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Marine Drugs Aug 2022Okadaic acid (OA) is a marine biotoxin associated with diarrhetic shellfish poisoning (DSP), posing some threat to human beings. The oral toxicity of OA is complex, and...
Okadaic acid (OA) is a marine biotoxin associated with diarrhetic shellfish poisoning (DSP), posing some threat to human beings. The oral toxicity of OA is complex, and the mechanism of toxicity is not clear. The interaction between OA and gut microbiota may provide a reasonable explanation for the complex toxicity of OA. Due to the complex environment in vivo, an in vitro study may be better for the interactions between OA and gut microbiome. Here, we conducted an in vitro fermentation experiment of gut bacteria in the presence of 0-1000 nM OA. The remolding ability of OA on bacterial composition was investigated by 16S rDNA sequencing, and differential metabolites in fermentation system with different concentration of OA was detected by LC-MS/MS. We found that OA inhibited some specific bacterial genera but promoted others. In addition, eight possible metabolites of OA, including dinophysistoxin-2 (DTX-2), were detected in the fermentation system. The abundance of was strongly correlated with the possible metabolites of OA, suggesting that may be involved in the metabolism of OA in vitro. Our findings confirmed the direct interaction between OA and gut bacteria, which helps to reveal the metabolic process of OA and provide valuable evidence for elucidating the complex toxicity of OA.
Topics: Animals; Chromatography, Liquid; DNA, Ribosomal; Gastrointestinal Microbiome; Humans; Marine Toxins; Okadaic Acid; Pyrans; Rats; Tandem Mass Spectrometry
PubMed: 36135745
DOI: 10.3390/md20090556 -
Environmental Monitoring and Assessment Sep 2022No studies have been carried out on the benthic harmful algal blooms (BHABs) along the Strait of Gibraltar in the Mediterranean, and little is known about the diversity...
Occurrence of three dominant epibenthic dinoflagellates (Ostreopsis spp., Coolia monotis and Prorocentrum lima) in relation to biotic substrates and environmental factors in a highly dynamic ecosystem, the Strait of Gibraltar (Southwestern Mediterranean).
No studies have been carried out on the benthic harmful algal blooms (BHABs) along the Strait of Gibraltar in the Mediterranean, and little is known about the diversity of blooming species. Here, epibenthic dinoflagellates were monitored at least biweekly over 18 months (May 2019-November 2020) in Oued Lihoud, Cap Malabata and Dalia on the thalli of five dominant macrophytes and in the water column. This is the first report on the seasonal distribution of BHAB species hosted by natural biotic substrates in the Strait of Gibraltar, which is known for high hydrodynamics, major entry of Atlantic waters and important maritime traffic. Three BHAB dinoflagellates were observed in the surveyed areas: Ostreopsis spp., Coolia monotis and Prorocentrum lima. The analysis of all data at the three sites showed that Dictyota dichotoma was the most favourable macroalgae host for these benthic dinoflagellates. The highest cell densities were observed in Cap Malabata for Ostreopsis spp. (2.7 × 10 cells/g fresh weight in September 2020), P. lima (4.57 × 10 cells/g FW in September 2020) and C. monotis (4.07 × 10 cells/g FW in June 2019). Phosphate and temperature were positively correlated to the abundances of the studied thermophilic BHAB species. In contrast, negative correlations were recorded with salinity, ammonium, nitrite, nitrate, DIN, nitrogen/phosphate ratio and suspended material, attesting of the complex relationships between environmental factors and BHAB species dynamic in each marine ecosystem. Toxin analyses of the natural phytoplankton assemblage during BHABs showed the presence of only lipophilic toxins, namely okadaic acid and dinophysistoxins produced by P. lima. These BHABs species have to be isolated to establish monoclonal cultures for ribotyping and ecophysiological investigations.
Topics: Ammonium Compounds; Dinoflagellida; Ecosystem; Environmental Monitoring; Gibraltar; Nitrates; Nitrites; Nitrogen; Okadaic Acid; Phosphates; Water
PubMed: 36129570
DOI: 10.1007/s10661-022-10426-9 -
ACS Chemical Neuroscience Oct 2022Alzheimer's disease (AD) is a progressive, fatal, neurodegenerative disorder for which only treatments of limited efficacy are available. Despite early mentions of...
