Ethanol Production from Colpomenia sinuosa by an Alginate Fermentation Strain Meyerozyma guilliermondii

With the consumption of energy and the spread of COVID-19, the demand for ethanol production is increasing in the world. The industrial ethanol fermentation microbes cannot metabolize the alginate component of macro algae, which affects the ethanol yield. In this research, the ethanol production process from macro algae by an alginate fermentation yeast Meyerozyma guilliermondii, especially the pretreatment process of Colpomenia sinuosa, was studied. At the same time, the experimental design of Box-Behnken was carried out to achieve the optimum fermentation performance. The concentration of KH₂PO₄ (A: 2–6 g.L⁻¹), pH (B: 4–7), reaction time (C: 60–120 h) and temperature (D: 24–34 °C) were variable input parameters. During the ethanol production process, the algae powder was firstly mixed with water at 90 °C for 0.5 h. Later the fermentation culture medium was prepared and then it was fermented by the yeast Meyerozyma guilliermondii to produce ethanol. And the optimal fermentation parameters were as follows: fermentation temperature of 28 °C, KH₂PO₄ dosage of 4.7 g.L⁻¹, initial pH of 6, and fermentation time of 99 h. The ethanol yield reached 0.268 g.g⁻¹ (ethanol to algae), close to the predicted value of model. The generation of alginate lyase during the fermentation of algae was also examined. The highest alginate lyase activity reached 46.42 U.mL⁻¹.     

Decadal Changes in the World's Coastal Latitudinal Temperature Gradients

Most of the world''s living marine resources inhabit coastal environments, where average thermal conditions change predictably with latitude. These coastal latitudinal temperature gradients (CLTG) coincide with important ecological clines,e.g., in marine species diversity or adaptive genetic variations, but how tightly thermal and ecological gradients are linked remains unclear. A first step is to consistently characterize the world''s CLTGs. We extracted coastal cells from a global 1°×1° dataset of weekly sea surface temperatures (SST, 1982–2012) to quantify spatial and temporal variability of the world''s 11 major CLTGs. Gradient strength, i.e., the slope of the linear mean-SST/latitude relationship, varied 3-fold between the steepest (North-American Atlantic and Asian Pacific gradients: −0.91°C and −0.68°C lat⁻¹, respectively) and weakest CLTGs (African Indian Ocean and the South- and North-American Pacific gradients: −0.28, −0.29, −0.32°C lat⁻¹, respectively). Analyzing CLTG strength by year revealed that seven gradients have weakened by 3–10% over the past three decades due to increased warming at high compared to low latitudes. Almost the entire South-American Pacific gradient (6–47°S), however, has considerably cooled over the study period (−0.3 to −1.7°C, 31 years), and the substantial weakening of the North-American Atlantic gradient (−10%) was due to warming at high latitudes (42–60°N, +0.8 to +1.6°C,31 years) and significant mid-latitude cooling (Florida to Cape Hatteras 26–35°N, −0.5 to −2.2°C, 31 years). Average SST trends rarely resulted from uniform shifts throughout the year; instead individual seasonal warming or cooling patterns elicited the observed changes in annual means. This is consistent with our finding of increased seasonality (i.e., summer-winter SST amplitude) in three quarters of all coastal cells (331 of 433). Our study highlights the regionally variable footprint of global climate change, while emphasizing ecological implications of changing CLTGs, which are likely driving observed spatial and temporal clines in coastal marine life.     

