qPCR Experiments Research Articles

Toxic effects of ammonia on the intestine of the Asian clam (Corbicula fluminea)

Intestines contain a large number of microorganisms that collectively play a vital role in regulating physiological and biochemical processes, including digestion, water balance, and immune function. In this study, we explored the effects of ammonia stress on intestinal inflammation, the antioxidant system, and the microbiome of the Asian clam (Corbicula fluminea). Exposure to varying ammonia concentrations (10 and 25 mg N/L) and exposure times (7 and 14 days) resulted in damage to C. fluminea intestinal tissue, according to histological analysis. Furthermore, intestinal inflammatory responses and damage to the antioxidant system were revealed through qPCR, ELISA, and biochemical analysis experiments. Inflammatory responses were more severe in the treatment group exposed to a lower concentration of ammonia. High-throughput 16S rDNA sequencing showed that ammonia stress under different conditions altered intestinal bacterial diversity and microbial community composition, particularly impacting the dominant phylum Proteobacteria and genus Aeromonas. These results indicate that ammonia stress can activate intestinal inflammatory reactions, damage the intestinal antioxidant system, and alter intestinal microbial composition, thereby impeding intestinal physiological function and seriously threatening the health of C. fluminea.

Diverse Trajectories Drive the Expression of a Giant Virus in the Oomycete Plant Pathogen Phytophthora parasitica

Giant viruses of amoebas, recently classified in the class Megaviricetes, are a group of viruses that can infect major eukaryotic lineages. We previously identified a set of giant virus sequences in the genome of Phytophthora parasitica, an oomycete and a devastating major plant pathogen. How viral insertions shape the structure and evolution of the invaded genomes is unclear, but it is known that the unprecedented functional potential of giant viruses is the result of an intense genetic interplay with their hosts. We previously identified a set of giant virus sequences in the genome of P. parasitica, an oomycete and a devastating major plant pathogen. Here, we show that viral pieces are found in a 550-kb locus and are organized in three main clusters. Viral sequences, namely RNA polymerases I and II and a major capsid protein, were identified, along with orphan sequences, as a hallmark of giant viruses insertions. Mining of public databases and phylogenetic reconstructions suggest an ancient association of oomycetes and giant viruses of amoeba, including faustoviruses, African swine fever virus (ASFV) and pandoraviruses, and that a single viral insertion occurred early in the evolutionary history of oomycetes prior to the Phytophthora–Pythium radiation, estimated at ∼80 million years ago. Functional annotation reveals that the viral insertions are located in a gene sparse region of the Phytophthora genome, characterized by a plethora of transposable elements (TEs), effectors and other genes potentially involved in virulence. Transcription of viral genes was investigated through analysis of RNA-Seq data and qPCR experiments. We show that most viral genes are not expressed, and that a variety of mechanisms, including deletions, TEs insertions and RNA interference may contribute to transcriptional repression. However, a gene coding a truncated copy of RNA polymerase II along a set of neighboring sequences have been shown to be expressed in a wide range of physiological conditions, including responses to stress. These results, which describe for the first time the endogenization of a giant virus in an oomycete, contribute to challenge our view of Phytophthora evolution.

Genome-wide (ChIP-seq) identification of target genes regulated by WRKY33 during submergence stress in Arabidopsis

BackgroundHypoxia induced by flooding causes significant losses to crop production almost every year. However, the molecular network of submergence signaling pathway is still poorly understood. According to previous studies, transgenic plants overexpressing the WRKY33 gene showed enhanced resistance to submergence stress. Thus, this transcription factor may regulate a series of target genes in response to submergence. Here, to determine putative downstream targets of WRKY33 at a genome-wide scale in Arabidopsis thaliana, we performed the chromatin immunoprecipitation sequencing (ChIP-seq) using 35S:FLAG-WRKY33 overexpression transgenic lines (WRKY33-OE) after 24 h of submergence treatment.ResultsUsing ChIP-seq data, we identified a total of 104 WRKY33-binding genes under submergence stress (WRKY33BGSs). Most WRKY33BGSs are involved in the oxidation-reduction process, programmed cell death in response to reactive oxygen species, lipid biosynthesis process, and other processes related to stress responses. Moreover, the major motif identified in the WRKY33BGSs promoters is a new cis-element, TCTCTC (named here as “TC box”). This cis-element differs from the previously known W box for WRKY33. Further qPCR experiments verified that genes carrying this motif in their promoters could be regulated by WRKY33 upon submergence treatment.ConclusionsOur study has identified a new putative binding motif of WRKY33 and recovered numerous previously unknown target genes of WRKY33 during submergence stress. The WRKY33 gene positively participates in flooding response probably by transcriptional regulation of the downstream submergence-related target genes via a “TC box”.

