Analysis of trace microcystins in vegetables using solid-phase extraction followed by high performance liquid chromatography triple-quadrupole mass spectrometry.

A selective and sensitive method for the simultaneous detection of three common and hazardous microcystins (microcystins-LR, -RR, and -YR) in various vegetables was established using solid-phase extraction followed by high performance liquid chromatography coupled with mass spectrometry. The methanol-water proportion ratio of the extraction solvent and its acidity, as well as the efficiencies of solid-phase extraction, were evaluated to optimize a pretreatment procedure for extracting the microcystins from 10 vegetable matrices. The limits of detection and quantitation were below 7.5 µg/kg (dw) and 25 µg/kg (dw), respectively, in different vegetable matrices. The recoveries of the microcystins in the 10 vegetable matrices ranged from 61.3 to 117.3%, with RSDs of 0.2-18.3%. The established method was used to analyze 28 field vegetable samples collected from the sides of Lake Dianchi, and microcystin-RR was found in almost all samples at concentrations of 36.4-2352.2 µg/kg (dw).

Expression of HIV-1 integrase in CEM cells inhibits HIV-1 replication.

BACKGROUND: HIV-1 integrase (IN) is an interesting target for the gene therapy of AIDS. Although the in vivo functions are not well characterized, it is thought that IN has pleiotropic effects and plays a central role in the interplay between the virus and the host cell. Expression of IN in mammalian cells has proven difficult. We have previously established a 293T-derived cell line that stably expresses high levels of HIV-1 IN from a synthetic gene. We now have constructed CEM-derived cell lines stably expressing the enzyme or its different domains and studied the impact of IN expression on HIV-1 replication. METHODS: The CEM cell lines were selected following transduction with a retroviral vector encoding the full-length IN, the N-terminal domain, the catalytic core or the C-terminal domain. Stable IN expression in CEM cell lines was verified by Western blotting. The impact of IN expression on HIV-1 replication and HIV-1 vector transduction was studied. RESULTS: A marked inhibitory effect on HIV-1 replication was observed in CEM cells expressing IN. Expression of IN interfered with both particle production and integration. Expression of the N-terminal domain alone was sufficient for the inhibiting of HIV-1 replication. CONCLUSIONS: Expression of IN in CEM cells inhibits HIV-1 replication by a cumulative inhibitory effect on integration and particle production, in accord with the known pleiotropic interactions of IN. The inhibition of HIV-1 replication in CEM cells expressing the N-terminal domain of IN may lead to a novel approach for the gene therapy of AIDS.