苹果果实韧皮部及其周围薄壁细胞的超微结构观察和功能分析

利用透射电镜技术,对发育过程中的苹果（Ｍａｌｕｓ ｄｏｍｅｓｔｉｃａ Ｂｏｒｋｈ）果实韧皮部及其周围薄壁细胞的超微结构进行了观察研究。结果表明,在主脉和细脉的筛分子（ＳＥ）和伴胞（ＣＣ）之间存在胞间连丝,胞间连丝在筛分子一侧是单通道,在伴胞一侧呈多分枝通道。在细脉中筛分子小,伴胞大,在主脉中则是筛分子大,伴胞小。伴胞内胞质和核质稠密,富含线粒体、内质网和高尔基体,液泡内往往呈现多膜包被的囊泡结构,     

生物波反跳现象的实验观察

生物波实验中采用奇异变形杆菌建立双机制波动模型的研究［１］中观察到红环、黄环的交替出现的宏观有序结构,红环上的细菌呈断裂生长,繁殖旺盛,细菌堆积较多,黄环部分细菌是呈纤细状形态的潜生体（ＣｒｙｐｔｉｃＧｒｏｗｔｈＣｅｌ,ＣＧＣ）。从形成过程观察,ＣＧ...     

小麦胚乳细胞中肌动蛋白纤丝分布格局的荧光显微观察

以异硫氰四甲基罗丹明－鬼笔环肽为探针,结合电视显微镜术对呈现原生质胞间运动的小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ Ｌ．）胚乳细胞胞质中肌动蛋白纤丝（ＡＦｓ）的存在与分布格局进行了观察与分析。结果表明,ＡＦｓ以多种形式在胚乳细胞内呈区域性分布：胞核为ＡＦｓ网络所包围,ＡＦｓ成束由核周向四处辐射直抵周质层,大量纤细ＡＦｓ在胞质皮层内呈无序的密集分布以及腹沟区细胞内ＡＦｓ梭状体的大量汇集。联系胞质组分在胞间运动中的动态与胞质纤索对ＣＢ处理的反应,讨论了ＡＦｓ的不同存在状态与胞质纤索的伸缩穿越和细胞基质的集流迁移这两种胞间运动方式的关系     

细胞转化过程中胞内钙离子浓度的变化

使用钙离子荧光探针Ｆｌｕｏ－３ＡＭ和ＤＮＡ荧光染料Ｈｏｅｃｈｓｔ３３３４２联染细胞的方法,利用显微分光光度计ＭＰＶⅡ测量了两种温度敏感细胞—６Ｍ２和ｔｓＲＳＶＮＩＨ３Ｔ３－ＬＡ９０细胞及Ｃ３Ｈ１０Ｔ１／２和转化Ｃ３Ｈ１０Ｔ１／２细胞在不同细胞周期时相内钙的浓度,发现从Ｇ１期到Ｓ期到Ｇ２期,６ｍ２细胞当在３３℃培养时（转化状态）胞内钙的浓度〔Ｃａ＾２＋〕ｉ分别为８５．０,１３８．４２３９．０ｎｍｏｌ     

大鼠运动性肥大心脏心肌血管内皮生长因子及其基因表达的研究

目的和方法：血管内皮生长因子（ｖａｓｃｕｌａｒｅｎｄｏｔｈｅｌｉａｌｇｒｏｗｔｈｆａｃｔｏｒ,ＶＥＧＦ）是新近确定的一种特异作用于血管内皮细胞的活性肽。最近发现正常心肌细胞可表达ＶＥＧＦ,高血压肥大心脏心肌ＶＥＧＦ及基因表达增强,但对运动性心肌肥大时的变化尚不清楚。本实验采用免疫组化和分子杂交方法,对游泳运动１０周大鼠稳定期肥大心脏心肌ＶＥＧＦ及其基因表达进行研究。结果：ＷｉｓｔａｒＫｙｏｔｏ（ＷＫＹ）大鼠、自发性高血压大鼠（ｓｐｏｎｔａｎｅｏｕｓｌｙｈｙｐｅｒｔｅｎｓｉｖｅｒａｔｓ,ＳＨＲ）和运动大鼠心肌细胞浆内均有特异性ＶＥＧＦ染色颗粒,但运动大鼠心肌细胞胞浆内染色颗粒增加最明显。Ｎｏｒｔｈｅｒｎ分子杂交结果表明三组大鼠心肌均有ＶＥＧＦｍＲＮＡ表达,其中ＳＨＲ表达最强,运动大鼠比ＷＫＹ大鼠增强,但低于ＳＨＲ。结论：目前对这一结果的生理意义还不清楚,推测可能与心肌肥大时细胞间质血管增生有关。     

