基因营养素—核酸在固体饲料的强化探讨

利用基因营养素－核酸作为强化剂添加在固体饲料中，中老年人通过补充核酸可以养育和修复基因，达到防病治病、延缓衰老、防治心脑血管疾病和糖尿病等目的。本文以基因营养素－核酸作为强化剂来生产固体饲料，就其原料、配方、工艺流程、治病机理、有效成分、组织结构、功效作用、吸收性、安全性、可行性等方面进行了详尽的介质和探讨。     

食品营养强化剂新品种6S-5-甲基四氢叶酸钙获批氮气等8种食品添加剂获准扩大使用范围

正国家卫生计生委发布2017年第13号公告指出,根据《中华人民共和国食品安全法》规定,审评机构组织专家对食品营养强化剂新品种6S-5-甲基四氢叶酸钙以及氮气等8种扩大使用范围的食品添加剂的安全性评估材料审查并通过。叶酸作为食品营养强化剂已列入《食品安全国家标准食品营养强化剂使用标准》(GB 14880),允许用于调制乳粉和固体饮料等食品类别。本次申请的6S-5-甲基四氢叶酸钙是叶酸的一种化合物来源,用于调制乳粉(儿童用乳粉和孕产     

食品营养强化剂在中国的应用现状及前景

<正> 人体日常所需的营养素高达四、五十种,按需求量可分为宏量营养素和微量营养素。宏量营养素包括蛋白质、脂肪、碳水化合物、水;微量营养素包括维生素和矿物质(包括常量元素和微量元素)。营养强化剂即为商品化的营养素,指"为增加营养成分而加入食品中的天然的或人工合成的属于天然营养素范围的食品添加剂"。根据中国食品营养强化剂食用卫生标准(GB14880-94)以     

铁营养强化剂的国内外应用情况及质量安全管理

食品营养强化剂是指为了增加食品的营养成分而加入到食品中的天然或人工合成的营养素和其他营养成分;营养素是指食物中具有特定生理作用,能维持机体生长、发育、活动、繁殖以及正常代谢所需的物质。在《GB14880-2012食品营养强化剂使用标准》发布前,主要依据《GB14880-1994营养强化剂使用卫生标准》（2760-1996附录B中）和199年～2012年卫生部1号公告。GB14880-2012标准相对于GB14880-1994标准发生了较大的变化,     

NaFeEDTA在食品中的应用

铁缺乏引起的缺铁性贫血是一个全球性的营养问题.NaFeEDTA是一种螯合型铁营养强化剂,近些年来研究证实NaFeEDTA具有生物利用率高、溶解性好、无铁味、无胃肠刺激、对其他微量元素吸收的无影响,对改善大人群缺铁性贫血有很好的效果,自1999年在我国批准作为营养强化剂,在面粉及其制品、固体饮料、调味品、饼干、乳品、保健食品等食品中都得到了应用,本文对NaFeEDTA在食品中应用进行了综述.     

NaFeEDTA在食品中的应用

铁缺乏引起的缺铁性贫血是一个全球性的营养问题.NaFeEDTA是一种螯合型铁营养强化剂,近些年来研究证实NaFeEDTA具有生物利用率高、溶解性好、无铁味、无胃肠刺激、对其他微量元素吸收的无影响,对改善大人群缺铁性贫血有很好的效果,自1999年在我国批准作为营养强化剂,在面粉及其制品、固体饮料、调味品、饼干、乳品、保健食品等食品中都得到了应用,本文对NaFeEDTA在食品中应用进行了综述.     

