[Effects of Rehmannia glutinosa consecutive monoculture on the community structure and diversity of phyllosphere bacteria]

Rehmannia glutinosa, a perennial herbaceous species, belongs to the family Scrophularia-ceae. As a staple medicinal material, its tuberous roots are highly valued in traditional Chinese medicine. However, R. glutinosa suffers from serious consecutive monoculture problems in production, which leads to a decline in both productivity and quality. Phyllosphere bacteria, the most abundant component of phyllosphere microorganisms, play crucial roles in plant growth and health. Characterization of phyllosphere bacteria could provide new insights into the mechanisms of consecutive monoculture problems and their control measures. Meanwhile, the varied taxa could be served as an important indicator of consecutive monoculture problems. The barcoded pyrosequencing of 16S rDNA genes combined with a culture-dependent approach was applied to characterize the shifts of bacterial community structure and diversity in the phyllosphere under consecutive monoculture of R. glutinosa. The results showed that consecutive monoculture clearly affected bacterial community structure in the phyllosphere. The phyllosphere bacterial communities of the two-year monocultured (TY) and the diseased plants (DP) were more similar, and different from the one-year monocultured (OY). The evenness, Shannon and Simpson diversity indices were significantly lower in TY and DP than in OY. Species annotation showed that bacterial community in R. glutinosa phyllosphere mainly consisted of Proteobacteria (91.2%), Firmicutes (5.1%) and Actinobacteria (3.7%). There was no significant difference in the number of detected bacterial taxa. However, Proteobacteria was significantly increased while Firmicutes and Actinobacteria were significantly decreased under consecutive monoculture. At the genus level, the relative abundances of genera Exiguobacterium, Bacillus and Arthrobacter, potentially beneficial microorganisms, were significantly higher in OY than that in TY and DP, but it was opposite for the genus Pseudomonas. The results from the culture-dependent approach and pathogenicity test showed that Pseudomonas plecoglossicida D9, widely isolated from the diseased leaves, was highly pathogenic to leaves. In conclusion, R. glutinosa monoculture resulted in distinct phyllosphere bacterial community variation with the accumulation of pathogen loads at the expense of beneficial microorganisms, which could contribute to the occurrence of leaf disease symptoms,and aggravate R. glutinosa replant disease in a monoculture regime.

High levels of glucose promote the activation of hepatic stellate cells via the p38-mitogen-activated protein kinase signal pathway

The relationship between the p38-mitogen-activated protein kinase (p38-MAPK) signal pathway and high glucose-induced hepatic stellate cell (HSC) activation was investigated in this study. Sixty human HSC samples were randomly selected and used in the control (cultured normally), high-glucose (cultured in the presence of high glucose), and blocking (cultured under high-glucose conditions in the presence of the p38-MAPK inhibitor, SB203580) groups. The cells were incubated for 120 h and subsequently analyzed for morphological changes by inverted microscopy and for a-smooth muscle actin (a-SMA) expression (to determine the degree of HSC activation) by the method of streptavidin-biotin complex and western blot. Phospho-p38-MAPK protein expression was analyzed by western blotting. a-SMA and phospho-p38-MAPK expression was significantly upregulated in HSCs cultured under high-glucose conditions, compared to the HSCs cultured normally (P < 0.01). On the other hand, phospho-p38-MAPK and a-SMA protein levels were significantly lower in the blocking group compared to the high-glucose group (P < 0.01). Based on these results, we concluded that high-glucose levels induce HSC activation mediated by phospho-p38-MAPK. Therefore, blocking the p38-MAPK signal pathway could inhibit this effect.

Origin of blue photoluminescence from colloidal silicon nanocrystals fabricated by femtosecond laser ablation in solution

We present a detailed investigation into the origin of blue emission from colloidal silicon (Si) nanocrystals (NCs) fabricated by femtosecond laser ablation of Si powder in 1-hexene. High resolution transmission electron microscopy and Raman spectroscopy observations confirm that Si NCs with average size 2.7 nm are produced and well dispersed in 1-hexene. Fourier transform infrared spectrum and x-ray photoelectron spectra have been employed to reveal the passivation of Si NCs surfaces with organic molecules. On the basis of the structural characterization, UV-visible absorption, temperature-dependent photoluminescence (PL), time-resolved PL, and PL excitation spectra investigations, we deduce that room-temperature blue luminescence from colloidal Si NCs originates from the following two processes: (i) under illumination, excitons first form within colloidal Si NCs by direct transition at the X or Γ (Γ25 → Γ'2) point; (ii) and then some trapped excitons migrate to the surfaces of colloidal Si NCs and further recombine via the surface states associated with the Si-C or Si-C-H2 bonds.

