Analysis of cytosolic pH changes in thymocytes during early apoptosis with improved three-channel real-time fluorescence imaging.

Cytosolic pH changes in single thymocytes in the early stages of apoptosis were examined with spectral-crosstalk-improved three-channel real-time fluorescence imaging. Spectral crosstalk was greatly reduced by this improved image processing method. Compared with normal thymocytes, the improved image processing method showed that the cytosolic pH value of thymocytes undergoing apoptosis was lower. A slight diversity in the intracellular pH values of samples subjected to different drug treatments was also observed. This new image processing method is beneficial to the application of the three-channel real-time fluorescence imaging to biological processes.

Three-dimensional structural changes in living hippocampal neurons imaged using magnetic AC mode atomic force microscopy.

We developed the magnetic AC (MAC) mode atomic force microscopy (AFM) to image the 3D ultrastructure of living hippocampal neurons under physiological conditions. Initially, the soma, the dendrites and the growth cones of hippocampal neurons were imaged. The imaging force was adjusted to a small value for the long-term observation. The neural spines were damaged when the tip produced a large force; the spines regenerated after the force was reduced. Subsequently, we explored the relationship between structural changes in hippocampal neurons and Alzheimer's disease by employing the new imaging technique. Time-lapse image acquisition (10 min intervals) showed that the growth cone collapsed after the addition amyloid peptide fragment beta(25-35), which is thought to initiate Alzheimer's disease. In addition, we found substantial changes in mechanical properties and in the volume of individual growth cone. This study suggested that MAC mode AFM may be a powerful tool for observing long-term structural changes in living neural cells under physiological conditions.

p73 activation is involved in regulation of Ara-C-induced apoptosis in human lung adenocarcinoma cells / 解剖学报

Objective To study the apoptosis pathway of human lung adenocarcinoma cell line A549 induced by 1-β-D-arabinofuranosylcytosine (Ara-C) in vitro. Methods A549 cells were incubated with Ara-C for 72hours in vitro. Biological changes of apoptotic cells were studied by TUNEL staining. Morphological changes of the A549 cells treated with Ara-C were observed by transmission electron microscope. The expressions of p53 and p73 were investigated by Western blotting. Results 1.Apoptotic rates of A549 cells exposure to Ara-C studied by TUNEL staining were higher than that of the control (P＜0.01). 2.Apoptosis body was apparently observed by transmission electron microscope. 3.Endogenous p73 but not p53 was induced and activated in dose-dependent manner upon Ara-C treatment by Western blotting.Conclusion Ara-C can effectively induce apoptosis of A549 cells. DNA damage-induced apoptosis of A549 cells treated by Ara-C is independent of functional p53.Up-regulation of p73 may play an important role that enhances the sensitivity of A549 cells to Ara-C and be partly responsible for p53-independent apoptosis.