Construction of hepatocyte-specific Sirt3 gene knockout mouse model / 安徽医科大学学报

Objective @#To construct hepatocyte-specific silence information regulator 3 ( Sirt3 ) gene knockout (Sirt3Δhep ) mice by Cre-loxP technique , and to provide an important animal model for further studying the biological function of the hepatocyte Sirt3 gene in diseases . @*Methods @#LoxP-labeled Sirt3flox/flox mice were mated with Alb-Cre homozygous (Alb-Cre + / + ) mice , and the F1 generation Sirt3flox/ - /Alb-Cre + / - mice were then mated with Sirt3flox/flox mice , and the F2 genotype of Sirt3flox/flox/Alb-Cre + / - mice were the Sirt3Δhep mice constructed in this ex- periment. Sirt3flox/flox/Alb-Cre - / - (Sirt3flox/flox ) mice were the control mice . Mouse tail genome DNA was extracted and PCR was used to identify the genotypes of the offspring mice . Immunofluorescence was used to detect Sirt3 ex- pression in mouse hepatocytes . Primary hepatocytes and tissue proteins of Sirt3Δhep mice were extracted , and the ex- pression of Sirt3 in mouse hepatocytes and other tissues was verified by Western blot. HE staining was used to ob- serve mice ′s liver , heart , spleen , and lung tissue structure . @*Results @#Sirt3Δhep mice were successfully identified .Immunofluorescence and Western blot results demonstrated a significant decrease in the expression of Sirt3 in the hepatocytes of these mice compared to the control group ( P < 0. 01) . At the same time , there was no significant difference in the expression of Sirt3 in the heart , spleen , kidney , and lung tissues of Sirt3Δhep mice compared with the control group (P > 0. 05) . The results of HE staining showed that the histological characteristics of the liver , heart , spleen , lungs , kidneys , and other major organs of Sirt3Δhep mice were not significantly different from those of the control group mice . @*Conclusion @#Hepatocyte-specific Sirt3 gene knockout mice are successfully constructed , which provides an animal model to explore further the role and molecular mechanism of the hepatocyte Sirt3 gene in diseases .

Breeding and genotyping of T lymphocyte-conditional Spi1 knockout mice / 安徽医科大学学报

Objective @#To breed and identify the T lymphocyte-conditional Spi1 knockout mice for the further in- vestgation of the specific role of Spi1-encoded protein PU. 1 . @*Methods @#The Lck-Cre mice were mated with Spi1 flox/flox mice to obtain Lck-Cre ×Spi1 flox/flox mice (T lymphocyte-specific Spi1 knockout mice) , and the genotype was determined by polymerase chain reaction (PCR) and agarose gel electrophoresis . Magnetic beads were used to sort out the splenic T lymphocytes , and the knockdown efficiency of PU. 1 in T cells was detected by Western blot , quantitative real-time PCR ( qPCR) and flow cytometry. @*Results @#The Lck-Cre ×Spi1 flox/flox mouse genotype was stably inherited . Compared with Spi1 flox/flox mice , the expression level of PU. 1 was significantly reduced in splenic T cells of Lck-Cre ×Spi1 flox/flox mice . @*Conclusion @#In this study , the T lymphocyte-specific Spi1 knockout mice was successfully constructed by applying Cre/LoxP system and CRISPR/Cas9 technology , which provided a reliable an- imal model for the subsequent experiments of the specific role of PU. 1 in T cell-related diseases .

Establishment and genotype identification of hepatic stellate cell-specific Grk2 gene knockout mouse model / 中国药理学通报

Aim To establish a stable hepatic stellate cell ( HSC ) -specific G protein-coupled receptor kinase 2 ( GRK2 ) knockout mice and provide the important animal model for further studying the biological function of GRK2 in HSC. Methods The loxP-labeled Grk2 gene mouse (Grk2

