神农架巴山冷杉天然林凋落物特性的研究

神农架地区的巴山冷杉（Abies fargesii）林是秦巴山地重要的森林生态系统类型，长期以来其在水土保持、水源涵养、林产品供给等方面的生态服务功能受到了广泛的重视，近年来该类森林的生物地球化学循环正成为关注的热点。本文以神农架巴山冷杉天然林为研究对象，从其凋落物的数量、养分、能量3个方面入手，着重研究1)凋落物组成及其凋落量的月变化模式;2)凋落物养分含量及养分年归还量的特征;3）凋落物的能流量及其月变化模式。研究表明： 巴山冷杉天然林的年凋落量为5702.99kg.hm-2，处于亚热带森林年凋落量的范围内;巴山冷杉林的凋落物组成比较丰富，主要有落叶、落枝、球花、球果和其它五部分，其中以落叶为多，占总凋落量的46.00%;凋落量的月变化模式呈双峰型，分别在2006年10-11月和2007年4-5月达到峰值。 巴山冷杉林凋落物养分含量的大小顺序为：N＞K＞Ca＞P＞Mg;N、P、K、Ca、Mg的年归还量分别为：39.1063 kg.hm-2、4.5346 kg.hm-2、13.4367 kg.hm-2、5.4965 kg.hm-2、0.0911 kg.hm-2，以N的年归还量最多;就凋落物各组分的养分年归还量而言，落叶的养分归还量远远大于其余组分的养分归还量，占总归还量的52.65%。因此，不论凋落量还是养分归还量，巴山冷杉林凋落物中的落叶都占有绝对的优势。 在巴山冷杉林凋落物各组分中，干重热值介于20.60 KJ/g 至22.70 KJ/g之间，灰分浓度介于1.38%至5.94%之间，去灰分热值介于21.34 KJ/g至23.55KJ/g之间，充分表明了灰分对热值的影响。在各组分中，无论是干重热值还是去灰分热值，均以落叶的热值最高。从整年来看，落叶的热值在2006年10－11月和2007年6－7月较高。巴山冷杉林通过凋落物的年能流量为 12500.96 KJ.m-2，以落叶能流量最大，占总能流量的47.72%。通过计算凋落物的能流量占太阳有效辐射的百分数可以得出太阳辐射进入凋落物的转化效率，巴山冷杉林凋落物的能量转化效率为0.61%，这在亚热带和热带森林类型中属于中等水平。

