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Phosphoinositide-3 kinase (PI3K) activity is important for several aspects of neuronal differentiation and plasticity. However, its direct involvement in regulated exocytosis is unclear, despite clear evidence for a requirement for phosphoinositides in this process. Neurotransmitter release from synaptosomes and hormonal secretion from chromaffin cells is only sensitive to high concentrations of the PI3K inhibitors wortmannin and LY294002 pointing to a possible role for the less sensitive PI3K-C2[alpha]. In neurosecretory cells PI3K-C2[alpha] was detected on a subpopulation of mature secretory granules, abutting the plasma membrane. Both PI3K-C2[alpha] antibodies and PI3K inhibitors selectively prevented ATP-dependent priming in permeabilized chromaffin cells. Transient expression of PI3K-C2[alpha] potentiated secretion, whereas its catalytically inactive mutant abolished exocytosis, suggesting a possible role of the main catalytic product of this enzyme, PtdIns-3-phosphate (PtdIns3P), in this process. Treatment of PC12 cells expressing the PtdIns3P-binding FYVE domain with a low concentration of wortmannin selectively abolished early endosomal staining and revealed a full colocalisation with PI3K-C2[alpha] on PC12 granules. Finally, sequestration of PtdIns3P by the overexpression of FYVE domain abolished secretion from PC12 cells. Together these data demonstrate that production of PtdIns3P along with PtdIns4,5[P.sub.2] is required in the acquisition of fusion competence that secretory vesicles undergo during or following docking to the plasma membrane.

Background Previously we described a transdominant negative mutant of the HIV-1 Tat protein, termed Nullbasic, that downregulated the steady state levels of unspliced and singly spliced viral mRNA, an activity caused by inhibition of HIV-1 Rev activity. Nullbasic also altered the subcellular localizations of Rev and other cellular proteins, including CRM1, B23 and C23 in a Rev-dependent manner, suggesting that Nullbasic may disrupt Rev function and trafficking by intervening with an unidentified component of the Rev nucleocytoplasmic transport complex. Results To seek a possible mechanism that could explain how Nullbasic inhibits Rev activity, we used a proteomics approach to identify host cellular proteins that interact with Nullbasic. Forty-six Nullbasic-binding proteins were identified by mass spectrometry including the DEAD-box RNA helicase, DDX1. To determine the effect of DDX1 on Nullbasic-mediated Rev activity, we performed cell-based immunoprecipitation assays, Rev reporter assays and bio-layer interferometry (BLI) assays. Interaction between DDX1 and Nullbasic was observed by co-immunoprecipitation of Nullbasic with endogenous DDX1 from cell lysates. BLI assays showed a direct interaction between Nullbasic and DDX1. Nullbasic affected DDX1 subcellular distribution in a Rev-independent manner. Interestingly overexpression of DDX1 in cells not only restored Rev-dependent mRNA export and gene expression in a Rev reporter assay but also partly reversed Nullbasic-induced Rev subcellular mislocalization. Moreover, HIV-1 wild type Tat co-immunoprecipitated with DDX1 and overexpression of Tat could rescue the unspliced viral mRNA levels inhibited by Nullbasic in HIV-1 expressing cells. Conclusions Nullbasic was used to further define the complex mechanisms involved in the Rev-dependent nuclear export of the 9 kb and 4 kb viral RNAs. All together, these data indicate that DDX1 can be sequestered by Nullbasic leading to destabilization of the Rev nucleocytoplasmic transport complex and decreased levels of Rev-dependent viral transcripts. The outcomes support a role for DDX1 in maintenance of a Rev nuclear complex that transports viral RREcontaining mRNA to the cytoplasm. To our knowledge Nullbasic is the first anti-HIV protein that specifically targets the cellular protein DDX1 to block Rev's activity. Furthermore, our research raises the possibility that wild type Tat may play a previously unrecognized but very important role in Rev function. [ABSTRACT FROM AUTHOR]

The substituted imidazolate-based MOF (SIM-1) easily forms a homogeneous layer at the surface of millimetric platinum-loaded alumina beads. This new core–shell SIM-1@Pt/Al2O3 catalyst shows the fine molecular sieving effect for the Pt-catalyzed hydrogenation of carbon–carbon double bonds. [ABSTRACT FROM AUTHOR]

