Facile and Programmable Capillary-Induced Assembly of Prototissues via Hanging Drop Arrays.

An important goal for bottom-up synthetic biology is to construct tissue-like structures from artificial cells. The key is the ability to control the assembly of the individual artificial cells. Unlike most methods resorting to external fields or sophisticated devices, inspired by the hanging drop method used for culturing spheroids of biological cells, we employ a capillary-driven approach to assemble giant unilamellar vesicles (GUVs)-based protocells into colonized prototissue arrays by means of a coverslip with patterned wettability. By spatially confining and controllably merging a mixed population of lipid-coated double-emulsion droplets that hang on a water/oil interface, an array of synthetic tissue-like constructs can be obtained. Each prototissue module in the array comprises multiple tightly packed droplet compartments where interfacial lipid bilayers are self-assembled at the interfaces both between two neighboring droplets and between the droplet and the external aqueous environment. The number, shape, and composition of the interconnected droplet compartments can be precisely controlled. Each prototissue module functions as a processer, in which fast signal transports of molecules via cell-cell and cell-environment communications have been demonstrated by molecular diffusions and cascade enzyme reactions, exhibiting the ability to be used as biochemical sensing and microreactor arrays. Our work provides a simple yet scalable and programmable method to form arrays of prototissues for synthetic biology, tissue engineering, and high-throughput assays.

Environmental-friendly regenerated lignocellulose functionalized cotton fabric to prepare multi-functional degradable membrane for efficient oil-water separation and solar seawater desalination.

Freshwater pollution and shortage have become an imminent problem. Therefore, it is necessary to develop a multi-functional membrane for the production of fresh water. In this work, the regenerated lignocellulose modified cotton fabric was developed as a novel, multi-functional and degradable membrane (LCPT@CF) for efficient oil-water separation and solar steam generation for the first time. The fabrication method has the merits of simple, environmentally friendly and cost effective. The regenerated lignocellulose was adhered on the surface of cotton fabric by tannic acid and polyvinyl alcohol complexes tightly, and the multilayered structures of the LCPT@CF can be formed, which endowed the membranes with underwater superoleophobic property and durability. The underwater superoleophobic property enabled LCPT@CF to purify various kinds of oil-in-water emulsions with a separation efficiency of more than 99.90%. Moreover, benefiting from the excellent photothermal conversion capacity of regenerated lignocellulose, the LCPT@CF achieved high evaporation rate of 1.39 kg m-2 h-1 and favorable evaporation efficiency of 84% under 1 sun illumination, and the LCPT@CF also presented excellent salt-resistance for evaporating seawater for 20 cycles, without salt accumulation. More importantly, the LCPT@CF could be naturally degradable by microorganisms in the natural condition within 3 months, which had outstanding environmental friendliness. These above results demonstrated that the green and efficient LCPT@CF could play great potential in oil-water separation and sewage purification.

Proteomics and post-secretory content adjustment of Nicotiana tabacum nectar.

MAIN CONCLUSION: The tobacco nectar proteome mainly consists of pathogenesis-related proteins with two glycoproteins. Expression of nectarins was non-synchronous, and not nectary specific. After secretion, tobacco nectar changed from sucrose rich to hexose rich. Floral nectar proteins (nectarins) play important roles in inhibiting microbial growth in nectar, and probably also tailoring nectar chemistry before or after secretion; however, very few plant species have had their nectar proteomes thoroughly investigated. Nectarins from Nicotiana tabacum (NT) were separated using two-dimensional gel electrophoresis and then analysed using mass spectrometry. Seven nectarins were identified: acidic endochitinase, ß-xylosidase, α-galactosidase, α-amylase, G-type lectin S-receptor-like serine/threonine-protein kinase, pathogenesis-related protein 5, and early nodulin-like protein 2. An eighth nectarin, a glycoprotein with unknown function, was identified following isolation from NT nectar using a Qproteome total glycoprotein kit, separation by SDS-PAGE, and identification by mass spectrometry. Expression of all identified nectarins, plus four invertase genes, was analysed by qRT PCR; none of these genes had nectary-specific expression, and none had synchronous expression. The total content of sucrose, hexoses, proteins, phenolics, and hydrogen peroxide were determined at different time intervals in secreted nectar, both within the nectar tube (in vivo) and following extraction from it during incubation at 30 °C for up to 40 h in plastic tubes (in vitro). After secretion, the ratio of hexose to sucrose substantially increased for in vivo nectar, but no sugar composition changes were detected in vitro. This implies that sucrose hydrolysis in vivo might be done by fixed apoplastic invertase. Both protein and hydrogen peroxide levels declined in vitro but not in vivo, implying that some factors other than nectarins act to maintain their levels in the flower, after secretion.

Floral nectar chitinase is a potential marker for monofloral honey botanical origin authentication: A case study from loquat (Eriobotrya japonica Lindl.).

