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Millions of museum specimens are integral to biodiversity studies; however, DNA degradation may limit the ability to obtain DNA sequences. In this study, a degradation analysis model for Lepidoptera specimens was established. Based on this model, we revealed the characteristics of DNA fragment distribution caused by external DNA damage factors during specimen preservation. We found that the degree of DNA degradation increased over time; DNA degradation of spread and dried adult specimens was significantly higher than that in the folded and formalin-fixed larval specimens. However, the effects of folding wings on DNA degradation and the effects of the preservation method/stage (formalin-fixed larval vs air-dried adult specimens) were different for different species.

Extracellular traps (ETs), such as neutrophil extracellular traps, are a physical mesh deployed by immune cells to entrap and constrain pathogens. ETs are immunogenic structures composed of DNA, histones, and an array of variable protein and peptide components. While much attention has been paid to the multifaceted function of these structures, mechanistic studies of ETs remain challenging due to their heterogeneity and complexity. Here, a novel DNA-histone mesostructure (DHM) formed by complexation of DNA and histones into a fibrous mesh is reported. DHMs mirror the DNA-histone structural frame of ETs and offer a facile platform for cell culture studies. It is shown that DHMs are potent activators of dendritic cells and identify both the methylation state of DHMs and physical interaction between dendritic cells and DHMs as key tuning switches for immune stimulation. Overall, the DHM platform provides a new opportunity to study the role of ETs in immune activation and pathophysiology., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The effect of S-substitution on the O6 guanine site of a 13-mer DNA duplex containing a G:T mismatch is studied using molecular dynamics. The structure, dynamic evolution and hydration of the S-substituted duplex are compared with those of a normal duplex, a duplex with S-substitution on guanine, but no mismatch and a duplex with just a G:T mismatch. The S-substituted mismatch leads to cell death rather than repair. One suggestion is that the G:T mismatch recognition protein recognises the S-substituted mismatch (GS:T) as G:T. This leads to a cycle of futile repair ending in DNA breakage and cell death. We find that some structural features of the helix are similar for the duplex with the G:T mismatch and that with the S-substituted mismatch, but differ from the normal duplex, notably the helical twist. These differences arise from the change in the hydrogen-bonding pattern of the base pair. However a marked feature of the S-substituted G:T mismatch duplex is a very large opening. This showed considerable variability. It is suggested that this enlarged opening would lend support to an alternative model of cell death in which the mismatch protein attaches to thioguanine and activates downstream damage-response pathways. Attack on the sulphur by reactive oxygen species, also leading to cell death, would also be aided by the large, variable opening.

Photochemotherapy, the combination of a photosensitiser and ultraviolet (UV) or visible light, is an effective treatment for skin conditions including cancer. The high mutagenicity and non-selectivity of photochemotherapy regimes warrants the development of alternative approaches. We demonstrate that the thiopyrimidine nucleosides 5-bromo-4-thiodeoxyuridine (SBrdU) and 5-iodo-4-thiodeoxyuridine (SIdU) are incorporated into the DNA of cultured human and mouse cells where they synergistically sensitise killing by low doses of UVA radiation. The DNA halothiopyrimidine/UVA combinations induce DNA interstrand crosslinks, DNA-protein crosslinks, DNA strand breaks, nucleobase damage and lesions that resemble UV-induced pyrimidine(6-4)pyrimidone photoproducts. These are potentially lethal DNA lesions and cells defective in their repair are hypersensitive to killing by SBrdU/UVA and SIdU/UVA. DNA SIdU and SBrdU generate lethal DNA photodamage by partially distinct mechanisms that reflect the different photolabilities of their C-I and C-Br bonds. Although singlet oxygen is involved in photolesion formation, DNA SBrdU and SIdU photoactivation does not detectably increase DNA 8-oxoguanine levels. The absence of significant collateral damage to normal guanine suggests that UVA activation of DNA SIdU or SBrdU might offer a strategy to target hyperproliferative skin conditions that avoids the extensive formation of a known mutagenic DNA lesion., (Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Acquisition of exogenous genetic material is a key event in bacterial speciation. It seems reasonable to assume that recombination of the incoming DNA into genome would be more efficient with higher levels of relatedness between the DNA donor and recipient. If so, bacterial speciation would be a smooth process, leading to a continuous spectrum of genomic divergence of bacteria, which, however, is not the case as shown by recent findings. The goal of this study was todetermine if DNA transfer efficiency is correlated with the levels of sequence identity., Results: To compare the relative efficiency of exogenous DNA acquisition among closely related bacteria, we carried out phage-mediated transduction and plasmid-mediated transformation in representative Salmonella strains with different levels of relatedness. We found that the efficiency was remarkably variable even among genetically almost identical bacteria. Although there was a general tendency that more closely related DNA donor-recipient pairs had higher transduction efficiency, transformation efficiency exhibited over a thousand times difference among the closely related Salmonella strains., Conclusion: DNA acquisition efficiency is greatly variable among bacteria that have as high as over 99% identical genetic background, suggesting that bacterial speciation involves highly complex processes affected not only by whether beneficial exogenous DNA may exist in the environment but also the "readiness" of the bacteria to accept it.

