膜分离技术在茶业中的应用现状及展望

膜分离技术在食品加工中的应用已非常普遍并日趋成熟,现代茶叶深加工,尤其是速溶茶及茶饮料的生产更是离不开膜技术。本文对膜分离技术及其在食品加工中的应用进行了概述,重点阐述了微滤、超滤、纳滤、反渗透及其集成技术在茶叶加工中的研究现状及存在的不足,并指出了其未来的发展趋势。     

橡胶树乳管HbPMP1基因的克隆与表达分析

过氧化物酶体膜蛋白PMP是ABC转运蛋白ABCD亚家族蛋白之一,存在于过氧化物酶体膜上。研究表明,拟南芥中的ABCD亚家族ABC转运蛋白AtABCD1主要通过参与部分物质运输进入过氧化物酶体,其中包括茉莉酸合成的前体 OPDA。本研究通过RACE技术克隆了一个ABCD亚家族ABC转运蛋白基因HbPMP1,并进行表达分析。结果表明：HbPMP1全长4 011 bp,编码1 337个氨基酸残基,其表达产物与拟南芥AtABCD1有较高的相似性(氨基酸一致性为78%);该基因在伤害及外源茉莉酸诱导下     

大菱鲆致病性溶藻弧菌SR1的外膜蛋白及其抗原性分析

用十二烷基肌氨酸钠(Sarkosyl)抽提结合超速离心的方法提取了一株大菱鲆致病性溶藻弧菌(Vibrio alginolyticus)SR1和其他7株弧菌的外膜蛋白。通过SDS-PAGE图谱分析比较了这8株弧菌外膜蛋白的组成,结果表明,8株弧菌的外膜蛋白电泳一般可得到6-12条条带,其分子量多集中在65-106 kD和28-48 kD,其中36 kD的蛋白带为8株弧菌所共有。用兔抗SR1全菌血清进行Western-blot印迹显示,菌株SR1的外膜蛋白条带中有6条发生了阳性反应,其分子量分别为73 kD、48 kD4、5 kD3、9 kD、36 kD和32 kD。而其他7株弧菌的外膜蛋白与兔抗SR1血清也发生程度不等的阳性反应,这些阳性反应条带的分子量集中在65-73 kD、45-48 kD和36-41 kD之间,其中36 kD的外膜蛋白在8株弧菌中均出现明显的阳性反应,说明36 kD的外膜蛋白是这8株弧菌共有的特异性抗原。     

热处理对低温胁迫下黄瓜活性氧代谢和膜脂组分的影响

为探讨热处理减轻黄瓜果实低温冷害的作用机理,本试验研究了47℃热水浸泡5 min处理对黄瓜果实在4℃贮藏期间活性氧代谢和膜脂组分的影响。结果表明,47℃热水5 min处理可显著抑制黄瓜果实冷害的发生,贮藏15 d后果实冷害指数较对照(CK)低20.87%。此外,热处理还可抑制黄瓜相对电导率及丙二醛(MDA)含量的上升,提高黄瓜果实超氧化物歧化酶(SOD)、过氧化物酶(DOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)的活性,抑制超氧阴离子($\mathop{{O}}_{2}^{{\mathop{}_{\ ·}^{-}}}$)及过氧化氢(H₂O₂)的产生,同时降低脂氧合酶的活性,保持较低的饱和脂肪酸含量、较高的不饱和脂肪酸含量和膜脂不饱和度。综上,热处理可维持黄瓜果实活性氧代谢的平衡,抑制膜脂的过氧化作用,从而提高黄瓜果实的抗冷性,减轻果实冷害损伤。     

Effect of Fucoidan on the Mitochondrial Membrane Potential (ΔΨm) of Leukocytes from Patients with Active COVID-19 and Subjects That Recovered from SARS-CoV-2 Infection

Fucoidan is a polysaccharide obtained from marine brown algae, with anti-inflammatory, anti-viral, and immune-enhancing properties, thus, fucoidan may be used as an alternative treatment (complementary to prescribed medical therapy) for COVID-19 recovery. This work aimed to determine the ex-vivo effects of treatment with fucoidan (20 µg/mL) on mitochondrial membrane potential (ΔΨm, using a cationic cyanine dye, 3,3′-dihexyloxacarbocyanine iodide (DiOC₆(3)) on human peripheral blood mononuclear cells (HPBMC) isolated from healthy control (HC) subjects, COVID-19 patients (C-19), and subjects that recently recovered from COVID-19 (R1, 40 ± 13 days after infection). In addition, ex-vivo treatment with fucoidan (20 and 50 µg/mL) was evaluated on ΔΨm loss induced by carbonyl cyanide 3-chlorophenylhydrazone (CCCP, 150 µM) in HPBMC isolated from healthy subjects (H) and recovered subjects at 11 months post-COVID-19 (R2, 335 ± 20 days after infection). Data indicate that SARS-CoV-2 infection induces HPBMC loss of ΔΨm, even 11 months after infection, however, fucoidan promotes recovery of ΔΨm in PBMCs from COVID-19 recovered subjects. Therefore, fucoidan may be a potential treatment to diminish long-term sequelae from COVID-19, using mitochondria as a therapeutic target for the recovery of cellular homeostasis.     

