Manual Silica-Based DNA Extractions.

There are several silica-based extraction methods that utilize silica-packed columns or silica-coated paramagnetic resin and are suitable for the needs of forensic DNA analysis and/or human identification. These rely on the use of chaotropic salts to alter the affinity of DNA such that it binds strongly to silica. A variety of samples can be successfully processed with these procedures, including buccal swabs, dried or liquid blood, saliva, semen, and other typical forensic-type samples. This chapter will describe the manual extraction process for Promega's DNA™ IQ System, as well as Qiagen's QIAamp® DNA Blood Mini Kit, QIAamp® DNA Mini Kit, and QIAamp® DNA Investigator Kit.

Optimized Method for Mycobacteria DNA Extraction from Sputum for Isothermal Amplification.

OBJECTIVE: Sputum sample processing for mycobacterial DNA extraction are demanding process to be integrated into isothermal amplification techniques because they often require procedures with number of centrifugation steps and manual interventions. Here, we established simple use of robust mycobacterial DNA extraction protocol from sputum samples suitable for isothermal amplification technique. METHODS: The DNA extraction efficiency of each protocol was evaluated using Mycovacterium gordonae (M. gordonae) and M. bovis bacillus Calmette-Guerin (BCG) spiked sputum samples. Three mycobacteria lysis methods, sonication, and heating at two different conditions (heating at 100°C for 20 min and 65°C for 30 min) were evaluated. As spin column based was used for DNA purification step, the optimal DNA adsorption protocol was assessed. RESULTS: Of three mycobacteria lysis methods, the difference of cycle threshold (Ct) values between for M. gordonea and BCG ranged between 0.10 to 0.62 and was not considered as appreciable. The thermal lysis method at 65°C for 30 min was selected due to its easier applicability. For DNA adsorption protocol, one-step protocol of adding DNA adsorption solution containing 4.5 M gudanidinium thiocyanate (GuSCN) before thermal lysis and performing DNA purification using spin column showed achieved efficient DNA extraction. CONCLUSION: DNA extraction by thermal lysis at 65°C with GuSCN followed by spin column DNA purification is simple, relatively fast (less than 50 min) and robust protocol applicable for downstream isothermal amplification.

A high-throughput genome-wide RNAi screen identifies modifiers of survival motor neuron protein.

Spinal muscular atrophy (SMA) is a debilitating neurological disorder marked by degeneration of spinal motor neurons and muscle atrophy. SMA results from mutations in survival motor neuron 1 (SMN1), leading to deficiency of survival motor neuron (SMN) protein. Current therapies increase SMN protein and improve patient survival but have variable improvements in motor function, making it necessary to identify complementary strategies to further improve disease outcomes. Here, we perform a genome-wide RNAi screen using a luciferase-based activity reporter and identify genes involved in regulating SMN gene expression, RNA processing, and protein stability. We show that reduced expression of Transcription Export complex components increases SMN levels through the regulation of nuclear/cytoplasmic RNA transport. We also show that the E3 ligase, Neurl2, works cooperatively with Mib1 to ubiquitinate and promote SMN degradation. Together, our screen uncovers pathways through which SMN expression is regulated, potentially revealing additional strategies to treat SMA.

Effects of DNA preservation solution and DNA extraction methods on microbial community profiling of soil.

Microbial community profiling using high-throughput sequencing relies in part on the preservation of the DNA and the effectiveness of the DNA extraction method. This study aimed at understanding to what extent these parameters affect the profiling. We obtained samples treated with and without a preservation solution. Also, we compared DNA extraction kits from Qiagen and Zymo-Research. The types of samples were defined strains, both as single species and mixtures, as well as undefined indigenous microbial communities from soil. We show that the use of a preservation solution resulted in substantial changes in the 16S rRNA gene profiles either due to an overrepresentation of Gram-positive bacteria or to an underrepresentation of Gram-negative bacteria. In addition, 16S rRNA gene profiles were substantially different depending on the type of kit that was used for extraction. The kit from Zymo extracted DNA from different types of bacteria in roughly equal amounts. In contrast, the kit from Qiagen preferentially extracted DNA from Gram-negative bacteria while DNA from Gram-positive bacteria was extracted less effectively. These differences in kit performance strongly influenced the interpretation of our microbial ecology studies.

Galaxy HiCExplorer 3: a web server for reproducible Hi-C, capture Hi-C and single-cell Hi-C data analysis, quality control and visualization.

