aging mice by increasing the expression of LC3 protein and reducing the expression of p62 protein. Meanwhile, the expression levels of the brain injury marker protein GFAP decreased. Moreover, quantitative targeted metabolomic analysis revealed that CPWE intervention reversed the abnormal levels of L-asparagine, L-glutamic acid, L-glutamine, serotonin hydrochloride, succinic acid, and acetic acid in the hippocampal tissue of aging mice. CPWE also significantly regulated pathways associated with D-glutamine and D-glutamate metabolism, nitrogen metabolism, arginine biosynthesis, alanine, aspartate, and glutamate metabolisms, and aminoacyl-tRNA biosynthesis.

CONCLUSIONS

CPWE could improve cognitive and pathological conditions induced by D-galactose in aging mice by activating autophagy and regulating metabolism, thereby slowing down brain aging.

Jianpi Gushen Huayu decoction ameliorated diabetic nephropathy through modulating metabolites in kidney, and inhibiting TLR4/NF-κB/NLRP3 and JNK/P38 pathways

BACKGROUND

Jianpi Gushen Huayu Decoction (JPGS) has been used to clinically treat diabetic nephropathy (DN) for many years. However, the protective mechanism of JPGS in treating DN remains unclear.

AIM

To evaluate the therapeutic effects and the possible mechanism of JPGS on DN.

METHODS

We first evaluated the therapeutic potential of JPGS on a DN mouse model. We then investigated the effect of JPGS on the renal metabolite levels of DN mice using non-targeted metabolomics. Furthermore, we examined the effects of JPGS on c-Jun N-terminal kinase (JNK)/P38-mediated apoptosis and the inflammatory responses mediated by toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB)/NOD-like receptor family pyrin domain containing 3 (NLRP3).

RESULTS

The ameliorative effects of JPGS on DN mice included the alleviation of renal injury and the control of inflammation and oxidative stress. Untargeted metabolomic analysis revealed that JPGS altered the metabolites of the kidneys in DN mice. A total of 51 differential metabolites were screened. Pathway analysis results indicated that nine pathways significantly changed between the control and model groups, while six pathways significantly altered between the model and JPGS groups. Pathways related to cysteine and methionine metabolism; alanine, tryptophan metabolism; aspartate and glutamate metabolism; and riboflavin metabolism were identified as the key pathways through which JPGS affects DN. Further experimental validation showed that JPGS treatment reduced the expression of TLR4/NF-κB/NLRP3 pathways and JNK/P38 pathway-mediated apoptosis related factors.

CONCLUSION

JPGS could markedly treat mice with streptozotocin (STZ)-induced DN, which is possibly related to the regulation of several metabolic pathways found in kidneys. Furthermore, JPGS could improve kidney inflammatory responses and ameliorate kidney injuries in DN mice via the TLR4/NF-κB/NLRP3 pathway and inhibit JNK/P38 pathway-mediated apoptosis in DN mice.

Effects of the Toxic Non-Protein Amino Acid β-Methylamino-L-Alanine (BMAA) on Intracellular Amino Acid Levels in Neuroblastoma Cells

The cyanobacterial non-protein amino acid (AA) β-Methylamino-L-alanine (BMAA) is considered to be a neurotoxin. BMAA caused histopathological changes in brains and spinal cords of primates consistent with some of those seen in early motor neuron disease; however, supplementation with L-serine protected against some of those changes. We examined the impact of BMAA on AA concentrations in human neuroblastoma cells in vitro. Cells were treated with 1000 µM BMAA and intracellular free AA concentrations in treated and control cells were compared at six time-points over a 48 h culture period. BMAA had a profound effect on intracellular AA levels at specific time points but in most cases, AA homeostasis was re-established in the cell. The most heavily impacted amino acid was serine which was depleted in BMAA-treated cells from 9 h onwards. Correction of serine depletion could be a factor in the observation that supplementation with L-serine protects against BMAA toxicity in vitro and in vivo. AAs that could potentially be involved in protection against BMAA-induced oxidation such as histidine, tyrosine, and phenylalanine were depleted in cells at later time points.

Microglia-containing cerebral organoids derived from induced pluripotent stem cells for the study of neurological diseases

Microglia play an important role in neuroinflammation and neurodegeneration. Here, we report an approach for generating microglia-containing cerebral organoids derived from human pluripotent stem cells involving the supplementation of growth factors (FGF, EGF, heparin) and 10% CO2 culture conditions. Using this platform, Western Pacific Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia Complex (ALS-PDC) cerebral organoids were generated from patient-derived induced pluripotent stem cells (iPSCs). These ALS-PDC-affected organoids had more reactive astrocytes and M1 microglia, and had fewer M2 microglia than their unaffected counterparts, leading to impaired microglia-mediated phagocytosis. RNA-seq analysis of ALS-PDC and control organoids indicated that the most significant changes were microglia- and astrocyte-related genes (IFITM1/2, TGF-β, and GFAP). The most significantly downregulated pathway was type I interferon signaling. Interferon-gamma supplementation increased IFITM expression, enhanced microglia-mediated phagocytosis, and reduced beta-amyloid accumulation in ALS-PDC-affected network. The results demonstrated the feasibility of using microglia-containing organoids for the study of neurodegenerative diseases.

