Detection of Extremely Low Level Ciguatoxins through Monitoring of Lithium Adduct Ions by Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry.

Ciguatera poisoning (CP) is the most common type of marine biotoxin food poisoning worldwide, and it is caused by ciguatoxins (CTXs), thermostable polyether toxins produced by dinoflagellate Gambierdiscus and Fukuyoa spp. It is typically caused by the consumption of large fish high on the food chain that have accumulated CTXs in their flesh. CTXs in trace amounts are found in natural samples, and they mainly induce neurotoxic effects in consumers at concentrations as low as 0.2 µg/kg. The U.S. Food and Drug Administration has established CTX maximum permitted levels of 0.01 µg/kg for CTX1B and 0.1 µg/kg for C-CTX1 based on toxicological data. More than 20 variants of the CTX1B and CTX3C series have been identified, and the simultaneous detection of trace amounts of CTX analogs has recently been required. Previously published works using LC-MS/MS achieved the safety levels by monitoring the sodium adduct ions of CTXs ([M+Na]+ > [M+Na]+). In this study, we optimized a highly sensitive method for the detection of CTXs using the sodium or lithium adducts, [M+Na]+ or [M+Li]+, by adding alkali metals such as Na+ or Li+ to the mobile phase. This work demonstrates that CTXs can be successfully detected at the low concentrations recommended by the FDA with good chromatographic separation using LC-MS/MS. It also reports on the method's new analytical conditions and accuracy using [M+Li]+.

A proteomics approach identifies novel resident zebrafish Balbiani body proteins Cirbpa and Cirbpb.

The Balbiani body (Bb) is the first marker of polarity in vertebrate oocytes. The Bb is a conserved structure found in diverse animals including insects, fish, amphibians, and mammals. During early zebrafish oogenesis, the Bb assembles as a transient aggregate of mRNA, proteins, and membrane-bound organelles at the presumptive vegetal side of the oocyte. As the early oocyte develops, the Bb appears to grow slowly, until at the end of stage I of oogenesis it disassembles and deposits its cargo of localized mRNAs and proteins. In fish and frogs, this cargo includes the germ plasm as well as gene products required to specify dorsal tissues of the future embryo. We demonstrate that the Bb is a stable, solid structure that forms a size exclusion barrier similar to other biological hydrogels. Despite its central role in oocyte polarity, little is known about the mechanism behind the Bb's action. Analysis of the few known protein components of the Bb is insufficient to explain how the Bb assembles, translocates, and disassembles. We isolated Bbs from zebrafish oocytes and performed mass spectrometry to define the Bb proteome. We successfully identified 77 proteins associated with the Bb sample, including known Bb proteins and novel RNA-binding proteins. In particular, we identified Cirbpa and Cirbpb, which have both an RNA-binding domain and a predicted self-aggregation domain. In stage I oocytes, Cirbpa and Cirbpb localize to the Bb rather than the nucleus (as in somatic cells), indicating that they may have a specialized function in the germ line. Both the RNA-binding domain and the self-aggregation domain are sufficient to localize to the Bb, suggesting that Cirbpa and Cirbpb interact with more than just their mRNA targets within the Bb. We propose that Cirbp proteins crosslink mRNA cargo and proteinaceous components of the Bb as it grows. Beyond Cirbpa and Cirbpb, our proteomics dataset presents many candidates for further study, making it a valuable resource for building a comprehensive mechanism for Bb function at a protein level.

Simultaneous determination of eight catechins and four theaflavins in bottled tea by liquid chromatography-tandem mass spectrometry for forensic analysis.

Tea, and particularly bottled tea, is widely consumed worldwide and is often encountered at crime scenes in poisoning cases or used in place of urine in drug abuse monitoring. Tea is a rich source of polyphenols, such as catechins and theaflavins, and these compounds are useful for identification of trace quantities of tea samples. However, information on the contents of catechins and theaflavins in bottled tea is limited. In this study, a method was developed for simultaneous analysis of eight catechins and four theaflavins in tea using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The concentrations of these polyphenols were determined in bottled black, oolong, and green teas after a simple pretreatment process by the standard addition method. The developed LC-MS/MS method was rapid and all tested polyphenol compounds were separated within ~14 min. All tea types contained all the catechins, at varying concentrations, but not all the theaflavins were present in all the tea types. This indicates that the theaflavin composition reflects the degree of the fermentation and could be used for discrimination among different types of tea. All the green tea samples contained all eight catechins; however, the concentrations of these compounds varied among the tea samples. Principal component analysis and hierarchical cluster analysis were useful for discrimination of samples. It has been unclear whether the variations of chemical components are useful for forensic discrimination. Our results demonstrate that, in addition to identification of tea varieties, catechins and theaflavins can be used for the discrimination of bottled tea samples.