培养的海马神经元致痫后谷氨酸的合成和释放的变化

通过谷氨酸（Ｇｌｕｔａｍａｔｅ,Ｇｌｕ）免疫细胞化学染色法观察到马桑内酯（ＣｏｒｉａｒｉａＬａｃｔｏｎｅ,ＣＬ）（２．５×１０－５ｍｏｌ／Ｌ）作用于体外培养的海马神经元６ｈ呈色增强,此后呈色反应明显减弱,阳性细胞数减少,胞体变小,突起短而稀少。ＭＫ－８０１（４×１０－５ｍｏｌ／Ｌ）可降低ＣＬ引起的海马神经元Ｇｌｕ免疫反应性。高效液相色谱法（ＨＰＬＣ）测定ＣＬ作用于培养的海马神经元２４ｈ后培养基中Ｇｌｕ和天门冬氨酸（Ａｓｐ）含量增加（Ｐ＜０．００１）,ＭＫ－８０１并不能阻断此种效应。结果提示ＣＬ致痫后,早期神经元内Ｇｌｕ合成增加,后期向胞外释放。     

蛋白激酶C对N－乙酰氨基葡萄糖转移酶Ⅲ的调节

人肝癌细胞株７７２１细胞的Ｎ－乙酰氨基葡萄糖转移酶Ⅲ（ＧｎＴⅢ）活性受Ｓｅｒ／Ｔｈｒ蛋白激酶的两种抑制剂ｑｕｅｒｃｅｔｉｎ和三氟吡嗪（ＴＦＰ）．蛋白激酶Ｃ（ＰＫＣ）的两种特异性抑制剂Ｄ－鞘氨醇和ｓｔａｕｒｏｓｐｏｒｉｎｅ的抑制。用ＰＭＡ处理细胞舌,ＧｎＴⅢ活力随膜性ＰＫＣ（ｍ－ＰＫＣ）活力而平行变化,但与胞液ＰＫＣ活力的变化无关。Ｑｕｅｒｃｅｔｉｎ、Ｄ－鞘氨醇和ｓｔａｕｒｏｓｐｏｒｉｎｅ还能够阻断ＰＭＡ对ＧｎＴⅢ的激活。Ｑｕｅｒｃｅｔｉｎ、ｓｔａｕｒｏｓｐｏｒｉｎｅ对ｍ－ＰＫＣ和ＧｎＴⅢ的抑制作用基本上与它们的应用浓度成正比关系。当人及大鼠肾脏的粗ＧｎＴ制剂分别用碱性磷酸酶切除磷酸基后,ＧＤＴⅢ的活力明显下降。这些结果表明ｍ－ＰＫＣ可能通过蛋白质的Ｓｅｒ／Ｔｈｒ残基上磷酸化和去磷酸化作用直接或间接地调节ＧｎＴⅢ。     

