Structural basis for the tethered peptide activation of adhesion GPCRs.

Adhesion G-protein-coupled receptors (aGPCRs) are important for organogenesis, neurodevelopment, reproduction and other processes1-6. Many aGPCRs are activated by a conserved internal (tethered) agonist sequence known as the Stachel sequence7-12. Here, we report the cryogenic electron microscopy (cryo-EM) structures of two aGPCRs in complex with Gs: GPR133 and GPR114. The structures indicate that the Stachel sequences of both receptors assume an α-helical-bulge-ß-sheet structure and insert into a binding site formed by the transmembrane domain (TMD). A hydrophobic interaction motif (HIM) within the Stachel sequence mediates most of the intramolecular interactions with the TMD. Combined with the cryo-EM structures, biochemical characterization of the HIM motif provides insight into the cross-reactivity and selectivity of the Stachel sequences. Two interconnected mechanisms, the sensing of Stachel sequences by the conserved 'toggle switch' W6.53 and the constitution of a hydrogen-bond network formed by Q7.49/Y7.49 and the P6.47/V6.47φφG6.50 motif (φ indicates a hydrophobic residue), are important in Stachel sequence-mediated receptor activation and Gs coupling. Notably, this network stabilizes kink formation in TM helices 6 and 7 (TM6 and TM7, respectively). A common Gs-binding interface is observed between the two aGPCRs, and GPR114 has an extended TM7 that forms unique interactions with Gs. Our structures reveal the detailed mechanisms of aGPCR activation by Stachel sequences and their Gs coupling.

Single hormone or synthetic agonist induces Gs/Gi coupling selectivity of EP receptors via distinct binding modes and propagating paths.

To accomplish concerted physiological reactions, nature has diversified functions of a single hormone at at least two primary levels: 1) Different receptors recognize the same hormone, and 2) different cellular effectors couple to the same hormone-receptor pair [R.P. Xiao, Sci STKE 2001, re15 (2001); L. Hein, J. D. Altman, B.K. Kobilka, Nature 402, 181-184 (1999); Y. Daaka, L. M. Luttrell, R. J. Lefkowitz, Nature 390, 88-91 (1997)]. Not only these questions lie in the heart of hormone actions and receptor signaling but also dissecting mechanisms underlying these questions could offer therapeutic routes for refractory diseases, such as kidney injury (KI) or X-linked nephrogenic diabetes insipidus (NDI). Here, we identified that Gs-biased signaling, but not Gi activation downstream of EP4, showed beneficial effects for both KI and NDI treatments. Notably, by solving Cryo-electron microscope (cryo-EM) structures of EP3-Gi, EP4-Gs, and EP4-Gi in complex with endogenous prostaglandin E2 (PGE2)or two synthetic agonists and comparing with PGE2-EP2-Gs structures, we found that unique primary sequences of prostaglandin E2 receptor (EP) receptors and distinct conformational states of the EP4 ligand pocket govern the Gs/Gi transducer coupling selectivity through different structural propagation paths, especially via TM6 and TM7, to generate selective cytoplasmic structural features. In particular, the orientation of the PGE2 ω-chain and two distinct pockets encompassing agonist L902688 of EP4 were differentiated by their Gs/Gi coupling ability. Further, we identified common and distinct features of cytoplasmic side of EP receptors for Gs/Gi coupling and provide a structural basis for selective and biased agonist design of EP4 with therapeutic potential.

Functional characterization of genes related to triterpene and flavonoid biosynthesis in Cyclocarya paliurus.

