Vertical migration and motility responses in three marine phytoplankton species exposed to solar radiation

Diurnal vertical migration in the water column and the impact of solar radiation on motility were investigated in three marine phytoplankton species: Tetraselmis suecica, Dunaliella salina and Gymnodinium chlorophorum. Cells were exposed to solar radiation either in ultraviolet radiation (UVR, 280-400 nm) transparent Plexiglas tubes (45 cm length, 10 cm diameter) or in quartz tubes under three radiation treatments: PAB (280-700 nm), PA (320-700 nm) and P (400-700 nm). The three species displayed different behavior after exposure to solar radiation. Tetraselmis suecica was insensitive to UVR and under high solar radiation levels, cells accumulated preferentially near the surface. Exposure experiments did not indicate any significant changes in swimming speed nor in the percentage of motile cells after 5 h of exposure. On the other hand, D. salina was sensitive to UV-B displaying a significant decrease in swimming speed and percentage of motile cells after 2-3 h of exposure. Moreover, D. salina cells migrated deep in the water column when irradiance was high. The response of G. chlorophorum was in between that of the other two species tested, with a slight (but significant) decrease in swimming speed and percentage of motile cells in all radiation treatments after 5 h of exposure. While G. chlorophorum cells were more or less homogenously distributed in the water column, a slight (but significant) avoidance response to high radiation was observed at local noon, with cells migrating deep in the water column. Our data clearly indicate that these sub-lethal effects of solar radiation are species-specific and they might have important implications for the aquatic ecosystem.     

Excessive irradiance and antioxidant responses of an Antarctic marine diatom exposed to iron limitation and to dynamic irradiance

The synergistic effects of iron limitation and irradiance dynamics on growth, photosynthesis, antioxidant activity and excessive PAR (400-700 nm) and UV (280-400 nm) sensitivity were investigated for the Antarctic marine diatom Chaetoceros brevis. Iron-limited and iron-replete cultures were exposed to identical daily irradiance levels, supplied as dynamic (20-1350 micromol m(-2) s(-1)) and constant (260 micromol m(-2) s(-1)) irradiance. After acclimation, growth, maximal quantum yield of PSII (F(v)/F(m)), pigment composition, and the activities of the antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) were determined. Then, excessive irradiance sensitivity was assessed by monitoring pigment composition, F(v)/F(m) and viability loss during a single excessive PAR and UV treatment. Iron limitation reduced growth rates, F(v)/F(m) dynamics, and cellular pigments pools. Cellular pigment concentrations were higher under dynamic irradiance than under constant irradiance but this difference was less pronounced under iron limitation compared to iron-replete conditions. SOD and APX activities increased during dynamic irradiance under iron limitation, suggesting increased radical formation around PSII. Despite these physiological differences, no effects on growth were observed between constant and dynamic irradiance cultivation in iron-limited and iron-replete cells. The applied culturing conditions did not affect glutathione reductase activity in C. brevis. F(v)/F(m) and xanthophyll de-epoxidation dynamics during excessive irradiance were not different for iron-limited and replete cells and viability loss was not found during excessive irradiance. This study revealed photoacclimation differences between iron-limited and iron-replete C. brevis cultures that did not affect growth rates and excessive irradiance sensitivity after acclimation to constant and dynamic irradiance.     

Iterative high-throughput polymorphism studies on acetaminophen and an experimentally derived structure for form III

Three crystal forms of acetaminophen were prepared and characterized using a newly developed high-throughput crystallization platform, CrystalMax. The platform consists of design software, robotic sample dispensing and handling, and high-throughput microanalytics and is capable of running thousands of crystallizations in parallel using several different methods to drive supersaturation and subsequent crystallization. Additionally, structural models of the elusive third form of acetaminophen will be discussed on the basis of powder X-ray diffraction data. One structure suggested has a bilayer motif, held together by O-H...O(H) hydrogen bonds, and helps explain the difficulty associated with preparing this form from solution.     

Biofouling studies on nanoparticle-based metal oxide coatings on glass coupons exposed to marine environment

Titania, niobia and silica coatings, derived from their respective nanoparticle dispersions or sols and fabricated on soda lime glass substrates were subjected to field testing in marine environment for antimacrofouling applications for marine optical instruments. Settlement and enumeration of macrofouling organisms like barnacles, hydroides and oysters on these nanoparticle-based metal oxide coatings subjected to different heat treatments up to 400 °C were periodically monitored for a period of 15 days. The differences observed in the antifouling behaviour between the coated and uncoated substrates are discussed based on the solar ultraviolet light induced photocatalytic activities as well as hydrophilicities of the coatings in case of titania and niobia coatings and the inherent hydrophilicity in the case of silica coating. The effect of heat treatment on the photocatalytic activity of the coatings is also discussed.     

