Phylogenetic relationships and molecular evolution of woody forest tree family Aceraceae based on plastid phylogenomics and nuclear gene variations.

The forest tree family Aceraceae is widespread in the northern hemisphere and it has ecological and economic importance. However, the phylogenetic relationships and classifications within the family are still controversial due to transitional intraspecific morphological characteristics and introgression hybridization among species. In this study, we determined the evolutionary relationships and molecular evolution of Aceraceae based on plastid phylogenomics and two nuclear gene variations. Phylogenetic analysis based on the plastid genomes suggested that Aceraceae species can be divided into two larger sub-clades corresponding to the two genera Acer and Dipteronia. Conjoint analysis of the plastid and nuclear gene sequences supported the classification with two genera in the family. Molecular dating showed that the two genera diverged 60.2 million years ago, which is generally consistently with previously reported results. Divergence hotspots and positively selected genes identified in the plastid genomes could be useful genetic resources in Aceraceae.

Highly Sensitive, Simple, and Cost- and Time-Effective Method to Determine the Absolute Configuration of a Secondary Alcohol Using Competing Enantioselective Acylation Coupled with LC/MS.

The absolute-configuration determination of natural products and synthetic compounds with stereogenic centers is very important because stereoisomers dramatically and differentially affect many crucial properties, such as physical behaviors and biological functions. Despite several established methods for determining the absolute configuration, significant unmet needs for new methods still exist owing to the specific limitations of established methodologies. Here, we present a simple, optimized, new chemical-derivative method that utilizes competing enantioselective acylation followed by LC/MS analysis, and we demonstrate its successful application in determining the absolute configuration of a secondary alcohol in natural products with multiple reactive functional groups. This new development relies on the enantiomeric pair of homobenzotetramisole (HBTM) catalysts exhibiting adequate kinetic resolution for acylation of the secondary alcohol, and then the fast reaction was quantitatively confirmed via LC/MS as the characterization technique for the enantioselective transformations. Our new approach was successfully applied to determine the absolute configuration of one secondary alcohol in compound 1, which has other hydroxyl groups to be reacted. The identified stereocenter of 1 was verified by previously established methods including quantum chemical electronic-circular-dichroism (ECD) calculations, computational NMR-chemical-shift calculations followed by DP4+ calculations, and modified Mosher's method. In addition, our method was applied to five known naturally occurring compounds, which led to the successful verification of their absolute configurations. Our newly developed method using the HBTM catalyst provides a highly sensitive, simple, and cost- and time-effective approach and an applicable and convenient analytical method for determining the absolute configuration of one secondary alcohol in natural products.

The complete chloroplast genome of Dipteronia sinensis (Aceraceae), an endangered endemic species to China.

The complete chloroplast sequence of D. sinensis was reported in this study. The total length was 157 080 bp containing a pair of 26 766 bp inverted repeat regions (IRa and IRb), which were separated by a small single copy regions and a large single copy regions (SSC and LSC) of 18 093 and 85 455 bp, respectively. A total of 138 functional genes were annotated, which included 90 protein-coding genes, 40 tRNAs, and eight rRNA genes. The overall GC content of the complete chloroplast genome is 37.8% and in LSC, SSC and IR regions were 35.9%, 32.1%, and 42.7%, respectively. The maximum likelihood (ML) phylogenetic analysis revealed that D. sinensis was closely related to A. buergerianum subsp. Ningpoense in Sapindales order.

The complete chloroplast genome sequence of Acer morrisonense (Aceraceae).

Acer morrisonense (Aceraceae) is an important forest tree species and is endemic to Taiwan area. In this study, we determined the complete nucleotide sequence of A. morrisonense chloroplast genome (cpDNA) by using next-generation sequencing. The cpDNA was 157 197 bp in size, contained a pair of 26 728 bp inverted repeat (IR) regions, which were separated by a large single copy region (LSC) and a small single copy (SSC) region of 85 655 and 18 086 bp, respectively. The cpDNA contained 134 genes, including 86 protein-coding genes (78 PCG species), 8 ribosomal RNA genes (four rRNA species), and 40 transfer RNA genes (31 tRNA species). The most of gene species occur as a single copy, while 21 gene species occur in double copies. The overall AT content of A. morrisonense chloroplast genome were 62.2%, while the corresponding values of the LSC, SSC, and IR regions were 64.0%, 67.9%, and 57.3%, respectively. The phylogenetic analysis suggested that the cpDNA of A. morrisonense is closely related to that of congeneric A. buergerianum subsp. ningpoense.

Acylated Triterpene Saponins from the Stem Bark of Acer nikoense (Aceraceae).

Three new acylated triterpene saponins, acernikoenosides A-C (1-3), were isolated from the stem bark of Acer nikoense, together with a known sterol glucoside. Their structures were elucidated on the basis of extensive spectroscopic analyses. This study provided the first example of triterpene saponins isolated from this plant. The anti-genotoxic activity of 1, 3 and 4 against ultraviolet irradiation was evaluated by comet assay.

Transcriptome Sequencing and Development of Genic SSR Markers of an Endangered Chinese Endemic Genus Dipteronia Oliver (Aceraceae).

