Silica Nanoparticle Size Determines the Mechanisms Underlying the Inhibition of Iron Oxide Nanoparticle Uptake by Daphnia magna.

Aquatic environments are complicated systems that contain different types of nanoparticles (NPs). Nevertheless, recent studies of NP toxicity, and especially those that have focused on bioaccumulation have mostly investigated only a single type of NPs. Assessments of the environmental risks of NPs that do not consider co-exposure regimes may lead to inaccurate conclusions and ineffective environmental regulation. Thus, the present study examined the effects of differently sized silica NPs (SiO2 NPs) on the uptake of iron oxide NPs (Fe2O3 NPs) by the zooplankton Daphnia magna. Both SiO2 NPs and Fe2O3 NPs were well dispersed in the experimental medium without significant heteroaggregation. Although all three sizes of SiO2 NPs inhibited the uptake of Fe2O3 NPs, the underlying mechanisms differed. SiO2 NPs smaller than the average mesh size (∼200 nm) of the filtering apparatus of D. magna reduced the accumulation of Fe2O3 NPs through uptake competition, whereas larger SiO2 NPs inhibited the uptake of Fe2O3 NPs mainly by reducing the water filtration rate of the daphnids. Overall, in evaluations of the risks of NPs in the natural environment, the different mechanisms underlying the effects of NPs of different sizes on the uptake of dissimilar NPs should be considered.

Turbid Waters and Clearer Standards: Refining Water Quality Criteria for Coastal Environments by Encompassing Metal Bioavailability from Suspended Particles.

Suspended particulate matter (SPM) carries a major fraction of metals in turbid coastal waters, markedly influencing metal bioaccumulation and posing risks to marine life. However, its effects are often overlooked in current water quality criteria for metals, primarily due to challenges in quantifying SPM's contribution. This contribution depends on the SPM concentration, metal distribution coefficients (Kd), and the bioavailability of SPM-bound metals (assimilation efficiency, AE), which can collectively be integrated as a modifying factor (MF). Accordingly, we developed a new stable isotope method to measure metal AE by individual organisms from SPM, employing the widely distributed filter-feeding clam Ruditapes philippinarum as a representative species. Assessing SPM from 23 coastal sites in China, we found average AEs of 42% for Zn, 26% for Cd, 20% for Cu, 8% for Ni, and 6% for Pb. Moreover, using stable isotope methods, we determined metal Kd of SPM from these sites, which can be well predicted by the total organic carbon and iron content (R2 = 0.977). We calculated MFs using a Monte Carlo method. The calculated MFs are in the range 9.9-43 for Pb, 8.5-37 for Zn, 2.9-9.7 for Cu, 1.4-2.7 for Ni, and 1.1-1.6 for Cd, suggesting that dissolved-metal-based criteria values should be divided by MFs to provide adequate protection to aquatic life. This study provides foundational guidelines to refine water quality criteria in turbid waters and protect coastal ecosystems.

Stimulated Raman Scattering Microscopy Reveals Bioaccumulation of Small Microplastics in Protozoa from Natural Waters.

Microplastics (MPs) are pollutants of global concern, and bioaccumulation determines their biological effects. Although microorganisms form a large fraction of our ecosystem's biomass and are important in biogeochemical cycling, their accumulation of MPs has never been confirmed in natural waters because current tools for field biological samples can detect only MPs > 10 µm. Here, we show that stimulated Raman scattering microscopy (SRS) can image and quantify the bioaccumulation of small MPs (<10 µm) in protozoa. Our label-free method, which differentiates MPs by their SRS spectra, detects individual and mixtures of different MPs (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polystyrene, and poly(methyl methacrylate)) in protozoa. The ability of SRS to quantify cellular MP accumulation is similar to that of flow cytometry, a fluorescence-based method commonly used to determine cellular MP accumulation. Moreover, we discovered that protozoa in water samples from Yangtze River, Xianlin Wastewater Treatment Plant, Lake Taihu and the Pearl River Estuary accumulated MPs < 10 µm, but the proportion of MP-containing cells was low (∼2-5%). Our findings suggest that small MPs could potentially enter the food chain and transfer to organisms at higher trophic levels, posing environmental and health risks that deserve closer scrutiny.