Honey, as a commercial product, is a target of adulteration through inappropriate production practices and deliberate mislabelling of botanical origin. Floral nectar protein could be a good marker for determining the source flowers of honey, especially monofloral honeys. Here, nectar and monofloral honey from Eriobotrya japonica Lindl. (loquat) were systematically compared, especially regarding proteomic and enzymatic activity. Using two-dimensional electrophoresis and mass spectrometry, only bee-originated proteins were detected in loquat honey. Xylosidase, thaumatin, and two kinds of chitinases were detected in loquat floral nectar, and their activity in loquat nectar and honey were quantified. Following gel electrophoresis, loquat honey had similar chitinase activity profiles to loquat nectar, but both were clearly distinguishable from Camellia sinensis nectar and Brassica napus honey. To our knowledge, this is the first examination of nectar-origin enzyme activity in honey. Zymography of chitinases is a potential marker for determining or authenticating the botanical origin of honeys.

[XPS analysis of tea plant leaf and root surface].

XPS was applied to analyze the surface chemical composition and structure of the tea plant leaf and root. It was detected that the surface is made up of mainly 4 elements: C, O, N and Al, with little P and F in abaxial leaf. Based on the botanic epidermis structure and the chemical composition, with the help of the standard spectrum data bank on line and the wood XPS study results, and through line Gaussian and Lorentizian the mixed, the binding energy of C(1s) of the leaf surface was classified as 3 types: the first was C1, with the electron binding energy of 285 eV, from C-C or C-H group, representing lipid compound like cutin and wax. C2 with the binding energy of 286.35 eV in the adaxial and 286.61 eV in the abaxial, came from the single bond of carbon and oxygen C-O, mainly standing for cellulose. C3 with the binding energy of approximately 288 eV (288.04 eV in adaxial and 288.09 eV in abaxial) was the sign of C=O group, which is acyl in protein with the confirmation of N(1s) (399-401 eV)and O(1s) analyses. In the root surface, besides the same compounds of cutin and wax (C1, binding energy 285 eV), cellulose (C2, binding energy 286.49 eV) and protein (C3, binding energy 288.78 eV)as in the leaf, there appeared C5 type with the binding energy of 283.32 eV. Because it was lower than C1, it was estimated as carbon linking to metal. Both the leaf and the root surfaces didn't have C4, a type of O-C=O, which is common in wood surface with the highest oxidated carbon of 289-289.5 eV binding energy, indicating that organic acid secreted by the root existed freely on the root surface, without any chemical association with the surface compounds. The results of the separated spectrum of O(1s) supported the above C(1s) results. By the ratio of each type of C, there were more oxygen groups in the abaxial than in the adaxial, implicating more active chemical properties on the abaxial. Compared with the leaf, cutin and wax was little in the root and oxygen groups were many, verifying more active chemical property on the root surface and more water and solute molecules passing. Again the protein content was in the order of root, abaxial and adaxial, indicating the same order of the wetness degree. Higher binding energy of Al than 73. 50 eV showed oxidized aluminum in tea plant surface, which might enhance the absorption, and more oxidized aluminum in the root meants that it has more powerful absorbability.

In vitro simulation studies of silica deposition induced by lignin from rice.

To reveal the possible mechanism of silica deposition in higher plants, lignin was isolated from rice straw following a modified method to conduct a simulation experiment in vitro. UV and infrared absorption spectra showed that the substance had the unique characteristics of pure lignin. The presence of silicon in the precipitation was revealed by TEM (transmission electron microscopy) with EDXA (energy dispersive X-ray analysis) device. It was found that in the borax solution where lignin precipitation occurred silica-lignin co-precipitation was produced but not in the DMSO solution where lignin was broken into its composition compounds and did not precipitate. This means that it is macromolecular lignin itself but not its compounds that could induce silica deposition in higher plants.

[Nanoscale silicas in oryza sativa L. and their UV absorption].

To reveal the unique microstructure of silica in rice and its absorption of ultra violet, wet digestion was chosen to isolate silica bodies from rice leaves and bract according to the fact that concentrated acid cannot destroy glass made of SiO2. A mixed solution of sulfuric and nitric acids was applied to the leaves and bract of rice, respectively. After keeping the treated samples in 60-70 "C water bath for 30 hours and times of washing and sedimentation in water, pure silica bodies were obtained. The detection by X-ray photoelectron spectroscopy(XPS) indicated that there was 35. 05% of carbon 10 nm under the surface of the silica body, much more than the amount of 5. 88% on the out surface which might be due to the contamination of the air contact with the sample. This fact showed that acid couldn't get into the silica body to oxidize the inner organic compounds to alter the structure, therefore the chemical and physical properties of the silica measured could account for the original status in the leaf and bract. Scanning electron microscopy and transmission electron microscopy observation revealed that the silica body of rice is made up of inseparable SiO2 particles of 1-2 nm, sticking slackly to form nano-scale rods of average 45 nm wide and arranging in the same direction. Besides, there were lots of pores inside the inner part of the silica body, including both micron-scale pores (< or = 1 microm) and nano interstitial pores(< or =1-2 nm). The bract silica has the greatest absorption at 285 nm of UV-B, while the leaf silica has a very low UV absorption, indicating that silica in the two organs of rice has different mechanism of radiation resistance.