Coupling between intra- and intermolecular motions in liquid water revealed by two-dimensional terahertz-infrared-visible spectroscopy.

The interaction between intramolecular and intermolecular degrees of freedom in liquid water underlies fundamental chemical and physical phenomena such as energy dissipation and proton transfer. Yet, it has been challenging to elucidate the coupling between these different types of modes. Here, we report on the direct observation and quantification of the coupling between intermolecular and intramolecular coordinates using two-dimensional, ultra-broadband, terahertz-infrared-visible (2D TIRV) spectroscopy and molecular dynamics calculations. Our study reveals strong coupling of the O-H stretch vibration, independent of the degree of delocalization of this high-frequency mode, to low-frequency intermolecular motions over a wide frequency range from 50 to 250 cm-1, corresponding to both the intermolecular hydrogen bond bending (≈ 60 cm-1) and stretching (≈ 180 cm-1) modes. Our results provide mechanistic insights into the coupling of the O-H stretch vibration to collective, delocalized intermolecular modes.

Fiber Connections of the Caudal Corpus Cerebelli, with Special Reference to the Intrinsic Circuitry, in a Teleost (Oreochromis niloticus).

The caudal part of the corpus cerebelli of Nile tilapia can be divided into dorsal and ventral regions. The granule cell layer of the dorsal (dGL) and ventral (vGL) regions of the caudal corpus cerebelli is known to receive indirect inputs from the telencephalon relayed by the nucleus paracommissuralis. The descending pathways are topographically organized, and the dGL and vGL receive inputs from different dorsal telencephalic parts. The caudal corpus cerebelli, in turn, projects extracerebellar efferents. However, it remains unknown how the descending telencephalic inputs are processed within the cerebellum. Therefore, the present study investigated intrinsic connections of the caudal corpus cerebelli by injecting neural tracers into the molecular layer of dorsal and ventral regions. Injections of tracers into the ventral molecular layer resulted in labeled cells in the vGL and the ganglionic layer of the ventral corpus. The axonal trajectories from labeled cells in the ganglionic layer were analyzed in detail via single-axon reconstructions, which suggested that the terminal portions were confined to the ganglionic layer of the dorsal corpus. No labeled terminals were observed outside the caudal corpus cerebelli. Tracer applications to the dorsal molecular layer resulted in labeled cells not only in the ganglionic layer and the granule cell layer of the dorsal corpus but also in the ganglionic layer of the ventral corpus. The latter finding confirms the presence of intrinsic projections from the ventral region to the dorsal region in the caudal corpus cerebelli. We further revealed that the intrinsic projection neurons are Purkinje cells by immunohistochemistry for zebrin II (aldolase C), which is a marker of Purkinje cells, combined with tracer injections into the dorsal corpus. Unlike injections into the ventral corpus, injections into the dorsal corpus resulted in labeled terminals in extracerebellar structures, such as the nucleus of the medial longitudinal fascicle and reticular formation. The present study suggests that indirect inputs from different telencephalic parts received and processed by distinct regions of caudal corpus cerebelli are sent out of the corpus through the efferent neurons in the dorsal corpus.

Effects of Intermolecular Charge Transfer in Liquid Water on Raman Spectra.

The low-frequency vibrational spectrum of liquid water is composed of contributions from the intermolecular librational and translation modes. The existence of these two modes introduces difficulty into the simulation of experimentally obtained Raman spectra. We constructed a polarizability function for a water model that includes intramolecular charge flow (CF) effects, intermolecular charge transfer (CT) effects, and intermolecular dipole-induced-dipole (DID) effects. We computed the one-dimensional (1D) Raman and terahertz (THz) spectra with all of these effects included (CFCT-DID) and compared with experimental spectra. We find that the CFCT-DID function provides a better description of the experimental results, because the CT effects reduce the polarizability only for translational motion to which parallelly polarized (VV) and perpendicularly polarized (VH) Raman spectra are sensitive. In our calculations of two-dimensional (2D) Raman and THz-Raman spectra, we observe the enhancement of echo signals in both cases. The details of the CFCT-DID function, along with its source code, are provided in the Supporting Information.

