Harrie van Erp
  • Post-Doc, Rothamsted Research
Research fields
  • Plant science
Boron Uptake Assay in Xenopus laevis Oocytes
Authors:  Sheliang Wang, Namiki Mitani-Ueno and Junpei Takano, date: 03/05/2018, view: 7306, Q&A: 0
Boron (B) is essential for plant growth and taken up by plant roots as boric acid. Under B limitation, B uptake and translocation in plants are dependent on the boric acid channels located in the plasma membrane. Xenopus leavis oocyte is a reliable heterologous expression system to characterize transport activities of boric acid channels and related major intrinsic proteins (aquaporins). Here, we outline the protocols for expression of boric acid channels and boric acid uptake assay in Xenopus leavis oocytes.
Analysis of Xyloglucan Composition in Arabidopsis Leaves
Authors:  Javier Sampedro, Cristina Gianzo, Esteban Guitián, Gloria Revilla and Ignacio Zarra, date: 10/05/2017, view: 5581, Q&A: 0
Xyloglucan is one of the main components of the primary cell wall in most species of plants. This protocol describes a method to analyze the composition of the enzyme-accessible and enzyme-inaccessible fractions of xyloglucan in the model species Arabidopsis thaliana. It is based on digestion with an endoglucanase that attacks unsubstituted glucose residues in the backbone. The identities and relative amounts of released xyloglucan fragments are then determined using MALDI-TOF mass spectrometry.
Estimation of Stomatal Aperture in Arabidopsis thaliana Using Silicone Rubber Imprints
Authors:  Telma E. Scarpeci, María I. Zanor and Estela M. Valle, date: 06/20/2017, view: 12523, Q&A: 2
Estimation of stomatal aperture using low viscosity silicone-base impression material has the advantage of working with the whole leaf. The developmental stage and the environment strongly affect the stomatal aperture. Therefore, it is mandatory to have accurate estimations of the stomatal aperture of intact leaves under different situations. With this technique, it is possible to get the real picture at any moment. The outputs of the data include studies on cell area and morphology, epidermis cell and stomata lineages, among others. This protocol is useful for the accurate estimation of stomatal aperture in many samples of intact leaves in Arabidopsis thaliana.
In Gel Kinase Assay
Authors:  Gaston A. Pizzio and Pedro L. Rodriguez, date: 03/05/2017, view: 14617, 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).
Visualising Differential Growth of Arabidopsis Epidermal Pavement Cells Using Thin Plate Spline Analysis
Authors:  William Jonathan Armour, Deborah Anne Barton and Robyn Lynette Overall, date: 11/20/2016, view: 7766, Q&A: 0
Epidermal pavement cells in Arabidopsis leaves and cotyledons develop from relatively simple shapes to form complex cells that have multiple undulations of varying sizes. Analyzing the growth of individual parts of the cell wall boundaries over time is essential to understanding how pavement cells develop their complex shapes. Thin plate spline analysis is a method for visualizing the change of size and shape of objects through warping or deformation of a regular mesh and can be applied to understand cell wall growth. This protocol describes the application of thin plate spline analysis to visualize the development of individual pavement cells over time.
Quantification of the Mucilage Detachment from Arabidopsis Seeds
Author:  Cătălin Voiniciuc, date: 05/05/2016, view: 7658, Q&A: 0
The Arabidopsis thaliana seed coat produces large amounts of cell wall polysaccharides, which swell out of the epidermal cells upon hydration of the mature dry seeds. While most mucilage polymers immediately diffuse in the surrounding solution, the remaining fraction tightly adheres to the seed, forming a dense gel-like capsule (Macquet et al., 2007). Recent evidence suggests that the adherence of mucilage is mediated by complex interactions between several cell wall components (Griffiths et al., 2014; Voiniciuc et al., 2015a). Therefore, it is important to evaluate how different cell wall mutants impact this mucilage property. This protocol facilitates the analysis of monosaccharides in sequentially extracted mucilage fractions, and quantifies the detachment of each component from seeds.
