Selenoproteins synergistically protect porcine skeletal muscle from oxidative damage via relieving mitochondrial dysfunction and endoplasmic reticulum stress

Background The skeletal muscle of pigs is vulnerable to oxidative damage,resulting in growth retardation.Selenoproteins are important components of antioxidant systems for animals,which are generally regulated by dietary selenium(Se)level.Here,we developed the dietary oxidative stress(DOS)-inducing pig model to investigate the protective effects of selenoproteins on DOS-induced skeletal muscle growth retardation.Results Dietary oxidative stress caused porcine skeletal muscle oxidative damage and growth retardation,which is accompanied by mitochondrial dysfunction,endoplasmic reticulum(ER)stress,and protein and lipid metabolism disorders.Supplementation with Se(0.3,0.6 or 0.9 mg Se/kg)in form of hydroxy selenomethionine(OH-SeMet)linearly increased muscular Se deposition and exhibited protective effects via regulating the expression of selenotranscriptome and key selenoproteins,which was mainly reflected in lower ROS levels and higher antioxidant capacity in skeletal muscle,and the mitigation of mitochondrial dysfunction and ER stress.What’s more,selenoproteins inhibited DOS induced protein and lipid degradation and improved protein and lipid biosynthesis via regulating AKT/mTOR/S6K1 and AMPK/SREBP-1 signalling pathways in skeletal muscle.However,several parameters such as the activity of GSH-Px and T-SOD,the protein abundance of JNK2,CLPP,SELENOS and SELENOF did not show dose-dependent changes.Notably,several key selenoproteins such as MSRB1,SELENOW,SELENOM,SELENON and SELENOS play the unique roles during this protection.Conclusions Increased expression of selenoproteins by dietary OH-SeMet could synergistically alleviate mitochondrial dysfunction and ER stress,recover protein and lipid biosynthesis,thus alleviate skeletal muscle growth retardation.Our study provides preventive measure for OS-dependent skeletal muscle retardation in livestock husbandry.

Selenoprotein W cDNAs From Five Species of Animals

The nucleotide sequences of the open reading frames of cDNAs for selenoprotein W from skeletal muscle of rat, mouse, sheep, rhesus monkey and human are reported. Theoretical translation of the coding sequences indicated highly similar proteins of 88 (mouse and rat) or 87 (human, monkey and sheep) amino acids. In 73 of 88 positions the specified amino acids are identical for all five proteins. TGA encoding selenocysteine is the 13th codon of all the cDNAs. The rnouse, rat and sheep open reading frames terminate with TGA but the human and rhesus monkey coding regions terminate with TAA. The encoded amino acid sequences are identical for the rat and mouse proteins, and for the human and monkey proteins. The similarity of the cDNAs continues in the 3' noncoding regions through the putative selenocysteine insertion sequence (SEClS) elements which are required for correct interpretation of the selenocysteine codon. The region between the SECIS elements and the polyadenylation signals showed much lower similarity. The cloned rat gene for selenoprotein W is 5000 bases long,with the 663 bases of the cDNA in six exons. The transcription start site was identified by nuclease protection assay to be 16 bases upstream of the longest cDNA clone. A canonical TATA box occurs 150 bases upstream, but the assay did not indicate the presence of longer mRNAs

Selenocysteine tRNAs as Central Components of Selenoprotein Biosynthesis in Eukaryotes

Selenocysteine (Sec) tRNAs serve as carrier molecules for the biosynthesis of Sec from serine and to donate Sec to protein in response to specific UGA codons. In this study, we describe the current status of Sec tRNAs in higher animals and further we exarnine: (i) the Sec tRNA population in Drosophila; (ii) transcription of the Sec tRNA in vivo (in Xenopus oocytes) and in vitro (in Xenopus oocyte extracts); (iii) the effect of selenium on the Sec tRNA population in various rat tissues following replenishment of extremely selenium deficient rats with this element; and (iv) the biosynthesis of the modified bases on Sec tRNA in Xenopus oocytes

