Acquisition of a brief behavioral experience in the presence of neuron-specific and D2-CAM/N-CAM-specific antisera

The effect of intraventricular infusion of D2-CAM/N-CAM directed antibodies prior to the acquisition of a passive-avoidance paradigm is described. The antisera used in this study were the neuron specific anti-BPM and a D2-CAM/N-CAM specific serum, anti-D2. Anti-BPM reliably inhibited paradigm acquisition when recall was ascertained at 24 and 48 hours and no effect was noted with absorbed anti-BPM or in sham-operated animals. This effect was time-dependent and no inhibition of memory formation was noted when the antiserum was administered at 6 and 10 hours after training. In contrast, infusion of anti-D2 had no effect on paradigm acquisition. These findings are discussed in relation to the potential synaptogenic events associated with memory formation.     

D2 Dopamine Receptors in Calf Globus Pallidus: Agonist High- and Low-Affinity Sites Not Regulated by Guanine Nucleotide

By use of the radioligand [3H]spiroperidol, D2 3,4-dihydroxyphenylethylamine (dopamine) receptor binding characteristics were studied in calf globus pallidus and compared with those of neostriatum. Antagonist competition curves were monophasic and revealed similar affinities for neostriatum and globus pallidus, suggesting a uniform receptor population with one affinity state for antagonists. In both regions, competition curves with the agonist dopamine were biphasic, distinguishing a high- and low-agonist-affinity state. In neostriatum and globus pallidus, respectively, 45% and 19% of [3H]spiroperidol binding was displaced with high affinity and the remainder with low affinity. In neostriatum, the addition of 0.4 mM GTP resulted in a partial conversion from high- to low-affinity state with a remaining high-affinity component of 15%. In globus pallidus, dopamine binding was not altered by GTP. The capability of GTP to modulate agonist binding to D2 receptors appears to be dependent on their neuroanatomical localization.     

Supramolecular Engineering for Formamidinium‐Based Layered 2D Perovskite Solar Cells: Structural Complexity and Dynamics Revealed by Solid‐State NMR Spectroscopy

Perovskite solar cells are one of the most promising photovoltaic technologies, although their molecular level design and stability toward environmental factors remain a challenge. Layered 2D Ruddlesden–Popper perovskite phases feature an organic spacer bilayer that enhances their environmental stability. Here, the concept of supramolecular engineering of 2D perovskite materials is demonstrated in the case of formamidinium (FA) containing A₂FA_n?1Pb_nI_3n+1 formulations by employing (adamantan‐1‐yl)methanammonium (A) spacers exhibiting propensity for strong Van der Waals interactions complemented by structural adaptability. The molecular design translates into desirable structural features and phases with different compositions and dimensionalities, identified uniquely at the atomic level by solid‐state NMR spectroscopy. For A₂FA₂Pb₃I₁₀, efficiencies exceeding 7% in mesoscopic device architectures without any additional treatment or use of antisolvents for ambient temperature film deposition are achieved. This performance improvement over the state‐of‐the‐art FA‐based 2D perovskites is accompanied by high operational stability under humid ambient conditions, which illustrates the utility of the approach in perovskite solar cells and sets the basis for advanced supramolecular design in the future.     

26S rDNA单链构象多态性分析在临床酵母菌菌种鉴定中的应用

摘要： 【目的】探讨酵母菌临床分离株26S rDNA D1/D2区序列种内相似性和种间差异性的快速检测方法,为临床酵母菌菌种鉴定方法的改进奠定基础。调查北京地区临床酵母菌的种群多样性,为国内酵母菌感染的流行病学研究提供新的基础数据。【方法】用5种常见临床酵母菌种的模式和权威菌株作为标准参考菌株,从北京四家综合性医院收集临床酵母菌260余株,PCR扩增其26S rDNA D1/D2区,对扩增产物进行单链构象多态性（Single-Strand Conformation Polymorphism,SSCP）分析和序列测定分析。【结果】常见病原酵母菌26S rDNA D1/D2区的SSCP图谱具有明显的种间差异性和种内相似性,可以通过该方法对菌株进行初步的菌种鉴定。D1/D2-SSCP和序列分析相结合,对260余株临床酵母菌进行了菌种鉴定,共鉴定有10个属20个种,优势属为念珠菌属(Candida),优势种及其所占比例分别是：C. albicans (57.7%), C. parapsilosis (10.0%), C. tropicalis (9.2%), C. glabrata (6.7%)和C. krusei (5.8%),并发现过去从未或很少报道致病的酵母菌种,愈来愈多地出现在临床分离菌株中。【结论】 26S rDNA D1/D2区的SSCP图谱分析为临床酵母菌株的快速鉴定提供了新的方法;北京地区酵母菌临床分离株呈种群多样性分布,C. albicans虽然仍占优势,但其它念珠菌种的比例已达42%。     

