入侵细胞和在细胞内生存的策略 - Norma Andrews P3
本视频由科普中国和生物医学大讲堂出品
Norma Andrews (U. Maryland) Part 3: Strategies for Cell Invasion and Intracellular Survival
In the third part of this lecture, I will discuss current work from our laboratory on mechanisms used by the intracellular parasites Trypanosoma cruzi and Leishmania to interact with mammalian cells. In addition to clarifying specific molecular strategies used by these parasites to infect and survive within host cells, these studies also led, in some instances, to unexpected insights on novel pathways regulating mammalian cell function.
Norma Andrews moved from Yale University to the University of Maryland in 2010.
细胞粘附、信号和癌症 - Mary Beckerle P1
本视频由科普中国和生物医学大讲堂出品
Mary Beckerle (University of Utah) Part 1: Adhesion, Signaling and Cancer
Cell-substratum adhesion is mediated by integrins, a family of transmembrane, heterodimeric, extracellular matrix receptors that are concentrated at focal adhesions. Integin engagement influences a variety of signaling pathways and regulates cell behaviors including motility, proliferation, and survival. Disturbance of normal integrin function is associated with a variety of pathologic conditions including cancer. In the first segment of my seminar, I provide a broad overview of the cancer problem for a lay audience. Advances in our understanding of cancer as a genetic disease are discussed. The influence of cell adhesion on control of cell growth is reviewed. See more at http://www.ibiology.org
端粒和端粒酶在人类干细胞和癌症中的作用 - Elizabeth Blackburn P2
本视频由科普中国和生物医学大讲堂出品
Elizabeth Blackburn (UCSF) Part 2: Telomeres and Telomerase in Human Stem Cells and in Cancer
Telomerase, a specialized ribonucleprotein reverse transcriptase, is important for long-term eukaryotic cell proliferation and genomic stability, because it replenishes the DNA at telomeres. Thus depending on cell type telomerase partially or completely (depending on cell type) counteracts the progressive shortening of telomeres that otherwise occurs. Telomerase is highly active in many human malignancies, and a potential target for anti-cancer approaches. Furthermore, recent collaborative studies have shown the relationship between accelerated telomere shortening and life stress and that low telomerase levels are associated with six prominent risk factors for cardiovascular disease.
头足纲动物的可变化的皮肤细胞 - Roger Hanlon P3
本视频由科普中国和生物医学大讲堂出品
Roger Hanlon (MBL) Part 3: Changeable Skin
Hanlon introduces the amazing adaptive coloration of cephalopods. He uses video and still photography to showcase their ability to rapidly change color, pattern and skin texture with fine control and a diversity of appearances, to produce camouflage or to send signals. He argues that all camouflage patterns in nature can be grouped into three types. In part 2, Hanlon shows us results from his lab that make a convincing case that the rapid adaptive coloration of cephalopods is controlled by their visual system; quite impressive for a color-blind animal! Part 3 focuses on the unique skin of cephalopods including the system of pigments and reflectors that allows it to quickly change to any hue and contrast, and the papillae musculature that allows the skin to deform and create multiple 3D textures.
非包膜病毒如何侵入细胞 - Stephen Harrison P3
本视频由科普中国和生物医学大讲堂出品
Stephen Harrison (Harvard) Part 3: Non-enveloped virus entry
Harrison begins his talk by asking why most non-enveloped viruses and some enveloped viruses are symmetrical in shape. He proceeds to show us lovely images of the structures obtained by x-ray crystallography of numerous viral coat proteins. Deciphering these structures allowed scientists to understand that viral coat proteins form multimers, such as dimers and pentamers, which in turn interact with a scaffold that ensures that the coat proteins are correctly placed. This arrangement results in symmetrically shaped viruses.
In Part 1, Harrison also explains that enveloped viruses infect cells by inducing the fusion of the viral and host cell membranes. He delves deeper into the molecular mechanism of membrane fusion driven by the hemagglutinin or HA protein of the influenza virus in Part 2 of his talk.
Non-enveloped viruses, on the other hand, must enter cells by a mechanism other than membrane fusion. This is the focus of Part 3. Using rotavirus as a model, Harrison and his colleagues have used a combination of Xray crystallography and electron cryomicroscopy to decipher how the spike protein on the viral surface changes its conformation and perforates the cell membrane allowing the virus to enter the cell.
病毒与宿主细胞表面结合的方式 - Ari Helenius P1
本视频由科普中国和生物医学大讲堂出品
Ari Helenius (ETH Zurich) Part 1: Virus entry
Viruses are extremely simple and small yet they are responsible for many of the worlds diseases. A virus particle consists of only a genome, a protein coat or capsid, and sometimes a surrounding lipid envelope. To replicate, a virus must successfully enter a host cell, uncoat its genome, and appropriate the host cell machinery to replicate its genome and produce viral proteins. Part 1 of this lecture will discuss ways in which viruses bind to the surface of host cells. Simian Virus 40 which binds to specific cell surface glycolipids, and Human Papilloma Virus-16 which binds to sites on filoipodia, are examples of different binding mechanisms. Attachment of viruses to the plasma membrane activates cell signaling resulting in endocytosis of the viral particles. This lecture is appropriate for upper level undergraduate and graduate classes studying virology or endocytosis.
牛痘病毒如何进入细胞 - Ari Helenius P3
本视频由科普中国和生物医学大讲堂出品
Ari Helenius (ETH Zurich) Part 3: Open Sesame: Cell Entry and Vaccinia Virus
Part 3 focuses on a single virus, the Vaccinia virus, as a model for cell binding, signaling and endocytosis. Fluorescently labeled Vaccinia viruses bind to and surf along host cell filopodia. Helenius lab members noticed that when Vaccinia, unlike other viruses, reached the surface of the cell body it caused the plasma membrane to form blebs. Further experiments showed that the virus tricks the cell into thinking it is apoptotic debris. This induces blebbing and subsequent uptake of the virus by macropinocytosis. Additionally, automated high throughput siRNA screening was used to screen a large number of infected cells for host genes required for Vaccinia virus uptake. Analysis of the genes identified allowed host factors and processes critical to viral infection to be identified. Expansion of this technique may provide a new source of information on pathogen-host interactions.