No abstract

We expressed the heat-labile enterotoxin B (LTB) subunit from enterotoxigenic Escherichia coli and the cholera toxin B (CTB) subunit from Vibrio cholerae under the control of the rice (Oryza sativa) globulin (Glb) promoter. Binding of recombinant LTB and CTB proteins was confirmed based on GM1-ganglioside binding enzyme-linked immunosorbent assays (GM1-ELISA). Real-time PCR of three generations (T3, T4, and T5) in homozygous lines (LCI-11) showed single copies of LTB, CTB, bar and Tnos. LTB and CTB proteins in rice transgenic lines were detected by Western blot analysis. Immunogenicity trials of rice-derived CTB and LTB antigens were evaluated through oral and intraperitoneal administration in mice, respectively. The results revealed that LTB- and CTB-specific IgG levels were enhanced in the sera of intraperitoneally immunized mice. Similarly, the toxin-neutralizing activity of CTB and LTB in serum of orally immunized mice was associated with elevated levels of both IgG and IgA. The results of the present study suggest that the combined expression of CTB and LTB proteins can be utilized to produce vaccines against enterotoxigenic strains of Escherichia coli and Vibrio cholera, for the prevention of diarrhea.

The objective of this study was to investigate the suitable parts for callus induction and optimal concentrations of growth regulators contained in the medium affecting shooting and rooting Echeveria laui and Echeveria elegans for in vitro mass production. To determine the suitable plant parts for callus induction, the leaves were divided into upper, medium and bottom parts and cultured on MS medium at different concentrations with 0~2 mgL-1 NAA and 0~4 mgL-1 BA. The upper and middle parts of leaves both showed 100% callus formation rate with NAA 1 mgL-1 and BA 1 mgL-1 treatment in E. laui. The middle parts of leaves showed 83.3% callus formation rate at NAA 2 mgL-1 and BA 4 mgL-1 treatment in E. elegans. The shoot induction rate from callus was highest at NAA 0.1 mgL-1 and BA 3 mgL-1 treatment in E. laui and NAA 0.3 mgL-1 in E. elegans. In addition, the number of shoots formation was 10.4 shoots high in NAA 1 mg L-1 and BA 1 mgL-1 treatment in E. laui and 12.0 shoots in most effective NAA 1 mgL-1 and BA 0.1 mg L-1 treatment in E. elegans. In the case of acclimatization of regenerated plant, growth characteristics did not show any significant difference (35~55%) shading with respect to the different ratio of substrate mixture, and it was determined that would be appropriate considered plant height and appearance preference of E. laui and E. elegans. It was established that the optimization of culture condition was responsible for the mass propagation in vitro cultures of E. laui and E. elegans.