Recombinant Human SCARB2 Expressed in Escherichia coli and its Potential in Enterovirus 71 Blockage.

Hand, foot and mouth disease is a common viral infectious disease caused by enteroviruses, including coxsackie A16 (CVA16) and enterovirus 71 (EV71). HFMD can cause severe symptoms in children which can be fatal. Human scavenger receptor class B member 2 (SCARB2) is a cellular receptor for EV71 and CVA16, providing a potential approach for preventing EV71 infection and transmission. In this present study, we constructed and assessed the potential of recombinant SCARB2, using E. coli expression system. To generate this construct, scarb2 gene was cloned into pET22b vector and expressed in E. coli BL21 (DE3). The expression of SCARB2 was induced by 0.1 mM IPTG and analyzed using SDS-PAGE, followed by Western blot. Expressed SCARB2 was in inclusion bodies and refolded to obtain the soluble form with recovery efficacy of 100%. This recombinant protein was then validated for binding with EV71 via indirect ELISA in two different pHs (7.4 and 5.5), which partially revealed the mechanism of virus-receptor interaction. These results envisaged potential applications for utilizing recombinant SCARB2 in preventing the virus transmission.

Molecular Identification and Evaluation of the Genetic Diversity of Dendrobium Species Collected in Southern Vietnam.

Dendrobium has been widely used not only as ornamental plants but also as food and medicines. The identification and evaluation of the genetic diversity of Dendrobium species support the conservation of genetic resources of endemic Dendrobium species. Uniquely identifying Dendrobium species used as medicines helps avoid misuse of medicinal herbs. However, it is challenging to identify Dendrobium species morphologically during their immature stage. Based on the DNA barcoding method, it is now possible to efficiently identify species in a shorter time. In this study, the genetic diversity of 76 Dendrobium samples from Southern Vietnam was investigated based on the ITS (Internal transcribed spacer), ITS2, matK (Maturase_K), rbcL (ribulose-bisphosphate carboxylase large subunit) and trnH-psbA (the internal space of the gene coding histidine transfer RNA (trnH) and gene coding protein D1, a polypeptide of the photosystem I reaction center (psaB)) regions. The ITS region was found to have the best identification potential. Nineteen out of 24 Dendrobium species were identified based on phylogenetic tree and Indel information of this region. Among these, seven identified species were used as medicinal herbs. The results of this research contributed to the conservation, propagation, and hybridization of indigenous Dendrobium species in Southern Vietnam.

Complete Chloroplast Genome of Paphiopedilum delenatii and Phylogenetic Relationships among Orchidaceae.

Paphiopedilum delenatii is a native orchid of Vietnam with highly attractive floral traits. Unfortunately, it is now listed as a critically endangered species with a few hundred individuals remaining in nature. In this study, we performed next-generation sequencing of P. delenatii and assembled its complete chloroplast genome. The whole chloroplast genome of P. delenatii was 160,955 bp in size, 35.6% of which was GC content, and exhibited typical quadripartite structure of plastid genomes with four distinct regions, including the large and small single-copy regions and a pair of inverted repeat regions. There were, in total, 130 genes annotated in the genome: 77 coding genes, 39 tRNA genes, 8 rRNA genes, and 6 pseudogenes. The loss of ndh genes and variation in inverted repeat (IR) boundaries as well as data of simple sequence repeats (SSRs) and divergent hotspots provided useful information for identification applications and phylogenetic studies of Paphiopedilum species. Whole chloroplast genomes could be used as an effective super barcode for species identification or for developing other identification markers, which subsequently serves the conservation of Paphiopedilum species.

Systematic characterisation of the structure and radical scavenging potency of Pu'Er tea () polyphenol theaflavin.

The structure, energetics and radical scavenging potency of theaflavin (TF), a natural polyphenolic antioxidant found in oxidised tea, have been characterised by a series of density functional theory (DFT) determinations. Exploratory conformational searches yielded 153 distinct neutral structures. Results showed TF's structural preferences to be regulated by its unique fused double ring benzotropolone moiety, and its degree of planarity, with structural diversity, principally arising from variations of its nine -OH groups. The distinct 3D conformational 'poses' are shown to be stabilised by a complex network of intra-system interactions, damping overall structural floppiness. This rigidification, together with stability, is shown to be coupled with radical scavenging potency in the TF system. Radical scavenging via hydrogen atom abstraction (HAB) in H2O solution was determined to be spontaneous with very low reaction barriers (ΔGrel ∼ 4 kJ mol-1).

Genetic Diversity and Identification of Vietnamese Paphiopedilum Species Using DNA Sequences.

Paphiopedilum is among the most popular ornamental orchid genera due to its unique slipper flowers and attractive leaf coloration. Most of the Paphiopedilum species are in critical danger due to over-exploitation. They were listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora, which prevents their being traded across borders. While most Paphiopedilum species are distinctive, owing to their respective flowers, their vegetative features are more similar and undistinguished. Hence, the conservation of these species is challenging, as most traded specimins are immature and non-flowered. An urgent need exists for effective identification methods to prevent further illegal trading of Paphiopedilum species. DNA barcoding is a rapid and sensitive method for species identification, at any developmental stage, using short DNA sequences. In this study, eight loci, i.e., ITS, LEAFY, ACO, matK, trnL, rpoB, rpoC1, and trnH-psbA, were screened for potential barcode sequences on the Vietnamese Paphiopedilum species. In total, 17 out of 22 Paphiopedilum species were well identified. The studied DNA sequences were deposited to GenBank, in which Paphiopedilum dalatense accessions were introduced for the first time. ACO, LEAFY, and trnH-psbA were limited in amplification rate for Paphiopedilum. ITS was the best single barcode. Single ITS could be used along with nucleotide polymorphism characteristics for species discrimination. The combination of ITS + matK was the most efficient identification barcode for Vietnamese Paphiopedilum species. This barcode also succeeded in recognizing misidentified or wrongly-named traded samples. Different bioinformatics programs and algorithms for establishing phylogenetic trees were also compared in the study to propose quick, simple, and effective tools for practical use. It was proved that both the Bayesian Inference method in the MRBAYES program and the neighbor-joining method in the MEGA software met the criteria. Our study provides a barcoding database of Vietnamese Paphiopedilum which may significantly contribute to the control and conservation of these valuable species.

In Silico Study on Molecular Sequences for Identification of Paphiopedilum Species.

Our study searched all available sequences of Paphiopedilum from NCBI (National Center for Biotechnology Information) and tested for their species resolution capability in single as well as in combination forms. A total of 28 loci were applied for analyses in the study. From the nuclear genome, the highest resolution was of LFY, followed by ACO, DEF4, and RAD51. These 4 loci were found to be even better than the popular region ITS for Paphiopedilum identification. Among the chloroplast regions, the intergenic spacer atpB-rbcL gave the highest species resolution (76.7%), followed by matK, trnL, rpoC2, and ycf1. The divergence of CHS, XDH, 18S, Nad1, ccsA, rbcL, and ycf2 was very low and should not be used as identifying markers for Paphiopedilum. In addition, 2-locus combinations could improve significantly the resolving capability for the genus, in which 14/36 data sets could be resolved completely (100%) with interspecies relationships. The indel information was also effective supporting data for molecular discrimination of species.