Glycerotoxin (GLTx) is capable of stimulating neurotransmitter release at the frog neuromuscular junction by directly interacting with N-type Ca2+ (Cav2.2) channels. Here we have utilized GLTx as a tool to investigate the functionality of Cav2.2 channels in various mammalian neuronal preparations. We first adapted a fluorescent-based high-throughput assay to monitor glutamate release from rat cortical synaptosomes. GLTx potently stimulates glutamate secretion and Ca2+ influx in synaptosomes with an EC50 of 50 pm. Both these effects were prevented using selective Cav2.2 channel blockers suggesting the functional involvement of Cav2.2 channels in mediating glutamate release in this system. We further show that both Cav2.1 (P/Q-type) and Cav2.2 channels contribute equally to depolarization-induced glutamate release. We then investigated the functionality of Cav2.2 channels at the neonatal rat neuromuscular junction. GLTx enhances both spontaneous and evoked neurotransmitter release causing a significant increase in the frequency of postsynaptic action potentials. These effects were blocked by specific Cav2.2 channel blockers demonstrating that either GLTx or its derivatives could be used to selectively enhance the neurotransmitter release from Cav2.2-expressing mammalian neurons. [ABSTRACT FROM AUTHOR]

Abstract: The reactivity and stability of the carbonate species formed at the surface of a Pt/CeO2 catalyst during the reverse was-gas-shift (RWGS) reaction was investigated by in situ diffuse reflectance (DRIFT) FT-IR spectroscopy at 523K. Like most oxide materials presenting some basic character, the surface of the sample (not yet exposed to the RWGS stream) exhibited a significant concentration of carbonate species, mostly of the polydentate-type. A fraction of these carbonates was reduced by H2 at 573K, leading to the formation of Pt-bound surface carbonyls. Additional carbonates (mostly bidentate species) were formed under RWGS conditions (1% CO2 +4% H2 in Ar at 523K), along with formate species and more carbonyl groups. These additional carbonates, like the polydentate species, were essentially stable under Ar and, surprisingly, under H2/Ar. On the contrary, all carbonate species were readily reacted and/or exchanged under the RWGS feed, as evidenced by steady-state isotopic transient kinetic analysis (SSITKA), and under CO2 and O2 mixtures. It is concluded that the bonding strength of the carbonates and, as a consequence, the reactivity of those depends on the nature of the feed. The possibility of ceria over-reduction is discussed as being a factor that would increase carbonate stability and result in surface poisoning. The possibility of adsorption-assisted desorption is also presented. The data reported here clearly show the need to use operando or steady-state techniques (such as SSITKA) to determine the reactivity of surface species in actual catalysis conditions, as misleading conclusions can otherwise be drawn on reaction mechanisms. [Copyright &y& Elsevier]

Presents information on a study which concluded that new nerve-terminal sprouts formed after damage to the neuromuscular junction are essential for the dynamic interplay between motor nerves and nonneuronal cells. Blockade of acetylcholine by botulinum neurotoxin type A; Materials and methods; Results and discussion.

The intensification of pharmaceutical use globally has led to an increase in the number of water bodies contaminated by drugs, and an effective strategy must be developed to address this issue. In this work, several biochars produced from Miscanthus straw pellets (MSP550, MSP700) and wheat straw pellets (WSP550, WSP700) at 550 and 700°C, respectively, were selected as adsorbents for removing various pharmaceuticals, such as pemetrexed (PEME), sulfaclozine (SCL), and terbutaline (TBL), from the aqueous phase. The biochar characterizations (physicochemical properties, textural properties, morphological structures, and zeta potentials) and adsorptive conditions (contact times, temperatures, and pH effect) were investigated. The infrared and Raman spectra of biochars before and after pharmaceutical adsorption, as well as quantum chemical computations, were carried out to explore the adsorption mechanisms. The results showed that the general adsorption abilities of biochars for pharmaceuticals were in the order of WSP700 > MSP700 > MSP550 > WSP550. Both the higher drug concentration and higher temperature improved biochar adsorption. By decreasing the pH, the adsorption amounts increased for PEME and SCL. However, TBL exhibited the best adsorption at pH 7, whereas a weakening of affinity occurred at lower or higher pH values. Electrostatic interactions and hydrogen bonding were the main adsorptive mechanisms between all biochars and pharmaceuticals. π–π interactions played a role in the adsorption process of low‐temperature‐prepared biochars (MSP550 and WSP550). This work can provide new insights into the control of pharmaceuticals from water with low‐cost adsorbents. Practitioner Points: Use of biochars for pharmaceuticals removal from aqueous phase.Characterization of biochars : physical and chemical properties, textural and surface properties.Simulation calculation for characterization of pharmaceuticals.Kinetic studies of pharmaceuticals adsorption on biochars.DRIFTS and Raman analysis for the understanding of adsorption process. [ABSTRACT FROM AUTHOR]