Construction of macrophage-specific MST1 knockout mouse model / 安徽医科大学学报

Objective @# To establish myeloid ( including macrophage and granulocyte) specific knockout mice of mammalian sterile line 20-like kinase 1 (MST1) gene for furtherinvestigating the role and the mechanism of MST1 in macrophages in related clinical diseases．@*Methods @#Mst1flox/flox LysM-Cre ( referred to as Mst1ΔM/ΔM hereafter) mice were generated by crossing Mst1flox/floxwith lysozyme (Lysm-Cre) mice．The loxP site and Cre gene were amplified by PCR for genotyping．The knockdown efficiency of MST1 in macrophages was verified by quantitative PCR and immunofluorescence．The main immune cell populations in the livers were detected by flow cytometry. @*Results@#Mst1flox/flox LysM-Cre (Mst1ΔM/ΔM ) was the genotype of macrophage specific knockout MST1 mice．The results of qPCR and immunofluorescence showed that the knock-out efficiency of MST1 was more than 70% in bone marrow- derived macrophages and peritoneal macrophages．Flow cytometry showed that macrophage knockout of MST1 had no significant effect on the main immune cell populations in the liver of mice．@*Conclusion @# Macrophage-specific knockout of MST1 mouse model is successfully established，which lays a foundation for further investigation on the role and mechanism of macrophage MST1 in clinical related disease.

Construction of the Pkd1 gene knockout mouse model with polycystic kidney disease based on CRISPR/Cas9 technology / 中华肾脏病杂志

Objective:To establish a conditional knockout mouse model of polycystic kidney disease 1 ( Pkd1) gene based on CRISPR/Cas9 and Cre-loxP gene editing technology, and to provide an animal model for in-depth research on the role of Pkd1 gene in the development of polycystic kidney disease. Methods:In-Fusion technology was used to construct a targeting vector. Corresponding gRNAs, Cas9 mRNAs, and donor vectors carrying the loxP site were prepared based on the Pkd1 gene, and injected into the fertilized eggs of C57BL/6N mice. The fertilized eggs were transferred to the fallopian tubes of female mice with pseudopregnancy. After the newborn mice were identified by PCR and sequencing analysis, Pkd1 flox/flox F0 generation positive mice were selected. The F0 generation positive mice were bred with wild-type mice, and F1 generation heterozygous mice with Pkd1 flox/+ genotype were selected for offspring. F2 generation homozygous mice with Pkd1 flox/flox genotype were obtained through internal expansion, and then hybridized with Cre positive Ggt1/ Cre mice. F3 generation mice with Pkd1 flox/+Ggt1 Cre genotype were obtained. F4 generation mice with Pkd1 flox/flox Ggt1 Cre genotype were obtained by self crossing or backcrossing with F2 generation Pkd1 flox/flox, namely kidney-specific Pkd1 gene knockout mice ( Ggt1-cKO mice). PCR method was used to identify the genotype of mice, and then the mice were divided into wild-type control (WT) group ( n=6), Pkd1 homozygous control (PKD) group ( n=6), and Ggt1-cKO knockout validation (CKO) group ( n=6) according to the gene identification results. Real-time fluorescence quantitative PCR (RT-qPCR) was used to detect the expression of Pkd1 mRNA in the kidneys and other organs of mice in each group. HE staining was used to detect the pathological changes in renal tissues of mice in each group. The automatic biochemical detector was used to detect the blood urea nitrogen and serum creatinine levels of mice, and the kidney coefficient was calculated. Results:The PCR detection results showed that the genotype of offspring mice in CKO group was consistent with Pkd1floxflox Ggt1 Cre. Pkd1 gene was only specifically expressed in the kidney, but not in other tissues. The RT-qPCR results showed that the relative expression of Pkd1 mRNA in the renal medulla of CKO group was significantly lower than that of WT and PKD groups. The kidney volume of the CKO group had increased by about twice compared to the WT group. Under the microscope, it could be observed that there were multiple vacuoles of varying sizes and shapes in the kidneys of the CKO group, and there was a significant increase in the interstitial space of the medullary tissue. The kidney coefficient, blood urea nitrogen, and serum creatinine in the CKO group were significantly higher than those in the WT and PKD groups (all P<0.05). Conclusion:Based on CRISPR/Cas9 and Cre-loxP gene editing technology, Pkd1 gene kidney conditional knockout mice can be successfully constructed, providing an animal model for further studying the action mechanism of Pkd1 gene in polycystic kidney disease.

