A plant-based expression system for matching cDNA clones and isozymes

Isozymes of barley α-amylase were matched to cDNAs that encode them using transient expression in oat aleurone layers. Four cDNAs, including two that are previously unpublished, were inserted into oat aleurone cells by microparticle bombardment. The cDNAs were under the control of theAct1 promoter of rice. Expression levels were sufficient for in-gel detection of enzyme activity following isoelectric focusing of aleurone homogenates. The system has also proved useful in characterizing a hybrid β-glucanase gene.     

mRNA accumulation and promoter activity of the gene coding for a hydroxyproline-rich glycoprotein in Oryza sativa

The accumulation of the mRNA corresponding to the gene coding for a hydroxyproline-rich glycoprotein has been studies in rice. The patterns of gene expression obtained are similar to those observed in maize in regions rich in dividing cells such as the meristematic zones of roots. However, the gene does not seem to be induced by wounding as it is the case in maize. This effect is correlated with the absence of sequences present in the promoter of the maize gene and that have been described as responsible for ethylene induction on other plant systems. Instead, the promoter has a sequence that corresponds to abscisic acid-responsive elements and, in fact, HRGP mRNA levels can be two-fold increased in rice leaves by ABA. The genes coding for homologous proteins in two cereal species such as maize and rice appear, therefore, to have distinct mechanisms of gene regulation.     

Involvement of platelet glycoprotein Ib in platelet microparticle mediated neutrophil activation

Summary Platelet microparticles (MPs) are membrane vesicles shed by platelets after activation, and carry antigens characteristic of intact platelets, such as glycoprotein (GP) IIb/IIIa, GPIb and P-selectin. Elevated platelet MPs have been observed in many disorders in which platelet activation is documented. Recently, platelet GPIb has been implicated in the mediation of platelet–leukocyte interaction via binding to its ligand Mac-1 on leukocyte. The role of GPIb for mediating adhesion-activation interactions between platelet MPs and leukocytes has not been clarified. In this study we investigate the role of GPIb in the interplay between platelet MPs and neutrophils. Platelet MPs were obtained from collagen-stimulated platelet-rich plasma (PRP). In a study model of neutrophil aggregation, platelet MPs can serve a bridge to support neutrophil aggregation under venous level shear stress, suggesting that platelet MPs may enhance leukocyte aggregation, which would bear clinical relevance in diseases where the platelet MPs are elevated. The level of aggregation can be reduced by GPIb blocking antibodies, AP1 and SZ2, but not by anti-CD18 mAb. The GPIb blocking antibodies also decreased platelet MP-mediated neutrophil activation, including β2 integrin expression, adherence-dependent superoxide release and platelet MP-mediated neutrophil adherence to immobilized fibrinogen. Our data provide the evidence for the involvement of GPIb–Mac-1 interaction in the cross-talk between platelet MPs and neutrophils.     

Amylosucrase‐mediated β‐carotene encapsulation in amylose microparticles

The β‐carotene embedded amylose microparticles (BC‐AmMPs) were prepared in one‐step by utilizing the unique catalytic activity of amylosucrase from Deinococcus geothermalis (DgAS), which synthesizes linear amylose chains using sucrose as the sole substrate. Synthesized amylose chains self‐assembled with β‐carotene to form well‐defined spherical microparticles with an encapsulation yield of 65%. The BC‐AmMPs produced (average diameter ～8 µm) were bright orange due to the embedded β‐carotene, and this was confirmed by Raman analysis. XRD showed BC‐AmMPs had a B‐type amylose crystal structure with a degree of crystallinity lower than that of AmMPs. This lower crystallinity of AmMP after BC encapsulation was confirmed by DSC analysis. Decreased enthalpy of gelatinization (ΔH_gel) of BC‐AmMP implied that molecular order within the amylose microstructure was influenced by the presence of BC. The stability of BC against environmental stresses, such as UV light and oxidative stress, was significantly enhanced by its encapsulation. The authors propose a new approach to the preparation of an amylose based carrier system for active compounds or expensive food ingredients with poor stabilities during storage or processing. Given that amylose is a safe food material, the devised encapsulation system will find wide range of practical applications in the food industry. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1640–1646, 2017     

An optimized magnetite microparticle-based phosphopeptide enrichment strategy for identifying multiple phosphorylation sites in an immunoprecipitated protein

To further improve the selectivity and throughput of phosphopeptide analysis for the samples from real-time cell lysates, here we demonstrate a highly efficient method for phosphopeptide enrichment via newly synthesized magnetite microparticles and the concurrent mass spectrometric analysis. The magnetite microparticles show excellent magnetic responsivity and redispersibility for a quick enrichment of those phosphopeptides in solution. The selectivity and sensitivity of magnetite microparticles in phosphopeptide enrichment are first evaluated by a known mixture containing both phosphorylated and nonphosphorylated proteins. Compared with the titanium dioxide-coated magnetic beads commercially available, our magnetite microparticles show a better specificity toward phosphopeptides. The selectively-enriched phosphopeptides from tryptic digests of β-casein can be detected down to 0.4 fmol μl⁻¹, whereas the recovery efficiency is approximately 90% for monophosphopeptides. This magnetite microparticle-based affinity technology with optimized enrichment conditions is then immediately applied to identify all possible phosphorylation sites on a signal protein isolated in real time from a stress-stimulated mammalian cell culture. A large fraction of peptides eluted from the magnetic particle enrichment step were identified and characterized as either single- or multiphosphorylated species by tandem mass spectrometry. With their high efficiency and utility for phosphopeptide enrichment, the magnetite microparticles hold great potential in the phosphoproteomic studies on real-time samples from cell lysates.     

