A longitudinal investigation of the cross-dimensional mediating role of negative life events between neuroticism and depressive symptoms in adolescents.

BACKGROUND: Neuroticism has been identified as a significant predictor for depression within the adolescent population However, few longitudinal studies have investigated this association and explored the mediation effect of the negative life events. This study aimed to examine the longitudinal association between neuroticism, negative life events, and depression in a large sample of Chinese adolescents. METHODS: Data on Five Factor Inventory-Neuroticism Subscale (FFI-N) was collected from 1150 participants aged 14-19 years old at baseline, and data on Adolescent Life Event Questionnaire (ALEQ) and Center of Epidemiological Study-Depression (CES-D) were collected both at baseline and 6-month follow-up. Multilevel modelings were used to analyze the longitudinal associations among neuroticism, negative life events and depression. RESULTS: Through a longitudinal study design, results from multilevel regression analyses indicated a direct correlation between increased levels of neuroticism and the aggregation of negative life events with the prediction of more severe depressive symptoms. Further, results of multilevel mediations suggested that the negative life events served to partially mediate the relationship between neuroticism and each dimension of depression. LIMITATIONS: The results cannot be used to make a clinical diagnosis. CONCLUSION: The current findings suggest the negative life events as a cross-dimensional mediator in the relationship between neuroticism and each dimension of depression. Regulating neuroticism levels and implementing strategies to coping stress derived from daily life events could be integral approaches to reducing the prevalence of depression within the adolescent population.

Enhancement of fermented sausage quality driven by mixed starter cultures: Elucidating the perspective of flavor profile and microbial communities.

The metabolic activities of microorganisms play a crucial role in the quality development of fermented sausage. This study investigated the effect of inoculation with different combinations of starter cultures (Lactiplantibacillus plantarum YR07, Latilactobacillus sakei L.48, Staphylococcus xylosus S.14, and Mammaliicoccus sciuri S.18) on the quality of sausages. Inoculation with mixed starter cultures promoted protein degradation to generate amino acids and the conversion to volatile compounds, which enhanced the flavor development in fermented sausages. The bacterial community analyses demonstrated that the inoculation of mixed starter cultures could inhibit the growth of spoilage and pathogenic bacteria, thereby reducing the total content of biogenic amines. The correlation analysis between the core bacteria and characteristic volatile compounds revealed that fermented sausages inoculated with Lactobacillus and coagulase negative staphylococci exhibited significant positive correlations with the majority of key characteristic volatile compounds. In four treatments, inoculation with L. plantarum YR07 and M. sciuri S.18 greatly promoted the formation of characteristic volatile compounds (3-hydroxy-2-butanone, hexanal, and 1- octen-3ol). Therefore, the combined inoculation of L. plantarum YR07 and M. sciuri S.18 is promising to enhance fermented sausage's flavor profile and safety.

Inhibition of fungal pathogenicity by targeting the H2S-synthesizing enzyme cystathionine ß-synthase.

The global emergence of antifungal resistance threatens the limited arsenal of available treatments and emphasizes the urgent need for alternative antifungal agents. Targeting fungal pathogenic functions is an appealing alternative therapeutic strategy. Here, we show that cystathionine ß-synthase (CBS), compared with cystathionine γ-lyase, is the major enzyme that synthesizes hydrogen sulfide in the pathogenic fungus Candida albicans. Deletion of CBS leads to deficiencies in resistance to oxidative stress, retarded cell growth, defective hyphal growth, and increased ß-glucan exposure, which, together, reduce the pathogenicity of C. albicans. By high-throughput screening, we identified protolichesterinic acid, a natural molecule obtained from a lichen, as an inhibitor of CBS that neutralizes the virulence of C. albicans and exhibits therapeutic efficacy in a murine candidiasis model. These findings support the application of CBS as a potential therapeutic target to fight fungal infections.

Ectopic overexpression of mulberry MnT5H2 enhances melatonin production and salt tolerance in tobacco.

