富硒产品中硒的形态分析及化学评分模式的建立

采用微波水解、HPLC-HG-AFS法测定了硒蛋白粉、硒蛋白片、肽粉、富硒原料等19种硒产品中的总硒、硒代氨基酸和亚硒酸根离子[Se(IV)],分析了硒代氨基酸、Se(IV)和其他形态硒占总硒的百分比及不同形态硒代氨基酸的组成比例。以此为依据,将硒产品分为硒蛋白型、单一硒代氨基酸型、其它形态硒型及有机无机硒混合型。根据DBS42/002-2014规定建立了富有机硒产品评分模式,其中18种为富有机硒产品;根据适硒地区母乳中硒代氨基酸的组成比例提出了硒代氨基酸的化学评分模式,评分结果显示13种以蛋白态硒为主的硒产品中硒代氨基酸的组成比例均与母乳相差甚远,不利于人体平衡吸收利用,其中10种SeMet含量远远超过人体所需,SeCys_2为限制硒代氨基酸。该评分模式的建立对硒产品的开发具有指导意义。     

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.     

硒在植物生命活动中的作用

简要叙述了微量元素硒在植物体内的吸收、运输、存在形态、生理功能及其与其他元素的相互作用，并就增加植物体内的硒含量提出了一些设想。     

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。     

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。     

青花菜硫、硒代谢竞争及其对保健功能的影响研究进展

青花菜含有天然活性成分萝卜硫素(sulforaphane),并且具有富硒能力。大量的流行病学、动物实验和临床研究表明,萝卜硫素和硒都具有抗多种癌症的生理功能,并且效果显著。已有的研究表明,硒与参与合成萝卜硫素的硫存在竞争效应,影响植物体内萝卜硫素含量。但两者在预防和治疗癌症中具有协同效应。硒和萝卜硫素的矛盾备受关注且对人类健康意义重大。本文综述了青花菜萝卜硫素和富硒能力的研究进展和关系,总结了二者抗癌功能的机制。     

钝顶螺旋藻富硒培养条件的优化

硒是人和动物必需的微量元素 ,补硒可以防治多种疾病。有机硒具有低毒、高生物利用度的优点 ,目前主要寄希望于生物转化的途径来获得有机硒[1 ] 。植物对硒的生物有机化作用已有综述[2 ] ,并开发有富硒酵母[3 ] 、富硒菇类[4] 、富硒大蒜、富硒黄芪、富硒西洋参、富硒麦芽、富硒茶以及富硒鸡蛋、富硒牛奶等[5] 。螺旋藻是一种很有开发利用前景的藻类 ,但其含硒量极微 ,实验报道富硒螺旋藻对60 Ｃｏ γ射线胸部照射大鼠诱发肺炎和早期肺、肝纤维增生有防治作用[6] 。在培养液中添加亚硒酸钠可以实现藻类对硒的富集和转化 ,而且螺旋藻对无机硒…     

几种开发的富硒野生植物研究进展

硒是人体必需的微量元素,与人体健康关系密切.野生植物是硒资源利用的重要途径.现今对植物富硒方面的研究主要还集中在传统栽培的粮食作物和经济作物,而野生植物资源在这方面的研究报道还较少.湖北恩施州硒资源丰富,本文对具有此地方特色的野生植物碎米荠、葛、板桥党参、显齿蛇葡萄、紫箕在含硒量、硒的存在形式、富集硒的特性、富硒技术及硒产品的药理保健作用等方面的研究概况进行了综述,并对研究前景进行了展望,以期为进一步的研究和相应富硒产品的开发提供参考信息.     

植物体内硒和硫的相互作用

植物体内硒,硫和同化途径类似,硒和硫的相互作用表现在植物中硒和硫的吸收,运输和积累过程以及植物硒甲基化过程中,可影响植物生长发育及品质成分,这种相互作用随植物种类,硒和硫形态,浓度,植物的生育期,以及生长部位的不同而呈现出不同的特点。     

富硒虫草的研究进展

虫草是传统名贵中药,具有抗癌、抗菌、调节免疫、降血脂、降血糖等广泛的药理作用;硒是人体必需的微量元素,具有抗癌、抗氧化、抗衰老等多种生理功能,与许多种疾病密切相关。利用虫草菌将无机硒转化为有机硒,实现虫草与硒的有机结合,研究功能更好的富硒虫草,无论作为药用、保健品还是补硒食品都具有很重要的现实意义。本文综述二十余年来富硒虫草的研究状况。     

