An in vitro novel mechanism of regulating the activity of pyruvate kinase M2 by thyroid hormone and fructose 1, 6-bisphosphate

We have recently shown that the cytosolic thyroid hormone binding protein (p58-M2) in human epidermoid carcinoma A431 cells is a monomer of pyruvate kinase, subtype M2 (PKM2). To characterize further the molecular properties of p58-M2, we overexpressed p58-M2 in Escherichia coli and purified it to homogeneity. At 22 degrees C, the monomeric p58-M2, exhibited kinase activity with an apparent Vmax of 22 +/- 9 units/mg. The Km for adenosine diphosphate (ADP) and phosphoenolpyruvate (PEP) are 3.85 +/- 2.4 and 1.55 +/- 0.73 mM, respectively. Upon activation by fructose 1,6-bisphosphate (Fru-1,6-P2), Vmax and Km for ADP and PEP were changed to 490 +/- 27 units/mg and 0.63 +/- 0.09 and 0.13 +/- 0.01 mM, respectively. These results indicated that p58-M2 has intrinsic kinase activity. Analysis of the molecular size indicated that the activation of p58-M2, by Fru-1,6-P2 resulted in the association of the monomeric p58-M2 to the tetrameric PKM2. p58-M2 bound to 3,3',5-triiodo-L-thyronine (T3) (Ka = 1.7 x 10(7) M-1) and exhibited analogue specificity, whereas PKM2 did not bind thyroid hormone. The order of binding affinity was L-T3 greater than L-thyroxine greater than 3,3',5-triiodothyropropionic acid greater than 3'-isopropyl-3,5-triiodo-L-thyronine greater than 3'5',3-triiodo-L-thyronine. Binding of T3 and its analogues resulted in the inhibition of the kinase activity of p58-M2. The order of kinase inhibitory activity and preventing its association to tetrameric PKM2 was parallel to that of binding activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

PYPAF7, a novel PYRIN-containing Apaf1-like protein that regulates activation of NF-kappa B and caspase-1-dependent cytokine processing

PYRIN-containing Apaf1-like proteins (PYPAFs) are members of the nucleotide-binding site/leucine-rich repeat (NBS/LRR) family of signal transduction proteins. We report here that PYPAF7 is a novel PYPAF protein that activates inflammatory signaling pathways. The expression of PYPAF7 is highly restricted to immune cells, and its gene maps to chromosome 19q13.4, a locus that contains a cluster of genes encoding numerous PYPAF family members. Co-expression of PYPAF7 with ASC results in the recruitment of PYPAF7 to distinct cytoplasmic loci and a potent synergistic activation of NF-kappa B. To identify other proteins involved in PYPAF7 and ASC signaling pathways, we performed a mammalian two-hybrid screen and identified pro-caspase-1 as a binding partner of ASC. Co-expression of PYPAF7 and ASC results in the synergistic activation of caspase-1 and a corresponding increase in secretion of interleukin-1 beta. In addition, PYPAF1 induces caspase-1-dependent cytokine processing when co-expressed with ASC. These findings indicate that PYPAF family members participate in inflammatory signaling by regulating the activation of NF-kappa B and cytokine processing.     

Effects of thymic polypeptides on the thymopoiesis of mouse embryonic stem cells

The thymus provides a unique cellular and hormonic microenvironment for the development of immunocompetent T cells. Thymic polypeptides have been widely used clinically for the treatment of tumors, infectious diseases and immune deficiency diseases. They have already shown the ability to stimulate the maturation of hematopoietic stem cells towards the CD3+CD4+ T cell lineage. However, their effects on the thymopoiesis of embryonic stem cells are still unexplored. In this paper, we compared the effects of three thymic polypeptides, thymopentin (TP5), thymosin alpha-1 (Talpha-1) and thymopeptides on the in vitro thymopoiesis of mouse embryonic stem (ES) cells. Using the embryoid body induction system, we found that both Talpha-1 and thymopeptides effectively induced ES cells to differentiate sequentially into the CD3+ and CD4+/CD8+ T cells. These T cells had T cell receptor (TCR) Vbeta gene rearrangement and most were TCRalphabeta T cells. We also found that the expression of the Notch receptor and its ligands Delta-like-1 and Delta-like-4 gradually increased during the induction. However, TP5 failed to induce the T cell differentiation of the ES cells. In summary, this is the first report to demonstrate that Talpha-1 can stimulate the T cell early stage differentiation from ES cells using the embryoid body protocol. These findings provide a powerful model for studying T cell development and may open new venues for the clinical application of Talpha-1.     

