Contents of Volume 53

Plant Molecular Biology -     

Random Amplified Polymorphic DNA Variation among and within Selected Ixora (Rubiaceae) Populations and Mutants

Random amplified polymorphic DNA (RAPD) analysis was used tostudy variation among and within selectedIxora (Rubiaceae) populationsand mutants. Six populations of I. congesta yielded identicalbanding patterns suggesting genetic uniformity of this species.However, six populations of I. coccinea varieties (three red-flowered,two yellow-flowered and one red-flowered wild-type) exhibitedinfraspecific differences in RAPD profiles. Small and largeleaves of an atavistic mutant cultivar of I. coccinea were alsosubjected to RAPD analysis. An extra band was amplified in thelarge leaves that was absent in small leaves, suggesting thatthe phenotypic alteration in this taxon is due to genetic mutationrather than epigenetic changes. Similarly, an extra band wasdetected in the white sectors of I. Variegated compared to thegreen sectors, suggesting that the shoot apical meristems ofthis cultivar exist as a genetic chimera. DNA gel blot hybridizationwas performed to confirm the specificities of selected bands.Our study indicates that differences among individuals of variouspopulations and mutants may be detected using RAPD markers.Copyright 1999 Annals of Botany Company Ixora L., variegated variety, RAPD fingerprinting, DNA gel blot, intraspecific genetic similarity, atavistic mutant.     

The Stress Hormone Corticosterone Increases Synaptic ��-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptors via Serum- and Glucocorticoid-inducible Kinase (SGK) Regulation of the GDI-Rab4 Complex

Corticosterone, the major stress hormone, plays an important role in regulating neuronal functions of the limbic system, although the cellular targets and molecular mechanisms of corticosteroid signaling are largely unknown. Here we show that a short treatment of corticosterone significantly increases α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated synaptic transmission and AMPAR membrane trafficking in pyramidal neurons of prefrontal cortex, a key region involved in cognition and emotion. This enhancing effect of corticosterone is through a mechanism dependent on Rab4, the small GTPase-controlling receptor recycling between early endosome and plasma membrane. Guanosine nucleotide dissociation inhibitor (GDI), which regulates the cycle of Rab proteins between membrane and cytosol, forms an increased complex with Rab4 after corticosterone treatment. Corticosterone also triggers an increased GDI phosphorylation at Ser-213 by the serum- and glucocorticoid-inducible kinase (SGK). Moreover, AMPAR synaptic currents and surface expression and their regulation by corticosterone are altered by mutating Ser-213 on GDI. These results suggest that corticosterone, via SGK phosphorylation of GDI at Ser-213, increases the formation of GDI-Rab4 complex, facilitating the functional cycle of Rab4 and Rab4-mediated recycling of AMPARs to the synaptic membrane. It provides a potential mechanism underlying the role of corticosteroid stress hormone in up-regulating excitatory synaptic efficacy in cortical neurons.     

B7-2胚胎性癌细胞诱导分化过程中的表型转变

胚胎性癌细胞(简称EC细胞)作为一类肿瘤(畸胎瘤)的干细胞近年受到广泛的重视,从胚胎学、肿瘤学和分子生物学等许多学科领域都应用它作为实验材料,离体诱导分化研究是其中的一个方面。B 7-2 EC细胞是我们从129品系小鼠的自发睾丸畸胎瘤中分离克隆得到的一株多能EC细胞,它在同种同基因小鼠     

体外分化的人体巨噬细胞抑制天然杀伤(NK)细胞的研究

本文继先前工作后,进一步应用正常健康人外周血单个核细胞(PBMNC)经塑料培皿粘附技术把单核细胞分离出来,经培养进一步纯化,随后动态观察培养0,2,4,6和8天的单核-巨噬细胞的形态变化和对新鲜分离同种异基因个体PBMNC中NK活性的影响。实验表明,体外分化6天和8天的巨噬细胞质/核比例和胞浆内空泡显著增加,细胞直径约为0天时的2倍。这些细胞和PBMNC之比为0.5:1时,引起了NK细胞活性的50%以上抑制(4小时~(51)Cr标记K 562肿瘤的同位素释放试验)。这种抑制效应不为过氧化氢酶(Catalase 4000单位/毫升)和前列腺素合成酶的抑制剂(Indom 1×10~(-5)M)所阻断。实验证明,同种异基因个体的NK细胞不能识别巨噬细胞表面抗原,从而排除了巨噬细胞和K562肿瘤抗原竞争的可能性。实验还表明,巨噬细胞对NK活性的抑制是不受HLA约束的。应用高频超声振荡破碎巨噬细胞膜方法和免疫调变技术进一步提示,人体巨噬细胞对NK活性的抑制与巨噬细胞体积无关,而与体外分化所赋有的固有特性和它们分泌的免疫调节分子有关。     

