Possibility analysis of thyroid imaging parameters for dose adjustment in 131I treatment of hyperthyroidism.

BACKGROUND: To determine the thyroid uptake rate by correcting the background and analyze its clinical significance. METHODS: The study included 161 patients with hyperthyroidism. The thyroid uptake rate was calculated by drawing a 100 pixels ROI (region of interest) background, above and below the thyroid and correcting the thyroid ROI for background counting. At the same time, the clinical baseline characteristic parameters such as age and thyroid volume etc. of patients with hyperthyroidism were collected. The consistency of 99mTcO4uptake rate before treatment and 131I-uptake rate after treatment, and the correlation between uptake rate of thyroid and baseline characteristic parameters were also analyzed. RESULTS: The uptake rate of 99mTcO4 was found positively correlated with 3 h-radioactive iodine uptake (RAIU), 24 h-RAIU, 3 h/24 h conversion rate, thyroid volume, 131I activity free triiodothyronine (FT3) and free thyroxine (FT4), and showed negative correlation with age, effective half-life (P<0.05). The uptake rate of 131I was found positively correlated with 3 h-RAIU, 24 h-RAIU, 3 h/24 h conversion rate, thyroid volume, 131I activity, FT3, FT4 (P<0.05). In patients with positive thyrotrophin receptor antibody (TRAb), a significant positive correlation between uptake rate of 99mTcO4 and 131I (P<0.05) was observed. There was a high consistency between pretreatment uptake rate of 99mTcO4 and post-treatment uptake rate of 131I (P=0.009; W=0.7). CONCLUSIONS: The corrected thyroid uptake rate is remarkably correlated with clinical characteristic parameters of patients, which can be used to comprehensively evaluate the comprehensive condition of patients with hyperthyroidism.

Ecological risk assessment for xylenes and propylbenzenes in aquatic environment using a species sensitivity distribution approach.

Xylenes and propylbenzenes (PBZs) are volatile aromatic hydrocarbons with high aquatic toxicity. Xylenes can be present in three isomers: o-xylene (OX), m-xylene (MX), and p-xylene (PX), while PBZs include two isomers: n-propylbenzene (n-PBZ) and isopropylbenzene (i-PBZ). Their accidental spills and improper discharges from petrochemical industries can cause severe contamination in water bodies posing potential ecological risks. In this study, the published acute toxicity data of these chemicals for aquatic species were collected to calculate hazardous concentrations protecting 95% species (HC5) using a species sensitivity distribution (SSD) approach. The acute HC5 values for OX, MX, PX, n-PBZ, and i-PBZ were estimated to be 1.73, 3.05, 1.23, 1.22, and 1.46 mg/L, respectively. The risk quotient (RQ) values calculated based on HC5 indicated their high risk (RQ: 1.23 ∼ 21.89) in groundwater, but low risk (RQ < 0.1) in natural seawater, river water, and lake water. When xylenes or PBZs leaked into the sea, they were expected to pose a high risk (RQ > 1) at the start and then a low risk (RQ < 0.1) after 10 days due to natural attenuation. These results may help to derive more reliable protection thresholds for xylenes and PBZs in aquatic environment and provide a basis for evaluating their ecological risks.

Cytotoxicity and intestinal permeability of phycotoxins assessed by the human Caco-2 cell model.

Phycotoxins are a class of multiple natural metabolites produced by microalgae in marine and freshwater ecosystems that bioaccumulate in food webs, particularly in shellfish, having a great impact on human health. Phycotoxins are mainly leached and absorbed in the small intestine when human consumers accidentally ingest toxic aquatic products contaminated by them. To assess the intestinal uptake and damage of phycotoxins, a typical in vitro model was developed and widely applied using the human colorectal adenocarcinoma Caco-2 cell line. In this review, the application cases were summarized for multiple phycotoxins, including microcystins (MCs), cylindrospermopsins (CYNs), domoic acids (DAs), saxitoxins (STXs), palytoxins (PLTXs), okadaic acids (OAs), pectenotoxins (PTXs) and azaspiracids (AZAs). The results of the previous studies showed that each group of phycotoxins presented different cytotoxicity and mechanisms to Caco-2 cells, and significant discrepancies in the transport of phycotoxin across the Caco-2 cell monolayers. Therefore, this review describes the evaluation assays of the Caco-2 cell monolayer model, illustrates the principles of several primary cytotoxicity evaluation assays, and summarizes the cytotoxicity of each group of phycotoxins to Caco-2 cells line and their cellular transport, and finally proposes the development of multicellular intestinal models for future comprehensive studies on the toxicity and absorption of phycotoxins in the intestine. It will improve the understanding of Caco-2 cell monolayer models in the toxicology studies on phycotoxins and the potentially detrimental effects of microalgal toxins on the human intestine.