Isolation and Characterization of Carbendazim-degrading Rhodococcus erythropolis djl-11

Carbendazim (methyl 1H-benzimidazol-2-yl carbamate) is one of the most widely used fungicides in agriculture worldwide, but has been reported to have adverse effects on animal health and ecosystem function. A highly efficient carbendazim-degrading bacterium (strain dj1-11) was isolated from carbendazim-contaminated soil samples via enrichment culture. Strain dj1-11 was identified as Rhodococcus erythropolis based on morphological, physiological and biochemical characters, including sequence analysis of the 16S rRNA gene. In vitro degradation of carbendazim (1000 mg·L⁻¹) by dj1-11 in minimal salts medium (MSM) was highly efficient, and with an average degradation rate of 333.33 mg·L⁻¹·d⁻¹ at 28°C. The optimal temperature range for carbendazim degradation by dj1-11 in MSM was 25–30°C. Whilst strain dj1-11 was capable of metabolizing cabendazim as the sole source of carbon and nitrogen, degradation was significantly (P<0.05) increased by addition of 12.5 mM NH₄NO₃. Changes in MSM pH (4–9), substitution of NH₄NO₃ with organic substrates as N and C sources or replacing Mg²⁺ with Mn²⁺, Zn²⁺ or Fe²⁺ did not significantly affect carbendazim degradation by dj1-11. During the degradation process, liquid chromatography-mass spectrometry (LC-MS) detected the metabolites 2-aminobenzimidazole and 2-hydroxybenzimidazole. A putative carbendazim-hydrolyzing esterase gene was cloned from chromosomal DNA of djl-11 and showed 99% sequence homology to the mheI carbendazim-hydrolyzing esterase gene from Nocardioides sp. SG-4G.     

Growth and Nitrogen Uptake Kinetics in Cultured Prorocentrum donghaiense

We compared growth kinetics of Prorocentrum donghaiense cultures on different nitrogen (N) compounds including nitrate (NO₃ ⁻), ammonium (NH₄ ⁺), urea, glutamic acid (glu), dialanine (diala) and cyanate. P. donghaiense exhibited standard Monod-type growth kinetics over a range of N concentraions (0.5–500 μmol N L⁻¹ for NO₃ ⁻ and NH₄ ⁺, 0.5–50 μmol N L⁻¹ for urea, 0.5–100 μmol N L⁻¹ for glu and cyanate, and 0.5–200 μmol N L⁻¹ for diala) for all of the N compounds tested. Cultures grown on glu and urea had the highest maximum growth rates (μ_m, 1.51±0.06 d⁻¹ and 1.50±0.05 d⁻¹, respectively). However, cultures grown on cyanate, NO₃ ⁻, and NH₄ ⁺ had lower half saturation constants (K_μ, 0.28–0.51 μmol N L⁻¹). N uptake kinetics were measured in NO₃ ⁻-deplete and -replete batch cultures of P. donghaiense. In NO₃ ⁻-deplete batch cultures, P. donghaiense exhibited Michaelis-Menten type uptake kinetics for NO₃ ⁻, NH₄ ⁺, urea and algal amino acids; uptake was saturated at or below 50 μmol N L⁻¹. In NO₃ ⁻-replete batch cultures, NH₄ ⁺, urea, and algal amino acid uptake kinetics were similar to those measured in NO₃ ⁻-deplete batch cultures. Together, our results demonstrate that P. donghaiense can grow well on a variety of N sources, and exhibits similar uptake kinetics under both nutrient replete and deplete conditions. This may be an important factor facilitating their growth during bloom initiation and development in N-enriched estuaries where many algae compete for bioavailable N and the nutrient environment changes as a result of algal growth.     

An Unaccounted Fraction of Marine Biogenic CaCO3 Particles

Biogenic production and sedimentation of calcium carbonate in the ocean, referred to as the carbonate pump, has profound implications for the ocean carbon cycle, and relate both to global climate, ocean acidification and the geological past. In marine pelagic environments coccolithophores, foraminifera and pteropods have been considered the main calcifying organisms. Here, we document the presence of an abundant, previously unaccounted fraction of marine calcium carbonate particles in seawater, presumably formed by bacteria or in relation to extracellular polymeric substances. The particles occur in a variety of different morphologies, in a size range from <1 to >100 µm, and in a typical concentration of 10⁴–10⁵ particles L⁻¹ (size range counted 1–100 µm). Quantitative estimates of annual averages suggests that the pure calcium particles we counted in the 1–100 µm size range account for 2–4 times more CaCO₃ than the dominating coccolithophoride Emiliania huxleyi and for 21% of the total concentration of particulate calcium. Due to their high density, we hypothesize that the particles sediment rapidly, and therefore contribute significantly to the export of carbon and alkalinity from surface waters. The biological and environmental factors affecting the formation of these particles and possible impact of this process on global atmospheric CO₂ remains to be investigated.     

