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11.
Croxford JL Triantaphyllopoulos KA Neve RM Feldmann M Chernajovsky Y Baker D 《Journal of immunology (Baltimore, Md. : 1950)》2000,164(5):2776-2781
In a murine relapsing experimental allergic encephalomyelitis (EAE) model, gene therapy to block TNF was investigated with the use of a retroviral dimeric p75 TNF receptor (dTNFR) construct. To effectively produce these TNF inhibitors in vivo, a conditionally immortalized syngeneic fibroblast line was established, using a temperature-sensitive SV40 large T Ag-expressing retrovirus. These cells were subsequently infected with a retrovirus expressing soluble dTNFR. CNS-injected cells could be detected 3 mo after transplantation and were shown to produce the transgene product by immunocytochemistry and ELISA of tissue fluids. These levels of dTNFR protein were biologically active and could significantly ameliorate both acute and relapsing EAE. This cell-based gene-vector approach is ideal for delivering proteins to the CNS and has particular relevance to the control of inflammatory CNS disease. 相似文献
12.
Evaluating the interaction between UCOE and DHFR‐linked amplification and stability of recombinant protein expression
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Chinese hamster ovary (CHO) cells are widely used in the biopharmaceutical industry. In the creation of mammalian cell lines plasmid DNA carrying the gene‐of‐interest integrates randomly into the host cell genome, which results in variable levels of gene expression between cell lines due to gene silencing mechanisms. In addition, cell lines often show unstable protein production during long‐term culture. This means that a large number of clones need to be screened in order to isolate stable, high producing cell lines making mammalian cell line development a long and laborious process. In this study an expression platform incorporating a Ubiquitous Chromatin Opening Element (UCOE; which are proposed to maintain chromatin in an open state) has been utilised for the expression of eGFP in CHO cells. Cell lines containing a UCOE vector, showed a significantly higher and more consistent eGFP expression than the non‐UCOE cell lines without DHFR amplification. To further improve recombinant protein production cell lines were amplified with methotrexate (MTX). UCOE cell lines showed improved growth in MTX therefore amplification to 250 nM MTX was achieved following a one‐step amplification procedure. However, non‐UCOE cell lines showed higher levels of eGFP production following MTX amplification. In addition, UCOE cell lines did not improve stability during long‐term culture in the absence of selective pressure. Stable eGFP production was achieved for all cell lines when MTX is present. Finally, UCOE cell lines displayed more consistent response to external stimuli than non‐UCOE cell lines, suggesting that UCOE cell lines are less prone to clonal variability. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1014–1025, 2015 相似文献
13.
The high‐fidelity replicative DNA polymerases, Pol ε and Pol δ, are generally thought to be poorly equipped to replicate damaged DNA. Direct and complete replication of a damaged template therefore typically requires the activity of low‐fidelity translesion synthesis (TLS) polymerases. Here we show that a yeast replisome, reconstituted with purified proteins, is inherently tolerant of the common oxidative lesion thymine glycol (Tg). Surprisingly, leading‐strand Tg was bypassed efficiently in the presence and absence of the TLS machinery. Our data reveal that following helicase–polymerase uncoupling a switch from Pol ε, the canonical leading‐strand replicase, to the lagging‐strand replicase Pol δ, facilitates rapid, efficient and error‐free lesion bypass at physiological nucleotide levels. This replicase switch mechanism also promotes bypass of the unrelated oxidative lesion, 8‐oxoguanine. We propose that replicase switching may promote continued leading‐strand synthesis whenever the replisome encounters leading‐strand damage that is bypassed more efficiently by Pol δ than by Pol ε. 相似文献
14.
Parasites exert a selection pressure on their hosts and are accountable for driving diversity within gene families and immune
gene polymorphisms in a host population. The overwhelming response of regulatory T cells during infectious challenges directs
the host immune system to lose the ability to mount parasite specific T cell responses. The underlying idea of this study
is that regulatory single nucleotide polymorphism (SNPs) can cause significant changes in gene expression in functional immune
genes. We identified and investigated regulatory SNPs in the promoter region of the FOXP3 gene in a group of Gabonese individuals exposed to a variety of parasitic infections. We identified two novel and one promoter
variants in 40 individual subjects. We further validated these promoter variants for their allelic gene expression using transient
transfection assays. Two promoter variants, −794 (C/G) and the other variant −734/−540 (C/T) revealed a significant higher
expression of the reporter gene at basal level in comparison to the major allele. The identification of SNPs that modify function
in the promoter regions could provide a basis for studying parasite susceptibility in association studies. 相似文献
15.
