Neutrophil gelatinase-associated lipocalin in kidney transplantation is an early marker of graft dysfunction and is associated with one-year renal function

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) has been suggested as potential early marker of delayed graft function (DGF) following kidney transplantation (KTx). We conducted a prospective study in 40 consecutive KTx recipients to evaluate serial changes of uNGAL within the first week after KTx and assess its performance in predicting DGF (dialysis requirement during initial posttransplant week) and graft function throughout first year. Urine samples were collected on post-KTx days 0, 1, 2, 4, and 7. Linear mixed and multivariable regression models, receiver-operating characteristic (ROC), and areas under ROC curves were used. At all-time points, mean uNGAL levels were significantly higher in patients developing DGF (n = 18). Shortly after KTx (3-6 h), uNGAL values were higher in DGF recipients (on average +242 ng/mL, considering mean dialysis time of 4.1 years) and rose further in following days, contrasting with prompt function recipients. Day-1 uNGAL levels accurately predicted DGF (AUC-ROC = 0.93), with a performance higher than serum creatinine (AUC-ROC = 0.76), and similar to cystatin C (AUC-ROC = 0.95). Multivariable analyses revealed that uNGAL levels at days 4 and 7 were strongly associated with one-year serum creatinine. Urinary NGAL is an early marker of graft injury and is independently associated with dialysis requirement within one week after KTx and one-year graft function.The authors recognize and thank Abbott Laboratories for their valuable contribution for donating kits used for testing almost 200 samples. The remaining kits were financed by funds of Unit for Multidisciplinary Investigation in Biomedicine, Porto, Portuga

Various Spatiotemporal Expression Profiles of Anther-Expressed Genes in Rice

The male gametophyte and tapetum play different roles during anther development although they are differentiated from the same cell lineage, the L2 layer. Until now, it has not been possible to delineate their transcriptomes due to technical difficulties in separating the two cell types. In the present study, we characterized the separated transcriptomes of the rice microspore/pollen and tapetum using laser microdissection (LM)-mediated microarray. Spatiotemporal expression patterns of 28,141 anther-expressed genes were classified into 20 clusters, which contained 3,468 (12.3%) anther-enriched genes. In some clusters, synchronous gene expression in the microspore and tapetum at the same developmental stage was observed as a novel characteristic of the anther transcriptome. Noteworthy expression patterns are discussed in connection with gene ontology (GO) categories and gene annotations, which are related to important biological events in anther development, such as pollen maturation, pollen germination, pollen tube elongation and pollen wall formation

Efficient preparation of Arabidopsis pollen tubes for ultrastructural analysis using chemical and cryo-fixation

The pollen tube (PT) serves as a model system for investigating plant cell growth and morphogenesis. Ultrastructural studies are indispensable to complement data from physiological and genetic analyses, yet an effective method is lacking for PTs of the model plant Arabidopsis thaliana. Methods: Here, we present reliable approaches for ultrastructural studies of Arabidopsis PTs, as well as an efficient technique for immunogold detection of cell wall epitopes. Using different fixation and embedding strategies, we show the amount of PT ultrastructural details that can be obtained by the different methods. Results: Dozens of cross-sections can be obtained simultaneously by the approach, which facilitates and shortens the time for evaluation. In addition to in vitro-grown PTs, our study follows the route of PTs from germination, growth along the pistil, to the penetration of the dense stylar tissue, which requires considerable mechanical forces. To this end, PTs have different strategies from growing between cells but also between the protoplast and the cell wall and even within each other, where they share a partly common cell wall. The separation of PT cell walls in an outer and an inner layer reported for many plant species is less clear in Arabidopsis PTs, where these cell wall substructures are connected by a distinct transition zone. Conclusions: The major advancement of this method is the effective production of a large number of longitudinal and cross-sections that permits obtaining a detailed and representative picture of pollen tube structures in an unprecedented way. This is particularly important when comparing PTs of wild type and mutants to identify even subtle alterations in cytoarchitecture. Arabidopsis is an excellent plant for genetic manipulation, yet the PTs, several-times smaller compared to tobacco or lily, represent a technical challenge. This study reveals a method to overcome this problem and make Arabidopsis PTs more amenable to a combination of genetic and ultrastructural analyses

