A high-throughput, near-saturating screen for type III effector genes from Pseudomonas syringae

Pseudomonas syringae strains deliver variable numbers of type III effector proteins into plant cells during infection. These proteins are required for virulence, because strains incapable of delivering them are nonpathogenic. We implemented a whole-genome, high-throughput screen for identifying P. syringae type III effector genes. The screen relied on FACS and an arabinose-inducible hrpL sigma factor to automate the identification and cloning of HrpL-regulated genes. We determined whether candidate genes encode type III effector proteins by creating and testing full-length protein fusions to a reporter called Delta79AvrRpt2 that, when fused to known type III effector proteins, is translocated and elicits a hypersensitive response in leaves of Arabidopsis thaliana expressing the RPS2 plant disease resistance protein. Delta79AvrRpt2 is thus a marker for type III secretion system-dependent translocation, the most critical criterion for defining type III effector proteins. We describe our screen and the collection of type III effector proteins from two pathovars of P. syringae. This stringent functional criteria defined 29 type III proteins from P. syringae pv. tomato, and 19 from P. syringae pv. phaseolicola race 6. Our data provide full functional annotation of the hrpL-dependent type III effector suites from two sequenced P. syringae pathovars and show that type III effector protein suites are highly variable in this pathogen, presumably reflecting the evolutionary selection imposed by the various host plants.     

Thrombopoietin stimulates megakaryocytopoiesis, myelopoiesis, and expansion of CD34+ progenitor cells from single CD34+Thy-1+Lin- primitive progenitor cells

Thrombopoietin (TPO) or MpI ligand is known to stimulate megakaryocyte (MK) proliferation and differentiation. To identify the earliest human hematopoietic cells on which TPO acts, we cultured single CD34+Thy- 1+Lin- adult bone marrow cells in the presence of TPO alone, with TPO and interleukin-3 (IL-3), or with TPO and c-kit ligand (KL) in the presence of a murine stromal cell line (Sys1). Two distinct growth morphologies were observed: expansion of up to 200 blast cells with subsequent differentiation to large refractile CD41b+ MKs within 3 weeks or expansion to 200-10,000 blast cells, up to 25% of which expressed CD34. The latter blast cell expansions occurred over a 3- to 6-week period without obvious MK differentiation. Morphological staining, analysis of surface marker expression, and colony formation analysis revealed that these populations consisted predominantly of cells committed to the myelomonocytic lineage. The addition of IL-3 to TPO-containing cultures increased the extent of proliferation of single cells, whereas addition of KL increased the percentage of CD34+ cells among the expanding cell populations. Production of multiple colony- forming unit-MK from single CD34+Thy-1+Lin- cells in the presence of TPO was also demonstrated. In limiting dilution assays of CD34+Lin- cells, TPO was found to increase the size and frequency of cobblestone areas at 4 weeks in stromal cultures in the presence of leukemia inhibitory factor and IL-6. In stroma-free cultures, TPO activated a quiescent CD34+Lin-Rhodamine 123lo subset of primitive hematopoietic progenitor cells into cycle, without loss of CD34 expression. These data demonstrate that TPO acts directly on and supports division of cells more primitive than those committed to the MK lineage.     

Evaluation of drugs for elimination of leukemic cells from the bone marrow of patients with acute leukemia

Relatively nonmyelotoxic drugs and drug combinations were investigated for their ability to eliminate malignant cells from human bone marrow. In vitro 90% inhibitory concentration (IC90) doses were established on granulocyte macrophage colony-forming units (GM-CFU) in culture of bone marrow by using the GM-CFU assay for the following drugs: 4- hydroperoxycyclophosphamide (4-HC), Adriamycin, L-asparaginase, bleomycin, hydrocortisone, VP-16, spirogermanium, Taxol, and vincristine. The leukemic cell kill efficiency of these drugs at IC90 doses was compared with that of 4-HC on acute lymphoid leukemia (ALL) cell lines by using the limiting-dilution assay. Under these conditions, no single drug was superior to 4-HC. To increase the in vitro effect in leukemic cell kill, combinations of vincristine with hydrocortisone, Adriamycin, VP-16, and 4-HC were investigated. Vincristine at 1 to 5 micrograms/mL increased the marrow cytotoxicity of hydrocortisone, Adriamycin, and VP-16, but it was protective (subadditive) with 4-HC. Vincristine and 4-HC in combination was additive to supraadditive on ALL cell lines, increased the leukemic cell kill by one to two logs above 4-HC alone at IC90 doses (P less than .05), and was not affected by the addition of excess marrow cells. The recommended doses for chemopurging in clinical studies are vincristine, 1 to 5 micrograms/mL, plus 4-HC, 5 micrograms/mL.     