Effect of FKBP38 protein on endometrial precancerous lesions and mechanism / 中国药理学通报

Aim To build the model of the gene FKBP38(FK506 binding protein 38)conditional knock out in uterus and then investigate the effect on endometrial precancerous lesions and the underlying mechanism.Methods Transgenic mice whose FKBP38 gene was flanked with loxP were constructed by embryo microinjection. The conditional knockout of FKBP38 was obtained by breeding mice harboring two loxP sites in FKBP38(FKBP38

Construction of a novel time-specific NLRP3 transgenic mouse model by Cre-LoxP system / 中国药理学通报

Aim To construct and identify a new time-specific NLRP3 point mutation transgenic mouse model by Cre-LoxP system. Methods Cre-LoxP system was used to generate NL-RP3

Influence of specifically knocking out AMP-activated protein kinase α1 subunit gene in excitatory neurons in brain energy metabolism and cognitive function in mice / 中华神经医学杂志

Objective:To investigate the changes of brain energy metabolism and cognitive function in mice with specifically knocking out AMP-activated protein kinase α1 subunit ( AMPKα1) gene in the excitatory neurons by Cre-loxP recombination system. Methods:Sixteen 6-month-old mice with genotype AMPKα1 flox/flox/Camk2a-Cre/ERT2 obtained by hybrid breeding were randomly divided into AMPKα1 knockout group ( n=8) and AMPKα1 wild-type group ( n=8). Mice in the AMPKα1 knockout group were intraperitoneally injected 0.1 mL tamoxifen (20 mg/mL, dissolved in corn oil) daily for a consecutive 5 d to control AMPKα1 gene knockout in the excitatory neurons; and mice in the AMPKα1 wild-type group were intraperitoneally injected 0.1 mL corn oil daily for a consecutive 5 d. Seven d after that, Morris water maze and T maze experiments were employed to detect the spatial learning and memory abilities and spatial working memory of these mice; chemical exchange saturation transfer imaging (CEST) was used to observe the glucose metabolism in the hippocampus and cortex surrounding the hippocampus; Western blotting was used to detect the AMPKα1 and glutamate receptor 1 (GluR1) protein expressions in the hippocampus and cortex surrounding hippocampus of two groups. Results:(1) Morris water maze showed that, as compared with those in the AMPKα1 wild-type group, mice in the AMPKα1 knockout group had significantly prolonged escape latency ([13.90±3.72] s vs. [22.40±6.28] s; [11.95±3.86] s vs. [22.39±9.77] s]) on the 3 rd and 4 th d of experiment, statistically decreased times crossing the platform ([5.25±1.83] times vs. [1.75±1.28] times, P<0.05). (2) T-maze experiment showed that as compared with that of the AMPKα1 wild-type group, the free alternation rate in mice of the AMPKα1 knockout group was significantly decreased ([73.21±9.16]% vs. [48.21±11.29]%, P<0.05). (3) CEST showed that the glucose metabolism levels in the hippocampus and cortex surrounding the hippocampus of AMPKα1 knockout group were significantly lower than those in AMPKα1 wild-type group (1.51±0.81 vs. 2.77±0.67; 1.31±0.83 vs. 2.42±0.95, P<0.05). (4) Western blotting showed that the AMPKα1 and GluR1 protein expressions in the hippocampus and cortex surrounding the hippocampus of the AMPKα1 wild-type group were significantly higher than those of the AMPKα1 knockout group (AMPKα1: 0.70±0.05 vs. 0.49±0.03, 0.98±0.04 vs. 0.64±0.06; GluR1: 1.22±0.18 vs. 0.60±0.11, 0.96±0.08 vs. 0.79±0.04, P<0.05). Conclusion:Specifically knocking out AMPKα1 in excitatory neurons can result in abnormal glucose metabolism in the brain of mice, and thus cause cognitive dysfunction, whose mechanism may be related to excitatory synaptic disorder caused by energy metabolism disorder.

