Synthetic DNA Fragments Research Articles

A novel test strip assay based on gold nanoparticles-labeled nucleic acid probe for rapid detection of Vibrio splendidus

Vibrio splendidus is an opportunistic pathogen in aquaculture. It can infect a variety of aquaculture animals and has caused huge losses to the aquaculture industry. In this study, a novel and efficient method for detecting V. splendidus was developed by combining the exonuclease Ⅲ amplification strategy with a nucleic acid test strip developed based on gold nanoparticles-labeled DNA probe. The results could be directly visualized by naked eyes, and this system overcame the difficulty in preparation of the monoclonal antibody used in conventional immunostrip. Upon optimization of experimental conditions, the detection limit of the strip was 5 ng/mL for the synthetic oligonucleotide DNA fragment and 10 ng/mL for the actual genomic DNA sample of V. splendidus. This test strip was more sensitive compared with the PCR method and was specific for the detection of V. splendidus. The rapid preparation of nucleic acid strip and the efficient detection of V. splendidus open a new way for the prevention and control of aquatic diseases.

A panel of real-time PCR assays for the detection of Bourbon virus, Heartland virus, West Nile virus, and Trypanosoma cruzi in major disease-transmitting vectors.

Vector-borne pathogens, such as Bourbon virus (BRBV), Heartland virus (HRTV), West Nile virus (WNV), and Trypanosoma cruzi (TCZ) are a great threat to public health and animal health. We developed a panel of TaqMan real-time PCR assays for pathogen surveillance. PCR targets were selected based on nucleic acid sequences deposited in GenBank. Primers and probes were either designed de novo or selected from publications. The coverages and specificities of the primers and probes were extensively evaluated by performing BLAST searches. Synthetic DNA or RNA fragments (gBlocks) were used as PCR templates in initial assay development and PCR positive controls in subsequent assay validation. For operational efficiency, the same thermocycling profile was used in BRBV, HRTV, and WNV reverse-transcription quantitative PCR (RT-qPCR) assays, and a similar thermocycling profile without the initial reverse-transcription step was used in TCZ qPCR. The assays were optimized by titrating primer and probe concentrations. The analytical sensitivities were 100, 100, 10, and 10 copies of gBlock per reaction for BRBV (Cq = 36.0 ± 0.7), HRTV (Cq = 36.6 ± 0.9), WNV (Cq = 35.5 ± 0.4), and TCZ (Cq = 38.8 ± 0.3), respectively. PCR sensitivities for vector genomic DNA or RNA spiked with gBlock reached 100, 100, 10, and 10 copies per reaction for BRBV, HRTV, WNV, and TCZ, respectively. PCR specificity evaluated against a panel of non-target pathogens showed no significant cross-reactivity. Our BRBV, HRTV, WNV, and TCZ PCR panel could support epidemiologic studies and pathogen surveillance.

Development of a genotyping platform for SARS-CoV-2 variants using high-resolution melting analysis

IntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus causing coronavirus disease 2019 (COVID-19), has been expanding globally since late 2019. SARS-CoV-2, an RNA virus, has a genome sequence that can easily undergo mutation. Several mutated SARS-CoV-2 strains, including those with higher infectivity than others, have been reported. To reduce SARS-CoV-2 transmission, it is crucial to trace its infection sources. Here, we developed a simple, easy-to-use genotyping method to identify SARS-CoV-2 variants using a high-resolution melting (HRM) analysis. MethodsWe investigated five mutation sites, A23403G, G25563T, G26144T, T28144C, and G28882A, which are known strain determinants according to GISAID clades (L, S, V, G, GH, and GR). ResultsWe first employed synthetic DNA fragments containing the five characteristic sites for HRM analysis. All sequences clearly differentiated wild-type from mutant viruses. We then confirmed that RNA fragments were suitable for HRM analysis following reverse transcription. Human saliva did not negatively affect the HRM analysis, which supports the absence of a matrix effect. ConclusionsOur results indicate that this HRM-based genotyping method can identify SARS-CoV-2 variants. This novel assay platform potentially paves the way for accurate and rapid identification of SARS-CoV-2 infection sources.