富硒酵母中硒赋态的研究

硒是人体必需的一种微量元素,参与合成硒代半胱氨酸、硒代甲硫氨酸以及多种硒代蛋白(酶),具有抗肿瘤、抗氧化、增强人体免疫等多种生物学活性,与人体的健康有着密切关系.硒以不同的形式存在于自然界中,大致可分为无机硒和有机硒两种,其生物活性与毒性也各有不同.富硒酵母作为补充硒元素的主要形式之一,具有生物利用度高、食用安全、毒性低等优点.研究富硒酵母中的硒的赋态,对合理摄取硒元素,促进人体健康具有重要意义,因此成为近年来研究的热点.     

富硒益生菌的功效研究进展

硒是人体必需的微量元素,对人体健康有重要作用。益生菌能够将硒元素转化为有机硒,降低硒的毒性,同时硒又提高了益生菌的生物活性,富硒益生菌具备了硒和益生菌的双重功效。本文主要综述了近年来富硒益生菌的功效,如抗氧化、抑制有害菌、调节肠道菌群、抗癌等。     

Preparation of selenium yeasts I. Preparation of selenium-enriched Saccharomyces cerevisiae

Selenium (Se) is an essential micronutrient for human and animal organisms. Organic selenium complexes and selenium-containing amino acids are considered the most bioavailable.Under appropriate conditions yeasts are capable of accumulating large amounts of trace elements, such as selenium, and incorporating them into organic compounds. It has been found that introduction of water-soluble selenium salt as a component of the culture medium for yeasts produced by conventional batch processing results in a substantial amount of selenium being absorbed by the yeast.Using a culture medium supplemented with 30 μg/mL sodium-selenite added during the exponential growth phase results in selenium-accumulation in the range of 1200–1400 μg/g dried baker's yeast (Saccharomyces cerevisiae) measured by ICP-AES method. In our previous studies it was shown that higher amounts of sodium-selenite in the culture medium have a strong inhibitory effect on the growth of this yeast. As a consequence of variations in cultivation conditions we obtained selenium yeast with different inorganic selenium content. The most important parameters influencing incorporated forms of selenium are pH value and dissolved oxygen level in the culture medium, and depending on these the selenium consumption rate of the yeast. A 0.40–0.50 mg/g h-1 specific selenium consumption rate was found to be appropriate to obtain selenium-enriched bakers' yeast of a high quality. Under suitable conditions the undesirable inorganic selenium content of the yeast could be suppressed to as low as 5–6% at the expense, however, of approximately a 20% decrease in the final biomass.     

Environmental impact and bioremediation of seleniferous soils and sediments

Selenium concentrations in the soil environment are directly linked to its transfer in the food chain, eventually causing either deficiency or toxicity associated with several physiological dysfunctions in animals and humans. Selenium bioavailability depends on its speciation in the soil environment, which is mainly influenced by the prevailing pH, redox potential, and organic matter content of the soil. The selenium cycle in the environment is primarily mediated through chemical and biological selenium transformations. Interactions of selenium with microorganisms and plants in the soil environment have been studied in order to understand the underlying interplay of selenium conversions and to develop environmental technologies for efficient bioremediation of seleniferous soils. In situ approaches such as phytoremediation, soil amendment with organic matter and biovolatilization are promising for remediation of seleniferous soils. Ex situ remediation of contaminated soils by soil washing with benign leaching agents is widely considered for removing heavy metal pollutants. However, it has not been applied until now for remediation of seleniferous soils. Washing of seleniferous soils with benign leaching agents and further treatment of Se-bearing leachates in bioreactors through microbial reduction will be advantageous as it is aimed at removal as well as recovery of selenium for potential re-use for agricultural and industrial applications. This review summarizes the impact of selenium deficiency and toxicity on ecosystems in selenium deficient and seleniferous regions across the globe, and recent research in the field of bioremediation of seleniferous soils.     

