Neuropathy Target Esterase: Rates of Turnover In Vivo Following Covalent Inhibition with Phenyl Di-n-Pentylphosphinate

Phenyl di-n-pentylphosphinate is a reasonably stable easily synthesized inhibitor of neuropathy target esterase (NTE) with low anticholinesterase activity. Like phenylmethylsulphonyl fluoride it protects hens against neuropathic effects of compounds such as diisopropylphosphorofluoridate. At intervals up to 15 days after dosing hens (10 mg/kg s.c. to inhibit 90% NTE) assays were made of catalytically active and of phosphinylated NTE in autopsy tissue. The sum of these components was always within the range of catalytic activity in undosed controls. However, the half-life of reappearance of active NTE was 2.07 days +/- 0.13 (SD, n = 6) for brain and 3.62 days +/- 0.23 (SD, n = 6) for spinal cord--shorter than after dosing with phenylmethylsulphonyl fluoride. It is proposed that: (1) The physiological turnover mechanism cannot distinguish between catalytically active and di-n-pentylphosphinylated NTE although initiation of organophosphate-induced delayed polyneuropathy might involve recognition of aged di-alkyl-phosphorylated NTE as "foreign". (2) The short half-lives indicate a slow spontaneous dephosphinylation of inhibited NTE occurs in vivo as well as de novo synthesis. The difference in half-lives for brain and spinal cord NTE may be due to different rates of synthesis de novo or (more likely) to different rates of spontaneous reactivation of the inhibited NTE in the two tissues.     

The extracellular nuclease of Serratia marcescens: studies on the activity in vitro and effect on transforming DNA in a groundwater aquifer microcosm

A quantitative endonuclease assay, which relies on the introduction of single and double strand breaks into supercoiled plasmid DNA, was used to study the activity of the extracellular nuclease of Serratia marcescens SM6 in buffer and in groundwater. The parallel enzyme concentration-dependent production of relaxed and linear plasmid molecules suggests that the nuclease produces single and double strand breaks in duplex DNA. Bovine serum albumin stimulated the nuclease activity towards DNA and RNA and increased the stability of the enzyme against thermal inactivation. The DNase activity at 4 °C and 50 °C was almost half of that at the optimum temperature (37 °C). The nuclease was active in groundwater, although the specific activity was lower than in buffer. In a groundwater aquifer microcosm, mineral-adsorbed transforming DNA was substantially less accessible to the nuclease than was dissolved DNA. The data suggest that the extracellular nuclease of Serratia marcescens may contribute to DNA turnover in the environment and that adsorption of DNA to minerals provides protection against the nuclease.Abbreviations GW groundwater GWA groundwater aquifer     

Choline derivatives and sodium fluoride protect acetylcholinesterase against irreversible inhibition and aging by DFP and paraoxon

A light addressable potentiometric sensor was used to measure acetylcholinesterase (AChE) activity in order to evaluate the protective effects of quaternary compounds and NaF against enzyme phosphorylation and aging by two organophosphates. The use of the immobilized AChE made possible the quick removal of reagents (i.e., organophosphate, 2-pralidoxime, and protectant), thereby permitting accurate determination of AChE activity before and after phosphorylation and aging. Paraoxon was 15-fold more potent in inhibiting AChE than DFP, while the percent aging following phosphorylation by diiso-propylfluorophosphate (DFP) was much higher. Sodium fluoride (NaF), the most effective protectant against phosphorylation and aging, and the quaternary ammonium compounds reduced significantly AChE inhibition by DFP and paraoxon, to similar degrees. Even though the percent AChE activity that was lost to aging was reduced by these agents, aging as a percent of phosphorylated AChE was not reduced. Thus, their major effect was in reducing the percent AChE phosphorylation, which consequently resulted in reduction of total aged AChE. The finding that quaternary ammonium compounds protect against phosphorylation is consonant with the proposed presence of the active site of AChE in an aromatic gorge.     