Alzheimer's disease (AD) is a progressive, fatal, neurodegenerative disorder for which only treatments of limited efficacy are available. Despite early mentions of dementia in the ancient literature and the first patient diagnosed in 1906, the underlying causes of AD are not well understood. This study examined the possible role of dopamine, a neurotransmitter that is involved in cognitive and motor function, in AD. We treated adult zebrafish () with okadaic acid (OKA) to model AD and assessed the resulting behavioral and neurochemical changes. We then employed a latent learning paradigm to assess cognitive and motor function followed by neurochemical analysis with fast-scan cyclic voltammetry (FSCV) at carbon fiber microelectrodes to measure the electrically stimulated dopamine release. The behavioral assay showed that OKA treatment caused fish to have lower motivation to reach the goal chamber, resulting in impeded learning and decreased locomotor activity compared to controls. Our voltammetric measurements revealed that the peak dopamine overflow in OKA-treated fish was about one-third of that measured in controls. These findings highlight the profound neurochemical changes that may occur in AD. Furthermore, they demonstrate that applying the latent learning paradigm and FSCV to zebrafish is a promising tool for future neurochemical studies and may be useful for screening drugs for the treatment of AD.
Topics: Alzheimer Disease; Animals; Carbon Fiber; Dopamine; Microelectrodes; Neurotransmitter Agents; Okadaic Acid; Zebrafish
PubMed: 36113115
DOI: 10.1021/acschemneuro.2c00484 -
Heliyon Sep 2022As a major component of diarrheic shellfish poisoning (DSP) toxins, okadaic acid (OA) is widely distributed worldwide, and causes a series of serious public health...
As a major component of diarrheic shellfish poisoning (DSP) toxins, okadaic acid (OA) is widely distributed worldwide, and causes a series of serious public health problems. In colon tissue, previous studies have shown that high doses of OA can affect various intracellular processes, including destroy intercellular communication at gap junctions, induce cell apoptosis and trigger cell cycle arrest. However, there is a scarcity of studies on the effect and mechanism of action of low doses of OA in colonic tissues. In this study, we observed that exposure to low levels of OA altered cell cycle progression and . Investigation of the underlying mechanism revealed that OA induced alterations in the cell cycle by inhibiting the p53 signaling pathway or inducing the Jak/Stat3 signaling pathway. In conclusion, this study provides novel insights into the effect and mechanism underlying long-term exposure to low levels of OA.
PubMed: 36105456
DOI: 10.1016/j.heliyon.2022.e10444 -
RSC Advances Aug 2022In this study, a simple electrochemical aptasensor for saxitoxin (STX) detection was developed based on a short anti-STX aptamer with a methylene blue (MB) incorporated...
In this study, a simple electrochemical aptasensor for saxitoxin (STX) detection was developed based on a short anti-STX aptamer with a methylene blue (MB) incorporated at the 3'-end. The aptamer was immobilized on the surface of gold electrode and served as the recognition element. The aptasensor was successfully used as a highly selective and sensitive biosensor for STX detection because of the selection of aptamer along with the excellent electrocatalytical properties of MB. With the increase of the dynamic concentration of STX from 1 nM to 1 μM, the aptasensor exhibited a sensitivity with a peak current change of 2.92 μA per decade and a low detection limit of 1 nM. In addition, the aptasensor demonstrated excellent selectivity to STX, which prevented the interferences from neo-STX, okadaic acid and common metal ions. Using the proposed principle, several other aptasensors with improved performance can be constructed the modification of the electrochemical sensor with appropriate aptamers.
PubMed: 36093254
DOI: 10.1039/d2ra03690h -
Journal of Pharmacological Sciences Oct 2022Studies have shown that inhibition of PI3K/AKT signaling is a key strategy for the treatment of tyrosine kinase inhibitor resistance in non-small cell lung cancer...
