Cardiac mitochondrial ATP-sensitive potassium channel is activated by nitric oxide in vitro

Previous observations on the activation of the mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) by nitric oxide (NO) in myocardial preconditioning were based on indirect evidence. In this study, we have investigated the direct effect of NO on the rat cardiac mitoK(ATP) after reconstitution of the inner mitochondrial membranes into lipid bilayers. We found that the mitoK(ATP) was activated by exogenous NO donor S-nitroso-N-acetyl penicillamine or PAPA NONOate. This activation was inhibited by mitoK(ATP) blockers 5-hydroxydecanoate or glibenclamide. Our observations confirm that NO can directly activate the cardiac mitoK(ATP), which may underlie its contribution to myocardial preconditioning.     

苏铁Cycas revoluta珊瑚根内生真菌的多样性

苏铁类植物是目前发现的唯一一类具有珊瑚根结构的裸子植物,是探究植物-微生物互作的理想材料。本研究通过高通量测序技术对中国13个地区栽培苏铁Cycas revoluta珊瑚根中的内生真菌组成及多样性进行分析,结果表明苏铁内生真菌多样性较高,但各地区间内生真菌的组成及多样性差异不显著,显示苏铁和珊瑚根内生真菌的共生与栽培地无关。     

Measurements of peripheral and deep body temperature in cattle – A review

Automation of the measurement of the physiological and behavioural parameters of livestock has become an important goal for both scientists and farmers. Accurate data and knowledge about farmed animals, especially in cattle breeding, are needed. Proper early diagnosis of a cow's health status in real time allows for preventing the development of infection, oestrus detection and leads to reduced environmental stress. Thus, it contributes to more effective herd management. Among the physiological parameters, body temperature and its fluctuations are key indicators of health and well-being in animals. Currently, along with the development of technical solutions and their implementation, increasingly more attention is being paid to the continuously measurement of body core and peripheral temperature in animals. Recently there has been an increased number of publications devoted to this subject. However, there is a need to systematise this knowledge as these studies have had different purposes, have been performed in various environmental conditions, and the measurements were taken using different methods and equipment. As such, the results obtained by the different authors often may not be comparable. For this reason, this paper has two main purposes: to present the most widely used continuous methods of peripheral and body core temperature measurement, and to show its references values which characterise the individual locations of the cattle body in thermoneutral ambient. An analysis of the professional publications regarding measurements of peripheral and deep body temperature led to the conclusion that these methods have high research and diagnostic potential. However, it is necessary to standardised research to enable better and more comparable results, including among others; different cattle groups, animal age, health and environmental conditions.     

Structural variability of DNA-containing Mg-pyrophosphate microparticles: optimized conditions to produce particles with desired size and morphology

Our previous studies demonstrated the formation of structurally diverse DNA-containing microparticles (DNA MPs) in PCR with Mg-pyrophosphate (MgPPi) as the structure-forming component. These DNA MPs were referred to major structural types: microdisks (2D MPs) with nanometer thickness and 3D MPs with sophisticated morphology and constructed from intersecting disks and their segments. Little is known about factors that influence both the morphology and size of DNA MPs, and the present study was aimed at fulfilling this gap. We showed that the addition of Mn²⁺ cations to PCR mixtures caused the profound changes in MPs morphology, depending on DNA polymerase used (KlenTaq or Taq). Asymmetric PCR with 20-fold decrease in the concentration of one of two primers facilitated the predominant formation of microdisks with unusual structure. The addition of 1 mM Na-pyrophosphate to PCR mixtures with synthesized DNA and subsequent thermal cycling (10–15 cycles) were optimal to produce microdisks or nanometer 3D particles. Using electron microscopy, we studied also the structure of inorganic micro- and nanoparticles from MgPPi, formed during multiple heating and cooling cycles of a mixture of Mg²⁺ and Na-pyrophosphate in various regimes. Also, we found the conditions to yield planar (Mg·Mn)PPi nanocrystals (diameter ~100 nm and thickness ~10 nm) which efficiently adsorbed exogenous DNA. These inorganic nanoparticles are promising for DNA delivery in transfection studies. Mechanisms to be involved in structural modifications of MPs and perspectives of their practical application are discussed.     

基于农艺性状指标的山西高粱地方品种核心种质构建

利用1285份山西省高粱地方品种18个农艺性状的历史数据,通过比较不同取样方法、取样比例和聚类方法组合的构建方法,确定了"多次聚类偏离度取样法+15％取样比例+欧氏距离+最长距离法"为山西省高粱地方核心种质构建的方法.192份初选核心种质和所有样本的均值差异百分率、方差差异百分率、极差符合率和变异系数变化率分别为0、8...     

