Molecular Biology


Protocols in Current Issue
Protocols in Past Issues
0 Q&A 120 Views Jan 5, 2023

Advances in imaging technology offer new opportunities in developmental biology. To observe the development of internal structures, microtome cross-sectioning followed by H&E staining on glass slides is a common procedure; however, this technique can be destructive, and artifacts can be introduced during the process. In this protocol, we describe a less invasive procedure with which we can stain insect samples and obtain reconstructed three-dimensional images using micro-computed tomography, or micro-CT (µCT). Specifically, we utilize the fungus-farming ambrosia beetle species Euwallacea validus to observe the morphology of mycangia, a critical internal organ with which beetles transport fungal symbionts. Not only this protocol is ideal to observe mycangia, our staining/scanning procedure can also be applied to observe other delicate tissues and small organs in arthropods.


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0 Q&A 324 Views Dec 20, 2022

MicroRNAs (miRNA) are small (21–24 nt) non-coding RNAs involved in many biological processes in both plants and animals. The biogenesis of plant miRNAs starts with the transcription of MIRNA (MIR) genes by RNA polymerase II; then, the primary miRNA transcripts are cleaved by Dicer-like proteins into mature miRNAs, which are then loaded into Argonaute (AGO) proteins to form the effector complex, the miRNA-induced silencing complex (miRISC). In Arabidopsis , some MIR genes are expressed in a tissue-specific manner; however, the spatial patterns of MIR gene expression may not be the same as the spatial distribution of miRISCs due to the non-cell autonomous nature of some miRNAs, making it challenging to characterize the spatial profiles of miRNAs. A previous study utilized protoplasting of green fluorescent protein (GFP) marker transgenic lines followed by fluorescence-activated cell sorting (FACS) to isolate cell-type-specific small RNAs. However, the invasiveness of this approach during the protoplasting and cell sorting may stimulate the expression of stress-related miRNAs. To non-invasively profile cell-type-specific miRNAs, we generated transgenic lines in which root cell layer-specific promoters drive the expression of AGO1 and performed immunoprecipitation to non-invasively isolate cell-layer-specific miRISCs. In this protocol, we provide a detailed description of immunoprecipitation of root cell layer-specific GFP-AGO1 using EN7::GFP-AGO1 and ACL5::GFP-AGO1 transgenic plants, followed by small RNA sequencing to profile single-cell-type-specific miRNAs. This protocol is also suitable to profile cell-type-specific miRISCs in other tissues or organs in plants, such as flowers or leaves.


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0 Q&A 1158 Views Dec 5, 2022

RNA is a vital component of the cell and is involved in a diverse range of cellular processes through a variety of functions. However, many of these functions cannot be performed without interactions with proteins. There are currently several techniques used to study protein–RNA interactions, such as electrophoretic mobility shift assay, fluorescence anisotropy, and filter binding. RNA-pulldown is a technique that uses biotinylated RNA probes to capture protein–RNA complexes of interest. First, the RNA probe and a recombinant protein are incubated to allow the in vitro interaction to occur. The fraction of bound protein is then captured by a biotin pull-down using streptavidin-agarose beads, followed by elution and immunoblotting for the recombinant protein with a His-tag–reactive probe. Overall, this method does not require specialized equipment outside what is typically found in a modern molecular laboratory and easily facilitates the maintenance of an RNase-free environment.


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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 826 Views Oct 5, 2022
The quantification of plant hormones and related gene expression is essential to improve the understanding of the molecular regulation of plant growth and development. However, plant hormone quantification is still challenging due to extremely low endogenous levels and high chemical diversity. In this study, we present a convenient extraction protocol that enables the simultaneous extraction of both phytohormones and RNA from the same sample in a small quantity (approximately 10 mg). Using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC–MS/MS), this protocol provides a method to quantify 13 phytohormones and their derivatives from four classes (cytokinin, auxin, abscisic acid, and gibberellin) at the speed of 14 min per sample.