GM3对重建Gs与AC偶联功能的影响

将神经节苷脂ＧＭ３（Ｍｏｎｏｓｉａｌｏｇａｎｇｌｉｏｓｉｄｅ－ＧＭ３）通过保温法掺入到含激活型Ｇ蛋白（ＳｔｉｍｕｌａｔｏｒｙＧＴＰ－ｂｉｎｄｉｎｇｐｒｏｔｅｉｎ,Ｇｓ）与腺苷酸环化酶（ＡｄｅｎｙｌｙｌＣｙｃｌａｓｅ,ＡＣ）的脂酶体中,研究了ＧＭ３对Ｇｓ和ＡＣ偶联功能的影响。实验结果表明,在４－１０μｍｏｌ／Ｌ浓度范围的ＧＭ３增加ＡＣ的基础活力;在高于４μｍｏｌ／Ｌ时,ＧＭ３可显著抑制Ｇｓ激活ＡＣ的能力;而在ＧＭ３浓度高于１００μｍｏｌ／Ｌ的条件下,Ｇｓ结合ＧＴＰγＳ（Ｇｕａｎｏｓｉｎｅ５＇－Ｏ－（３－ｔｈｉｏｔｒｉｐｈｏｓｐｈａｔｅ））的活力受到明显抑制。随外源ＧＭ３浓度的增加,ＧＭ３对Ｇｓ激活ＡＣ的能力与对ＡＣ基础活力的影响似乎并不完全一致。这些结果提示,Ｇｓ与ＡＣ的解偶联对较低浓度的ＧＭ３的影响更加敏感。用荧光探剂ＭＣ５４０标记脂酶体,测量其荧光光谱的结果显示,随着ＧＭ３浓度增加,ＭＣ５４０的荧光强度增强,这说明外源性的ＧＭ３的掺入使膜脂质分子头部的堆积变得更加疏松。这可能提示,ＧＭ３介导的膜脂物理状态的变化是调节Ｇｓ与ＡＣ偶联功能的重要因素之一。     

二酰甘油－蛋白激酶C信使系统在LA90细胞转化中的作用

以ＬＡ９０细胞（ＲＳＶ温度敏感突变株ＬＡ９０转化的小鼠成纤维细胞〕为模型,研究了二酰甘油（ＤＧ）－蛋白激酶Ｃ（ＰＫＣ）信使系统在细胞转化中的作用。通过免疫沉淀法观察到ＬＡ９０细胞在允许温度（３３℃）时具有很高的ｐｐ６０ｖ－ｓｒｃ激酶活性,远高于非允许温度（３９℃）,当从３９℃转至３３℃１０分钟,激酶活性就已显著升高。同时运用３Ｈ－甘油掺入并结合板层析分离方法和酶活性测定,发现ＬＡ９０细胞中ＤＧ含量和ＰＫＣ活性在３３℃条件下高于３９℃,当由３９℃转至３３℃１０分钟,细胞内ＤＧ含量和ＰＫＣ活性均明显增加。我们进一步探讨了ＰＫＣ活性与癌基因ｖ－ｓｅｒ、ｐ５３基因表达的相关性,实验表明,ＰＫＣ的激活剂ＴＰＡ可刺激３９℃条件下的ＬＡ９０细胞中ｖ－ｓｒｅ和ｐ５３基因表达,ＰＫＣ选择性抑制剂Ｈ７可抑制３３℃条件下ＬＡ９０细胞中ｖ－ｅｒｃ和ｐ５３基因表达。看来,ｐｐ６０ｖ－ｓｒｃ可通过刺激磷脂酰肌醇（ＰＩ）代谢激活ＤＧ－ＰＫＣ（ｄｉａｃｙｌｇｌｙｃｅｒｏｌ－ｐｒｏｔｅｉｎｋｉｎａｓｅＣ）信使系统,后者通过某种途径调控ｖ－ｓｒｃ和ｐ５３等癌基因之表达。因此ＤＧ－ＰＫＣ信使系统可能是ｐｐ６０ｖ－ｓｒｃ转化细胞及被转化细胞维持转     

