[A Luciferase-EGFP Reporter System for the Evaluation of DNA Methylation in Mammalian Cells].

DNA methylation is an essential epigenetic modification involved in numerous biological processes. Here, we present a cell-based system pLTR-Luc2P-EGFP for evaluation of DNA methylation in mammalian cells. In this system, the expression of reporter gene luciferase2P (Luc2P)-EGFP is under the control of HIV-1 promoter 5' long terminal repeat (LTR), which contains multiple CpG sites. Once these sites are methylated, the expression of Luc2P-EGFP is turned off, which may be visualized under fluorescence microscopy, with quantification performed in luciferase activity assay. As a proof of principle, pLTR-Luc2P-EGFP was methylated in vitro, and transfected into 293T cells, where the reduction of Luc2P-EGFP expression was confirmed. Premixed reporter DNA samples with the methylation levels varying from 0 to 100% were used for quantitative measurements of DNA methylation. The resulting standard curves indicated the accuracy of luciferase activity exceeding that of the Western blotting against EGFP. The Bland-Altman analysis showed that data from luciferase activity assay were in good agreement with the actual DNA methylation levels. In summary, we have established a reporter system coupled with reliable detection technique capable of efficient quantifying the changes in methylation in mammalian cells. This system may be utilized as a high throughput screening tool for identifying molecules that modulate DNA methylation.

A possible way that φC31 integrase regulates the recombination direction.

φC31 integrase encoded by Streptomyces phage can mediate site-specific recombination between phage and host genomes. The recombination direction is generally considered to be accurately regulated, but the regulatory mechanisms involved are still unclear. Recently, some hyperactive mutants of φC31 integrase that can bypass the regulatory steps have been isolated and extensively studied. A putative coiled-coil region is found to play a critical role in controlling recombination direction. Further analysis led us to the speculation that at least two regions in the N-terminal domain of φC31 integrase are involved in the tetrameric interfaces and that the putative coiled coil interacts with one of the regions to regulate the recombination direction.

Phylogenetic analysis of Gansu sheeppox virus isolates based on P32, GPCR, and RPO30 genes.

Two outbreaks of sheeppox in sheep have occurred in Gansu Province, China. The P32, GPCR, and RPO30 genes were used as markers for differential diagnosis. We confirmed that the outbreaks were caused by sheeppox virus. Sequence and phylogenetic analysis of the P32, GPCR, and RPO30 genes revealed a close relationship between the 2 isolates and Chinese sheeppox viruses. Because ill sheep were imported from Jingyuan, another county of Gansu Province, our results strongly suggest the importance of veterinary surveillance prior to transportation.

Association between single nucleotide polymorphisms of the osteoprotegerin gene and postmenopausal osteoporosis in Chinese women.

Osteoporosis is an important and common complex health problem, particularly in postmenopausal women. It is characterized by a reduction in bone mineral density (BMD) and a deterioration of bone microarchitecture with a consequent increase of fracture risk. The osteoprotegerin (OPG) gene is considered to play an important role in the pathogenesis of osteoporosis. We analyzed SNPs of the OPG gene and associations between these polymorphisms and BMD in 399 Chinese postmenopausal women. BMD was quantified at the lumbar spine (L2-4), femoral neck, and total hip. The g.2264T>C and g.27676A>C SNPs were detected by PCR-RFLP and DNA sequencing methods. A significant association with spine BMD was found for g.27676A>C. The spine BMD value for subjects with genotype AA was significantly higher than those with genotypes GA and AA. No significant association was detected between any of the SNP marker genotypes and the other traits. We conclude that g.27676A>C in the OPG gene affects spine BMD and that the C allele is associated with increased risk for osteoporosis in Chinese postmenopausal women.

A Luciferase-EGFP Reporter System for the Evaluation of DNA Methylation in Mammalian Cells.

DNA methylation is an essential epigenetic modification involved in numerous biological processes. Here, we present a cell-based system pLTR-Luc2P-EGFP for evaluation of DNA methylation in mammalian cells. In this system, the expression of reporter gene luciferase2P (Luc2P)-EGFP is under the control of HIV-1 promoter 5' long terminal repeat (LTR), which contains multiple CpG sites. Once these sites are methylated, the expression of Luc2P-EGFP is turned off, which may be visualized under fluorescence microscopy, with quantification performed in luciferase activity assay. As a proof of principle, pLTR-Luc2P-EGFP was methylated in vitro, and transfected into 293T cells, where the reduction of Luc2P-EGFP expression was confirmed. Premixed reporter DNA samples with the methylation levels varying from 0 to 100% were used for quantitative measurements of DNA methylation. The resulting standard curves indicated the accuracy of luciferase activity exceeding that of the Western blotting against EGFP. The Bland-Altman analysis showed that data from luciferase activity assay were in good agreement with the actual DNA methylation levels. In summary, we have established a reporter system coupled with reliable detection technique capable of efficient quantifying the changes in methylation in mammalian cells. This system may be utilized as a high throughput screening tool for identifying molecules that modulate DNA methylation.

