利用DSC和EPR技术研究杜仲种子的贮藏条件

种子贮藏稳定性对于种质资源的长期保存具有重要意义，目前关于种子贮藏的最新理论为玻璃态理论，该理论认为种子的玻璃化有利于种子的长期贮藏。当种子处于玻璃态时，玻璃化物质的高度粘滞性降低了种子细胞内分子流动性，阻止了细胞质中分子的扩散，从而减少老化过程中细胞结构的损伤和化学组分的变化，延缓种子老化劣变反应速率，延长贮藏寿命。评价玻璃态的一个重要指标是玻璃化转变温度，当种子贮藏于玻璃化温度或以下10℃～30℃范围内时，种子具有最佳的贮藏稳定性。因此，检测种子的玻璃化转变温度对于种子的长期有效贮藏具有重要指导意义。 本研究将差示量热扫描技术（DSC）与电子顺磁共振波谱仪技术（EPR）应用于杜仲种子玻璃化转变温度方面的研究。在DSC方法中，选用4.4%～31.6%含水量范围的杜仲种胚分别进行了DSC图谱扫描。EPR方法选用3-羧基-2,2,5,5-四甲基吡咯烷-1-氧（3-carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl，CP）和2,2,6,6-四甲基哌啶（4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy，TEMPO）作为探针标记杜仲种胚， 利用EPR技术测定不同含水量杜仲种胚的分子运动，通过对EPR图谱参数的分析计算，最终确定不同含水量杜仲种胚的玻璃化转变温度。 DSC实验结果显示，含水量为22.3%、28.0%、31.6%的杜仲种胚在0℃ 左右出现了一个水的熔融峰。该熔融峰的面积代表了自由水含量的多少，随着种胚含水量的降低该熔融峰面积减小。4.4%～31.6%含水量范围的杜仲种胚在-28℃左右还出现了一个熔融峰，推测此峰为杜仲种胚中某类物质熔融所形成的熔融峰。然而在此曲线上我们未观察到标志玻璃化转变的“台阶”出现。 CP-EPR实验的结果表明，利用EPR测定得到含水量为4.4%～11.6%的杜仲种胚在-110℃～20℃温度范围内，同一含水量的杜仲种胚随着温度的升高，分子运动速率加快;在同一温度条件下，高含水量的种胚比低含水量种胚的分子运动速率快。通过CP-EPR波谱两外缘峰最大距离（2Azz）的测定和数据统计分析，得到含水量为4.4%、5.7%、8.6%、10.3%、11.6%杜仲种胚的玻璃化转变温度分别约为44℃、25℃、4℃、-31℃、-43℃。可以把测定的杜仲种胚的这几个含水量的玻璃化转变温度与杜仲种子贮藏相结合，用于指导杜仲种子的贮藏。 TEMPO-EPR实验测定分析得到含水量为2.1%、3.4%、4.8%、8.3%、11.2% 的杜仲种胚的玻璃化转变温度分别为-21℃、-18℃、-24℃、-20℃、-27℃，玻璃化转变温度随含水量升高其变化的规律不明显，这与CP-EPR实验测得的结果有着较明显的差别。通过分析，认为对于脂质含量较高的杜仲种胚，随着含水量的降低，作为标记化合物的TEMPO随着脱水进入脂相，从而不能真实反映出不同含水量种胚的分子运动情况。与TEMPO标记相比，CP标记可能能够更真实地反映不同含水量杜仲种胚细胞质分子运动的情况，根据其分子运动情况得到的玻璃化转变温度更准确。