Construction of mammary gland cell-specific SENP7 knockout mice by Cre-loxP system / 中国临床药理学与治疗学

AIM: To construct and identify the mammary gland cell-specific conditional knockout of SENP7 by the Cre-loxP system. METHODS: The homozygous SENP7

Engineering CrtW and CrtZ for improving biosynthesis of astaxanthin in Escherichia coli / 中国天然药物

This study engineered β-carotene ketolase CrtW and β-carotene hydroxylase CrtZ to improve biosynthesis of astaxanthin in Escherichia coli. Firstly, crtW was randomly mutated to increase CrtW activities on conversion from β-carotene to astaxanthin. A crtW* mutant with A6T, T105A and L239M mutations has improved 5.35-fold astaxanthin production compared with the wild-type control. Secondly, the expression levels of crtW* and crtZ on chromosomal were balanced by simultaneous modulation RBS regions of their genes using RBS library. The strain RBS54 selected from RBS library, directed the pathway exclusively towards the desired product astaxanthin as predominant carotenoid (99%). Lastly, the number of chromosomal copies of the balanced crtW-crtZ cassette from RBS54 was increased using a Cre-loxP based technique, and a strain with 30 copies of the crtW*-crtZ cassette was selected. This final strain DL-A008 had a 9.8-fold increase of astaxanthin production compared with the wild-type control. Fed-batch fermentation showed that DL-A008 produced astaxanthin as predominant carotenoid (99%) with a specific titer of 0.88 g·L without addition of inducer. In conclusion, through constructing crtW mutation, balancing the expression levels between crtW* and crtZ, and increasing the copy number of the balanced crtW*-crtZ cassette, the activities of β-carotene ketolase and β-carotene hydroxylase were improved for conversion of β-carotene to astaxanthin with higher efficiency. The series of conventional and novel metabolic engineering strategies were designed and applied to construct the astaxanthin hetero-producer strain of E. coli, possibly offering a general approach for the construction of stable hetero-producer strains for other natural products.

Construction and identification of mouse model with conditional knockout of p75 neurotrophin receptor gene in epidermal cells by Cre-loxP system / 中华烧伤杂志

Objective@#To construct and identify a mouse model with conditional knockout (cKO) of p75 neurotrophin receptor (p75NTR-cKO) gene in epidermis cells by Cre-loxP system.@*Methods@#Five p75NTRflox/flox transgenic C57BL/6J mice (aged 6-8 weeks, male and female unlimited, the age and sex of mice used for reproduction were the same below) and five keratin 14 promotor-driven (KRT14-) Cre+ /- transgenic C57BL/6J mice were bred and hybridized via Cre-loxP system. Five p75NTRflox/+ ·KRT14-Cre+ /- mice selected from the first generation of mice were mated with five p75NTRflox/flox mice to obtain the second generation hybrids. After the second generation mice were born 20-25 days, the parts of the mice tail were cut off to identify the genotype by polymerase chain reaction method. Four p75NTR gene complete cKO mice (6 weeks old) and 4 wild-type mice (6 weeks old) were selected and sacrificed respectively. The abdominal skin tissue and brain tissue were excised to observe the expression of p75NTR in the two tissue of two types of mice by immunohistochemical staining. The abdominal skin tissue of two types of mice was obtained to observe the histomorphological changes by hematoxylin and eosin staining.@*Results@#(1) Twenty second generation mice were bred. The genotype of 4 mice was p75NTRflox/flox·KRT14-Cre+ /-(p75NTR-/-), i. e. p75NTR gene complete cKO mice; the genotype of 5 mice was p75NTRflox/+ ·KRT14-Cre+ /-, i. e. p75NTR gene partial cKO mice; the genotype of 5 mice was p75NTRflox/flox·KRT14-Cre-/-, and that of 6 mice was p75NTRflox/+ ·KRT14-Cre-/-, all of which were wild-type mice. (2) The expression of p75NTR was negative in skin epidermis tissue of p75NTR gene complete cKO mice, while numerous p75NTR positive expression was observed in skin epidermis tissue of wild-type mice. Abundant p75NTR positive expression was observed in brain tissue of both wild-type mice and p75NTR gene complete cKO mice. (3) There was no abnormal growth of skin epidermis tissue in both wild-type mice and p75NTR gene complete cKO mice, with intact hair follicle structure.@*Conclusions@#Applying Cre-loxP system can successfully construct a p75NTR-cKO mice model in epidermis cells without obvious changes in skin histomorphology.

