Construction and expression of circular RNA in vitro / 中国生物制品学杂志

@#Objective To construct encoding RNA that can be cyclized in vitro by using the permuted intron exon(PIE)strategy in the maturation process of eukaryotic mRNA,and transfect it into HEK-293T cells for expression.Methods The sequences of 5'and 3'cyclic arms with groupⅠcatalytic intron,the internal ribosome entry sites(IRES)of Coxsackievirus B3(CVB3)and the target gene were selected to construct the template plasmid. Linearization plasmid template obtained by PCR was used to synthesize linear RNA through in vitro transcription(IVT),which then started in vitro cyclization(IVC)by the addition of cyclization reagents to obtain circular RNA(circRNA). RNA cyclization was confirmed by agarose gel electrophoresis and ribonuclease R(RNase R)digestion. HEK-293T cells were transfected with circRNAs respectively carrying enhanced green fluorescent protein(EGFP),firefly luciferase(Fluc),and influenza virus hemagglutinin(HA)IVR-180 genes,to verify their expression with in vitro.Results With RNA cyclization,the main band of agarose gel electrophoresis became smaller and small fragments appeared. After RNase R digestion,only some circRNA bands remained.HEK-293T cells transfected with EGFP-circRNA showed significant green fluorescence under the fluorescence microscope.The Fluc expression values of HEK-293T cells transfected with Fluc-circRNA were on average 20 times higher than non cyclized RNA,and the relative light unit(RLU)scaled up with the increase of Fluc-circRNA transfection dose. Western blot analysis showed that HA protein was successfully expressed in HEK-293T cells transfected with HA-circRNA.Conclusion In this study,linear RNA was successfully cyclized in vitro and different proteins were expressed,which lays a foundation of the research of new influenza vaccines and mRNA vaccines.

Construction of Artificial Cells with Application to Investigate Peritoneal Metastasis in Ovarian Cancer / 中山大学学报(医学科学版)

ObjectiveTo construct a human ovarian cancer cell line SKOV3 （SK-Luc-EGFP） stably co-expressing luciferase （Luc） and enhanced green fluorescent protein （EGFP） and to explore its application in ovarian cancer research both in vitro and in vivo. MethodsThe recombinant plasmid pCDH-Luc-T2A-EGFP-Puro was constructed by introducing a Luc-T2A-EGFP fusion gene fragment amplified by Overlap PCR into plasmid vector. The three-plasmid lentivirus packaging system was transfected into HEK 293T cells and the viral supernatant was harvested to infect SKOV3 cells. SK-Luc-EGFP cell line with the highest fluorescence intensity of EGFP was obtained by puromycin selection and flow cytometry assessment， and the Luc expression of the cell line was subsequently validated by in vitro bioluminescent assay. SK-Luc-EGFP cells were further explored for the following applications： distinguishing SK-Luc-EGFP cells from non-tumor cells in ascites by flow cytometry and confocal microscopy； visualizing adhesion of SK-Luc-EGFP cells to mesothelial cells or omentum by fluorescence microscopy； monitoring process of SK-Luc-EGFP tumorigenesis by in vivo bioluminescence imaging. ResultsA recombinant lentiviral expression plasmid pCDH-Luc-T2A-EGFP-Puro was constructed and packaged into lentiviral particles that were then transfected into SKOV3 cells to generate SK-Luc-EGFP cell line. The purity of SK-Luc-EGFP cells based on EGFP expression was 100% as validated by fluorescence microscopy and flow cytometry； SK-Luc-EGFP cells could be visually distinguished from non-tumor cells in ascitic fluid by flow cytometry and confocal imaging. Moreover， Luc expression in SK-Luc-EGFP cells was verified by in vitro bioluminescence assay， and a linear relationship with a correlation coefficient of 0.997 9 was found between cell number and the bioluminescent signal. Adhesion of SK-Luc-EGFP cells to mesothelial cells was directly observed by fluorescence imaging in in vitro adhesion assay； peritoneal adhesion of SK-Luc-EGFP cells to omentum was also observed after intraperitoneal （i.p.） injection of SK-Luc-EGFP cells in nude mice； in the peritoneal metastasis mouse model established by i.p. injection of SK-Luc-EGFP cells， monitoring of tumorigenesis process was achieved by in vivo bioluminescence imaging. ConclusionSK-Luc-EGFP cell line is a useful tool for investigating ovarian cancer in vitro and in vivo.

