浙贝母鳞片细胞休眠解除前后超微结构的变化

浙贝母休眠解除后,鳞片近轴面表皮附近的几层细胞首先降解。本文观察了这些细胞在休眠解除前后超微结构的变化。与休眠状态时的细胞相比,解除休眠后的细胞中颗粒和丝状物的数量明显增加,一些细胞中出现了复杂的膜结构。线粒体的数目增加,常聚集在细胞核和细胞壁旁。胞间连丝的直径略有增加。休眠解除前后的细胞中,常可见到各类囊泡、多泡体与壁旁体,一些小囊泡正在进入细胞中。表明两种时期的细胞间都发生着物质和信息的交换     

温度对大蒜鳞茎休眠的影响及其在贮藏保鲜上的应用

大蒜鳞茎在通过休眠时,蒜瓣内出现一系列结构与生理变化,由于鳞片细胞内物质的转化、降解、外运,局部组织的衰退、瓦解以及幼芽的伸展,蒜瓣的食用品质逐步下降。温度可调节休眠进程,高温(32℃左右)明显阻抑休眠进展,鱗片细胞内含物的解体、物质的外运与呼吸消耗亦大大地被延缓或削弱,因而可较长期(半年以上)保持蒜瓣的鲜脆状态。     

短时间高温处理下桃树活性氧代谢与桃芽自然休眠解除的关系

以6年生曙光油桃为试验材料,研究40 ℃、45 ℃、50 ℃ 3个梯度高温短时间处理对桃树花芽和叶芽存活率、萌芽级数、活性氧含量及其相关酶活性的影响,探讨短时间高温处理对桃芽自然休眠解除的调控效应.结果表明：随着短时间高温处理时期的延后以及处理温度的升高和处理持续时间的延长,高温处理对桃芽自然休眠的解除作用增强.11月30日处理中,40 ℃处理对桃芽自然休眠的解除具有负调控效应,其萌芽级数、·OH和 O₂^-.产生速率、H₂O₂含量、过氧化物酶（POD）和过氧化氢酶（CAT）活性均低于对照,而超氧化物歧化酶（SOD）活性高于对照;45 ℃和50 ℃处理对桃芽自然休眠的解除呈正调控效应,其萌芽级数、·OH和 O₂^-·产生速率、H₂O₂含量及POD、CAT活性与对照相比明显升高,而SOD活性显著降低.12月10日处理中,40 ℃处理对桃芽自然休眠解除的调控效应不明显,45 ℃和50 ℃处理与11月30日处理相同,但前者对桃芽自然休眠的调控效果优于后者.相关分析表明,活性氧的迅速增加可能是高温解除桃芽自然休眠的原因.     

急纤虫营养细胞和休眠细胞的中间纤维-核骨架体系

利用生化分级抽提、DGD包埋—去包埋透射电镜术和SDS—PAGE凝胶电泳,研究了膜状急纤虫营养细胞和休眠细胞内中间纤维—核骨架体系的分化特征及其蛋白组成。观察到营养细胞中,位于细胞质不同区域的中间纤维形成网状,其网络的密度不同;核骨架中,核纤层位于细胞核周缘,薄层状,厚约50nm;核内骨架由较致密的纤维网络组成。休眠细胞内该结构体系依然存在,但位于细胞内不同层次的纤维网比营养细胞的同种结构要致密得多,这可能与纤毛虫脱分化时细胞大范围的收缩有关;休眠细胞的包囊壁中层壁存在相当于中间纤维的网络结构。SDS—PAGE电泳图谱显示,休眠细胞内该体系的蛋白组成发生了较明显的变化,其中保留了营养细胞的部分蛋白条带,丢失了部分条带,同时还产生了一些特异性条带。分析表明,膜状急纤虫的中间纤维—核骨架体系是细胞在营养条件下和休眠状态下都稳定存在的结构;而纤毛虫形成休眠细胞后中间纤维—核骨架体系及蛋白组成上的变化提示,细胞在休眠状态下,基因的表达水平与营养细胞是不同的。     