Soil salinization severely inhibits plant growth and has become one of the major limiting factors for global agricultural production. Melatonin (N-acetyl-5-methoxytryptamine) plays an important role in regulating plant growth and development and in responding to abiotic stresses. Tryptamine-5-hydroxylase (T5H) is an enzyme essential for the biosynthesis of melatonin in plants. Previous studies have identified the gene MnT5H for melatonin synthesis in mulberry (Morus notabilis), but the role of this gene in response to salinity stress in mulberry is remain unclear. In this study, we ectopically overexpressed MnT5H2 in tobacco (Nicotiana tabacum L.) and treated it with NaCl solutions. Compared to wild-type (WT), melatonin content was significantly increased in the overexpression-MnT5H2 tobacco. Under salt stress, the expression of NtCAT, NtSOD, and NtERD10C and activity of catalase (CAT), peroxidase (POD), and the content of proline (Pro) in the transgenic lines were significantly higher than that in WT. The Malondialdehyde (MDA) content in transgenic tobacco was significantly lower than that of WT. Furthermore, transgenic tobacco seedlings exhibited faster growth in media with NaCl. This study reveals the changes of melatonin and related substance content in MnT5H2-overexpressing tobacco ultimately lead to improve the salt tolerance of transgenic tobacco, and also provides a new target gene for breeding plant resistance to salt.

Molecular Mechanisms Underlying the Biosynthesis of Melatonin and Its Isomer in Mulberry.

Mulberry (Morus alba L.) leaves and fruit are traditional Chinese medicinal materials with anti-inflammatory, immune regulatory, antiviral and anti-diabetic properties. Melatonin performs important roles in the regulation of circadian rhythms and immune activities. We detected, identified and quantitatively analyzed the melatonin contents in leaves and mature fruit from different mulberry varieties. Melatonin and three novel isoforms were found in the Morus plants. Therefore, we conducted an expression analysis of melatonin and its isomer biosynthetic genes and in vitro enzymatic synthesis of melatonin and its isomer to clarify their biosynthetic pathway in mulberry leaves. MaASMT4 and MaASMT20, belonging to class II of the ASMT gene family, were expressed selectively in mulberry leaves, and two recombinant proteins that they expressed catalyzed the conversion of N-acetylserotonin to melatonin and one of three isomers in vitro. Unlike the ASMTs of Arabidopsis and rice, members of the three ASMT gene families in mulberry can catalyze the conversion of N-acetylserotonin to melatonin. This study provides new insights into the molecular mechanisms underlying melatonin and its isomers biosynthesis and expands our knowledge of melatonin isomer biosynthesis.

Remote Generation of Magnon Schrödinger Cat State via Magnon-Photon Entanglement.

The magnon cat state represents a macroscopic quantum superposition of collective magnetic excitations of large number spins that not only provides fundamental tests of macroscopic quantum effects but also finds applications in quantum metrology and quantum computation. In particular, remote generation and manipulation of Schrödinger cat states are particularly interesting for the development of long-distance and large-scale quantum information processing. Here, we propose an approach to remotely prepare magnon even or odd cat states by performing local non-Gaussian operations on the optical mode that is entangled with the magnon mode through pulsed optomagnonic interaction. By evaluating key properties of the resulting cat states, we show that for experimentally feasible parameters, they are generated with both high fidelity and nonclassicality, as well as with a size large enough to be useful for quantum technologies. Furthermore, the effects of experimental imperfections such as the error of projective measurements and dark count when performing single-photon operations have been discussed, where the lifetime of the created magnon cat states is expected to be t∼1 µs.

Genome-wide identification and characterization of genes involved in melatonin biosynthesis in Morus notabilis (wild mulberry).

Melatonin is recognized as an important regulator for human health and widely distributed in many plant species, including mulberry (Morus L.). Previous studies suggested mulberry contains high melatonin content, but the molecular mechanisms underlying melatonin biosynthesis in mulberry remain unclear. Here, 37 genes involved in melatonin biosynthesis were identified in mulberry genome, including a tryptophan decarboxylase gene (MnTDC), seven tryptophan 5-hydroxylase genes (MnT5Hs), six serotonin N-acetyltransferase genes (MnSNATs), 20 N-acetylserotonin methyltransferase genes (MnASMTs) and three caffeic acid 3-O-methyltransferase genes (MnCOMTs). Expression analysis showed that MnTDC, MnT5H2, MnSNAT5, MnASMT12 and MnCOMT1 from these genes had highest expression levels within their corresponding families. In vitro enzymatic assays indicated that MnTDC, MnT5H2, MnSNAT5, MnASMT12 and MnCOMT1 play important roles in melatonin biosynthesis. Multiple different pathways for melatonin biosynthesis in mulberry were discovered. In addition, mulberry ASMT showed distinct roles with those of ASTMs in Arabidopsis and rice. The class I ASMT, MnASMT12, and the class III ASMT, MnASMT20, catalyzed the conversion of N-acetylserotonin to melatonin and serotonin to 5-methoxytryptamine. Furthermore, the class II ASMT, MnASMT16, only catalyzed the conversion of N-acetylserotonin to melatonin. This study improved our knowledge on melatonin biosynthesis in mulberry and expands the repertoire of melatonin biosynthesis pathways in plants.