Establishment of a screening cell model for cannabinoid type 1 receptor agonists / 药学学报

Cannabinoid receptors are one of the most expressed G protein-coupled receptors in the central nervous system, which are potential drug targets for inflammation, pain and drug abuse. Cannabinoid receptors are composed of type 1 receptor (CB1R), type 2 receptor (CB2R) and other receptors, of which CB1R plays a vital role in regulating central memory, cognition, and motor function. Therefore, screening CB1R agonists has potential value in treating nervous system diseases. In this study, the intracellular loop 3 (ICL3) domain of CB1R was replaced with a circular-permutated enhanced green fluorescent protein (cpEGFP). After infecting HEK 293T cells with lentivirus particles, we obtained a stable cell line that was overexpressed human CB1R-cpEGFP after puromycin selection. The interaction between receptor agonists and CB1R led to the change of receptor conformation, resulting in de-protonation of the EGFP, and enhancing the fluorescence intensity. Therefore, active CB1R compounds could be verified by measuring the fluorescence intensity. Using CB1R agonist arachidonyl-2′-chloroethylamide (ACEA) as a positive control to evaluate the reliability of this model, studies have shown that ACEA could induce receptor activation and increase fluorescence intensity, while antagonist rimonabant inhibited receptor activation with unchanged fluorescence intensity. In conclusion, this study successfully constructed a fluorescent probe screening model for CB1R agonists.

Construction of ATMT System for Clonostachys rosea and Its Conditional Optimization of Colonization into Glycyrrhiza uralensis Seeds / 中国实验方剂学杂志

ObjectiveAgrobacterium tumefaciens-mediated transformation （ATMT） of Clonostachys rosea， an endophytic fungus of Glycyrrhiza uralensis seeds， was established and optimized， and orthogonal test was designed to optimize the colonization conditions of C. rosea for G. uralensis seeds， so as to lay foundation for the development of biofertilizer and the breeding of high-quality G. uralensis. MethodThe conditions of ATMT were optimized from three aspects， including the concentration of acetosyringone， co-culture time and the concentration of conidia of recipient fungi. Then， high-quality transformants were selected. Orthogonal test was used to optimize the colonization conditions by taking co-culture temperature， co-culture time and spore concentration as factors and colonization rate as index. ResultWhen spore concentration was 1×107 cfu·mL-1， acetosyringone concentration was 150 μmol·L-1 and the co-culture time was 60 h， the transformation efficiency of C. rosea was the highest， which was 135 transformants per 1×107 recipient fungal spores. The accuracy and stability of the transformations were tested by cloning the marker gene green fluorescent protein （GFP） and β-glucuronidase （GUS） staining. When co-culture temperature was 25 ℃， co-culture time was 36 h and the spore concentration was 1×106 cfu·mL-1， the colonizing rate for C. rosea back dyeing into G. uralensis seeds by seed soaking method was the highest， which was 71.11%. ConclusionThis study successfully establishes stable and efficient technical systems not only of ATMT in C. rosea， but also of colonization of the transformants into G. uralensis seeds， which can lay a foundation for the development of biofertilizer of G. uralensis.

A preparation strategy for protein-oriented immobilized silica magnetic beads with Spy chemistry for ligand fishing / 药物分析学报

Due to the complexity of bioactive ingredients in biological samples,the screening of target proteins is a complex process.Herein,a feasible strategy for directing protein immobilization on silica magnetic beads for ligand fishing based on SpyTag/SpyCatcher(ST/SC)-mediated anchoring is presented.Carboxyl functional groups on the surface of silica-coated magnetic beads(SMBs)were coupled with SC using the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride/N-hydroxysulfosuccinimide method,named SC-SMBs.The green fluorescent protein(GFP),as the capturing protein model,was ST-labeled and anchored at a specific orientation onto the surface of SC-SMBs directly from relevant cell lysates via ST/SC self-ligation.The characteristics of the SC-SMBs were studied via electron microscopy,energy dispersive spectroscopy,and Fourier transform infrared spectroscopy.The spontaneity and site-specificity of this unique reaction were confirmed via electrophoresis and fluorescence analyses.Although the alkaline stability of ST-GFP-ligated SC-SMBs was not ideal,the formed isopeptide bond was unbreakable under acidic conditions(0.05 M glycine-HCl buffer,pH 1-6)for 2 h,under 20％ethanol solution within 7 days,and at most temperatures.We,therefore,present a simple and universal strategy for the preparation of diverse protein-functionalized SMBs for ligand fishing,prompting its usage on drug screening and target finding.