MAIN CONCLUSION: The oxidosqualene cyclases (OSCs) generating triterpenoid skeletons in Cyclocarya paliurus were identified for the first time, and two uridine diphosphate (UDP)-glycosyltransferases (UGTs) catalyzing the glycosylation of flavonoids were characterized. Cyclocarya paliurus, a native rare dicotyledonous plant in China, contains an abundance of triterpenoid saponins and flavonoid glycosides that exhibit valuable pharmaceutical effects in preventing hypertension, hyperlipidemia, and diabetes. However, the molecular mechanism explaining the biosynthesis of triterpenoid saponin and flavonoid glycoside in C. paliurus remains unclear. In this study, the triterpene content in different tissues and the expression pattern of genes encoding the key enzymes associated with triterpenoid saponin and flavonoid glycoside biosynthesis were studied using transcriptome and metabolome analysis. The eight upstream oxidosqualene cyclases (OSCs) involved in triterpenoid saponin biosynthesis were functionally characterized, among them CpalOSC6 catalyzed 2,3;22,23-dioxidosqualene to form 3-epicabraleadiol; CpalOSC8 cyclized 2,3-oxidosqualene to generate dammarenediol-II; CpalOSC2 and CpalOSC3 produced ß-amyrin and CpalOSC4 produced cycloartenol, while CpalOSC2-CpalOSC5, CpalOSC7, and CpalOSC8 all produced lanosterol. However, no catalytic product was detected for CpalOSC1. Moreover, two downstream flavonoid uridine diphosphate (UDP)-glycosyltransferases (UGTs) (CpalUGT015 and CpalUGT100) that catalyze the last step of flavonoid glycoside biosynthesis were functionally elucidated. These results uncovered the key genes involved in the biosynthesis of triterpenoid saponins and flavonoid glycosides in C. paliurus that could be applied to produce flavonoid glycosides and key triterpenoid saponins in the future via a synthetic strategy.

Development of a stable genetic transformation system in Erigeron breviscapus: a case study with EbYUC2 in relation to leaf number and flowering time.

MAIN CONCLUSION: A stable genetic transformation system for Erigeron breviscapus was developed. We cloned the EbYUC2 gene and genetically transformed it into Arabidopsis thaliana and E. breviscapus. The leaf number, YUC2 gene expression, and the endogenous auxin content in transgenic plants were significantly increased. Erigeron breviscapus is a prescription drug for the clinical treatment of cardiovascular and cerebrovascular diseases. The rosette leaves have the highest content of the major active compound scutellarin and are an important component in the yield of E. breviscapus. However, little is known about the genes related to the leaf number and flowering time of E. breviscapus. In our previous study, we identified three candidate genes related to the leaf number and flowering of E. breviscapus by combining resequencing data and genome-wide association study (GWAS). However, their specific functions remain to be characterized. In this study, we cloned and transformed the previously identified full-length EbYUC2 gene into Arabidopsis thaliana, developed the first stable genetic transformation system for E. breviscapus, and obtained the transgenic plants overexpressing EbYUC2. Compared with wild-type plants, the transgenic plants showed a significant increase in the number of leaves, which was correlated with the increased expression of EbYUC2. Consistently, the endogenous auxin content, particularly indole-3-acetic acid, in transgenic plants was also significantly increased. These results suggest that EbYUC2 may control the leaf number by regulating auxin biosynthesis, thereby laying a foundation for revealing the molecular mechanism governing the leaf number and flowering time of E. breviscapus.

Risk-stratified screening and colorectal cancer incidence and mortality: A retrospective study from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

OBJECTIVE: To determine whether risk stratification can optimize the benefits of flexible sigmoidoscopy (FSG) screening. METHODS: The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial was conducted from 1993 to 2001 in the United States. A colorectal cancer (CRC) risk stratification tool was developed in the control arm (n = 64,207) from the PLCO cohort and validated in the UK Biobank (n = 270,726). PLCO participants (n = 130,021) were classified into low-, medium-, and high-risk groups. Cumulative incidence and mortality were estimated using the Kaplan-Meier method. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between screening and CRC incidence and mortality. RESULTS: The CRC risk stratification tool was based on age, gender, body mass index, smoking status, family history of CRC, diabetes, regular use of aspirin, and CRC screening history. Compared with the control arm, FSG screening was significantly associated with a reduction in mortality in both the medium-risk (HR = 0.76, 95% CI = 0.63-0.92) and high-risk groups (0.58, 0.46-0.73), but not in the low-risk group (0.85, 0.61-1.19). FSG screening also reduced distal CRC incidence and mortality in the medium-risk and high-risk groups. Furthermore, it was associated with a reduction in incidence (0.74, 0.59-0.92) and mortality (0.59, 0.40-0.87) of proximal colon cancer in the high-risk group. CONCLUSIONS: FSG screening yielded more benefits for the high-risk group than for the low-risk and medium-risk groups, supporting the development of a risk-stratified CRC screening strategy.

Intracellular Protein Adsorption Behavior and Biological Effects of Polystyrene Nanoplastics in THP-1 Cells.

