The Larix kaempferi genome reveals new insights into wood properties.

Here, through single-molecule real-time sequencing, we present a high-quality genome sequence of the Japanese larch (Larix kaempferi), a conifer species with great value for wood production and ecological afforestation. The assembled genome is 10.97 Gb in size, harboring 45,828 protein-coding genes. Of the genome, 66.8% consists of repeat sequences, of which long terminal repeat retrotransposons are dominant and make up 69.86%. We find that tandem duplications have been responsible for the expansion of genes involved in transcriptional regulation and stress responses, unveiling their crucial roles in adaptive evolution. Population transcriptome analysis reveals that lignin content in L. kaempferi is mainly determined by the process of monolignol polymerization. The expression values of six genes (LkCOMT7, LkCOMT8, LkLAC23, LkLAC102, LkPRX148, and LkPRX166) have significantly positive correlations with lignin content. These results indicated that the increased expression of these six genes might be responsible for the high lignin content of the larches' wood. Overall, this study provides new genome resources for investigating the evolution and biological function of conifer trees, and also offers new insights into wood properties of larches.

Characterization and diabetic wound healing benefits of protein-polysaccharide complexes isolated from an animal ethno-medicine Periplaneta americana L.

Periplaneta americana L. (PA), a type of animal medicine, has been widely used for wound healing in clinical settings. In order to further investigate the bioactive wound healing substances in PA, crude PA protein-polysaccharide complexes were further purified by cellulose DE-52 and Sephadex G100 chromatography in succession. Among these isolated fractions, two fractions eluted by 0.3 M and 0.5 M NaCl with the higher yield, respectively named PaPPc2 and PaPPc3 respectively, were chosen for the wound healing experiments. Mediated by HPGPC, amino acid and monosaccharide composition analysis, circular dichroism spectrum, glycosylation type, FT-IR, and 1H NMR analysis, the characterization of PaPPc2 and PaPPc3 was implemented. And then, the benefits of PaPPcs to promote cell proliferation, migration, and tube formation of HUVECs were determined in vitro, indicated these fractions would facilitate angiogenesis. Finally, as proof of concept, PaPPc2 and PaPPc3 were employed to accelerate the acute wounds of diabetic mice, involving in increase blood vessels and the amounts of angiogenesis-related cytokines (α-SMA, VEGF, and CD31). In short, this study provides an experimental basis to demonstrate the protein-polysaccharide complexes of Periplaneta americana L. as its wound healing bioactive substances.

Ultralong purely organic aqueous phosphorescence supramolecular polymer for targeted tumor cell imaging.

Purely organic room-temperature phosphorescence has attracted attention for bioimaging but can be quenched in aqueous systems. Here we report a water-soluble ultralong organic room-temperature phosphorescent supramolecular polymer by combining cucurbit[n]uril (CB[7], CB[8]) and hyaluronic acid (HA) as a tumor-targeting ligand conjugated to a 4-(4-bromophenyl)pyridin-1-ium bromide (BrBP) phosphor. The result shows that CB[7] mediated pseudorotaxane polymer CB[7]/HA-BrBP changes from small spherical aggregates to a linear array, whereas complexation with CB[8] results in biaxial pseudorotaxane polymer CB[8]/HA-BrBP which transforms to relatively large aggregates. Owing to the more stable 1:2 inclusion complex between CB[8] and BrBP and the multiple hydrogen bonds, this supramolecular polymer has ultralong purely organic RTP lifetime in water up to 4.33 ms with a quantum yield of 7.58%. Benefiting from the targeting property of HA, this supramolecular polymer is successfully applied for cancer cell targeted phosphorescence imaging of mitochondria.

A Supramolecular Artificial Light-Harvesting System with an Ultrahigh Antenna Effect.

An efficient artificial light-harvesting system is fabricated from a cyclic polysaccharide, sulfato-ß-cyclodextrin (SCD); an aggregation-induced emission molecule, an oligo(phenylenevinylene) derivative (OPV-I); and a fluorescent dye, nile red (NiR), via noncovalent interactions in an aqueous solution. In this system, the OPV-I/SCD supramolecular assembly acts as a donor, and NiR that is loaded into the OPV-I/SCD assembly acts as an acceptor. Significantly, an efficient energy-transfer process occurs between the OPV-I/SCD assembly and the loaded NiR, leading to an extremely high antenna effect.

