High Tissue Concentrations Research Articles

Quantification of spatial metal accumulation patterns in Noccaea caerulescens by X-ray fluorescence image processing for genetic studies

BackgroundHyperaccumulation of trace elements is a rare trait among plants which is being investigated to advance our understanding of the regulation of metal accumulation and applications in phytotechnologies. Noccaea caerulescens (Brassicaceae) is an intensively studied hyperaccumulator model plant capable of attaining extremely high tissue concentrations of zinc and nickel with substantial genetic variation at the population-level. Micro-X-ray Fluorescence spectroscopy (µXRF) mapping is a sensitive high-resolution technique to obtain information of the spatial distribution of the plant metallome in hydrated samples. We used laboratory-based µXRF to characterize a collection of 86 genetically diverse Noccaea caerulescens accessions from across Europe. We developed an image-processing method to segment different plant substructures in the µXRF images. We introduced the concentration quotient (CQ) to quantify spatial patterns of metal accumulation and linked that to genetic variation.ResultsImage processing resulted in automated segmentation of µXRF plant images into petiole, leaf margin, leaf interveinal and leaf vasculature substructures. The harmonic means of recall and precision (F1 score) were 0.79, 0.80, 0.67, and 0.68, respectively. Spatial metal accumulation as determined by CQ is highly heritable in Noccaea caerulescens for all substructures, with broad-sense heritability (H2) ranging from 76 to 92%, and correlates only weakly with other heritable traits. Insertion of noise into the image segmentation algorithm barely decreases heritability scores of CQ for the segmented substructures, illustrating the robustness of the trait and the quantification method. Very low heritability was found for CQ if randomly generated substructures were compared, validating the approach.ConclusionsA strategy for segmenting µXRF images of Noccaea caerulescens is proposed and the concentration quotient is developed to provide a quantitative measure of metal accumulation pattern, which can be used to determine genetic variation for such pattern. The metric is robust to segmentation error and provides reliable H2 estimates. This strategy provides an avenue for quantifying XRF data for analysis of the genetics of metal distribution patterns in plants and the subsequent discovery of new genes that regulate metal homeostasis and sequestration in plants.

Effects of modified atmosphere and sugar immersion on physiology and quality of fresh-cut 'Braeburn' apples

Fresh-cut fruits are highly perishable and show a short shelf life. Therefore, storage in sugar syrup is commercially used to delay undesirable metabolic changes and to prevent browning. Investigations on the effects of syrup application on volatile organic compounds (VOCs), important for the consumers’ acceptance, are rare. It is, however, known that low O2 availability, as found in fruit slices after immersion, may result in the formation of unwanted off-odour. This negatively affects the sensory quality of fresh-cuts. In the present study, fresh-cut 'Braeburn' apples were comparatively stored in air, in three modified atmospheres (O2: 10, 5 and approx. 0 %; CO2: 10, 15 and 20 %) or in sugar syrup (20 % sugar content). Relevant quality, physiological and microbiological parameters were evaluated on days 3, 6 and 10 of storage. Particular focus was laid on the evaluation of VOC emission to indicate biosynthetic responses that affect aroma-relevant VOCs. Atmospheric storage of apple slices, among others, increased the emission of ethyl acetate, which may create off-odour and negatively affects the customers’ acceptance. In contrast, syrup-immersion of apple slices resulted in a pronounced loss of aroma but prevented the occurrence of off-odour. The results indicated metabolic changes, which were independent of O2 availability. High CO2 or VOCs concentrations in the fruit tissue may inhibit esterification or may induce a feedback inhibition of VOC synthesis.