We developed a new simple and sensitive assay for lysozyme based on gold nanoparticle plasmon resonance light scattering (PRLS) measurement and naked-eye detection using for the first time the lysozyme DNA aptamer as the recognition element. Lysozyme DNA aptamer could stabilize gold nanoparticles (AuNPs) at high ionic strength. Introducing lysozyme to the system easily triggered the aggregation of AuNPs, producing a red-to-blue color change of the solution, red-shifted plasmon absorption, and enhanced plasmon resonance light scattering. The linear range was found to be 0.2∼4 nM for 0.7 nM AuNPs, 0.3∼6 nM for 1.4 nM AuNPs and 0.6∼8 nM for 2.1 nM AuNPs. About 0.1 nM lysozyme can produce an observable enhancement of PRLS signal. For visual detection, 1 nM lysozyme can produce a very distinctive color change. Satisfactory recoveries were obtained for simulated saliva and diluted urine samples, indicating that the method has potential for analyses of clinical samples. The simplicity and high sensitivity that are consistent with the resources and needs of many laboratories makes this method a good choice for routine analysis.

Background: Purified human thymine DNA glycosylase (TDG) recognizes a G: T mispair in a CpG sequence context more strongly than in any other, in addition to its inactivity toward 2-aminopurine: T or 2,6 diaminopurine: T pairs. We investigated the multiplicity of TDG to establish a better relationship between in vitro G: T mismatch incision and in vivo repair of a G: T to a G: C pair., Material/methods: Cell-free extract was prepared from A1235-MR4 human glioma cells grown in tissue culture. Fractions containing TDG activities were separated on a strong anion-exchange column. 45-bp DNA containing a single G: T or altered G: T mispair was prepared for measuring mismatch-specific strand-incision., Results: The extract yielded three fractions containing TDG activities. Each was further purified on a sizing column to exclude a relationship between a small fragment and TDG activity. While the substrate activity range of fraction III, eluting at the highest salt concentration, was the same as the known TDG, fractions eluted at medium and low concentrations were distinct: fractions I and II reacted with substrates of known TDG and DNA containing or 2-aminopurine: T (2,6-diaminopurine: T) base pairs. Modified m4T mispaired with G in DNA was acted on by fraction I and not II or III, suggesting fraction I activity is distinct. Each fraction showed strong activity on DNA with G: U and G: T mispairs in the CpG sequence context., Conclusions: The unique range of each TDG activity corresponding to the three fractions indicates that human cells possibly express three distinct TDGs.

4-Thio-5-bromo-2'-deoxyuridine (3a) is prepared from 5-bromo-2'-deoxyuridine (BrdU) and its key properties are explored. The thionucleoside (3a) can react readily with monobromobimane and produces high fluorescence. 3a has UV maximum absorption at 340 nm and can be incorporated into cellular DNA. The cells containing 3a become sensitive to UVA light, offering therapeutic potential for UVA-induced cell killing.

