杂种小麦及亲本旗叶老化过程中RubisCO特性的研究

小麦（ＴｒｉｔｉｃｕｍａｅｓｔｉｖｕｍＬ．）旗叶的ＲｕＢＰｃａｓｅ活性、含量及ＲｕＢＰｏａｓｅ活性在旗叶全展或全展后１０ｄ达最大值,以后逐渐下降。与亲本相比,供试杂种小麦“麦优４号”在旗叶一生中尤其老化后期上述参数皆表现明显的杂种优势。旗叶ＲｕＢＰｃａｓｅ比活性在叶绿素缓降期保持平稳,在叶绿素速降期逐渐下降。供试杂种小麦较亲本具有较高的ＲｕＢＰ羧化酶和加氧酶活性,表明杂种小麦不仅具有较强的光合羧化作用,而且叶片光合作用过程中的光呼吸也较强。结果与旗叶ＲｕｂｉｓＣＯ亲合ＣＯ２和Ｏ２的动力学常数的测定结果相符。     

水稻叶片生育过程中RubisCO活性与光合,光呼吸的关系

水稻生育过程中，ＲｕＢＰ羧化酶活性与光合速率，ＲｕＢＰ加氧酶活性与光呼吸速率、ＲｕＢＰ羧化酶活性与加氧酶活性以及光合速率与光呼吸速率之间是相关的。籼型品种与粳型品种间酶活性的高低及光合、光呼吸速率的高低基本一致，籼型三系杂交稻无明显的光合优势。酶的羧化活性搞低只在一定范围内与光合速率的高低平行，在正常生育条件下，酶蛋白的数量不是水稻光合速率的限制因子。     

水稻叶片生育过程中RubisCO活性与光合、光呼吸的关系

水稻生育过程中,ＲｕＢＰ羧化酶活性与光合速率、ＲｕＢＰ加氧酶活性与光呼吸速率、ＲｕＢＰ羧化酶活性与加氢酶活性以及光合速率与光呼吸速率之间是相关的。籼型品种与粳型品种间酶活性的高低及光合、光呼吸速率的高低基本一致,籼型三系杂交稻（Ｆ１）无明显的光合优势。酶的羧化活性的高低只在一定范围内与光合速率的高低平行。在正常生育条件下,酶蛋白的数量不是水稻光合速率的限制因子。     

杂交稻核酮糖二磷酸羧化酶的动力学性质

在ｐＨ８．０和３０Ｃ的条件下测定了杂交稻ＲｕＢＰ羧化酶的动力学常数,纯化酶测定值与粗酶快速测定值无明显差异。１２种不同组合的三系杂交稻其ＲｕＢＰ羧化酶动力学常数差不大,Ｋｍ（ＣＯ２）和Ｔｍａｘ的平均值与普通栽培品种也无显著差异。杂交稻汕优６３号ＲｕＢＰ羧化酶的动力学常数和酶蛋白含量与父本恢复系相类似,枰本不育系的Ｔｍａｘ和酶蛋白含量均较高。     

光和暗条件培养的眼虫藻内RuBP羧化酶的免疫定位

应用免疫金标记技术证明,在眼虫藻和其它藻类中ＲｕＢＰ羧化酶主要分布在蛋白核部位,这与高等植物中ＲｕＢＰ羧化酶分布不同,在眼虫藻叶绿体间质中有少量ＲｕＢＰ羧化酶存在,这与高等植物中ＲｕＢＰ羧化酶的分布也有相似之处。暗中培养的眼虫藻不能形成类囊体,无ＲｕＢＰ羧化酶,无光合能力,只能进行异养代谢。     

河西走廊芦苇在不同盐渍生境中RuBP羧化酶的比较研究

对不同盐渍生境中芦苇的ＲｕＢＰ羧化酶结构的研究表明,不同类型芦苇的ＲｕＢＰ羧化酶大、小亚基分子量相同,但盐化草甸芦苇和过渡地带芦苇与沼泽芦苇相比,ＲｕＢＰ羧化酶的亲水氨基酸相对含量增加,疏水氨基酸相对含量降低,酶分子被ＰＣＭＢ滴定的ＳＨ基数亦显著减少．表明芦苇的ＲｕＢＰ羧化酶结构发生了变化,反映出该酶有基因表达的环境适应．     