Polymorphisms at the 3’end of the movement protein (MP) gene of grapevine Pinot gris virus (GPGV) affect virus titre and small interfering RNA accumulation in GLMD disease

Grapevine Leaf Mottling and Deformation (GLMD) is a grapevine disease that has been associated with a trichovirus, the grapevine Pinot gris virus (GPGV). A wide diversity in the severity of GLMD disease symptoms has been recorded worldwide, but the relationship of this diversity to the sequence variation in the GPGV genome is still a matter of debate. Results from comparative analysis of GPGV genomic sequences have suggested an association of polymorphisms at the 3’-end of the movement protein (MP) with GLMD severity. Here, the 3’-terminus of the MP gene of a GPGV infectious clone derived from an isolate from grapevine showing severe symptoms (fvg-12), was substituted with a 356 bp synthetic DNA fragment having a sequence resembling that of another GPGV isolate (fvg-15), recovered from an asymptomatic grapevine. The clone containing this chimeric construct was root-inoculated in virus-free Kober rootstocks along with the clones containing the fvg-12 and fvg-15 full length sequence. Remarkable differences in virus titre, accumulation of GPGV-derived small interfering RNAs (siRNAs), alterations in the gene expression of boron transporters and, to a lesser extent, in symptom expression were recorded among plants infected with either one of the three GPGV derived clones. In particular, the chimeric clone behaviour was indistinguishable from that of the donor of the small 356 bp fragment and significantly different from the other. Thus, this work experimentally confirmed the critical role of the GPGV-MP C-terminus in determining the fate of the infection, as it had been previously hypothesized on the basis of comparative sequence analysis.

The Application of Control Materials for Ongoing Quality Management of Next-Generation Sequencing in a Clinical Genetic Laboratory.

Next-generation sequencing (NGS) has played an important role in detecting genetic variants with pathologic and therapeutic potential. The advantages of NGS, such as high-throughput sequencing capacity and massively parallel sequencing, have a significant impact on realization of genetic profiling in clinical genetic laboratories. These changes have enabled clinicians to execute precision medicine in diagnosis, prognosis, and treatment for patients. However, to adapt targeted gene panels in diagnostic use, analytical validation and ongoing quality control should be implemented and applied with both practical guidelines and appropriate control materials. Several guidelines for NGS quality control recommend usage of control materials such as HapMap cell lines, synthetic DNA fragments, and genetically characterized cell lines; however, specifications or applications of such usage are insufficient to guideline method development. This review focuses on what factors should be considered before control material selection for NGS assay and practical methods of how they could be developed in clinical genetic laboratories. This review also provides the detailed sources of critical information related to control materials.

Study of the multiple incorporation of modified nucleotides into the growing DNA strand

Objectives. This study investigated the substrate properties of the modified derivatives of triphosphates of purine and pyrimidine deoxynucleosides (5-propynyl-2’-deoxyuridine-5’-triphosphate, 5-propynyl2’-deoxycytidine-5’-triphosphate, 5-methyl-2’-deoxycytidine-5’-triphosphate, and N6-methyl-2’-deoxyadenosine-5’-triphosphate) during their simultaneous incorporation in enzymatic reactions (polymerase chain and primer extension reactions).Methods. The real-time polymerase chain and primer extension reactions were used to study the substrate efficiency of modified deoxynucleotide triphosphates. Various pairwise combinations of modified derivatives were used; specially designed synthetic DNA fragments and libraries for the Systematic Evolution of Ligands by Exponential Enrichment technology were used as templates. Reactions were conducted using DNA polymerases: Taq, Vent (exo-), DeepVent (exo-), and KOD XL.Results. In each case, a pair of compounds (modified dUTP + dCTP, dUTP + dATP, and dCTP + dATP) was selected to study the simultaneous incorporation into the growing DNA strand. The most effective combinations of nucleotides for simultaneous insertion were dU and dC, having 5-propynyl substitution. The Vent (exo-) DNA polymerase was found as the most effective for the modified substrates.Conclusions. The selected compounds can be used for the enzymatic preparation of modified DNA, including aptamers with extended physicochemical properties.

Recurrent Potential G-Quadruplex Sequences in Archaeal Genomes.