Molecular characterization of the cytochrome P450 enzyme CYP18A1 in Henosepilachna vigintioctopunctata.

In insects, the expression of 20E response genes that initiate metamorphosis is triggered by a pulse of 20-hydroxyecdysone (20E). The 20E pulse is generated through two processes: synthesis, which increases its level, and inactivation, which decreases its titer. CYP18A1 functions as an ecdysteroid 26-hydroxylase and plays a role in 20E removal in several representative insects. However, applying 20E degradation activity of CYP18A1 to other insects remains a significant challenge. In this study, we discovered high levels of Hvcyp18a1 during the larval and late pupal stages, particularly in the larval epidermis and fat body of Henosepilachna vigintioctopunctata, a damaging Coleopteran pest of potatoes. RNA interference (RNAi) targeting Hvcyp18a1 disrupted the pupation. Approximately 75% of the Hvcyp18a1 RNAi larvae experienced developmental arrest and remained as stunted prepupae. Subsequently, they gradually turned black and eventually died. Among the Hvcyp18a1-depleted animals that successfully pupated, around half became malformed pupae with swollen elytra and hindwings. The emerged adults from these deformed pupae appeared misshapen, with shriveled elytra and hindwings, and were wrapped in the pupal exuviae. Furthermore, RNAi of Hvcyp18a1 increased the expression of a 20E receptor gene (HvEcR) and four 20E response transcripts (HvE75, HvHR3, HvBrC, and HvαFTZ-F1), while decreased the transcription of HvßFTZ-F1. Our findings confirm the vital role of CYP18A1 in the pupation, potentially involved in the degradation of 20E in H. vigintioctopunctata.

PIAS1 upregulation confers protection against Cerulein-induced acute pancreatitis via FTO downregulation by enhancing sumoylation of Foxa2.

OBJECTIVE: This research discussed the specific mechanism by which PIAS1 affects acute pancreatitis (AP). METHODS: PIAS1, Foxa2, and FTO expression was assessed in Cerulein-induced AR42J cells and mice. Loss- and gain-of-function assays and Cerulein induction were conducted in AR42J cells and mice for analysis. The relationship among PIAS1, Foxa2, and FTO was tested. Cell experiments run in triplicate, and eight mice for each animal group. RESULTS: Cerulein-induced AP cells and mice had low PIAS1 and Foxa2 and high FTO. Cerulein induced pancreatic injury in mice and inflammation and oxidative stress in pancreatic tissues, which could be reversed by PIAS1 or Foxa2 upregulation or FTO downregulation. PIAS1 elevated SUMO modification of Foxa2 to repress FTO transcription. FTO upregulation neutralized the ameliorative effects of PIAS1 or Foxa2 upregulation on Cerulein-induced AR42J cell injury, inflammation, and oxidative stress. CONCLUSION: PIAS1 upregulation diminished FTO transcription by increasing Foxa2 SUMO modification, thereby ameliorating Cerulein-induced AP.

Toward Citizen Science-Based Ocean Acidification Observations Using Smartphone Devices.