Reaction mechanism and detecting properties of a novel molecularly imprinted electrochemical sensor for microcystin based on three-dimensional AuNPs@MWCNTs/GQDs.

Microcystins with leucine arginine (MC-LR) is a virulent hepatotoxin, which is commonly present in polluted water with its demethylated derivatives [Dha7] MC-LR. This study reported a low-cost molecularly imprinted polymer network-based electrochemical sensor for detecting MC-LR. The sensor was based on a three-dimensional conductive network composed of multi-walled carbon nanotubes (MWCNTs), graphene quantum dots (GQDs), and gold nanoparticles (AuNPs). The molecularly imprinted polymer was engineered by quantum chemical computation utilizing p-aminothiophenol (p-ATP) and methacrylic acid (MAA) as dual functional monomers and L-arginine as a segment template. The electrochemical reaction mechanism of MC-LR on the sensor was studied for the first time, which is an irreversible electrochemical oxidation reaction involving an electron and two protons, and is controlled by a mixed adsorption-diffusion mechanism. The sensor exhibited a great detection response to MC-LR in the linear range of 0.08-2 µg/L, and the limit of detection (LOD) is 0.0027 µg/L (S/N = 3). In addition, the recoveries of the total amount of MC-LR and [Dha7] MC-LR in the actual sample by the obtained sensor were in the range from 91.4 to 116.7%, which indicated its great potential for environmental detection.

Preparation and Characterization of Magnetic Metal-Organic Frameworks Functionalized by Ionic Liquid as Supports for Immobilization of Pancreatic Lipase.

Enzymes are difficult to recycle, which limits their large-scale industrial applications. In this work, an ionic liquid-modified magnetic metal-organic framework composite, IL-Fe3O4@UiO-66-NH2, was prepared and used as a support for enzyme immobilization. The properties of the support were characterized with X-ray powder diffraction (XRD), Fourier-transform infrared (FTIR) spectra, transmission electron microscopy (TEM), scanning electronic microscopy (SEM), and so on. The catalytic performance of the immobilized enzyme was also investigated in the hydrolysis reaction of glyceryl triacetate. Compared with soluble porcine pancreatic lipase (PPL), immobilized lipase (PPL-IL-Fe3O4@UiO-66-NH2) had greater catalytic activity under reaction conditions. It also showed better thermal stability and anti-denaturant properties. The specific activity of PPL-IL-Fe3O4@UiO-66-NH2 was 2.3 times higher than that of soluble PPL. After 10 repeated catalytic cycles, the residual activity of PPL-IL-Fe3O4@UiO-66-NH2 reached 74.4%, which was higher than that of PPL-Fe3O4@UiO-66-NH2 (62.3%). In addition, kinetic parameter tests revealed that PPL-IL-Fe3O4@UiO-66-NH2 had a stronger affinity to the substrate and, thus, exhibited higher catalytic efficiency. The results demonstrated that Fe3O4@UiO-66-NH2 modified by ionic liquids has great potential for immobilized enzymes.

Performance of different extraction methods for paralytic shellfish toxins and toxin stability in shellfish during storage.