Simulating two-dimensional infrared-Raman and Raman spectroscopies for intermolecular and intramolecular modes of liquid water.

Full classical molecular dynamics (MD) simulations of two-dimensional (2D) infrared-Raman and 2D Raman spectroscopies of liquid water were carried out to elucidate a mode-mode coupling mechanism using a polarizable water model for intermolecular and intramolecular vibrational spectroscopy (POLI2VS). This model is capable of describing both infrared and Raman spectra. Second-order response functions, which consist of one molecular polarizability and two molecular dipole moments for 2D IR-Raman and three molecular polarizabilities for 2D Raman spectroscopies, were calculated using an equilibrium-non-equilibrium hybrid MD approach. The obtained signals were analyzed using a multi-mode Brownian oscillator (BO) model with nonlinear system-bath interactions representing the intramolecular OH stretching, intramolecular HOH bending, hydrogen bonded (HB)-intermolecular librational motion and HB-intermolecular vibrational (translational) motion of liquid water. This model was applied through use of hierarchal Fokker-Planck equations. The qualitative features of the peak profiles in the 2D spectra obtained from the MD simulations are accurately reproduced with the BO model. This indicates that this model captures the essential features of the intermolecular and intramolecular motion. We elucidate the mechanisms governing the 2D signal profiles involving anharmonic mode-mode coupling, the nonlinearities of the polarizability and dipole moment, and the vibrational dephasing processes of liquid water even in the case that the 2D spectral peaks obtained from the MD simulation overlap or are unclear. The mode coupling peaks caused by electrical anharmonic coupling (EAHC) and mechanical anharmonic coupling (MAHC) are observed in all of the 2D spectra. We find that the strength of the MAHC between the OH-stretching and HB-intermolecular vibrational modes is comparable to that between the OH-stretching and HOH bending modes. Moreover, we find that this OH-stretching and HB-intermolecular vibrational coupling should be observed as off-diagonal cross peaks in the 2D spectra.

The Parapineal Is Incorporated into the Habenula during Ontogenesis in the Medaka Fish.

The parapineal is present in many teleost families, while it is absent in several others. To find out why the parapineal is absent at adult stages in the latter families, the development of the epithalamus was examined in the medaka fish (Oryzias latipes). For this purpose, a green fluorescent protein-transgenic medaka line, in which the pineal complex (pineal and parapineal) is visible fluorescently, was used. We found that a distinct parapineal was present in the roof plate at early developmental stages. Subsequently, however, the parapineal and the associated roof plate began to be incorporated into the habenula between embryonic stages 28 and 29. Between embryonic stages 29 and 30, the entire parapineal was incorporated into the habenula. That is, the parapineal became a small caudomedial region (termed the 'parapineal domain') within the left habenula in the majority of embryos, resulting in the left-sided asymmetry of the epithalamus. Thereby the left habenula became larger and more complex than its right counterpart. In the minority of embryos, the parapineal was incorporated into the right habenula or into the habenulae on both sides. In the majority of embryos, the parapineal domain projected a fiber bundle to a subnucleus (termed the 'rostromedial subnucleus') in the left habenula. The rostromedial subnucleus sent axons, through the left fasciculus retroflexus, to the rostral region of the left half of the interpeduncular nucleus. We further found that the ratio of the left-sided phenotype was temperature dependent and decreased in embryos raised at a high temperature. The present study is the first demonstration that the supposed lack of a distinct parapineal in adult teleost fishes is due to ontogenetic incorporation into the habenula.

Analysis of 2D THz-Raman spectroscopy using a non-Markovian Brownian oscillator model with nonlinear system-bath interactions.

