鲫鱼视网膜亮度型水平细胞上不同视锥信号的相互作用:实验及模型

本文应用胞内记录和动态模型分析方法,研究了离体鲫鱼视网膜视锥驱动的高度型水平细胞（ＬＨＣ）上不同视锥信号的相互作用。实验表明,绿背景光的作用可以提高ＬＨＣ的红光反应,这种增强作用与绿敏锥的活动程度密切相关,模型分析表明,背景光 的作用谷氨酸介导的前馈性通路和ＧＡＢＡ介导的反馈性通路活动同时得以增强,水平细胞对光反应的增强效应不能为外泊性ＧＡＢＡ所消除。则其程度为前馈性通路和反馈性通路活动增加的相对     

缓激肽抑制大鼠DRG分离神经元的GABA激活电流

本文应用全细胞膜片箝技术在新鲜分离的大鼠背根神经节（ＤＲＧ）神经元上研究缓激肽（ＢＫ）对γ－氨基丁酸（ＧＡＢＡ）反应的调制作用。结果发现：在３４个对ＧＡＢＡ反应的细胞中有３１个细胞对ＢＫ敏感。在对ＢＫ敏感并引起内向电流的２７个细胞中预加ＢＫ,对ＧＡＢＡ－激活电流具有明显的抑制作用,如１０＾－６ｍｏｌ／Ｌ的ＢＫ可抑制ＧＡＢＡ（１０＾－４ｍｏｌ／Ｌ）激活电流３０％。ＢＫ可将ＧＡＢＡ量效曲线明显下移,并     

赤霉素与脱落酸对番茄种子萌发中细胞周期的调控

利用细胞流检仪检测番茄（Ｌｙｃｏｐｅｒｓｉｃｏｎ ｅｓｃｕｌｅｎｔｕｍ Ｍｉｌｌ．） ＧＡ－缺陷型、ＡＢＡ－缺陷型和相应的正常品种（野生型）成熟种子胚根尖细胞倍性水平时发现：ＧＡ－缺陷型和野生型种子绝大多数细胞ＤＮＡ 水平为２Ｃ,而ＡＢＡ－缺陷型种子则含有较多的４Ｃ细胞。在标准发芽条件下,ＡＢＡ－缺陷型和野生型种子浸种１ ｄ 后胚根尖细胞ＤＮＡ 开始复制,随后胚根突破种皮而发芽。然而ＧＡ－缺陷型种子除非加入外源ＧＡ,否则既不发生细胞ＤＮＡ 复制,也不发芽。这说明内源ＧＡ 是启动番茄种子胚根尖细胞ＤＮＡ 复制的关键因素,同时也说明番茄根尖细胞ＤＮＡ 复制是种子发芽的必要条件。实验证明：ＡＢＡ 不抑制细胞ＤＮＡ 合成,但阻止Ｇ２ 细胞进入到Ｍ 期。外源ＡＢＡ处理野生型种子与渗控处理结果相似,可以大幅度提高胚根尖４Ｃ／２Ｃ细胞的比例,但抑制种子的最终发芽     

糖皮质激素对谷氨酸和DGABA受体的电生理反应的快速调制作用

在大鼠下丘脑薄片和豚鼠腹腔神经节上,分别用玻璃微电极细胞外和细胞内记录方法,观察了１０－６ｍｏｌ／Ｌ糖皮质激素（ＧＣ）对谷氨酸和ＧＡＢＡ受体介导效应的快速调制作用。结果表明,ＧＣ灌流后５ｍｉｎ,对谷氨酸受体介导的效应起抑制作用,而对ＧＡＢＡ受体介导的效应起增强作用。撤除ＧＣ后,神经元对谷氨酸和ＧＡＢＡ的反应恢复到对照水平。低钙高镁灌流液不能取消ＧＣ的调制作用。结果提示,ＧＣ在不需要突触环路条件下,可能通过非基因组途径影响谷氨酸和ＧＡＢＡ受体介导的效应。     

糖皮质激素对谷氨酸和GABA受体的电生理反应的快速调制作用

在大鼠下丘脑薄片和豚鼠腹腔神经节上,分别用玻璃微电极细胞外和细胞内记录方法,观察了１０＾６ｍｏｌ／Ｌ糖皮质激素（ＧＣ）对谷氨酸和ＧＡＢＡ受体分层效应的快速调制作用。结果表明,ＧＣ灌流后５ｍｉｎ,对谷氨酸受体介导的效应起抑制作用,而对ＧＡＢＡ受体介导的效应起增强作用。撤除ＧＣ后,神经元对谷氨酸和ＧＡＢＡ的反应恢复到对照水平。低钙高镁灌流液不能取消ＧＣ的调制作用。结果提示,ＧＣ在不需要突触环路条件下,     

