Advanced portable micro-SORS prototype coupled with SERDS for heritage science

We investigate the subsurface composition of turbid materials at the micro scale by means of a portable non-invasive technique, micro-spatially offset Raman spectroscopy (micro-SORS), combined with shifted excitation Raman difference spectroscopy (SERDS). This combination enables the microscale layer analysis and allows to deal effectively with highly fluorescing samples as well as ambient light, all in a form of an in-house portable prototype device optimised for applications in heritage science. The instrument comprises ability to simultaneously collect multiple spectra by means of an optical fibre bundle, thus reducing the dead time and simplifying the ease of deployment of the technique. The performance of the synergy between micro-SORS and 785 nm SERDS dual-wavelength diode laser is demonstrated on a stratified mock-up painting samples including highly fluorescing painted layers. This instrumental approach could be ground-breaking in heritage science, due to the largely unmet need of analysing the molecular composition of subsurface of artworks non-invasively and in situ, and in the presence of fluorescent background and ambient light. Moreover, many other fields are expected to benefit from this technological advancement such as solar energy, forensic and food analytical areas.

Silicon nanoparticles vs trace elements toxicity: Modus operandi and its omics bases

Phytotoxicity of trace elements (commonly misunderstood as 'heavy metals') includes impairment of functional groups of enzymes, photo-assembly, redox homeostasis, and nutrient status in higher plants. Silicon nanoparticles (SiNPs) can ameliorate trace element toxicity. We discuss SiNPs response against several essential (such as Cu, Ni, Mn, Mo, and Zn) and non-essential (including Cd, Pb, Hg, Al, Cr, Sb, Se, and As) trace elements. SiNPs hinder root uptake and transport of trace elements as the first line of defence. SiNPs charge plant antioxidant defence against trace elements-induced oxidative stress. The enrolment of SiNPs in gene expressions was also noticed on many occasions. These genes are associated with several anatomical and physiological phenomena, such as cell wall composition, photosynthesis, and metal uptake and transport. On this note, we dedicate the later sections of this review to support an enhanced understanding of SiNPs influence on the metabolomic, proteomic, and genomic profile of plants under trace elements toxicity.

Copper and zinc accumulation, distribution, and tolerance in Pistia stratiotes L.; revealing the role of root caps

Pollution by potentially toxic trace metals, such as copper or zinc, is global. Both Cu and Zn are essential microelements, which in higher concentrations become toxic. The aquatic plant Pistia stratiotes(L. has great potential for phytoremediation. Also, it has an unusually large and easily detachable root cap, which makes it a suitable model for studying the potential role of the root cap in metal uptake. Plant response to environmentally relevant concentrations of Cu (0.1, 0.3, and 1 μM) and Zn (0.3, 1, and 3 μM) was investigated with the aim of studying their interaction and distribution at the root tissue level as well as revealing their tolerance mechanisms. Changes in the root anatomy and plant ionome were determined using light and fluorescence microscopy, ICP-MS, and μXRF imaging. Alterations in photosynthetic activity caused by Cu or Zn excesses were monitored by direct imaging of fast chlorophyll fluorescence kinetics (OJIP). Fe and Mn were preferentially localized in the root cap, while Ca, Cu, Ni, and Zn were mainly in the root tip regardless of the Cu/Zn treatment. Translocation of Cu and Zn to the leaves increased with higher doses, however the translocation factor was the lowest in the highest treatments. Measurements of photosynthetic parameters showed a higher susceptibility of electron transport flux from QA to QB under increasing Cu than Zn supply. This, along with our findings regarding the root anatomy and the differences in Ca accumulation and distribution, led to the conclusion that P. stratiotes is more effective for Zn remediation than Cu.

[Radiation-induced cataract-an occult risk for urologists]

BACKGROUND

Radiation-induced cataracts represent a relevant risk to people occupationally exposed to radiation. The annual limit dose for the eye lens was reduced to 20 mSv per year by German legislation (radiation protect law StrlSchG 2017; 2013/59/Euratom) based on recommendation of International Commission on Radiation Protection (2011 ICRP) to avoid radiation-induced cataracts.

OBJECTIVES

Is there a risk of exceeding the annual limit dose for the eye lens in routine urological practice without special radiation protection for the head?

METHODS

As part of a prospective, monocentric dosimetry study, of 542 different urological, fluoroscopically guided interventions, the eye lens dose was determined using a forehead dosimeter (thermo-luminescence dosemeter TLD, Chipstrate) over a period of 5 months.

RESULTS

An average head dose of 0.05 mSv per intervention (max. 0.29 mSv) was found with an average dose area product of 485.33 Gy/cm². Significant influencing factors for a higher dose were a higher patient body mass index (BMI), a longer operation time, and a higher dose area product. The level of experience of the surgeon showed no significant influence.

DISCUSSION

With 400 procedures per year or an average of 2 procedures per working day, the critical annual limit value for the eye lenses or for the risk of radiation-induced cataract would be exceeded without special protective measures.

CONCLUSION

Consistently effective radiation protection of the eye lens is essential for daily work in uroradiological interventions. This may require further technical developments.

Silicon nanoparticles (SiNPs) restore photosynthesis and essential oil content by upgrading enzymatic antioxidant metabolism in lemongrass (Cymbopogon flexuosus) under salt stress

Lemongrass (Cymbopogon flexuosus) has great relevance considering the substantial commercial potential of its essential oil. Nevertheless, the increasing soil salinity poses an imminent threat to lemongrass cultivation given its moderate salt-sensitivity. For this, we used silicon nanoparticles (SiNPs) to stimulate salt tolerance in lemongrass considering SiNPs special relevance to stress settings. Five foliar sprays of SiNPs 150 mg L^-1 were applied weekly to NaCl 160 and 240 mM-stressed plants. The data indicated that SiNPs minimised oxidative stress markers (lipid peroxidation, H₂O₂ content) while triggering a general activation of growth, photosynthetic performance, enzymatic antioxidant system including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), and osmolyte proline (PRO). SiNPs amplified stomatal conductance and photosynthetic CO₂ assimilation rate by about 24% and 21% in NaCl 160 mM-stressed plants. Associated benefits contributed to pronounced plant phenotype over their stressed counterparts, as we found. Foliar SiNPs sprays assuaged plant height by 30% and 64%, dry weight by 31% and 59%, and leaf area by 31% and 50% under NaCl 160 and 240 mM concentrations, respectively. SiNPs relieved enzymatic antioxidants (SOD, CAT, POD) and osmolyte (PRO) in lemongrass plants stressed with NaCl 160 mM (9%, 11%, 9%, and 12%, respectively) and NaCl 240 mM (13%, 18%, 15%, and 23%, respectively). The same treatment supported the oil biosynthesis improving essential oil content by 22% and 44% during 160 and 240 mM salt stress, respectively. We found SiNPs can completely overcome NaCl 160 mM stress while significantly palliating NaCl 240 mM stress. Thus, we propose that SiNPs can be a useful biotechnological tool to palliate salinity stress in lemongrass and related crops.