Influence of wastewater composition on nutrient removal behaviors in the new anaerobic–anoxic/nitrifying/induced crystallization process

In this study, the new anaerobic–anoxic/nitrifying/induced crystallization (A₂N–IC) system was compared with anaerobic-anoxic/nitrifying (A₂N) process to investigate nutrient removal performance under different influent COD and ammonia concentrations. Ammonia and COD removal rates were very stable in both processes, which were maintained at 84.9% and 86.6% when the influent ammonia varied from 30 mg L⁻¹ to 45 mg L⁻¹ and COD ranged from 250 mg L⁻¹ to 300 mg L⁻¹. The effluent phosphorus always maintained below 0.2 mg L⁻¹ in A₂N–IC, whereas in A₂N the effluent phosphorus concentration was 0.4–1.7 mg L⁻¹, demonstrating that A₂N–IC is suitable to apply in a broader influent COD and ammonia concentration range. Under higher influent COD (300 mg L⁻¹) or lower ammonia conditions (30 mg L⁻¹), the main function of chemical induced crystallization was to coordinate better nutrient ratio for anoxic phosphorus uptake, whereas under high phosphorus concentration, it was to reduce phosphorus loading for biological system. Under the similar influent wastewater compositions, phosphorus release amounts were always lower in A₂N–IC. To clarify the decrease procedure of phosphorus release in the A₂N–IC, the equilibrium between chemical phosphorus removal and biological phosphorus removal in A₂N–IC was analyzed by mass balance equations. During the long-term experiment, some undesirable phenomena were observed: the declining nitrification in post-aerobic tank and calcium phosphorus precipitation in the anaerobic tank. The reasons were analyzed; furthermore, the corresponding improvements were proposed. Nitrification effect could be enhanced in the post-aerobic tank, therefore ammonia removal rate could be increased; and biologically induced phosphorus precipitation could be inhibited by controlling pH at the anaerobic stage, so the phosphorus release and recovery could be improved.     

A New Highly Sensitive Method to Assess Respiration Rates and Kinetics of Natural Planktonic Communities by Use of the Switchable Trace Oxygen Sensor and Reduced Oxygen Concentrations

Oxygen respiration rates in pelagic environments are often difficult to quantify as the resolutions of our methods for O₂ concentration determination are marginal for observing significant decreases during bottle incubations of less than 24 hours. Here we present the assessment of a new highly sensitive method, that combine Switchable Trace Oxygen (STOX) sensors and all-glass bottle incubations, where the O₂ concentration was artificially lowered. The detection limit of respiration rate by this method is inversely proportional to the O₂ concentration, down to <2 nmol L⁻¹ h⁻¹ for water with an initial O₂ concentration of 500 nmol L⁻¹. The method was tested in Danish coastal waters and in oceanic hypoxic waters. It proved to give precise measurements also with low oxygen consumption rates (∼7 nmol L⁻¹ h⁻¹), and to significantly decrease the time required for incubations (≤14 hours) compared to traditional methods. This method provides continuous real time measurements, allowing for a number of diverse possibilities, such as modeling the rate of oxygen decrease to obtain kinetic parameters. Our data revealed apparent half-saturation concentrations (K_m values) one order of magnitude lower than previously reported for marine bacteria, varying between 66 and 234 nmol L⁻¹ O₂. K_m values vary between different microbial planktonic communities, but our data show that it is possible to measure reliable respiration rates at concentrations ∼0.5–1 µmol L⁻¹ O₂ that are comparable to the ones measured at full air saturation.     