Evaluating the potential bioextractive capacity of South Florida native macroalgae Agardhiella subulata for use in integrated multi-trophic aquaculture (IMTA)

With the expansion of marine aquaculture throughout the world comes a need for solutions to improve the economic viability and environmental sustainability of farming operations. Integrated multi-trophic aquaculture (IMTA) has been identified as a promising method of farming that typically combines multiple cultured species in connected systems in an effort to decrease the concentration of nutrients expelled as waste products from intensive finfish culture while also increasing commercial profits via subsequent extractive biomass production. This study examined the effectiveness of South Florida native red macroalgal species Agardhiella subulata for use as a productive, nutrient-extracting species for IMTA in the Atlantic, Gulf of Mexico, and Caribbean regions. When cultured in a pilot-scale, land-based IMTA system for replicated 15 day trials with American red snapper, Lutjanus campechanus, A. subulata grew up to 14.4% d−1 and significantly decreased the concentration of all measured dissolved inorganic nutrients in the effluent water. The average percent (% ± SE) removal of nutrients were: 68.8 ± 4.8 ammonia, 94.5 ± 1.3 nitrate, 96.6 ± 2.0 nitrite, and 93.2 ± 3.1 phosphate from primary culture effluents. Further evidence of A. subulata fitness for commercial IMTA practices is shown through significantly high bulk nitrogen tissue concentration of experimental (nutrient-enriched) compared to control (un-enriched) groups. Results of this study demonstrate the efficient growth and nutrient removal capabilities of A. subulata when used in IMTA applications with marine finfish production in warm water environments, as may be encountered in marine aquaculture projects in the Atlantic, Gulf of Mexico and Caribbean regions.

Bioaccumulation of trace metals in the ocypodid burrowing crab, Paratylodiplax blephariskios, in Richards Bay Harbour, South Africa

Bioaccumulation of metals in an endemic ocypodid burrowing mud crab, Paratylodiplax blephariskios, was investigated in contaminated mudflats of the subtropical Richards Bay Harbour (RBH), South Africa. Following sampling of water, sediment and mud crabs from three sites (Bhizolo, Mzingazi and Richards Bay Coal Terminal) in RBH during 2016/2017, tissue and sediment samples were oven dried for 48 hours, weighed and digested in an advanced microwave digester. Samples were then analyzed in triplicate for Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES). Highest tissue concentrations of Co, Cu, Mn, Ni, Pb and Zn were recorded at Bhizolo. High Biota Sediment Accumulation Factor (BSAF) values for Cd, Cu, Mn, Ni and Zn at all sites confirmed that crabs bioaccumulated these metals. The high Cr concentration in sediment (Bhizolo: 104 ± 18.2 µg g−1; Richards Bay Coal Terminal (RBCT): 104 ± 29.2 µg g−1; Mzingazi: 94.1 ± 38.7 µg g−1) was not reflected in the biota-sediment accumulation factor (BSAF) value, suggesting low bioavailability of Cr. High BSAF values for Cd, Cu, Mn, Ni and Zn suggest that the threshold of regulation in P. blephariskios was exceeded, resulting in net bioaccumulation.

Hyperthermic Intraperitoneal Chemotherapy: A Critical Review

Simple SummaryPatients with cancer of the digestive system or ovarian cancer are at risk of developing peritoneal metastases (PM). In some patients with PM, surgery followed by intraperitoneal (IP) chemotherapy has emerged as a valid treatment option. The addition of hyperthermia is thought to further enhance the efficacy of IP chemotherapy. However, the results of recent clinical trials in large bowel cancer have put into question the use of hyperthermic intraperitoneal chemotherapy (HIPEC). Here, we review the rationale and current results of HIPEC for PM and propose a roadmap to further progress.With increasing awareness amongst physicians and improved radiological imaging techniques, the peritoneal cavity is increasingly recognized as an important metastatic site in various malignancies. Prognosis of these patients is usually poor as traditional treatment including surgical resection or systemic treatment is relatively ineffective. Intraperitoneal delivery of chemotherapeutic agents is thought to be an attractive alternative as this results in high tumor tissue concentrations with limited systemic exposure. The addition of hyperthermia aims to potentiate the anti-tumor effects of chemotherapy, resulting in the concept of heated intraperitoneal chemotherapy (HIPEC) for the treatment of peritoneal metastases as it was developed about 3 decades ago. With increasing experience, HIPEC has become a safe and accepted treatment offered in many centers around the world. However, standardization of the technique has been poor and results from clinical trials have been equivocal. As a result, the true value of HIPEC in the treatment of peritoneal metastases remains a matter of debate. The current review aims to provide a critical overview of the theoretical concept and preclinical and clinical study results, to outline areas of persisting uncertainty, and to propose a framework to better define the role of HIPEC in the treatment of peritoneal malignancies.