Analysis of Monosaccharides in Total Mucilage Extractable from Arabidopsis Seeds
Authors:  Cătălin Voiniciuc and Markus Günl, date: 05/05/2016, view: 10054, Q&A: 0
The Arabidopsis thaliana seed coat epidermis produces copious amounts of mucilage polysaccharides (Haughn and Western, 2012). Characterization of mucilage mutants has identified novel genes required for cell wall biosynthesis and modification (North et al., 2014). The biochemical analysis of seed mucilage is essential to evaluate how different mutations affect cell wall structure (Voiniciuc et al., 2015c). Here we describe a robust method to screen the monosaccharide composition of Arabidopsis seed mucilage using ion chromatography (IC). Mucilage from up to 48 samples can be extracted and prepared for IC analysis within 24 h (only 4 h hands-on). Furthermore, this protocol enables fast separation (31 min per sample), automatic detection and quantification of both neutral and acidic sugars.
LC/MS-based Detection of Hydroxyproline O-galactosyltransferase Activity
Authors:  Mari Ogawa-Ohnishi and Yoshikatsu Matsubayashi, date: 01/20/2016, view: 7137, Q&A: 0
Arabinogalactan proteins (AGPs) are plant-specific extracellular glycoproteins regulating a variety of processes during growth and development. AGP biosynthesis involves O-galactosylation of hydroxyproline (Hyp) residues followed by a stepwise elongation of the complex sugar chains. The initial Hyp O-galactosylation is mediated by Hyp O-galactosyltransferase (HPGT) that catalyzes the transfer of a D-galactopyranosyl residue to the hydroxyl group of Hyp residues of peptides from the sugar donor UDP-α-D-galactose (Figure 1). Here we describe a LC/MS-based method for the detection of HPGT activity in vitro.


Figure 1. Reaction scheme for Hyp galactosylation by HPGT. HPGT catalyzes the addition of a D-galactopyranose from an UDP-α-D-Gal to the hydroxylgroup of Hyp residues.
Detection of Hydroxyproline O-galactoside by LC/MS
Authors:  Mari Ogawa-Ohnishi and Yoshikatsu Matsubayashi, date: 01/20/2016, view: 6321, Q&A: 0
Hydroxyproline (Hyp) O-galactosylation is a plant-specific post-translational modification found in extracellular glycoproteins such as arabinogalactan proteins (AGPs). Hyp O-galactosylation is mediated by Hyp O-galactosyltransferase (HPGT) that catalyzes the transfer of a D-galactopyranosyl residue to the hydroxyl group of Hyp residues of peptides from the sugar donor UDP-α-D-Gal. Here we describe an LC/MS-based method for the detection of Hyp O-galactoside.
Saccharification Protocol for Small-scale Lignocellulosic Biomass Samples to Test Processing of Cellulose into Glucose
Authors:  Rebecca Van Acker, Ruben Vanholme, Kathleen Piens and Wout Boerjan, date: 01/05/2016, view: 11302, Q&A: 0
Second generation biofuels are derived from inedible lignocellulosic biomass of food and non-food crops. Lignocellulosic biomass is mainly composed of cell walls that contain a large proportion of cellulosic and hemicellulosic polysaccharides. An interesting route to generate biofuels and bio-based materials is via enzymatic hydrolysis of cell wall polysaccharides into fermentable sugars, a process called saccharification. The released sugars can then be fermented to fuels, e.g., by use of yeast.

To test the saccharification efficiency of lignocellulosic biomass on a lab-scale, a manual saccharification protocol was established that uses only small amounts of biomass and a low concentration of enzyme. This protocol can be used for different plant species like Arabidopsis thaliana, tobacco, maize and poplar. The low enzyme concentrations make it possible to detect subtle improvements in saccharification yield and to analyze the speed of hydrolysis. Although a specific acid and alkali pretreatment were included, the saccharification step can be preceded by any other pretreatment. Because no advanced equipment is necessary, this protocol can be carried out in many laboratories to analyze saccharification yield. The protocol was initially described in Van Acker et al. (2013).
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