冬小麦对盐分与臭氧胁迫的生理生态响应机理研究

本研究选用抗盐冬小麦品种—德抗961（DK961）和盐敏感品种—济南17（JN17）为试验材料。一方面，研究了冬小麦对盐分及臭氧胁迫的生理生态响应机制；另一方面，探讨了外源硝酸钾对小麦盐伤害的缓解机理，提出了盐胁迫下小麦优质高产的栽培技术规程。主要结论如下： 1 冬小麦产量与品质对不同浓度盐胁迫的响应 同一小麦品种在不同盐浓度胁迫下产量和品质存在显著差异，不同小麦品种在同一盐分浓度胁迫下产量和品质也有显著差异，说明盐胁迫下小麦产量和品质与小麦品种特性和耐盐性关系密切。在对照栽培条件下，两小麦品种的产量次序为JN17＞DK961；在轻度（0.3%）盐胁迫下，耐盐品种仍获得了较高的产量（仅下降5.8%），而盐敏感品种下降幅度较大（为22.9%），此时的产量次序为DK961＞JN17；DK961在0.5%盐胁迫下，产量较对照处理下降9.7%，而JN17下降了54.3%；在0.7％盐浓度环境中，DK961和JN17产量均出现了大幅降低，但DK961的产量仍显著高于JN17。 盐胁迫下的小麦品质指标表现为：在0.3％和0.5%盐浓度下，随着盐浓度的升高，蛋白质含量升高，淀粉含量下降；当盐浓度达到0.7%时，两者都快速下降。 2 不同耐盐性冬小麦品种对盐胁迫的生理生态响应 2.1品种与盐浓度对小麦生长特性的影响 盐胁迫造成了小麦的后期衰老加快，光合速率降低，生育期缩短。但这种影响会因小麦的耐盐性不同而有很大的差异：DK961在轻、中度盐浓度（0.3％、0.5％）下，生育期与无盐处理时无显著差异，但当盐浓度达到0.7%时，生育期出现了明显的缩短；相反，JN17生育期在各个盐浓度下都出现了显著变化。对盐敏感品种，盐胁迫导致小麦出苗期、拔节期推迟3-5 d，抽穗期和开花期提前6-7 d，成熟期提前10-15 d。盐胁迫对小麦生育期的影响主要是缩短生殖生长期。 2.2品种与盐浓度对小麦生理代谢的影响 不同冬小麦品种对盐胁迫产生的生理反应程度不同，耐盐小麦品种在一定的盐浓度范围内，盐胁迫症状不明显，生理反应比较迟钝，光合速率、气孔导度、光饱和点等基本维持在无盐处理的水平，丙二醛和活性氧清除酶活性增加不显著；盐敏感品种在各种盐浓度胁迫下或耐盐品种在过重的盐分浓度胁迫下，盐胁迫症状极为显著，小麦植株生长矮小，光合速率、气孔导度、光饱和点等大幅下降，丙二醛和活性氧自由基含量大幅上升，严重的情况下，小麦植株不能正常生长，甚至出现“干死”现象。 3 盐胁迫下冬小麦生理生态特征对臭氧浓度升高的响应 3.1 臭氧污染对小麦生理代谢的影响 3.1.1对小麦叶片气体交换的影响 气孔是小麦叶片与外界气体交换的“大门”，是臭氧进入叶片的主要通道，控制着蒸腾、光合、呼吸等重要生理过程。通常，高浓度臭氧环境中，小麦表现出较低的气孔导度。气孔的这种反应是植物限制臭氧进入叶片中的一种避害机制。 臭氧的强氧化性导致高浓度臭氧环境中小麦的光合速率下降。臭氧通过气孔进入叶片后，对植物叶片光合作用的抑制主要是由Rubiso酶含量/活性的降低引起的。研究发现，臭氧低于某一临界值时，产生的氧化伤害可以被植物体的抗氧化系统清除而不会对光合作用产生抑制，而高于该临界值时由Rubsico限制引起的光合速率降低将与臭氧吸收量呈线性关系。高浓度臭氧环境下，植物光合作用降低的生理原因，主要是臭氧导致叶绿素和可溶性蛋白分解，叶片衰老加快、叶绿体结构发生改变、活性氧清除酶活性升高，而与碳素固定有关的酶活性降低、光合产物向外运输受阻而导致的反馈抑制。 3.1.2对小麦生长特性的影响 研究表明，环境中臭氧浓度升高可引起小麦生长特性发生巨大改变。臭氧污染首先加快老叶的衰老，而对新叶的影响很小。然而老叶衰老能够将其中的营养转移到新生长叶片中，有利于维持植株的生长。臭氧环境下，老叶迅速衰老的同时，同一植株中的新生组织具有较高的Rubisco合成速率和总量，同化速率加强。这一现象被认为是植株在臭氧环境下的一种补偿机制。臭氧显著降低植株同化物向根系的分配，而同化物向根系分配的改变将导致根系与整株植物功能关系的改变。在水分亏缺环境下，植物根系的生长受到抑制，导致根系对土壤营养吸收能力的降低，从而间接降低叶片的光合速率。 3.2 盐胁迫引起的生理响应提高了小麦抵御臭氧伤害的能力 试验结果表明，盐胁迫引起的小麦生理响应（如，气孔导度降低、抗氧化酶活性升高等），显著增强了小麦抵抗臭氧伤害的能力。但这种保护作用是相对的，因为盐胁迫本身已对小麦生长产生显著的抑制作用。 3.2.1 气孔导度下降减少了臭氧的进入 研究发现，臭氧是通过气孔进入植物体内的，而盐胁迫引起的小麦气孔导度下降，显著减少了臭氧进入小麦体内的量，大大减轻了臭氧对小麦的伤害。