We explore and describe the roles of inter-molecular vibrations employing a Brownian oscillator (BO) model with linear-linear (LL) and square-linear (SL) system-bath interactions, which we use to analyze two-dimensional (2D) THz-Raman spectra obtained by means of molecular dynamics (MD) simulations. In addition to linear infrared absorption (1D IR), we calculated 2D Raman-THz-THz, THz-Raman-THz, and THz-THz-Raman signals for liquid formamide, water, and methanol using an equilibrium non-equilibrium hybrid MD simulation. The calculated 1D IR and 2D THz-Raman signals are compared with results obtained from the LL+SL BO model applied through use of hierarchal Fokker-Planck equations with non-perturbative and non-Markovian noise. We find that all of the qualitative features of the 2D profiles of the signals obtained from the MD simulations are reproduced with the LL+SL BO model, indicating that this model captures the essential features of the inter-molecular motion. We analyze the fitted 2D profiles in terms of anharmonicity, nonlinear polarizability, and dephasing time. The origins of the echo peaks of the librational motion and the elongated peaks parallel to the probe direction are elucidated using optical Liouville paths.

Notes on simulating two-dimensional Raman and terahertz-Raman signals with a full molecular dynamics simulation approach.

Recent developments in two-dimensional (2D) THz-Raman and 2D Raman spectroscopies have created the possibility for quantitatively investigating the role of many dynamic and structural aspects of the molecular system. We explain the significant points for properly simulating 2D vibrational spectroscopic studies of intermolecular modes using the full molecular dynamics approach, in particular, regarding the system size, the treatment of the thermostat, and inclusion of an Ewald summation for the induced polarizability. Moreover, using the simulation results for water employing various polarization functions, we elucidate the roles of permanent and induced optical properties in determining the 2D profiles of the signal.

Calculating two-dimensional THz-Raman-THz and Raman-THz-THz signals for various molecular liquids: the samplers.

Recently, two-dimensional (2D) THz-Raman spectroscopy has been used to investigate the intermolecular modes of liquid water. We examine such 2D spectroscopy signals by means of full molecular dynamics (MD) simulations. In this way, we carry out a detailed analysis of intermolecular interactions that play an essential role in many important chemical processes. We calculate 2D Raman-THz-THz (RTT), THz-Raman-THz (TRT), and 2D Raman signals for liquid water, methanol, formamide, acetonitrile, formaldehyde, and dimethyl sulfoxide using an equilibrium-non-equilibrium hybrid MD simulation algorithm originally developed for 2D Raman spectroscopy. These signals are briefly analyzed in terms of anharmonicity and nonlinear polarizability of vibrational modes on the basis of the 2D Raman signals calculated from a Brownian oscillator model with a nonlinear system-bath interaction. We find that the anharmonic contribution is dominant in the RTT case, while the nonlinear polarizability contribution is dominant in the TRT case. For water and methanol, we observed vibrational echo peaks of librational motion in the 2D TRT signals. The predicted signal profiles and intensities that we obtained provide valuable information that can be applied to 2D spectroscopy experiments, allowing them to be carried out more efficiently.

Prevalence of CD44-positive glomerular parietal epithelial cells reflects podocyte injury in adriamycin nephropathy.

BACKGROUND/AIMS: Recent study suggests that activation of parietal epithelial cells (PECs) contributes to pathogenesis of glomerulosclerosis and the activation marker CD44 increases in evolving glomerulosclerosis. Here we examined the pathogenic roles of CD44+ epithelial cells in mouse adriamycin nephropathy (ADRN), a representative rodent model for idiopathic focal segmental glomerulosclerosis (FSGS). We also evaluated whether the prevalence of CD44+ PECs reflects different levels of podocyte injuries. METHODS: As a model of FSGS with different degrees of podocyte injury, ADRN models in mice of different ages were utilized. Immunohistochemistry and immunofluorescence were used to determine roles of CD44 expression. RESULTS: By immunohistochemistry, CD44 expression became positive in claudin-1+ PECs and an increase in CD44+ PECs was associated with reduced expression of synaptopodin and podocin in diseased glomeruli. Furthermore, immunofluorescence staining demonstrated co-expression with osteopontin, a CD44 ligand that plays a significant role in the progression of glomerulosclerosis, thereby suggesting interactions between these molecules. Analysis of the number of WT-1+ podocytes and the levels of electron microscopic foot process effacement revealed a milder degree of podocyte injury in younger ADRN models compared to older ones. Comparative immunohistochemical analysis indicated that the prevalence of CD44+ PECs consistently reflects different degrees of podocyte injury within each different-aged ADRN model. CONCLUSION: CD44+ PECs play significant roles in progressive glomerulosclerosis and the prevalence of the cells reflects different degrees of podocyte injury in ADRN.

