Oxidative desorption of thiocholine assembled on core-shell Fe3O4/AuNPs magnetic nanocomposites for highly sensitive determination of acetylcholinesterase activity: an exposure biomarker of organophosphates

Acetylcholinesterase (AChE) activity is a well established biomarker for biomonitoring of exposures to organophosphates (OPs) pesticides and chemical nerve agents. In this work, we described a novel electrochemical oxidative desorption-process of thiocholine, the product of enzymatic reaction, for rapid and highly sensitive determination of AChE activity in human serum. This principle is based on self-assembling of produced thiocholine onto core-shell Fe(3)O(4)/Au nanoparticles (Fe(3)O(4)/AuNPs) magnetic nanocomposites and its oxidation at electrode surface. Fe(3)O(4) magnetic core is not only used for magnetic separation from sample solutions, but also carrying more AuNPs due to its large surface-to-volume ratio. The core-shell Fe(3)O(4)/AuNPs nanocomposites were characterized by UV-Vis spectroscopy, field-emission scanning electron microscopy (FE-SEM) and electrochemical measurements. A linear relationship was obtained between the AChE activity and its concentration from 0.05 to 5.0 mU mL(-1) with a detection limit of 0.02 mU mL(-1). The method showed good results for characterization of AChE spiked human serum and detection of OP exposures from 0.05 to 20 nM, with detection limit of 0.02 nM. This new oxidative desorption assay thus provides a sensitive and quantitative tool for biomonitoring of the exposure to OP pesticides and nerve agents.     

城市道路绿化带"微峡谷效应"及其对非机动车道污染物浓度的影响

研究不同绿化带结构对非机动车道污染物浓度的影响,将为城市道路绿化带格局提供依据。利用遮荫网模拟10、20、30 m隔离的道路绿化带,并模拟了3种不同结构的绿化带,分别对各类道路微气候条件(风)及SO₂、NO_x、NH₃、总悬浮颗粒物(TSP)和可吸入颗粒物(PM10)等5种主要污染物浓度进行了观测。结果表明:风速小于2 m/s时,10 m和20 m间隔的道路绿化带会产生"微峡谷效应",使绿化带间隔内风速增加。10 m间隔的绿化带较其它两种绿化带对各种污染物的净化百分率更明显,且污染物净化百分率与风速大多正相关显著。12.5 m的模拟绿化带与10 m的间隔交替的绿化带可以更有效地降低非机动车道的污染物浓度,污染物净化百分率与风速也大多正相关显著。不同结构道路绿化带会影响道路微气候条件,从而影响非机动车道污染物浓度。城市道路绿带存在合理的绿带结构,可以通过设计更合理的城市道路绿带模式有效改善城市非机动车道空气质量。     

TIG3 tumor suppressor-dependent organelle redistribution and apoptosis in skin cancer cells

TIG3 is a tumor suppressor protein that limits keratinocyte survival during normal differentiation. It is also important in cancer, as TIG3 level is reduced in tumors and in skin cancer cell lines, suggesting that loss of expression may be required for cancer cell survival. An important goal is identifying how TIG3 limits cell survival. In the present study we show that TIG3 expression in epidermal squamous cell carcinoma SCC-13 cells reduces cell proliferation and promotes morphological and biochemical apoptosis. To identify the mechanism that drives these changes, we demonstrate that TIG3 localizes near the centrosome and that pericentrosomal accumulation of TIG3 alters microtubule and microfilament organization and organelle distribution. Organelle accumulation at the centrosome is a hallmark of apoptosis and we demonstrate that TIG3 promotes pericentrosomal organelle accumulation. These changes are associated with reduced cyclin D1, cyclin E and cyclin A, and increased p21 level. In addition, Bax level is increased and Bcl-XL level is reduced, and cleavage of procaspase 3, procaspase 9 and PARP is enhanced. We propose that pericentrosomal localization of TIG3 is a key event that results in microtubule and microfilament redistribution and pericentrosomal organelle clustering and that leads to cancer cell apoptosis.     

