化学糖生物学 - Carolyn Bertozzi P1
本视频由科普中国和生物医学大讲堂出品
Carolyn Bertozzi (UC Berkeley) Part 1: Chemical Glycobiology
Part 1 A large part of an organism's complexity is not encoded by its genome but results from post-translational modification. Glycosylation, or the addition of sugar molecules to a protein is an example of such a modification. These sugars, or glycans, are often complex, branched molecules specific to particular cells. Cell surface glycans determine human blood types, allow viral infections and play a key role in tissue inflammation. See more at http://www.ibioseminars.org
端粒和端粒酶的作用 - Elizabeth Blackburn P1
本视频由科普中国和生物医学大讲堂出品
Elizabeth Blackburn (UCSF) Part 1: The Roles of Telomeres and Telomerase
Lecture Overview
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.
头足纲动物的伪装和信号 - Roger Hanlon P1
本视频由科普中国和生物医学大讲堂出品
Roger Hanlon (MBL) Part 1: Camouflage and Signaling in Cephalopods
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.
病毒结构的一般原则 - Stephen Harrison P1
本视频由科普中国和生物医学大讲堂出品
Stephen Harrison (Harvard) Part 1: Virus structures: General principles
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.
控制声乐学习行为的大脑通路 - Erich Jarvis P1
本视频由科普中国和生物医学大讲堂出品
Erich Jarvis (Duke/HHMI) Part 1: Convergent behavior and brain pathways
In Part 1, Jarvis explains that vocal learning is the ability to hear a sound and repeat it. Only 5 groups of mammals (including humans) and 3 groups of birds (parrots, hummingbirds and songbirds) are capable of vocal learning. Jarvis and his lab members imaged changes in gene expression in bird's brains after singing. They found that hummingbirds, songbirds and parrots each have pathways in specific areas of the brain that are not found in non-vocal learning birds. Interestingly, analogous networks exist in the human brain but not in non-vocal learning monkeys.
In Part 2, Jarvis proposes a mechanism by which vocal learning may have evolved. He suggests that the brain areas that control vocal learning are the result of a duplication of a pre-existing neural circuit that controls motor movement. A similar duplication event may have occurred during the evolution of humans with the result that both humans and Snowball, a cockatoo, can sing and dance to a beat!
In Jarvis' third talk, he demonstrates that the brain pathways necessary for vocal learning are associated with the expression of particular axonal guidance genes. He also proposes that the evolutionary events responsible for the development of vocal learning may be a general mechanism for the development of other complex behavioral traits.
控制老化的基因 - Cynthia Kenyon P1
本视频由科普中国和生物医学大讲堂出品
Cynthia Kenyon (UCSF) Part 1: Genes that Control Aging
Once it was thought that aging was just a random and haphazard process. Instead, the rate of aging turns out to be subject to regulation by transcription factors that respond to hormones and other signals. In the nematode C. elegans, in which many key discoveries about aging were first made, the aging process is subject to regulation by food intake, sensory perception, and signals from the reproductive system. Changing genes and cells that affect aging can lengthen lifespan by six fold, and can also delay age-related disease, such as the growth of tumors.
枯草芽孢杆菌中芽孢的形成 - Richard Losick P1
本视频由科普中国和生物医学大讲堂出品
Richard Losick (Harvard) Part 1: Spore Formation in Bacillus Subtilis
How do simple cells differentiate, assemble into communities, and cope with change? Losick's seminar addresses these questions in the spore-forming bacterium Bacillus subtilis. Part I is an overview of how B. subtilis makes a spore.
在染色体分离中有关长度和数量的问题 - Richard McIntosh P1
本视频由科普中国和生物医学大讲堂出品
Richard McIntosh (U. Colorado, Boulder) Part 1: Separating Duplicated Chromosomes
The goal of these three talks is to define the problems that a cell faces as it prepares for division and to describe some of the ways it solves them. In Part 1, both the length and amount of DNA are presented as problems for chromosome segregation, particularly in eukaryotic cells. The actions of cohesins and of chromosome condensation are described as solutions. The mitotic machinery is introduced, including its diversity of form across phylogeny, however, the features that appear to be conserved are emphasized. This lecture may be useful for upper level undergraduate and graduate courses discussing mitosis and cell division. See more at www.ibioseminars.org
免疫反应的细胞基础 - Ira Mellman P1
本视频由科普中国和生物医学大讲堂出品
Ira Mellman (Genentech) Part 1: Cellular Basis of the Immune Response
The immune system is charged with protecting us from invading microorganisms, a task that falls to a complex array of highly specialized cell types spread throughout the body but that must work together as an integrated system. How they accomplish and perform their functions can be wonderfully understood by probing the basic mechanisms governing their activities. In the first video, we will consider the overall organization of the immune response in cellular terms, the innate immune system (comprising evolutionarily ancient phagocytic cells that recognize conserved molecules of microorganisms) and the adaptive immune system (composed of lymphocytes that recognize chemically diverse antigens).