Effect of photosensitizer dose on fluence rate responses to photodynamic therapy

Photodynamic therapy (PDT) regimens that conserve tumor oxygenation are typically more efficacious, but require longer treatment times. This makes them clinically unfavorable. In this report, the inverse pairing of fluence rate and photosensitizer dose is investigated as a means of controlling oxygen depletion and benefiting therapeutic response to PDT under conditions of constant treatment time. Studies were performed for Photofrin-PDT of radiation-induced fibrosarcoma tumors over fluence rate and drug dose ranges of 25-225 mW cm(-2) and 2.5-10 mg kg(-1), respectively, for 30 min of treatment. Tumor response was similar among all inverse regimens tested, and, in general, tumor hemoglobin oxygen saturation (SO2) was well conserved during PDT, although the highest fluence rate regimen (225 mWx2.5 mg) did lead to a modest but significant reduction in SO2. Regardless, significant direct tumor cell kill (>1 log) was detected during 225 mWx2.5 mg PDT, and minimal normal tissue toxicity was found. PDT effect on tumor oxygenation was highly associated with tumor response at 225 mWx2.5 mg, as well as in all other regimens tested. These data suggest that high fluence rate PDT can be carried out under oxygen-conserving, efficacious conditions at low photosensitizer dose. Clinical confirmation and application of these results will be possible through use of minimally invasive oxygen and photosensitizer monitoring technologies, which are currently under development.     

Determination of tributyltin oxide in coastal marine sediments and mussels by electrothermal atomic absorption spectrometry

We have devised a new method for bis(tributyltin)oxide (TBTO) determination in marine sediments and mussels. This technique involves an n-hexane/methylene chloride mixture extraction and extract purification with a sodium hydroxide wash in order to eliminate interfering compounds. TBTO is then extracted again by nitric acid and converted into an inorganic tin species; the analysis has been effected using Zeeman graphite furnace-atomic absorption spectrophotometry. The method detection limit for the matrices examined is 0.004 μg TBTO g^?1 (wet weight) and is sufficient for the analysis in real samples. The percentage recovery of TBTO from sediments and mussels samples is higher than 85% and 95% respectively. This method has been applied to TBTO level determination in sediments and mussels (Mytilus galloprovincialis) sampled in the harbour area in Taranto, where mussel culture activities are much developed; the TBTO levels obtained in sediments and mussels were in the range 15-47 ng g^?1 (wet weight) and 11-30 ng g^?1 (wet weight) respectively. Such values are comparable with those found in other harbour areas in the Mediterranean Sea.     

Novel biomarker pipeline to probe the oxidation sites and oxidation degrees of hemoglobin in bovine erythrocytes exposed to oxidative stress

Research on biomarkers for protein oxidation might give insight into the mechanistic mode of oxidative stress. In the work present here, a novel pipeline was established to probe the oxidation mechanism of bovine hemoglobin (Hb) with its oxidation products serving as the biomarkers. Reactive oxygen species generated by irradiation were used to mimic oxidative stress conditions to oxidize Hb in bovine erythrocytes. After Hb extraction and digestion, oxidized peptides in the tryptic fragments were assigned by comparison with the extracted ion chromatography spectra of native peptide from the control sample. Subsequent tandem mass spectrometry analysis of these peptides proved that oxidation was limited to partially exposed amino acid residues (α‐Phe₃₆, β‐Met₁, β‐Trp₁₄, for instance) in Hb. Quantitation analysis on these oxidized peptides showed that oxidation degrees of target sites had positive correlations with the extended oxidation dose and the oxidation processes were also controlled by residues types. Compared with the conventional protein carbonyl assay, the identified oxidized products were feasibility biomarkers for Hb oxidation, indicating that the proposed biomarker pipeline was suitable to provide specific and valid information for protein oxidation. Copyright © 2015 John Wiley & Sons, Ltd.     

Effects of alcohols on fluorescence intensity and color of a discharged-obelin-based biomarker

Photoproteins are responsible for bioluminescence of marine coelenterates; bioluminescent and fluorescent biomarkers based on photoproteins are useful for monitoring of calcium-dependent processes in medical investigations. Here, we present the analysis of intensity and color of light-induced fluorescence of Ca²⁺-discharged photoprotein obelin in the presence of alcohols (ethanol and glycerol). Complex obelin spectra obtained at different concentrations of the alcohols at 350- and 280-nm excitation (corresponding to polypeptide-bound coelenteramide and tryptophan absorption regions) were deconvoluted into Gaussian components; fluorescent intensity and contributions of the components to experimental spectra were analyzed. Five Gaussian components were found in different spectral regions—ultraviolet (tryptophan emission), blue-green (coelenteramide emission), and red (hypothetical indole-coelenteramide exciplex emission). Inhibition coefficients and contributions of the components to experimental fluorescent spectra showed that presence of alcohols increased contributions of ultraviolet, violet, and red components, but decreased contributions of components in the blue-green region. The effects were related to (1) changes of proton transfer efficiency in fluorescent S*₁ state of coelenteramide in the obelin active center and (2) formation of indole-coelenteramide exciplex at 280-nm photoexcitation. The data show that variation of fluorescence color and intensity in the presence of alcohols and dependence of emission spectra on excitation wavelength should be considered while applying the discharged obelin as a fluorescence biomarker.     