Heterotrimeric G-protein γ subunits regulate ABA signaling in response to drought through interacting with PP2Cs and SnRK2s in mulberry (Morus alba L.).

ABA signaling plays a central role in regulating plants respond to drought. Although much progress has been made in understanding the functions of ABA signaling in drought response, very little information is available regarding woody plants. In this study, the components of ABA signaling pathway were identified in mulberry which has excellent adaptation to drought, including three PYLs, two PP2Cs, two SnRK2s, four ABFs, and an ABA responsive gene MaRD29B. The gene expression of ABA signaling components exhibited significant response to ABA and drought, and their roles in drought response were revealed using a transient transformation system in mulberry seedlings. We discovered the ABA signaling components, MaABI1/2 and MaSnRK2.1/2.4, could directly interact with G-protein γ subunits, MaGγ1 and MaGγ2, which indicated that G-protein γ subunits may mediate the signal crosstalk between G-proteins and ABA signaling. Transient activation assay in tobacco and RNAi silencing assay in mulberry further demonstrated that MaGγ1 and MaGγ2 regulated drought response by enhancing ABA signaling. This study expands the repertoire of ABA signaling controlling drought responses in plants and provides the direct evidence about the crosstalk between ABA signaling and G-proteins for the first time.

Efflux pump-mediated resistance to antifungal compounds can be prevented by conjugation with triphenylphosphonium cation.

Antifungal resistance due to upregulation of efflux pumps is prevalent in clinical Candida isolates. Potential efflux pump substrates (PEPSs), which are active against strains deficient in efflux pumps but inactive against wild-type strains, are usually missed in routine antifungal screening. Here we present a method for identification of PEPSs, and show that conjugation with mitochondria-targeting triphenylphosphonium cation (TPP+) can enhance or restore the compounds' antifungal activity. The screening method involves co-culturing a wild-type C. albicans strain and a Cdr efflux pump-deficient strain, labelled with different fluorescent proteins. We identify several PEPSs from a library of natural terpenes, and restore their antifungal activity against wild-type and azole-resistant C. albicans by conjugation with TPP+. The most active conjugate (IS-2-Pi-TPP) kills C. albicans cells, prevents biofilm formation and eliminates preformed biofilms, without inducing significant resistance. The antifungal activity is accompanied by mitochondrial dysfunction and increased levels of intracellular reactive oxygen species. In addition, IS-2-Pi-TPP is effective against C. albicans in a mouse model of skin infection.

Chiloscyphenol A derived from Chinese liverworts exerts fungicidal action by eliciting both mitochondrial dysfunction and plasma membrane destruction.

This study aimed to characterize the antifungal effects of chiloscyphenol A (CA), a natural small molecule isolated from Chinese liverworts, and investigate its mode of action. CA was effective against five tested Candida species with a minimal inhibitory concentration (MIC) of 8-32 µg/ml and exhibited fungicidal activity against Candida albicans in both the planktonic state and mature biofilms. The in vivo study using Caenorhabditis elegans showed that CA prolonged the survival of C. albicans infected worms. Further investigations revealed that CA resulted in mitochondrial dysfunction as indicated by mtΔψ hyperpolarization, increased ATP production and intracellular ROS accumulation, and aggregated distribution of Tom70. In addition, CA caused perturbation of the cell membrane and increased membrane permeability, as demonstrated by specific staining and confocal microscopic and transmission electron microscopy (TEM) observations and by calcein-leakage measurements. This conclusion was further confirmed by the decreased cell size of CA-treated cells via three-dimensional contour-plot analysis using flow cytometry. Taken together, these results suggest that CA exerts fungicidal activity by eliciting both mitochondrial dysfunction and plasma membrane destruction in C. albicans. The elucidated mechanism supports the potential application of CA against clinical fungal infections.

