胰腺干细胞的研究进展

概述了胰腺干细胞的分布、胰腺的发生、胰腺干细胞的相关标记物以及胰腺干细胞的体外分离培养、增殖、分化等领域的研究进展，并对胰腺干细胞的生物学特征、体外分离培养时遇到的困难等进行了探讨，针对所遇到的困难提出了一些改进意见。     

饲养层细胞对胚胎干细胞的影响及其分离培养的影响因素

胚胎干细胞及其相关研究是生命科学领域中最有活力、最有影响力、最有应用前景的研究方向之一，它与遗传工程，转基因技术等相结合具有重大的理论意义与实践价值。饲养层细胞在胚胎干细胞分离培养的过程中起着异常重要的作用。作者结合实践经验就饲养层细胞对胚胎干细胞的影响进行了概述，介绍了饲养层细胞的分类，并分析了饲养层细胞分离培养的影响因素。     

胚胎干细胞的研究进展

胚胎干细胞来源于附植前胚胎的内细胞团或附植后胎儿的原始生殖细胞具有发育全能性的细胞。本文从它的研究概况、生物学特性、胚胎干细胞的分离培养与建系等方面做一概述。     

In vitro neuronal and osteogenic differentiation of mesenchymal stem cells from human umbilical cord blood

Mesenchymal stem cells (MSCs) have the capabilities for self-renewal and differentiation into cells with the phenotypes of bone, cartilage, neurons and fat cells. These features of MSCs have attracted the attention of investigators for using MSCs for cell-based therapies to treat several human diseases. Because bone marrow-derived cells, which are a main source of MSCs, are not always acceptable due to a significant drop in their cell number and proliferative/differentiation capacity with age, human umbilical cord blood (UCB) cells are good substitutes for BMCs due to the immaturity of newborn cells. Although the isolation of hematopoietic stem cells from UCB has been well established, the isolation and characterization of MSCs from UCB still need to be established and evaluated. In this study, we isolated and characterized MSCs. UCB-derived mononuclear cells, which gave rise to adherent cells, exhibited either an osteoclast or a mesenchymal-like phenotype. The attached cells with mesenchymal phenotypes displayed fibroblast-like morphologies, and they expressed mesenchym-related antigens (SH2 and vimentin) and periodic acid Schiff activity. Also, UCB-derived MSCs were able to transdifferentiate into bone and 2 types of neuronal cells, in vitro. Therefore, it is suggested that the MSCs from UCB might be a good alternative to bone marrow cells for transplantation or cell therapy.     

Biological characters of mesenchymal stem cells of human umbilical cord blood

AIM：To study the isolation,expansion and purification of mesenchymal stem cells (MSCs) from human umbilical cord blood (UCB),and investigate some biological identities of MSCs.METHODS：(1) MSCs of UCB,adult bone marrow (BM) and fetus BM were isolated by centrifugation with Ficoll,and the different kinds of MSCs were observed everyday.(2) Surface markers of MSCs were identified by flow cytometry.(3) The level of HGFs (TPO,SCF,FLT-3L,IL-6) secreted by different sources of MSCs was checked by ELISA method.RESULTS：(1) No difference in morphology of the colonies between UCB MSCs and BM MSCs was observed.However,the mononuclear cells needed in culture of UCB MSCs was about 3 times more than that in culture of BM MSCs.The times of UCB MSCs colony formation and confluencing were longer than that of BM in primary culture.(2) After passaged,there was no significant difference in the proliferation rates of 3 kinds of MSCs.Only 4 of 15 UCB samples contained a homogeneous population of MSCs.(3) UCB MSCs shared the same markers with BM MSCs.Neither hematopoietic marker nor immunologic recognition antigens were expressed.(4) The level of hematopoietic growth factors (HGFs) secreted by 3 kinds of MSCs was similar.CONCLUSIONS：(1) MSCs were isolated from UCB,but the amount of MSCs in UCB was smaller than that in BM,and just seldom samples of UCB contained homogeneous MSCs.(2) MSCs from UCB and BM shared the same biological characteristics,such as proliferation ability,surface markers,immunophenotypes and HGFs secretion.     

地高辛标记cDNA探针检测苹果茎痘病毒

 Partial sequence(314 bp) of ASPV was cloned and used as a probe labelled with digoxigenin-11dUTP. The total RNA extracted from samples with Apple stem pitting virus and a series of dilutions of plasmid with ASPV-cDNA were detected by dot blot hybridization. The results showed that the probe was sensitive and specific. The probe couldn't hybridize with total RNA of Apple stem grooving virus, Apple mosaic virus and Apple chlorotic leaf spot virus samples as well as negative control, only hybridized with that extracted from dormant shoot infected with ASPV. The sensitivity for detection of plasmid contained ASPV-cDNA was 1.64 μg.     