Micro(nano)plastics (MNPs) are emerging pollutants that can adsorb pollutants in the environment and biological molecules and ultimately affect human health. However, the aspects of adsorption of intracellular proteins onto MNPs and its biological effects in cells have not been investigated to date. The present study revealed that 100 nm polystyrene nanoplastics (NPs) could be internalized by THP-1 cells and specifically adsorbed intracellular proteins. In total, 773 proteins adsorbed onto NPs with high reliability were identified using the proteomics approach and analyzed via bioinformatics to predict the route and distribution of NPs following cellular internalization. The representative proteins identified via the Kyoto Encyclopedia of Genes and Genomes pathway analysis were further investigated to characterize protein adsorption onto NPs and its biological effects. The analysis revealed that NPs affect glycolysis through pyruvate kinase M (PKM) adsorption, trigger the unfolded protein response through the adsorption of ribophorin 1 (RPN1) and heat shock 70 protein 8 (HSPA8), and are chiefly internalized into cells through clathrin-mediated endocytosis with concomitant clathrin heavy chain (CLTC) adsorption. Therefore, this work provides new insights and research strategies for the study of the biological effects caused by NPs.

Association between metabolic syndrome and kidney cancer risk: a prospective cohort study.

BACKGROUND: Kidney cancer has become known as a metabolic disease. However, there is limited evidence linking metabolic syndrome (MetS) with kidney cancer risk. This study aimed to investigate the association between MetS and its components and the risk of kidney cancer. METHODS: UK Biobank data was used in this study. MetS was defined as having three or more metabolic abnormalities, while pre-MetS was defined as the presence of one or two metabolic abnormalities. Hazard ratios (HRs) and 95% confidence intervals (CIs) for kidney cancer risk by MetS category were calculated using multivariable Cox proportional hazards models. Subgroup analyses were conducted for age, sex, BMI, smoking status and drinking status. The joint effects of MetS and genetic factors on kidney cancer risk were also analyzed. RESULTS: This study included 355,678 participants without cancer at recruitment. During a median follow-up of 11 years, 1203 participants developed kidney cancer. Compared to the metabolically healthy group, participants with pre-MetS (HR= 1.36, 95% CI: 1.06-1.74) or MetS (HR= 1. 70, 95% CI: 1.30-2.23) had a significantly greater risk of kidney cancer. This risk increased with the increasing number of MetS components (P for trend < 0.001). The combination of hypertension, dyslipidemia and central obesity contributed to the highest risk of kidney cancer (HR= 3.03, 95% CI: 1.91-4.80). Compared with participants with non-MetS and low genetic risk, those with MetS and high genetic risk had the highest risk of kidney cancer (HR= 1. 74, 95% CI: 1.41-2.14). CONCLUSIONS: Both pre-MetS and MetS status were positively associated with kidney cancer risk. The risk associated with kidney cancer varied by combinations of MetS components. These findings may offer novel perspectives on the aetiology of kidney cancer and assist in designing primary prevention strategies.

Effects of loose combined cutting seton surgery on wound healing and pain in patients with high anal fistula: A meta-analysis.

A meta-analysis was conducted to evaluate the effects of loose combined cutting seton surgery on wound healing and pain in patients with high anal fistula, aiming to provide evidence-based medical evidence for surgical method selection for these patients. A comprehensive computerized search of PubMed, Cochrane Library, EMBASE, Wanfang and China National Knowledge Infrastructure databases was conducted to collect all relevant studies published up to November 2023, evaluating the effects of loose combined cutting seton surgery in treating patients with high anal fistulas. Two researchers independently screened, extracted data, and assessed the quality of the identified studies. RevMan 5.4 software was employed for data analysis. Overall, 16 articles were included, comprising 1124 patients, with 567 undergoing loose combined cutting seton surgery and 557 undergoing simple cutting seton surgery. The analysis revealed patients undergoing loose combined cutting seton surgery had a higher rate of postoperative wound healing (97.44% vs. 81.69%, odds ratio [OR]: 7.49, 95% confidence interval [CI]: 4.29-13.10, p < 0.00001), shorter wound healing time (standardized mean differences [SMD]: -1.48, 95% CI: -1.89 to -1.08, p < 0.00001), lower postoperative wound pain scores (SMD: -2.51, 95% CI: -3.51 to -1.51, p < 0.00001), and a lower rate of postoperative complications (3.43% vs. 20.83%, OR: 0.13, 95% CI: 0.05-0.31, p < 0.00001). The current evidence suggests that compared to simple cutting seton surgery, loose combined cutting seton surgery in treating high anal fistulas can promote postoperative wound healing, shorten wound healing time, alleviate pain, and reduce the incidence of postoperative complications, making it a worthy clinical practice for widespread application.

