动物细胞在鼓泡式生物反应器中的死亡速率

通过实验测定,证明生物反应器中细胞死亡速率与气体鼓泡速率成正比而与反应器体积成反比。实验发现气泡大小对细胞死亡速率具有两种作用,一种作用在于影响气泡表面积生成速率;另一种作用则在于影响细胞在气泡表面的吸附程度,其最佳直径为5mm左右。血清和Pluronic F68能显著降低细胞死亡速率,当Pluronic F68浓度达到0．1％时,kd趋于零。所有这些实验结果均与前文提出的生物反应器设计模型具有很好的一致性。     

培养大鼠颈上神经节单烟碱受体通道及突触电流的膜片钳研究

在培养１─２周的大鼠颈上神经节交感神经元标本上,用膜片钳技术记录了单烟碱受体通道电流及胆碱能突触电流,并分析了它们之间的关系。单烟碱受体通道至少有三种亚导状态,即１５ｐＳ,２７ｐＳ,３８ｐＳ,其中以２７ｐＳ最常见。通道有两种开放模式,即单个短促开放与长串开放。对应的平均开放时间分别为τ＿１＝１．７１ｍｓ,τ＿２＝１２．２４ｍｓ。对自发突触电流的分析表明,其下降相的衰减时间常数（τ＝１５．７±１ｍｓ）与上述长串开放的持续时间相当,提示在突触传递过程中,突触前末梢释放的ＡＣｈ引起了突触后神经元烟碱受体通道的长串开放。     

硒对培养人胚肝细胞Ⅲ型前胶原,羟脯氨酸合成的影响

原代培养人胚肝细胞经１．１５６×１０￣(－７）ｍｏｌ／Ｌ硒预处理４ｈ,加入２０ｍｍｏｌ／Ｌ四氟化碳作用２０ｈ,观察硒对其Ⅲ型前胶原（ＰＣⅢ）和羟脯氨酸（Ｈｙｐ）生成的影响。结果培养液中ＰＣⅢ水平、细胞内Ｈｙｐ含量及细胞内外丙二醛（ＭＤＡ）水平均降低,与未加硒对照组比较差别有显著性（Ｐ＜０．０１）。而硒谷腕甘肽过氧化物酶（Ｓｅ－ＧＳＨ－ＰＸ）活性则较对照组显著增高（Ｐ＜０．００１）,且ＰＣⅢ水平与Ｓｅ－ＧＳＨ－Ｐ＿Ｘ／ＭＤＡ比值呈负相关（ｒ＝－０．９１５６,Ｐ＜０．０１）。提示硒可提高Ｓｅ－ＧＳＨ－Ｐ＿Ｘ／ＭＤＡ比值,抑制脂质过氧化激发的肝细胞胶原合成。     

SH－SY5Y细胞胞内钙库特性研究

运用单细胞显微荧光测量技术测量了单个ＳＨ—ＳＹ５Ｙ细胞内游离钙离子浓度的变化。首次报道了ＳＨ—ＳＹ５Ｙ细胞内存在毒蕈碱敏感而非咖啡因敏感的钙库,并研究了它的动力学特征。Ｎ￣￣Ｃ￣ｈｅｔｗＭａｄＵｇｈ＊ＴＯｗｈｏｍＣｂ￣ｐｏｎｄｅｎｅｅｓｈｏｕｌｄｂｅ￣．     

链脲佐菌素诱导糖尿病大鼠胰腺外分泌部A、B细胞密度的变化

本文应用A蛋白金银—过氧化物酶抗过氧化物酶(PAGS-PAP)双重染色法,观察了链脲佐菌素(streptozotocin,STZ)诱导的糖尿病大鼠胰腺外分泌部含高血糖素的单个A细胞(单A细胞)及合胰岛素的单个B细胞(单B细胞)密度的变化.在一次大剂量腹腔注射STZ后第5天和第10天,大鼠胰腺外分泌部单A细胞密度较对照组大鼠增加,而单B细胞密度在注射STZ后第5天较对照组大鼠减少,但在第15天与对照组大鼠接近.在第15天,一些单B细胞分布在靠近胰岛的腺泡中,岛周腺泡含单B细胞的胰岛百分率明显高于对照组.由于胰腺外分泌部的单A、单B细胞在分布特征上与中间细胞相似,在糖尿病时其数量变化也与中间细胞一致,因此,本研究所观察到的单A、单B细胞与前人报道的中间细胞有密切关系.上述单A、单B细胞密度的变化提示,在STZ诱导的糖尿病大鼠,胰腺中的B细胞被STZ破坏后,其外分泌部可能有某些细胞通过中间细胞向单A、单B细胞发生了转化或者单A、单B细胞即此转化过程中的中间细胞.     

植物的水容特征与其耐旱性的关系

在自然风晾条件下,研究了不同植物器官的相对含水量、水势及比水容之间的相互关系。结果表明：植物叶片阻止体内蒸腾失水的能力大小顺序依次为：花生（Arrachishypogaea）＞甘薯（Ipomoeabatatas）＞大豆（Glycinemax）＞玉米（Zeamays）,各植物茎的保水能力相差不大;甘薯的茎、叶在风晾4h后仍未永久凋萎,其他植物的茎、叶在风晾1～3h就出现永久凋萎;花生、甘薯、大豆和玉米叶片风晚3～4h后,其水势的下降幅度分别为：1．00,1．30,1．80和2．70mPa,花生、甘薯、大豆茎的水势下降幅度分别为：1．95,1.40和1．30mPa;植物茎、叶的水势与其相对含水量具有较好的对数关系;植株茎、叶的比水客值范围在0．0258～0．6835mPa-1之间,叶片的比水容大于茎的比水容。因此,植物的水容特征表明不同植物茎、叶的保水、释水能力不同,因而其耐旱、抗旱性不同。玉米和大豆的耐旱性小于花生、甘薯的耐旱性。     

