Morphological and phylogenetic studies of Cytospora (Valsaceae,Diaporthales) isolates from Chinese scholar tree,with description of a new species

Cytospora species are the most serious and widespread pathogens associated with canker disease on multiple plants. In this study, three species, i.e., Cytospora sophoricola, C. chrysosperma, and C. sophorae, which were isolated from Sophora in China, are described and illustrated based on their morphological characteristics and phylogenetic analyses. Cytospora sophoricola was distinguished clearly by its larger disc, multiple ostioles, cystic and multiple locules, and specific cultural characteristics, i.e., protruding fruiting bodies. Maximum parsimony and maximum likelihood analysis showed that it did not cluster with any known species of Cytospora, so it is described as a new species. Cytospora sophorae is a previously reported species from Sophora, which is redescribed based on new isolates and additional observations. Another species was identified as C. chrysosperma, which is reported for the first time on Sophora, so Papilionaceae is shown to be a new host family for C. chrysosperma. The morphological affinities of these species with related taxa are discussed, while the phylogenetic relationships of these species with other fungus in the genus Cytospora were elucidated based on their internal transcribed spacer (ITS) rRNA region sequences.     

Isolation of monoclonal antibodies reacting with peribacteriod membranes and other components of pea root nodules containing Rhizobium leguminosarum

Plant and bacterial antigens contributing to nodule development and symbiosis in pea (Pisum sativum L.) roots were identified after isolation of a set of monoclonal antibody (McAb)-producing hybridoma lines. Rats were immunised with the peribacteriod material released by mild osmotic shock treatment from membrane-enclosed bacteroids of Rhizobium leguminosarum bv. viceae. In order to diversify the range of McAb specificities, this material was either used as immunogen directly (method 1), or after immunodepletion of a set of glycoprotein and lipopolysaccharide antigens (method 2), or after deglycosylation (method 3). After fusion and screening of cloned hybridoma lines, these three immunisation methods gave respectively 4, 2 and 1 classes of McAb with unique antigen specificities. Ultrastructural immunogold localisation studies showed four different antigens to be present on peribacteriod and plasma membranes (identified by MAC 64, 202, 206 or 209); in addition, a glycoprotein of plant origin but present in the infection-thread matrix was identified by MAC 204. Although none of the epitopes recognised by these McAb was nodule-specific, several were found to be more abundant in extracts of nodule tissue than in uninfected roots (MAC 64, 202, 204, 206). Two McAb reacted with new bacterial antigens: MAC 203 identified a bacterial antigen expressed upon infection but not in free-living cultures of Rhizobium, and MAC 115 identified a bacterial polypeptide (55 kdaltons) that was present in both free-living and bacteroid forms. There were also some McAb of broader specificity that react with antigens present in both plant and bacterial cytoplasms.Abbreviations ELISA enzyme-linked immunosorbent assay - Ig inmunoglobulin - kDa kilodalton - LPS lipopolysaccharide - McAb monoclonal antibody - PBM peribacteroid membrane - SDS-PAGE sodium dodecyl sulfate-polyacryl-amide gel electrophoresis - TFMS trifluoromethane sulfonic acid     

