First Report of Ralstonia solanacearum Causing Bacterial Wilt of Yacon in China

Yacon (Smallanthus sonchifolius) is an important cash crop in Yunnan Province, China. In 2003, yacon was introduced to Yunnan province as a novelty root crop and as an experimental source of natural sugars; now more than 15 provinces cultivate the crop. Yunnan is one of the major yacon producing areas of China, with up to 10,000 ha yielding up to 50,000 t of yacon, which is nearly half of the production in China. In April and May 2010, bacterial wilt of yacon was observed in the fields of Lion Mountain of Wuding County, Yunnan Province, China. In 2011, the disease occurred in approximately 1 ha of yacon, resulting in 10% crop loss in that area. The initial symptoms observed were irregular, black, necrotic lesions on leaf margins. After 4 to 7 days, leaves became totally necrotic, plants wilted, and black stripes were observed on plant stems. Within 2 to 3 weeks, more than 70% of leaves within the crop were wilted. Subsequently, the plants died and stems became brittle. When dead plants were pulled from the soil, tubers were found to have turned black. When diseased stems and/or petioles were cut with a sterile sharp knife or razor blade, bacterial ooze appeared on the cut ends. High populations of morphologically uniform bacteria were isolated from the diseased plants by conventional methods. When cultured on TZC (2,3,5-Triphenylte tetrazolium chloride) agar medium (3), colonies were large, elevated, fluidal, and entirely white with a pale red center. The isolated bacterium was gram-negative, grew aerobically, and did not form endospores. The cells were 0.5 to 0.7 × 1.5 to 2.0 μm and nonencapsulated. Ralstonia solanacearum was identified and confirmed as the pathogen on the basis of morphological and physiological characteristics, pathogenicity test, and 16S rDNA sequence analysis (1,4). The nucleotide sequence is available in GenBank (Accession No. HQ176322.1). The pathogenic strain belonged to race 1 and biovar 3 according to the pathogenicity and carbohydrate utilization tests (2). Koch's postulates were tested in the greenhouse, with 10 plants inoculated per species. Plants were inoculated with 15 μl of cell suspension containing 10⁶ to 10⁷ CFU ml^-1 deposited into the third axilla with a capillary tube. The bacteria could infect tomato, pepper, tobacco, potato, common sage (Salvia dugesii Fernald), and patchouli, and caused typical symptoms of wilt and black lesions, but could not infect leaves of swamp mahogany (Eucalyptus robusta Smith), stramonium (Dature stramonium Datura L.), ginger, or maize. To our knowledge, this is the first report of yacon as a host of R. solanacearum. Since the pathogen has a wide host range, monitoring of the vegetation in and around yacon fields should be implemented as a mandatory management measure to prevent disease spread. References: (1) C. A. Boucher et al. J. Bacteriol. 169:5626, 1987. (2) A. C. Hayward. J. Appl. Bacteriol. 27:265, 1964. (3) A. Kelman. Phytopathology 44:693, 1954. (4) W. G. Weisburg et al. J. Bacteriol. 173:697, 1991.

GhAGP31, a cotton non-classical arabinogalactan protein, is involved in response to cold stress during early seedling development

Arabinogalactan proteins (AGPs), a superfamily of highly glycosylated hydroxyproline-rich glycoproteins, are widely implicated in plant growth and development. A gene (including its cDNA), designated GhAGP31, encoding a non-classical AGP protein was isolated from cotton (Gossypium hirsutum). The deduced GhAGP31 protein contains the conserved features of non-classical AGPs: a putative signal peptide, N-terminal histidine-rich stretch, middle repetitive proline-rich domain and a cysteine-containing 'PAC' domain. GFP fluorescence assay demonstrated that GhAGP31 protein was localised on cell walls. GhAGP31 transcripts were mainly detected in roots, hypocotyls and ovules, but little or almost none were detected in other tissues. In particular, expression of GhAGP31 was developmentally regulated in roots. Further study demonstrated that GhAGP31 expression in cotton roots was remarkably up-regulated by cold stress. Expression of the GUS gene driven by the GhAGP31 promoter was also dramatically enhanced in roots of transgenic Arabidopsis seedlings under cold treatment. Additionally, overexpression of GhAGP31 in yeast and Arabidopsis significantly improved the freezing tolerance of yeast cells and cold tolerance of Arabidopsis seedlings. These data imply that GhAGP31 protein may be involved in the response to cold stress during early root development of cotton.

