Rainer Melzer
  • Assistant Professor, University College Dublin
Research fields
  • Plant science
Using indCAPS to Detect CRISPR/Cas9 Induced Mutations
Authors:  Charles Hodgens, Zachary L. Nimchuk and Joseph J. Kieber, date: 09/20/2019, view: 3311, Q&A: 0
Cleaved amplified polymorphic sequences (CAPS) assays are useful tools for detecting small mutations such as single nucleotide polymorphisms (SNPs) or insertion/deletions (indels) present in an amplified DNA fragment. A mutation that disrupts or creates a restriction site will prevent cleavage by a restriction enzyme, allowing discrimination of wild-type and mutant alleles. In cases where no convenient restriction site is present, a derived Cleaved Amplified Polymorphic Sequence (dCAPS) assay can be used, where mismatches in the primer are used to create a diagnostic restriction site. No special design constraints are present for a CAPS assay, but cases where CAPS assays can be used are infrequent. A dCAPS assay can be burdensome to design by hand, but it is more broadly applicable. This protocol will describe the use of the indCAPS tool for the design of CAPS and dCAPS primers. The indCAPS tool was designed to be compatible with indel alleles, which prior tools struggled with but have increased importance since the rise of CRISPR/Cas9 mutagenesis methods.
Quantification of Serotonin in Rice and Insect Pest and its Functional Analysis in Insects Using Artificial Diet Feeding
Authors:  Long Wang, Xiaohao Guo, Wenqian Huang, Haiping Lu and Qing-yao Shu, date: 02/20/2019, view: 4232, Q&A: 0
Rice is one of the world’s most important crops, but its production suffers from insect pests. Rice brown planthopper (BPH; Nilaparvata lugens Stål) and striped stem borer (SSB, Chilo suppressalis Walker) are the two most serious pests in rice production. We reported that serotonin is an essential mediator in the interaction between rice and insect. Here, we established a method for extraction and determination of serotonin in rice and BPH.
Tethered Chromosome Conformation Capture Sequencing in Triticeae: A Valuable Tool for Genome Assembly
Authors:  Axel Himmelbach, Ines Walde, Martin Mascher and Nils Stein, date: 08/05/2018, view: 8189, Q&A: 0
Chromosome conformation capture sequencing (Hi-C) is a powerful method to comprehensively interrogate the three-dimensional positioning of chromatin in the nucleus. The development of Hi-C can be traced back to successive increases in the resolution and throughput of chromosome conformation capture (3C) (Dekker et al., 2002). The basic workflow of 3C consists of (i) fixation of intact chromatin, usually by formaldehyde, (ii) cutting the fixed chromatin with a restriction enzyme, (iii) religation of sticky ends under diluted conditions to favor ligations between cross-linked fragments or those between random fragments and (iv) quantifying the number of ligations events between pairs of genomic loci (de Wit and de Laat, 2012). In the original 3C protocol, ligation frequency was measured by amplification of selected ligation junctions corresponding to a small number of genomic loci (‘one versus one’) through semi-quantitative PCR (Dekker et al., 2002). The chromosome conformation capture-on-chip (4C) and chromosome conformation capture carbon copy (5C) technologies then extended 3C to count ligation events in a ‘one versus many’ or ‘many versus many’ manner, respectively. Hi-C (Lieberman-Aiden et al., 2009) finally combined 3C with next-generation sequencing (Metzker, 2010). Here, before religation sticky ends are filled in with biotin-labeled nucleotide analogs to enrich for fragments with a ligation junction in a later step. The Hi-C libraries are then subjected to high-throughput sequencing and the resultant reads mapped to a reference genome, allowing the determination of contact probabilities in a ‘many versus many’ way with a resolution that is limited only by the distribution of restriction sites and the read depth. The first application of Hi-C was the elucidation of global chromatin folding principles in the human genome (Lieberman-Aiden et al., 2009). Similar efforts have since been carried out in other eukaryotic model species such as yeast (Duan et al., 2010), Drosophila (Sexton et al., 2012) and Arabidopsis (Grob et al., 2014; Wang et al., 2015; Liu et al., 2016). Other uses of Hi-C include the study of chromatin looping at high-resolution (Rao et al., 2014; Liu et al., 2016), of chromatin reorganization along the cell cycle (Naumova et al., 2013) and of differences in chromatin organization in mutant individuals (Feng et al., 2014). The tethered conformation capture protocol (TCC) (Kalhor et al., 2011) described here is a variant of the original Hi-C method (Lieberman-Aiden et al., 2009) and was adapted to Triticeae.