Silicon nanoparticles in higher plants: Uptake, action, stress tolerance, and crosstalk with phytohormones, antioxidants, and other signalling molecules

Silicon is absorbed as uncharged mono-silicic acid by plant roots through passive absorption of Lsi1, an influx transporter belonging to the aquaporin protein family. Lsi2 then actively effluxes silicon from root cells towards the xylem from where it is exported by Lsi6 for silicon distribution and accumulation to other parts. Recently, it was proposed that silicon nanoparticles (SiNPs) might share a similar route for their uptake and transport. SiNPs then initiate a cascade of morphophysiological adjustments that improve the plant physiology through regulating the expression of many photosynthetic genes and proteins along with photosystem I (PSI) and PSII assemblies. Subsequent improvement in photosynthetic performance and stomatal behaviour correspond to higher growth, development, and productivity. On many occasions, SiNPs have demonstrated a protective role during stressful environments by improving plant-water status, source-sink potential, reactive oxygen species (ROS) metabolism, and enzymatic profile. The present review comprehensively discusses the crop improvement potential of SiNPs stretching their role during optimal and abiotic stress conditions including salinity, drought, temperature, heavy metals, and ultraviolet (UV) radiation. Moreover, in the later section of this review, we offered the understanding that most of these upgrades can be explained by SiNPs intricate correspondence with phytohormones, antioxidants, and signalling molecules. SiNPs can modulate the endogenous phytohormones level such as abscisic acid (ABA), auxins (IAAs), cytokinins (CKs), ethylene (ET), gibberellins (GAs), and jasmonic acid (JA). Altered phytohormones level affects plant growth, development, and productivity at various organ and tissue levels. Similarly, SiNPs regulate the activities of catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD), and ascorbate-glutathione (AsA-GSH) cycle leading to an upgraded defence system. At the cellular and subcellular levels, SiNPs crosstalk with various signalling molecules such as Ca²⁺, K⁺, Na⁺, nitric oxide (NO), ROS, soluble sugars, and transcription factors (TFs) was also explained.

[Characteristics and prevalence of painful coenesthesia in a pain clinic]

BACKGROUND

Coenesthesia, a rarely described symptom, is classified as schizophrenia according to ICD-10 and can occur independently of psychiatric diseases as a form of pain. The prevalence in chronic pain disorders is still unknown. The present study investigates the characteristics and psychological comorbidities of painful coenesthesia.

MATERIALS AND METHODS

For the present study, all patients were pseudonymized and retrospectively analyzed qualitatively and quantitatively for existing coenesthesia. They were consecutively admitted, examined, and treated in the pain outpatient clinic of the University of Magdeburg over a five-year period (2013-2017).

RESULTS

Of the 844 patients evaluated, 57 (6.7%) fulfilled the criteria of coenesthesia. The pain description may be rather bizarre if the patient is suffering from a psychiatric disorder, but it was also conspicuous by inappropriate localization for the pain description (tooth cramp instead of abdominal cramp). In our study, pain was mainly localized in the facial area (n = 35). Twenty-seven patients had no psychopathological abnormalities and 30 patients could be assigned an additional psychiatric diagnosis. In 23 patients, depression occurred as a psychological comorbidity.

DISCUSSION AND CONCLUSION

Coenesthesia does not necessarily occur in connection or only with schizophrenia. Coenesthesia should be considered if the patient gives a bizarre description of pain, but also in common pain descriptions, such as burning, stabbing, cramping, or a feeling of pressure, if these are related to unusual locations (cramping tooth).

Aluminum toxicity in plants and its possible mitigation in acid soils by biochar: A review

Toxicity of aluminum (Al) is a serious problem for agricultural plants, especially due to excessive soil acidification caused by continuous intensive agriculture and modified environmental conditions related with global climate change. Decreased root elongation and shoot growth, reduced biomass production, nutrient imbalance and altered physiological and metabolic processes are responsible for lower yield and crop quality and therefore, decreased variability and productivity of the land. Recently, biochar is gaining popularity for ameliorating metal toxicity in soils. However, there is a lack of comprehensive information regarding the effects of biochar and its functioning. Multiple mechanisms are involved in ameliorating Al toxicity in which inherent properties of biochar influencing Al adsorption, absorption, complexation, cation exchange and electrostatic interaction are considered to play major roles. Modification of biochar to enhance these mechanisms might hold the key for long term solution. Present review indicates gaps for further research. Long term field studies are needed to understand the effects of biochar on Al toxicity.

The secrets of calcicole species revealed

This article comments on: Kotula L, Clode PL, Ranathunge K, Lambers H. 2021. Role of roots in adaptation of soil-indifferent Proteaceae to calcareous soils in south-western Australia. Journal of Experimental Botany 72, 1490–1505.

Sharing primary percutaneous coronary intervention care: first experiences with South Limburg ST-elevation myocardial infarction network

Background

In the region of South Limburg, the Netherlands, a shared ST-elevation myocardial infarction (STEMI) networking system (SLIM network) was implemented. During out-of-office hours, two percutaneous coronary intervention (PCI) centres—Maastricht University Medical Centre and Zuyderland Medical Centre—are supported by the same interventional cardiologist. The aim of this study was to analyse performance indicators within this network and to compare them with contemporary European Society of Cardiology guidelines.

Methods

Key time indicators for an all-comer STEMI population were registered by the emergency medical service and the PCI centres. The time measurements showed a non-Gaussian distribution; they are presented as median with 25th and 75th percentiles.

Results

Between 1 February 2018 and 31 March 2019, a total of 570 STEMI patients were admitted to the participating centres. The total system delay (from emergency call to needle time) was 65 min (53–77), with a prehospital system delay of 40 min (34–47) and a door-to-needle time of 22 min (15–34). Compared with in-office hours, out-of-office hours significantly lengthened system delays (55 (47–66) vs 70 min (62–81), p < 0.001), emergency medical service transport times (29 (24–34) vs 35 min (29–40), p < 0.001) and door-to-needle times (17 (14–26) vs 26 min (18–37), p < 0.001).

Conclusions

With its effective patient pathway management, the SLIM network was able to meet the quality criteria set by contemporary European revascularisation guidelines.

Alleviation mechanisms of metal(loid) stress in plants by silicon: a review

Silicon (Si), although not considered as an essential element for plants in general, can ameliorate the phytotoxicity induced by excess metal(loid)s whether non-essential (e.g. Cd, Pb, Cr, Al, As, and Sb) or essential (e.g. Cu, Ni, and Zn). The Si-enhanced resistance allowing plants to cope with this type of abiotic stress has been developed at multiple levels in plants. Restriction of root uptake and immobilization of metal(loid)s in the rhizosphere by Si is probably one of the first defence mechanism. Further, retention of elements in the root apoplasm might enhance the resistance and vigour of plants. At the cellular level, the formation of insoluble complexes between Si and metal(loid)s and their storage within cell walls help plants to decrease available element concentration and restrict symplasmic uptake. Moreover, Si influences the oxidative status of plants by modifying the activity of various antioxidants, improves membrane stability, and acts on gene expression, although its exact role in these processes is still not well understood. This review focuses on all currently known plant-based mechanisms related to Si supply and involved in amelioration of stress caused by excess metal(loid)s.

