An integrated system of pyrene and rhodamine-6G for selective colorimetric and fluorometric sensing of mercury(II)

A pyrene and rhodamine-6G functionalized simple chemosensor L is studied toward sensing of metal ions in solution extensively. L shows selective color change from colorless to pink in the presence of Hg²⁺ in acetonitrile and the UV-Vis study shows peak at 525 nm with a ε value of 5.2 × 10⁴ M⁻¹ cm⁻¹ due to selective ring opening of rhodamine spirolactam moiety. The selective sensing of Hg²⁺ by L in the presence of other metal ions and reversible nature of “OFF-ON-OFF” functionality of L by Hg²⁺ and EDTA, respectively, are also established. The fluorescence study of L in the presence of Hg²⁺ shows emission at 550 nm when excited at 525 nm (ring opened rhodamine wavelength) or 340 nm (pyrene wavelength) in dry CH₃CN. Thus L acts as a selective colorimetric and fluorometric probe (dual probe) for the Hg²⁺ in solution. Metal ion sensing ability of L is also carried out in water as well as in aqueous Hepes buffer. These studies suggest that the fluorescence output of L in presence of Hg²⁺ in aqueous environment is apparently due to the generation of acid upon addition of Hg²⁺ salt in water.     

Assays Based on Differential Adsorption of Single-stranded and Double-stranded DNA on Unfunctionalized Gold Nanoparticles in a Colloidal Suspension

Under certain conditions, single-stranded DNA adsorbs to negatively charged gold nanoparticles in a colloid whereas double-stranded DNA does not. We present evidence that this phenomenon can be explained by the difference in their electrostatic properties that in turn reflects conformational differences. The ability to discriminate the hybridization state of DNA on the basis of adsorption behavior can be utilized to design simple colorimetric and fluorimetric assays that take advantage of plasmon resonance in the gold nanoparticles. We present examples where we detect specific target sequences in oligonucleotides and in genomic DNA. Because conformational changes in special DNA sequences can also be induced by analytes such as potassium, we report a potassium ion detection scheme based on the same principle.     

Sensitive and selective colorimetric detection of Staphylococcus aureus-SPA gene by engineered gold nanosensor

Staphylococcal protein A (SPA) is an important virulence factor that enables Staphylococcus aureus to evade host immune responses. The current work aims to detect the S. aureus SPA gene by a colorimetric method based on gold nanoparticles (AuNPs). For this purpose, the chromosomal DNA of S. aureus was extracted. Thereafter, primers and thiolated oligonucleotide probe were designed based on protein A sequence data in the gene bank. PCR analysis was performed, and the PCR product was electrophoresed on 2 % agarose gel. Gold nanosensor (Au-Ns) was synthesized by the reaction between AuNPs and the thiolated oligonucleotide probe. The physicochemical properties of AuNPs and Au-Ns were characterized. The detection of the SPA gene was performed based on color change detected by the naked eye and UV–vis spectrophotometry. Finally, the described method was optimized and validated for standard, clinical, and food samples. The PCR analysis showed a characteristic fragment of the SPA gene with a molecular size of 545 base pairs (bp) and a detection limit of 60 pg/ µL. The physicochemical analyses illustrated Au-Ns’ correct preparation with a zeta potential of ?13.42 mV and particle size range 6–11 nm. Moreover, Au-Ns showed 100 % specificity with a detection limit (DL) of 6 fg/ µL. The proposed method was well described to be applied in clinical and research laboratories.     

Sensitive detection of estradiol based on ligand binding domain of estrogen receptor and gold nanoparticles

With increasing concerns of estrogenic effects of endocrine disrupting compounds, the development of simple detection assay for these compounds is an ongoing need. Herein, a simple, rapid, and highly sensitive assay for estradiol (E2) detection was developed using the ligand binding domain of estrogen receptor α (LBD-ERα), the receptor interacting domain of steroid receptor co-activator 1 (RID-SRC1), and gold nanoparticles (AuNPs). The colloidal AuNPs could be stabilized against a salt-induced aggregation by adding LBD-ERα protein. However, with the presence of E2, the specific binding of LBD-ERα protein and E2 led to a salt-induced aggregation of AuNPs as seeing from a color change from red to blue. This developed assay exhibited a high sensitivity for E2 detection with the limit of detection (LOD) of 2.62 × 10⁻¹⁴ M. When the RID-SRC1 protein was included, the detection sensitivity was increased, which the LOD for E2 was at 1.20 × 10⁻¹⁵ M. This assay was specific for a detection of E2 but not progesterone, the negative control ligand. Results of this work clearly showed the efficiency of developed assay for E2 detection, which possibly further developed for an onsite monitoring of E2.     