Dipteronia Oliver (Aceraceae) is an endangered Chinese endemic genus consisting of two living species, Dipteronia sinensis and Dipteronia dyeriana. However, studies on the population genetics and evolutionary analyses of Dipteronia have been hindered by limited genomic resources and genetic markers. Here, the generation, de novo assembly and annotation of transcriptome datasets, and a large set of microsatellite or simple sequence repeat (SSR) markers derived from Dipteronia have been described. After Illumina pair-end sequencing, approximately 93.2 million reads were generated and assembled to yield a total of 99,358 unigenes. A majority of these unigenes (53%, 52,789) had at least one blast hit against the public protein databases. Further, 12,377 SSR loci were detected and 4179 primer pairs were designed for experimental validation. Of these 4179 primer pairs, 435 primer pairs were randomly selected to test polymorphism. Our results show that products from 132 primer pairs were polymorphic, in which 97 polymorphic SSR markers were further selected to analyze the genetic diversity of 10 natural populations of Dipteronia. The identification of SSR markers during our research will provide the much valuable data for population genetic analyses and evolutionary studies in Dipteronia.

HPLC and GC-MS Analysis of Phenolic Substances in Acer tegmentosum

The stem barks, heartwoods, and leaves of Acer tegmentosum (Aceraceae) are widely used in Korea to treat hepatic or cerebral disorders mainly due to alcohol poisoning. This study was aimed to analyze phenolic substances in A. tegmentosum. Quantitative analysis of the three phenolic substances (salidroside, (+)-catechin and scopoletin) was performed by HPLC and the identification of volatile phenolic substances were done by GC-MS. The contents of the three compounds in the three MeOH extracts were higher in the stem bark (salidroside: 80.22 mg/g, (+)-catechin: 23.31 mg/g, and scopoletin: 9.45 mg/g) compared to the heartwoods and leaves. And GC-MS analysis of the stem bark extract demonstrated that p-tyrosol is a main substance of twenty-one compounds identified.

Tree pollen spectra and pollen allergy risk in the Osijek-Baranja County.

The forests of north-eastern Croatia, as well as various plants and trees in the parks and streets of the Osijek-Baranja County, produce large amounts of pollen during the pollen season, which can cause allergy symptoms in pollen sensitive individuals. The aim of this study was to determine the most frequent types of pollen in this area and estimate possible health risks, especially the risk of allergy. In 2009 and 2010, the staff of the Health Ecology Department of the Osijek Public Health Institute monitored tree pollen concentrations in four cities from the Osijek - Baranja County (Osijek, Nasice, Dakovo and Beli Manastir) using a Burkard volumetric instrument. The results were affected by weather conditions. Windy and sunny days facilitated the transfer of pollen, whereas during rainy days, the concentration of pollen grains decreased. High pollen concentrations of Cupressaceae/Taxaceae, Betulaceae, Salicaceae and Aceraceae could be the cause for symptoms of pollen allergy. In 2009, conifers, birch and poplar pollen were dominant at all monitoring stations with 5000 pollen grains (PG), 3188 PG and 3113 PG respectively. The highest number of pollen grains was recorded at measuring site Osijek. The variations in airborne pollen concentration between pollen seasons were recorded at all monitoring stations. The most obvious variations were recorded at measuring site Osijek. The usual pollination period lasts two to three months, which means that most pollen grains remain present from February to early June. However, the Cupressaceae / Taxaceae pollination periods last the longest and their pollen grains remain present until the end of summer. The risk of allergy was determined at four monitored measuring stations and the obtained data confirmed that the largest number of days with a high health risk was at the Dakovo measuring station for a species of birch. The research information aims to help allergologists and individuals allergic to plant pollen develop preventive measures and proper treatment therapies.

The major Platanus acerifolia pollen allergen Pla a 1 has sequence homology to invertase inhibitors.

BACKGROUND: Sycamores or plane trees are an important source of airborne allergens in many cities of the United States and Western Europe. Pla a 1 has been described as a major allergen from Platanus acerifolia (London plane tree). OBJECTIVE: To clone and characterize the cDNA for Pla a 1 and to express the recombinant protein. METHODS: Pla a 1 was isolated by cationic exchange, gel filtration, and reverse-phase chromato-graphies. Pla a 1 cDNA was cloned by reverse transcription followed by polymerase chain reaction, using amino acid sequences from tryptic peptides of the allergen. The Pla a 1 encoding sequence has been subcloned into the pKN172 expression vector and expressed in Escherichia coli as a non-fusion protein. Purified recombinant protein has been tested for its IgE-binding capacity in immunoblot, immunoblot inhibition, and ELISA. RESULTS: Pla a 1 reacted with serum IgE from 35 of the 42 (83.3%) Platanus-allergic patients studied and represented 60% of the total IgE-binding capacity of the P. acerifolia pollen extract. The allergen displayed 43% sequence identity to a grape invertase inhibitor and showed a predicted secondary structure characteristic of all-alpha proteins. Serological analysis revealed that both natural and recombinant forms of Pla a 1 displayed similar IgE-binding capacity. CONCLUSIONS: Pla a 1 belongs to a new class of allergens related to proteinaceous invertase inhibitors. Recombinant Pla a 1 binds IgE in vitro like its natural counterpart and, therefore, it can be useful for specific diagnosis and structural studies.