Megachromosomes in tissue culture ofAllium

Chromosome studies have been conducted on the long-term callus cultures of threeAllium species:A. porrum (2n=32),A. tuberosum (2n=32) andA. fistulosum (2n=16). In cultures ofA. fistulosum several interesting cytological abnormalities were observed. They included direct elimination of chromatin from nuclei, multiple chromosome fusions and formation of polycentric and megachromosomes. The rate of abnormalities increased with the time of culture. Allium fistulosum may provide an excellent model system to analyse cytogenetic and molecular aspects of callus-induced genomic changes and, thus, somaclonal variation.     

细胞膜脂质流动性的不均一性与细胞分裂动力学的关系

细胞腊脂流动性在不同类属细胞存在着差异,其差异的程度取决于细胞的生理和生化特性。正常淋巴细胞、肺腺癌、肺鳞癌细胞以及结核细胞膜脂流动发生 分别为２．５１７±０．２６７、２２．５５７±３．７７１,３２．８７５±９．７０９和４．０２６±０．７２２。细胞分裂动力学与膜脂质流动性有关系。细胞分裂及其程度是膜脂质流动性差异的物质基础,同时并受细胞膜脂质的组成,脂蛋白生化以及外界因素的ｐＨ、Ｃａ＾２＋等影响,     

Chromosomal location of rDNA in Allium: in situ hybridization using biotin- and fluorescein-labelled probe

Summary A biotin- and fluorescein-labelled probe of Helianthus argophyllus has been used to map specific repeated rDNA sequences by in situ hybridization on mitotic chromosomes of Alliwn cepa, Allium fistulosum, a diploid interspecific (Allium fistulosum x Allium cepa) F₁ hybrid, and a triploid interspecific (2 x = A. cepa, 1 x = A. fistulosum) shallot. Hybridization sites were restricted to satellited and smallest pairs of chromosomes in both A. cepa and A. fistulosum. The number, size, and position of the hybridization sites distinguish homologous chromosomes and identify the individual chromosomes carrying the nucleolus organizing region (NOR) at the secondary constriction, as well as the individual chromosomes carrying an additional NOR. This in situ hybridization technique is the first reported in a plant species and offers new cytogenetic markers in Allium.     

沉默NHEJ修复通路中关键蛋白Ku70在牙髓干细胞增殖和凋亡中的作用及其机制研究

目的:研究沉默非同源重组修复(non-homologous endjoining,NHEJ)通路中关键蛋白Ku70在牙髓干细胞增殖和凋亡中的作用,分析其机制。方法:提取健康恒牙牙髓组织,进行牙髓干细胞培养。采用脂多糖诱导人牙髓干细胞,分为对照组、阴性对照组、脂多糖组、沉默组和沉默+脂多糖组。观察Ku70免疫组化情况,进行细胞增殖、细胞凋亡实验,检测γ-H2A.X、Ku70、X线修复交叉互补基因4(X-ray repair cross complementary gene 4,Xrcc4)、Rad51 m RNA、Cleaved Caspase-3、p-p38水平。结果:与沉默组相比,对照组、阴性对照组、脂多糖组、沉默+脂多糖组各时间段牙髓干细胞增殖降低;沉默+脂多糖牙髓干细胞增殖高于脂多糖组(P<0.05)。随时间延长,脂多糖组牙髓干细胞增殖不断降低,其他四组牙髓干细胞增殖不断升高,其中在第5 d变化最明显。第5d,与沉默组相比,对照组、阴性对照组牙髓干细胞凋亡率、γ-H2A.X、Rad51 m RNA,Cleaved Caspase-3降低,p-p38升高;脂多糖组、沉默+脂多糖组各项指标较高,p-p38降低;对照组、阴性对照组、脂多糖组、沉默+脂多糖组Ku70、Xrcc4 m RNA降低(P<0.05)。沉默+脂多糖组牙髓干细胞凋亡率、γ-H2A.X、Rad51 m RNA,Cleaved Caspase-3低于脂多糖组,p-p38高于脂多糖组(P<0.05)。结论:沉默Ku70能促进脂多糖诱导的牙髓干细胞增殖,抑制其凋亡,其可能与γ-H2A.X、Rad51 m RNA表达降低,Ku70,Xrcc4升高有关。     