KaiC from Synechococcus elongatus PCC 7942 (KaiC) is an essential circadian clock protein in cyanobacteria. Previous sequence analyses suggested its inclusion in the RecADnaB superfamily. A characteristic of the proteins of this superfamily is that they form homohexameric complexes that bind DNA. We show here that KaiC also forms ring complexes with a central pore that can be visualized by electron microscopy. A combination of analytical ultracentrifugation and chromatographic analyses demonstrates that these complexes are hexameric. The association of KaiC molecules into hexamers depends on the presence of ATP. The KaiC sequence does not include the obvious DNA-binding motifs found in RecA or DnaB. Nevertheless, KaiC binds forked DNA substrates. These data support the inclusion of KaiC into the RecADnaB superfamily and have important implications for enzymatic activity of KaiC in the circadian clock mechanism that regulates global changes in gene expression patterns.

The thiopurine 6-thioguanine (S6G) is used to treat acute leukaemia. Its cytotoxic effect requires an active DNA mismatch repair (MMR) system. S6G is incorporated into DNA where a small fraction undergoes in situ conversion to S6-thiomethylguanine (S6meG). After replication, S6meG-containing base pairs interact with MMR. This interaction is ultimately lethal and MMR-defective cells are resistant to S6G. Here, we report that growing human cells extensively incorporate the thiopyrimidine nucleoside 4-thiothymidine (S4TdR) into their DNA. The incorporated thiopyrimidine (S4T) can also undergo facile S-methylation to 4-thiomethylthymine (S4meT). The rate of methylation of S4TdR in model substrates is similar to that for the conversion of S6G to S6meG indicating that the DNA of cells grown in S4TdR will contain significant levels of S4meT. Despite this, S4TdR is not associated with MMR-related cell death. We demonstrate that, in contrast to S6meG, neither DNA S4T nor S4meT codes ambiguously. S4T retains the coding properties of unmodified T, whereas S4meT behaves like a normal cytosine and exclusively directs the incorporation of guanine. The preferred S4meT:G base pair is also a poor substrate for binding by the hMutSalpha mismatch recognition factor. We suggest that the ability of S4meT to produce a structurally acceptable base pair during replication underlies the absence of MMR-related death in cells treated with S4TdR.

Recently, lipid nanoparticles (LNPs) have been extensively investigated as non-viral carriers of nucleic acid vaccines due to their high transport efficiency, safety, and straightforward production and scalability. However, the molecular mechanism underlying the interactions between nucleic acids and phospholipid bilayers within LNPs remains elusive. In this study, we employed the all-atom molecular dynamics simulation to investigate the interactions between single-stranded nucleic acids and a phospholipid bilayer. Our findings revealed that hydrophilic bases, specifically G in single-stranded RNA (ssRNA) and single-stranded DNA (ssDNA), displayed a higher propensity to form hydrogen bonds with phospholipid head groups. Notably, ssRNA exhibited stronger binding energy than ssDNA. Furthermore, divalent ions, particularly Ca2+, facilitated the binding of ssRNA to phospholipids due to their higher binding energy and lower dissociation rate from phospholipids. Overall, our study provides valuable insights into the molecular mechanisms underlying nucleic acid-phospholipid interactions, with potential implications for the nucleic acids in biotherapies, particularly in the context of lipid carriers. [ABSTRACT FROM AUTHOR]

