Toxicological effects of N,N,N′,N′-tetramethylethylenediamine on electric eel (Electrophorus electricus) acetylcholinesterase and human serum butyrylcholinesterase

This study examined the adverse effects of N,N,N′,N′-tetramethylethylenediamine (TEMED) on electric eel (Electrophorus electricus) acetylcholinesterase (AChE) and human serum butyrylcholinesterase (BChE). Data show that TEMED inhibited AChE in electric eel as well as human serum BChE. Kinetic studies indicated that the inhibition produced by TEMED in both sources was of mixed type, i.e. K_m increased and V _max decreased in a concentration-dependent manner. K_I (constant of ChE–substrate–TEMED complex into ChE–substrate complex and TEMED) was estimated to be 0.674 mM for electric eel and 0.024 mM for human serum BChE. The γK_m (dissociation constant of ChE–substrate–TEMED complex into ChE–TEMED complex and substrate) was 0.083 and 0.2 mM for electric eel AChE and human serum BChE, respectively. The IC₅₀ for electric eel and for human serum ChE was 1.57 and 0.043 mM, respectively. The present results suggest that TEMED produced adverse effects on electric eel and human serum via inhibition of ChE.     

Green synthesis of symmetrical N, N′-disubstituted thiourea derivatives in water using solar energy

Thioureas are of importance in medicinal chemistry due to their biological activities such as antituberculosis, anti-HIV, analgesic, anti-inflammatory, antimicrobial, antiarrhythmic, fungicide, herbicides, rodenticides and as phenoloxidase enzymatic inhibitors. Treatment of primary and secondary amines with thiophosgene is the common method of making symmetrical disubstituted thioureas. However, this method is hazardous due to the toxic properties of thiophosgene. Here, we report a green, operationally simple approach for the synthesis of 1, 3-disubstituted thiourea derivatives in moderate to excellent yields of 57–99 %. We use primary amines and CS₂ in water without any catalyst and solar thermal energy. This method is more environmentally benign and energy-saving compared with previously reported methods.     

Amelioration of acute mercury toxicity by a novel,non-toxic lipid soluble chelator N,N′bis-(2-mercaptoethyl)isophthalamide: effect on animal survival,health, mercury excretion,and organ accumulation

The toxic effects of mercury are known to be complex with specific enzyme inhibitions and subsequent oxidative stress adding to the damaging effects. There are likely other factors involved, such as the development of impaired metal ion homeostasis and depletion of thiol- and selenium-based metabolites such as cysteine and selenium. Much of the toxicity of mercury occurs at the intracellular level via binding of Hg²⁺ to thiol groups in specific proteins. Therefore, amelioration of mercury toxicity by the use of chelation would likely be enhanced by the use of a chelator that could cross the cell membrane and the blood brain barrier. It would be most favorable if this compound was of low toxicity, had appropriate pharmacokinetics, bound and rendered mercury cation non-toxic and had antioxidant properties. Herein we report on such a chelator, N,N′-bis(2-mercaptoethyl)isophthalamide (NBMI), and, using an animal model, show that it prevented the toxic effects associated with acute exposure induced by injected mercury chloride.     

1,2-二溴-4-(1,2-二溴乙基)环己烷(TBECH)对土壤中蚯蚓(Eisenia foetida)的毒性效应

1,2-二溴-4-(1,2-二溴乙基)环己烷(1,2-dibromo-4-(1,2-dibromoethyl) cyclohexane, TBECH)作为一种新型溴代阻燃剂已在多种环境介质和生物体中被检出,但其毒性效应研究相当匮乏。笔者研究了赤子爱胜蚓(Eisenia fetida)对土壤中TBECH的4种异构体(α-TBECH、β-TBECH、γ-TBECH和δ-TBECH)的选择性积累,考察了TBECH对赤子爱胜蚓的生长、蚯蚓体内自由基水平、丙二醛(MDA)、磷酸化组蛋白(γ-H2AX)含量以及抗氧化酶活性的影响。结果表明,蚯蚓对TBECH的富集存在异构体选择性,γ-TBECH的生物土壤富集因子(BSAF)大于其他异构体。低浓度暴露(50～200 mg·kg^-1)时,蚯蚓平均体质量、死亡率与空白组均无显著性差异,高浓度暴露(≥400 mg·kg^-1)时,随暴露浓度的增加,平均体质量下降,死亡率增加。TBECH暴露过程中,蚯蚓体内MDA和γ-H2AX含量显著增加。超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)以及谷胱甘肽S转移酶(GSTs)的活性在50 mg·kg^-1暴露下被显著诱导,在100～600 mg·kg^-1暴露下,随暴露时间和浓度的增加而降低。采用电子自旋共振结合二级自由基捕获技术测定了蚯蚓体内自由基水平,发现TBECH暴露能够引起蚯蚓体内大量羟基自由基的产生,且羟基自由基水平与MDA含量存在显著正相关关系,表明诱导蚯蚓体内产生大量羟基自由基从而导致的氧化损伤是TBECH对蚯蚓产生毒性的重要原因。以上研究结果揭示了赤子爱胜蚓对TBECH的富集能力以及TBECH对赤子爱胜蚓的毒性效应,为TBECH的生态健康风险评估提供了依据。     

