Building an emission library of donor-acceptor-donor type linker-based luminescent metal-organic frameworks.

Luminescent metal-organic frameworks (LMOFs) have been extensively studied for their potential applications in lighting, sensing and biomedicine-related areas due to their high porosity, unlimited structure and composition tunability. However, methodical development in systematically tuning the emission properties of fluorescent organic linker-based LMOFs to facilitate the rational design and synthesis of target-specific materials has remained challenging. Herein we attempt to build an emission library by customized synthesis of LMOFs with targeted absorption and emission properties using donor-acceptor-donor type organic linkers. By tuning the acceptor groups (i.e. 2,1,3-benzothiadiazole and its derivatives), donor groups (including modification of original donors and use of donors with different metal-linker connections) and bridging units between acceptor and donor groups, an emission library is developed for LMOFs with their emissions covering the entire visible light range as well as the near-infrared region. This work may offer insight into well controlled design of organic linkers for the synthesis of LMOFs with specified functionality.

Tuning and Directing Energy Transfer in the Whole Visible Spectrum through Linker Installation in Metal-Organic Frameworks.

While limited choice of emissive organic linkers with systematic emission tunability presents a great challenge to investigate energy transfer (ET) over the whole visible light range with designable directions, luminescent metal-organic frameworks (LMOFs) may serve as an ideal platform for such study due to their tunable structure and composition. Herein, five Zr6 cluster-based LMOFs, HIAM-400X (X=0, 1, 2, 3, 4) are prepared using 2,1,3-benzothiadiazole and its derivative-based tetratopic carboxylic acids as organic linkers. The accessible unsaturated metal sites confer HIAM-400X as a pristine scaffold for linker installation. Six full-color emissive 2,1,3-benzothiadiazole and its derivative-based dicarboxylic acids (L) were successfully installed into HIAM-400X matrix to form HIAM-400X-L, in which the ET can be facilely tuned by controlling its direction, either from the inserted linkers to pristine MOFs or from the pristine MOFs to inserted linkers, and over the whole range of visible light. The combination of the pristine MOFs and the second linkers via linker installation creates a powerful two-dimensional space in tuning the emission via ET in LMOFs.

Linker Engineering toward Full-Color Emission of UiO-68 Type Metal-Organic Frameworks.

Luminescent metal-organic frameworks (LMOFs) demonstrate strong potential for a broad range of applications due to their tunable compositions and structures. However, the methodical control of the LMOF emission properties remains a great challenge. Herein, we show that linker engineering is a powerful method for systematically tuning the emission behavior of UiO-68 type metal-organic frameworks (MOFs) to achieve full-color emission, using 2,1,3-benzothiadiazole and its derivative-based dicarboxylic acids as luminescent linkers. To address the fluorescence self-quenching issue caused by densely packed linkers in some of the resultant UiO-68 type MOF structures, we apply a mixed-linker strategy by introducing nonfluorescent linkers to diminish the self-quenching effect. Steady-state and time-resolved photoluminescence (PL) experiments reveal that aggregation-caused quenching can indeed be effectively reduced as a result of decreasing the concentration of emissive linkers, thereby leading to significantly enhanced quantum yield and increased lifetime.

Plasma treated TiO2/C nanofibers as high performance anode materials for sodium-ion batteries.

TiO2 has been a promising anode material for sodium-ion batteries because it is low-cost and environment-friendly. However, its electrochemical performance at high rates is still not acceptable. Herein, we synthesized a TiO2/C nanofiber material by the electrospinning method, and introduced air plasma treatments to modify the obtained material. Characterization results indicate that after the plasma treatments, the C fibers may have reacted with the plasma, and the surface areas of the nanofibers are increased. Electrochemical tests show this plasma treatment may be beneficial to the rate performance. The TiO2/C nanofiber with plasma treatment could deliver a high redox capacity of 191 mA h g-1 after 500 cycles at a very high rate of 10C (3300 mA g-1). The superior effects of the plasma treatment on the rate performance may provide new insights for developing better materials for practical sodium-ion batteries.

Preparation of Nanofibrous Silver/Poly(vinylidene fluoride) Composite Membrane with Enhanced Infrared Extinction and Controllable Wetting Property.