Interaction of Sulforaphane with DNA and RNA

Sulforaphane (SFN) is an isothiocyanate found in cruciferous vegetables with anti-inflammatory, anti-oxidant and anti-cancer activities. However, the antioxidant and anticancer mechanism of sulforaphane is not well understood. In the present research, we reported binding modes, binding constants and stability of SFN–DNA and -RNA complexes by Fourier transform infrared (FTIR) and UV–Visible spectroscopic methods. Spectroscopic evidence showed DNA intercalation with some degree of groove binding. SFN binds minor and major grooves of DNA and backbone phosphate (PO₂), while RNA binding is through G, U, A bases with some degree of SFN–phosphate (PO₂) interaction. Overall binding constants were estimated to be K_(SFN–DNA)=3.01 (± 0.035)×10⁴ M^-1 and K_(SFN–RNA)= 6.63 (±0.042)×10³ M^-1. At high SFN concentration (SFN/RNA = 1/1), DNA conformation changed from B to A occurred, while RNA remained in A-family structure.     

Influence of Prior Exercise on VO2 Kinetics Subsequent Exhaustive Rowing Performance

Prior exercise has the potential to enhance subsequent performance by accelerating the oxygen uptake (VO₂) kinetics. The present study investigated the effects of two different intensities of prior exercise on pulmonary VO₂ kinetics and exercise time during subsequent exhaustive rowing exercise. It was hypothesized that in prior heavy, but not prior moderate exercise condition, overall VO₂ kinetics would be faster and the VO₂ primary amplitude would be higher, leading to longer exercise time at VO_2max. Six subjects (mean ± SD; age: 22.9±4.5 yr; height: 181.2±7.1 cm and body mass: 75.5±3.4 kg) completed square-wave transitions to 100% of VO_2max from three different conditions: without prior exercise, with prior moderate and heavy exercise. VO₂ was measured using a telemetric portable gas analyser (K4b², Cosmed, Rome, Italy) and the data were modelled using either mono or double exponential fittings. The use of prior moderate exercise resulted in a faster VO₂ pulmonary kinetics response (τ₁ = 13.41±3.96 s), an improved performance in the time to exhaustion (238.8±50.2 s) and similar blood lactate concentrations ([La⁻]) values (11.8±1.7 mmol.L⁻¹) compared to the condition without prior exercise (16.0±5.56 s, 215.3±60.1 s and 10.7±1.2 mmol.L⁻¹, for τ₁, time sustained at VO_2max and [La⁻], respectively). Performance of prior heavy exercise, although useful in accelerating the VO₂ pulmonary kinetics response during a subsequent time to exhaustion exercise (τ₁ = 9.18±1.60 s), resulted in a shorter time sustained at VO_2max (155.5±46.0 s), while [La⁻] was similar (13.5±1.7 mmol.L⁻¹) compared to the other two conditions. Although both prior moderate and heavy exercise resulted in a faster pulmonary VO₂ kinetics response, only prior moderate exercise lead to improved rowing performance.     

Aphotic N2 Fixation in the Eastern Tropical South Pacific Ocean

We examined rates of N₂ fixation from the surface to 2000 m depth in the Eastern Tropical South Pacific (ETSP) during El Niño (2010) and La Niña (2011). Replicated vertical profiles performed under oxygen-free conditions show that N₂ fixation takes place both in euphotic and aphotic waters, with rates reaching 155 to 509 µmol N m⁻² d⁻¹ in 2010 and 24±14 to 118±87 µmol N m⁻² d⁻¹ in 2011. In the aphotic layers, volumetric N₂ fixation rates were relatively low (<1.00 nmol N L⁻¹ d⁻¹), but when integrated over the whole aphotic layer, they accounted for 87–90% of total rates (euphotic+aphotic) for the two cruises. Phylogenetic studies performed in microcosms experiments confirm the presence of diazotrophs in the deep waters of the Oxygen Minimum Zone (OMZ), which were comprised of non-cyanobacterial diazotrophs affiliated with nifH clusters 1K (predominantly comprised of α-proteobacteria), 1G (predominantly comprised of γ-proteobacteria), and 3 (sulfate reducing genera of the δ-proteobacteria and Clostridium spp., Vibrio spp.). Organic and inorganic nutrient addition bioassays revealed that amino acids significantly stimulated N₂ fixation in the core of the OMZ at all stations tested and as did simple carbohydrates at stations located nearest the coast of Peru/Chile. The episodic supply of these substrates from upper layers are hypothesized to explain the observed variability of N₂ fixation in the ETSP.     