番茄子叶细胞内三磷酸腺苷酶活性的超微结构定位及其在冷害中的变化

采用磷酸铅沉淀的细胞化学方法,对番茄子叶细胞内三磷酸腺苷酶(ATPase)活性进行了超微结构的定位,并研究了番茄幼苗在遭受冷害过程中 ATPase 活性的变化。结果指出:1.在28℃下萌发生长的番茄幼苗子叶细胞内的 ATPase 活性被定位于质膜、胞间连丝、核仁及核的染色质、叶绿体片层膜、部分细胞壁以及细胞间隙周围的细胞壁表面及其内含物上。2.当番茄幼苗遭受12小时冷(5℃)处理时,质膜、细胞壁及细胞间隙内的 ATPase 活性开始明显地降低,但细胞核和叶绿体片层膜上的 ATPase 仍保持高的活性反应。在冷处理24小时后,质膜与细胞壁的 ATPase 活性几乎完全丧失,而细胞核和叶绿体片层膜的 ATPase 活性仅开始减弱。这种情况揭示,冷害可能首先损伤细胞表面(质膜与壁)的 ATPase 活性。3.讨论了细胞间隙作为养料运输通道的作用以及冷害的一种可能过程与机理。关于高等植物细胞内三磷酸腺苷酶(ATPase)活性的细胞化学的超微结构定位,以往主要集中于维管束的韧皮部和根尖细胞的研究。不久前,我们报道了冬小麦分蘖节细胞内 ATPase 活性的细胞化学定位叫,初步揭示 ATPase 的活性变化与植物抗寒性有密切关系。番茄等喜温植物在冷害中的细胞超微结构,呼吸作用和一些酶(如过氧化物酶,过氧化氢酶及吲(口朶)乙酸氧化酶)活性的变化,已有一些报道,提出膜可能是冷害损伤的最初部位。然而冷害究竟首先是损伤膜的拟脂成分,还是损伤膜的蛋白质成分,或者是二者同时遭到破坏,目前的实验证据还十分缺乏。ATPase 是膜束缚的一种功能性蛋白质,我们试图通过探索它在寒害中的活性变化,为阐明寒害机理提供实验依据。     

葡萄休眠解除过程中冬芽组织活性氧与抗氧化系统的变化特征

以酿酒葡萄‘赤霞珠’(红)和‘霞多丽’(白)为试材,通过考察其自然休眠过程和打破休眠(单氰胺处理)过程中冬芽组织活性氧及抗氧化系统的变化,探讨葡萄休眠机制。结果表明:(1)在陕西杨陵地区,早熟品种‘霞多丽’在12月20日左右进入深度休眠,第2年1月29日进入休眠解除阶段;晚熟品种‘赤霞珠’在1月9日左右达到深度休眠,2月18日左右进入休眠解除阶段;单氰胺处理可促进葡萄休眠的解除。(2)葡萄休眠过程中,活性氧O2.-和H2O2含量在休眠初期逐渐增加,深度休眠时含量最高,休眠解除过程中含量降低,从而促进休眠的解除;超氧化物歧化酶(SOD)活性在休眠中一直降低,休眠解除后活性上升;过氧化物酶(POD)活性在休眠前期较低,随后活性上升,休眠解除过程中活性又降低;过氧化氢酶(CAT)活性在休眠过程中持续上升,随后维持在较高水平;抗坏血酸-还原态的谷胱甘肽(ASA-GSH)循环在休眠前期较弱,休眠解除过程中逐渐增强。研究发现,葡萄进入休眠后,其冬芽抗氧化能力逐渐降低,至深度休眠时抗氧化能力降至最低,随着低温积累需冷量得到满足,活化了抗氧化系统进而抗氧化能力迅速提高,休眠被解除。     

共聚焦荧光镜检术揭示大蒜鳞片细胞间期核中的F肌动蛋白网络

采用免疫荧光和荧光分子探针技术与共聚焦激光扫描显微镜观察相结合,对大蒜（Ａｌｌｉｕｍ ｓａｔｉｖｕｍ Ｌ．）鳞片细胞间期核中是否存在Ｆ肌动蛋白进行了研究。结果表明,以兔抗肌动蛋折抗体为一抗、ＦＴＴＧ－羊抗兔ＩｇＧ抗体为二抗进行免疫荧光标记实验,在荧光镜下观察到蒜瓣薄壁组织的细胞核及表皮细胞核均发出明亮的黄绿色荧光经共聚焦激光扫描显微镜进一步检查,整个细胞核呈黄绿色荧光,说明其中含有肌动蛋白。经ＴＲ     

肽类生长因子对游离细胞核中拓扑异构酶活性的影响

将表皮生长因子及神经生长因子分别作用于分离所得的鼠胚成纤维细胞及其转化细胞的细胞核。结果表明表皮生长因子可以提高游离细胞核中ＤＮＡ拓扑异构酶的活性,但神经生长因子无此作用。     

肽类生长因子对游离细胞核中拓扑异构酶活性的影响

将表皮生长因子及神经生长因子分别作用于分离所得的鼠胚成纤维细胞及其转化细胞的细胞核。结果表明表皮生长因子可以提高游离细胞核中ＤＮＡ拓扑异构酶的活性,但神经生长因子无此作用。     