Preparation of transgenic Musca domestica by microinjection method / 生物工程学报

The transposon vector containing enhanced green fluorescent protein (EGFP) was injected into early housefly (Musca domestica L.) eggs by microinjection method to realize stable gene expression in vivo for verification, and to study housefly gene function. A borosilicate glass micro injection needle suitable for microinjection of housefly eggs was made, the softening treatment conditions of housefly egg shells were explored, and a microinjection technology platform suitable for housefly was constructed with a high-precision microsyringe Nanoject Ⅲ as the main body. The recombinant plasmid PiggyBac-[3×P3]-EGFP containing the eye-specific 3×P3 promoter and EGFP and the stable genetic expression helper plasmid pHA3pig helper were microinjected into the treated housefly eggs. After emergence, the eye luminescence was observed, and the expression and transcription level of EGFP were detected. The results showed that the normal hatching rate of housefly eggs was 55% when rinsed in bleaching water for 35 s. The hardness of the egg shell treated for 35 s was suitable for injection and the injection needle was not easy to break. About 3% of the emerged housefly eyes had green fluorescence. Through further molecular detection, EGFP specific fragments with a size of 750 bp were amplified from DNA and RNA of housefly. Through the technical platform, the stable expression of reporter genes in housefly can be conveniently and effectively realized, and a bioreactor with housefly as the main body can be established, which provides certain reference value for subsequent research on housefly gene function.

Transient expression of a green fluorescent protein in tobacco and maize chloroplast

BACKGROUND: Maize is one of the most important crops worldwide and has been a target of nuclear-based transformation biotechnology to improve it and satisfy the food demand of the ever-growing global population. However, the maize plastid transformation has not been accomplished due to the recalcitrant condition of the crop. RESULTS: In this study, we constructed two different vectors with homologous recombination sequences from maize (Zea mays var. LPC13) and grass (Bouteloua gracilis var. ex Steud) (pZmcpGFP and pBgcpGFP, respectively). Both vectors were designed to integrate into rrn23S/rrn16S from an inverted repeat region in the chloroplast genome. Moreover, the vector had the mgfp5 gene driven by Prrn, a leader sequence of the atpB gene and a terminator sequence from the rbcL gene. Also, constructs have an hph gene as a selection marker gene driven by Prrn, a leader sequence from rbcL gene and a terminator sequence from the rbcL gene. Explants of maize, tobacco and Escherichia coli cells were transformed with both vectors to evaluate the transitory expression­an exhibition of green and red fluorescent light under epifluorescence microscopy. These results showed that both vectors were expressed; the reporter gene in all three organisms confirmed the capacity of the vectors to express genes in the cell compartments. CONCLUSIONS: This paper is the first report of transient expression of GFP in maize embryos and offers new information for genetically improving recalcitrant crops; it also opens new possibilities for the improvement in maize chloroplast transformation with these vectors.

Progress in fluorescent visualization techniques for neurotransmitter detection / 生物工程学报

Neurotransmitters play an important role in nervous system. Temporal and spatial changes of neurotransmitter distribution are crucial to information processing in neural networks. Biosensors that can visually monitor neurotransmitters are one of the vital tools to explore a variety of physiological and pathological activities. This article reviews recent advances in monitoring neurotransmitters with high temporal and spatial resolution, and introduces the latest fluorescent imaging methods for typical neurotransmitters, including glutamate, dopamine, γ-aminobutyric acid and acetylcholine. The article also summarizes the basic principles, advantages and disadvantages of various visually detection methods, and provides systematic suggestions for designing neurotransmitter sensors with high temporal and spatial resolution.

Advances in the research and applications of orange fluorescent protein / 生物工程学报

Fluorescent proteins can be used as probes to investigate intercellular molecular interactions and trace the pathway of specific metabolites, thus providing a detailed and accurate description of various metabolic processes and cellular pathways in living cells. Nowadays, the existing fluorescent proteins cover almost all spectral bands from ultraviolet to far-red. These fluorescent proteins have been applied in many fields of bioscience with the help of high-resolution microscopy, making great contributions to the development of biology. It is generally agreed that orange fluorescent proteins refer to the fluorescent proteins at the spectral range of 540-570 nm. In recent years, researches on orange fluorescent proteins have made great progress, and they have been widely applied in the field of biology and medicine as reporter protein and fluorescence resonance energy transfer as fluorescent receptor. This paper reviews the studies in the field of orange fluorescent proteins over the last 15 years, with the special focus on the development and application of orange fluorescent proteins to provide the basis for the future studies.