Evolutionary conservation or over-representation of the potential G-quadruplex sequences (PQS) in genomes are usually considered as a sign of the functional relevance of these sequences. However, uneven base distribution (GC-content) along the genome may along the genome may result in seeming abundance of PQSs over average in the genome. Apart from this, a number of other conserved functional signals that are encoded in the GC-rich genomic regions may inadvertently result in emergence of G-quadruplex compatible sequences. Here, we analyze the genomes of archaea focusing our search to repetitive PQS (rPQS) motifs within each organism. The probability of occurrence of several identical PQSs within a relatively short archaeal genome is low and, thus, the structure and genomic location of such rPQSs may become a direct indication of their functionality. We have found that the majority of the genomes of Methanomicrobiaceae family of archaea contained multiple copies of the interspersed highly similar PQSs. Short oligonucleotides corresponding to the rPQS formed the G-quadruplex (G4) structure in presence of potassium ions as demonstrated by circular dichroism (CD) and enzymatic probing. However, further analysis of the genomic context for the rPQS revealed a 10–12 nt cytosine-rich track adjacent to 3'-end of each rPQS. Synthetic DNA fragments that included the C-rich track tended to fold into alternative structures such as hairpin structure and antiparallel triplex that were in equilibrium with G4 structure depending on the presence of potassium ions in solution. Structural properties of the found repetitive sequences, their location in the genomes of archaea, and possible functions are discussed.

Quantitative detection of human adenovirus from river water by monolithic adsorption filtration and quantitative PCR

Water contaminated with fecally derived viruses, also known as enteric viruses, represents a particularly high risk for human health. However, they have not been included in water quality regulations yet. The detection of these viruses is often more expensive and time-consuming compared to the analysis of conventional fecal indicator organisms. In addition, most methods are not sensitive enough to detect small viral loads that may already cause serious health issues if present in water. In this study, we established a workflow for the successful and direct enrichment of human adenovirus (HAdV) from artificially contaminated river water based on monolithic adsorption filtration (MAF) and quantitative polymerase reaction (qPCR). With a clear focus on efficiency, we used targeted synthetic DNA fragments as standard for the quantification of HAdV by qPCR, leading to accurate and robust results with a qPCR efficiency of 95 %, a broad working range over 6 orders of magnitude and an LOD of 1 GU/μL. We carried out a cascade of spiking experiments, enhancing the complexity of the spiking matrix with each step to progressively evaluate MAF for the direct concentration of HAdV. We found that negatively charged MAF using monoliths with hydroxyl groups (MAF−OH) showed a better reproducibility and a significantly faster turnaround time than skimmed milk flocculation (SMF) when concentrating HAdV35 from artificially contaminated, acidified mineral water. We then validated positively charged MAF using monoliths with diethyl aminoethyl groups (MAF-DEAE) for the direct concentration of HAdV5 without pre-conditioning of water samples using tap water as spiking matrix with a less defined and controlled water chemistry. Finally, we evaluated MAF-DEAE for the direct concentration of HAdV5 from surface water using river water as representative matrix with an undefined water chemistry. We found, that MAF-DEAE achieved reproducible recoveries of HAdV5, independently of the spiked concentration level or sample volume. Furthermore, we showed, that MAF-DEAE drastically reduced the limit of detection (LOD) of HAdV5 by a factor of 115 from 6.0 ∙ 103 GU/mL before to 5.2 ∙ 101 GU/mL after MAF-DEAE. We identified that recoveries increased for smaller processing volumes with a peak at 0.5 L of 84.0 % and showed that recovery efficiency depends on sample volume and matrix type. The here presented workflow based on MAF-DEAE and qPCR offers an easy-to-implement and highly efficient alternative to existing approaches and allows for a fast detection of HAdV in water.

Rapid reconstruction of porcine reproductive and respiratory syndrome virus using synthetic DNA fragments

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most challenging infectious disease of pig populations causing devastating economic loss to swine industry. Reverse genetics allow to engineer modified viruses such attenuated strains for vaccine development. Some reverse genetic systems were described for PRRSVs but, due to genome complexity of PRRSVs, construction and modification of such systems remain laborious and time-consuming.In this study, we described a reverse genetics approach based on the “Infectious-Subgenomic Amplicons” (ISA) method to rescue infectious PRRSV particles. Permissive cells were transfected with 4 overlapping synthetic DNA fragments covering the entire genome of PRRSV which allowed the rapid reconstruction of the complete virus genome and the subsequent generation of infectious wild-type particles within days.The ISA method represent a rapid alternative of conventional reverse genetic systems. This method will help to generate genetically modified and attenuated strains for the development of sanitary countermeasures in the future.