Patients undergoing urgent trans-aortic valve implantation suffer from an increased mortality rate

Introduction

Information on the outcome of urgent Transcatheter valve implantations (TAVI) is scarce, but available data suggest that it could be a reasonable option for the treatment of decompensated severe aortic valve stenosis. The prospects of an all-comer urgent population, however, are unknown. Here we report our experience with clinically indicated urgent TAVI implantation in an unselected patient population with severe aortic valve stenosis (AS).

Purpose

To compare the outcome of patients undergoing urgent or elective TAVI and to identify potential predictors of outcome.

Methods

A retrospective, single centre study of AS patients undergoing femoral or apical TAVI between 01. 01.2013 and 30.09.2018 was performed. Demographic information, medical history, clinical and procedural data were collected from the local electronic database. Urgent implantation was defined as accelerated, in-hospital patient preparation and urgent device placement following an acute admission. Survival was investigated with Kaplan-Meier survival analysis and log-rank test. Regression analysis was performed to identify possible predictors of mortality.

Results

During the study period TAVI was performed in 631 patients, of whom 53 (8.4%) underwent urgent TAVI. In the case of urgent procedures, the median admission-to-procedure time was 18 [10–29] days. Age, gender and the prevalence of diabetes mellitus, chronic obstructive lung disease (COPD) and a glomerular filtration rate of ≤30ml/min was comparable among the groups. Patients in the urgent group had a lower BMI (26 [23–28] vs. 27 [24–30]; p&lt;0.05), had more frequently an ejection fraction &lt;30% (30% vs 4%p&lt;0.001) and a higher Euroscore II (5.3 [3.4–10.9]% vs 2.9 [1.7–4.5]%; p&lt;0.001). The rate of apical implantation and post-operative stroke, pacemaker implantation and renal failure did not differ between the groups. Urgent patients, however, needed longer post-procedural hospitalization (6 [4–9] vs 4 [3–6] days; p&lt;0.001) and had higher in-hospital (11.3% vs 3,1%; &lt;0.001) and one-year mortality rates (28.3% vs 8.5%; p&lt;0.001). Urgency was an independent predictor of overall one-year mortality (HR 3.0, p=0.001) and worsened the survival of the individuals who were discharged from the hospital (out-of-hospital mortality at one-year; HR 2.8, p=0.011), but had no effect on in-hospital mortality. In-hospital mortality was mainly determined by apical access (OR 3.1; p=0.016) and major post-operative stroke (OR 8.8.; p=0.006), with both worsening overall 1-year survival too (HR 1.8 for apical access and 4.8 for stroke; p&lt;0.05). Mortality after a successful hospital discharge was increased not only by urgency (HR 2.8, p=0.011), but by COPD (HR 2.1; p=0.04) and prolonged post-operative hospitalization (HR 1.05/day; p=0.001) as well.

Conclusion

Stabilizing AS patients can mitigate the effect of urgency on peri-procedural survival. Urgency remains, however, an important determinant of one-year TAVI outcome.

Funding Acknowledgement

Type of funding source: None

A new insight on structural and some functional aspects of peri-endodermal thickenings, a specific layer in Noccaea caerulescens roots

BACKGROUND AND AIMS

Cell walls of the peri-endodermis, a layer adjacent to the endodermis in alpine pennycress (Noccaea caerulescens) roots, form C-shaped peri-endodermal thickenings (PETs). Despite its specific position close to the endodermis, the assumed similarity of PETs to phi thickenings in many other species, and the fact that N. caerulescens is a well-studied heavy-metal-hyperaccumulating plant, the PET as a root trait is still not understood.

METHODS

Here, we characterized PET cell walls by histochemical techniques, Raman spectroscopy, immunolabelling and electron microscopy. Moreover, a role of PETs in solute transport was tested and compared with Arabidopsis thaliana plants, which do not form PETs in roots.

KEY RESULTS

Cell walls with PETs have a structured relief mainly composed of cellulose and lignin. Suberin, typical of endodermal cells, is missing but pectins are present on the inner surface of the PET. Penetrating dyes are not able to cross PETs either by the apoplasmic or the symplasmic pathway, and a significantly higher content of metals is found in root tissues outside of PETs than in innermost tissues.

CONCLUSIONS

Based on their development and chemical composition, PETs are different from the endodermis and closely resemble phi thickenings. Contrarily, the different structure and dye impermeability of PETs, not known in the case of phi thickenings, point to an additional barrier function which makes the peri-endodermis with PETs a unique and rare layer.

Cd-induced difference in root characteristics along root apex contributes to variation in Cd uptake and accumulation between two contrasting ecotypes of Sedum alfredii

The root apex is the most active part for water and ions uptake, however, longitudinal alterations in root characteristics along root apex and consequences for metal uptake in hyperaccumulator are poorly understood. Here, we compared cadmium (Cd)-induced longitudinal alterations in root apex of two ecotypes of Sedum alfredii and assess their effects on Cd uptake. Under Cd treatment, cell death began from epidermis to the stele in non-hyperaccumulating ecotype (NHE) over time, and the number of dead cells was significantly higher than that in hyperaccumulating ecotype (HE). Cd-induced the presence of border-like cells (BLCs) surrounding the root tip of NHE prevented Cd from entering roots, however, almost no BLCs were observed in the root tip of in HE. Besides, Cd-treated NHE exhibited 76% and 52% decrease in the proportions of meristematic and elongation zone, respectively, resulting in lower Cd influx and less intensive Cd-fluorescence in these zones, as compared with HE. In the differentiation zone, Cd induced earlier initiation of root hairs (RHs), lower RHs-density, shorter RHs-length, thicker RHs-radius and less trichoblasts in NHE than those in HE. These remarkable variations led to less Cd influx and lower intensity of Cd-fluorescence in RHs of NHE than those of HE. Furthermore, decline in cell wall thickness under Cd exposure resulted in less cell-wall-bond Cd in the cell wall of HE. Therefore, Cd-induced alterations in root characteristics alongside root apex contributed to the difference in Cd uptake and accumulation between two ecotypes of S. alfredii.

Silicification of Root Tissues

Silicon (Si) is not considered an essential element, however, its tissue concentration can exceed that of many essential elements in several evolutionary distant plant species. Roots take up Si using Si transporters and then translocate it to aboveground organs. In some plant species, root tissues are also places where a high accumulation of Si can be found. Three basic modes of Si deposition in roots have been identified so far: (1) impregnation of endodermal cell walls (e.g., in cereals, such as Triticum (wheat)); (2) formation of Si-aggregates associated with endodermal cell walls (in the Andropogoneae family, which includes Sorghum and Saccharum (sugarcane)); (3) formation of Si aggregates in "stegmata" cells, which form a sheath around sclerenchyma fibers e.g., in some palm species (Phoenix (date palm)). In addition to these three major and most studied modes of Si deposition in roots, there are also less-known locations, such as deposits in xylem cells and intercellular deposits. In our research, the ontogenesis of individual root cells that accumulate Si is discussed. The documented and expected roles of Si deposition in the root is outlined mostly as a reaction of plants to abiotic and biotic stresses.