High Resolution Melting Temperature Analysis to Identify CRISPR/Cas9 Mutants from Arabidopsis
Authors:  Cynthia Denbow, Sonia Carole Ehivet and Sakiko Okumoto, date: 07/20/2018, view: 7965, Q&A: 0
CRISPR/Cas9 made targeted mutagenesis and genome editing possible for many plant species. One of the ways that the endonuclease is used for plant genetics is the creation of loss-of-function mutants, which typically result from erroneous DNA repair through non-homologous end joining (NHEJ) pathway. The majority of erroneous repair events results in single-bp insertion or deletion. While single-bp insertions or deletions (indels) effectively destroy the function of protein-coding genes through frameshift, detection is difficult due to the small size shift. High-resolution melting temperature analysis allows quick detection, and it does not require any additional pipetting steps after the PCR amplification of the region of interest. In this protocol, we will describe the steps required for the analysis of potential homozygous mutants.
Construction of a Single Transcriptional Unit for Expression of Cas9 and Single-guide RNAs for Genome Editing in Plants
Authors:  Xu Tang, Zhaohui Zhong, Xuelian Zheng and Yong Zhang, date: 09/05/2017, view: 12524, Q&A: 0
The CRISPR (clustered regularly interspaced short palindromic repeats)-associated protein9 (Cas9) is a simple and efficient tool for genome editing in many organisms including plant and crop species. The sgRNAs of the CRISPR/Cas9 system are typically expressed from RNA polymerase III promoters, such as U6 and U3. In many transformation events, more nucleotides will increase the difficulties in plasmid construction and the risk of wrong integration in genome such as base-pair or fragment missing (Gheysen et al., 1990). And also, in many organisms, Pol III promoters have not been well characterized, and heterologous Pol III promoters often perform poorly (Sun et al., 2015). Thus, we have developed a method using single transcriptional unit (STU) CRISPR-Cas9 system to drive the expression of both Cas9 and sgRNAs from a single RNA polymerase II promoter to achieve effective genome editing in plants.
Comprehensive Methods for Leaf Geometric Morphometric Analyses
Authors:  Laura L. Klein and Harlan T. Svoboda, date: 05/05/2017, view: 14611, Q&A: 0
Leaf morphometrics are used frequently by several disciplines, including taxonomists, systematists, developmental biologists, morphologists, agronomists, and plant breeders to name just a few. Leaf shape is highly variable and can be used for identifying species or genotypes, developmental patterning within and among individuals, assessing plant health, and measuring environmental impacts on plant phenotype. Traditional leaf morphometrics requires hand tools and access to specimens, but modern efforts to digitize botanical collections make digital morphometrics a readily accessible and scientifically rigorous option. Here we provide detailed instructions for performing some of the most informative digital geometric morphometric analyses available: generalized Procrustes analysis, elliptical Fourier analysis, and shape features. This comprehensive procedure for leaf shape analysis is comprised of six main sections: A) scanning of material, B) acquiring landmarks, C) analysis of landmark data, D) isolating leaf outlines, E) analysis of leaf outlines, and F) shape features. This protocol provides a detailed reference for applying landmark and outline analysis to leaf shape as well as describing leaf shape features, thus empowering researchers to perform high throughput phenotyping for diverse applications.