Inverse electron demand Diels-Alder click chemistry for pretargeted PET imaging and radioimmunotherapy.

Radiolabeled antibodies have shown promise as tools for both the nuclear imaging and endoradiotherapy of cancer, but the protracted circulation time of radioimmunoconjugates can lead to high radiation doses to healthy tissues. To circumvent this issue, we have developed an approach to positron emission tomography (PET) imaging and radioimmunotherapy (RIT) predicated on radiolabeling the antibody after it has reached its target within the body. This in vivo pretargeting strategy is based on the rapid and bio-orthogonal inverse electron demand Diels-Alder reaction between tetrazine (Tz) and trans-cyclooctene (TCO). Pretargeted PET imaging and RIT using TCO-modified antibodies in conjunction with Tz-bearing radioligands produce high activity concentrations in target tissues as well as reduced radiation doses to healthy organs compared to directly labeled radioimmunoconjugates. Herein, we describe how to prepare a TCO-modified antibody (humanized A33-TCO) as well as how to synthesize two Tz-bearing radioligands: one labeled with the positron-emitting radiometal copper-64 ([64Cu]Cu-SarAr-Tz) and one labeled with the β-emitting radiolanthanide lutetium-177 ([177Lu]Lu-DOTA-PEG7-Tz). We also provide a detailed description of pretargeted PET and pretargeted RIT experiments in a murine model of human colorectal carcinoma. Proper training in both radiation safety and the handling of laboratory mice is required for the successful execution of this protocol.

Tocopherols and Tocotrienols-Bioactive Dietary Compounds; What Is Certain, What Is Doubt?

Tocopherols and tocotrienols are natural compounds of plant origin, available in the nature. They are supplied in various amounts in a diet, mainly from vegetable oils, some oilseeds, and nuts. The main forms in the diet are α- and γ-tocopherol, due to the highest content in food products. Nevertheless, α-tocopherol is the main form of vitamin E with the highest tissue concentration. The α- forms of both tocopherols and tocotrienols are considered as the most metabolically active. Currently, research results indicate also a greater antioxidant potential of tocotrienols than tocopherols. Moreover, the biological role of vitamin E metabolites have received increasing interest. The aim of this review is to update the knowledge of tocopherol and tocotrienol bioactivity, with a particular focus on their bioavailability, distribution, and metabolism determinants in humans. Almost one hundred years after the start of research on α-tocopherol, its biological properties are still under investigation. For several decades, researchers’ interest in the biological importance of other forms of vitamin E has also been growing. Some of the functions, for instance the antioxidant functions of α- and γ-tocopherols, have been confirmed in humans, while others, such as the relationship with metabolic disorders, are still under investigation. Some studies, which analyzed the biological role and mechanisms of tocopherols and tocotrienols over the past few years described new and even unexpected cellular and molecular properties that will be the subject of future research.

Electrochemical Competitive Magneto-Immunoassay for Determination of Neurotoxin Domoic Acid

Domoic acid is heterocyclic amino acid neurotoxin and the principal toxin associated with amnesic shellfish poisoning (ASP) produced by certain species of marine diatom. It can bio accumulated at high concentrations in the shellfish tissues when the toxic phytoplankton is high in concentration in the surrounding waters. Ingestion of domoic acid contaminated shellfish leads to ASP, which is characterized by both gastrointestinal and neurological symptoms, including severe headache, seizures, tremors, and either temporary or permanent memory loss.Herein, the detection of domoic acid is carried out through an enzymatic immunoassay that uses magnetic beads as support of the immunoreaction and screen-printed electrodes as suitable detector of the enzymatic product. Thereby, the immunological reaction is performed in solution, where the domoic acid, antigen, domoic acid labeled with horseradish peroxidase are incubated with the rabbit IgG antibody against domoic acid. Subsequently, the antibody-antigen complex is captured by the anti-rabbit IgG modified magnetic beads. Then, the magnetic beads are deposited onto the electrode surface with the help of the magnet placed under the screen printed electrode. Finally, the analytical signal is obtained by amperometric detection of the product enzymatically generated from the mixture of H2O2and 3,3,5,5-tetramethylbenzidine (TMB).The use of magnetic beads provides the capability to preconcentrate the sample and avoid the poisoning of the electrode surface through non specific absorptions.The experimental conditions of the magneto-immunological assay has been optimized and a calibration curve has been obtained between 0-2 ng/mL domoic acid, being able to detect down to 100 pg/mL domoic acid. Acknowledgements This work has been carried out in the framework of FLAshMoB project. This project is funded by the MarTERA partners; Italian Ministry of Education, Universities and Research (MIUR), French National Research Agency (ANR) and Spanish Centre for the Development of Industrial Technology (CDTI) and co-funded by the European Union.

