In-situ construction of biomineralized cadmium sulfide-Rhodopseudomonas palustris hybrid system: Mechanism of synergistic light utilization.

Sulfide biomineralization is a microorganism-induced process for transforming the environmentally hazardous cadmium into useful resource utilization. This study successfully constructed cadmium sulfide nanoparticles-Rhodopseudomonas palustris (Bio-CdS NPs-R. palustris) hybrids. For the self-assembling hybrids, Bio-CdS NPs were treated as new artificial-antennas to enhance photosynthesis, especially under low light (LL). Bacterial physiological results of hybrids were significantly increased, particularly for cells under LL, with higher enhancement photon harvesting ability. The enhancement included the pigment contents, and the ratio of the peripheral light-harvesting complex Ⅱ (LH2) to light-harvesting Ⅰ (1.33 ± 0.01 under LL), leading to the improvements of light-harvesting, transfer, and antenna conversion efficiencies. Finally, the stimulated electron chain of hybrids improved bacterial metabolism with increased nicotinamide adenine dinucleotide (NADH, 174.5% under LL) and adenosine triphosphate (ATP, 41.1% under LL). Furthermore, the modified photosynthetic units were induced by the up-regulated expression of fixK, which was activated by reduced oxygen tension of the medium for hybrids. fixK up-regulated genes encoding pigments (crt, and bch) and complexes (puf, pucAB, and pucC), leading to improved light-harvesting and transfer, and transform ability. This study provides a comprehensive understanding of the solar energy utilization mechanism of in-situ semiconductor-phototrophic microbe hybrids, contributing to further theoretical insight into their practical application.

Stability and biomineralization of cadmium sulfide nanoparticles biosynthesized by the bacterium Rhodopseudomonas palustris under light.

Cadmium (Cd) pollution is regarded as a potent problem due to its hazard risks to the environment, making it crucial to be removed. Compared to the physicochemical techniques (e.g., adsorption, ion exchange, etc.), bioremediation is a promising alternative technology for Cd removal, due to its cost-effectiveness, and eco-friendliness. Among them, microbial-induced cadmium sulfide mineralization (Bio-CdS NPs) is a process of great significance for environmental protection. In this study, microbial cysteine desulfhydrase coupled with cysteine acted as a strategy for Bio-CdS NPs by Rhodopseudomonas palustris. The synthesis, activity, and stability of Bio-CdS NPs-R. palustris hybrid was explored under different light conditions. Results show that low light (LL) intensity could promote cysteine desulfhydrase activities to accelerate hybrid synthesis, and facilitated bacterial growth by the photo-induced electrons of Bio-CdS NPs. Additionally, the enhanced cysteine desulfhydrase activity effectively alleviated high Cd-stress. However, the hybrid rapidly dissolved under changed environmental factors, including light intensity and oxygen. The factors affecting the dissolution were ranked as follows: darkness/microaerobic ≈ darkness/aerobic < LL/microaerobic < high light (HL)/microaerobic < LL/aerobic < HL/aerobic. The research provides a deeper understanding of Bio-CdS NPs-bacteria hybird synthesis and its stability in Cd-polluted water, allowing advanced bioremediation treatment of heavy metal pollution in water.

Metabolism and pharmacokinetics of major polyphenol components in rat plasma after oral administration of total flavonoid tablet from Anemarrhenae Rhizoma.

Total flavonoid tablet from Anemarrhenae Rhizoma (Zhimu tablet), which was made of total polyphenol components extracted from the dried rhizome of Anemarrhena asphodeloides Bge. (Zhimu in Chinese), is a novel traditional Chinese medicine prescribed for the treatment of diabetes. Mangiferin (MF) and neomangiferin (NMF) are the two main components detected and determined in Zhimu tablet, accounting for 8.9% of the total weight of each tablet. In the present study, high performance liquid chromatography (HPLC) coupled with time-of-flight (TOF) tandem mass spectrometry (MS) was applied to characterize the metabolites of MF and NMF in rat plasmas collected at different time points after oral administration of Zhimu tablet at a dose of 3.63g/kg (corresponding to 270mg/kg MF). Accurate mass measurement was used to determine the elemental composition of metabolites and thus to confirm the proposed structures of identified metabolites. Time points of appearance of some metabolites, such as isomers, were also taken into account during the structure confirmation. A total of 21 potential metabolites were found in rat plasma at different time points, and the metabolic pathways in vivo were involved in hydrolysis, methylation, glucuronide conjugation, glycoside conjugation, sulphation, dehydration and isomerisation. Furthermore, a selective and accurate LC-MS assay method was developed and validated for the quantification of MF in plasma. Semi-quantification of main conjugated metabolites was also performed in order to describe the dynamic metabolism profiles of polyphenol components in Zhimu tablet. MF concentration in plasma reached 1.36±0.47µgmL(-1) about 5.0h after oral administration of Zhimu tablet, which showed a 3.24- and 4.91-fold increase in plasma maximum concentration and area under the concentration-time curve (AUC) from 0 to 24h of MF compared with those for rats administered with free MF, respectively. The results indicated that the pharmacokinetic processes and bioavailability of MF in rats would be affected by other components in Zhimu tablet.