Experimental observation of transplantation of rabbit corneal stromal cells with LV-EGFP<i> in vitro</i> / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate the survival time and distribution of rabbit corneal stromal cells(CSCs)after transplantation of rabbit corneal <i>in vitro</i>. <p>METHODS: Primary rabbit CSCs was cultured <i>in vitro</i> and identified by immunohistochemical staining. using lentivirus(LV)with marker gene enhanced green fluorescent protein(EGFP)transfection rabbit CSCs, the growth status and fluorescence intensity of the transfected cells were observed under an inverted fluorescence microscope. The <i>in vitro</i> animal experiments were randomly divided into 2 groups. experimental group lines of LV-EGFP tag of rabbit CSCs suspension stromal injection, control group amount of normal saline injection corneal stroma, Frozen sections were taken 1wk and 1mo after surgery to observe the fluorescence of transplanted CSCs, and hematoxylin-eosin(HE)was used to observe the tissue morphology of paraffin sections. <p>RESULTS: LV-EGFP transfected rabbit CSCs showed a small amount of fluorescence after 24h under an inverted fluorescence microscope, with the strongest at 96h and 110h. There was no significant difference in the morphology of the transfected CSCs and normal CSCs. Green fluorescence can be seen in the stromal layer of the cornea in the experimental group at 1wk and 1mo, while there is no green fluorescence in the control group. Paraffin section for 1wk showed obvious epithelial cell hyperplasia and slight corneal edema in the experimental group, and a small amount of inflammatory cell infiltration. 1mo after surgery, the epithelial cell hyperplasia was weakened in the experimental group, and no corneal layer edema was observed. No obvious abnormality was found in the control group for 1wk and 1mo. <p>CONCLUSION: Extracorporeal corneal stroma transplantation of LV-EGFP labeled rabbit CSCs can survive at least 1mo in the corneal and is compatible with adjacent tissues.

Lentiviral vector mediated enhanced green fluorescent protein screening for stably transfected rabbit bone marrow mesenchymal stem cells / 西安交通大学学报(医学版)

Objective: To isolate, culture and identify rabbit bone mesenchymal stem cells (BMSCs) so as to explore the optimal conditions for lentiviral vector-mediated enhanced green fluorescent protein (eGFP) infection in rabbit BMSCs and screen stable transfected BMSCs in rabbits. Methods: BMSCs were obtained by whole bone marrow adherence method. The osteogenic, chondrogenic and adipogenic differentiation of BMSCs was made by alizarin red, toluidine blue and oil red O staining, respectively. The expressions of CD44 and CD90 were detected by immunofluorescence. The concentration of puromycin was used to screen the minimum lethal concentration of BMSCs; the lentiviral vector with multiplicity of infection (MOI) of 50, 100, 150 and 200 mediated eGFP BMSCs were infected; the fluorescence expression was observed under an inverted microscope, and the stable transformation system was screened with puromycin. Results: When MOI was 150, lentiviral vector-mediated eGFP infection of rabbit BMSCs was the most efficient. The optimum concentration of puromycin for stable transfection of rabbit BMSCs was 1.0 μg/mL. Conclusion: Rabbit BMSCs were successfully cultured in this experiment. The stem cells were labeled with lentivirus-mediated GFP and stable transfected rabbit BMSCs were screened. A simple and effective stem cell labeling method was established to label BMSCs in vivo.

Construction and application of mCherry red fluorescent protein fusion expression system in lactic acid bacteria / 生物工程学报

In order to enrich the library of domestic research about new red fluorescent marker in lactic acid bacteria (LAB), we described a new fusion expression system in Lactobacillus plantarum WCFS1 based on the pSIP vector. This system contained red fluorescent protein mCherry as a marker and bile salt hydrolase gene (bsh) as a reporter gene. Moreover, in this study, four different promoters (PsppA, PldhL, P32 and PslpA) were used to regulate the expression of the fusion protein mCherry-BSH, completing the inducible and constitutive expression in lactic acid bacteria. The recombinant protein mCherry-BSH presented activity of red fluorescence and bile salt hydrolase (BSH). The successful construction of the fusion expression system in LAB using a red fluorescent protein mCherry provides favorable conditions for the distribution, intestinal colonization and survival rate of lactic acid bacteria, so as to reveal the function mechanism of its probiotic characteristics; and the system also could lay the foundation for researches on protein expression, cellular localization and properties identification of active protein in lactic acid bacteria.