Accurate analysis of paralytic shellfish toxins (PSTs) in shellfish is important to protect seafood safety and human health. In this study, the performance of different extraction protocols for PSTs from scallop tissues is compared and discussed, including regular extraction solvents hydrochloric acid (HCl) and acetic acid (AcOH) followed by heating and solid-phase extraction (SPE) purification, and a novel technique of matrix solid-phase dispersion (MSPD) without heating. The possible conversion of C1/2 and GTX2/3 standards after heating, and the stability of PSTs in wet scallop tissues stored at -20 °C for a 6-month period are also explored. Results showed that the MSPD technique could effectively mitigate matrix interference, but its recoveries of PSTs were significantly lower than those of the HCl and AcOH extraction methods followed by carbon SPE purification. The molar concentrations of M-toxins obtained by the MSPD method were generally lower than those analyzed by the HCl and AcOH extraction methods, which demonstrated a weak chemical conversion of C1/2 and GTX2/3 due to the heating process. Most of the PSTs were relatively stable in scallop tissues during 1-month storage at -20 °C, while the concentrations of PSTs in scallop tissues obviously changed after 6 months due to the degradation and transformation of PSTs during long-term storage at -20 °C. This work helps improve our understanding of the performance of different extraction methods and the stability of PSTs in scallop tissues stored at -20 °C.

Two New and Nontoxigenic Pseudo-nitzschia species (Bacillariophyceae) from Chinese Southeast Coastal Waters.

To explore the species diversity and toxin profile of Pseudo-nitzschia, monoclonal strains were established from Chinese southeast coastal waters. The morphology was examined under light and transmission electron microscopy. The internal transcribed spacer region of ribosomal DNA was sequenced for phylogenetic analyses, and the secondary structure of ITS2 was predicted and compared among allied taxa. A combination of morphological and molecular data showed the presence of two new species, Pseudo-nitzschia hainanensis sp. nov. and Pseudo-nitzschia taiwanensis sp. nov. Pseudo-nitzschia hainanensis was characterized by a dumpy-lanceolate valve with slightly blunt apices and a central nodule, as well as striae comprising two rows of poroids. Pseudo-nitzschia taiwanensis was characterized by a slender-lanceolate valve, and striae comprising one row of split poroids. The poroid structure mainly comprised two sectors. Both taxa constituted their own monophyletic lineage in the phylogenetic analyses inferred from ITS2 rDNA and were well differentiated from other Pseudo-nitzschia species. Morphologically, P. hainanensis and P. taiwanensis could be assigned to the Pseudo-nitzschia delicatissima and the Pseudo-nitzschia pseudodelicatissima complex, respectively. Particulate domoic acid was measured using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), but no detectable pDA was found. With the description of the two new species, the species diversity of genus Pseudo-nitzschia reaches 58 worldwide, among which 31 have been recorded from Chinese coastal waters.

Chlorine disinfectants promote microbial resistance in Pseudomonas sp.

The substantial use of disinfectants has increased antibiotic resistance, thereby mediating serious ecological safety issues worldwide. Accumulating studies have reported the role of chlorine disinfectants in promoting disinfectant resistance. The present study sought to investigate the role of chlorine disinfectants in developing multiple resistance in Pseudomonas sp. isolated from the river through antioxidant enzyme measurement, global transcriptional analyses, Gene Ontology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. The results demonstrated that 100 mg/L sodium hypochlorite could increase disinfectant resistance and antibiotic resistance. The SOS response (a conserved response to DNA damage) triggered by oxidative stress makes bacteria resistant to chlorine. An increase in antibiotic resistance could be attributed to a decreased membrane permeability, increased expression of MuxABC-OpmB efflux pump, beta-lactamase, and antioxidant enzymes. Additionally, KEGG enrichment analysis suggested that the differentially expressed genes were highly enriched in the metabolic pathways. In summary, the study results revealed the impact of chlorine disinfectants in promoting microbial disinfectant resistance and antibiotic resistance. This study will provide insight into disinfectant resistance mechanisms.

Disinfectant resistance in bacteria: Mechanisms, spread, and resolution strategies.