Nanofibrous silver (Ag)/poly(vinylidene fluoride) (PVDF) composite membranes were obtained from a two-step preparation method. In the first step, the electrospun silver nitrate (AgNO3)/PVDF membranes were prepared and the influence of the AgNO3 content on the electrospinning process was studied. According to scanning electron microscopy (SEM) results, when the electrospinning solution contained AgNO3 in the range between 3 to 7 wt.%, the nanofiber morphologies can be obtained. In the second step, the electrospun AgNO3/PVDF membranes were reduced by sodium borohydride to form the nanofibrous Ag/PVDF composite membranes. The resultant composite membranes were characterized by SEM, X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), differential scanning calorimetry, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared. The XRD, XPS, and EDS characterizations proved the existence of Ag in the nanofibrous Ag/PVDF composite membranes. The crystallinity degree of PVDF for composite membranes declined with the increase in Ag content. More importantly, the nanofibrous Ag/PVDF composite membranes had obviously higher Rosseland extinction coefficients and lower thermal radiative conductivities in comparison with electrospun PVDF membrane, which demonstrates that such composite membranes with high porosity, low density, and good water vapor permeability are promising thermal insulating materials to block the heat transfer resulting from thermal radiation. In addition, three different methods for surface modification have been used to successfully improve the hydrophobicity of nanofibrous Ag/PVDF composite membranes.

In-depth comparative transcriptome analysis of intestines of red swamp crayfish, Procambarus clarkii, infected with WSSV.

Crayfish has become one of the most important farmed aquatic species in China due to its excellent disease resistance against bacteria and viruses. However, the antiviral mechanism of crayfish is still not very clear. In the present study, many high-quality sequence reads from crayfish intestine were obtained using Illumina-based transcriptome sequencing. For the normal group (GN), 44,600,142 high-quality clean reads were randomly assembled to produce 125,394 contigs. For the WSSV-challenged group (GW), 47,790,746 high-quality clean reads were randomly assembled to produce 148,983 contigs. After GO annotation, 39,482 unigenes were annotated into three ontologies: biological processes, cellular components, and molecular functions. In addition, 15,959 unigenes were mapped to 25 different COG categories. Moreover, 7,000 DEGs were screened out after a comparative analysis between the GN and GW samples, which were mapped into 250 KEGG pathways. Among these pathways, 36 were obviously changed (P-values < 0.05) and 28 pathways were extremely significantly changed (P-values < 0.01). Finally, five key DEGs involved in the JAK-STAT signaling pathway were chosen for qRT-PCR. The results showed that these five DEGs were obviously up-regulated at 36 h post WSSV infection in crayfish intestine. These results provide new insight into crayfish antiviral immunity mechanisms.

Dissipation of excess excitation energy of the needle leaves in Pinus trees during cold winters.

Photooxidative damage to the needle leaves of evergreen trees results from the absorption of excess excitation energy. Efficient dissipation of this energy is essential to prevent photodamage. In this study, we determined the fluorescence transients, absorption spectra, chlorophyll contents, chlorophyll a/b ratios, and relative membrane permeabilities of needle leaves of Pinus koraiensis, Pinus tabulaeformis, and Pinus armandi in both cold winter and summer. We observed a dramatic decrease in the maximum fluorescence (F m) and substantial absorption of light energy in winter leaves of all three species. The F m decline was not correlated with a decrease in light absorption or with changes in chlorophyll content and chlorophyll a/b ratio. The results suggested that the winter leaves dissipated a large amount of excess energy as heat. Because the cold winter leaves had lost normal physiological function, the heat dissipation depended solely on changes in the photosystem II supercomplex rather than the xanthophyll cycle. These findings imply that more attention should be paid to heat dissipation via changes in the photosystem complex structure during the growing season.

A novel single WAP domain-containing protein isoform with antibacterial relevance in Litopenaeus vannamei.