动植物检疫在生物多样性保护中的作用

生物多样性保护不仅包括对野生物种的保护,也包含对栽培和驯化物种的遗传多样性的保护,动植物检疫在保护栽培和驯化物种的安全和防止野生物种资源外流两个方面发挥了重要作用。可以认为,动植物检疫系统是生物多样性保护中的一支生力军。文章强调,一要加强动植物检疫,减少国际贸易对生物多样性的影响;二要增强口岸把关,有效地保护我国濒危、珍稀物种资源。文中例举了过去我国濒危、珍稀生物资源破坏和流失情况,并介绍了在加强对濒危、珍稀物种进出口管理中,动植物检疫机关所起的把关作用。     

Changes in composition and structure of Vitex shrubland in northern China in relation to human disturbance

Vegetation and biomass in six plots, each with five quadrats, in Vitex shrubland in northern China were related to type and degree of human disturbance. Canonical correspondence analysis of the vegetation and environmental data showed two lines of variation, the first one highly correlated with the degree of disturbance, but the second one appearing within the disturbed plots cannot yet be fully explained. Changes in life-form spectrum were small, but the geographical spectrum changed under heavy disturbance towards a higher proportion of tropical, subtropical and cosmopolitan species. The number of shrub species also decreased noticeably. The above-ground biomass of both Vitex and the accompanying species and the total above-ground biomass of the shrubland was negatively correlated with the intensity of disturbance. The root/stem biomass ratio in Vitex reaches values of over 5 in disturbed plots, but only between 1 and 2 in the protected plots.     

Alien or endangered? Historical development of Chara connivens in the Baltic coastal waters and its implication for the species management

The occurrence of Chara connivens (Charophyta, Characeae) and its status in the Baltic Sea may raise controversies regarding its origin and historical dispersal pathways in the area. This study critically revises the protection status of C. connivens in the countries around the Baltic Sea, as well as its status on the red lists of endangered plant species (including the HELCOM Red List). The first reports on the presence of C. connivens in the Baltic Sea area were published in the aftermath of Carl Baenitz’s talks given in the early 1870s. Already then, the scientific community was well aware of the fact that C. connivens had been introduced as a ballast plant to the known Baltic areas of occurrence – the first known record of the species is from 1829. Since Poland is the only country where C. connivens is protected, the historical and contemporary distribution of this charophyte in the Polish coastal waters is presented against the background of the available historical and recent records of the species in the Baltic Sea. Recent reports from the second half of the 20th century and the beginning of the 21st century have confirmed a fairly common occurrence of C. connivens in Estonia, Sweden and Poland. This species still occurs on the German coast and has also been reported from Finland (the Åland archipelago). In recent decades, however, the species was considered rare in the Baltic Sea area. In Poland, C. connivens was even classified as extinct, despite earlier data on its occurrence in the Vistula Lagoon in the 1970s, where it was rediscovered in 2011. It was also found in the Szczecin Lagoon a year later. Both localities well suit Luther’s pattern of C. connivens occurrence in areas with intensive shipping and ballast discharge operations in historical times. Based on this in-depth revision of historical and current distribution, it is postulated that C. connivens, as non-indigenous, should not be red-listed in the Baltic Sea area, following the example of Finland. Moreover, its legal status in Poland of a strictly protected species should be reconsidered.     

Factors underpinning Iranian farmers’ intention to conserve biodiversity at the farm level

The depletion of biodiversity is a major environmental challenge of the present time, with the agricultural sector being a significant contributor to the loss. Therefore, farmers' decisions and practices are pivotal in safeguarding biodiversity at the farm level. Accordingly, this study aimed to unravel the key factors influencing farmers' intention to conserve biodiversity (ICB), and in doing so, it adopted the protection motivation theory (PMT) as the theoretical framework. The study's statistical population comprised 412 farmers residing in Bavi County in the southwestern region of Iran. The research employed a questionnaire as the data collection instrument, and the research hypotheses were tested using structural equation modeling (SEM). The findings indicated that the respondents held a perception of high costs associated with implementing biodiversity conservation behaviors. They believed that such measures would not be easy to implement, and they would incur both monetary and non-monetary costs. Furthermore, the findings of the study revealed that the variables of SE and ICB among the studied farmers were lower than the theoretical median of 3, indicating that farmers may not have a strong desire and self-efficacy to engage in biodiversity conservation practices. Through the application of SEM, the study determined that the PMT accounts for 65.2% of farmers’ ICB. Additionally, perceived severity and self-efficacy were found to have the strongest effects on farmers’ ICB (as the first and second determinants), highlighting the importance of these variables in predicting farmers’ conservation behaviors. Overall, it can be concluded that these results have significant implications for policymakers in the agricultural sector, providing valuable insights into how to promote biodiversity conservation practices among farmers.     