The primary brain vesicles revisited: are the three primary vesicles (forebrain/midbrain/hindbrain) universal in vertebrates?

It is widely held that three primary brain vesicles (forebrain, midbrain, and hindbrain vesicles) develop into five secondary brain vesicles in all vertebrates (von Baer's scheme). We reviewed previous studies in various vertebrates to see if this currently accepted scheme of brain morphogenesis is a rule applicable to vertebrates in general. Classical morphological studies on lamprey, shark, zebrafish, frog, chick, Chinese hamster, and human embryos provide only partial evidence to support the existence of von Baer's primary vesicles at early stages. Rather, they suggest that early brain morphogenesis is diverse among vertebrates. Gene expression and fate map studies on medaka, chick, and mouse embryos show that the fates of initial brain vesicles do not accord with von Baer's scheme, at least in medaka and chick brains. The currently accepted von Baer's scheme of brain morphogenesis, therefore, is not a universal rule throughout vertebrates. We propose here a developmental hourglass model as an alternative general rule: Brain morphogenesis is highly conserved at the five-brain vesicle stage but diverges more extensively at earlier and later stages. This hypothesis does not preclude the existence of deep similarities in molecular prepatterns at early stages.

[Analytical method of cereulide in processed cereal-based foods and milk powder by LC-MS/MS].

An LC-MS/MS method for analysis of cereulide, an emetic toxin produced by Bacillus cereus, was developed. Cereulide was extracted from samples, fried rice, pan-fried noodles, red bean paste and baby formula, with methanol and purified using Oasis HLB cartridges. LC separation was performed on a C18 column with a mixture of formic acid solution and methanol containing ammonium formate as a mobile phase, and the mass spectrometer was operated in the positive electrospray ionization mode. Performance evaluation showed that trueness was higher than 70% and repeatability and reproducibility were within 10%. The limits of quantification were lower than 1 µg/kg.

[Determination of vedaprofen in livestock products and seafoods by liquid chromatography-tandem mass spectrometry].

A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the trace residue determination of vedaprofen (VPF) in livestock products and seafoods. VPF was extracted from each sample with acidified acetone, and the crude extract was re-extracted with ethyl acetate and NaCl solution. Clean-up was performed using a weak anion exchange cartridge (Bond Elut DEA). The LC separation was performed on a C18 column using acetonitrile-0.0025 mol/L formic acid (3 : 2) as the mobile phase and MS was run in the negative ion electrospray ionization mode. The calibration curve was linear in the range of 0.001-0.1 µg/mL VPF. The mean recoveries from equine muscle, cattle muscle, cattle liver, cattle fat, salmon, eel, corbicula, milk, egg and buckwheat honey were 72-94%, and the relative standard deviations (RSDs) were 1.1-2.0%. Limits of quantitation (LOQs) ranged from 0.001 to 0.007 µg/g.

Determination of residual fluoroquinolones in honey by liquid chromatography using metal chelate affinity chromatography.