The biotoxin BMAA promotes dysfunction via distinct mechanisms in neuroblastoma and glioblastoma cells

Chronic exposure to the Cyanobacteria biotoxin Beta-methylamino-L-alanine (BMAA) has been associated with development of a sporadic form of ALS called Amyotrophic Lateral Sclerosis/Parkinsonism-Dementia Complex (ALS/PDC), as observed within certain Indigenous populations of Guam and Japan. Studies in primate models and cell culture have supported the association of BMAA with ALS/PDC, yet the pathological mechanisms at play remain incompletely characterized, effectively stalling the development of rationally-designed therapeutics or application of preventative measures for this disease. In this study we demonstrate for the first time that sub-excitotoxic doses of BMAA modulate the canonical Wnt signaling pathway to drive cellular defects in human neuroblastoma cells, suggesting a potential mechanism by which BMAA may promote neurological disease. Further, we demonstrate here that the effects of BMAA can be reversed in cell culture by use of pharmacological modulators of the Wnt pathway, revealing the potential value of targeting this pathway therapeutically. Interestingly, our results suggest the existence of a distinct Wnt-independent mechanism activated by BMAA in glioblastoma cells, highlighting the likelihood that neurological disease may result from the cumulative effects of distinct cell-type specific mechanisms of BMAA toxicity.

Whole-transcriptome profiling across different developmental stages of Aedes albopictus (Diptera: Culicidae) provides insights into chitin-related non-coding RNA and competing endogenous RNA networks

BACKGROUND

The Asian tiger mosquito, Aedes albopictus, is one of the most invasive species and a vector of numerous arboviruses. The deleterious effects of long-term and inappropriate use of chemical pesticides have stimulated the exploration of new, environmentally friendly control strategies. Non-coding RNAs (ncRNAs) have been proven to participate in almost all biological processes of insects.

METHODS

In this study, circular RNAs (circRNAs) and microRNAs (miRNAs) covering five developmental stages [egg, early larvae, late larvae, pupae, adult (female and male)] of A. albopictus were obtained using whole-transcriptome sequencing technology. Combined with long non-coding RNAs (lncRNAs) from previous research, circRNA/lncRNA‒miRNA‒mitochondrial RNA (mRNA) networks were constructed.

RESULTS

A total of 1434 circRNAs and 208 miRNAs were identified. More differentially expressed circRNAs (DE circRNAs) and miRNAs (DE miRNAs) were found in the egg versus early larvae comparison group. Functional enrichment analysis demonstrated that most of the circRNA/lncRNA‒miRNA‒mRNA networks were involved in chitin metabolism. Hub genes of each circRNA/lncRNA‒miRNA‒mRNA network were screened out, which can be used as novel targets to disturb the molting process of A. albopictus.

CONCLUSIONS

Regulatory relationships obtained from competing endogenous RNA (ceRNA) networks provide more information to manipulate the metamorphosis process and are helpful for developing effective and sustainable methods to control mosquitoes.

Mutation analysis of the WFS1 gene in a Chinese family with autosomal-dominant non-syndrome deafness

To analyse the pathogenic genes and mutations of a family with hereditary deafness. We recruited a three-generation family with NSHL. A detailed medical history inquiry and related examinations were performed. Next-generation sequencing (NGS) was used to confirm the gene mutation in the proband, and Sanger sequencing was used for verification. The effect of the WFS1 mutation on the function and structure of the wolframin protein was predicted by multiple computational software. From the Gene Expression Omnibus (GEO) database, we obtained GSE40585 dataset and performed enrichment analyses. The family clinically manifested as autosomal dominant NSHL. A novel WFS1 c.2421C>G (p.Ser807Arg) mutation was identified in four affected individuals in the pedigree . The p.Ser807Arg mutation is a highly conserved residue and causes an increase in protein stability. It had an important influence on not only amino acid size, charge and hydrophobicity but also protein intermolecular hydrogen bonding and spatial structure. There were differentially expressed genes (DEGs) in GSE40585 dataset. Enrichment analysis revealed that DEGs mainly functioned in amino acid metabolism, signal transduction and dephosphorylation. We reported a novel mutation c.2421C>G (p.Ser807Arg in WFS1. This study expands the mutation spectrum of WFS1.

The Anti-Cancer Effects of Mitochondrial-Targeted Triphenylphosphonium-Resveratrol Conjugate on Breast Cancer Cells

Breast cancer is the most commonly diagnosed cancer in women. Resveratrol, a naturally occurring phytochemical, shows great promise in developing novel anti-cancer therapies. This study hypothesized that the mitochondria-targeted delivery of resveratrol would increase its potency and induce mitochondria-mediated apoptosis. The targeted delivery of resveratrol was achieved by conjugating resveratrol to triphenylphosphonium (TPP). The anti-cancer effects of TPP-resveratrol were studied in the murine breast cancer 4T1 and the human breast cancer MDA-MB-231 cell lines. Flow cytometry was used to study apoptosis induction, cell cycle arrest, and mitochondrial membrane potential loss. The morphological changes in the mitochondria in MDA-MB-231 cells after TPP-resveratrol treatments were examined using transmission electron microscopy. Moreover, the changes in MDA-MB-231 cell metabolism after resveratrol and TPP-resveratrol treatments were studied using metabolomic analysis. We demonstrate that TPP-resveratrol significantly improved cytotoxicity in 4T1 cells and MDA-MB-231 cells by inducing apoptosis and mitochondrial membrane potential loss. Swollen and vacuolated mitochondria were observed after the TPP-resveratrol treatment. Meanwhile, TPP-resveratrol treatment down-regulated amino acid and energy metabolism and caused the dysfunction of purine and pyrimidine metabolism. Our results provide evidence supporting the targeted delivery of resveratrol to mitochondria and suggest that TPP-resveratrol may be an effective agent for breast cancer treatment.