Selenium and Iodine Deficiencies and Selenoprotein Function

This paper reviews some recent findings on the interactions between selenium deficiency and iodine deficency. Both micronutrients can control the levels of selenoprotein mRNAs, particularly in the thyroid and brain. When selenium and iodine supplies are limiting the compensatory mechanisms work to minimise adverse effects on thyroid hormone metabolsm and thus neurological developtnent. The mechanisms for regulation of selenoproteins in selenium and iodine deficiency are however very tissue-specific. For example, unlike the brain and thyroid,brown adipose tissue is unable to retain selenoproteins in selenium and iodine deficiency and is therefore at greater risk from injurious effects of the deficiencies.

Biological Functions of Selenoprotein Iodothyronine Deiodinase and its Expression in Osteoarthritis

Objective Iodothyronine deiodinases(DIOs)are important selenoproteins that play a key role in the bone and joint diseases.Osteoarthritis(OA)is the most prevalent joint disease especially in elders.This bioinformatic analysis was performed to explore the role of DIOs in OA pathogenesis.Methods The biological functions of selenoprotein DIOs were analyzed by bioinformatic techniques,mcluding GenCLip 3.0,Database for Annotation,Visualization and Integrated Discovery(DAVID),STRING,Cytoscape,and Network Analyst.The expression of DIOs in the healthy individuals and OA patients was determined by mining OA-related microarray data in the gene expression omnibus(GEO)database of National Center for Biotechnology Information and performing a Meta-analysis of the data with Review Manager 5.3.Results Cluster analysis revealed that the function of the DIOs was associated with thyroid hormone receptor and iodothyronine;GO analysis showed that DIOs were mainly involved in biological processes,such as ethanol metabolism and phenol-containing compound metabolism and primarily involved in the cytochrome P450 metabolism of exogenous organisms and thyroid hormone signaling;SULT1A1 was the core node of the PPI network;miRNAs and thyroid hormones had some iterations with DIO1 and DI02;Meta-analysis showed that DIO3 expression was significantly up-regulated in OA patients(SMD=0.31,95%CI:0.03,0.59,P=0.03).Conclusions The main biological functions of DIOs were closely associated with the regulation of thyroid hormone.And the up-regulated expression of DIO3 may have crucial impact on the occurrence of OA.

RNA and Protein Requirements for Eukaryotic Selenoprotein Synthesis

Selenium has been recognized as an essential nutrient in animals since the 1950s. Demonstration of the role of dietary selenium in protection from oxidative stress foIlowed in the early 1970s, and was largely attributed to its presence as an integral part of cellular glutathione peroxidase. However, the functions of this enzyme did not explain many of the other effects of selenium deficiency. The identification of other mammalian selenoproteins during the last few years has provided new insights into the functions of this trace nutrient. The discovery that type 1 deiodinase (D1) is a selenoenzyme, in addition to unveiling an essential role for selenium in thyroid hormone action, has had more far-reaching implications. Studies of this protein opened the door for investigation of the requirements for eukaryotic selenoprotein synthesis,and the features that distinguish this pathway from the corresponding prokaryotic pathway.Selenium is present in a number of prokaryotic and eukaryotic proteins in the form of the unusual amino acid, selenocysteine. Incorporation of selenocysteine into these proteins requires a novel translation step in which UGA specifies selenocysteine insertion. Since UGA codons are typically recognized as translation stop signals, an intriguing question is raised: How does a cell recognize and distinguish a UGA selenocysteine codon from a UGA stop codon? In this review, we will focus on what is known about selenocysteine incorporation in eukaryotes, briefly summarizing initial studies and discussing a few recent advances in our understanding of this unique 'recoding' process

Two New Selenoproteins Found in the Prostatic Glandular Epithelium and in the Spermatid Nuclei

