Expression of the reporter LacZ driven by human dentin sialophosphoprotein promoter in human dental mesenchymal cells / 生物工程学报

The expression of dentin sialophosphoprotein (DSPP) is the marker for cells differentiated into odontoblasts. This study attempted to analyze the DSPP promoter and build the reporter LacZ expression system driven by this promoter, which allows convenient and quick detection of odontoblast cells. First, we separated the human dental mesenchymal cells in which the expression of DSPP can be effectively induced by dexamethasone. Second, four 5' flanking regions of human DSPP gene (- 4 000-+54, -2 500-+54, -1 447-+54 and -1 027-+54) were analyzed, the results showed that the highest promoter activity lied in the -2 500-+54 region. The promoter activity is reduced when the 5' flanking region was extended from -2 500 to -4 000 bp upstream from the transcription start site; The promoter activity are also decreased when the 5' flanking regions were shorted from -2 500 to -1 447 bp and from -1 447 to -1 027 bp, indicating that potential suppresser elements are lied in the region between -4 000 and -2 500 bp and potential activator elements are lied in the region between -2 500 and -1 027 bp. Then we constructed the lentiviral report vector phDSPP-LacZ containing the -2 500-+ 54 promoter region in front of the LacZ gene. The expression of LacZ was detected using X-Gal staining in both human dental mesenchymal cells and immortalized human dental mesenchymal cells infected with phDSPP-LacZ. The phDSPP-LacZ lentiviral vector may provide a more convenient method to detect the expression of DSPP in human odontogenic differentiation, tooth development and tooth regeneration studies.

Comparison of an ELISA assay for the detection of adhesive/invasive Neospora caninum tachyzoites / Comparação de um ensaio de ELISA para a detecção de taquizoítas adesivos/invasivos de Neospora caninum

Neospora caninum belongs to the phylum Apicomplexa, the causative agent of neosporosis, which leads to economic impacts on cattle production. A common feature among apicomplexan parasites is the invasive process driven mostly by the parasite. As a first evaluation of candidate molecules that play a possible role by interfering in this invasive process, the in vitro invasion assay is a fast and direct way to screen future agonists or antagonists. This work involved the development of a new cell culture ELISA and transient β-galactosidase activity applied to the semi-quantitative detection of N. caninum in Vero cell culture. Cell culture ELISA is based on histochemistry and immunology, resulting in a colorimetric reaction. The β-galactosidase activity was obtained by the transient transfection of the lacZ gene under control of RPS13 promoter of N. caninum. These methods were used to evaluate the effects of temperature (37°C and 85°C) on the invasion and adhesion of tachyzoites. The three tested methods (real time PCR, β-galactosidase activity and ELISA) showed a similar pattern, indicating that different methods may be complementary.

Neospora caninum, parasita do filo Apicomplexa, é causador da neosporose, doença responsável por perdas econômicas importantes na pecuária. Um fator comum entre os apicomplexas é o processo de invasão majoritariamente dirigido pelo parasita. Dentre as primeiras avaliações de moléculas candidatas, que possivelmente interferem no processo de invasão, o ensaio de invasão in vitro é um meio rápido e direto de selecionar futuros agonistas ou antagonistas. Este trabalho desenvolveu um novo ELISA baseado em cultura (Cell-culture ELISA) e um ensaio que mede a atividade transiente de β-galactosidase, aplicados para a detecção semiquantitativa de N. caninum em células Vero. Cell-culture ELISA é baseado em histoquímica e imunologia, resultando em uma reação colorimétrica. A atividade da β-galactosidase foi obtida pela transfecção transiente do gene LacZ sob controle do promotor RPS13 de N. caninum. Esses métodos avaliaram os efeitos da temperatura (37°C e 85°C) sobre a invasão e adesão. Os três métodos testados (real time PCR, atividade de β-galactosidase e ELISA) mostraram um padrão similar, indicando que diferentes métodos podem ser complementares. Adicionalmente, esse ELISA é adequado para aplicação em laboratórios carentes de uma complexa estrutura para métodos de detecção moleculares.