Effects of confined geometry on phase-separated dextran/gelatine mixtures exposed to shear

The effect of shear on aqueous phase-separated dextran/fish gelatine mixtures with a total concentration of 5 and 10% was studied in a confined geometry. It was measured as a function of composition, strain rate and gap size. This was done by using both small-angle light scattering and a shear cell combined with a confocal laser scanning microscope. At a total polymer concentration of 5%, small-angle light scattering results showed that up to 100 s(-1) the deformation of the domains increases with the strain rate. At strain rates less than 100 s(-1), the response of the system to strain is dominated by strain rate-dependent deformation. At a higher strain rate there might be balance between break-up and re-coalescence. At a total concentration of 10%, small effects of the gap size were found. In confined geometry, the coalescence rate was faster than expected from viscous hydrodynamic growth. The microscope images showed that the gelatine-enriched phase forms a wetting layer on the surface of the glass wall. The degree of wetting appears to increase with increasing the strain rate up to 60 s(-1) and decreases again at higher strain rates.     

Concentrations of rare earth elements in sediments,mussels and fish from a Danish marine environment,Lillebaelt

Results for the content of the rare earth elements (REE), La, Ce, Nd, Sm, Eu, Tb, Yb and Lu in sediments, mussels and fish are presented for an area polluted by REE. The REE are emitted with the process waste water stream from a fertilizer production plant. The method of analysis has been INAA. An attempt to combine the INAA with a simple destruction/preconcentration method is described.     

Effect of preillumination on photomotile responses of the marine ciliate Fabrea salina

Fabrea salina is a marine ciliate that shows photomotile responses such as positive phototaxis and a step-down photophobic reaction. We found that preilluminated F. salina cells show a phototactic response significantly greater than that of dark-adapted cells when exposed to the same phototactic light stimulus. In particular, positive phototaxis is strongly enhanced by preillumination. This enhancement effect depends on the preillumination light irradiance, on the total preillumination dose, and on the duration of the dark interval between preillumination and the phototaxis measurement. Our results show that the determining factor is the total preillumination dose given to the sample. The enhancement effect shows an asymptotic behavior over a certain range of energy values (10-200 W/m2). Further, the effect is transient; after 120 s in the dark, the cells lose any memory of the preillumination, independent of the preillumination energy received. These results are tentatively discussed in terms of light-driven membrane potential or membrane channel conductances.     

Effects of environmental oestrogens on marine fish species

This article considers methods for the detection of oestrogenic effects in marine fish. As a marker for oestrogenic effects, plasma vitellogenin was determined in Atlantic cod, Atlantic salmon and goldsinny wrasse using ELISA with homologous or heterologous antisera. The sensitivity of marine fish to oestrogen exposure is species-dependent and cod is a suitable species for monitoring the effects of environmental oestrogens.     

Optical and electrochemical responses of an anthrax biomarker based on single-walled carbon nanotubes covalently loaded with terbium complexes

An effective single-walled carbon nanotube (SWNT) covalently loaded with unsaturated terbium emissive material was designed for specific and rapid (2-3 s) detection of calcium dipicolinate (CaDPA) (detection limit 1 μM). The nanoprobe was successfully assembled onto electrodes and its sensing abilities were investigated through electrochemical measurement. Cyclic voltammetry curves were selectively responsive to calcium dipicolinate compared with benzoic acid, o-phthalic acid and m-phthalic acid. This novel material provides dual opto-electrochemical recognition of the anthrax biomarker CaDPA.     

Occurrence of venlafaxine residues and its metabolites in marine mussels at trace levels: development of analytical method and a monitoring program

Coastal areas are subject to growing pressures and impacts because of the increase in human activities. Lipophilic organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) or polychlorinated biphenyls (PCBs), have been monitored for decades within monitoring programs. However, until now, little information on the detection of so-called “emerging contaminants” such as hydrophilic organic compounds in the marine environment and no data on its metabolites or transformation products in marine organisms is available. In this report, a sensitive analytical methodology for identification and confirmation of venlafaxine (VEN) residues and five of its main metabolites in the marine mussels Mytilus galloprovincialis was validated. The sample preparation procedure was based on the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) approach. An analytical method was developed to quantify these compounds at trace levels by liquid chromatography coupled to high-resolution mass spectrometry. The method was then applied to marine mussels collected from the Mediterranean Sea in southeastern France. Residues of the antidepressant VEN were occasionally detected at ng/g dw level. In addition, the approach allowed us to identify several transformation products in the analyzed samples. N-desmethylvenlafaxine (NDV) was the most frequently detected metabolite followed by N,O-di-desmethylvenlafaxine (NODDV).

