Proteins responding to drought and high-temperature stress in <Emphasis Type="Italic">Populus </Emphasis>× <Emphasis Type="Italic">euramericana</Emphasis> cv. ‘74/76’

Proteomic analysis provides a powerful method of studying plant responses to stress at the protein level. In order to study stress-responsive molecular mechanisms for Populus × euramericana cv. ‘74/76’, one of the most important forest plantation tree species in subtropical and temperate regions, we analyzed the response of 2-year-old cuttings of P. × euramericana cv. ‘74/76’ to drought and high temperature using two-dimensional gel electrophoresis. More than 1,000 reproducible leaf proteins were detected in the controls and treatments, and 26 proteins were found to change notably in abundance. We identified 13 proteins affected by drought stress and 11 proteins affected by high temperature. These proteins are mainly involved in photosynthesis such as ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit and putative photosystem I reaction center subunit II precursor, and detoxification (manganese superoxide dismutase and methionine sulfoxide reductase A). Furthermore, the level of the photosynthesis proteins affected greatly by the imposed stress conditions was consistent with the observed noticeable decrease in net photosynthesis rate. These studies provides a fundamental data for future research on responses to drought and high temperature, two major factors limiting the growth of forest trees during summer under recent climatic warming.     

Hedgehog-mediated paracrine interaction between hepatic stellate cells and marrow-derived mesenchymal stem cells

During liver injury, bone marrow-derived mesenchymal stem cells (MSCs) can migrate and differentiate into hepatocytes. Hepatic stellate cell (SC) activation is a pivotal event in the development of liver fibrosis. Therefore, we hypothesized that SCs may play an important role in regulating MSC proliferation and differentiation through the paracrine signaling pathway. We demonstrate that MSCs and SCs both express hedgehog (Hh) pathway components, including its ligands, receptors, and target genes. Transwell co-cultures of SCs and MSCs showed that the SCs produced sonic hedgehog (Shh), which enhanced the proliferation and differentiation of MSCs. These findings demonstrate that SCs indirectly modulate the activity of MSCs in vitro via the Hh pathway, and provide a plausible explanation for the mechanisms of transplanted MSCs in the treatment of liver fibrosis.     

Cu2+对离体培养猪腺垂体细胞GH分泌的影响

目的：研究铜离子（Cu2＋）对离体培养猪腺垂体细胞生长激素（GH）分泌的影响。方法：试验选取32-35日龄仔猪腺垂体细胞,于10%小牛血清的Dulbecco MEM培养液（DMEM）中离体培养48 h。之后用含不同浓度Cu2＋（0 mg/L、0.025 mg/L、0.1 mg/L、0.4 mg/L、1.6 mg/L）的无小牛血清DMEM培养液培养36 h,于12 h、24 h、36 h收集细胞培养液,用Linco公司的试剂盒及放射免疫法测定培养液中GH浓度。结果：铜离子离体培养腺垂体细胞24 h,0.025 mg/L、0.1 mg/L、0.4 mg/L组培养液中GH浓度均高于0 mg/L组,其中0.1 mg/L组与0 mg/L组差异显著（P〈0.05）。结论：铜离子可促进离体培养猪腺垂体细胞分泌GH。     

蛋白质代谢、折叠、运输、定位、装配相关基因在大鼠肝再生中表达变化

为在基因转录水平了解蛋白质代谢、折叠、运输、定位、装配相关基因在大鼠肝再生中表达情况和作用,本文用搜集网站资料和查阅相关论文等方法获得上述基因,用Rat Genome 2302.0芯片检测它们在大鼠再生肝中表达情况,用真、假手术比较方法确定肝再生相关基因。初步证实上述基因中1147个基因与肝再生相关。其中,参与蛋白质代谢、折叠、运输、定位和装配的基因以上调表达为主;参与蛋白质代谢的基因主要在部分肝切除（partial hepatectomy,PH）后0.5-1h和16-30h起始表达;0.5-12h表达的促进蛋白降解基因数多于促进蛋白积累基因数,而16-48h表达的促进蛋白质积累基因数显著多于促进蛋白质降解基因数;蛋白质合成相关基因在肝再生的16、24、42和66h表达上调较多,在42h最多;几乎在整个肝再生中蛋白质降解相关基因表达上调,在早、前期较多,在后期较少;蛋白质折叠相关基因在2、16-24、42、66、72和168h表达上调较多,在66h最多;蛋白质运输和定位相关基因在整个肝再生中表达上调,在66h表达上调最多;蛋白质装配相关基因在96h前均表达上调,其中,12h表达上调基因最多。根据上述结果推测,在肝再生中期蛋白质合成旺盛,几乎整个肝再生中蛋白质降解、折叠、运输定位和装配活动活跃。     