Thioguanine is sensitive to UVA light and generates singlet molecular oxygen (1O2*) when exposed to UVA. Three thioguanosine derivatives, 2′,3′,5′-tri-O-acetyl-6-thioguanosine (ta6TGuo), 2′,3′,5′-tri-O-acetyl-8-thioguanosine (ta8TGuo), and 2′,3′,5′-tri-O-acetyl-6,8-dithioguanosine (taDTGuo) were explored photophysically and photochemically. Nanosecond transient absorption and time-resolved near-infrared emission measurements were carried out to investigate the characteristics of their excited triplet states in acetonitrile solution. The quantum yield of intersystem crossing (ΦISC), the intrinsic decay rate constant (k0), the quenching rate constant by 3O2 (kq) and the self-quenching rate constant (kSQ) of their triplet states were all determined. From the precise analysis of the quantum yield of 1O2* generation (ΦΔ) against the concentration of dissolved molecular oxygen, the fraction of the triplet states quenched by dissolved oxygen which gives rise to 1O2* formation (SΔ) was successfully obtained with high accuracy. The ΦΔ values at low oxygen concentrations reveal that these thioguanosines, particularly taDTGuo, can still effectively generate 1O2* at low molecular oxygen concentrations like carcinomatous microenvironments. These findings indicate that taDTGuo would perform well as a potential agent for photo-induced cancer therapies. [ABSTRACT FROM AUTHOR]

Epigenetic aberrations have been identified as biomarkers to predict the risk of Alzheimer's disease (AD). This study aimed to evaluate whether altered DNA methylation status of BDNF promoter could be used as potential epigenetic biomarkers for predicting the progression from amnestic mild cognitive impairment (aMCI) to AD. A total of 506 aMCI patients and 728 cognitively normal controls were recruited in the cross-sectional analyses. Patients (n = 458) from aMCI cohort were classified into two groups after 5-year follow-up: aMCI-stable group (n = 330) and AD-conversion group (n = 128). DNA methylation of BDNF promoter was detected by bisulfite-PCR amplification and pyrosequencing. The DNA methylation levels of CpG1 and CpG2 in promoter I and CpG5 and CpG6 in promoter IV of BDNF gene were significantly higher in the aMCI group than in the control group at baseline and also were increased in the conversion group compared with the non-conversion group at 5-year follow up time point. CpG5 in BDNF promoter IV had the highest AUC of 0.910 (95% CI: 0.817-0.983, p < 0.05). Kaplan-Meier analysis showed a significant AD conversion propensity for aMCI patients with high methylation levels of CpG5 (HR = 1.96, 95% CI: 1.07-2.98, p < 0.001). Multivariate Cox regression analysis revealed elevated methylation status of CpG5 was a significant independent predictor for AD conversion (HR = 3.51, p = 0.013). These results suggest that elevation of peripheral BDNF promoter methylation might be used as potential epigenetic biomarkers for predicting the conversion from aMCI to AD. [ABSTRACT FROM AUTHOR]

Cyanobacterial blooms are often associated with an increase in abundance of small-bodied zooplankton. The hypothesis that toxic cyanobacteria lead to in the dominance of small-bodied zooplankton was tested by investigating competitive outcomes with three common cladoceran species, analysing cladoceran remains in sediments, and identifying zooplankton resting eggs., Although the large-bodied cladoceran Daphnia pulex outcompeted the medium-sized cladoceran Simocephalus vetulus when fed green algae in laboratory experiments, the presence of toxic cyanobacteria completely altered this competitive outcome. Similar shifts in competitive dominance with the presence of cyanobacteria were observed when both D. pulex and S. vetulus competed with the small-bodied cladoceran Bosmina longirostris., Sediment cores from Dianshan Lake, the largest shallow lake in Shanghai, and surface sediments from 10 random ponds and rivers in the area were collected to recover the cladoceran and total zooplankton communities. Microcystin concentrations in sediments were used as a proxy for cyanobacterial abundances in nature. Altogether, cladoceran remains representing 10 genera were recovered from the sediment samples. Microcystin concentrations in the Dianshan Lake sediment cores were positively correlated with Bosmina abundance, but negatively correlated with both Daphnia and Diaphanosoma abundance. The proportion of large-bodied cladocerans significantly declined in relation to small-bodied species with increasing microcystin concentrations in the lake sediments., Fifty-eight types of zooplankton resting eggs were recovered in sediments from Shanghai waters and identified using DNA barcoding. The abundance of both a lecanid rotifer and total rotifers significantly increased with increasing cyanobacteria in the sediment cores, whereas the dominant copepod, Sinocalanus tenellus, decreased. However, these trends were not observed in comparison of surface sediments from 10 ponds and rivers in the area., These results indicate that the presence of toxic cyanobacteria may have altered the zooplankton communities and contributed to increased dominance of small-bodied species. This study also demonstrates that cladoceran remains and zooplankton resting eggs recovered from sediment cores are convenient natural archives for evaluating zooplankton responses to cyanobacterial blooms. [ABSTRACT FROM AUTHOR]