An Osmotic Model of the Growing Pollen Tube

Pollen tube growth is central to the sexual reproduction of plants and is a longstanding model for cellular tip growth. For rapid tip growth, cell wall deposition and hardening must balance the rate of osmotic water uptake, and this involves the control of turgor pressure. Pressure contributes directly to both the driving force for water entry and tip expansion causing thinning of wall material. Understanding tip growth requires an analysis of the coordination of these processes and their regulation. Here we develop a quantitative physiological model which includes water entry by osmosis, the incorporation of cell wall material and the spreading of that material as a film at the tip. Parameters of the model have been determined from the literature and from measurements, by light, confocal and electron microscopy, together with results from experiments made on dye entry and plasmolysis in Lilium longiflorum. The model yields values of variables such as osmotic and turgor pressure, growth rates and wall thickness. The model and its predictive capacity were tested by comparing programmed simulations with experimental observations following perturbations of the growth medium. The model explains the role of turgor pressure and its observed constancy during oscillations; the stability of wall thickness under different conditions, without which the cell would burst; and some surprising properties such as the need for restricting osmotic permeability to a constant area near the tip, which was experimentally confirmed. To achieve both constancy of pressure and wall thickness under the range of conditions observed in steady-state growth the model reveals the need for a sensor that detects the driving potential for water entry and controls the deposition rate of wall material at the tip

Facile preparation of a cellulose microfibers–exfoliated graphite composite: a robust sensor for determining dopamine in biological samples

© 2017, Springer Science+Business Media B.V. A simple and robust dopamine (DA) sensor was developed using a cellulose microfibers (CMF)–exfoliated graphite composite-modified screen-printed carbon electrode (SPCE) for the first time. The graphite-CMF composite was prepared by sonication of pristine graphite in CMF solution and was characterized by high-resolution scanning electron microscopy, Fourier transform, infrared, and Raman spectroscopy. The cyclic voltammetry results reveal that the graphite-CMF composite modified SPCE has superior electrocatalytic activity against oxidation of dopamine than SPCE modified with pristine graphite and CMF. The presence of large edge plane defects on exfoliated graphite and abundant oxygen functional groups of CMF enhance electrocatalytic activity and decrease potential to oxidize DA. Differential pulse voltammetry was used to quantify DA using the graphite-CMF composite-modified SPCE and demonstrated a linear response for DA detection in the range of 0.06–134.5 µM. The sensor shows a detection limit at 10 nM with an appropriate sensitivity and displays appropriate recovery of DA in human serum samples with good repeatability. Sensor selectivity is demonstrated in the presence of 50-fold concentrations of potentially active interfering compounds including ascorbic acid, uric acid, and dihydroxybenzene isomers

Signal processing and transduction in plant cells: the end of the beginning?

Plants have a very different lifestyle to animals, and one might expect that unique molecules and processes would underpin plant-cell signal transduction. But, with a few notable exceptions, the list is remarkably familiar and could have been constructed from animal studies. Wherein, then, does lifestyle specificity emerge

Calcium Channel Activity during Pollen Tube Growth and Reorientation.

We have shown previously that the inhibition of pollen tube growth and its subsequent reorientation in Agapanthus umbellatus are preceded by an increase in cytosolic free calcium ([Ca2+]c), suggesting a role for Ca2+ in signaling these processes. In this study, a novel procedure was used to measure Ca2+ channel activity in living pollen tubes subjected to various growth reorienting treatments (electrical fields and ionophoretic microinjection). The method involves adding extracellular Mn2+ to quench the fluorescence of intracellular Indo-1 at its ca2+-insensitive wavelength (isosbestic point). The spatial and temporal kinetics of Ca2+ channel activity correlated well with measurements of [Ca2+]c dynamics obtained by fluorescence ratio imaging of Indo-1. Tip-focused gradients in Ca2+ channel activity and [Ca2+]c were observed and quantified in growing pollen tubes and in swollen pollen tubes before reoriented growth. In nongrowing pollen tubes, Ca2+ channel activity was very low and [Ca2+]c gradients were absent. Measurements of membrane potential indicated that the growth reorienting treatments induced a depolarization of the plasma membrane, suggesting that voltage-gated Ca2+ channels might be activated