Does Bioavailability Limit Biodegradation? A Comparison of Hydrocarbon Biodegradation and Desorption Rates in Aged Soils

In order to determine whether bioavailability limits the biodegradability of petroleum hydrocarbons in aged soils, both the biodegradation and abiotic desorption rates of PAHs and n-alkanes were measured at various time points in six different aged soils undergoing slurry bioremediation treatment. Alkane biodegradation rates were always much greater than the respective desorption rates, indicating that these saturated hydrocarbons apparently do not need to be dissolved into the aqueous phase prior to metabolism by soil microorganisms. The biodegradation of PAHs was generally not mass-transfer rate limited during the initial phase, while it often became so at the end of the treatment period when biodegradation rates equaled abiotic desorption rates. However, in all cases where PAH biodegradation was not observed or PAH removal temporarily stalled, bioavailability limitations were not deemed responsible for this recalcitrance since these PAHs desorbed rapidly from the soil into the aqueous phase. Consequently, aged PAHs that are often thought to be recalcitrant due to bioavailability limitations may not be so and therefore may pose a greater risk to environmental receptors than previously thought.     

Comparative Evaluation of Three Supplements for Helicobacter pylori Growth in Liquid Culture

Helicobacter pylori, a microaerophilic fastidious bacterium, has been cultured on various plating and broth media since its discovery. Although the agar media can be sufficient for the identification, typing, and antibiotic resistance studies, no secretory antigen of H. pylori can be evaluated in such media. Thus, satisfactory growth of H. pylori in liquid culture which is needed for analysis of secretory proteins without the presence of interfering agents is in demand. We assessed the impact of β-cyclodextrin, Fetal Bovine Serum (FBS), and charcoal as supplements for H. pylori growth. Furthermore, we aimed to identify the most favorable supplement that supports the secretion of the dominant secretory protein, vacuolating cytotoxin (VacA). Five clinical strains were cultured on broth media and the growth, viability, morphology, and protein content of each strain were determined. Our results revealed that β-cyclodextrin supports the growth rate, viability, and cell lysate protein content to the extent similar to FBS. Application of β-cyclodextrin is found to postpone spiral to coccoid conversion up to 72 h of incubation. Although FBS supports a higher VacA protein content, presence of interfering macromolecules in FBS questions its utility particularly for purposes of studying extra cellular proteins such as VacA. This study recommends further application of β-cyclodextrin as a culture supplement with the potential capacity in neutralizing toxic compounds and flourishing the secretion of H. pylori proteins without addition of interfering proteins.     

Development and Evaluation of Simple Dot–Blot Assays for Rapid Detection of Staphylococcal Enterotoxin-A in Food

The present study was aimed to develop and evaluate dot–blot assays for rapid detection of staphylococcal enterotoxin-A (SEA) in food. Dot blots were developed in two formats, indirect and sandwich utilizing mouse monoclonal anti-SEA and rabbit polyclonal anti-SEA antibodies. In indirect dot–blot format, recombinant SEA was directly coated on NCM dot–blot strip and detection was carried out by anti-SEA antibodies. In sandwich dot–blot format, SEA was trapped between anti-SEA capture and detection antibodies. Both the dot–blot assays exhibited a sensitivity of ~48 ng ml^?1 when tested in different food matrices. The developed assays were highly specific as no cross-reactivity was detected with other classical staphylococcal enterotoxins, toxigenic bacteria and foodborne pathogens. Sensitivity and specificity of developed indirect and sandwich dot–blot assays with respect to PCR was found to be 100 and 99%, respectively. The results shows that the developed dot–blot assays can be used as rapid preliminary screening tests for detection of SEA in food or determining the toxigenic potential of staphylococci, especially in resource-limited settings.     

Development and Evaluation of Intron and Insertion–Deletion Markers for Gossypium barbadense