pH is a key parameter in many chemical, biological, and biogeochemical processes, making it a fundamental aspect of environmental monitoring. Rapid and accurate seawater pH measurements are essential for effective ocean observation and acidification investigations, resulting in the need for novel solutions that allow robust, precise, and affordable pH monitoring. In this study, a versatile smartphone-based environmental analyzer (vSEA) was used for the rapid measurement of seawater pH in a field study. The feasibility of the use of the vSEA algorithm for pH quantification was explored and verified. When used in conjunction with a three-dimensional (3D)-printed light-proof shell, the quality of captured images is guaranteed. The quantitative accuracy of vSEA pH measurements reached 0.018 units with an uncertainty of <0.01, meeting the requirements of the Global Ocean Acidification Observing Network (GOA-ON) for "weather" goals (permitting a maximum pH uncertainty of 0.02). The vSEA-pH system was successfully applied for on-site pH measurements in coastal seawater and coral systems. The performance of the vSEA-pH system was validated using different real-world samples, and t-test results showed that the vSEA-pH system was consistent with pH measurements obtained using a state-of-the-art benchtop spectrophotometer (t = 1.986, p = 0.7949). The vSEA-pH system is applicable to different types of smartphone devices, making it possible for vSEA-pH to be widely promoted for public citizen use. The vSEA-pH system offers a simple, accurate, and applicable method for the on-site measurement of seawater pH, assisting the large-scale monitoring of ocean acidification by allowing the contribution of citizen science-based data collection.

Label-Free Imaging of Humic Substance Bioaccumulation by Pump-Probe Microscopy.

Humic substances (HS) are the most abundant forms of natural organic matter on the earth surface. Comprised of decomposed plant and animal materials rich in carbon, oxygen, hydrogen, nitrogen, and sulfur complexes, HS facilitate global carbon and nitrogen cycling and the transport of anthropogenic contaminants. While it is known that HS also interact with organisms at different trophic levels to produce beneficial and harmful effects whether HS exert these biological effects through accumulation remains unknown. Current radiolabeling techniques, which only detect the amount of accumulated radiolabels, cannot visualize the transport and accumulation behavior of HS. Here, using a label-free method based on pump-probe microscopy, we show HS entered the protozoan Tetrahymena thermophila, zebrafish embryos, and human cells and exerted direct effects on these organisms. HS accumulated in the nucleus of T. thermophila, chorion pore canals of zebrafish embryos, and nucleus of intestinal and lung cells in a concentration- and time-dependent way. Epigenetic and transcriptomics assays show HS altered chromatin accessibility and gene transcription in T. thermophila. In zebrafish larvae, HS induced neurotoxicity, altering spontaneous muscle contraction and locomotor activity. Detailed images showing HS accumulation in our study reveal new insights on the ecological and environmental behavior of HS.

Higher Risks of Copper Toxicity in Turbid Waters: Quantifying the Bioavailability of Particle-Bound Metals to Set Site-Specific Water Quality Criteria.

In coastal waters, particulate metals constitute a substantial fraction of the total metals; however, the prevalent water quality criteria are primarily based on dissolved metals, seemingly neglecting the contribution of particulate metals. Here we developed a method to quantify the toxicity risk of particulate metals, and proposed a way to calculate modifying factors (MFs) for setting site-specific criteria in turbid waters. Specifically, we used a side-by-side experimental design to study copper (Cu) bioaccumulation and toxicity in an estuarine clam, Potamocorbula laevis, under the exposure to "dissolved only" and "dissolved + particulate" 65Cu. A toxicokinetic-toxicodynamic model (TK-TD) was used to quantify the processes of Cu uptake, ingestion, assimilation, egestion, and elimination, and to relate mortality risk to tissue Cu. We find that particulate Cu contributes 40-67% of the Cu bioaccumulation when the suspended particulate matter (SPM) ranges from 12 to 229 mg L-1. The Cu-bearing SPM also increases the sensitivity of organisms to internalized Cu by decreasing the internal threshold concentration (CIT) from 141 to 76.8 µg g-1. MFs were derived based on the TK-TD model to consider the contribution of particulate Cu (in the studied SPM range) for increasing Cu bioaccumulation (MF = 1.3-2.2) and toxicity (MF = 2.3-3.9). Water quality criteria derived from dissolved metal exposure need to be lowered by dividing by an MF to provide adequate protection. Overall, the method we developed provides a scientifically sound framework to manage the risks of metals in turbid waters.

Enhancing Sediment Bioaccumulation Predictions: Isotopically Modified Bioassay and Biodynamic Modeling for Nickel Assessment.