Systematic NMR characterization of 4-thio-5-furan-pyrimidine nucleosides or 4-thio-5-thiophene-pyrimidine nucleosides (ribonucleosides and 2′-deoxynucleosides) was performed. All proton and carbon signals of 4-thio-5-thiophene-ribouridine and related analogues were unambiguously assigned. The orientations of the base (4-thiouridine or its deoxy analogue) relative to the ring (furan or thiophene) are explored by a NMR approach and further supported by X-ray crystallographic studies. The procedures presented here would be applicable to other modified nucleosides and nucleotides. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The plant-phloem-feeding Blissus insularis possesses specialized midgut crypts, which harbor a dense population of the exocellular bacterial symbiont Burkholderia. Most individual B. insularis harbor a single Burkholderia ribotype in their midgut crypts; however, a diverse Burkholderia community exists within a host population. To understand the mechanism underlying the consistent occurrence of various Burkholderia in B. insularis and their specific association, we investigated potential gut symbiont transmission routes. PCR amplification detected a low titer of Burkholderia in adult reproductive tracts; however, fluorescence in situ hybridization assays failed to produce detectable signals in these tracts. Furthermore, no Burkholderia-specific PCR signals were detected in eggs and neonates, suggesting that it is unlikely that B. insularis prenatally transmits gut symbionts via ovarioles. In rearing experiments, most nymphs reared on St. Augustinegrass treated with cultured Burkholderia harbored the cultured Burkholderia strains. Burkholderia was detected in the untreated host grass of B. insularis, and most nymphs reared on untreated grass harbored a Burkholderia ribotype that was closely related to a plant-associated Burkholderia strain. These findings revealed that B. insularis neonates acquired Burkholderia primarily from the environment (i.e., plants and soils), even though the possibility of acquisition via egg surface cannot be excluded. In addition, our study explains how the diverse Burkholderia symbiont community in B. insularis populations can be maintained. [ABSTRACT FROM AUTHOR]

In this study, rat models of acute kidney injury (AKI) induced by renal ischemia-reperfusion (I/R) and HK-2 cell models of hypoxia-reoxygenation (H/R) were established to investigate the expression of inhibitor of DNA binding 1 (ID1) in AKI, and the regulation relationship between ID1 and hypoxia-inducible factor 1 alpha (HIF-1α). Through western blot, quantitative real-time PCR, immunohistochemistry, and other experiment methods, the induction of ID1 after renal I/R in vivo was observed, which was expressed mainly in renal tubular epithelial cells (TECs). ID1 expression was upregulated in in vitro H/R models at both the protein and mRNA levels. Via RNAi, it was found that ID1 induction was inhibited with silencing of HIF-1α. Moreover, the suppression of ID1 mRNA expression could lead to decreased expression and transcription of HIF-1α during hypoxia and reoxygenation. In addition, it was demonstrated that both ID1 and HIF-1α can regulate the transcription of twist. This study demonstrated that ID1 is induced in renal TECs during I/R and can regulate the transcription and expression of HIF-1α. [ABSTRACT FROM AUTHOR]