After labeling of rats in vivo with 75Se and protein separation by sodium dodecyl sulfatepolyacrylamide gel electrophoresis more than 25 Se-containing bands could be distinguished.Of those proteins which were detected only in certain compartments and might therefore have tissue-specific functions, two were chosen for detailed investigation.A 15 kDa-protein was found in the prostatic epithelium where it accounted for about two thirds of the protein-bound 75Se. It was mainly present in the cytosol but was not released into the prostatic secretion. After gel chromatography it was found in the fraction which contained proteins with molecular masses of about 300 kDa. Using two-dimensional electrophoresis a plvalue of about 4. 5 was determined.In the testis a specific Se-containing 34 kDa-protein was observed which appeared after the onset of puberty. It was localized in the spermatid nuclei where it contained about 80% of the Se tracer present and was found to be bound to the DNA. After extraction it partly disintegrated into a 20 kDa-protein.Both compounds contain Se in the form of selenocysteine. The fact that their formation had priority over that of glutathione peroxidase during insufficient Se intake is an indication of their biological significance. Special interest in the prostatic epithelial selenoprotein derives from a possible inverse relationship between the Se status and the incidence of prostate cancer observed in epidemiological studies, whereas with the 34 kDa-selenoprotein its appearance during the condensation phase of the spermatid nuclei might suggest its participation in some processes of sperm maturation

Ebola viral selenoproteins:a metallomics analysis

Ebola virus infection is the present public health problem.The trend of worldwide epidemic becomes the serious consideration for this infection.The Ebola virus infection has main clinical manifestation as acute febrile illness with hemorrhagic episode.The problem of hemostatic disturbance can be seen.Focusing on the palhophysiology.selenium plays an important role in the blood clotting regulation.The study on the selenoprotein of the Ebola virus can be useful for further understanding on the pathology of the infection.Here,the authors use metallomics analysis for assessment of Ebola virus genome.According to this study,the selenoprotein portion within Ebola virus genome can be detected at position 1046-1115.

Maternal reproductive health: Expression patterns of antioxidant enzyme selenoproteins of post-implantation embryos conceived by ethanol-treated murine mothers supplemented with α-tocopherol

Objective:To investigate if the protective effect ofα-tocopherol against the impact of ethanol on brain morphogenesis involved the activity of the selenoproteins phospholipid hydroperoxide glutathione peroxidase (PHGPx;GPx4) and selenoprotein P (SelPP) that have roles against oxidative stress.Methods:Forty female mice were randomly assigned into natural control (CON), positive control (ETOH), low-, medium-, and high-α-tocopherol-supplemented-ethanol groups (LTOC, MTOC, HTOC, respectively). CON received drinking water without ethanol while ETOH, LTOC, MTOC and HTOC groups received 20% ethanol in drinking water. The supplemented groups were given respective dosages ofα-tocopherol, 0.410, 0.819, and 1.640 mg/g body weight, at day 14 before mating onwards to the day 9 of gestation. At 10.5 ED of gestation (1100 h), the pregnant females were sacrificed by cervical dislocation and the embryos were harvested. Total RNA were extracted, cDNA synthesis and qRT- PCR analyses were carried out.Results: The level of expression of PHGPx in the positive control was significantly lower than that of the natural control. Among the threeα-tocopherol-supplemented groups, only the medium dose- group was significantly higher than the positive control. The level of expression of SelPP in the positive control was significantly lower than those of the natural control, the low- and medium- dose -tocopherol supplemented groups. In the high dose-α-tocopherol supplemented group, the level of expression was not significantly different from the positive control but significantly lower than the natural control.Conclusions: The activity of the selenoproteins PHGPx and SelPP are involved in the internetwork of antioxidative enzymes with vitamin E when given up to a medium dose only and is one of the possible pathways of shielding embryonic development against the impact of ethanol on brain morphogenesis. This study strengthens the impact of dietaryα-tocopherol and Selenium supplement during the critical period of pregnancy.

