Epstein-Barr virus-encoded latent membrane protein 1 impairs G2 checkpoint in human nasopharyngeal epithelial cells through defective Chk1 activation

Nasopharyngeal carcinoma (NPC) is a common cancer in Southeast Asia, particularly in southern regions of China. EBV infection is closely associated with NPC and has long been postulated to play an etiological role in the development of NPC. However, the role of EBV in malignant transformation of nasopharyngeal epithelial cells remains enigmatic. The current hypothesis of NPC development is that premalignant nasopharyngeal epithelial cells harboring genetic alterations support EBV infection and expression of EBV genes induces further genomic instability to facilitate the development of NPC. The latent membrane protein 1 (LMP1) is a well-documented EBV-encoded oncogene. The involvement of LMP1 in human epithelial malignancies has been implicated, but the mechanisms of oncogenic actions of LMP1, particularly in nasopharyngeal cells, are unclear. Here we observed that LMP1 expression in nasopharyngeal epithelial cells impaired G2 checkpoint, leading to formation of unrepaired chromatid breaks in metaphases after γ-ray irradiation. We further found that defective Chk1 activation was involved in the induction of G2 checkpoint defect in LMP1-expressing nasopharyngeal epithelial cells. Impairment of G2 checkpoint could result in loss of the acentrically broken chromatids and propagation of broken centric chromatids in daughter cells exiting mitosis, which facilitates chromosome instability. Our findings suggest that LMP1 expression facilitates genomic instability in cells under genotoxic stress. Elucidation of the mechanisms involved in LMP1-induced genomic instability in nasopharyngeal epithelial cells will shed lights on the understanding of role of EBV infection in NPC development.     

Aptamer selection for the detection of Escherichia coli K88

In this study, the first group of single-stranded DNA aptamers that are highly specific to enterotoxigenic Escherichia coli (ETEC) K88 was obtained from an enriched oligonucleotide pool by the SELEX (Systematic Evolution of Ligands by Exponential Enrichment) procedure, during which the K88 fimbriae protein was used as the target and bovine serum albumin as counter targets. These aptamers were applied successfully in the detection of ETEC K88. They were then grouped under different families based on the similarity of their secondary structure and the homology of their primary sequence. Four sequences from different families were deliberately chosen for further characterization by fluorescence analysis. Having the advantage of high sensitivity, fluorescence photometry was selected as single-stranded DNA quantification method during the SELEX process. Aptamers with the highest specificity and affinity were analyzed to evaluate binding ability with E. coli. Since ETEC K88 is the only type of bacterium that expressed abundant K88 fimbriae, the selected aptamers against the K88 fimbriae protein were able to specifically identify ETEC K88 among other bacteria. This method of detecting ETEC K88 by aptamers can also be applied to bacteria other than ETEC K88.     

红松单木高生长模型的研究

１引言生长模型是定量研究树木生长过程的有效手段。它既可对林木生长作出现实的评价,也可用来预估将来各测树因子的变化;既是编制修订各种数表的基础,也是森林经营中各种措施实施的依据。在林学上,生长模型主要包括单木生长模型和林分生长模型,其中单木生长模型是林...     

Peroxisome proliferator-activated receptor-gamma agonist 15-deoxy-Delta(12,14)-prostaglandin J(2) ameliorates experimental autoimmune encephalomyelitis

Peroxisome proliferator-activated receptors (PPAR) are members of a nuclear hormone receptor superfamily that includes receptors for steroids, retinoids, and thyroid hormone, all of which are known to affect the immune response. Previous studies dealing with PPAR-gamma expression in the immune system have been limited. Recently, PPAR-gamma was identified in monocyte/macrophage cells. In this study we examined the role of PPAR-gamma in experimental autoimmune encephalomyelitis (EAE), an animal model for the human disease multiple sclerosis. The hypothesis we are testing is whether PPAR-gamma plays an important role in EAE pathogenesis and whether PPAR-gamma ligands can inhibit the clinical expression of EAE. Initial studies have shown that the presence of the PPAR-gamma ligand 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ2) inhibits the proliferation of Ag-specific T cells from the spleen of myelin basic protein Ac(1-11) TCR-transgenic mice. 15d-PGJ2 suppressed IFN-gamma, IL-10, and IL-4 production by both Con A- and myelin basic protein Ac(1-11) peptide-stimulated lymphocytes as determined by ELISA and ELISPOT assay. Culture of encephalitogenic T cells with 15d-PGJ2 in the presence of Ag reduced the ability of these cells to adoptively transfer EAE. Examination of the target organ, the CNS, during the course of EAE revealed expression of PPAR-gamma in the spinal cord inflammatory infiltrate. Administration of 15d-PGJ2 before and at the onset of clinical signs of EAE significantly reduced the severity of disease. These results suggest that PPAR-gamma ligands may be a novel therapeutic agent for diseases such as multiple sclerosis.     

