Suberin Goes Genomics: Use of a Short Living Plant to Investigate a Long Lasting Polymer

Suberin is a highly persistent cell wall polymer, predominantly composed of long-chain hydroxylated fatty acids. Apoplastic suberin depositions occur in internal and peripheral dermal tissues where they generate lipophilic barriers preventing uncontrolled flow of water, gases, and ions. In addition, suberization provides resistance to environmental stress conditions. Despite this physiological importance the knowledge about suberin formation has increased slowly for decades. Lately, the chemical characterization of suberin in Arabidopsis enabled the proposal of genes required for suberin biosynthesis such as β-ketoacyl-CoA synthases (KCS) for fatty acid elongation and cytochrome P450 oxygenases (CYP) for fatty acid hydroxylation. Advantaged by the Arabidopsis molecular genetic resources the in silico expression pattern of candidate genes, concerted with the tissue-specific distribution of suberin in Arabidopsis, led to the identification of suberin involved genes including KCS2, CYP86A1, and CYP86B1. The isolation of mutants with a modified suberin composition facilitated physiological studies revealing that the strong reduction in suberin in cyp86a1 mutants results in increased root water and solute permeabilities. The enhanced suberin 1 mutant, characterized by twofold increased root suberin content, has increased water-use efficiency and is affected in mineral ion uptake and transport. In this review the most recent findings on the biosynthesis and physiological importance of suberin in Arabidopsis are summarized and discussed

Critical implications of IVDR for innovation in diagnostics: input from the BioMed alliance diagnostics task force

With the implementation of Regulation (European Union [EU]) 2017/746 on in vitro diagnostic medical devices (IVDR), from May 26, 2022, onwards, the development and use of diagnostic tests will be governed by a vastly expanded and upgraded EU regulatory framework. We provide here an overview of the amended transition timelines, the role of notified bodies, EU reference laboratories, expert panels, and the Medical Device Coordination Group (MDCG). We also describe the implications of the IVDR for innovative laboratory medicine by explaining the exemption for in-house devices (IH-IVDs). Two key challenges faced by the academic diagnostic sector are: (1) the stipulation on equivalence of tests (article 5.5d), which poses a new condition for the use of IH-IVDs and (2) the gray area between CE marked in vitro diagnostics (CE-IVDs), modified CE-IVDs, Research Use Only (RUO) tests, and IH-IVDs. Furthermore, the results of a questionnaire on current diagnostic practice conducted by European medical societies collaborating in the BioMed Alliance indicate widespread use of IH-IVDs in diagnostic laboratories across Europe and emphasize the need for support and guidance to comply with the IVDR. Diagnostic equivalents of the European Reference Networks (ERNs) for rare diseases could help ensure affordable and equal access to specialized diagnostics across the EU. Concerted action by clinical and laboratory disciplines, regulators, industry, and patient organizations is needed to support the efficient and effective implementation of the IVDR in a way that preserves innovation and safeguards the quality, safety, and accessibility of innovative diagnostics.Peer reviewe

Patient specific real-time PCR in precision medicine – Validation of IG/TR based MRD assessment in lymphoid leukemia

Detection of patient- and tumor-specific clonally rearranged immune receptor genes using real-time quantitative (RQ)-PCR is an accepted method in the field of precision medicine for hematologic malignancies. As individual primers are needed for each patient and leukemic clone, establishing performance specifications for the method faces unique challenges. Results for series of diagnostic assays for CLL and ALL patients demonstrate that the analytic performance of the method is not dependent on patients’ disease characteristics. The calibration range is linear between 10-1 and 10-5 for 90% of all assays. The detection limit of the current standardized approach is between 1.8 and 4.8 cells among 100,000 leukocytes. RQ-PCR has about 90% overall agreement to flow cytometry and next generation sequencing as orthogonal methods. Accuracy and precision across different labs, and above and below the clinically applied cutoffs for minimal/measurable residual disease (MRD) demonstrate the robustness of the technique. The here reported comprehensive, IVD-guided analytical validation provides evidence that the personalized diagnostic methodology generates robust, reproducible and specific MRD data when standardized protocols for data generation and evaluation are used. Our approach may also serve as a guiding example of how to accomplish analytical validation of personalized in-house diagnostics under the European IVD Regulation

