植物硒同化的研究进展及其耐硒突变体的筛选

简要叙述了高等植物对硒元素吸收、同化的过程和特点。对近年来植物硒蛋白存在状态、硒相关突变体的筛选和应用硒代谢关键酶基因的转基因植物研究等方面的最新进展怍了扼要综述。在此基础上对植物硒营养研究的发展提出了几点设想。     

植物硒吸收转化机制及生理作用研究进展

硒是大多微生物、动物及人类的必要微量元素,但其在植物生长发育中的生理作用至今存在争议.较低浓度硒具有促进植物生长、提高植物耐受能力的功能,而大部分植物在高浓度下表现出中毒现象.随着人类对摄入硒及环境硒污染问题的认识加深,作物硒生物强化与硒污染植物修复问题引起重视,推动了对硒在植物中的吸收积累及代谢调控的研究.近年来对植物硒吸收及转化的研究表明,不同硒水平下植物对硒吸收积累及生理响应存在差异,土壤环境因素对植物硒吸收及转化具有重要影响,对高聚硒植物硒代谢研究逐渐揭示出硒在植物体内的转化过程和调控机理等.本文总结了目前硒生物强化与植物修复方面的研究进展,对环境中硒分布特点、植物硒吸收及其影响因素、植物体内硒转化及其过程调控关键酶,以及硒在植物中的生理作用等进行了综述,并对植物硒生理及分子机制未来研究方向进行展望.     

含硒酶与非酶作用机制

在微生物、植物和动物体内,硒的功能形式多种多样,但其作用机制可归纳为酶与非酶两个方面,含硒酶的作用主要有：谷胱甘肽过氧化物酶（GPx）家族催化超氧化物还原,防止细胞膜的氧化损伤;脱磺酶（ID）家族调节甲状腺激素代谢,硫氧还蛋白还原酶（TDR）家族催化硫氧还蛋白（Trx）还原,TDR／Trx系统为细胞的生长和分化所必需,硒的非酶化学保护作用体现在：可诱导一些蛋白激酶的富半胱氨酸结构域发生氧化还原修饰,增强免疫功能等作用,硒在植物中的作用机制具有许多特殊性。     

植物硒同化的研究进展及其耐硒突变体的筛选

简要叙述了高等植物对硒元素吸收、同化的过程和特点。对近年来植物硒蛋白存在状态、硒相关突变体的筛选和应用硒代谢关键酶基因的转基因植物研究等方面的最新进展作了扼要综述。在此基础上对植物硒营养研究的发展提出了几点设想。     

植物硒生理及与重金属交互的研究进展

硒是一种重要的微量元素,在低浓度时对生物有益,但高浓度时呈现与重金属类似的毒性。植物作为人体硒摄入的主要来源,其硒代谢对于植物硒积累乃至人体硒营养水平十分重要。研究植物硒吸收、代谢和积累机理能指导富硒粮食的生产,是解决人体硒摄入不足/超量问题的有效途径。本文在阐述土壤硒含量、形态、生物有效性及分布的基础上,综述了植物对硒的吸收、代谢机理的研究进展,并讨论了农业生物强化以及遗传育种生物强化等两种硒生物强化的实践方法,以及利用硒生物强化缓解重金属毒性减少积累;最后,提出了植物硒代谢及硒生物强化研究的前沿问题,以期为改善人体硒营养水平提高人体健康状况提供理论和实践依据。     

植物硒及其含硒蛋白的研究

硒是植物的有益元素,植物对硒的吸收与外源硒的有效性、硒的形态、植物的种类等有关;硒在植物中主要以有机硒形态存在,HPLC-ICP-MS联用已成为植物体内硒形态鉴定的最常用手段;含硒蛋白是植物体内最主要的有机大分子硒,具有抗肿瘤、抗氧化等多种生物活性。在环境安全和人类健康等方面,富硒植物具有很好的应用价值,所以利用分子生物学手段分析富硒植物的富硒机制,可以为富硒基因的筛选和利用提供理论依据。     

