Molecular Biology

Protocols in Current Issue
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0 Q&A 390 Views Dec 5, 2022

N6-methyladenosine (m6A) is the most prevalent internal modification of eukaryotic messenger RNAs (mRNAs), affecting their fold, stability, degradation, and cellular interaction(s) and implicating them in processes such as splicing, translation, export, and decay. The m6A modification is also extensively present in non-coding RNAs, including microRNAs (miRNAs), ribosomal RNAs (rRNAs), and transfer RNAs (tRNAs). Common m6A methylation detection techniques play an important role in understanding the biological function and potential mechanism of m6A, mainly including the quantification and specific localization of m6A modification sites. Here, we describe in detail the dot blotting method for detecting m6A levels in RNA (mRNA as an example), including total RNA extraction, mRNA purification, dot blotting, and data analysis. This protocol can also be used to enrich specific RNAs (such as tRNA, rRNA, or miRNA) by isolation technology to detect the m6A level of single RNA species, so as to facilitate further studies of the role of m6A in biological processes.

0 Q&A 1264 Views Mar 5, 2022

The impact of viral diseases on human health is becoming increasingly prevalent globally with the burden of disease being shared between resource-rich and poor areas. As seen in the global pandemic caused by SARS-CoV-2, there is a need to establish viral detection techniques applicable to resource-limited areas that provide sensitive and specific testing with a logistically conscious mindset. Herein, we describe a direct-to-PCR technology utilizing mechanical homogenization prior to viral PCR detection, which allows the user to bypass traditional RNA extraction techniques for accurate detection of human coronavirus. This methodology was validated in vitro, utilizing human coronavirus 229E (HCoV-229E), and then clinically, utilizing patient samples to test for SARS-CoV-2 infection. In this manuscript, we describe in detail the protocol utilized to determine the limit of detection for this methodology with in vitro testing of HCoV-229E.

0 Q&A 1869 Views Jan 20, 2022

The Drosophila larval haematopoietic organ or lymph gland consists of multiple cell types arranged in zones. The smallest stem cell compartment consists of 40-45 cells that constitute the haematopoietic niche. In order to analyse the haematopoietic niche, it needs to be labelled with a specific antibody to differentiate it from the other cell types. To characterise a phenotype, it is often necessary to investigate the expression of a gene in a particular stem cell compartment within the lymph gland. In such a situation, in-situ hybridization is performed, as it indicates the localization of gene expression. Although chromogenic in-situ hybridization enables us to compare the signal and tissue morphology simultaneously, it fails to harness the information related to the degree of gene expression. Dual immunofluorescence and in-situ hybridization (IF-FISH) serves as the powerful technique that helps to visualize both protein and mRNA expression within the same cell type. This technique also provides reliable quantification regarding mRNA expression levels. When dealing with a few cells within the organ, like the niche of the larval lymph gland, fluorescently labelled riboprobes allows us to localize and assess the magnitude of gene expression within the niche cells, which are also immunolabelled with a niche-specific marker, to distinguish them from the adjoining cell types.

0 Q&A 1665 Views Nov 20, 2021

Regionalized distribution of genes plays crucial roles in the formation of the spatial pattern in tissues and embryos during development. In situ hybridization has been one of the most widely used methods to screen, identify, and validate the spatial distribution of genes in tissues and embryos, due to its relative simplicity and low cost. However, acquisition of high-quality hybridization signals remains a challenge while maintaining good tissue morphology, especially for small tissues such as early post-implantation mouse embryos. In this protocol, we present a detailed RNA in situ hybridization protocol suitable for wholemount early post-implantation mouse embryos and other small tissue samples. This protocol uses digoxigenin (DIG) labeled riboprobes to hybridize with target transcripts, alkaline phosphatase-conjugated anti-DIG antibodies to recognize DIG-labeled nucleotides, and nitroblue tetrazolium (NBT)/5-bromo-4-chloro-3-indolyl-phosphate (BCIP) chromogenic substrates for color development. Specific steps and notes on riboprobe preparation, embryo collection, probe hybridization, and color development are all included in the following protocol.

Graphic abstract:

Overview of Wholemount in situ Hybridization in Early Mouse Embryos.

