Enrichment of soil rare bacteria in root by an invasive plant Ageratina adenophora.

The assembly of the root-associated microbiome provides mutual benefits for the host plant and bacteria in soils. It is interesting how invasive plants interact with the local soil microbial community and establish the soil bacterial community in the endosphere of these plants in the short term. In this study, we compared the bacterial community in the rhizosphere with that in the root endosphere of an invasive plant, Ageratina adenophora, using high-throughput sequencing. The results showed that the roots of A. adenophora selectively accumulated the genera Clostridium and Enterobacter, which are rarely distributed in the rhizosphere. This selective accumulation caused a switch in the bacterial composition at the phylum level from Bacteroidetes predominant in the rhizosphere to Proteobacteria dominant in the root endosphere of A. adenophora. Our data indicated the potential existence of a highly conserved signal recognition in which hosts, either invasive or native, enrich the endosphere bacteria, such as Clostridium, Enterobacter, etc., from the rhizosphere. Moreover, the accumulated bacteria were physiologically and genetically different at the strain level and displayed distinct roles in growth between invasive and native plants. The assembly of the bacterial community in the roots may be an advantageous strategy for A. adenophora in competition with native plants.

Anatomical mechanism of spontaneous recovery in regions caudal to thoracic spinal cord injury lesions in rats.

BACKGROUND: The nerve fibre circuits around a lesion play a major role in the spontaneous recovery process after spinal cord hemisection in rats. The aim of the present study was to answer the following question: in the re-control process, do all spinal cord nerves below the lesion site participate, or do the spinal cord nerves of only one vertebral segment have a role in repair? METHODS: First we made a T7 spinal cord hemisection in 50 rats. Eight weeks later, they were divided into three groups based on distinct second operations at T7: ipsilateral hemisection operation, contralateral hemisection, or transection. We then tested recovery of hindlimbs for another eight weeks. The first step was to confirm the lesion had role or not in the spontaneous recovery process. Secondly, we performed T7 spinal cord hemisections in 125 rats. Eight weeks later, we performed a second single hemisection on the ipsilateral side at T8-T12 and then tested hindlimb recovery for another six weeks. RESULTS: In the first part, the Basso, Beattie, Bresnahan (BBB) scores and the electrophysiology tests of both hindlimbs weren't significantly different after the second hemisection of the ipsilateral side. In the second part, the closer the second hemisection was to T12, the more substantial the resulting impairment in BBB score tests and prolonged latency periods. CONCLUSIONS: The nerve regeneration from the lesion area after hemisection has no effect on spontaneous recovery of the spinal cord. Repair is carried out by all vertebrae caudal and ipsilateral to the lesion, with T12 being most important.

Triterpenoids and steroids from the fruits of Melia toosendan and their cytotoxic effects on two human cancer cell lines.

Ten new triterpenoids, named meliasenins I-R (1-10), one new steroid (11), and 11 related known compounds (12-22) were isolated from fruits of Melia toosendan. The structures of the new compounds were established on the basis of spectroscopic methods, including 2D NMR techniques and mass spectrometry. The relative configuration of 1, (20R*,23E)-25-hydroperoxyeupha-7,23-diene-3ß,16ß-diol (meliasenin I), was confirmed by single-crystal X-ray diffraction analysis. All isolated triterpenoids (1-10, 12-15) and two steroids (11, 20) were tested for their cytotoxicity against U20S human osteosarcoma and MCF-7 human breast cancer cells using the MTT assay, and some of them were significantly cytotoxic (IC(50) <10 µg/mL). The insecticidal properties of compounds 1-15 and 20 were also briefly evaluated.

[Sinerem labeling and MRI tracking of neural stem cells in vivo and in vitro].

OBJECTIVE: To label rat neural stem cells (NSCs) with the complex of Sinerem, the ultrasmall superparamagnetic iron oxide (USPIO), and poly-L-lysine (PLL), and evaluate the feasibility of tracking the labeled cells with magnetic resonance imaging (MRI) in vitro and in vivo. METHODS: Sinerem was incubated with PLL to obtain the complex of Sinerem-PLL. The mesenchymal stem cells (MSCs) isolated from the bone marrow of SD rats were cultured and induced to differentiate into the neural stem cells. The second-passage cells were cultured overnight with the Sinerem-PLL complex, after which Prussian blue staining and transmission electron microscopy were performed to observe the nanoparticles in the cytoplasm. Cell apoptosis assay was performed to assess the cell viability 1 day, 1 week, and 2 weeks after the labeling. Cell tracking with 4.7 MR system was carried out in vivo and in vitro using T(2)WI and T(2)*WI sequences. RESULTS: The NSCs could be effectively labeled with Sinerem-PLL complex with the labeling efficiency exceeding 95%. Prussian blue staining showed numerous blue iron particles in the cytoplasm, and under transmission electron microscope, these particles accumulated in the endosomes/lysosomes. The labeling did not significantly affect the cell viability and proliferation. Remarkable low signal density changes of the labeled cells was seen on T(2)WI and T(2)*WI in vivo and in vitro. CONCLUSION: NSCs can be effectively labeled with Sinerem-PLL complex, and MRI can be used to track the labeled cells in vivo and in vitro.

[Effect of superparamagnetic iron oxide labeling on neural stem cell survival and proliferation].

OBJECTIVE: To study the effect of superparamgnetic iron oxides (ferumoxides) on the survival and proliferation of neural stem cells (NSCs) and determine the optimal ferumoxides concentration for labeling. METHODS: Bone marrow stromal cells (BMSCs) were obtained from rat femoral marrow and cultured in vitro to induce their differentiation into NSCs. Ferumoxides labeling of the NSCs was performed with different final concentrations of ferumoxides, and the labeling efficiency and viability of the labeled NSCs were evaluated by Prussian blue staining, MTT assay, flow cytometry and transmission electron microscope. RESULTS: The NSCs could be effectively labeled with ferumoxides with a labeling efficiency of around 90%. Prussian blue staining showed numerous fine granules with blue staining in the cytoplasm of the labeled NSCs, and the intensity of the blue staining was in positive correlation with the ferumoxide concentration for labeling. Transmission electron microscopy of the labeled NSCs revealed the presence of numerous vesicles spreading in the cytoplasm and filled with electron-dense magnetic iron particles. The ferumoxides vesicles increased with the labeling concentration of ferumoxides, and at the final concentration exceeding 25 microg/ml, ferumoxides vesicles in the NSCs gave rise to conglomeration which hampered observation of the cellular ultrastructure by transmission electron microscope. The results of flow cytometry and MTT assay demonstrated that the cell viability, proliferation, differentiation and apoptosis of the labeled cells were affected by ferumoxides at the concentration above 25 microg/ml, but such effects could be minimal at lower concentrations. CONCLUSION: Ferumoxides might be feasible for in vitro labeling of the NSCs with the optimal concentration of 25 microg/ml.