Combination of bone tissue engineering and BMP-2 gene transfection promotes bone healing in osteoporotic rats

OBJECTIVE: The aim of this study was to develop a feasible approach to promote bone healing in osteoporotic rats using autogenous bone tissue-engineering and gene transfection of human bone morphogenetic protein 2 (hBMP-2). METHODS: Bone marrow stromal cells (BMSCs) from the left tibia of osteoporotic rats were transfected with the hBMP-2 gene in vitro which was confirmed by immunohistochemistry, in situ hybridization and Western blotting. Autogenous transfected or untransfected BMSCs were seeded on macroporous coral hydroxyapatite (CHA) scaffolds. Each cell-scaffold construct was implanted into a defect site which was created in the ramus of the mandible of osteoporotic rats. Four or eight weeks after implantation in situ hybridization was performed in BMSCs transfected with hBMP-2, X-ray examinations, histological and histomorphological analyses were used to evaluate the effect of tissue-engineered bone on osseous defect repair. RESULTS: Newly formed bone was observed at the margin of the defect 4 weeks after implantation with BMSCs transfected with BMP-2. Mature bone was observed 8 weeks after treatment. In the control group there was considerably less new bone and some adipose tissue was observed at the defect margins 8 weeks after implantation. CONCLUSIONS: Autogenous cells transfected with hBMP-2 promote bone formation in osteoporotic rats. BMSC-mediated BMP-2 gene therapy used in conjunction with bone tissue engineering may be used to successfully treat bone defects in osteoporotic rats. This method provides a powerful tool for bone regeneration and other tissue engineering.     

基于CSSL的水稻抽穗期QTL定位及遗传分析

抽穗期是水稻（Oryza sativa）品种的重要农艺性状之一,适宜的抽穗期是获得理想产量的前提。鉴定和定位水稻抽穗期基因/QTL,分析其遗传效应对改良水稻抽穗期至关重要。以籼稻品种9311（Oryzasativa ssp.indica‘Yangdao 6’）为受体,粳稻品种日本晴（Oryza sativa ssp.japonica‘Nipponbare’）为供体构建的94个染色体片段置换系群体为材料,以P≤0.01为阈值,对置换片段上的抽穗期QTL进行了鉴定。采用代换作图法共定位了4个控制水稻抽穗期的QTL,分别位于第3、第4、第5和第8染色体;QTL的加性效应值变化范围为–6.4––2.7,加性效应百分率变化范围为–6.4%––2.7%;qHD-3和qHD-8加性效应值较大,表现主效基因特征。为了进一步定位qHD-3和qHD-8,在目标区域加密16对SSR引物,qHD-3和qHD-8分别被界定在第3染色体RM3166–RM16206之间及第8染色体RM4085–RM8271之间,其遗传距离分别为13.9cM和6.4cM。研究结果为利用分子标记辅助选择改良水稻抽穗期奠定了基础。     

脱落酸人工抗原合成及多克隆抗体制备

目的:为了对植物细胞中的脱落酸(ABA)进行定量和定位分析,研究了脱落酸人工抗原的合成以及多克隆抗体的制备。方法:用重氮化法将ABA分别与牛血清白蛋白(BSA)、卵清白蛋白(OVA)联结,得到ABA的免疫抗原和包被抗原,并采用紫外全波长扫描和SDS-PAGE对合成的抗原进行了鉴定。以经过鉴定的抗原免疫白兔,制备出ABA的多克隆抗体;采用间接酶联免疫法(ELISA)对抗血清进行效价检测,通过离子交换层析法获得纯化的抗体。结果:ABA与BSA的平均偶联比为5.3∶1,抗血清效价为1∶16000。结论:人工抗原和多克隆抗体制备成功,为采用ELISA和免疫胶体金技术(ICG)检测ABA提供了有效工具。     

Formation of collagen-glycosaminoglycan blended nanofibrous scaffolds and their biological properties