Fluorescence tracing of umbilical cord blood mesenchymal stem cells in transplantation treatment of scalded wound in mice / 国际检验医学杂志

Objective Using the previously established mesenchymal stem cells strain derived from human fetal umbilical cord blood (FUCB-MSCs) to culture then label enhanced green fluorescent protein (EGFP) , and to observe skin repair effects of FUCB-MSCs by GFP tracing after exogenous FUCB-MSCs transplantation on to scald wound models of SCID mice.Methods FUCB-MSCs were labeled GFP by transfection with the recombinant retrovirus containing EGFP gen;The established SCID scald mice model were randomLy divided into 3groups, low dose group, high dose group and control group, 6rats each group, 2wounds each mouse, 12wounds in total, then were tail intravenous injected into 0.2mL 1×106, 0.2mL 2×106 GFP-FUCB-MSCs cells, and same volume of medium respectively.On 9days after transplantation, the sections from scald wound area were observed the expression of GFP under the fluorescence microscope and the others were analyzed by the bright-field microscopy after HE staining, and the area of wound surface and the number of wound cells were compared simultaneously.Results After 48h, expression of EGFP in FUCB-MSCs can be seen under the fluorescence microscope, positive rate of GFP was>80％, and after 6weeks GFP expression is still stable, besides, the positive expression of human GFP can be observed after transplantation and there were no fluorescence decay in transplantation after 3weeks.Compared with the control group, there was a significant difference in wound area and wound cell number in the low and high-dose group (P<0.05) .ConclusionGFP can be used as a tracking marker to label FUCB-MSCs during transplantation treatment.It indicates that exogenous FUCB-MSCs can migrate to the scalded wounds via blood circulation system and continuously participate in the repair through SCID mouse.

Preparation and in vitro evaluation of redox-sensitive polypeptide vector for co-delivery of gene and chemotherapeutic drugs / 第二军医大学学报

Objective To prepare a lipoic acid (LA) modified intrinsically disordered protein-cytosol-localizing internalization peptide 6 (CL) nanocomplex (LA-CL) entering cells by non-endocytosis mechanism for co-delivery of gene and chemotherapeutic drugs, and to investigate its transfection efficiency and cellular uptake on human embryonic kidney cell line HEK293 cells and its release behavior in vitro. Methods We synthesized four disulfide cross-linked lipoic acid modified LA-CLss(1-4) at different cross-linked degrees using different mass fractions (2.5%, 5%, 10% and 20%) of cysteine as cross-linking agent. The construction of LA-CLss was characterized by1H nuclear magnetic resonance (1HNMR) and gel permeation chromatography. The LA-CLss/plasmid enhanced green fluorescent protein (pEGFP) nanocomplexes were self-assembled with LA-CLss and pEGFP at different nitrogen/phosphorus (N/P) ratios (2.5, 5, 10, 20, 40 and 80). The size and zeta potential of LA-CLss/pEGFP nanocomplexes were determined by particle size analyzer, and the pEGFP enrichment capacity of LA-CLss was determined by agarose gel electrophoresis. The docetaxel (DTX)-loaded micelles were prepared by ultrasonic emulsification, and the critical micelle concentration of LA-CLss3 was determined by pyrene fluorescence probe spectroscopy. The LA-CLss/pEGFP nanocomplexes were co-cultured with HEK293 cells, and the transfection efficiencies of LA-CLss/pEGFP nanocomplexes at different cross-linked degrees were investigated. Results1 HNMR results showed the LA-CLss was successfully synthesized. When N/P ratio was 40, the transfection efficiency of LA-CLss3/pEGFP nanocomplex by HEK293 cells was significantly higher than that of LA-CL/pEGFP, LA-CLss1/pEGFP, LA-CLss2/pEGFP and LA-CLss4 nanocomplexes. The encapsulation efficiency and drug loading of docetaxel-loaded micelles prepared by ultrasonic emulsification were (85.25±0.04)% and (8.81±0.02)%, respectively. Cellular uptake test showed that the gene could be effectively delivered into the HEK293 cells by the LA-CLss micelles. In vitro release experiments showed that the LA-CLss micelles had redox-responsive drug release behavior. Conclusion The prepared LA-CLss/DTX/pEGFP nanocomplex is expected to become an efficient vector for co-delivery of gene and chemotherapeutic drugs.