Disinfectants are widely acknowledged for removing microorganisms from the surface of the objects and transmission media. However, the emergence of disinfectant resistance has become a severe threat to the safety of life and health and the rational allocation of resources due to the reduced disinfectant effectiveness. The horizontal gene transfer (HGT) of disinfectant resistance genes has also expanded the resistant flora, making the situation worse. This review focused on the resistance mechanisms of disinfectant resistant bacteria on biofilms, cell membrane permeability, efflux pumps, degradable enzymes, and disinfectant targets. Efflux can be the fastest and most effective resistance mechanism for bacteria to respond to stress. The qac genes, located on some plasmids which can transmit resistance through conjugative transfer, are the most commonly reported in the study of disinfectant resistance genes. Whether the qac genes can be transferred through transformation or transduction is still unclear. Studying the factors affecting the resistance of bacteria to disinfectants can find breakthrough methods to more adequately deal with the problem of reduced disinfectant effectiveness. It has been confirmed that the interaction of probiotics and bacteria or the addition of 4-oxazolidinone can inhibit the formation of biofilms. Chemicals such as eugenol and indole derivatives can increase bacterial sensitivity by reducing the expression of efflux pumps. The role of these findings in anti-disinfectant resistance has proved invaluable.

Natural attenuation characteristics and comprehensive toxicity changes of C9 aromatics under simulated marine conditions.

Microcosmic experiments were performed under a simulated marine environment to investigate the natural attenuation of C9 aromatics using nine components (propylbenzene, isopropylbenzene, 2-ethyltoluene, 3-ethyltoluene, 4-ethyltoluene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, and indene). This research aims to assess the contribution of biodegradation and abiotic activity to total attenuation of C9 aromatics and ascertain the changes in the comprehensive toxicity of seawater in the natural environment. The process of natural attenuation indicates the agreement with pseudo-first-order kinetics for all nine components in microcosmic experiments. The half-lives of the nine main compounds in C9 aromatics ranged between 0.34 day and 0.44 day under optimal conditions. The experiments showed that the natural attenuation of nine aromatic hydrocarbons mainly occurred via abiotic processes. Seawater samples significantly inhibited the luminescence of P. phosphoreum (the luminescence inhibition ratio reached 100%) at the beginning of the experiment. In addition, the toxicity declined slowly and continued for 25 days. The attenuation kinetics and changes in toxicity could be applied to explore the natural attenuation of C9 aromatics in the marine environment.

Response of fatty acids and lipid metabolism enzymes during accumulation, depuration and esterification of diarrhetic shellfish toxins in mussels (Mytilus galloprovincialis).

Bivalve mollusks accumulate diarrhetic shellfish toxins (DSTs) from toxigenic microalgae, thus posing a threat to human health by acting as a vector of toxins to consumers. In bivalves, free forms of DSTs can be esterified with fatty acids at the C-7 site to form acyl esters (DTX3), presumably a detoxification mechanism for bivalves. However, the effects of esterification of DSTs on fatty acid metabolism in mollusks remain poorly understood. In this study, mussels (Mytilus galloprovincialis) were fed the DST-producing dinoflagellate Prorocentrum lima for 10 days followed by an additional 10-days depuration in filtered seawater to track the variation in quantity and composition of DST acyl esters and fatty acids. A variety of esters of okadaic acid (OA) and dinophysistoxin-1 (DTX1) were mainly formed in the digestive gland (DG), although trace amounts of esters also appeared in muscle tissue. A large relative amount of OA (60%-84%) and DTX1 (80%-92%) was esterified to DTX3 in the visceral mass (referred to as digestive gland, DG), and the major ester acyl chains were C16:0, C16:1, C18:0, C18:1, C20:1 and C20:2. The DG and muscle tissues showed pronounced differences in fatty acid content and composition during both feeding and depuration periods. In the DG, fatty acid content gradually decreased in parallel with increasing accumulation and esterification of DSTs. The decline in fatty acids was accelerated during depuration without food. This reduction in the content of important polyunsaturated fatty acids, especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), would lead to a reduction in the nutritional value of mussels. Enzymes involved in lipid metabolism, including acetyl-coenzyme A carboxylase (ACC), fatty acid synthase (FAS), lipoprotein lipase (LPL) and hepatic lipase (HL), were actively involved in the metabolism of fatty acids in the DG, whereas their activities were weak in muscle tissue during the feeding period. This study helps to improve the understanding of interactions between the esterification of DSTs and fatty acid dynamics in bivalve mollusks.

