Cre-lox recombination system consists of two elements: Cre recombinase enzyme and lox sites. Cre recombinase can recombine the lox site sequences by specifically detecting and cutting them. The direction and position of lox sites determine the functional effects of Cre enzyme such as deletion, inversion or chromosomal translocation. The hematopoietic system of mouse consists of multi-lineages and various developmental stage hematopoietic cells that are differentiated from hematopoietic stem cells (hematopoietic stem cells, HSC). The hematopoietic stem cells are maintained in the bone marrow microenvironment (niche). Currently, a variety of floxed conditional-knockout mice, recognized by Cre-lox recombination system, are used for the study of the hematopoietic system. This review summarizes the commonly used Cre transgenic mice and their applications in the study of hematopoietic system.
Animals ; Hematopoietic Stem Cells ; cytology ; metabolism ; Integrases ; Mice ; Mice, Transgenic

Limited information is available regarding horse-associated antimicrobial resistant (AR) Escherichia (E.) coli. This study was designed to evaluate the frequency and characterize the pattern of AR E. coli from healthy horse-associated samples. A total of 143 E. coli (4.6%) were isolated from 3,078 samples collected from three national racetracks and 14 private horse-riding courses in Korea. Thirty of the E. coli isolates (21%) showed antimicrobial resistance to at least one antimicrobial agent, and four of the AR E. coli (13.3%) were defined as multi-drug resistance. Most of the AR E. coli harbored AR genes corresponding to their antimicrobial resistance phenotypes. Four of the AR E. coli carried class 1 integrase gene (intI1), a gene associated with multi-drug resistance. Pulsed-field gel electrophoretic analysis showed no genetic relatedness among AR E. coli isolated from different facilities; however, cross-transmissions between horses or horses and environments were detected in two facilities. Although cross-transmission of AR E. coli in horses and their environments was generally low, our study suggests a risk of transmission of AR bacteria between horses and humans. Further studies are needed to evaluate the risk of possible transmission of horse-associated AR bacteria to human communities through horse riders and horse-care workers.
Bacteria ; Drug Resistance, Multiple ; Escherichia coli* ; Escherichia* ; Genes, vif ; Horses* ; Humans ; Integrases ; Korea* ; Phenotype

BACKGROUND: The incidence of infections with imipenem- resistant Acinetobacter baumannii (IRAB) and Pseudomonas aeruginosa (IRPA) is increasing worldwide, and recent molecular studies indicate that the prevalence of carbapenemases is increasing in various parts of the world. However, few long-term longitudinal studies have assessed the prevalence of IRAB- and IRPA-derived carbapenemases and integrases in a hospital setting in Korea. METHODS: The carbapenemase genes (blaOXA-23, blaOXA-24, blaOXA-58, blaIMP-1, blaVIM-2, blaSIM-1, blaSPM-1) and integrase genes (intI1, intI2, intI3) produced by 46 IRAB strains and 51 IRPA strains collected at Chosun University Hospital between 2003 and 2006 were determined by PCR. RESULTS: The IRAB strains produced class 1 integrases more often than did the IRPA strains. However, the incidence increased steadily in both strains, reaching 100% in 2006. Carbapenemases of blaIMP-1 and blaVIM-2 types were found in 57% and 64% of the IRAB strains, respectively, in 2003. However, only one strain with blaVIM-2 was found in 2004 and another one with blaIMP-1 in 2005. The prevalence of carbapenemases was very low in the IRPA strains, just one strain with blaVIM-2 in 2005 and another one with blaoxa-23 in 2006. No other types of carbapenemase genes were detected in both strains. Rep-PCR of IRAB strains in 2003 showed different patterns. CONCLUSION: The incidence of carbapenemase varied by year but was generally low, except in 2003. The prevalence of class 1 integrases was consistently high and increased every year. The reason for the high prevalence of carbapenemases in 2003 is still unknown, but we assumed that it was not from the spread of a clone containing either blaIMP-1 or blaVIM-2 because the strains exhibited different rep-PCR patterns.
Acinetobacter baumannii* ; Acinetobacter* ; Clone Cells ; Imipenem ; Incidence ; Integrases* ; Korea ; Polymerase Chain Reaction ; Prevalence* ; Pseudomonas aeruginosa* ; Pseudomonas*

OBJECTIVETo construct a mouse that specifically expresses Cre recombinase in hepatocyte.

METHODSA hepatocyte specific transgenic construct containing mouse albumin promoter, the Cre recombinase gene and the poly (A) of human growth factor gene was generated. The linearized constructs were introduced into the fertilized eggs by microinjection to obtain the transgenic mice. The transcriptional specificity of Cre recombinase was detected by reverse transcription polymerase chain reaction (RT-PCR). The expression and function of Cre recombinase were detected by PCR and Southern Blot after crossing the Alb-Cre transgenic mice with the Smad4 conditional knockout mice.