In Vitro and in Silico Studies of Potential Coronavirus-Specific 3C-Like Protease Inhibitors.

We investigated similar compounds to ebselen and tideglusib, which exhibit strong activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), using Molecular ACCess System (MACCS) keys. Four candidate compounds were identified. One of them, phenyl-benzothiazol-3-one, showed coronavirus-specific 3C-like (3CL) protease inhibitory activity. The results indicated that a similarity score above 0.81 is a good indicator of activity for ebselen-and-tideglusib-like compounds. Subsequently, we simulated the ring-cleavage Michael reaction of ebselen at the Se center, which is responsible for its 3CL protease inhibitory activity, and determined the activation free energy of the reaction. The results showed that reaction simulation is a useful tool for estimating the activity of inhibitory compounds that undergo Michael addition reactions with the relevant cysteine S atom of 3CL proteases.

Microinjection Method for Analyzing Zebrafish Early Stage Oocytes.

Maternal factors which accumulate and establish oocyte polarity during the early stages of oogenesis play key roles in embryonic development, as well as germ cell formation. However, vertebrate oogenesis, especially early stages of oogenesis, is not well understood due to the difficulty of accessing these oocytes and the lack of analytical methods. Here, we report on a microinjection method for analyzing zebrafish early-stage oocytes and some artifacts to be aware of when performing oocyte injections or analyzing oocytes. Using this method, we successfully injected mRNAs encoding fluorescent-tagged proteins into early-stage oocytes and observed subcellular localization in the live oocytes. This method is expected to advance the functional analysis of genes involved in oogenesis.

Preparation of ß(1→3)/ß(1→4) xylooligosaccharides from red alga dulse by two xylanases from Streptomyces thermogriseus.

Red alga dulse contains xylan with ß(1→3)/ß(1→4) linkages. We previously prepared xylooligosaccharides (XOSs) from dulse xylan; however, the product contained many D-xylose residues and fewer XOSs with ß(1→3) linkages. To improve the efficiency of XOS production, we prepared two recombinant endoxylanases from Streptomyces thermogriseus (StXyl10 and StXyl11). Comparing the kcat/Km values for dulse xylan, this value from StXyl10 was approximately two times higher than that from StXyl11. We then determined the suitable conditions for XOS production. As a result, dulse XOS was prepared by the successive hydrolysis of 10 mg/mL dulse xylan by 0.5 µg/mL StXyl10 for 4 h at 50 °C and then 2.0 µg/mL StXyl11 for 36 h at 60 °C. Xylan was converted into 95.8% XOS, including 59.7% XOS with a ß(1→3) linkage and 0.97% D-xylose. Our study provides useful information for the production of XOSs with ß(1→3) linkages.

The maternal coordinate system: Molecular-genetics of embryonic axis formation and patterning in the zebrafish.

Axis specification of the zebrafish embryo begins during oogenesis and relies on proper formation of well-defined cytoplasmic domains within the oocyte. Upon fertilization, maternally-regulated cytoplasmic flow and repositioning of dorsal determinants establish the coordinate system that will build the structure and developmental body plan of the embryo. Failure of specific genes that regulate the embryonic coordinate system leads to catastrophic loss of body structures. Here, we review the genetic principles of axis formation and discuss how maternal factors orchestrate axis patterning during zebrafish early embryogenesis. We focus on the molecular identity and functional contribution of genes controlling critical aspects of oogenesis, egg activation, blastula, and gastrula stages. We examine how polarized cytoplasmic domains form in the oocyte, which set off downstream events such as animal-vegetal polarity and germ line development. After gametes interact and form the zygote, cytoplasmic segregation drives the animal-directed reorganization of maternal determinants through calcium- and cell cycle-dependent signals. We also summarize how maternal genes control dorsoventral, anterior-posterior, mesendodermal, and left-right cell fate specification and how signaling pathways pattern these axes and tissues during early development to instruct the three-dimensional body plan. Advances in reverse genetics and phenotyping approaches in the zebrafish model are revealing positional patterning signatures at the single-cell level, thus enhancing our understanding of genotype-phenotype interactions in axis formation. Our emphasis is on the genetic interrogation of novel and specific maternal regulatory mechanisms of axis specification in the zebrafish.