Assessment of the Streptomyces-plant system to mitigate the impact of Cr(VI) and lindane in experimental soils.

Phytoremediation techniques have been proposed as ecological methods to clean up contaminated sites. This study is aimed to evaluate the effect of the Streptomyces sp. Waksman & Henrici and Zea mays L. plant system on the dissipation of Cr(VI) and/or lindane from a co-contaminated soil, being 2mgkg-1 of lindane and 150mgkg-1 of chromium used. Lindane dissipation was improved in the presence of plant-microorganism association; however, Cr(VI) removal was higher when plants or the microorganism were separately. In co-contaminated systems, chromium content in plant tissues was lower than metal content in plants grown only with Cr(VI), suggesting that lindane could interfere with metal accumulation in the plant. The high malondialdehyde (MDA) concentration detected in non-inoculated plants grown with chromium could be consequence of high metal concentration in plant tissues. Interestingly, plants inoculated with Streptomyces sp. Z38 growing with Cr(VI) showed decrease in MDA concentration, indicating that the bacterium could activate defense mechanisms in the plant. Also, inoculated plants showed the highest value of superoxide dismutase activity. Lettuce plants used as bioindicators grew better in biologically treated soils compared with lettuce grown on non-treated soil. The results presented in this work provide the basis that will allow the optimization of future trials on a larger scale.

Mercury contamination at Vembanad Lake and near-shore regions in the southwest coast of India

Mercury (Hg) contamination in aquatic systems is a universal concern because of its persistence, bioaccumulation, toxicity, and trans-boundary nature. The current study focuses on monitoring the fate and transport of Hg in aquatic matrices such as water, interstitial water, sediment and fish in a tropical coastal ecosystem. The cold vapour atomic fluorescence spectrometer was used for the Hg analysis. The study assessed the fractionation of Hg and its methylation potential in sediments. The high Hg concentration in fish tissues showed the ineffectiveness of biogeochemical control over the methyl Hg mobility and bioavailability through the food web. Research results indicate that the accumulation potential of Hg subsequently increases along the food chain. The conducive physico-chemical environment at the sediment–water interface supports chemical transformations/transport of Hg from one matrix to the next. The fate of Hg in the lake has also been discussed based on the data generated.

Mercury offloading in gametes and potential adverse effects of high mercury concentrations in blood and tissues of Atlantic Goliath Grouper Epinephelus itajara in the southeastern United States.

Mercury (Hg) is a ubiquitous and non-essential heavy metal that is highly toxic to aquatic organisms. Few studies examine Hg and its effects on wild fish populations. Here, we investigated the potential effects of Hg exposure on a large and long-lived marine species of conservation concern, the vulnerable Atlantic Goliath Grouper Epinephelus itajara. Our objectives were (1) to measure Hg (methyl-Hg; and total Hg=combined methyl-Hg and inorganic-Hg) concentrations in whole blood (WB) and gametes (eggs and sperm); (2) to investigate the relationships between Hg concentrations in muscle and liver with WB and gametes; (3) to investigate the relationships between Hg concentrations in liver, muscle, and WB with hematological and plasma biochemical analytes; and (4) to investigate the relationship between liver Hg and pigmented macrophage aggregates in liver tissue sections. We found several lines of evidence for potential adverse effects on Goliath Grouper health and reproduction by high Hg concentrations in liver, muscle, WB, and gametes, including (1) Hg concentrations in all tissues and gametes were well above observable ranges of marine and freshwater fishes from experimental exposure studies; (2) gamete Hg concentrations were among the highest recorded in wild fishes, with seasonal patterns suggesting females offload significant amounts of Hg into their eggs during the spawning season; (3) Methyl-Hg was highest in muscle, followed by sperm, liver, eggs, and WB; (4) there were significant correlations between liver, muscle, and WB Hg concentrations with various blood analytes; (5) vitellogenin positively correlated with female liver methyl-Hg concentrations, and was abnormally high in males, suggesting direct endocrine effects; and (6) liver total Hg positively correlated with pigmented macrophage aggregate count and percent area. This work will help guide future research examining the potential adverse effects of Hg and its role as an additional stressor on wild fish populations.

