大米小包装储藏过程中脂类及微观结构的变化

【目的】由于胚乳失去保护,大米在储藏过程中易发生陈化、霉变等问题,致使其品质劣变甚至丧失食用价值。通过测定储藏过程中大米游离脂肪酸、总酸含量、脂肪酸组成和含量,观察大米横断面胚乳细胞、淀粉颗粒微观结构,探讨大米品质劣变原因,为大米储藏技术提供参考。【方法】以粳稻99号大米为对象,进行人工模拟储藏试验：采用编织袋、自然密闭缺氧、抽真空3种包装方式,置于温度为15、25和30℃（60%湿度）的人工气候箱中储藏180 d,每个月进行一次品质指标测定;测定大米储藏过程中脂肪酸值、总酸值的变化,利用气相色谱分析脂肪酸组成及含量变化,利用扫描电镜观察大米横断面胚乳细胞形态,探索脂类及横断面胚乳结构导致大米品质陈化的机理及品质劣变后淀粉颗粒微观形态的变化规律。【结果】①储藏过程中,编织袋及自然密闭缺氧包装的大米游离脂肪酸及总酸含量皆呈现急剧上升趋势,当品质劣变严重时两者含量反而下降;抽真空包装的大米游离脂肪酸及总酸含量均保持在较稳定的水平,且储藏温度对其含量影响不显著;②脂肪酸组成中含量最多的是亚油酸、油酸和棕榈酸,这3种脂肪酸含量占总脂肪90%以上。包装方式及储藏温度对各脂肪酸组成影响不同。除了花生酸（C20:0）及二十二烯酸（C22:1）外,其余脂肪酸受包装方式影响较大;而储藏温度仅与豆蔻酸（C14:0）和山嵛酸（C22:0）有显著性关系,对其余脂肪酸影响不大。脂肪酸变化规律符合：高不饱和脂肪酸含量随温度升高而降低,多不饱和脂肪酸与饱和脂肪酸及单不饱和脂肪酸间呈现显著负相关,具体表现为硬脂酸（C18:0）与亚油酸（C18:2）、亚麻酸（C18:3）;油酸（C18:1）与亚油酸、亚麻酸皆呈现明显的“此消彼长”现象。③新鲜大米淀粉粒以复粒形式存在,形状较大,表面有较厚的膜,排列整齐有序,两侧以片状的细胞间断面居多,放射状结构清晰可见。陈化加剧的大米胚乳细胞横断面结构松散无序,细胞内断面多于细胞间断面,横断面上可观测到“小孔”及一些分散在淀粉体周围的蛋白体和脂肪滴;细胞壁的完整性受到破坏致使复粒崩解并可见大量单粒细胞,一部分单淀粉粒形状近圆型,棱角较钝;细胞间的棱角模糊,放射状结构变得模糊甚至消失。【结论】编织袋及自然密闭缺氧包装的大米陈化劣变较为严重,储藏过程中其脂肪酸值、总酸值急剧上升后下降,胚乳表面光滑度变差、小孔数量及表面蛋白质膜的翘起变多,辐射状趋势渐渐消失。抽真空包装可以有效延缓大米品质劣变进程。     

沈阳2次降水过程ANC和TRACER检验分析

随着大城市的不断发展和社会对于气象精细化要求的提高,临近预报特别是突发性灾害天气的临近预报已经成为了社会关注的重点。为了提升短临预报能力,沈阳市气象局先后引进了ANC和TRACER系统,但是由于使用时间较短,之前还没有总结出对于2个系统预报产品的订正技术。本研究通过2013年10月10日与2014年8月24日沈阳2次大雨到暴雨天气过程,总结出ANC和TRACER在短临预报中的不同,ANC的优势更侧重于局地性的强对流天气的预报,而TRACER更有利于相对大范围的、连续性的降水预报。希望研究结果能够给预报员利用ANC和TRACER制作沈阳地区精细化预报预提供订正方法和依据。     

绵羊感染伪狂犬病的病理学观察与病毒分离鉴定

为了确诊1例疑似绵羊伪狂犬病病例,本试验以上海郊区某羊场发病绵羊的病料为研究对象进行了病理学观察、病毒分离和鉴定。病理组织学变化显示,发病羊大脑组织神经元发生广泛性变性、坏死并伴有嗜神经现象,神经元周围出现胶质细胞增生。病料接种BHK-21细胞,细胞出现病变,间接免疫荧光试验和荧光定量PCR检测结果证实所分离的病毒为伪狂犬病病毒。流行病学调查结果表明,绵羊伪狂犬病可能是由猪伪狂犬病病毒感染引起的。通过免疫接种猪伪狂犬病弱毒疫苗,绵羊伪狂犬病疫情得到及时控制。     

