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The study on nucleic acid retention in ion-pair reversed-phase high-performance liquid chromatography mainly focuses on size-dependence, however, other factors influencing retention behaviors have not been comprehensively clarified up to date. In this present work, the retention behaviors of oligonucleotides and double-stranded DNAs were investigated on silica-based C stationary phase by ion-pair reversed-phase high-performance liquid chromatography. It is found that the retention of oligonucleotides was influenced by base composition and base sequence as well as size, and oligonucleotides prone to self-dimerization have weaker retention than those not prone to self-dimerization but with the same base composition. However, homo-oligonucleotides are suitable for the size-dependent separation as a special case of oligonucleotides. For double-stranded DNAs, the retention is also influenced by base composition and base sequence, as well as size. This may be attributed to the interaction of exposed bases in major or minor grooves with the hydrophobic alky chains of stationary phase. In addition, no specific influence of guanine and cytosine content was confirmed on retention of double-stranded DNAs. Notably, the space effect resulted from the stereostructure of nucleic acids also influences the retention behavior in ion-pair reversed-phase high-performance liquid chromatography.

A facile solvothermal method was developed for synthesis of magnetic nickel-based iron oxide nanocomposites (MNFOs) with different ratios of Ni2+ to Fe3+ for different reaction time. Two factors including dosage of Ni source and length of reaction were investigated for influence on the morphology and composition of MNFOs, as well as their distinct selectivity for different phosphopeptides. After thorough characterization, the possible formation mechanism of MNFOs was proposed. Very interestingly, MNFOs with Ni2+/Fe3+ ratios of 4:5 prepared for 8 h (MNFO-S) and for 24 h (MNFO-L) can selectively capture global- and monophosphopeptides at the fmol level with excellent enrichment performance. These two affinity probes have been exploited to isolate and enrich the phosphopeptides from human normal hepatic cells HL 7702 after exposure to atmospheric fine particulates (PM2.1), which revealed that the protein phosphorylation level was increased significantly in cells after stimulation by fine particulate matters. The findings could provide a new insight for the nickel-based affinity protocol to analyze the mutation of phosphopeptides during cellular signaling pathways in response to exogenous environment stimulation. Consequently, this present work proposed a promising strategy to isolate monophosphopeptides from global phosphopeptides for phosphoproteome research.

Foxj2 (forkhead box J2), a novel member of the forkhead/HNF3 family, binds DNA with a dual sequence specificity. It may play a role in maintenance and survival of developing and adult neurons. However, its expression and function in the central nervous system lesion are still unclear. In this study, we performed a spinal cord injury (SCI) model in adult Sprague-Dawley rats and investigated the dynamic changes of Foxj2 expression in the spinal cord. Western blot analysis revealed that Foxj2 was present in normal spinal cord. It gradually increased, reached a peak at day 5 after SCI, and then declined during the following days. Double immunofluorescence staining revealed wide expression of Foxj2, which is detected in neurons and astrocytes. After injury, Foxj2 expression was increased predominantly in astrocytes, which highly expressed proliferating cell nuclear antigen, a marker for proliferating cells. And knockdown of Foxj2 in cultured primary astrocytes by siRNA showed that Foxj2 played an important role in lipopolysaccharide-induced inflammatory responses. These results suggested that Foxj2 may be involved in the pathophysiology of SCI, and further research is needed to have a good understanding of its function and mechanism.