Identification of a Key Enzyme for the Hydrolysis of ß-(1→3)-Xylosyl Linkage in Red Alga Dulse Xylooligosaccharide from Bifidobacterium Adolescentis.

Red alga dulse possesses a unique xylan, which is composed of a linear ß-(1→3)/ß-(1→4)-xylosyl linkage. We previously prepared characteristic xylooligosaccharide (DX3, (ß-(1→3)-xylosyl-xylobiose)) from dulse. In this study, we evaluated the prebiotic effect of DX3 on enteric bacterium. Although DX3 was utilized by Bacteroides sp. and Bifidobacterium adolescentis, Bacteroides Ksp. grew slowly as compared with ß-(1→4)-xylotriose (X3) but B. adolescentis grew similar to X3. Therefore, we aimed to find the key DX3 hydrolysis enzymes in B. adolescentis. From bioinformatics analysis, two enzymes from the glycoside hydrolase family 43 (BAD0423: subfamily 12 and BAD0428: subfamily 11) were selected and expressed in Escherichia coli. BAD0423 hydrolyzed ß-(1→3)-xylosyl linkage in DX3 with the specific activity of 2988 mU/mg producing xylose (X1) and xylobiose (X2), and showed low activity on X2 and X3. BAD0428 showed high activity on X2 and X3 producing X1, and the activity of BAD0428 on DX3 was 1298 mU/mg producing X1. Cooperative hydrolysis of DX3 was found in the combination of BAD0423 and BAD0428 producing X1 as the main product. From enzymatic character, hydrolysis of X3 was completed by one enzyme BAD0428, whereas hydrolysis of DX3 needed more than two enzymes.

Molecular genetics of maternally-controlled cell divisions.

Forward genetic screens remain at the forefront of biology as an unbiased approach for discovering and elucidating gene function at the organismal and molecular level. Past mutagenesis screens targeting maternal-effect genes identified a broad spectrum of phenotypes ranging from defects in oocyte development to embryonic patterning. However, earlier vertebrate screens did not reach saturation, anticipated classes of phenotypes were not uncovered, and technological limitations made it difficult to pinpoint the causal gene. In this study, we performed a chemically-induced maternal-effect mutagenesis screen in zebrafish and identified eight distinct mutants specifically affecting the cleavage stage of development and one cleavage stage mutant that is also male sterile. The cleavage-stage phenotypes fell into three separate classes: developmental arrest proximal to the mid blastula transition (MBT), irregular cleavage, and cytokinesis mutants. We mapped each mutation to narrow genetic intervals and determined the molecular basis for two of the developmental arrest mutants, and a mutation causing male sterility and a maternal-effect mutant phenotype. One developmental arrest mutant gene encodes a maternal specific Stem Loop Binding Protein, which is required to maintain maternal histone levels. The other developmental arrest mutant encodes a maternal-specific subunit of the Minichromosome Maintenance Protein Complex, which is essential for maintaining normal chromosome integrity in the early blastomeres. Finally, we identify a hypomorphic allele of Polo-like kinase-1 (Plk-1), which results in a male sterile and maternal-effect phenotype. Collectively, these mutants expand our molecular-genetic understanding of the maternal regulation of early embryonic development in vertebrates.

New-onset Refractory Status Epilepticus Involving the Limbic System, Spinal Cord, and Peripheral Nerves.

A healthy 28-year-old woman presented suddenly with intractable status epilepticus: a focal seizure evolved into a generalized seizure preceded by a high fever. Brain magnetic resonance imaging indicated bilateral hyperintensities in the hippocampus on T2-weighted imaging. Electroencephalograms continuously demonstrated diffuse sharp waves and poly-spikes. Comprehensive immunomodulation therapies and anti-epileptic drugs did not lead to any improvements. We therefore diagnosed her with cryptogenic limbic encephalitis and new-onset refractory status epilepticus (NORSE). We detected positive anti-ganglioside antibodies, IgG-GQ1b, GD1a, and GT1b, which were negative at six months after the onset. We emphasize the heterogeneous pathogenesis and intractable conditions of NORSE.