Comparative Metabolomics Study of the Impact of Articaine and Lidocaine on the Metabolism of SH-SY5Y Neuronal Cells

Articaine (ATC) and lidocaine (LDC) are the local anesthetics (LAs) currently most employed in dentistry. Cases of paresthesia, reported more frequently for ATC, have raised concerns about their potential neurotoxicity, calling for further investigation of their biological effects in neuronal cells. In this work, the impact of ATC and LDC on the metabolism of SH-SY5Y cells was investigated through 1H NMR metabolomics. For each LA, in vitro cultured cells were exposed to concentrations causing 10 and 50% reductions in cell viability, and their metabolic intracellular and extracellular profiles were characterized. Most effects were common to ATC and LDC, although with varying magnitudes. The metabolic variations elicited by the two LAs suggested (i) downregulation of glycolysis and of glucose-dependent pathways (e.g., one-carbon metabolism and hexosamine biosynthetic pathway), (ii) disturbance of branched chain amino acids (BCAA) catabolism, (iii) downregulation of TCA cycle anaplerotic fueling and activation of alternative energy producing pathways, (iv) interference with choline metabolism and (v) lipid droplet build-up. Interestingly, LDC had a greater impact on membrane phospholipid turnover, as suggested by higher phosphatidylcholine to phosphocholine conversion. Moreover, LDC elicited an increase in triglycerides, whereas cholesteryl esters accumulated in ATC-exposed cells, suggesting a different composition and handling of lipid droplets.

Marine Neurotoxins' Effects on Environmental and Human Health: An OMICS Overview

Harmful algal blooms (HAB), and the consequent release of toxic metabolites, can be responsible for seafood poisoning outbreaks. Marine wildlife can accumulate these toxins throughout the food chain, which presents a threat to consumers’ health. Some of these toxins, such as saxitoxin (STX), domoic acid (DA), ciguatoxin (CTX), brevetoxin (BTX), tetrodotoxin (TTX), and β-N-methylamino-L-alanine (BMAA), cause severe neurological symptoms in humans. Considerable information is missing, however, notably the consequences of toxin exposures on changes in gene expression, protein profile, and metabolic pathways. This information could lead to understanding the consequence of marine neurotoxin exposure in aquatic organisms and humans. Nevertheless, recent contributions to the knowledge of neurotoxins arise from OMICS-based research, such as genomics, transcriptomics, proteomics, and metabolomics. This review presents a comprehensive overview of the most recent research and of the available solutions to explore OMICS datasets in order to identify new features in terms of ecotoxicology, food safety, and human health. In addition, future perspectives in OMICS studies are discussed.

Cysteine biosynthesis contributes to β-methylamino-l-alanine tolerance in Escherichia coli

In contrast to mammalian cells, bacteria such as Escherichia coli have been shown to display tolerance towards the neurotoxin β-methylamino-l-alanine (BMAA) suggesting that these prokaryotes possess a way to metabolise BMAA or its products, resulting in their export, degradation, or detoxification. Single gene deletion mutants of E. coli K-12 with inactivated amino acid biosynthesis pathways were treated with 500 μg/ml BMAA and the resulting growth was monitored. Wild type E. coli and most of the gene deletion mutants displayed unaltered growth in the presence of BMAA over 12 h. Conversely, deletion of genes in the cysteine biosynthesis pathway, cysE, cysK or cysM resulted in a BMAA dose-dependent growth delay in minimal medium. Through further studies of the ΔcysE strain, we observed increased susceptibility to oxidative stress from H2O2 in minimal medium, and disruptions in glutathione levels and oxidation state. The cysteine biosynthesis pathway is therefore linked to the tolerance of BMAA and oxidative stress in E. coli, which potentially represents a mechanism of BMAA detoxification.

Effects of dietary inclusion of yerba mate (Ilex paraguariensis) extract on lamb muscle metabolomics and physicochemical properties in meat

This study aimed to evaluate the effect of dietary yerba mate (Ilex paraguariensis) extract (YME) on muscle metabolomics and physicochemical properties of lamb meat. Thirty-six uncastrated male lambs (90 d old) were fed experimental diets, which treatments consisted of 0%, 1%, 2%, and 4% inclusion of YME. Animals were fed for 50 d before slaughter. Muscle and meat samples were collected for metabolomics and meat quality analysis, respectively. The experiment was carried out in a randomized block design and analyzed using orthogonal contrasts. There was a quadratic effect of YME inclusion in tenderness (P < 0.05) and a positive linear effect on meat lightness (P < 0.05). No qualitative changes (P > 0.05) on individual metabolites were observed; however, changes in the quantitative metabolic profile were observed, showing that animals fed 1% and 2% of YME have a greater concentration of desirable endogenous muscle antioxidants, with direct impact on metabolic pathways related to beta-alanine metabolism and glutathione metabolism. Therefore, YME dietary supplementation up to 2% of the diet to lambs had little to no effects on the majority of meat quality traits evaluated; moreover, 4% of YME inclusion negatively affected feed intake and meat quality traits.