Iron Release in Erythrocytes and Plasma Non Protein-bound Iron in Hypoxic and Non Hypoxic Newborns

Iron is released in a desferrioxamine (DFO)-chelatable form (DCI) when erythrocytes are challenged by an oxidative stress. In &#103 -thalassemic erythrocytes, both DCI content and release (after aerobic incubation for 24 h) are increased and correlated with the fetal hemoglobin (HbF) levels. Since erythrocytes from newborns have an extremely high content of HbF and are exposed to conditions of oxidative stress, the release of iron in these erythrocytes was investigated. The erythrocyte DCI content was increased in preterm but not in term newborns as compared to adults, while the release was increased in both preterm and term erythrocytes. The level of plasma non protein-bound iron (NPBI), which was not detectable in adults, was much higher in preterm than in term newborns. When term plus preterm newborns were divided in two groups, normoxic and hypoxic, according to cord blood pH, it was found that both iron release and NBPI were markedly higher in the hypoxic newborns compared to normoxic ones. Similar results were also obtained when the preterm and term infants were considered separately on the basis of cord blood pH. Therefore, iron release and NPBI are higher when conditions of hypoxia occur. In fact, when the values for iron release and NPBI were separately plotted against cord blood pH values, significant negative correlations were seen in both cases. NPBI was correlated with iron release seen in all the newborns and a significant part of the released iron could be recovered into the incubation medium at the end of the incubation.     

Proteomic analysis for Type I interferon antagonism of Japanese encephalitis virus NS5 protein

Japanese encephalitis virus (JEV) nonstructural protein 5 (NS5) exhibits a Type I interferon (IFN) antagonistic function. This study characterizes Type I IFN antagonism mechanism of NS5 protein, using proteomic approach. In human neuroblastoma cells, NS5 expression would suppress IFNβ‐induced responses, for example, expression of IFN‐stimulated genes PKR and OAS as well as STAT1 nuclear translocation and phosphorylation. Proteomic analysis showed JEV NS5 downregulating calreticulin, while upregulating cyclophilin A, HSP 60 and stress‐induced‐phosphoprotein 1. Gene silence of calreticulin raised intracellular Ca²⁺ levels while inhibiting nuclear translocalization of STAT1 and NFAT‐1 in response to IFNβ, thus, indicating calreticulin downregulation linked with Type I IFN antagonism of JEV NS5 via activation of Ca²⁺/calicineurin. Calcineurin inhibitor cyclosporin A attenuated NS5‐mediated inhibition of IFNβ‐induced responses, for example, IFN‐sensitive response element driven luciferase, STAT1‐dependent PKR mRNA expression, as well as phosphorylation and nuclear translocation of STAT1. Transfection with calcineurin (vs. control) siRNA enhanced nuclear translocalization of STAT1 and upregulated PKR expression in NS5‐expressing cells in response to IFNβ. Results prove Ca²⁺, calreticulin, and calcineurin involvement in STAT1‐mediated signaling as well as a key role of JEV NS5 in Type I IFN antagonism. This study offers insights into the molecular mechanism of Type I interferon antagonism by JEV NS5.     

Analysis of CLDN14 gene in deaf Moroccan patients with non-syndromic hearing loss

Mutations in the CLDN14 gene, encoding the tight junction claudin 14 protein has been reported to date in an autosomal recessive form of isolated hearing loss DFNB29. In order to identify the contribution of CLDN14 to inherited deafness in Moroccan population, we performed a genetic analysis of this gene in 80 Moroccan familial cases. Our results show the presence of 7 mutations: 6 being conservative and one leading to a missense mutation (C11T) which was found at heterozygous and homozygous states, with a general frequency of 6.87%. The pathogenicity of the resulting T4M substitution is under discussion.