反向遗传技术在传染性法氏囊病病毒研究中的应用

传染性法氏囊病是鸡的最严重疾病之一,其病原是鸡传染性法氏囊病病毒(IBDV),IBDV基因组为两片段双链RNA,变异株和超强毒株的出现,给传统的疫苗免疫带来了新的挑战,因此,加强对IBDV的基础研究是控制该病的关键.RNA的结构不稳定成为阻碍RNA病毒研究的主要障碍,近年来兴起的反向遗传技术将RNA病毒的基因组转化为cDNA,从而使RNA病毒的基因操作成为可能,也使RNA病毒的研究获得了快速的发展.文章就传染性法氏囊病病毒反向遗传操作研究的意义、方法、概况及相关分子生物学进行了全面综述.     

Interacting effects of temperature integration and light intensity on growth and development of single-stemmed cut rose plants

Energy conservation in horticulture can be achieved by allowing temperatures to fluctuate within predefined bandwidths instead of using rigid set points for heating and ventilation. In temperature integration, plants are supposed to compensate effects of temporarily deviations of the average temperature some time later by deviations in the opposite direction. However, little is still known on the effects of integration periods exceeding 1 day. In this study, effects of temperature integration on growth and development of single-stemmed cut rose plants were determined. Pruned rose shoots were placed in climate chambers in which light levels switched daily (2 days integration period) or weekly (14 days integration period) from high light intensity (300 μmol m⁻² s⁻¹) to low light (150 μmol m⁻² s⁻¹). Temperatures were kept continuously at 20 °C (control) or changed with the light intensity (phase, high temperature at high light intensity, low temperature at low light intensity) or changed opposite to the light intensity (counter phase). Bandwidths of temperature integration were 0, 6 or 10 °C. Under these conditions, buds grew out to harvestable shoots in approximately 45 days. At both integration periods, shoot length was significantly reduced with increasing bandwidths of temperature integration. Shoot dry weights were reduced when a bandwidth of 10 °C was applied. At both integration periods, rates of photosynthesis were primarily determined by light intensity. However, in the counter phase treatments, photosynthesis rate at high light and low temperature was reduced compared to the high light condition of the control. Under these conditions, starch content increased to approximately 10%, suggesting a feedback inhibition of the rate of photosynthesis. However, this did not (yet) affect plant growth or development.     

Analysis of chromosome aberration due to ethidium bromide using AFM

AIM: To study chromosome aberration due to ethidium bromide (EB),a heterocyclic organic compound and an organic fluorescence dye commonly used in biochemical experiment,and to help further understanding the molecular mechanism of tumor or cancer induced by EB and other heterocyclic organic compounds.METHODS: The toxicity action of EB was evaluated from three aspects including DNA,chromosome and embryo stem cells (ESCs) using atomic force microscopy (AFM),and thereinto,the morphology structural difference of ESCs treated with two EB doses was also valuated.RESULTS: The morphological structures of DNA,chromosome and ESCs were dramatically damaged.The average height of DNA decreased 0.5 nm;chromosomal arms were ruptured from centromere location;molecules of cellular membrane congregated and loop-like structure formed,and ES cell masses were collapsed and became dead after large EB doses treatment and mesh-like morphological structure was discernable.CONCLUSION: The toxicity action of EB is strong and destroys the surface structure of DNA and chromosome.EB induces structural aberration of ES cellular membrane and cell death.The results indicate that the action of EB is externalized at gene level and cell level,which is important to study the carcinogenicity of EB.     

Influences of coculture with bone marrow mesenchymal stem cells on dopaminergic neurons in brain slice treated with 1-methyl-4-phenylpytidinium

AIM: To study the protective effects of bone marrow-derived mesenchymal stem cells on damaged dopaminergic neurons induced by 1-methyl-4-phenylpytidinium(MPP+).METHODS: The parkinson disease(PD) models were established in newborn rats. Bone marrow mesenchymal stem cells(MSCs) obtained from adult bone marrow were cultured, isolated and purified. MSCs were co-cultured with brain slice and the immunohistochemical technique, electron microscopy, propidium iodide staining were used to observe the changes of neurons. RESULTS: In the MPP+ treatment group, the neurites grew slowly and sparsely, dead cells were found in all regions. In the co-culture group, the neuritis grew densely, only a few cells were dead, the number of tyrosine hydroxylase(TH)-stained neurons increased and the structure of organellae was normal. CONCLUSION: MSCs may protect dopaminergic neurons against damage induced by MPP+. These results provide some data for cell transplantation therapy to Parkinsons disease.