The Galaxy HiCExplorer provides a web service at https://hicexplorer.usegalaxy.eu. It enables the integrative analysis of chromosome conformation by providing tools and computational resources to pre-process, analyse and visualize Hi-C, Capture Hi-C (cHi-C) and single-cell Hi-C (scHi-C) data. Since the last publication, Galaxy HiCExplorer has been expanded considerably with new tools to facilitate the analysis of cHi-C and to provide an in-depth analysis of Hi-C data. Moreover, it supports the analysis of scHi-C data by offering a broad range of tools. With the help of the standard graphical user interface of Galaxy, presented workflows, extensive documentation and tutorials, novices as well as Hi-C experts are supported in their Hi-C data analysis with Galaxy HiCExplorer.

Strengthening Security for Gene Synthesis: Recommendations for Governance.

Since the inception of gene synthesis technologies, there have been concerns about possible misuse. Using gene synthesis, pathogens-particularly small viruses-may be assembled "from scratch" in the laboratory, evading the regulatory regimes many nations have in place to control unauthorized access to dangerous pathogens. Progress has been made to reduce these risks. In 2010, the US Department of Health and Human Services (HHS) published guidance for commercial gene synthesis providers that included sequence screening of the orders and customer screening. The industry-led International Gene Synthesis Consortium (IGSC) was formed in 2009 to share sequence and customer screening methods, and it now includes the major international gene synthesis providers among its members. Since the 2010 HHS Guidance was released, however, there have been changes in gene synthesis technologies and market conditions that have reduced the efficacy of these biosecurity protections, leading to questions about whether the 2010 HHS Guidance should be updated, what changes could make it more effective, and what other international governance efforts could be undertaken to reduce the risks of misuse of gene synthesis products. This article describes these conditions and recommends actions that governments should take to reduce these risks and engage other nations involved in gene synthesis research.

Intra- and inter-laboratory agreement of the FAM19A4/mir124-2 methylation test: Results from an international study.

BACKGROUND: HPV-based cervical screening detects women at an increased risk of cervical cancer and precancer. To differentiate among HPV-positive women those with (pre)cancer, triage testing is necessary. The detection of cancer-associated host-cell DNA methylation (FAM19A4 and hsa-mir124-2) in cervical samples has shown valuable as triage test. This multicenter study from 6 collaborating European laboratories and one reference laboratory was set out to determine the intra- and inter-laboratory agreement of FAM19A4/mir124-2 DNA methylation analysis utilizing the QIAsure Methylation Test. METHODS: Agreement analysis for the QIAsure Methylation Test was assessed on high-risk HPV-positive cervical specimens (n = 1680) both at the level of the assay and at the full workflow, including bisulfite conversion. RESULTS: Intra- and inter-laboratory assay agreement were 91.4% (534/584; 95% CI 88.9-93.5; κ = 0.82) and 92.5% (369/399; 95% CI 90.0-94.7; κ = 0.83), respectively. The inter-laboratory workflow (bisulfite conversion and assay combined) agreement was 90.0% (627/697; 95% CI 87.5%-92.0%; κ = 0.76). CONCLUSION: These data show that the QIAsure Methylation Test performs robust and reproducible in different laboratory contexts. These results support the use of the QIAsure Methylation Test for full molecular screening for cervical cancer, including primary HPV testing and triage testing by methylation analysis.

Urine RNA Processing in a Clinical Setting: Comparison of 3 Protocols.

OBJECTIVE: The objective of this study was to compare quantitative and qualitative RNA extraction results from clinical voided urine samples between 3 commercially available extraction protocols. METHODS: For phase 1, fresh voided urine samples from 10 female subjects were collected and processed in clinic and transported to the laboratory with cold packs. RNA was purified with 1 of 3 RNA extraction protocols: (1) TRI Reagent Protocol; (2) Absolutely RNA Nanoprep Kit; and (3) ZR Urine RNA Isolation Kit. Real-time polymerase chain reactions (RT-PCR) were performed. As the ZR Urine RNA Isolation Kit provided the highest quality RNA in phase 1, for phase 2, RNA was extracted from 9 additional voided urine specimens using this kit to perform additional qualitative analyses. RESULTS: Median RNA yield was significantly higher with the TRI Reagent Protocol as compared with the other protocols (P = 0.007). However, there was a significantly lower median threshold cycle value from polymerase chain reaction (indicating improved downstream application performance) with the ZR Urine RNA Isolation Kit as compared with the other methods (P = 0.005). In phase 2, the median RNA integrity number of urine RNA was 2.5 (range, 1.6-5.9). CONCLUSIONS: Although other methods may provide a higher quantity of RNA, when using clinical urine samples, the ZR Urine RNA Isolation Kit provided the highest quality of extracted RNA. This kit is especially attractive for the clinical setting because it does not require an initial centrifugation step. The urine RNA obtained with this kit may be useful for polymerase chain reaction but is not likely to be of high enough integrity for RNA sequencing.