Quantifying metal bioaccumulation in a sedimentary environment is a valuable line of evidence when evaluating the ecological risks associated with metal-contaminated sediments. However, the precision of bioaccumulation predictions has been hindered by the challenges in accurately modeling metal influx processes. This study focuses on nickel bioaccumulation from sediment and introduces an innovative approach using the isotopically modified bioassay to directly measure nickel assimilation rates in sediment. Tested in sediments spiked with two distinct nickel concentrations, the measured Ni assimilation rates ranged from 35 to 78 ng g-1 h-1 in the Low-Ni treatment and from 96 to 320 ng g-1 h-1 in the High-Ni treatment. Integrating these rates into a biodynamic model yielded predictions of nickel bioaccumulation closely matching the measured results, demonstrating high accuracy with predictions within a factor of 3 for the Low-Ni treatment and within a factor of 1 for the High-Ni treatment. By eliminating the need to model metal uptake from various sources, this streamlined approach provides a reliable method for predicting nickel bioaccumulation in contaminated sediments. This advancement holds promise for linking bioaccumulation with metal toxicity risks in sedimentary environments, enhancing our understanding of metal-contaminated sediment risks and providing valuable insights to support informed decision-making in ecological risk assessment and management.

Case report: septic shock after endometrial polypectomy with tissue removal system.

As an emerging surgical technology, tissue removal systems have been widely used in the treatment of endometrial polyps due to its characteristics of less endometrial damage, shorter learning curve and clearer vision of the operative field. There are few cases in the literature reporting serious complications after endometrial polypectomy using tissue removal systems. As known, septic shock is a rare complication following hysteroscopic polypectomy. Now, we present the case of a 23-year-old woman who developed septic shock after polypectomy with tissue removal system. The patient had a history of recurrent vaginitis for more than half a year. Due to endometrial polyps, she was admitted to our hospital and scheduled to undergo hysteroscopic endometrial polypectomy. Three hours after the endometrial polypectomy using the tissue removal system, the patient had shock symptoms such as increased body temperature, decreased blood pressure and increased heart rate. Then, the patient was successfully treated and discharged after anti-infection and anti-shock treatments. The purpose of this case report is to remind clinicians to consider the possibility of serious infection and comprehensively evaluate the risk of infection before choosing hysteroscopic devices for endometrial polyps, especially for patients who choose the mechanical hysteroscopic tissue removal systems. Furthermore, the mechanical hysteroscopic tissue removal systems should be used with caution in patients with previous recurrent vaginitis.

Impacts of hydraulic conditions on microplastics biofilm development, shear stresses distribution, and microbial community structures in drinking water distribution pipes.

Both microplastic and biofilm are contamination sources in drinking water, but their integrated impacts on water quality have been rarely studied, especially in drinking water distribution pipes with complex hydraulic conditions. This study explored the impacts of hydraulic conditions (0-2 m/s) on microplastic biofilm (MP-BM) development, shear stresses distribution, and microbial community structures. The research was conducted for two weeks using a pilot test device to simulate practical water pipes. The following were the primary conclusions: (1) According to morphology analysis, clusters (>5 µm) significantly increased in the plastisphere when the flow velocity ranged from 0.55 m/s to 0.95 m/s, and average size of clusters decreased when the flow velocity ranged from 1.14 m/s to 1.40 m/s (2) Characteristics of MP-BM impact shear stress on both plastisphere and pipe wall biofilm. Shear stresses were positively correlated with flow velocity, number of MP-BM, and size of MP-BM, while negatively correlated with diameters of pipes. (3) 31 genera changed strictly and monotonously with the fluid velocity, accounting for 15.42%. Opportunistic pathogens in MP-BM such as Sediminibacterium, Curvibacter, and Flavobacterium were more sensitive to hydraulic conditions. Moreover, microplastics (<100 µm) deserve more attention to avoid human ingestion and to prevent mechanical damage and bio-chemical risks.