人体硒代谢与硒营养研究进展

硒是人体所必需的重要微量营养元素,综述了当前国内外人体硒代谢与硒营养的研究进展,包括硒源形式与吸收、人体的硒含量与分布、硒的代谢途径、硒的生物活化形式、硒与疾病、硒中毒和硒的安全摄入量。在此基础上,提出了针对我国硒资源分布、硒反应症分布和居民膳食结构硒摄入量的研究建议,为满足居民通过膳食和补充剂补硒预防和治疗疾病提供理论和实践指导。     

一株耐硒壶瓶碎米荠内生菌分离、鉴定及其体外硒代谢研究

【背景】壶瓶碎米荠对硒具有超积累能力,并主要以硒代胱氨酸的形式存在,与已有的硒超积累植物显著不同,其硒超积累机制不明。【目的】从硒超积累植物壶瓶碎米荠(Cardamine hupingshanensis)体内分离耐硒内生菌,并对其进行鉴定和体外硒代谢特征研究,为壶瓶碎米荠超积累硒的机制研究提供参考。【方法】从壶瓶碎米荠新鲜叶片中分离纯化耐硒内生菌株,对其进行生理生化特征及16S rRNA基因序列分析鉴定,并对其进行亚硒酸钠培养代谢。【结果】获得一株耐硒内生菌CSN-1,被鉴定为甲基营养型芽孢杆菌(Bacillus methylotrophicus),培养液中硒含量低(Se 1.5 mg/L)时其吸光度值较对照组高,硒含量高(Se 10 mg/L)时其吸光度值较对照组低;代谢后的上清液中硒主要以Se~(4+)存在,而菌体中硒主要是硒代胱氨酸(SeCys_2)。【结论】硒超积累植物壶瓶碎米荠叶片体内存在甲基营养型芽孢杆菌(Bacillus methylotrophicus)CSN-1,具有将亚硒酸钠转化为硒代胱氨酸的能力,低浓度的硒对该内生菌的生长具有一定的促进作用,而高浓度的硒则会抑制该内生菌的生长。     

硒酶及硒化合物生理功能研究的新进展

硒是动物必需的微量元素,硒半胱氨酸是硒蛋白的组份并构成硒酶的活性中心,硒蛋白特别是硒酶是硒的主要功能形式,研究发现,硒半胱氨酸是参入到蛋白质分子中的第21种氨基酸,硒是唯一受基因调控的微量元素,最新研究表明,硒及其化合物还具有阻断某些炎症介质的生理活性,抑制蛋白激酶C,激活促分裂原活化蛋白激酶和S6核糖体蛋白激酶,免疫调节及与其它元素和维生素相互作用等多种生理功能,提示硒在人类健康中的作用及其机制比我们过去所预计的更为复杂。     

富硒植物与人体健康

硒是生态环境中的一个重要微量元素。1957年施瓦茨发现,硒有抗氧化作用,并首次提出硒是人体的必需元素。同年,谷跳甘肽过氧化物酶被发现。1971年,Rotz－uch证明,硒是该酶的组成成分。1973年,世界卫生组织宣布硒是人体生命的必需元素。近年,德国植物营养学家已将硒列于植物有益元素的行列。硒通过生物地球化学营养链：岩石一土壤和水一植物一动物和人给人和动物以影响。几十年来的研究结果表明,人和动物的四十多种疾病与体内硒缺乏有关,典型疾病如地方性克山病、大骨节病、牲畜的白肌病。禽类的渗出性素质等,而硒制剂对这些疾病均…     

Carnobacterium: positive and negative effects in the environment and in foods

The genus Carnobacterium contains nine species, but only C. divergens and C. maltaromaticum are frequently isolated from natural environments and foods. They are tolerant to freezing/thawing and high pressure and able to grow at low temperatures, anaerobically and with increased CO(2) concentrations. They metabolize arginine and various carbohydrates, including chitin, and this may improve their survival in the environment. Carnobacterium divergens and C. maltaromaticum have been extensively studied as protective cultures in order to inhibit growth of Listeria monocytogenes in fish and meat products. Several carnobacterial bacteriocins are known, and parameters that affect their production have been described. Currently, however, no isolates are commercially applied as protective cultures. Carnobacteria can spoil chilled foods, but spoilage activity shows intraspecies and interspecies variation. The responsible spoilage metabolites are not well characterized, but branched alcohols and aldehydes play a partial role. Their production of tyramine in foods is critical for susceptible individuals, but carnobacteria are not otherwise human pathogens. Carnobacterium maltaromaticum can be a fish pathogen, although carnobacteria are also suggested as probiotic cultures for use in aquaculture. Representative genome sequences are not yet available, but would be valuable to answer questions associated with fundamental and applied aspects of this important genus.     