Differential proteomic analysis of the anti-depressive effects of oleamide in a rat chronic mild stress model of depression.

Depression is a complex psychiatric disorder, and its etiology and pathophysiology are not completely understood. Depression involves changes in many biogenic amine, neuropeptide, and oxidative systems, as well as alterations in neuroendocrine function and immune-inflammatory pathways. Oleamide is a fatty amide which exhibits pharmacological effects leading to hypnosis, sedation, and anti-anxiety effects. In the present study, the chronic mild stress (CMS) model was used to investigate the antidepressant-like activity of oleamide. Rats were exposed to 10weeks of CMS or control conditions and were then subsequently treated with 2weeks of daily oleamide (5mg/kg, i.p.), fluoxetine (10mg/kg, i.p.), or vehicle. Protein extracts from the hippocampus were then collected, and hippocampal maps were generated by way of two-dimensional gel electrophoresis (2-DE). Altered proteins induced by CMS and oleamide were identified through mass spectrometry and database searches. Compared to the control group, the CMS rats exhibited significantly less body weight gain and decreased sucrose consumption. Treatment with oleamide caused a reversal of the CMS-induced deficit in sucrose consumption. In the proteomic analysis, 12 protein spots were selected and identified. CMS increased the levels of adenylate kinase isoenzyme 1 (AK1), nucleoside diphosphate kinase B (NDKB), histidine triad nucleotide-binding protein 1 (HINT1), acyl-protein thioesterase 2 (APT-2), and glutathione S-transferase A4 (GSTA4). Compared to the CMS samples, seven spots changed significantly following treatment with oleamide, including GSTA4, glutathione S-transferase A6 (GSTA6), GTP-binding nuclear protein Ran (Ran-GTP), ATP synthase subunit d, transgelin-3, small ubiquitin-related modifier 2 (SUMO2), and eukaryotic translation initiation factor 5A-1 (eIF5A1). Of these seven proteins, the level of eIF5A1 was up-regulated, whereas the remaining proteins were down-regulated. In conclusion, oleamide has antidepressant-like properties in the CMS rat model. The identification of proteins altered by CMS and oleamide treatment provides support for targeting these proteins in the development of novel therapies for depression.

Functional evolution of leptin of Ochotona curzoniae in adaptive thermogenesis driven by cold environmental stress.

BACKGROUND: Environmental stress can accelerate the directional selection and evolutionary rate of specific stress-response proteins to bring about new or altered functions, enhancing an organism's fitness to challenging environments. Plateau pika (Ochotona curzoniae), an endemic and keystone species on Qinghai-Tibetan Plateau, is a high hypoxia and low temperature tolerant mammal with high resting metabolic rate and non-shivering thermogenesis to cope in this harsh plateau environment. Leptin is a key hormone related to how these animals regulate energy homeostasis. Previous molecular evolutionary analysis helped to generate the hypothesis that adaptive evolution of plateau pika leptin may be driven by cold stress. METHODOLOGY/PRINCIPAL FINDINGS: To test the hypothesis, recombinant pika leptin was first purified. The thermogenic characteristics of C57BL/6J mice injected with pika leptin under warm (23±1°C) and cold (5±1°C) acclimation is investigated. Expression levels of genes regulating adaptive thermogenesis in brown adipose tissue and the hypothalamus are compared between pika leptin and human leptin treatment, suggesting that pika leptin has adaptively and functionally evolved. Our results show that pika leptin regulates energy homeostasis via reduced food intake and increased energy expenditure under both warm and cold conditions. Compared with human leptin, pika leptin demonstrates a superior induced capacity for adaptive thermogenesis, which is reflected in a more enhanced ß-oxidation, mitochondrial biogenesis and heat production. Moreover, leptin treatment combined with cold stimulation has a significant synergistic effect on adaptive thermogenesis, more so than is observed with a single cold exposure or single leptin treatment. CONCLUSIONS/SIGNIFICANCE: These findings support the hypothesis that cold stress has driven the functional evolution of plateau pika leptin as an ecological adaptation to the Qinghai-Tibetan Plateau.