P959The specific characteristics and independent predictors of no-reflow phenomenon, development of a clinically-adaptable risk estimation system

Introduction

No-reflow (NR) phenomenon occurs, when myocardial perfusion is not re-established despite opening the coronary artery during percutaneous coronary intervention (PCI).

Purpose

Our aim was to identify no-reflow specific characteristics, its independent predictors, and to develop a clinically-adaptable risk score.

Methods

We have analysed 4085 patient data from two Hungarian cardiovascular centres. We included all STEMI/NSTEMI patients underwent PCI (n=3187). 158 patients treated with papaverine/adenosine formed NR group, while 3029 patients were in control (C) group. Anamnestic parameters, laboratory and operation data were compared. Statistical analysis was carried out with Mann-Whitney-, Fisher test, binary logistic regression and Kaplan Meier survival curve. Based on our results, we designed a risk estimation system, checking its applicability with ROC analysis.

Results

As for NR-specific characteristics, malignant ventricular arrhythmias (11% vs. 4%, p=0,0031; NR-C consequently) and complications (21% vs. 11%, p=0,064) showed their vulnerability. The increment of glucose (8,1 vs. 7,1 mmol/l, p=0,004), WBC (12,08 vs. 10,5 G/l, p=0,001), CRP (12,46 vs. 7,67 mg/l, p=0,051) and LDL levels (3,34 vs. 3,13 mmol/l, p=0,059) supported the pathomechanism of NR. Higher biomarker levels (troponinT: 2040 vs. 510,5 ng/ml; CK-MB: 100,4 vs. 63,65 U/l, p<0,0001) indicated severe perfusion disturbance. Tendency was seen in higher BMI (28,65 vs. 28,03 kg/m2, p=0,12). STEMI dominated in NR (83 vs. 59%, p<0,0001). Lower platelet level (213,3 vs. 228 G/l, p=0,107) and single vessel disease (46 vs. 25%, p=0,0042) characterized NR.

30-day survival was significantly different (85,1 vs. 93,54%, p<0,0001). The mortality rate of NR in STEMI was 69,7% (69,7% vs. 7,94%, p<0,0001) and in NSTEMI 3,7% (3,7% vs. 4,32%).

From the significant differences, CRP was the independent predictor of NR (OR: 1,011, p=0,004; pro 1 mg/l change). Examining STEMI/NSTEMI separately, in STEMI CRP was the independent predictor (OR: 1,0092, p=0,036). In NSTEMI LDL (OR: 4,23, p=0,021) was the independent factor.

In the risk score, the following 8 parameters were included: BMI>28 kg/m2, glucose>8 mmol/l, WBC>12 G/l, CK-MB>100 U/l, hs troponin T>2000 ng/ml, CRP>12 mg/l, LDL>3,3 mmol/l, STEMI (yes/no), thus maximum 8 points could be reached. Low (0–1 points, 5–20%), moderate (2–5 points, 55–70%) and high risk groups (6–8 points, 41–11%) were formed. Supervising the model with ROC analysis: AUC=0,69, p=0,0026, which indicates its ability to discriminate effectively between different risk levels of NR.

Conclusions

The specific characteristics of NR group were identified, from which CRP was the independent predictor - as well as in STEMI, while in NR-NSTEMI LDL was the independent factor. With the elaborated risk estimation system –using anamnestic and routine laboratory parameters– NR could be predicted and unsuccessful PCI could be reduced, resulting in positive therapeutic consequences.

Silicon Uptake and Localisation in Date Palm (Phoenix dactylifera) - A Unique Association With Sclerenchyma

Date palm (Phoenix dactylifera) can accumulate as much as 1% silicon (Si), but not much is known about the mechanisms inherent to this process. Here, we investigated in detail the uptake, accumulation and distribution of Si in date palms, and the phylogeny of Si transporter genes in plants. We characterized the PdNIP2 transporter following heterologous expression in Xenopus oocytes and used qPCR to determine the relative expression of Si transporter genes. Silicon accumulation and distribution was investigated by light microscopy, scanning electron microscopy coupled with X-ray microanalysis and Raman microspectroscopy. We proved that PdNIP2-1 codes for a functional Si-permeable protein and demonstrated that PdNIP2 transporter genes were constitutively expressed in date palm. Silicon aggregates/phytoliths were found in specific stegmata cells present in roots, stems and leaves and their surfaces were composed of pure silica. Stegmata were organized on the outer surface of the sclerenchyma bundles or associated with the sclerenchyma of the vascular bundles. Phylogenetic analysis clustered NIP2 transporters of the Arecaceae in a sister position to those of the Poaceae. It is suggested, that Si uptake in date palm is mediated by a constitutively expressed Si influx transporter and accumulated as Si aggregates in stegmata cells abundant in the outer surface of the sclerenchyma bundles (fibers).

c-Met and PD-L1 on Circulating Exosomes as Diagnostic and Prognostic Markers for Pancreatic Cancer

Exosomes are membrane vesicles which offer potential as blood derived biomarkers for malign tumors in clinical practice. Pancreatic cancer is counted among cancer diseases with the highest mortality. The present work seeks to assess whether pancreatic carcinomas release exosomes which express c-Met (proto-oncogene mesenchymal-epithelial transition factor) and PD-L1 (programmed cell death 1 ligand 1), and whether the detection of such expression in serum has diagnostic or prognostic meaning for the affected patients. Exosome isolation was performed on culture media of one benign pancreatic cell line and ten pancreatic carcinoma cell lines as well as on serum samples from 55 patients with pancreatic ductal adenocarcinoma (PDAC), 26 patients with chronic pancreatitis and 10 patients with benign serous cyst adenoma of the pancreas. Exosomes were bound to latex beads and stained with antibodies against c-Met or PD-L1. Analysis of fluorescence intensity was performed by flow cytometry. In terms of c-Met, the mean fluorescence intensity of PDAC-patients was significantly higher than the fluorescence intensity of the comparative patients with benign disease (p < 0.001). A diagnostic test based on c-Met resulted in a sensitivity of 70%, a specificity of 85% and a diagnostic odds ratio of 13:2. The specificity of the test can be further improved by combining it with the established tumor marker carbohydrate antigen 19-9 (CA 19-9). In addition, c-Met-positive patients showed a significantly shorter postoperative survival time (9.5 vs. 21.7 months, p < 0.001). In terms of PD-L1, no significant difference between fluorescence intensity of PDAC-patients and comparative patients was detectable. However, PD-L1-positive PDAC-patients also showed a significantly shorter postoperative survival time (7.8 vs. 17.2 months, p = 0.043). Thus, both markers can be considered as negative prognostic factors.

[Treatment outcomes of recurrent respiratory papillomatosis : Retrospective analysis of juvenile and adult cases. German version]

BACKGROUND

Recurrent respiratory papillomatosis (RRP) is a rare, chronic disease of viral etiology which is characterized by multiple, recurrent growth of papillomas in the aerodigestive tract.