Optical spin injection and spin lifetime in Ge heterostructures

We demonstrate optical orientation in Ge/SiGe quantum wells and study their spin properties. The ultrafast electron transfer from the center of the Brillouin zone to its edge allows us to achieve high spin polarizations and to resolve the spin dynamics of holes and electrons. The circular polarization degree of the direct gap photoluminescence exceeds the theoretical bulk limit, yielding ∼37% and ∼85% for transitions with heavy and light holes states, respectively. The spin lifetime of holes at the top of the valence band is estimated to be ∼0.5  ps and it is governed by transitions between light and heavy hole states. Electrons at the bottom of the conduction band, on the other hand, have a spin lifetime that exceeds 5 ns below 150 K. Theoretical analysis of the spin relaxation indicates that phonon-induced intervalley scattering dictates the spin lifetime of electrons.

The diagnostic accuracy of chromoendoscopy for dysplasia in ulcerative colitis: meta-analysis of six randomized controlled trials

AIM

The diagnostic accuracy of chromoendoscopy for dysplasia in ulcerative colitis (UC) was systematically evaluated.

METHOD

  Original studies in any language were searched from PubMed and Embase. Meta-analysis of prospective studies that compared chromoendoscopy with histological diagnosis was carried out. Sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated for each study and pooled together; summary receiver operating characteristic (ROC) and subgroup analyses were performed, while the quality of the study and heterogeneity were assessed.

RESULTS

Six randomized controlled trials were included, which used methylene blue or indigo carmine dye spray. The meta-analysis demonstrated a pooled sensitivity of 83.3% (95% confidence interval (CI), 35.9-99.6%), specificity of 91.3% (95% CI, 43.8-100%), and DOR of 17.544 (95% CI, 1.245-247.14). Subgroup analyses revealed that both the methylene blue dye spray subgroup and the unspecified endoscopist subgroup include the same studies, and their pooled sensitivity and specificity were 0.737 and 0.917, respectively. The other subgroup, which used indigo carmine dye spray, had overall higher sensitivity (0.930) and lower specificity (0.910).

CONCLUSION

Chromoendoscopy has medium to high sensitivity and a high diagnostic accuracy for dysplastic lesions in UC.

Acute treatment with candesartan cilexetil, an angiotensin II type 1 receptor blocker, improves insulin sensitivity in high-fructose-diet-fed rats

We aimed to determine whether acute treatment with candesartan cilexetil (CV-11974), an angiotensin II type 1 receptor blocker (ARB) can improve insulin sensitivity in high-fructose-diet (HFD)-fed rats. In vivo glucose utilization was measured by applying the euglycemic clamp technique and the expression levels of insulin-signaling molecules in skeletal muscles were examined by western blotting. A bolus injection of CV-11974 improved the glucose infusion rate (GIR) of HFD-fed rats to the level of the control rats. Furthermore, restoration of impaired tyrosine phosphorylation of insulin receptor (IR) β, Akt phosphorylation at Ser⁴⁷³ and Thr³⁰⁸, and phosphorylation of the 160-kDa Akt substrate (AS160) in the skeletal muscles of HFD-fed rats were achieved by this treatment. These results suggest that acute administration of candesartan cilexetil can increase insulin sensitivity of HFD-fed rats, which is associated with improved insulin signaling in skeletal muscles.

Unique genomic structure and distinct mitotic behavior of ring chromosome 21 in two unrelated cases

A ring chromosome replacing a normal chromosome could involve variable structural rearrangements and mitotic instability. However, most previously reported cases lacked further genomic characterization. High-resolution oligonucleotide array comparative genomic hybridization with single-nucleotide polymorphism typing (aCGH+SNP) was used to study 2 unrelated cases with a ring chromosome 21. Case 1 had severe myopia, hypotonia, joint hypermobility, speech delay, and dysmorphic features. aCGH detected a 1.275-Mb duplication of 21q22.12-q22.13 and a 6.731-Mb distal deletion at 21q22.2. Case 2 showed severe growth and developmental retardations, intractable seizures, and dysmorphic features. aCGH revealed a contiguous pattern of a 3.612- Mb deletion of 21q22.12-q22.2, a 4.568-Mb duplication of 21q22.2-q22.3, and a 2.243-Mb distal deletion at 21q22.3. Mitotic instability was noted in 13, 30, and 76% of in vitro cultured metaphase cells, interphase cells, and leukocyte DNA, respectively. The different phenotypes of these 2 cases are likely associated with the unique genomic structure and distinct mitotic behavior of their ring chromosome 21. These 2 cases represent a subtype of ring chromosome 21 probably involving somatic dicentric ring breakage and reunion. A cytogenomic approach is proposed for characterizing the genomic structure and mitotic instability of ring chromosome abnormalities.