Floricolin C elicits intracellular reactive oxygen species accumulation and disrupts mitochondria to exert fungicidal action.

Candida albicans, one of the most prevalent fungal pathogens, causes severe mucosal and invasive infections in predisposed individuals. The rise of fungal infection and drug resistance demands the development of novel antifungal agents. In this study, we observed that floricolin C (FC), a p-terphenyl pigment from an endolichenic fungus, killed C. albicans cells in the planktonic state or within biofilms through reactive oxygen species (ROS) accumulation. Further tests revealed that FC could directly damage the mitochondria to cause ROS accumulation. In addition, FC can quench thiol-based agents through a Michael reaction involving the α,ß-unsaturated carbonyl group, whose effect may chelate intracellular thiol-based molecules or proteins in C. albicans, resulting in an imbalance in redox homeostasis. Increased ROS generation led to mitochondrial dysfunction, nuclear dispersion and consequently cell death. We further demonstrated that FC could prevent biofilm formation of other Candida species and eradicate their pre-formed biofilms. An in vivo study demonstrated that FC prolonged the survival of C. albicans-infected Caenorhabditis elegans. Taken together, our study provides the basis for the application of FC to combat Candida infections.

Weak Iaser effects on the biocompatibiIity of chitosan and Nafion as impIantabIe gIucose sensor outer materiaIs / 中国组织工程研究

BACKGROUND: The biocompatibility of chitosan and Nafion can be improved by external factors. OBJECTIVE: To explore the effect of different weak laser irradiations (red, blue, green) on biocompatibility of porous chitosan membrane and the Nafion membrane. METHODS: (1) Porous chitosan membrane test: Forty-eight Sprague-Dawley rats were randomized into red, green, blue light groups (n=16 per group). Porous chitosan membranes (two membranes at each side) were implanted into the bilateral subcutaneous tissue of the rat back with the spine as the axis of symmetry, and then the four implanted membranes in each rat were irradiated by red light for 0, 2, 4, 6 minutes respectively. The irradiation lasted until sample collection at 7, 14, 28 and 56 days after implantation, and the samples were used for histological analysis. The same procedures were done in the blue and green light groups. (2) Nafion membrane test: Twenty-four Sprague-Dawley rats were randomized into red, blue and green light groups (n=8 per group). Nafion membranes (two membranes at each side) were implanted into the bilateral subcutaneous tissue of the rat back with the spine as the axis of symmetry, and then the four implanted membranes in each rat were irradiated by red light for 0, 2, 4, 6 minutes respectively. The irradiation lasted until sample collection at 7 and 14 days after implantation, and the samples were used for histological analysis. The same procedures were done in the blue and green light groups. RESULTS AND CONCLUSION: The content of red blood cells in blood vessels and vascular density around the membrane materials (porous chitosan membranes and Nafion membranes) increased after irradiated by red light (especially at 7 days after implantation); the red light had less influence on the inflammatory response and fibrous capsule thickness around the two kinds of membranes. The inflammatory cells percentage around the membrane materials irradiated by green light for 4 minutes was significantly reduced, and the blue light had less influence on inflammatory responses; blue and green lights showed effects on the fibrous capsule thickness and vascular density around the membrane materials, but the effect was not obvious. Thus, to a certain extent, weak lasers can improve the biocompatibility of PCSM and Nafion membrane.

Solasodine-3-O-ß-d-glucopyranoside is hydrolyzed by a membrane glucosidase into active molecule solasodine against Candida albicans.

Antifungal activity of some natural molecules can be abated or blocked by efflux pumps in Candida albicans, which restricts the discovery of potential antifungal agents. Here we found that the steroidal alkaloid solasodine is active against C. albicans efflux pump-deficient strains but inert towards the wild type. However, the glucosylated solasodine-3-O-ß-d-glucopyranoside exhibits antifungal activity towards the wild type strain. Further investigation revealed that the entry of solasodine into C. albicans cells is blocked by efflux pumps. Glucosylation provides an alternative access not disturbed by efflux pumps. Once inside cells, the carried glucosylated solasodine is cleaved into the active molecule solasodine by the glucosidase, which is located in cytoplasm membrane and exhibits selective activity against hydrolyzing glucosyl natural products but not against other monosaccharide-substituted products. This glucosidase is not encoded by orf19.4031, considered homologous to steryl-ß-glucosidase encoded by the gene EGH1 in Saccharomyces cerevisiae. Our study reveals that glucosylation is an alternative approach for introducing potential antifungal activity into C. albicans cells and overcoming the drug-resistance resulting from hyperactivation of efflux pumps.