[Effects of polyacrylamide on soil erosion and soil nutrient loss in sloped apple orchards.] / èšä¸™çƒ¯é °èƒºå¯¹å¡åœ°è‹¹æžœå›­æ°´åœŸæµå¤±å’ŒåœŸå£¤å »åˆ†æµå¤±çš„å½±å“.

In order to improve the soil environment, reduce soil erosion and soil nutrient loss, and explore the suitable dry broadcasting rate of polyacrylamide (PAM) in sloped apple orchard, experiments of different dry broadcasting rates of polyacrylamide were carried out in apple orchards with a slope of 20° in the hilly-gully region of northern Shaanxi from 2010 to 2012. PAM treatment levels included 0, 0.6, 0.8, 1.0, 1.2, 1.4 and 1.6 g·m-2. Surface runoff, eroded sediment, soil nutrient loss, and the growth of apple trees were monitored. Results showed that the surface runoff and runoff yield times from May to July exhibited a "V" shape with the increase of PAM application rate, and reached a minimum at the 1.0 g·m-2 level. However, the sediment yield decreased with increasing the PAM application rate. The concentrations of the ammonium nitrogen, available phosphorus, and available potassium in surface runoff and sediment decreased with increa-sing the PAM application rate. PAM significantly reduced the content of nitrate nitrogen in surface runoff, whereas it had no significant effect on nitrate nitrogen in sediment. Organic matter, total nitrogen, total phosphorus, and total potassium in the sediment decreased with increasing the PAM application rate. Moreover, PAM improved average fruit mass and fruit yields in sloped orchards, but it had no significant effect on the growth of apple trees and apple fruit flavor. An application le-vel of PAM at 1.0 g·m-2 should be suitable in sloped apple orchards.

The biomechanical role of periodontal ligament in bonded and replanted vertically fractured teeth under cyclic biting forces.

After teeth are replanted, there are two possible healing responses: periodontal ligament healing or ankylosis with subsequent replacement resorption. The purpose of this study was to compare the fatigue resistance of vertically fractured teeth after bonding the fragments under conditions simulating both healing modes. Thirty-two human premolars were vertically fractured and the fragments were bonded together with Super-Bond C&B. They were then randomly distributed into four groups (BP, CP, CA, BA). The BP and CP groups were used to investigate the periodontal ligament healing mode whilst the BA and CA groups simulated ankylosis. All teeth had root canal treatment performed. Metal crowns were constructed for the CP and CA groups. The BP and BA groups only had composite resin restorations in the access cavities. All specimens were subjected to a 260 N load at 4 Hz until failure of the bond or until 2 × 106 cycles had been reached if no fracture occurred. Cracks were detected by stereomicroscope imaging and also assessed via dye penetration tests. Finally, interfaces of the resin luting agent were examined by scanning electron microscope. The results confirmed that the fatigue resistance was higher in the groups with simulated periodontal ligament healing. Periodontal reattachment showed important biomechanical role in bonded and replanted vertically fractured teeth.

[Construction of recombinant for generation of Porphyromonas gingivalis minor accessory proteins FimCDE deficient strain].

PURPOSE: To construct a recombinant plasmid containing the upstream of fimC and downstream of fimE of Porphyromonas gingivalis, designated as pPHU281-C-Spec-E, which may be further used to knock out fimCDE gene to determine the role of FimCDE in the infection by P. gingivalis. METHODS: DNA fragments were generated by PCR with the genomic DNA of P. gingivalis strain ATCC 33277 as the template. The upstream fragment of fimC (fragment C) and downstream fragment of fimE (fragment E) were cloned into the suicide plasmid pPHU281 to generate plasmid pPHU281-C-E. The spectinomycin resistance gene was inserted between fragment C and E to construct plasmid Pphu281-C-Spec-E. The recombinant plasmid was verified by restriction enzyme digestion and DNA sequencing. RESULTS: The recombinant plasmid pPHU281-C-Spec-E was successfully constructed, which was ready for generation of FimCDE-knockout mutant of P. gingivalis. CONCLUSIONS: The recombinant plasmid pPHU281-C-Spec-E is a tool for construction of FimCDE deficient mutant of P. gingivalis. Supported by National Natural Science Foundation of China (81070839). Team Project of Medical Leaders in Talent and Innovation of Jiangsu Province (LJ201110), Science and Technology Development Plan of Nanjing City(YKK06115) and Medical Science and Technology Development Project of Nanjing City(ZKX1030).