Cyanobacteria, Cyanotoxins, and Neurodegenerative Diseases: Dangerous Liaisons

The prevalence of neurodegenerative disease (ND) is increasing, partly owing to extensions in lifespan, with a larger percentage of members living to an older age, but the ND aetiology and pathogenesis are not fully understood, and effective treatments are still lacking. Neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis are generally thought to progress as a consequence of genetic susceptibility and environmental influences. Up to now, several environmental triggers have been associated with NDs, and recent studies suggest that some cyanotoxins, produced by cyanobacteria and acting through a variety of molecular mechanisms, are highly neurotoxic, although their roles in neuropathy and particularly in NDs are still controversial. In this review, we summarize the most relevant and recent evidence that points at cyanotoxins as environmental triggers in NDs development.

Effects of Bisphenol A and Bisphenol S Exposure at Low Doses on the Metabolome of Adolescent Male Sprague-Dawley Rats

Toxic effects induced upon exposure to low-dose bisphenol A (BPA) or bisphenol S (BPS) remains controversial. In this study, metabolomics was used to examine the metabolomic perturbation arising from 28 days of exposure to BPA or BPS at 50 μg/kg bw/day in Sprague-Dawley (SD) rats. Endogenous metabolite profiling revealed a clear discrimination of metabolome in the rat plasma among BPA-treatment, BPS-treatment, and control groups. BPA exposure induced the up-regulation of 19 metabolites and down-regulation of 32 metabolites in plasma of SD rats, compared with the control. BPS exposure induced the up-regulation of 15 metabolites and the down-regulation of 33 metabolites in the plasma of SD rats, compared with the control. Joint pathway analysis suggested marked perturbations in the citrate cycle, butanoate metabolism, and alanine, aspartate, and glutamate metabolism for BPA-exposed rats as well as glycerophospholipid metabolism for BPS-exposed rats. These findings provide novel insights into associations between the metabolomic perturbation and phenotypic changes arising from BPA and BPS exposure.

Is Exposure to BMAA a Risk Factor for Neurodegenerative Diseases? A Response to a Critical Review of the BMAA Hypothesis

In a literature survey, Chernoff et al. (2017) dismissed the hypothesis that chronic exposure to β-N-methylamino-L-alanine (BMAA) may be a risk factor for progressive neurodegenerative disease. They question the growing scientific literature that suggests the following: (1) BMAA exposure causes ALS/PDC among the indigenous Chamorro people of Guam; (2) Guamanian ALS/PDC shares clinical and neuropathological features with Alzheimer's disease, Parkinson's disease, and ALS; (3) one possible mechanism for protein misfolds is misincorporation of BMAA into proteins as a substitute for L-serine; and (4) chronic exposure to BMAA through diet or environmental exposures to cyanobacterial blooms can cause neurodegenerative disease. We here identify multiple errors in their critique including the following: (1) their review selectively cites the published literature; (2) the authors reported favorably on HILIC methods of BMAA detection while the literature shows significant matrix effects and peak coelution in HILIC that may prevent detection and quantification of BMAA in cyanobacteria; (3) the authors build alternative arguments to the BMAA hypothesis, rather than explain the published literature which, to date, has been unable to refute the BMAA hypothesis; and (4) the authors erroneously attribute methods to incorrect studies, indicative of a failure to carefully consider all relevant publications. The lack of attention to BMAA research begins with the review's title which incorrectly refers to BMAA as a "non-essential" amino acid. Research regarding chronic exposure to BMAA as a cause of human neurodegenerative diseases is emerging and requires additional resources, validation, and research. Here, we propose strategies for improvement in the execution and reporting of analytical methods and the need for additional and well-executed inter-lab comparisons for BMAA quantitation. We emphasize the need for optimization and validation of analytical methods to ensure that they are fit-for-purpose. Although there remain gaps in the literature, an increasingly large body of data from multiple independent labs using orthogonal methods provides increasing evidence that chronic exposure to BMAA may be a risk factor for neurological illness.

Altered metabolic profiles and biomarkers associated with astragaloside IV-mediated protection against cisplatin-induced acute kidney injury in rats: An HPLC-TOF/MS-based untargeted metabolomics study

Cisplatin (CDDP)-induced acute kidney injury (AKI) limits the therapeutic use of CDDP, which urgently needs to be addressed. Our previous study demonstrated that astragaloside IV (AS IV), an active compound of the traditional Chinese herb Astragalus membranaceus, alleviated CDDP-induced AKI. To explore the mechanism, we performed a metabolomics study to explore the altered metabolic pathways and screen for sensitive biomarkers. Twenty-four rats were randomly divided into three groups, which were treated with vehicle solutions (Control), intraperitoneally injected CDDP, and intraperitoneally injected CDDP plus oral AS IV, respectively. Metabolic profiles of serum, urine, and kidney samples were analyzed by high-performance liquid chromatography-time of flight mass spectrometry. There were 38 key metabolites in the urine samples, 20 in the serum samples, and 16 in the kidney samples that were significantly altered due to AS IV-mediated protection against CDDP-induced AKI relative to CDDP-only treatment. CDDP + AS IV co-treatment significantly altered two pathways in the blood (biosynthesis of unsaturated fatty acids and alanine, aspartate, and glutamate metabolism), five pathways in the urine (phenylalanine metabolism; phenylalanine, tyrosine, and tryptophan biosynthesis; arginine biosynthesis; arginine and proline metabolism; and histidine metabolism), and five pathways in the kidneys (glutathione metabolism; alanine, aspartate, and glutamate metabolism; glyoxylate and dicarboxylate metabolism; arginine and proline metabolism; and D-glutamine and D-glutamate metabolism). The metabolic pathways were mainly associated with improvements in inflammatory responses, oxidative stress, and energy metabolism. Adrenic acid in serum and L-histidine and L-methionine in urine were identified as sensitive biomarkers. This study provides new insights to understand the mechanism of AS IV-mediated protection against CDDP-induced AKI and has identified three candidate biomarkers to evaluate preventative treatment and assess therapeutic effectiveness.