Generation of Adiponectin Gene Knock-out and LacZ Gene Knock-in Mouse Model / 生物化学与生物物理进展

Adiponectin is an adipocyte-derived secretory protein. It was found to be associated with insulin resistance, inflammation and arteriosclerosis. To further study the biological function and expression of adiponection in vivo, adipoenctin gene knock-out and LacZ gene knock-in mouse model was constructed. Gene targeting strategy was designed to replace part of exon 2 and exon 3 of adiponectin gene with full length LacZ gene in frame with remaining upstream ATG and signal peptide sequence of exon 2. The targeting vector (Adipo-LacZ-XpPNT) was constructed and verified by restriction enzyme digestion and sequencing. CJ7 ES cells were transfected with targeting vector linearized by NotⅠ digestion, selected in the medium containing both G418 and ganciclovoir. Resistant clones were screened by PCR and further confirmed by Southern blot for correct homologous recombinants. Chimera mice were obtained by routing microinjection of homologous recombined ES cells into blastocysts. After mating, mice heterozygous and further homozygous for adiponectin knockout and LacZ gene knock-in were established. Expression of both endogenous adiponectin and exogenous LacZ gene in mouse tissues and sera were detected by RT-PCR, Northern-blot, Western blot and ELISA. The results show that adiponectin was disrupted at both mRNA and protein levels. LacZ gene is expressed exclusively in adipose tissue of mutant mice. Its expression profile is identical to endogenous adiponection. Unexpectedly, LacZ activity could not be detected in both adipose tissue and serum although LacZ protein can be detected in adipose tissue but not in serum of mutant mice. In conclusion, mice homozygous for adiponectin knockout and LacZ gene knock-in have been successfully constructed. Mutant mice display LacZ expression profile identical to endogenous adiponectin albeit neither LacZ activity nor protein can be detected in serum of mutant mice.

Effects of recombinant antisense c-myc adenovirus in induction of differentiation of HL-60 cells / 第三军医大学学报

Objectives To evaluate the potential of antisense c myc gene therapy for acute promyelocytic leukemia by investigating the biological effects and molecular mechanisms in induction of differentiation of HL 60 cell line using recombinant antisense c myc adenovirus (Ad AS c myc). Methods Cultured HL 60 cells treated with Ad AS c myc or Ad LacZ with polybrene and protamine sulfate were analyzed by X gal staining, morphology, MTT, flow cytometric analysis, RT PCR, and immunocytochemical techniques in vitro . Results HL 60 cells could be transfected effectively by Ad LacZ+protamine sulfate (79.8%). The level of c myc transcription and the version could be strongly inhibited by Ad AS c myc in the transfected HL 60 cells. Ad AS c myc could strongly inhibit the cell growth in HL 60 cells (51%). Ad AS c myc could reduce the ratio of nuclear/cytoplasm, and increase the activity of peroxidase in HL 60 cells. Ad AS c myc could lead to the blocking of G 0/G 1 phase in HL 60 cells. Ad AS c myc could also increase the expression of c fos in HL 60 cells. Conclusion The expression of Ad AS c myc can inhibit the growth and induce differentiation of HL 60 cells in vitro . The biological effects of Ad AS c myc may be closely associated with the activity of peroxidase and c fos gene in HL 60 cells. Ad AS c myc is of clinical potential in gene thera py for acute promyelocytic leukemia.