Comparing Two Common DNA Extraction Kits for the Characterization of Symbiotic Microbial Communities from Ascidian Tissue.

Various DNA extraction methods are often used interchangeably for the characterization of microbial communities despite indications that different techniques produce disparate results. The microbiomes of two ascidian species were herein characterized using two common DNA extraction kits, the DNeasy Blood and Tissue Kit (Qiagen) and the PowerSoil DNA Isolation Kit (Mo Bio Laboratories), followed by next-generation (Illumina) sequencing of partial 16S rRNA genes. Significant differences were detected in microbial community diversity and structure between ascidian species, but not between kits, suggesting similar recovery of biological variation and low technical variation between the two extraction methods for ascidian microbiome characterization.

Extracellular DNA in natural environments: features, relevance and applications.

Extracellular DNA (exDNA) is abundant in many habitats, including soil, sediments, oceans and freshwater as well as the intercellular milieu of metazoa. For a long time, its origin has been assumed to be mainly lysed cells. Nowadays, research is collecting evidence that exDNA is often secreted actively and is used to perform a number of tasks, thereby offering an attractive target or tool for biotechnological, medical, environmental and general microbiological applications. The present review gives an overview on the main research areas dealing with exDNA, depicts its inherent origins and functions and deduces the potential of existing and emerging exDNA-based applications. Furthermore, it provides an overview on existing extraction methods and indicates common pitfalls that should be avoided whilst working with exDNA.

Pharmacological versus genetic inhibition of heme oxygenase-1 - the comparison of metalloporphyrins, shRNA and CRISPR/Cas9 system.

Inhibition of heme oxygenase-1 (HO-1, encoded by HMOX1), a cytoprotective, anti-apoptotic and anti-inflammatory enzyme, may serve as a valuable therapy in various pathophysiological processes, including tumorigenesis. We compared the effect of chemical inhibitors - metalloporphyrins, with genetic tools - shRNA and CRISPR/Cas9 systems, to knock-down (KD)/knock-out (KO) HO-1 expression/activity. 293T cells were incubated with metalloporphyrins, tin and zinc protoporphyrins (SnPPIX and ZnPPIX, respectively) or were either transduced with lentiviral vectors encoding different shRNA sequences against HO-1 or were modified by CRISPR/Cas9 system targeting HMOX1. Metalloporphyrins decreased HO activity but concomitantly strongly induced HO-1 mRNA and protein in 293T cells. On the other hand, only slight basal HO-1 inhibition in shRNA KD 293T cell lines was confirmed on mRNA and protein level with no significant effect on enzyme activity. Nevertheless, silencing effect was much stronger when CRISPR/Cas9-mediated knock-out was performed. Most of the clones harboring mutations within HMOX1 locus did not express HO-1 protein and failed to increase bilirubin concentration after hemin stimulation. Furthermore, CRISPR/Cas9-mediated HO-1 depletion decreased 293T viability, growth, clonogenic potential and increased sensitivity to H2O2 treatment. In summary, we have shown that not all technologies can be used for inhibition of HO activity in vitro with the same efficiency. In our hands, the most potent and comprehensible results can be obtained using genetic tools, especially CRISPR/Cas9 approach.

Determination of the Selection Capacity of Antibiotics for Gene Selection.

