Eugenol targeting CrtM inhibits the biosynthesis of staphyloxanthin in Staphylococcus aureus

Staphylococcus aureus is a serious foodborne pathogen threatening food safety and public health.Especially the emergence of methicillin-resistant Staphylococcus aureus(MRSA)increased the difficulty of S.aureus treatment.Staphyloxanthin is a crucial virulence factor of S.aureus.Blocking staphyloxanthin production could help the host immune system counteract the invading S.aureus cells.In this study,we first screened for staphyloxanthin inhibitors using a virtual screening method.The outcome of the virtual screening method resulted in the identification of eugenol(300μg/mL),which significantly inhibits the staphyloxanthin production in S.aureus ATCC 29213,S.aureus Newman,MRSA ATCC 43300 and MRSA ATCC BAA1717by 84.2%,63.5%,68.1%,and 79.5%,respectively.The outcome of the growth curve assay,field-emission scanning electron,and confocal laser scanning microscopy analyses confirmed that eugenol at the test concentration did not affect the morphology and growth of S.aureus.Moreover,the survival rate of S.aureus ATCC 29213 and MRSA ATCC 43300 under H_(2)O_(2) pressure decreased to 51.9%and 45.5%in the presence of eugenol,respectively.The quantitative RT-PCR and molecular simulation studies revealed that eugenol targets staphyloxanthin biosynthesis by downregulating the transcription of the crtM gene and inhibiting the activity of the CrtM enzyme.Taken together,we first determined that eugenol was a prominent compound for staphyloxanthin inhibitor to combat S.aureus especially MRSA infections.

Identification of an immune-related gene signature for predicting prognosis and immunotherapy efficacy in liver cancer via cell-cell communication

BACKGROUND Liver cancer is one of the deadliest malignant tumors worldwide.Immunotherapy has provided hope to patients with advanced liver cancer,but only a small fraction of patients benefit from this treatment due to individual differences.Identifying immune-related gene signatures in liver cancer patients not only aids physicians in cancer diagnosis but also offers personalized treatment strategies,thereby improving patient survival rates.Although several methods have been developed to predict the prognosis and immunotherapeutic efficacy in patients with liver cancer,the impact of cell-cell interactions in the tumor microenvir-onment has not been adequately considered.AIM To identify immune-related gene signals for predicting liver cancer prognosis and immunotherapy efficacy.METHODS Cell grouping and cell-cell communication analysis were performed on single-cell RNA-sequencing data to identify highly active cell groups in immune-related pathways.Highly active immune cells were identified by intersecting the highly active cell groups with B cells and T cells.The significantly differentially expressed genes between highly active immune cells and other cells were subsequently selected as features,and a least absolute shrinkage and selection operator(LASSO)regression model was constructed to screen for diagnostic-related features.Fourteen genes that were selected more than 5 times in 10 LASSO regression experiments were included in a multivariable Cox regression model.Finally,3 genes(stathmin 1,cofilin 1,and C-C chemokine ligand 5)significantly associated with survival were identified and used to construct an immune-related gene signature.RESULTS The immune-related gene signature composed of stathmin 1,cofilin 1,and C-C chemokine ligand 5 was identified through cell-cell communication.The effectiveness of the identified gene signature was validated based on experi-mental results of predictive immunotherapy response,tumor mutation burden analysis,immune cell infiltration analysis,survival analysis,and expression analysis.CONCLUSION The findings suggest that the identified gene signature may contribute to a deeper understanding of the activity patterns of immune cells in the liver tumor microenvironment,providing insights for personalized treatment strategies.