稳定高效表达猪CD163的Marc-145细胞系的构建与鉴定

试验旨在构建一株高效表达猪CD163(pCD163)的Marc-145细胞系,为猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus,PRRSV)的临床分离和疫苗生产奠定基础。根据GenBank中序列设计引物从猪肺泡巨噬细胞(PAM)中扩增pCD163基因,将其插入真核表达载体pCI-neo构建真核表达质粒pCI-pCD163,将该重组质粒转染Marc-145细胞,通过G418筛选、单克隆化并扩大培养筛选获得表达pCD163的Marc-145细胞系,IFA、Western blotting鉴定其表达情况。IFA结果显示,构建的pCD163-Marc细胞系中荧光明显亮于普通Marc-145细胞;Western blotting结果显示,pCD163-Marc细胞系中CD163蛋白表达量约为对照Marc-145细胞中CD163蛋白表达量的8.7倍。且该细胞系可稳定传至20代,各代次之间表达量无差异。证明高效表达猪CD163的Marc-145细胞系构建成功。     

雌激素和孕酮对犬子宫内膜基质细胞增殖和孕酮受体表达的影响

本试验应用不同消化分离途径获取犬子宫内膜基质细胞,调节培养液中雌激素(E₂)和孕酮(P₄)的浓度,采用MTT法测定E₂和P₄浓度水平对犬子宫内膜基质细胞体外增殖的影响,利用细胞免疫组织化学法鉴定细胞并测定细胞孕酮受体(PR)表达与激素浓度水平的相关性。结果表明,E₂浓度变化(15、30、100 pg/mL)对犬子宫内膜基质细胞的增殖和PR的表达均没有显著的调节作用(P>0.05);P₄(15、30 ng/mL)对犬子宫内膜基质细胞的增殖有显著促进作用(P<0.05),P₄(3、15、30 ng/mL)对犬子宫内膜基质细胞PR的表达具有显著的抑制作用(P<0.05),其影响程度与浓度和作用时间关系密切。     

BRCA1基因多态性及其与奶牛乳房炎抗性的相关性研究

为了研究BRCA1基因突变与荷斯坦奶牛体细胞数和体细胞评分的关系,试验通过对BRCA1基因外显子13、14进行克隆、序列比对和挖掘已有突变的方法确定该基因的多态位点,采用SNaPshot技术检测了BRCA1基因25025 T>A和46126 G>T突变位点在北京郊区荷斯坦奶牛群体中的分布,并对突变位点与体细胞数和体细胞评分进行了关联分析。结果表明,荷斯坦奶牛BRCA1基因2个位点均检测到3种基因型,其中25025 bp位点TT基因型为优势基因型,46126 bp位点GT基因型为优势基因型。25025 bp位点AA基因型个体体细胞数(P<0.05)和体细胞评分(P<0.01)都显著低于TT和TA基因型;46126 bp位点TT基因型个体体细胞数显著低于GG和GT基因型个体(P<0.05),但3种基因型个体体细胞评分无显著差异(P>0.05)。本研究结果初步表明,BRCA1基因25025和46126 bp位点可作为中国荷斯坦牛乳房炎抗性的标记辅助选择。     

Heparanase and Syndecan-4 Are Involved in Low Molecular Weight Fucoidan-Induced Angiogenesis

Induction of angiogenesis is a potential treatment for chronic ischemia. Low molecular weight fucoidan (LMWF), the sulfated polysaccharide from brown seaweeds, has been shown to promote revascularization in a rat limb ischemia, increasing angiogenesis in vivo. We investigated the potential role of two heparan sulfate (HS) metabolism enzymes, exostosin-2 (EXT2) and heparanase (HPSE), and of two HS-membrane proteoglycans, syndecan-1 and -4 (SDC-1 and SDC-4), in LMWF induced angiogenesis. Our results showed that LMWF increases human vascular endothelial cell (HUVEC) migration and angiogenesis in vitro. We report that the expression and activity of the HS-degrading HPSE was increased after LMWF treatment. The phenotypic tests of LMWF-treated and EXT2- or HPSE-siRNA-transfected cells indicated that EXT2 or HPSE expression significantly affect the proangiogenic potential of LMWF. In addition, LMWF increased SDC-1, but decreased SDC-4 expressions. The effect of LMWF depends on SDC-4 expression. Silencing EXT2 or HPSE leads to an increased expression of SDC-4, providing the evidence that EXT2 and HPSE regulate the SDC-4 expression. Altogether, these data indicate that EXT2, HPSE, and SDC-4 are involved in the proangiogenic effects of LMWF, suggesting that the HS metabolism changes linked to LMWF-induced angiogenesis offer the opportunity for new therapeutic strategies of ischemic diseases.     