Derivation of male germ cells from induced pluripotent stem cells in vitro and in reconstituted seminiferous tubules

OBJECTIVES

Previous studies have demonstrated that mouse- and human-induced pluripotent stem (iPS) cells can differentiate into primordial germ cells in vitro. However, up to now it is not known whether iPS cells would be able to differentiate into male germ cells in vivo. The aim of this study was to explore differentiation potential of iPS cells to male germ cells in vitro and in vivo.

MATERIALS AND METHODS

In this study, approaches using in vitro retinoic acid induction and in vivo ectopic transplantation were combined to induce iPS cells to become male germ cells.

RESULTS

RT-PCR showed that expression of pre-meiotic and meiotic germ cell-specific genes was enhanced in iPS cell-derived embryoid bodies (EBs) compared to mRNA transcripts of iPS cells. Immunofluorescence analysis revealed that iPS cell-derived EBs positively expressed germ-cell markers VASA, c-Kit and SCP3. Furthermore, iPS cell-derived cells dissociated from EBs were injected with testicular cells into dorsal skin of mice. Histological examination showed that iPS cell-derived cells could reconstitute seminiferous tubules, and meanwhile, iPS cell-derived germ cells could settle at basement membranes of reconstituted tubules.

CONCLUSION

Our results suggest that iPS cells are able to differentiate into male germ cells in vitro and that reconstituted seminiferous tubules may provide a functional niche for exogenous iPS cell-derived male germ cells. Derivation of male germ cells from iPS cells has potential application for treating male infertility and provides an ideal platform for elucidating molecular mechanisms of male germ-cell development.

Association study of C1qA polymorphisms with systemic lupus erythematosus in a Han population

Objective: The aim of this study was to evaluate the association of single nucleotide polymorphisms (SNPs) in the C1qA gene region with systemic lupus erythematosus (SLE) in a Chinese Han population. Methods: Chinese SLE patients ( n = 748) and ethnically- and geographically-matched healthy controls ( n = 750) were genotyped for the C1qA region SNPs, rs172378 and rs665691, by using the Sequenom MassArray system. Results: The Chinese Han SLE patients and controls had statistically similar frequencies of alleles, genotypes, and haplotypes of C1qA polymorphisms. Moreover, no association signal was detected on different genetic models (additive, dominant, and recessive) or in SLE subgroups stratified by various clinical manifestations. Conclusions: The C1qA SNPs, rs172378 and rs665691, confer no genetic predisposition to SLE in a Chinese Han population.

Comb-drive tracking and focusing lens actuators integrated on a silicon-on-insulator wafer

This paper reports integrated tracking (horizontal) and focusing (vertical) actuators using microelectromechanical (MEMS) technology for optical storage. The design, fabrication and characterization of the integrated tracking and focusing actuators are demonstrated. The integrated tracking and focusing lens actuators that consist of springs, a lens holder and comb-drive actuators are implemented to obtain the two-dimensional tuning effect of an objective lens. A two-mask process is used to define the actuators on a silicon-on-insulator (SOI) wafer. The DC displacements and the frequency responses are characterized by applying voltage to the micro lens actuators. Displacements are experimentally characterized with ± 24.6μm in tracking direction and 5.7μm in focusing direction. Moreover, the influences of the cross-axis coupling are measured and evaluated. This MEMS device which has a small form factor provides an excellent response time and size reduction. The minimization and integration of the lens actuators can offer low costs in assembly and expand the application area of the optical head.

Serial evaluation of high-resolution CT findings in patients with pneumonia in novel swine-origin influenza A (H1N1) virus infection

OBJECTIVES

The purpose of our study was to review the changes in the serial high-resolution CT (HRCT) findings from patients with novel swine-origin influenza A (H1N1) virus (S-OIV) infection.

METHODS

HRCT findings of 70 patients with presumed or laboratory-confirmed novel S-OIV infection were reviewed. The pattern (consolidation, ground glass, fibrosis and air trapping), distribution and extent of abnormality of the lesions on the HRCT were evaluated at different time points. To assess changes that occurred over time, the CT scans in 56 patients were examined in sequence.

RESULTS

The most common CT findings in patients with S-OIV infection are ground-glass opacities with or without consolidation at the first week. The abnormalities peaked at the second week and resolved after that time, which resulted in substantial reduced residual disease at 4 weeks or later. The development of fibrosis was noted in the first week and peaked at the third week of illness (34.7%), then decreased slowly after that time. The mean time of air trapping being noted after the onset of symptoms was 55.5 ± 20.6 days. Comparing the findings of initial CT, most results (96.4%) of follow-up chest CT findings showed improvement (p<0.01).

CONCLUSION

The abnormalities of ground-glass opacities and/or consolidation on initial CT scans tended to resolve to fibrosis, which then resolved completely or displayed substantially reduced residual disease. HRCT may show more changes in disease progression and play an important role in the evaluation of severe S-OIV.