Electrochemical determination of acetaminophen in the presence of propranolol using an electrode modified with a Schiff base from 2-hydroxy-1-naphthaldehyde and ethylenediamine and multi-walled carbon nanotubes

A carbon paste electrode, modified with N,N′-bis-(2-hydroxy-1-naphthalidene)ethylenediamine and multi-walled carbon nanotubes (HNED-MWCNPE), was used for the determination of acetaminophen (ACOP) and propranolol (PP). Cyclic voltammetry (CV), chronocoulometry, chronoamperometry and differential pulse voltammetry (DPV) techniques were employed to study electro-oxidation of ACOP. The results revealed that the modified electrode showed an electrocatalytic activity toward the anodic oxidation of acetaminophen by a marked enhancement in the current response in buffered solution at pH 8.0. Some kinetic parameters such as the electron transfer coefficient (α) were also determined for the ACOP oxidation. The linear concentration range of 1 × 10^?3?1 × 10^?6 M with a detection limit of 4.6 × 10^?8 M (n = 16) for ACOP was obtained using DPV (pH 8.0). The modified electrode shows good sensitivity, selectivity and stability. The prepared electrode was also applied for the determination of ACOP in human blood serum.     

Effects of chronic ethanol feeding on the protein composition of mitochondrial ribosomes

Chronic ethanol feeding has been shown to decrease the number of functionally active mitochondrial ribosomes by 55%. In this work, 55S mitochondrial ribosomes were isolated from rat liver and their constitutive proteins characterized by two-dimensional polyacrylamide gel electrophoresis and quantified by densitometry. A total of 86 proteins were found to be associated with the mitochondrial ribosome. This compares with 70 isolated from cytoplasmic ribosomes. In addition, mitochondrial ribosomal proteins were found to be significantly less basic than their cytoplasmic counterparts. Chronic ethanol feeding was found to significantly decrease the levels of a number of constitutive proteins of the mitochondrial ribosome when compared to those isolated from pair-fed controls. Sucrose density gradient analyses revealed a significant decrease in the number of intact 55S ribosomes. It is suggested that ethanol-elicited alterations in specific constitutive proteins of the mitochondrial ribosome may lead to impaired assembly of the monosome and that this may result in lower levels of those displaying functional activity.     

Effects of acid etching on the structure of PtNi catalyst and total exposed active sites

The integration technology of hydrogen preparation–hydrogen storage not only can utilize hydrogen energy efficiently but also can improve the selectivity of the electrode maximally. In the present work, the structure and composition of the PtNi catalyst was characterized by X-ray diffraction (XRD); and its electrochemical properties, morphology, and surface binding energy were analyzed by cyclic voltammetry (CV) and linear scanning voltammetry (LSV), scanning electron microscopy equipped with energy-dispersive spectrometry (SEM-EDS), and X-ray photoelectron spectroscopy (XPS), respectively. The effects of different acid etching treatments (e.g., etching time, etchant concentration, and etching temperature) on the structure and surface active sites were investigated by the orthogonal experiment. The experimental results reveal that after etching with 0.5 mol/L of perchloric acid for 0.5 h at 60°C, the electrode weight loss of the PtNi catalyst is mainly attributed to the large loss of Ni atoms in film layer. This results in the reduced alloy phase in film layer and the appearance of Pt characteristic diffraction peak. The relative content of Pt on the surface of the film electrode increases significantly, and the total number of active sites also increases correspondingly. The binding energy of Pt4f_7/2 decreases by 0.19 eV, and the number of active sites involved in hydrogen release decreases, indicative of the reduced promotion effect of the PtNi catalyst on hydrogen release.     

Atomic absorption spectrometric screening and gas chromatographic-mass spectrometric determination of organotin compounds in marine mussels: an application in samples from the Venetian Lagoon

A new analytical approach for the determination of organotin compounds (OTC) in mussel samples has been developed and evaluated. A preliminary step, performed by graphite furnace atomic absorption spectrometry (GFAAS) for the total tin determination may be followed by gas chromatographic-mass spectrometric (GC/ MS) speciation only for the characterization of those samples exhibiting total tin concentration higher than 30 ng/g wet weight (GFAAS limit of detection). The GFAAS method was optimized using Pd nitrate under reducing conditions as matrix modifier to minimize NaCl interferences. Organotins were derivatized with a Grignard reagent for GC/MS analysis (TBT limit of detection = 80 ng/g). An application of this strategy was performed on mussel samples collected from the Venetian Lagoon.