Tracking of herpesviruses: what have been seen and will be seen? / 生物工程学报

Viral infection of cells is a highly intricate process that involves the complex virus-cell interactions. Recently, virologists can monitor the virus life cycle at the primary infection site in real-time using various virus tracking techniques. Herpesviruses, a class of large enveloped DNA viruses, are important pathogens threatening the health of humans and animals. This review discussed the applications of different virus tracking techniques in herpesvirus studies, to provide new insights into virus-cell interactions and replication mechanisms of herpesviruses. Though the techniques have widely been exploited, some issues need to be addressed, such as the selection of the optimal site to insert reporters and the inability to track the whole process of the virus life cycle. With the updated tracking techniques, hopefully, more complex replication mechanismsof herpesviruses will be revealed in detail.

Screening efficient constitutive promoters in Corynebacterium glutamicum based on time-series transcriptome analysis / 生物工程学报

Promoter, an essential regulatory element, is widely used for metabolic engineering of industrial strains. Corynebacterium glutamicum is an important industrial workhorse to produce various amino acids. However, strong constitutive promoters that are applicable to C. glutamicum are rarely reported. In this study, we first performed a time-series transcriptome analysis of a glutamate hyper-producing strain C. glutamicum SL4 by using RNA-Seq. Overall, we picked 10 samples at different time during the fermentation process. By analyzing the time-series transcriptome data, we selected 10 candidate genes with the highest transcriptional level. These genes were all transcribed stably during the fermentation process. We subsequently cloned the promoter sequences and evaluated the promoters' strength in strain SL4 using a red fluorescent protein reporter system. To evaluate the universality of the promoters in different C. glutamicum strains, we further tested the performance of some promoters in wild type C. glutamicum strains, including ATCC 13869 and ATCC 13032. The strongest promoter was further characterized using LacZ as a reporter in all the three C. glutamicum strains. Finally, we successfully obtained three constitutive promoters with universality, PcysK, PgapA and PfumC. PcysK is the most efficient promoter among the three C. glutamicum strains. In strains SL4 and ATCC 13869, the strength of PcysK is 2-fold of the strong inducible promoter Ptac using the red fluorescent protein as a reporter and 4-fold of Ptac using LacZ as a reporter. Moreover, the strength of PcysK reaches 30%-40% of Ptac in strain ATCC 13032. The promoter PcysK is identified as a strong promoter for the first time, which can be used as an efficient biobrick for metabolic engineering of synthesis pathways in C. glutamicum.

Construction of lung tumor cells using RFP and Fluc dual-labeled system / 国际生物医学工程杂志

Objective To establish a human lung cancer cell line that can stably express firefly luciferase (Fluc) and red fluorescent protein (RFP) gene so as to lay the foundation for the further establishment of a live-imaging lung cancer xenograft model in nude mice and therapeutic research.Methods The lentiviral vector pHBLV-FlucRFP containing luciferase and red fluorescent protein was constructed and then transfected into 293T cells for virus packaging.The complete virus was used to infect human lung cancer cell lines A549,H1975 and human B-cell lymphoma cell line K562.The stable cell lines were obtained by puromycin selection.Fluorescence microscopy and quantitative PCR were used to confirm the RFP and Fluc expression.Results The lentiviral vector pHBLV-FlucRFP was successfully constructed.Cancer cell line A549,H1975 and K562 stably expressing Fluc and RFP was obtained.The real-time quantitative PCR results showed that the relative expression of Fluc gene in the three stable infected cells was much higher than that in the corresponding wild-type cells,and the differences were statistically significant(all P＜0.05).Conclusion The human lung cancer cell line A549,H1975 and human B-cell lymphoma cell line K562 with dual expression of RFP and Fluc were obtained,which provided a new model of fluorescent cells for in vivo imaging of immunodeficient mouse models such as nude mice.