A total of 588 Gossypium barbadense coding sequences (CDSs) from nucleotide databases were selected for marker development. After selection, 125 CDSs were used to design 126 markers, including 39 intron polymorphisms (GbIPs) and 87 insertion?Cdeletion polymorphisms (GbIDPs). These markers were evaluated by analyzing the genetic diversity of 66 tetraploid cotton accessions including 56 G. barbadense accessions and 10 Gossypium hirsutum accessions. The amplification efficiencies of the GbIPs and GbIDPs were 0.560 and 0.489 for polymorphism information content, 0.744 and 0.690 for effective multiplex ratio (E), 0.653 and 0.438 for qualitative of nature of data, and 0.272 and 0.148 for effective marker index. Principal coordinate analysis showed profound differences between G. hirsutum and G. barbadense accessions. In addition, most of the G. barbadense accessions of Xinjiang, China were clearly different from foreign and other Chinese G. barbadense accessions. The 126 markers were also evaluated for their ability to enrich genetic maps, and 16 polymorphic loci were mapped on nine chromosomes with six loci on A subgenome and 10 loci on D subgenome. The mapping efficiencies of GbIPs and GbIDPs primers were 15.38% and 11.49%, respectively. This study well proves that GbIPs and GbIDPs can be successfully applied to the analysis of genetic diversity and construction of genetic maps.     

Dynamics of Inorganic Nitrogen in Nitrate and Glucose-amended Alkaline–saline Soil

Induction of assimilatory NO ₃ ⁻ reduction through the application of an easily decomposable substrate in alkaline–saline soils of the former lake Texcoco (Mexico) resulted in a fast immobilization of NO ₃ ⁻ in excess of N required for metabolic activity and the release of large concentrations of NO ₂ ⁻ and smaller amounts of NH ₄ ⁺ . We postulated that this was regulated by the amounts of NO ₃ ⁻ and glucose added, and affected by the specific characteristics of soil from the former lake Texcoco. This was investigated by spiking soils of different electrolytic conductivity (EC) 56.0 dS m⁻¹ (soil A of Texcoco) and 11.6 dS m⁻¹ (soil B of Texcoco) with different concentrations of NO ₃ ⁻ and glucose while dynamics of CO₂, NH ₄ ⁺ , NO ₂ ⁻ and NO ₃ ⁻ were monitored in an aerobic incubation for 7 days. For comparison reasons (control) an agricultural soil with low EC (0.3 dS m⁻¹) was included as well. In the agricultural soil, 67% of the added glucose mineralized within 7 days, but only 15% in soil A of Texcoco and 20% in soil B of Texcoco. The application of NO ₃ ⁻ to the agricultural soil added with glucose increased cumulative production of CO₂ 1.2 times, 1.5 times in soil A of Texcoco and 1.8 times in soil B of Texcoco. Concentration of NO ₂ ⁻ increased to > 100 mg NO ₂ ⁻ -N kg⁻¹ when 1000 mg glucose-C kg⁻¹ and 500 mg NO ₃ ⁻ -N kg⁻¹ were added to soil A and B of Texcoco, but remained < 3 mg NO ₂ ⁻ -N kg⁻¹ in the agricultural soil. The ratio between the cumulative production of CO₂ and the decrease in concentration of NO ₃ ⁻ was approximately one in soil A and B of Texcoco, but 10 in the agricultural soil after 3 days. It was found that micro-organisms in the alkaline–saline soil of the former lake Texcoco were capable of immobilizing large quantities of NO ₃ ⁻ when an easy decomposable substrate was available in excess of what might be required for metabolic activity while producing large concentrations of NO ₂ ⁻ , but these phenomena were absent in an agricultural soil. In soil of Texcoco, concentrations of NO ₂ ⁻ and NH ₄ ⁺ increased with increased salinity and availability of NO ₃ ⁻ . This ability to remove large quantities of NO ₃ ⁻ under these conditions and then utilize it at a later time might benefit micro-organisms of the N limited alkaline–saline soils of Texcoco.     

Characteristics and application of S1–P1 nucleases in biotechnology and medicine

3′–nucleases/nucleotidases of the S1–P1 family (EC 3.1.30.1) are single–strand–specific or non-specific zinc–dependent phosphoesterases present in plants, fungi, protozoan parasites, and in some bacteria. They participate in a wide variety of biological processes and their current biotechnological applications rely on their single–strand preference, nucleotide non-specificity, a broad range of catalytic conditions and high stability. We summarize the present and potential utilization of these enzymes in biotechnology and medicine in the context of their biochemical and structure–function properties. Explanation of unanswered questions for bacterial and trypanosomatid representatives could facilitate development of emerging applications in medicine.     