Construction and identification of recombinant adenovirus shuttle plasmid pAdCMVLacZ / 第三军医大学学报

Objective To construct replication deficient adenovirus vector AdCMV lacZ Methods Recombinant adenovirus shuttle plasmid pAdCMVlacZ was first constructed and then lacZ cDNA cloned into Hind Ⅲ and Eco R Ⅴ of adenovirus shuttle plasmid pAdCMV by conventional methods Results The restriction enzymatic map of pAdCMVlacZ accorded with theoretic analyses and pAdCMVlacZ showed blue bacterium groups under the existence of revulsant and X gal Conclusion The adenovirus shuttle plasmid pAdCMVlacZ has been constructed successfully

Construction and identification of recombinant adenovirus vector expressing LacZ gene / 医学研究生学报

Objective:AIM To obtein a recombinant replication-deficient adenovirus expressing LacZ protein. Methods:The recombinant adenovirus vector engineered to express LacZ gene(Ad-LacZ) was constructed by recombination in E.coli-BJ5183.The replication-deficient adenovirus was then packed in HEK293 cells after transfection with the construct and subsequently identified by X-gal staining,electron microscopic observation and dot blotting.The expression of LacZ in HeLa cells infected by Ad-LacZ could be detected by X-gal stain. Results:Recombinant adenovirus expression vector of LacZ was successfully reconstructed.And the titer of Ad-LacZ virus reached 1.58?10~(9) pfu/ml.Under transmission(electron) microscope,adenoviral inclusions could be found in the nucleus of the infected HEK293 cells. Ad-LacZ virus was comfirmed to be replication-deficient by dot blotting.And the expression of LacZ was observed in the infected HeLa cells.The gene transfer capability of the recombinant virus was correlated with multiplicity of infection and the infection time. Conclusion:Recombinant adenovirus expression vector of LacZ was successfully reconstructed.

Establishment of double reporter transgenic mice for monitoring Cre recombinase activity / 第三军医大学学报

Objective To establish a double reporter transgenic mice for monitoring Cre recombinase activity. Methods ZAP DNA fragment with lacZ and human alkaline phosphatase (hAP) gene was microinjected into the male pronucleus of 554 fertilized eggs from C57BL/6 mice. The founder mice and their progeny were screened for integration of transgene into the mouse genome by PCR and Southern blotting. The expression of lacZ transgene at early embryos from F1 generation mice was analyzed by X gal staining. Results A total of 398 survival ZAP DNA injected fertilized eggs were transfered to the oviducts of 21 pseudopregnant recipient mice. Of the 21 recipient mice, 13 became pregnancy and gave birth to 68 offspring mice. The zygote survival rate and birth rate were 71% (398/554) and 17% (68/398), respectively. Of the 68 offspring mice, 9 mice (5 males and 4 females) were identified by PCR and Southern blot analysis. Total integration rate and efficiency of transgene was 13% (9/68) and 1.6% (9/554), respectively. Nine mice as the founders were back crossed to set up F1 generation with other inbred C57BL/6 mice. Out of 9 transgenic mice, transmission of reporter gene in F1 offspring mice followed Mendelian rules, but the expression of lacZ protein was detected at the early embryonic stage (13.5 days postcoitum) in only 3 mice. Conclusion A double reporter transgenic mice for monitoring Cre recombinase activity is established.

THE INFLUENCING ELEMENTS AND OPTIMIZATION OF X-gal STAINING METHOD IN THE STUDY OF TRANSPLANTATION / 解剖学报

Objective To study the influencing elements in x-Gal staining method and optimize the reactive conditions so that nonspecific background can be eliminated and grafted exogenous cells carrying LacZ gene can be discerned correctly. Methods C17 2 cells (carrying lzcZ gene) were injected into the right lateral ventricle both in the adult and newborn animals. After one week they were perfused using two methods, then the slices were stained at different pH and incubating time respectively. The X-gal positive cells in hippocampus were counted under light microscope. Results Background staining in this method has close correlation with the species and age of the host animals and it decreases when pH is higher or incubating time is shorter. The results are the best when pH 9 5 and the incubating time is 1*!h.Conclusion The reliability of X-gal staining method depends on optimization of several parameters, including pH, incubating time, perfusion etc. It is necessary to establish the correspondent controls.;