Application of activated carbon to accelerate detoxification of paralytic shellfish toxins from mussels Mytilus galloprovincialis and scallops Chlamys farreri.

Contamination of economic bivalves with paralytic shellfish toxins (PST) occurs frequently in many parts of the world, which potentially threatens consumer health and the marine aquaculture economy. It is the objective of this study to develop a suitable technology for accelerating detoxification of PST from shellfish using activated carbon (AC). The adsorption efficiency of PST by eight different AC materials and by different particle sizes of wood-based AC (WAC) were tested and compared. Then WAC particles (37-48µm) were fed to mussels Mytilus galloprovincialis and scallops Chlamys farreri previously contaminated with PST through feeding with dinoflagellate Alexandrium tamarense ATHK. Results showed that the maximum adsorption ratio (65%) of PST was obtained by WAC. No significant differences in adsorption ratios were found between different particle sizes of WAC. The toxicity of mussels decreased by 41% and 68% after detoxification with WAC for 1 d and 3 d, respectively. Meanwhile, the detoxification ratio of mussels was approximately 3 times higher than that of scallops. This study suggests that the WAC could be used to accelerate the detoxification of PST by shellfish.

New Typical Vector of Neurotoxin ß-N-Methylamino-l-Alanine (BMAA) in the Marine Benthic Ecosystem.

The neurotoxin ß-N-methylamino-l-alanine (BMAA) has been identified as an environmental factor triggering neurodegenerative diseases such as Amyotrophic Lateral Sclerosis (ALS) and Alzheimer's disease (AD). We investigated the possible vectors of BMAA and its isomers 2,4-diaminobutyric acid (DAB) and N-2(aminoethyl)glycine (AEG) in marine mollusks collected from the Chinese coast. Sixty-eight samples of marine mollusks were collected along the Chinese coast in 2016, and were analyzed by an HILIC-MS/MS (hydrophilic interaction liquid chromatography with tandem quadrupole mass spectrometer) method without derivatization. BMAA was detected in a total of five samples from three species: Neverita didyma, Solen strictus, and Mytilus coruscus. The top three concentrations of free-form BMAA (0.99~3.97 µg·g-1 wet weight) were detected in N. didyma. DAB was universally detected in most of the mollusk samples (53/68) with no species-specific or regional differences (0.051~2.65 µg·g-1 wet weight). No AEG was detected in any mollusk samples tested here. The results indicate that the gastropod N. didyma might be an important vector of the neurotoxin BMAA in the Chinese marine ecosystem. The neurotoxin DAB was universally present in marine bivalve and gastropod mollusks. Since N. didyma is consumed by humans, we suggest that the origin and risk of BMAA and DAB toxins in the marine ecosystem should be further investigated in the future.

Growth and toxin production of Azadinium poporum strains in batch cultures under different nutrient conditions.

Azaspiracid-2 (AZA2) is the dominant toxin produced by Azadinium poporum strains AZDY06 and AZFC22 isolated from the South China Sea. Biomass and AZA2-production were examined within batch cultures with variation in experimental concentrations of nitrate (0, 88, 882, and 2647µM) or phosphate (0, 3.6, 36, and 109µM), different nitrogen sources (nitrate and urea) and media (f/2-Si, L1-Si, and K-Si) in the present study. Growth of both strains positively responded to nitrate or phosphate nutrients, but the growth status was significantly repressed by the highest additional level of phosphate (109µM). Both AZDY06 and AZFC22 grew well with higher specific growth rates, but with shorter growth periods, within f/2-Si medium spiked with urea than that within media spiked with nitrate. L1-Si medium with relatively high concentrations of trace metals was relatively favorable to both strains of A. poporum tested here. No obvious change within the toxin profile occurred in all cultures of both strains under the various nutrient conditions, although trace amounts of some suspicious derivatives of AZA2 occurred in some cultures. AZA2 cell quotas within both strains significantly (p<0.05) increased at the stationary phase under lower additional phosphate (0 and 3.6µM). Significant differences were not found within AZA2 cell quotas in cultures with additional nitrate ranging from 0 to 2647µM. The highest AZA2 cell quota and maximum AZA2 quantity per culture volume occurred in batch culture at the stationary phase under phosphate concentrations at 3.6µM. Neither A. poporum strain exhibited significant changes in AZA2 cell quotas within f/2-Si media spiked with urea or nitrate as nitrogen sources. The AZA2 cell quota of strain AZDY06 also did not change remarkably within f/2-Si, L1-Si, and K-Si media, however the AZA2 cell quota of strain AZFC22 within L1-Si medium was significantly (p<0.05) higher than that within f/2-Si medium.