我国人与犬、猫共患病防控存在的主要问题与对策建议

随着社会经济的发展、城市化进程的加速及人们生活水平的不断提高,越来越多的宠物走进了人们的家庭,在人类社会生活中发挥了积极作用。但同时,宠物也是人兽共患病的重要传染源和传播媒介。与人类关系最为密切的犬、猫在人兽共患病的防控中具有重要的意义。在已报道的200多种主要的人兽共患病中,与宠物犬、猫有直接或间接关系的有70余种。随着宠物犬猫数量的大幅攀升和宠物业的飞速发展,我国人与犬猫共患病可能会出现逐步高发的趋势,疫病防控工作面临着许多问题。为了完善宠物管理制度,建立有效的防疫监督体系,对人与犬猫共患病实行有效的防控,本文就完善法律法规、形成综合管理机制,加强卫生监督、强化无害化处理、培养专业人才以及广泛开展宣传教育等6个方面提出了相关建议。     

Dogs and Cats in Animal Shelters in Japan

ABSTRACT

Although there are proportionately fewer pet owners in Japan than in the United States, the keeping of indigenous Japanese dog breeds, along with those common in Europe and North America, is long-established. Japan has a centralized governmental network of animal shelters, which permits accurate record-keeping of the numbers of dogs and cats admitted, reclaimed, and euthanized. Although in the United States an accurate census is not simple to accomplish because a variety of humane societies and animal control agencies admit homeless dogs and cats, some cultural comparisons are possible.

Despite recent increases in petkeeping in Japan, the numbers of dogs admitted to shelters have decreased from 345,136 dogs in 1984 to 243, 753 dogs in 1994. The numbers euthanized show similar declines, from 331,442 in 1984 to 219,831 in 1994. In the city of Tokyo, kittens account for the majority of the animals admitted: 34,745 kittens (55%) of a total of 62,803 dogs and cats in 1980; 12,805 kittens (61%) of a total of 21,075 in 1993. Cats usually are brought in after being found on the street and are not reclaimed by their owners; virtually all are euthanized. Most dogs, 61%, are caught as strays by shelter personnel. Among those admitted to Tokyo shelters, 41% are reclaimed or returned to the owner, 7% are adopted by new owners, and 52% are euthanized.

Spaying and neutering of dogs and cats are not wide spread practices in Japan. There are few private shelters; the government provides no tax incentives for charitable contributions to such organizations. While American shelters invariably offer animals for adoption, most of Japan's governmental shelters do not. However, this is gradually changing.     

生态毒理基因组学和生态毒理蛋白质组学研究进展

将基因组学和蛋白质组学知识整合到生态毒理学中形成了生态毒理基因组学和生态毒理蛋白质组学.通过生态毒理基因组学和生态毒理蛋白质组学的研究能够在基因组和蛋白质组水平更深入理解毒物的作用机制,寻找更敏感、有效的生物标记物,形成潜在的强有力的生态风险评价工具.介绍了生态毒理基因组学和生态毒理蛋白质组学的研究进展,以及DNA芯片技术和2D-凝胶电泳技术在持久性有毒污染物的生态毒理学研究中的应用.     

Genes involved in phenotypic and antigenic variation in African trypanosomes and malaria

Large polymorphic gene families that are involved in clonal phenotypic variation have been identified in both African trypanosomes and malaria parasites. Many of these gene families are necessary for host adaptation, allowing the parasite to infect different species of host or types of host cells. In many cases, switching between these functionally variable proteins also results in antigenic variation.     

