AIM:To study chromosome aberration due to ethidium bromide (EB), a heterocyclic organic compound and an organic fluorescence dye commonly used in biochemical experiment, and to help further understanding the molecular mechanism of tumor or cancer induced by EB and other heterocyclic organic compounds. METHODS: The toxicity action of EB was evaluated from three aspects including DNA, chromosome and embryo stem cells (ESCs) using atomic force microscopy (AFM), and thereinto, the morphology structural difference of ESCs treated with two EB doses was also valuated. RESULTS: The morphological structures of DNA, chromosome and ESCs were dramatically damaged. The average height of DNA decreased 0.5 nm; chromosomal arms were ruptured from centromere location; molecules of cellular membrane congregated and loop-like structure formed, and ES cell masses were collapsed and became dead after large EB doses treatment and mesh-like morphological structure was discernable. CONCLUSION: The toxicity action of EB is strong and destroys the surface structure of DNA and chromosome. EB induces structural aberration of ES cellular membrane and cell death. The results indicate that the action of EB is externalized at gene level and cell level, which is important to study the carcinogenicity of EB.

Scanning near-field optical microscopy (SNOM) is developing on the base of near-field optical theory and SPM technique, and producing the highest optical resolution to break through the diffraction limit. It is able to study cellular ultrastructure, function and interaction between biomolecules without destructing the living cells. Recent advances in applying SNOM to cellular and molecular biology were introduced in this review.

AIM: To study the cytoskeleton of mesench ymal stem cells (MSCs), the ultrastructure and function relationship by using atomic force microscope (AFM). METHODS: The ultrastructures and morphological feature of MSCs c ultured for 1 d and 5 d were studied by AFM. RESULTS: The special structures that possess peculiar morphologi cal characteristic of MSCs such as cytoskeleton, pseudopod, microfilament etc we re identified by AFM, and these special structures are difficult to observe unde r electronic microscopy or other conventional optical microscopy. CONCLUSIONS: AFM is a powerful tool to study ultrastructures, mo rphological features, and cytoskeleton of stem cells in near physiological condi t ions. Its application prospect in cellular biology is extensive. The special cyt oskeleton and other structures of MSCs observed above may represent the structur al base of multi-differentiation potential of MSCs.

Atomic force microscope (AFM) was used to study biotoxicity of food preservative sodium benzoate (SB) at the single cellular level. Lymphocyte morphology and membrane ultrastructure treated with SB at different concentrations and time were analyzed visually. As compared to the normal lymphocyte, the cell morphology and membrane was significantly changed and its ultrastructure was also complicated. After treated with SB, the Rp-v, Rq, Ra and Z values were changed. The statistical analysis of lymphocytes after treated with SB was studied, and discussed its mechanism.
Animals ; Cell Membrane ; ultrastructure ; Lymphocytes ; drug effects ; pathology ; Mice ; Mice, Inbred BALB C ; Microscopy, Atomic Force ; Sodium Benzoate ; toxicity