The development of blended collagen and glycosaminoglycan (GAG) scaffolds can potentially be used in many soft tissue engineering applications since the scaffolds mimic the structure and biological function of native extracellular matrix (ECM). In this study, we were able to obtain novel nanofibrous collagen-GAG scaffolds by electrospinning collagen blended with chondroitin sulfate (CS), a widely used GAG, in a mixed solvent of trifluoroethanol and water. The electrospun collagen-GAG scaffold with 4% CS (COLL-CS-04) exhibited a uniform fiber structure with nanoscale diameters. A second collagen-GAG scaffold with 10% CS consisted of smaller diameter fibers but exhibited a broader diameter distribution due to the different solution properties in comparison with COLL-CS-04. After cross-linking with glutaraldehyde vapor, the collagen-GAG scaffolds became more biostable and were resistant to collagenase degradation. This is evidently a more favorable environment allowing increased proliferation of rabbit conjunctiva fibroblast on the scaffolds. Incorporation of CS into collagen nanofibers without cross-linking did not increase the biostability but still promoted cell growth. The potential of applying the nanoscale collagen-GAG scaffold in tissue engineering is significant since the nanodimension fibers made of natural ECM mimic closely the native ECM found in the human body. The high surface area characteristic of this scaffold may maximize cell-ECM interaction and promote tissue regeneration faster than other conventional scaffolds.     

阴道毛滴虫铁氧还蛋白基因的原核表达

目的在原核细胞中表达阴道毛滴虫铁氧还蛋白(ferredoxin,Fd)基因。方法构建阴道毛滴虫Fd基因的原核表达重组质粒pUC19-Fd,转化大肠埃希菌JM109感受态细胞中,异丙基-β-D-硫代半乳糖苷(IPTG)诱导蛋白质表达。结果经十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)和免疫印迹(Western blot)分析,重组质粒在大肠埃希菌中表达出Fd。结论在大肠埃希菌中表达出了Fd。     

广西孢堆黑粉菌新种(黑粉菌目)

本文报道寄生在白健秆［Eulaliapallens（Hash）Kuntze］植物上的广西孢堆黑粉菌（SporisoriumguangxieseL．Guo）新种,其孢子堆生在全部小穗中,外有白色包被包围。中轴单个。孢子团黑褐色,粉状。黑粉孢子近球形,卵圆形或椭圆形,6～9×5～7．5μm,黄褐色;壁厚不均匀,12μm,通常在黑粉孢子的两端色深并增厚或一边色深,密的细瘤。不育细胞6～11．5（～14）×5～11μm,黄色,光滑,短链。文中讨论了其与分布于澳大利亚的黄金茅孢堆黑粉菌［Sporisoriumeulaliae（Ling）Vanky］及单序草孢堆黑粉菌（SporisoriumamauraeK．＆C．Vanky）的主要区别。     

水稻条纹病毒蛋白与核酸的特性

提纯的水稻条纹病毒（云南宜良分离物）在电镜下的形态为多型性,但主要是宽8－10urn,长80－25O的分枝丝状体,有些为直径3urn或8urn的开环环状体,有些为13urn宽,130－190urn长的丝状体,但其基本结构应是直径3urn、长度不等的丝状体。经聚丙烯酸胺凝胶电泳分析,VRNA4编码的病害特异蛋白（SP）分子量为19．9kDa,而VCRNA3编码的外壳蛋白（CP）约为336kDa。在非变性条件下,RSV的4条ssRNAs大小分别为3‘OXIO‘（ssRNAI）、互．2XIc‘（ssR．NAZ）、0．9X10‘（ssRNA3）和0．8X10‘Da（SSRNA4）,有时出现一条大小为0．58X10‘Da的单链RNA（ssRNA）;而4条dsRNAs的分子量分别为4．9X10‘（dsRNAI）、2．8X10‘（dsRNAZ）、20XIOo（dsRNA3）和1．7X10‘D。（dSRNA4）。利用制备电泳分离提纯的外壳蛋白免疫家兔,得到了高特异性的抗血清。A蛋白夹心ELISA检测结果表服RSV－CP与水稻草状矮化病毒（RGSV）CP抗血清有微弱的反应,但与RSV、RGSV的SP抗血清没有反应,而RSV－CP抗血清与RSV．SP及RGSV的SP、CP都无血清学关系,这个结果表明RGSV与RSV之间在进化上具有一定的亲缘关系。