Selenoprotein P mRNA expression in human hepatic tissues

AIM: To investigate the expression of selenoprotein P mRNA (SePmRNA) in tissues of normal liver, liver cirrhosis and hepatocellular carcinoma (HCC), and its relationship with HCC occurrence and development. METHODS: The expression of SePmRNA in tissues of normal liver, liver cirrhosis and HCC were detected by in situ hybridization using a cDNA probe. RESULTS: The enzyme digesting products of PBluescript-H uman Selenoprotein P were evaluated by electrophoresis. The positive expression of SePmRNA was found in the tissues of normal liver, liver cirrhosis and HCC. The expression of SeP mRNA was found in hepatic interstitial substance, especially in endothelial cells and lymphocytes of vasculature. The positive rate of SePmRNA in normal liver tissue was 84.6% (11/13) and the positive signals appeared in the nucleus and cytoplasm, mostly in the nucleolus, and the staining granules were larger in the nucleolus and around the nucleus. The positive rate of SePmRNA in liver cirrhosis tissue was 45.0% (9/20) and the positive signals were mainly in the nucleolus and cytoplasm, being less around the nucleus and inner nucleus than that in normal liver tissue. The positive rate of SePmRNA in HCC tissue was 30.0% (9/30) and the positive signals were in the cytoplasm, but less in the nucleus. CONCLUSION: SePmRNA expression in the tissues of normal liver and HCC is significantly different (84.6% vs 30.0%, P = 0.003), suggesting that SeP might play a role in the occurrence and development of HCC.

Selenoprotein expression is regulated at multiple levels in prostate cells

在有低基础血硒层次的一张人口的硒补充被报导了减少包括前列腺癌症的几癌症的发生。基于的在临床的调查结果，至少一 selenoproteins 的抗氧化剂功能为 chemopreventive 效果负责，是可能的，尽管低分子量 seleno 混合物也被安置了有选择地在转变房间导致 apoptosis。在前列腺房间在 selenoprotein 表示上探讨硒补充的效果，我们在 non-tumorigenicprostate 承担了抗氧化剂 selenoprotein 表示以及硒毒性的分析上皮的房间(RWPE-1 ) 和前列腺癌症房间(LNCaP 和 PC-3 ) 。我们的结果证明二个谷胱甘肽过氧化物酶家庭成员(GPX1 和 GPX4 ) 被补加的硒高度在前列腺癌症房间劝诱，但是仅仅稍微在 RWPE-1 导致了房间。另外， GPX1levels 作为与 RWPE-1 或 LNCaP 房间相比在 PC-3 房间是戏剧性地更低的。然而， GPX2 蛋白质 andmRNA 在 RWPE-1 房间仅仅是可检测的。测试的三硒混合物(钠亚硒酸盐，钠硒酸盐和 selenomethionine ) ，仅仅钠亚硒酸盐在硒集中的一个生理的范围显示出毒性。尤其是并且与以前的研究相对照， RWPE-1cells 是显著地对比前列腺癌症的任何一个，房间衬里的亚硒酸盐更敏感。这些结果证明那 selenoproteins 和硒新陈代谢在前列腺房间在多重层次被调整。

Role of selenoprotein M knockdown in the melatonin antagonism of nickel-induced apoptosis and endoplasmic reticulum stress in mouse heart