A Processive Glycosyltransferase Involved in Glycolipid Synthesis during Phosphate Deprivation in Mesorhizobium loti▿ †

Natural habitats are often characterized by a low availability of phosphate. In plants and many bacteria, phosphate deficiency causes different physiological responses, including the replacement of phosphoglycerolipids in the membranes with nonphosphorous lipids. We describe here a processive glycosyltransferase (Pgt) in Mesorhizobium loti (Rhizobiales) involved in the synthesis of di- and triglycosyldiacylglycerols (DGlycD and TGlycD) during phosphate deprivation. Cells of the corresponding Δpgt deletion mutant are deficient in DGlycD and TGlycD. Additional Pgt-independent lipids accumulate in Mesorhizobium after phosphate starvation, including diacylglyceryl trimethylhomoserine (DGTS) and ornithine lipid (OL). The accumulation of the nonphosphorous lipids during phosphate deprivation leads to the reduction of phosphoglycerolipids from 90 to 50%. Nodulation experiments of Mesorhizobium wild type and the Δpgt mutant with its host plant, Lotus japonicus, revealed that DGlycD and TGlycD are not essential for nodulation under phosphate-replete or -deficient conditions. Lipid measurements showed that the Pgt-independent lipids including OL and DGTS accumulate to higher proportions in the Δpgt mutant and therefore might functionally replace DGlycD and TGlycD during phosphate deprivation

The New EU Regulation on In Vitro Diagnostic Medical Devices: Implications and Preparatory Actions for Diagnostic Laboratories

Afdeling Klinische Chemie en Laboratoriumgeneeskunde (AKCL

Experience With IVDR Implementation in Three Diagnostic Laboratories: Messages to EU Health Institutions, Diagnostic Healthcare Payers, and Authorities

Regulation (EU) 2017/746 on in vitro diagnostic medical devices1 (IVDR) has been implemented with the aim to safeguard the quality of diagnostic tests in the EU, for example, by requiring robust proof of safety and performance. The IVDR is a product regulation mainly aimed at industry manufacturing and marketing medical devices. While IVDR-compliant diagnostic tests should predominantly be supplied by manufacturers, health institutions have the possibility of manufacturing and using in-house devices (IH-IVDs), provided they meet the Article 5(5) conditions and relevant general safety and performance requirements in Annex I. This “health institution exemption” concerns, for example, their quality management system (QMS), risk management, performance evaluation, and justification of IH-IVD use.2 The first significant task for diagnostic laboratories at health institutions, compliance with Annex I, has been applicable since May 2022, whereas other implementation timelines are shifted based on the December 2021 amendment of the IVDR.3,

Quantification of sterol lipids in plants by quadrupole time-of-flight mass spectrometry

Glycerolipids, sphingolipids, and sterol lipids constitute the major lipid classes in plants. Sterol lipids are composed of free and conjugated sterols, i.e., sterol esters, sterol glycosides, and acylated sterol glycosides. Sterol lipids play crucial roles during adaption to abiotic stresses and plant-pathogen interactions. Presently, no comprehensive method for sterol lipid quantification in plants is available. We used nanospray ionization quadrupole-time-of-flight mass spectrometry (Q-TOF MS) to resolve and identify the molecular species of all four sterol lipid classes from Arabidopsis thaliana. Free sterols were derivatized with chlorobetainyl chloride. Sterol esters, sterol glycosides, and acylated sterol glycosides were ionized as ammonium adducts. Quantification of molecular species was achieved in the positive mode after fragmentation in the presence of internal standards. The amounts of sterol lipids quantified by Q-TOF MS/MS were validated by comparison with results obtained with TLC/GC. Quantification of sterol lipids from leaves and roots of phosphate-deprived A. thaliana plants revealed changes in the amounts and molecular species composition. The Q-TOF method is far more sensitive than GC or HPLC. Therefore, Q-TOF MS/MS provides a comprehensive strategy for sterol lipid quantification that can be adapted to other tandem mass spectrometers