Single WAP domain (SWD)-containing protein is a small protein containing a whey acidic protein (WAP) domain at the C-terminal region. SWD-containing protein exhibits structural similarity to the family of serine proteinase inhibitors. As of this writing, some SWD domain-containing proteins have been identified in crustaceans, and their functions included antibacterial and anti-proteinase activities. We identified a SWD protein isoform gene in Litopenaeus vanname (Lv-SWDi). Very high sequence similarity was found between Lv-SWDi and Lv-SWD. Results of time-course analysis for the gene expression profile showed that Lv-SWDi could produce a rapid feedback and an obvious upregulation at 12 h after Vibrio injection. Endogenous Lv-SWDi protein was obviously upregulated, and the highest expression level was reached at 24 h after Vibrio injection. The purified rLv-SWDi could directly bind to Gram-positive and Gram-negative bacteria. Results of the proteinase inhibitory assay also showed that rLv-SWDi could inhibit secretory protease activity from Bacillus subtilis. Lv-SWDi is a part of an important immunity-relevant gene and may serve important functions in defense against bacteria.

Introduction of two mutations into AroG increases phenylalanine production in Escherichia coli.

L-Phenylalanine is an important amino acid commercially, and therefore optimization of its manufacture is of interest. We constructed a range of mutant alleles of AroG, the enzyme involved in the first step of phenylalanine biosynthesis. Three single-site mutant alleles were constructed (aroG8, aroG15, and aroG29), which were then combined to generate three double-site aroG (fbr) mutant alleles (aroG8/15, aroG8/29, and aroG15/29). Enzymatic activity, feedback inhibition, and fermentation were analyzed in all of the mutants. All double-site mutants, except AroG15/29, showed higher enzymatic activity and greater resistance to feedback inhibition than their respective single-site mutants. The E. coli strain carrying the aroG8/15 allele produced a phenylalanine titer of 26.78 g/l, a 116 % improvement over the control phenylalanine overproducing strain (12.41 g/l). Our findings provide an effective method for modifying phenylalanine biosynthetic genes, which may be applied to optimize the commercial manufacture of phenylalanine.

A modified version of the digestion-ligation cloning method for more efficient molecular cloning.

Here we describe a modified version of the digestion-ligation approach for efficient molecular cloning. In comparison with the original method, the modified method has the additional steps of gel purification and a second ligation after the first ligation of the linearized vector and DNA insert. During this process, the efficiency and reproducibility could be significantly improved for both stick-end cloning and blunt-end cloning. As an improvement of the very important molecular cloning technique, this method may find a wide range of applications in bioscience and biotechnology.

Recombinant Salmonella-based 4-1BBL vaccine enhances T cell immunity and inhibits the development of colorectal cancer in rats: in vivo effects of vaccine containing 4-1BBL.

BACKGROUND: Immunotherapy with vaccines is attractive for the treatment of cancer. This study is aimed at determining the effect of recombinant Salmonella (SL3261)-based 4-1BB ligand (4-1BBL) vaccine on the development of colorectal cancers and the potential immune mechanisms in rats. RESULTS: In comparison with that in the PBS group, similar levels of 4-1BBL expression, the frequency of T cells, IFN-γ responses, and comparable numbers of tumors were detected in the SL3261 and SL3261C groups of rats. In contrast, significantly fewer numbers of tumors, increased levels of 4-1BBL expression in the spleens and colorectal tissues, higher frequency of peripheral blood and splenic CD3+CD25+ T cells, and stronger splenic T cell IFN-γ responses were detected in the SL3261R group of rats. CONCLUSION: Our results indicated that vaccination with recombinant attenuated Salmonella harboring the 4-1BBL gene efficiently enhanced T cell immunity and inhibited the development of carcinogen-induced colorectal cancers in rats.

Prevalence and distribution profiles of Candida parapsilosis, Candida orthopsilosis and Candida metapsilosis responsible for superficial candidiasis in a Chinese university hospital.

The Candida parapsilosis complex consists of C. parapsilosis sensu stricto, C. orthopsilosis and C. metapsilosis. Recently, many studies described the prevalence of this species complex mainly in invasive candidiasis. Additionally, data showed that these three species are different in virulence and in vitro drug susceptibility. However, to our knowledge, the prevalence and distribution of the species complex in superficial candidiasis is not very clear to date. In this study, 2,128 Candida isolates from specimens of superficial candidiasis were collected over a 1-year period. Combination of routine and molecular tools, a total of 214 samples were identified to be positive for the C. parapsilosis complex (10.1%), of which 198 (92.5%) were monofungal and 16 (7.5%) were polyfungal. Among the 198 monofungal isolates, 191 (96.5%) were identified as C. parapsilosis sensu stricto, 5 (2.5%) as C. metapsilosis, and 2 (1.0%) as C. orthopsilosis species based on the molecular method. All C. parapsilosis complex isolates from the 16 polyfungal populations were found to be C. parapsilosis sensu stricto. Further analysis showed that the distribution profiles of the C. parapsilosis complex in adult patients were different from that in pediatric patients, and the prevalence rate of it varied greatly by sites of isolation. This study provides insight into the epidemiology of the species complex in superficial candidiasis.

