Copper in the silk formation process of Bombyx mori silkworm

Evidence is presented here that cupric ions play a part in the natural spinning of Bombyx mori silk. Proton induced X-ray emission studies revealed that the copper content increased from the posterior part to the anterior part of silk gland, and then further increased in the silk fiber. Spectrophotometric analysis demonstrated that cupric ions formed coordination complexes with silk fibroin chains while Raman spectroscopy indicated that they induced a conformation transition from random coil/helix to beta-sheet. Taken together these findings indicate that copper could play a role in the natural spinning process in silkworms.     

前列环素参与低氧,高二氧化碳脑血管张力调节

本工作是在初生小牛基底动脉血管条上,用前列环素合成酶抑制剂—消炎痛（Ｉｎｄｏｍｅｔｈａｃｉｎ）研究前列环素及内皮细胞在低氧高二氧化碳脑血管扩张机制中的作用。实验结果表明,消炎痛对常氧下脑血管张力没有影响,但可抑制低氧高二氧化碳引起的脑血管扩张反应。去除内皮细胞后低氧、高二氧化碳扩张脑血管的作用显著减小,此时再给予消炎痛对血管张力无明显作用。由此提示,前列环素和内皮细胞参与低氧,高二氧化碳的脑血管扩张作用,而前列环素是来源于内皮细胞。     

用小鼠模型分析可溶性表达结核分枝杆菌Ag85A的免疫原性

【目的】可溶性表达结核分枝杆菌Ag85A蛋白,并评价其免疫原性。【方法】利用冷休克表达质粒和含有伴侣质粒的大肠杆菌对Ag85A蛋白进行可溶性原核表达,并进行纯化与鉴定,通过C57BL/6小鼠模型对Ag85A蛋白的免疫原性,包括诱导机体特异性体液免疫应答和细胞免疫应答水平进行分析。【结果】重组菌诱导后裂解上清中检测到可溶性Ag85A蛋白的表达,经过亲和层析纯化收获了纯度在90%以上的Ag85A蛋白,Western blot鉴定显示其具有较好的免疫反应性。Ag85A蛋白免疫小鼠后,血清中可以检测到高水平的Ig G抗体效价,其中Ig G2b水平要高于Ig G1。通过特异性多肽、蛋白刺激脾脏和腹股沟淋巴结细胞可分泌高水平的IFN-γ、TNF-α等Th1型细胞因子。【结论】实现了Ag85A蛋白的可溶性表达,免疫特性评价显示Ag85A蛋白可诱导机体产生强烈的特异性体液免疫应答及Th1型的细胞免疫应答,从而为其进一步免疫学功能的研究奠定了重要基础。     

Highly efficient antibacterial diblock copolypeptides based on lysine and phenylalanine

A series of amphiphilic diblock copolypeptides (K₃₀‐b ‐F₁₅, K₃₀‐b ‐F₃₀, and K₃₀‐b ‐F₄₅) were synthesized via N ‐carboxy‐α‐amino‐anhydride ring‐opening polymerization. The copolypeptides had excellent antibacterial efficacy to both Gram positive (S. aureus ) and Gram negative (E. coli ) bacteria. The minimum inhibitory concentrations (MICs) against E. coli and S. aureus are 8 μg mL^?1 and 2 μg mL^?1, respectively, lower than most natural and artificial antimicrobial peptides (AMPs). The morphological changes of the bacteria treated with diblock copolypeptides were investigated by transmission electron microscopy; the results proved that the diblock copolypeptides had a similar antibacterial pore‐forming mechanism to natural cationic peptides. This was confirmed by laser scanning confocal microscope images. CCK‐8 results and the MICs showed that the diblock copolypeptides have high selectivity to bacteria, which suggested that the diblock copolypeptides could be excellent candidates to replace traditional antibiotics in future.     

降水格局变化对红砂幼苗生长的影响

以西北荒漠生态系统典型植物红砂(Reaumuria soongorica)一年生幼苗为研究对象,利用人工遮雨装置,设置3个降水量梯度(W-、W、W+)和2个降水间隔时间梯度(T、T+)进行模拟试验,研究了不同降水格局下红砂幼苗生长、生物量积累和分配的变化特征。结果表明:(1)降水量增加30%,幼苗株高和基径分别平均增加22.0%和28.0%,延长降水间隔时间其作用更显著,分别平均增加24.57%和32.98%(P0.05);(2)在延长降水间隔时间的同时增加降水量,幼苗地上、地下和总生物量分别显著增加了241.57%、223.95%和236.72%(P0.05),幼苗地上部分的生长优于地下部分;(3)与对照相比,降水量减少30%,幼苗根长平均增加21.0%,根冠比平均显著增加53.73%(P0.05),而各部分生物量差异不显著。     

人体股骨弹性模量与骨矿含量的关系

选取正常男性成人股骨18段,制成5-20mm测试块202个,用Ⅱ型γ线骨矿分析仪测得骨矿含量面密度分别为1.324-1.901g/cm2,再用WE-10(A)型液压式万能试验机和千分表测得测试块受纵向压应力时所承受的压力及相应的高度变化并计算其弹性模量。结果显示：骨矿含量在1.802g/cm2以下时,弹性模量及力学性能与骨矿含量呈正相关关系,但超出此范围后,骨矿含量的增加可能会使骨的力学性能下降。     

Elasticity of spider silks

The elasticity of spider MAA silks containing varying proline content was investigated and compared with that of silkworm ( Bombyx mori) silk. For silks with similar breaking strain (suggesting similar molecular order), the elasticity appears to increase with increasing proline content. Particularly, across all spider silks, intra- and interspecies relationships are found between capacity to shrink (Csh) and strain recovery, while only the interspecies relationship is found between Csh and work recovery. Four factors, that is, molecular orientation, crystallinity, amino acid motif, and hydration, are discussed to explain the origin of silk's elasticity. Our study corroborates the view that proline-containing motifs contribute to the elasticity of not only spider silks, but also other bioelastomers.     

结核分枝杆菌Rv2628蛋白的免疫生物学特性

Rv2628蛋白是结核分枝杆菌Mycobacterium tuberculosis(M.tb)DosR调控的潜伏感染相关抗原。本研究对Rv2628蛋白进行了原核表达和纯化,并以巨噬细胞系和小鼠为研究模型,对其免疫生物学特性进行了分析。SDS-PAGE及Western blotting鉴定结果表明,Rv2628-His融合蛋白以包涵体形式表达,能与兔抗H37Rv多抗血清发生特异性反应,具有较好的免疫反应性。与巨噬细胞系RAW264.7的互作实验结果表明,在1–12 h内Rv2628蛋白能诱导前炎性因子IL-6的上调表达。将纯化的Rv2628融合蛋白皮下免疫BALB/c小鼠,夹心ELISA的测定结果表明,Rv2628蛋白免疫组诱导产生的特异性IFN-γ水平显著高于IL-4的水平(P0.000 1),呈现Th1型细胞免疫应答趋势;以Rv262811-30多肽作为包被抗原,通过间接ELISA测定的血清抗体效价能达到11 600,表明Rv2628也能诱导体液免疫应答。总之,Rv2628能促进巨噬细胞炎症反应的发生,激发小鼠产生强烈的Th1型细胞免疫应答和较好的体液免疫应答,具有作为亚单位疫苗的潜力,为M.tb与宿主之间的相互作用奠定了一定的理论基础。