时间：2013年08月12日（星期一）下午13:30-15:00
地点：教三 338 会议室
Applications of ultrafast laser microsurgery
and live tissue imaging in biomedical research
Dr. Jun Cheng
Assistant Professor， Department of Bioengineering
University of Illinois at Chicago， Illinois 60607, USA
Abstract
Ever since their invention, laser and optical imaging microscopy have revolutionized biomedical research. Ultrafast laser pulses to selectively ablate structures with nanometer precision has found enormous applications, such as 3D micromachining in material processing and structural-knockout in biomedical fields. Live tissue imaging makes it possible to directly study kinetics and biomechanical properties of subcellular structures within their intact microenvironment.
Besides protein patterning by ultrafast laser irradiation, two projects are discussed in details to demonstrate the efficacy and value of ultrafast laser microsurgery in selectively ablating intracellular structures. One project is to study bio-mechanistic oscillatory movements of mitotic chromosomes (known as “directional instability”), in which sections of a chromosome’s arms were removed by femtosecond laser microsurgery thus decreasing the polar-ejection force on the chromosome. The second project is to investigate study the role of ASC protein aggregation during apoptosis by their structural knockouts, which is complimentary to genetic knockout method.
In many tissue types, stem cells reside inside their microenvironment and divide asymmetrically, i.e, one daughter cell self-renews and the other daughter cell differentiates. Using male Drosophila gonad as a model system, 3D live tissue imaging microscopy was developed to directly study the kinetics and biomechanics of subcellular structures during asymmetric stem cell divisions. The results show that aged germ stem cells uniquely re-orient their centrosomes before undergoing asymmetric stem cell divisions, and cyst stem cells adopt the distinctive spindle repositioning mechanism to achieve asymmetric stem cell divisions.
Biography
Dr. Jun Cheng, male, received his B.S. degree in Physics from Peking University, Beijing, China in 1999, M.S. degree in Electrical Engineering in 2002 and Ph.D. degree in Physics in 2006 from University of Michigan, Ann Arbor. Then he joined in Dr. Hunt's lab in the Department of Biomedical Engineering and Dr. Yamashita's lab in Life Sciences Institute at University of Michigan as post-doctoral research fellow. After four years postdoctoral training, he is currently an assistant professor in the Department of Bioengineering, University of Illinois at Chicago. As the Director of Laboratory for Live-cell Imaging and Ultrafast laser Microsurgery, Dr. Cheng’s current research interests include developing novel live tissue imaging microscopy and applying ultrafast laser microsurgery in various biomedical fields, particularly studying stem cell regulations in their native micro-environment.