Quantitative determination of acetylshikonin in macaque monkey blood by LC-ESI-MS/MS after precolumn derivatization with 2-mercaptoethanol and its application in pharmacokinetic study.

AIM: To develop and validate a novel precolumn derivatization method for the quantitative determination and pharmacokinetic application of acetylshikonin in macaque monkeys by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). METHODS: 2-Mercaptoethanol was added to the blood sample as the derivatization reagent. The derivatization reaction formed 1 major derivation product, which was well correlated with acetylshikonin. The acetylshikonin concentrations in the biological samples were calculated by quantitative determination of the major derivation product using LC-ESI- MS/MS. Separation was achieved using a C18 column (2 mm x 50 mm, 5 microm) at room temperature and a linear gradient elution with a mobile phase containing methanol (1.96% acetic acid) and 10% methanol in water (1.96% acetic acid and 10 mmol/L ammonium acetate) at a flow rate of 0.2 mL/min. In addition, the major derivative, named derivative III, was identified by UV spectra, MS, and the (1)H-NMR and (13)C-NMR spectra. RESULTS: Good linearity was obtained within the range of 5 and 2000 ng/mL (r>0.99 using a linear regression model with 1/x2 weighting) for acetylshikonin. The interday and intraday precisions were found to be less than 12.3%, with the exception of the lowest concentration, which was less than 17.2%. The interday and intraday accuracies, which were between -3% and 0.6%, were also observed. After the administration of acetylshikonin (80 mg/kg, po) in macaque monkeys, the pharmacokinetic parameters were obtained through the non-compartmental analysis, where the area under the concentration-time curve to the last measurable concentration, the terminal elimination halflife, and the mean residual time were 615.4+/-206.5 ng x dh/mL,12.3+/-1.6 h, and 10.2+/-0.7 h, respectively. CONCLUSION: The method was validated and applied to the quantitative determination and pharmacokinetic study of acetylshikonin in the blood samples of macaque monkeys.

Natural selection and adaptive evolution of leptin in the ochotona family driven by the cold environmental stress.

BACKGROUND: Environmental stress can accelerate the evolutionary rate of specific stress-response proteins and create new functions specialized for different environments, enhancing an organism's fitness to stressful environments. Pikas (order Lagomorpha), endemic, non-hibernating mammals in the modern Holarctic Region, live in cold regions at either high altitudes or high latitudes and have a maximum distribution of species diversification confined to the Qinghai-Tibet Plateau. Variations in energy metabolism are remarkable for them living in cold environments. Leptin, an adipocyte-derived hormone, plays important roles in energy homeostasis. METHODOLOGY/PRINCIPAL FINDINGS: To examine the extent of leptin variations within the Ochotona family, we cloned the entire coding sequence of pika leptin from 6 species in two regions (Qinghai-Tibet Plateau and Inner Mongolia steppe in China) and the leptin sequences of plateau pikas (O. curzonia) from different altitudes on Qinghai-Tibet Plateau. We carried out both DNA and amino acid sequence analyses in molecular evolution and compared modeled spatial structures. Our results show that positive selection (PS) acts on pika leptin, while nine PS sites located within the functionally significant segment 85-119 of leptin and one unique motif appeared only in pika lineages-the ATP synthase alpha and beta subunit signature site. To reveal the environmental factors affecting sequence evolution of pika leptin, relative rate test was performed in pikas from different altitudes. Stepwise multiple regression shows that temperature is significantly and negatively correlated with the rates of non-synonymous substitution (Ka) and amino acid substitution (Aa), whereas altitude does not significantly affect synonymous substitution (Ks), Ka and Aa. CONCLUSIONS/SIGNIFICANCE: Our findings support the viewpoint that adaptive evolution may occur in pika leptin, which may play important roles in pikas' ecological adaptation to extreme environmental stress. We speculate that cold, and probably not hypoxia, may be the primary environmental factor for driving adaptive evolution of pika leptin.