Efficiency Correction Is Required for Accurate Quantitative PCR Analysis and Reporting.

Quantitative PCR (qPCR) aims to measure the DNA or RNA concentration in diagnostic and biological samples based on the quantification cycle (Cq) value observed in the amplification curves. Results of qPCR experiments are regularly calculated as if all assays are 100% efficient or reported as just Cq, ΔCq, or ΔΔCq values. When the reaction shows specific amplification, it should be deemed to be positive, regardless of the observed Cq. Because the Cq is highly dependent on amplification efficiency that can vary among targets and samples, accurate calculation of the target quantity and relative gene expression requires that the actual amplification efficiency be taken into account in the analysis and reports. PCR efficiency is frequently derived from standard curves, but this approach is affected by dilution errors and hampered by properties of the standard and the diluent. These factors affect accurate quantification of clinical and biological samples used in diagnostic applications and collected in challenging conditions. PCR efficiencies determined from individual amplification curves avoid these confounders. To obtain unbiased efficiency-corrected results, we recommend absolute quantification with a single undiluted calibrator with a known target concentration and efficiency values derived from the amplification curves of the calibrator and the unknown samples. For meaningful diagnostics or biological interpretation, the reported results of qPCR experiments should be efficiency corrected. To avoid ambiguity, the Minimal Information for Publications on Quantitative Real-Time PCR Experiments (MIQE) guidelines checklist should be extended to require the methods that were used (1) to determine the PCR efficiency and (2) to calculate the reported target quantity and relative gene expression value.

Survey of the Transcription Factor Responses of Mouse Lung Alveolar Macrophages to Pneumocystis murina.

Pneumocystis jirovecii is a fungal pathogen that can cause life-threatening infections in individuals who are immunocompromised. Acquired via inhalation, upon entering the respiratory tract, the fungi first encounter innate immune cells such as alveolar macrophages (AMs). Relatively little is known about the AM cellular responses to the organism, and particularly transcription factor (TF) profiles leading to early host responses during infection. Utilizing the Mouse Transcription Factors RT2 Profiler™ PCR Array, we report an initial TF survey of these macrophage and Pneumocystis interactions. Expression levels of a panel of mouse TFs were compared between unstimulated and Pneumocystis murina-stimulated AMs. Interestingly, a number of TFs previously implicated in pathogen–host cell interactions were highly up- or downregulated, including hif1a and Pparg. qPCR experiments were further conducted to verify the results of these surveyed transcripts. Furthermore, with immunoblotting, we show that HIF-1A and PPAR-γ are indeed significantly upregulated and downregulated, respectively. Lastly, and importantly, we report that in the mouse model of Pneumocystis pneumonia (PCP), which mimics human Pneumocystis jirovecii pneumonia (PJP), qPCR analysis of Pneumocystis murina lungs also mimic the initial TF profile analysis, suggesting an importance for these TFs in immunocompromised hosts with Pneumocystis pneumonia. These data demonstrate the use of TF profiling in host AMs and Pneumocystis organism interactions that may lead to a better understanding of the specific inflammatory responses of the host to Pneumocystis pneumonia and may inform novel strategies for potential therapeutics.

The Transcriptome of SH-SY5Y at Single-Cell Resolution: A CITE-Seq Data Analysis Workflow.

Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq) is a recently established multimodal single cell analysis technique combining the immunophenotyping capabilities of antibody labeling and cell sorting with the resolution of single-cell RNA sequencing (scRNA-seq). By simply adding a 12-bp nucleotide barcode to antibodies (cell hashing), CITE-seq can be used to sequence antibody-bound tags alongside the cellular mRNA, thus reducing costs of scRNA-seq by performing it at the same time on multiple barcoded samples in a single run. Here, we illustrate an ideal CITE-seq data analysis workflow by characterizing the transcriptome of SH-SY5Y neuroblastoma cell line, a widely used model to study neuronal function and differentiation. We obtained transcriptomes from a total of 2879 single cells, measuring an average of 1600 genes/cell. Along with standard scRNA-seq data handling procedures, such as quality checks and cell filtering procedures, we performed exploratory analyses to identify most stable genes to be possibly used as reference housekeeping genes in qPCR experiments. We also illustrate how to use some popular R packages to investigate cell heterogeneity in scRNA-seq data, namely Seurat, Monocle, and slalom. Both the CITE-seq dataset and the code used to analyze it are freely shared and fully reusable for future research.

Reference Gene Optimization for Ganglia of the Sympathetic Nervous System in Male and Female Mice after Exposure to Cold Stress

The sympathetic branch of the autonomic nervous system (ANS) regulates the body’s response to psychogenic and systemic stress. In response to stress, endocrine pathways are activated to rebalance physiological changes and restore homeostasis. Gene expression analysis through quantitative real-time PCR (qPCR) is a key method to assess differential gene expression in tissue and cell samples, with high sensitivity and specificity. To assess differential gene expression between samples, qPCR data must be normalized to two or more reference genes to account for technical variation in nucleic acid loading between samples, ensuring data represents target gene expression due to experimental treatments (1). Reference genes must be selected and tested for each experimental paradigm, showing stability of expression between samples and treatments. Reference genes are usually constitutively expressed genes required for cellular maintenance, such as well known “housekeeping” genes or genes encoding ribosomal RNAs. Ganglia of the sympathetic nervous system (SNS) are small in size, and thus total yields of RNA for qPCR experiments are limited. Our group has established a protocol for the isolation of adrenal glands, superior cervical, celiac, and stellate ganglia using a dissecting scope and anatomical landmarks in mice. Here we present optimization data assessing five commonly used reference genes for normalization of qPCR data in three ganglia of the SNS (superior cervical, stellate, and celiac) and adrenal glands. We have evaluated their suitability as reference genes in these tissues after acclimation to cold (4°C) stress compared to the same tissues from animals housed at thermoneutrality (30°C). Through qPCR reaction optimization and subsequent calculations of geNorm stability-measure M, we present optimized primer sequences and reaction conditions, and provide recommendations for combinations of three or more reference genes to use for normalization in gene expression analysis experiments in adrenal gland, superior cervical, stellate or celiac ganglia from male and female mice exposed to thermoneutrality or cold. This research will be valuable to groups interested in SNS physiology and facilitate a streamlined approach to gene expression analysis given the low RNA availability from these minute tissue samples, saving valuable sample, costs and time in carrying out qPCR experiments. Reference: (1) Bustin et al., Clin Chem. 2009 Jan 27;55(4):611-622.

Gene knockout revealed the role of gene feoA in cell growth and division of Lactobacillus delbrueckii subsp. bulgaricus.

Gene feoA plays an important role in cell growth because of its function of transport Fe2+ which is a necessary element for cells. In this study, the recombinant plasmid pUC19-feoA-Tet was successfully constructed using the inserted gene inactivation method. Using the homologous recombination technique, the tet gene was used as a resistance screening marker to knock out the feoA gene of Lactobacillus delbrueckii subsp. bulgaricus 34.5 (strain 34.5). Comparative analysis of growth curves revealed the growth changes in the absence of feoA gene in strain 34.5. The results showed that the growth of the bacteria was prolonged by 2h and could be restored in the stationary phase. To further study whether feoA is related to the cell division of strain 34.5, the qPCR experiment was carried out. The results showed that, compared with the wild-type strain, the expression of genes related to cell division in the mutant strain was up-regulated in the pre-log phase, down-regulated in the late-log phase, and returned to the original level in the stationary phase. These findings provide ideas for Lactobacillus delbrueckii subsp. bulgaricus to control division and cell cycle.

Early-stage iron deficiency alters physiological processes and iron transporter expression, along with photosynthetic and oxidative damage to sorghum.

