Antibiotic feeding changes the bacterial community of Chilo suppressalis and thereby affects its pesticide tolerance.

BACKGROUND: Owing to the widespread use of chemical pesticides to control agricultural pests, pesticide tolerance has become a serious problem. In recent years, it has been found that symbiotic bacteria are related to pesticides tolerance. To investigate the potential role of microorganisms in the pesticide tolerance of Chilo suppressalis, this study was conducted. RESULTS: The insect was fed with tetracycline and cefixime as the treatment group (TET and CFM, respectively), and did not add antibiotics in the control groups (CK). The 16S rDNA sequencing results showed that antibiotics reduced the diversity of C. suppressalis symbiotic microorganisms but did not affect their growth and development. In bioassays of the three C. suppressalis groups (TET, CFM, and CK), a 72 h LC50 fitting curve was calculated to determine whether long-term antibiotic feeding leads to a decrease in pesticide resistance. The CK group of C. suppressalis was used to determine the direct effect of antibiotics on pesticide tolerance using a mixture of antibiotics and pesticides. Indirect evidence suggests that antibiotics themselves did not affect the pesticide tolerance of C. suppressalis. The results confirmed that feeding C. suppressalis cefixime led to a decrease in the expression of potential tolerance genes to chlorantraniliprole. CONCLUSIONS: This study reveals the impact of antibiotic induced changes in symbiotic microorganisms on the pesticide tolerance of C. suppressalis, laying the foundation for studying the interaction between C. suppressalis and microorganisms, and also providing new ideas for the prevention and control of C. suppressalis and the creation of new pesticides.

Defence and nutrition synergistically contribute to the distinct tolerance of rice subspecies to the stem borer, Chilo suppressalis.

Damage caused by the rice striped stem borer (SSB), Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), is much more severe on indica/xian rice than on japonica/geng rice (Oryza sativa) which matches pest outbreak data in cropping regions of China. The mechanistic basis of this difference among rice subspecies remains unclear. Using transcriptomic, metabolomic and genetic analyses in combination with insect bioassay experiments, we showed that japonica and indica rice utilise different defence responses to repel SSB, and that SSB exploited plant nutrition deficiencies in different ways in the subspecies. The more resistant japonica rice induced patterns of accumulation of methyl jasmonate (MeJA-part of a defensive pathway) and vitamin B1 (VB1-a nutrition pathway) distinct from indica cultivars. Using gene-edited rice plants and SSB bioassays, we found that MeJA and VB1 jointly affected the performance of SSB by disrupting juvenile hormone levels. In addition, genetic variants of key biosynthesis genes in the MeJA and VB1 pathways (OsJMT and OsTH1, respectively) differed between japonica and indica rice and contributed to performance differences; in indica rice, SSB avoided the MeJA defence pathway and hijacked the VB1 nutrition-related pathway to promote development. The findings highlight important genetic and mechanistic differences between rice subspecies affecting SSB damage which could be exploited in plant breeding for resistance.

Tyrosine hydroxylase plays crucial roles in larval cuticle formation and larval-pupal tanning in the rice stem borer, Chilo suppressalis.

The striped stem borer, Chilo suppressalis (Walker), a notorious pest infesting rice, has evolved a high level of resistance to many commonly used insecticides. In this study, we investigate whether tyrosine hydroxylase (TH), which is required for larval development and cuticle tanning in many insects, could be a potential target for the control of C. suppressalis. We identified and characterized the full-length cDNA (CsTH) of C. suppressalis. The complete open reading frame of CsTH (MW690914) was 1683 bp in length, encoding a protein of 560 amino acids. Within the first to the sixth larval instars, CsTH was high in the first day just after molting, and lower in the ensuing days. From the wandering stage to the adult stage, levels of CSTH began to rise and reached a peak at the pupal stage. These patterns suggested a role for the gene in larval development and larval-pupal cuticle tanning. When we injected dsCsTH or 3-iodotyrosine (3-IT) as a TH inhibitor or fed a larva diet supplemented with 3-IT, there were significant impairments in larval development and larval-pupal cuticle tanning. Adult emergence was severely impaired, and most adults died. These results suggest that CsTH might play a critical role in larval development as well as larval-pupal tanning and immunity in C. suppressalis, and this gene could form a potential novel target for pest control.