A diagnostic LAMP assay for the destructive grapevine insect pest, phylloxera (Daktulosphaira vitifoliae)

Grape phylloxera (Daktulosphaira vitifoliae) is a destructive insect pest of grapevines that is highly invasive worldwide, despite strict biosecurity containment measures in place at farm and regional levels. Current phylloxera identification by visual inspection and laboratory-based molecular methods is time-consuming and costly. More rapid and cost-effective methods for identification of this pest would benefit industry, growers, and biosecurity services. Loop mediated isothermal amplification (LAMP) is a new portable technology available for rapid and accurate in-field molecular diagnostics. This study outlines the development of a new LAMP assay to enable the identification of phylloxera specimens. New LAMP primers were developed to specifically amplify phylloxera mitochondrial DNA (5′-COI), which we have shown is effective as a DNA barcode for identification of phylloxera, using LAMP technology. Positive LAMP reactions, containing phylloxera DNA, amplified in less than twelve minutes with an anneal derivative temperature of approximately 79 °C to 80 °C compared to a newly designed synthetic DNA (gBlock) fragment which had an anneal derivative temperature of 82 °C. No LAMP amplification was detected in any of the non-target species tested, i.e. no false-positive identification resulted for these species. We also successfully optimised a non-destructive DNA extraction procedure, HotSHOT “HS6”, for use in the field on phylloxera adults, nymphs and eggs, to retain physical specimens. DNA extracted using this method was also suitable for species and genotype molecular identification methods, such as DNA barcoding, qPCR and microsatellite genotyping. The new LAMP assay provides a novel visual molecular tool for accurate diagnostics of phylloxera in the laboratory and field.

Rapid reconstruction of SARS-CoV-2 using a synthetic genomics platform.

Reverse genetics has been an indispensable tool to gain insights into viral pathogenesis and vaccine development. The genomes of large RNA viruses, such as those from coronaviruses, are cumbersome to clone and manipulate in Escherichia coli owing to the size and occasional instability of the genome1-3. Therefore, an alternative rapid and robust reverse-genetics platform for RNA viruses would benefit the research community. Here we show the full functionality of a yeast-based synthetic genomics platform to genetically reconstruct diverse RNA viruses, including members of the Coronaviridae, Flaviviridae and Pneumoviridae families. Viral subgenomic fragments were generated using viral isolates, cloned viral DNA, clinical samples or synthetic DNA, and these fragments were then reassembled in one step in Saccharomyces cerevisiae using transformation-associated recombination cloning to maintain the genome as a yeast artificial chromosome. T7 RNA polymerase was then used to generate infectious RNA to rescue viable virus. Using this platform, we were able to engineer and generate chemically synthesized clones of the virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)4, which has caused the recent pandemic of coronavirus disease (COVID-19), in only a week after receipt of the synthetic DNA fragments. The technical advance that we describe here facilitates rapid responses to emerging viruses as it enables the real-time generation and functional characterization of evolving RNA virus variants during an outbreak.

Creating New β-Globin-Expressing Lentiviral Vectors by High-Resolution Mapping of Locus Control Region Enhancer Sequences

Hematopoietic stem cell gene therapy is a promising approach for treating disorders of the hematopoietic system. Identifying combinations of cis-regulatory elements that do not impede packaging or transduction efficiency when included in lentiviral vectors has proven challenging. In this study, we deploy LV-MPRA (lentiviral vector-based, massively parallel reporter assay), an approach that simultaneously analyzes thousands of synthetic DNA fragments in parallel to identify sequence-intrinsic and lineage-specific enhancer function at near-base-pair resolution. We demonstrate the power of LV-MPRA in elucidating the boundaries of previously unknown intrinsic enhancer sequences of the human β-globin locus control region. Our approach facilitated the rapid assembly of novel therapeutic βAS3-globin lentiviral vectors harboring strong lineage-specific recombinant control elements capable of correcting a mouse model of sickle cell disease. LV-MPRA can be used to map any genomic locus for enhancer activity and facilitates the rapid development of therapeutic vectors for treating disorders of the hematopoietic system or other specific tissues and cell types.