脑源性神经营养因子（BDNF）在成肌细胞中的稳定表达

将ｂｄｎｆ基因克隆入逆转录病毒载体ｐＬＮＣＸ,构建得到ｐＬＮＣ／ＢＤＮＦ,经ＰＡ３１７细胞包装后,感染大鼠成肌细胞Ｌ６ＴＧ,Ｇ４１８筛选２周后,得到稳定表达ｂｄｎｆ基因的细胞克隆Ｌ６ＴＧ／ＢＤＮＦ。ＤＮＡ印迹结果证实ｂｄｎｆ基因已经整合入Ｌ６ＴＧ染色体中,ＲＮＡ印迹和斑点印迹结果分别从ｍＲＮＡ水平和蛋白水平证明了ｂｄｎｆ基因的表达,且Ｌ６ＴＧ／ＢＤＮＦ培养上清中ＢＤＮＦ的含量约为２５ｎｇ（１０６细胞数每ｍｌ每２４ｈ）。     

SKF38393抑制大鼠DRG分离神经元GABA-激活电流

在大鼠新鲜分离ＤＲＧ神经元标本上应用全细胞膜片箝记录,观察了多巴胺Ｄ１受体的选择性激动剂ＳＫＦ３８３９３ＨＣＩ对ＧＡＢＡ－激活电流的作用。大部分受检细胞对ＧＡＢＡ敏感,１０＾－６－１０＾－３－ｍｏｌ／Ｌ ＧＡＢＡ可于引起呈剂量依赖性的明显去敏感作用的内向电流。     

豚鼠腹腔神经节细胞γ－氨基丁酸双相反应的药理学特性

在豚鼠腹腔神经节细胞,γ－氨基丁酸（ＧＡＢＡ）可诱发“去极化－超极化”的双相反应,去极化伴膜电阻减小,超极化伴膜电阻增大,这种反应在低钙高镁液中仍然存在。蝇蕈醇可模拟ＧＡＢＡ双相反应,但在诱发相同强度的去极化反应时,蝇蕈醇产生的超极化弱于ＧＡＢＡ。荷包牡丹碱（１００μｍｏｌ／Ｌ）和印防已毒素（１００—３００μｍｏｌ／Ｌ）能可逆地抑制ＧＡＢＡ诱发的双相反应。Ｂａｃｌｏｆｅｎ对神经节细胞的膜电位无明显影响。结果提示,ＧＡＢＡ双相反应的去极化相由ＧＡＢＡＡ／Ｃｌ－通道受体复合物介导,而超极化相很可能由不同于经典的ＧＡＢＡＡ受体,但其药理学行为又由与之十分相近的另一种ＧＡＢＡ受体介导。     

球茎甘薯花托及花柄切口直接出芽的研究

培养球茎甘蓝的带有花托、花柄和子房的外植体。在附加ＢＡ和ＧＡ３的培养基上,花托部位直接出芽;在附加不同浓度ＢＡ的培养基和附加ＢＡ和ＧＡ３的培养基上均诱导花柄切口直接出芽,在附加ＢＡ和ＮＡＡ的培养基上,花托花柄切口剧烈增生愈伤组织,组织细胞学观察了芽的发生过程,结果表明;花托芽是由靠近维管束的多个皮层薄壁细胞恢复分理解能力形成,并与母体建立维管联系;花柄切口出芽是由皮层几个相靠近的薄壁细胞恢复分裂能     

5—HT对大鼠新鲜分离DRG神经元GABA激活电流的调制作用

本实验在新鲜分离的大鼠背根神经节（ＤＲＧ）细胞上应用全细胞膜片钳技术,观察５－ＨＴ对ＧＡＢＡ激活电流的调制作用。结果发现,绝大多数细胞（４９／５４）对ＧＡＢＡ（１０－８～１０－３ｍｏｌ／Ｌ）产生浓度依赖性的内向电流,并有明显的去敏感现象。在多数细胞预加５－ＨＴ（１０－７～１０－４ｍｏｌ／Ｌ）,ＧＡＢＡ激活电流受到明显抑制,抑制率分别为３．０％,１３．５％,１９．７％,２４．７％,５９．１％。５－ＨＴ（１０－７～１０－４ｍｏｌ／Ｌ）本身在部分细胞（２４／４０）可引起浓度依赖性的内向电流,部分细胞（１２／４０）未检测到膜电流,少数细胞（４／４０）可引起微弱的外向电流。此结果提示５－ＨＴ可能作用于初级传入终末,抑制ＧＡＢＡ引起的初级传入去极化从而调节ＧＡＢＡ的突触前抑制效应     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.