MATERIALS AND METHODS

The surgical outcomes and the recurrence rates of 106 patients with RRP of the larynx were analyzed. The patients were treated at the University of Magdeburg between 1983 and 2014. The surgical outcomes of conventional and laser surgery regarding time to relapse and complications were compared. In addition, the influence of the quadrivalent vaccine Gardasil® on the disease was analyzed in 10 patients.

RESULTS

Children with RRP had a statistically significant greater number of surgeries throughout their lifetimes compared to adult patients. There were no differences between the adult (n = 79) and juvenile (n = 27) groups in the time to relapse and the number of surgeries/year. The time to relapse and number of procedures/year were not influenced by the various surgical methods. Complications after conventional and laser surgery were not statistically different between the two groups. Serious complications and the need for a tracheotomy were only reported after conventional surgery. In the 10 patients who were immunized with Gardasil®, a statistically significant lower number of surgeries/year after vaccination was achieved.

CONCLUSION

RRP is a rare disease. Treatment requires experience and may be very difficult. The analysis of the course of the disease has shown that the treatment of choice is surgical excision with the CO₂ laser combined with the quadrivalent or polyvalent vaccine. Consequent vaccination of both boys and girls has the potential to reduce the occurrence of RRP.

Tobacco plants (Nicotiana benthamiana) were influenced by silicon and were not infected by dodder (Cuscuta europaea)

The effect of silicon (Si) on tobacco (Nicotiana benthamiana) development and dodder (Cuscuta europaea) - tobacco interaction were studied. Three Si application approaches were tested: tobacco seed priming (2.5 mM Si and 5 mM Si; 2.5S, 5S), watering tobacco plants with Si solution (2.5 mM Si and 5 mM Si; 2.5W, 5W) and foliar application (1 mM Si and 2.5 mM Si; 1F, 2.5F). Dodder was not able to infect the host plant in almost all Si treatments. Only in the control and 2.5W treatments was dodder able to infect its host. A significant increase in all observed antioxidant enzymes activities (POX, CAT and SOD) occurred in the plants of 2.5W treatment after infection in comparison with the uninfected 2.5W treatment and control plants, which indicated the importance of antioxidant enzymes activities in the plant parasite - host interaction. Resistance of Si treated plants to dodder could have been due to the changes in the cell wall properties of the epidermis and cortex where activity of POX was confirmed histochemically. The growth and development of tobacco shoots were evaluated after four and eight weeks of cultivation in the individual Si treatments. The development of shoots was enhanced after eight weeks of cultivation in the 2.5S, 5S, 2.5W and 5W treatments in comparison with the control treatment. However, a negative effect of Si was observed in 1F and 2.5F treatments. In the majority of cases, the plants treated with Si had decreased chlorophyll content when compared to control, except for chl a in 5W plants after 8 weeks of cultivation. Contrary to this, carotenoids increased in all Si treated plants after eight weeks cultivation in comparison with the control. The secondary xylem formation in tobacco was enhanced after 4 and 8 weeks cultivation in shoots of plants receiving the 2.5S, 5S, 2.5W and 5W treartments. The cambium was the most active in producing secondary xylem in the 2.5S treatment. Protein profile and antioxidant enzymes activities (POX, CAT and SOD) were altered by Si treatment. After 8 weeks of cultivation, activities of POX were significantly decreased in 2.5S, 5S, 2.5W and 5W in comparison with control. Catalase was decreased in 2.5S, 5S and 5W in comparison with the control, however, 1F and 2.5F treatments had significantly increased CAT and SOD activities. The specific activity of POX was confirmed histochemically in Si treated plants in the cell walls of several stem tissues like the epidermis, cortex and pith. A small amount of H2O2 was detected in leaves in the control and Si treated plants. The amount of O2- decreased in all treatments with time. The highest Si concentration in the plants (almost 800 mg . kg-1 d. w.) was detected in the 2.5W, 5W treatments.

Abscisic acid-mediated modifications of radial apoplastic transport pathway play a key role in cadmium uptake in hyperaccumulator Sedum alfredii

Abscisic acid (ABA) is a key phytohormone underlying plant resistance to toxic metals. However, regulatory effects of ABA on apoplastic transport in roots and consequences for uptake of metal ions are poorly understood. Here, we demonstrate how ABA regulates development of apoplastic barriers in roots of two ecotypes of Sedum alfredii and assess effects on cadmium (Cd) uptake. Under Cd treatment, increased endogenous ABA level was detected in roots of nonhyperaccumulating ecotype (NHE) due to up-regulated expressions of ABA biosynthesis genes (SaABA2, SaNCED), but no change was observed in hyperaccumulating ecotype (HE). Simultaneously, endodermal Casparian strips (CSs) and suberin lamellae (SL) were deposited closer to root tips of NHE compared with HE. Interestingly, the vessel-to-CSs overlap was identified as an ABA-driven anatomical trait. Results of correlation analyses and exogenous applications of ABA/Abamine indicate that ABA regulates development of both types of apoplastic barriers through promoting activities of phenylalanine ammonialyase, peroxidase, and expressions of suberin-related genes (SaCYP86A1, SaGPAT5, and SaKCS20). Using scanning ion-selected electrode technique and PTS tracer confirmed that ABA-promoted deposition of CSs and SL significantly reduced Cd entrance into root stele. Therefore, maintenance of low ABA levels in HE minimized deposition of apoplastic barriers and allowed maximization of Cd uptake via apoplastic pathway.

Formation of a subero-lignified apical deposit in root tip of radish (Raphanus sativus) as a response to copper stress

BACKGROUND AND AIMS

Heavy metals induce changes in root metabolism and physiology, which can lead to a complex remodelling of the root system. The final morphological responses of radish (Raphanus sativus) roots exposed to toxic concentrations of the heavy metal (Cu) include root growth inhibition, differentiation of xylem vessels close to the root tip, enhanced suberin lamellae deposition and enhanced lateral root production. Recently, we have found that such changes in root morphology and anatomy are coupled to the formation of a subero-lignified apical deposit (SLAD) very close to the root tip.

METHODS

To clarify the details of the formation of a SLAD in the root tip, we conducted experiments with radish roots exposed to a high Cu concentration (60 µm). Histochemical analysis of lignin and suberin as well as analysis of spatial-temporal characteristics of SLAD formation were performed by bright-field, fluorescence and confocal microscopy.

KEY RESULTS

This unique structure, not longer than 100 µm, consists of modified cell walls of the central cylinder that are encircled by a short cylinder of prematurely suberized endodermal cells. A SLAD starts to form, in both primary and lateral roots, after cessation of root elongation, and it is coupled with xylem differentiation and root branching close to the root apex. We noticed that deposition of phenolic substances into a SLAD, mainly suberin in the endodermis, is spatially separated from suberization or lignification in basally located endodermis.

CONCLUSIONS

Although the main reason for formation of a SLAD is elusive, we suggest that it is a part of stress-induced responses which relate to decreased root growth or permeability in heavy metal stress.