Construction ,Expression and Characteristic Analysis of Recombinant Human TIM-4-EGFP Fusion Protein / 华中科技大学学报(医学版)

Objective The present study aimed to explore the expression and purification of a fusion protein of human TIM-4 and EGFP in Escherichiacoli(E.coli)and evaluate its bioactivity.Methods The cDNA fragments of human TIM-4 and EG-FP genes were respectively amplified by RT-PCR and cloned into prokaryotic expression vector pET-28a. The constructed re-combinant plasmid pET-28a-TIM-4-EGFP was transformed to E. coli BL21 (DE3)for the expression under the induction of IPTG.The expressed protein was purified by Ni-NTA resin.Recombinant protein was analyzed by SDS-PAGE and Western blotting ,and its binding activity to the apoptotic cells was detected under the fluorescence microscope.Results The TIM-4-EG-FP vector was constructed and expressed in E. coli. The TIM-4-EGFP fusion protein was identified and verified by SDS-PAGE and Western blotting.Our results demonstrated that all the TIM-4-EGFP fusion proteins recognize and bind directly to apoptot-ic cells ,but not to viable cells.We further verified that the interactions of TIM-4-EGFP with apoptotic cells were blocked by TIM-4-Ig fusion proteins.Conclusion We successfully constructed a fusion protein encoding human TIM-4 and EGFP ,and ex-pressed it in E.coli. The fusion protein shows a readily obtainable source of biologically active TIM-4 ,which has considerable potential for further studies on human TIM-4 and its receptor.

Dynamic distribution of calmodulin labeled with red fluorescent protein in the polar growth of Aspergillus fumigatus / 中华皮肤科杂志

Objective To construct a native promoter-regulated Aspergillus fumigatus strain containing red fluorescent protein-labeled calmodulin (CaM-RFP),and to observe the dynamic distribution of calmodulin during the growth of Aspergillus fumigatus.Methods Bilateral flanking sequences of Aspergillus fumigatus calmodulin gene were designed,and plasmids containing the two flanking sequences and mRFP-Aspergillus fumigatus pyrG gene (mRFP-AfpyrG) were amplified separately.The final linear PCR product for transformation was generated from the above three PCR products by fusion PCR.Then,the above linear fragment was transferred into the Aspergillus fumigatus strain by protoplast transformation,so as to construct the CaM-RFP Aspergillus fumigatus strain.The monoclonal colony was picked from the screening medium and subjected to culture.Then,the stablest fluorescent monoxenic strain of Aspergillus fumigatus was selected,and the transformant was verified by PCR.The recombinant strain and wild-type stain were cultured on solid nutrient media separately,and the morphology of these strains was observed by fluorescence microscopy at different time points.Additionally,the above 2 strains were cultured in liquid media separately,and XTT assay was performed to evaluate the growth activity of strains.Microscopy was also conducted to dynamically observe the CaM-RFP Aspergillusfumigatus strain,and analyze the spatial and temporal distribution of calmodulin during the growth and development of Aspergillus fumigatus.Results The fluorescent phenotype and PCR identification results both indicated the successful construction of the CaM-RFP Aspergillus fumigatus strain.The growth activity at 24 hours did not differ between the recombinant strain and wild-type stain (A490:0.689 ± 0.081 vs.0.678 ± 0.054,t =1.32,P ＞0.05),so did the morphology.During the polarized growth of Aspergillus fumigatus,calmodulin was always at the top of the hyphae,germination site of the hyphal branch and the top of new branches.Conclusion Calmodulin may be involved in the regulation of spore germination and polar hyphal growth of Aspergillus fumigatus.

Achievement of constitutive fluorescent pLEXSY-egfp Leishmania braziliensis and its application as an alternative method for drug screening in vitro

BACKGROUND Gene reporter-fluorescent cells have emerged as alternative method for drug screening. OBJECTIVE Achievement of constitutive expression of fluorescent protein GFP by Leishmania braziliensis as alternative method for drug screening. METHODS L. braziliensis-GFP was generated using Leishmania tarentolae pLEXSY-egfp for constitutive expression of GFP. Fluorescent cells were selected and subjected to standardisation tests of anti-promastigote and anti-intracellular amastigote assays. FINDINGS Our results showed that L. braziliensis-GFP method is faster and more sensitive than Allamar Blue-resazurin. MAIN CONCLUSION Transfected parasites maintained stable fluorescence after successive in vitro passages and pLEXSY system can be used to achieve non-L. tarentolae fluorescent cells.