Genomic insight into domestication of rubber tree.

Understanding the genetic basis of rubber tree (Hevea brasiliensis) domestication is crucial for further improving natural rubber production to meet its increasing demand worldwide. Here we provide a high-quality H. brasiliensis genome assembly (1.58 Gb, contig N50 of 11.21 megabases), present a map of genome variations by resequencing 335 accessions and reveal domestication-related molecular signals and a major domestication trait, the higher number of laticifer rings. We further show that HbPSK5, encoding the small-peptide hormone phytosulfokine (PSK), is a key domestication gene and closely correlated with the major domestication trait. The transcriptional activation of HbPSK5 by myelocytomatosis (MYC) members links PSK signaling to jasmonates in regulating the laticifer differentiation in rubber tree. Heterologous overexpression of HbPSK5 in Russian dandelion (Taraxacum kok-saghyz) can increase rubber content by promoting laticifer formation. Our results provide an insight into target genes for improving rubber tree and accelerating the domestication of other rubber-producing plants.

Validation of reference genes for quantitative real-time PCR during latex regeneration in rubber tree.

In rubber tree, latex regeneration is one of the decisive factors influencing the rubber yield, although its molecular regulation is not well known. Quantitative real-time PCR (qPCR) is a popular and powerful tool used to understand the molecular mechanisms of latex regeneration. However, the suitable reference genes required for qPCR are not available to investigate the expressions of target genes during latex regeneration. In this study, 20 candidate reference genes were selected and evaluated for their expression stability across the samples during the process of latex regeneration. All reference genes showed a relatively wide range of the threshold cycle values, and their stability was validated by four different algorithms (comparative delta Ct method, Bestkeeper, NormFinder and GeNorm). Three softwares (comparative delta Ct method, NormFinder and GeNorm) exported similar results that identify UBC4, ADF, UBC2a, eIF2 and ADF4 as the top five suitable references, and 18S as the least suitable one. The application of the screened references would improve accuracy and reliability of gene expression analysis in latex regeneration experiments.

[PREPARATION OF ACELLULAR DERMAL MATRIX AS A KIND OF SCAFFOLD FOR CARTILAGE TISSUE ENGINEERING AND ITS BIOCOMPATIBILITY].

OBJECTIVE: To study the preparation method of acellular dermal matrix (ADM) for cartilage tissue engineering and analyze its biocompatibility. METHODS: The dermal tissues of the calf back were harvested, and decelluarized with 0.5% SDS, and the ADM was reconstructed with 0.5% trypsin, cross-linked with formaldehyde, and modified with 0.5% chondroitin sulfate which can promote the proliferation of chondrocytes. And the porosity, cytotoxicity, and biocompatibility were determined. Co-cultured 2nd passage chondrocytes and bone marrow stromal cells in a proportion of 3 to 7 were used as seed cells. The cells were seeded on ADM (experimental group) for 48 hours to observe the cell adhesion. The expressions of mRNA and protein of collagen type II were tested by RT-PCR and Western blot methods, respectively. And the expressions were compared between the cells seeded on the scaffold and cultured in monolayer (control group). RESULTS: After modification of 0.5% trypsin, the surface of ADM was smooth and had uniform pores; the porosity (85.4% ± 2.8%) was significantly higher than that without modification (72.8% ± 5.8%) (t = -4.384, P = 0.005). The cell toxicity was grade 1, which accords to the requirements for cartilage tissue engineering scaffolds. With time passing, the number of inflammatory cells decreased after implanted in the back of the rats (P < 0.05). The scanning electron microscope observation showed that lots of seed cells adhered to the scaffold, the cells were well stacked, displaying surface microvilli and secretion. The expressions of mRNA and protein of collagen type II were not significantly different between experimental and control groups (t = 1.265, P = 0.235; t = 0.935, P = 0.372). CONCLUSION: The ADM prepared by acellular treatment, reconstruction, cross-linking, and modification shows perfect characters. And the seed cells maintain chondrogenic phenotype on the scaffold. So it is a proper choice for cartilage tissue engineering.

Regeneration of mammalian cochlear and vestibular hair cells through Hes1/Hes5 modulation with siRNA.

The Notch pathway is a cell signaling pathway determining initial specification and subsequent cell fate in the inner ear. Previous studies have suggested that new hair cells (HCs) can be regenerated in the inner ear by manipulating the Notch pathway. In the present study, delivery of siRNA to Hes1 and Hes5 using a transfection reagent or siRNA to Hes1 encapsulated within poly(lactide-co-glycolide acid) (PLGA) nanoparticles increased HC numbers in non-toxin treated organotypic cultures of cochleae and maculae of postnatal day 3 mouse pups. An increase in HCs was also observed in cultured cochleae and maculae of mouse pups pre-conditioned with a HC toxin (4-hydroxy-2-nonenal or neomycin) and then treated with the various siRNA formulations. Treating cochleae with siRNA to Hes1 associated with a transfection reagent or siRNA to Hes1 delivered by PLGA nanoparticles decreased Hes1 mRNA and up-regulated Atoh1 mRNA expression allowing supporting cells (SCs) to acquire a HC fate. Experiments using cochleae and maculae of p27(kip1)/-GFP transgenic mouse pups demonstrated that newly generated HCs trans-differentiated from SCs. Furthermore, PLGA nanoparticles are non-toxic to inner ear tissue, readily taken up by cells within the tissue of interest, and present a synthetic delivery system that is a safe alternative to viral vectors. These results indicate that when delivered using a suitable vehicle, Hes siRNAs are potential therapeutic molecules that may have the capacity to regenerate new HCs in the inner ear and possibly restore human hearing and balance function.

Partial splenic embolization using Bletilla striata particles for hypersplenism in cirrhosis: a prospective study.

The article evaluates the long-term follow-up results of PSE using Bletilla striata (BS) particles for hypersplenism in cirrhosis, as compared to PSE using gelfoam particles. Fifty-nine patients with cirrhosis-induced hypersplenism were treated with PSE. The patients were randomly assigned into two groups: gelfoam group, which includes 32 patients using gelfoam particles as the embolic material, and BS group, which includes 27 patients using BS particles. The peripheral blood cell counts and parameters for complications associated with PSE were measured during the follow-up. The mean values of leukocyte and thrombocyte, but not hemoglobin, were significantly increased after PSE (p < 0.01) in both groups. The values of leukocyte and thrombocyte during the long-term follow-up were significantly improved in BS group than that in gelfoam group (both p < 0.01). The frequency of bleeding episodes from esophageal varices in both groups was significantly reduced after PSE (both p < 0.01), but the post-PSE bleeding episodes showed no remarkable differences between the two groups (p = 0.084). Post-embolization syndrome consisted mainly of fever, nausea and vomiting, and abdominal pain in the two groups. The incidence of grade II to III abdominal pain in BS group (82.8%, 27/33) was significantly higher than in gelfoam group (57.9%, 33/57) (p = 0.020). The mean survival time was 61.5 ± 9.1 (median 60, 1-157) months in gelfoam group and 63.4 ± 9.9 (median 52, 0-161) months in BS group, which showed no significant difference (p = 0.930). In conclusion, BS particles could be used as the embolic material in PSE. Compared to gelfoam used in PSE, BS can achieve even better efficacy in alleviating hypersplenism. It provides a long-term effect on the hematological parameters, bleeding from esophageal varices and good palliation, and improved clinical status contributing to symptomatic control.