Structural insight into the selective agonist ST1936 binding of serotonin receptor 5-HT6.

The serotonin receptor 5-HT6R is an important G-protein-coupled receptor (GPCR) that involved in essential functions within the central and peripheral nervous systems and is linked to various psychiatric disorders. Selective activation of 5-HT6R promotes neural stem cell regeneration activity. As a 5-HT6R selective agonist, 2-(5 chloro-2-methyl-1H-indol-3-yl)-N, N-dimethylethanolamine (ST1936) has been widely used to investigate the functions of the 5-HT6R. The molecular mechanism of how ST1936 is recognized by 5-HT6R and how it effectively couples with Gs remain unclear. Here, we reconstituted the ST1936-5-HT6R-Gs complex in vitro and solved its cryo-electron microscopy structure at 3.1 Å resolution. Further structural analysis and mutational studies facilitated us to identify the residues of the Y3107.43 and "toggle switch" W2816.48 of the 5-HT6R contributed to the higher efficacy of ST1936 compared with 5-HT. By uncovering the structural foundation of how 5-HT6R specifically recognizes agonists and elucidating the molecular process of G protein activation, our discoveries offer valuable insights and pave the way for the development of promising 5-HT6R agonists.

TREM-1 triggers necroptosis of macrophages through mTOR-dependent mitochondrial fission during acute lung injury.

BACKGROUND: Necroptosis of macrophages is a necessary element in reinforcing intrapulmonary inflammation during acute lung injury (ALI). However, the molecular mechanism that sparks macrophage necroptosis is still unclear. Triggering receptor expressed on myeloid cells-1 (TREM-1) is a pattern recognition receptor expressed broadly on monocytes/macrophages. The influence of TREM-1 on the destiny of macrophages in ALI requires further investigation. METHODS: TREM-1 decoy receptor LR12 was used to evaluate whether the TREM-1 activation induced necroptosis of macrophages in lipopolysaccharide (LPS)-induced ALI in mice. Then we used an agonist anti-TREM-1 Ab (Mab1187) to activate TREM-1 in vitro. Macrophages were treated with GSK872 (a RIPK3 inhibitor), Mdivi-1 (a DRP1 inhibitor), or Rapamycin (an mTOR inhibitor) to investigate whether TREM-1 could induce necroptosis in macrophages, and the mechanism of this process. RESULTS: We first observed that the blockade of TREM-1 attenuated alveolar macrophage (AlvMs) necroptosis in mice with LPS-induced ALI. In vitro, TREM-1 activation induced necroptosis of macrophages. mTOR has been previously linked to macrophage polarization and migration. We discovered that mTOR had a previously unrecognized function in modulating TREM-1-mediated mitochondrial fission, mitophagy, and necroptosis. Moreover, TREM-1 activation promoted DRP1Ser616 phosphorylation through mTOR signaling, which in turn caused surplus mitochondrial fission-mediated necroptosis of macrophages, consequently exacerbating ALI. CONCLUSION: In this study, we reported that TREM-1 acted as a necroptotic stimulus of AlvMs, fueling inflammation and aggravating ALI. We also provided compelling evidence suggesting that mTOR-dependent mitochondrial fission is the underpinning of TREM-1-triggered necroptosis and inflammation. Therefore, regulation of necroptosis by targeting TREM-1 may provide a new therapeutic target for ALI in the future.

Development of a modified ABC method among Helicobacter pylori infected but serum pepsinogen test-negative individuals.