Direct detection of a single[4Fe-4S]cluster in a tungsten-containing enzyme:Electrochemical conversion of CO_(2) into formate by formate dehydrogenase

The conversion of CO_(2) into fuels and valuable chemicals is one of the central topics to combat climate change and meet the growing demand for renewable energy.Herein,we show that the formate dehydrogenase from Clostridium ljungdahlii(ClFDH)adsorbed on electrodes displays clear characteristic voltammetric signals that can be assigned to the reduction and oxidation potential of the[4Fe-4S]^(2+/+)cluster under nonturnover conditions.Upon adding substrates,the signals transform into a specific redox center that engages in catalytic electron transport.ClFDH catalyzes rapid and efficient reversible interconversion between CO_(2) and formate in the presence of substrates.The turnover frequency of electrochemical CO_(2) reduction is determined as 1210 s^(-1) at 25℃ and pH 7.0,which can be further enhanced up to 1786 s^(-1) at 50℃.The Faradaic efficiency at−0.6 V(vs.standard hydrogen electrode)is recorded as 99.3%in a 2-h reaction.Inhibition experiments and theoretical modeling disclose interesting pathways for CO_(2) entry,formate exit,and OCN−competition,suggesting an oxidation-state-dependent binding mechanism of catalysis.Our results provide a different perspective for understanding the catalytic mechanism of FDH and original insights into the design of synthetic catalysts.

Microbially-mediated formation of Ca-Fe carbonates during dissimilatory ferrihydrite reduction:Implications for the origin of sedimentary ankerite

The origin of sedimentary dolomite has become a long-standing problem in the Earth Sciences.Some carbonate minerals like ankerite have the same crystal structure as dolomite,hence their genesis may provide clues to help solving the dolomite problem.The purpose of this study was to probe whether microbial activity can be involved in the formation of ankerite.Bio-carbonation experiments associated with microbial iron reduction were performed in batch systems with various concentrations of Ca^(2+)(0–20 mmol/L),with a marine iron-reducing bacterium Shewanella piezotolerans WP3 as the reaction mediator,and with lactate and ferrihydrite as the respective electron donor and acceptor.Our biomineralization data showed that Ca-amendments expedited microbially-mediated ferrihydrite reduction by enhancing the adhesion between WP3 cells and ferrihydrite particles.After bioreduction,siderite occurred as the principal secondary mineral in the Ca-free systems.Instead,Ca-Fe carbonates were formed when Ca^(2+)ions were present.The CaCO_(3) content of microbially-induced Ca-Fe carbonates was positively correlated with the initial Ca2+concentration.The Ca-Fe carbonate phase produced in the 20 mmol/L Ca-amended biosystems had a chemical formula of Ca_(0.8)Fe_(1.2)(CO_(3))_(2),which is close to the theoretical composition of ankerite.This ankeritelike phase was nanometric in size and spherical,Ca-Fe disordered,and structurally defective.Our simulated diagenesis experiments further demonstrated that the resulting ankerite-like phase could be converted into ordered ankerite under hydrothermal conditions.We introduced the term“proto-ankerite”to define the Ca-Fe phases that possess near-ankerite stoichiometry but disordered cation arrangement.On the basis of the present study,we proposed herein that microbial activity is an important contributor to the genesis of sedimentary ankerite by providing the metastable Ca-Fe carbonate precursors.

Action modes of transcription activator-like effectors(TALEs) of Xanthomonas in plants

Plant-pathogenic Xanthomonas infects a wide variety of host plants and causes many devastating diseases on crops. Transcription activator-like effectors（TALEs） are delivered by a type III secretion system（T3 SS） of Xanthomonas into plant nuclei to directly bind specific DNA sequences（TAL effector-binding elements, EBEs） on either strand of host target genes with an unique modular DNA-binding domain and to bidirectionally drive host gene transcription. The target genes in plants consist of host susceptibility（S） genes promoting disease（ETS） and resistance（R） genes triggering defense（ETI）. Here we generally summarized the discovery of TALEs in Xanthomonas species, their functions in bacterial pathogenicity in plants and their target genes in different host plants, and then focused on the newly revealed modes of protein action in triggering or suppressing plant defense.