Diastereodivergent and Regiodivergent Total Synthesis of Princepin and Isoprincepin in Both (7″R,8″R) and (7″S,8″S) Isomers.

The first total synthesis of (7″R,8″R)-, (7″S,8″S)-isomers of princepin (1) and (7″R,8″R)-, (7″S,8″S)-isomers of isoprincepin (2) was accomplished in a highly stereoselective manner via para quinomethide-mediated construction of the furofuran and 1,4-benzodioxane rings. Structural confirmation methods of 1 and 2 were established by CD and HPLC analysis of each diastereomers with natural products.

Effects of cationic liposomes with stearylamine against virus infection.

In this study, we demonstrated that cationic liposomes with incorporated stearylamine (SA) inhibit viral infectivity without preloaded active pharmaceutical ingredients. Specifically, we correlated physiochemical properties of liposomes, such as zeta potentials and particle sizes, with virus infectivity using the BacMam™ reagent, which is based on recombinant baculovirus (BV). Compared with neutral or negatively-charged liposomes, SA liposomes suppressed BV infectivity in several mammalian cell lines, including A549 cells. SA liposomes inhibited BV infection over 80% by optimizing the liposomal concentration and exposure time with cells. Moreover, these antiviral SA liposomes were not cytotoxic, and reducing the embedded cholesterol contents intensified the antiviral effects and simultaneously increased the binding of SA liposomes to the cell membranes. These data indicate that binding of SA liposomes to cell membranes may block virus entry. Finally, we also demonstrated the antiviral effects of SA liposomes on herpes simplex virus type 1 in A549 cells, and showed comparable efficacy to that of the antiviral drug acyclovir.

Anti-NMDA receptor encephalitis due to large-cell neuroendocrine carcinoma of the uterus.

A 44-year-old woman presented with a large-cell neuroendocrine carcinoma and uterine endometrioid carcinoma with anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis. Following the diagnosis of uterine cancer, the patient suddenly developed psychosis with abnormal behaviors, delusions, irritability, and forgetfulness. The cerebrospinal fluid tested positive for anti-NMDAR antibodies (encoding the NR1 subunit). The patient was diagnosed with paraneoplastic limbic encephalitis due to uterine cancer. Histology of multiple abdominal metastatic samples revealed a neuroendocrine tumor. Her consciousness improved temporarily after tumor resection and comprehensive immunomodulatory therapy. On day 104 after admission, the patient died of multiple organ failure. The autopsy revealed a perivascular infiltration of inflammatory cells in the amygdala and NMDAR-positive cells in the primary uterine cancer. Our findings demonstrated that neuroendocrine tumors can induce anti-NMDAR encephalitis, which is consistent with three previous reports. A comprehensive treatment with resection of the carcinoma, immunoglobulins, and plasma exchange can induce a partial improvement of the symptoms.

Effects of Calcium Ions on the Thermostability and Spectroscopic Properties of the LH1-RC Complex from a New Thermophilic Purple Bacterium Allochromatium tepidum.

The light harvesting-reaction center (LH1-RC) complex from a new thermophilic purple sulfur bacterium Allochromatium (Alc.) tepidum was isolated and characterized by spectroscopic and thermodynamic analyses. The purified Alc. tepidum LH1-RC complex showed a high thermostability comparable to that of another thermophilic purple sulfur bacterium Thermochromatium tepidum, and spectroscopic characteristics similar to those of a mesophilic bacterium Alc. vinosum. Approximately 4-5 Ca2+ per LH1-RC were detected by inductively coupled plasma atomic emission spectroscopy and isothermal titration calorimetry. Upon removal of Ca2+, the denaturing temperature of the Alc. tepidum LH1-RC complex dropped accompanied by a blue-shift of the LH1 Qy absorption band. The effect of Ca2+ was also observed in the resonance Raman shift of the C3-acetyl νC═O band of bacteriochlorophyll-a, indicating changes in the hydrogen-bonding interactions between the pigment and LH1 polypeptides. Thermodynamic parameters for the Ca2+-binding to the Alc. tepidum LH1-RC complex indicated that this reaction is predominantly driven by the largely favorable electrostatic interactions that counteract the unfavorable negative entropy change. Our data support a hypothesis that Alc. tepidum may be a transitional organism between mesophilic and thermophilic purple bacteria and that Ca2+ is one of the major keys to the thermostability of LH1-RC complexes in purple bacteria.