The aim of this study was to investigate the role of selenoprotein M(SelM)in endoplasmic reticulum stress and apoptosis in nickel-exposed mouse hearts and to explore the detoxifying effects of melatonin.At 21 d after intraperitoneal injection of nickel chloride(NiCl_(2))and/or melatonin into male wild-type(WT)and SelM knockout(KO)C57BL/6J mice,NiCl_(2)was found to induce changes in the microstructure and ultrastructure of the hearts of both WT and SelM KO mice,which were caused by oxidative stress,endoplasmic reticulum stress,and apoptosis,as evidenced by decreases in malondialdehyde(MDA)content and total antioxidant capacity(T-AOC)activity.Changes in the messenger RNA(mRNA)and protein expression of genes related to endoplasmic reticulum stress(activating transcription factor 4(ATF4),inositol-requiring protein 1(IRE1),c-Jun N-terminal kinase(JNK),and C/EBP homologous protein(CHOP))and apoptosis(B-cell lymphoma-2(Bcl-2),Bcl-2-associated X protein(Bax),Caspase-3,Caspase-9,and Caspase-12)were also observed.Notably,the observed damage was worse in SelM KO mice.Furthermore,melatonin alleviated the heart injury caused by NiCl_(2)in WT mice but could not exert a good protective effect in the heart of SelM KO mice.Overall,the findings suggested that the antioxidant capacity of SelM,as well as its modulation of endoplasmic reticulum stress and apoptosis,plays important roles in nickel-induced heart injury.

Carrimycin,a first in-class anti-cancer agent,targets selenoprotein H to induce nucleolar oxidative stress and inhibit ribosome biogenesis

Carrimycin is a synthetic macrolide antibiotic that has been shown to have anti-cancer activity;however,its exact mechanism of action and molecular target were previously unknown.It was recently elucidated that Isovalerylspiramycin I(ISP I),the active component of carrimycin,targets selenoprotein H(SelH),a nucleolar reactive oxygen species-scavenging enzyme in the selenoprotein family.ISP I treatment accelerates SelH degradation,resulting in oxidative stress,disrupted ribosomal biogenesis,and apoptosis in tumor cells.Specifically,ISP I disrupts the association between RNA polymerase I and ribosomal DNA in the nucleolus.This inhibits ribosomal RNA transcription and subsequent ribosomal assembly,which prevents cancer cells from sustaining elevated rates of protein synthesis and cellular proliferation that are necessary for tumor growth and malignancy.In this review,we(1)describe the historical categorization and evolution of anti-cancer agents,including macrolide antibiotics,(2)outline the discovery of SelH as a target of ISP I,and(3)summarize the ways in which carrimycin has been used both clinically and at the bench to date and propose additional potential therapeutic uses.

血清硒蛋白P与类风湿关节炎的相关性

目的探讨血清硒蛋白P与类风湿关节炎(RA)的相关性。方法选取RA病人96例为研究对象(RA组),根据疾病活动度评分分为稳定期49例,活动期47例;选取同期健康查体者50例为对照组。采用ELISA法检测两组血清硒蛋白P浓度。结果RA组与对照组血清硒蛋白P浓度差异有统计学意义(t=-7.169,P<0.001);RA稳定组与活动组血清硒蛋白P浓度差异有统计学意义(t=-4.964,P<0.001),C反应蛋白(CRP)、红细胞沉降率(ESR)差异也均有统计学意义(Z=-4.796、-4.194,P<0.05)。二分类Logistic回归分析显示,高硒蛋白P、高CRP的RA病人疾病活动度增高的风险增加(OR=1.286~1.368,P<0.05)。结论血清硒蛋白P是RA病人疾病活动的独立危险因素。

黄颡鱼硒蛋白基因的克隆与分析

为探讨黄颡鱼硒蛋白selenow2a、selenop2和selenot2基因之间的关系,采用3′/5′RACE PCR克隆得到3个基因的cDNA全长,分别为891、1998和1432bp,其中ORF长度分别为288、828和600bp,编码95、275和219个氨基酸。在线工具SECISerach3对3个基因的cDNA序列分析结果显示,它们都含有可以编码硒代半胱氨酸的终止密码子,以及在3′非编码区存在SECIS元件。通过氨基酸序列比对和系统发育树分析,发现sele-now2a、selenop2和selenot2基因预测得到的氨基酸序列与斑马鱼(Danio rerio)氨基酸相似性分别为82.24%、66.19%和79.45%,而与斑点叉尾鮰(Ictalurus punetaus)的氨基酸相似性分别为94.74%、68.50%和90.95%,在发育树上则显示为树杈相接近。采用实时荧光定量PCR检测3个硒蛋白基因的mRNA在黄颡鱼心脏、肝脏、肌肉、脑、肠、脾脏、精巢和卵巢组织中的表达,结果显示其mRNA表达水平呈现组织特异性。表明3个基因拥有硒蛋白家族的特征,但在组织表达上具有特异性。