脂肪细胞膜抗血清对猪胴体品质和肉品质的影响

将36头5周龄的断奶上海大白猪随机分成6组.对照组C1和C2、皮下免疫试验组S1和S2、腹腔免疫试验组A1和A2,每组6头猪.试验周期为11周和17周.试验组A1和A2腹腔注射5.0 ml/kg BW山羊抗猪脂肪细胞膜抗血清,试验组S1和S2皮下注射5.0 ml/kg BW山羊抗猪脂肪细胞膜抗血清,对照组C1和C2以相同剂量注射正常山羊血清.11周末和17周末屠宰结果显示:①各试验组猪板油重和背膘厚都显著低于对照组(P＜0.05);11周末,与对照组相比,试验组S1和A1中猪眼肌面积均显著升高;17周末,腹腔免疫组猪眼肌面积显著高于对照组(P＜0.05).②11周末,腹腔免疫组猪半腱肌和里脊、皮下免疫组猪背最长肌和里脊中脂肪含量均明显低于对照组(P＜0.05);17周末,与对照组相比,腹腔免疫组猪半腱肌中脂肪含量显著下降(P＜0.05).③11周末,腹腔免疫组猪背最长肌和里脊中蛋白质含量显著高于对照组(P＜0.05);17周末,各试验组背最长肌和里脊中蛋白质含量与腹腔免疫组半腱肌中蛋白质含量均显著高于对照组(P＜0.05).表明,山羊抗猪脂肪细胞膜被动免疫具有较好改善猪胴体品质和肉品质的作用.     

Plasma membrane of trout spermatozoa: I. Isolation and partial characterization

The plasma membrane from spermatozoa of rainbow trout was isolated by four techniques: sonication, hypotonic shock, mechanical homogenization after freeze-thawing, and nitrogen cavitation, in combination with continuous sucrose gradient centrifugation. Nitrogen cavitation (900 PSI, 20 min equilibration at 4°C) was the most effective technique.Following nitrogen cavitation, four bands were recovered in the sucrose gradient at densities 1.03, 1.05, 1.09 and 1.15 g/ml. Electron microscopy revealed membrane vesicles of various sizes in bands 1 to 3, while enzyme analysis revealed a 3.9 to 5.5-fold enrichment in 5'-nucleotidase and little contamination by lactate dehydrogenase (cytosol) and succinic dehydrogenase (mitochondria). Lipid analysis of bands 1 and 2 indicated a 6 to 7-fold enrichment in cholesterol and a cholesterol: phospholipid ratio of 0.59–0.70. Seven classes of phospholipids were present in bands 1–3 with no significant differences observed among bands. These data indicate that the vesicles (in bands 1 and 2) obtained after nitrogen cavitation are primarily plasma membranes. Membranes in band 3 appear to be slightly contaminated with nuclear membranes.Most of the plasma membrane proteins were acidic to neutral. The 2 main membrane proteins were 42 and 30 Kilodaltons.     

Determination of Moisture Deficit and Heat Stress Tolerance in Corn Using Physiological Measurements and a Low‐Cost Microcontroller‐Based Monitoring System

In the southern United States, corn production encounters moisture deficit coupled with high‐temperature stress, particularly during the reproductive stage of the plant. In evaluating plants for environmental stress tolerance, it is important to monitor changes in their physical environment under natural conditions, especially when there are multiple stress factors, and integrate this information with their physiological responses. A low‐cost microcontroller‐based monitoring system was developed to automate measurement of canopy, soil and air temperatures, and soil moisture status in field plots. The purpose of this study was to examine how this system, in combination with physiological measurements, could assist in detecting differences among corn genotypes in response to moisture deficit and heat stress. Three commercial hybrids and two inbred germplasm lines were grown in the field under irrigated and non‐irrigated conditions. Leaf water potential, photosynthetic pigments, cell membrane thermostability (CMT) and maximum quantum efficiency of photosystem II (Fv/Fm) were determined on these genotypes under field and greenhouse conditions. Variations observed in air and soil temperatures, and soil moisture in plots of the individual corn genotypes helped explain their differences in canopy temperature (CT), and these variations were reflected in the physiological responses. One of the commercial hybrids, having the lowest CT and the highest CMT, was the most tolerant among the genotypes under moisture deficit and heat stress conditions. These results demonstrated that the low‐cost microcontroller‐based monitoring system, in combination with physiological measurements, was effective in evaluating corn genotypes for drought and heat stress tolerance.     

聚乙烯醇共混改性膜作为农药种衣剂成膜剂的性能研究

以水溶性聚合物聚乙烯醇(PVA)和水不溶性聚合物乙酸乙烯-乙烯共聚物(VAE)乳液为原料,采用溶液共混法制备了PVA-VAE共混膜,为农药成膜剂的制备开辟了新途径。红外光谱、透射电镜、激光粒度仪测试结果显示,PVA溶液中的胶束被打开,体系的比表面积急剧增大,两相间的界面消失,说明共混体系分子间具有良好的相容性;透水性与耐水性测定结果表明,PVA-VAE的质量比为80∶ 20、70∶ 30、60∶ 40时其共混膜的性能适用于农药种衣剂的成膜剂;种子发芽试验显示,与单独使用PVA膜相比,引入适当比例VAE后的共混膜用于种子包衣,其耐水性显著提高,渗水率适宜,对种子发芽无明显影响。     

猪肺炎支原体膜蛋白P46基因在大肠杆菌中的表达

把猪肺炎支原体(Mycoplasma hyopneumoniae)国际标准株232的P46基因克隆进pGEM-T-EASY载体上,通过PCR方法把该基因中三个编码Trp的密码子TGA突变为TGG,然后将该基因亚克隆到载体pMAL-P2X上,得到重组表达载体pMAL-P2X-P46.用该重组载体转化大肠杆菌TB1,得到表达重组菌TB1-pMAL-P2XA-P46,用终浓度为0.3 mM的IPTG在37℃下诱导表达,获得可溶性表达的融合蛋白MBP-P46,在免疫印迹试验中,兔抗MBP高免血清和兔抗猪肺炎支原体高免血清都能与目的蛋白发生阳性反应,证明猪肺炎支原体P46基因在大肠杆菌里获得了可溶性表达.该融合蛋白对于建立特异性和敏感性好的EIISSA方法具有重要意义.