前列腺特异抗原研究进展与挑战(摘要)

前列腺特异抗原(ＰＳＡ)发现四分之一世纪以来,已成为诊断前列腺癌最有价值的肿瘤标志物。前列腺癌在男性癌症发病中占首位。自从80年代中期第一代检测ＰＳＡ的方法问世以来,前列腺癌的发病率有了显著改变。这部分归功于ＰＳＡ检测的增加,从而使前列腺癌得到早期诊断,这有利于将癌症控制在发病早期,增加治愈的可能性。虽然ＰＳＡ是一个有效的肿瘤标志物,并具有器官特异性,但其癌症特异性不高。ＰＳＡ升高也可见于其他良性前列腺疾病,尤其当ＰＳＡ浓度在4～10μｇ/Ｌ时。这个浓度范围被称为“诊断灰色区域”。对ＰＳＡ分子结构的研究主要集中…     

Study on liver injury models induced by CCl4 D-Gal and ANIT in mice

ＳｔｕｄｙｏｎｌｉｖｅｒｉｎｊｕｒｙｍｏｄｅｌｓｉｎｄｕｃｅｄｂｙＣＣｌ４ＤＧａｌａｎｄＡＮＩＴｉｎｍｉｃｅＹＡＮＧＸｉｎＢｏ１，ＨＵＡＮＧＺｈｅｎｇＭｉｎｇ１，ＣＡＯＷｅｎＢｉｎ１，ＺＨＥＮＧＭｉｎｇ１，ＣＨＥＮＨｏｎｇＹａｎ１，ＺＨＡＮ...     

Effects of sera from burn patients on human hepatocytic viscoelasticity

ＥｆｅｃｔｓｏｆｓｅｒａｆｒｏｍｂｕｒｎｐａｔｉｅｎｔｓｏｎｈｕｍａｎｈｅｐａｔｏｃｙｔｉｃｖｉｓｃｏｅｌａｓｔｉｃｉｔｙＷＡＮＧＸｉａｏＪｕｎ，ＬＵＯＸｉａｎｇＤｏｎｇ，ＬＵＯＱｉｎａｎｄＹＡＮＧＺｏｎｇＣｈｅｎｇＢｕｒｎＲｅｓｅａｒｃｈＩｎ...     

多聚二磷酸腺苷核糖合成酶抑制剂对血管紧张素Ⅱ刺激培养心肌细胞异常基因表达的阻止作用

目的:观察多聚二磷酸腺苷(ADP)核糖合成酶(PARP)抑制剂对血管紧张素Ⅱ(AngⅡ)刺激的乳鼠心脏心肌重构的预防作用.方法:新生大鼠心肌细胞原代培养,传代,用PARP抑制剂3-AB预处理细胞,观察PARP抑制剂对AngⅡ诱导心肌细胞PARP激活、PARPl表达,细胞内ROS产生和c-fos,ANP,β/aMHC基因表达的影响.结果:AngⅡ显著诱导心肌细胞PARP激活,ROS产生增加,PARPl、c-los、β/a-MHC、ANP基因表达增加.给予3-AB预处理可显著抑制AngⅡ诱导的上述变化.结论:AngⅡ可以诱导培养的心肌细胞内PARP激活,PARPl蛋白表达增加,3-AB预处理可以明显降低AngⅡ诱导的心肌细胞内异常基因表达增加,提示PARPl参与了心室重构的发生发展过程.