Munc18-interacting proteins (Mints) are multidomain adaptors that regulate neuronal membrane trafficking, signaling, and neurotransmission. Mint1 and Mint2 are highly expressed in the brain with overlapping roles in the regulation of synaptic vesicle fusion required for neurotransmitter release by interacting with the essential synaptic protein Munc18-1. Here, we have used AlphaFold2 to identify and then validate the mechanisms that underpin both the specific interactions of neuronal Mint proteins with Munc18-1 as well as their wider interactome. We found that a short acidic α-helical motif within Mint1 and Mint2 is necessary and sufficient for specific binding to Munc18-1 and binds a conserved surface on Munc18-1 domain3b. In Munc18-1/2 double knockout neurosecretory cells, mutation of the Mint-binding site reduces the ability of Munc18-1 to rescue exocytosis, and although Munc18-1 can interact with Mint and Sx1a (Syntaxin1a) proteins simultaneously in vitro, we find that they have mutually reduced affinities, suggesting an allosteric coupling between the proteins. Using AlphaFold2 to then examine the entire cellular network of putative Mint interactors provides a structural model for their assembly with a variety of known and novel regulatory and cargo proteins including ADPribosylation factor (ARF3/ARF4) small GTPases and the AP3 clathrin adaptor complex. Validation of Mint1 interaction with a new predicted binder TJAP1 (tight junction-associated protein 1) provides experimental support that AlphaFold2 can correctly predict interactions across such large-scale datasets. Overall, our data provide insights into the diversity of interactions mediated by the Mint family and show that Mints may help facilitate a key trigger point in SNARE (soluble Nethylmaleimide-sensitive factor attachment receptor) complex assembly and vesicle fusion. [ABSTRACT FROM AUTHOR]

[Display omitted] • The surface of cobalt was monitored by operando IR under CO 2 -CO-H 2 mixtures. • The selectivity to methane decreased monotonously with CO surface coverage. • The state of the cobalt metallic surface remained unaffected by the CO/CO2 ratio. An operando IR study was carried out to investigate the loss of selectivity to higher hydrocarbons observed over cobalt-based Fischer-Tropsch catalysts when CO is replaced with CO 2. Our data unambiguously show that the structure and oxidation state of the surface of metallic cobalt remains the same whether CO 2 or CO are cofed with H 2. The selectivity to CH 4 appears to increase monotonously with decreasing surface coverage of adsorbed CO. The switch from Fischer-Tropsch synthesis to methanation using CO 2 -rich feeds over metallic cobalt can therefore be assigned to surface coverage effects only, assuming that most, if not all, hydrocarbons products are formed on metallic cobalt. [ABSTRACT FROM AUTHOR]

SiC and Fe 3 O 4 were used as microwave (MW) susceptors in a novel type of domestic MW oven featuring the so-called "Inverter" technology used for CO 2 trapping and methanation. A catalyst based on cobalt was added and the conversion of CO 2 was studied both in continuous mode (co-feeding H 2 and CO 2) and pulsed mode (sequential CO 2 trapping and desorption/hydrogenation). CO 2 conversion up to 80 % could be achieved over the physical mixture of SiC, Fe 3 O 4 and Co/Al 2 O 3 , although high selectivities to CO were observed. The periodic glow of the susceptors and the corresponding oscillation of the catalytic activity at powers lower than 440 W revealed that MW power delivery was actually pulsed, unlike the manufacturer claim. Higher output power enabled both higher CO 2 conversion rate and selectivity to CH 4. The catalytic performances were improved by operating in CO 2 trapping/methanation mode as compared to a continuous flow mode. [Display omitted] • An "Inverter" domestic microwave, presumably delivering continuous power, oven was tested. • The trapping and microwave-assisted conversion of CO 2 was investigated over non-noble metals. • The inverter MW oven appeared to deliver pulsed radiation at low power. • The slow reduction of cobalt oxide limited the initial conversion of CO 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polymeric carbon was deposited over cobalt catalysts by an ethylene treatment at 230 °C and 260 °C. • The deposited species were found to be similar to those formed during FTS. • Ethylene treatments induced severe catalyst deactivation of the catalysts. • An important deselectivation was observed at similar conversion levels. Polymeric carbon was deposited over Siralox supported cobalt catalysts by an ethylene treatment at 230 °C and 260 °C. Cobalt catalysts with cobalt particle sizes of 10 and 14 nm were studied. Temperature programmed hydrogenation and Raman spectroscopy analyses of the deposited species were found to be similar to those formed during Fischer-Tropsch synthesis. The cobalt catalysts were tested in high-throughput 16 parallel reactors at 20 bars and 220 °C, using a H 2 /CO ratio of 2.12. Data were collected at different space times to compare activities and selectivities at iso -conversion levels. Ethylene treated catalysts showed lower activity that corresponded roughly to the loss of CO adsorption sites. Additionally, a decrease of the heavy products selectivity, an increase in the methane selectivity and a decrease of the olefin to paraffin ratio was observed after the ethylene treatments. Unlike the loss in activity, the deselectivation level was found to depend on the amount of deposited carbon. This phenomenon can be explained by a steric effect of the deposit, but an electronic effect cannot be excluded, but is challenging to prove. [ABSTRACT FROM AUTHOR]