A facile method for preparing biodegradable chitosan derivatives with low grafting degree of poly(lactic acid).

Chemical modification of chitosan by grafting with PLA (CS-g-PLA) was developed via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) mediated coupling reaction. The introduction of PLA disrupted the crystalline structure of chitosan, improved its solubility and thermal stability. Low degree of PLA substitution showed better degradation efficiency than chitosan and PLA. Weight loss of CS-g-PLA6 and CS-g-PLA4 was 87% and 94%, respectively, in 7 days enzymatic degradation study. CS-g-PLA2 was totally degraded in 1 day. Self-assembly behavior was studied using pyrene fluorescence dye technique and found to be PLA grafting level dependent. CS-g-PLA with low grafting degree showed hydrophilic, self-assembling properties and controllable biodegradability that may widen its applications.

Immobilized beta-cyclodextrin polymer coupled to agarose gel properly refolding recombinant Staphylococcus aureus elongation factor-G in combination with detergent micelle.

A novel artificial chaperone system using a combination of interactions between the unfolded protein, a detergent and a chromatographic column packed with immobilized beta-cyclodextrin (beta-CD) polymer coupled to an agarose gel, was introduced to refold recombinant Staphylococcus aureus elongation factor-G (EF-G). Pre-mixing of 10% Triton X-100 and unfolded EF-G at 24 mg/ml followed by a 20-fold dilution into refolding buffer led to successful capturing of EF-G by Triton X-100 resulting in formation of a detergent-protein complex at 1.2mg/ml of final protein concentration. The complex was subsequently applied to the immobilized beta-CD polymer column resulting in correct refolding of EF-G at a concentration of 530 microg/ml with 99% mass recovery. Detergent concentrations above critical micelle concentration were required for efficient capturing of EF-G at high protein concentration. Other detergents with hydrophile-lipophile-Balance values similar to that of Triton X-100 (Triton N-101, Noindet P40 (NP40), and Berol 185) also produced similar result. Soluble polymerized beta-CD was more efficient than the monomer to remove the detergent from the protein complex in a batch system. Immobilized beta-CD polymer column further improved the capability of detergent removal and was able to prevent aggregation that occurred with the addition of soluble beta-CD polymer at high protein concentration in the batch system. The mechanism for this system-assisted refolding was tentatively interpreted: the released protein could correctly refold in an enclosed hydrophilic environment provided by the integration of matrix and beta-CD polymer, and thus avoided aggregation during detergent removal.

A mild hydrophobic interaction chromatography involving polyethylene glycol immobilized to agarose media refolding recombinant Staphylococcus aureus elongation factor G.

Recombinant Staphylococcus aureus elongation factor G (EF-G) is difficult to refold by dilution due to the formation of large amounts of misfolded structures. However, refolding of EF-G by adsorption to a chromatographic column packed with immobilized polyethylene glycol 20,000 (PEG 20 K) followed by pulse elution with 8 M urea resulted in 88% mass recovery and 80% of correctly refolded structure. The PEG 20 K was coupled to brominated allyl group derivatized Sepharose High Performance to construct a mild hydrophobic adsorbent. Various other hydrophobic interaction adsorbents were also attempted to refold EF-G. However, ligands with high hydrophobicity tended to misfold EF-G, resulting in irreversible adsorption. Various solvents, detergents, and low temperature as well as 8 M urea were tried to release bound EF-G. Only pulse elution with 8 M urea was efficient. Urea concentrations favorable for efficiently refolding EF-G were investigated. Low urea concentration produced more misfolded structures.