高等植物PSI ,PSII反应中心及天线系统色素蛋白复合体结构与功能的研究

一、实验证明了Cd H、Mg“在小麦类囊体膜上色素蛋白复合体的解聚和再聚合过程中，具有不同的作用。因此，二阶阳离子对激发能在光系统间的分配调节作用，可能不能仅仅用“静电现象”(Barber(1980))去解释。分析表明，在Ca2+作用下与PSII内周天线CP-47，GP-43多肽结合的L H C II和LHClb是来自间质膜区的PS I系统的。从PSI迁移到P S II的捕光色素蛋白，增加了PSII的捕光截面，从而促进了激发能有利于PsII分配。 二、Ca2*、Mg2+对小麦和菠菜类囊体膜光谱性质的影响有所差异。Ca2+对小麦类囊体膜光谱性质的影响还可以随着介质中Ca2+的消除而消除。同小麦类囊体膜相比，菠菜PSII以及LHCII更为集中在基粒区域，这可能是菠菜类囊体膜强Fv以及高F888／F735，F89H／F735比值的原因。因此，Ca2+，HgH对激发能在光系统间分配的调节作用是依赖于光系统间激发能及天线色素蛋白的分配状况的。 三、对菠菜叶中分离的PSII-RC: D1-D2-cyt b55g复合物进行的低温荧光发射光谱的研究表明，这一复合物可能具有F681和F684两种波长的低温荧光发射，但它们通常并不是同时存在，而是取决于Ca-670与Ca-680 Chla分子的相对含量的。PSII-RC内周无线GP-47，GP-43多肽的存在是D1-D2-cyt b559复合物低温荧光发射红移的原因;而D1一D2cyt b559复合物的不稳定性则与其低温荧光发射的蓝移现象有关。 从蕹菜叶中分离的Dl—D2-cyt b559复合物的F 381低温荧光发射也是由其相对含量较高的C．i-6 7 0 Chla分子的存在决定的。对蕹菜D 1一D 2-cyt b559复合物中的分析还表明，F 681的低温荧光发射直接来源于Di／D2复合物，而415nm处相对较强的吸收，则可能主要是与Pheo的存在有关的。 四、多肽分析与光谱分析的对照表明，CP-26内周天线多肽可能是PSII中F695低温荧光发射的真正来源。 五、实验分析了蔗糖密度离心分离的LHClI和PSI颗粒。结果排除了CP-27多肽（以及CP，一2 5，GP-47，CP -4 3多肽）具有F695低温荧光发射的可能，因此支持了CP-26多肽是PSII中F695低荧光发射来源的看法。对PsI颗粒的分析表明，P700的存在可能是与PSI-RC中较大的Sub-I亚基相联系的。 六、根据以上的研究结果，提出了PSI，PSII在类囊体膜上的结构模式，并对其内容进行了分析和讨论。

水分胁迫对光合作用影响的研究

1．水分胁迫降低了水稻叶片的光合速率。轻度及中度水分胁迫下，气孔的限制是光合速率下降的主要原因;而严重水分胁迫下，叶肉细胞光合能力的降低是光合速率下降的主要原因。叶肉细胞光 合能力的降低可能是由于光合量子效率、光合电子传递速率和光合磷酸化活力及羧化效率下降所致。 2．水分胁迫降低了小麦叶片的可变荧光产量、可变荧光淬灭速率、荧光上升互补面积，叶绿体的室温荧光产量、可变荧光产量以及DCMU作用下的小麦叶片及叶绿体的可变荧光产量，表明光系统Ⅱ受到了伤害。光系统Ⅱ氧化侧的人工电子供体(DPC) 能部分恢复受抑制的叶绿体可变荧光和光系统II的电子传递速率，说明水分胁迫对光系统Ⅱ的损伤不仅位于氧化侧，也可能在反应中心上。 3．水分胁迫抑制了激发能向PSII的传递;降低了Mg2+对叶绿体可变荧光及激发能在两个光系统间分配的调节能力。水分胁迫使PS II内外周天线色素蛋白复合体（CPa和LHCⅡ）和PSⅠ叶绿素a蛋白复合体(CPⅠ、CPⅠa和CPⅠb)含量下降，其中以LHCⅡ降低幅度最大。从类囊体膜多肽分析结果，发现25KD多肽随着水分胁迫的加剧其含量显著降低。 4．水分供应充分及轻度和中度水分胁迫下，高氮素营养对水稻光合作用有明显的促进作用;而严重水分胁迫则削弱了高氮营养对光合作用的促进作用，使高氮营养水稻叶片在严重水分胁迫下的光合速率反而比低氮营养叶片低，这可能与严重水分胁迫下，高氮叶片水势、气孔导度、光合羧化效率、光合量子产量及RuBP再生速率比低氮叶片有更大的下降有关。两种氮素营养水平下，轻度和中度水分胁迫均提高了叶片的水分利用效率;而严重水分胁迫则使叶片的水分利用效率降低，但始终是高氨营养水稻叶片的水分利用效率高于低氮叶片。