In vitro peptidergic neurons from the adult locust pars intercerebralis: Morphological and immunocytological studies

Primary cell cultures were prepared from a major neurosecretory center of the adult locust brain, the pars intercerebralis, in order to characterize neurosecretory cells growingin vitro. Individual pars intercerebralis could be removed free of surrounding tissue and dissociated by mechanical treatment. Mature neurosecretory neurons of different sizes regenerate new neurites during the initial three daysin vitro in serum-free medium. They show a tendency to sprout one primary neurite from which fine processes develop. By means of electron microscopy, we observed the integrity of the cellular organelles, indicating that cultured neurons are healthy, and we were able to distinguish three types of neurosecretory neurons on the basis of the ultrastructural aspects of the neurosecretory material. These three types have the same ultrastructural characteristics asin situ neuroparsin, ovary maturing parsin and locust insulin related peptide neurons. Immunogold labelling at the electron microscopic level, using the two available specific antibodies, anti-neuroparsin and anti-ovary maturing parsin, confirms the morphological characterization of neuroparsin and ovary maturing parsin cells. These results show for the first time that cultured locust neurosecretory neurons behave like thosein vivo, in terms of their ultrastructure and immunocytochemistry. Moreover, the presence of recently-formed neurosecretory material both in the Golgi zone of the perikaryon and in the neuronal processes indicates that cultured neurons have functional capacity since they are able to synthesizede novo and to transport the neurosecretory material along the neurite. Thus our well-characterized culture system provides a suitable invitro model to investigate the secretory mechanism of locust neurosecretory neurons.     

Aplysia hemolymph promotes neurite outgrowth and synaptogenesis of identifiedHelix neurons in cell culture

Hemolymph of adultAplysia californica significantly affects neurite outgrowth of identified neurons of the land snailHelix pomatia. The metacerebral giant cell (MGC) and the motoneuron C3 from the cerebral ganglion and the neuron B2 from the buccal ganglion ofH. pomatia were isolated by enzymatic and mechanical dissociation and plated onto poly-l-lysine-coated dishes either containing culture medium conditioned byHelix ganglia, or pre-treated withAplysia hemolymph. To determine the extent of neuronal growth we measured the neurite elongation and the neuritic field of cultured neurons at different time points.Aplysia hemolymph enhances the extent and rate of linear outgrowth and the branching domain ofHelix neurons. With the hemolymph treatment the MGC neuron more consistently forms specific chemical synapses with its follower cell B2, and these connections are more effective than those established in the presence of the conditioned medium.     

Cellular mechanisms governing synapse formation: lessons from identified neurons in culture

The accessibility of embryonic and adult neurons within invertebrate nervous systems has made them excellent subjects for neurobiological study. The ability to readily identify individual neurons, together with their great capacity for regeneration, has been especially beneficial to investigations of synapse formation and the specificity of neuronal connectivity. Many invertebrate neurons survive for long periods following isolation into primary cell culture. In addition, they readily extend new neuritic arbors and form electrical and chemical connections at sites of contact. Thus, cell culture approaches have allowed neuroscientists greater access to, and resolution of, events underlying neurite outgrowth and synaptogenesis. Studies of identified neuromuscular synapses ofHelisoma have determined a number of signaling mechanisms involved in transsynaptic communication at sites of neuron-target contact. At these sites, both anterograde and retrograde signals regulate the transformation of growth cones into functional presynaptic terminals. We have found that specific muscle targets induce both global and local changes in neurotransmitter secretion and intracellular calcium handling. Here we review recent studies of culturedHelisoma synapses and discuss the mechanisms thought to govern chemical synapse formation in these identified neurons and those of other invertebrate species.     

Isolation and propagation of yolk-sac-derived endothelial cells from a hypervascular transgenic mouse expressing a gain-of-functionFPS/FES proto-oncogene

Summary We report on the isolation and propagation of endothelial cells from the mouse embryonic yolk sac, the earliest site of blood vessel development, and on the advantages of a hypervascular transgenic mouse source of these cells. These transgenic mice express multiple copies of an activated allele of the humanfps/fes proto-oncogene and display hypervascularity progressing to multifocal hemangiomas. This phenotype suggested a role of thefps/fes proto-oncogene in vasculogenesis and angiogenesis and led us to investigate the growth characteristics of yolk-sac-derived endothelial cells from transgenicfps/fes embryos. We have established eight independent cell clones from a mixture of transgenic and control yolk sacs from Day 12 embryos. Southern blot hybridization analysis showed all eight clones to be derived from transgenic cells suggesting a growth advantage of cells carrying the activatedfps/fes gene. A cell line, Clone 166 (C166), established from one of these clones, was more fully characterized. C166 exhibits normal endothelial characteristics, such as rearrangement into tubelike structures when placed on Matrigel, expression of angiotensin converting enzyme, retention of cobblestone morphology at confluence, and the presence of cell surface receptors for acetylated low density lipoprotein. The cells constitutively express murine endothelial cell adhesion molecule VCAM-1 and the vascular addressin identified by antibody MECA-99. As expected, the cell line expresses high levels of the cytoplasmic protein-tyrosine kinase encoded by thefps/fes proto-oncogene. The clone we have described as well as other endothelial cell lines that we have established from the mouse embryonic yolk sac should prove useful for the study of endothelial cell differentiation and for the determination of the mechanisms underlying the establishment of organ-specific endothelial cell heterogeneity.