A new analytical method for the simultaneous determination of seven fluoroquinolones, namely, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, orbifloxacin, sarafloxacin, and difloxacin, especially in dark-colored honey, has been developed. Fluoroquinolone antibiotics were extracted from samples with MacIlvaine buffer solution (pH 4.0) containing EDTA disodium salt dihydrate. The extracts were treated with both a polymeric cartridge and a metal chelate affinity column preloaded with ferric ion (Fe3+). LC separation with fluorescence detection was performed at 40 degrees C using an Inertsil ODS-4 analytical column (150 x 4.6 mm, 3 microm). The mobile phase was composed of 20 mM/L citrate buffer solution (pH 3.1)-acetonitrile mixture (70 + 30, v/v) containing 1 mM/L sodium dodecyl sulfate. Lomefloxacin was used as an internal standard. The developed method was validated according to the criteria of European Commission Decision 2002/657/EC. Decision limits and detection capabilities were below 2.9 and 4.4 microg/kg, respectively.

Catalytic asymmetric synthesis of 1,1-disubstituted tetrahydro-ß-carbolines by phase-transfer catalyzed alkylations.

Efficient catalytic asymmetric synthesis of 1,1-disubstituted tetrahydro-ß-carbolines has been achieved via asymmetric alkylation of 1-cyanotetrahydro-ß-carbolines using a binaphthyl-modified N-spiro-type chiral phase-transfer catalyst. This is a valuable example of hitherto difficult highly enantioselective alkylations at α-carbon of the cyano group under phase-transfer conditions.

Morphogenesis of the medaka cerebellum, with special reference to the mesencephalic sheet, a structure homologous to the rostrolateral part of mammalian anterior medullary velum.

We have examined cerebellar morphogenesis after neural tube stage in medaka (Oryzias latipes), a ray-finned fish, by conventional histology and immunohistochemistry using anti-proliferating cell nuclear antigen (PCNA) and anti-acetylated tubulin antibodies. Our results indicate that the medaka cerebellum is formed in 4 successive stages: (1) formation and enlargement of the cerebellar primordia; (2) rostral midline fusion of the left/right halves of the cerebellar primordia; (3) formation of the cerebellar matrix zones in the midline and caudalmost regions of the primitive cerebellum, and (4) growth and differentiation of the cerebellum. Our results also show that cerebellar morphogenesis is different from that in mammals in 3 important points: the developmental origins of the primordia, directions along which cerebellar fusion proceeds, and number, locations and duration of the cerebellar matrix zones. During the course of this study, an alar-derived membranous structure between the cerebellum and the midbrain in the adult medaka brain was identified as the structure homologous to the rostrolateral part of the mammalian anterior medullary velum. We have named this structure in the adult teleostean brains as the 'mesencephalic sheet'. The present study indicates that there exists both conserved and divergent patterns in cerebellar morphogenesis in vertebrates.

[Determination of bicozamycin in livestock products and seafoods by liquid chromatography-tandem mass spectrometry].

A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for trace residue determination of bicozamycin (BZM) in livestock products and seafoods. BZM was extracted from a sample with acetonitrile-water (4 : 1), followed by a two-stage SPE enrichment and cleanup. The first stage involved a styrene-divinylbenzene copolymer cartridge (GL-Pak PLS-2), and the second stage involved a divinylbenzene-N-vinylpyrrolidone copolymer cartridge (Oasis HLB). The LC separation was performed on a C18 column using 0.01% formic acid-methanol (8 : 2) as the mobile phase and MS detection with negative ion electrospray ionization. The mean recoveries from swine muscle, liver, yellowtail, and milk fortified at the minimum residue limit (MRL) levels and 0.01 microg/g were >70%, and the relative standard deviations (RSDs) were <20%. Limits of quantitation (LOQs) ranged from 0.002 to 0.005 microg/g.

Non-laminar cerebral cortex in teleost fishes?

A large skull is disadvantageous to animals that move quickly in three-dimensional space, such as fishes and birds in water or air. A cerebral neocortex with a six-layered sheet has not evolved, most likely due to the limited cranial space. Instead of the laminar cortex, telencephalic nuclear masses seem to have evolved as the pallium in teleost fishes. We consider that the nuclear masses contain rather simple neural circuits sharing a skeleton of simple circuits in the mammalian cortex, which have been elaborated by additional circuits in mammals. Such basic similarities at the connectional level shared by nuclear and cortical pallium might underlie similar or equivalent functions.