关注铁营养强化——NaFeEDTA在食品中的应用

铁缺乏引起的缺铁性贫血是一个全球性的营养问题。NaFeEDTA是一种鳌合型铁营养强化剂,近些年来研究证实NaFeEDTA具有生物利用率高、溶解性好、无铁味、无胃肠刺激、对其他微量元素的吸收无影响,对改善大人群缺铁性贫血有很好的效果,自1999年在我国批准作为营养强化剂,在面粉及其制品、固体饮料、调味品、饼干、乳品、保健食品筹食品中都得到了应用。     

开发蔬菜固体饮料

我国有关专家建议开发新型蔬菜固体饮料 ,以满足人们对蔬菜的需要 ,解决人们摄入蔬菜的问题。新型固体饮料的优点是 :口感好 ,食用方便 ;富含纤维素 ;保留大部分或全部蔬菜原料的维生素和其他营养素。开发蔬菜固体饮料系列产品的关键在于保留蔬菜原有营养和原汁原味的特色 ,但需要多层次的加工工艺 ,例如超声速射流低温粉碎、微胶囊或脂质体、菜粉发酵再制、抗氧化及“复氧”等技术的应用和研究 ,是高科技、高附加值的工艺。开发蔬菜固体饮料     

常吃核酸抗衰老

目前在美国、西欧、日本等国,各种核酸饮食、核酸保健品、核酸化妆品等风糜一时,备受青睐,核酸已成为抗衰老新宠。近代食品科学家已将核酸列为继蛋白质、脂肪、糖类、维生素、矿物质、纤维等营养素之外的“第七营养素。” 核酸是人体细胞中最重要     

利用乳酸锌强化食品的试验

锌是人体内最重要的微量元素之一。我国的膳食构成中易引起锌缺乏症。本试验利用乳酸锌作为锌强化剂对豆米粉,Vc固体饮料,豆奶进行了强化试验,试验结果表明:强化锌工艺简单,产品质地、风味不受显著影响,在食品中用乳酸锌强化锌是可行的     

Isolation and characterization of the ATF2 gene encoding alcohol acetyltransferase II in the bottom fermenting yeast Saccharomyces pastorianus

The ATF2 gene encodes alcohol acetyltransferase II, which catalyses the synthesis of isoamyl acetate from acetyl coenzyme A and isoamyl alcohol. To characterize the ATF2 gene from the bottom fermenting yeast Saccharomyces pastorianus, the S. pastorianus ATF2 gene was cloned by colony hybridization using the S. cerevisiae ATF2 gene as a probe. When an atf1 null mutant strain was transformed with a multi-copy plasmid carrying the S. pastorianus ATF2 gene, the AATase activity of this strain was increased by 2.5-fold compared to the control. The S. pastorianus ATF2 gene has 99% nucleic acid homology in the coding region and 100% amino acid homology with the S. cerevisiae ATF2 gene. Southern blot analysis of chromosomes separated by pulse-field gel electrophoresis indicated that the ATF2 gene probe hybridized to chromosome VII in S. cerevisiae and to the 1100 kb chromosome in S. pastorianus. As S. pastorianus is thought to be a hybrid of S. cerevisiae and S. bayanus, the S. bayanus-type gene, which has a relatively low level of homology with the S. cerevisiae-type gene, is also usually detected. Interestingly, an S. bayanus-type ATF2 gene could not be detected. These results suggested that the cloned ATF2 gene was derived from S. cerevisiae. Analysis using an ATF2-lacZ fusion gene in S. pastorianus showed that expression of the ATF2 gene was relatively lower than that of the ATF1 gene and that it is repressed by aeration but activated by the addition of unsaturated fatty acids. The S. pastorianus ATF1, Lg-ATF1 and ATF2 Accession Numbers in the DDBJ Nucleotide Sequence Database are D63449, D63450 and D86480, respectively.     

