酪氨酸对大鼠离体颗粒细胞孕酮、雌激素和cAMP生成的影响

本实验应用培养细胞悬浮液的方法,研究了酪氨酸对经 PMSG 处理的未成熟大鼠颗粒细胞孕酮、雌激素和 cAMP 生成的影响。给30天龄未成熟雌鼠皮下注射 PMSG 100单位/只48小时后,取出卵巢,分离出排卵前卵泡中的颗粒细胞,制成细胞悬浮液。按实验要求,在细胞悬浮液中加入(1)培养液空白,(2)hCG(101U),(3)酪氨酸(20μg)和(4)α-MT(20μg)。培养45分钟后,取出一部分样品用蛋白竞争结合法测各管 cAMP 含量。培养4小时后,用放射免疫分析法测各管孕酮和雌激素含量。结果表明,hCG 和酪氨酸均可促进颗粒细胞孕酮、雌激素和 cAMP 的生成,当两者共同作用时,孕酮、雌激素和 cAMP 的生成量进一步增加。α-MT 与酪氨酸的作用相同,在α-MT 与酪氨酸共同作用时,不但未阻断酪氨酸的作用,而且α-MT 本身也表现酪氨酸样的作用,使孕酮、雌激素和 cAMP 的生成量进一步增加。本实验结果提示,酪氨酸而非其衍生物,可促进大鼠离体排卵前卵泡的颗粒细胞生成孕酮和雌激素。酪氨酸的这一作用可能是通过 cAMP 完成的。     

大鼠黄体细胞酪氨酸含量及hCG,cAMP和孕酮对含量的影响

经PMSG-hCG处理的未成年雌性大鼠卵巢,用胶原酶-DNA酶溶液消化,制成黄体细胞悬浮液。预培育1h后,加入不同浓度的hCG、cAMP及孕酮;并在加入hCG(10mIU/ml)、cAMP(2.5mmol/L)或孕酮(1nmol/L)的同时分别加入苯丙氨酸或放线菌酮,再培育1.5h,取细胞悬浮液400μl,用薄层层析扫描技术测其酪氨酸含量。结果:黄体细胞内有一定量内源酪氨酸,hCG,cAMP和孕酮均可明显促进酪氨酸的释放(P<0.05).苯丙氨酸对酪氨酸的含量无影响。酪氨酸释放也不依赖蛋白质合成过程。     

L-酪氨酸对大鼠黄体细胞3β-羟-甾体脱氢酶活性的影响

目的:研究L-酪氨酸对离体培养大鼠黄体细胞3β-HSD活性的影响.方法:运用细胞培养技术和放射免疫分析法,观察不同剂量L-酪氨酸对大鼠黄体细胞3β-HSD活性的影响和L-酪氨酸及其类似物酪氨酰肼在拮抗hCG诱导孕酮生成作用中,3β-HSD活性的变化.结果:①0.2 mmol-1和2.0 mmol-1的L-酪氨酸明显抑制3β-HSD的活性,相同浓度的L-苯丙氨酸及L-多巴胺对此酶活性无影响;②在底物浓度较低时,L-酪氨酸可显著增强3β-HSD活性,随着底物浓度的增加,L-酪氨酸的作用逐渐减弱并转为抑制作用.③L-酪氨酸及酪氨酰肼对hCG诱导的3β-HSD活性有明显的抑制作用.结论:L-酪氨酸可明显影响大鼠黄体细胞3β-HSD活性,其作用性质与底物浓度密切相关.L-酪氨酸及酪氨酰肼抑制hCG诱导的3β-HSD活性.     

L-酪氨酸对大鼠黄体细胞3p-羟-甾体脱氢酶活性的影响

目的：研究L-酪氨酸对离体培养大鼠黄体细胞3β-HSD活性的影响。方法：运用细胞培养技术和放射免疫分析法,观察不同剂量L-酪氨酸对大鼠黄体细胞3β-HSD活性的影响和L-酪氨酸及其类似物酪氨酰肼在拮抗hCG诱导孕酮生成作用中,3β-HSD活性的变化。结果：①0．2mmol^-1和2．0mmol^-1的L酪氨酸明显抑制3β-HSD的活性,相同浓度的L-苯丙氨酸及L-广多巴胺对此酶活性无影响;②在底物浓度较低时,L-酪氨酸可显著增强3β-HSD活性,随着底物浓度的增加,L-酪氨酸的作用逐渐减弱并转为抑制作用。③L-酪氨酸及酪氨酰胼对hCG诱导的3β-HSD活性有明显的抑制作用。结论：L-酪氨酸可明显影响大鼠黄体细胞3β-HSD活性,其作用性质与底物浓度密切相关。L-酪氨酸及酪氯酰肼抑制hCG诱导的3β-HSD活性。     