Alpha-synuclein aggregation and cell death triggered by energy deprivation and dopamine overload are counteracted by D2/D3 receptor activation

Progressive degeneration and intraneuronal Lewy bodies made of filamentous α-synuclein (α-syn) in dopaminergic cells of the nigrostriatal system are characteristics of Parkinson's disease (PD). Glucose uptake is reduced in some of the brain regions affected by PD neurodegenerative changes. Defects in mitochondrial activity in the substantia nigra have been observed in the brain of patients affected by PD and substantia nigra lesions can induce the onset of a secondary parkinsonism. Thus, energy starvation and consequently metabolic impairment to dopaminergic neurons may be related to the onset of PD. On this line, we evaluated the effect of nutrient starvation, reproduced ' in vitro ' by glucose deprivation (GD), in primary mesecephalic neuronal cultures and dopaminergic-differentiated SH-SY5Y cells, to evaluate if decreased glucose support to dopaminergic cells can lead to mitochondrial damage, neurodegeneration and α-syn misfolding. Furthermore, we investigated the effect of dopamine (DA) treatment in the presence of a DA-uptake inhibitor or of the D₂/D₃ receptor (D₂R/D₃R) agonist quinpirole on GD-treated cells, to evaluate the efficacy of these therapeutic compounds. We found that GD induced the formation of fibrillary aggregated α-syn inclusions containing the DA transporter in dopaminergic cells. These alterations were accompanied by dopaminergic cell death and were exacerbated by DA overload. Conversely, the block of DA uptake and D₂R/D₃R agonist treatment exerted neuroprotective effects. These data indicate that glucose starvation is likely involved in the induction of PD-related pathological changes in dopaminergic neurons. These changes may be counteracted by the block of DA uptake and by dopaminergic agonist treatment.     

Spontaneously Self‐Assembly of a 2D/3D Heterostructure Enhances the Efficiency and Stability in Printed Perovskite Solar Cells

As perovskite solar cells (PSCs) are highly efficient, demonstration of high‐performance printed devices becomes important. 2D/3D heterostructures have recently emerged as an attractive way to relieving the film inhomogeneity and instability in perovskite devices. In this work, a 2D/3D ensemble with 2D perovskites self‐assembled atop 3D methylammonium lead triiodide (MAPbI₃) via a one‐step printing process is shown. A clean and flat interface is observed in the 2D/3D bilayer heterostructure for the first time. The 2D perovskite capping layer significantly suppresses nonradiative charge recombination, resulting in a marked increase in open‐circuit voltage (V_OC) of the devices by up to 100 mV. An ultrahigh V_OC of 1.20 V is achieved for MAPbI₃ PSCs, corresponding to 91% of the Shockley–Queisser limit. Moreover, notable enhancement in light, thermal, and moisture stability is obtained as a result of the protective barrier of the 2D perovskites. These results suggest a viable approach for scalable fabrication of highly efficient perovskite solar cells with enhanced environmental stability.     

Identification of medically important yeasts by sequence analysis of the internal transcribed spacer and D1/D2 region of the large ribosomal subunit

