Stay in touch with the endoplasmic reticulum

The endoplasmic reticulum(ER),which is composed of a continuous network of tubules and sheets,forms the most widely distributed membrane system in eukaryotic cells.As a result,it engages a variety of organelles by establishing membrane contact sites(MCSs).These contacts regulate organelle positioning and remodeling,including fusion and fission,facilitate precise lipid exchange,and couple vital signaling events.Here,we systematically review recent advances and converging themes on ER-involved org...     

我国草兔的分类研究

草兔(即好望角兔)(Lepus capensis Linnaeus,1758)是我国野兔中的优势种,数量多,分布广,亚种分化多,但长期以来,定名混乱,须重新校定。本篇报导专题讨论了我国草兔的分类学问题,并用电子计算机进行模糊聚类(Fuzzy aggregation),探讨了我国草兔亚种分化的中心。     

MyD88-dependent signaling for IL-15 production plays an important role in maintenance of CD8 alpha alpha TCR alpha beta and TCR gamma delta intestinal intraepithelial lymphocytes

Interaction between commensal bacteria and intestinal epithelial cells (i-ECs) via TLRs is important for intestinal homeostasis. In this study, we found that the numbers of CD8alphaalpha TCRalphabeta and TCRgammadelta intestinal intraepithelial lymphocytes (i-IELs) were significantly decreased in MyD88-deficient (-/-) mice. The expression of IL-15 by i-ECs was severely reduced in MyD88(-/-) mice. Introduction of IL-15 transgene into MyD88(-/-) mice (MyD88(-/-) IL-15 transgenic mice) partly restored the numbers of CD8alphaalpha TCRalphabeta and TCRgammadelta i-IELs. The i-IEL in irradiated wild-type (WT) mice transferred with MyD88(-/-) bone marrow (BM) cells had the same proportions of i-IEL as WT mice, whereas those in irradiated MyD88(-/-) mice transferred with WT BM cells showed significantly reduced proportions of CD8alphaalpha TCRalphabeta and TCRgammadelta i-IELs, as was similar to the proportions found in MyD88(-/-) mice. However, irradiated MyD88(-/-) IL-15 transgenic mice transferred with WT BM cells had increased numbers of CD8alphaalpha TCRalphabeta and TCRgammadelta subsets in the i-IEL. These results suggest that parenchymal cells such as i-ECs contribute to the maintenance of CD8alphaalpha TCRalphabeta and gammadelta i-IELs at least partly via MyD88-dependent IL-15 production.     

In vivo skin penetration and metabolic path of quantum dots

The skin is the largest organ of the body and is a potential route of exposure to sunscreens and cosmetics containing nanoparticles;however,the permeability of the skin to these nanoparticles is currently unknown.In this paper,we studied the transdermal delivery capacity through mouse skin of water-soluble CdSeS quantum dots(QDs) and the deposition of these QDs in the body.QD solution was coated onto the dorsal hairless skin of male ICR mice.Fluorescence microscopy and transmission electron microscopy(TEM) were used to observe the distribution of QDs in the skin and organs,and inductively coupled plasma-mass spectrometry(ICP-MS) was used to measure the 111Cd content to indicate the concentration of QDs in plasma and organs.Experimental results indicate that QDs can penetrate into the dermal layer and are limited to the uppermost stratum corneum layers and the hair follicles.Through blood circulation,QDs deposit mostly in liver and kidney and are difficult to clear.111Cd concentration was greater than 14 ng g-1 in kidney after 120 h after 0.32 nmol QDs was applied to a mouse.These results suggest that QDs have in vivo transdermal delivery capacity through mouse skin and are harmful to the liver and kidney.     