BACKGROUND: Although the ABC method for gastric cancer (GC) screening has been widely adopted in Japan, it may not be suitable for other countries due to population heterogeneity and different tumor histology. We aim to develop a modified ABC method to improve GC screening performance, especially among Helicobacter pylori (Hp) infected but serum pepsinogen (sPG) test-negative individuals. METHODS: A total of 4745 participants were recruited from Tianjin, China, and were classified into four groups by combined assay for Hp infection and sPG concentrations: Group A (Hp [-], PG [-]), Group B (Hp [+], PG [-]), Group C (Hp [+], PG [+]), and Group D (Hp [-], PG [+]). We used receiver-operating characteristic (ROC) curves analysis and minimum p value method to determine the optimal cutoff point for PG II in Group B. We performed logistic regressions to examine the risk of GC across different subgroups. In addition to the derivation set, the performance of the modified ABC method was also evaluated in an external set involving 16,292 participants from Liaoning, China. RESULTS: In the modified ABC method, we further classified Group B as low-risk (Group B1) and high-risk subgroups (Group B2) using optimal sPG II cutoff point (20.0 ng/mL) by ROC curves analysis and minimum p value method. Compared with Group B1, Group B2 had a significantly higher risk of GC (adjusted OR = 2.54, 95% CI = 1.94-3.33). The modified ABC method showed good discrimination for GC (AUC = 0.61, 95% CI = 0.59-0.63) and improved risk reclassification (NRI = 0.11, p < .01). Similar results were observed in the validation dataset. CONCLUSIONS: The modified ABC method can effectively identify high-risk population for GC among Hp-infected but sPG test-negative participants in China.

Cadmium facilitates the formation of large lipid droplets via PLCß2-DAG-DGKε-PA signal pathway in Leydig cells.

Cadmium (Cd) exposure damages the reproductive system. Lipid droplets (LDs) play an important role in steroid-producing cells to provide raw material for steroid hormone. We have found that the LDs of Leydig cells exposed to Cd are bigger than those of normal cells, but the effects on steroidogenesis and its underlying mechanism remains unclear. Using Isobaric tag for relative and absolute quantitation (iTARQ) proteomics, phosphodiesterase beta-2 (PLCß2) was identified as the most significantly up-regulated protein in immature Leydig cells (ILCs) and adult Leydig cells (ALCs) derived from male rats exposed to maternal Cd. Consistent with high expression of PLCß2, the size of LDs was increased in Leydig cells exposed to Cd, accompanied by reduction in cholesterol and progesterone (P4) levels. However, the high PLCß2 did not result in high diacylglycerol (DAG) level, because Cd exposure up-regulated diacylglycerol kinases ε (DGKε) to promote the conversion from DAG to phosphatidic acid (PA). Exogenous PA, which was consistent with the intracellular PA concentration induced by Cd, facilitated the formation of large LDs in R2C cells, followed by reduced P4 level in the culture medium. When PLCß2 expression was knocked down, the increased DGKε caused by Cd was reversed, and then the PA level was decreased to normal. As results, large LDs returned to normal size, and the level of total cholesterol was improved to restore steroidogenesis. The accumulation of PA regulated by PLCß2-DAG-DGKε signal pathway is responsible for the formation of large LDs and insufficient steroid hormone synthesis in Leydig cells exposed to Cd. These data highlight that LD is an important target organelle for Cd-induced steroid hormone deficiency in males.

An aging-related signature predicts favorable outcome and immunogenicity in lung adenocarcinoma.

Aging has been demonstrated to play vital roles in the prognosis and treatment efficacy of cancers, including lung adenocarcinoma (LUAD). This novel study aimed to construct an aging-related risk signature to evaluate the prognosis and immunogenicity of LUAD. Transcriptomic profiles and clinical information were collected from a total of 2518 LUAD patients from 12 independent cohorts. The risk signature was developed by combining specific gene expression with the corresponding regression coefficients. One cohort treated with the immune checkpoint inhibitor (ICI) was also used. Subsequently, a risk signature was developed based on 21 aging-related genes. LUAD patients with low-risk scores exhibited improved survival outcomes in both the discovery and validation cohorts. Further immunology analysis revealed elevated lymphocyte infiltration, decreased infiltration of immune-suppressive cells, immune response-related pathways, and favorable ICI predictor enrichment in the low-risk subgroup. Genomic mutation exploration indicated the enhanced mutation burden and higher mutation rates in significantly driver genes of TP53, KEAP1, SMARCA4, and RBM10 were enriched in patients with a low-risk signature. In the immunotherapeutic cohort, it was observed that low-risk aging scores were markedly associated with prolonged ICI prognosis. Overall, the estimated aging signature proved capable of evaluating the prognosis, tumor microenvironment, and immunogenicity, which further provided clues for tailoring prognosis prediction and immunotherapy strategies, apart from promoting individualized treatment plans for LUAD patients.

Citrus heat shock transcription factor CitHsfA7-mediated citric acid degradation in response to heat stress.

