Delphinieae flowers originated from the rewiring of interactions between duplicated and diversified floral organ identity and symmetry genes.

Species of the tribe Delphinieae (Ranunculaceae) have long been the focus of morphological, ecological, and evolutionary studies due to their highly specialized, nearly zygomorphic (bilaterally symmetrical) spiral flowers with nested petal and sepal spurs and reduced petals. The mechanisms underlying the development and evolution of Delphinieae flowers, however, remain unclear. Here, by conducting extensive phylogenetic, comparative transcriptomic, expression, and functional studies, we clarified the evolutionary histories, expression patterns, and functions of floral organ identity and symmetry genes in Delphinieae. We found that duplication and/or diversification of APETALA3-3 (AP3-3), AGAMOUS-LIKE6 (AGL6), CYCLOIDEA (CYC), and DIVARICATA (DIV) lineage genes was tightly associated with the origination of Delphinieae flowers. Specifically, an AGL6-lineage member (such as the Delphinium ajacis AGL6-1a) represses sepal spur formation and petal development in the lateral and ventral parts of the flower while determining petal identity redundantly with AGL6-1b. By contrast, two CYC2-like genes, CYC2b and CYC2a, define the dorsal and lateral-ventral identities of the flower, respectively, and form complex regulatory links with AP3-3, AGL6-1a, and DIV1. Therefore, duplication and diversification of floral symmetry genes, as well as co-option of the duplicated copies into the preexisting floral regulatory network, have been key for the origin of Delphinieae flowers.

[Expression and immunogenicity analysis of EsxA protein of Staphylococcus aureus isolated from cow milk].

To study the immunogenicity of EsxA protein of Staphylococcus aureus, the EsxA-pET-28a recombinant plasmid was constructed and the expression product was analyzed by SDS-PAGE and Western blotting after the positive recombinant plasmid was induced by IPTG. Mice were immunized with purified EsxA protein and then the IgG, IgG1 and IgG2a antibody were detected with indirect ELISA. Then the histopathological examination, bacteria loading and immune protection of immunized mice were studied after challenge with S. aureus. The recombinant protein EsxA was successfully induced and expressed. After immunization the EsxA specific antibody titer could reach 1:900. Bacteria loading and pathological damage of liver, spleen and kidney were reduced after immunization with EsxA in the immunized mice. The protection rate of immunized mice was 75%. In conclusion, EsxA protein has good immunogenicity.