Utilization of Multi-Parametric Quantitative Magnetic Resonance Imaging in the Early Diagnosis of Duchenne Muscular Dystrophy.

BACKGROUND: It is challenging to diagnose suspected Duchenne muscular dystrophy (DMD) patients in the very early stage of the disease. More evidence is needed to demonstrate the potential of quantitative MRI (qMRI) in precisely identifying patients before substantial physical decline occurs. PURPOSE: To assess the early diagnostic performance of multi-parametric qMRI for DMD patients, and the ability to identify DMD patients with mild functional decline. STUDY TYPE: Prospective. SUBJECTS: One hundred and forty DMD subjects (9.0 ± 2.2 years old), 24 male healthy controls (HCs) (9.2 ± 2.5 years old). FIELD STRENGTH/SEQUENCE: 3.0 T/3-point Dixon, T1-mapping, and T2-mapping. ASSESSMENT: qMRI measurements (fat fraction [FF], T1, and T2) of 11 thigh muscles (rectus femoris [RF], vastus lateralis [VL], vastus intermedius, vastus medialis, gracilis, sartorius, adductor longus, adductor magnus [AM], semitendinosus, semimembranosus, biceps femoris long head [BFLH]) on the right side were conducted. NorthStar ambulatory assessment (NSAA) score used to evaluate the function of DMD patients and divided them into three subgroups: mild (76-100 score), moderate (51-75 score), and severe (0-50 score) functional decline. STATISTICAL TESTS: Independent t-test, ANOVA analysis, and receiver operating characteristic (ROC) curves. A P-value <0.05 was considered statistically significant. RESULTS: Compared with HCs, FF and T2 were significantly higher in the group of all DMD patients, while T1 was significantly lower. The combination of T1 and T2 in RF, VL, AM, and BFLH achieved excellent area under curve (AUCs) (0.967-0.992) in differentiating five DMD patients without abnormal fat infiltration from HCs. Overall, T2 reached higher AUCs than FF and T1 in distinguishing DMD with mild functional decline from HCs, whereas FF achieved higher AUCs than T1 and T2 in distinguishing three DMD subgroups with functional decline. DATA CONCLUSION: Multi-parametric qMRI demonstrate effective diagnostic capabilities for DMD patients in the early stage of the disease, and can identify patients with mild physical decline. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 3.

Rapid Identification of Seven Common ABO Alleles by Two-Dimensional Polymerase Chain Reaction Technology.

Introduction: The molecular biology detection technology of the human ABO blood group system makes up for the limitations in many aspects compared with conventional serological typing technology. This study aimed to establish a new method to identify seven common ABO alleles (ABO*A1.01, ABO*A1.02, ABO*A2.01, ABO*B.01, ABO*O.01.01, ABO*O.01.02, and ABO*O.02.01) by two-dimensional polymerase chain reaction (2D PCR). 2D PCR can identify multiple target genes in a closed test tube by labeling specific primers with tags homologous to the sequence of fluorescently labeled probes, and melting curve analysis is performed after the fluorescent probes are hybridized with tag complementary sequences in PCR-specific products. In this study, 2D PCR and PCR sequence-specific primer (PCR-SSP) were combined to discriminate different alleles in a single reaction, which has the characteristics of high throughput, and compared with other typing techniques; the typing results can be obtained without additional operations. Methods: The ABO*A1.01 allele genetic sequence was used as the reference sequence. The specific sense and antisense primers for seven common ABO alleles were designed on exons 6 and 7 according to the principle of 2D PCR and PCR-SSP. Single nucleotide polymorphism sites for identifying seven alleles were detected in FAM and HEX channels, respectively. Two hundred sixty DNA samples were enrolled for rapid ABO genotyping by 2D PCR, and 95 of them were selected for Sanger sequencing. The Kappa test was used to analyze the agreement of the methodologies. Results: These 7 alleles each had four characteristic melting valleys at different single nucleotide polymorphism loci. A total of 15 genotypes were detected, including ABO*A1.01/A1.02, ABO*A1.01/O.01.01, ABO*A1.01/O.01.02, ABO*A1.02/A1.02, ABO*A1.02/O.01.01, ABO*A1.02/O.01.02, ABO*B.01/B.01, ABO*B.01/O.01.01, ABO*B.01/O.01.02, ABO*O.01.01/O.01.01, ABO*O.01.01/O.01.02, ABO*O.01.02/O.01.02, ABO*A1.01/B.01, ABO*A1.02/B.01, and ABO*B.01/O.01. v (containing a rare ABO*O allele, based on the sequencing results). The Kappa test showed completely consistent results for 2D PCR and Sanger sequencing (Kappa = 1). Conclusion: The 2D PCR technique could be used for molecular typing of the ABO blood group, which was efficient, rapid, accurate, and economical.