Genomic, transcriptomic, and metabolomic analysis of Oldenlandia corymbosa reveals the biosynthesis and mode of action of anti-cancer metabolites.

Plants accumulate a vast array of secondary metabolites, which constitute a natural resource for pharmaceuticals. Oldenlandia corymbosa belongs to the Rubiaceae family, and has been used in traditional medicine to treat different diseases, including cancer. However, the active metabolites of the plant, their biosynthetic pathway and mode of action in cancer are unknown. To fill these gaps, we exposed this plant to eight different stress conditions and combined different omics data capturing gene expression, metabolic profiles, and anti-cancer activity. Our results show that O. corymbosa extracts are active against breast cancer cell lines and that ursolic acid is responsible for this activity. Moreover, we assembled a high-quality genome and uncovered two genes involved in the biosynthesis of ursolic acid. Finally, we also revealed that ursolic acid causes mitotic catastrophe in cancer cells and identified three high-confidence protein binding targets by Cellular Thermal Shift Assay (CETSA) and reverse docking. Altogether, these results constitute a valuable resource to further characterize the biosynthesis of active metabolites in the Oldenlandia group, while the mode of action of ursolic acid will allow us to further develop this valuable compound.

Isotopically Modified Bioassay Bridges the Bioavailability and Toxicity Risk Assessment of Metals in Bedded Sediments.

The application of bioavailability-based risk assessment for the management of contaminated sediments requires new techniques to rapidly and accurately determine metal bioavailability. Here, we designed a multimetal isotopically modified bioassay to directly measure the bioavailability of different metals by tracing the change in their isotopic composition within organisms following sediment exposure. With a 24 h sediment exposure, the bioassay sensed significant bioavailability of nickel and lead within the sediment and determined that cadmium and copper exhibited low bioavailable concentrations and risk profiles. We further tested whether the metal bioavailability sensed by this new bioassay would predict the toxicity risk of metals by examining the relationship between metal bioavailability and metal toxicity to chironomid larvae emergence. A strong dose-toxicity relationship between nickel bioavailability (nickel assimilation rate) and toxicity (22 days emergence ratio) indicated exposure to bioavailable nickel in the sediment induced toxic effects to the chironomids. Overall, our study demonstrated that the isotopically modified bioassay successfully determined metal bioavailability in sediments within a relatively short period of exposure. Because of its speed of measurement, it may be used at the initial screening stage to rapidly diagnose the bioavailable contamination status of a site.

Malaria.tools-comparative genomic and transcriptomic database for Plasmodium species.

Malaria is a tropical parasitic disease caused by the Plasmodium genus, which resulted in an estimated 219 million cases of malaria and 435 000 malaria-related deaths in 2017. Despite the availability of the Plasmodium falciparum genome since 2002, 74% of the genes remain uncharacterized. To remedy this paucity of functional information, we used transcriptomic data to build gene co-expression networks for two Plasmodium species (P. falciparum and P. berghei), and included genomic data of four other Plasmodium species, P. yoelii, P. knowlesi, P. vivax and P. cynomolgi, as well as two non-Plasmodium species from the Apicomplexa, Toxoplasma gondii and Theileria parva. The genomic and transcriptomic data were incorporated into the resulting database, malaria.tools, which is preloaded with tools that allow the identification and cross-species comparison of co-expressed gene neighbourhoods, clusters and life stage-specific expression, thus providing sophisticated tools to predict gene function. Moreover, we exemplify how the tools can be used to easily identify genes relevant for pathogenicity and various life stages of the malaria parasite. The database is freely available at www.malaria.tools.

Outcomes of prolonged mechanical ventilation and tracheostomy in critically ill elderly patients: a historical cohort study.

