H2S, endoplasmic reticulum stress, and apoptosis of insulin-secreting beta cells

Cystathionine gamma-lyase (CSE) is a key enzyme in the trans-sulfuration pathway, which uses L-cysteine to produce hydrogen sulfide (H2S). Functional changes of pancreatic beta cells induced by endogenous H2S have been reported, but the effect of the CSE/H2S system on pancreatic beta cell survival has not been known. In this study, we demonstrate that H2Sat physiologically relevant concentrations induced apoptosis of INS-1E cells, an insulin-secreting beta cell line. Transfection of INS-1E cells with a recombinant defective adenovirus containing the CSE gene (Ad-CSE) resulted in a significant increase in CSE expression and H2S production. Ad-CSE transfection also stimulated apoptosis. The other two end products of CSE-catalyzed enzymatic reaction, ammonium and pyruvate, had no effects on INS-1E cell apoptosis, indicating that overexpression of CSE may stimulate INS-1E cell apoptosis via increased endogenous production of H2S. Both exogenous H2S (100 microM) and Ad-CSE transfection inhibited ERK1/2 but activated p38 MAPK. Interestingly, BiP and CHOP, two indicators of endoplasmic reticulum (ER) stress, were up-regulated in H2S-and CSE-mediated apoptosis in INS-1E cells. After suppressing CHOP mRNA expression, H2S-induced apoptosis of INS-1E cells was significantly decreased. Inhibition of p38 MAPK, but not of ERK1/2, inhibited the expression of BiP and CHOP and decreased H2S-stimulated apoptosis, suggesting that p38 MAPK activation functions upstream of ER stress to initiate H2S-induced apoptosis. It is concluded that H2S induces apoptosis of insulin-secreting beta cells by enhancing ER stress via p38 MAPK activation. Our findings may help unmask a novel role of CSE/H2S system in regulating pancreatic functions under physiological condition and in diabetes.     

In vitro formation of lacuna structure by human dermal fibroblasts co-cultured with porcine chondrocytes on a 3D biodegradable scaffold

Dermal fibroblasts (DF) possess chondrogenic differentiation potential but whether DF, or a subpopulation of DF, can form a typical cartilage structure in culture is unknown. In this study, human DF were co-cultured with porcine articular chondrocytes on a biodegradable scaffold of polylactic acid/polyglycolic acid. Histological analysis demonstrated that some DFs can be induced to form cartilage lacuna structure showing the existence of a chondrogenic subpopulation of human DF. Moreover, the 3D-co-culture system can serve as an optimal model for directing stem cell differentiation in vitro. Xia Liu and Guangdong Zhou contributed equally to this work.     

A modified piggybac transposon system mediated by exogenous mRNA to perform gene delivery in bovine mammary epithelial cells

Transposons are widely used for genetic engineering in various model organisms. Recently, piggyBac (PB) has been developed as a transposable and efficient gene transfer tool in mammalian cells. In the present study, we developed three types of PB transposon systems containing a dual plasmid system (DPS), a single plasmid system (SPS), and a DNA-mRNA combined system (DRPS) and characterized their basic properties in HEK293 cells. The basic elements of the donor plasmid included a selectable-reporter gene expression cassette, two loxP sites in the same orientation, a multiple cloning site, and two chicken β-globin insulator core elements. We further identified the function of the selectable-reporter and examined PB integration sites in the human genome. Moreover, we compared the transposition efficacy and found that SPS transposed more efficiently, as compared to DPS; integration into the host genome was determined by measuring PBase activity. Results discovered the loss of PBase activity in the DRPS, indicating that this system is much more biologically safe, as compared to DPS and SPS. Finally, we employed the DRPS to successfully perform a gene delivery into bovine mammary epithelial cells (BMECs). Taken together, the information from this study will improve the flexibility of PB transposon systems and reduce the genotoxicity of PBase in genetic engineering.     