柑桔种间体配融合及培养研究

“平户”文旦（柚）（Ｃｉｔｒｕｓｇｒａｎｄｉｓ）Ｏｓｂｅｃｋ的四分体经酶解,分离出原生质体。ＰＥＧ（聚乙二醇）诱导这类原生质体与二倍体“伏令夏”甜橙（Ｃ．ｓｉｎｅｎｓｉｓ）胚性悬浮细胞系的原生质体融合。融合后的原生质体培养于ＢＨ３／ＥＭＥ培养基中。２天后,观察到花粉管生长现象。不同处理的结果显示,这一现象来源于异核体细胞。这种具花粉管生长的细胞可进一步分裂,形成多细胞团及球形和心形胚状体。对再生的胚状体进行染色体数检查,证明１３．１％的胚状体为三倍体,２ｎ＝３ｘ＝２７。而起始悬浮细胞系为二倍体,检查的３９２个细胞,未发现有染色体倍性变异。     

The Vital Role of Blood Flow-Induced Proliferation and Migration in Capillary Network Formation in a Multiscale Model of Angiogenesis

Sprouting angiogenesis and capillary network formation are tissue scale phenomena. There are also sub-scale phenomena involved in angiogenesis including at the cellular and intracellular (molecular) scales. In this work, a multiscale model of angiogenesis spanning intracellular, cellular, and tissue scales is developed in detail. The key events that are considered at the tissue scale are formation of closed flow path (that is called loop in this article) and blood flow initiation in the loop. At the cellular scale, growth, migration, and anastomosis of endothelial cells (ECs) are important. At the intracellular scale, cell phenotype determination as well as alteration due to blood flow is included, having pivotal roles in the model. The main feature of the model is to obtain the physical behavior of a closed loop at the tissue scale, relying on the events at the cellular and intracellular scales, and not by imposing physical behavior upon it. Results show that, when blood flow is considered in the loop, the anastomosed sprouts stabilize and elongate. By contrast, when the loop is modeled without consideration of blood flow, the loop collapses. The results obtained in this work show that proper determination of EC phenotype is the key for its survival.     

Effect of fixation temperature on flow cytometric measurement of intracellular antibody content of hybridomas during batch culture

In order to investigate the effect of fixation temperature on flow cytometric measurement of intracellular antibody content of hybridoma cells, cells in different growth stages during a batch culture were fixed and stored at 4 and -20 °C, respectively. Flow cytometric analysis indicates that both fixation temperatures can be used in monitoring the changes in intracellular antibody content of the cells during a batch culture. However, it is better to fix and store the cells at -20 °C than 4 °C with regard to preservation of intracellular antibody and storage stability.     

Small-scale fluid motion mediates growth and nutrient uptake of Selenastrum capricornutum

1. A fluid‐flow reactor using submersible speakers was constructed to generate small‐scale fluid motion similar to conditions measured in open water environments; flow was quantified by particle image velocimetry. Additionally a Couette‐type rotating cylinder was used to generate shear flows; flow was quantified using an optical hotwire probe and torque measurements. Growth rates of the green alga Selenastrum capricornutum were determined from changes in cell counts and viability was tested using the fluorogenic probe fluoresceine diacetate. 2. Evidence that fluid motion directly affects growth rates was obtained as a significant difference between growth in a moving versus non‐moving fluid. A near 2‐fold increase in growth rate was achieved for an energy dissipation rate of ? = 10^?7 m² s^?3; a rate common in lakes and oceans. The onset of the viability equilibrium, identified as the day of the test period when the number of active cells equalled non‐active cells, was delayed by 2 days for moving fluid conditions as compared with a non‐moving fluid. 3. Nutrient uptake was determined by a decrease in the bulk fluid concentration and cellular phosphorus concentration was also estimated. The thickness of the diffusive sublayer surrounding a cell, a zone dominated by molecular diffusion, was estimated. Increasing fluid motion was found to decrease the thickness of this layer. The Sherwood number (ratio of total mass flux to molecular mass flux) showed that advective flux surrounding cells dominated molecular diffusion flux with regard to Péclet numbers (ratio of advective transport to molecular diffusion transport). Fluid motion facilitated uptake rates and resulted in increased growth rates, compared with no‐flow conditions. The rate‐of‐rotation and the rate‐of‐strain in a moving fluid equally mediated the diffusive sublayer thickness surrounding the cells. Our study demonstrates that small‐scale fluid motion mediates algal growth kinetics and therefore should be included in predictive models for algal blooms.     