Comparative Bioavailability of Mineral-enriched Gluconates and Yeast in Rat Liver After Depletion–Repletion Feeding

There are many forms of mineral supplements currently available. Among these mineral-enriched gluconates and yeast are considered two of the more biologically available supplements. The purpose of this study was to use zinc (Zn)- or copper (Cu)-deficient rats to determine whether the organically bound mineral in yeast or the salt gluconate form was more bioavailable, i.e., is absorbed and found in a greater concentration in liver. It was demonstrated that Zn-enriched yeast was 3.7 times more bioavailable than the Zn gluconate and that Cu-enriched yeast was 1.4 times more bioavailable than the Cu gluconate.     

Cloning and Characterization of Three APETALA1/FRUITFULL-like Genes in Different Flower Types of Rosa?��?hybrida L.

To clarify the molecular mechanism of flower development in Rosa × hybrida L., three different APETALA1/FRUITFULL (AP1/FUL)-like MADS-box genes were isolated and their expression analyzed in normally developed flowers and in malformed flowers of a stable phenotype. AP1/FUL-like genes were designated as RhAP1-1, RhFUL, and RhAP1-2. Alignment of amino acid sequences showed 83% identity between RhAP1-1 and TrAP1 of Taihangia rupestris and 82% identity between RhFUL and TrFUL of T. rupestris. RhAP1-1 is 97% identical to RhAP1-2 and 58% identical to RhFUL. Expression of RhAP1-1 and RhAP1-2 in whorls 1 and 2 of rose flowers exclusively is in accordance with the expression pattern of class A genes in other plant species. In contrast, RhFUL showed a unique expression pattern and was expressed only in sepals. The roles of all putative A, B, and C class genes were examined in different flower organs of normally developed flowers and in malformed flowers that are similar to a classic C function mutant from Arabidopsis (with petals in whorl 3 and sepals in whorl 4). The expression pattern of the putative class B genes was similar in both normal and malformed flowers. However, the putative class A genes were upregulated and class C genes were downregulated in all flower organs of the mutant. These data suggest that suppression of the class C genes RhC1 and RhC2 leads to altered expression of RhAP1-1, RhFUL, and RhAP1-2 in whorls 3 and 4 that leads to the mutant flower phenotype.     

Soil hydraulic manipulation and organic amendment for the enhancement of selenium volatilization in a soil–pickleweed system

Biological volatilization of selenium (Se) in contaminated areas represents an environmentally friendly phytoremediation approach. Implementation of phytovolatilization technology for the remediation of Se-contaminated soils or sediments is oftentimes limited by its low remediation efficiency under field conditions. This greenhouse study determined the feasibility of manipulating soil organic content and hydraulic conditions in a soil–pickleweed (Salicornia bigelovii) system for the enhancement of Se volatilization. Based on annual shoot biomass production rate under field conditions (approximately 1.5 kg m⁻²), the addition of pickleweed shoot tissues to the soil surface resulted in 2.2-fold more biogenic volatile Se than the control, up to 251.6 ± 140.5 μg m⁻² d⁻¹. Selenium volatilization was significantly reduced at a soil water potential of −25 kPa, but substantially increased after re-irrigation to 0 kPa. In a 42-day experiment, the rate of Se volatilization was significantly correlated with soil water potential (P < 0.0001). Findings from this study demonstrate that Se volatilization be substantially enhanced by amending soil with pickleweed residues and by creating wetting and drying cycles that can be monitored with soil water potential probes in the field.     

Co-Composting of Soil Heavily Contaminated with Creosote with Cattle Manure and Vegetable Waste for the Bioremediation of Creosote–Contaminated Soil

Mispah form (FAO: Lithosol) soil contaminated with >380 000 mg kg^?1 creosote was co-composted with cattle manure and mixed vegetable waste for 19 months. The soil was mixed with wood chips to improve aeration and then mixed with cattle manure or mixed vegetable waste in a ratio of 4:1. Moisture, temperature, pH, ash content, C:N ratios, and the concentrations of creosote in the compost systems were monitored monthly. The concentrations of selected hydrocarbons in the compost systems were determined at the end of composting. Temperature rose to about 45°C in the cattle manure compost within two months of incubation while temperature in the control and vegetable waste remained below 30°C until the fourth month. Creosote concentration was reduced by 17% in the control and by more than 99% in the cattle manure and vegetable waste compost after composting. The rate of reduction in concentration in the mixed vegetable waste compost was initially lower than in the cattle manure compost. The reduction rate became similar in later months with only small differences towards the end of the composting. The concentrations of selected creosote components were reduced by between 96% and 100% after composting. There was no significant difference in reduction in concentration in both compost systems at p 0.05. Microbial activity correlated with reduction in creosote concentration.     