Ligustrazine attenuates neuropathic pain by inhibition of JAK/STAT3 pathway in a rat model of chronic constriction injury.

AIM: Neuropathic pain is a common clinical complication of nerve injury, and the effective treatment of neuropathic pain is still challenging. Ligustrazine is mainly used for the treatment of cardiovascular disease and its role in neuropathic pain is less investigated. The purpose of our study was to explore the effects of ligustrazine on neuropathic pain, as well as the underlying molecular mechanism. METHODS: Neuropathic pain was induced by chronic constriction injury (CCI) of the right sciatic nerve in Sprague-Dawley (SD) rats. After CCI, rats received ligustrazine, IL-6, or both. Mechanical withdrawal threshold (MWT) and paw withdrawal thermal latency (PWTL) were assessed on days 1, 3, 7, and 14 after surgery. Expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-ß, IL-2, and phosphorylation of Signal Transducer and Activator of Transcription (STAT) 3 were analyzed. RESULTS: Our results showed that both MWT and PWTL were significantly decreased by CCI on days 1, 3, 7 and 14 compared to sham group, however, ligustrazine reversed this effects. Additionally, the elevated levels of TNF-α, IL-1ß, and IL-2 in CCI spinal cord were inhibited by ligustrazine. Quantitative real-time (qRT-PCR) and Western blotting analysis showed that the test substance reduced the elevated expression of pSTAT3 in the spinal cord induced by CCI, and while IL-6 administration reversed the levels as well as the behavior responses. CONCLUSION: Our results suggest that ligustrazine could effectively attenuate neuropathic pain by inhibition of Janus Kinase (JAK)/STAT3 pathway in CCI rats.

[Chemical constituents of Trichosanthes kirilowii peels].

OBJECTIVE: To study the chemical constituents of the peels of Trichosanthes kirilowii. METHODS: Many chromatographic techniques were used including repeated silica column chromatography, polyamide resin and semi-preparative high performance liquid chromatography. According to the physical and chemical properties and spectral analysis, the chemical structures of the compounds were determined. RESULTS: Thirteen compounds were isolated and identified as quercetin-3-O-[alpha-L-rhamnose(1 --> 2)-beta-D-glucopyranosyl]-5-O-beta-D-glucopyranoside (1), quercetin-3-O-rutinoside (2), apigenin-7-O-beta-D-glucopyranoside (3), diosmetin-7-O-beta-D-glucopyranoside (4), luteolin (5), apigenin (6), diosmetin (7), methyl palmitate (8), methyl stearate (9), palmitic acid (10), beta-sitosterol (11), alpha-spin-asterol (12) and stigmasterol (13). CONCLUSION: Compounds 1 - 3, 5 - 7 are isolated from this plant for the first time.

Emergency response to ecological protection in maritime phenol spills: Emergency monitor, ecological risk assessment, and reduction.

