Yonnie Wu

Detection of phospholipid-carbon nanotube translocation using fluorescence energy transfer

Single-walled carbon nanotubes (SWNTs) and lysophospholipids readily assemble into supramolecular complexes in aqueous solutions. Upon light excitation the fluorescence of rhodamine-labeled lysophospholipids was redshifted and quenched due to the optical absorption of the SWNTs. Utilizing fluorescence energy transfer, the authors detected the translocation and disassembly of SWNT complexes in MCF breast cancer cells. These lipid-coated SWNT complexes enable drugs to be delivered at an effective dose and their subsequent release to be monitored in real time.

Straw blood cell count, growth, inhibition and comparison to apoptotic bodies

BackgroundMammalian cells transform into individual tubular straw cells naturally in tissues and in response to desiccation related stress in vitro. The transformation event is characterized by a dramatic cellular deformation process which includes: condensation of certain cellular materials into a much smaller tubular structure, synthesis of a tubular wall and growth of filamentous extensions. This study continues the characterization of straw cells in blood, as well as the mechanisms of tubular transformation in response to stress; with specific emphasis placed on investigating whether tubular transformation shares the same signaling pathway as apoptosis.ResultsThere are approximately 100 billion, unconventional, tubular straw cells in human blood at any given time. The straw blood cell count (SBC) is 45 million/ml, which accounts for 6.9% of the bloods dry weight. Straw cells originating from the lungs, liver and lymphocytes have varying nodules, hairiness and dimensions. Lipid profiling reveals severe disruption of the plasma membrane in CACO cells during transformation. The growth rates for the elongation of filaments and enlargement of rabbit straw cells is 0.6~1.1 (μm/hr) and 3.8 (μm3/hr), respectively. Studies using apoptosis inhibitors and a tubular transformation inhibitor in CACO2 cells and in mice suggested apoptosis produced apoptotic bodies are mediated differently than tubular transformation produced straw cells. A single dose of 0.01 mg/kg/day of p38 MAPK inhibitor in wild type mice results in a 30% reduction in the SBC. In 9 domestic animals SBC appears to correlate inversely with an animals average lifespan (R2 = 0.7).ConclusionStraw cells are observed residing in the mammalian blood with large quantities. Production of SBC appears to be constant for a given animal and may involve a stress-inducible protein kinase (P38 MAPK). Tubular transformation is a programmed cell survival process that diverges from apoptosis. SBCs may be an important indicator of intrinsic aging-related stress.

Analysis of proteins involved in programmed cell death in Hemerocallis petals

Discovery of characteristic proteins expressed by a given cell type and how these proteins change during development or pathology, has only been feasible very recently. Powerful separation techniques coupled with the sensitivity and selectivity of mass spectrometry, are used to identify these proteins. Computer-based, bioinformatics techniques are used to match unique peptides to the genome. We recently received a Major Research Instrumentation award from the National Science Foundation (USA) to obtain new state-of-the-art protein analysis equipment. Specifically, we have acquired a research grade hybrid quadrapole ESI-MS/MS mass spectrometer interfaced with a capillary liquid chromatograph (cap-LC). This system (Micromass V-QTM) is a sensitive (femtomole), high resolution, time of flight mass spectrometer (Tof) with electrospray ionization (ESI) sample introduction interface for the capLC. Tandem quadrapole mass spectrometric capabilities and high resolution permits the determination of amino acid sequence of peptides. Software associated with the spectrometer is used to unsort multiple charged versions of the same peptides and proteins, drive the LC separations, and handle other, expected complications in data analysis. As part of this proposal, we received funds to develop an education and outreach module for educators. The proposed module involves proteomics-based experiments conducted for the study of cell death in plants. The daylily flower (Hemerocallis spp.) provides an ideal model system for the study of non-stress related programmed cell death in plants. The entire genetic program/cascade occurs over a compact 24-h period and can be studied in a series of specific sequential steps. We are currently analyzing changes in the daylily petal proteome during the various stages of cell death begining at 12 h prior to flower opening and ending at the final stages of cell death 12 h after opening. A shotgun proteomics approach is currently being utilized. Data derived from this study will not only provide valuable insight in programmed cell death in plants, but also be used to teach proteomics and the study of biological processes to educators involved in biological instruction.