Development and validation of a sensitive UHPLC-MS/MS method for the measurement of β-elemonic acid in rat plasma and tissues and its application to pharmacokinetics and tissue distribution study

β-Elemonic acid is one of the main active ingredients isolated from Boswellia carterii Birdw. which has been reported to exhibit potential anti-inflammatory and anti-cancer activities. There is few information about pharmacokinetics and tissue distribution of β-elemonic acid by now. In this study, an ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC-MS/MS) method has been developed and validated to determine β-elemonic acid in rat plasma and various tissues after intragastric administration. Oleanolic acid was chosen as an internal standard (IS) and the plasma/tissue samples were pretreated with one-step liquid–liquid extraction. Chromatographic separation was accomplished on Eclipse Plus C18 analytical column (2.1 × 50 mm, 1.8 μm) utilizing a gradient mobile phase system consisting of water (with 0.1% ammonia-solution) and acetonitrile. β-Elemonic acid and IS were detected and quantified using negative electrospray ionization in multiple reaction monitoring (MRM) mode with transitions of m/z 453.3 → 423.5 for β-elemonic acid and m/z 455.3 → 407.6 for IS. β-Elemonic acid showed good linearity over the investigated concentration range (r > 0.9934) in rat plasma and tissue sample. The method was successfully applied for determination of β-elemonic acid in bio-samples. A bimodal phenomenon appeared in the plasma concentration–time curve of the β-elemonic acid. The highest tissue concentrations were found in the intestine including jejunum, ileum and colon.

Phase 1 Randomized Placebo-Controlled Study in Healthy Adult Volunteers to Evaluate the Safety, Tolerability, and Pharmacokinetics of Orally Inhaled Aerosolized Hydroxychloroquine Sulfate – A Potential Treatment for COVID-19

The airways and lungs are the primary sites of SARS-CoV-2 entry, replication, and damage, so there is reason to administer drugs to these regions. Oral hydroxychloroquine (oHCQ) has produced mixed results in COVID-19, despite reported antiviral activity in vitro (EC50=0.72-119 μM). We tested the hypothesis that aerosolized HCQ sulfate (aHCQ) tolerably, safely, and rapidly achieves high respiratory tissue concentrations, while minimizing systemic toxicity. aHCQ was administered via Aerogen nebulizer (oral inhalation, nasal exhalation) to healthy volunteers in a Phase 1 study to assess tolerability, safety, and pharmacokinetics. 10 volunteers (age 55±13 years, 60% female) were randomized to Placebo (n=2), or aHCQ (20 mg, n=2; 50 mg, n=6); all completed the inhalation. 6/8 receiving aHCQ had adverse events (all mild; 75% transient dysgeusia, 25% dizziness). FEV1 and FVC were essentially unchanged from baseline after 15-360 minutes and 1 and 7 days. QT segments were minimally changed from baseline (maximum change 34 msec) after 1-6 hours, and 1 and 7 days; all were ≤455 msec. Pharmacokinetics of 50 mg: Area Under the Blood Curve 0-24 hours post-inhalation was 377±127 ng*hr/mL, <15% of that reported for oHCQ 200 mg; Pharmacokinetic modelling predicts initial epithelial lining fluid concentrations in excess of reported EC50s, and peak respiratory tissue concentrations of 0.5 mM, decreasing to 0.01 mM at 24 hours as HCQ slowly releases into blood. aHCQ was safe, well-tolerated, and appears to be sequestered in respiratory tissues. Administering aHCQ at a fraction of oral dosing may rapidly achieve respiratory tract concentrations sufficient to inhibit SARS-CoV-2.