应用高效体积排阻色谱偶联多角度激光散射鉴定猪圆环病毒2型灭活疫苗及病毒样颗粒疫苗抗原

本文旨在建立基于高效体积排阻色谱(high-performance size-exclusion chromatography,HPSEC)偶联多角度激光散射仪(multi-angle laser light scattering,MALLS)的猪圆环病毒2型(porcine circovirus type 2,PCV2)疫苗抗原检测方法。以纯化的PCV2灭活病毒及病毒样颗粒(virus-like particles,VLP)为参照,对4家生产企业的2种PCV2灭活病毒疫苗(a、b)及VLP疫苗(c、d)破乳后进行HPSEC-MALLS检测及分子量分析;结合PCV2抗原检测卡、Western blotting和透射电子显微镜(transmission electron microscope,TEM),鉴定了特征色谱峰;考察了方法的重复性和检测线性。结果表明,两家企业生产的PCV2灭活病毒疫苗破乳液水相经HPSEC分离,在保留时间约13.3 min处出现抗原特征峰;MALLS计算该色谱峰分子量分别为2.61×10⁶(±4.34%) Da和2.40×10⁶(±2.51%) Da。两种VLP疫苗也在13.3 min处出现抗原特征峰,分子量分别为2.09×10⁶(±2.94%) Da和2.88×10⁶(±11.85%) Da,接近PCV2的理论分子量;同时在保留时间约11.4 min处也出现色谱峰,经检测分子量为4.37×10⁶(±0.42%) Da,TEM表征显示为VLP二聚体。取疫苗d和PCV2 VLP纯品进行重复检测,抗原色谱峰面积的RSD(n=3)均小于1.5%,重复性好;将PCV2 VLP纯品梯度稀释检测,VLP及其多聚体的色谱峰面积与浓度均呈良好的线性关系,R²分别为0.999及0.997,能够满足定量及多聚体含量分析。该方法有望成为一种准确、高效的PCV2疫苗的体外评价方法,用于质量评价与提升。     

Mechanism of proteasome gate modulation by assembly chaperones Pba1 and Pba2

The active sites of the proteasome are housed within its central core particle (CP), a barrel-shaped chamber of four stacked heptameric rings, and access of substrates to the CP interior is mediated by gates at either axial end. These gates are constitutively closed and may be opened by the regulatory particle (RP), which binds the CP and facilitates substrate degradation. We recently showed that the heterodimeric CP assembly chaperones Pba1/2 also mediate gate opening through an unexpected structural arrangement that facilitates the insertion of the N terminus of Pba1 into the CP interior; however, the full mechanism of Pba1/2-mediated gate opening is unclear. Here, we report a detailed analysis of CP gate modulation by Pba1/2. The clustering of key residues at the interface between neighboring α-subunits is a critical feature of RP-mediated gate opening, and we find that Pba1/2 recapitulate this strategy. Unlike RP, which inserts at six α-subunit interfaces, Pba1/2 insert at only two α-subunit interfaces. Nevertheless, Pba1/2 are able to regulate six of the seven interfacial clusters, largely through direct interactions. The N terminus of Pba1 also physically interacts with the center of the gate, disrupting the intersubunit contacts that maintain the closed state. This novel mechanism of gate modulation appears to be unique to Pba1/2 and therefore likely occurs only during proteasome assembly. Our data suggest that release of Pba1/2 at the conclusion of assembly is what allows the nascent CP to assume its mature gate conformation, which is primarily closed, until activated by RP.     

Rotamer strain as a determinant of protein structural specificity

We present direct evidence for a change in protein structural specificity due to hydrophobic core packing. High resolution structural analysis of a designed core variant of ubiquitin reveals that the protein is in slow exchange between two conformations. Examination of side-chain rotamers indicates that this dynamic response and the lower stability of the protein are coupled to greater strain and mobility in the core. The results suggest that manipulating the level of side-chain strain may be one way of fine tuning the stability and specificity of proteins.     

8-Hydroxyguanosine formed in human lung tissues and the association with diesel exhaust particles

Diesel exhaust particles consist of various organic chemicals, heavy metals, and carbon particles. Knowledge of the fate of organic chemicals and carbon particles in the lungs is important to determine the mechanisms responsible for lung tumors. In the present study, diesel particle extracts were found to show mutagenicity for YG3003, a sensitive strain to some oxidative mutagens, as well as other mutant strains, and those of lung tissues obtained from lung cancer patients exhibited potent mutagenicity. Formation of 8-hydroxyguanosine (8-OHdG) as a biomarker of oxidative damage was analyzed with in vitro and in vivo assay systems. The 8-OHdG was detected in all 22 cases of lung tissues with carcinomas tested and their levels increased with the increasing age of the patients, suggesting a correlation between age and the presence of carbon particles in lung tissues. Therefore, the formation of 8-OHdG due to diesel exhaust particles was investigated via intratracheal injections into mice. 8-OHdG formation was elevated when carboneceous particles, after removal of organic chemicals with various solvents, were administered to mice, but it was not elevated when polyaromatic compounds such as benzo[a]pyrene, 1,8-dinitropyrene, and 1-nitropyrene were used in the same procedure in mice. The carboneceous particles were formed from a giant particle that was aggregated by micro-particles with diameters of 1.47 +/- 1.34 to 1.05 +/- 0.83 microm. These results suggest that carboneceous particles, but not mutagens and carcinogens, promote the formation of 8-OHdG, and that as a mechanism, alveolar macrophages may be involved in oxidative damage. The oxidative damage may be due to the fact that the mutation is involved with the generation of a hydroxyl radical during phagocytosis, and the hydroxyl radical leads to hydroxylation at the C-8 position of the deoxyguanosine residue in the DNA.     

The use of ferromagnetic Dacron as solid-phase in chemiluminescent assays

Ferromagnetic Dacron hydrazide particles (63–74 m) were activated either by converting hydrazide groups to azide or binding glutaraldehyde to the hydrazide groups. Human serum albumin (HSA) was immobilised to the activated matrices and antibodies against HSA were detected by using the chemiluminescent assay. The use of these particles (either Dacron-azide or Dacron-glutaraldehyde) gave similar results compared with the paramagnetic particles commercially available from Ciba Corning.