Recently, hundreds of maritime accidental spills of hazardous chemicals have raised public concerns, especially for phenol due to its potential of spills and highly toxicity. Therefore, for marine ecological protection, this article prepared specific strategies of emergency response to phenol spills. Through the identification for phenol behavior at sea, migration prediction, emergency monitor, as well as their new methods were reviewed. Further, ecological risk assessment and seawater quality criteria were conducted by using a species sensitivity distribution (SSD) approach, wherein, risk quotient (RQ) indicated phenol of simulated marine spills posed a high risk (RQ > 1) in 30 days. The method with eco-friendliness and high-efficiency for phenol reduction was constructed by combination of dredging equipment such as pneumatic dredgers (Airlift) and bioremediation, where marine microorganisms that degraded phenol were summarized, as well as future research needs. This study provided a guidance for emergency response and policy development of phenol spills.

ß-N-methylamino-L-alanine production, photosynthesis and transcriptional expression in a possible mutation strain and a wild strain of Thalassiosira minima.

The neurotoxin ß-N-methylamino-L-alanine (BMAA) produced by marine diatoms has been implicated as an important environmental trigger of neurodegenerative diseases in humans. However, the biosynthesis mechanism of BMAA in marine diatoms is still unknown. In the present study, the strain of diatom Thalassiosira minima almost lost the biosynthesis ability for BMAA after a long-term subculture in our laboratory. The production of BMAA-containing proteins in the mutant strain of T. minima reduced to 18.2 % of that in the wild strain, meanwhile the cell size decreased but pigment content increased in the mutant strain. Take consideration of our previous transcriptional data on the mixed diatom and cyanobacterium cultures, the current transcriptome analysis showed four identical and highly correlated KEGG pathways associated with the accumulation of misfolded proteins in diatom, including ribosome, proteasome, SNARE interactions in vesicle transport, and protein processing in the endoplasmic reticulum. Analysis of amino acids and transcriptional information suggested that amino acid synthesis and degradation are associated with the biosynthesis of BMAA-containing proteins. In addition, a reduction in the precision of ubiquitination-mediated protein hydrolysis and vesicular transport by the COPII system will exacerbate the accumulation of BMAA-containing proteins in diatoms.

How does the neurotoxin ß-N-methylamino-L-alanine exist in biological matrices and cause toxicity?

The neurotoxin ß-N-methylamino-L-alanine (BMAA) has been deemed as a risk factor for some neurodegenerative diseases such as amyotrophic lateral sclerosis/parkinsonism dementia complex (ALS/PDC). This possible link has been proved in some primate models and cell cultures with the appearance that BMAA exposure can cause excitotoxicity, formation of protein aggregates, and/or oxidative stress. The neurotoxin BMAA extensively exists in the environment and can be transferred through the food web to human beings. In this review, the occurrence, toxicological mechanisms, and characteristics of BMAA were comprehensively summarized, and proteins and peptides were speculated as its possible binding substances in biological matrices. It is difficult to compare the published data from previous studies due to the inconsistent analytical methods and components of BMAA. The binding characteristics of BMAA should be focused on to improve our understanding of its health risk to human health in the future.

Detection and dietary risk of per- and polyfluoroalkyl substances in shellfish products from the coasts of Bohai Sea and South China Sea.

Artificial per- and polyfluoroalkyl substances (PFASs) are widely distributed in the environment and are potentially harmful to human health. This study assessed the matrix effect of different shellfish on LC-MS analysis and the recoveries of PFASs in purified extracts purified by adding ENVI-Carb graphitized carbon black. Total 76 samples were collected from coastal cities of the Bohai Sea and South China Sea in China. Results showed that the signal response of perfluorocarboxylic acid increased with the length of fluorocarbon chains. ENVI-Carb can mitigate the shellfish matrix effects for analysis of PFASs. Ten PFASs components were detected in shellfish samples at concentrations ranging from 1.3 to 8.5 ng/g wet weight. The PFOA and PFHxS were the dominant components, and PFOA, PFTrDA and PFNA were detected at high rates of 58-93%. The highest levels of ∑PFASs were accumulated in clams, while the lowest levels were found in mussels. The dietary risk assessment indicated that PFASs potentially threaten human health via consumption of clam products in the Bohai Sea region. This study will improve the understanding of the contamination status and the dietary risk of PFASs in shellfish products along the coasts of Bohai Sea and South China Sea in China.