Cytokine-inducible SRC homology 2 domain protein (CISH) is a suppressor of cytokine signaling that controls interleukin-2
signaling pathway. We investigated the single nucleotide polymorphism (SNP) -292A>T in 473 Vietnamese hepatitis B virus (HBV)
carriers and 416 healthy controls. CISH variants at -292A>T were associated to HBV infection (Allelic: OR, 1.22 95% CI, 1–1.49; P = 0.04; Recessive: OR, 1.69 95% CI 1.23–2.54; P = 0.007). A gene dose effect for the risk allele -292T was observed (P = 0.04). The level of interleukin 2 and liver enzymes such as alanine transaminase, aspartate transaminase, total bilirubin,
and direct bilirubin were not associated to CISH polymorphism at position -292A>T This study associated the vital role of CISH SNP -292A>T variant to hepatitis B virus infection in a Vietnamese population. 相似文献
16.
Zea ribosomal repeat evolution and substitution patterns 总被引:2,自引:1,他引:1
Zea and Tripsacum nuclear ribosomal internal transcribed spacer (ITS)
sequences were used to evaluate patterns of concerted evolution, rates of
substitutions, patterns of methylation-induced deamination, and structural
constraints of the ITS. ITS pseudogenes were identified by their
phylogenetic position, differences in nucleotide composition, extensive
deamination at ancestral methylation sites, and substitutions resulting in
low-stability secondary RNA structures. Selection was important in shaping
the kinds of polymorphisms and substitutions observed in the ITS. ITS
substitution rates were significantly different among the Zea taxa.
Deamination of cytosines at methylation sites was a potent mutation source,
but selection appeared to maintain high methylation site density throughout
the ribosomal repeat except for the gene promoter. Nucleotide divergence
statistics identified selectively constrained regions at the 5' ends of the
ITS1 and ITS2.
相似文献
17.
Loss of phylogenetic information in chorion gene families of Bombyx mori gene conversion 总被引:1,自引:0,他引:1
Regier JC; Weigmann BM; Leclerc RF; Friedlander TP 《Molecular biology and evolution》1994,11(1):72-87
The silkmoth chorion has provided a stimulating model for the study of
evolution and developmental regulation of gene families. Previous attempts
at inferring relationships among chorion sequences have been based on
pairwise comparisons of overall similarity, a potentially problematic
approach. To remedy this, we identified the alignable regions of low
sequence variability and then analyzed this restricted database by
parsimony and neighbor-joining methods. At the deepest level, the chorion
sequence tree is split into two branches, called "alpha" and "beta." Within
each branch, early- and late-expressing genes each constitute monophyletic
groups, while the situation with middle-expressing genes remains uncertain.
The HcB gene family appears to be the most basal beta-branch group, but
this conclusion is qualified because the effect of gene conversion on
branching order is unknown. Previous studies by Eickbush and colleagues
have strongly suggested that ErA, HcA, and HcB families undergo gene
conversion within a gene family, whereas the ErB family does not. The
occurrence of conversion correlates with a particular tree structure;
namely, branch lengths are much greater at the base of the family than at
higher internodes and terminal branches. These observations raise the
possibility that chorion gene families are defined by gene conversion
events (reticulate evolution) rather than by descent with modification
(synapomorphy).
相似文献
18.