Mouse Cre-LoxP system: general principles to determine tissue-specific roles of target genes / 한국실험동물학회지

Genetically engineered mouse models are commonly preferred for studying the human disease due to genetic and pathophysiological similarities between mice and humans. In particular, Cre-loxP system is widely used as an integral experimental tool for generating the conditional. This system has enabled researchers to investigate genes of interest in a tissue/cell (spatial control) and/or time (temporal control) specific manner. A various tissue-specific Cre-driver mouse lines have been generated to date, and new Cre lines are still being developed. This review provides a brief overview of Cre-loxP system and a few commonly used promoters for expression of tissue-specific Cre recombinase. Also, we finally introduce some available links to the Web sites that provides detailed information about Cre mouse lines including their characterization.

Construction and identification of conditional islet βcell DEPTOR knockout mice / 实用医学杂志

Objective To study the function of Deptor gene on the regulation of diabetes mellitus in suc-cessfully constructed and identified islet β-cell conditionally DEPTOR knockout mice model. Method By cross-breeding Deptorflox/floxmice with Cre mice expressed conditional specifically in pancreatic β-cell,Deptorflox/+Cre+/-mice were acquired and their genotypic identification was then performed. As the mice model of this study, Deptorflox/floxCre+/-mice were generated by crossing Deptorflox/+Cre+/-mice with Deptorflox/floxmice.Genotypic identifica-tion was performed by PCR at the age of 3 weeks. Tamoxifen was administered through intraperitoneal injection to induce the activation of the Cre recombination in islet beta cells of 8 weeks mice.Double immunofluorescence label-ing was then applied to identify the knockout effect of DEPTOR gene. Results Ten Islets Deptor knockout mice models were successfully acquired after 10-month cross-breeding. Validated genotype by PCR analysis were Deptorflox/floxCre+/- and double immunofluorescence labeling showed a significant difference between knockout mice and rodent controls. Conclusion Our study successfully constructs the islets conditionally Deptor deleted mice model by using Cre-loxp recombination system,providing a promising appliable animal model for study of dia-betes mellitus pathogenetic mechanism.

Establishment of transgenic mice model with overexpression of neuritin in bone marrow / 实用医学杂志

Objective To establish transgenic mice model with over expression of neuritin in bone mar-row,for the further study on the function of neuritin protein in the treatment of peripheral neuropathy. Methods Two pairs of transgenic mice(loxp-stop-loxp-neuritin and lyz-Cre/+)were fed and propagated,the DNA from the mice tails extracted and the genotype of transgenic mice identified by PCR. The wild type mice with B6 were as-signed as the controls,and the immunofluorescence was used to detect the accuracy of the neuritinloxp/+ _lyz -Cre/+. Results The two trensgenetic homozygous mice had the ability to reproduce,and the hybrid offsprings were neuritinloxp/+_lyz-Cre/+,neuritinloxp/-_lyz-Cre/+,neuritinloxp/+_lyz-Cre/-,neuritinloxp/-_lyz-Cre/-. The re-sults were met with the Mendel′s law. The results of immunofluorescence showed that the expression of neuritin of neuritinloxp/+_lyz-Cre/+ mice in bone marrow was significantly higher than the wild type mice(P < 0.05). Con-clusion The PCR method is of high reliability for identification of sub pus genotype and the female neuritinloxp/+mice mating with the male lyz-Cre/+ ones is an effective way for obtaining the neuritinloxp/+_lyz-Cre/+ mice.

Construction of a Mouse Model of Hepatocyte Cell-specific Disruption of the FKBP38 Gene / 现代生物医学进展

Objective:To build the model of the gene FKBP38 (FK506 binding protein 38) conditional knock out in liver.Methods:Transgenic mouse whose FKBP38 gene was flanked with loxP was constructed by embryo microinjection.The FKBP38 gene was deleted by breeding mice harboring two loxP sites in FKBP38 (FKBP38fl/fl) with the mice bearing the expression ofCre recombinase mice driven by an album promoter.Afterward,the genotype of FKBP38 conditional knockout mice was analyzed.Results:①Relative hepatic FKBP38 mRNA levels showed significant difference between FKBP38 conditional knockout mice (FKBP38-/-) and wild type(P＜ 0.001).②Relative hepatic FKBP38 protein expression levels of FKBP38 conditional knockout mice (FKBP38-/-) were significantly different with wild type(P＜0.001).③Relative phosphorylation of hepatic p70 S6K and 4E-BP-1 protein of FKBP38 conditional knockout mice (FKBP38-/-) showed no significant difference,with slight decrease in phosphorylation of 4E-BP-1,compared with wild type.④No significant difference in expression of hepatic Bcl-2 between FKBP38-/-and wild type.Conclusions:The mouse model of the gene FKBP38 (FK506 binding protein 38) conditional knock out in liver is successfully built.