本实验中，无盐栽培条件下，臭氧引起的小麦光合速率降低，达到了显著水平；而盐胁迫下，由臭氧引起的小麦光合速率降低，未达到显著水平。这说明盐胁迫引起的气孔导度降低，起到了减轻臭氧对小麦生长抑制的作用。 3.2.2 渗透调节能力的增强弱化了臭氧的伤害 盐胁迫引起的可溶性糖、可溶性蛋白、脯氨酸等渗透调节物质含量的升高，大大增强了小麦抵御臭氧伤害的能力。如，臭氧往往造成植物蛋白质的分解，降低蛋白质含量；但盐胁迫下，可溶性蛋白含量是上升的，两方面协调，维持了植株蛋白质水平，促进了小麦生长。另一方面，渗透调节物质的积累，有利于小麦同化物的合成、转化和运输，加快了循环的节奏，这也是盐胁迫降低臭氧对小麦伤害的重要原因之一。 3.2.3 抗氧化能力增强降低了臭氧的氧化伤害 盐胁迫引起的小麦酶促保护系统抗氧化酶（SOD、POD等）活性升高，提高了小麦体内活性氧清除能力。臭氧污染可产生大量的活性氧自由基，对小麦产生强氧化伤害，抑制小麦生长。通常情况下，臭氧胁迫也可引起小麦抗氧化酶活性的提高，来适应这种污染环境。本实验表明，在盐和臭氧的交互作用下，小麦抗氧化酶活性的升高呈现了叠加效应，小麦的活性氧清除能力大大加强，减缓了小麦衰老进程，有利于小麦生长。 4 外源硝酸钾对冬小麦盐胁迫伤害的缓解机理及高产栽培技术规程 4.1 不同浓度硝酸钾处理对盐胁迫下小麦幼苗生理代谢的影响 植株体内K+/Na+比值是衡量小麦抗盐性的一项重要指标。盐胁迫下，小麦体内Na+含量快速上升，而K+含量相对下降，K+/Na+比值快速降低，打破了植株体内离子平衡，对小麦造成Na+“单盐毒害”，严重抑制小麦生长。可溶性糖、脯氨酸等低分子量渗透调节物质含量升高；膜质过氧化程度加重，电解质外渗量及丙二醛含量升高；活性氧自由基增多，抗氧化酶活性升高。 外源KNO3显著提高了小麦植株组织内K+/Na+比值，盐胁迫症状减轻，可溶性糖、脯氨酸等低分子量渗透调节物质含量比单独NaCl胁迫时降低；膜质过氧化程度减轻，电解质外渗量及丙二醛含量降低；活性氧自由基减少，抗氧化酶活性恢复到接近正常水平。但过量施用硝酸钾同样不利于小麦的生长。实验结果表明，小麦生长环境中最佳的K+/Na+ = 16:100。 4.2 抽穗期叶面喷施硝酸钾对盐胁迫下小麦花后生长及籽粒产量的影响 根据小麦生长环境中最佳的钾/钠 = 16:100的实验结果，设计了对100 mM NaCl生长环境中小麦抽穗期叶面喷施10 mM KNO3溶液试验（Hoagland 营养液中已含6 mM KNO3），得出外源硝酸钾有利于盐胁迫下小麦生长的恢复及籽粒产量的提高，DK961和JN17的穗粒数分别比单纯盐胁迫时提高了1.9%和7.1%；千粒重分别提高了2.3%和2.8 %；产量分别提高了4.5%和12.3%；叶面喷施钾肥后，盐胁迫对耐盐小麦产量指标影响变小，小麦各项指标恢复到接近于对照水平。盐敏感小麦品种受到盐胁迫的伤害较重，产量下降幅度较大，施钾肥后小麦盐胁迫症状虽有改善，但仍与对照相差较远。所以，盐胁迫下小麦高产优质栽培中，耐盐品种的选用是首要的。 4.3外源硝酸钾对盐胁迫下花后小麦旗叶气体交换的影响 盐胁迫下小麦叶面喷施钾肥，旗叶光合速率在灌浆期比不施钾处理显著升高，且维持高光合速率时间延长，小麦后期衰老速率减缓。由于施钾处理使旗叶光合速率提高，功能期延长，使籽粒可溶性总糖含量和蔗糖含量高于不施钾的处理，促进了淀粉合成底物的供应，由此促进了淀粉的合成。盐胁迫下小麦抽穗期施钾，可促进小麦旗叶、籽粒的碳、氮代谢，淀粉合成速率加快。同时游离氨基酸含量增加，籽粒中蛋白质合成底物的供应增加，蛋白质产量提高。适宜的钾肥处理能够显著促进小麦植株碳、氮代谢过程，加速碳水化合物和蛋白质的合成，使籽粒蛋白质、淀粉产量提高。 4.4外源硝酸钾对盐胁迫下小麦花后旗叶抗衰老酶活性的影响 盐胁迫可使小麦代谢过程中产生的活性氧自由基增多，刺激酶促防御系统的保护酶（如，SOD、POD、CAT等）活性提高，但当盐浓度超过其上限时，酶活性达到一定的极限，活性氧自由基不能及时的清除，代谢发生紊乱，植株加速衰老或不能正常生长，出现“早死”现象。外源硝酸钾可有效缓解这一抑制作用，提高小麦在盐胁迫下的代谢能力，减少活性氧自由基的产生，减轻活性氧清除系统的压力，能较长时间维持叶片细胞结构的完整性，提高小麦抵抗盐胁迫的能力。 4.5 盐胁迫下小麦优质高产栽培技术规程 研究结果表明：选用高产优质抗盐小麦新品种，并合理配合施用钾肥是获得小麦优质高产的一项有效措施： 1） 选用高产优质抗盐小麦新品种 在品种选用上，首先要考虑苗期耐盐力好、个体分蘖强、成穗率高三大因素，在此基础上选择多穗、粒大、粒多的性状。 2）配合施用钾肥 钾肥基施和抽穗期叶面喷施皆对盐胁迫下小麦生长有促进作用。钾肥的施用量应根据土壤盐浓度而定，小麦生长环境中最佳的K+/Na+比值为16:100。

