Nitrogen fertilizer affects rhizosphere Cd re-mobilization by mediating gene AmALM2 and AmALMT7 expression in edible amaranth roots.

In-situ stabilization of Cd-contaminated farmland is a commonly used remediation technology. Yet, rhizosphere metabolites (e.g., organic acids) during crop cultivation may cause Cd re-mobilization and over-accumulation. Here, we identified four pivotal cytomembrane-localized genes underlying Cd accumulation difference between two contrasting edible amaranth cultivars based on root gene expression profile, studied their subcellular localization and functional characteristics, and then investigated effects of nitrogen fertilizer on their expression and rhizosphere Cd re-mobilization. Results showed that more Cd accumulated by edible amaranth was due to rhizosphere Cd mobilization by mediating high expression of AmALMT2 and AmALMT7 genes, not Cd transporters in roots. This was confirmed by heterologous expression of AmALMT2 and AmALMT7 genes in Arabidopsis thaliana, since they mediated malic, fumaric, succinic, and aspartic acids efflux. Furthermore, nitrogen influencing rhizosphere acidification might be closely associated with organic acids efflux genes. Compared with N-NO3- application, N-NH4+ was massively assimilated into glutamates and oxaloacetates through up-regulating glutamine synthetase and alanine-aspartate-glutamate metabolic pathways, thereby enhancing TCA cycle and organic acids efflux dominated by binary carboxylic acids via up-regulating AmALMT2 and AmALMT7 genes, which finally caused Cd re-mobilization. Therefore, N-NO3--dominated nitrogen retarded rhizosphere Cd re-mobilization via inhibiting organic acids efflux function of AmALMT2 and AmALMT7 proteins.

[Surveillance on antibody levels of diphtheria, pertusis and tetanus in health population in Shenzhen].

OBJECTIVE: To know the antibody levels of DDT and the immunization effect of DPT vaccine in health population in Shenzhen, and to provide theoretic basis for the immunization strategy of DPT. METHODS: Antibody of pertusis was tested by agglutination tests, antibodies of diphtheria and tetanus were tested by IHA tests. RESULTS: The antibody positive rate of diphtheria, pertusis and tetanus were 88.31%, 71.54% and 92.77% respectively. The protective rate were 87.38%, 64.15% and 37.23% respectively. The GMT of diphtheria, pertusis and tetanus were 0.2595, 0.5607 and 1:156.87 respectively. CONCLUSION: The antibody levels of diphtheria, pertusis and tetanus decreased by age, we should carry out DT booster immunization in freshmen of middle school, colleges and adults.