Choosing a potent selection antibiotic (SA), is a crucial success factor when creating stably transfected cell lines using an antibiotic selection marker. The selection capacity of this antibiotic is defined as its ability to kill sensitive, untransfected parental cells, while leaving resistant, transfected cells unharmed. Currently, no procedure has been described to determine this selection capacity. Therefore, a protocol to obtain a numerical value, called the "selectivity factor" (SF), that defines the selection capacity of SAs is developed. The SF is determined by using a modified MTT (3-(4,5-dimethylthiazol-2-yl)-diphenyltetrazolium bromide) assay for both sensitive and resistant cells, and applies to commonly used cell lines. To prove the concept, the SF of the SA G418 and hygromycin B (HmB) on several cell lines is determined. The SF of G418 on BHK-21 cells is very high, indicating that G418 is an ideal SA for transfected BHK-21 cells. For HeLa cells, the SF of G418 is very low suggesting G418 is not an optimal SA for selecting transfected HeLa cells. For these cells, HmB would be a better choice. These conclusions are confirmed by an independent cell death assay. The SF identifies the most optimal SA for a certain cell line, reduces the risk of selecting spontaneously resistant cell clones, and streamlines the process of generating stable cell lines. Most importantly, the method is especially time saving when obtaining stable cell lines expressing toxic genes, and reduces culture times for generating large numbers of cell lines from the same parental cell line.

Comparative evaluation of DNA extraction methods for amplification by qPCR of superficial vs intracellular DNA from Bacillus spores.

This study was designed to assess the efficiency of eight extraction methods regarding their ability to release superficial (exogenous) and intracellular (endogenous) DNA from B. cereus spores for subsequent analysis by quantitative PCR (qPCR). B. cereus spore suspensions were subjected to both commercial DNA extraction kits and mechanical DNA extraction methods. The spores were observed by transmission electron microscopy to evaluate any damage caused during extraction. The efficiency of both extraction and purification were assessed using a qPCR assay targeting the bclA gene. Most of the extraction methods assessed, except the passage through the French press or the use of the QIAamp DNA Blood Mini kit without 95°C treatment, allowed the amplification of significant amounts of DNA. By using propidium monoazide, which is a photoreactive DNA-binding dye, the presence of non-negligible amounts of amplifiable DNA at the spore surface was highlighted. A further set of extraction assays was then performed on spores previously treated with PMA. The results of this study show that both superficial and intracellular spore DNA can be released by extraction methods to a greater or lesser extent and then further amplified by qPCR. The Precellys extraction allowed the detection of both intracellular and superficial DNA, the DNeasy Blood & Tissue kit the specific detection of intracellular DNA, while the Instagene kit detected only superficial DNA. Of the methods tested in this study, the Precellys extraction was the most efficient in terms of further DNA detection. SIGNIFICANCE AND IMPACT OF THE STUDY: In order to verify the presence or absence of B. cereus spores in food or on surfaces in the food environment, the use of an efficient extraction method is required, followed by a qPCR analysis on the DNA released. Conversely, in order to quantify the population of Bacillus spores, any superficial DNA must be blocked, e.g. with PMA, prior to intracellular DNA extraction and further amplification.

Discusión ética y legal del asesoramiento genético en paciente portadora de una variación patológica en RAD51D / Ethical and legal discussion on genetic counselling in a carrier of a deleterious variation in RAD51D

En el campo de la genética del cáncer, los avances en innovación tecnológica han ayudado a detectar variaciones patogénicas con baja prevalencia en la población en genes que todavía están en investigación, lo que significa que todavía hay poca evidencia científica disponible sobre el riesgo que estas variaciones podrían conllevar en cuanto a la susceptibilidad de desarrollar cáncer. La difícil tarea de asesorar genéticamente e informar del seguimiento, detección precoz y acciones profilácticas de estos casos, como el aquí expuesto, conlleva importantes implicaciones desde el punto de vista ético y legal sobre las que hay muy poco descrito en la literatura (AU)

In the field of the genetics of the cancer, advances in technological innovation have helped to detect low prevalence deleterious variation in genes within the population that still are under investigation. This means that little scientific evidence is available concerning the risk that these variations might constitute as regards the susceptibility of developing cancer. The difficult task of genetically assessing and reporting on the early detection, the prophylactic actions, and follow-up of these cases, as detailed herein, has important implications from an ethical and legal point of view, but hardly anything about them has been discussed in the literature (AU)

Soil DNA Extraction Procedure Influences Protist 18S rRNA Gene Community Profiling Outcome.