Effects of methylmercury on the early life stages of an estuarine forage fish using two different dietary sources

Marine fish accumulate methylmercury (MeHg) to elevated concentrations, often higher than in freshwater systems. As a neurotoxic compound, high MeHg tissue concentrations could affect fish behavior which in turn could affect their populations. We examined the sublethal effects of MeHg on larvae of the Sheepshead minnow (Cyprinodon variegatus), an estuarine fish, using artificial or natural diets with varying MeHg concentrations (0–4.8 ppm). Larvae were fed control and MeHg-contaminated diets at low or normal (10% of their body mass) daily food rations from 7 to 29 days when they reached juvenile stage. Growth, respiration, swimming activity and prey capture ability were assessed. Food ration affected Hg toxicity in our study. Natural diets containing 3.2 ppm MeHg had no impacts on growth and swimming in fish that were fed normal food rations but depressed growth and swimming at low food rations. MeHg toxicity did not differ between artificial and natural foods, however fish accumulated more MeHg from the former. Artificial food containing 4.8 ppm MeHg only affected prey capture after 21 days of exposure. Sheepshead minnows, a forage fish species occupying a low trophic level in coastal waters, can be MeHg tolerant, especially when food is abundant, and can serve as an enriched Hg source for higher trophic level predators.

Safety and Pharmacokinetic Assessments of a Novel Ivermectin Nasal Spray Formulation in a Pig Model.

Recently published data indicates that high ivermectin (IVM) concentrations suppress in vitro SARS-CoV-2 replication. Nasal IVM spray administration may contribute to attaining high drug concentrations in nasopharyngeal tissue, a primary site of virus entrance/replication. The safety and pharmacokinetic performances of a novel IVM spray formulation were assessed in a pig model. Piglets received IVM either orally (0.2 mg/kg) or by one or two nasal spray doses. The overall safety, and histopathology of the IVM-spray application site tissues, were assessed. The IVM concentration profiles measured in plasma and respiratory tract tissues after the nasal spray were compared with those achieved after the oral administration. Animals tolerated well the nasal spray formulation. No local/systemic adverse events were observed. After nasal administration, the highest IVM concentrations were measured in nasopharyngeal and lung tissues. The nasal/oral IVM concentration ratios in nasopharyngeal and lung tissues markedly increased by repeating (12 h apart) the spray application. The fast attainment of high and persistent IVM concentrations in nasopharyngeal tissue is the main advantage of the nasal over the oral route. These original results support the undertaking of future clinical trials to evaluate the safety/efficacy of the nasal IVM spray application in the prevention and/or treatment of COVID-19.

More Levels of Complexity in the Control of Intestinal Inflammation

More Levels of Complexity in the Control of Intestinal Inflammation

Structural and physiological effects of chromium uptake in the seagrass Halophila stipulacea

This work aims to provide insight on the effects of chromium (Cr) uptake in seagrasses at environmentally relevant exposure concentrations; information on this issue can further increase the utility of marine angiosperms as indicators of trace metal contamination. Cr uptake kinetics, effects on physiological and structural cell traits, and the uptake-effects relationship in Halophila stipulacea leaves incubated in 0.01–10 mg L−1 (0.2–200 μM) of Cr (VI) were examined. An initial uptake was followed by a decrease at 0.01–0.5 mg L−1 (0.2–10 μM); at higher exposures, the fit of uptake data to a Michaelis-Menten-type equation was significant (p < 0.001). The mean tissue concentration over the exposure period, and the highest tissue concentration attained both increased as exposure concentration (Cw) increased from 0.05 to 10 mg L−1 (1 to 200 μM); uptake rate generally increased with Cw. Cytotoxic effects occurred even at 0.01 mg L−1 (0.2 μM). Actin filaments (AFs) and endoplasmic reticulum (ER) were impacted in a dose- and time- dependent pattern, while microtubule integrity was not markedly affected even at the highest exposure. AF disruption in differentiating cells initiated at 0.01 mg L−1 (0.2 μM), while ER disorganization did so at 0.1 mg L−1 (2 μM); regression equations described the relationships of Cw vs. time required for effect onset, and of Cw vs. AF disturbance progress. Elevated levels of hydrogen peroxide (H2O2) were detected on the 2d. In addition, a significant reduction in epidermal cell viability appeared at 5–10 or 10 mg L−1 (100–200 or 200 μM), depending on the leaf age. The lowest tissue concentration associated with effect onset was 31.05 μg g−1 dry wt (2d, 5 mg L−1); at lower exposures, higher tissue concentrations did not coincide with impact, implying that the uptake rate rather than the tissue concentration relates to the effect onset. The above suggest that (a) Cr (VI) may pose a high risk to seagrass meadows, (b) H. stipulacea can act as a bioindicator of ambient Cr (VI) bioavailability, mainly at elevated exposure concentrations, (c) AF and ER disturbances in seagrass leaf cells could be considered as sensitive biomarkers of Cr (VI)-induced stress, (d) regression equations describing the relationships Cw vs. time required for effect onset and Cw vs. effect progress increase the utility of AF and ER impairment as biomarkers, and (e) the time frame of the exposure should be considered in the interpretation of tissue residues. Our findings improve the utility of seagrasses as indicators of trace metal contamination and could be utilized in the overall effort for seagrass meadows conservation.