Nadia Hanum Valentina Cambiano Janey Sewell Alison J. Rodger Nneka Nwokolo David Asboe Richard Gilson Amanda Clarke Ada R. Miltz Simon Collins Valerie Delpech Sara Croxford Andrew N. Phillips Fiona C. Lampe for the AURAH Study Group 《PLoS medicine》2021,18(6)
BackgroundProspective cohort studies of incident HIV and associated factors among gay, bisexual, and other men who have sex with men (GBMSM) in the United Kingdom are lacking. We report time trends in and factors associated with HIV incidence between 2013 and 2019 among a cohort of GBMSM: the AURAH2 prospective study.Methods and findingsParticipants were recruited through 1 of 3 sexual health clinics in London and Brighton (July 2013 to April 2016) and self-completed a baseline paper questionnaire and subsequent 4-monthly and annual online questionnaires (March 2015 to March 2018), including information on sociodemographics, lifestyle, health and well-being, HIV status, sexual/HIV-related behaviours, and preexposure prophylaxis and postexposure prophylaxis (PrEP/PEP). Incident HIV was ascertained by linkage with national HIV surveillance data from Public Health England (PHE). We investigated the associations of HIV incidence with (1) baseline factors using mixed-effects Weibull proportional hazard models, unadjusted and adjusted for age, country of birth and ethnicity, sexuality, and education level; and (2) time-updated factors, using mixed-effects Poisson regression models.In total, 1,162 men (mean age 34 years, 82% white, 94% gay, 74% university-educated) were enrolled in the study. Thirty-three HIV seroconversions occurred over 4,618.9 person-years (PY) of follow-up: an overall HIV incidence rate (IR) of 0.71 (95% confidence interval (CI) 0.51 to 1.00) per 100 PY. Incidence declined from 1.47 (95% CI 0.48 to 4.57) per 100 PY in 2013/2014 to 0.25 (95% CI 0.08 to 0.78) per 100 PY in 2018/2019; average annual decline was 0.85-fold (p < 0.001). Baseline factors associated with HIV acquisition included the following: injection drug use (6/38 men who reported injection drug-acquired HIV; unadjusted conditional hazard ratio (HR) 27.96, 95% CI 6.99 to 111.85, p < 0.001), noninjection chemsex-related drug use (13/321; HR 6.45, 95% CI 1.84 to 22.64, p < 0.001), condomless anal sex (CLS) (26/741; HR 3.75, 95% CI 1.31 to 10·74, p = 0.014); higher number of CLS partners (HRs >10 partners [7/57]; 5 to 10 partners [5/60]; and 2 to 4 partners [11/293]: 14.04, 95% CI 4.11 to 47.98; 9.60, 95% CI 2.58 to 35.76; and 4.05, 95% CI 1.29 to 12.72, respectively, p < 0.001); CLS with HIV–positive partners (14/147; HR 6.45, 95% CI 3.15 to 13.22, p < 0.001), versatile CLS role (21/362; HR 6.35, 95% CI 2.18 to 18.51, p < 0.001), group sex (64/500; HR 8.81, 95% CI 3.07 to 25.24, p < 0.001), sex for drugs/money (4/55, HR 3.27, 95% CI 1.14 to 9.38, p = 0.027) (all in previous 3 months); previous 12-month report of a bacterial sexually transmitted infection (STI) diagnoses (21/440; HR 3.95, 95% CI 1.81 to 8.63, p < 0.001), and more than 10 new sexual partners (21/471, HRs 11 to 49, 50 to 99, and >100 new partners: 3.17, 95% CI 1.39 to 7.26; 4.40, 95% CI 1.35 to 14.29; and 4.84, 95% CI 1.05 to 22.4, respectively, p < 0.001). Results were broadly consistent for time-updated analysis (n = 622 men). The study’s main limitation is that men may not be representative of the broader GBMSM population in England.ConclusionsWe observed a substantial decline in HIV incidence from 2013 to 2019 among GBMSM attending sexual health clinics. Injection drug use, chemsex use, and measures of high-risk sexual behaviour were strongly associated with incident HIV. Progress towards zero new infections could be achieved if combination HIV prevention including Test and Treat strategies and routine commissioning of a PrEP programme continues across the UK and reaches all at-risk populations.Nadia Hanum and colleagues analyze trends in HIV incidence among gay, bisexual, and other Men Who Have Sex with Men attending sexual health clinics in England. 相似文献
19.
* The provision of sequence-tagged site (STS) anchor points allows meaningful comparisons between mapping studies but can be a time-consuming process for nonmodel species or orphan crops. * Here, the first use of high-resolution melt analysis (HRM) to generate STS markers for use in linkage mapping is described. This strategy is rapid and low-cost, and circumvents the need for labelled primers or amplicon fractionation. * Using white lupin (Lupinus albus, x = 25) as a case study, HRM analysis was applied to identify 91 polymorphic markers from expressed sequence tag (EST)-derived and genomic libraries. Of these, 77 generated STS anchor points in the first fully resolved linkage map of the species. The map also included 230 amplified fragment length polymorphisms (AFLP) loci, spanned 1916 cM (84.2% coverage) and divided into the expected 25 linkage groups. * Quantitative trait loci (QTL) analyses performed on the population revealed genomic regions associated with several traits, including the agronomically important time to flowering (tf), alkaloid synthesis and stem height (Ph). Use of HRM-STS markers also allowed us to make direct comparisons between our map and that of the related crop, Lupinus angustifolius, based on the conversion of RFLP, microsatellite and single nucleotide polymorphism (SNP) markers into HRM markers. 相似文献
20.