Studies on some physico-chemical factors of Kaptai lake

The present investigation dealt with the climatic and some physico-chemical conditions of the Kaptai lake with respect to their monthly variation. Air temperature was found always higher than water temperature. Vertical variation in temperature (0.8-4.7°C) was observed in all months. The water level fluctuates appreciably throughout the year. Wide seasonal fluctuations were also noted in water transparency. The lake was found to be slightly hard and alkaline pH. Dissolved oxygen (DO) (6.4-9.1 mg/l) and free carbondioxide (4.7- 6.0 mg/l) contents showed favourable condition for aquatic lives. DO at different depth has shown no wide variation (1.0-2.4 mg/1). Conductivity ranged between 91.9±7.1 and 106.4 ±5.2 mS/cm.

Larval rearing of a freshwater prawn Macrobrachium gangeticum

Observations were made on the larval development of a freshwater prawn, Macrobrachium gangeticum, which revealed that hatching occurred in freshwater but the larvae failed to survive after 2nd molting. Salinity was necessary for survival of the larvae after 2nd molting. The complete larval development involved nine larval stages and the 10th stage was considered to be the post-larva which measured between 4.5 and 5.0 mm in length. All the larval stages were completed within 26 days of hatching. Specimens from each larval stage were taken out and examined under a microscope.