Microbial Degradation of Acetamiprid by Ochrobactrum sp. D-12 Isolated from Contaminated Soil

Neonicotinoid insecticides are one of the most important commercial insecticides used worldwide. The potential toxicity of the residues present in environment to humans has received considerable attention. In this study, a novel Ochrobactrum sp. strain D-12 capable of using acetamiprid as the sole carbon source as well as energy, nitrogen source for growth was isolated and identified from polluted agricultural soil. Strain D-12 was able to completely degrade acetamiprid with initial concentrations of 0–3000 mg·L⁻¹ within 48 h. Haldane inhibition model was used to fit the special degradation rate at different initial concentrations, and the parameters q _max, K _s and K _i were determined to be 0.6394 (6 h)⁻¹, 50.96 mg·L⁻¹ and 1879 mg·L⁻¹, respectively. The strain was found highly effective in degrading acetamiprid over a wide range of temperatures (25–35°C) and pH (6–8). The effects of co-substrates on the degradation efficiency of acetamiprid were investigated. The results indicated that exogenously supplied glucose and ammonium chloride could slightly enhance the biodegradation efficiency, but even more addition of glucose or ammonium chloride delayed the biodegradation. In addition, one metabolic intermediate identified as N-methyl-(6-chloro-3-pyridyl)methylamine formed during the degradation of acetamiprid mediated by strain D-12 was captured by LC-MS, allowing a degradation pathway for acetamiprid to be proposed. This study suggests the bacterium could be a promising candidate for remediation of environments affected by acetamiprid.     

Direct Determination of Carbon and Nitrogen Contents of Natural Bacterial Assemblages in Marine Environments

In order to better estimate bacterial biomass in marine environments, we developed a novel technique for direct measurement of carbon and nitrogen contents of natural bacterial assemblages. Bacterial cells were separated from phytoplankton and detritus with glass fiber and membrane filters (pore size, 0.8 μm) and then concentrated by tangential flow filtration. The concentrate was used for the determination of amounts of organic carbon and nitrogen by a high-temperature catalytic oxidation method, and after it was stained with 4′,6-diamidino-2-phenylindole, cell abundance was determined by epifluorescence microscopy. We found that the average contents of carbon and nitrogen for oceanic bacterial assemblages were 12.4 ± 6.3 and 2.1 ± 1.1 fg cell⁻¹ (mean ± standard deviation; n = 6), respectively. Corresponding values for coastal bacterial assemblages were 30.2 ± 12.3 fg of C cell⁻¹ and 5.8 ± 1.5 fg of N cell⁻¹ (n = 5), significantly higher than those for oceanic bacteria (two-tailed Student’s t test; P < 0.03). There was no significant difference (P > 0.2) in the bacterial C:N ratio (atom atom⁻¹) between oceanic (6.8 ± 1.2) and coastal (5.9 ± 1.1) assemblages. Our estimates support the previous proposition that bacteria contribute substantially to total biomass in marine environments, but they also suggest that the use of a single conversion factor for diverse marine environments can lead to large errors in assessing the role of bacteria in food webs and biogeochemical cycles. The use of a factor, 20 fg of C cell⁻¹, which has been widely adopted in recent studies may result in the overestimation (by as much as 330%) of bacterial biomass in open oceans and in the underestimation (by as much as 40%) of bacterial biomass in coastal environments.     

