陶瓷膜超滤纯化香菇多糖及其相对分子质量的测定

采用截留分子量为104u的陶瓷超滤膜纯化香菇多糖溶液,考察运行时间、跨膜压差（TMP）、稀释倍数和操作温度对膜通量的影响,分析各条件下稳定通量的变化规律。结果表明：实验设备运行1 h后膜管通量开始稳定,当跨膜压差为0.08 MPa、料液稀释倍数为3倍、操作温度50℃时,稳定通量维持在75 L/（h·m2）。通过超滤纯化制得的香菇多糖的纯度为89.7%,高效凝胶渗透色谱法测得平均相对分子量为2.27×106u,并对所得香菇多糖的光谱学性质进行了研究。     

Functional Analysis of Lysosomes During Mouse Preimplantation Embryo Development

Lysosomes are acidic and highly dynamic organelles that are essential for macromolecule degradation and many other cellular functions. However, little is known about lysosomal function during early embryogenesis. Here, we found that the number of lysosomes increased after fertilization. Lysosomes were abundant during mouse preimplantation development until the morula stage, but their numbers decreased slightly in blastocysts. Consistently, the protein expression level of mature cathepsins B and D was high from the one-cell to morula stages but low in the blastocyst stage. One-cell embryos injected with siRNAs targeted to both lysosome-associated membrane protein 1 and 2 (LAMP1 and LAMP2) were developmentally arrested at the two-cell stage. Pharmacological inhibition of lysosomes also caused developmental retardation, resulting in accumulation of lipofuscin. Our findings highlight the functional changes in lysosomes in mouse preimplantation embryos.     

高铜对肉鸡原代肝细胞周期及细胞膜电位的影响

通过流式细胞仪测定各组的细胞周期及细胞膜电位,研究高铜对肉鸡原代肝细胞凋亡的影响。将全量换液24h后的细胞分为空白对照组和低铜组（10μmol/L Cu2＋组）、高铜Ⅰ组（50μmol/L Cu2＋组）、高铜Ⅱ组（100μmol/L Cu2＋组）,培养48h后测定荧光值,结果表明,高铜组能显著引起静止期（G0/G1）肝细胞数增多、增殖期（S、G2＋M）肝细胞数减少、细胞膜电位下降（P〈0.05）;低铜组未出现明显变化;表明高浓度的铜能明显改变肝细胞的细胞周期及细胞膜电位。     

不同抗寒性冬小麦叶鞘质膜的稳定性表现

为了解叶鞘质膜稳定性与小麦抗寒性的关系,以返青率不同的4个冬小麦品种(系)为材料,研究寒地冬小麦越冬期叶鞘质膜稳定性变化及其影响因素。结果表明,低温下,冬小麦叶鞘相对电导率与自由水和总水分含量呈显著正相关,丙二醛含量与SOD和POD活性、AsA含量呈显著正相关;封冻后,抗寒性强的冬麦品种(系)的SOD活性和GSH含量显著高于抗寒性弱的品种(系)。在深度封冻期保持叶鞘质膜稳定性有助于增强冬小麦抗寒性。     

Anti-Microbial,Anti-Biofilm Activities and Cell Selectivity of the NRC-16 Peptide Derived from Witch Flounder,Glyptocephalus cynoglossus

Previous studies had identified novel antimicrobial peptides derived from witch flounder. In this work, we extended the search for the activity of peptide that showed antibacterial activity on clinically isolated bacterial cells and bacterial biofilm. Pseudomonas aeruginosa was obtained from otitis media and cholelithiasis patients, while Staphylococcus aureus was isolated from otitis media patients. We found that synthetic peptide NRC-16 displays antimicrobial activity and is not sensitive to salt during its bactericidal activity. Interestingly, this peptide also led to significant inhibition of biofilm formation at a concentration of 4–16 μM. NRC-16 peptide is able to block biofilm formation at concentrations just above its minimum inhibitory concentration while conventional antibiotics did not inhibit the biofilm formation except ciprofloxacin and piperacillin. It did not cause significant lysis of human RBC, and is not cytotoxic to HaCaT cells and RAW264.7 cells, thereby indicating its selective antimicrobial activity. In addition, the peptide’s binding and permeation activities were assessed by tryptophan fluorescence, calcein leakage and circular dichroism using model mammalian membranes composed of phosphatidylcholine (PC), PC/cholesterol (CH) and PC/sphingomyelin (SM). These experiments confirmed that NRC-16 does not interact with any of the liposomes but the control peptide melittin did. Taken together, we found that NRC-16 has potent antimicrobial and antibiofilm activities with less cytotoxicity, and thus can be considered for treatment of microbial infection in the future.     