Iron (Fe) starvation in Strategy II plants is a major nutritional problem causing severe visual symptoms and yield reductions. This prompted us to investigate the physiological and molecular consequences of Fe deficiency responses at an early stage in sorghum plants. The Fe-starved sorghum did not show shoot biomass reduction, but the root length, biomass, and chlorophyll synthesis were severely affected. The chlorophyll a fluorescence analysis showed that the quantum yield efficiency of PSII (Fv/Fm) and photosynthesis performance index (Pi_ABS) in young leaves significantly reduced in response to low Fe. Besides, Fe concentration in root and shoot significantly declined in Fe-starved plants relative to Fe-sufficient plants. Accordingly, this Fe reduction in tissues was accompanied by a marked decrease in PS-release in roots. The qPCR experiment showed the downregulation of SbDMAS2 (deoxymugineic acid synthase 2), SbNAS3 (nicotianamine synthase 3), and SbYSL1 (Fe-phytosiderophore transporter yellow stripe 1) in Fe-deprived roots, suggesting that decreased rhizosphere mobilization of Fe(III)-PS contributes to reduced uptake and long-distance transport of Fe. The cis-acting elements of these gene promoters are commonly responsive to abscisic acid and methyl jasmonate, while SbYSL1 additionally responsive to salicylic acid. Further, antioxidant defense either through metabolites or antioxidant enzymes is not efficient in counteracting oxidative damage in Fe-deprived sorghum. These findings may be beneficial for the improvement of sorghum genotypes sensitive to Fe-deficiency through breeding or transgenic approaches.

GPrimer: a fast GPU-based pipeline for primer design for qPCR experiments

BackgroundDesign of valid high-quality primers is essential for qPCR experiments. MRPrimer is a powerful pipeline based on MapReduce that combines both primer design for target sequences and homology tests on off-target sequences. It takes an entire sequence DB as input and returns all feasible and valid primer pairs existing in the DB. Due to the effectiveness of primers designed by MRPrimer in qPCR analysis, it has been widely used for developing many online design tools and building primer databases. However, the computational speed of MRPrimer is too slow to deal with the sizes of sequence DBs growing exponentially and thus must be improved.ResultsWe develop a fast GPU-based pipeline for primer design (GPrimer) that takes the same input and returns the same output with MRPrimer. MRPrimer consists of a total of seven MapReduce steps, among which two steps are very time-consuming. GPrimer significantly improves the speed of those two steps by exploiting the computational power of GPUs. In particular, it designs data structures for coalesced memory access in GPU and workload balancing among GPU threads and copies the data structures between main memory and GPU memory in a streaming fashion. For human RefSeq DB, GPrimer achieves a speedup of 57 times for the entire steps and a speedup of 557 times for the most time-consuming step using a single machine of 4 GPUs, compared with MRPrimer running on a cluster of six machines.ConclusionsWe propose a GPU-based pipeline for primer design that takes an entire sequence DB as input and returns all feasible and valid primer pairs existing in the DB at once without an additional step using BLAST-like tools. The software is available at https://github.com/qhtjrmin/GPrimer.git.

Hesperetin, a dietary flavonoid, inhibits AGEs-induced oxidative stress and inflammation in RAW264.7 cells

• Three typical structural derivatives of Naringenin were tested in this paper. • Hesperetin could significantly inhibit both AGEs-induced ROS production and inflammation. • Gene set enrichment analysis was performed and twenty-three key genes related were screened. Advanced glycation end products (AGEs) excessive accumulation in the body either by exogenous intake or endogenous formation makes individuals prone to oxidative stress and inflammation damage. In this study, DCFH-DA fluorescence test and qPCR experiment were carried out to study the effect of some dietary flavonoids on AGEs induced toxicity. Among four tested flavonoids, it was found that hesperetin could significantly inhibit both AGEs-induced ROS production and gene expressions of TNF-α, IL-1β, IL-6, MCP-1, COX-2 and iNOS. High-throughput transcriptome analysis showed that the protective effect of hesperetin against AGEs-induced toxicity might be attributed to inhibit the activation of MAPK, JAK, NF-κB-related pathways. Furthermore, gene set enrichment analysis was performed using the MSigDB database and twenty-three key genes related were screened. This study might provide new ideas for the prevention of AGEs-related diseases and lay a theoretical foundation for the application of dietary flavonoids.

