During development, how do embryos distinguish their posterior (tail) versus anterior (head)? Dr. Geraldine Seydoux’s lab uses the small worm C.elegans as a simple model to study this question. In her first video, she introduces how the sperm divides the egg into distinct anterior and posterior domains shortly after fertilization to create the body axis. Her lab… Continue Reading
iBiology Podcasts
Randy Schekman Part 3: How Human Cells Secrete Small RNAs in Extracellular Vesicles
Schekman outlines exosome biogenesis. Exosomes are extracellular vesicles released by the cell, and in contrast to intracellular vesicles, exosomes contain small molecules of RNA. Schekman’s laboratory characterized the RNAs contained in exosomes and showed the importance of Ybx1 protein for the recruitment of certain miRNAs into exosomes. Continue Reading
John Schiller Part 2: Why Do HPV Virus-Like Particle Vaccines Work So Well?
Schiller discusses the high efficacy of HPV vaccine, which is exceptionally good at producing neutralizing antibodies and also benefits from the low mutation rate of HPV. Coming to a better understanding of the efficacy of the HPV vaccine will provide evidence to support single-dose vaccination and aids in the development of new vaccines. Continue Reading
John Schiller Part 1: Human Papillomavirus (HPV) Vaccines to Prevent Cancer
Human Papillomavirus (HPV) causes 5% of all cancers worldwide, and the first vaccine against HPV was approved in 2006. In this seminar, Dr. John Schiller provides an overview of HPV virus and infection, compares the three FDA approved vaccines against HPV, and explains the endpoints used in the clinical trials to prove vaccine efficacy. After… Continue Reading
Randy Schekman Part 1: The Secretory Pathway: How Cells Package and Traffic Proteins for Export
Dr. Randy Schekman overviews the secretory pathway and reviews historical experiments that shaped our molecular understanding of this pathway. The journey begins at the endoplasmic reticulum (ER), where proteins that engage the secretory pathway get translated. The mRNA of these proteins codes for a signal sequence that serves as a “tag” to bring the mRNA-ribosome-newly-synthesized… Continue Reading
Randy Schekman Part 2: Genes and Proteins Required for Secretion
Schekman explains how his laboratory used baker’s yeast to uncover major proteins involved in the secretory pathway, and describes proteins involved in budding, vesicle trafficking, and vesicle fusion. Schekman also presents data from his laboratory that helped to identify the ER channel through which proteins enter the secretory pathway. These series of experiments show how,… Continue Reading
Lalita Ramakrishnan Part 3: Tuberculosis as an Inflammatory Disease
Ramakrishnan’s laboratory has studied the molecular pathogenesis of TB using the power of forward genetics in the zebrafish. They discovered that mutations in LTA4H, a key enzyme in the eicosanoid pathway that alters the levels of the cytokine tumor necrosis factor (TNF), affect tuberculosis pathogenesis by regulating the inflammatory response. This work showed that a… Continue Reading
Lalita Ramakrishnan Part 1: An Introduction to Tuberculosis: The Pathogenic Personality of the Tubercle Bacillus
In this seminar, Dr. Lalita Ramakrishnan gives an introduction to tuberculosis (TB) pathogenesis, and gives an overview of Mycobacterium tuberculosis’ life cycle. She explains how the TB bacteria gain entry into the host by using specific lipids to avoid microbicidal macrophages and recruit growth-permissive ones. Once inside the macrophage, the bacteria use multiple virulence genes… Continue Reading
Lalita Ramakrishnan Part 2: The Troublesome Tubercle in Tuberculosis
After the TB bacteria infect macrophages, a complex structure called a granuloma develops. Different immune cells arrive at the granuloma to surround the bacterial infection and fight the disease. In her second lecture, Ramakrishnan explains how her laboratory used a zebrafish model of TB to study the involvement of granulomas in TB progression. Although granulomas… Continue Reading
Anne Pringle Part 2: Reverse Ecology: A Tool to Understand the Natural Histories of Cryptic Organisms, Including Amanita Phalloides
Pringle explains how one can use a “reverse ecology” approach to describe and characterize different organisms and their habitats, by studying their genes. Her laboratory used this approach to study the origins of the Bay Area Amanita phalloides. Although Amanita phalloides was thought to be an invasive species, historical records were mostly descriptive and hard to use as… Continue Reading
Anne Pringle Part 3: Convergent Interactions and the Genome Architectures of Symbiotic Fungi
Pringle provides an overview of convergent interactions, defined as the independent emergence of multi-species interactions with similar physiological or ecological functions. For example, multiple plant lineages have independently evolved interactions with fungi in order to exchange resources and form what are known as mycorrhizal symbioses. To further understand how convergent interactions are formed, the Pringle… Continue Reading
Anne Pringle Part 1: Introduction to Fungi
Although people usually relate fungi with diseases, Dr. Anne Pringle provides an overview of the vastly diverse and complex world of fungi, and provides examples of the beneficial roles that fungi have on Earth. For example, although some fungi have been associated with devastating infections that threaten harvests every year, other fungi are mutualists needed… Continue Reading