Advances in sequencing technologies allow deeper studies of the soil protist diversity and function. However, little attention has been given to the impact of the chosen soil DNA extraction procedure to the overall results. We examined the effect of three acknowledged DNA recovery methods, two manual methods (ISOm-11063, GnS-GII) and one commercial kit (MoBio), on soil protist community structures obtained from different sites with different land uses. Results from 18S rRNA gene amplicon sequencing suggest that DNA extraction method significantly affect the replicate homogeneity, the total number of operational taxonomic units (OTUs) recovered and the overall taxonomic structure and diversity of soil protist communities. However, DNA extraction effects did not overwhelm the natural variation among samples, as the community data still strongly grouped by geographical location. The commercial DNA extraction kit was associated with the highest diversity estimates and with a corresponding higher retrieval of Excavata, Cercozoa and Amoebozoa-related taxa. Overall, our findings indicate that this extraction offers a compromise between rare and dominant taxa representation, while providing high replication reproducibility. A comprehensive understanding of the DNA extraction techniques impact on soil protist diversity can enable more accurate diversity assays.

Evaluation and Identification of Marek's Disease Virus BAC Clones as Standardized Reagents for Research.

Marek's disease virus (MDV) is an alphaherpesvirus that causes Marek's disease (MD), a lymphoproliferative disease in chickens. Understanding of MDV gene function advanced significantly following the cloning of the MDV genome as either a series of overlapping cosmids or as a bacterial artificial chromosome (BAC), both of which could produce viable MDV. The objectives of this study were to compare multiple virulent MDV BAC clones using the Avian Disease and Oncology Laboratory's pathotyping assay, and to demonstrate the use of these clones as standardized reagents for a modified pathotyping assay by other laboratories. To date, MDV BAC clones have been produced for at least 10 MDV strains from all three serotypes including several virulent serotype 1 strains. We determined that MDV BAC clones exist for each virulent pathotype, despite the fact that these clones are not always equal in virulence to their corresponding parental strains. One clone from each pathotype was further evaluated in commercial specific-pathogen-free (SPF) chickens and found suitable for use in assays such as best-fit pathotyping, although results were variable based on the source of the SPF birds. The benefits of using BAC clones, which include easy shipping, ability to more easily manipulate, and long-term ability to use at a low passage level, are likely to result in the use of BAC clones as standard reagents for MD research. The use of the defined set of clones should allow side-by-side comparison, allowing researchers to better interpret results produced in different laboratories using different MDV field strains. Furthermore, a modified best-fit pathotyping assay has been proposed using these clones and reduced bird numbers.

What have single-molecule studies taught us about gene expression?

The production of a single mRNA is the result of many sequential steps, from docking of transcription factors to polymerase initiation, elongation, splicing, and, finally, termination. Much of our knowledge about the fundamentals of RNA synthesis and processing come from ensemble in vitro biochemical measurements. Single-molecule approaches are very much in this same reductionist tradition but offer exquisite sensitivity in space and time along with the ability to observe heterogeneous behavior and actually manipulate macromolecules. These techniques can also be applied in vivo, allowing one to address questions in living cells that were previously restricted to reconstituted systems. In this review, we examine the unique insights that single-molecule techniques have yielded on the mechanisms of gene expression.

Unbiased identification of signal-activated transcription factors by barcoded synthetic tandem repeat promoter screening (BC-STAR-PROM).

The discovery of transcription factors (TFs) controlling pathways in health and disease is of paramount interest. We designed a widely applicable method, dubbed barcorded synthetic tandem repeat promoter screening (BC-STAR-PROM), to identify signal-activated TFs without any a priori knowledge about their properties. The BC-STAR-PROM library consists of ∼3000 luciferase expression vectors, each harboring a promoter (composed of six tandem repeats of synthetic random DNA) and an associated barcode of 20 base pairs (bp) within the 3' untranslated mRNA region. Together, the promoter sequences encompass >400,000 bp of random DNA, a sequence complexity sufficient to capture most TFs. Cells transfected with the library are exposed to a signal, and the mRNAs that it encodes are counted by next-generation sequencing of the barcodes. This allows the simultaneous activity tracking of each of the ∼3000 synthetic promoters in a single experiment. Here we establish proof of concept for BC-STAR-PROM by applying it to the identification of TFs induced by drugs affecting actin and tubulin cytoskeleton dynamics. BC-STAR-PROM revealed that serum response factor (SRF) is the only immediate early TF induced by both actin polymerization and microtubule depolymerization. Such changes in cytoskeleton dynamics are known to occur during the cell division cycle, and real-time bioluminescence microscopy indeed revealed cell-autonomous SRF-myocardin-related TF (MRTF) activity bouts in proliferating cells.

Habilidades y competencias en genética clínica para el médico de familia español / Skills and competencies in clinical genetics for Spanish family doctor

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