马铃薯Y病毒外壳蛋白基因的导入以及转基因马铃薯植株的大田攻毒

应用四种不同的马铃薯试管微型薯诱导体系生产试管微型薯，通过比较建立了—种有效的试管微型薯诱导系统。这种诱导系统使用液体培养基，具有试管微型薯发生频率高、薯块体积大和微型薯形成早的特点。同时，此系统使用的培养基成分成本低、方法简便以及所用设备简单，适用于容器内大批量生产马铃薯试管微型薯以及马铃薯种质资源的保存。 对银离子在马铃薯叶片组织培养过程中对愈伤组织诱导或芽分化和再生的影响作了研究。结果表明银离子通过抑制叶片组织培养过程中形成的乙烯与其受体的结合从而促进芽再生，但是其对叶片愈伤组织的诱导无显著效果。银离子的这些作用在通过同时应用2，4-D而明显表现出来。2，4-D通过促进乙烯的生物合成而降低银离子的促进作用，两者则通过对乙烯的调节而影响马铃薯叶片的愈伤组织诱导和芽分化再生。 将马铃薯Y病毒外壳蛋白基因通过根癌农杆菌双元载体系统导入马铃薯品种Desiree、K4和Favorita，获得了若干转基因株系。除了K4品种中—转化株系具有非正常生长形态外，其余转基因植株都生长发育正常。由此表明以根癌农杆菌介导的马铃薯转化中，构建于双元载体上的外源目的基因是随机进入并整合到受体细胞的染色体上。具有畸形生长性状的转基因植株的产生说明了PVY CP基因的整合可能干扰了控制正常生长发育、尤其是形态建成的基因表达。 在转化试验中，应用了试管微型薯薄片、茎切段和叶片三种外植体作为转化材料。对转化过程中农杆菌对外植体的侵染时间、共培养时间、外植体的类型以基因型对转化频率的影响作了比较研究。发现以试管微型薯薄片和茎切段作为受体的最佳侵染时间是十分钟，而叶片则为五分钟，三种外植体的最佳共培养时间皆为四天。在各种处理的最佳条件下，Desiree比K4具有相对较高的转化频率，表明马铃薯Desiree比K4在转化反应上更温和或顺从。 通过比较几种由不同统计得出的农杆菌介导的转化频率，认为使用“净转换频率”(Net Transformation Frequency)能更精确地表达马铃薯的转化效率。而在以前的报导中还没有—种统一的、并且能被广泛接受和使用的表达转化效率的参数或指标。． 以叶片作为起始材料的转化具有较高的转化频率。在转化外植体的植株再生过程中应用了2，4-D和AgN03两种乙烯调节剂分别于愈伤组织诱导和芽分化再生阶段，使其产生高频的植株再生。尤其是它的净化频率明显高于其它外植体的转化频率，并且无显著品种之间的差异，具有高效马铃薯转化系统的特征。 以聚合酶链式反应(PCR)检测转化再生植株得到的结果与DNA杂交(Southern blot analysis)的鉴定结果比较，结论是相同的。由此表明在以农杆菌介导的马铃薯转化试验中，PCR可被用于证实外源目的DNA的导入，它以简便、迅速的特点帮助节省时间以及提供及时的转化证据。 对三个马铃薯品种的一系列转基因株系在大田条件下进行了攻毒试验．最后从Favorita 品种中筛选出了两个抗性较强的无性系，它们具有明显较低的病毒侵染发生频率以及正常的生长发育性状，具有很大潜力成为生产上推广应用的抗病新品种。

Genetic diversity of cattle in South China as revealed by blood protein electrophoresis

Genetic variation of 31 blood protein loci in 236 cattle from eight South China populations (including mithan, Bos frontalis) and a Holstein population was investigated by means of horizontal starch gel electrophoresis. Thirteen loci (ALB, CAR, Hb-b, Np, PGM, Amy-I, PEP-B, AKP, 6PGD, Cp, Pa, EsD, and TF) were found to be polymorphic. The comparison of average heterozygosities (H) shows that all the native cattle embrace a rich genetic diversity Our results on protein polymorphism suggest that cattle in China originated mainly from Bos indicus and Bos taurus; Xuwen, Hainan, Wenshan, and Dehong cattle and the Dehong zebu are close to zebu-type cattle, and Diqing and Zhaotong cattle are close to the taurine. The mithan was very different from other native cattle, and we suggest that its origin was complicated and may be influenced by other cattle species.

意大利蜜蜂毒Melittin组分的研究(Ⅱ)-活化家兔血小板聚集作用机制

分离纯化的意大利蜜蜂毒Melittin组分活化家兔血小板聚集作用,实验结果表明,Melittin在终浓度为65#mu#g/mL,其活化家兔血小板的聚集率为54.95±10.91;分别加入ADP清除剂CP/CPK,花生四烯酸环氧化酶抑制剂阿斯匹林及血栓烷合成酶抑制剂咪唑后,不能抑制其聚集作用,聚集率依次为47.36±0.20,50.97±15.60及51.88±11.49。TXB_(2)放射免疫测出,花生四烯酸活化家兔血小板生成的TXB_(2)量(即1445.65±113.50#mu#g/mL)远远高于Melittin活化的生成量(即117.51±57.55#mu#g/mL)。

Stability and molecular modeling of triplex DNA inhibiting DNA binding protein binding to the core promoter of hepatitis B virus.