BackgroundThe prevalence of opportunistic yeast infections has increased in recent decades as the result of an increasing immunocompromised patient population.AimsTo evaluate ribosomal RNA (rRNA) gene sequence to identify medically important yeast species, to investigate the performance of both the rRNA gene internal transcribed spacer (ITS) and D1/D2 region in identifying clinically relevant yeasts, and to compare these results with those of a standard phenotypic method.MethodsBoth regions from 50 yeast strains, comprising 45 clinical isolates and 5 reference strains, were amplified using PCR and then sequenced. The sequences were compared to reference data available from the GenBank database of the National Center for Biotechnology Information using the BLASTn tool.ResultsUsing ID32C, 88% (44/50) of all strains were identified accurately at the species level, although 6% were misidentified; two Candida eremophila isolates were identified as Candida glabrata and Candida tropicalis, and one Saprochaete clavata isolate was identified as Saprochaete capitata. Two of the four isolates identified by phenotypic methods as Trichosporon asahii were defined so by analyzing the ITS region, but the remaining two were not distinguishable from closely related species. Based on the D1/D2 region, these four isolates had 100% sequence identity with T. asahii, Trichosporon japonicum, and Trichosporon asteroides. The isolate identified as Trichosporon inkin using ID32C could not be distinguished from Trichosporon ovoides by analyzing the ITS and D1/D2 regions.ConclusionsIdentifying medically important yeasts by sequencing the ITS and D1/D2 region is a rapid and reliable alternative to conventional identification methods. For a diagnostic algorithm, we suggest a two-step procedure integrating conventional methods (e.g. microscopic morphology on corn meal agar with Tween® 80 and API ID32C®) and sequence analysis of the ITS and D1/D2 region.     

TBK1-associated Protein in Endolysosomes (TAPE)/CC2D1A Is a Key Regulator Linking RIG-I-like Receptors to Antiviral Immunity

Retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) are key RNA viral sensors for triggering antiviral immunity. The underlying mechanisms for RLRs to trigger antiviral immunity have yet to be explored. Here we report the identification of TAPE (TBK1-associated protein in endolysosomes) as a novel regulator of the RLR pathways. TAPE functionally and physically interacts with RIG-I, MDA5, and IPS-1 to activate the IFN-β promoter. TAPE knockdown impairs IFN-β activation induced by RLRs but not IPS-1. TAPE-deficient cells are defective in cytokine production upon RLR ligand stimulation. During RNA virus infection, TAPE knockdown or deficiency diminishes cytokine production and antiviral responses. Our data demonstrate a critical role for TAPE in linking RLRs to antiviral immunity.     

Cytochalasin D enhances the accumulation of a protease‐resistant form of prion protein in ScN2a cells: involvement of PI3 kinase/Akt signalling pathway

The conversion of a host‐encoded PrPsen (protease‐sensitive cellular prion protein) into a PrPres (protease‐resistant pathogenic form) is a key process in the pathogenesis of prion diseases, but the intracellular mechanisms underlying PrPres amplification in prion‐infected cells remain elusive. To assess the role of cytoskeletal proteins in the regulation of PrPres amplification, the effects of cytoskeletal disruptors on PrPres accumulation in ScN2a cells that were persistently infected with the scrapie Chandler strain have been examined. Actin microfilament disruption with cytochalasin D enhanced PrPres accumulation in ScN2a cells. In contrast, the microtubule‐disrupting agents, colchicine, nocodazole and paclitaxel, had no effect on PrPres accumulation. In addition, a PI3K (phosphoinositide 3‐kinase) inhibitor, wortmannin and an Akt kinase inhibitor prevented the cytochalasin D‐induced enhancement of PrPres accumulation. Cytochalasin D‐induced extension of neurite‐like processes might correlate with enhanced accumulation of PrPres. The results suggest that the actin cytoskeleton and PI3K/Akt pathway are involved in the regulation of PrPres accumulation in prion‐infected cells.     

LC-MS/MS with 2D mass mapping of skin secretions' peptides as a reliable tool for interspecies identification inside Rana esculenta complex

Identification of species constituting Rana esculenta complex represents a certain problem as two parental species Rana ridibunda and Rana lessonae form their hybrid R. esculenta, while external signs and sizes of the members of this complex are intersected. However the composition of skin secretion consisting mainly of peptides is different for the species of the complex. LC-MS/MS is an ideal analytical tool for the quantitative and qualitative analysis of these peptides. The results covering elemental composition of these peptides, their levels in the secretion, as well as their belonging to a certain family of peptides may be visualized by means of 2D mass maps. The proposed approach proved itself to be a perspective tool for the reliable identification of all 3 species constituting R. esculenta complex. Easy distinguishing between the species may be achieved using 2D maps as fingerprints. Besides this approach may be used to study hybridogenesis and mechanisms of hemiclonal transfer of genetic information, when rapid and reliable identification of species involved in the process is required.     