Biochemical characterization of ethanol-dependent reduction of furfural by alcohol dehydrogenases

Lignocellulosic biomass is usually converted to hydrolysates, which consist of sugars and sugar derivatives, such as furfural. Before yeast ferments sugars to ethanol, it reduces toxic furfural to non-inhibitory furfuryl alcohol in a prolonged lag phase. Bioreduction of furfural may shorten the lag phase. Cupriavidus necator JMP134 rapidly reduces furfural with a Zn-dependent alcohol dehydrogenase (FurX) at the expense of ethanol (Li et al. 2011). The mechanism of the ethanol-dependent reduction of furfural by FurX and three homologous alcohol dehydrogenases was investigated. The reduction consisted of two individual reactions: ethanol-dependent reduction of NAD⁺ to NADH and then NADH-dependent reduction of furfural to furfuryl alcohol. The kinetic parameters of the coupled reaction and the individual reactions were determined for the four enzymes. The data indicated that limited NADH was released in the coupled reaction. The enzymes had high affinities for NADH (e.g., K _d of 0.043 μM for the FurX-NADH complex) and relatively low affinities for NAD⁺ (e.g., K _d of 87 μM for FurX-NAD⁺). The kinetic data suggest that the four enzymes are efficient “furfural reductases” with either ethanol or NADH as the reducing power. The standard free energy change (ΔG°′) for ethanol-dependent reduction of furfural was determined to be −1.1 kJ mol⁻¹. The physiological benefit for ethanol-dependent reduction of furfural is likely to replace toxic and recalcitrant furfural with less toxic and more biodegradable acetaldehyde.     

QUARTET突变四倍体拟南芥的获得与表型分析

为了将四分子分析应用于多倍体遗传重组的研究,本研究从qrt1基因突变的二倍体Columbia(Col)与Landsberg erecta(Ler)生态型拟南芥出发,利用秋水仙素诱导核基因组加倍,利用流式细胞技术及荧光原位杂交技术筛选出成功加倍的qrt1基因突变的四倍体Col与Ler生态型拟南芥。并对其进行营养及生殖相关表型分析。首先qrt1突变抑制了侧根数量、基部侧枝数量以及莲座叶片面积。其次,四倍体莲座叶片面积、花粉、花药以及种子更大,侧根及茎基部分枝减少,抽薹时间推迟,每株果荚数与每果荚种子数更少,但种子发芽率都接近100%。倍性还对某些表型的影响具有背景依赖性,如对主茎分支数量、最终株高以及果荚长度的影响在Col与Ler生态型中表现不同。     

Evidence that bacterial ABC-type transporter imports free EDTA for metabolism

EDTA, a common chelating agent, is becoming a major organic pollutant in the form of metal-EDTA complexes in surface waters, partly due to its recalcitrance to biodegradation. Even an EDTA-degrading bacterium, BNC1, does not degrade stable metal-EDTA complexes. In the present study, an ABC-type transporter was identified for possible uptake of EDTA because the transporter genes and the EDTA monooxygenase gene were expressed from a single operon in BNC1. The ABC-type transporter had a periplasmic-binding protein (EppA) that should confer the substrate specificity for the transporter; therefore, EppA was produced in Escherichia coli, purified, and characterized. EppA was shown to bind free EDTA with a dissociation constant as low as 25 nM by using isothermal titration calorimetry. When unstable metal-EDTA complexes, e.g., (Mg-EDTA)²⁻, were added to the EppA solution, binding was also observed. However, experimental data and theoretical analysis supported EppA binding only of free EDTA. When stable metal-EDTA complexes, e.g., (Cu-EDTA)²⁻, were titrated into the EppA solution, no binding was observed. Since EDTA monooxygenase in the cytoplasm uses some of the stable metal-EDTA complexes as substrates, we suggest that the lack of EppA binding and EDTA uptake are responsible for the failure of BNC1 cells to degrade the stable complexes.     

DHA和EPA的研究现状与趋势

本文综述了DHA和EPA的研究背景、生物体内的代谢、生理作用及开发应用,并据此提出今后进一步开展该方面研究的方向。     

呼伦贝尔草原有关布氏田鼠防治方面的某些生物学研究

呼伦贝尔草原,是黑龙江省重要牧业基地;但是,草原鼠害相当猖獗。危害草场的主要害鼠,布氏田鼠(Microtus brandti Radde),目前在呼伦贝尔草原的栖息范围,已遍布新巴尔虎左旗和右旗,且有继续向陈巴尔虎旗和鄂温克族自治旗漫延的趋势。根据新巴尔虎右旗农牧局的初步调查,1971年约有70％的草场遭受不同程度的危害,其中害情严重