An investigation into nicotinic receptor involvement in mood disorders uncovers novel depression candidate genes

BackgroundWe have previously reported reduced expression of the cholinergic autoreceptor CHRM2 in Brodmann's Area (BA) 24 of the anterior cingulate cortex from subjects with major depressive disorder (MDD) and bipolar disorder (BD), consistent with a hypercholinergic state. This led us to investigate whether levels of the high affinity nicotinic acetylcholine receptors are also altered in BA 24. MethodsWe measured the binding levels of a high-affinity nicotinic receptor-selective radioligand, [3H]epibatidine, in BA 24 from subjects with MDD (n = 20), BD (n = 18) and age- and sex-matched controls (n = 20). We used qPCR to measure mRNA expression of the high affinity nicotinic acetylcholine receptor subunit CHRNB2 in these subjects. Results[3H]Epibatidine binding density and CHRNB2 mRNA expression were not significantly altered in either MDD or BD compared to control levels. While validating reference genes for our qPCR experiments, we found that the mRNA levels of 3 putative reference genes, TFB1M, PPIA and SNCA, were increased in MDD but not BD compared to controls. Further investigations in other cortical regions showed that these changes were specific to BA24. LimitationsCohort size and available patient data were limited due to standard constraints associated with post-mortem studies. ConclusionOur data suggest that decreased CHRM2 in BA24 in mood disorders is not associated with a corresponding change in high affinity nicotinic acetylcholine receptor expression. Our findings of increased TFB1M, PPIA and SNCA expression in MDD point to a broader derangement of several homeostatic pathways in MDD that are distinct from BD.

Zona Pellucida Protein 2 (ZP2) Is Expressed in Colon Cancer and Promotes Cell Proliferation.

Simple SummaryOur study shows ZP2 to be a new biomarker for diagnosis, best used in combination with other low abundant genes in colon cancer. Furthermore, ZP2 promotes cell proliferation via the ERK1/2-cyclinD1-signaling pathway. We demonstrate that ZP2 mRNA is expressed in a low-abundant manner with high specificity in subsets of cancer cell lines representing different cancer subtypes and also in a significant proportion of primary colon cancers. The potential benefit of ZP2 as a biomarker is discussed. In the second part of our study, the function of ZP2 in cancerogenesis has been analyzed. Since ZP2 shows an enhanced transcript level in colon cancer cells, siRNA experiments have been performed to verify the potential role of ZP2 in cell proliferation. Based on these data, ZP2 might serve as a new target molecule for cancer diagnosis and treatment in respective cancer types such as colon cancer.Background: Zona pellucida protein ZP2 has been identified as a new colon tumor biomarker. Its transcripts were specifically expressed in four out of four human colon cancer cell lines and enhanced in about 60% of primary colon cancer tissues when compared to matched healthy ones. ZP2 down-regulation by siRNA led to a decreased proliferation rate, EXOSC5 transcript, cyclin D1 protein level, and ERK1/2 phosphorylation state. Methods: Sensitivity and quantitative expression analysis of ZP2 transcripts in tumor and matched normal colon tissue was performed with respective cDNA preparations. Silencing RNA effects on colon cancer cells were examined by q-PCR, western blot, and proliferation rate experiments. Results: In a significant portion of 69 primary colon tumor samples, the molecule showed a low but specific expression, which revealed a sensitivity value of around 90% and a specificity value of 30% when matched to the respective normal counterparts. Down-regulation of ZP2 protein by siRNA led to a decreased proliferation rate, EXOSC5 and cyclin D1 level, and phosphorylation state of ERK1/2. ZP2 has also been found to be a cell membrane-bound protein. Conclusion: ZP2 shows an enhanced expression level in colon cancer tissue and, thus, can be used as a diagnostic tool, albeit in combination with other biomarkers. Its character as a membrane protein makes ZP2 even a potential target molecule for tumor therapy, especially as it positively affects colon cancer cell proliferation.