PURPOSE: With an aging global population, the increased proportion of elderly patients in the intensive care unit (ICU) raises important questions regarding optimal management. Currently, data on tracheostomy and its outcomes in the elderly are limited. We aimed to determine the in-hospital survival of elderly ICU patients following tracheostomy, and describe impacts on discharge disposition and functional outcomes. METHODS: We conducted a historical cohort study at two academic hospitals in Toronto. All patients aged ≥ 70 yr who received a tracheostomy during their ICU stay between January 2010 and June 2016 were included in a retrospective chart review. Data on patient demographics, frailty, tracheostomy indication, and outcomes were collected. RESULTS: The study included 270 patients with a mean (standard deviation) age of 81 (6) yr. The majority were admitted to ICU for respiratory failure (147/270, 54%) and received a tracheostomy for prolonged mechanical ventilation (202/270, 75%). Intensive care unit and hospital mortality were 26% (68/270) and 46% (125/270), respectively. Twenty-five percent (67/270) of patients were decannulated during hospital admission, a median [interquartile range (IQR)] of 41 [25-68] days after tracheostomy. Intensive care unit and hospital length of stay were 31 [17-53] and 81 [46-121] days, respectively. At hospital discharge, 6% (17/270) of patients were discharged home, all were frail (median Clinical Frailty Score of 7) and most were tube-fed (101/270, 70%), unable to speak (81/270, 56%), and nonambulatory (98/270, 68%). CONCLUSIONS: In patients aged ≥ 70 yr, tracheostomy during ICU stay marked a transition toward prolonged chronic critical illness. Nearly half of the patients died during the admission, and although a quarter were successfully decannulated, the majority of survivors were left with severe frailty and functional impairment.

RéSUMé: OBJECTIF: Avec le vieillissement de la population mondiale, la proportion accrue de patients âgés aux soins intensifs (USI) soulève d'importantes questions concernant leur prise en charge optimale. À l'heure actuelle, les données sur la trachéotomie et ses issues chez les personnes âgées sont limitées. Nous avions pour objectif de déterminer la survie hospitalière des patients âgés en soins intensifs après une trachéotomie et d'examiner les impacts sur la disposition au congé et les devenirs fonctionnels. MéTHODE: Nous avons mené une étude de cohorte historique dans deux hôpitaux universitaires de Toronto. Tous les patients âgés de ≥ 70 ans ayant reçu une trachéotomie pendant leur séjour à l'USI entre janvier 2010 et juin 2016 ont été inclus dans un examen rétrospectif des dossiers. Les données sur la démographie des patients, leur fragilité, l'indication pour la trachéotomie et les devenirs ont été recueillies. RéSULTATS: L'étude a inclus 270 patients avec un âge moyen (écart type) de 81 (6) ans. La majorité d'entre eux ont été admis à l'USI pour insuffisance respiratoire (147/270, 54 %) et ont subi une trachéotomie pour une ventilation mécanique prolongée (202/270, 75 %). La mortalité à l'USI et à l'hôpital était de 26 % (68/270) et 46 % (125/270), respectivement. Vingt-cinq pour cent (67/270) des patients ont été décanulés pendant leur admission à l'hôpital, [écart interquartile (ÉIQ)] 41 [25-68] jours après la trachéotomie en moyenne. La durée du séjour à l'USI et à l'hôpital était de 31 [17-53] et 81 [46-121] jours, respectivement. Lors du congé de l'hôpital, 6 % (17/270) des patients sont rentrés chez eux, tous étaient fragiles (score médian de fragilité clinique de 7) et la plupart étaient nourris par sonde (101/270, 70 %), incapables de parler (81/270, 56 %) et non ambulatoires (98/270, 68 %). CONCLUSIONS: Chez les patients âgés de ≥ 70 ans, la trachéotomie pendant le séjour aux soins intensifs a marqué une transition vers une maladie chronique grave prolongée. Près de la moitié des patients sont décédés pendant leur séjour, et bien qu'un quart aient été décanulés avec succès, la majorité des survivants se sont retrouvés avec une fragilité sévère et une déficience fonctionnelle.

High-flow nasal cannula therapy: A multicentred survey of the practices among physicians and respiratory therapists in Singapore.