亚硒酸钠对四氯化碳损伤草鱼肝原代细胞与肝组织的保护作用

不同浓度四氯化碳（ＣＣｌ４）对草鱼肝原代细胞的损伤实验中,ＣＣｌ４浓度为１０μｌ／ｍｌ可引起细胞血清中丙氨酸氨基转移酶（ＡＬＴ）、天门冬氨酸氨基转移酶（ＡＳＴ）、乳酸脱氢酶（ＬＤＨ）逸出量与细胞破损率显著增高,培养液中添加亚硒酸钠（Ｎａ２ＳｅＯ３）０．２μｇ／ｍｌ,则可降低ＡＬＴ、ＡＳＴ、ＬＤＨ的逸出量,减轻细胞破损程度。Ｎａ２ＳｅＯ３保护实验中,Ｎａ２ＳｅＯ２＋ＣＣｌ４组预先腹腔注射（ｉｐ）０．１ｍｇ／ｋｇ．ｂｗ连续三日,末次ｉｐＣＣｌ４混合液１ｍｌ／ｋｇ．ｂｗ,２４ｈ内肝组织超氧物歧化酶（ＳＯＤ）相对活性比ＣＣｌ４组提高达９１．５％,第七日仍提高达５４．５％,与对照组的水平基本接近;血清中丙氨酸氨基转氨酶（ＡＬＴ）水平逐渐降低。本实验还观察到Ｎａ２ＳｅＯ３可引起肝脂质过氧化物显著降低,肝微粒体蛋白含量与细胞色素Ｐ—４５０活性升高;组织切片观察显示肝组织损伤程度减轻,７２ｈ后细胞核增多。表明Ｎａ２ＳｅＯ３可提高草鱼肝清除自由基能力,增强肝脏解毒功能。     

Cell signaling and heat shock protein expression

Exposure of cells and organs to heat shock is associated with numerous changes in various cellular metabolic parameters and overexpression of proteins collectively known as heat shock proteins (HSP). In this communication we review the cell-signaling events that are altered in response to heat shock as they relate to the subsequent induction of HSP 70 kd (HSP-70) expression. We also review the mechanisms by which HSP-70 is involved in conferring cytoprotective effects. The possibility of altering HSP expression through manipulations of the cell-signal process has clinical importance.The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the Department of the Army or Department of Defense.     

The utilization of molecular hydrogen by the blue-green alga Anabaena cylindrica

The blue-green alga Anabaena cylindrica is found to consume molecular hydrogen in a hydrogenase dependent reaction. This hydrogen uptake proceeds in the dark and is strictly dependent on oxygen, thus representing a Knallgas reactions. Its rate is almost as high as that of the endogenous respiration in Anabaena. Studies with inhibitors reveal that hydrogen is utilized via the complete respiratory chain providing additional energy for the alga. CO plus C₂H₂ completely block the Knallgas reaction which explains the previously reported considerable increase in the total H₂ formation representing the difference between the nitrogenase-dependent H₂-evolution and the reutilization of the gas catalysed by the hydrogenase in intact Anabaena.H₂ is able to support the C₂H₂-reduction in the dark in a reaction again strictly dependent on oxygen. Moreover, H₂ is also consumed in experiments carried out under far red light and in the presence of dichlorophenyl-dimenthyl-urea (DCMU) where the energy for nitrogen fixation is no longer provided by respiration but by cyclic photophosphorylation. Under these conditions, H₂ is found to supply electrons for the formation of C₂H₄ from C₂H₂ in a reaction no longer dependent on the presence of oxygen. Moreover, in these experiments, the presence of H₂ stabilizes the C₂H₂-reduction activity against the deleterious effect of oxygen.Thus, this communication provides evidence for a triplicate function of the H₂-uptake catalysed by hydrogenase in intact Anabaena which is (a) to provide energy by the Knallgas reaction, (b) to supply reducing equivalents for nitrogenase, (c) to protect nitrogenase from damage by oxygen.Abbreviations DCMU N-(3,4-dichlorophenyl)N,N-dimethylurea - DNP 2-4-dinitrophenol - FCCP carbonylcyanid-p-trifluormethoxyphenyl-hydrazone(=p-CF₃-CCP) - Chl chlorophyll