转植酸酶基因玉米的研究与安全评价

植酸酶是应用最广泛的饲料添加剂之一,它在自然界中广泛存在,能提高饲料中磷的利用率,对减轻动物高磷粪便导致的环境水域污染有着重要意义.玉米是动物饲料的主要原料,在玉米饲料中添加植酸酶易造成饲料成本升高和生产效率降低等问题.近年来随着基因工程技术的发展,已克隆出多个真菌植酸酶基因,并成功在微生物、植物系统中表达.本文主要介绍了植酸酶基因的微生物来源与相关研究成果,阐述了转基因技术的常用方法和转植酸酶基因玉米的研究进展,并详细评价了转植酸酶基因玉米的安全性.通过对转植酸酶基因玉米的深入探讨,对改善玉米的品质,降低成本及推广植酸酶在饲料工业中的应用具有重要意义.     

植酸酶及其植物基因工程*

综述了植酸酶的来源、其酶学性质及植酸酶的植物基因工程,并对其存在的问题、应用前景作了展望。     

植酸酶的多样性及其分类

植酸酶是一类催化植酸水解逐步释放磷酸基团形成低级肌醇磷酸衍生物的正磷酸单酯磷酸水解酶。植酸酶在动物营养、资源环境保护和人类健康等领域有巨大的应用潜力。目前,人们对植酸酶的多样性及其分类的认识比较模糊甚至错误,严重影响了植酸酶的研究进程和水平。首先简要概述了基于最适pH和立体专一性的植酸酶分类,然后着重论述了基于结构和催化机理的植酸酶分类及其代表酶特征的最新研究进展,最后探讨了根据不同分类标准特别是基于结构和催化机理准确理解和全面表征各种植酸酶的重要性,以期为植酸酶的研究和应用提供参考。     

微生物植酸酶研究进展

植酸酶作为一种新型酶制剂,引起了国内外专家的广泛关注,对植酸酶进行了大量的研究工作。综述了近年来微生物胞内和胞外植酸酶分类、酶性质、酶活测定方法、酶作用机理、基因工程、酶的应用等方面的研究进展。     

植酸酶研究进展及土壤植酸酶应用展望

磷元素是农作物的主要营养限制因子之一,开发利用土壤中的磷资源对解决作物的磷素限制意义深远。植酸是土壤有机磷的主要形态,其矿化分解并释放有效磷的过程是一个酶促反应,植酸酶是这一过程的关键酶。植酸酶在土壤改良及农业的可持续发展领域具有较强的应用前景,高通量测序技术的出现也为土壤植酸酶研究提供了全新的思路和策略。综述了植酸酶的多样性、获取技术、提高产率的策略及在农业领域的应用现状,分析了土壤植酸酶研究存在的问题和未来发展的趋势,并对其应用前景进行了展望。     

植酸酶及其植物基因工程

综述了植酸酶的来源、其酶学性质及植酸酶的植物摹因工程,并对其存在的问题、应用前景作了展望。     

植酸酶及其基因工程研究进展

植酸酶可添加于食品与饲料中,能消除因不能降解的植酸所引起的抗营养作用,提高机体对蛋白质及多种微量元素的利用率,降低粪便中磷的含量,从而减少环境中磷的积累污染,有利于保护生态环境。弄清植酸酶的性质、基因结构和功能,了解其基因工程的研究进展,不仅具有重要的理论意义,而且在开发研究植酸酶制剂用于饲料、食品和医药等方面具有重要的实践价值。本文谨对植酸酶的性质、基因结构和功能及其基因工程的研究进展做一综述,并探讨了植酸酶的应用前景。     

饲用植酸酶蛋白质工程研究进展*

植酸酶作为一种单胃动物的饲料添加剂,它的推广和应用受到酶性质的局限。本在植酸酶改性策略,以及提高饲用植酸酶的表达量,改善热稳定性,提高催化效率,改良最适pH等方面介绍了植酸酶蛋白质工程方面的研究进展。     

植酸酶基因工程菌构建及其生产应用中问题分析

简要分析了植酸酶的生物学特性以及构建植酸酶基因工程菌和酶生产应用中存在的问题,提出了对植酸酶基因的重组改造、载体表达宿主筛选的方法和途径,以求构建高效表达、高活性和高稳定性的酶基因工程菌,促进酶的生产和应用。     

植酸酶的研究与应用进展

综述了植酸酶的生物学特性 ,产植酸酶的菌种来源 ,以及通过诱变和基因工程对菌种的选育 ,并阐述了植酸酶在饲料中的应用     

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.