Characterisation of the bacterial community in expressed prostatic secretions from patients with chronic prostatitis/chronic pelvic pain syndrome and infertile men： a preliminary investigation

The expressed prostatic secretions （EPSs） of men with chronic prostatitis/chronic pelvic pain syndrome （CP/CPPS）, infertile men and normal men were subjected to microbiological study. EPSs were collected from the subjects, which included 26 normal men, 11 infertile patients and 51 CP/CPPS patients. DNA was extracted from each specimen, and the V3 regions of the 16S rRNA genes were amplified using universal bacterial primers. The results showed that the EPS 16S rRNA gene-positive rate in the CP/CPPS and infertile patients was much higher than in the normal men, but without any difference among the three patient groups. The denaturing gradient gel electrophoresis （DGGE） method was used to characterize the EPS bacterial community structure of the prostate fluid from patients with CP/CPPS or infertility issues. Principal component analysis （PCA） and partial least squares （PLS） analyses of PCR-DGGE profiles revealed that the EPS bacterial community structure differed among the three groups. Three bands were identified as the key factors responsible for the discrepancy between CP/CPPS patients and infertile patients （P〈O.05）. Two bands were identified as priority factors in the discrepancy of category IliA and category IIIB prostatitis patients （P〈O.05）. According to this research, the ecological balance of the prostate and low urethra tract, when considered as a microenvironment, might play an important role in the maintenance of a healthy male reproductive tract.

Qualitative analysis of chemical components in Lianhua Qingwen capsule by HPLC-Q Exactive-Orbitrap-MS coupled with GC-MS

The Lianhua Qingwen(LHQW) capsule is a popular traditional Chinese medicine for the treatment of viral respiratory diseases.In particular,it has been recently prescribed to treat infections caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).However,due to its complex composition,little attention has been directed toward the analysis of chemical constituents present in the LHQW capsule.This study presents a reliable and comprehensive approach to characterizing the chemical constituents present in LHQW by high-performance liquid chromatography-Q Exactive-Orbitrap mass spectrometry(HPLC-Q Exactive-Orbitrap-MS) coupled with gas chromatography-mass spectrometry(GC-MS).An automated library alignment method with a high mass accuracy(within 5 ppm) was used for the rapid identification of compounds.A total of 104 compounds,consisting of alkaloids,flavonoids,phenols,phenolic acids,phenylpropanoids,quinones,terpenoids,and other phytochemicals,were successfully characterized.In addition,the fragmentation pathways and characteristic fragments of some representative compounds were elucidated.GC-MS analysis was conducted to characterize the volatile compounds present in LHQW.In total,17 compounds were putatively characterized by comparing the acquired data with that from the NIST library.The major constituent was menthol,and all the other compounds were terpenoids.This is the first comprehensive report on the identification of the major chemical constituents present in the LHQW capsule by HPLC-Q Exactive-Orbitrap-MS,coupled with GCMS,and the results of this study can be used for the quality control and standardization of LHQW capsules.

Core Metabolic Features and Hot Origin of Bathyarchaeota

The archaeal phylum Bathyarchaeota comprises highly diversified subgroups and is considered to be one of the most abundant microorganisms on earth. The metabolic features and evolution of this phylum still remain largely unknown. In this article, a comparative metabolic analysis of 15 newly reconstructed and 36 published metagenomic assembled genomes (MAGs) spanning 10 subgroups was performed, revealing the core metabolic features of Bathyarchaeota—namely, protein, lipid, and benzoate degradation;glycolysis;and the Wood–Ljungdahl (WL) pathway, indicating an acetyl-CoA-centralized metabolism within this phylum. Furthermore, a partial tricarboxylic acid (TCA) cycle, acetogenesis, and sulfur-related metabolic pathways were found in specific subgroups, suggesting versatile metabolic capabilities and ecological functions of different subgroups. Intriguingly, most of the MAGs from the Bathy-21 and -22 subgroups, which are placed at the phylogenetic root of all bathyarchaeotal lineages and likely represent the ancient Bathyarchaeota types, were found in hydrothermal environments and encoded reverse gyrase, suggesting a hyperthermophilic feature. This work reveals the core metabolic features of Bathyarchaeota, and indicates a hot origin of this archaeal phylum.