Dihydroaustrasulfone Alcohol Inhibits PDGF-Induced Proliferation and Migration of Human Aortic Smooth Muscle Cells through Inhibition of the Cell Cycle

Dihydroaustrasulfone alcohol is the synthetic precursor of austrasulfone, which is a marine natural product, isolated from the Taiwanese soft coral Cladiella australis. Dihydroaustrasulfone alcohol has anti-inflammatory, neuroprotective, antitumor and anti-atherogenic properties. Although dihydroaustrasulfone alcohol has been shown to inhibit neointima formation, its effect on human vascular smooth muscle cells (VSMCs) has not been elucidated. We examined the effects and the mechanisms of action of dihydroaustrasulfone alcohol on proliferation, migration and phenotypic modulation of human aortic smooth muscle cells (HASMCs). Dihydroaustrasulfone alcohol significantly inhibited proliferation, DNA synthesis and migration of HASMCs, without inducing cell death. Dihydroaustrasulfone alcohol also inhibited platelet-derived growth factor (PDGF)-induced expression of cyclin-dependent kinases (CDK) 2, CDK4, cyclin D1 and cyclin E. In addition, dihydroaustrasulfone alcohol inhibited PDGF-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), whereas it had no effect on the phosphorylation of phosphatidylinositol 3-kinase (PI3K)/(Akt). Moreover, treatment with PD98059, a highly selective ERK inhibitor, blocked PDGF-induced upregulation of cyclin D1 and cyclin E and downregulation of p27^kip1. Furthermore, dihydroaustrasulfone alcohol also inhibits VSMC synthetic phenotype formation induced by PDGF. For in vivo studies, dihydroaustrasulfone alcohol decreased smooth muscle cell proliferation in a rat model of restenosis induced by balloon injury. Immunohistochemical staining showed that dihydroaustrasulfone alcohol noticeably decreased the expression of proliferating cell nuclear antigen (PCNA) and altered VSMC phenotype from a synthetic to contractile state. Our findings provide important insights into the mechanisms underlying the vasoprotective actions of dihydroaustrasulfone alcohol and suggest that it may be a useful therapeutic agent for the treatment of vascular occlusive disease.     

Morphological and Proteomic Analyses Reveal that Unsaturated Guluronate Oligosaccharide Modulates Multiple Functional Pathways in Murine Macrophage RAW264.7 Cells

Alginate is a natural polysaccharide extracted from various species of marine brown algae. Alginate-derived guluronate oligosaccharide (GOS) obtained by enzymatic depolymerization has various pharmacological functions. Previous studies have demonstrated that GOS can trigger the production of inducible nitric oxide synthase (iNOS)/nitric oxide (NO), reactive oxygen species (ROS) and tumor necrosis factor (TNF)-α by macrophages and that it is involved in the nuclear factor (NF)-κB and mitogen-activated protein (MAP) kinase signaling pathways. To expand upon the current knowledge regarding the molecular mechanisms associated with the GOS-induced immune response in macrophages, comparative proteomic analysis was employed together with two-dimensional electrophoresis (2-DE), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) and Western blot verification. Proteins showing significant differences in expression in GOS-treated cells were categorized into multiple functional pathways, including the NF-κB signaling pathway and pathways involved in inflammation, antioxidant activity, glycolysis, cytoskeletal processes and translational elongation. Moreover, GOS-stimulated changes in the morphologies and actin cytoskeleton organization of RAW264.7 cells were also investigated as possible adaptations to GOS. This study is the first to reveal GOS as a promising agent that can modulate the proper balance between the pro- and anti-inflammatory immune responses, and it provides new insights into pharmaceutical applications of polysaccharides.