Identification of selenocyst-eine insertion sequence(SECIS) element in eukaryotic selenoproteins by RNA Draw program

The computer program RNA Draw was used to identify the secondary structures in the 3’untranslated regions (3’UTRs) of the mRNAs from 46 eukaryotic seleno-proteins among 7 species. The program found one or two possible SECIS elements in these selenoproteins. The SECIS element consists of a stem-loop or hairpin structure with three conserved sequences of AUGA-(A)AA-GA. SECIS element was not found by the RNA Draw program in randomly selected non-selenoproteins. The results showed that SECIS element is the unique character of the genes ofeukaryotic selenoproteins. Thus it is possible to use RNA Draw to search the SECIS elements in gene bank for potential new selenoproteins.

Determination of optimal dietary selenium levels by full expression of selenoproteins in various tissues of broilers from 1 to 21 d of age

The current NRC dietary selenium(Se)requirement(0.15 mg/kg)of broilers is primarily based on growth performance data reported in 1986.Our study aimed to determine optimal dietary Se levels of broilers fed a practical corn-soybean meal diet for the full expression of selenoproteins in various tissues.A total of 384 one-d-old male broilers(n=8 replicates/diet)were fed a basal corn-soybean meal diet or the basal diet supplemented with 0.1,0.2,0.3,0.4 or 0.5 mg Se/kg in the form of Na_(2)SeO_(3) for 21 d.Regression analysis was conducted to evaluate the optimal dietary Se levels using broken-line,quadratic or asymptotic models.The activity of glutathione peroxidase(GPX)in the plasma,liver,kidney and pancreas,iodothyronine deiodinase(DIO)in the plasma,liver and pancreas,and thioredoxin reductase(Txnrd)in the liver and pancreas,the mRNA levels of Gpx1,Gpx4,Dio1,selenoprotein(Seleno)h,Selenop and Selenou in the liver,Gpx4,Dio1,Txnrd1,Txnrd2,Selenoh,Selenop and Selenou in the kidney,and Gpx1,Gpx4,Selenoh and Selenou in the pancreas,and the protein levels of GPX4 in the liver and kidney of broilers were influenced(P<0.05)by added Se levels,and increased quadratically(P<0.05)with the increase of added Se levels.The estimates of optimal dietary Se levels were 0.07 to 0.36 mg/kg based on the fitted broken-line,quadratic or asymptotic models(P<0.001)of the aforementioned selenoprotein expression in the plasma,liver and kidney,and 0.09 to 0.46 mg/kg based on the fitted broken-line models(P<0.001)of the aforementioned selenoprotein expression in the pancreas.The results indicate that the optimal dietary Se levels would be 0.36 mg/kg to support the full expression of selenoproteins in the plasma,liver and kidney,and 0.46 mg/kg to support the full expression of selenoproteins in the pancreas of broilers fed a practical corn-soybean meal diet from 1 to 21 d of age.