Root hair abundance impacts cadmium accumulation in Arabidopsis thaliana shoots

BACKGROUND AND AIMS

Root hairs increase the contact area of roots with soil and thereby enhance the capacity for solute uptake. The strict hair/non-hair pattern of Arabidopsis thaliana can change with nutrient deficiency or exposure to toxic elements, which modify root hair density. The effects of root hair density on cadmium (Cd) accumulation in shoots of arabidopsis genotypes with altered root hair development and patterning were studied.

METHODS

Arabidopsis mutants that are unable to develop root hairs (rhd6-1 and cpc/try) or produce hairy roots (wer/myb23) were compared with the ecotype Columbia (Col-0). Plants were cultivated on nutrient agar for 2 weeks with or without Cd. Cadmium was applied as Cd(NO3)2 at two concentrations, 10 and 100 µm. Shoot biomass, root characteristics (primary root length, lateral root number, lateral root length and root hair density) and Cd concentrations in shoots were assessed. Anatomical features (suberization of the endodermis and development of the xylem) that might influence Cd uptake and translocation were also examined.

KEY RESULTS

Cadmium inhibited plant growth and reduced root length and the number of lateral roots and root hairs per plant. Suberin lamellae in the root endodermis and xylem differentiation developed closer to the root apex in plants exposed to 100 µm Cd. The latter effect was genotype dependent. Shoot Cd accumulation was correlated with root hair abundance when plants were grown in the presence of 10 µm Cd, but not when grown in the presence of 100 µm Cd, in which treatment the development of suberin lamellae closer to the root tip appeared to restrict Cd accumulation in shoots.

CONCLUSIONS

Root hair density can have a large effect on Cd accumulation in shoots, suggesting that the symplasmic pathway might play a significant role in the uptake and accumulation of this toxic element.

Formation of silica aggregates in sorghum root endodermis is predetermined by cell wall architecture and development

Background and Aims

Deposition of silica in plant cell walls improves their mechanical properties and helps plants to withstand various stress conditions. Its mechanism is still not understood and silica-cell wall interactions are elusive. The objective of this study was to investigate the effect of silica deposition on the development and structure of sorghum root endodermis and to identify the cell wall components involved in silicification.

Methods

Sorghum bicolor seedlings were grown hydroponically with (Si+) or without (Si-) silicon supplementation. Primary roots were used to investigate the transcription of silicon transporters by quantitative RT-PCR. Silica aggregation was induced also under in vitro conditions in detached root segments. The development and architecture of endodermal cell walls were analysed by histochemistry, microscopy and Raman spectroscopy. Water retention capability was compared between silicified and non-silicified roots. Raman spectroscopy analyses of isolated silica aggregates were also carried out.

Key Results

Active uptake of silicic acid is provided at the root apex, where silicon transporters Lsi1 and Lsi2 are expressed. The locations of silica aggregation are established during the development of tertiary endodermal cell walls, even in the absence of silicon. Silica aggregation takes place in non-lignified spots in the endodermal cell walls, which progressively accumulate silicic acid, and its condensation initiates at arabinoxylan-ferulic acid complexes. Silicification does not support root water retention capability; however, it decreases root growth inhibition imposed by desiccation.

Conclusion

A model is proposed in which the formation of silica aggregates in sorghum roots is predetermined by a modified cell wall architecture and takes place as governed by endodermal development. The interaction with silica is provided by arabinoxylan-ferulic acid complexes and interferes with further deposition of lignin. Due to contrasting hydrophobicity, silicification and lignification do not represent functionally equivalent modifications of plant cell walls.

Novel 9 amino acid in-frame deletion in the NTRK1 tyrosine kinase domain in a patient with congenital insensitivity to pain with anhydrosis

Schematic presentation of NTRK1 protein structure. Variants identified in this study are shown in red and previously reported variants associated with CIPA are shown in black (LRM, leucine rich motif; Ig, immunoglobulin-like domain; TM, transmembrane domain; TK, tyrosine kinase domain).

Caregiver's perception of epilepsy treatment, quality of life and comorbidities in an international cohort of CDKL5 patients

OBJECTIVE

CDKL5 is a genetic condition associated with drug-resistant epilepsy and intellectual disability. There is limited information on its natural history. We investigated the natural history, complications, and the effectiveness of current treatment strategies.

METHODS

This study was conducted in conjunction with the CDKL5-UK Charity, with patients recruited from the USA and Europe. Online questionnaires were completed by parents/carers and included information relating to demographics, growth, development, epilepsy, comorbid conditions, and efficacy and side effects of antiepileptic treatments.

RESULTS

Thirty-nine of the 44 patients were female. Median age was five years (range five months to 31 years), and all had a history of epilepsy. All patients had developmental delay, with 4/21 able to run and 4/22 able to climb. Gastrointestinal problems were reported in 31/43. Cardiac arrhythmia was seen in 11/29. Over one-quarter of the patients had tried ten or more antiepileptic medications. Vigabatrin was reportedly the most effective AED (antiepileptic drug) in 12/23; clobazam (most effective in 6/14); sodium valproate (most effective in 5/27), and levetiracetam (most effective in 3/27). VNS (Vagal Nerve Stimulator) was reported to be effective in 9/12. One year after VNS insertion, 9/12 reported improved (QoL), and there were improvements in mood, school achievement and concentration in (9/11). The ketogenic diet was considered effective and to have improved QoL in (12/23).

CONCLUSION

Vigabatrin appears to be more effective than other AEDs. VNS and ketogenic diet are also relatively effective. Gastrointestinal and cardiovascular system complications are common. The results may help to guide management of epilepsy in CDKL5. It highlights a possible link between CDKL5 and potentially treatable life-threatening complications such as cardiac arrhythmia. More research in this area may help us develop a more systematic approach to treating these patients. HIPPOKRATIA 2017, 21(3): 130-135.

Expression of Genes for Si Uptake, Accumulation, and Correlation of Si with Other Elements in Ionome of Maize Kernel

The mineral composition of cells, tissues, and organs is decisive for the functioning of the organisms, and is at the same time an indicator for understanding of physiological processes. We measured the composition of the ionome in the different tissues of maize kernels by element microanalysis, with special emphasis on silicon (Si). We therefore also measured the expression levels of the Si transporter genes ZmLsi1, ZmLsi2 and ZmLsi6, responsible for Si uptake and accumulation. Two weeks after pollination ZmLsi1 and ZmLsi6 genes were expressed, and expression continued until the final developmental stage of the kernels, while ZmLsi2 was not expressed. These results suggest that exclusively ZmLsi1 and ZmLsi6 are responsible for Si transport in various stages of kernel development. Expression level of ZmLsi genes was consistent with Si accumulation within kernel tissues. Silicon was mainly accumulated in pericarp and embryo proper and the lowest Si content was detected in soft endosperm and the scutellum. Correlation linkages between the distribution of Si and some other elements (macroelements Mg, P, S, N, P, and Ca and microelements Cl, Zn, and Fe) were found. The relation of Si with Mg was detected in all kernel tissues. The Si linkage with other elements was rather specific and found only in certain kernel tissues of maize. These relations may have effect on nutrient uptake and accumulation.

