Cadmium stimulated cooperation between bacterial endophytes and plant intrinsic detoxification mechanism in Lonicera japonica thunb.

Due to the intimate association between plant physiology and metabolism, the internal colonizing microbe (endophytes) community must be adjusted to support plant productivity in response to cell damage in plants under stress. However, how endophytes coordinate their activities with plant intrinsic mechanisms such as antioxidative systems and detoxification pathways during Cd accumulation remains unknown. In this hydroponic pot study, we investigated how exposure of Lonicera japonica. thunb. to different levels of Cd (0.5, 2.5, 5, 10, and 20 mg kg-1) affected plant growth, metabolic pathways, and endophyte community structure and function. Although Cd accumulation increased at 5 mg kg-1 Cd, the biomass and height of L. japonica increased in association with elevated endophyte-involved plant detoxification activities. Endophytes, such as Sphingomonas, Klenkia, and Modestobacter, expressed major antioxidative regulators (superoxide dismutase and ascorbate acid) to detoxify Cd in L. japonica. Furthermore, L. japonica and its endophytes synergistically regulated the toxic effects of Cd accumulation via multiple plant metabolic defensive pathways to increase resistance to metal-induced stress.

[Establishment of microarray for detecting mutation in HBV pre-core/core and basic core promoter regions].

OBJECTIVE: To develop a sensitive and specific microarray for detecting mutations of HBV pre-core/core and basic core promoter regions in the clinic. METHODS: Site-specific oligonucleotide probes were designed and immobilized to microarray slides and hybridized to HBV gene fragments amplified with specific biotin-labeled primer using asymmetrical PCR. The specificity and sensitivity of the method were estimated. And the microarray was applied to detect 138 clinical serum samples with HBV-DNA. RESULTS: The mutations of HBV pre-core/core and basic core promoter regions can be specifically detected using the microarray, and the sensitivity was 1 x 10(1) copies/microl. Among 138 samples, 40 samples had T1762/ A1764 mutation, 11 samples had C1814 mutation, and 16 samples had A1896 mutation. The A1896 mutation rate in high HBV-DNA load group was significantly higher than that in low HBV-DNA load group (P < 0.01). CONCLUSION: An DNA microarray assay was successfully established to detect the mutations in HBV pre-core/core and basic core promoter regions. The A1896 mutation in pre-core/core region maybe involve in duplication of HBV.