Gold finder: a computer method for fast automatic double gold labeling detection,counting, and color overlay in electron microscopic images

This work presents a computerized method to identify, detect, evaluate, and, by colored overlay, present gold particle pairs in electron microscopy (EM), even in wide-field views. Double gold immunolabeled specimens were analyzed in a LEO 912 electron microscope equipped with a 2k x 2k-pixel slow-scan cooled CCD camera connected to a computer with analySIS 3.1 PRO image processing software. The acquisition of a high-resolution and high-dynamic-range image by the camera allowed correct segmentation of the gold particles, separating them from other cell structures and from the substrate. Particle identification was performed by a classification module designed by us. Based on shape and size, the computer recognized the group of small particles and classified them as either singular or clustered and differentiated these from the single bigger type. The final image shows the particle types separated and colored, and indicates the total number of objects encountered in the specific region of interest. Moreover, a montage tool allowed us to obtain final representative images of large microscopic fields, which on analysis by the Gold Finder module provided information on the distribution and localization of antigens comparable to that provided by the wide-field light microscope images.     

Effects of Ca(II) ions on Mn(II) dynamics in chick glia and rat astrocytes: Potential regulation of glutamine synthetase

Previous studies have demonstrated that in glia and astrocytes Mn(II) is distributed with ca. 30–40% in the cytoplasm, 60–70% in mitochondria. Ca(II) ions were observed to alter both the flux rates and distribution of Mn(II) ions in primary cultues of chick glia and rat astrocytes. External (influxing) Ca(II) ions had the greatest effect on Mn(II) uptake and efflux, compared to internal (effluxing) or internal-external equilibrated Ca(II) ions. External (influxing) Ca(II) ions inhibited the net rate and extent of Mn(II) uptake but enhanced Mn(II) efflux from mitochondria. These observations differ from Ca(II)–Mn(II) effects previously reported with brain (neuronal) mitochondria. Overall, increased cytoplasmic Ca(II) acts to block Mn(II) uptake and enhance Mn(II) release by mitochondria, which serve to increase the cytoplasmic concentration of free Mn(II). A hypothesis is presented involving external L-glutamate acting through membrane receptors to mobilize cell Ca(II), which in turn causes mitochondrial Mn(II) to be released. Because the concentration of free cytoplasmic Mn(II) is poised near the K_d for Mn(II) with glutamine synthetase, a slight increase in cytoplasmic Mn(II) will directly enhance the activity of glutamine synthetase, which catalyzes removal of neurotoxic glutamate and ammonia.     

The gold nanoparticle size and exposure duration effect on the liver and kidney function of rats: In vivo

Nanoparticles (NPs) offer a great possibility for biomedical application, not only to deliver pharmaceutics, but also to be used as novel diagnostic and therapeutic approaches. Currently, there are no data available regarding to what extent the degree of the toxicity and the accumulation of gold nanoparticles (GNPs) are present in in vivo administration. This study aimed to address the GNP size and exposure duration effect on the liver and kidney function of rats: in vivo.MethodsA total of 30 healthy male Wistar-Kyoto rats of the same age (12 weeks old) and weighing 220–240 g of King Saud University colony were used. Animals were randomly divided into groups, two GNP-treated rat groups and one control group (CG). The 50 μl of 10 and 50 nm GNPs was intraperitoneally administered in rats for exposure duration of 3 days. Then, several biochemical parameters such as aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), alanine transaminase (ALT), alkaline phosphatase (ALP), urea (UREA) and creatinine (CREA) were evaluated.ResultsIn this study, the AST values increased with the administration of 10 and 50 nm GNPs compared with the control. The AST values significantly increased with 10 nm GNPs compared with 50 nm GNPs and control. The GGT and ALT values decreased with the administration of 10 and 50 nm GNPs compared with the control. The GGT and ALT values significantly decreased with 50 nm GNPs compared with 10 nm GNPs and control. The ALP values significantly decreased with the administration of 10 and 50 nm GNPs compared with the control. The decrease in ALP values with 10 nm GNPs was higher than those compared with 50 nm GNPs. In this study, the levels of UREA and CREA values increased in a non significant manner after the administration of 10 and 50 nm GNPs compared with the control.ConclusionsThis study demonstrates that the increase in the enzymes AST and the decrease in ALP are smaller GNPs (10 nm) size-dependent for exposure duration of 3 days; while the decrease in the enzymes GGT and ALT are bigger GNPs (50 nm) size-dependent. The levels of UREA and CREA values indicated no significant changes with the administration of 10 and 50 nm GNPs for exposure duration of 3 days compared with the control. The administration of 10 and 50 nm GNPs for short exposure duration of 3 days induced only significant variations with some liver enzymes while kidney showed no significant variations. This study suggests that synthesis and metabolism of GNPs as well as the protection of the liver will be more important issues for medical applications of gold-based nanomaterials in future.     

