Role of ATP and disulphide bonds during protein folding in the endoplasmic reticulum.

Being topologically equivalent to the extracellular space, the lumen of the endoplasmic reticulum (ER) provides a unique folding environment for newly synthesized proteins. Unlike other compartments in the cell where folding occurs, the ER is oxidizing and therefore can promote the formation of disulphide bonds. The reducing agent dithiothreitol, when added to living cells, inhibits disulphide formation with profound effects on folding. Taking advantage of this effect, we demonstrate here that folding of influenza haemagglutinin is energy dependent. Metabolic energy is required to support the correct folding and disulphide bond formation in this well characterized viral glycoprotein, to rescue misfolded proteins from disulphide-linked aggregates, and to maintain the oxidized protein in its folded and oligomerization-competent state.     

含极大循环阵的8维类置换阵群

如果一个群里的任意一个矩阵相似于一个置换阵, 称这个矩阵群为类置换群. 此群相似于一个置换阵群. 本文利用群作用轨道的不变集刻画了8 维类置换阵群各个元素的表示矩阵, 利用这个结论证明了若此类置换阵群包含一个极大循环正规子群时, 则其相似于一个置换群.     

Sea-level fluctuations during the last glacial cycle

The last glacial cycle was characterized by substantial millennial-scale climate fluctuations, but the extent of any associated changes in global sea level (or, equivalently, ice volume) remains elusive. Highstands of sea level can be reconstructed from dated fossil coral reef terraces, and these data are complemented by a compilation of global sea-level estimates based on deep-sea oxygen isotope ratios at millennial-scale resolution or higher. Records based on oxygen isotopes, however, contain uncertainties in the range of +/-30 m, or +/-1 degrees C in deep sea temperature. Here we analyse oxygen isotope records from Red Sea sediment cores to reconstruct the history of water residence times in the Red Sea. We then use a hydraulic model of the water exchange between the Red Sea and the world ocean to derive the sill depth-and hence global sea level-over the past 470,000 years (470 kyr). Our reconstruction is accurate to within +/-12 m, and gives a centennial-scale resolution from 70 to 25 kyr before present. We find that sea-level changes of up to 35 m, at rates of up to 2 cm yr(-1), occurred, coincident with abrupt changes in climate.     

BMP2，BMP4及BMP信号通路相关成员在发情周期小鼠子宫中的表达

研究目的：研究骨形态发生蛋白（BMP）2,4及BMP信号通路相关成员在发情周期小鼠子宫中的表达模式。创新要点：运用实时荧光定量聚合酶链式反应（PCR）系统地研究了Bmp2和Bmp4及其BMP信号通路相关成员在小鼠子宫中mRNA水平表达模式,同时运用免疫组化方法研究了BMP2蛋白在小鼠子宫中的定位模式。研究方法：重要结论：收集发情周期各个时期小鼠子宫,一侧子宫角贮存于液氮或-80℃冰箱用于实时荧光定量PCR,另一侧子宫角用40mg／ml多聚甲醛固定用于BMP2蛋白免疫组化定位。实时荧光定量PCR结果表明,Bmp2的表达水平在发情前期显著高于发情期和发情后期（P〈0．05）,Bmp4的表达水平呈现显著波动,但Bmp2与Bmp4差异不显著（P〉0．05）。Bmprla和Bmpr2的表达水平在整个发情周期无显著变化（P〉0．05）。然而,Bmprlb的mRNA水平在发情期显著下降（P〈0．05）,在发情后期上升。此外,Bmprlb的mRNA水平显著低于相应时期Bmprla和Bmpr2的mRNA水平（P〈0．05）。三种R—Smads差异地表达于小鼠子宫,并且Smad1和Smad5的表达水平显著高于Smad8（P〈0．05）。此外,Smad4的表达水平在整个发情周期无显著变化。免疫组化结果显示,BMP2蛋白在整个发情周期差异表达,并主要定位于子宫腔上皮细胞和腺上皮细胞。我们的结果提供了BMP2和BMP4及其BMP信号通路相关成员mRNA水平表达变化信息,这些数据为论证BMP在子宫内膜中的作用如子宫内膜的退化与重塑提供量化和有用的信息。     

Dynamics and functions of the actin cytoskeleton during the plant cell cycle

In eukaryotic cells, the course of the cell cycle depends on correct cytoskeleton arrangement. The cell cycle consists of several phases, and in each of them the cytoskeleton has a unique structure and set of characteristics. The dynamics of the cytoskeleton together with its binding proteins greatly contribute to progression of the cell cycle. Here, we mainly review recent research on the dynamic distribution of the actin cytoskeleton and actin-binding proteins, and the mechanisms by which they affect the ...