Glucagon-like peptide-1 receptor agonists inhibit hepatic stellate cell activation by blocking the p38 MAPK signaling pathway

We investigated the effects of glucagon-like peptide-1 receptor (GLP-1R) agonists on p38 mitogen-activated protein kinase (MAPK) signaling during inhibition of hepatic stellate cell (HSC) activity. Human HSCs were cultured and morphologically identified. HSC samples were collected and randomly divided into three groups (N = 20 samples per group): a control group treated with high glucose (final concentration 25 mM); a GLP-1R agonist group treated with liraglutide (final concentration 5 mM); and a p38-blocked group treated with the p38 MAPK inhibitor SB203580 (final concentration 14 μM). All cells were cultured for 120 h followed by detection of phosphorylated p38 MAPK (p-p38 MAPK) and α-smooth muscle actin (α-SMA, a measure of HSC activation) by western blot. p-p38 MAPK and α-SMA expression levels were both significantly lower in HSCs in the GLP-1R agonist and p38-blocked groups compared with the control group (all P < 0.01). GLP-1R agonists may inhibit the activation of HSCs by blocking the p38 MAPK signaling pathway.

[Effect of continuous cropping of Rehmannia on its morphological and physiological characteristics]

OBJECTIVE

In contrast to the newly-planted plants, through measuring and analyzing the chlorophyll content, photosynthetic characteristics, root activity and enzyme activity of Rehmannia glutinosa in growth stages, the differentiation manifestation of R. glutinosa physiological activity mediated by continuous cropping was studied.

METHODS

SPAD-502 chlorophyll meter was used to measure chlorophyll content and LI-6400 portable photosynthetic apparatus to determine plant photosynthetic characteristics. Plant root vigor and enzyme system were measured following reference literature.

RESULTS

The problems of Rehmannia caused by continuous cropping had happened since the early stage of its growth period, and lasted throughout the whole growth period. Under the condition of continuous cropping, the chlorophyll content, photosynthetic characteristics and root activity remained at a lower level compared with the newly-planted plants, among which, the chlorophyll content and the root activity (100 days after planting) had significant differences.

CONCLUSION

The insufficient photosynthesis source and the reducing of the storage capacity (root tuber) under the condition of continuous cropping might be the main reasons for these problems of R. glutinosa.

Characterization of metaproteomics in crop rhizospheric soil

Soil rhizospheric metaproteomics is a powerful scientific tool to uncover the interactions between plants and microorganisms in the soil ecosystem. The present study established an extraction method suitable for different soils that could increase the extracted protein content. Close to 1000 separate spots with high reproducibility could be identified in the stained 2-DE gels. Among the spots, 189 spots representing 122 proteins on a 2-DE gel of rice soil samples were successfully identified by MALDI-TOF/TOF-MS. These proteins mainly originated from rice and microorganisms. They were involved in protein, energy, nucleotide, and secondary metabolisms, as well as signal transduction and resistance. Three characteristics of the crop rhizospheric metaproteomics seemed apparent: (1) approximately one-third of the protein spots could not be identified by MALDI-TOF/TOF/MS, (2) the conservative proteins from plants formed a feature distribution of crop rhizospheric metaproteome, and (3) there were very complex interactions between plants and microorganisms existing in a crop rhizospheric soil. Further functional analysis on the identified proteins unveiled various metabolic pathways and signal transductions involved in the soil biotic community. This study provides a paradigm for metaproteomic research on soil biology.

A comparison of an anti-CD25 immunotoxin, Ontak and anti-CD25 microbeads for their ability to deplete alloreactive T cells in vitro

Ex vivo depletion of alloreactive CD25(+) T cells from a stem cell transplant (SCT) can reduce the incidence of graft-versus-host disease (GVHD) while preserving antimicrobial and perhaps antileukemia activity. However, the most effective methods for allodepleting T cells prior to transplant have not been determined. In this study, we have compared three agents that deplete CD25(+) activated, alloreactive T cells. These included Ontak (Denileukin Diftitox), an IL-2 fusion toxin, anti-CD25 microbeads (MACS), an anti-CD25 immunotoxin (IT) and a combination of the IT and MACS. Peripheral blood mononuclear cells (PBMCs) activated in a primary mixed lymphocyte reaction (MLR) were allodepleted using optimal amounts of each agent, and the cells were then analyzed by flow cytometry. The treated cells were examined both for remaining alloreactivity and for the preservation of third party reactivity by testing them in a secondary MLR. Our data demonstrate that both the anti-CD25 IT and the anti-CD25 MACS were equally effective in depleting CD4(+)CD25(+) cells and in sparing T cells that were reactive with third party cells. The anti-CD25 IT was, however, superior in depleting alloreactive CD8(+)CD25(+) cells. In contrast, Ontak did not eliminate alloreactive cells and the Ontak-treated cells retained significant reactivity against the original stimulator cells.

[Pharmacological localization of Horner's syndrome. Case report]

Horner's syndrome is derived from an interruption of the sympathetic pathway at any point along its course between the hypothalamus and the orbit. This pathway is generally considered to consist of three neurons. It had been suggested that the pupillary response to various pharmacologic agents will aid in localizing the lesioned neuron in the sympathetic pathway. We had the opportunity to observe a patient who developed Horner's syndrome as a consequence of pulmonary apex adenocarcinoma. Clinical, radiologic and pharmacologic studies are presented. The methods of pharmacologic localization are discussed.