大鼠非致瘤四倍体细胞系的建立及细胞遗传学和酶学特征

从大鼠自然诱发的肉瘤细胞中,我们建立了一个四倍体细胞系(4n=84),命名为RC(ratcell)。它具有典型的成纤维细胞外形,能在玻璃表面贴壁生长,但不能生长在琼脂半固体培养基中。该细胞在含15％小牛血清的RPMI 1640培养基中生长良好,至今已连续繁殖112世代,细胞群体倍增时间约为15小时。染色体G-带分析表明,RC为整四倍体细胞,它的1条X染色体在第32至34区为均染区。RC细胞核仁组织者(NORs)活性显然比大鼠二倍体细胞NORs活性的加倍还高(P<0.001)。这个具有非常高NORs活性的RC细胞系对于研究细胞18S+28S rRNA基因转录活性的调控、基因表达与基因剂量关系有一定的意义。RC细胞还有异常高的磷酸酯酶活性,而且它的同工酶谱也与大鼠肌肉细胞明显不同。体内接种实验和扫描电镜的观察表明,RC是非致瘤细胞。RC细胞各号染色体的C-带图样与大鼠二倍体细胞无明显的差异。     

糙叶败酱挥发油镇静作用的研究

本文观察了败酱科植物糙叶败酱(Patrinia scabra Bunge)根和根茎中制得的挥发油的镇静作用,井与黄花败酱挥发油做了比较。结果表明,此油灌胃给予数组小鼠,剂量0.45ml/kg,显示如下的作用:[1]能显著延长由于腹腔注射戊巴比妥钠(50mg/kg)引起的小鼠睡眠时间,但其作用强度弱于黄花败酱挥发油。(2)一次灌胃给予小鼠大剂量10.46g/kg的糙叶败酱挥发油,连续观察10天,动物外观正常,无一死亡,体重增加与对照组相似。     

应用MUCAP试剂快速检测沙门氏菌

报告了用4-甲基伞形酮辛酯(4-Methylumbelliferyl-caprylate, MUCAP)快速检测沙门氏菌的特异性、敏感性和实用性。经HE,DHL,SS和麦康凯琼脂平板分离的65株沙门氏菌标准菌株和48株从食品中分离的沙门氏菌,用MUCAP测试均呈阳性反应;394株非沙门氏菌中呈阳性反应的假单胞菌、气单胞菌、邻单胞菌可通过氧化酶试验与沙门氏菌区分开;与粘质沙雷氏菌的交叉反应改用加1％蔗糖的分离平板也可排除。此方法的敏感性和特异性均达到97％以上,而且操作简便、快速,数分钟内即可完成。     

质体醌重组的D1／D2／Cytb559复合物的荧光衰减动力学和光破坏作用

光系统Ⅱ反应中心Ｄ１／Ｄ２／Ｃｙｔｂ５５９ 在分离纯化过程中失去了电子受体ＱＡ 和ＱＢ,人工合成的质体醌可以与Ｄ１／Ｄ２／Ｃｙｔｂ５５９ 复合物发生重组。癸基质体醌（ＤＰＱ）与Ｄ１／Ｄ２／Ｃｙｔｂ５９９ 复合物的重组导致该复合物的荧光强度下降及发射光谱蓝移,同时两个与光化学活性相关的长寿命（２４ ｎｓ和７３ ｎｓ）荧光衰减组分占整个荧光的百分数下降,这些结果表明ＤＰＱ作为Ｐｈｅｏ－ 的电子受体,限制了Ｐ６８０＋ ·Ｐｈｅｏ－ 的电荷重组。ＤＰＱ 的加入对Ｄ１／Ｄ２／Ｃｙｔｂ５５９复合物中Ｃｈｌａ 分子的光破坏敏感性影响不大,但β－胡萝卜素在加入ＤＰＱ 之后可以被光照破坏,这个过程可能与β－胡萝卜素的生理功能相关。     

大别山北坡落叶阔叶林种间相关的研究

应用联结系数AC,点相关系数PCC,x~2检验和pearson相关系数r公式测定了大别山北坡落叶阔叶林的种间关系,依据种间联结程度将乔木层划分出3个生态种组,即栓皮栎──枫香种组,化香──短柄抱种组和锐齿栎──灯台树种组。