化学发光微粒子免疫法和梅毒螺旋体颗粒凝集试验检测梅毒抗体的比较

目的评价化学发光微粒子免疫法（chemiluminescence microparticle immunoassay, CMIA）检测临床血清标本梅毒螺旋体抗体的敏感性和特异性。方法用梅毒螺旋体颗粒凝集试验（TVeponema Pallidum particie agglutination test,TPPA）法作为对照标准,采用CMIA法检测2012年11月到12月1200例住院患者的血清标本,并用卡方检验评价两种检测方法对同一个样本的化验结果的一致性。结果1200例血清标本中用CMIA法检出阳性率为11.3%,TPPA法检出阳性率为10. 9% ,以TPPA为标准,CMIA法敏感性为96. 9%,特异性为99. 2%,其中CMIA法检测血清S/CO值〉 4. 00的110例,用TPPA确认107例阳性,阳性预测值（PPV）为97.3%;CMIA法S/C0值在1.0-9.0,TPPA可出现阴性结果。结论CMIA法可替代TPPA法进行梅毒螺旋体抗体检测,对于CMIA法检测S/C0值1. 0-4.0的需进一步复检。     

Development of a novel T cell-oriented vaccine using CTL/Th-hybrid epitope long peptide and biodegradable microparticles,against an intracellular bacterium

Antigen-specific CD8+ T-lymphocytes (cytotoxic T-lymphocytes: CTL), as well as CD4+ T-lymphocytes (helper T-lymphocytes: Th), simultaneously play an important role in the elimination of intracellular bacteria such as Mycobacterium tuberculosis and Listeria monocytogenes. Administration of T-cell epitope short peptide needs large numbers of peptides for effective vaccination due to its easily degradable nature in vivo. In this respect, biocompatible and biodegradable microparticles combined with CTL/Th-hybrid epitope long peptide (long peptide) have been used to diminish the degradation of loaded peptide. The aim of this study is to develop a novel T cell-oriented vaccine against intracellular bacteria that is composed of long peptide and poly (lactic-co-glycolic acid) (PLGA) microparticles. Mouse bone marrow-derived dendritic cells (BMDCs) were loaded with L. monocytogenes listeriolysin O (LLO)-derived or ovalbumin (OVA)-derived long peptide/PLGA or other comparative antigens. The antigen-loaded BMDCs were injected subcutaneously into the flank of mice twice, and then, the spleens were collected and lymphocyte proliferation and interferon-γ production were evaluated. The median diameter of the PLGA spheres was 1.38 μm. Both LLO- and OVA-long peptide/PLGA showed significantly more robust CTL and Th proliferations with higher interferon-γ production than the long peptide alone or CTL and Th short peptides/PLGA vaccination. Furthermore, the LLO-long peptide/PLGA vaccination showed a significantly lower bacterial burden in spleens compared with the long peptide alone or the CTL and Th short peptides/PLGA vaccination after the challenge of lethal amounts of L. monocytogenes. These results suggest that the novel vaccine taking advantages of CTL/Th-hybrid epitope long peptide and PLGA microparticle is effective for protection against intracellular bacteria.     

灵芝悬浮培养中添加微颗粒Talc对灵芝酸产生的影响

灵芝酸是灵芝中重要的药理活性物质,其低产量限制了它的广泛应用和深入研究,高效提高液体发酵中灵芝酸的含量十分必要。以CGMCC 5.65为材料,在悬浮培养条件下,研究添加微颗粒Talc对灵芝酸产生的影响。结果表明,微颗粒Talc添加显著减小了灵芝细胞粒径,对照组为(3.33±0.16)mm,15g/L微颗粒Talc添加组为(2.04±0.12)mm。灵芝细胞中单体灵芝酸和总灵芝酸的含量在微颗粒Talc添加条件下也显著提高。15g/L微颗粒Talc添加组的总灵芝酸含量达到(1.51±0.02)mg/100mg细胞干重,GA-Mk、GA-T和GA-Me的含量最高为(6.02±0.29)、(5.08±0.14)和(1.71±0.09)μg/100mg细胞干重,分别是对照的1.6、4、1.9和1.4倍。另外,15g/L微颗粒Talc添加条件下鲨烯和羊毛甾醇的最大积累量分别为(3.69±0.23)和(34.86±6.41)μg/100mg细胞干重,是对照的2.6和4.2倍;灵芝酸生物合成途径关键基因fps和cyp-5150l8的表达量最高为对照的2.35和1.53倍。     

INTRACELLULAR LOCALIZATION OF AN ENDOGENOUS CELLULOSE SYNTHASE OF MICRASTERIAS DENTICULATA (DESMIDIALES,CHLOROPHYTA) BY MEANS OF TRANSIENT GENETIC TRANSFORMATION1

The desmid Micrasterias denticulata Bréb. is useful for the study of streptophyte cell wall biology and morphology. However, no tools to analyze cell biological processes in vivo in this species are available. In the present study, transient gene expression under the control of the chl a/b–binding protein gene of the Closterium peracerosum–strigosum–littorale complex (CpCAB1) promotor was achieved for M. denticulata and illustrated by the intracellular localization of an endogenous cellulose synthase (MdCesA1). A transformation efficiency of 1/5,000 cells was achieved following microparticle bombardment. The free green fluorescent protein (GFP) signal was detected both in the nucleus and in the cytoplasm. The MdCesA1‐GFP fusion protein, on the other hand, occurred at the plasma membrane in particles concentrated at the lobe indentations, the lobe tips, and, to a lesser extent, along the lobe sides. Hence, the multipolar growth mechanism of the cell is reflected. In addition, the margins of cytoplasmic compartments, most likely dictyosomes, were labeled, in accordance with the known secretory pathway of cellulose synthase complexes. Besides intracellular localization studies, the utility of the system for overexpression phenotyping is discussed.