Amino Acids Regulate Cisplatin Insensitivity in Neuroblastoma

Simple Summary

Neuroblastomas mostly show poor response to the Cisplatin therapy. Amino acids serve as building blocks for proteins, which are acquired either through diet or protein breakdown. Our study reveals high amino acid pools and dependence of Cisplatin-tolerant neuroblastomas cells on amino acids for their survival, especially, in drug treated conditions. Our study also demonstrates that response of neuroblastomas to Cisplatin can be improved by decreasing cellular amino acid levels either by reducing amino acid supplements or by applying autophagy inhibitor, Hydroxychloroquine. Thus, our findings establish that neuroblastomas can be sensitized to Cisplatin by targeting amino acid metabolism.

Abstract

Neuroblastoma are pediatric, extracranial malignancies showing alarming survival prognosis outcomes due to their resilience to current aggressive treatment regimens, including chemotherapies with cisplatin (CDDP) provided in the first line of therapy regimens. Metabolic deregulation supports tumor cell survival in drug-treated conditions. However, metabolic pathways underlying cisplatin-resistance are least studied in neuroblastoma. Our metabolomics analysis revealed that cisplatin-insensitive cells alter their metabolism; especially, the metabolism of amino acids was upregulated in cisplatin-insensitive cells compared to the cisplatin-sensitive neuroblastoma cell line. A significant increase in amino acid levels in cisplatin-insensitive cells led us to hypothesize that the mechanisms upregulating intracellular amino acid pools facilitate insensitivity in neuroblastoma. We hereby report that amino acid depletion reduces cell survival and cisplatin-insensitivity in neuroblastoma cells. Since cells regulate their amino acids levels through processes, such as autophagy, we evaluated the effects of hydroxychloroquine (HCQ), a terminal autophagy inhibitor, on the survival and amino acid metabolism of cisplatin-insensitive neuroblastoma cells. Our results demonstrate that combining HCQ with CDDP abrogated the amino acid metabolism in cisplatin-insensitive cells and sensitized neuroblastoma cells to sub-lethal doses of cisplatin. Our results suggest that targeting of amino acid replenishing mechanisms could be considered as a potential approach in developing combination therapies for treating neuroblastomas.

Proteomic Insights into Starvation of Nitrogen-Replete Cells of Nostoc sp. PCC 7120 under β-N-Methylamino-L-Alanine (BMAA) Treatment

All cyanobacteria produce a neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA). However, the biological function of BMAA in the regulation of cyanobacteria metabolism still remains undetermined. It is known that BMAA suppresses the formation of heterocysts in diazotrophic cyanobacteria under nitrogen starvation conditions, and BMAA induces the formation of heterocyst-like cells under nitrogen excess conditions, by causing the expression of heterocyst-specific genes that are usually “silent” under nitrogen-replete conditions, as if these bacteria receive a nitrogen deficiency intracellular molecular signal. In order to find out the molecular mechanisms underlying this unexpected BMAA effect, we studied the proteome of cyanobacterium Nostoc sp. PCC 7120 grown under BMAA treatment in nitrogen-replete medium. Experiments were performed in two experimental settings: (1) in control samples consisted of cells grown without the BMAA treatment and (2) the treated samples consisted of cells grown with addition of an aqueous solution of BMAA (20 µM). In total, 1567 different proteins of Nostoc sp. PCC 7120 were identified by LC-MS/MS spectrometry. Among them, 80 proteins belonging to different functional categories were chosen for further functional analysis and interpretation of obtained proteomic data. Here, we provide the evidence that a pleiotropic regulatory effect of BMAA on the proteome of cyanobacterium was largely different under conditions of nitrogen-excess compared to its effect under nitrogen starvation conditions (that was studied in our previous work). The most significant difference in proteome expression between the BMAA-treated and untreated samples under different growth conditions was detected in key regulatory protein PII (GlnB). BMAA downregulates protein PII in nitrogen-starved cells and upregulates this protein in nitrogen-replete conditions. PII protein is a key signal transduction protein and the change in its regulation leads to the change of many other regulatory proteins, including different transcriptional factors, enzymes and transporters. Complex changes in key metabolic and regulatory proteins (RbcL, RbcS, Rca, CmpA, GltS, NodM, thioredoxin 1, RpbD, ClpP, MinD, RecA, etc.), detected in this experimental study, could be a reason for the appearance of the “starvation” state in nitrogen-replete conditions in the presence of BMAA. In addition, 15 proteins identified in this study are encoded by genes, which are under the control of NtcA—a global transcriptional regulator—one of the main protein partners and transcriptional regulators of PII protein. Thereby, this proteomic study gives a possible explanation of cyanobacterium starvation under nitrogen-replete conditions and BMAA treatment. It allows to take a closer look at the regulation of cyanobacteria metabolism affected by this cyanotoxin.