Synthetic Oligodeoxynucleotides in the Regulation of Leukotriene Synthesis in Human Neutrophils

Polymorphonuclear leukocytes (PMNLs, neutrophils) play a central role in the defense against microbial infections. In the immune response to bacterial and fungal infections neutrophils eliminate pathogens through phagocytosis. During phagocytosis neutrophils produce physiologically active compounds called leukotrienes. Neutrophil production of leukoriene B4 is responsible for a second wave of neutrophil recruitment during inflammation. In the activation of neutrophils, not only the bacteria themselves play a role, but also pathogen associated molecular patterns, in particular, bacterial DNA and its fragments. Neutrophil priming with bacterial products makes neutrophils more responsive to activating stimuli. Synthetic CpG‐oligodeoxynucleotides (CpG‐ODNs) mimic microbial DNA and are now widely used to study DNA‐mediated cellular events. In our study we compared the effects of synthetic oligodeoxynucleotides (ODNs) of different structure on leukotriene synthesis in neutrophils during Salmonella bacteria phagocytosis. We treated PMNLs with opsonized S. typhimurium at a ratio of bacteria:PMNLs in the range 20–25:1. Leukotrienes and other 5‐lipoxygenase products were detected after priming neutrophils by 30 min incubation with 1 μM ODN and further stimulation for 15 min with opsonized Salmonella bacteria. The neutrophil exposure to A‐class CpG‐ODN, with phosphodiester inner core, inhibited leukotriene synthesis in neutrophil interaction with bacteria Salmonella typhimurium. Sequences, containing the human telomeric (TTAGGG)n repeats, on the contrary, activated leukotriene synthesis. Effects of A‐class CpG‐ODNs were sensitive to inhibitors of endosomal acidification and probably induced intracellular signaling through binding to toll like receptor TLR9. Synthetic DNA fragments containing stimulating CpG motifs initiate TLR9 signals, which lead to activation of the transcription factor NF‐kB. In our assays NF‐kB inhibitor BAY11‐7082 abolished the effects of A‐class CpG ODNs and increased the effects of telomeric ODNs on leukotriene synthesis. The results of our study revealed that the signal to inhibition of leukotriene synthesis by A‐class CpG‐ODNs and to activation of leukotriene synthesis by telomeric ODNs may be due to interaction of both classes of ODNs with TLR9 on neutrophils.Ethics statement. The authors prepared neutrophils from the blood of healthy volunteers. Blood was collected via venous puncture, as approved by the Ministry of Public Health Service of the Russian Federation. Experimental and the subject consent procedures were approved by the Ethics Committee of the A. N. Belozersky Institute of Physico‐Chemical Biology, Moscow State University. Fully informed consent was obtained, and all investigations were conducted according to the principles laid down in the Declaration of Helsinki.Support or Funding InformationThis study was funded by a grant from the Russian Foundation for Basic Research (17‐04‐01491)

MESA: automated assessment of synthetic DNA fragments and simulation of DNA synthesis, storage, sequencing and PCR errors.

SummaryThe development of de novo DNA synthesis, polymerase chain reaction (PCR), DNA sequencing and molecular cloning gave researchers unprecedented control over DNA and DNA-mediated processes. To reduce the error probabilities of these techniques, DNA composition has to adhere to method-dependent restrictions. To comply with such restrictions, a synthetic DNA fragment is often adjusted manually or by using custom-made scripts. In this article, we present MESA (Mosla Error Simulator), a web application for the assessment of DNA fragments based on limitations of DNA synthesis, amplification, cloning, sequencing methods and biological restrictions of host organisms. Furthermore, MESA can be used to simulate errors during synthesis, PCR, storage and sequencing processes.Availability and implementationMESA is available at mesa.mosla.de, with the source code available at github.com/umr-ds/mesa_dna_sim.Contact dominik.heider@uni-marburg.de Supplementary information Supplementary data are available at Bioinformatics online.