An integrase facilitates long-lasting foreign gene expression in vivo in mouse spermatogenic cells

The objective of the present study was to attain long-lasting foreign gene expression in vivo in spermatogenic cells in the mouse testis for establishing spermatogenic-cell mediated gene transformation. Prior to in vivo gene transfer, surgical cryptorchidism was performed by retaining the testis into the abdominal cavity for 1 month to remove differentiated spermatogenic cells. Subsequently, in vivo gene transfer was conducted by electroporation with a lacZ reporter gene in combination with a retroviral integrase gene, and the testis was descended immediately to the scrotum to recover from the cryptorchidism, and restart spermatogenesis. At 1 month post-transfection in vivo, lacZ gene expression was detected in some spermatocyte-like cells in seminiferous tubules of the mouse testis. However, the recovery period of 1 month appeared to be too short, since no elongated and fully differentiated spermatids were found. At 2 months post-transfection, fully differentiated spermatogenic cells expressing the lacZ gene, albeit at low frequency, were detected when the integrase gene was co-transfected, while virtually no lacZ-positive cells were found in the absence of the integrase gene. It was concluded, therefore, that stable transformation of spermatogenic cells in vivo would be facilitated by integrase gene co-transfection.     

热带假丝酵母ctfat1p基因在吸收脂肪族化合物中的功能研究

以热带假丝酵母(Candida tropicalis)1798中的ctfat1p基因为研究对象,利用重叠PCR将ctfat1p基因内约500 bp片段与G418抗性基因(kanr)相连接,经末端单酶切后电转化至C. tropicalis 1798感受态细胞中,通过一次同源单交换,将抗性基因kanr插入至ctfat1p基因内部,实现目的基因的敲除,并通过发酵实验分析Ctfat1p在热带假丝酵母脂肪酸跨膜转运过程中的功能。结果表明,经过G418抗性筛选和基因组PCR鉴定,成功获得ctfat1p基因缺失菌株C. tropicalis 1798 Δctfat1p;分析发现ctfat1p基因敲除对C. tropicalis 1798以油脂为底物培养12 h后重组菌OD600 nm值仅为野生型菌株的47.9%,表明ctfat1p基因敲除后影响C. tropicalis 1798对油脂吸收利用。通过基因敲除手段构建ctfat1p基因缺失菌株,可以减弱细胞对长链脂肪酸的摄取,验证了ctfat1p基因为热带假丝酵母油脂吸收和利用的关键基因。     

P. nalgiovense carries a gene which is homologous to the paf gene of P. chrysogenum which codes for an antifungal peptide

Penicillium nalgiovense is related to P. chrysogenum. P. chrysogenum carries the paf gene (Penicillium antifungal peptide) with homology to the afp gene of Aspergillus giganteus. This gene codes for a peptide with antifungal activity. Based on the sequence of the published P. chrysogenum paf gene primers were generated. By the use of these primers a PCR product of the expected length could be isolated from strains of P. nalgiovense. This fragment was sequenced and compared to the sequence of the paf gene of P. chrysogenum. According to the results P. nalgiovense carries a gene (naf = P. nalgiovense antifungal peptide) which is highly homologous to the paf gene of P. chrysogenum. The gene also codes for a preproprotein with the same processing sites as the paf gene, suggesting that the mature product is also a 55 amino acid (aa) peptide. The naf gene has three amino acid exchanges compared to the paf gene, which however do not influence the amino acid sequence of the mature peptide. It also carries two introns at the same positions, however, the sequence differences between the introns are higher than between the coding regions. When P. nalgiovense were grown on plates containing other food-relevant fungi it showed weak antifungal activity.     

Cloning of a novel tyrosinase-encoding gene (melB) from Aspergillus oryzae and its overexpression in solid-state culture (Rice Koji)