A Novel Approach Based on Metabolomics Coupled With Intestinal Flora Analysis and Network Pharmacology to Explain the Mechanisms of Action of Bekhogainsam Decoction in the Improvement of Symptoms of Streptozotocin-Induced Diabetic Nephropathy in Mice

Bekhogainsam decoction (BHID), a representative prescription for the treatment of diabetes mellitus (DM) and diabetic complications in both traditional Korean and Chinese medicine, was examined for its ability to ameliorate diabetic nephropathy (DN), and its mechanism of action was evaluated by metabolomics, gut microbiota, and network pharmacology. In this study, male specific pathogen-free C57BL/6 mice were intraperitoneally injected with streptozotocin (STZ, 100 mg/kg) once per day for 3 days consecutively, and were then orally administered BHID at 100 and 500 mg/kg, and metformin at 250 mg/kg once per day for 4 weeks. Our results showed that the administration of BHID to mice with STZ-induced DN prevented physiological and serological changes, structural damage, and kidney dysfunction. Based on a metabolomics test with serum, the profoundly altered metabolites in the BHID treatment group were identified. Thirty-six BHID-related proteins and four signaling pathways, including valine, leucine, and isoleucine biosynthesis, nicotinate and nicotinamide metabolism, tryptophan metabolism, and alanine, aspartate, and glutamate metabolism pathways, were explored. Principal coordinates analysis (PCoA) of the gut microbiota revealed that BHID treatment significantly affected the flora composition. In addition, the network pharmacology analysis revealed that BHID acted through phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) and MAPK-related protein targets. Our findings on the anti-DN effects of BHID and its mechanism of action, from the perspective of systems biology, have provided scientific evidence to support the clinical treatment of patients with diabetes, and implied that BHID has the potential to prevent the progression of DN.

The First Proteomics Study of Nostoc sp. PCC 7120 Exposed to Cyanotoxin BMAA under Nitrogen Starvation

The oldest prokaryotic photoautotrophic organisms, cyanobacteria, produce many different metabolites. Among them is the water-soluble neurotoxic non-protein amino acid beta-N-methylamino-L-alanine (BMAA), whose biological functions in cyanobacterial metabolism are of fundamental scientific and practical interest. An early BMAA inhibitory effect on nitrogen fixation and heterocyst differentiation was shown in strains of diazotrophic cyanobacteria Nostoc sp. PCC 7120, Nostocpunctiforme PCC 73102 (ATCC 29133), and Nostoc sp. strain 8963 under conditions of nitrogen starvation. Herein, we present a comprehensive proteomic study of Nostoc (also called Anabaena) sp. PCC 7120 in the heterocyst formation stage affecting by BMAA treatment under nitrogen starvation conditions. BMAA disturbs proteins involved in nitrogen and carbon metabolic pathways, which are tightly co-regulated in cyanobacteria cells. The presented evidence shows that exogenous BMAA affects a key nitrogen regulatory protein, PII (GlnB), and some of its protein partners, as well as glutamyl-tRNA synthetase gltX and other proteins that are involved in protein synthesis, heterocyst differentiation, and nitrogen metabolism. By taking into account the important regulatory role of PII, it becomes clear that BMAA has a severe negative impact on the carbon and nitrogen metabolism of starving Nostoc sp. PCC 7120 cells. BMAA disturbs carbon fixation and the carbon dioxide concentrating mechanism, photosynthesis, and amino acid metabolism. Stress response proteins and DNA repair enzymes are upregulated in the presence of BMAA, clearly indicating severe intracellular stress. This is the first proteomic study of the effects of BMAA on diazotrophic starving cyanobacteria cells, allowing a deeper insight into the regulation of the intracellular metabolism of cyanobacteria by this non-protein amino acid.

Inhibitory effects of neurotoxin β-N-methylamino-L-alanine on fertilization and early development of the sea urchin Lytechinus pictus

Neurotoxin β-N-methylamino-L-alanine (BMAA) has been widely detected in diverse aquatic organisms and hypothesized as an environmental risk to neurodegenerative diseases in humans. However, the knowledge of its toxicity to marine organisms requires attention. In the present study, embryos and sperm of the sea urchin, Lytechinus pictus, were used to assess the toxicity of BMAA. Effects of BMAA on fertilization and development of sea urchin embryos were measured, and its impacts on efflux transport of sea urchin blastula were also assayed. Results demonstrated that the fertilization and development of embryos were significantly inhibited by high concentrations of BMAA above 300 μg L^-1. The EC₅₀ values indicated by active swimming larvae and total larvae numbers at 96 HPF (hours post fertilization) were 165 μg L^-1 (1.4 μmol L^-1) and 329 μg L^-1 (2.8 μmol L^-1), respectively. Additionally, sperm exposed to BMAA for 10 min significantly reduced the fertilization ratio of sea urchin eggs. However, the ABC transport activity on the cytomembrane of sea urchin blastula was not inhibited by the presence of BMAA at 50 μg L^-1, even up to 500 μg L^-1. Abnormal division and developmental malformations occurred at different developmental stages for sea urchin embryos exposed to BMAA at 500 μg L^-1. The inhibitory effects of BMAA on sea urchin embryos were reported at the first time in this study, for which the toxicological mechanisms will be explored in future studies.