Spatial segregation of calving and nursing Risso’s dolphins (Grampus griseus) in the Azores,and its conservation implications

Calving can be a critical period for cetaceans. Areas providing security for vulnerable calves, and high food availability for lactating females can be critical habitats requiring specific conservation measures. Here, we test the hypothesis that calving and nursing habitat could be defined for Risso’s dolphins (Grampus griseus). We investigated the spatial and temporal preferences of this species around Pico Island, Azores, using data gathered from land-based surveys and dedicated at-sea observations between 2004 and 2007. We divided observed pods into three groups: (1) those with newborn and young calves, (2) those with older calves or juveniles and (3) those consisting only of adults or sub-adults. We analysed eco-geographical variables and incorporated them into a presence-only spatial distribution model to evaluate differences in habitat suitability among the groups. We identified 694 pods of Risso’s dolphins overall. On the 267 pods observed in the first and second groups, 136 calves or juveniles were identified, of which 22 were newborns. The peak of the calving season was between June and August. The pods with newborn calves were larger and closer to shore, whereas the other groups were more widely dispersed offshore. Our results support the definition of critical habitat areas for this species, but we suggest widening the geographical coverage for better mapping around the island and throughout the archipelago generally. Conservation measures can, nevertheless, be implemented immediately, in order to reduce human impacts on a vulnerable component of the Risso’s dolphin population     

Preparation and characterization of β-FeOOH-coated sand and its adsorption of Cr(VI) from aqueous solutions

Batch adsorption experiments were conducted to explore the adsorption of Cr(VI) in aqueous solutions by β-FeOOH-coated sand. We investigated the key factors which affected the adsorption process such as adsorbent dosage, initial pH, initial Cr(VI) ion concentration, contact time and temperature. The uptake of Cr(VI) was very rapid and 44.3%, 51.6%, 58.9% of the adsorption happened during the first 180 minutes at 293K, 303K and 313K, respectively. The pseudo-second-order rate equation successfully described the adsorption kinetics. To study the adsorption isotherm, two equilibrium models, the Langmuir and Freundlich isotherms, were adopted. At 293K, 303K and 313K, the adsorption capacities obtained from the Langmuir isotherm were 0.060, 0.070 and 0.076 mg Cr(VI) per gram of the adsorbent, respectively. Thermodynamic parameters such as the change of energy, enthalpy and entropy were calculated using the equilibrium constants. The negative value of ΔG0 and the positive value of ΔH0 showed that the adsorption of Cr(VI) in aqueous solutions by β-FeOOH-coated sand was spontaneous, endothermic and occurred by physisorption.     

The international register of potentially toxic chemicals (IRPTC) its databank and network partners∗

The IRPTC was established by UNEP in 1976, upon the recommendation of the United Nations Conference on the Human Environment held in Stockholm in 1972.

It consists of a central unit and a network for information exchange. The main objective of IRPTC is to provide information adequate for the assessment of the hazards to health and the environment posed by chemicals. It is designed primarily to assist authorities responsible for protection of human health and the environment; however, its services are available to everyone.     

Synthesis and in vitro anti-inflammatory activity of novel benzo[d] imidazolyl dihydrospiro[indoline-3,1′-isoindole]-2,4′,7′-triones

Synthesis of novel benzo[d]imidazolyldihydrospiro[indoline-3,1′-isoindole]-2,4′,7′-triones has been described. The key intermediate 2-[(2-sulfanyl-1H-benzo[d]imidazol-5-yl)amino]acetic acid is obtained by reacting 5-amino-2-mercapto benzimidazole and chloroacetic acid. The three-component reaction of 2-[(2-sulfanyl-1H-benzo[d]imidazol-5-yl)amino]acetic acid with isatin and 1,4-benzoquinone in the presence of 10 mol% of L-proline at ambient temperature afforded 2′-(2-mercapto-1H-benzo [d] imidazol-5-yl)-3′,3a′-dihydrospiro[indoline-3,1′-isoindole]-2,4′,7′(2′H,7a′H)-triones. All the synthesized compounds were evaluated for in vitro anti-inflammatory activity.     

