Vaccinia viral A26 protein is a fusion suppressor of mature virus and triggers membrane fusion through conformational change at low pH.

Vaccinia mature virus requires A26 envelope protein to mediate acid-dependent endocytosis into HeLa cells in which we hypothesized that A26 protein functions as an acid-sensitive membrane fusion suppressor. Here, we provide evidence showing that N-terminal domain (aa1-75) of A26 protein is an acid-sensitive region that regulates membrane fusion. Crystal structure of A26 protein revealed that His48 and His53 are in close contact with Lys47, Arg57, His314 and Arg312, suggesting that at low pH these His-cation pairs could initiate conformational changes through protonation of His48 and His53 and subsequent electrostatic repulsion. All the A26 mutant mature viruses that interrupted His-cation pair interactions of His48 and His 53 indeed have lost virion infectivity. Isolation of revertant viruses revealed that second site mutations caused frame shifts and premature termination of A26 protein such that reverent viruses regained cell entry through plasma membrane fusion. Together, we conclude that viral A26 protein functions as an acid-sensitive fusion suppressor during vaccinia mature virus endocytosis.

MiR397b regulates both lignin content and seed number in Arabidopsis via modulating a laccase involved in lignin biosynthesis.

Plant laccase (LAC) enzymes belong to the blue copper oxidase family and polymerize monolignols into lignin. Recent studies have established the involvement of microRNAs in this process; however, physiological functions and regulation of plant laccases remain poorly understood. Here, we show that a laccase gene, LAC4, regulated by a microRNA, miR397b, controls both lignin biosynthesis and seed yield in Arabidopsis. In transgenic plants, overexpression of miR397b (OXmiR397b) reduced lignin deposition. The secondary wall thickness of vessels and the fibres was reduced in the OXmiR397b line, and both syringyl and guaiacyl subunits are decreased, leading to weakening of vascular tissues. In contrast, overexpression of miR397b-resistant laccase mRNA results in an opposite phenotype. Plants overexpressing miR397b develop more than two inflorescence shoots and have an increased silique number and silique length, resulting in higher seed numbers. In addition, enlarged seeds and more seeds are formed in these miR397b overexpression plants. The study suggests that miR397-mediated development via regulating laccase genes might be a common mechanism in flowering plants and that the modulation of laccase by miR397 may be potential for engineering plant biomass production with less lignin.

Roles of cysteines Cys115 and Cys201 in the assembly and thermostability of grouper betanodavirus particles.

The virus-like particle (VLP) assembled from capsid subunits of the dragon grouper nervous necrosis virus (DGNNV) is very similar to its native T = 3 virion. In order to investigate the effects of four cysteine residues in the capsid polypeptide on the assembly/dissociation pathways of DGNNV virions, we recombinantly cloned mutant VLPs by mutating each cysteine to destroy the specific disulfide linkage as compared with thiol reduction to destroy all S-S bonds. The mutant VLPs of C187A and C331A mutations were similar to wild-type VLPs (WT-VLPs); hence, the effects of Cys187 and Cys331 on the particle formation and thermostability were presumably negligible. Electron microscopy showed that either C115A or C201A mutation disrupted de novo VLP formation significantly. As shown in micrographs and thermal decay curves, beta-mercaptoethanol-treated WT-VLPs remained intact, merely resulting in lower tolerance to thermal disruption than native WT-VLPs. This thiol reduction broke disulfide linkages inside the pre-fabricated VLPs, but it did not disrupt the appearance of icosahedrons. Small dissociated capsomers from EGTA-treated VLPs were able to reassemble back to icosahedrons in the presence of calcium ions, but additional treatment with beta-mercaptoethanol during EGTA dissociation resulted in inability of the capsomers to reassemble into the icosahedral form. These results indicated that Cys115 and Cys201 were essential for capsid formation of DGNNV icosahedron structure in de novo assembly and reassembly pathways, as well as for the thermal stability of pre-fabricated particles.