A synthetic multi-epitope antigen enhances hepatitis C virus-specific B- and T-cell responses.

Combining results from previous studies, a multi-epitope antigen PCXZ against the hepatitis C virus was synthesized in this study. The antigenic specificity of PCXZ was determined by recognizing antibodies in serum samples from hepatitis C virus patients, but not from healthy subjects or subjects who had the hepatitis B virus. The characteristics of PCXZ immunogenicity were evaluated in BALB/c mice. Strong antibody responses were generated in mice immunized with either naked PCXZ or PCXZ in Freund's adjuvant. As for the T-cell responses, Freund's adjuvant significantly increased interferon-γ secretion and enhanced the lytic activity of cytotoxic T lymphocytes. The epitope Pa, one component of PCXZ, made the most significant contribution to specific CTL lysis; this epitope was also a B-cell epitope and was able to induce high IgG titers. In summary, PCXZ was found to be highly immunogenic, and elicited both humoral and cellular immune responses in mice.

Attenuated Salmonella typhimurium carrying shRNA-expressing vectors elicit RNA interference in murine bladder tumors.

AIM: To examine whether attenuated Salmonella typhimurium (S typhimurium) could be used as an anti-cancer agent or a tumor-targeting vehicle for delivering shRNA-expressing pDNA into cancer cells in a mouse tumor model. METHODS: Mouse bladder transitional cancer cell line (BTT-T739) expressing GFP was used, in which the GFP expression level served as an indicator of RNA interference (RNAi). BTT-T739-GFP tumor-bearing mice (4-6 weeks) were treated with S typhimurium carrying plasmids encoding shRNA against gfp or scrambled shRNA. The mRNA and protein expression levels of GFP were assessed 5 d after the bacteria administration, and the antitumor effects of S typhimurium were evaluated. RESULTS: In BTT-T739-GFP tumor-bearing mice, S typhimurium (1×10(9) cfu, po) preferentially accumulated within tumors for as long as 40 d, and formed a tumor-to-normal tissue ratio that exceeded 1000/1. S typhimurium carrying plasmids encoding shRNA against gfp inhibited the expression of GFP in tumor cells by 73.4%. Orally delivered S typhimurium significantly delayed tumor growth and prolonged the survival of tumor-bearing mice. CONCLUSION: This study demonstrates that attenuated S typhimurium can be used for both delivering shRNA-expressing vectors into tumor cells and eliciting RNAi, thus exerting anti-tumor activity, which may represent a new strategy for the treatment of solid tumors.

Proliferating cells in suborbital tissue drive eye migration in flatfish.

The left/right asymmetry of adult flatfishes (Pleuronectiformes) is remarkable given the external body symmetry of the larval fish. The best-known change is the migration of their eyes: one eye migrates from one side to the other. Two extinct primitive pleuronectiformes with incomplete orbital migration have again attracted public attention to the mechanism of eye migration, a subject of speculation and research for over a century. Cranial asymmetry is currently believed to be responsible for eye migration. Contrary to that hypothesis, we show here that the initial migration of the eye is caused by cell proliferation in the suborbital tissue of the blind side and that the twist of frontal bone is dependent on eye migration. The inhibition of cell proliferation in the suborbital area of the blind side by microinjected colchicine was able to prevent eye migration and, thereafter, cranial asymmetry in juvenile Solea senegalensis (right sideness, Soleidae), Cynoglossus semilaevis (left sideness, Cynoglossidae), and Paralichthys olivaceus (left sideness, Paralichthyidae) with a bottom-dwelling lifestyle. Our results correct the current misunderstanding that eye migration is driven by the cranial asymmetry and simplify the explanation for broken left/right eye-symmetry. Our findings should help to focus the search on eye migration-related genes associated with cell proliferation. Finally, a novel model is proposed in this research which provides a reasonable explanation for differences in the migrating eye between, and sometimes within, different species of flatfish and which should aid in our overall understanding of eye migration in the ontogenesis and evolution of Pleuronectiformes.