Influence of Lipid A Acylation Pattern on Membrane Permeability and Innate Immune Stimulation

Lipid A, the hydrophobic anchor of lipopolysaccharide (LPS), is an essential component in the outer membrane of Gram-negative bacteria. It can stimulate the innate immune system via Toll-like receptor 4/myeloid differentiation factor 2 (TLR4/MD2), leading to the release of inflammatory cytokines. In this study, six Escherichia coli strains which can produce lipid A with different acylation patterns were constructed; the influence of lipid A acylation pattern on the membrane permeability and innate immune stimulation has been systematically investigated. The lipid A species were isolated and identified by matrix assisted laser ionization desorption-time of flight/tandem mass spectrometry. N-Phenyl naphthylamine uptake assay and antibiotic susceptibility test showed that membrane permeability of these strains were different. The lower the number of acyl chains in lipid A, the stronger the membrane permeability. LPS purified from these strains were used to stimulate human or mouse macrophage cells, and different levels of cytokines were induced. Compared with wild type hexa-acylated LPS, penta-acylated, tetra-acylated and tri-acylated LPS induced lower levels of cytokines. These results suggest that the lipid A acylation pattern influences both the bacterial membrane permeability and innate immune stimulation. The results would be useful for redesigning the bacterial membrane structure and for developing lipid A vaccine adjuvant.     

Glaucoma associated with uveal cysts and goniodysgenesis in American Bulldogs: a case series

We present a series of three American Bulldogs with clinical signs of glaucoma and intraocular inflammation accompanied by bilateral uveal cysts and abnormal gonioscopic findings. All dogs proved refractory to medical management and were enucleated. Histopathologic findings were similar in all three and included significant preiridal fibrovascular membranes and mononuclear inflammatory infiltrates in the anterior uvea. On microscopic evaluation, cysts appeared to arise primarily from the ciliary body and iridociliary sulcus, with smaller cysts also budding from the posterior iris. Pigment dispersion was variable but consistent, involving deposition of a small number of pigment‐laden cells in the dependent trabecular meshwork. Cataract formation was not noted. Glaucoma associated with uveal cysts has been described previously in Golden Retrievers and Great Danes, although clinical and histopathologic findings in those breeds are not identical to those described here. American Bulldogs with uveal cysts should have gonioscopy performed and should be monitored carefully for signs of increased intraocular pressure and intraocular inflammation. Furthermore, documentation of cyst‐associated glaucoma in a third breed suggests clinicians should exercise caution in dismissing uveal cysts in dogs as incidental findings.     

副鸡禽杆菌A、B、C 3个血清型菌株外膜蛋白的差异分析

为了探索不同血清型副鸡禽杆菌菌株外膜蛋白的差异,本试验采用FOCUSTM Global Fractionation试剂盒制备副鸡禽杆菌A(221株)、B(0222株)、C(Modesto株)3个血清型参考菌株的外膜蛋白,进行SDS-PAGE凝胶电泳。结果表明,不同血清型参考菌株的电泳图谱相似,经凝胶定量软件分析,结果显示,主要条带均有7个,其分子质量相似,分别占A、B和C蛋白质总量的70.85%、68.6%和65.71%。此外共有3个蛋白质条带分子质量相似,但蛋白质含量差异显著(P<0.05)。本试验为副鸡禽杆菌外膜蛋白的进一步研究提供了理论依据。     

荧光增白剂对Cry1Ac抗感棉铃虫围食膜的影响及增效作用

为了提高Bt的杀虫活性,运用扫描电镜、SDS-PAGE电泳和生物测定技术,研究了荧光增白剂FB28对棉铃虫Cry1Ac抗性和敏感品系围食膜的影响及对Cry1Ac杀虫蛋白的增效作用。结果表明,正常棉铃虫围食膜表面光滑致密,没有空洞和缝隙。用含1%FB28的人工饲料饲喂刚蜕皮的5龄棉铃虫幼虫2 h后,抗感棉铃虫围食膜表面均出现许多空洞,且敏感棉铃虫的空洞明显大于抗性棉铃虫;随着处理时间的延长,围食膜上的空洞逐渐变小,13 h后恢复正常。用1%FB28离体或活体处理抗、感品系棉铃虫,均可造成围食膜蛋白被降解。用1%FB28与Cry1Ac杀虫蛋白混合饲喂抗、感棉铃虫初孵幼虫,可明显提高棉铃虫的死亡率,且对抗性品系的增效作用明显大于敏感品系,对敏感和抗性品系棉铃虫的增效比分别为2.23和9.34;1%FB28还可以明显增加对抗、感品系3龄棉铃虫幼虫的生长抑制作用。