Functional analysis of slow myosin heavy chain 1 and myomesin-3 in sarcomere organization in zebrafish embryonic slow muscles

Myofibrillogenesis, the process of sarcomere formation, requires close interactions of sarcomeric proteins and various components of sarcomere structures. The myosin thick filaments and M-lines are two key components of the sarcomere. It has been suggested that myomesin proteins of M-lines interact with myosin and titin proteins and keep the thick and titin filaments in order. However, the function of myomesin in myofibrillogenesis and sarcomere organization remained largely enigmatic. No knockout or knockdown animal models have been reported to elucidate the role of myomesin in sarcomere organization in vivo. In this study, by using the gene-specific knockdown approach in zebrafish embryos, we carried out a loss-of-function analysis of myomesin-3 and slow myosin heavy chain 1 (smyhc1) expressed specifically in slow muscles. We demonstrated that knockdown of smyhc1 abolished the sarcomeric localization of myomesin-3 in slow muscles. In contrast, loss of myomesin-3 had no effect on the sarcomeric organization of thick and thin filaments as well as M- and Z-line structures. Together, these studies indicate that myosin thick filaments are required for M-line organization and M-line localization of myomesin-3. In contrast, myomesin-3 is dispensable for sarcomere organization in slow muscles.     

人胎肝细胞分泌的低分子抑瘤物对白血病细胞的抑制作用

本工作证明了在胎儿组织中存在一类低分子天然肿瘤抑制物,它是胎儿组织细胞生成和分泌的,对瘤株细胞和原代白血病细胞有选择性抑制作用。初发期或复发期急性非淋巴细胞白血病患者的骨髓在体外液体培养条件下与肝细胞上清及其甲醇提取物共同孵育4d,可使所有病例的骨髓AML—CFU降低到不可检出的程度。因而,低分子天然抑瘤物是天然肿瘤免疫中的一个组成部分,它在肿瘤的诊断和治疗中有着深远的意义。     

影响棉铃虫增殖马尾松毛虫质型多角体病毒的条件因子的初步探讨

棉铃虫为马尾松毛虫多角体病毒 (DPCPV)理想的替代寄主。试验结果表明 ,不同接毒方法、接种浓度、接种温度及接种虫龄对棉铃虫增殖病毒有影响 ,以病毒涂在人工饲料表面的接毒方法、2 0～ 2 3℃温度及 3龄虫为最佳组合条件。由于利用棉铃虫生产出的病毒 (Ha DPCPV)容易诱发棉铃虫本身的多角体病毒 (NPV) ,尤其对那些带有NPV源的虫种 ,Ha DPCPV不宜作毒种 ,因此为慎重起见 ,最好用马尾松毛虫复制出的病毒作为生产毒种。     

iTRAQ-based proteomics analysis of autophagy-mediated immune responses against the vascular fungal pathogen Verticillium dahliae in Arabidopsis

The mechanisms underlying the functional link between autophagy and plant innate immunity remain largely unknown. In this study, we investigated the autophagy-mediated plant defense responses against Verticillium dahliae (V. dahliae) infection by comparative proteomics and cellular analyses. An assessment of the autophagy activity and disease development showed that autophagic processes were tightly related to the tolerance of Arabidopsis plant to Verticillium wilt. An isobaric tags for relative and absolute quantification (iTRAQ)-based proteomics analysis was performed, and we identified a total of 780 differentially accumulated proteins (DAPs) between wild-type and mutant atg10-1 Arabidopsis plants upon V. dahliae infection, of which, 193 ATG8-family-interacting proteins were identified in silico and their associations with autophagy were verified for several selected proteins. Three important aspects of autophagy-mediated defense against V. dahliae infection were revealed: 1) autophagy is required for the activation of upstream defense responses; 2) autophagy-mediated mitochondrial degradation (mitophagy) occurs and is an important player in the defense process; and 3) autophagy promotes the transdifferentiation of perivascular cells and the formation of xylem hyperplasia, which are crucial for protection against this vascular disease. Together, our results provide several novel insights for understanding the functional association between autophagy and plant immune responses.     

The NSR1 gene encodes a protein that specifically binds nuclear localization sequences and has two RNA recognition motifs

We previously identified a protein (p67) in the yeast, Saccharomyces cerevisiae, that specifically recognizes nuclear localization sequences. We report here the partial purification of p67, and the isolation, sequencing, and disruption of the gene (NSR1) encoding this protein. p67 was purified using an affinity column conjugated with a peptide containing the histone H2B nuclear localization sequence from yeast. Using antibodies against p67 we have cloned the gene for this protein. The protein encoded by the NSR1 gene recognizes the wild-type H2B nuclear localization sequence, but does not recognize a mutant H2B sequence that is incompetent for nuclear localization in vivo. Interestingly, the NSR1 protein has two RNA recognition motifs, as well as an acidic NH2 terminus containing a series of serine clusters, and a basic COOH terminus containing arg-gly repeats. We have confirmed the nuclear localization of p67 by immunofluorescence and found that a restricted portion of the nucleus is highlighted. We have also shown that NSR1 (p67) is required for normal cell growth.     