Phase 1/2a clinical trial in ALS with ropinirole,a drug candidate identified by iPSC drug discovery

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Inhibition of benzo(a)pyrene-induced cell cycle progression by all-trans retinoic acid partly through cyclin D1/E2F-1 pathway in human embryo lung fibroblasts

Benzo(a)pyrene [B(a)P] is a potent environmental carcinogen, which induces cell cycle changes. All-trans retinoic acid (ATRA) is a promising agent in prevention and treatment of human cancers. In the present study, we investigated the inhibition of B(a)P-induced cell cycle progression by ATRA in human embryo lung fibroblast (HELF). Our results showed that after treatment with B(a)P, the expression of cyclin D1 and E2F-1 were both increased significantly in HELF. There were almost no changes of CDK4 and E2F-4 expression by treatment with B(a)P. As expected, pretreatment with ATRA could efficiently decrease B(a)P-induced overexpression of cyclin D1 and E2F-1. In a further study, we stably transfected antisense cyclin D1 and antisense CDK4 plasmid into HELF. The inhibition of cyclin D1 expression and the inhibition of CDK4 expression significantly impaired the B(a)P-induced overexpression of E2F-1 respectively. Pretreatment with ATRA, cells expressing antisense cyclinD1 or antisense CDK4 showed a lesser decrease of B(a)P-induced overexpression of E2F-1 compared with similarly treated HELF. Furthermore, flow cytometry analysis showed that B(a)P promoted cell cycle progression from G(1) phase to S phase, while pretreatment with ATRA could inhibit B(a)P-induced cell cycle progression by an accumulation of cells in the G(1) phase. It was suggested that ATRA could block B(a)P-induced cell cycle promotion partly through the cyclin D1/E2F-1 pathway in HELF.     

Glycerate-3-phosphate, produced by CO2 fixation in the Calvin cycle, is critical for the synthesis of the D1 protein of photosystem II

We demonstrated recently that, in intact cells of Chlamydomonas reinhardtii, interruption of CO₂ fixation via the Calvin cycle inhibits the synthesis of proteins in photosystem II (PSII), in particular, synthesis of the D1 protein, during the repair of PSII after photodamage. In the present study, we investigated the mechanism responsible for this phenomenon using intact chloroplasts isolated from spinach leaves. When CO₂ fixation was inhibited by exogenous glycolaldehyde, which inhibits the phosphoribulokinase that synthesizes ribulose-1,5-bisphosphate, the synthesis de novo of the D1 protein was inhibited. However, when glycerate-3-phosphate (3-PGA), which is a product of CO₂ fixation in the Calvin cycle, was supplied exogenously, the inhibitory effect of glycolaldehyde was abolished. A reduced supply of CO₂ also suppressed the synthesis of the D1 protein, and this inhibitory effect was also abolished by exogenous 3-PGA. These findings suggest that the supply of 3-PGA, generated by CO₂ fixation, is important for the synthesis of the D1 Protein. It is likely that 3-PGA accepts electrons from NADPH and decreases the level of reactive oxygen species, which inhibit the synthesis of proteins, such as the D1 protein.     

Ganoderic acid D prevents oxidative stress‐induced senescence by targeting 14‐3‐3ε to activate CaM/CaMKII/NRF2 signaling pathway in mesenchymal stem cells

Stem cell senescence is an important cause of aging. Delaying senescence may present a novel way to combat aging and age‐associated diseases. This study provided a mechanistic insight into the protective effect of ganoderic acid D (GA‐D) against human amniotic mesenchymal stem cell (hAMSCs) senescence. GA‐D, a Ganoderma lucidum‐derived triterpenoid, markedly prevented hAMSCs senescence via activating the Ca²⁺ calmodulin (CaM)/CaM‐dependent protein kinase II (CaMKII)/nuclear erythroid 2‐related factor 2 (Nrf2) axis, and 14‐3‐3ε was identified as a target of GA‐D. 14‐3‐3ε‐encoding gene (YWHAE) knockdown in hAMSCs reversed the activation of the CaM/CaMKII/Nrf2 signals to attenuate the GA‐D anti‐aging effect and increase senescence‐associated β‐galactosidase (SA‐β‐gal), p16 and p21 expression levels, including reactive oxygen species (ROS) production, thereby promoting cell cycle arrest and decreasing differentiation potential. YWHAE overexpression maintained or slightly enhanced the GA‐D anti‐aging effect. GA‐D prevented d‐galactose‐caused aging in mice by significantly increasing the total antioxidant capacity, as well as superoxide dismutase and glutathione peroxidase activity, and reducing the formation of malondialdehyde, advanced glycation end products, and receptor of advanced glycation end products. Consistent with the protective mechanism of GA‐D against hAMSCs senescence, GA‐D delayed the senescence of bone‐marrow mesenchymal stem cells in this aging model in vivo, reduced SA‐β‐gal and ROS production, alleviated cell cycle arrest, and enhanced cell viability and differentiation via regulating 14‐3‐3ε and CaM/CaMKII/Nrf2 axis. Therefore, GA‐D retards hAMSCs senescence by targeting 14‐3‐3ε to activate the CaM/CaMKII/Nrf2 signaling pathway. Furthermore, the in vivo GA‐D anti‐aging effect may involve the regulation of stem cell senescence via the same signal axis.     