Combined application of Trichoderma harzianum SH2303 and difenoconazole-propiconazolein controlling Southern corn leaf blight disease caused by Cochliobolus heterostrophus in maize

Southern corn leaf blight(SCLB)disease caused by Cochliobolus heterostrophus is one of the major threats to corn production worldwide.The synergistic application of low toxic chemical fungicide and biocontrol agents could improve biocontrol stability and efficiency against plant diseases,which ultimately reduce use of chemical fungicide.Trichoderma spp.,well-known biocontrol fungi have been used to control some foliar diseases.However,few works have been reported on synergistic application of chemical fungicide and Trichoderma against foliar diseases.This study was aimed to investigate the control effect on the synergistic application of Trichoderma harzianum SH2303 and difenoconazole-propiconazole(DP)against SCLB.Results showed that the synergistic application of DP and SH2303 reduced the leaf spot area compared to the control.The efficacy of synergistic application of DP+SH2303 against SCLB could last for 15–20 d in pot trial under the greenhouse condition.Under the natural field condition,maize treated with DP+DP and DP+SH2303 showed 60%control,which was higher than that of SH2303+DP(45%)and SH2303+SH2303(35%).All these treatments induced the synthesis of defense-related enzymes(phenylalanine ammonia lyase(PAL),catalase(CAT),and superoxide dismutase(SOD))and the defence-related gene expression of SA pathway(PR1).Taken together the in-vitro leaf test and field trial,the control of SCLB by synergistic application of DP+SH2303 was similar to that of DP+DP.Among synergistic application,the sequential application of DP+SH2303 showed better control than the sequential application of SH2303+DP.It was concluded that the synergistic application of chemical fungicide(DP)and biocontrol agent(T.harzianum SH2303)could be used to reduce the chemical fungicide and to reduce the SCLB diseases in maize,which provided alternative approach to realize an eco-friendly controlling of the foliar disease.

Screening of antagonistic Trichoderma strains and their application for controlling stalk rot in maize

Maize is one of the major crops in China, but maize stalk rot occurs nationwide and has become one of the major challenges in maize production in China. In order to find an environment-friendly and feasible technology to control this disease, a Trichoderma-based biocontrol agent was selected. Forty-eight strains with various inhibition activities to Fusarium graminearum, and Fusarium verticillioides were tested. A group of Trichoderma strains(DLY31, SG3403, DLY1303 and GDFS1009) were found to provide an inhibition rate to pathogen growth in vitro of over 70%. These strains also prevented pathogen infection over 65% and promoted the maize seedling growth for the main root in vivo by over 50%. Due to its advantage in antifungal activity against pathogens and promotion activity to maize, Trichoderma asperellum GDSF1009 was selected as the most promising strain of the biocontrol agent in the Trichoderma spectrum. Pot experiments showed that the Trichoderma agent at 2–3 g/pot could achieve the best control of seedling stalk rot and promotion of maize seedling growth. In the field experiments, 8–10 g/hole was able to achieve over 65% control to stalk rot, and yield increased by 2–11%. In the case of natural morbidity, the control efficiency ranged from 27.23 to 48.84%, and the rate of yield increase reached 11.70%, with a dosage of Trichoderma granules at 75 kg ha^-1. Based on these results, we concluded that the Trichoderma agent is a promising biocontrol approach to stalk rot in maize.