BACKGROUND: Use of high-flow nasal cannula (HFNC) has become a regular intervention in the intensive care units especially in patients coming in with hypoxaemic respiratory failure. Clinical practices may differ from published literature. OBJECTIVES: The objective of this study was to determine the clinical practices of physicians and respiratory therapists (RTs) on the use of HFNC. METHODS: A retrospective observational study looking at medical records on HFNC usage from January 2015 to September 2017 was performed and was followed by a series of questions related to HFNC practices. The survey involved physicians and RTs in intensive care units from multiple centres in Singapore from January to April 2018. Indications and thresholds for HFNC usage with titration and weaning practices were compared with the retrospective observational study data. RESULTS: One hundred twenty-three recipients (69.9%) responded to the survey and reported postextubation (87.8%), pneumonia in nonimmunocompromised (65.9%), and pneumonia in immunocompromised (61.8%) patients as the top three indications for HFNC. Of all, 39.8% of respondents wanted to use HFNC for palliative intent. Similar practices were observed in the retrospective study with the large cohort of 63% patients (483 of the total 768 patients) where HFNC was used for acute hypoxaemic respiratory failure and 274 (35.7%) patients to facilitate extubation. The survey suggested that respondents would initiate HFNC at a lower fraction of inspired oxygen (FiO2), higher partial pressure of oxygen to FiO2 ratio, and higher oxygen saturation to FiO2 ratio for nonpneumonia patients than patients with pneumonia. RTs were less likely to start HFNC for patients suffering from pneumonia and interstitial lung disease than physicians. RTs also preferred adjustment of FiO2 to improve oxygen saturations and noninvasive ventilation for rescue. CONCLUSIONS: Among the different intensive care units surveyed, the indications and thresholds for the initiation of HFNC differed in the clinical practices of physicians and RTs.

Measuring Metal Uptake and Loss in Individual Organisms: A Novel Double Stable Isotope Method and its Application in Explaining Body Size Effects on Cadmium Concentration in Mussels.

Interindividual variabilities in metal bioaccumulation confound our interpretation of the biomonitoring data. Measuring metal toxicokinetics in organism "individuals" may provide insights into the processes underlying the variabilities. Therefore, we developed a double stable isotope method that can simultaneously measure uptake and elimination of metals in individual organisms and thus the distribution of the toxicokinetic parameters. Specifically, we exposed organisms to both isotopes (113Cd and 114Cd; Cd = cadmium) during the first stage and to only one isotope (114Cd) during the second stage. Metal uptake and elimination rate constants (i.e., ku and ke) were simultaneously estimated from the content of the two isotopes measured in each organism at the end of the second stage. We applied the method to investigate the interindividual variability in Cd concentrations caused by body size in two marine mussel species. Cd concentrations are higher in larger Xenostrobus atratus but lower in smaller Perna viridis. Size-dependent Cd uptake is found to be responsible for size effects on Cd concentrations in the mussels and the interspecies differences in the relationship between Cd concentration and body size. Specifically, Cd ku increases with size in X. atratus (0.057-0.297 L g-1 d-1) but decreases with size in P. viridis (0.155-0.351 L g-1 d-1). In contrast, Cd ke is not influenced by body size (X. atratus: 0.002-0.060 d-1; P. viridis: 0.008-0.060 d-1). Overall, we extended the applicability of the stable isotope methods to measure metal toxicokinetics in "individual" organisms, providing a readily available tool for investigating problems related to metal bioaccumulation.

Application of a Multi-Metal Stable-Isotope-Enriched Bioassay to Assess Changes to Metal Bioavailability in Suspended Sediments.