Steroid synthesis and metabolic pathways play important roles in the pathophysiology of PCOS, but until now there have been no studies on the methylation profiles of specific genes in steroid synthesis pathways that are known to be associated with PCOS. Here we used MassARRAY quantitative methylation analysis to determine the methylation levels of each CpG site or cluster in the promoters of EPHX1, SRD5A1, and CYP11A1 in 64 peripheral blood samples. We further examined the methylation level of EPHX1 in an independent cohort consisting of 116 people. Finally, we investigated the role of EPHX1 in steroidogenesis in the KGN cell line. For SRD5A1 and CYP11A1, there was no significant difference in methylation level between patients and controls. For EPHX1, however, the methylation levels of a few consecutive CpG sites and clusters were found to be significantly associated with PCOS. The methylation levels of a number of CpG clusters or sites were significantly lower in patients than in controls in the first cohort consisting of 64 people, such as clusters 13–14 (P<0.05), 15–16 (P<0.001), and 19–24 (P<0.001) and sites CpG_53 (P<0.01) and CpG_54 (P<0.05). Among differentiated methylation sites and clusters, the methylation levels of the CpG cluster 13–14 and CpG cluster 19–24 in PCOS patients were significantly lower than in controls in the second cohort of 116 people (P<0.05 for both). In addition, knockdown and overexpression experiments in KGN cells showed that EPHX1 can regulate estradiol concentrations, and this indicates a role for EPHX1 in steroidogenesis. Our study has demonstrated that methylation of the EPHX1 promoter might be associated with PCOS. This study provides direct evidence that methylation plays an important role in PCOS and demonstrates a novel role for EPHX1 in female reproduction. [ABSTRACT FROM AUTHOR]

Unambiguous characterization of 5-substituted-4-thiopyrimidine nucleosides (ribonucleosides and 2'-deoxynucleosides) was performed using NMR spectroscopy. Assignments of all proton and carbon signals of 5-bromo-4-thiouridine and related nucleosides were systematically carried out and firmly established by COSY and HMQC techniques. The NMR data of various 4-thiopyrimidine nucleosides are compared, and the key contributing factors discussed. The approach presented here is applicable to other modified nucleosides and nucleotides, as well as nucleobases. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Cyanobacterial blooms, forming massive scum and various cyanotoxins, increasingly spread in a wide range of freshwater ecosystems. One heavy Microcystis bloom occurred in the entire Qinhuai River basin in 2010 summer for the first time. To determine the Microcystis populations and their spatial distributions along Qinhuai River, a molecular approach was applied by sequencing the DNA library based on the internal transcribed spacer sequences of 16-23S rRNA (ITS). The parsimony network (TCS) analysis showed that 9 groups were formed based on the main 24 genotypes, and each group was dominated by one highly represented root sequence. Marked changes in the composition and proportion of the Microcystis ITS genotype were detected from the upper to the lower reaches. The seed sources forming the bloom were probably located at 4 different locations. Furthermore, it was found that pH was the primary factor affecting the spatial distribution of the main genotype group among samples. [Copyright &y& Elsevier]