Sod gene of Curvularia lunata is associated with the virulence in maize leaf

Curvularia leaf spot, caused mainly by Curvularia lunata, is a widespread plant disease in China. In the recent years, di- rectional host selection by the pathogen, which likely results in the virulence differentiation in pathogens, is widely reported. Among the hallmarks potentially associated to pathogen variation in virulence, superoxide dismutase gene Sod has been found to be closely related to the enhancement of virulence. In the present study, the full-length of Sod was obtained via Blastn alignment against GenBank and the whole genome of C. lunata. In order to understand the role of Sod in the vir- ulence variation in C. lunata, targeted gene disruption was performed to construct Sod mutants. The cell wall degrading enzyme （CWDE） activities and toxin production of ASod were not distinctly different from wild-type strain CX-3 and its complon. However, at an early stage of infection, 3Sod virulence appeared to be lower than CX-3 and the complon, while at a later stage, its virulence gradually returned to the level of CX-3 and the complon. Furthermore, the melanin production of ASod was significantly reduced compared to CX-3 and the complon, suggesting that Sod gene influences the virulence by regulating melanin production at an early stage of infection but is not essential for pathogenicity. However, the disruption of Sod did not significantly affect the transcriptional expression of the melanin biosynthesis-associated genes, bml and scd. Therefore, we infer that Sod in C. lunata are involved, to some extent, with the virulence in maize leaf, but still needs further studies to have a clear understanding of its mechanism.

Molecular diversity of Thermococcales isolated from Guaymas Basin hydrothermal vents

Members of Thermococcales are organoheterotrophic hyperthermophilic anaerobes consisting of three genera, Thermococcus, Pyrococcus, and Palaeococcus, among which Thermococcus are the most frequently isolated. In this study, a variety of Thermococcales strains were isolated from the Guaymas Basin hydrother- mal vents under different temperatures and pressures. Based on their 16S rRNA gene sequences, all the s- trains isolated from 85℃ or 95℃ enrichment cultures at ambient pressure were classified as Thermococcus, while strains isolated from 108℃-30 MPa enrichment cultures belonged to Pyrococcus. The combination of high pressure and high temperature for enrichment was shown to be an efficient method for isolating Pyro- coccus strains. Through selecting and analyzing with multiple molecular phylogenetic markers, the isolated Thermococcales strains were found quite diversified including several putative novel species. This demon- strates a vast genetic reservoir of Thermoccoccales in the deep-sea hydrothermal vents, and a fast evolving of the Thermococcales species adapting to the fast changing environment.

Transcriptome analysis for understanding the mechanism of dark septate endophyte S16 in promoting the growth and nitrate uptake of sweet cherry

Sweet cherry is one of the most popular fresh fruits in the world.Previously,we isolated a soilborne dark septate endophyte(DSE)strain,S16,which promoted the growth of Gisela 5 sweet cherry rootstock.However,little is known about the molecular mechanism of the effect of S16 on the growth of sweet cherry.In this study,the physiological parameters and transcript profiles of sweet cherry roots were analyzed under S16 treatment compared with a control to elucidate the molecular mechanisms of the effect of this strain on sweet cherry growth.After inoculation with S16,sweet cherry seedlings exhibited more vigorous growth.Moreover,we identified 4249 differentially expressed genes(DEGs)between S16-treated plants and the control.Many of the DEGs are involved in pathways related to plant growth,such as cellular metabolic and plant hormone pathways.Additionally,some genes involved in nitrate regulation were also enriched;and these genes may be involved in the regulation of nitrate uptake in plants.Physiological index detection demonstrated that S16 could improve the nitrate assimilation of sweet cherry via NO3–transporters.This RNA-seq dataset provides comprehensive insight into the transcriptomic landscape to reveal the molecular mechanisms whereby the DSE influences the growth of sweet cherry.

Statistical optimization and anticancer activity of a red pigment isolated from Streptomyces sp. PM4

Objective:To enhance the pigment production byStreptomycessp.PM4 for evaluating its anticancer activity.Methods:Response surface methodology was employed to enhance the production of red pigment fromStreptomycessp.PM4.Optimized pigment was purified and evaluated for the anticancer activity against HT1080,Hep2,HeLa and MCF7 cell lines by MTT assay.Results:Based on the response surface methodology,it could be concluded that maltose (4.06 g),peptone (7.34 g),yeast extract(4.34 g)and tyrosine(2.89 g)were required for the maximum production of pigment(1.68 g/L)by theStreptomycessp.PM4.Optimization of the medium with the above tested features increased the pigment yield by 4.6 fold.Pigment showed the potential anticancer activity against HT1080,HEp-2,HeLa and MCF-7cell lines with the IC50value of 18.5,15.3,9.6 and 8.5 respectively.Conclusions:The study revealed that the maximum amount of pigment could be produced to treat cancer.