Establishment and Phenotype Analysis of SHBG Knockout Mouse Model / 中国生物工程杂志

Objective:To generate sex hormone binding globulin(SHBG) conditional knockout mice model.In order to investigate the physiological function of SHBG in vivo and to provide experimental means for the study of the relationship between SHBG and gestational diabetes mellitus.Methods:The mouse genomic DNA sequence of SHBG was verified through bioinformatic analysis.According to the SHBG genomic DNA sequence,the gene targeting and knockout vector were constructed.Transfection of the vectors to ES cells by electroporation was performed according to common protocol.Positive ES cells were screened and identified by PCR.Therefore,the dual selected ES cells were microinjected into blastula,then blastula transplantations into the host mice.The chimeric mice were mated with C57BL/6J mice,and the Flox mice were obtained after screening.The Flox mice were hybridized with EIIA-Cre transgenic mice,and the progeny of the SHBG gene knockout (SHBG-/-) mice were obtained by autocopuation for several times.Results:Several Flox homozygous mice and SHBG gene knockout mice were successfully obtained.Compared with control mice,homozygous mice of SHBG gene knockout were well developed and had reproductive ability.The growth and development of SHBG knockout mice were not significantly different from that of wild type mice.Conclusion:Homozygous mice model of SHBG gene knockout was successfully established,which laid the foundation for further study of the role of SHBG in the gestational diabetes.The SHBG gene knockout mouse model was successfully established and the preliminary phenotypic analysis was performed,which laid the foundation for further study on the role of SHBG in gestational diabetes mellitus.SHBG gene knockout mice were normal in appearance.Due to the limited number of samples and many unknown biological characteristics of gene knockout mice,it needs further study.

Gcm2 gene knock-out induces the hypoparathyroidism in adult mice / 中华内分泌代谢杂志

Objective To investigate the role of Glial cells missing 2 (Gcm2) in pathogenesis of hypoparathyroidism by knocking out Gcm2 gene in adult mice.Methods Tamoxifen was used to induce conditional knock-out of Gcm2 gene in Gcm2E2fl/flCre-ER mice.Genotypes of knock-out mice were identified by PCR.The protein expression level of Gcm2 was measured by Western blotting.The serum calcium and phosphorus were detected by the calcium and phosphorus assay kits, and the serum parathyroid hormone (PTH) level was detected by ELISA.Parathyroid cell proliferation was tested by Ki-67 immunohistochemical assay.The mRNA expression levels of PTH and calcium sensing receptor (CaSR) were detected by Real-time PCR.Bone mineral density was detected by micro CT.Results Gcm2 gene of parathyroid was confirmed to be knocked out by PCR.Compared with wild type and solvent control groups, Gcm2 knock-out group showed markedly lower protein expression of Gcm2, notably higher serum phosphorus and lower serum calcium and PTH concentrations (all P<0.01).The proliferation of parathyroid cells in Gcm2 knock-out mice were significantly higher(both P<0.01).The mRNA levels of PTH and CaSR in parathyroid gland of the knock-out group were significantly reduced (all P<0.01).Bone mineral density was significantly higher in Gcm2 knock-out group (all P<0.01).Conclusion Knockout of Gcm2 can lead to hypoparathyroidism in adult mice, indicating that Gcm2 is probably a therapeutic target for hypoparathyroidism.