Heat stress is a major abiotic stress for plants, which can generate a range of biochemical and genetic responses. In 'Ponkan' mandarin fruit, hot air treatment (HAT) accelerates the degradation of citric acid. However, the transcriptional regulatory mechanisms of citrate degradation in response to HAT remain to be elucidated. Here, 17 heat shock transcription factor sequences were isolated, and dual-luciferase assays were employed to investigate whether the encoded proteins that could trans-activate the promoters of key genes in the GABA shunt, involved in citrate metabolism. We identified four heat shock transcription factors (CitHsfA7, CitHsfA3, CitHsfA4b and CitHsfA8) that showed trans-activation effects on CitAco3, CitIDH3 and CitGAD4, respectively. Transient expression of the CitHsfs in citrus fruits indicated that CitHsfA7 was the only factor that resulted in a significant lowering of the citric acid content, and these results were confirmed by a virus-induced gene silencing system (VIGS). Sub-cellar localization showed that CitHsfA7 is located in the nucleus and is capable of binding directly to a putative HSE in the CitAco3 promoter and enhance its expression. We proposed that the induction of CitHsfA7 transcript level contributes to citric acid degradation in citrus fruit, via modulation of CitAco3 in response to HAT.

Electrochemical Tip-Enhanced Raman Spectroscopy: An In Situ Nanospectroscopy for Electrochemistry.

Revealing the intrinsic relationships between the structure, properties, and performance of the electrochemical interface is a long-term goal in the electrochemistry and surface science communities because it could facilitate the rational design of electrochemical devices. Achieving this goal requires in situ characterization techniques that provide rich chemical information and high spatial resolution. Electrochemical tip-enhanced Raman spectroscopy (EC-TERS), which provides molecular fingerprint information with nanometer-scale spatial resolution, is a promising technique for achieving this goal. Since the first demonstration of this technique in 2015, EC-TERS has been developed for characterizing various electrochemical processes at the nanoscale and molecular level. Here, we review the development of EC-TERS over the past 5 years. We discuss progress in addressing the technical challenges, including optimizing the EC-TERS setup and solving tip-related issues, and provide experimental guidelines. We also survey the important applications of EC-TERS for probing molecular protonation, molecular adsorption, electrochemical reactions, and photoelectrochemical reactions. Finally, we discuss the opportunities and challenges in the future development of this young technique.

Progress on the formation mechanism of sexual dimorphism plumage color in birds.

Sexually dimorphic plumage coloration is widespread in birds in which the male plumage is brighter than the female. This phenomenon is related to the environmental constraints on sexual selection or intraspecific competition between males and females in birds. The physiological factors and genetic regulation mechanism affecting the color of sexual dimorphism plumages in birds have always attracted significant attention in research. Understanding the diversity of sexually dimorphic traits provides insights into the mating strategies of the sexes and their behavior, ecology, and evolution. Interestingly, the ASIP, MC1R, TYRP1, and BCO2 genes have been identified to play a potential role in the coloration of melanin and carotenoids in bird sexual dimorphism plumages, either by controlling the rate and type of melanin or carotene synthesis or degradation by exerting an effect on the pigment biosynthetic pathway. In this review, we systematically summarize the biological significance, the direct causes (chemical and physical color), and the influence of sex hormones in sexually dimorphic plumage coloration. We also investigate the molecular mechanism underlying the roles of some genes on sexual dimorphism coloration, thereby providing a reference for in-depth understanding on the formation mechanism(s) of sexual dimorphic coloration in birds.

Identification of two UDP-glycosyltransferases involved in the main oleanane-type ginsenosides in Panax japonicus var. major.