Metamorphosis of Magnetospirillum magneticum AMB-1 cells

Magnetospirillum magneticum strain AMB-1 belongs to the family of magnetotactic bacteria. It possesses a magnetosome chain aligning, with the assistance of cytoskeleton filaments MamK, along the long axis of the spiral cells. Most fresh M. magneticum AMB-1 cells exhibit spiral morphology. In addition, other cell shapes such as curved and spherical were also observed in this organism. Interestingly, the spherical cell shape increased steadily with prolonged incubation time. As the actin-like cytoskeleton protein MreB is involved in maintenance of cell shapes in rod-shaped bacteria such as Escherichia coli and Bacillus subtilis, the correlation between MreB protein levels and cell shape was investigated in this study. Immunoblotting analysis showed that the quantity of MreB decreased when the cell shape changed along with incubation time. As an internal control, the quantity of MamA was not obviously changed under the same conditions. Cell shape directs cell-wall synthesis during growth and division. MreB is required for maintaining the cell shape. Thus, MreB might play an essential role in maintaining the spiral shape of M. magneticum AMB-1 cells.

Biochemical Characterization of Uracil-DNA Glycosylase from Pyrococcus furiosus

We report the characterization of a uracil-DNA glycosylase（UDG） from the hyperthermophilic archaea Pyrococcus furiosus（P, furiosus）. P. furiosus UDG（PfUDG） has high sequence similarity to the families IV and V UDGs（thermostable UDG family and PaUDG-b family）. PfUDG excises uracil from various DNA substrates with the following order： U/T=U/C〉U/G=U/AP=U/-〉U/U=U/I=U/A. The optimal temperature and pH value for uracil exci- sion by PfUDG are 70 ℃ and 9.0, respectively. The removal of U is inhibited by the divalent ions of Fe, Ca, Zn, Cu, Co, Ni and Mn, as well as a high concentration of NaC1. The phosphorothioates near uracil strongly inhibit the exci- sion of uracil by PfUDG. Interestingly, pfuDNA（Pyrococcusfuriosus DNA） polymerase, which tightly binds the ura- cil-carrying oligonucleotide, does not inhibit the excision by Pfl.IDG, suggesting PfUDG in vivo functions as the re- pair enzyme to excise uracil damage in genome.

Synergism of essential oils with lipid based nanocarriers: emerging trends in preservation of grains and related food products

Grains are one of the major food staples in the world.The cereal grains are easily susceptible to damage by moisture content,flour beetles and food pathogens during storage,harvesting and post harvesting.Food preservative techniques namely drying,freezing,and dehydration,acquire little advantages.However,they cause few undesirable alterations in the organoleptic and nutritional properties of the preserved food items.Therefore,there is a continuous search for new preservation techniques in food industries,to satisfy the customer demands on the addition of natural food preservatives,devoid of pathogenic contaminants and without changes in organoleptic properties.Essential oils(EOs)have been predicted as“natural food additives”in the preservative process.The synergistic potential of EOs with various nanocarriers plays an emerging role in the food industry.Therefore,the present review has focused on the lipid based nanocarriers,and the methods used for the functionalization or encapsulation of EOs and applications in the preservation of food items such as cooked rice,rice flour,grains,sliced breads have also been discussed.The present review ascertains the antimicrobial significance of active EOs loaded lipid nanocarriers in the form of nano emulsions,solid lipid nanoparticles and liposomes for preserving grains and flours.