Synthesis,separation and structure determination of 2,3,3'‐trichlorobiphenyl (PCB 20)† and 3,3’,4‐trichlorobiphenyl (PCB35)†

The combined synthesis and spectrometric characterization of 2,3,3'‐trichlorobiphenyl (PCB 20) and 3,3’,4‐trichlorobiphenyl (PCB 35) is described for the first time. By a combination of highly efficient column distillation and repeated recrystallizations it was possible to isolate the two products as reference materials with a purity exceeding 99%. X‐ray analysis of crystals of 2,3,3'‐trichlorobiphenyl positively identified the substitution pattern of the biphenyl moiety by chlorine atoms. The two phenyl rings are at an angle of 52°, while the relative disposition of the chlorine atoms on both rings is closer to anti than to syn.     

Effects of low doses of bisphenol A and o,p ′- DDT on reproductive function of posthatching male Japanese quail

Forty-six posthatched male Japanese quail (Coturnix japonica) were divided into five groups; Control (n = 8), Oil (n = 8), 2 mg Bisphenol A (BPA) (n = 12), 20 µg o, p′-DDT (n = 11) and Mix [BPA (2 mg) and o, p′-DDT (20 µg)/10 µL] (n = 7). Chemicals were given orally to the quail daily for about 100 days. At day 90 of the experiment, sexual behavior was studied. Moreover, one day before the quail were sacrificed, cloacal gland areas were measured. All birds were scarified at 100 days. Testicular weights as well as gonado-somatic index were recorded. Sperm concentration was analyzed by the computer-assisted sperm analysis system. The testes of each bird were subjected to histopathological examination and the diameter of 30 randomly selected seminiferous tubules was measured. Sexual maturity was significantly delayed in o, p′-DDT and Mix groups. In addition, quail that were given BPA and o, p′-DDT took a significantly longer time to perform the first sexual interaction. The diameters of seminiferous tubules were remarkably reduced in all treated groups. In conclusion, low doses of BPA, o, p′-DDT or a combination of these two agents affected reproductive functions in male Japanese quail, when administered at posthatching.     

Synthesis of a three-dimensional network sodium alginate–poly(acrylic acid)/attapulgite hydrogel with good mechanic property and reusability for efficient adsorption of Cu2+ and Pb2+

Environmental Chemistry Letters - Water pollution caused by heavy metals has dramatically impacted ecosystems in recent years. For instance, 45.4% of lakes in China are in the category of moderate...     

Screening and identification of bacterial strain producing (R)-1-phenyl-1,2-Ethanediol by efficient whole-cell catalytic reduction system北大核心CSCD

(R)-1-Phenyl-1,2-ethanediol [(R)-PED] is an important chiral intermediate used to synthesize pharmaceutical intermediates. The production of (R)-PED is of great practical significance. A novel bacterial strain HBU-SI7 isolated from soil samples was screened using a-hydroxyacetophenone (2-HAP) as substrate, which is capable of enantioselective reduction of 2-HAP to (R)-PED. HBU-SI7 was identified as Rhodococcus sp. by bacterial morphological observation and 16S rDNA analysis. The analysis of whole-cell catalytic system showed that the bioconversion of 2-HAP reached 96.2% in the two-phase reaction system (dibutyl phthalate/phosphate buffer = 1/3, V/V) with the substrate concentration of 3.0 g/L, and 99.3% of e.e. for (R)-PED was achieved. A new enantio selective reduction system with the whole cells of Rhodococcus sp. was established for efficient production of (R)-PED, which has potential research and application values. © 2018 Science Press. All rights reserved.     

In vitro antioxidant and antibacterial activities of certain 3-{4-(5-mercapto-1,3,4-oxadiazole-2-yl)phenylimino}-indolin-2-one derivatives

A new series of 5- or 7-substituted 3-{4-(5-mercapto-1,3,4-oxadiazol-2-yl)phenylimino}-indolin-2-one derivatives were screened for in vitro antioxidant and antimicrobial activities. The results of this study revealed that all synthesized compounds were significantly scavenged DPPH free radicals in a concentration-dependant manner. The IC₅₀ values of all test compounds were found to be between 18.34 and 50.54?µM. All compounds significantly inhibited growth of bacteria and most of the minimum inhibitory concentration values were between 20 and 100?mg?mL^?1 indicating potent to moderate antibacterial activity. In conclusion, 3-{4-(5-mercapto-1,3,4-oxadiazole-2-yl)phenylimino)-5 or 7-substituted indolin-2-ones derivatives exhibited moderate antioxidant and antimicrobial activities.     