Two three-dimensional structure models of the 21nt oligodeoxyribonucleotides, CPI (G3TG-2TGT2G5TG2TGT) and CP3 (TGTG2TGST2GTG2TG3), were constructed by InsightII (MSI) software in IRIS Indigo2 (SGI) workstation using the crystal structure of TAT tripler formation as the template. The initial structures subsequently were minimized by molecular mechanics. The final structures were believed as the dominant conformation. The results showed that the energy of CP1 is lower than that of CP3, and the former is more stable than the latter. Moreover, the results further proved that the 21nt oligodeoxyribo-nucleotide CP1 stably combines with the core promoter (Cp) fragment of hepatitis B virus (HBV) to form a tripler DNA, and CP1 specifically inhibits a specific cellular factor (DNA binding protein) binding to Cp fragment. These results indicated that specific repression of gene transcription of HBV DNA might be possible by tripler-formation DNA.

In vitro anti-HIV and -HSV activity and safety of sodium rutin sulfate as a microbicide candidate

Sodium rutin sulfate (SRS) is a sulfated rutin modified from the natural flavonol glycoside rutin. Here, we investigated its in vitro anti-HIV and -HSV activities and its cytotoxic profile. Fifty percent inhibitory concentration (IC50) values of SRS against HIV-1 X4 virus IIIB, HIV-1 R5 isolates Ada-M and Ba-L were 2.3 +/- 0.2, 4.5 +/- 2.0 and 8.5 +/- 3.8 mu M with a selectivity index (SI) of 563, 575 and 329, respectively. Its IC50 against primary R5 HIV-1 isolate from Yunnan province in China was 13.1 +/- 5.5 mu M, with a Sl of 197. In contrast, unsulfated rutin had no activity against any of the HIV-1 isolates tested. Further study indicated that SRS blocked viral entry and virus-cell fusion likely through interacting with the HIV- I envelope glycoprotein. SRS also demonstrated some activity against human herpes simplex virus (HSV) with an IC50 of 88.3 +/- 0.1 mu M and a Sl of 30. The 50% cytotoxicity concentration (CC50) of SRS was >3.0 mM, as determined in human genital ME 180, HeLa and primary human foreskin fibroblast cells. Minimum inhibitory concentration of SRS for vaginal lactobacilli was >3.0 mM. These results collectively indicate that SRS represents a novel candidate for anti-HIV-1/HSV microbicide development. (C) 2007 Elsevier B.V. All rights reserved.

固氮蓝藻Anabaena sp.7120的叶绿素蛋白复合体的分离和光谱特性的研究

用光合膜片增溶和SDS-聚丙烯酰胺凝胶电泳方法,从固氮蓝藻Anabaena sp.7120分离到7条色素带。迁移率较慢的五条叶绿素蛋白复合体带,具有相同的吸收光谱和室温荧光光谱特性。它们的红区最大吸收峰在676nm;蓝区最大吸收峰在438nm。它们的室温荧光发射最高峰在672—673nm;在710,732和740nm都有小峰。这些是CPⅠ叶绿素所特有的。我们认为这5条带都是属于光系统Ⅰ的叶绿素蛋白复合体。另一条迁移率稍快的叶绿素蛋白复合体带为CPⅡ。它的红区最大吸收峰在672nm;蓝区最大吸收峰在436n

Molecular cloning and characterization of common carp (Cyprinus carpio L.) TCR gamma and CD3 gamma/delta chains

Partial cDNA sequences of TCR gamma and CD3 gamma/delta were isolated from the thymus of common carp (Cyprinus carpio L.) by the method of suppression subtractive hybridization (SSH). Subsequently the full length cDNAs of carp TCR gamma and CD3 gamma/delta were obtained by means of 3' RACE and 5' RACE, respectively. The full length of carp TCR gamma chain is 1368 bp and encodes 326 amino acids including a signal peptide region of 19 amino acids and a transmembrane region of 23 amino acids at the C-terminal region from aa 291 to 313. The V region of carp TCR gamma contains 109 amino acids, the core motif FGXG in J segment was also found in carp TCR gamma. The C region of carp TCR gamma contains the characteristic CX6PX6WX45C motif. The CP region of carp TCR C gamma contains 37 amino acids. The full length of carp CD3 gamma/delta is 790 bp and encodes 175 amino acids including a signal peptide region of 17 amino acids and a transmembrane region of 23 amino acids from aa 93 to 115. Similar to other known CD3 gamma/delta s, four cysteine residues in the extracellular domain and an immunoreceptor tyrosine-based activation motif ITAM (YxxL/Ix6-8YxxL/I) in the intracellular domain are also included in carp CD3 gamma/delta. Differing from other known CD3 gamma/delta s, carp CD3 gamma/delta tacks the CXXCXE motif in the extracellular domain. RTPCR analysis demonstrated that the expression of TCR gamma gene was mainly in the thymus and gill of 6-month carp, but in 18-month carp, TCR gamma gene was detected in all the examined tissues. The expression of CD3 gamma/delta gene was detected in all examined tissues of 6 and 18-month carp; among them, the highest expression level was in the thymus of 6-month carp. In situ hybridization showed that CD3 gamma/delta-expressing cells were widely distributed in the head kidney, spleen and kidney of carp, whereas in the thymus, they were densely distributed in the lymphoid outer zone and scattered in the epithelioid inner zone. (c) 2007 Published by Etsevier Ltd.