Perfusion Method for Assaying Microbial Activities in Sediments: Applicability to Studies of N2 Fixation by C2H2 Reduction

A perfusion method for assaying nitrogenase activity (acetylene reduction) in marine sediments was developed. The method was used to assay sediment cores from Spartina alterniflora (salt marsh), Zostera marina (sea grass), and Thalassia testudinum (sea grass) communities, and the results were compared with those of conventional sealed-flask assays. Rates of ethylene production increased progressively with time in the perfusion assays, reaching plateau values of 2 to 3 nmol · g of dry sediment⁻¹ · h⁻¹ by 10 to 20 h. Depletion of interstitial NH₄⁺ was implicated in this stimulation of nitrogenase activity. Initial acetylene reduction rates determined by the perfusion assay of cores from the Spartina community ranged from 0.15 to 0.60 nmol of C₂H₄ · g of dry sediment⁻¹ · h⁻¹. These rates were similar to those for sediments assayed in sealed flasks without seawater when determined over linear periods of C₂H₄ production. Initial values obtained by using the perfusion method were 0.66 nmol of C₂H₄ · g of dry sediment⁻¹ · h⁻¹ for sediments from Zostera communities and 0.70 nmol of C₂H₄ · g of dry sediment⁻¹ · h⁻¹ for sediments from Thalassia communities. In all cases, rates determined by simultaneous slurry assays were lower than those determined by the perfusion method.     

Validity of Cooper’s 12-minute run test for estimation of maximum oxygen uptake in male university students

The present study was conducted to validate the applicability of Cooper''s 12-minute run test (CRT) for predicting VO₂max in male university students of Kolkata, India, to bypass the exhaustive and complicated protocol of direct estimation of VO₂max. Eighty-eight sedentary male university students recruited by simple random sampling from the University of Calcutta, Kolkata, were randomly assigned to the study group (N = 58) and the confirmatory group (N = 30). VO₂max of each participant was determined by the direct procedure and the indirect CRT method. The mean value of predicted VO₂max (PVO₂max) (42.8±4.0 ml · kg⁻¹ · min⁻¹ with a range of 33.7–50.9) showed a significant difference with VO₂max (39.8±4.0 ml · kg⁻¹ · min⁻¹ with a range of 33.5–47.7) in the study group. Limits of agreement between PVO₂max and VO₂max were large enough (0.10 to 5.94 ml · kg⁻¹ · min⁻¹) with poor confidence intervals indicating inapplicability of the current protocol of CRT in the studied population. The prediction norm [Y = 21.01X – 11.04 (SEE = 0.193 ml · kg⁻¹ · min⁻¹)] was computed from the significant correlation (r = 0.93, P < 0.001) between distance covered in CRT and VO₂max. Application of this norm in the confirmatory group revealed an insignificant difference between PVO₂max and VO₂max. The modified equation is recommended for application of CRT as a valid method to evaluate the cardiorespiratory fitness in terms of VO₂max in sedentary male Indian youth.     

Binding of β-lactam antibiotics to the exocellular dd-carboxypeptidase–transpeptidase of Streptomyces R39