[Analysis on condom use negotiation with sex partners and condom use in female sex workers].

Objective: To know condom use negotiation with clients and regular sex partners and condom use in female sex workers (FSWs), and provide reference for the development of comprehensive HIV/AIDS intervention for FSWs. Methods: The cross sectional survey was conducted in Jianshui county and Mengzi county in Honghe Hani and Yi autonomous prefecture. A total of 476 FSWs aged 16 years and above were recruited from entertainment venues, and the information about their demographic characteristics, condom use negotiation and condom use were collected by using questionnaires. Logistic regression model was used to analyze related factors of condom use after negotiation between FSWs and clients unwilling use condom. Results: A total of 852 FSWs who aged (24.29±8.44) years old participated in the survey. In past month, 499 FSWs had negotiation for condom use with unwilling clients (58.6%, 499/852), after negotiation, 441 FSWs (88.4%, 441/499) had consistent condom use in each sex with the clients. In the past one month, 99 FSWs had negotiation for unwilling use condom with regular sex partners (14.4%, 99/687), after negotiation, 54 FSWs (54.5%, 54/99) had consistent condom use in each sex with regular sex partners. Among the FSWs, 266 (53.3%, 266/499) reported that they could say "It is a mandatory requirement" to persuade clients who were unwilling to use condom. 97(19.4%, 97/499) reported that they could say "There is risk for infection" to persuade clients who were unwilling to use condoms. 115 (23.1%,115/499) reported that they could say "It is a mandatory requirement" and "there is risk for infection" to persuade their unwilling clients to use condoms. 21 (4.2%, 21/499) reported that they used other strategies. 22 (4.4%, 22/499) felt that it was difficult to persuade clients to use condoms. Multivariate logistic regression analysis showed that compared with FSWs who felt difficult in persuading clients to use condoms, FSWs who felt moderate difficulty were more likely to have consistent condom use after negotiation (OR=4.00, 95%CI: 1.55-10.32) and FSWs who felt easy in persuading clients to use condoms were also more likely to have consistent condom use (OR=30.17, 95%CI: 3.22-282.44). Compared with FSWs used other strategies to persuade their clients to use condoms, FSWs who said it was a mandatory requirement were more likely to have consistent condom use after negotiation (OR=4.44, 95%CI: 1.41-14.01) and FSWs who said it was a mandatory requirement and there was risk for infection were also more likely to have consistent condom use (OR=5.52, 95%CI: 1.55-19.73). Conclusions: Negotiation for condom use increased the rate of condom use in FSWs in sex with clients who were unwilling to use condom. The negotiation strategy of "It is a mandatory requirement" would promote condom use in FSWs in sex with clients who were unwilling to use condom. Besides, the negotiation strategy of saying "there is risk for infection" had additional effects.

[Determination of 17-hydroxycorticosteroid by capillary zone electrophoresis].

OBJECTIVE: To detect and dissociate 17-hydroxycorticosteroids(17-OHCS) in urine by using high performance capillary zone electrophoresis(CZE) so as to solve the problem that phenolic compounds interfere with the determination of urine 17-OHCS by chromatographic-spectrophotometry. METHODS: Pigments were absorbed from samples by activated kaolin in which the internal standard was theophyline. Urine 17-OHCS was absorbed by neutral styrene-divinylbenzene resin. Thus pigments and phenolic compounds were separated roughly. Then 17-OHCS was washed down by alcohol and separated and detected by capillary zone electrophoresis. RESULTS: Urinary 17-OHCS was separated successfully. Urinary 17-OHCS had a good linearity in the range of 2-50 mg.L-1 (r = 0.994). The average recovery rate was 96.17%. The relative standard deviation was less than 5%. The consistence detection limit was 0.3 mg.L-1. CONCLUSIONS: Compared with chromatographic-spectrophotometry, the high performance capillary electrophoresis has much less interference and is more simple, rapid, and accurate.