Effects of anions and/or cell volume on the permeance of an apical water pathway induced by Hg in toad skin epithelium

Hg compounds block membrane transport units behaving as water channels. Here we show that Hg induces an apical water pathway in toad skins pretreated with 10^–3 M CH₃ClHg or HgCl₂, added to the outer bathing medium. Washing with SO₄-Ringer caused a several-fold increase in net water flow (J _w ) and osmotic permeability coefficient (P _f ) that was reversed by re-exposure to Cl- or NO₃-Ringer and mimicked by gluconate-Ringer. These P _f changes could be elicited repeatedly and were present if, and only if, anion replacements took place in the inner bathing solution. Such inner polarity was related to the anion permeability of the epidermal basolateral membrane: impermeant anions (SO₄, gluconate) increased P _f ; permeant anions (Cl, NO₃) did not change basal P _f but reversed the high P _f induced by impermeant anions. Hg induced the appearance of aggregates that persisted despite repeated washings of the skins during 4–5 h, and whether P _f was high (SO₄-Ringer) or low (Cl-Ringer) before skin fixation.The Hg-induced apical water pathway in toad skin appears to be a unique model for studying the interplay between cell volume, cell ionic composition and water permeability.We thank P. Brawand and P. Fruleux for technical assistance. This work has been supported by grants from the Swiss National Science Foundation (Nos. 31-30030.90 to A.G. and R.C.dS., and 32-34090.92 to P.M.)     

Effects of temperature on body color change in the grasshopper Atractomorpha lata (Orthoptera: Pyrgomorphidae) with reference to sex differences in color morph frequencies

The effects of five environmental factors, background color, density, humidity, photoperiod and temperature, on the body color of a pyrgomorphid green/brown polymorphic grasshopper, Atractomorpha lata, were examined in rearing experiments, in which the differences in color morph frequencies between males and females were also examined. Field censuses were conducted to determine whether the sex difference in body‐color polymorphism occurs under field conditions. Among the environmental factors examined, temperature was the only factor that significantly affected body color: the frequency of brown morphs tended to be higher at higher temperatures. The frequency of brown morphs in the female was higher than in the male, a consistent finding in both the rearing experiments and the field censuses. The threshold temperature at which body color changes may be lower in the female than in the male.     

The impact of accelerating land-use change on the N-Cycle of tropical aquatic ecosystems: Current conditions and projected changes

Published data and analyses from temperate and tropical aquatic systems are used to summarize knowledge about the potential impact of land-use alteration on the nitrogen biogeochemistry of tropical aquatic ecosystems, identify important patterns and recommend key needs for research. The tropical N-cycle is traced from pre-disturbance conditions through the phases of disturbance, highlighting major differences between tropical and temperate systems that might influence development strategies in the tropics. Analyses suggest that tropical freshwaters are more frequently N-limited than temperate zones, while tropical marine systems may show more frequent P limitation. These analyses indicate that disturbances to pristine tropical lands will lead to greatly increased primary production in freshwaters and large changes in tropical freshwater communities. Increased freshwater nutrient flux will also lead to an expansion of the high production, N- and light-limited zones around river deltas, a switch from P- to N-limitation in calcareous marine systems, with large changes in the community composition of fragile mangrove and reef systems. Key information gaps are highlighted, including data on mechanisms of nutrient transport and atmospheric deposition in the tropics, nutrient and material retention capacities of tropical impoundments, and N/P coupling and stoichiometric impacts of nutrient supplies on tropical aquatic communities. The current base of biogeochemical data suggests that alterations in the N-cycle will have greater impacts on tropical aquatic ecosystems than those already observed in the temperate zone.     