The effects and possible mechanism of action of apolipoprotein M on the growth of breast cancer cells.

BACKGROUND: To investigate the effects and mechanism of action of apolipoprotein M (ApoM) on the growth of breast cancer (BC) cells. METHODS AND RESULTS: Bioinformatics, cell experiments and animal experiments were used to verify the effect of ApoM on breast cancer cell lines and breast tumor growth in vivo. ApoM expression was significantly reduced in BC tissues, and patients with lower ApoM mRNA expression had a poorer prognosis (P < 0.0001). Besides, ApoM can partially inhibit the proliferative, migratory and invasive processes of BC cells. In vivo, the difference between ApoM-OE and NC groups was no significant. The level of vitamin D receptor (VDR) protein in MDA-MB-231 cells was increased by overexpression of ApoM (P < 0.05), while in MCF-7 cells, VDR levels decreased (P < 0.05). CONCLUSIONS: ApoM can partially inhibit the growth of BC cells. VDR may play a role, but is not the main pathway.

Insecticide resistance associated overexpression of two sigma GST genes assists Nilaparvata lugens to remedy oxidative stress from feeding on resistant rice variety.

Insect glutathione S-transferases (GSTs) participate in detoxifying insecticides and plant metabolites in two different ways, metabolizing toxic components and remedying oxidative stress. Here in Nilaparvata lugens, a major insect pest on rice, the roles of cytosolic GSTs in resistance to insecticides and to plant defences were evaluated. The over-expression in four resistant strains indicated that NlGSTs1 and NlGSTs2 were essential to resistances to four test insecticides and H2O2 through an antioxidation mechanism. RNAi verified the antioxidation function of NlGSTs1 and NlGSTs2 in the resistances as a common mechanism, regardless of the structural differences among insecticides and H2O2. NlGSTs1 and NlGSTs2 also provided protection for N. lugens against rice defense by the same mechanism, reducing H2O2 levels when N. lugens were fed on the resistant rice variety Mudogo. The antioxidation activity of recombinant NlGSTs1 and NlGSTs2 is higher than their direct detoxification, which supported the ability of these two GSTs to remedy oxidative stress. For oxidative stress remediation as a common mechanism of NlGSTs1 and NlGSTs2 in both insecticide resistance and host adaptability, the development of insecticide resistance might enhance the ability of insects to remedy oxidative stress from feeding on resistant rice variety and thus to lower the resistance level of rice variety to N. lugens. The results call for careful assessment on N. lugens control when both insecticides and resistant rice variety are applied.

Time-Series Transcriptomic Analysis Reveals the Molecular Profiles of Diapause Termination Induced by Long Photoperiods and High Temperature in Chilo suppressalis.

Survival and adaptation to seasonal changes are challenging for insects. Many temperate insects such as the rice stem borer (Chilo suppressalis) overcome the adverse situation by entering diapause, wherein development changes dynamically occur and metabolic activity is suppressed. The photoperiod and temperature act as major environmental stimuli of diapause. However, the physiological and molecular mechanisms that interpret the ecologically relevant environmental cues in ontogenetic development during diapause termination are poorly understood. Here, we used genome-wide high-throughput RNA-sequencing to examine the patterns of gene expression during diapause termination in C. suppressalis. Major shifts in biological processes and pathways including metabolism, environmental information transmission, and endocrine signalling were observed across diapause termination based on over-representation analysis, short time-series expression miner, and gene set enrichment analysis. Many new pathways were identified in diapause termination including circadian rhythm, MAPK signalling, Wnt signalling, and Ras signalling, together with previously reported pathways including ecdysteroid, juvenile hormone, and insulin/insulin-like signalling. Our results show that convergent biological processes and molecular pathways of diapause termination were shared across different insect species and provided a comprehensive roadmap to better understand diapause termination in C. suppressalis.