CXCR4基因转染人脐带间充质干细胞移植治疗糖尿病肾病的实验研究

摘要 目的：探讨过表达CXCR4的人脐带间充质干细胞（human umbilical cord mesenchymal stem cell, hUC-MSCs）移植后对糖尿病肾病的治疗作用。方法：构建CXCR4的慢病毒表达载体，并建立过表达 CXCR4 的人脐带间充质干细胞（CXCR4-MSCs）。采用8周龄健康雌性SD大鼠75只，其中15只为正常对照组，60只为实验组。实验组糖尿病成模后一个月，将糖尿病实验大鼠60只随机分为4组：①移植CXCR4-MSCs组(CXCR4基因转染MSCs组)，即CXCR4组；②移植null-MSCs组(空质粒未转染CXCR4基因的MSCs组)，即null-MSCs；③移植MSCs组( MSCs组)；④PBS组(未移植任何的MSCs，单纯PBS注射，PBS组)。将CXCR4-MSCs、null-MSCs及MSCs消化离心，取含1×106个细胞悬液经尾静脉分别注入CXCR4-MSCs组、null-MSCs组及MSCs组大鼠体内，PBS组注射l mL PBS。干细胞治疗8周后，处死五组大鼠。各组大鼠处死前放代谢笼留取24 h尿，计算尿量，保存送检。处死前尾静脉采血检测血糖、称体重并记录。观察血糖、肾脏肥大指数、肾重、体重、24小时尿蛋白排泄量，并观察肾脏组织病理学改变。结果：60只SD雌性大鼠糖尿病模型成功率达100％，至实验8周糖尿病大鼠总共死亡14只，存活率达76.67％。实验开始后的8周，所有CXCR4组、Null-MSCs组、MSCs组、PBS组大鼠与正常组比较，体重均明显减轻(P<0.01)，血糖明显升高(P<0.01)。MSCs治疗后8周，除正常组外，其余各组大鼠血糖、肾重、肾重/体重比、24小时尿蛋白均显著增高，体重显著降低(P<0.05)；与PBS组相比，CXCR4组、null-MSCs组，MSCs组大鼠的肾重、肾重/体重比、24小时尿蛋白均明显降低(P<0.05)，体重无明显增加，血糖无明显降低(P>0.05)。CXCR4组大鼠的肾重、肾重/体重比、24小时尿蛋白较除正常组外的各组均明显降低(P<0.05)。糖尿病成模后，给予大鼠尾静脉注射干细胞悬液或等量培养液，注射后8周，除正常组外，其余各组PAS染色可见大鼠肾小球肥大，肾小球基底膜增厚、系膜增生、系膜基质增多，部分肾小球出现明显硬化，符合糖尿病肾病中期病理表现。CXCR4组大鼠肾小球系膜基质增生较其余各组大鼠减少(P<0.05)。结论：转染CXCR4的MSCs可改善糖尿病肾病。     

Anomalous segregations at the Sr6 locus for stem rust resistance in wheat

The action of the gene Sr6 for stem rust resistance in wheat is affected by temperature, light, and the particular susceptible parent with which a line carrying Sr6 has been crossed. Two experiments were carried out to determine whether the effect of the susceptible parents was due to modifier genes, the general genetic background, or interallelic interactions. The data indicated that the susceptible parents carried different sr6 alleles that interacted with Sr6, possibly in a paramutation-like process. In the course of the study, a number of anomalous results were obtained that may be due to the action of transposable elements. Received: 18 February 2000 / Accepted: 31 October 2000     

iPSC technology-Powerful hand for disease modeling and therapeutic screen

Cardiovascular and neurodegenerative diseases are major health threats in many developed countries. Recently, target tissues derived from human embryonic stem (hES) cells and induced pluripotent stem cells (iPSCs), such as cardiomyocytes (CMs) or neurons, have been actively mobilized for drug screening. Knowledge of drug toxicity and efficacy obtained using stem cell-derived tissues could parallel that obtained from human trials. Furthermore, iPSC disease models could be advantageous in the development of personalized medicine in various parts of disease sectors. To obtain the maximum benefit from iPSCs in disease modeling, researchers are now focusing on aging, maturation, and metabolism to recapitulate the pathological features seen in patients. Compared to pediatric disease modeling, adult-onset disease modeling with iPSCs requires proper maturation for full manifestation of pathological features. Herein, the success of iPSC technology, focusing on patient-specific drug treatment, maturation-based disease modeling, and alternative approaches to compensate for the current limitations of patient iPSC modeling, will be further discussed. [BMB Reports 2015; 48(5): 256-265]     

Human Pluripotent Stem Cells Have a Novel Mismatch Repair-dependent Damage Response

Human pluripotent stem cells (PSCs) are presumed to have robust DNA repair pathways to ensure genome stability. PSCs likely need to protect against mutations that would otherwise be propagated throughout all tissues of the developing embryo. How these cells respond to genotoxic stress has only recently begun to be investigated. Although PSCs appear to respond to certain forms of damage more efficiently than somatic cells, some DNA damage response pathways such as the replication stress response may be lacking. Not all DNA repair pathways, including the DNA mismatch repair (MMR) pathway, have been well characterized in PSCs to date. MMR maintains genomic stability by repairing DNA polymerase errors. MMR is also involved in the induction of cell cycle arrest and apoptosis in response to certain exogenous DNA-damaging agents. Here, we examined MMR function in PSCs. We have demonstrated that PSCs contain a robust MMR pathway and are highly sensitive to DNA alkylation damage in an MMR-dependent manner. Interestingly, the nature of this alkylation response differs from that previously reported in somatic cell types. In somatic cells, a permanent G₂/M cell cycle arrest is induced in the second cell cycle after DNA damage. The PSCs, however, directly undergo apoptosis in the first cell cycle. This response reveals that PSCs rely on apoptotic cell death as an important defense to avoid mutation accumulation. Our results also suggest an alternative molecular mechanism by which the MMR pathway can induce a response to DNA damage that may have implications for tumorigenesis.