Expression system for <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis> based on a promoter of the mitochondrial potential-dependent porin VDAC gene

In this study, we designed an expression system for the Y. lipolytica yeast, which can be fully efficient in media with non-standard industrial ingredients. Previously, we reported that the mitochondrial Voltage Dependent Anion Channel (VDAC) was a major protein overproduced in the Yarrowia lipolytica yeast in an alkaline (pH = 9.0) culture medium. In this study, the VDAC promoter was cloned and tested using a reporter system based on the LacZ gene. Naturally, the VDAC gene contains an intron located just within the ATG translation initiation codon. The VDAC promoter V2 variant with the intron and V3 variant without the intron were studied. The VDAC-driven clones exhibited high variability of the expression profile. Some clones were more active than the clones induced by the artificial hp4d promoter, when grown in both complete and low-cost industrial ingredient (10% fish and sunflower meal) containing media. The new expression system may greatly expand the range of recombinant producers of feed enzymes and some other types of fodder additives in the Y. lipolytica yeast, appropriate for assimilation of low-cost and non-standard raw material.     

<Emphasis Type="Italic">Camellia nanningensis</Emphasis> sp. nov.: the earliest fossil wood record of the genus <Emphasis Type="Italic">Camellia</Emphasis> (Theaceae) from East Asia

A new species Camellia nanningensis was described on the basis of well-preserved mummified wood from the upper Oligocene Yongning Formation of Nanning Basin in Guangxi Province, South China. This represents the most ancient fossil wood assigned to Camellia, and the earliest fossil record of the family Theaceae in China. This fossil material shows that Camellia occurred in China as early as the late Oligocene, suggesting more ancient radiation of this genus than estimated by molecular dating.     

陕西秦岭平河梁自然保护区小型兽类的组成与分布

2005年9月利用铗日法辅以陷阱法对位于秦岭山脉南坡东段的平河梁自然保护区及牛背梁自然保护区小型兽类进行了调查,共设置采集点10个;2460铗日中共捕获小型兽类689只,隶属于3目6科19属27种(另有两种鼢鼠和一种鼯鼠系其他手段捕获),平均捕获率28.01%。对捕获的27种小型兽类生态和垂直分布进行分析结果表明:平河梁保护区3个群落的Shannon-Weiner多样性指数在2.9288-3.3639之间,Pielou均匀性指数在0.7669-0.8602之间。在上述调查的基础上,结合前人对邻近地区的调查,据一些物种的分布特点,订出平河梁自然保护区小型兽类的名录,计48种,结果显示秦岭南坡东段小型兽类的物种多样性和丰富度要高于秦岭其他地区。另在考察中采集到白尾鼹(Parascaptor leucura)、小纹背鼩鼱(Sorex bedfordiae)、斯氏鼢鼠(Myospalaxsmithii)、川西白腹鼠(Niviventer excelsior),在秦岭山区尚属首次记录。还整理了秦岭南坡小型兽类名录,认为秦岭南坡有小型兽类55种,在动物地理区划上应属于西南区。     

Structural and thermodynamic properties of starches extracted from GBSS and GWD suppressed potato lines

A combined DSC–SAXS approach was employed to study the effects of amylose and phosphate esters on the assembly structures of amylopectin in B-type polymorphic potato tuber starches. Amylose and phosphate levels in the starches were specifically engineered by antisense suppression of the granule bound starch synthase (GBSS) and the glucan water dikinase (GWD), respectively. Joint analysis of the SAXS and DSC data for the engineered starches revealed that the sizes of amylopectin clusters, thickness of crystalline lamellae and the polymorphous structure type remained unchanged. However, differences were found in the structural organization of amylopectin clusters reflected in localization of amylose within these supramolecular structures. Additionally, data for annealed starches shows that investigated potato starches possess different types of amylopectin defects. The relationship between structure of investigated potato starches and their thermodynamic properties was recognized.     