Downregulation of RPS14 inhibits the proliferation and metastasis of estrogen receptor-positive breast cancer cells.

Ribosomal protein S14 (RPS14) is a component of the 40S ribosomal subunit and is considered to be indispensable for ribosomal biogenesis. Previously, we found that RPS14 was significantly downregulated in estrogen receptor-positive (ER+) breast cancer cells following treatment with 4-hydroxytamoxifen (4-OH-TAM). However, its role in breast cancer remains poorly understood. In the present study, we sought to demonstrate, for the first time, that RPS14 is highly expressed in ER+ breast cancer tissues and its downregulation can significantly inhibit the proliferation, cycle, and metastasis of ER+ breast cancer cells, as well as induce cell apoptosis. Quantitative RT-PCR and western blotting were used to determine the expression of target genes. Herein, lentivirus-mediated small hairpin RNA (shRNA) targeting RPS14 was designed to determine the impact of RPS14 knockdown on ER+ breast cancer cells. Further, bioinformatics analysis was used to reveal the significance of differentially expressed genes in RPS14 knockdown breast cancer cells. RPS14 was highly expressed in ER+ breast cancer tissues compared to ER- tissues. The downregulation of RPS14 in two ER+ breast cancer cell lines suppressed cell proliferation, cell cycle and metastasis, and induced apoptosis. Based on bioinformatics analysis, the expression level of several significant genes, such as ASNS, Ret, and S100A4, was altered in breast cancer cells after RPS14 downregulation. Furthermore, the BAG2 and interferon signaling pathways were identified to be significantly activated. The downregulation of RPS14 in ER+ breast cancer cells can inhibit their proliferation and metastasis.

Resveratrol inhibits the tumor migration and invasion by upregulating TET1 and reducing TIMP2/3 methylation in prostate carcinoma cells.

BACKGROUND: Recently, resveratrol (Res) has been suggested to suppress the migration and invasion of prostate cancer (PCa). In the present study, we aimed to investigate the effects of Res on genomic DNA methylation, as well as the migration and invasion of PCa cells. METHODS: The suppression by Res of the growth of PCa cells was verified through a cytotoxicity assay. In addition, the effects of Res on 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC), and ten-eleven translocation 1 (TET1) levels were assessed, and the cell migration and invasion were also determined. The expressions of TET1, tissue inhibitor of metalloproteinases (TIMP) 2, TIMP3, MMP2, and MMP9 were detected through Western blot analysis. Afterward, TET1 was silenced using lentiviral short hairpin RNA to examine the effect of TET1 on the Res-triggered inhibition of migration and invasion of PCa cells. RESULTS: Our results showed that Res upregulated the 5hmC and TET1 levels and downregulated the 5mC level. Moreover, Res also inhibited the migration and invasion of PCa cells, promoted the demethylation of TIMP2 and TIMP3 to upregulate their expressions, and suppressed the expressions of MMP2 and MMP9. The silencing of TET1 in the presence of Res showed that Res could exert its effect through TET1. CONCLUSIONS: Our findings indicated that Res inhibited the migration and invasion of PCa cells via the TET1/TIMP2/TIMP3 pathway, which might potentially serve as a target for the treatment of PCa.

High-Throughput Two-Dimensional Polymerase Chain Reaction Technology.

Polymerase chain reaction (PCR) is a very powerful tool for clinical gene detection. Multiplex PCR especially improves the throughput of this technology. However, it is often necessary to employ techniques such as electrophoresis, mass spectrometry, or sequencing after multiplex PCR amplification for product identification, which requires additional equipment and has high risks of contamination. In this work, we developed a high-throughput two-dimensional (2D) PCR technology that can identify multiple target genes simultaneously in just one closed tube and within a relatively short time by using both fluorescence and the melting temperature (Tm). As an example, a method detecting 9 human papillomavirus (HPV) subtypes and reference genes in a single tube was successfully established using 2D PCR. If designed properly, 2D PCR is believed to have the capability to identify more than 30 genes in one closed tube at a time. This method is particularly suitable for distinguishing microorganisms, single-nucleotide polymorphisms, and the methylation of genes and will be of great help to clinical work.