The mechanism of myoblast deformation in response to cyclic strain - A cytomechanical study

Mechanical strain is one of the important epigenetic factors that cause deformation and differentiation of skeletal muscles. This research was designed to investigate how myoblast deformation occurs after cyclic strain loading. Myoblasts were passaged three times and harvested; various cyclic strains (2.5kPa, 5kPa and 10kPa) were then loaded using a pulsatile mechanical system. The adaptive response of the myoblasts was observed at different time points (0.5h, 1h, 6h and 12h) post-loading. At the early stage of cyclic strain loading (<1h), almost no visible morphological changes were observed in the myoblasts. The actin cytoskeleton showed a disordered arrangement and a weak fluorescence expression; there was little expression of talin. At 6h and 12h post-loading, the myoblasts changed their orientation to parallel (in the 2.5kPa and 5kPa groups) or perpendicular (in the 10kPa group) to the direction of strain. Fluorescence expression of both the actin cytoskeleton and talin was significantly increased. The results suggest that cyclic strain has at least two ways to regulate adaptation of myoblasts: (1) by directly affecting actin cytoskeleton at an early stage post-loading to cause depolymerization; and (2) by later chemical signals transmitted from the extracellular side to intracellular side to initiate repolymerization.     

一种东亚钳蝎碱性神经毒素的纯化和初步晶体学研究

经ＳｅｐｈａｄｅｘＧ－５０和ＳＰ－ＳｅｐｈａｄｅｘＣ－２５两次柱层析,从河南淅川马氏钳蝎毒素中分得一种碱性神经毒素ＢｍＫＭＩ８．等电聚焦和ＳＤＳ电泳显示单一组分,其ｐＩ为９．１,Ｍｒ为７１００．毒性测试结果表明,该组分对小白鼠有较强的毒性,对昆虫也有一定的毒性,已获得该毒素的两种晶型的大单晶,并测定其空间群为Ｐ２＿１２＿１２＿１,晶胞参数为：ＢｍＫＭＩ８－Ａ：ａ＝３６．７,ｂ＝２６．６,ｃ＝５２．０,ＢｍＫＭＩ８－Ｂ：ａ＝３６．６４Ａ,ｂ＝３７．３１,ｃ＝３７．９５,已收集了ＢｍＫＭＩ８－Ｂ分辨率为１．７４的Ｘ射线单晶衍射数据。     

OsGRF4 controls grain shape,panicle length and seed shattering in rice

Traits such as grain shape, panicle length and seed shattering, play important roles in grain yield and harvest. In this study, the cloning and functional analysis of PANICLE TRAITS 2 (PT2), a novel gene from the Indica rice Chuandali (CDL), is reported. PT2 is synonymous with Growth‐Regulating Factor 4 (OsGRF4), which encodes a growth‐regulating factor that positively regulates grain shape and panicle length and negatively regulates seed shattering. Higher expression of OsGRF4 is correlated with larger grain, longer panicle and lower seed shattering. A unique OsGRF4 mutation, which occurs at the OsmiRNA396 target site of OsGRF4, seems to be associated with high levels of OsGRF4 expression, and results in phenotypic difference. Further research showed that OsGRF4 regulated two cytokinin dehydrogenase precursor genes (CKX5 and CKX1) resulting in increased cytokinin levels, which might affect the panicle traits. High storage capacity and moderate seed shattering of OsGRF4 may be useful in high‐yield breeding and mechanized harvesting of rice. Our findings provide additional insight into the molecular basis of panicle growth.     

Isolation and characterization of endophytic fungi from Camptotheca acuminata

In this study, a total of 161 endophytic fungal isolates from Camptotheca acuminata were obtained and classified to 16 taxa according to morphological and molecular analysis. These taxa were composed of 2 frequent genera (Botryosphaeria and Fusarium) and 14 infrequent groups such as Xylaria, Diaporthe, Rhizopus, Epicoccum, and Preussia, demonstrating that fungal endophytes in C. acuminata were highly abundant and diverse. Antimicrobial activity screening using filter-paper diffusion method showed that 47.6 % of the tested isolates had antimicrobial activity against at least one of the test microorganisms. Screening of fungal endophyte-derived camptothecin analogues by TLC and LC–MS/MS³ demonstrated that a strain Botryosphaeria dothidea, X-4 could produce 9-methoxycamptothecin (9-MCPT) when cultured in Sabouraud’s dextrose broth for 12 days under shake flask and bench-scale fermention conditions. This work showed that the fungal endophytes from C. acuminata could be an alternative source for the production of 9-MCPT and other natural antimicrobial compounds.     

Colonization of endophyte Acremonium sp. D212 in Panax notoginseng and rice mediated by auxin and jasmonic acid

Endophytic fungi can be beneficial to plant growth. However, the molecular mechanisms underlying colonization of Acremonium spp. remain unclear.In this study, a novel endophytic Acremonium strain was isolated from the buds of Panax notoginseng and named Acremonium sp. D212. The Acremonium sp. D212 could colonize the roots of P. notoginseng,enhance the resistance of P. notoginseng to root rot disease, and promote root growth and saponin biosynthesis in P. notoginseng. Acremonium sp. D212 could secrete indole-3-acetic acid(IAA) and jasmonic acid(JA), and inoculation with the fungus increased the endogenous levels of IAA and JA in P. notoginseng. Colonization of the Acremonium sp. D212 in the roots of the rice line Nipponbare was dependent on the concentration of methyl jasmonate(Me JA)(2–15 μmol/L) and 1-naphthalenacetic acid(NAA)(10–20 μmol/L). Moreover, the roots of the JA signaling-defective coi1-18 mutant were colonized by Acremonium sp. D212 to a lesser degree than those of the wild-type Nipponbare and mi R393 boverexpressing lines, and the colonization was rescued by Me JA but not by NAA. It suggests that the cross-talk between JA signaling and the auxin biosynthetic pathway plays a crucial role in the colonization of Acremonium sp. D212 in host plants.