Protein kinase C delta null mice exhibit structural alterations in articular surface,intra-articular and subchondral compartments

IntroductionStructural alterations in intra-articular and subchondral compartments are hallmarks of osteoarthritis, a degenerative disease that causes pain and disability in the aging population. Protein kinase C delta (PKC-δ) plays versatile functions in cell growth and differentiation, but its role in the articular cartilage and subchondral bone is not known.MethodsHistological analysis including alcian blue, safranin O staining and fluorochrome labeling were used to reveal structural alterations at the articular cartilage surface and bone–cartilage interface in PKC-δ knockout (KO) mice. The morphology and organization of chondrocytes were studied using confocal microscopy. Glycosaminoglycan content was studied by micromass culture of chondrocytes of PKC-δ KO mice.ResultsWe uncovered atypical structural demarcation between articular cartilage and subchondral bone of PKC-δ KO mice. Histology analyses revealed a thickening of the articular cartilage and calcified bone–cartilage interface, and decreased safranin O staining accompanied by an increase in the number of hypertrophic chondrocytes in the articular cartilage of PKC-δ KO mice. Interestingly, loss of demarcation between articular cartilage and bone was concomitant with irregular chondrocyte morphology and arrangement. Consistently, in vivo calcein labeling assay showed an increased intensity of calcein labeling in the interface of the growth plate and metaphysis in PKC-δ KO mice. Furthermore, in vitro culture of chondrocyte micromass showed a decreased alcian blue staining of chondrocyte micromass in the PKC-δ KO mice, indicative of a reduced level of glycosaminoglycan production.ConclusionsOur data imply a role for PKC-δ in the osteochondral plasticity of the interface between articular cartilage and the osteochondral junction.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0720-4) contains supplementary material, which is available to authorized users.     

Mechanisms of the acute ischemia-induced arrhythmogenesis--a simulation study

The underlying ionic mechanisms of ischemic-induced arrhythmia were studied by the computer simulation method. To approximate the real situation, ischemic cells were simulated by considering the three major component conditions of acute ischemia (elevated extracellular K(+) concentration, acidosis and anoxia) at the level of ionic currents and ionic concentrations, and a round ischemic zone was introduced into a homogeneous healthy sheet to avoid sharp angle of the ischemic tissue. The constructed models were solved using the operator splitting and adaptive time step methods, and the perturbation finite difference (PFD) scheme was first used to integrate the partial differential equations (PDEs) in the model. The numerical experiments showed that the action potential durations (APDs) of ischemic cells did not exhibited rate adaptation characteristic, resulting in flattening of the APD restitution curve. With reduction of sodium channel availability and long recovery of excitability, refractory period of the ischemic tissue was significantly prolonged, and could no longer be considered as same as APD. Slope of the conduction velocity (CV) restitution curve increased both in normal and ischemic region when pacing cycle length (PCL) was short, and refractory period dispersion increased with shortening of PCL as well. Therefore, dynamic changes of CV and dispersion of refractory period rather than APD were suggested to be the fundamental mechanisms of arrhythmia in regional ischemic myocardium.     

污水土地处理生态工程综合效益评价以霍林河森林型慢速渗滤土地处理工程为例

为了科学、定量地评价污水土地处理生态工程的综合效益,运用层次分析法（ＡＨＰ）,提出了评价指标体系、指标权重和综合效益计算方法．应用此方法对霍林河森林型慢速渗滤土地处理工程的综合效益进行了分析与评价．结果表明,霍林河森林型慢速渗滤土地处理工程的综合效益值ＣＥ＝０．６４,属于中级生态经济系统,而且具有良好的环境效益和社会效益     

Methylation protects miRNAs and siRNAs from a 3'-end uridylation activity in Arabidopsis

Small RNAs of 21-25 nucleotides (nt), including small interfering RNAs (siRNAs) and microRNAs (miRNAs), act as guide RNAs to silence target-gene expression in a sequence-specific manner. In addition to a Dicer homolog, DCL1, the biogenesis of miRNAs in Arabidopsis requires another protein, HEN1. miRNAs are reduced in abundance and increased in size in hen1 mutants. We found that HEN1 is a miRNA methyltransferase that adds a methyl group to the 3'-most nucleotide of miRNAs, but the role of miRNA methylation was unknown. Here, we show that siRNAs from sense transgenes, hairpin transgenes, and transposons or repeat sequences, as well as a new class of siRNAs known as trans-acting siRNAs, are also methylated in vivo by HEN1. In addition, we show that the size increase of small RNAs in the hen1-1 mutant is due to the addition of one to five U residues to the 3' ends of the small RNAs. Therefore, a novel uridylation activity targets the 3' ends of unmethylated miRNAs and siRNAs in hen1 mutants. We conclude that 3'-end methylation is a common step in miRNA and siRNA metabolism and likely protects the 3' ends of the small RNAs from the uridylation activity.     

Generation and Analysis of ESTs from the Grass Carp,Ctenopharyngodon idellus

Grass carp, Ctenopharyngodon idellus (Valenciennes, 1844), is an economically important species widely cultured in the world, but its genome research resources are largely lacking. The objectives of this study were to construct normalized cDNA libraries for efficient EST analysis, to generate ESTs from these libraries, and to identify EST-related molecular markers such as microsatellites and single nucleotide polymorphisms (SNPs) for genetic analysis of this species. A total of 6,269 ESTs were generated representing 4,815 unique sequences, from which 105 putative microsatellites and 5,228 SNPs were identified. These genome resources provide the material basis for future genetic and functional analyses in this species.     

cⅠ857基因的体外定位同义突变

 ｃⅠ８５７基因的体外定位同义突变陈南春,高辉,陈苏民,杨萍,刘新平（西安第四军医大学分子生物学研究所,西安７１００３２）外源基因要在大肠杆菌中获得高表达,需要合适的ＳＤ序列和可调控的强启动子［１］。ＰＬ启动子在原核启动子中属强启动子,它受ｃⅠ基因产物...     

A simple and sensitive assay for 1-aminocyclopropane-1-carboxylic acid

A simple, rapid, and sensitive method for the quantitative determination of 1-amino-cyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene in plant tissues, is described. The assay is based on the liberation of ethylene from ACC with NaOCl in the presence of Hg²⁺; ethylene is assayed by gas chromatography. The yield is normally 80% and can be determined by internal standards. The method is quite specific and can detect as little as 5 pmol of ACC.     

The C termini of Arabidopsis cryptochromes mediate a constitutive light response

Cryptochrome blue light photoreceptors share sequence similarity to photolyases, flavoproteins that mediate light-dependent DNA repair. However, cryptochromes lack photolyase activity and are characterized by distinguishing C-terminal domains. Here we show that the signaling mechanism of Arabidopsis cryptochrome is mediated through the C terminus. On fusion with beta-glucuronidase (GUS), both the Arabidopsis CRY1 C-terminal domain (CCT1) and the CRY2 C-terminal domain (CCT2) mediate a constitutive light response. This constitutive photomorphogenic (COP) phenotype was not observed for mutants of cct1 corresponding to previously described cry1 alleles. We propose that the C-terminal domain of Arabidopsis cryptochrome is maintained in an inactive state in the dark. Irradiation with blue light relieves this repression, presumably through an intra- or intermolecular redox reaction mediated through the flavin bound to the N-terminal photolyase-like domain.