Crystallographic analysis of the thermal motion of the inclusion complex of cyclomaltoheptaose (beta-cyclodextrin) with hexamethylenetetramine

The crystal structure of the inclusion complex of cyclomaltoheptaose (beta-cyclodextrin) with hexamethylenetetramine was determined at temperatures of 123, 173, 223, and 293 K. The rigid-body motion of the host and guest molecules was evaluated by means of the TLS method that represents the molecular motion in terms of translation, libration, and screw motion. In increasing the temperature from 123 to 293 K, the amplitude of the rigid body vibration of the host molecule was increased from 1.0 to 1.3 degrees in the rotational motion and from 0.16 to 0.17 A in the translational motion. The cyclomaltoheptaose molecule has the flexibility in seven alpha-(1-->4)-linkages, and each glucose unit was in the rotational vibration around an axis through two glycosidic oxygen atoms. As a result, the rigid-body parameters of cyclomaltoheptaose were considered to be overestimated because of including the contribution from the local motion of glucose units. In contrast, for the guest molecule having no structural flexibility, the TLS analysis demonstrated that the atomic thermal vibration was mostly derived from the rigid body motion. The rotational amplitude of hexamethylenetetramine was changed from 5.2 to 6.6 degrees in increasing the temperature from 123 to 293 K, while the change of the translational amplitude was from 0.20 to 0.23 A. The translational motion of the guest molecule was hindered by the inside wall of the host cavity. The molecular motion was characterized by the rotational vibration around the axis through two nitrogen atoms that were involved in the hydrogen-bond formation.     

Quantified small-scale turbulence inhibits the growth of a green alga

1. Laboratory experiments were conducted to elucidate the effect of small-scale turbulent fluid motion on the growth of laboratory cultures of the freshwater algae Scenedesmus quadricauda . Turbulent flow was generated using an oscillating-grid apparatus. The experiments were performed under the range of fluid flow conditions similar to those occurring in nature. The only growth limiting factor was the effect of small-scale fluid motion; all other environmental factors, such as light, temperature and nutrients, were kept constant.
2. Growth of Scenedesmus quadricauda , measured in terms of chlorophyll a concentration, was inhibited when the level of turbulence in the water column was increased. Algal growth was maximum in a quiescent fluid. The inhibitory effect of fluid motion was observed independently of flow regime (laminar, transitional, turbulent) in the water column.
3. Cell destruction and aggregation of dead and living cells of algae were observed in a turbulent flow. High shear rates, estimated from the dissipation of turbulent kinetic energy, caused the cell destruction, algal collision and agglomeration of algae. Data on Scenedesmus responses to small-scale fluid motion will enhance and broaden our ability to develop predictive multispecies models for freshwater phytoplankton communities.     

An AMP nucleosidase gene knockout in Escherichia coli elevates intracellular ATP levels and increases cold tolerance

Disparate psychrophiles (e.g. glacier ice worms, bacteria, algae and fungi) elevate steady-state intracellular ATP levels as temperatures decline, which has been interpreted as a compensatory mechanism to offset reductions in molecular motion and Gibb's free energy of ATP hydrolysis. In this study, we sought to manipulate steady-state ATP levels in the mesophilic bacterium, Escherichia coli, to investigate the relationship between cold temperature survivability and elevated intracellular ATP. Based on known energetic pathways and feedback loops, we targeted the AMP nucleotidase (amn) gene, which is thought to encode the primary AMP degradative enzyme in prokaryotes. By knocking out amn in wild-type E. coli DY330 cells using recombineering methodology, we generated a mutant (AMNk) that elevated intracellular ATP levels by more than 30% across its viable temperature range. As temperature was lowered, the relative ATP disparity between AMNk and DY330 cells increased to approximately 66% at 10 degrees C, and was approximately 100% after storage at 0 degrees C for 5-7 days. AMNk cells stored at 0 degrees C for 7 days displayed approximately fivefold higher cell viability than wild-type DY330 cells treated in the same manner.     