Metabolomics analysis reveals perturbations of cerebrocortical metabolic pathways in the Pahenu2 mouse model of phenylketonuria

AIMS

Phenylketonuria (PKU), which is caused by mutations in the phenylalanine hydroxylase (PAH) gene, is one of the most common inherited diseases of amino acid metabolism. Phenylketonuria is characterized by an abnormal accumulation of phenylalanine and its metabolites in body fluids and brain tissues, subsequently leading to severe brain dysfunction. Various pathophysiological and molecular mechanisms underlying brain dysfunction in PKU have been described. However, the metabolic changes and their impacts on the function of cerebral cortices of patients with PKU remain largely unknown.

METHODS

We measured the levels of small molecule metabolites in the cerebrocortical tissues of PKU mice and wild-type control mice using liquid chromatography-mass spectrometry (LC-MS)-based metabolome analysis. Differential metabolites were further subjected to metabolic pathway and enrichment analysis.

RESULTS

Metabolome analysis revealed 35 compounds among 143 detected metabolites were significantly changed in PKU mice as compared to those in their wild-type littermates. Metabolic pathway and enrichment analysis of these differential metabolites showed that multiple metabolic pathways, including phenylalanine, tyrosine, and tryptophan biosynthesis; valine, leucine, and isoleucine biosynthesis; alanine, aspartate, and glutamate metabolism; purine metabolism; arginine and proline metabolism and methionine metabolism, were impacted in the cerebral cortices of PKU mice.

CONCLUSIONS

The data revealed that multiple metabolic pathways in cerebral cortices of PKU mice were disturbed, suggesting that the disturbances of the metabolic pathways might contribute to neurological or neurodevelopmental dysfunction in PKU, which could thus provide new insights into brain pathogenic mechanisms in PKU as well as mechanistic insights for better understanding the complexity of the metabolic mechanisms of the brain dysfunction in PKU.

Quantitative Comparative Proteomics Reveal Biomarkers for Dengue Disease Severity

Dengue fever (DF) could develop into dengue haemorrhagic fever (DHF) with increased mortality rate. Since the clinical characteristics and pathogen are same in DF and DHF. It's important to identify different molecular biomarkers to predict DHF patients from DF. We conducted a clinical plasma proteomics study using quantification (TMT)-based quantitative proteomics methodology to found the differential expressed protein in DF patients before they developed into DHF. In total 441 proteins were identified up or down regulated. There proteins are enriched in diverse biological processes such as proteasome pathway, Alanine, aspartate, and glutamate metabolism and arginine biosynthesis. Several proteins such as PLAT, LAMB2, and F9 were upregulated in only DF patients which developed into DHF cases, not in DF, compared with healthy-control. In another way, FGL1, MFAP4, GLUL, and VCAM1 were upregulated in both DHF and DF cases compare with healthy-control. RT-PCR and ELISA were used to validate these upregulated gene expression and protein level in 54 individuals. Results displayed the same pattern as proteomics analysis. All including PLAT, LAMB2, F9, VCAM1, FGL1, MFAP4, and GLUL could be considered as potential markers of predicting DHF since the levels of these proteins vary between DF and DHF. These new founding identified potential molecular biomarkers for future development in precision prediction of DHF in DF patients.

Rearing pattern alters porcine myofiber type, fat deposition, associated microbial communities and functional capacity

BACKGROUND

The Chinese believe that the meat of pigs reared in the past with free range tastes better than that of the pigs reared indoor on a large scale today. Gastrointestinal microflora is closely associated with the main factor of meat flavour, including fibre characteristics and lipid metabolism. Our method in this study involved different raising patterns within the semi free-grazing farm (FF) or indoor feeding farm (DF), the measurement of fat deposition and myofiber type by paraffin section and reverse transcription polymerase chain reaction and the identification of microbiome and functional capacities associated with meat quality through metagenomic sequencing.

RESULTS

Results showed that the fat area in muscle and adipose tissue and the myofiber density significantly increased in the pigs of the FF group. The relative abundance of bacteria associated with lipid metabolism, such as g_Oscillibacter, in the feces of the FF group was higher than that in DF group, and the relative abundance of some bacteria with probiotic function, including g_Lactobacillus and g_Clostridium, was lower than that in DF group. The abundance of g_Clostridium was significantly positively correlated with the intramuscular fat area, whereas health-related bacteria, such as g_Butyricicoccus, g_Eubacterium, g_Phascolarctobacterium and g_Oribacterium, was significantly negatively correlated with abdominal fat area, myofiber density and adipose triglyceride lipase (ATGL) mRNA expression. KEGG analysis showed that pigs raised in semi free-grazing farm can activate the pathway of inosine monophosphate (IMP) biosynthesis, glycolysis/gluconeogenesis and alanine, aspartate and glutamate metabolism.

CONCLUSIONS

Free range feeding improves meat quality by changing the fibre type, myofiber density and metabolic pathways related to flavour amino acids, IMP or glycolysis/gluconeogenesis in muscle. However, prolonged feeding cycle increases fat deposition and associated microbial communities.

