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。     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).