RESULTSThe linearized constructs were microinjected into 837 fertilized eggs, and then the 797 effective eggs of microinjected eggs were implanted into the oviducts of 27 pseudo pregnant mice. In the 53 offspring, there were 6 mice carrying the transgene identified by polymerase chain reaction (PCR) and Southern Blot. Cre recombinase transcripts were detected in the livers and testis of the Alb-Cre transgenic mice using RT-PCR. The Cre recombinase was expressed in the livers of the double heterozygous for Alb-Cre and Smad4 floxed allele, and the exon 8 floxed by loxP site was deleted.

CONCLUSIONA hepatocyte-specific Cre transgenic mouse was generated successfully. The Cre recombinase expressed specifically in liver and could mediate the recombination between loxP sites in vivo.

Animals ; Female ; Hepatocytes ; metabolism ; Humans ; Integrases ; genetics ; Mice ; Mice, Transgenic ; Viral Proteins ; genetics

Mouse chromosome engineering, characterized by deletion and rearrangement of large fragment of chromosome, has been an important method for studying the function of mouse genome on a large scale. The latest progress in mouse chromosome engineering was introduced.
Animals ; Chromosome Deletion ; Chromosomes ; Genetic Engineering ; Integrases ; genetics ; Mice ; genetics ; Mutation ; Viral Proteins ; genetics

The Cre recombinase, an integrase from bacteriophage P1, catalyzes site-specific recombination between 34-bp repeats termed loxP sites, in the absence of any additional cofactors and energy. Mediated by Cre recombinase, specific DNA fragments can be excised, inversed or integrated depending on the orientation or position of loxP sites in vitro or in vivo. Because of its simplicity and high efficiency, Cre/loxP site-specific recombination system has been widely used in gene deletion and function identification, gene site-specific integration, gene trapping and chromosome engineering. It has been used as a useful tool for DNA recombination in transgenic yeast, plants, insects and mammals. Here progress in the study of the structure and function of Cre recombinase is discussed.
Integrases ; chemistry ; physiology ; Organisms, Genetically Modified ; Recombination, Genetic ; Viral Proteins ; chemistry ; physiology

Marker-free plants have been public concern. Co-transformation and site-specific recombination system are more important methods in self-gene excision. We reviewed the Cre/lox site-specific system and its applications in plants, also, we discussed perspectives of the system in according with our experience.
DNA, Plant ; genetics ; Genes, Plant ; genetics ; Genetic Markers ; Integrases ; Plants, Genetically Modified ; genetics ; Recombination, Genetic

The present study investigated prevalence of integrase strand transfer inhibitors (INSTI) resistance mutations in HIV-1-infected antiretroviral therapy (ART)-naïve patients in Korea. From 106 plasma samples, amplification and sequencing of integrase genes was performed, and major or minor mutations were calculated by the Stanford HIV drug resistance mutation interpretation algorithm. No major INSTI resistance mutations were found, and 14 minor mutations were detected in 13 (12.3%) patients. The present data support the recommendation that routine testing for INSTI resistance mutations before starting ART is not necessary.
Drug Resistance ; HIV ; Humans ; Integrases* ; Korea* ; Observational Study* ; Plasma ; Prevalence ; Prospective Studies*

An atypical teratoid/rhabdoid tumor (AT/RT) is a rare malignancy occurring in the first few years of life. This tumor shows rapid growth, a poor response to treatment, and poor prognosis. Cutaneous metastases presents as hamartomatous lesions mimicking skin tags. Immunohistochemical examination shows varied patterns of expression based on the sites of the body affected. Integrase interactor-1 (INI-1) gene sequencing and loss of expression of INI-1 observed with immunostaining can confirm AT/RT. In our patient, the skin lesion was identified at birth. Histopathological examination of the skin lesion could not establish an accurate diagnosis. Two months later, the patient presented with a brain tumor. Immunohistochemical examination of the brain lesion revealed complete loss of INI-1 expression in tumor cells, and the lesion was diagnosed as AT/RT. After that, we can detect the loss of INI-1 expression in the skin on the back. We report a rare case of AT/RT affecting the brain with cutaneous metastasis diagnosed with immunohistochemical staining.
Brain ; Brain Neoplasms ; Diagnosis ; Humans ; Integrases ; Neoplasm Metastasis ; Parturition ; Prognosis ; Skin

Humans ; HIV Infections ; HIV-1 ; Integrases ; China ; Drug Resistance, Viral ; Mutation