Modeling the Transmission of Middle East Respirator Syndrome Corona Virus in the Republic of Korea

The 2015 epidemic of Middle East respiratory syndrome (MERS) in the Republic of Korea has been the largest outbreak outside Middle East. This epidemic had caused 185 laboratory-confirmed cases and 36 deaths in the Republic of Korea until September 2, 2015, which attracted public’s attention. Based on the detailed data of patients released by World Health Organization (WHO) and actual propagation of the epidemic, we construct two dynamical models to simulate the propagation processes from May 20 to June 8 and from June 9 to July 10, 2015, respectively and find that the basic reproduction number R₀ reaches up to 4.422. The numerical analysis shows that the reasons of the outbreak spread quickly are lack of self-protection sense and targeted control measures. Through partial correction analysis, the parameters β₁ and γ have strong correlations with R₀, i.e., the infectivity and proportion of the asymptomatic infected cases have much influence on the spread of disease. By sensitivity analysis, strengthening self-protection ability of susceptible and quickly isolating or monitoring close contacts are effective measures to control the disease.     

A cold-adapted and glucose-stimulated type II α-glucosidase from a deep-sea bacterium <Emphasis Type="Italic">Pseudoalteromonas</Emphasis> sp. K8

Objectives

To express and characterize a putative α-glucosidase, Pagl, from Pseudoalteromonas sp. K8 obtained via genome mining approach.

Results

Pagl was expressed and purified to homogeneity, with a molecular mass of 60 kDa. It was optimally active at pH 8.5 and 30 °C, and showed cold-adapted activity. Pagl exhibited specific activity towards substrates with α-1,4-linkage, with the highest specific activity of 19.4 U/mg for maltose, followed by pNPαG and maltodextrins, suggesting that Pagl belongs to the type II α-glucosidase. Interestingly, the activity of Pagl is significantly enhanced (2.7 times) in the presence of 200 mM glucose.

Conclusion

The unique catalytic properties of Pagl make it an attractive candidate for several industrial applications.

     

Effect of pathogenic cysteine mutations on FGFR3 transmembrane domain dimerization in detergents and lipid bilayers

Mutations in fibroblast growth factor receptors are known as the genetic basis of skeletal growth disorders. The mechanism of pathogenesis, as determined by mutation-induced changes in receptor structure, interactions, and function, is elusive. Here we study three pathogenic Cys mutations, associated with either thanatophoric dysplasia or achondroplasia, in the TM domain of fibroblast growth factor receptors 3 (FGFR3). We characterize the dimerization propensities of the mutant TM domains in detergents and in lipid bilayers, in the presence and absence of reducing agents, and compare them to previous measurements of wild-type. We find that the Cys mutations increase the propensity for dimerization in detergent, with the Cys370 mutant exhibiting the highest propensity for disulfide bond formation, the Cys371 mutant having an intermediate propensity, and Cys375 the lowest. Thus, disulfide bonds readily form in detergents, with efficiency that correlates with the severity of the phenotype. In lipid bilayers, however, the Cys370 mutant, which dimerizes strongly in detergent, behaves as the wild-type, suggesting that Cys370-mediated disulfide bonds do not form between the isolated TM domains in bilayers. Thus, the nature of the hydrophobic environment plays an important role in defining the structure and flexibility of transmembrane dimers. These results and previous findings from cellular studies lead us to propose a conformational flexibility mechanism of receptor stabilization as a basis for disregulated FGFR3 signaling in thanatophoric dysplasia and achondroplasia.     

乳腺癌易感蛋白2的结构和功能

乳腺癌易感蛋白2是由乳腺癌易感基因2编码的一种在维持哺乳动物细胞染色体的稳定及DNA损伤生物应答中发挥重要作用的蛋白质。文章通过介绍近几年来对乳腺癌易感蛋白2的结构研究,阐述其在双链DNA损伤修复中的作用模型及其在肿瘤抑制中的功能。     

由不同细胞核背景引起的小麦细胞质雄性不育系(CMS)叶绿体蛋白质组的变化(简报)

叶绿体和线粒体是高等植物细胞内2种重要的细胞器。由于细胞质雄性不育(CMS)被认为是一种由线粒体基因编码的性状,因此,近10多年来,国内外研究者对线粒体基因组结构与功能、由线粒体基因编码的与CMS相关蛋白的研究积累了大量的资料。与线粒体相比,叶绿体与CMS关系的研究相对滞后。虽然一些研究者在核不育水稻中,观