Studies have shown that inhibition of PI3K/AKT signaling is a key strategy for the treatment of tyrosine kinase inhibitor resistance in non-small cell lung cancer (NSCLC). Vasculogenic mimicry (VM) not only accelerates tumor progression but also increases drug-induced resistance. As a tumor suppressor, protein phosphatase 2A (PP2A) is a ubiquitous conserved serine/threonine phosphatase. While its effects and mechanisms on VM formation and invasion in NSCLC remain unclear. The present study aimed to investigate the role of PP2A in VM formation and elucidate the underlying mechanisms. Results showed that PP2A could significantly inhibit VM formation and VM-dependent behavior, including invasion and migration both in vitro and in vivo. Activation of PP2A with FTY720 or Ad-PP2A reduced phosphorylated AKT and inhibited ZEB1 transcription, thereby further downregulating the expression of MMP-2, VE-cadherin, and VEGFR-2, whereas inhibition of PP2A with okadaic acid (OA) or Ad-dn-PP2A exerted the opposite effect. Furthermore, PP2A inhibited tumor growth and VM formation in the xenograft tumor model. PI3K inhibitor BENC-511 could potentiate activation of PP2A, leading to inhibition of p-AKT/ZEB1 and VM formation in vitro and in vivo. This study indicated that PP2A could regulate VM formation in NSCLC through the PI3K/AKT/ZEB1 axis. PP2A reactivation or combination with PI3K inhibitor might be a more effective treatment against advanced NSCLC by inhibiting VM formation.
Topics: Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Humans; Lung Neoplasms; Neovascularization, Pathologic; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Protein Phosphatase 2; Proto-Oncogene Proteins c-akt; Zinc Finger E-box-Binding Homeobox 1
PubMed: 36055752
DOI: 10.1016/j.jphs.2022.07.001 -
Nutrients Aug 2022In this study, the effects of cinnamaldehyde and curcumin on Akt2, a serine/threonine protein kinase central to the insulin signaling pathway, were examined in...
In this study, the effects of cinnamaldehyde and curcumin on Akt2, a serine/threonine protein kinase central to the insulin signaling pathway, were examined in preadipocytes. Cinnamaldehyde or curcumin treatment increased Akt2 phosphorylation at multiple sites including T450 and Y475, but had no effect on Akt2 phosphorylation at S474, which is critical for Akt2 activation. Surprisingly, insulin treatment with cinnamaldehyde or curcumin increased p-Akt2 (S474) by 3.5-fold versus insulin treatment alone. Furthermore, combined cinnamaldehyde, curcumin, and insulin treatment increased p-Akt2 (S474) by 7-fold versus insulin treatment alone. Interestingly, cinnamaldehyde and curcumin inhibited both serine/threonine phosphatase 2A (PP2A) and protein tyrosine phosphatase 1B (PTP1B). Akt2 activation is a multistep process that requires phosphorylation at T450 for proper folding and maturation, and phosphorylation of both Y475 and S474 for stabilization of the catalytic domain. It is plausible that by inhibiting PP2A and PTP1B, cinnamaldehyde and curcumin increase phosphorylation at T450 and Y475, and prime Akt2 for insulin-stimulated phosphorylation at S474. Notably, the combination of a PP2A inhibitor, okadaic acid, and a PTP1B inhibitor increased p-Akt2 (S474), even in the absence of insulin. Future combinations of PP2A and PTP1B inhibitors provide a rational platform to engineer new therapeutics for insulin resistance syndrome.
Topics: Acrolein; Curcumin; Enzyme Inhibitors; Insulin; Phosphorylation; Serine
PubMed: 36014807
DOI: 10.3390/nu14163301 -
Molecular Biology of the Cell Oct 2022The term M-phase supershift denotes the phosphorylation-dependent substantial increase in the apparent molecular weight of numerous proteins of varied biological...
The term M-phase supershift denotes the phosphorylation-dependent substantial increase in the apparent molecular weight of numerous proteins of varied biological functions during M-phase induction. Although the M-phase supershift of multiple key mitotic regulators has been attributed to the multisite phosphorylation catalyzed by the Cdk1/cyclin B/Cks complex, this view is challenged by multiple lines of paradoxical observations. To solve this problem, we reconstituted the M-phase supershift of Xenopus Cdc25C, Myt1, Wee1A, APC3, and Greatwall in Xenopus egg extracts and characterized the supershift-producing phosphorylations. Our results demonstrate that their M-phase supershifts are each due to simultaneous phosphorylation of a considerable portion of S/T/Y residues in a long intrinsically disordered region that is enriched in both S/T residues and S/TP motifs. Although the major mitotic kinases in Xenopus egg extracts, Cdk1, MAPK, Plx1, and RSK2, are able to phosphorylate the five mitotic regulators, they are neither sufficient nor required to produce the M-phase supershift. Accordingly, inhibition of the four major mitotic kinase activities in Xenopus oocytes did not inhibit the M-phase supershift in okadaic acid-induced oocyte maturation. These findings indicate that the M-phase supershift is produced by a previously unrecognized category of mitotic phosphorylation that likely plays important roles in M-phase induction.