Ecology of Shakla heel (Brahmanbaria), Bangladesh

The bed Shakla, comprising an average area of 75.0 ha is located in the northeastern region (Brahmanbaria district) of Bangladesh. The study was carried out to assess the ecological aspects of bed ecosystem. Surface run-off and increase inflow of rain water from the upper stretch during monsoon cause inundation and resumption of connection between beel and parent rivers. The range of dissolved oxygen (DO) content ( 4.5-8.9 mg/L) was found congenial for aquatic life. pH was in the alkaline range (7.3-8.5) and free C02 was reletavely high. Lower values of total hardness and total alkalinity indicated less nutrients in the beel water. A wide variation (1.4-27.2 x 103 ceHs/L) in the standing crop of total plankton was recorded during study period of which phytoplankton alone contributed about 90%. Phytoplankton diversity in the beel represented by three groups viz. Chlorophyceae, Myxophyceae and Bacillariophyceae in order of abundance. A total of 52 fish species belonging to 36 genera, 20 families and 1 species of prawn were identified so far from the beel. About l3 types of fishing method were found in operation. Seine nets (moshari berja, ghono berjal) and gill net (current jal) were identified as detrimental gear killing juveniles of different species during post spawning period. Kua fishing was also found harmful due to dewatering nature. A total of 11 species belonging to 11 genera and 10 families of aquatic weeds were identified from the beet The eggs of Macrobrachium Jamarrei were identified into the Najas najas vegetation during April-September.

Alternative phosphorus sources for formulated fish feed

An experiment was conducted to evaluate the possibility of using inorganic fertilizer triple super phosphate (TSP), inorganic fertilizer 16:20 (a 16:20 grade fertilizer contains 16 percent N and 20 percent P20 5), rice-bran and duck-manure as phosphorus sources in formulated fish feed for Nile tilapia ( Oreochromis niloticus). Experiment was conducted for a period of 2 months in net-cages suspended in fertilized earthen ponds and all male sex-reversed Nile tilapia (9.39- 10.37 g) were used in the experiment. Seven treatments including one non-feed treatment were used in this experiment. Treatment 1 (non-feed), treatment 2 (-P) where fish fed with phosphorus non-supplemented diet acted as control 1 and treatment 3, 4, 5, 6 and 7 where fish fed with 3% di-calcium phosphate (DCP), 3% triple supper phosphate (TSP), 7% 16:20 inorganic fertilizer, 30% rice-bran and 30% duck-manure supplemented diet, respectively. Results showed that the TSP and 16:20 grade inorganic fertilizer supplementation in diets as phosphorus sources were equivalent to DCP (Di-calcium phosphate) supplementation in terms of growth performance, feed utilization efficiency and final body composition of Nile tilapia. Ricebran and duck-manure were not found as good phosphorus sources.

Studies on the suitability of producing value-added products from silver carp, Hypophthalmichthys molitrix

Silver carp, Hypophthalmichthys molitrix is contributing significantly to the total production of fish through aquaculture in Bangladesh. However, its low market price has become a serious concern to the fish farmers. The suitability of silver carp mince for the production of various value-added products (VAPs) - surimi, fish sausage, fish burger and fish stick was studied during April-September 2000 to ensure more appropriate and profitable utilization of silver carp. Surimi/frozen mince block was produced by washing the silver carp mince with 0.1% NaCl for 7-8 min (4-5 min agitation and 3-4 min settling). A two-step heating schedule for incubation at 50°C for 2 h and cooking at 95°C for 30 min gave high textured good quality consumer product. With the addition of cryoprotectants, surimi could be kept frozen for 5 months without loosing [sic] much of its textural and sensory qualities. Mince-mix and a batter with different ingredients and spices were formulated to produce fish burger using potato smash as the binding agent. Fish flake-mix and a batter with different ingredients and spices were formulated to prepare fish stick using both potato starch and potato smash as filler ingredients. Unwashed and washed frozen mince block or fresh flesh of silver carp was used to prepare fish sausage by heating at 100°C for 1 h after incubating at 50°C for 2 h. A spice-mix formulated with various local spices at the rate of 1.0-1.2% gave good texture and flavor to the sausage. A good-appeared sausage-pink color was developed by combining three food-grade colors of asthaxanthin. Products prepared with potato starch, potato smash and rice smash had an acceptable bacterial load in refrigeration (5°C) for up to 8 days and in room temperature (28°C) for up to 3 days. No coliform bacteria were found in the products prepared.