Construction of a mutant strain of Streptococcus mutans with clpC-deletion to study the role of clpC ;gene in genetic competence / 中华微生物学和免疫学杂志

Objective To construct a mutant strain of Streptococcus mutans ( S.mutans ) with clpC-deletion and to investigate the role of clpC gene in genetic competence.Methods The fragment of clpC gene and the kanamycin resistant cassette flanked by two loxP sites were amplified by PCR.The purified fragment of clpC gene was cloned into pMD-19T simple vector to construct pCKX1.The pCKX1 vector was digested with ClaⅠ/EcoRⅠ, then blunted and introduced into lox71-KMR-lox66 to obtain pCKX2 vector via homologous recombination.The pCKX2 vector was linearized with SalⅠ and transformed into S.mutans UA159 strain.The positive strains constructed via homologous recombination were screened with kanamycin and transformed with the thermosensitive plasmid pCrePA.The KMR cassette was excised after incubating at 30℃ for 48 hours.Then the pCrePA plasmid was removed after overnight incubating at 37℃for the prepara-tion of clpC-deletion mutant.Total RNA were extracted from the S.mutans UA159 strain and the clpC-dele-tion mutant strain respectively, and then reverse transcribed into first strand cDNA.The target gene frag-ments were amplified by RT-PCR and analyzed by the agarose gel electrophoresis and sequencing.After be-ing verified by PCR and sequencing, the S.mutans UA159 strain and the clpC-deletion mutant strain were re-spectively transformed with E.coli-S.mutans shuttle vector pDL276 to observe the competence development induced by the competence-stimulating peptide (CSP).Results The PCR and sequencing results showed that the pCKX2 vector and the mutant strain with clpC-deletion were constructed successfully via homologous recombination.No clpC gene was detected in the clpC-deletion mutant as indicated by RT-PCR analysis.The formation of competent clpC-deletion mutant was delayed and the competence state was prolonged as com-pared with its parent strains.Conclusion The clpC gene negatively regulated the formation of competent S.mutans.

Molecular regulation of kidney development / 대한해부학회지

Genetically engineered mice have provided much information about gene function in the field of developmental biology. Recently, conditional gene targeting using the Cre/loxP system has been developed to control the cell type and timing of the target gene expression. The increase in number of kidney-specific Cre mice allows for the analysis of phenotypes that cannot be addressed by conventional gene targeting. The mammalian kidney is a vital organ that plays a critical homeostatic role in the regulation of body fluid composition and excretion of waste products. The interactions between epithelial and mesenchymal cells are very critical events in the field of developmental biology, especially renal development. Kidney development is a complex process, requiring inductive interactions between epithelial and mesenchymal cells that eventually lead to the growth and differentiation of multiple highly specialized stromal, vascular, and epithelial cell types. Through the use of genetically engineered mouse models, the molecular bases for many of the events in the developing kidney have been identified. Defective morphogenesis may result in clinical phenotypes that range from complete renal agenesis to diseases such as hypertension that exist in the setting of grossly normal kidneys. In this review, we focus on the growth and transcription factors that define kidney progenitor cell populations, initiate ureteric bud branching, induce nephron formation within the metanephric mesenchyme, and differentiate stromal and vascular progenitors in the metanephric mesenchyme.

Construction of the markless clpP-deletion mutant of Streptococcus mutans / 中华微生物学和免疫学杂志

Objective To construct markless gene deletion mutant at the clpP loci on the chromosome of Streptococcus mutans(S.mutans).Methods ASp resistance gene was amplified by PCR,to construct the Sp resistance cassette where the Sp resistance gene was flanked with two loxP site.After the clpP gene was cloned into the pGEM-T-Easy TA cloning vector,it was digested and linked with the Sp resistance cassette,yielding homologous recombination vector pIB △ clpP-Sp.The vector was linearized and used for the transformation of S.mutans UA159,with transformants selected on TPY plates containing Sp.The selected strain was transformed with the thermosensitive plasmid pCrePA to excise the Sp resistance gene.The pCre-PA was then easily eliminated at nonpermissive temperature,resulting in a markless mutant strain carrying a deletion at the clpP loci,which was verified by PCR and DNA sequencing.Results The result of the PCR analysis and DNA sequencing indicated that a part of the clpP gene was deleted.There was a loxP at this loci without the Sp resistance gene.Conclusion The markless clpP-deletion mutant of S.mutans was constructed successfully,which laid a foundation for further study of its biological function and its influence on the cariogenicity of S.mutans.