两种结缕草种子休眠及萌发特性

通过测定兰引Ⅲ号结缕草和青岛结缕草休眠种子和解除休眠种子的吸水率、呼吸强度和脱氢酶活性等萌发生理指标,探讨了结缕草种子的休眠类型。试验结果表明,解除休眠的结缕草种子的吸水率大于未处理的种子。解除休眠种子的呼吸强度、脱氢酶活性都有较大幅度的增长,显著高于未处理。结缕草种子萌发期需30～35℃高温和充足光照。两种结缕草种子的颖壳、种皮的透性障碍及种子内存在发芽抑制物质是导致种子休眠的主要原因,属于混合休眠类型。     

Evidence that the C-terminus of OprM is involved in the assembly of the VceAB-OprM efflux pump

Although the architecture of tripartite multiple drug resistance (MDR) efflux pumps of Gram-negative bacteria has been well characterized, the means by which the components recognize each other and assemble into a functional pump remains obscure. In this study we present evidence that the C-terminal domain of the Pseudomonas aeruginosa OprM and the α-helical hairpin domain of Vibrio cholerae VceA play an important role in the recognition/specificity/recruitment step in the assembly of a functional, VceAB-OprM chimeric efflux pump. To our knowledge, this is the first evidence directly linking the C-terminal domain of an outer membrane efflux protein to its recruitment during the assembly of a tripartite efflux pump.     

Studies on the energy coupling sites of photophosphorylation IV. The relation of proton fluxes to the electron transport and ATP formation associated with Photosystem II

1. By using dibromothymoquinone as the electron acceptor, it is possible to isolate functionally that segment of the chloroplast electron transport chain which includes only Photosystem II and only one of the two energy conservation sites coupled to the complete chain (Coupling Site II, observed P/e₂ = 0.3–0.4). A light-dependent, reversible proton translocation reaction is associated with the electron transport pathway: H₂O → Photosystem II → dibromothymoquinone. We have studied the characteristics of this proton uptake reaction and its relationship to the electron transport and ATP formation associated with Coupling Site II.

2. The initial phase of H⁺ uptake, analyzed by a flash-yield technique, exhibits linear kinetics (0–3 s) with no sign of transient phenomena such as the very rapid initial uptake (“pH gush”) encountered in the overall Hill reaction with methylviologen. Thus the initial rate of H⁺ uptake obtained by the flash-yield method is in good agreement with the initial rate estimated from a pH change tracing obtained under continuous illumination.

3. Dibromothymoquinone reduction, observed as O₂ evolution by a similar flash-yield technique, is also linear for at least the first 5 s, the rate of O₂ evolution agreeing well with the steady-state rate observed under continuous illumination.

4. Such measurements of the initial rates of O₂ evolution and H⁺ uptake yield an H⁺/e⁻ ratio close to 0.5 for the Photosystem II partial reaction regardless of pH from 6 to 8. (Parallel experiments for the methylviologen Hill reaction yield an H⁺/e⁻ ratio of 1.7 at pH 7.6.)

5. When dibromothymoquinone is being reduced, concurrent phosphorylation (or arsenylation) markedly lowers the extent of H⁺ uptake (by 40–60%). These data, unlike earlier data obtained using the overall Hill reaction, lend themselves to an unequivocal interpretation since phosphorylation does not alter the rate of electron transport in the Photosystem II partial reaction. ADP, P_i and hexokinase, when added individually, have no effect on proton uptake in this system.

6. The involvement of a proton uptake reaction with an H⁺/e⁻ ratio of 0.5 in the Photosystem II partial reaction H₂O → Photosystem II → dibromothymoquinone strongly suggests that at least 50% of the protons produced by the oxidation of water are released to the inside of the thylakoid, thereby leading to an internal acidification. It is pointed out that the observed efficiencies for ATP formation (P/e₂) and proton uptake (H⁺/e⁻) associated with Coupling Site II can be most easily explained by the chemiosmotic hypothesis of energy coupling.     

心脑血管疾病大额住院消费统计分析

通过对医院2004-2006年心脑血管疾病大额住院消费(消费大于50000元,以下简称大额消费)病例发病率高的前五种疾病的构成情况、药费、材料费消耗情况进行分析,认为加强大额病例中发病率高的病种的重点管理,是降低医疗费用的有效途径。建议制定常见病大额病种预定额付费方案和审查报销制度;采用适宜技术;控制药费,防止过度医疗,有效地遏制医疗费用的过快增长。     

Strategy for Stabilizing Enzymes Part Two: Increasing Enzyme Stability by Selective Chemical Modification

The molecular mechanisms of change in the thermal stability of proteins modified with low molecular weight reagents are discussed. The choice of stabilization mechanisms to be used as a general strategy for increasing enzyme stability by chemical modification is addressed. Hydrophilization of nonpolar surface areas is the most simple and reliable approach to artificial stabilization of enzymes for use in applied biochemistry and biotechnology.     