顶体反应抑制剂4'- 乙酰胺苯基4-胍基苯甲酸酯(AGB)具有阻断HIV-1进入细胞的作用

】目的: 研究4'- 乙酰胺苯基4- 胍基苯甲酸酯(AGB)抗 HIV-1 活性及作用靶点。方法: 通过 AGB对宿主细胞的毒性实验、合胞体抑制实验、融合阻断实验、对HIV-1感染细胞的保护作用实 验和对HIV-1急性感染细胞p24抗原产生的抑制作用等试验，观察AGB对HIV-1复制的影响和作 关键词: AGB; HIV-1; 病毒进入; 杀微生物剂; 杀精子活性 中图分类号: R967; 文献标识码: A 文章编号: 0253-357X(2005)11-0660-05 本研究为国家高技术研究发展计划(2003AA219142)、国 家科技攻关计划 (2004BA719A14)、中国科学院知识创新 工程重要方向(KSCX2-SW-216; KSCX12-SW-11)、云南 省科技攻关计划(2004NG12)和云南省生育调节与少数民 族优生研究重点实验室资助项目 通讯作者: 郑永唐; Tel: +86-871-5195684; Fax:+86-871-5191823; E-mail: zhengyt@mail.kiz.ac.cn 在我国, 人免疫缺陷病毒(human immunodeficiency virus, HIV)危害日趋严重，处在全国低流行 与局部地区及特定人群高流行并存的态势。卫生部 的数据显示，截止2005 年3 月底，全国累计报告 HIV 感染者114 703 例。专家估计我国实际HIV 感 染者超过100 万人。预计到2010 年, 全国HIV感染 者将突破千万。截止2004 年底, 云南省累计报告的 HIV 感染者已达28 391 人, 是全国流行最严重的地 区。艾滋病流行正由高危人群向一般人群传播。 新的证据显示近年来由性传播途径感染的比例有所 上升, 女性感染者的比例有较大幅度的上升, 迫切需 要发展一种女性可自主控制的方法 [1]。杀微生物剂 是可以局部用药于阴道和宫颈、能够杀灭或抑制 包括HIV等病毒性和细菌性病原体、人工合成或天 然的药物。具有避孕作用的杀微生物剂更是近年 来的研究热点，也具有广阔的应用前景[2,3]。 顶体酶是存在于精子顶体内的一种类胰蛋白 酶, 它是受精过程中的一种重要的蛋白水解酶, 此酶 能水解卵细胞的透明带, 使精子能够与卵细胞相融 合; 顶体酶还能促进生殖系统中激肽的释放, 后者能 够增强精子的活力和促进精子的运动, 顶体酶的失 活将导致不孕[4]。AGB(4'- 乙酰胺苯基 4- 胍基苯甲 酸酯)是顶体酶的抑制剂, 实验表明在多种动物中有 很好的杀精子作用[5-7]。Bourimbaiar等[8]曾报道AGB 还具有体外抗HIV-1的作用, 活性较N-9高, 且毒性 较小。在本实验中, 我们发现AGB 的体外抗HIV-1 活性主要是阻断HIV-1 进入细胞。 用机制。结果: AGB抑制HIV-1IIIB诱导C8166细胞形成合胞体, EC50为39.5 μg/ml; 抑制HIV-1感染 细胞上清中HIV-1 p24抗原的表达, EC50为33.36 μg/ml; 阻断HIV-1慢性感染H9细胞与正常C8166 细胞间融合的作用。结论: AGB具有阻断HIV-1 进入宿主细胞的作用，是一种有前景的具杀精子 作用的杀微生物剂。

In-situ deposition of sparse vertically aligned carbon nanofibres on catalytically activated stainless steel mesh for field emission applications

We report on an inexpensive, facile and industry viable carbon nanofibre catalyst activation process achieved by exposing stainless steel mesh to an electrolyzed metal etchant. The surface evolution of the catalyst islands combines low-rate electroplating and substrate dissolution. The plasma enhanced chemical vapour deposited carbon nanofibres had aspect-ratios > 150 and demonstrated excellent height and crystallographic uniformity with localised coverage. The nanofibres were well-aligned with spacing consistent with the field emission nearest neighbour electrostatic shielding criteria, without the need of any post-growth processing. Nanofibre inclusion significantly reduced the emission threshold field from 4.5 V/μm (native mesh) to 2.5 V/μm and increased the field enhancement factor to approximately 7000. © 2011 Elsevier B.V. All rights reserved.