皮肤成纤维细胞永生化的研究进展

正常体细胞的生命周期都是有限的 ,经过一定数目的分裂后 ,会进入增殖抑制状态。永生化细胞是近年来生物科学探索较多的领域之一。因为它不仅能为细胞生物学的研究提供性状稳定的研究对象 ,还为人类实现器官再生开辟了新方向。所以皮肤成纤维细胞的永生化对于皮肤疾病以及皮肤组织工程的研究都具有非常深远的意义。就皮肤成纤维细胞的永生化的研究作一阐述 ,并讨论其应用前景和可能面临的问题     

温度对谷皮菱形藻生长及其理化成分的影响

考察了不同温度对谷皮菱形藻生长及其理化成分的影响。结果表明:温度在10℃或30℃条件下不利于细胞生长,同时也不利于胞内理化成分的积累。在20℃条件下细胞密度、叶绿素含量、胞内蛋白、胞外多糖及胞内多糖达到最大值。谷皮菱形藻的最适生长温度为20℃,10℃可以作为种质保存的温度。     

Starvation survival of Salmonella enteritidis.

Washed cells of Salmonella enteritidis harvested from a defined medium during logarithmic growth were subjected to starvation in pH 7 phosphate buffer at 37 C. Viability was measured by slide cultures and plate counts. The survival of cell suspensions equivalent to 1 to 10 mg (dry wt)/ml was influenced by cryptic growth. The rate of cryptic growth, assessed by plate counts, increased with cell density and could not be alleviated by starvation with dialysis. Dialysis of the starving culture did retard the onset of cryptic growth but did not eliminate it, indicating that the major substrates for regrowth were relatively large cellular components. In phosphate buffer, 6.7 homologous heat-killed cells allowed for the doubling of one S. enteritidis cell. Cryptic growth was not observed when cells were starved on the surface of membrane filters or in suspensions equivalent to 20 mug (dry wt)/ml (105 cells/ml). Similar half-life survival times were calculated for both these populations, but the shape of their survival curves differed significantly. These differences were attributed to stress factors encountered during cell preparation and during starvation. The half-life survival time of S. enteritidis starved at 20 mug (dry wt)/ml was 140 h in phosphate buffer, 82 h in 3,6-endomethylene-1,2,3,-6-tetrahydrophthalic acid buffer, and 77 h in tris(hydroxymethyl)aminomethane buffer.     

Cryptic collagen elements as signaling hubs in the regulation of tumor growth and metastasis

Structural remodeling of the extracellular matrix is a well-established process associated with tumor growth and metastasis. Tumor and stromal cells that compose the tumor mass function cooperatively to promote the malignant phenotype in part by physically interacting with intact and structurally altered matrix proteins. To this end, collagen represents the most abundant component of the extracellular matrix and is known to control the behavior of histologically distinct tumor types as well as a diversity of stromal cells. Although a significant molecular understanding has been established concerning how cellular interactions with intact collagen govern signaling pathways that control tumor progression, considerably less is known concerning how interactions with cryptic or hidden regions within remodeled collagen may selectively alter signaling cascades, or whether inhibition of these cryptic signaling pathways may represent clinically effective therapeutic strategies. Here, we review the emerging evidence concerning the possible mechanisms for the selective generation of cryptic or hidden elements within collagen and their potential cell surface receptors that may facilitate signal transduction. We discuss the concept that cellular communication links between cell surface receptors and these cryptic collagen elements may serve as functional signaling hubs that coordinate multiple signaling pathways operating within both tumor and stromal cells. Finally, we provide examples to help illustrate the possibility that direct targeting of these unique cryptic signaling hubs may lead to the development of more effective therapeutic strategies to control tumor growth and metastasis.