Benzylpenicillin and cephaloridine reacted with the exocellular dd-carboxypeptidase–transpeptidase from Streptomyces R39 to form equimolar and inactive antibiotic–enzyme complexes. At saturation, the molar ratio of chromogenic cephalosporin 87-312 to enzyme was 1.3:1, but this discrepancy might be due to a lack of accuracy in the measurement of the antibiotic. Spectrophotometric studies showed that binding of cephaloridine and cephalosporin 87-312 to the enzyme caused opening of their β-lactam rings. Benzylpenicillin and cephalosporin 87-312 competed for the same site on the free enzyme, suggesting that binding of benzylpenicillin also resulted in the opening of its β-lactam ring. In Tris–NaCl–MgCl₂ buffer at pH7.7 and 37°C, the rate constants for the dissociation of the antibiotic–enzyme complexes were 2.8×10⁻⁶, 1.5×10⁻⁶ and 0.63×10⁻⁶s⁻¹ (half-lives 70, 130 and 300h) for benzylpenicillin, cephalosporin 87-312 and cephaloridine respectively. During the process, the protein underwent reactivation. The enzyme that was regenerated from its complex with benzylpenicillin was as sensitive to fresh benzylpenicillin as the native enzyme. With [¹⁴C]benzylpenicillin, the released radioactive compound was neither benzylpenicillin nor benzylpenicilloic acid. The Streptomyces R39 enzyme thus behaved as a β-lactam-antibiotic-destroying enzyme but did not function as a β-lactamase. Incubation at 37°C in 0.01m-phosphate buffer, pH7.0, and in the same buffer supplemented with sodium dodecyl sulphate caused a more rapid reversion of the [¹⁴C]benzylpenicillin–enzyme complex. The rate constants were 1.6×10⁻⁵s⁻¹ and 0.8×10⁻⁴s⁻¹ respectively. Under these conditions, however, there was no concomitant reactivation of the enzyme and the released radioactive compound(s) appeared not to be the same as before. The Streptomyces R39 enzyme and the exocellular dd-carboxypeptidase–transpeptidase from Streptomyces R61 appeared to differ from each other with regard to the topography of their penicillin-binding site.     

Structural analysis of DNA complexation with cationic lipids

Complexes of cationic liposomes with DNA are promising tools to deliver genetic information into cells for gene therapy and vaccines. Electrostatic interaction is thought to be the major force in lipid–DNA interaction, while lipid-base binding and the stability of cationic lipid–DNA complexes have been the subject of more debate in recent years. The aim of this study was to examine the complexation of calf-thymus DNA with cholesterol (Chol), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), dioctadecyldimethylammoniumbromide (DDAB) and dioleoylphosphatidylethanolamine (DOPE), at physiological condition, using constant DNA concentration and various lipid contents. Fourier transform infrared (FTIR), UV-visible, circular dichroism spectroscopic methods and atomic force microscopy were used to analyse lipid-binding site, the binding constant and the effects of lipid interaction on DNA stability and conformation. Structural analysis showed a strong lipid–DNA interaction via major and minor grooves and the backbone phosphate group with overall binding constants of K_Chol = 1.4 (±0.5) × 10⁴ M⁻¹, K_DDAB = 2.4 (±0.80) × 10⁴ M⁻¹, K_DOTAP = 3.1 (±0.90) × 10⁴ M⁻¹ and K_DOPE = 1.45 (± 0.60) × 10⁴ M⁻¹. The order of stability of lipid–DNA complexation is DOTAP>DDAB>DOPE>Chol. Hydrophobic interactions between lipid aliphatic tails and DNA were observed. Chol and DOPE induced a partial B to A-DNA conformational transition, while a partial B to C-DNA alteration occurred for DDAB and DOTAP at high lipid concentrations. DNA aggregation was observed at high lipid content.     

Microzooplankton Growth Rates Examined across a Temperature Gradient in the Barents Sea

Growth rates (µ) of abundant microzooplankton species were examined in field experiments conducted at ambient sea temperatures (−1.8–9.0°C) in the Barents Sea and adjacent waters (70–78.5°N). The maximum species-specific µ of ciliates and athecate dinoflagellates (0.33–1.67 d⁻¹ and 0.52–1.14 d⁻¹, respectively) occurred at temperatures below 5°C and exceeded the µ_max predicted by previously published, laboratory culture-derived equations. The opposite trend was found for thecate dinoflagellates, which grew faster in the warmer Atlantic Ocean water. Mixotrophic ciliates and dinoflagellates grew faster than their heterotrophic counterparts. At sub-zero temperatures, microzooplankton µ_max matched those predicted for phytoplankton by temperature-dependent growth equations. These results indicate that microzooplankton protists may be as adapted to extreme Arctic conditions as their algal prey.     