Effects of age and dietary protein level on digestive enzyme activity and gene expression of Pelteobagrus fulvidraco larvae

The present research studied the effects of age and dietary protein level on pepsin, trypsin and amylase activity and their mRNA level in Petteobagrus fulvidraco larvae from 3 to 26 days after hatch (DAH). Three DAH larvae were fed three isoenergetic diets, containing 42.8% (CP 43), 47.3% (CP 47) and 52.8% (CP 53) crude protein. Live food (newly hatched Artemia, unenriched) was included as a control. The effects of age on enzyme activity and mRNA were as follows: pepsin and trypsin activity in all treatment groups showed a significant (P < 0.05) increase at the beginning and decrease later although the timing of decrease was not the same among treatment groups and between the digestive enzymes. Pepsin and trypsin mRNA level followed the pattern of their respective enzyme changes. Age significantly affected amylase activity (P < 0.05) while age had no effect on amylase mRNA during the experimental period. The four diets significantly (P < 0.05) affected activity and mRNA level of pepsin and trypsin. Diets did not affect amylase activity or mRNA level. These results suggest that the effects of age on pepsin and trypsin gene expressions are at the transcriptional level. Dietary protein level does affect pepsin and trypsin gene expression in the early life of P. fulvidraco. There were no transcriptional effects on amylase gene expression. (c) 2005 Elsevier B.V. All rights reserved.

Culture of the terrestrial cyanobacterium, Nostoc flagelliforme (Cyanophyceae), under aquatic conditions

Both colonies and free-living cells of the terrestrial cyanobacterium, Nostoc flagelliforme (Berk. & Curtis) Bornet & Flahault, were cultured under aquatic conditions to develop the techniques for the cultivation and restoration of this endangered resource. The colonial filaments disintegrated with their sheaths ruptured in about 2 days without any desiccating treatments. Periodic desiccation played an important role in preventing the alga from decomposing, with greater delays to sheath rupture with a higher frequency of exposure to air. The bacterial numbers in the culture treated with seven periods of desiccation per day were about 50% less compared with the cultures without the desiccation treatment. When bacteria in the culture were controlled, the colonial filaments did not disintegrate and maintained the integrity of their sheath for about 20 days even without the desiccation treatments, indicating the importance of desiccation for N. flagelliforme to prevent them from being disintegrated by bacteria. On the other hand, when free-living cells obtained from crushed colonial filaments were cultured in liquid medium, they developed into single filaments with sheaths, within which multiple filaments were formed later on as a colony. Such colonial filaments were developed at 15, 25, and 30degreesC at either 20 or 60 mumol photons.m(-2).s(-1); colonies did not develop at 180 mumol photons.m(-2).s(-1), though this light level resulted in the most rapid growth of the cells. Conditions of 60 mumol photons.m(-2).s(-1) and 25degrees C appeared to result in the best colonial development and faster growth of the sheath-held colonies of N. flagelliforme when cultured indoor under aquatic conditions.

光通道性能在线监测模块

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

GaN 基半导体材料的非线性光学性质研究

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

Magnetointersubband oscillations of the two-dimensional electron gas in AlxGa1-xN/GaN heterostructures

Shubmkov-de Haas (SdH) measurements are performed over a temperature range of 1.5-20K in AL(0.22)Ga(0.78)N/GaN heterostructures with two subbands occupied. In addition to an intermodulation between two sets of SdH oscillations from the first and second subbands, a beating in oscillatory magnetoresistance at 12K is observed, due to the mixing of the first subband SdH oscillations and 'magnetointersubband' (MIS) oscillations. A phase shift of pi between the SdH and MIS oscillations is also clearly identified. Our experimental results, i.e. that the SdH oscillations dominate at low temperature and MIS oscillations dominate at high temperature, fully comply with the expected behaviour of MIS oscillations.