Recapitulation of gametic DNA methylation and its post-fertilization maintenance with reassembled DNA elements at the mouse Igf2/H19 locus

BackgroundPaternal allele-specific DNA methylation of the H19 imprinting control region (ICR) regulates imprinted expression of the Igf2/H19 genes. The molecular mechanism by which differential methylation of the H19 ICR is established during gametogenesis and maintained after fertilization, however, is not fully understood. We previously showed that a 2.9-kb H19 ICR fragment in transgenic mice was differentially methylated only after fertilization, demonstrating that two separable events, gametic and post-fertilization methylation, occur at the H19 ICR. We then determined that CTCF/Sox-Oct motifs and the 478-bp sequence of the H19 ICR are essential for maintaining its maternal hypomethylation status and for acquisition of paternal methylation, respectively, during the post-fertilization period.ResultsUsing a series of 5′-truncated H19 ICR transgenes to dissect the 478-bp sequence, we identified a 118-bp region required for post-fertilization methylation activity. Deletion of the sequence from the paternal endogenous H19 ICR caused loss of methylation after fertilization, indicating that methylation activity of the sequence is required to protect endogenous H19 ICR from genome-wide reprogramming. We then reconstructed a synthetic DNA fragment in which the CTCF binding sites, Sox-Oct motifs, as well as the 118-bp sequence, were inserted into lambda DNA, and used it to replace the endogenous H19 ICR. The fragment was methylated during spermatogenesis; moreover, its allele-specific methylation status was faithfully maintained after fertilization, and imprinted expression of the both Igf2 and H19 genes was recapitulated.ConclusionsOur results identified a 118-bp region within the H19 ICR that is required for de novo DNA methylation of the paternally inherited H19 ICR during pre-implantation period. A lambda DNA-based artificial fragment that contains the 118-bp sequence, in addition to the previously identified cis elements, could fully replace the function of the H19 ICR in the mouse genome.

Gold@Silica Nanoparticles Functionalized with Oligonucleotides: A Prominent Tool for the Detection of the Methylated Reprimo Gene in Gastric Cancer by Dynamic Light Scattering.

Reprimo (RPRM) is a tumor suppressor gene involved in the development of gastric cancer. Hypermethylation of the RPRM promoter region has been found in tumor tissue and plasma samples from patients with gastric cancer. These findings suggest that circulating methylated DNA of RPRM could be a candidate for a noninvasive detection of gastric cancer. We designed a nanosystem based on the functionalization of silica coated gold nanoparticles with oligonucleotides that recognize a specific DNA fragment of the RPRM promoter region. The functionality of the oligonucleotide on the surface of the nanoparticle was confirmed by polymerase chain reaction (PCR). The nanoparticles were incubated with a synthetic DNA fragment of methylated DNA of RPRM and changes in the size distribution after hybridization were evaluated by dynamic light scattering (DLS). A difference in the size distribution of nanoparticles hybridized with genomic DNA from the KATO III gastric cancer cell line was observed when was compared with DNA from the GES-1 normal cell line. These results showed that this nanosystem may be a useful tool for the specific and sensitive detection of methylated DNA of RPRM in patients at risk of developing gastric cancer.

Rescue of Recombinant Zika Virus from a Bacterial Artificial Chromosome cDNA Clone.

The association of Zika virus (ZIKV) infection with neurological complications during the recent worldwide outbreak and the lack of approved vaccines and/or antivirals have underscored the urgent need to develop ZIKV reverse genetic systems to facilitate the study of ZIKV biology and the development of therapeutic and/or prophylactic approaches. However, like with other flaviviruses, the generation of ZIKV full-length infectious cDNA clones has been hampered due to the toxicity of viral sequences during its amplification in bacteria. To overcome this problem, we have developed a nontraditional approach based on the use of bacterial artificial chromosomes (BACs). Using this approach, the full-length cDNA copy of the ZIKV strain Rio Grande do Norte Natal (ZIKV-RGN) is generated from four synthetic DNA fragments and assembled into the single-copy pBeloBAC11 plasmid under the control of the human cytomegalovirus (CMV) immediate-early promoter. The assembled BAC cDNA clone is stable during propagation in bacteria, and infectious recombinant (r)ZIKV is recovered in Vero cells after transfection of the BAC cDNA clone. The protocol described here provides a powerful technique for the generation of infectious clones of flaviviruses, including ZIKV, and other positive-strand RNA viruses, particularly those with large genomes that have stability problems during bacterialpropagation.

Development of a robust, field-deployable loop-mediated isothermal amplification (LAMP) assay for specific detection of potato pathogen Dickeya dianthicola targeting a unique genomic region.