A comprehensive study of lysozyme adsorption using dual polarization interferometry and quartz crystal microbalance with dissipation.

Protein adsorption plays a crucial role in biomaterial surface science as it is directly linked to the biocompatibility of artificial biomaterial devices. Here, elucidation of protein adsorption mechanism is effected using dual polarization interferometry and a quartz crystal microbalance to characterize lysozyme layer properties on a silica surface at different coverage values. Lysozyme is observed to adsorb from sparse monolayer to multilayer coverage. At low coverage an irreversibly adsorbed layer is formed with slight deformation consistent with side-on orientation. At higher coverage values dynamic re-orientation effects are observed which lead to monolayer surface coverages of 2-3 ng/mm² corresponding to edge-on or/and end-on orientations. These monolayer thickness values ranged between 3 and 4.5 nm with a protein density value of 0.60 g/mL and with 50 wt% solvent mass. Further increase of coverage results formation of a multilayer structure. Using the hydration content and other physical layer properties a tentative model lysozyme adsorption is proposed.

A comprehensive study of lysozyme adsorption using dual polarization interferometry and quartz crystal microbalance with dissipation

Protein adsorption plays a crucial role in biomaterial surface science as it is directly linked to the biocompatibility of artificial biomaterial devices. Here, elucidation of protein adsorption mechanism is effected using dual polarization interferometry and a quartz crystal microbalance to characterize lysozyme layer properties on a silica surface at different coverage values. Lysozyme is observed to adsorb from sparse monolayer to multilayer coverage. At low coverage an irreversibly adsorbed layer is formed with slight deformation consistent with side-on orientation. At higher coverage values dynamic re-orientation effects are observed which lead to monolayer surface coverages of 2-3 ng/mm2 corresponding to edge-on or/and end-on orientations. These monolayer thickness values ranged between 3 and 4.5 nm with a protein density value of 0.60 g/mL and with 50 wt% solvent mass. Further increase of coverage results formation of a multilayer structure. Using the hydration content and other physical layer properties a tentative model lysozyme adsorption is proposed. © 2012 Elsevier Ltd.

DE-71-induced apoptosis involving intracellular calcium and the Bax-mitochondria-caspase protease pathway in human neuroblastoma cells In vitro

Polybrominated diphenyl ethers (PBDEs) are used extensively as flame-retardants and are ubiquitous in the environment and in wildlife and human tissue. Recent studies have shown that PBDEs induce neurotoxic effects in vivo and apoptosis in vitro. However, the signaling mechanisms responsible for these events are still unclear. In this study, we investigated the action of a commercial mixture of PBDEs (pentabrominated diphenyl ether, DE-71) on a human neuroblastoma cell line, SK-N-SH. A cell viability test showed a dose-dependent increase in lactate dehydrogenase leakage and 3-(4,5-dimethylthia-zol-2-yl)-2,5-diphenyl-tetrazolium bromide reduction. Cell apoptosis was observed through morphological examination, and DNA degradation in the cell cycle and cell apoptosis were demonstrated using flow cytometry and DNA laddering. The formation of reactive oxygen species was not observed, but DE-71 was found to significantly induce caspase-3, -8, and -9 activity, which suggests that apoptosis is not induced by oxidative stress but via a caspase-dependent pathway. We further investigated the intracellular calcium ([Ca2+](i)) levels using flow cytometry and observed an increase in the intracellular Ca2+ concentration with a time-dependent trend. We also found that the N-methyl d-aspartate (NMDA) receptor antagonist MK801 (3 mu M) significantly reduced DE-71-induced cell apoptosis. The results of a Western blotting test demonstrated that DE-71 treatment increases the level of Bax translocation to the mitochondria in a dose-dependent fashion and stimulates the release of cytochrome c (Cyt c) from the mitochondria into the cytoplasm. Overall, our results indicate that DE-71 induces the apoptosis of ([Ca2+](i)) in SK-N-SH cells via Bax insertion, Cyt c release in the mitochondria, and the caspase activation pathway.