Determination of chloramphenicol residues in bee pollen by liquid chromatography/tandem mass spectrometry.

A novel liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed for the trace residue determination of chloramphenicol (CAP) in bee pollen. CAP was extracted from bee pollen with a mixture of methanol and 1% metaphosphoric acid solution, followed by a 2-stage solid-phase extraction enrichment and cleanup. The first stage involved a polymeric cartridge, and the second stage involved an alumina neutral cartridge. The LC separation was performed on a C18 column with 10 mM ammonium formate-acetonitrile (7 + 3) as the mobile phase and MS detection with negative-ion electrospray ionization. CAP-d5 was used as the internal standard. The method was validated according to Commission Decision 2002/657/EC. The calibration curves were linear between 0.1 and 5.0 ng/mL, and overall recoveries ranged from 98 to 113%. Decision limits (CCalpha) ranged from 0.05 to 0.07 microg/kg, and detection capabilities (CCbeta) ranged from 0.08 to 0.12 microg/kg. The developed method was applied to 11 samples.

Analysis of trace residues of tetracyclines in dark-colored honeys by high-performance liquid chromatography using polymeric cartridge and metal chelate affinity chromatography.

An efficient clean-up procedure was developed for the trace residue determination of tetracyclines (TCs) in dark-colored honeys. TCs were extracted from samples with McIlvaine buffer (pH 4.0) containing 0.01 mol/L Na(2)EDTA. The extracts were treated with both a polymeric cartridge (GL-Pak PLS-2) and a metal chelate affinity column (MCAC) preloaded with copper(II). TCs were eluted and analyzed by high-performance liquid chromatography (HPLC) using fluorescence detection. The method was evaluated for the determination of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) in buckwheat honey, because its color is the darkest. The mean recoveries of OTC, TC and CTC from spiked samples, at three fortification levels, were >70%, and the relative standard deviations (RSDs) were <10%. Limits of quantitation (LOQs) of OTC, TC, and CTC were estimated to be 0.015 mg/kg, 0.019 mg/kg, and 0.024 mg/kg, respectively.

Early development of the cerebellum in teleost fishes: a study based on gene expression patterns and histology in the medaka embryo.

The cerebellar structures of teleosts are markedly different from those of other vertebrates. The cerebellum continues rostrally into the midbrain ventricle, forming the valvula cerebelli, only in ray-finned fishes among vertebrates. To analyze the ontogenetic processes that underlie this morphological difference, we examined the early development of the cerebellar regions, including the isthmus (mid/hindbrain boundary, MHB), of the medaka (Oryzias latipes), by histology and in-situ hybridization using two gene (wnt1 and fgf8) probes. Isthmic wnt1 was expressed stably in the caudalmost mesencephalic region in the neural tube at all developmental stages examined, defining molecularly the caudal limit of the mesencephalon. The wnt1-positive mesencephalic cells became located rostrally to the isthmic constriction at Iwamatsu's stages 25-26. Isthmic fgf8 expression changed dynamically and became restricted to the rostralmost metencephalic region at stage 24. The rostralmost part (prospective valvula cerebelli) of the fgf8-positive rostral metencephalon protruded rostrally into the midbrain ventricle, bypassing the isthmic constriction, at stages 25-26. Thus, the isthmic constriction shifted caudally with respect to the molecularly defined MHB at stages 25-26. Paired cerebellar primordia were formed from the alar plates of the fgf8-positive rostral metencephalon and the fgf8-negative caudal metencephalon in the medaka neural tube. Our results show that cerebellar development differs between teleosts and murines: both the rostral and caudal metencephalic alar plates develop into the cerebellum in medaka, whereas in the murines only the caudal metencephalic alar plate develops into the cerebellum, and the rostral plate is reduced to a thin membrane.