The concentration of Cu and Pb in the funnel spider Eratigena atrica (C. L. Koch 1843) (Araneae: Agelenidae) and its web

Studies on the heavy metal concentrations on spider webs in relation to the pathways of pollution penetration (external and internal) have yet to be performed. This work assesses the concentration levels of two heavy metals: essential copper (Cu) and toxic lead (Pb) in spider webs and spiders (females, males and juveniles). Spiders divided into three treatment groups were exposed to the heavy metals in their diet as prey (fruit flies and mealworms larvae) were artificially contaminated with Cu and Pb. In general, we found higher rates of Cu compared to Pb concentrations in spiders and their webs. A positive correlation between levels of Cu and Pb in webs and spiders was found. Males had higher concentrations of both metals Cu and Pb in their bodies and webs compared to females. In an additional experiment, washed webs had significantly less metals than unwashed suggesting the dominance of external pollution in the contamination pathway.     

Research progress of nitrous oxide reductase gene (nosZII) and its relationship with the environment北大核心CSCD

The greenhouse effect has become increasingly serious globally. Nitrous oxide (N2O) is both the major ozone depleting substance and a potent greenhouse gas having a global warming potential 298 times that of CO2, and the N2O concentration is still increasing at an annual rate of about 0.8 × 10-9. Nitrous oxide reductase (N2OR) can reduce N2O to N2, and until recently, the nosZ gene was the only gene known to be able to encode N2OR. Besides the well-known nosZI, a new lineage of the N2O-reductase (nosZ clade II), which is abundant and widespread in soils, has been identified. In this paper, the main characters of nosZII-containing microbial communities and the related working mechanisms are summarized. In addition to the main differences between nosZI and nosZII, the important environmental factors that regulate the composition, abundance, and expression of nosZII-containing communities are also discussed in this paper. Studies have shown that nosZII communities are distributed among a diverse range of bacterial and archaeal phyla, such as Epsilon-proteobacteria, Bacteroidetes, and Aquificae. Interestingly, most of the nosZII microbes lack a nitrite reductase encoding gene (nirS or nirK) and are therefore unable to denitrify, indicating the importance of these communities as N2O sinks. Soil properties such as texture, pH, C/ N ratio, temperature, and lake physical gradient could regulate nosZII microbe abundance and diversity, and the pH and C/ N ratio may be the most important influencing factors. Studies on the ecological function of nosZII microbes have advanced considerably with the development of molecular biology technology. However, further studies on the community structure of nosZII microbes, the influencing factors of nosZII microbe abundance and diversity, and characteristics of nosZII strains with strong N2O reducing ability are needed. We hope to provide a theoretical basis that can be used to facilitate N2O reduction and relieve the greenhouse gas problem. © 2018 Science Press. All rights reserved.     

Microbiological degradation of polycyclic aromatic hydrocarbons: Anthracene,benzo(K)fluoranthene,dibenzothiophene, benzo(H) quinoline and 2‐nitronaphthalene

Biodegradation experiments of various polycyclic aromatic hydrocarbons were studied with mixed bacteria culture under aerobic conditions. An easy‐to‐handle clean‐up procedure was developed for PAH and their metabolites simultaneously as well as a gc‐ms‐method to identify and quantify these compounds.

Anthracene and dibenzothiophene are completely degradable in an aqeous system, whereas biodegradation of benzo(k)fluoranthene and benzo(h)quinoline is possible only in an oil‐in‐water‐system with dodecane as cosubstrate. No degradation of nitronaphthalene was observed in aqueous systems. New metabolites are 2,3‐dihydroxybenzothiophene, hydroxybenzothiophenecarbonic acid and benzothiophenequinone for dibenzothiophene and hydroxyfluoranthenic acid for benzo(k)flouranthene. Whereas the former metabolites are degradable under the experimental conditions, the latter accumulates during the degradation experiment.

The results are important for microbiological wastewater treatment, since knowledge of biodegradation processes is indespensable for the successful treatment of PAH‐containing wastewater.