Physiological comparison between colonial and unicellular forms of Microcystis aeruginosa Kutz. (Cyanobacteria)

In order to gain insight into the bloom sustainment of colonial Microcystis aeruginosa Katz., physiological characterizations were undertaken in this study. Compared with unicellular Microcystis, colonial Microcystis phenotypes exhibited a higher maximum photosynthetic rate (Pm), a higher maximum electron transfer rate (ETRmax), higher phycocyanin content, and a higher affinity for inorganic carbon (K-0.5 DIC <= 8.4 +/- 0.7 mu M) during the growth period monitored in this study. This suggests that photosynthetic efficiency is a dominant physiological adaptation found in colonial Microcystis, thus promoting bloom sustainment. In addition, the high content of soluble and total carbohydrates in colonial Microcystis suggests that this phenotype may possess a higher ability to tolerate enhanced stress conditions when compared to unicellular (noncolonial) phenotypes. Therefore, high photosynthetic activities and high tolerance abilities may explain the bloom sustainment of colonial Microcystis in eutrophic lakes.

A phototaxis inhibition assay using barnacle larvae

The effects of sublethal concentrations of phenol and cadmium on the phototactic responses of the stage II nauplii of the barnacle Balanus amphitrite were investigated. Increased toxicant concentrations caused a reduction in phototactic responses. Balanus amphitrite nauplii exposed to nominal phenol concentrations of 100 ppm and higher for 1-12 h failed to exhibit phototactic responses, while longer exposure times of 24 and 48 h reduced the lowest observable effect concentration (LOECs) to 80 and 60 ppm, respectively. For cadmium, the LOECs, based on nominal concentrations, for B. amphitrite following 1, 6, 12, 24, and 48 h exposures were 20, 4.5, 4.0, 1, and 0.75 ppm, respectively. The LOECs can be significantly reduced by increasing the duration of exposure to the toxicants. A good relationship exists between the phototactic response and toxicant concentration as well as exposure time. Results of this study indicate that the toxicant-induced reduction in phototactic responses of barnacle larvae can be used in a sensitive, rapid screening test for ecotoxicological assessments. (C) 1997 by John Wiley & Sons, Inc.

New observations on the pressure dependence of luminescence from Eu2+-doped MF2 (M = Ca, Sr, Ba) fluorides

The luminescence from Eu2+ ions in MF2 (M = Ca, Sr, Ba) fluorides has been investigated under the pressure range of 0-8 GPa. The emission band originating from the 4f(6)5d(1) -> 4f(7) transition of Eu2+ ions in CaF2 and SrF2 shows the red-shift as increasing pressure with pressure coefficients of -17 meV/GPa for CaF2 and -18 meV/GPa for SrF2. At atmospheric pressure, the emission spectrum of BaF2:Eu2+ comprises two peaks at 2.20 and 2.75 eV from the impurity trapped exciton (ITE) and the self-trapped exciton (STE), respectively. As the pressure is increased, both emission peaks shift to higher energies, and the shifting rate is slowed by the phase transition from the cubic to orthorhombic phase at 4 GPa. Due to the phase transition at 4-5 GPa pressure, the ITE emission disappears gradually, and the STE emission is gradually replaced by the 4f(6)5d(1) -> 4f(7) transition of Eu2+. Above 5 GPa, the pressure behavior of the 4f(6)5d(1) -> 4f(7) transition of EU2+ in BaF2: EU2+ is the same as the normal emission of Eu2+ in CaF2 and SrF2 phosphors.