Rice embryogenic calli express a unique set of microRNAs, suggesting regulatory roles of microRNAs in plant post-embryogenic development.

In vitro cultured embryogenic callus was employed as a model to investigate microRNAs (miRNAs) associated with embryogenesis and post-embryonic development. Thirty-one miRNAs including 16 novel species were identified from a large number of small RNAs which were cloned from both differentiated and undifferentiated rice embryogenic calli. Four target genes of the miRNAs were further validated. A set of the miRNAs, including miR397 and miR156, exhibited intriguing expression patterns during the transition from undifferentiated to differentiated calli. By exploiting the correlations between the differential expression patterns of these miRNAs and their targets, the regulatory roles of the miRNAs on meristem maintenance and embryogenesis were indicated.

Efficacy of tripterygium glycosides tablet in treating ankylosing spondylitis: a systematic review and meta-analysis of randomized controlled trials.

Hundreds of randomized controlled trials (RCTs) on tripterygium glycosides tablet (TGT) in the treatment of ankylosing spondylitis (AS) have been published, but the therapeutic effects have never been systematically reviewed yet. The aim of this meta-analysis was to evaluate the efficacy of TGT on AS based on RCTs. PubMed, ScienceDirect, Cochrane Library, China Journals Full-text Database, and Wanfang Data were searched. The RCT quality was evaluated by the Cochrane Collaboration's tool for assessing risk of bias. The RCT characteristics including publication years, sample sizes, and follow-up periods as well as outcome measures including symptoms improvement, morning stiffness (MS), bath ankylosing spondylitis patient global score (BAS-G), pain index (PI), swelling index (SI), finger to floor distance (FFD), pillow wall distance (PWD), Schober test (Schober), erythrocyte sedimentation rate (ESR), and C reactive protein (CRP) were extracted. The odds ratio (OR), mean difference (MD), and its 95% confidence interval (CI) were selected for overall effect sizes. Subgroup, sensitivity, and meta-regression analyses were conducted to confirm the results. Eleven RCTs with 807 participants were included, the quality of which was moderate. OR of TGT in treating AS was 0.46 (95% CI 0.24, 0.90]. MD of MS was 11.79 (95% CI 3.13, 20.45). MD of BAS-G was 0.13 (95% CI -19.73, 19.99). MD of PI was 0.78 (95% CI 0.22, 1.34). MD of SI was 0.80 (95% CI 0.06, 1.53). MD of FFD was 0.80 (95% CI 0.06, 1.53). MD of PWD was 1.37 (95% CI -0.64, 3.38). MD of Schober was -0.36 (95% CI -0.65, -0.07]. MD of ESR was 4.58 (95% CI 2.10, 7.06). MD of CRP was 1.86 (95% CI -2.03, 5.76). Subgroup, sensitivity, and meta-regression analyses found the robust results. In conclusion, TGT could not treat AS effectively, as suggested by the moderate RCT quality and meta-analysis evidence.

Crystallization and X-ray diffraction of virus-like particles from a piscine betanodavirus.

Dragon grouper nervous necrosis virus (DGNNV), a member of the genus Betanodavirus, causes high mortality of larvae and juveniles of the grouper fish Epinephelus lanceolatus. Currently, there is no reported crystal structure of a fish nodavirus. The DGNNV virion capsid is derived from a single open reading frame that encodes a 338-amino-acid protein of approximately 37 kDa. The capsid protein of DGNNV was expressed to form virus-like particles (VLPs) in Escherichia coli. The VLP shape is T = 3 quasi-symmetric with a diameter of ∼38 nm in cryo-electron microscopy images and is highly similar to the native virion. In this report, crystals of DGNNV VLPs were grown to a size of 0.27 mm within two weeks by the hanging-drop vapour-diffusion method at 283 K and diffracted X-rays to ∼7.5 Šresolution. In-house X-ray diffraction data of the DGNNV VLP crystals showed that the crystals belonged to space group R32, with unit-cell parameters a = b = 353.00, c = 800.40 Å, α = ß = 90, γ = 120°. 23 268 unique reflections were acquired with an overall Rmerge of 18.2% and a completeness of 93.2%. Self-rotation function maps confirmed the fivefold, threefold and twofold symmetries of the icosahedron of DGNNV VLPs.