Use of Geminivirus for Delivery of CRISPR/Cas9 Components to Tobacco by Agro-infiltration
Authors:  Kangquan Yin, Ting Han and Yule Liu, date: 04/05/2017, view: 14488, Q&A: 0
CRISPR/Cas9 system is a recently developed genome editing tool, and its power has been demonstrated in many organisms, including some plant species (Wang et al., 2016). In eukaryotes, the Cas9/gRNA complexes target genome sites specifically and cleave them to produce double-strand breaks (DSBs), which can be repaired by non-homologous end joining (NHEJ) pathway (Wang et al., 2016). Since NHEJ is error prone, mutations are thus generated. In plants, delivery of genome editing reagents is still challenging. In this protocol, we detail the procedure of a virus-based gRNA delivery system for CRISPR/Cas9 mediated plant genome editing (VIGE). This method offers a rapid and efficient way to deliver gRNA into plant cells, especially for those that are recalcitrant to transformation with Agrobacterium.
In Gel Kinase Assay
Authors:  Gaston A. Pizzio and Pedro L. Rodriguez, date: 03/05/2017, view: 14669, Q&A: 0
Proper spatiotemporal regulation of protein phosphorylation in cells and tissues is required for normal development and homeostasis. We present the protocol ‘In Gel Kinase Assay’, which is useful for protein kinase activity measurements from crude protein extracts. We have successfully used ‘In Gel Kinase Assay’ protocol to show that the Arabidopsis thaliana sextuple mutant in the PYRABACTIN RESISTANCE1/PYR1-LIKE/REGULATORY COMPONENTS OF ABA RECEPTORS (PYR/PYL/RCAR-ABA receptors; line pyr/pyl112458) is impaired in ABA-mediated activation of SnRK2.2, SnRK2.3 and OST1/SnRK2.6, as much as the triple mutant snrk2.2/2.3/2.6 (Gonzalez-Guzman et al., 2012).
Multiplexed GuideRNA-expression to Efficiently Mutagenize Multiple Loci in Arabidopsis by CRISPR-Cas9
Authors:  Julia Schumacher, Kerstin Kaufmann and Wenhao Yan, date: 03/05/2017, view: 11542, Q&A: 0
Since the discovery of the CRISPR (clustered regularly interspaced short palindromic repeats)-associated protein (Cas) as an efficient tool for genome editing in plants (Li et al., 2013; Shan et al., 2013; Nekrasov et al., 2013), a large variety of applications, such as gene knock-out, knock-in or transcriptional regulation, has been published. So far, the generation of multiple mutants in plants involved tedious crossing or mutagenesis followed by time-consuming screening of huge populations and the use of the Cas9-system appeared a promising method to overcome these issues. We designed a binary vector that combines both the coding sequence of the codon optimized Streptococcus pyogenes Cas9 nuclease under the control of the Arabidopsis thaliana UBIQUITIN10 (UBQ10)-promoter and guide RNA (gRNA) expression cassettes driven by the A. thaliana U6-promoter for efficient multiplex editing in Arabidopsis (Yan et al., 2016). Here, we describe a step-by-step protocol to cost-efficiently generate the binary vector containing multiple gRNAs and the Cas9 nuclease based on classic cloning procedure.
Production of Guide RNAs in vitro and in vivo for CRISPR Using Ribozymes and RNA Polymerase II Promoters
Authors:  Tao Zhang, Yangbin Gao, Rongchen Wang and Yunde Zhao, date: 02/20/2017, view: 16938, Q&A: 0
CRISPR/Cas9-mediated genome editing relies on a guide RNA (gRNA) molecule to generate sequence-specific DNA cleavage, which is a prerequisite for gene editing. Here we establish a method that enables production of gRNAs from any promoters, in any organisms, and in vitro (Gao and Zhao, 2014). This method also makes it feasible to conduct tissue/cell specific gene editing.
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