We have cloned a novel tyrosinase-encoding gene (melB) specifically expressed in solid-state culture of Aspergillus oryzae. A tyrosinase-encoding gene (melO) from A. oryzae was already cloned and the protein structures of its catalytic and copper binding domains were investigated. However, our recent results revealed that the melO gene was highly expressed in submerged culture but not in solid-state culture. Because tyrosinase activity was also detected in solid-state culture, we assumed that another tyrosinase gene other than melO is expressed in solid-state culture. Another tyrosinase gene was screened using the expressed sequence tag (EST) library. One redundant cDNA clone homologous with the tyrosinase gene was found in the collection of wheat bran culture. Northern blot analysis revealed that the gene corresponding to the cDNA clone was specifically expressed in solid-state culture (koji making), but not in submerged culture. Molecular cloning showed that the gene carried six exons interrupted by five introns and had an open reading frame encoding 616 amino acid residues. This gene was designated as melB. The deduced amino acid sequence of the gene had weak homology (24%-33%) with MelO and other fungal tyrosinases but the sequences of the copper binding domains were highly conserved. When the melB gene was expressed under the control of the glaB promoter in solid-state culture, tyrosinase activity was markedly enhanced and the culture mass was browned with the melanization by MelB tyrosinase. These results indicated that the melB gene encodes a novel tyrosinase associated with melanization in solid-state culture.     

食源性金黄色葡萄球菌青霉素类药物耐药基因型的分析

目的 建立多重PCR方法检测青霉素酶基因和mecA基因,了解食源性金黄色葡萄球菌两种β-内酰胺类药物耐药基因的分布情况,为金黄色葡萄球菌引起食源性疾病的防治提供参考数据.方法 建立多重PCR技术检测金黄色葡萄球菌青霉素酶基因、mecA基因和16S rDNA;多重PCR方法测定食品来源的171株金黄色葡萄球菌对青霉素类药物的耐药基因型.结果 165株菌携带有青霉素酶基因(96.5％),9株菌携带有mecA基因(5.3％).结论 建立的多重PCR检测方法快速、简便、准确,可满足高通量筛选菌株的需求;食源性金黄色葡萄球菌具有很高的青霉素酶基因携带率,并存在耐甲氧西林的菌株.     

Bayesian segregation analysis of somatic cell scores of Ontario Holstein cattle

Bayesian segregation analysis using a Gibbs sampling approach was applied to four sets of simulated data and one set of field data to detect evidence of major genes affecting the evaluated trait. The substitution effect of a major gene and its allelic frequency were estimated for each set of data. For two datasets simulated with a model with no major gene effect, the resulting estimates of polygenic variance and heritability agreed with the simulated values and tests for the presence of a major gene were not significant. Analyses of two sets of data simulated with a major gene produced posterior distributions that gave significant evidence of major gene effects but underestimated the substitution values of the major gene. The segregation analysis of field data suggested that a major gene significantly affected somatic cell score (SCS) in the population of Ontario Holstein cattle. The estimated heritability of SCS was approximately 0.16. The major gene variance accounted for about 17% of the total genetic variance and the point estimate of the frequency of the allele having a positive effect on SCS was 0.30. However, the precision of these estimates is questionable based on the simulation results. The effect of the major gene may be underestimated.     

奶山羊青春期乳腺发育重要基因RelA的全长克隆

从本实验室已建立的关中奶山羊7个时期乳腺Long-SAGE标签库中筛选出在青春期高表达的RelA基因,用RACE方法克隆并获得关中奶山羊RelA基因的全长,将全长序列与NCBI GenBank中人(H.sapiens)和牛(Bos taurus)数据库进行同源性比对,证实用所选EST标签引物克隆出的基因全长是奶山羊RelA基因.     

嗜热链球菌胸苷酸合成酶基因的克隆与序列分析

本研究以嗜热链球菌(S．thermophilus)染色体DNA为模板,利用PCR技术扩增出胸苷酸合成酶(thymidylate synthase,thyA)基因,将其克隆入T载体中,转化DH5α,筛选阳性克隆,提取质粒,进行酶切鉴定,PCR扩增鉴定,进行测序,与已知序列进行同源性比较,结果表明成功克隆了thyA基因,全长900bp,与国外报道的S．thermophilus ATCC19258 thyA基因同源性达99．9%。这为构建以thyA基因为选择压力的非抗生素抗性载体提供了理论依据。