Formin-like 1 (FMNL1) Is Regulated by N-terminal Myristoylation and Induces Polarized Membrane Blebbing

The formin protein formin-like 1 (FMNL1) is highly restrictedly expressed in hematopoietic lineage-derived cells and has been previously identified as a tumor-associated antigen. However, function and regulation of FMNL1 are not well defined. We have identified a novel splice variant (FMNL1γ) containing an intron retention at the C terminus affecting the diaphanous autoinhibitory domain (DAD). FMNL1γ is specifically located at the cell membrane and cortex in diverse cell lines. Similar localization of FMNL1 was observed for a mutant lacking the DAD domain (FMNL1ΔDAD), indicating that deregulation of autoinhibition is effective in FMNL1γ. Expression of both FMNL1γ and FMNL1ΔDAD induces polarized nonapoptotic blebbing that is dependent on N-terminal myristoylation of FMNL1 but independent of Src and ROCK activity. Thus, our results describe N-myristoylation as a regulative mechanism of FMNL1 responsible for membrane trafficking potentially involved in a diversity of polarized processes of hematopoietic lineage-derived cells.     

Predominance of Single Prophage Carrying a CRISPR/cas System in “Candidatus Liberibacter asiaticus” Strains in Southern China

“Candidatus Liberibacter asiaticus” (CLas) is an uncultureable α-proteobacterium associated with citrus Huanglongbing (HLB, yellow shoot disease), a highly destructive disease affecting citrus production worldwide. HLB was observed in Guangdong Province of China over a hundred years ago and remains endemic there. Little is known about CLas biology due to its uncultureable nature. This study began with the genome sequence analysis of CLas Strain A4 from Guangdong in the prophage region. Within the two currently known prophage types, Type 1 (SC1-like) and Type 2 (SC2-like), A4 genome contained only a Type 2 prophage, CGdP2, namely. An analysis on CLas strains collected in Guangdong showed that Type 2 prophage dominated the bacterial population (82.6%, 71/86). An extended survey covering five provinces in southern China also revealed the predominance of single prophage (Type 1 or Type 2) in the CLas population (90.4%, 169/187). CLas strains with two and no prophage types accounted for 7.2% and 2.8%, respectively. In silico analyses on CGdP2 identified a CRISPR (clustered regularly interspaced short palindromic repeats)/cas (CRISPR-associated protein genes) system, consisting of four 22 bp repeats, three 23 bp spacers and 9 predicted cas. Similar CRISPR/cas systems were detected in all 10 published CLas prophages as well as 13 CLas field strains in southern China. Both Type 1 and Type 2 prophages shared almost identical sequences in spacer 1 and 3 but not spacer 2. Considering that the function of a CRISPR/cas system was to destroy invading DNA, it was hypothesized that a pre-established CLas prophage could use its CRISPR/cas system guided by spacer 1 and/or 3 to defeat the invasion of the other phage/prophage. This hypothesis explained the predominance of single prophage type in the CLas population in southern China. This is the first report of CRISPR/cas system in the “Ca. Liberibacter” genera.     

小麦—天兰偃麦草—黑麦三属杂种花粉植株诱导条件的研究

研究表明,三属杂种处于单核中晚期阶段的花粉最适于诱导形成愈伤组织。低温预处理对促进三属杂种花粉愈伤组织的诱导有一定的作用。利用以马铃薯提取物为基础物质的马铃薯-Ⅱ培养基作诱导培养基,其愈伤组织诱导与分化的频率比目前两个较好的合成培养基要高。同一个三属杂种F_1春、秋播种植株之间在形成愈伤组织的能力上有较大的差异,秋播材料形成愈伤组织的能力明显高于春播材料。F_(?)杂种植株诱导愈伤组织和分化植株的频率均比F_1杂种明显提高。     

用体外免疫法建立人—人抗流行性乙型脑炎病毒杂交瘤细胞株

利用单克隆抗体(McAb)进行病毒病的治疗是人们所关心的一个重大课题。 流行性乙型脑炎(乙脑)是一种严重威胁人民健康的急性传染病,病死率高,后遗症严重。国内外目前尚无特效疗法。陈伯权等用乙脑病毒皮下或腹腔感染3周龄小白鼠24、48小时及5天后,分别用乙脑病毒51-8McAb进行治疗,平均治愈率分别为78％、73％及22％。     

Role of actin binding protein phosphorylation in platelet cytoskeleton assembly

Actin binding protein from human blood platelets is shown to exist in the resting platelet as a phosphorylated protein and contains two residues of phosphate per 260,000 kd. Removal of one-half of these residues with E. coli alkaline phosphatase results in the loss of its ability to crosslink F-actin into a low speed sedimentable complex (its cytoskeleton) and to bind to an F-actin affinity column. Thus, phosphorylation-dephosphorylation of ABP may be an important regulatory mechanism by which the platelet regulates its shape via its cytoskeletal structure.     

聚合酶链式反应检测结核杆菌的研究

以人型结核杆菌基因组DNA为模板,合成二段引物各20个碱基进行聚合酶链式反应(PCR)。经琼脂糖凝胶电泳证实,获得一条245bp扩增带。PCR检测的敏感性染色体基因组DNA为1pg,菌悬液为13个活菌／ml。在特异性试验中,人型结核杆趋,牛型结核杆菌、BCG可见此扩增带。被试的其它14种扰酸菌以及变铅青链霉菌、大肠杆菌质粒Puc19、星状诺卡氏菌、红球菌均未见该扩增带。54例肺结核痰标本3种方法检查的阳性率分别为：萋尼氏抗酸染色16．7％,培养法14．8％,PCR 37．0％。前2种检查方法分别与PCR比较,经统计学处理均有显著性差异(P<0．01)。12例非结核性肺部疾患痰标本抗酸染色和PCR均为阴性。结果表明,PCR技术是快速、敏感、特异诊断结核病的方法。     

Preliminary study of the distribution of the toxic elements As,Cd, and Hg in human hair and tissues by RNAA

In order to study the relationships between trace element concentrations of hair and internal body burdens, a radiochemical NAA technique has been used for determination of the elements As, Cd, and Hg in autopsy samples of liver, kidney-cortex, lung, and hair from 24 male persons who died by accident. High significant positive correlations were observed between the As concentration in hair and in kidney-cortex, and between Cd and Zn concentrations in kidney-cortex. The contents of Cd, both for lung and kidney-cortex, were related to the smoking habits of the subjects.