The apoplasmic pathway via the root apex and lateral roots contributes to Cd hyperaccumulation in the hyperaccumulator Sedum alfredii

Although the significance of apoplasmic barriers in roots with regards to the uptake of toxic elements is generally known, the contribution of apoplasmic bypasses (ABs) to cadmium (Cd) hyperaccumulation is little understood. Here, we employed a combination of stable isotopic tracer techniques, an ABs tracer, hydraulic measurements, suberin lamellae staining, metabolic inhibitors, and antitranspirants to investigate and quantify the impact of the ABs on translocation of Cd to the xylem in roots of a hyperaccumulating (H) ecotype and a non-hyperaccumulating (NH) ecotype of Sedum alfredii. In the H ecotype, the Cd content in the xylem sap was proportional to hydrostatic pressure, which was attributed to pressure-driven flow via the ABs. The contribution of the ABs to Cd transportation to the xylem was dependent on the Cd concentration applied to the H ecotype (up to 37% at the highest concentration used). Cd-treated H ecotype roots showed significantly higher hydraulic conductance compared with the NH ecotype (76 vs 52 × 10–8 m s–1MPa–1), which is in accordance with less extensive suberization due to reduced expression of suberin-related genes. The main entry sites of apoplasmically transported Cd were localized in the root apexes and lateral roots of the H ecotype, where suberin lamellae were not well developed. These findings highlight the significance of the apoplasmic bypass in Cd hyperaccumulation in hyperaccumulating ecotypes of S. alfredii.

Asymmetrical development of root endodermis and exodermis in reaction to abiotic stresses

Background and Aims In the present study, we show that development of endodermis and exodermis is sensitively regulated by water accessibility. As cadmium (Cd) is known to induce xeromorphic effects in plants, maize roots were exposed also to Cd to understand the developmental process of suberin lamella deposition in response to a local Cd source. Methods In a first experiment, maize roots were cultivated in vitro and unilaterally exposed to water-containing medium from one side and to air from the other. In a second experiment, the roots were placed between two agar medium layers with a strip of Cd-containing medium attached locally and unilaterally to the root surface. Key Results The development of suberin lamella (the second stage of exodermal and endodermal development) started asymmetrically, preferentially closer to the root tip on the side exposed to the air. In the root contact with Cd in a spatially limited area exposed to one side of the root, suberin lamella was preferentially developed in the contact region and additionally along the whole length of the root basipetally from the contact area. However, the development was unilateral and asymmetrical, facing the treated side. The same pattern occurred irrespective of the distance of Cd application from the root apex. Conclusions These developmental characteristics indicate a sensitive response of root endodermis and exodermis in the protection of vascular tissues against abiotic stresses.

[Pain therapy in in-patients with cancer. Effects of a manual-based approach as guideline for pain-consulting service at a university hospital]

BACKGROUND

Appropriate medication is an important and substantial part in the therapy of tumor-induced pain.

OBJECTIVE

The objective of this study was to investigate the efficiency of anaesthesiology-based consultant service characterizing the quality of this type of treatment in daily clinical practice of a university hospital, i. e., in the patient profile of a tertiary center (study design: systematic clinical, unicenter observational study reflecting clinical practice and study-based control of therapeutic care quality).

METHODS

In the course of consulting function with regard to pain care on the single wards a considerable portion of cancer patients are recieving drugs. For most patients such care comprises several consultations and subsequently initiated treatment modifications. The consulting function ends if the patients feel free of pain or report a substantial improvement. From 1/1/2010 to 12/31/2012 detailed information on the drug therapy applied prior to, during and after the consultation was prospectively documented.This data was retrospectively evaluated as "pre-vs.-post" comparison (Chi-squared test, Fisher's exact test and McNemar's test), in particular, focussing on the quality of pain medication using the WHO index as well as pain intensity obtained by means of the visual analogue scale (VAS).

RESULTS

In total, 375 in-patients were treated. The modified pain medication by the anesthesiological consultant service led to a significant increase (p < 0.001; Wilcoxon's test) in the mean WHO index from 6.37 (SD, 1.83) to 8.43 (SD, 1.47). Furthermore, a reduction of VAS from 5.00 (SD, 2.39) to 2.64 (SD, 1.64) was noted (p < 0.001; Wilcoxon's test).

CONCLUSION

The consequent application of established guidelines (according to WHO scheme) and the WHO index leads to a qualitative and measurable improvement of drug therapy for cancer-related pain.

Antimony (SbIII) reduces growth, declines photosynthesis, and modifies leaf tissue anatomy in sunflower (Helianthus annuus L.)

The role of antimony (Sb)--a non-essential trace metalloid--in physiological processes running in crops is still poorly understood. Present paper describes the effect of Sb tartrate (SbIII) on growth, Sb uptake, photosynthesis, photosynthetic pigments, and leaf tissue organization in young sunflower plants grown in hydroponics. We found that growth of below- and aboveground part was reduced with increasing concentration of Sb in the medium. Although Sb was mostly taken up by sunflower roots and only small part (1-2%) was translocated to the shoots, decline in photosynthesis, transpiration, and decreased content of photosynthetic pigments were observed. This indicates that despite relatively low mobility of Sb in root-shoot system, Sb in shoot noticeably modifies physiological status and reduced plant growth. Additionally, leaf anatomical changes indicated that Sb reduced the size of intercellular spaces and made leaf tissue more compact.

Silicon alleviates cadmium toxicity by enhanced photosynthetic rate and modified bundle sheath's cell chloroplasts ultrastructure in maize

Silicon was shown to alleviate the negative effects of various biotic and abiotic stresses on plant growth. Although the positive role of Si on toxic and heavy metal Cd has been already described, the mechanisms have been explained only partially and still remain unclear. In the present study we investigated the effect of Si on photosynthetic-related processes in maize exposed to two different levels of Cd via measurements of net photosynthetic rate (AN), chlorophyll a fluorescence and pigment analysis, as well as studies of leaf tissue anatomy and cell ultrastructure using bright-field and transmission electron microscopy. We found that Si actively alleviated the toxic syndromes of Cd by increasing AN, effective photochemical quantum yield of photosystem II (ϕPSII) and content of assimilation pigments, although did not decrease the concentration of Cd in leaf tissues. Cadmium did not affect the leaf anatomy and ultrastructure of leaf mesophyll's cell chloroplasts; however, Cd negatively affected thylakoid formation in chloroplasts of bundle sheath cells, and this was alleviated by Si. Improved thylakoid formation in bundle sheath's cell chloroplasts may contribute to Si-induced enhancement of photosynthesis and related increase in biomass production in C4 plant maize.

Evaluation of endourological tools to improve the diagnosis and therapy of ureteral tumors – from model development to clinical application

Adequate diagnosis of upper urinary tract (UUT) tumors is essential for successful local treatment. Organsparing approaches are technically difficult and require consistent further development. Appropriate models for investigating new diagnostic and therapeutic methods are not yet available. This study demonstrates the incorporation of a fresh sample model into five different test levels (I-V) for improving the diagnosis and therapy of ureteral tumors. In these test levels, new diagnostic and ablation techniques are evaluated for feasibility, application safety, efficacy and accuracy. An assessment of their suitability for broad preclinical and clinical application also took economic aspects into account.