Destructive maceration, a wide host range, and longevity in non-plant substrates has established Dickeya dianthicola (blackleg of potato) as a significant threat to potato industries worldwide. To protect these businesses, a specific and sensitive point-of-care D. dianthicola detection tool is necessary. We have developed a loop-mediated isothermal amplification (LAMP) assay for specific, sensitive, and rapid detection of D. dianthicola, which can be streamlined for point-of-care use. The developed LAMP assay targets a unique gene, alcohol dehydrogenase, of D. dianthicola. Assay specificity was assessed using strains present in inclusivity (16 D. dianthicola strains) and exclusivity panels (56 closely related, potato pathogenic, and other bacterial strains). Amplification with strains of inclusivity panel occurred, and cross-reactivity with non-target DNA was not observed. The limit of detection (LOD) was 10 CFU/ml when dilutions were made before isolating the genomic DNA; however, LOD was determined as 1 pg using 10-fold serially diluted D. dianthicola genomic DNA. Similar LOD of 1 pg was observed when serially diluted target genomic DNA was mixed with host genomic DNA. LOD (1 pg) was also calculated with 10-fold serially diluted synthetic DNA fragments containing primer target sites. Naturally and artificially inoculated plant samples were used for field adaptability tests with the field-deployable Optigene Plant Material Lysis Kit and a heat block (65°C); the results were obtained within 20 minutes. Despite the lack of method precision, no false positives or false negatives were observed. Therefore, with prepared reactions and a steady heat source, this assay can be used for rapid point-of-care detection, which is imperative for quarantine, eradication, disease management, and border protection.

Ethylene Response of Plum ACC Synthase 1 (ACS1) Promoter is Mediated through the Binding Site of Abscisic Acid Insensitive 5 (ABI5).

The enzyme 1-amino-cyclopropane-1-carboxylic acid synthase (ACS) participates in the ethylene biosynthesis pathways and it is tightly regulated transcriptionally and post-translationally. Notwithstanding its major role in climacteric fruit ripening, the transcriptional regulation of ACS during ripening is not fully understood. We studied fruit ripening in two Japanese plum cultivars, the climacteric Santa Rosa (SR) and its non-climacteric bud sport mutant, Sweet Miriam (SM). As the two cultivars show considerable difference in ACS expression, they provide a good system for the study of the transcriptional regulation of the gene. To investigate the differential transcriptional regulation of ACS1 genes in the SR and SM, their promoter regions, which showed only minor sequence differences, were isolated and used to identify the binding of transcription factors interacting with specific ACS1 cis-acting elements. Three transcription factors (TFs), abscisic acid-insensitive 5 (ABI5), GLABRA 2 (GL2), and TCP2, showed specific binding to the ACS1 promoter. Synthetic DNA fragments containing multiple cis-acting elements of these TFs fused to β-glucuronidase (GUS), showed the ABI5 binding site mediated ethylene and abscisic acid (ABA) responses of the promoter. While TCP2 and GL2 showed constant and similar expression levels in SM and SR fruit during ripening, ABI5 expression in SM fruits was lower than in SR fruits during advanced fruit ripening states. Overall, the work demonstrates the complex transcriptional regulation of ACS1.

Antifibrotic Effect of Smad Decoy Oligodeoxynucleotide in a CCl₄-Induced Hepatic Fibrosis Animal Model.

Hepatic fibrosis is the wound-healing process of chronic hepatic disease that leads to the end-stage of hepatocellular carcinoma and demolition of hepatic structures. Epithelial–mesenchymal transition (EMT) has been identified to phenotypic conversion of the epithelium to mesenchymal phenotype that occurred during fibrosis. Smad decoy oligodeoxynucleotide (ODN) is a synthetic DNA fragment containing a complementary sequence of Smad transcription factor. Thus, this study evaluated the antifibrotic effects of Smad decoy ODN on carbon tetrachloride (CCl4)-induced hepatic fibrosis in mice. As shown in histological results, CCl4 treatment triggered hepatic fibrosis and increased Smad expression. On the contrary, Smad decoy ODN administration suppressed fibrogenesis and EMT process. The expression of Smad signaling and EMT-associated protein was markedly decreased in Smad decoy ODN-treated mice compared with CCl4-injured mice. In conclusion, these data indicate the practicability of Smad decoy ODN administration for preventing hepatic fibrosis and EMT processes.