Global-Scale Diversity and Distribution Characteristics of Reef-Associated Symbiodiniaceae via the Cluster-Based Parsimony of Internal Transcribed Spacer 2 Sequences

Photosynthetic species belonging to Symbiodiniaceae play important ecological roles in coral reef ecosystems. Nine phylogenetically supported Symbiodiniaceae clades(each containing multiple genetically distinct molecular types) have been detected in reef-associated animals and in seawater or sediments near coral reef areas. Although major advances in research on Symbiodiniaceae diversity have been made, information on the global-scale diversity and distribution characteristics of Symbiodiniaceae clades/types is still limited or must be expanded because most studies on Symbiodiniaceae have mainly focused on a limited number of hosts associated with Symbiodiniaceae or coral reef areas. Here, the diversity and distribution characteristics of Symbiodiniaceae data derived from reef-associated animals and seawater or sediments near coral reef areas were analyzed using 3899 qualified Symbiodiniaceae internal transcribed spacer 2(ITS2) sequences retrieved from the GenBank database in May 2017. These sequences were annotated as Symbiodiniaceae ITS2 types via sequence alignment against database of Symbiodiniaceae ITS2 types. Results showed that photosynthetic Symbiodiniaceae ITS2 sequences could be annotated as 119 Symbiodiniaceae ITS2 types within nine clades(A–I), and Symbiodiniaceae ITS2 types mainly inhabited coral reefs between 30?N and 30?S. Symbiodiniaceae ITS2 types could be associated with multiple host taxa. Interestingly, these results implied that the distribution of Symbiodiniaceae ITS2 types was distinct in the Atlantic Ocean, the Red Sea, the Mediterranean Sea, and the Indo-Pacific Ocean. Although future field research should be performed to verify our results, this study provided a broad perspective of the diversity of Symbiodiniaceae clades/types on a global scale.

Self-Assembled Nanomicelles of Affibody-Drug Conjugate with Excellent Therapeutic Property to Cure Ovary and Breast Cancers

Affibody molecules are small nonimmunoglobulin affinity proteins,which can precisely target to some cancer cells with specific overexpressed molecular signatures.However,the relatively short in vivo half-life of them seriously limited their application in drug targeted delivery for cancer therapy.Here an amphiphilic affibody-drug conjugate is self-assembled into nanomicelles to prolong circulation time for targeted cancer therapy.As an example of the concept,the nanoagent was prepared through molecular self-assembly of the amphiphilic conjugate of Z_(HHR2:342)-Cys with auristatin E derivate,where the affibody used is capable of binding to the human epidermal growth factor receptor 2(HER2).Such a nanodrug not only increased the blood circulation time,but also enhanced the tumor targeting capacity(abundant affibody arms on the nanoagent surface) and the drug accumulation in tumor.As a result,this affibody-based nanoagent showed excellent antitumor activity in vivo to HER2-positive ovary and breast tumor models,which nearly eradicated both small solid tumors(about 100 mm^(3)) and large established tumors(exceed 500 mm^(3)).The relative tumor proliferation inhibition ratio reaches 99.8% for both models.

Impact of oxygen supply on production of terpenoids by microorganisms: State of the art

Terpenoids are a class of high value-added natural products with a variety of biological functions.Genetically engineered microorganisms,such as those of Escherichia coli and Saccharomyces cerevisiae,have merits in producing plant or fungus-derived terpenoids,due to their mature genetic manipulation,simple nutrient demand and fast growth.Oxygen,as a key environmental factor,is particularly important to microbial metabolism and growth,and suitable oxygen supply is viewed as a prerequisite for realizing highly efficient production of terpenoids by engineered microorganisms.In this article,the role of oxygen in regulating terpenoid bioproduction is overviewed from the viewpoints of cellular carbon metabolism,energy metabolism and terpenoid anabolism.Strategies on adjusting oxygen availability to microorganisms,including genetic modification of cellular metabolism related with oxygen utilization,are summarized and discussed,to provide helpful information for further improvement of terpenoid biosynthesis by microbes.