The direct measurement of particulate contaminant bioavailability is a challenging aspect for the environmental risk assessment of contaminated sites. Here, we demonstrated a multi-metal stable-isotope-enriched bioassay to simultaneously measure the bioavailability of Cd, Cu, and Zn in naturally contaminated sediments following differing periods of resuspension treatment. Freshwater filter-feeding clams were pre-labeled with the isotopes 114Cd, 65Cu, and 68Zn to elevate isotope abundances in their tissues and then exposed to metal-contaminated suspended sediments. The assimilation of sediment-associated metals by clams would decrease the isotope ratios (Cd114/111, Cu65/63, and Zn68/64) in tissues, providing a direct measurement of metal bioavailability. For the sediments tested here, the method revealed bioavailable cadmium and non-bioavailable copper in sediments but was inconclusive for zinc. With a longer resuspension time, the bioavailability of particulate cadmium increased, but that of copper was unaffected. Metal bioavailability predicted using traditional wet-chemical extraction methods was inconsistent with these findings. The study indicated that multi-metal stable-isotope-enriched bioassay provides a new tool for directly assessing metal bioavailability in sediments, and this method is amenable for use in in situ assessments.

Enhancing Antigen Cross-Presentation in Human Monocyte-Derived Dendritic Cells by Recruiting the Intracellular Fc Receptor TRIM21.

Suboptimal immune responses to pathogens contribute to chronic infections. One way to improve immune responses is to boost Ag presentation. In this study, we investigate the potential of the tripartite motif-containing 21 (TRIM21) pathway. TRIM21 is a ubiquitously expressed cytosolic protein that recognizes the Fc region of Abs. When Abs that are bound to pathogens enter the cell as immune complexes, binding of TRIM21 to Fc initiates downstream inflammatory signaling and targets the immune complexes for proteasomal degradation. In APCs, peptides generated by proteasomes are loaded onto MHC class I molecules to stimulate CD8 T cell responses, which are crucial for effective immunity to pathogens. We hypothesized that increasing the affinity between immune complexes and TRIM21 might markedly improve CD8 T cell responses to Ags processed by the TRIM21 pathway. Using phage display technology, we engineered the human IgG1 Fc to increase its affinity for TRIM21 by 100-fold. Adenovirus immune complexes with the engineered Fc induced greater maturation of human dendritic cells (DC) than immune complexes with unmodified Fc and stimulated increased Ag-specific CD8 T cell proliferation and IFN-γ release in cocultures of DC-PBMC. Thus, by increasing the affinity between Fc and TRIM21, Ags from immune complexes undergo enhanced cross-presentation on DC, leading to greater CD8 T cell responses. Our study reveals an approach that could potentially be used in vaccines to increase cytotoxic T cell responses against Ags that are targeted or delivered by Fc-modified Abs.

LSTrAP-Crowd: prediction of novel components of bacterial ribosomes with crowd-sourced analysis of RNA sequencing data.

BACKGROUND: Bacterial resistance to antibiotics is a growing health problem that is projected to cause more deaths than cancer by 2050. Consequently, novel antibiotics are urgently needed. Since more than half of the available antibiotics target the structurally conserved bacterial ribosomes, factors involved in protein synthesis are thus prime targets for the development of novel antibiotics. However, experimental identification of these potential antibiotic target proteins can be labor-intensive and challenging, as these proteins are likely to be poorly characterized and specific to few bacteria. Here, we use a bioinformatics approach to identify novel components of protein synthesis. RESULTS: In order to identify these novel proteins, we established a Large-Scale Transcriptomic Analysis Pipeline in Crowd (LSTrAP-Crowd), where 285 individuals processed 26 terabytes of RNA-sequencing data of the 17 most notorious bacterial pathogens. In total, the crowd processed 26,269 RNA-seq experiments and used the data to construct gene co-expression networks, which were used to identify more than a hundred uncharacterized genes that were transcriptionally associated with protein synthesis. We provide the identity of these genes together with the processed gene expression data. CONCLUSIONS: We identified genes related to protein synthesis in common bacterial pathogens and thus provide a resource of potential antibiotic development targets for experimental validation. The data can be used to explore additional vulnerabilities of bacteria, while our approach demonstrates how the processing of gene expression data can be easily crowd-sourced.