Electrochemistry of cytochrome P450 enzyme on nanoparticle-containing membrane-coated electrode and its applications for drug sensing

In the current study, we describe an improved system to study the two-electron delivery reaction pathway of cytochrome P450, family 2, subfamily B, polypeptide 6 (CYP2B6) in vitro. In particular, a biocompatible film containing colloidal gold nanoparticles and chitosan was used to encapsulate CYP2B6 on an electrode. The electrocatalytic behaviors of CYP2B6 toward common drugs in the absence of NADHP-cytochrome P450 reductase as electron donor were studied. In an anaerobic solution, direct and reversible electron transfer between the electroactive heme center of CYP2B6 and the electrode was observed with a formal potential of -0.454 +/- 0.006 V at pH 7.4. In an air-saturated solution, an increase in the bioelectrocatalytic reduction current was observed after drug addition. The bioelectrocatalytic products were analyzed using high-performance liquid chromatography (HPLC) and electrospray ionization-mass spectrometry (ESI-MS). Both results confirmed that C-hydroxylation and heteroatom release were the main pathways for CYP2B6-mediated drug oxidation, similar to what occurred in vivo. The use of immobilized proteins in nanoparticle-containing films in drug biosensing was also demonstrated.     

A novel electrochemical biosensor for selective determination of mercury ions based on DNA hybridization

An electrochemical biosensor was developed for Hg²⁺ determination based on DNA hybridization. In the presence of Hg²⁺, the target and probe DNAs with thymine–thymine (T–T) mismatches could hybridize by forming T–Hg²⁺–T complex. This induced DNA hybridization led to the decrease in reduction peak currents of ethyl green (EG) as electroactive label, which could be used for determination of Hg²⁺. The difference in the value of the peak currents of EG before and after DNA hybridization (ΔI) was linear with the concentration of Hg²⁺ in the range of 9.0 × 10⁻¹¹–1.0 × 10⁻⁹ M. The detection limit was 3.08 × 10⁻¹¹ M.     

Effects of ice and floods on vegetation in streams in cold regions: implications for climate change

Riparian zones support some of the most dynamic and species‐rich plant communities in cold regions. A common conception among plant ecologists is that flooding during the season when plants are dormant generally has little effect on the survival and production of riparian vegetation. We show that winter floods may also be of fundamental importance for the composition of riverine vegetation. We investigated the effects of ice formation on riparian and in‐stream vegetation in northern Sweden using a combination of experiments and observations in 25 reaches, spanning a gradient from ice‐free to ice‐rich reaches. The ice‐rich reaches were characterized by high production of frazil and anchor ice. In a couple of experiments, we exposed riparian vegetation to experimentally induced winter flooding, which reduced the dominant dwarf‐shrub cover and led to colonization of a species‐rich forb‐dominated vegetation. In another experiment, natural winter floods caused by anchor‐ice formation removed plant mimics both in the in‐stream and in the riparian zone, further supporting the result that anchor ice maintains dynamic plant communities. With a warmer winter climate, ice‐induced winter floods may first increase in frequency because of more frequent shifts between freezing and thawing during winter, but further warming and shortening of the winter might make them less common than today. If ice‐induced winter floods become reduced in number because of a warming climate, an important disturbance agent for riparian and in‐stream vegetation will be removed, leading to reduced species richness in streams and rivers in cold regions. Given that such regions are expected to have more plant species in the future because of immigration from the south, the distribution of species richness among habitats can be expected to show novel patterns.     