LncRNA MIAT activates vascular endothelial growth factor A through RAD21 to promote nerve injury repair in acute spinal cord injury

BackgroundThe main pathological feature of acute spinal cord injury (ASCI) is neuronal apoptosis and Long non-coding RNA (lncRNA) myocardial infarction-related transcript (MIAT) is involved in the regulation of neuronal apoptosis. This study aimed to investigate the role and potential mechanism of LncRNA MIAT in neuronal apoptosis induced by ASCI. MethodsAfter Lenti-MIAT lentivirus was microinjected into ASCI rats, Basso, Beattie and Bresnahan Score, Hematoxylin-eosin staining, TUNEL staining, immunohistochemical, immunofluorescence, quantitative real-time PCR and Western blot were used to observe the effect of LncRNA MIAT on the nerve function of ASCI rats. MTT and flow cytometry assays were used to identify the in vitro function of LncRNA MIAT. RNA immunoprecipitation, RNA pull-down, Cycloheximide chase and Chromatin immunoprecipitation combined with qPCR experiments were used to study the mechanism. ResultsThe overexpression of LncRNA MIAT was conducive to the recovery of motor function in ASCI rats and repressed neuronal cell apoptosis and increased neuronal cell viability. Furthermore, the overexpression of LncRNA MIAT in PC12 cells upregulated RAD21 expression by repressing RAD21 protein degradation and further promoted VEGFA transcription to inhibit neuronal cell apoptosis, ultimately improved ASCI. ConclusionOur data indicated that the overexpression of LncRNA MIAT activated VEGFA through RAD21 to inhibit neuronal cell apoptosis in ASCI.

Mining the key genes for ventilator-induced lung injury using co-expression network analysis.

Mechanical ventilation is extensively adopted in general anesthesia and respiratory failure management, but it can also induce ventilator-induced lung injury (VILI). Therefore, it is of great urgency to explore the mechanisms involved in the VILI pathogenesis, which might contribute to its future prevention and treatment. Four microarray datasets from the GEO database were selected in our investigation, and were subjected to the Weighted Gene Co-Expression Network Analysis (WGCNA) to identify the VILI-correlated gene modules. The limma package in R software was used to identify the differentially expressed genes (DEGs) between the VILI and control groups. WGCNA was constructed by merging the GSE9314, GSE9368, GSE11434 and GSE11662 datasets. A total of 49 co-expression network modules were determined as associated with VILI. The intersected genes between hub genes screened from DEGs for VILI and those identified using WGCNA were as follows: Tlr2, Hmox1, Serpine1, Mmp9, Il6, Il1b, Ptgs2, Fos and Atf3, which were determined to be key genes for VILI. Those key genes were validated by GSE86229 and quantitative PCR (qPCR) experiment to have significantly statistical difference in their expression between the VILI and control groups. In a nutshell, nine key genes with expression differences in VILI were screened by WGCNA by integrating multiple datasets.

RNA sequencing reveals the expression profiles of circRNA and identifies a four-circRNA signature acts as a prognostic marker in esophageal squamous cell carcinoma

BackgroundCircRNAs with tissue-specific expression and stable structure may be good tumor prognostic markers. However, the expression of circRNAs in esophageal squamous cell carcinoma (ESCC) remain unknown. We aim to identify prognostic circRNAs and construct a circRNA-related signature in ESCC.MethodsRNA sequencing was used to test the circRNA expression profiles of 73 paired ESCC tumor and normal tissues after RNase R enrichment. Bioinformatics methods, such as principal component analysis (PCA), t-distributed Stochastic Neighbor Embedding (t-SNE) algorithm, unsupervised clustering and hierarchical clustering were performed to analyze the circRNA expression characteristics. Univariate cox regression analysis, random survival forests-variable hunting (RSFVH), Kaplan–Meier analysis, multivariable Cox regression and ROC (receiver operating characteristic) curve analysis were used to screen the prognostic circRNA signature. Real-time quantitative PCR (qPCR) and fluorescence in situ hybridization(FISH) in 125 ESCC tissues were performed.ResultsCompared with normal tissues, there were 11651 differentially expressed circRNAs in cancer tissues. A total of 1202 circRNAs associated with ESCC prognosis (P < 0.05) were identified. Through bioinformatics analysis, we screened a circRNA signature including four circRNAs (hsa_circ_0000005, hsa_circ_0007541, hsa_circ_0008199, hsa_circ_0077536) which can classify the ESCC patients into two groups with significantly different survival (log rank P < 0.001), and found its predictive performance was better than that of the TNM stage(0.84 vs. 0.66; 0.65 vs. 0.62). Through qPCR and FISH experiment, we validated the existence of the screened circRNAs and the predictive power of the circRNA signature.ConclusionThe prognostic four-circRNA signature could be a new prognostic biomarker for ESCC, which has high clinical application value.