Producing selenium-enriched eggs and meat to improve the selenium status of the general population

The role of selenium (Se) in human health and diseases has been discussed in detail in several recent reviews, with the main conclusion being that selenium deficiency is recognised as a global problem which urgently needs resolution. Since selenium content in plant-based food depends on its availability from soil, the level of this element in food and feeds varies among regions. In general, eggs and meat are considered to be good sources of selenium in human diet. When considering ways to improve human selenium intake, there are several potential options. These include direct supplementation, soil fertilisation and supplementation of food staples such as flour, and production of functional foods. Analysing recent publications related to functional food production, it is evident that selenium-enriched eggs can be used as an important delivery system of this trace mineral for humans. In particular, developments and commercialisation of organic forms of selenium have initiated a new era in the availability of selenium-enriched products. It has been shown that egg selenium content can easily be manipulated to give increased levels, especially when organic selenium is included in hen’s diet at levels that provide 0.3–0.5 mg/kg selenium in the feed. As a result, technology for the production of eggs delivering ≈50% (30–35 μg) of the human selenium RDA have been developed and successfully tested. Currently companies all over the world market selenium-enriched eggs including the UK, Ireland, Mexico, Columbia, Malaysia, Thailand, Australia, Turkey, Russia and the Ukraine. Prices for enriched eggs vary from country to country, typically being similar to free-range eggs. Selenium-enriched chicken, pork and beef can also be produced when using organic selenium in the diet of poultry and farm animals. The scientific, technological and other advantages and limitations of producing designer/modified eggs as functional foods are discussed in this review.     

硒的检测技术研究进展

硒是人和动物必需的微量元素之一,其存在形态划分为有机硒和无机硒,本文对总硒、有机硒的多种检测方法、原理及研究进展进行了综述,为硒产品开发研究工作提供依据。     

硒在苹果叶片中的赋存形式

通过筛选‘红富士’苹果适宜的叶面施硒浓度,研究了营养元素硒在苹果叶片中的赋存形式、分布及含硒大分子的提取分离技术。结果表明,（1）‘红富士’苹果最佳叶面施硒浓度为100mg·L-1,此处理的叶片总硒含量为2．7283mg·L-1（FW）,其中有机硒含量为2．3384mg·L-1（FW）,有机化程度达85．71％。（2）无论在对照组还是处理组,叶片中的有机硒均主要以蛋白质结合态存在,平均占有机硒的77．09％。（3）蛋白质、多糖和核酸3种有机物在100mg·L-1最优处理组的叶片中结合硒的量分别占有机硒含量的77．42％、18．46％和0．54％。（4）在100mg·L-1处理组的蛋白质组分中,又以盐溶性蛋白质结合硒的量最多,占蛋白质结合态硒含量的46．27％。     

环境与植物中硒形态研究进展

本文综述了近年来在环境及植物中的硒形态研究方面的进展。在土壤和水中各种不同形态硒的分布情况与ｐＨ值及其它特性之间的关系;植物中各种有机硒化合物的含量,可能的结构和硫素之间的关系,植物对硒的吸收转化过程等等     

Selenium uptake, translocation and speciation in wheat supplied with selenate or selenite

Selenite can be a dominant form of selenium (Se) in aerobic soils; however, unlike selenate, the mechanism of selenite uptake by plants remains unclear. Uptake, translocation and Se speciation in wheat (Triticum aestivum) supplied with selenate or selenite, or both, were investigated in hydroponic experiments. The kinetics of selenite influx was determined in short-term (30 min) experiments. Selenium speciation in the water-extractable fraction of roots and shoots was determined by HPLC-ICPMS. Plants absorbed similar amounts of Se within 1 d when supplied with selenite or selenate. Selenate and selenite uptake were enhanced in sulphur-starved and phosphorus-starved plants, respectively. Phosphate markedly increased K(m) of the selenite influx. Selenate and selenite uptake were both metabolically dependent. Selenite was rapidly converted to organic forms in roots, with limited translocation to shoots. Selenomethionine, selenomethionine Se-oxide, Se-methyl-selenocysteine and several other unidentified Se species were detected in the root extracts and xylem sap from selenite-treated plants. Selenate was highly mobile in xylem transport, but little was assimilated to organic forms in 1 d. The presence of selenite decreased selenate uptake and xylem transport. Selenite uptake is an active process likely mediated, at least partly, by phosphate transporters. Selenite and selenate differ greatly in the ease of assimilation and xylem transport.     

湖北省豆类植物种子硒含量的测定及赋存状态的研究

硒是人类必需的微量元素之一。我们对湖北省豆类植物种子的硒含量进行测定并对硒的赋存状态进行了研究。结果显示:大豆具有较强的富硒能力;大豆硒的赋存形态是含硒蛋白质,主要存在于白蛋白和球蛋白中;高硒地区的大豆含硒量比一般地区高近100倍。