Aaron Pomerantz: Decoding Butterfly Color
How is butterfly color created? In this lecture, Aaron Pomerantz takes us on a journey through the Amazon rainforest, where interesting observations about butterfly color and patterns lead him to use imaging and genetics to decode butterfly color. This talk is part of the Young Scientist Seminars, a video series produced that features young scientists giving… Continue Reading
Hidde Ploegh Part 2: Unusual Antibody Fragments: The Camelid Nanobodies
Ploegh describes how his lab takes advantage of the unique properties of antibodies from the Camelidae family (alpacas, llamas, camels, etc). In addition to traditional antibodies, these animals naturally make small, heavy-chain only antibodies (nanobodies). These molecules can be isolated, amplified in bacteria, and engineered for new applications. As well as using nanobodies to target… Continue Reading
Hidde Ploegh Part 1: Immunology: The Basics of Antibody Diversity
How does our immune system protect us against all of the infectious agents and foreign substances we encounter? Much of the answer lies in antibody diversity. In his first talk, Dr. Hidde Ploegh explains how B cells shuffle their genetic material such that regions of the immunoglobulin protein are rearranged. This generates the antibody diversity… Continue Reading
Helen Piwnica-Worms Part 1: Frogs, Clams, Yeast & Human Cancer: Historical Perspective on Cell Cycle Regulation
Dr. Helen Piwnica-Worms provides a historical perspective on cell cycle regulation and outlines important experiments in frogs, clams, and yeast that revealed crucial mediators of the cell cycle. Scientists observed that there were factors that allowed cell cycle progression, while there were other factors that prevented the cell from going backward. Using these model organisms,… Continue Reading
Helen Piwnica-Worms Part 2: Translating Fundamental Cell Cycle Principles to Targeted Cancer Therapies
Piwnica-Worms explains how scientists have used their understanding of the cell cycle regulation to generate targeted cancer therapies. The cell has proteins that serve as cell cycle checkpoints, which allows the cell to respond appropriately to DNA damage. Although not all of the checkpoints are functional in a cancer cell, these cells still need the… Continue Reading
Shiv Pillai Part 1: Early B Cell Development: A Look at the Defining Questions in Immunology
Dr. Shiv Pillai provides a historical perspective on the current model of how the immune system works. Scientists observed that the body produces molecules (antibodies) that recognize the entry of foreign particles (antigens). He outlines the different models of the structure and functions of antibodies and explains the process by which antibody diversity is generated… Continue Reading
Shiv Pillai Part 2: Bruton Tyrosine Kinase Signaling: The pre-B Cell Receptor and B Cell Differentiation
Pillai explains how earlier in his career he discovered that two surrogate light chains bind to the heavy chain in pre-B cells to create the pre-B cell receptor (pre-BCR). He showed that binding of the surrogate chains facilitates the formation of the pre-BCR that is needed for B cell development. Pillai demonstrated that the pre-BCR… Continue Reading
Shiv Pillai Part 3: IgG4-Related Disease: Collaboration Between B and T Cells
Pillai explains IgG4-Related Disease (IgG4-RD), a chronic inflammatory condition characterized by elevated numbers of T cells and IgG4 secreting plasma cells in the affected tissue. Using tissue samples from patients with the disease, his laboratory isolated and characterized the CD4+ T cells associated with IgG4-RD. Furthermore, he explains how the crosstalk between these CD4+ T… Continue Reading
Dipti Nayak: Archaea and the Tree of Life
Before 1977, all life on Earth was classified into two groups: single-celled microorganisms and complex cellular life such as fungi, plants, and animals. A seminal discovery in 1977 rewrote the tree of life and introduced a whole new domain of organisms known as the archaea – mysterious microbes that are genetically distinct from bacteria. Fast… Continue Reading
Manuel Leonetti: Functional Genomics: Systematic Approaches for Mapping the Cell
What if we could understand the human cell in such detail that we could paint an accurate representation of a cell’s molecular organization? In this lecture, Dr. Manuel Leonetti outlines the different genome-wide approaches that scientists are using to build a complete map of the human cellular architecture. Understanding protein networks and localization could aid… Continue Reading
Ruslan Medzhitov Part 1: Introduction to Inflammation
Dr. Ruslan Medzhitov provides an overview of the field of inflammation and outlines its role in pathology and homeostasis. Medzhitov explains how Inflammation is generated when pathogens, allergens, or other perturbations are recognized by sensor cells that then release inflammatory mediators (cytokines and chemokines) to activate effector cells. Inflammation is then followed by a resolution… Continue Reading
Ruslan Medzhitov Part 2: Inflammation and Disease Tolerance: Surviving Acute Illness
Why do we experience fatigue and loss of appetite, as well as other symptoms when we get ill? Sometimes what we associate with a pathogenic response and illness is the effect of inflammation. In his second talk, Medzhitov outlines the symptoms that we often feel when we get sick, like the lack of appetite (anorexia),… Continue Reading