Apolipoprotein M: Research Progress and Clinical Perspective.

Apolipoprotein M (apoM) was first identified and characterized to the apolipoprotein family in 1999. Human apoM gene is located in a highly conserved segment in the major histocompatibility complex (MHC) class III locus on chromosome 6 and codes for an about 23 kDa protein that structurally belongs to the lipocalin superfamily. ApoM is selectively expressed in hepatocytes and in the tubular epithelium of kidney. In human plasma, apoM is mainly confined to the high-density lipoprotein (HDL) particles, but it may also occur in other lipoprotein classes, such as in the triglyceride-rich particles after fat intake. It has been demonstrated that apoM is critical for the formation of HDL, notably pre-beta HDL1. The antiatherogenic function of HDL is well established, and its ability to promote cholesterol efflux from foam cells in the atherosclerotic lesions is generally regarded as one of the key mechanisms behind this protective function. However, HDL could also display a variety of properties that may affect the complex atherosclerotic processes by other mechanisms, thus being involved in processes related to antioxidant defense, immune system, and systemic effects in septicemia, which may be partly contributed via its apolipoproteins and/or phospholipids. Moreover, it has been demonstrated that apoM functions as a natural carrier of sphingosin-1-phosphate (S1P) in vivo which may be related to its antiatherosclerotic and protective effects on endothelial cell barrier and anti-inflammatory properties. These may also provide a link between the diverse effects of HDL.

Systematic Review and Meta-Analysis of the Prognostic Value of Serum High-Density Lipoprotein Cholesterol Levels for Solid Tumors.

Numerous studies have demonstrated that serum high-density lipoprotein cholesterol (HDL-C) levels correlate strongly with cancer patient survival. However, other studies have had the opposite results. We therefore conducted a systematic review and meta-analysis to assess the prognostic value of HDL-C levels in people with cancer. We searched PubMed, Embase, and the Cochrane Library (last update by December 28, 2017) for studies evaluating the effect of serum HDL-C levels on cancer patient prognosis. Data from 25 studies covering13,140 patients were included. Combined hazard ratios (HRs) for overall survival (OS) and disease-free survival (DFS) were assessed using fixed-effects and random-effects models. High serum HDL-C levels were associated with better OS (pooled HR = 0.70; 95% confidence interval (CI) (0.60-0.82). In the subgroup, the relative high level of HDL-C yielded a favorable outcome in most of tumor types. However, in the nasopharyngeal carcinoma subgroup, the correlation was not significant (combined HR = 1.31; 95% CI (0.91-1.90)). High serum HDL-C levels were associated with better DFS (pooled HR = 0.64; 95% confidence interval (CI) (0.50-0.81)). This meta-analysis demonstrates that high serum HDL-C levels are associated with better OS in patients with solid tumors, but not nasopharyngeal carcinoma; and high serum HDL-C levels are associated with better DFS.

miR-10b Downregulated by DNA Methylation Acts as a Tumor Suppressor in HPV-Positive Cervical Cancer via Targeting Tiam1.