DND protein functions as a translation repressor during zebrafish embryogenesis.

Germline and somatic cell distinction is regulated through a combination of microRNA and germ cell-specific RNA-binding proteins in zebrafish. An RNA-binding protein, DND, has been reported to relieve the miR-430-mediated repression of some germ plasm mRNAs such as nanos3 and tdrd7 in primordial germ cells (PGCs). Here, we showed that miR-430-mediated repression is not counteracted by the overexpression of DND protein in somatic cells. Using a λN-box B tethering assay in the embryo, we found that tethering of DND to reporter mRNA results in translation repression without affecting mRNA stability. Translation repression by DND was not dependent on another germline-specific translation repressor, Nanos3, in zebrafish embryos. Moreover, our data suggested that DND represses translation of nanog and dnd mRNAs, whereas an RNA-binding protein DAZ-like (DAZL) promotes dnd mRNA translation. Thus, our study showed that DND protein functions as a translation repressor of specific mRNAs to control PGC development in zebrafish.

Cerebrospinal fluid dissemination of anaplastic intraventricular meningioma: report of a case presenting with progressive brainstem dysfunction and multiple cranial nerve palsies.

BACKGROUND: It is extremely rare to see cerebrospinal fluid dissemination of intraventricular meningioma, particularly with the development of acute, progressive brainstem/cerebellar dysfunction with an absence of mass formation in the corresponding anatomical sites. CASE PRESENTATION: An 81-year-old man was admitted because of double vision, right facial nerve palsy and truncal ataxia. Brain magnetic resonance imaging showed normal findings except for a tumor mass in the left lateral ventricle, which had been noted over 6 months previously. The patient developed hiccups, hyperventilation, and drowsiness, which worsened progressively, and did not respond to corticosteroid or intraventricular immunoglobulin therapy. Cerebrospinal fluid study revealed a mild elevation of protein, and cytology was negative. The patient died and an autopsy was performed. Postmortem investigation disclosed a malignant transformation of benign fibroid meningioma with cerebrospinal fluid dissemination of the malignant cells, diversely involving the surface of brainstem, cerebellum, and spinal cords, secondarily resulting in extensive ischemia in the brain parenchyma by vessel occlusion. CONCLUSION: If a patient with an intraventricular tumor develops acute, progressive neurological symptoms, the possibility that it is be caused by cerebrospinal fluid dissemination of tumor cells, after malignant transformation, should be considered.

Pre-existing Mobile Cardiac Thrombus and the Risk of Early Recurrent Embolism after Intravenous Thrombolysis: A Case Report.

BACKGROUND: Early recurrence of an embolism is rarely observed in patients with stroke treated with intravenous thrombolysis. Pre-existing cardiac thrombus is thought as a risk factor for recurrent embolism, although the relationship remains unclear. METHODS: The present patient was a 30-year-old man with acute ischemic stroke. Transthoracic echocardiography performed before thrombolysis demonstrated an intraventricular mobile thrombus, and the patient was treated with intravenous thrombolysis 183 minutes after the onset of stroke. During thrombolysis, he suffered from a peripheral artery embolism, without further signs of neurologic deterioration. Repeated transthoracic echocardiography showed the disappearance of the intraventricular thrombus. However, follow-up magnetic resonance imaging disclosed new ischemic lesions at the splenium of the corpus callosum, and body computed tomography showed infarction of the spleen and kidney. The peripheral artery embolism improved spontaneously without further evidence of recurrent embolism. RESULTS: This is the first report to provide findings of an intracardiac mobile thrombus before thrombolysis and to demonstrate the acceleration of detachment of the thrombus during thrombolysis. CONCLUSIONS: Because there are currently no guidelines for the use of intravenous thrombolysis for acute ischemic stroke associated with a pre-existing intracardiac thrombus with respect to the efficacy and safety, physicians should pay special attention to similar cases.