Climatic Control on Plant and Soil δ13C along an Altitudinal Transect of Lushan Mountain in Subtropical China: Characteristics and Interpretation of Soil Carbon Dynamics

Decreasing temperature and increasing precipitation along altitude gradients are typical mountain climate in subtropical China. In such a climate regime, identifying the patterns of the C stable isotope composition (δ¹³C) in plants and soils and their relations to the context of climate change is essential. In this study, the patterns of δ¹³C variation were investigated for tree leaves, litters, and soils in the natural secondary forests at four altitudes (219, 405, 780, and 1268 m a.s.l.) in Lushan Mountain, central subtropical China. For the dominant trees, both leaf and leaf-litter δ¹³C decreased as altitude increased from low to high altitude, whereas surface soil δ¹³C increased. The lower leaf δ¹³C at high altitudes was associated with the high moisture-related discrimination, while the high soil δ¹³C is attributed to the low temperature-induced decay. At each altitude, soil δ¹³C became enriched with soil depth. Soil δ¹³C increased with soil C concentrations and altitude, but decreased with soil depth. A negative relationship was also found between O-alkyl C and δ¹³C in litter and soil, whereas a positive relationship was observed between aromatic C and δ¹³C. Lower temperature and higher moisture at high altitudes are the predominant control factors of δ¹³C variation in plants and soils. These results help understand C dynamics in the context of global warming.     

Numerical Simulation of Plant–microbial Remediation for Petroleum-polluted Soil

This paper presents a numerical analysis of the migration and transformation mechanism of petroleum hydrocarbons (PHs) pollutants in soil. The mathematical model of the solute migration and plant–microbial remediation for PH polluted soil was established. The model was verified by field experimental data. Then, the software Hydrus-1D was employed to simulate the processes of diffusion, adsorption, desorption, microbial degradation, and plant adsorption of PHs in the soil–water system. The process of plant–microbial remediation for PH-contaminated soil was also simulated. The space-time change of PHs in soil was obtained, and the fate and remediation efficiency of PHs in soil were revealed in different remediation conditions. The results indicated that the Hydrus-1D model can adequately simulate the process of plant–microbial remediation. Plant–microbial remediation appears to be more efficient than the application of bacteria or Suaeda salsa. The majority of PH pollutants are degraded in the upper soil levels. For long-chain petro-alkane-contaminated soil, plant–microbial remediation is a more efficient method. A suitable moisture level in soil is important for improving the bioremediation effect of plant–microbial remediation technology.     

Epidemiological Characteristics of Influenza A and B in Macau, 2010–2018

Virologica Sinica - Influenza is one of the major respiratory diseases in humans. Macau is a tourist city with high density of population and special population mobility. The study on the...     

Differential Effect of Nimodipine in Attenuating Iron-Induced Toxicity in Brain- and Blood–Brain Barrier-Associated Cell Types

Metal homeostasis is increasingly being evaluated as a therapeutic target in stroke and neurodegenerative diseases. Metal dysregulation has been shown to lead to protein aggregation, plaque formation and neuronal death. In 2007, we first reported that voltage-gated calcium channels act as a facile conduit for the entry of free ferrous (Fe²⁺) ions into neurons. Herein, we evaluate differential iron toxicity to central nervous system cells and assess the ability of the typical L-type voltage-gated calcium channel blocker nimodipine to attenuate iron-induced toxicity. The data demonstrate that iron sulfate induces a dose-dependent decrease in cell viability in rat brain endothelial cells (RBE4; LC₅₀ = 150 μM), neuronal cells (Neuro-2α neuroblastoma; LC₅₀ = 400 μM), and in astrocytes (DI TNC1; LC₅₀ = 1.1 mM). Pre-treatment with nimodipine prior to iron sulfate exposure provided a significant (P < 0.05) increase in viable cell numbers for RBE4 (2.5-fold), Neuro2-α (~2-fold), and nearly abolished toxicity in primary neurons. Astrocytes were highly resistant to iron toxicity compared to the other cell types tested and nimodipine had no (P > 0.05) protective effect in these cells. The data demonstrate variable susceptibility to iron overload conditions in different cell types of the brain and suggest that typical L-type voltage-gated calcium channel blockers (here represented by nimodipine), may serve as protective agents in conditions involving iron overload, particularly in cell types highly susceptible to iron toxicity.     

Purification and Properties of Three Types of Xylanases Induced by Methyl β-Xyloside from Streptomyces sp.