二倍体和四倍体杂交兰幼苗对低温胁迫的生理响应差异分析

为探究不同倍性杂交兰（Cymbidium hybrid）对低温胁迫的生理响应差异,对低温胁迫下（昼温10℃、夜温4℃）二倍体杂交兰以及四倍体杂交兰株系T1和T2幼苗叶片中脯氨酸、可溶性糖、可溶性蛋白质、MDA和叶绿素含量,O-·2产生速率以及SOD、POD和CAT活性的动态变化进行了测定和分析;在此基础上,比较了二倍体和四倍体杂交兰的耐低温特性差异。结果显示：随着胁迫时间的延长,二倍体杂交兰和四倍体杂交兰株系T1和T2幼苗叶片中脯氨酸、可溶性糖、可溶性蛋白质和MDA含量,O-·2产生速率以及POD和CAT活性总体呈逐渐增加的趋势;叶绿素含量呈逐渐下降的趋势;SOD活性呈先上升后下降的趋势,并分别在胁迫后第9天和第6天达到峰值。在常温（25℃）下恢复生长3d后,二倍体杂交兰和四倍体杂交兰株系T1和T2幼苗叶片中脯氨酸、可溶性糖、可溶性蛋白质和MDA含量,O-·2产生速率以及SOD、POD和CAT活性均降低,而叶绿素含量升高。总体上,二倍体杂交兰叶片中脯氨酸、可溶性糖和可溶性蛋白质含量以及SOD、POD和CAT活性的增幅明显小于四倍体杂交兰,MDA含量和O-·2产生速率的增幅则大于四倍体杂交兰,而叶绿素含量的降幅则明显大于四倍体杂交兰。综合分析结果表明：在低温胁迫下,四倍体杂交兰叶片中渗透调节物质含量和保护酶活性均较高,其对低温的耐性强于二倍体杂交兰。     

Density functional theory calculations on the thermodynamic properties of polynitrosoprismanes

A series of polynitrosoprismanes, C(6)H(6 - n )(NO)( n ) (n?=?1-6), considered as high energy density compounds (HEDCs), have been designed computationally. We calculated the electronic structures, the heats of formation, the specific enthalpies of combustion, the bond dissociation energies, and the strain energies of the title compounds using density functional theory (DFT) with the 6-311G** basis set. It was found that the ΔE (LUMO-HOMO) values of the title compounds decrease as the number of nitroso groups increase, and the energy gaps of the prismane derivatives are much lower than that of TATB. Their high positive heats of formation indicate that polynitrosoprismanes can store a great deal of energy. Furthermore, the HOFs for the nitrosoprismane series were observed to decrease until three nitroso groups were connected to the prismane skeleton. For the polynitrosoprismanes, the trigger bond was confirmed to be the C-C bond in the skeleton. According to our calculations, all nitrosoprismanes appear to have large strain energies, and these calculations can provide basic information that may prove useful for the molecular design of novel high energy density materials.     

辽宁西部早三叠世苏铁植物一新属--Mediocycas gen. nov.及其演化意义

报道苏铁植物大孢子叶化石一新属———中间苏铁属(Mediocycasgen.nov.)。标本采集于辽宁省西部,喀左县杨树沟煤矿后山的早三叠世红砬组。这些标本以前曾被处理为疑问化石(Problematicum)。因当时资料不足,所以没有确定属种名称。但鉴于这些化石在苏铁类早期起源与演化研究中具有重要意义,故对它们作了重新研究。文中除了以喀左中间苏铁(Mediocycaskazuoensisgen.etsp.nov.)为典型种进行描述以外,还对新属、种在苏铁类起源与演化方面的意义作了较为详细的讨论。     

应用参数和辅助剂对昆虫病原线虫Steinernema carpocapsae All品系于小白菜叶面存活和黏附数量的影响

测定了叶面应用参数(喷雾压力、高度、线虫悬浮液浓度、线虫悬液量、温度和湿度)以及辅助剂对昆虫病原线虫S．carpocapsaeAll于小白菜叶面的存活率和叶面黏附数量的影响。结果显示：(1)喷雾压力对线虫于叶面的黏附数量有负影响;(2)线虫悬浮液浓度高于2000IJs／mL时,随着线虫浓度的增加,叶面上黏附的线虫数量也明显提高;(3)喷洒的线虫悬液量越多(从3．3mL到19．8mL),叶面上黏附的线虫数量也就越多(从10．1IJs／cm^2到45．5IJs／cm^2),但是当线虫悬液量超出19．8mL时,叶面上黏附的线虫数量不再提高;(4)感染期线虫在叶面存活率随着暴露时间的增长而下降;(6)加入黄原胶和表面活性剂可以提高线虫在叶面的存活率和黏附数量,其中加入0．3％黄原胶的线虫悬浮液在叶面存活的线虫数量是清水对照的150倍。线虫喷洒叶面停留24小时后,2％甘油的线虫悬浮液的线虫在叶面上的存活率大约是清水对照液的62倍,叶面上存活线虫数量也是清水对照液的53倍。     

附丝壳属西藏一新记录种(英文)

武夷附丝壳寄生在冬青属植物的叶上 ,是我国西藏首次报道的附丝壳属种类。     

植物源异戊二烯及其生态意义

异戊二烯为植物挥的众多有机碳氢化合物中的主要成分,它的合成和释放对全球尺度上的C素平衡、温室效应的大气污染都有极其重要的作用。本文系统论述了影响异戊二烯释放的主要因子,异戊二烯的释放量及其计量方法,以及它可能的生态意义,指出了研究多重环境胁迫与异戊二烯合成和释放的关系的必要性。