[Surgical treatment of thoracolumbar burst fractures through Wiltse paraspinal approach].

OBJECTIVE: To investigate clinical effects and advantages of Wiltse paraspinal approach to thoracolumbar burst fractures. METHODS: From June 2008 to June 2010, the data of 53 patients with thoracolumbar burst fractures with no obviously nerve injury were retrospectively analyzed, including 43 males and 10 females with an average age of 41 years ( ranged, 19 to 62 years). For segmental distribution, 6 cases were T11, 11 cases were T12, 22 cases were L1 and 14 cases were L2. Among them, 28 cases were treated with Wiltse paraspinal approach, and 25 cases with postmiddle approach. The operation time, blood loss, postoperative drainage,VAS score of back, Cobb angle of injured cord, changes of collapse of vertebral and median sagittal diameter of injured vertebral were observed. RESULTS: Compared with two methods, there were advantages in improving operation time, blood loss, postoperative drainage and VAS score of back, but there were no significant differences in improving Cobb angle of injuried cord, changes of collapse of vertebral and median sagittal diameter of injuried vertebral. CONCLUSION: Wiltse paraspinal approach to thoracolumbar burst fractures can achieve the same reduction with postmiddle approach,and has advantages of minimally invasive, less blood, simple operation and rapid recovery, and worth popularizing.

[Arthroscopic minimally invasive treatment of tibial intercondylar eminence fractures in children].

OBJECTIVE: To analyze the characteristics of children tibial intercondylar eminence fractures, and introduce arthroscopic minimally invasive techniques for the treatment of tibial intercondylar eminence fractures in children. METHODS: From January 2004 to December 2008, 12 children with tibial intercondylar eminence fractures were treated with cross Kirschner wire fixation after arthroscopic reduction. According to Meyers-McKeever classification systems, there were 1 case of type I, 4 cases of type II, and 7 cases of type III. There were 10 fresh and 2 old fractures in all. Among the patients, 10 patients were boy and 2 patients were girl,ranging in age from 8 to 13 years, with an average of 10 years. All the patients underwent arthroscopic exploration, reduction and fixation. During follow-up ranging from 10 to 36 months, the union of fracture, range of motion and stabilization of the knee were assessed. One patient was combined with lesions of the menisci, 1 patient with femoral trochlea cartilage injury, and 5 patients with meniscal entrapment under the bone. RESULTS: The heeling time averaged 5 weeks. No knee laxity or instability and no intercondylar notch impingement was detected in all cases at 3 months postoperatively. At same time, full range of motion of the affected knee returned, and the average Lysholm knee score was (92.7 +/- 2.5), the average Lysholm knee score was (96.4 +/- 1.7) at 6 months postoperatively. The Lachman test and ADT test was negative. CONCLUSION: The type II and type III tibial intercondylar eminence fractures occur frequently in children. Lesions of the menisci and cartilage occur seldom. The method of arthroscopic cross Kirschner wire fixation for the treatment of tibial intercondylar eminence fracture is easy to operate. Simultaneously, this technique is less invasive and allows early recovery. Also it coincidences with the characteristic rapid bone growth of children.

Expression analysis of phytohormone-regulated microRNAs in rice, implying their regulation roles in plant hormone signaling.

Twenty-two conserved miRNAs were chosen to investigate the expression pattern in response to phytohormone treatments, in which the effects of five classic plant hormone stresses were surveyed in Oryza sativa. The results showed that 11 miRNAs were found to be dysregulated by one or more phytohormone treatments. The target genes of these miRNAs were validated in vivo and their expression profiling were revealed. We also analyzed the promoter regions of the 22 conserved miRNAs for phytohormone-responsive elements and the existence of the elements provided further evidences supporting our results. These findings enable us to further investigate the role of miRNAs in phytohormone signaling.