杂交稻核酮糖二磷酸羧化酶的动力学性质

在ｐＨ８．０和３０℃的条件下测定了杂交稻ＲｕＢＰ羧化酶的动力学常数,纯化酶测定值与粗酶快速测定值无明显差异。１２种不同组合的三系杂交稻（Ｆ１）其ＲｕＢＰ羧化酶动力学常数差异不大,Ｋｍ（ＣＯ２）和Ｖｍａｘ的平均值与普通栽培品种也无显著差异。杂交稻汕优６３号ＲｕＢＰ羧化酶的动力学常数和酶蛋白含量与父本恢复系相类似,而母本不育系的Ｖｍａｘ和酶蛋白含量均较高。     

二乙基亚硝胺诱发肝癌的大鼠中维生素K依赖性羧化酶的研究

本文证明DENA诱发的大鼠肝癌结节中维生素K依赖性羧化酶活性显著降低,外源多肽羧化酶活性只有正常大鼠肝脏中的62.6％,而内源蛋白质前体羧化酶活性仅为27％。华法令能在正常大鼠肝脏中诱导羧化酶的合成,而这种诱导能力在诱癌晚期的肝癌大鼠肝脏中明显下降。上述结果说明肝癌细胞中维生素K依赖性羧化酶的合成受阻,造成肝癌组织中羧化酶的缺乏。诱癌过程中大鼠肝脏维生素K依赖性羧化酶活性和血浆异常凝血酶原水平形成良好的对应关系。随着肝癌组织的增大,肝癌细胞分泌入血的异常凝血酶原水平显著升高,诱癌第20周时的大鼠血浆中异常凝血酶原含量为正常大鼠的2.5倍。由此认为,肝癌组织由于不能合成足量的维生素K依赖性羧化酶,导致凝血酶原在成熟过程中羧化受阻,分泌入血形成高水平的异常凝血酶原。     

ABA和6—BA对干旱玉米幼苗PEP羧化酶活性的影响（简报）

玉米幼苗ＰＥＰ羧化酶活性随着土壤含量的下降而逐渐下降,复水后其活性虽然有回升,但未恢复到干旱前水平,叶面喷施１０＾－５ｍｏｌ／Ｌ ６－ＢＡ可提高玉米幼苗ＰＥＰ羧化酶活性,而同样浓度的ＡＢＡ则抑制ＰＥＰ羧化酶活性。６－ＢＡ还可增加干旱条件下玉米幼苗的光合速率,叶水势和叶绿素含量。     

稀土离子对烟草RuBPcase的激活作用及EXFAS研究

研究了稀土离子（Ｌｎ３ ＋） 对烟草（Ｎｉｃｏｔｉａｎａ ｔａｂａｃｕｍ）１ ,５ － 二磷酸核酮糖羧化酶（ＲｕＢＰｃａｓｅ）活力的影响。结果表明,在该酶的反应体系中,用Ｌｎ３ ＋ 替代Ｍｇ２ ＋ ,烟草ＲｕＢＰｃａｓｅ 的活力随Ｌｎ３ ＋ 浓度的变化曲线呈双相效应, 即在高浓度时, Ｌｎ３ ＋ 抑制该酶活性; 低浓度的Ｌｎ３ ＋ 提高ＲｕＢＰｃａｓｅ 活性。其活化效应为轻稀土离子大于重稀土离子,但Ｌｎ３ ＋ 的活化效应低于Ｍｇ２ ＋ 。在有Ｍｇ２ ＋ 的反应体系中,Ｌｎ３ ＋ 在低浓度时也有提高ＲｕＢＰｃａｓｅ 活性的能力,提高幅度较低;而高浓度的Ｌｎ３ ＋ 显著地抑制酶活性。进一步对ＲｕＢＰｃａｓｅ － Ｌａ 二元复合物的ＥＸＦＡＳ 研究,证实Ｌａ３ ＋ 与ＲｕＢＰｃａｓｅ 氨基酸残基的Ｏ 原子键合,键长为２ ．５１?;Ｌａ３ ＋ 还与Ｓ 原子结合。最后对Ｌｎ３ ＋ 和ＲｕＢＰｃａｓｅ 相互作用的分子机制进行讨论     

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.