BACKGROUND/AIMS: microRNAs (miRNAs) are known to act as oncogenes or tumor suppressors in diverse cancers. Although miR-10b is an oncogene implicated in many tumors, its role in cervical cancer (CC) remains largely unclear. Here, we investigated the function and underlying mechanisms of miR-10b in human CC. METHODS: Quantitative RT-PCR was used to measure miR-10b expression in CC and normal tissues, and its association with clinicopathologic features was analyzed. Methylation of CpG sites in the miR-10b promoter was analyzed by methylation sequencing. Cell proliferation, apoptosis, migration, and invasion assays were used to elucidate the biological effects of miR-10b and expression of the target gene was assayed with Western blot. RESULTS: miR-10b was downregulated in CC tissues compared with normal tissues, and less miR-10b expression was associated with larger tumors, vascular invasion and HPV-type 16 positivity. miR-10b expression decreased in HeLa (HPV18-positive) and SiHa (HPV16-positive) cells compared with C-33A (HPV-negative), but increased after treatment with 5-Aza-CdR. Methylation ratio of site -797 in the miR-10b promoter in C-33A was lower than that in HeLa and SiHa. Further analysis indicates that site -797 is located within a transcription factor AP-2A (TFAP2A) binding element. Functionally, overexpression of miR-10b in HeLa and SiHa suppressed cell proliferation, migration and invasion, and induced apoptosis and miR-10b downregulation had opposite effects. Mechanistically, T-cell lymphoma invasion and metastasis 1 (Tiam1) was identified as a direct and functional target of miR-10b. CONCLUSION: miR-10b acts as a tumor suppressor in CC by suppressing oncogenic Tiam1, and its expression may be downregulated through methylation of TFAP2A binding element by HPV.

Apolipoprotein M promotes proliferation and invasion in non-small cell lung cancers via upregulating S1PR1 and activating the ERK1/2 and PI3K/AKT signaling pathways.

Apolipoprotein M (ApoM) is a sphingosine 1-phosphate (S1P) carrier involved in the regulation of S1P. Signaling pathways involving sphingosine kinases (SphKs) and S1P-S1P receptors (S1PRs) play important roles in the oncogenesis of multiple cancers including non-small cell lung cancer (NSCLC). In the present study we have clarified the potential roles of ApoM on the oncogenesis process of NSCLC cells. We detected the ApoM expression in NSCLC tissues and further analyzed its clinical significance. Moreover, we determined effects of ApoM overexpression on tumor cellular behaviours of NSCLC in vitro and in vivo. Our results demonstrated that ApoM protein mass were clearly higher in the NSCLC tissues than in non-NSCLS tissues. Overexpression of ApoM could promote NSCLC cell proliferation and invasion in vitro and tumor growth in vivo, which might be via upregulating S1PR1 and activating the ERK1/2 and PI3K/AKT signaling pathways. It is concluded that up-regulation of ApoM in NSCLC might be associated with the tumor induced inflammation and tumor microenvironment as well as promoting oncogenesis of NSCLC. Further study needs to elucidate the underlying mechanisms.

Prognostic role of long non-coding RNA XIST expression in patients with solid tumors: a meta-analysis.

BACKGROUND: The aberrant expression of long non-coding RNA (lncRNA) X inactivate-specific transcript (XIST) has been demonstrated to be involved in the tumourigenesis and the development of various cancers. Therefore, we conducted a meta-analysis to assess the prognostic role of lncRNA XIST expression in solid tumors. METHODS: The databases of PubMed, EMBase, Web of Science, Cochrane library (up to Dec 31, 2017) were searched for the related studies and identified 15 eligible studies containing 1209 patients to include in the meta-analysis. Hazards ratios (HRs) with corresponding 95% confidence intervals (CIs) were pooled to estimate the association between lncRNA XIST expression and survival of cancer patients from Asian. RESULTS: The result showed that higher lncRNA XIST expression in cancer tissue was related to a worse overall survival (OS) (HR = 1.54, 95% CI 1.07-2.23). In subgroup analysis, it revealed that lncRNA XIST overexpression was significantly associated with worse OS in digestive system tumors (HR = 1.67, 95% CI 1.11-2.51, p = 0.031). In addition, the association between high lncRNA XIST expression and poor OS was also statistically significant in other subgroups, including multivariate analysis (HR = 2.39, 95% CI 1.28-4.46, p = 0.006, random-effect), patients' number was greater than 65 (HR = 1.75, 95% CI 1.24-2.47, p = 0.001, random-effect), and reported in text (HR = 2.50, 95% CI 1.49-4.18, p = 0.000, random-effect). CONCLUSIONS: The expression of lncRNA XIST could be regarded as a poor prognostic biomarker for solid tumors, which might shed new light on epigenetic diagnostics and therapeutics in tumors.

Detection of simultaneous multi-mutations using base-quenched probe.