The biogeochemistry of copper metallophytes in the Roseby Corridor (North-West Queensland, Australia)

The ability of Australian native metallophytes to tolerate extreme metal concentrations in the soil and other difficult edaphic conditions is still not well understood. Copper is an essential micronutrient for plants to survive, but at high concentrations (> 20 µg g−1) in plant tissues, it can cause foliar chlorosis, stunted growth, and ultimately plant death. The Roseby Corridor in Central Queensland (near Cloncurry) is host to copper metallophytes (Polycarpaea spirostylis, Bulbostylis barbata, Tephrosia virens, Eriachne mucronata) which are able to tolerate soils with total copper concentrations up to 12,700 µg g−1. Even with these high levels of copper in the rhizosphere, the maximum copper in all species is relatively low when compared to Cu concentrations in the soil (leaf/stem: Bulbostylis barbata: 40.9 µg g−1, Eriachne mucronata: 12.3 µg g−1, Polycarpaea spirostylis: 10.9 µg g−1, Tephrosia virens: 128 µg g−1). Therefore, all of these species can be classified as copper Excluder-type metallophytes. Their affinity to copper makes these metallophytes useful indicators of copper surface mineralisation within the Roseby Corridor.

Relation of Endothelin-1 to Abnormal Umbilical Doppler Waveform Studies in Pregnancies Complicated by IDDM and its Relation to the Neonatal Outcome

Introduction Endothelin-1 (ET-1) seems to act as a local paracrine signal rather than a circulating hormone. Its effects are mediated by specific, membrane- bound receptors, which are detectable in high concentrations in the fetoplacental tissue. ET-1 causes an initial transient fall in blood pre

Characterization of sponge-associated Verrucomicrobia: microcompartment-based sugar utilization and enhanced toxin-antitoxin modules as features of host-associated Opitutales.

Bacteria of the phylum Verrucomicrobia are ubiquitous in marine environments and can be found as free-living organisms or as symbionts of eukaryotic hosts. Little is known about host-associated Verrucomicrobia in the marine environment. Here we reconstructed two genomes of symbiotic Verrucomicrobia from bacterial metagenomes derived from the Atlanto-Mediterranean sponge Petrosia ficiformis and three genomes from strains that we isolated from offshore seawater of the Eastern Mediterranean Sea. Phylogenomic analysis of these five strains indicated that they are all members of Verrucomicrobia subdivision 4, order Opitutales. We compared these novel sponge-associated and seawater-isolated genomes to closely related Verrucomicrobia. Genomic analysis revealed that Planctomycetes-Verrucomicrobia microcompartment gene clusters are enriched in the genomes of symbiotic Opitutales including sponge symbionts but not in free-living ones. We hypothesize that in sponge symbionts these microcompartments are used for degradation of l-fucose and l-rhamnose, which are components of algal and bacterial cell walls and therefore may be found at high concentrations in the sponge tissue. Furthermore, we observed an enrichment of toxin-antitoxin modules in symbiotic Opitutales. We suggest that, in sponges, verrucomicrobial symbionts utilize these modules as a defence mechanism against antimicrobial activity deriving from the abundant microbial community co-inhabiting the host.