Comparative Analyses of Chloroplast Genomes for Parasitic Species of Santalales in the Light of Two Newly Sequenced Species, Taxillus nigrans and Scurrula parasitica.

When a flowering plant species changes its life history from self-supply to parasite, its chloroplast genomes may have experienced functional physical reduction, and gene loss. Most species of Santalales are hemiparasitic and few studies focus on comparing the chloroplast genomes of the species from this order. In this study, we collected and compared chloroplast genomes of 12 species of Santalales and sequenced the chloroplast genomes of Taxillus nigrans and Scurrula parasitica for the first time. The chloroplast genomes for these species showed typical quadripartite structural organization. Phylogenetic analysis suggested that these 12 species of Santalales clustered into three clades: Viscum (4 spp.) and Osyris (1 sp.) in the Santalaceae and Champereia (1 sp.) in the Opiliaceae formed one clade, while Taxillus (3 spp.) and Scurrula (1 sp.) in the Loranthaceae and Schoepfia (1 sp.) in the Schoepfiaceae formed another clade. Erythropalum (1 sp.), in the Erythropalaceae, appeared as a third, most distant, clade within the Santalales. In addition, both Viscum and Taxillus are monophyletic, and Scurrula is sister to Taxillus. A comparative analysis of the chloroplast genome showed differences in genome size and the loss of genes, such as the ndh genes, infA genes, partial ribosomal genes, and tRNA genes. The 12 species were classified into six categories by the loss, order, and structure of genes in the chloroplast genome. Each of the five genera (Viscum, Osyris, Champereia, Schoepfia, and Erythropalum) represented an independent category, while the three Taxillus species and Scurrula were classified into a sixth category. Although we found that different genes were lost in various categories, most genes related to photosynthesis were retained in the 12 species. Hence, the genetic information accorded with observations that they are hemiparasitic species. Our comparative genomic analyses can provide a new case for the chloroplast genome evolution of parasitic species.

Enhanced healing process of tooth sockets using strontium-doped TiO2.

Prevention of residual ridge resorption is important for tooth socket healing in clinical treatment. As a well known biomaterial, titanium dioxide (TiO2) has been reported to show desirable bone regeneration capability. On the other hand, strontium plays a role in maintaining normal function in organisms and balancing bone remodeling. Hence, we synthesized strontium-doped titanium dioxide mesoporous nanospheres functionalized with amino-group using diphenyl diisocyanate. After incorporation with segmented polyurethane, the obtained injectable SPU/Sr-TiO2/MDI nanocomposite adhesive showed satisfactory antibacterial activity and cell nontoxicity. This nanocomposite was used for tooth socket healing, and greatly promoted the formation of new bone tissue in the tooth extraction socket.