Solasodine-3-O-ß-d-glucopyranoside kills Candida albicans by disrupting the intracellular vacuole.

The increasing incidence of fungal infections and emergence of drug resistance underlie the constant search for new antifungal agents and exploration of their modes of action. The present study aimed to investigate the antifungal mechanisms of solasodine-3-O-ß-d-glucopyranoside (SG) isolated from the medicinal plant Solanum nigrum L. In vitro, SG displayed potent fungicidal activity against both azole-sensitive and azole-resistant Candida albicans strains in Spider medium with its MICs of 32 µg/ml. Analysis of structure and bioactivity revealed that both the glucosyl residue and NH group were required for SG activity. Quantum dot (QD) assays demonstrated that the glucosyl moiety was critical for SG uptake into Candida cells, as further confirmed by glucose rescue experiments. Measurement of the fluorescence intensity of 2',7'-dichlorofluorescin diacetate (DCFHDA) by flow cytometry indicated that SG even at 64 µg/ml just caused a moderate increase of reactive oxygen species (ROS) generation by 58% in C. albicans cells. Observation of vacuole staining by confocal microscopy demonstrated that SG alkalized the intracellular vacuole of C. albicans and caused hyper-permeability of the vacuole membrane, resulting in cell death. These results support the potential application of SG in fighting fungal infections and reveal a novel fungicidal mechanism.

Biatriosporin D displays anti-virulence activity through decreasing the intracellular cAMP levels.

Candidiasis has long been a serious human health problem, and novel antifungal approaches are greatly needed. During both superficial and systemic infection, C. albicans relies on a battery of virulence factors, such as adherence, filamentation, and biofilm formation. In this study, we found that a small phenolic compound, Biatriosporin D (BD), isolated from an endolichenic fungus, Biatriospora sp., displayed anti-virulence activity by inhibiting adhesion, hyphal morphogenesis and biofilm formation of C. albicans. Of note is the high efficacy of BD in preventing filamentation with a much lower dose than its MIC value. Furthermore, BD prolonged the survival of worms infected by C. albicans in vivo. Quantitative real-time PCR analysis, exogenous cAMP rescue experiments and intracellular cAMP measurements revealed that BD regulates the Ras1-cAMP-Efg1 pathway by reducing cAMP levels to inhibit the hyphal formation. Further investigation showed that BD could upregulate Dpp3 to synthesize much more farnesol, which could inhibit the activity of Cdc35 and reduce the generation of cAMP. Taken together, these findings indicate that BD stimulates the expression of Dpp3 to synthesize more farnesol that directly inhibits the Cdc35 activity, reducing intracellular cAMP and thereby disrupting the morphologic transition and attenuating the virulence of C. albicans. Our study uncovers the underlying mechanism of BD as a prodrug in fighting against pathogenic C. albicans and provides a potential application of BD in fighting clinically relevant fungal infections by targeting fungal virulence.

Quinone derivatives isolated from the endolichenic fungus Phialocephala fortinii are Mdr1 modulators that combat azole resistance in Candida albicans.

One of the main azole-resistance mechanisms in Candida pathogens is the upregulation of drug efflux pumps, which compromises the efficacy of azoles and results in treatment failure. The combination of azole-antifungal agents with efflux pump inhibitors represents a promising strategy to combat fungal infection. High-throughput screening of 150 extracts obtained from endolichenic fungal cultures led to the discovery that the extract of Phialocephala fortinii exhibits potent activity for the reversal of azole resistance. From P. fortinii cultures, a total of 15 quinone derivatives, comprising 11 new derivatives and 4 known compounds, were obtained. Among these compounds, palmarumycin P3 (3) and phialocephalarin B (8) specifically modulate the expression of MDR1 to inhibit the activity of drug efflux pumps and therefore reverse azole resistance. The present study revealed Mdr1 targeting as an alternative mechanism for the discovery of new agents to fight antifungal drug resistance.