Partial purification and properties of Galleria mellonella larvae proteolytic inhibitors acting on Metarhizium anisopliae toxic protease

Gel permeation, preparative isoelectric focusing, and affinity chromatography were used to purify three inhibitors of proteolytic activity from perchloric acid extracts of last instar Galleria mellonella larvae. Electrofocusing experiments revealed three isoinhibitors with different isoelectric points: inhibitor I-1 with p1 of pH 5.6, inhibitor I-2, pH 7.7, and inhibitor I-3 (of small inhibitory activity), pH 8.6. By affinity chromatography on trypsin-Sepharose 4B the I-1 was purified 9.7 ×, but 71.1% of inhibitory activity was lost. Molecular mass of the inhibitory complex was 12,600 Da. I-1 and I-2 are relatively stable to heat at several pHs with minor stability at pH 10. I-1 and I-2 inhibit serine proteases about 2.5 times as much as sulfhydryl proteases. In the same ratio protease P-1 and protease P-2 from Metarhizium anisopliae are inhibited.     

THE DEATH OF BIOETHICS (AS WE ONCE KNEW IT)

Fast forward 50 years into the future. A look back at what occurred in the field of bioethics since 2010 reveals that a conference in 2050 commemorated the death of bioethics. In a steady progression over the years, the field became increasingly fragmented and bureaucratized. Disagreement and dissension were rife, and this once flourishing, multidisciplinary field began to splinter in multiple ways. Prominent journals folded, one by one, and were replaced with specialized publications dealing with genethics, reproethics, nanoethics, and necroethics. Mainstream bioethics organizations also collapsed, giving way to new associations along disciplinary and sub‐disciplinary lines. Physicians established their own journals, and specialty groups broke away from more general associations of medical ethics. Lawyers also split into three separate factions, and philosophers rejected all but the most rigorous, analytic articles into their newly established journal. Matters finally came to a head with global warming, the world‐wide spread of malaria and dengue, and the cost of medical treatments out of reach for almost everyone. The result was the need to develop plans for strict rationing of medical care. At the same time, recognition emerged of the importance of the right to health and the need for global justice in health. By 2060, a spark of hope was ignited, opening the door to the resuscitation of bioethics and involvement of the global community.     

Survival and metabolism of the harpacticoid copepod Thompsonula hyaenae (Thompson) fed on different diatoms

Survival times and oxygen consumption rates have been determined for a benthic harpacticoid copepod, Thompsonula hyaenae (Thompson), when fed different algal diets. Nauplii and adults lived slightly longer on a diet of Navicula sp. than did those fed N. pelliculosa or a mixture of both naviculoid species. Mean numbers of harpacticoids hatched were significantly higher in cultures of N. pelliculosa. Metabolic rates of non-gravid females fed for one week on N. sp. were significantly lower than those fed N. pelliculosa or the mixture. There was no significant difference in oxygen uptake between animals fed N. pelliculosa and those fed the mixed culture. The smaller size and lower food energy content of N. pelliculosa are reflected in the higher respiratory rates of animals led this diatom species.Based on a thesis submitted in partial fulfillment of the M.S. degree in Marine Science at the University of South Carolina. Belle W. Baruch Institute for Marine Biology and Coastal Research Contribution No. 114. Research supported by the Oceanography Section, National Science Foundation, NSF Grant DES72-01573 A01.     

贵州疣螈繁殖生态的研究

贵州疣螈（Tylototritonkweichowensis）是一年繁殖一次的有尾两栖动物。繁殖期肥满度、肝脏系数、脂肪系数、性腺成熟系数、性腺体积均具一定的生物学意义。繁殖期一般为5月上旬至7月上旬,窝卵数平均121．5±7．81枚,孵化期21．6天,孵化率44．33％。每窝印数与雌体头体长成正相关。幼体不同日龄的形态特征变化明显。其全长的Logistic生长方程为：     

用离散量的方法识别蛋白质的超二级结构

用离散量的方法,对2208个分辨率在2.5I以上的高精度的蛋白质结构中四类超二级结构进行了识别。从蛋白质一级序列出发,以氨基酸(20种氨基酸加一个空位)和其紧邻关联共同为参数,当序列模式固定长取8个氨基酸残基时,对“822”序列模式3交叉检验的平均预测精度达到78.1%,jack-knife检验的平均预测精度达到76.7%;当序列模式固定长取10个氨基酸残基时,对“1041”序列模式3交叉检验的平均预测精度达到83.1%,jack-knife检验的平均预测精度达到79.8%。