鲤鱼,鲫鱼和鲤鲫移核鱼DNA的复性动力学研究与比较

才文报道鲤鱼、鲫鱼DNA复性动力学研究结果。它们均由快、中、慢速复性3个组份构成。鲤鱼DNA中Cot<1×10(-1)的复性组份占7.5％,1×10(-1)1×10~2的复性组份占75％;鲫鱼DNA中Cot<5×10~(-1)的复性组份占22％;5×10~(-1)1×10~2的复性组份占70％。它们都没有明显百分数的迥折序列组份;快速复性组份的拷贝数低于10~6,相当于中度重复序列1;中、慢速复性组份则分别为中度重复序列Ⅱ和原拷贝序列。在快速复性部份,鲤鱼与鲫鱼之间表现出较大差异。此外,本文还就鲤鱼和鲫鱼的DNA复性动力学与鲤鲫移核鱼(cyc(?))F_3进行了比较。鲤鲫移核鱼DNA的复性动力学特征与其细胞核供体鱼(即鲤鱼)是相似的。这说明异源细胞核与胞质的结合没有导致核内DNA基因组结构出现明显变化。     

植物组织切片谷氨酸传感器的研究

本文应用南瓜中果皮组织切片与BSA-戊二醛交联,然后与二氧化碳电极偶合组成了南瓜组织切片谷氨酸传感器.对电极的动力学响应特性,适宜的缓冲介质,不同pH及温度对电极响应的影响;电极的选择性及使用寿命作了研究。该电极在5.0×10~(-4)～1.0×10~(-2)mol/L谷氨酸浓度范围内,其动力学响应与谷氨酸浓度呈线性关系,相关系数为0.9586。计算得其Km值为7.13×10~(-3)mol/L,检测下限为3.0×10~(-4)mol/L,斜率为43mv/dec。该电极有良好的选择性。使用寿命可达一周以上。     

去甲肾上腺素、乙酰胆碱对绵羊心肌浦肯野纤维瞬时性内向离子流的影响

用电压箝制术观察了去甲肾上腺素、乙酰胆碱对绵羊浦肯野纤维由乙酰毒毛旋花子甙元诱发的瞬时性内向离子流(I_Ti)的效应。当乙酰毒毛旋花子甙元浓度为4.5×10~(-8)mol/L 时,诱发出的I_(T1)稳定并能维持约1.5h。去甲肾上腺素1.5×10~(-6)mol/L,可使I_(Ti)的峰值由11.4±2.5nA 增加到14.5±4.1nA(n=11,P相似文献   

体外组织培养增殖的油桐尺蠖核型多角体病毒毒力的生物测定

活体增殖和体外组织培养增殖的BsNPV悬液稀释成不同浓度,分别喷于人工饲料上,使其自然渗入饲料内,接3龄幼虫取食感染,感染剂量与幼虫死亡率的回归直线方程分别为;y=3.1815+0.679x和y=3.2000+0.665x,由回归直线方程推算的LD_(50)值及95％置信界限为4.0753×10~2[9.6075×10~2][1.7301×10~2]PIB/克饲料及5.0898×10~2[1.2411×10~3][2.0874×10~2]PIB/克饲料。感染剂量为4×10~5PIB/克饲料的LT_(50)值分别为4.7168天和4.8083天。比较两种来源的BsNPV,其多角体的感染力无明显差异。     

酿酒酵母原生质体融合的研究

本实验通过酿酒酵母(Saccharomyces cerevisiae)营养缺陷型菌株H802-9A(a ade~-his~7 cys~2 tyr~1)和H802-3 A(a ade~- cra~1)进行原生质体融合,获得营养互补的重组融合子,选择两亲株的对数生长早期细胞(2-4×10~7个/m1),在0.1％β-琉基乙醇及1-2％蜗牛酶的作用下,原生质体形成率达99-100％,在35％聚乙二醇(MW6000)-10mMCaC1溶液的作用下,可获得融合率为2.6×10~(-6)-2.1×10~(-7)的杂合子,自发回复突变率1.5-7×10~(-9)。     

HPLC法测定麻仁润肠丸大黄素、大黄酚的含量

采用KromacilC18(4 .6mm× 2 5 0mm ,5 μm)色谱柱 ,以甲醇 - 0 .1%磷酸溶液 (85∶15 )为流动相 ,流速为 1mL·min ,柱温为 30℃ ,检测波长为 2 5 4nm ,以外标法测定了麻仁润肠丸中大黄素、大黄酚的含量。大黄素在 8.992× 10 -3 ～ 116 .896× 10 -3 ,大黄酚在 2 1.376× 10 -3 ～ 2 77.85 8× 10 -3 范围内呈线性关系 ,其在制剂中的平均回收率 (n =6 )分别为 10 1.5 6 % (RSD =1.3% )、96 .78% (RSD =1.3% )。     