Genetic polymorphism is a difference in DNA sequence among individuals, groups, or populations that give rise to different forms. Differences in DNA sequences that occur naturally in a population. Single nucleotide substitutions, insertions and deletions of nucleotides and repetitive sequences (microsatellites) are all examples of polymorphism. The position at which such a sequence difference is found is a polymorphic site. A single nucleotide substitution is called a single nucleotide polymorphism (SNP). SNPs can occur in coding parts of the gene. If they result in genetic code change, amino-acid polymorphism would occur. The heterodimeric IFN-γ receptor ( IFNGR) complex was made up of two receptor subunits including IFNGR-1 and IFNGR-2. There exist five dbSNP alleles in IFNGR1 exon region and six dbSNP alleles in IFNGR2. Some researchers had found that the greatest risk of the development of systemic lupus erythematosus (SLE) be detected in the individuals who had the Met14/Val14 genotype or the combination of IFNGR1 Met14/Val14 genotype and IFNGR2 Gln64/Gln64 genotype in Japanese patients. So we aimed to assess the association between two polymorphisms within the IFNGR gene (A88G and A839G) and SLE in Chinese patients. This study included 154 patients with SLE and 159 unrelated healthy controls. We examined the IFNGR genotype by the reverse transcription-polymerase chain reaction (RT-PCR)-single-strand conformation polymorphism method, RT-PCR-restriction fragment length polymorphism method and DNA sequencing. Genotype frequencies between SLE patients and controls were compared and relationship between genotype frequencies and clinical manifestations of SLE were evaluated. We found that IFNGR2 Arg64/Arg64 genotype decrease the risk of SLE (OR = 2.326, 95% CI 1.181–4.581, Fisher P = 0.015), and the same as IFNGR2 Arg64/Arg64 genotype and IFNGR1 Val14/Val14 genotype combination (OR = 2.420, 95% CI 1.206–4.854, Fisher P = 0.013). The allelic frequency of Val14/Met14 is significantly higher in the patients with oral ulcer or thrombocytopenia when compared with patient without these clinical feature (OR = 4.630, 95% CI 1.370–15.640, Fisher P = 0.021; or OR = 6.368, 95% CI 2.009–20.191, Fisher P = 0.003). On the contrary, the allelic frequency of Val14/Val14 is lower in the patients with oral ulcer or thrombocytopenia than those without these clinical feature (OR = 0.216, 95% CI 0.064–0.730, Fisher P = 0.021; or OR = 0.157, 95% CI 0.050–0.498, Fisher P = 0.003). And after data analysis, we also find that the allelic frequency of Gln64/Gln64 is lower in the patients with arthritis when compared with patient without arthritis (OR = 0.369, 95% CI 0.166–0.818, Fisher P = 0.017). We can conclude that the IFNGR polymorphisms (Val14Met and Gln64Arg) are protective in SLE in Chinese patients. We describe a novel association between Val14/Met14 carriage and patients with oral ulcer or thrombocytopenia. [ABSTRACT FROM AUTHOR]

Fluorescence biosensor to detect microRNAs via integrating DNA hairpins transition mediated strand displacement amplification with primer exchange reaction. [Display omitted] Herein, we constructed a fluorescence biosensor for the ultra-sensitive analysis of microRNAs (miRNAs) by combining DNA hairpins transition triggered strand displacement amplification (DHT-SDA) with primer exchange reaction (PER). Target miRNA initiated DHT-SDA to facilitate the generation of multiple single-stranded DNA (ssDNA) as PER primer, which was extended into a long ssDNA. The biosensor is successfully utilized in detecting miRNAs with high sensitivity (limit of detection for miRNA-21 was 58 fM) and a good linear relationship between 100 nM and 100 fM. By simply changing the DNA hairpin sequence, the constructed biosensor can be extended to analyze another miRNAs. Moreover, the biosensor has the feasibility of detecting miRNAs in real samples with satisfactory accuracy and reliability. Therefore, the fluorescent biosensor has great application potential in clinical diagnosis. [ABSTRACT FROM AUTHOR]

Abstract: The therapeutic effect of the thiopurines, 6-thioguanine (6-TG), 6-mercaptopurine, and its prodrug azathioprine, depends on the incorporation of 6-TG into cellular DNA. Unlike normal DNA bases, 6-TG absorbs UVA radiation, and UVA-mediated photochemical damage of DNA 6-TG has potentially harmful side effects. When free 6-TG is UVA irradiated in solution in the presence of molecular oxygen, reactive oxygen species are generated and 6-TG is oxidized to guanine-6-sulfonate (GSO3) and guanine-6-thioguanine in reactions involving singlet oxygen. This conversion is prevented by antioxidants, including the dietary vitamin ascorbate. DNA GSO3 is also the major photoproduct of 6-TG in DNA and it can be selectively introduced into DNA or oligonucleotides in vitro by mild chemical oxidation. Thermal stability measurements indicate that GSO3 does not form stable base pairs with any of the normal DNA bases in duplex oligonucleotides and is a powerful block for elongation by Klenow DNA polymerase in primer extension experiments. In cultured human cells, DNA damage produced by 6-TG and UVA treatment is associated with replication inhibition and provokes a p53-dependent DNA damage response. [Copyright &y& Elsevier]