The Cyanotoxin BMAA Induces Heterocyst Specific Gene Expression in Anabaena sp. PCC 7120 under Repressive Conditions

Cyanobacteria synthesize neurotoxic β-N-methylamino-l-alanine (BMAA). The roles of this non-protein amino acid in cyanobacterial cells are insufficiently studied. During diazotrophic growth, filamentous cyanobacteria form single differentiated cells, called heterocysts, which are separated by approximately 12–15 vegetative cells. When combined nitrogen is available, heterocyst formation is blocked and cyanobacterial filaments contain only vegetative cells. In the present study, we discovered that exogenous BMAA induces the process of heterocyst formation in filamentous cyanobacteria under nitrogen-replete conditions that normally repress cell differentiation. BMAA treated cyanobacteria form heterocyst-like dark non-fluorescent non-functional cells. It was found that glutamate eliminates the BMAA mediated derepression. Quantitative polymerase chain reaction (qPCR) permitted to detect the BMAA impact on the transcriptional activity of several genes that are implicated in nitrogen assimilation and heterocyst formation in Anabaena sp. PCC 7120. We demonstrated that the expression of several essential genes increases in the BMAA presence under repressive conditions.

Neurotoxic Agent-Induced Injury in Neurodegenerative Disease Model: Focus on Involvement of Glutamate Receptors

Glutamate receptors play a crucial role in the central nervous system and are implicated in different brain disorders. They play a significant role in the pathogenesis of neurodegenerative diseases (NDDs) such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Although many studies on NDDs have been conducted, their exact pathophysiological characteristics are still not fully understood. In in vivo and in vitro models of neurotoxic-induced NDDs, neurotoxic agents are used to induce several neuronal injuries for the purpose of correlating them with the pathological characteristics of NDDs. Moreover, therapeutic drugs might be discovered based on the studies employing these models. In NDD models, different neurotoxic agents, namely, kainic acid, domoic acid, glutamate, β-N-Methylamino-L-alanine, amyloid beta, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, 1-methyl-4-phenylpyridinium, rotenone, 3-Nitropropionic acid and methamphetamine can potently impair both ionotropic and metabotropic glutamate receptors, leading to the progression of toxicity. Many other neurotoxic agents mainly affect the functions of ionotropic glutamate receptors. We discuss particular neurotoxic agents that can act upon glutamate receptors so as to effectively mimic NDDs. The correlation of neurotoxic agent-induced disease characteristics with glutamate receptors would aid the discovery and development of therapeutic drugs for NDDs.

Stress effects of cyanotoxin β-methylamino-L-alanine (BMAA) on cyanobacterial heterocyst formation and functionality

Various species of cyanobacteria, diatoms and dinoflagellates are capable of synthesizing the non-proteinogenic neurotoxic amino acid β-N-methylamino-L-alanine (BMAA), which is known to be a causative agent of human neurodegeneration. Similar to most cyanotoxins, the biological and ecological functions of BMAA in cyanobacteria are unknown. In this study, we show for the first time that BMAA, in micromolar amounts, inhibits the formation of heterocysts (specialized nitrogen-fixing cells) in heterocystous, diazotrophic cyanobacteria [Anabaena sp. PCC 7120, Nostoc punctiforme PCC 73102 (ATCC 29133), Nostoc sp. strain 8963] under conditions of nitrogen starvation. The inhibitory effect of BMAA is abolished by the addition of glutamate. To understand the genetic reason for the observed phenomenon, we used qPCR to study the expression of key genes involved in cell differentiation and nitrogen metabolism in the model cyanobacterium Anabaena sp. PCC 7120. We observed that in the presence of BMAA, Anabaena sp. PCC 7120 does not express two essential genes associated with heterocyst differentiation, namely, hetR and hepA. We also found that addition of BMAA to cyanobacterial cultures with mature heterocysts inhibits nifH gene expression and nitrogenase activity.

Cisplatin-induced metabolome changes in serum: an experimental approach to identify markers for ototoxicity

BACKGROUND

Ototoxicity from treatment with the anticancer drug cisplatin remains a clinical problem. A wide range of intracellular targets of cisplatin has been found in vivo.

AIM

To investigate cisplatin-induced change of the serum metabolite profile and its association with ototoxicity.

MATERIAL AND METHODS

Guinea pigs (n = 14) were treated with cisplatin (8 mg/kg b.w., i.v.) 30 min after administration of the otoprotector candidate sodium thiosulfate (group STS; n = 7) or sodium chloride (group NaCl; n = 7). Ototoxicity was evaluated by ABR (3-30 kHz) before and 4 d after drug treatment, and by assessment of hair cell loss. A blood sample was drawn before and 4 d after drug treatment and the polar metabolome in serum was analyzed using LC-MS.

RESULTS

Cisplatin-treatment caused significant threshold elevations and outer hair cell (OHC) loss in both groups. The ototoxicity was generally lower in group STS, but a significant difference was reached only at 30 kHz (p = .007). Cisplatin treatment altered the metabolite profile significantly and similarly in both groups. A significant inverse correlation was found between L-acetylcarnitine, N-acetylneuraminic acid, ceramide, and cysteinylserine and high frequency hearing loss in group NaCl. The implication of these correlations should be explored in targeted studies.