Als1 and Als3 regulate the intracellular uptake of copper ions when Candida albicans biofilms are exposed to metallic copper surfaces.

Copper surfaces possess efficient antimicrobial effect. Here, we reported that copper surfaces could inactivate Candida albicans biofilms within 40 min. The intracellular reactive oxygen species in C. albicans biofilms were immediately stimulated during the contact of copper surfaces, which might be an important factor for killing the mature biofilms. Copper release assay demonstrated that the copper ions automatically released from the surface of 1 mm thick copper coupons with over 99.9% purity are not the key determinant for the copper-mediated killing action. The susceptibility test to copper surfaces by using C. albicans mutant strains, which were involved in efflux pumps, adhesins, biofilms formation or osmotic stress response showed that als1/als1 and als3/als3 displayed higher resistance to the copper surface contact than other mutants did. The intracellular concentration of copper ions was lower in als1/als1 and als3/als3 than that in wild-type strain. Transcriptional analysis revealed that the expression of copper transporter-related gene, CRP1, was significantly increased in als1/als1, als3/als3, suggesting a potential role of ALS1 and ALS3 in absorbing ions by regulating the expression of CRP1 This study provides a potential application in treating pathogenic fungi by using copper surfaces and uncovers the roles of ALS1 and ALS3 in absorbing copper ions for C. albicans.

Trapping toxins within lipid droplets is a resistance mechanism in fungi.

Lipid droplets (LDs) act as intracellular storage organelles in most types of cells and are principally involved in energy homeostasis and lipid metabolism. However, the role of LDs in resistance to toxins in fungi remains largely unknown. Here, we show that the trapping of endogenous toxins by LDs is a self-resistance mechanism in the toxin producer, while absorbing external lipophilic toxins is a resistance mechanism in the toxin recipient that acts to quench the production of reactive oxygen species. We found that an endolichenic fungus that generates phototoxic perylenequinones (PQs) trapped the PQs inside LDs. Using a model that incorporates the fungicidal action of hypocrellin A (HA), a PQ derivative, we showed that yeast cells escaped killing by trapping toxins inside LDs. Furthermore, LD-deficient mutants were hypersusceptible to HA-mediated phototoxins and other fungicides. Our study identified a previously unrecognised function of LDs in fungi that has implications for our understanding of environmental adaptation strategies for fungi and antifungal drug discovery.

Cornel iridoid glycoside reduces infarct size measured by magnetic resonance imaging and improves neurological function after focal cerebral ischemia in rats.

OBJECTIVE: To investigate the effect of cornel iridoid glycoside (CIG), an ingredient extracted from traditional Chinese herb Cornus offificinalis, on neurological function and infarct size in rats as measured by magnetic resonance imaging (MRI) after ischemic stroke. METHODS: Sprague-Dawley rats were divided into three group: control (n=11), model (n=20) and CIG (n=16) groups. Rats in the model and CIG groups underwent 90-min middle cerebral artery occlusion (MCAO) followed by reperfusion. Their neurological defect was measured by using a modified neurological severity score (mNSS). T2-weighted MRI (T2-MRI) of the brain was performed in vivo from 2 to 28 days after MCAO. The infarct volume in the brain was also measured using 2,3,5-triphenyltetrazolium chloride (TTC) staining 28 days after stroke. RESULTS: CIG, 60 mg/(kg day), administered by oral gavage starting from 6 h after the onset of MCAO improved neurological function at 7, 14, 21, and 28 days post occlusion (P<0.05 orP<0.01) and decreased mortality. The infarct volumes computed from the T2-MR images were reduced in the CIG-treated group compared with the model group at 7, 14 and 28 days after MCAO (P<0.05); and the rate at which the infarct volume decreased from 2 to 28 days was higher in the CIG-treated group than that in the model group (P<0.05). The infarct volumes measured by TTC staining were also decreased 28 days after stroke (P<0.05). CONCLUSION: CIG treatment, starting from 6 h after MCAO, reduced infarct size in the brain as measured by MRI and improved neurological function 2-28 days after focal cerebral ischemia in rats, suggesting that CIG could be a clinical application in improving stroke treatment.