The base-quenched probe method for detecting single nucleotide polymorphisms (SNPs) relies on real-time PCR and melting-curve approaches. Here, we applied the most common commercial fluorophores including FAM, HEX, CY5, CY3, TET, JOE, Texas Red and ROX for labeling probes to detect multi-mutations simultaneously according to the different fluorescence channels. Accuracy of the method was confirmed by direct sequencing. The results demonstrated that all above dyes could be influenced by bases and could be applied to detect SNPs. Furthermore, this method was applied to detect APOM rs707921, APOM rs707922 and MCP-1 rs1024611 simultaneously, which was demonstrated successfully.

Correction: The mechanism and regularity of quenching the effect of bases on fluorophores: the base-quenched probe method.

Correction for 'The mechanism and regularity of quenching the effect of bases on fluorophores: the base-quenched probe method' by Huihui Mao et al., Analyst, 2018, 143, 3292-3301.

The mechanism and regularity of quenching the effect of bases on fluorophores: the base-quenched probe method.

The base-quenched probe method for detecting single nucleotide polymorphisms (SNPs) relies on real-time PCR and melting-curve analysis, which might require only one pair of primers and one probe. At present, it has been successfully applied to detect SNPs of multiple genes. However, the mechanism of the base-quenched probe method remains unclear. Therefore, we investigated the possible mechanism of fluorescence quenching by DNA bases in aqueous solution using spectroscopic techniques. It showed that the possible mechanism might be photo-induced electron transfer. We next analyzed electron transfer or transmission between DNA bases and fluorophores. The data suggested that in single-stranded DNA, the electrons of the fluorophore are transferred to the orbital of pyrimidine bases (thymine (T) and cytosine (C)), or that the electron orbitals of the fluorophore are occupied by electrons from purine bases (guanine (G) and adenine (A)), which lead to fluorescence quenching. In addition, the electrons of a fluorophore excited by light can be transmitted along double-stranded DNA, which gives rise to stronger fluorescence quenching. Furthermore, we demonstrated that the quenching efficiency of bases is in the order of G > C ≥ A ≥ T and the capability of electron transmission of base-pairs in double-stranded DNA is in the order of CG[combining low line] ≥ GC[combining low line] > TA[combining low line] ≥ AT[combining low line] (letters representing bases on the complementary strand of the probe are bold and underlined), and the most common commercial fluorophores including FAM, HEX, TET, JOE, and TAMRA could be influenced by bases and are in line with this mechanism and regularity.

Increased apolipoprotein M induced by lack of scavenger receptor BI is not activated via HDL-mediated cholesterol uptake in hepatocytes.

BACKGROUND: Scavenger receptor BI (SR-BI) is a classic high-density lipoprotein (HDL) receptor, which mediates selective lipid uptake from HDL cholesterol esters (HDL-C). Apolipoprotein M (ApoM), as a component of HDL particles, could influence preß-HDL formation and cholesterol efflux. The aim of this study was to determine whether SR-BI deficiency influenced the expression of ApoM. METHODS: Blood samples and liver tissues were collected from SR-BI gene knockout mice, and serum lipid parameters, including total cholesterol (TC), triglyceride (TG), high and low-density lipoprotein cholesterol (HDL-C and LDL-C) and ApoM were measured. Hepatic ApoM and ApoAI mRNA levels were also determined. In addition, BLT-1, an inhibitor of SR-BI, was added to HepG2 cells cultured with cholesterol and HDL, under serum or serum-free conditions. The mRNA and protein expression levels of ApoM were detected by RT-PCR and western blot. RESULTS: We found that increased serum ApoM protein levels corresponded with high hepatic ApoM mRNA levels in both male and female SR-BI-/- mice. Besides, serum TC and HDL-C were also significantly increased. Treatment of HepG2 hepatoma cells with SR-BI specific inhibitor, BLT-1, could up-regulate ApoM expression in serum-containing medium but not in serum-free medium, even in the presence of HDL-C and cholesterol. CONCLUSIONS: Results suggested that SR-BI deficiency promoted ApoM expression, but the increased ApoM might be independent from HDL-mediated cholesterol uptake in hepatocytes.