Commonness,rarity, and intraspecific variation in traits and performance in tropical tree seedlings

One of the few rules in ecology is that communities are composed of many rare and few common species. Trait‐based investigations of abundance distributions have generally focused on species‐mean trait values with mixed success. Here, using large tropical tree seedling datasets in China and Puerto Rico, we take an alternative approach that considers the magnitude of intraspecific variation in traits and growth as it relates to species abundance. We find that common species are less variable in their traits and growth. Common species also occupy core positions within community trait space indicating that they are finely tuned for the available conditions. Rare species are functionally peripheral and are likely transients struggling for success in the given environment. The work highlights the importance of considering intraspecific variation in trait‐based ecology and demonstrates asymmetry in the magnitude of intraspecific variation among species is critical for understanding of how traits are related to abundance.     

Duplication and divergence in humans and chimpanzees

It has become a truism that we humans are genetically about 99% identical to chimpanzees. The origins of this assertion are clear: among early studies of DNA sequences, nucleotide identity between humans and chimpanzees was found to average around 98.9%.(1) However, this figure is correct only with respect to regions of the genome that are shared between humans and chimpanzees. Often ignored are the many parts of their genomes that are not shared. Genomic rearrangements, including insertions, deletions, translocations and duplications, have long been recognized as potentially important sources of novel genomic material(2,3) and are known to account for major genomic differences between humans and chimpanzees.(4) Further, such changes have been implicated in a number of genetic disorders, such as DiGeorge, Angelman/Prader-Willi and Charcot-Marie-Tooth syndromes.(5)     

Symbionts and organelles in ancrobic protozoa and fungi

The discovery of methanogenic bacteria as endosymbionts of free-living anaerobic protozoa opened new fields of research in microbial ecology, cell physiology and molecular biology. Recent information from 16S rRNA sequence studies has shown in three cases that endosymbiotic methanogenic bacteria differ from free-living species. Frequently, endosymbiotic methanogens are localized in anaerobic protozoa near hydrogenosomes - organelles that produce H2, C02 and acetate, all of which are substrates for methanogenesis. Hydrogenosomes are also present in anaerobic fungi. The current view is that the organelles are endosymbllont-derived and were probably acquired on several distinct occasions during evolution.     

Flavonoid and isoflavonoid distribution in developing soybean seedling tissues and in seed and root exudates

The distribution of flavonoids, isoflavonoids, and their conjugates in developing soybean (Glycine max L.) seedling organs and in root and seed exudates has been examined. Conjugates of the isoflavones daidzein and genistein are major metabolites in all embryonic organs within the dry seed and in seedling roots, hypocotyl, and cotyledon tissues at all times after germination. Primary leaf tissues undergo a programmed shift from isoflavonoid to flavonoid metabolism 3 days after germination and become largely predominated by glycosides of the flavonols kampferol, quercetin, and isorhamnetin by 5 days. Cotyledons contain relatively constant and very high levels of conjugates of both daidzein and genistein. Hypocotyl tissues contain a third unidentified compound, P19.3, also present in multiple conjugated forms. Conjugates of daidzein, genistein, and P19.3 are at their highest levels in the hypocotyl hook and fall off progressively down the hypocotyl. These isoflavones also undergo a programmed and dramatic decrease between 2 and 4 days in the hypocotyl hook. All root sections are predominated by daidzein and its conjugates, particularly in the root tip, where they reach the highest levels in the seedling. Light has a pronounced effect on the distribution of the isoflavones; in the dark, isoflavone levels in the root tips are greatly reduced, while those in the cotyledons are higher. Finally, the conjugates of daidzein and genistein and several unidentified aromatic metabolites are selectively excreted into root and seed exudates. Analysis of seed exudates suggests that this is a continuous, but saturable event.     

Chiasmata and variability in Lolium and Festuca populations

There are significant differences in mean pollen mother cell chiasma frequencies between populations within Lolium perenne, L. multiflorum and Festuca pratensis. The differences are genotypically controlled. With low chiasma frequencies the chiasmata are distally located. With increasing chiasma frequency the frequency of chiasmata in interstitial segments increases. Shorter lived populations have higher chiasma frequencies than the more perennial. — The higher the chiasma frequency of a population the lower the phenotypic and genetic variance for characters under polygenic control, such as flowering time, and the less effective also is the response to selection for such characters. These observations are interpreted on the premise that high chiasma frequencies are instrumental in the breaking up of supergene sequences in interstitial chromosome segments.