Cadmium translocation by contractile roots differs from that in regular, non-contractile roots

BACKGROUND AND AIMS

Contractile roots are known and studied mainly in connection with the process of shrinkage of their basal parts, which acts to pull the shoot of the plant deeper into the ground. Previous studies have shown that the specific structure of these roots results in more intensive water uptake at the base, which is in contrast to regular root types. The purpose of this study was to find out whether the basal parts of contractile roots are also more active in translocation of cadmium to the shoot.

METHODS

Plants of the South African ornamental species Tritonia gladiolaris were cultivated in vitro for 2 months, at which point they possessed well-developed contractile roots. They were then transferred to Petri dishes with horizontally separated compartments of agar containing 50 µmol Cd(NO3)2 in the region of the root base or the root apex. Seedlings of 4-d-old maize (Zea mays) plants, which do not possess contractile roots, were also transferred to similar Petri dishes. The concentrations of Cd in the leaves of the plants were compared after 10 d of cultivation. Anatomical analyses of Tritonia roots were performed using appropriately stained freehand cross-sections.

KEY RESULTS

The process of contraction required specific anatomical adaptation of the root base in Tritonia, with less lignified and less suberized tissues in comparison with the subapical part of the root. These unusual developmental characteristics were accompanied by more intensive translocation of Cd ions from the basal part of contractile roots to the leaves than from the apical-subapical root parts. The opposite effects were seen in the non-contractile roots of maize, with higher uptake and transport by the apical parts of the root and lower uptake and transport by the basal part.

CONCLUSIONS

The specific characteristics of contractile roots may have a significant impact on the uptake of ions, including toxic metals from the soil surface layers. This may be important for plant nutrition, for example in the uptake of nutrients from upper soil layers, which are richer in humus in otherwise nutrient-poor soils, and also has implications for the uptake of surface-soil pollutants.

Ionome and expression level of Si transporter genes (Lsi1, Lsi2, and Lsi6) affected by Zn and Si interaction in maize

Zinc (Zn) is an essential microelement involved in various plant physiological processes. However, in excess, Zn becomes toxic and represents serious problem for plants resulting in Zn toxicity symptoms and decreasing biomass production. The effect of high Zn and its combination with silicon (Si) on ionome and expression level of ZmLsi genes was investigated in maize (Zea mays, L; hybrid Novania). Plants were cultivated hydroponically in different treatments: control (C), Zn (800 μM ZnSO4 · 7H2O), Si5 (5 mM of sodium silicate solution), and Si5 + Zn (combination of Zn and Si treatments). Growth of plants cultivated for 10 days was significantly inhibited in the presence of high Zn concentration and also by Zn and Si interaction in plants. Based on principal component analysis (PCA) and mineral element concentration in tissues, root ionome was significantly altered in both Zn and Si5 + Zn treatments in comparison to control. Mineral elements Mn, Fe, Ca, P, Mg, Ni, Co, and K significantly decreased, and Se increased in Zn and Si5 + Zn treatments. Shoot ionome was less affected than root ionome. Concentration of shoot Cu, Mn, and P decreased, and Mo increased in Zn and Si5 + Zn treatments. The PCA also revealed that the responsibility for ionome changes is mainly due to Zn exposure and also, but less, by Si application to Zn stressed plants. Expression level of Lsi1 and Lsi2 genes for the Si influx and efflux transporters was downregulated in roots after Si supply and even more downregulated by Zinc alone and also by Zn and Si interaction. Expression level of shoot Lsi6 gene was differently regulated in the first and second leaf. These results indicate negative effect of high Zn alone and also in interaction with Si on Lsi gene expression level and together with ionomic data, it was shown that homeostatic network of mineral elements was disrupted and caused negative alterations in mineral nutrition of young maize plants.

RNA sequencing of Populus x canadensis roots identifies key molecular mechanisms underlying physiological adaption to excess zinc

Populus x canadensis clone I-214 exhibits a general indicator phenotype in response to excess Zn, and a higher metal uptake in roots than in shoots with a reduced translocation to aerial parts under hydroponic conditions. This physiological adaptation seems mainly regulated by roots, although the molecular mechanisms that underlie these processes are still poorly understood. Here, differential expression analysis using RNA-sequencing technology was used to identify the molecular mechanisms involved in the response to excess Zn in root. In order to maximize specificity of detection of differentially expressed (DE) genes, we consider the intersection of genes identified by three distinct statistical approaches (61 up- and 19 down-regulated) and validate them by RT-qPCR, yielding an agreement of 93% between the two experimental techniques. Gene Ontology (GO) terms related to oxidation-reduction processes, transport and cellular iron ion homeostasis were enriched among DE genes, highlighting the importance of metal homeostasis in adaptation to excess Zn by P. x canadensis clone I-214. We identified the up-regulation of two Populus metal transporters (ZIP2 and NRAMP1) probably involved in metal uptake, and the down-regulation of a NAS4 gene involved in metal translocation. We identified also four Fe-homeostasis transcription factors (two bHLH38 genes, FIT and BTS) that were differentially expressed, probably for reducing Zn-induced Fe-deficiency. In particular, we suggest that the down-regulation of FIT transcription factor could be a mechanism to cope with Zn-induced Fe-deficiency in Populus. These results provide insight into the molecular mechanisms involved in adaption to excess Zn in Populus spp., but could also constitute a starting point for the identification and characterization of molecular markers or biotechnological targets for possible improvement of phytoremediation performances of poplar trees.

New method for visualization of silica phytoliths in Sorghum bicolor roots by fluorescence microscopy revealed silicate concentration-dependent phytolith formation

Silica phytoliths are microscopic structures of amorphous hydrated silica (SiO2 · nH2O) formed by specialized plant cells. Besides their biological roles, physical, chemical, and structural properties of biogenic silica offer a wide spectrum of applications in many fields of industry and technology. Therefore, processes involved in their formation recently become a very interesting topic to study. However, optical transparency and microscopic sizes of silica phytoliths do not allow their visualization and localization by classical light microscopy methods. Their observation thus requires phytolith isolation, technically difficult or lengthy sample preparation procedures, or a work with toxic chemicals. In this paper we are proposing a novel method for visualization of silica phytoliths in Sorghum bicolor root endodermal cells by fluorescence microscopy using alkali mounting solution (pH 12). This method offers an easy and quick preparation of the samples and high contrast imaging. Based on our results we can assume that the proposed fluorescent method for silica phytolith investigation allows observation of multiple samples in relatively short time period and thus might be applicable also for high-throughput screenings. Using this method we found out that after a 3-day cultivation of sorghum plants the minimal needed concentration of sodium silicate, limiting the formation of silica phytoliths in the root endodermis, was 25 µmol dm(-3). The positive correlation of sodium silicate concentration in the substrate with the phytolith diameter was also observed.