0 Q&A 2504 Views Sep 20, 2021

Genome-wide sequencing of RNA (RNA-seq) has become an inexpensive tool to gain key insights into cellular and disease mechanisms. Sample preparation and sequencing are streamlined and allow the acquisition of hundreds of gene expression profiles in a few days; however, in particular, data processing, curation, and analysis involve numerous steps that can be overwhelming to non-experts. Here, the sample preparation, sequencing, and data processing workflow for RNA-seq expression analysis in yeast is described. While this protocol covers only a small portion of the RNA-seq landscape, the principal workflow common to such experiments is described, allowing the reader to adapt the protocol where necessary.

Graphic abstract:

Basic workflow of RNA-seq expression analysis.

0 Q&A 1725 Views Sep 20, 2021

Cytidine-to-uridine (C-to-U) RNA editing is one of the most important post-transcriptional RNA processing in plant mitochondria and chloroplasts. Several techniques have been developed to detect the RNA editing efficiency in plant mitochondria and chloroplasts, such as poisoned primer extension (PPE) assays, high-resolution melting (HRM) analysis, and DNA sequencing. Here, we describe a method for the quantitative detection of RNA editing at specific sites by sequencing cDNA from plant leaves to further evaluate the effect of different treatments or plant mutants on the C to U RNA editing in mitochondria and chloroplasts.

0 Q&A 4703 Views Mar 20, 2021

During pandemics, such as the one caused by SARS-CoV-2 coronavirus, simple methods to rapidly test large numbers of people are needed. As a faster and less resource-demanding alternative to detect viral RNA by conventional qPCR, we used reverse transcription loop-mediated isothermal amplification (RT-LAMP). We previously established colorimetric RT-LAMP assays on both purified and unpurified SARS-CoV-2 clinical specimens and further developed a multiplexed sequencing protocol (LAMP-sequencing) to analyze the outcome of many RT-LAMP reactions at the same time (Dao Thi et al., 2020). Extending on this work, we hereby provide step-by-step protocols for both RT-LAMP assays and read-outs.

0 Q&A 3587 Views Feb 20, 2021

Exosomes and other extracellular vesicles (EVs) are considered the main vehicles transporting RNAs in extracellular samples, including human bodily fluids. However, a major proportion of extracellular RNAs (exRNAs) do not copurify with EVs and remain in ultracentrifugation supernatants of cell-conditioned medium or blood serum. We have observed that nonvesicular exRNA profiles are highly biased toward those RNAs with intrinsic resistance to extracellular ribonucleases. These highly resistant exRNAs are interesting from a biomarker point of view, but are not representative of the actual bulk of RNAs released to the extracellular space. In order to understand exRNA dynamics and capture both stable and unstable RNAs, we developed a method based on size-exclusion chromatography (SEC) fractionation of RNase inhibitor (RI)-treated cell-conditioned medium (RI-SEC-seq). This method has allowed us to identify and study extracellular ribosomes and tRNAs, and offers a dynamical view of the extracellular RNAome which can impact biomarker discovery in the near future.

Graphical abstract:

Overview of the RI-SEC-seq protocol: sequencing of size-exclusion chromatography fractions from nonvesicular extracellular samples treated or not with RNase inhibitors (+/- RI)

0 Q&A 4183 Views Nov 5, 2020
Standard diagnostic methods of Coronavirus Disease 2019 (COVID-19) rely on RT-qPCR technique which have limited point-of-care test (POCT) potential due to necessity of dedicated equipment and specialized personnel. LAMP, an isothermal nucleic acid amplification test (NAAT), is a promising technique that may substitute RT-qPCR for POCT of genomic materials. Here, we provide a protocol to perform reverse transcription LAMP targeting SARS-CoV-2. We adopted both real-time fluorescence detection and end-point colorimetric detection approaches. Our protocol would be useful for screening diagnosis of COVID-19 and be a baseline for development of improved POCT NAAT.
0 Q&A 3569 Views Oct 20, 2020
SARS-CoV-2 has quickly spread all around the globe causing illness and wide damages. Most countries were unprepared for such a rapid spread and crisis. This led to various strategies for effective control of the new pandemic. A key aspect in all countries was to effectively test the population for the virus. Most countries chose a lockdown strategy in which many workplaces and activities are completely closed, leading to substantial economy costs. Here, we present a protocol we recently developed that allows rapid and simple detection of SARS-CoV-2 for the large population, eliminating costs and involvement of professional teams and laboratories. This protocol is based on Reverse Transcribed Loop-Mediated Isothermal Amplification (RT-LAMP). We tested this protocol directly on patient samples, both nasal and throat clinical swabs as well as saliva. Notably, this protocol is simple, cheap and can be easily applied to other pathogens as well.

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