MAIN CONCLUSION: Two UDP-glycosyltransferases from Panax japonicus var. major were identified, and the biosynthetic pathways of three oleanane-type ginsenosides (chikusetsusaponin IVa, ginsenoside Ro, zingibroside R1) were elucidated. Chikusetsusaponin IVa and ginsenoside Ro are primary active components formed by stepwise glycosylation of oleanolic acid in five medicinal plants of the genus Panax. However, the key UDP-glycosyltransferases (UGTs) in the biosynthetic pathway of chikusetsusaponin IVa and ginsenoside Ro are still unclear. In this study, two UGTs (PjmUGT1 and PjmUGT2) from Panax japonicus var. major involved in the biosynthesis of chikusetsusaponin IVa and ginsenoside Ro were identified based on bioinformatics analysis, heterologous expression and enzyme assays. The results show that PjmUGT1 can transfer a glucose moiety to the C-28 carboxyl groups of oleanolic acid 3-O-ß-D-glucuronide and zingibroside R1 to form chikusetsusaponin IVa and ginsenoside Ro, respectively. Meanwhile, PjmUGT2 can transfer a glucose moiety to oleanolic acid 3-O-ß-D-glucuronide and chikusetsusaponin IVa to form zingibroside R1 and ginsenoside Ro. This work uncovered the biosynthetic mechanism of chikusetsusaponin IVa and ginsenoside Ro, providing the rational production of valuable saponins through synthetic biology strategy.

Effect of feed restriction on the intestinal microbial community structure of growing ducks.

In poultry, feed restriction is common feeding management to limit poultry nutrients intake so that poultry only intake the essential energy, meeting the basic need of growth and development. Our study investigated whether feeding restriction affects the diversity of the intestinal microbiota of growing breeding ducks. In this research, the 60-120-day-old ducks were raised in restricted and free-feeding groups. After slaughtering, the carcass traits and the cecal contents were collected for 16S rRNA sequencing analysis. After feeding restriction, the growth rate of ducks was limited, the weight and rate of abdominal fat decreased, and the rate of chest and leg muscles increased. In addition, feeding restriction can also change the diversity of intestinal microorganisms in breeding ducks, such as the increase of Firmicutes abundance and the decrease of Bacteroidetes abundance. After analyzing of correlation, significant correlations between gut microbiota and carcass phenotypes were found. The results indicated that gut microbiota might be involved in the life activities associated with phenotypic changes. This study proved the effect of feeding methods on the intestinal microbiota of ducks, providing a theoretical basis of the microbial angle for raising ducks in a feeding-restricted period.

Block-copolymer-like self-assembly behavior of mobile-ligand grafted ultra-small nanoparticles.

We use coarse-grained molecular dynamics simulations to study the self-assembly behavior of polyoxometalate (POM) nanoparticles (NPs) decorated with mobile polymer ligands under melt conditions. We demonstrate that due to the mobile nature of the grafted ligands on the NP surface, NPs have the ability to expose a part of their surfaces, leading to a block-copolymer-like self-assembly behavior. The exposed NP surface serves as one block and the grafted ligand polymers as another. This system has a strong ability to self-assemble into long-range ordered structures such as block copolymers due to large incompatibility between POM and ligand polymers, i.e., POM NPs can form lamellar, cylindrical, and spherical structures, which are consistent with previous experimental results. More importantly, these ordered structures are on the sub-10 nm scale, which is an important requirement for many applications. At low graft density, we find a new inverse-cylindrical structure formation where polymers form cylinders and POMs form a continuous network structure. A full self-assembly phase diagram is constructed which illustrates rules to manipulate the self-assembly structures of NPs decorated with mobile polymer ligands. We hope that these computational results will be useful for the new design of nanostructures with improved optical or electronic functions.

Increasing the activity of cell adherent cyclic NGR peptides by optimizing the peptide length and amino acid character.

Cyclic peptides are an attractive modality for the development of therapeutics and the identification of functional cyclic peptides that contribute to novel drug development. The peptide array is one of the optimization methods for peptide sequences and also useful to understand sequence-function relationship of peptides. Cell adherent cyclic NGR peptide which selectively binds to the aminopeptidase N (APN or CD13) is known as an attractive tumor marker. In this study, we designed and screened a library of different length and an amino acid substitution library to identify stronger cell adhesion peptides and to reveal that the factor of higher binding between CD13 and optimized cyclic peptides. Additionally, we designed and evaluated 192 peptide libraries using eight representative amino acids to reduce the size of the library. Through these optimization steps of cyclic peptides, we identified 23 peptides that showed significantly higher cell adhesion activity than cKCNGRC, which was previously reported as a cell adhesion cyclic peptide. Among them, cCRHNGRARC showed the highest activity, that is, 1.65 times higher activity than cKCNGRC. An analysis of sequence and functional data showed that the rules which show higher cell adhesion activity for the three basic cyclic peptides (cCX1 HNGRHX2 C, cCX1 HNGRAX2 C, and cCX1 ANGRHX2 C) are related with the position of His residues and cationic amino acids.