Simultaneous Detection of Forbidden Chemical Residues in Milk Using Dual-Label Time-Resolved Reverse Competitive Chemiluminescent Immunoassay Based on Amine Group Functionalized Surface

In this study, a sensitive dual-label time-resolved reverse competitive chemiluminescent immunoassay was developed for simultaneous detection of chloramphenicol (CAP) and clenbuterol (CLE) in milk. The strategy was performed based on the distinction of the kinetic characteristics of horseradish peroxidase (HRP) and alkaline phosphatase (ALP) in chemiluminesecence (CL) systems and different orders of magnitude in HRP CL value for CAP and ALP CL value for CLE in the chemiluminescent immunoassay. Capture antibodies were covalently bound to the amine group functionalized chemiluminescent microtiter plate (MTP) for efficient binding of detection antibodies for the enzymes labeled CAP (HRP-CAP) and CLE (ALP-CLE). The CL signals were recorded at different time points by the automatic luminometers with significant distinction in the dynamic curves. When we considered the ALP CL value (about 10⁵) of CLE as background for HRP CL signal value (about 10⁷) of CAP, there was no interaction from ALP CL background of CLE and the differentiation of CAP and CLE can be easily achieved. The 50% inhibition concentration (IC₅₀) values of CAP and CLE in milk samples were 0.00501 µg L⁻¹ and 0.0128 µg L⁻¹, with the ranges from 0.0003 µg L⁻¹ to 0.0912 µg L⁻¹ and from 0.00385 µg L⁻¹ to 0.125 µg L⁻¹, respectively. The developed method is more sensitive and of less duration than the commercial ELISA kits, suitable for simultaneous screening of CAP and CLE.     

Lidocaine,Dexmedetomidine and Their Combination Reduce Isoflurane Minimum Alveolar Concentration in Dogs

The effects of intravenous (IV) lidocaine, dexmedetomidine and their combination delivered as a bolus followed by a constant rate infusion (CRI) on the minimum alveolar concentration of isoflurane (MAC_ISO) in dogs were evaluated. Seven healthy adult dogs were included. Anaesthesia was induced with propofol and maintained with isoflurane. For each dog, baseline MAC (MAC_ISO/BASAL) was determined after a 90-minute equilibration period. Thereafter, each dog received one of the following treatments (loading dose, CRI): lidocaine 2 mg kg⁻¹, 100 µg kg⁻¹ minute⁻¹; dexmedetomidine 2 µg kg⁻¹, 2 µg kg⁻¹ hour⁻¹; or their combination. MAC was then determined again after 45- minutes of treatment by CRI. At the doses administered, lidocaine, dexmedetomidine and their combination significantly reduced MAC_ISO by 27.3% (range: 12.5–39.2%), 43.4% (33.3–53.3%) and 60.9% (46.1–78.1%), respectively, when compared to MAC_ISO/_BASAL. The combination resulted in a greater MAC_ISO reduction than the two drugs alone. Their use, at the doses studied, provides a clinically important reduction in the concentration of ISO during anaesthesia in dogs.     

Synthesis and biological evaluation of 2-arylbenzofuran derivatives as potential anti-Alzheimer’s disease agents

Alzheimer''s disease (AD) is a type of progressive dementia caused by degeneration of the nervous system. A single target drug usually does not work well. Therefore, multi-target drugs are designed and developed so that one drug can specifically bind to multiple targets to ensure clinical effectiveness and reduce toxicity. We synthesised a series of 2-arylbenzofuran derivatives and evaluated their in vitro activities. 2-Arylbenzofuran compounds have good dual cholinesterase inhibitory activity and β-secretase inhibitory activity. The IC₅₀ value of compound 20 against acetylcholinesterase inhibition (0.086 ± 0.01 µmol·L⁻¹) is similar to donepezil (0.085 ± 0.01 µmol·L⁻¹) and is better than baicalein (0.404 ± 0.04 µmol·L⁻¹). And most of the compounds have good BACE1 inhibitory activity, of which 3 compounds (8, 19 and 20) show better activity than baicalein (0.087 ± 0.03 µmol·L⁻¹). According to experimental results, 2-arylbenzofuran compounds provide an idea for drug design to develop prevention and treatment for AD.