0 Q&A 1401 Views Aug 20, 2022

RNA granules are conserved, non-membranous, biphasic structures predominantly composed of RNA and RNA-binding proteins. RNA granules often assemble as a result of cellular responses to a variety of stresses, including infection. Two types of RNA granules are best characterized: stress granules (SGs) and processing bodies (P-bodies). The mechanism of RNA granule assembly and disassembly is still understudied because of its complex composition and dynamic behavior. The assembly of RNA granules is driven by a process known as phase separation of granule components. Edc3 is a conserved decapping activator and an essential P-body component in Saccharomyces cerevisiae. Phase separation of P-body proteins has been poorly explored. This protocol will enable the visualization of the phase transition behavior of Edc3, since it is tagged to mCherry. It further describes using small molecules and other proteins to study P-body dynamics. In addition to the assembly of Edc3, this assay also lays the foundation to study disassembly of phase-separated assemblies in vitro, which was not explored earlier. We have devised the assay to describe the use of one such protein that acts as a disassembly factor. Overall, this protocol is simple to perform and can potentially be combined with analyzing these assemblies using other approaches.

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0 Q&A 1403 Views Jul 20, 2022

Cilia and flagella are microtubule-based hair-like organelles protruding from the surface of most eukaryotic cells, and play essential roles in cell locomotion, left-right asymmetry, embryo development, and tissue homeostasis. With isolated cilia and flagella, great progress has been made in understanding the composition, structure, and function of cilia. However, the current cilia/flagella isolation methods are deficient in the integrity or productivity of purified cilia when applied to mammalian motile cilia. Here, we describe a new protocol that isolates cilia shafts from mouse ependymal cells, by horizontal shear force and mild detergent. This method enables the production of virtually integral cilia with high yields and less cell body contamination. It is suitable for immunostaining, puromycin labeling assay, and proximity ligation assay of mammalian motile cilia.


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1 Q&A 1614 Views May 20, 2022

Kinetoplastids are unicellular eukaryotic parasites responsible for human pathologies such as Chagas disease, sleeping sickness or Leishmaniasis, caused by Trypanosoma cruzi, Trypanosoma brucei, and various Leishmania spp., respectively. They harbor a single large mitochondrion that is essential for the survival of the parasite. Interestingly, most of the mitochondrial gene expression machineries and processes present significant differences from their nuclear and cytosolic counterparts. A striking example concerns their mitochondrial ribosomes, in charge of translating the few essential mRNAs encoded by mitochondrial genomes. Here, we present a detailed protocol including the specific procedures to isolate mitochondria from two species of kinetoplastids, T. cruzi and L. tarentolae, by differential centrifugations. Then, we detail the protocol to purify mitochondrial ribosomal complexes from these two species of parasites (including ribosomal maturating complexes) by a sucrose gradient approach. Finally, we describe how to prepare cryo-electron microscopy (cryo-EM) grids from these two sorts of samples. This protocol will be useful for further studies aiming at analyzing mitochondrial translation regulation.

1 Q&A 1822 Views Apr 20, 2022

Due to overlapping sequences with linear cognates, identifying internal sequences of circular RNA (circRNA) remains a challenge. Recently, we have developed a full-length circRNA sequencing method (circFL-seq) and computational pipeline, to profile ordinary and fusion circRNA at the isoform level. Compared to short-read RNA-seq, rolling circular reverse transcription and nanopore long-read sequencing of circFL-seq make circRNA reads more than tenfold enriched, and show advantages for identification of both short (<100 nt) and long (>2,000 nt) circRNA transcripts. circFL-seq allows identification of differential alternative splicing suggested wide application prospects for functional studies of internal sequences in circRNAs. In addition, the experimental protocol and computational pipeline of circFL-seq shows better sensitivity and precision for identification of back-splicing junctions than current long-read sequencing methods. Together, the accurate identification and quantification of full-length circRNAs makes circFL-seq a potential tool for large-scale screening of functional circRNAs.

0 Q&A 1265 Views Apr 20, 2022

In the Japanese rhinoceros beetle Trypoxylus dichotomus, various candidate genes required for a specific phenotype of interest are listed by next-generation sequencing analysis. Their functions were investigated using RNA interference (RNAi) method, the only gene function analysis tool for T. dichotomus developed so far. The summarized procedure for the RNAi method used for T. dichotomus is to synthesize double-stranded RNA (dsRNA), and inject it in larvae or pupae of T. dichotomus. Although some dedicated materials or equipment are generally required to inject dsRNA in insects, the advantage of the protocol described here is that it is possible to inject dsRNA in T. dichotomus with one syringe.




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