New selenoproteins identified in silico from the genome of Anopheles gambiae

Selenoprotein is biosynthesized by the incorporation of selenocysteine into proteins,where the TGA codon in the open reading frame does not act as a stop signal but is translated into selenocysteine.The dual functions of TGA result in mis-annotation or lack of selenoproteins in the sequenced genomes of many species.Available computational tools fail to correctly predict selenoproteins.Thus,we devel-oped a new method to identify selenoproteins from the genome of Anopheles gambiae computationally.Based on released genomic information,several programs were edited with PERL language to identify selenocysteine insertion sequence(SECIS)element,the coding potential of TGA codons,and cys-teine-containing homologs of selenoprotein genes.Our results showed that 11365 genes were termi-nated with TGA codons,918 of which contained SECIS elements.Similarity search revealed that 58 genes contained Sec/Cys pairs and similar flanking regions around in-frame TGA codons.Finally,7 genes were found to fully meet requirements for selenoproteins,although they have not been anno-tated as selenoproteins in NCBI databases.Deduced from their basic properties,the newly found se-lenoproteins in the genome of Anopheles gambiae are possibly related to in vivo oxidation tolerance and protein regulation in order to interfere with anopheles' vectorial capacity of Plasmodium.This study may also provide theoretical bases for the prevention of malaria from anopheles transmission.

Determination of optimal dietary selenium levels by full expression of selenoproteins in various tissues of broilers from 22 to 42 d of age

The current NRC dietary selenium(Se)requirement(0.15 mg/kg)of broilers from 22 to 42 d of age is primarily based on a previous study reported in 1986,which might not be applicable to modern classes of rapidly growing broilers.The present experiment was conducted to determine the optimal dietary Se level for meeting metabolic and functional Se requirements of broilers fed a corn-soybean meal diet from 22 to 42 d of age.A total of 336 Arbor Acres male broilers at 22 d old were randomly assigned to 1 of 6 treatments with 7 replicates and fed a basal corn-soybean meal diet(control,containing 0.014 mg Se/kg)and the basal diet supplemented with 0.10,0.20,0.30,0.40,or 0.50 mg Se/kg from Na_(2)SeO_(3) for 21 d.The results showed that the Se concentrations in plasma,liver,kidney,pancreas,breast and thigh muscles,the activity of glutathione peroxidase(GPX)in plasma,liver and kidney,the mRNA expression levels of Gpx4,selenoprotein(Seleno)h and Selenou in liver,Selenop and Selenoh in kidney,and the protein expression levels of GPX4 in the liver and kidney of broilers were affected(P<0.05)by supplemental Se level,and increased quadratically(P<0.05)with the increase of supplemental Se level.The estimates of optimal dietary Se levels were 0.10 to 0.49 mg/kg based on the fitted broken-line or asymptotic models(P<0.0001)of the above Se concentration indices,and 0.08 to 0.37 mg/kg based on the fitted brokenline,quadratic or asymptotic models(P<0.007)of the above selenoprotein expression indices.These results indicate that the optimal dietary Se levels would be 0.49 mg/kg to support the maximum Se concentrations and 0.37 mg/kg to support the full expression of selenoproteins in plasma and various tissues of broilers fed a corn-soybean meal diet from 22 to 42 d of age.

紫花苜蓿、白三叶硒蛋白的提取方法筛选及工艺优化

硒蛋白是微量元素硒(Se)在生物体内发挥生物学作用的主要形式,对宿主在抗氧化、抗炎、提高免疫力等方面有重要意义。为探究不同豆科牧草硒蛋白提取方法筛选及其工艺优化,本研究以紫花苜蓿(Medicago sativa)和白三叶(Trifolium repens)为原材料,采用碱提法(NaOH)、盐提法(NaCl)、酸提法(HCl)和水提法(H2O)4种溶剂提取法获得牧草硒蛋白,并在单因素试验基础上进行正交试验优化硒蛋白提取工艺。结果表明:碱提法提取紫花苜蓿和白三叶硒蛋白效果最好。紫花苜蓿最佳工艺条件为温度40℃、料液比1∶20 g·mL^(-1)、碱浓度0.15 mol·L^(-1),硒蛋白提取率为35.39%。白三叶最佳工艺条件为温度50℃、料液比1∶40 g·mL^(-1)、碱浓度0.15 mol·L^(-1),硒蛋白提取率为35.52%。本研究可为从豆科牧草中提取硒蛋白提供重要的技术支持和实践指导。