Modified LDLs induce proliferation-mediated death of human vascular endothelial cells through MAPK pathway

The ability of modified low-density lipoptoteins (LDLs) to induce both proliferation and death of endothelial cells is considered to be a mechanism of early atherosclerosis development. We previously showed that carbamylated LDL (cLDL) induces human coronary artery endothelial cell (HCAEC) death in vitro. This effect is similar to the atherogenic action of oxidized LDL (oxLDL) that induces the proliferation and death of endothelial cells. The present study was designed to analyze a potential proliferative effect of cLDL and whether proliferation caused by modified LDLs is related to cell death. Cultured HCAECs were exposed to different concentrations of modified LDL or native LDL for varying periods of time. Cell proliferation measured by bromodeoxyuridine incorporation and S-phase analysis was dose-dependently increased in the presence of cLDL (6.25-200 microg/ml). The proliferation induced by cLDL or oxLDL was associated with cell death and increased phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun NH(2)-terminal kinase (JNK). Inhibition of cLDL- or oxLDL-induced proliferation by aphidicolin (1 microg/ml) was protective against both short-term cell death measured by lactate dehydrogenase release into the medium and long-term cell viability visualized by cell multiplication. Inhibition of ERK phosphorylation led to a significant decrease of DNA synthesis and cell rescue from injury by modified LDLs, while inhibition of JNK phosphorylation had an only partial rescue effect without involvement in cell proliferation. These data are the first evidence that endothelial cell death induced by cLDL or oxLDL is mediated by cell proliferation through the mitogen-activated protein kinase pathway.     

Global gene expression profiling reveals similarities and differences among mouse pluripotent stem cells of different origins and strains

Pluripotent stem cell lines with similar phenotypes can be derived from both blastocysts (embryonic stem cells, ESC) and primordial germ cells (embryonic germ cells, EGC). Here, we present a compendium DNA microarray analysis of multiple mouse ESCs and EGCs from different genetic backgrounds (strains 129 and C57BL/6) cultured under standard conditions and in differentiation-promoting conditions by the withdrawal of Leukemia Inhibitory Factor (LIF) or treatment with retinoic acid (RA). All pluripotent cell lines showed similar gene expression patterns, which separated them clearly from other tissue stem cells with lower developmental potency. Differences between pluripotent lines derived from different sources (ESC vs. EGC) were smaller than differences between lines derived from different mouse strains (129 vs. C57BL/6). Even in the differentiation-promoting conditions, these pluripotent cells showed the same general trends of gene expression changes regardless of their origin and genetic background. These data indicate that ESCs and EGCs are indistinguishable based on global gene expression patterns alone. On the other hand, a detailed comparison between a group of ESC lines and a group of EGC lines identified 20 signature genes whose average expression levels were consistently higher in ESC lines, and 84 signature genes whose average expression levels were consistently higher in EGC lines, irrespective of mouse strains. Similar analysis identified 250 signature genes whose average expression levels were consistently higher in a group of 129 cell lines, and 337 signature genes whose average expression levels were consistently higher in a group of C57BL/6 cell lines. Although none of the genes was exclusively expressed in either ESCs versus EGCs or 129 versus C57BL/6, in combination these signature genes provide a reliable separation and identification of each cell type. Differentiation-promoting conditions also revealed some minor differences between the cell lines. For example, in the presence of RA, EGCs showed a lower expression of muscle- and cardiac-related genes and a higher expression of gonad-related genes than ESCs. Taken together, the results provide a rich source of information about the similarities and differences between ESCs and EGCs as well as 129 lines and C57BL/6 lines. Such information will be crucial to our understanding of pluripotent stem cells. The results also underscore the importance of studying multiple cell lines from different strains when making comparisons based on gene expression analysis.     

Innovative proteomic approaches for cancer biomarker discovery

Substantial technological advances in proteomics and related computational science have been made in the past few years. These advances overcome in part the complexity and heterogeneity of the human proteome, permitting quantitative analysis and identification of protein changes associated with tumor development. Here, we discuss some of these advances that are uncovering new cancer biomarkers that have potential to detect cancer at early and curable stages and address remaining challenges.