Effects of microclimate on behavioural and life history traits of terrestrial isopods: implications for responses to climate change

The sensitivity of terrestrial isopods to changes in both temperature and moisture make them suitable models for examining possible responses of arthropod macro-decomposers to predicted climate change. Effects of changes in both temperature and relative humidity on aggregation, growth and survivorship of species of isopods contrasting in their morphological and physiological adaptations to moisture stress have been investigated in laboratory microcosms.All three traits were more sensitive to a reduction in relative humidity of 20–25% than they were to an increase in temperature of 5–6 °C. These results suggest that predicted changes in climate in south east England may reduce the extent to which soil animals stimulate microbial activity and hence carbon dioxide (CO₂) emissions from soils in the future. This may help to mitigate the potential for a positive feedback between increased CO₂ emissions from soils, and increased greenhouse effects causing an increase in soil temperatures.     

Effects of climate‐driven primary production change on marine food webs: implications for fisheries and conservation

Climate change is altering the rate and distribution of primary production in the world's oceans. Primary production is critical to maintaining biodiversity and supporting fishery catches, but predicting the response of populations to primary production change is complicated by predation and competition interactions. We simulated the effects of change in primary production on diverse marine ecosystems across a wide latitudinal range in Australia using the marine food web model Ecosim. We link models of primary production of lower trophic levels (phytoplankton and benthic producers) under climate change with Ecosim to predict changes in fishery catch, fishery value, biomass of animals of conservation interest, and indicators of community composition. Under a plausible climate change scenario, primary production will increase around Australia and generally this benefits fisheries catch and value and leads to increased biomass of threatened marine animals such as turtles and sharks. However, community composition is not strongly affected. Sensitivity analyses indicate overall positive linear responses of functional groups to primary production change. Responses are robust to the ecosystem type and the complexity of the model used. However, model formulations with more complex predation and competition interactions can reverse the expected responses for some species, resulting in catch declines for some fished species and localized declines of turtle and marine mammal populations under primary productivity increases. We conclude that climate‐driven primary production change needs to be considered by marine ecosystem managers and more specifically, that production increases can simultaneously benefit fisheries and conservation. Greater focus on incorporating predation and competition interactions into models will significantly improve the ability to identify species and industries most at risk from climate change.     

Rapid light-induced shifts in opsin expression: finding new opsins, discerning mechanisms of change, and implications for visual sensitivity

Light-induced shifts in cone frequency and opsin expression occur in many aquatic species. Yet little is known about how quickly animals can alter opsin expression and, thereby, track their visual environments. Similarly, little is known about whether adult animals can alter opsin expression or whether shifts in opsin expression are limited to critical developmental windows. We took adult wild-caught bluefin killifish (Lucania goodei) from three different lighting environments (spring, swamp and variable), placed them under two different lighting treatments (clear vs. tea-stained water) and monitored opsin expression over 4 weeks. We measured opsin expression for five previously described opsins (SWS1, SWS2B, SWS2A, RH2-1 and LWS) as well as RH2-2 which we discovered via 454 sequencing. We used two different metrics of opsin expression. We measured expression of each opsin relative to a housekeeping gene and the proportional expression of each opsin relative to the total pool of opsins. Population and lighting environment had large effects on opsin expression which were present at the earliest time points indicating rapid shifts in expression. The two measures of expression produced radically different patterns. Proportional measures indicated large effects of light on SWS1 expression, whereas relative measures indicated no such effect. Instead, light had large effects on the relative expression of SWS2B, RH2-2, RH2-1 and LWS. We suggest that proportional measures of opsin expression are best for making inferences about colour vision, but that measures relative to a housekeeping gene are better for making conclusions about which opsins are differentially regulated.     

环境颜色对异色瓢虫生长发育及繁殖能力的影响

在室内利用不同颜色的饲养容器,对异色瓢虫Harmonia axyridis (Pallas) 生长发育、体长体重变化及繁殖能力进行了比较研究。结果显示：不同环境颜色条件对异色瓢虫幼虫各龄历期均有显著影响; 尽管蛹期受不同颜色影响显著,但其总胚后发育期在各处理间差异不显著。异色瓢虫1龄和2龄幼虫体长增量在不同颜色处理间无显著差异,但3龄幼虫在红色条件下体长增量显著小于其余各处理。不同环境颜色条件下异色瓢虫各虫期体重增量均有显著差异,而4龄幼虫体重增量在各处理中均显著大于其余各虫期,并占总胚后发育期体重增量的50%以上。异色瓢虫成虫的交配持续时间在各处理间无显著差异,但其产卵前期在黄色及绿色条件下显著小于其余各处理。其首堆产卵量在各处理间无显著差异,但在红色及自然光下的48 h累计产卵量均显著小于其余处理。     