The Arabidopsis Rop2 GTPase is a positive regulator of both root hair initiation and tip growth

Root hairs provide a model system for the study of cell polarity. We examined the possibility that one or more members of the distinct plant subfamily of RHO monomeric GTPases, termed Rop, may function as molecular switches regulating root hair growth. Specific Rops are known to control polar growth in pollen tubes. Overexpressing Rop2 (Rop2 OX) resulted in a strong root hair phenotype, whereas overexpressing Rop7 appeared to inhibit root hair tip growth. Overexpressing Rops from other phylogenetic subgroups of Rop did not give a root hair phenotype. We confirmed that Rop2 was expressed throughout hair development. Rop2 OX and constitutively active GTP-bound rop2 (CA-rop2) led to additional and misplaced hairs on the cell surface as well as longer hairs. Furthermore, CA-rop2 depolarized root hair tip growth, whereas Rop2 OX resulted in hairs with multiple tips. Dominant negative GDP-bound Rop2 reduced the number of hair-forming sites and led to shorter and wavy hairs. Green fluorescent protein-Rop2 localized to the future site of hair formation well before swelling formation and to the tip throughout hair development. We conclude that the Arabidopsis Rop2 GTPase acts as a positive regulatory switch in the earliest visible stage in hair development, swelling formation, and in tip growth.     

胆固醇逆向转运的分子机制

胆固醇逆向转运是周围细胞胆固醇转运至肝脏转化、清除的重要生理过程,它在维持机体胆固醇代谢平衡和对抗动脉粥样硬化发生及发展中起重要作用。研究证实胆固醇逆向转运直是高密度脂蛋白在多种生物活性分子参与下,由新生前β－ＨＤＬ到成熟α－ＨＤＬ递变的胆固醇转运及代谢过程。     

含翻译增强子的表达载体pSC34的构建及初步应用

１９８８年Ｏｌｉｎｓ［１］发现Ｔ７噬菌体基因１０的先导序列（Ｔ７ｇ１０Ｌ）具有明显的促进基因翻译的作用．本文构建了含Ｔ７ｇ１０Ｌ的表达载体ｐＳＣ３４,并尝试表达了几个不同类型的基因．１材料与方法１．１菌株大肠杆菌菌株ＴＡＰ１０６为本室储存．ＴＡＰ１０...     

人骨保护素(OPG)重组腺病毒的制备及其生物活性研究

采用RT-PCR法得到人OPG的编码区cDNA,克隆至穿梭质粒pShuttle,构建重组有OPG编码区cDNA的腺病毒DNA,经Pac I 酶切线性化,在脂质体介导下转染HEK293细胞,制备重组腺病毒并测定病毒滴度约为5×10⁶～1.5×10⁷ pfu/mL。体外感染小鼠成肌细胞C2C12,Western blot及ELISA检测证实有OPG蛋白的表达,并可在细胞培养上清中持续表达6周。感染OPG重组腺病毒的C2C12细胞生长状态良好、细胞周期无明显变化。将重组腺病毒加入体外培养的小鼠骨髓细胞的培养基中,诱导形成的破骨细胞数量及在象牙片上形成的吸收陷窝的数量显著减少（P<0.01）。      

协同刺激分子与疾病

在T细胞表面受体中,除TCR外,协同刺激分子在调节T细胞的免疫反应中起关键性作用,目前较熟悉的协同刺激分子及其配体有：CD40／CD40L、B7—1／B7-2-CD28／CTLA-4、ICOS—B7RP-1。最近人们又发现了CD2-LFA3、CD5-CD5L、4—1BB／4—1BBL、HAS等新的协同刺激分子组合,它们在器官移植、肿瘤治疗、自身免疫病的治疗方面有重要作用;在基础研究中则可用于T细胞与B细胞分化、活化机制、抗原递呈、协同刺激机制、免疫耐受、移植排异反应和自体免疫等的研究。