Validation of bacterial markers to discriminate against the source of nitrate contamination: a promising application within the EU Nitrates Directive

The European Community (EC) Nitrates Directive (ND) (Council Directive 1991/676/EEC) aims to avoid water pollution by nitrates from poor farming practices. Under the ND, Nitrate Vulnerable Zones (NVZs) have been defined as areas where the concentration of agricultural nitrates in surface or groundwater exceeds 50 mg/L. Groundwater is one of the main sources of drinking water in Europe, so ensuring its quality is of significant importance. Monitoring of water parameters, the identification of pollution, the development of good agricultural practice codes is included in ND as measures and action programs. ND provides for the attribution of areas affected by nitrate pollution to the NVZ in which farmers must comply with measures necessary to reduce nitrogen in excess and protect the quality of environmental matrices. However, in some cases the quality of water bodies remains poor, suggesting that some action measures are ineffective or need improvements. Nevertheless, nitrates in excess in groundwater might be related to industrial inputs, untreated waste discharge, and sewage spilling. Due to this, identifying non-agricultural contributions to nitrate groundwater pollution can be of great interest. With this aim, the employment of biomarkers such as microbes associated with the intestinal tract of a specific host is under study for identifying fecal pollution. This strategy is known, in scientific literature, as Microbial Source Tracking (MST)(Furtula et al. 2011)The amplification of 16S rRNA genes of host-specific Bacteroidales allows discriminating against human and livestock fecal sources in samples from nitrate polluted environment. The aim of this work is to evaluate the sensitivity and specificity of these intestinal biomarkers in groundwater samples collected along with the Apulian Region (Southern Italy) in order to assess the applicability of the MST in the employ of ND. A preliminary study was carried out to validate the performance of seven markers for MST using two different approaches: Polimerase Chain Reaction (PCR) and quantitative Real-time PCR (qPCR) assays. For both PCR and qPCR experiments selected primer sets were checked using fecal samples of known origin as positive controls. PCR assay was used for human (HF74 and Enterococcus faecalis) (Bernhard and Field 2000, Jackson et al. 2004), cattle (CF123) (Bernhard and Field 2000), equine (HoF597) (Dick et al. 2005), and pig (Pig163) (Dick et al. 2005) markers screening. Two additional markers were tested through Real-time PCR: human (Human- Bacteroides) (Seurinck et al. 2005) and zootechnical (BacPre I) (Kobayashi et al. 2012). The results indicate that biomarkers can be considered reliable in distinguishing human from animal pollution. Nevertheless, our studies show that the tests conducted with the human Enterococcus faecalis biomarker do not discriminate the zootechnical source from the human one. In some cases, PCR-tested biomarkers cannot determine the source of contamination in environmental matrices due to the detection limit. Animal and human fecal markers were widely detected on eleven groundwater samples through Real Time PCR, highlighting the prevalent source of contamination in the environmental matrix. This research provides evidence that MST technology is a valid tool for local authorities to identify the source of nitrate contamination and review uncertainties during the NVZs definition and the action program development required by the European Nitrate Directive.