小鼠卵巢对酪氨酸的摄取与酪氨酸抗hCG致孕酮生成作用

末成年小鼠用PMSG处理后48小时,注射hCG(5单位/10克体重)诱发排卵。在注射hCG后12、24、48、96、144小时,静脉注射~3H-酪氨酸(5μCi/10克体重)5分钟后摘取卵巢,干燥、称重、消化后,加闪烁液测其放射性(以cpm/毫克干重表示)。结果表明,卵巢对~3H-酪氨酸的摄取量,在排卵后显著增加。随着孕酮分泌的增加,卵巢对酪氨酸的摄取亦增加,两者的变化趋势一致。此外,本文证明,卵巢摄取的外源酪氨酸,对hCG诱发的孕酮生成有抑制作用。     

酪氨酸对人离体滋养层细胞孕酮与hCG分泌的影响

本文观察三种剂量(2×10~(-5)mol/L,2×10~(-4)mol/L和2×10~(-3)mol/L)的酪氮酸对离体培养的滋养层细胞孕酮及hCG分泌的影响,并对其抑制效应的机理作了初步探讨。实验结果表明,三种剂量的酪氨酸均可抑制滋养层细胞孕酮分泌(P<0.01),但是,在孕酮分泌受酪氨酸抑制的同时,未见对hCG分泌发生影响(P>0.05),进一步观察了酪氨酸对滋养层细胞3β-羟甾脱氢酶活性的影响,结果表明,酪氨酸能显著抑制3β-羟甾脱氢酶活性,提示酪氨酸对滋养层细胞孕酮生成的抑制作用与抑制3β-羟甾脱氢酶活性有关。     

酪氨酸对大鼠离体Leydig细胞睾酮和cAMP生成的影响

本实验采用胶原酶消化,Ficoll 密度梯度离心,制备大鼠睾丸 Leydig 细胞悬浮液进行体外培养(每管内含有10~6 细胞),以研究酪氨酸对 Leydig 细胞睾酮和cAMP 生成的影响。实验结果表明,hCG(100mIU)能明显地促进Leydig 细胞睾酮和 cAMP的生成。睾酮从对照组的3.08±0.58ng(X±SD,下同)增加到41.61±1.52ng,cAMP 含量从19.62±2.56pmol增加到153.24±5.92pmol。若将酪氨酸(60μg)与hCG同时加入到细胞培养液中,则睾酮和cAMP 含量分别下降到 19.22±.0.52ng(P<0.01)和92.63±6.02pmol(P<0.05)。但是,酪氨酸羟化酶抑制剂(α-甲基酪氨酸)对酪氨酸抗hCG致睾酮生成作用无阻断效应,而酪氨酸对外源cAMP(2.5mM)诱导的睾酮生成,则有明显的抑制作用,睾酮含量从27.56±1.53ng降至 19.50±0.47ng(P<0.01)。以上实验结果表明,酪氨酸抗hCG致睾酮生成的作用机理与cAMP有关。     

酪氨酸对未成年小鼠和大鼠诱发排卵和孕酮含量的影响

本实验室曾证明酪氨酸有抗hCG致孕酮生成作用,同时也发现酪氨酸对大鼠排卵前的颗粒细胞有促进cAMP和甾体激素合成作用,表明酪氨酸对卵巢有逆向的双重作用。本文观察酪氨酸对未成年小鼠和大鼠诱发排卵和血清孕酮含量的影响。结果显示酪氨酸有促进未成年小鼠和大鼠诱发排卵和提高孕酮的作用。苯丙氨酸和色氨酸无此作用。在甲状腺素、去甲肾上腺素和多巴胺等酪氨酸衍生物中,仅多巴胺与酪氨酸的作用相似。     

酪氨酸对大鼠生殖内分泌功能的影响

在假妊大鼠,口服酪氨酸可使卵巢静脉血中孕酮含量减少,子宫静脉血中前列腺素含量增加,卵巢对~(125)I-hCG 的结合力降低。在切除一侧卵巢的大鼠,口服酪氨酸可使对侧卵巢代偿性增生及子宫重量增加受抑制。同时也明显地抑制卵巢 hCG 受体功能,使卵巢对~(125)I-hCG 的结合力,hCG 受体数目和亲和力降低。本实验结果提示,酪氨酸可直接或间接作用于卵巢,抑制黄体功能,使孕酮分泌减少,从而可能具有抗生育作用。     

~3H-酪氨酸与大鼠离体黄体细胞的结合

用孕马血清促性腺激素和hCG处理25—28d龄未成年雌性大鼠,造成超排卵并形成黄体,取hCG处理后7d的黄体制备黄体细胞。将黄体细胞与~3H-酪氨酸一起孵育(24℃,45min)后,~3H-酪氨酸能与黄体细胞特异结合,~3H-酪氨酸浓度为7.5μmol/L时达到饱和,在4℃孵育10min条件下仍有~3H-酪氨酸的结合。用哇巴因抑制酪氨酸向细胞内的转运后,~3H-酪氨酸的特异结合依然存在,放线菌酮也不能影响~3H-酪氨酸结合。这些结果证明,酪氨酸能与黄体细胞特异结合,并提示酪氨酸的结合位点存在于细胞膜上。     

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.