2-fluoro-1-methylpyridinium p-toluene sulfonate: a new LC-MS/MS derivatization reagent for vitamin D metabolites

Vitamin D analysis by MS faces several analytical challenges, including inefficient ionization, nonspecific fragmentation, interferences from epimers, isomers, and isobars, as well as very low concentration levels. In this study, we used 2-fluoro-1-methylpyridinium (FMP) p-toluene sulfonate for derivatization of vitamin D3 metabolites to increase detection sensitivity and allow for full chromatographic separation of vitamin D isomers and epimers. UHPLC-MS/MS was used for measurement of five vitamin D3 metabolites in human serum. Compared with Amplifex and 4-phenyl-1,2,4-triazolin-3,5-dion, the FMP p-toluene sulfonate reaction required less time to be performed. The method was optimized and validated to ensure accuracy, precision, and reliability. In-house and commercial quality control samples were used to assure the quality of the results for 25-hydroxyvitamin D3. The method showed very good linearity and intraday and interday accuracy and precision; coefficients of determination (r²) ranged between 0.9977 and 0.9992, relative recovery from 95 to 111%, and coefficient of variation from 0.9 to 11.3. Stability tests showed that the extracted derivatized serum samples were stable for 24 h after storage at −20°C; 24,25-dihydroxyvitamin D3 and 1,25-dihydroxyvitamin D3-FMP derivatives were stable for 1 week at −80°C. The method was applied to samples of healthy individuals for quantitative determination of vitamin D3, the two epimers of 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3.     

Parallel expression of alternate forms of psbA2 gene provides evidence for the existence of a targeted D1 repair mechanism in Synechocystis sp. PCC 6803

The D1 protein of Photosystem II (PSII) is recognized as the main target of photoinhibitory damage and exhibits a high turnover rate due to its degradation and replacement during the PSII repair cycle. Damaged D1 is replaced by newly synthesized D1 and, although reasonable, there is no direct evidence for selective replacement of damaged D1. Instead, it remains possible that increased turnover of D1 subunits occurs in a non-selective manner due for example, to a general up-regulation of proteolytic activity triggered during damaging environmental conditions, such as high light. To determine if D1 degradation is targeted to damaged D1 or generalized to all D1, we developed a genetic system involving simultaneous dual expression of wild type and mutant versions of D1 protein. Dual D1 strains (nS345P:eWT and nD170A:eWT) expressed a wild type (WT) D1 from ectopic and a damage prone mutant (D1-S345P, D1-D170A) from native locus on the chromosome. Characterization of strains showed that all dual D1 strains restore WT like phenotype with high PSII activity. Higher PSII activity indicates increased population of PSII reaction centers with WT D1. Analysis of steady state levels of D1 in nS345P:eWT by immunoblot showed an accumulation of WT D1 only. But, in vivo pulse labeling confirmed the synthesis of both S345P (exists as iD1) and WT D1 in the dual strain. Expression of nS345P:eWT in FtsH2 knockout background showed accumulation of both iD1 and D1 proteins. This demonstrates that dual D1 strains express both forms of D1, yet only damage prone PSII complexes are selected for repair providing evidence that the D1 degradation process is targeted towards damaged PSII complexes. Since the N-terminus has been previously shown to be important for the degradation of damaged D1, the possibility that the highly conserved cysteine 18 residue situated in the N-terminal domain of D1 is involved in the targeted repair process was tested by examining site directed mutants of this and the other cysteines of the D1 protein. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: Keys to Produce Clean Energy.