When mycelia of Streptomyces sp. No. 3137 were cultivated in a medium containing methyl β-xyloside, xylanases (EC 3.2.1.8) were inductively produced into the medium. Three types of enzyme from the culture filtrate have been purified by ultrafiltration with DIAFLO UM-10, chromatography on DEAE-Sephadex A-25, gel filtration on Bio Gel P-100, and isoelectric focusing with Servalyt 6~8 or 9~11. The three purified enzymes, tentatively named X-I, X-II-A, and X-II-B, were homogeneous by Polyacrylamide gel electrophoresis at pH 4.3. The molecular weight of X-I was about 50,000 by SDS-polyacrylamide gel electrophoresis or gel filtration on Bio Gel P-100. The molecular weight of X-II-A and X-II-B were both approximately 25,000 by SDS-polyacrylamide gel electrophoresis and that of X-II-B was 25,680 by the sedimentation-equilibrium method. X-I had an isoelectric point at 7.10, and X-II-A and X-II-B had different isoelectric points, 10.06 and 10.26, respectively. The three enzymes were optimally active at 60~65°C and stable to 55°C. The optimal pH of X-I, X-II-A, and X-II-B were pH 5.5~6.5, 5.0~6.0, and 5.0~6.0, respectively. The ranges of two X-I’s pH stability (pH 1.5 ~ 11.5) were wider than that of X-I’s (pH 3.0 ~ 10.5). These purified preparations hydrolyzed xylotriose, xylotetraose, and xylan but not xylobiose, cellobiose, maltose, carboxymethyl cellulose, or soluble starch. Their actions were inhibited by Hg²⁺ and Fe³⁺ ions, sodium dodecyl sulfate, and N-bromosuccinimide.     

Hand Hygiene – Evaluation of Three Disinfectant Hand Sanitizers in a Community Setting

Hand hygiene is acknowledged as the single most important measure to prevent nosocomial infections in the healthcare setting. Similarly, in non-clinical settings, hand hygiene is recognised as a key element in helping prevent the spread of infectious diseases. The aim of this study was to evaluate the efficacy of three different disinfectant hand sanitizers in reducing the burden of bacterial hand contamination in 60 healthy volunteers in a community setting, both before and after education about the correct use of hand sanitizers. The study is the first to evaluate the efficacy and ease of use of different formulations of hand rubs used by the general population. The products tested were: Sterillium (perfumed, liquid), desderman pure gel (odorless, gel) and Lavit (perfumed, spray). Sterillium and desderman are EN1500 (hygienic hand rub) certified products (available in pharmacy) and Lavit is non EN1500 certified and available in supermarkets. The two EN1500 certified products were found to be significantly superior in terms of reducing bacterial load. desderman pure gel, Sterillium and Lavit reduced the bacterial count to 6.4%, 8.2% and 28.0% respectively. After education in the correct use of each hand rub, the bacterial load was reduced even further, demonstrating the value of education in improving hand hygiene. Information about the testers'' perceptions of the three sanitizers, together with their expectations of a hand sanitizer was obtained through a questionnaire. Efficacy, followed by skin compatibility were found to be the two most important attributes of a hand disinfectant in our target group.     

Adsorption and aerobic biodegradation of four selected endocrine disrupting chemicals in soil–water system

Adsorption and aerobic biodegradation characteristics of four selected endocrine disrupting chemicals (EDCs), 17β-estradiol (E2), 17α-ethinylestradiol (EE2), bisphenol A (BPA) and nonylphenol (NP) were investigated in soil–water system. The sorption of EDCs onto the soil was in the following order: NP > E2 > EE2 > BPA. Sorption isotherms of the four compounds fitted Freundlich models well. The aerobic biodegradation rates of these selected EDCs in the soil–water system could be described by pseudo-first-order kinetic equation. In a single chemical system, the half-lives of EDCs were 1.7, 5.3, 2.7 and 3.3 d for E2, EE2, NP and BPA, respectively, indicating that EE2 was not as readily biodegradable as the others. In a binary-chemical system, the half-lives of EDCs in all cominations were 1.5–2.2 times prolonged than the single chemical system. The following biotransformation pathway of estrogen was proposed: E2/EE2 → E1 → E3. An aerobic conversion of EE2 to E3 was also observed. The result of this research could be useful for predicting environmental fate and ecological risks of EDCs in natural environments especially when soil is their depository.