Cohesin promotes HSV-1 lytic transcription by facilitating the binding of RNA Pol II on viral genes

BackgroundHerpes Simplex Virus type I (HSV-1) is a large double-stranded DNA virus that enters productive infection in epithelial cells and reorganizes the host nucleus. Cohesin, a major constituent of interphase and mitotic chromosomes comprised of SMC1, SMC3, and SCC1 (Mcd1/Rad21), SCC3 (SA1/SA2), have diverse functions, including sister chromatid cohesion, DNA double-stranded breaks repair, and transcriptional control. Little is known about the role of cohesin in HSV-1 lytic infection.MethodsWe measured the effect on HSV-1 transcription, genome copy number, and viral titer by depleting cohesin components SMC1 or Rad21 using RNAi, followed by immunofluorescence, qPCR, and ChIP experiments to gain insight into cohesin's function in HSV-1 transcription and replication.ResultsHere, we report that cohesion subunits SMC1 and Rad21 are recruited to the lytic HSV-1 replication compartment. The knockdown results in decreased viral transcription, protein expression, and maturation of viral replication compartments. SMC1 and Rad21 knockdown leads to the reduced overall RNA pol II occupancy level but increased RNA pol II ser5 phosphorylation binding on viral genes. Consistent with this, the knockdown increased H3K27me3 modification on these genes.ConclusionsThese results suggest that cohesin facilitates HSV-1 lytic transcription by promoting RNA Pol II transcription activity and preventing chromatin's silencing on the viral genome.

Quorum Sensing Signaling Molecules Positively Regulate c-di-GMP Effector PelD Encoding Gene and PEL Exopolysaccharide Biosynthesis in Extremophile Bacterium Acidithiobacillus thiooxidans.

Acidithiobacillus species are fundamental players in biofilm formation by acidophile bioleaching communities. It has been previously reported that Acidithiobacillus ferrooxidans possesses a functional quorum sensing mediated by acyl-homoserine lactones (AHL), involved in biofilm formation, and AHLs naturally produced by Acidithiobacillus species also induce biofilm formation in Acidithiobacillus thiooxidans. A c-di-GMP pathway has been characterized in Acidithiobacillus species but it has been pointed out that the c-di-GMP effector PelD and pel-like operon are only present in the sulfur oxidizers such as A. thiooxidans. PEL exopolysaccharide has been recently involved in biofilm formation in this Acidithiobacillus species. Here, by comparing wild type and ΔpelD strains through mechanical analysis of biofilm-cells detachment, fluorescence microscopy and qPCR experiments, the structural role of PEL exopolysaccharide and the molecular network involved for its biosynthesis by A. thiooxidans were tackled. Besides, the effect of AHLs on PEL exopolysaccharide production was assessed. Mechanical resistance experiments indicated that the loss of PEL exopolysaccharide produces fragile A. thiooxidans biofilms. qRT-PCR analysis established that AHLs induce the transcription of pelA and pelD genes while epifluorescence microscopy studies revealed that PEL exopolysaccharide was required for the development of AHL-induced biofilms. Altogether these results reveal for the first time that AHLs positively regulate pel genes and participate in the molecular network for PEL exopolysaccharide biosynthesis by A. thiooxidans.

Global proteome profiling of human livers upon ischemia/reperfusion treatment

Hepatic ischemia/reperfusion (I/R) injury represents a major risk factor for liver transplantation and is related to graft dysfunction and acute/chronic rejection. However, a significant part of these processes remain poorly characterized. To reveal differences in the proteome during liver I/R injury, we collected human liver biopsy samples during hepatectomy before and after the Pringle maneuver and conducted a TMT-based proteomic analysis through quantitative high-throughput mass spectrometry. We used a fold-change threshold of 1.3 and a t-test p-value < 0.05 as the criteria to identify 5,257 total quantifiable proteins. The levels of 142 proteins were increased, while the levels of 103 proteins were decreased in response to hepatic I/R treatment. Bioinformatic analysis further revealed that these differentially expressed proteins are mainly involved in multiple biological functions and enzyme-regulated metabolic pathways. Most proteins whose expression was changed are related to the defense, immune and inflammatory responses as well as lipid and steroid metabolic processes. Based on this finding, we developed a panel for targeted proteomic analysis and used the parallel reaction monitoring (PRM) method, qPCR and western blotting experiments to validate alterations in the expression of some of the identified proteins. The upregulated proteins were found to be involved in immunity and inflammatory responses, and downregulated proteins were enriched in metabolic pathways. This study therefore may provide a research direction for the design of new therapeutic strategies for hepatic ischemia/reperfusion injury.