The PADI4 gene does not contribute to genetic susceptibility to rheumatoid arthritis in Chinese Han population.

The Peptidyl arginine deiminase, type IV (PADI4) gene has been suggested to have an association with rheumatoid arthritis (RA) in several populations. But its role in Chinese RA is not clarified. We investigated five single-nucleotide polymorphisms (SNPs) of PADI4 as PADI4-89 (rs11203366), PADI4-90 (rs11203367), PADI4-92 (rs874881) PADI4-94 (rs2240340), and PADI4-104 (rs1748033) in Chinese Han population. A total of 378 unrelated RA patients and 204 healthy controls were genotyped for the five SNPs. Individual allele, genotype and haplotype frequencies were compared between patients and controls. No significant differences in the frequency of PADI4 alleles, genotypes and haplotypes were observed between the patients and controls except PADI4-92. These data indicated that PADI4 polymorphisms were unlikely to play an important role in the susceptibility to RA in Chinese Han population.

Perilla frutescens seed agar, a new medium for identification of the Cryptococcus species complex: evaluation for all major molecular types.

Here we present a new and simple medium made by Perilla frutescens seed as a tool for identification of the Cryptococcus species complex, namely Cryptococcus neoformans and Cryptococcus gattii. Its usefulness was evaluated for all major molecular types within the Cryptococcus species complex. As a result, this medium is better for identification of the species complex compared with Guizotia abyssinica or Helianthus annuus seed medium.

Tumor antigen delivered by Salmonella III secretion protein fused with heat shock protein 70 induces protection and eradication against murine melanoma.

Attenuated Salmonella typhimurium possess the ability to stimulate innate immune responses and preferentially allocate within the solid tumor. These two main characteristics make attenuated Salmonella one of the most attractive vehicles for development of vaccine and also targeted cancer therapies. However, location of Salmonella prevents the process of antigen presentation. Salmonella Type III secretion system can be utilized to circumvent this problem because this system secretes the protein it encoded outside the cells. Heat shock protein 70 (Hsp70) is referred to as an "immunochaperone" for its capacity to elicit tumor-specific adaptive immune responses in the form of Hsp70-TAA (tumor associated antigen) complex. Hsp70 facilitates the cross-presentation of exogenous antigens through its receptor on antigen-presenting cells and therefore activates an antigen-specific cytotoxic T lymphocyte (CTL) response, which can directly contribute to potent anti-tumor immunity. Here, we designed a novel therapeutic vaccine utilizing the type III secretion system and Hsp70 to deliver and present the tumor-specific antigen. This live recombinant bacteria vaccine, when administrated orally, successfully broke the immune tolerance, induced a specific CTL response against tumor cells, and therefore revealed protective and therapeutic effects against generation and growth of B16F10 melanoma in C57BL/6J mice.

Rapid differentiation of VGII/AFLP6 genotype within Cryptococcus gattii by polymerase chain reaction.

VGII/AFLP6 genotype, also considered to be a cryptic species within Cryptococcus gattii, is an emerging pathogen and always related to higher incidence of C. gattii infection. Here, a polymerase chain reaction-based method with specific primers was developed to rapid differentiation of this emerging pathogen.

Enzymatic synthesis of 2'-deoxyadenosine and 6-methylpurine-2'-deoxyriboside by Escherichia coli DH5alpha overexpressing nucleoside phosphorylases from Escherichia coli BL21.

Genes encoding purine nucleoside phosphorylase (deo D), uridine phosphorylase (udp) and thimidine phosphorylase (deo A) from Escherichia coli BL21 were cloned and overexpressed in E. coli DH5alpha. The recombinant strains were employed to synthesize 2'-deoxyadenosine (dAR) and 6-methylpurine-2'-deoxyriboside (MePdR). Experimental parameters such as strains, temperature, pH, reagent concentration and cell mass were optimized. Under the optimal situation, 96% adenine was converted to dAR and 95% 6-methylpurine (MeP) was converted to MePdR in an hour, using 0.2 per thousand (dry wt./v) cell paste as biocatalyst.