Topics: Animals; CDC2 Protein Kinase; Cell Cycle Proteins; Cyclin B; Mitosis; Okadaic Acid; Oocytes; Phosphorylation; Xenopus Proteins; Xenopus laevis
PubMed: 35976701
DOI: 10.1091/mbc.E22-04-0118 -
Environmental Science & Technology Sep 2022A multiplex lateral flow immunoassay (LFA) has been developed to detect the primary marine biotoxin groups: amnesic shellfish poisoning toxins, paralytic shellfish...
A multiplex lateral flow immunoassay (LFA) has been developed to detect the primary marine biotoxin groups: amnesic shellfish poisoning toxins, paralytic shellfish poisoning toxins, and diarrhetic shellfish poisoning toxins. The performance characteristics of the multiplex LFA were evaluated for its suitability as a screening method for the detection of toxins in shellfish. The marine toxin-specific antibodies were class-specific, and there was no cross-reactivity between the three toxin groups. The test is capable of detecting all three marine toxin groups, with working ranges of 0.2-1.5, 2.5-65.0, and 8.2-140.3 ng/mL for okadaic acid, saxitoxin, and domoic acid, respectively. This allows the multiplex LFA to detect all three toxin groups at the EU regulatory limits, with a single sample extraction method and dilution volume. No matrix effects were observed on the performance of the LFA with mussel samples spiked with toxins. The developed LFA uses a simple and pocket-sized, portable Cube Reader to provide an accurate result. We also evaluated the use of this Cube Reader with commercially available monoplex lateral flow assays for marine toxins.
Topics: Animals; Bivalvia; Marine Toxins; Okadaic Acid; Saxitoxin; Shellfish; Shellfish Poisoning
PubMed: 35951987
DOI: 10.1021/acs.est.2c02339 -
Antioxidants (Basel, Switzerland) Jul 2022Glycoside hydrolases (GHs) are enzymes that hydrolyze glycosidic bonds, but some of them can also catalyze the synthesis of glycosides by transglycosylation. However,...
Glycoside hydrolases (GHs) are enzymes that hydrolyze glycosidic bonds, but some of them can also catalyze the synthesis of glycosides by transglycosylation. However, the yields of this reaction are generally low since the glycosides formed end up being hydrolyzed by these same enzymes. For this reason, mutagenic variants with null or drastically reduced hydrolytic activity have been developed, thus enhancing their synthetic ability. Two mutagenic variants, a glycosynthase engineered from a β-glucosidase (BGL-1-E521G) and a thioglycoligase from a β-xylosidase (BxTW1-E495A), both from the ascomycete , were used to synthesize three novel epigallocatechin gallate (EGCG) glycosides. EGCG is a phenolic compound from green tea known for its antioxidant effects and therapeutic benefits, whose glycosylation could increase its bioavailability and improve its bioactive properties. The glycosynthase BGL-1-E521G produced a β-glucoside and a β-sophoroside of EGCG, while the thioglycoligase BxTW1-E495A formed the β-xyloside of EGCG. Glycosylation occurred in the 5″ and 4″ positions of EGCG, respectively. In this work, the reaction conditions for glycosides' production were optimized, achieving around 90% conversion of EGCG with BGL-1-E521G and 60% with BxTW1-E495A. The glycosylation of EGCG caused a slight loss of its antioxidant capacity but notably increased its solubility (between 23 and 44 times) and, in the case of glucoside, also improved its thermal stability. All three glycosides showed better antiproliferative properties on breast adenocarcinoma cell line MDA-MB-231 than EGCG, and the glucosylated and sophorylated derivatives induced higher neuroprotection, increasing the viability of SH-S5Y5 neurons exposed to okadaic acid.
PubMed: 35883816
DOI: 10.3390/antiox11071325