酿酒酵母原生质体融合及其融合子的鉴定

应用原生质体融合技术,得到乙醇产量较高的两株多倍体酵母菌融合子F_(28)和F_(38),融合频率为2×10~(-5)。测定融合子F_(28)、F_(38)每个细胞内DNA含量分别为2.14×10~(-8)、2.34×10~(-8)μg,而亲株DNA含量分别为0.78×10~(-8)和1.24×10~(-8)μg。并进行了融合子细胞增殖率、乙醇发酵能力及同功酶分析等试验。用固定化细胞发酵乙醇试验结果表明,在pH4.0,17％糖蜜为基质情况下,发酵3小时,融合子F_(28)、F_(38)的乙醇产量分别为77.21和77.09mg/ml;亲株乙醇产量仅为65.00mg/ml和68.40mg/ml。为固定化细胞发酵乙醇提供优良菌株。     

胰岛素依赖型糖尿病HLAⅡ类抗原DNA多态性研究

 用Southern DNA分析法,对正常人和胰岛素依赖型糖尿病(IDDM)病人外周血白细胞DNA进行限制性片段长度多态性(RFLP)研究。HLA抗原与IDDM相关,我们用HLA-DQβcDNA探针和EcoR Ⅰ、BamH Ⅰ内切酶,测得EcoR Ⅰ 2.2kb片段与正常人DR2抗原相关联(r=0.78,P=1×10~(-6),与IDDM DR2抗原无关联;此片段在DR2的正常组和IDDM组中的频率有显著差异(P=0.02)。EcoR Ⅰ 3.0kb和BamH Ⅰ 3.3kb片段在IDDM组中的频率均降低,与正常组比较其频率有显著差异(P=3.2×10~(-3)和P=1.8×10~(-3),这二片段的差异还未见报道。DNA的RFLP研究提示,IDDM病人中可能是由于基因片段的缺失或是基因结构的改变,导致经酶切后与探针杂交的结果与正常者有差异。     

乙酰胆碱对蟾蜍背根神经节神经元膜电位的影响及离子机制

在离体灌流的蟾蜍背根神经节(DRG)标本上,用微电极进行胞内记录。在73个神经元中,依神经纤维的传导速度将神经元分为 A 型及 C 型,其中 A 型细胞67个,C 型6个,静息膜电位为-67.5±1.3mV((?)±SE)。当加4×10~(-4)—6×10~(-4)mol/L 乙酰胆碱(ACh),可观察到如下四种膜电位变化:1.超极化:幅值9.1±3.0mV((?)±SE,n=23);(2)去极化:幅值12.9±2.2mV((?)+SE,n=20);(3)双相反应(n=24):先超极化,后去极化,超极化幅值8.0±2.4mV((?)+SE),去极化幅值10.9±3.1mV((?)±SE);(4)无反应(n=6)。用阿托品(1.3×10~(-5)mol/L,n=23),或同时应用筒箭毒与六甲双铵(浓度均为1.4×10~(-5)mol/L,n=8)灌流,能分别阻断 ACh 引起的膜的超极化或去极化。ACh 引起超极化反应时膜电导平均增加13.8%,翻转电位值大约-96mV。四乙铵(TEA,20mmol/L)能使 ACh 的去极化幅值增加48.2±3.2%((?)±SE,n=6),超极化幅值减小79.4±4.3%((?)±SE,n=8)。MnCl_2(4mmol/L)使 ACh 的去极化及超极化幅值分别减小54.2±7.2%((?)±SE,n=5)及69.2±6.4%((?)±SE,n=14)。以上结果提示:ACh 引起的 DRG 神经细胞膜去极化反应由 N 型乙酰胆碱受体介导,而超极化反应由 Μ 型乙酰胆碱受体介导,前者可能包含了多种离子电导的改变,后者则可能与钾电导增加有关。     

二乙基二硫代氨基甲酸钠对癌细胞的双时相毒性

二乙基二硫代氨基甲酸钠(DDC)(C_2H_5)_2NCS_2Na的浓度在10~(-5)～3×10~(-3)M范围内,对高度癌变的叙利亚地鼠成纤维细胞的集落形成率、DNA合成和细胞形态,都具有双时相特征的毒性。第一中毒时相发生在10~(-5)和10~(-4)M,第二时相在3×10~(-3)M。DDC也使含铜及锌的超氧化物歧化酶活性下降,但无时相性。     

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.     

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     

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.     

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.