Effects of plant traits on ecosystem and regional processes: a conceptual framework for predicting the consequences of global change

Human activities are causing widespread changes in the species composition of natural and managed ecosystems, but the consequences of these changes are poorly understood. This paper presents a conceptual framework for predicting the ecosystem and regional consequences of changes in plant species composition. Changes in species composition have greatest ecological effects when they modify the ecological factors that directly control (and respond to) ecosystem processes. These interactive controls include: functional types of organisms present in the ecosystem; soil resources used by organisms to grow and reproduce; modulators such as microclimate that influence the activity of organisms; disturbance regime; and human activities. Plant traits related to size and growth rate are particularly important because they determine the productive capacity of vegetation and the rates of decomposition and nitrogen mineralization. Because the same plant traits affect most key processes in the cycling of carbon and nutrients, changes in plant traits tend to affect most biogeochemical cycling processes in parallel. Plant traits also have landscape and regional effects through their effects on water and energy exchange and disturbance regime.     

Effects of temperature and ultraviolet radiation on microbial foodweb structure: potential responses to global change

1. A series of growth experiments were conducted with natural plankton communities from a lake and river in northern Quebec, to evaluate the response of microbial foodweb structure to changes in ambient temperature and solar ultraviolet radiation (UVR). 2. Bioassays were incubated for 6 days at two temperatures (10 and 20 °C) and three near-surface irradiance conditions [photosynthetically active radiation (PAR) + UVA + UVB, PAR + UVA, and PAR only). 3. The concentration of total bacteria showed no net response to temperature, but the percentage of actively respiring bacteria, as measured with the cellular redox probe 5-cyano-2,3-ditolyl tetrazolium chloride (CTC), was up to 57% higher at 20 °C relative to 10 °C. Chlorophyll a concentrations in the < 2 μm size fraction also reacted strongly to temperature, with a net increase of up to 61% over the temperature range of 10–20 °C. 4. The UVR effects were small or undetectable for most of the measured variables; however, the percentage of actively respiring bacteria was significantly inhibited in the presence of UVR at 20 °C, decreasing by 29–48% on day 6 in the lake experiments and by 59% on day 2 in one river experiment. 5. The results show differential sensitivity to temperature among organisms of microbial communities in subarctic freshwaters, and a resilience by the majority of micro-organisms to their present UVR conditions. Microbial foodwebs in northern freshwaters appear to be relatively unresponsive to short-term (days) changes in UVR. However, the observed responses to temperature suggest that climate change could influence community structure, with warmer temperatures favouring picoplanktonic phototrophs and heterotrophs, and a shift in nanoplankton species composition and size structure.     

Adaptive management of estuarine resource utilization and wetland conservation based on multi-temporal remote sensing: A case study of Minjiang Estuary,China

Adaptive management of estuarine resource utilization and wetland conservation (ERU&WC) have both socioeconomic and ecological implications because estuaries involve plentiful navigation, aquaculture, wetland, and land-reclamation resources but are featured with complexity and vulnerability of hydrodynamics, morphodynamics, and ecological processes. To achieve positive synergistic effects and prevent disasters by optimizing the allocation of estuarine space to various activities and biological habitats, there is a need to track the estuarine evolutionary trajectories and demarcate the spatial function subareas. However, estuarine field data acquisition is time-consuming, spatially limited, expensive, and there are some areas not accessible due to shallowness or moving sand bars. This paper presents an exact estuarine morphodynamics acquisition and evolution analysis based on multi-temporal remote sensing images, with Minjiang Estuary, China as a case study. The imageries with high tide level (1995, 2017) and low tide level (1995, 2002, 2010, and 2017) were chosen to track the changes of coastline, tidal flat, channel, sand bar, sand island, wetland vegetation, and the spatial heterogeneity of Minjiang Estuary, and the results show visually the section of shoreline change, the pattern of TCSS change and the part of tidal flat vegetation change, which are the fundamental data for demarcating the spatial function subareas. Also, the adaptive management rule was explored, and the schematic diagram of the estuarine morphodynamic evolution process and the framework of ERU&WC adaptive management were outlined. The research result will provide technical support and theoretical guidance for the management of other estuarine environments.