Type I Transglutaminase Accumulation in the Endoplasmic Reticulum May Be an Underlying Cause of Autosomal Recessive Congenital Ichthyosis

Type I transglutaminase (TG1) is an enzyme that is responsible for assembly of the keratinocyte cornified envelope. Although TG1 mutation is an underlying cause of autosomal recessive congenital ichthyosis, a debilitating skin disease, the pathogenic mechanism is not completely understood. In the present study we show that TG1 is an endoplasmic reticulum (ER) membrane-associated protein that is trafficked through the ER for ultimate delivery to the plasma membrane. Mutation severely attenuates this processing and a catalytically inactive point mutant, TG1-FLAG(C377A), accumulates in the endoplasmic reticulum and in aggresome-like structures where it is ubiquitinylated. This accumulation results from protein misfolding, as treatment with a chemical chaperone permits it to exit the endoplasmic reticulum and travel to the plasma membrane. ER accumulation is also observed for ichthyosis-associated TG1 mutants. Our findings suggest that misfolding of TG1 mutants leads to ubiquitinylation and accumulation in the ER and aggresomes, and that abnormal intracellular processing of TG1 mutants may be an underlying cause of ichthyosis.     

Volume-Activated Chloride Currents in Fetal Human Nasopharyngeal Epithelial Cells

Volume-activated chloride channels have been studied by us extensively in human nasopharyngeal carcinoma cells. However, the chloride channels in the counterpart of the carcinoma cells have not been investigated. In this study, volume-activated chloride currents (I_cl,vol) were characterized in normal fetal human nasopharyngeal epithelial cells using the whole-cell patch-clamp technique. Under isotonic conditions, nasopharyngeal epithelial cells displayed only a weak background current. Exposure to 47% hypotonic solution activated a volume-sensitive current. The reversal potential of the current was close to the calculated equilibrium potential for Cl⁻. The peak values of the hypotonicity-activated current at +80 mV ranged from 0.82 to 2.71 nA in 23 cells. Further analysis indicated that the density of the hypotonicity-activated current in most cells (18/23) was smaller than 60 pA/pF. Only five cells presented a current larger than 60 pA/pF. The hypotonicity-activated current was independent of the exogenous ATP. Chloride channel inhibitors ATP, tamoxifen and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), inhibited the current dramatically. The anion permeability of the hypotonicity-activated chloride channels was I⁻ > Br⁻ > Cl⁻ > gluconate. Unexpectedly, in isotonic conditions, ATP (10 mM) activated an inward-rectified current, which had not been observed in the nasopharyngeal carcinoma cells. These results suggest that, under hypotonic challenges, fetal human nasopharyngeal epithelial cells can produce I_cl,vol, which might be involved in cell volume regulation.     

黑龙江省红松林资源动态变化研究

利用黑龙江省1949~1998年的调查数据和1949、1986年的两期1∶2500000森林资源分布图,从资源统计和景观格局两个角度对黑龙江省红松林的变化进行了研究。结果表明,从数量上看,黑龙江省红松林的面积和蓄积急剧减少,占全省森林资源的比例不断降低,林龄结构趋于不合理;从景观格局来看,1949年和1986年两期景观相比,红松林面积急剧减少,斑块数量增多,斑块密度加大,平均斑块面积减小,总边缘长度减小,边缘密度增大,呈严重的破碎化,大部分红松林景观转变为阔叶混交林和非林地。     

Alkoxy-auxins are selective inhibitors of auxin transport mediated by PIN, ABCB, and AUX1 transporters

Polar auxin movement is a primary regulator of programmed and plastic plant development. Auxin transport is highly regulated at the cellular level and is mediated by coordinated transport activity of plasma membrane-localized PIN, ABCB, and AUX1/LAX transporters. The activity of these transporters has been extensively analyzed using a combination of pharmacological inhibitors, synthetic auxins, and knock-out mutants in Arabidopsis. However, efforts to analyze auxin-dependent growth in other species that are less tractable to genetic manipulation require more selective inhibitors than are currently available. In this report, we characterize the inhibitory activity of 5-alkoxy derivatives of indole 3-acetic acid and 7-alkoxy derivatives of naphthalene 1-acetic acid, finding that the hexyloxy and benzyloxy derivatives act as potent inhibitors of auxin action in plants. These alkoxy-auxin analogs inhibit polar auxin transport and tropic responses associated with asymmetric auxin distribution in Arabidopsis and maize. The alkoxy-auxin analogs inhibit auxin transport mediated by AUX1, PIN, and ABCB proteins expressed in yeast. However, these analogs did not inhibit or activate SCF(TIR1) auxin signaling and had no effect on the subcellular trafficking of PIN proteins. Together these results indicate that alkoxy-auxins are inactive auxin analogs for auxin signaling, but are recognized by PIN, ABCB, and AUX1 auxin transport proteins. Alkoxy-auxins are powerful new tools for analyses of auxin-dependent development.